Total documents retrieved: 62 en AM TI - Contracted coordinations without deletions - The structure of contracted word groups [Dutch] SO - Tijdschrift voor Nederlandse Taal-En Letterkunde 2000;116(1):23-48 IS - 0040-7550 AB - It is generally assumed that in contracted co-ordinations such as 'big and small trees', an element is deleted. In this article it is argued that what seems to be 'co-ordination reduction' is actually the result of reanalysis. Originally autonomous word classes, like the declined adjective and the finite verb, became dependent on a noun and a subject. In phrases consisting of one head and two specifying elements, or two heads and one specifier, that dependency causes a discontinuous structure: the firs element is connected to the last, and one of these is also linked with the second element. This asymmetry suggests a gap, but no word has been omitted. contraction of compounds is also the result of reinterpretation. Compounds with two co-ordinated specifiers or heads, indicating two subcategories of one set, can be understood to be two complementary sets: [a + b] c or a [b + c] => a(c) + bc and ab + (a)c. Among the three elements the same complex structure applies as described above. [References: 35] LG - Dutch PT - Article SB - Current Contents(R)/Arts & Humanities 2 UI - 324UH-0001 AU - Gano KW AU - Myles DC TI - Progress toward the synthesis of a biomimetic membrane SO - Tetrahedron Letters 2000 Jun 8;41(22):4247-4250 IS - 0040-4039 MH - Antioxidant MH - Reagents AB - Ubiquinone has antioxidant properties and is important in the conversion of products from glycolysis and the citric acid cycle to ATP. We report the synthesis of the necessary components of a biological membrane mimic that can serve as a model system for elucidating the third step in the prokaryotic biosynthesis of ubiquinone. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 23] LG - English PT - Article SB - Current Contents(R)/Life Sciences Current Contents(R)/Physical, Chemical & Earth Sciences IN - Myles DC Chiron Corp, Organ & Med Chem 5300 Chiron Way,Mail Stop 4-5 Emeryville, CA 94608 USA Univ Calif Los Angeles, Dept Chem & Biochem Los Angeles, CA 90095 USA 3 UI - 325FX-0018 AU - Iuchi S AU - Kobayashi M AU - Yamaguchi-Shinozaki K AU - Shinozaki K TI - A stress-inducible gene for 9-cis-epoxycarotenoid dioxygenase involved in abscisic acid biosynthesis under water stress in drought-tolerant cowpea SO - Plant Physiology 2000 Jun;123(2):553-562 IS - 0032-0889 MH - Zeaxanthin epoxidase MH - Arabidopsis-thaliana MH - Expression MH - Identification MH - Carotenoids MH - Library MH - Cloning MH - Plants MH - Leaves MH - Cdnas AB - Four cDNA clones named CPRD (cowpea responsive to dehydration) corresponding to genes that are responsive to dehydration were isolated using differential screening of a cDNA library prepared from 10-h dehydrated drought-tolerant cowpea (Vigna unguiculata) plants. One of the cDNA clones has a homology to 9-cis-epoxpcarotenoid dioxygenase (named VuNCED1), which is supposed to be involved in abscisic acid (ABA) biosynthesis.:The GST (glutathione S-transferase)-fused protein indicates a 9-cis-epoxycarotenoid dioxygenase activity, which catalyzes the cleavage of 9-cis-epoxycarotenoid. The N-terminal region of the VuNCED1 protein directed the fused sGFP (synthetic green-fluorescent protein) into the plastids of the protoplasts, indicating that the N-terminal sequence acts as a transit peptide. Both the accumulation of ABA and expression of VuNCED1 were strongly induced by drought stress in the 8-d-old cowpea plant, whereas drought stress did not trigger the expression of VuABA1 (accession no. AB030295) gene that encodes zeaxanthin epoxidase. These results indicate that the VuNCED1 cDNA encodes a 9-cis-epoxycarotenoid dioxygenase and that its product has a key role in the synthesis of ABA under drought stress. [References: 26] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Shinozaki K RIKEN, Isukuba Inst, Plant Mol Biol Lab 3-1-1 Koyadai Tsukuba Ibaraki 3050074 Japan RIKEN, Isukuba Inst, Plant Mol Biol Lab Tsukuba Ibaraki 3050074 Japan Minist Agr Forestry & Fisheries, Japan Int Res Ctr Agr Sci, Biol Resources Div Tsukuba Ibaraki 3050851 Japan 4 UI - 325FX-0020 AU - Miller AG AU - Hunter KJ AU - O'Leary SJB AU - Hart LJ TI - The photoreduction of H2O2 by Synechococcus sp PCC 7942 and UTEX 625 SO - Plant Physiology 2000 Jun;123(2):625-635 IS - 0032-0889 MH - Air-grown cells MH - Cyanobacterium anacystis-nidulans MH - Chlorophyll-a fluorescence MH - Hydrogen-peroxide MH - Inorganic carbon MH - O-2 photoreduction MH - Catalase-peroxidase MH - Ascorbate peroxidase MH - Active-transport MH - Electron flow AB - It has been claimed that the sole H2O2-scavenging system in the cyanobacterium Synechococcus sp. PCC 7942 is a cytosolic catalase-peroxidase. We have measured in vivo activity of a light-dependent peroxidase in Synechococcus sp. PCC 7942 and UTEX 625. The addition of small amounts of H2O2 (2.5 mu M) to illuminated cells caused photochemical quenching (qP) of chlorophyll fluorescence that was relieved as the H2O2 was consumed. The qP was maximal at about 50 mu M H2O2 With a Michaelis constant of about 7 mu M. The H2O2-dependent qP strongly indicates that photoreduction can be involved in H2O2 decomposition. Catalase-peroxidase activity was found to be almost completely inhibited by 10 mu M NH2OH with no inhibition of the H2O2-dependent qP, which actually increased, presumably due to the light-dependent reaction now being the only route for H2O2-decomposition. When O-18-labeled H2O2 was presented to cells in the light there was an evolution of O-16(2), indicative of (H2O)-O-16 oxidation by PS 2 and formation of photoreductant. In the dark O-18(2) was evolved from added (H2O2)-O-18 as expected for decomposition by the catalase-peroxidase. This evolution was completely blocked by NH2OH, whereas the light-dependent evolution of O-16(2) during (H2O2)-O-18 decomposition was unaffected. [References: 44] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Miller AG St Francis Xavier Univ, Dept Biol Antigonish NS B2G 2W5 Canada St Francis Xavier Univ, Dept Biol Antigonish NS B2G 2W5 Canada 5 UI - 325AE-0015 AU - Miskiewicz E AU - Ivanov AG AU - Williams JP AU - Khan MU AU - Falk S AU - Huner NPA TI - Photosynthetic acclimation of the filamentous cyanobacterium, Plectonema boryanum UTEX 485, to temperature and light SO - Plant & Cell Physiology 2000 Jun;41(6):767-775 IS - 0032-0781 MH - Acclimation MH - Electron transport MH - Irradiance MH - Photoinhibition MH - Plectonema boryanum MH - Temperature MH - Ii excitation pressure MH - Harvesting complex-ii MH - Photosystem-ii MH - Synechocystis pcc-6714 MH - Redox state MH - Chlorella-vulgaris MH - Induced accumulation MH - Gene-transcription MH - Growth irradiance MH - Dunaliella-salina AB - Photosynthetic acclimation to temperature and irradiance was studied in the filamentous, non-heterocystous cyanobacterium Plectonema boryanum UTEX 485. Growth rates of this cyanobacterium measured at ambient CO2 were primarily influenced by temperature with minimal effects of irradiance, Both growth temperature and irradiance affected linolenic (18:3) and linoleic acid (18:2) levels in the four major lipid classes in an independent but additive manner. In contrast, photosynthetic acclimation was not due to either growth temperature or irradiance per se, but rather, due to the interaction of these environmental factors. P. boryanum grown at low temperature and moderate irradiance mimicked cells grown at high light. Compared to cells grown at either 29 degrees C/150 mu mol m(-2) s(-1) (29/150) or 15/10, P. boryanum grown at either15/150 or 29/750 exhibited: (1) reduced cellular levels of Chi a and phycobilisomes (PBS), and concomitantly higher content of an orange-red carotenoid, myxoxanthophyll; (2) higher light saturated rates (Pmax) when expressed on a Ch1 a basis but lower apparent quantum yields of oxygen evolution and (3) enhanced resistance to high light stress. P. boryanum grown at 15/150 regained normal blue-green pigmentation within 16 h after a temperature shift to 29 degrees C at a constant irradiance of 150 mu mol m(-2) s(-1). DBMIB and KCN but not DCMU and atrazine partially inhibited the change in myxoxanthophyll/Ch1 a ratio following the shift from 15 to 29 degrees C, We conclude that P. boryanum responds to either varying growth temperature or varying growth irradiance by adjusting the ability to absorb light through decreasing the cellular contents of Ch1 a and light-haFvesting pigments and screening of excessive light by myxoxanthophyll predominantly localized in the cell wall/cell membrane to protect PSII from over-excitation. The possible role of redox sensing/signalling for photosynthetic acclimation of cyanobacteria to either temperature or irradiance is discussed. [References: 45] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Huner NPA Univ Western Ontario, Dept Plant Sci London ON N6A 5B7 Canada Univ Western Ontario, Dept Plant Sci London ON N6A 5B7 Canada Univ Toronto, Dept Bot Toronto ON M5S 3B2 Canada Mid Sweden Univ, Dept Ekotekn Ostersund Sweden 6 UI - 324BL-0002 AU - Heraud P AU - Beardall J TI - Changes in chlorophyll fluorescence during exposure of Dunaliella tertiolecta to UV radiation indicate a dynamic interaction between damage and repair processes SO - Photosynthesis Research 2000;63(2):123-134 IS - 0166-8595 MH - Dunaliella tertiolecta MH - Fluorescence MH - Microalgae MH - Psii MH - Uvr MH - Ultraviolet-b radiation MH - Ii electron-transport MH - Photosystem-ii MH - Phytoplankton photosynthesis MH - Quantum yield MH - Photoinhibition MH - Irradiance MH - Inhibition AB - Photosynthesis in the green alga Dunaliella tertiolecta, as measured by chlorophyll fluorescence, is inhibited by ultraviolet radiation and specifically, under the conditions used, by UVB radiation (UVBR). The decline in the fluorescence parameters F-v/F-m and Delta F/F-m' under constant UVBR is a first-order function of time of exposure. The data are well-described by the Kok (1956) model, which assumes a dynamic interaction between damage and repair, with repair being proportional to the pool size of inactivated targets. The pattern of photoinhibition is also consistent with the Kok model, in that it shows an initial, approximately linear phase which is time-dependent (reciprocity holds), a transition phase and then an asymptotic phase, representing an equilibrium between damage and repair, which is determined by UVBR fluence rate (reciprocity fails). Photoinhibition in the presence of lincomycin, a protein synthesis inhibitor, is consistent with the cessation of repair processes and, under these conditions, photoinhibition is proportional to exposure time. [References: 30] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Beardall J Monash Univ, Dept Biol Sci Clayton Vic 3168 Australia Monash Univ, Dept Biol Sci Clayton Vic 3168 Australia 7 UI - 324BL-0003 AU - Komenda J AU - Koblizek M AU - Prasil O TI - Characterization of processes responsible for the distinct effect of herbicides DCMU and BNT on Photosystem II photoinactivation in cells of the cyanobacterium Synechococcus sp PCC 7942 SO - Photosynthesis Research 2000;63(2):135-144 IS - 0166-8595 MH - D1 protein MH - Photoinhibition MH - Psii inhibitors MH - Synechococcus pcc 7942 MH - Reaction-center protein MH - D1 protein MH - Chlamydomonas-reinhardtii MH - Chloroplast membranes MH - High irradiance MH - Electron flow MH - Acceptor side MH - In-vivo MH - Ps-ii MH - Photoinhibition AB - Light-induced modification of Photosystem II (PS II) complex was characterized in the cyanobacterium Synechococcus sp. PCC 7942 treated with either DCMU (a phenylurea PS II inhibitor) or BNT (a phenolic PS II inhibitor). The irradiance response of photoinactivation of PS II oxygen evolution indicated a BNT-specific photoinhibition that saturated at relatively low intensity of light. This BNT-specific process was slowed down under anaerobiosis, was accompanied by the oxygen-dependent formation of a 39 kDa D1 protein adduct, and was not related to stable Q(A) reduction or the ADRY effect. In the BNT-treated cells, the light-induced, oxygen-independent initial drop of PS II electron flow was not affected by formate, an anion modifying properties of the PS II non-heme iron. For DCMU-treated cells, anaerobiosis did not significantly affect PS II photoinactivation, the D1 adduct was not observed and addition of formate induced similar initial decrease of PS II electron flow as in the BNT-treated cells. Our results indicate that reactive oxygen species (most likely singlet oxygen) and modification of the PS II acceptor side are responsible for the fast BNT-induced photoinactivation of PS II. [References: 41] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Komenda J Acad Sci Czech Republ, Inst Microbiol, Lab Photosynth Trebon 37901 Czech Republic Acad Sci Czech Republ, Inst Microbiol, Lab Photosynth Trebon 37901 Czech Republic 8 UI - 324BL-0004 AU - Exss-Sonne P AU - Tolle J AU - Bader KP AU - Pistorius EK AU - Michel KP TI - The IdiA protein of Synechococcus sp PCC 7942 functions in protecting the acceptor side of Photosystem II under oxidative stress SO - Photosynthesis Research 2000;63(2):145-157 IS - 0166-8595 MH - Cyanobacteria MH - Idia MH - Oxidative stress MH - Photosystem ii MH - Psbo MH - Synechococcus sp. MH - Pcc 7942 and pcc 6301 MH - Amino-acid oxidase MH - Manganese-stabilizing protein MH - Synechocystis sp pcc-6803 MH - Sp strains pcc-6301 MH - Electron-transport MH - Anacystis-nidulans MH - Oxygen evolution MH - Wild-type MH - Cyanobacterium MH - Iron AB - Synechococcus sp. strains PCC 7942 and PCC 6301 contain a 35 kDa protein called IdiA (Iron deficiency induced protein A) that is expressed in elevated amounts under Fe deficiency and to a smaller extent also under Mn deficiency. Absence of this protein was shown to mainly damage Photosystem II. To decide whether IdiA has a function in optimizing and/or protecting preferentially either the donor or acceptor side reaction of Photosystem II, a comparative analysis was performed of Synechococcus sp. PCC 7942 wild-type, the IdiA-free mutant, the previously constructed PsbO-free Synechococcus PCC 7942 mutant and a newly constructed Synechococcus PCC 7942 double mutant lacking both PsbO and IdiA. Measurements of the chlorophyll fluorescence and determinations of Photosystem II activity using a variety of electron acceptors gave evidence that IdiA has its main function in protecting the acceptor side of Photosystem II. Especially, the use of dichlorobenzoquinone, preferentially accepting electrons from Q(A), gave a decreased O-2 evolving activity in the IdiA-free mutant. Investigations of the influence of hydrogen peroxide treatment on cells revealed that this treatment caused a significantly higher damage of Photosystem II in the IdiA-free mutant than in wild-type. These results suggest that although the IdiA protein is not absolutely required for Photosystem II activity in Synechococcus PCC 7942, it does play an important role in protecting the acceptor side against oxidative damage. [References: 52] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Pistorius EK Univ Bielefeld D-33501 Bielefeld Germany Univ Bielefeld D-33501 Bielefeld Germany 9 UI - 324BL-0005 AU - Doege M AU - Ohmann E AU - Tschiersch H TI - Chlorophyll fluorescence quenching in the alga Euglena gracilis SO - Photosynthesis Research 2000;63(2):159-170 IS - 0166-8595 MH - Chlorophyll fluorescence MH - Chlororespiration MH - Euglena MH - Photosynthesis MH - Spill over MH - State transitions MH - Xanthophyll cycle MH - Light-harvesting complexes MH - Photosystem-ii MH - Xanthophyll-cycle MH - Chlamydomonas-reinhardtii MH - Mantoniella-squamata MH - Diadinoxanthin cycle MH - Energy-dissipation MH - State transitions MH - Protein complexes MH - Mutants deficient AB - When far red light preincubated cells of Euglena gracilis are transferred to dark or light, chlorophyll fluorescence (F-0 and F-m) decreases. Non-photochemical quenching in the dark is suggested to be induced partly by chlororespiration and partly by changes in the distribution of excitation energy between the photosystems. Depending on the light intensities it was possible to resolve the non-photochemical quenching into at least three different components. The slowest relaxation phase of non-photochemical quenching occurred only after exposure to high light and was assigned to photoinhibition. The other two components were an energy-dependent quenching (qE), and the one which we attribute to a spill over mechanism. We suggest that both photosystems use a common antenna system consisting of LHC I and LHC II proteins. In contrast to higher plants, qE in Euglena gracilis is independent of the xanthophyll cycle and an aggregation of LHC II. [References: 53] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Tschiersch H Univ Halle Wittenberg, Inst Pflanzen & Zellphysiol Kirchtor 1 D-06108 Halle Germany Univ Halle Wittenberg, Inst Pflanzen & Zellphysiol D-06108 Halle Germany 10 UI - 324BL-0006 AU - Kurreck J AU - Schodel R AU - Renger G TI - Investigation of the plastoquinone pool size and fluorescence quenching in thylakoid membranes and Photosystem II (PS II) membrane fragments SO - Photosynthesis Research 2000;63(2):171-182 IS - 0166-8595 MH - Chlorophyll fluorescence MH - Non-photochemical quenching MH - Photosystem ii MH - Thylakoid membranes MH - Chlorophyll fluorescence MH - Spinach thylakoids MH - Electron-transport MH - P680(+center-dot) reduction MH - Actinic light MH - System-ii MH - Chloroplasts MH - Kinetics MH - Complexes MH - Particles AB - The efficiency of oxidized endogenous plastoquinone-9 (PQ-9) as a non-photochemical quencher of chlorophyll fluorescence has been analyzed in spinach thylakoids and PS II membrane fragments isolated by Triton X-100 fractionation of grana stacks. The following results were obtained: (a) After subjection of PS II membrane fragments to ultrasonic treatment in the presence of PQ-9, the area over the induction curve of chlorophyll fluorescence owing to actinic cw light increases linearly with the PQ-9/PS II ratio in the reconstitution assay medium; (b) the difference of the maximum fluorescence levels, F-max, of the induction curves, measured in the absence and presence of DCMU, is much more pronounced in PS II membrane fragments than in thylakoids; (c) the ratio F-max(-DCMU)/F-max(+DCMU) increases linearly with the content of oxidized PQ-9 that is varied in the thylakoids by reoxidation of the pool after preillumination and in PS II membrane fragments by the PQ-9/PS II ratio in the reconstitution assay; (d) the reconstitution procedure leads to tight binding of PQ-9 to PS II membrane fragments, and PQ-9 cannot be replaced by other quinones; (e) the fluorescence quenching by oxidized PQ-9 persists at low temperatures, and (f) oxidized PQ-9 preferentially affects the F695 of the fluorescence emission spectrum at 77 K. Based on the results of this study the oxidized PQ-9 is inferred to act as a non-photochemical quencher via a static mechanism. Possible implications for the nature of the quenching complex are discussed. [References: 58] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Renger G Tech Univ Berlin, Max Volmer Inst Biophys Chem & Biochem Str 17 Juni 135 D-10623 Berlin Germany Tech Univ Berlin, Max Volmer Inst Biophys Chem & Biochem D-10623 Berlin Germany 11 UI - 326FP-0005 AU - Shikany JM AU - Witte JS TI - Correlations of individual plasma carotenoid concentrations in free-living older adults SO - Nutrition Research 2000 Jul;20(7):955-965 IS - 0271-5317 MH - Beta carotene MH - Carotenoids MH - Diet MH - High pressure liquid chromatography MH - Plasma MH - Performance liquid-chromatography MH - Beta-carotene MH - Serum MH - Vegetables MH - Vitamin MH - Men MH - Micronutrients MH - Antioxidants MH - Consumption MH - Fruits AB - Correlations between the plasma concentrations of six distinct carotenoids were determined in 958 participants in a sigmoidoscopy-based case-control study of nutritional factors and colorectal polyps. Plasma carotenoid concentrations were determined by high-performance liquid chromatography following a 12-hour fast. Spearman rank correlation coefficients (r) were used to assess the relationships between carotenoids. We first looked at the group as a whole and then stratified the data by sex, age, smoking status, and ethnicity to determine whether these variables modified the correlations. Among all subjects, concentrations of alpha-carotene versus beta-carotene (r = 0.73) and lutein versus zeaxanthin (r = 0.64) were most highly correlated, likely reflecting common dietary sources among these pairs of carotenoids. In contrast, lycopene was minimally correlated with the other carotenoids (r = 0.23 to 0.27), probably due to this carotenoid having different dietary sources from the others. There was little effect of age, sex, or smoking status on correlations. Correlations between lycopene and the other carotenoids were substantially lower in Asian subjects. While this may reflect distinct dietary patterns in Asians, it could also be due to differences in carotenoid absorption and metabolism. (C) 2000 Elsevier Science Inc. [References: 20] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Shikany JM Univ Alabama, Div Prevent Med 1717 11th Ave S,Room 737 Birmingham, AL 35203 USA Univ Alabama, Sch Med, Div Prevent Med Birmingham, AL 35294 USA Case Western Reserve Univ, Dept Epidemiol & Biostat Cleveland, OH 44109 USA 12 UI - 325VH-0020 AU - Barocsi A AU - Kocsanyi L AU - Varkonyl S AU - Richter P AU - Csintalan Z AU - Szente K TI - Two-wavelength, multipurpose, truly portable chlorophyll fluorometer and its application in field monitoring of phytoremediation SO - Measurement Science & Technology 2000 Jun;11(6):717-729 IS - 0957-0233 MH - Chlorophyll fluorometer MH - Kautsky kinetics MH - Rfd values MH - Pc/104 form factor MH - Single board computer MH - Stress diagnostics MH - Soil phytoremediation MH - Laser-induced fluorescence MH - Plant xerophyta-scabrida MH - Vegetation canopies MH - Induction kinetics MH - A fluorescence MH - Stress MH - Spectra MH - Leaves MH - System MH - Ratio AB - In this paper a compact, portable instrument is presented for the measurement of full chlorophyll fluorescence kinetics of plants at two different wavelengths. The instrument uses a 635 nm laser diode as a light source with variable gain driving that allows excitations at selectable actinic levels. The plant fluorescence is detected, at 690 nm and 735 nm, through a specially mixed three-branch optical fibre bundle. Large scale field monitoring of vegetation is made possible by the utilization of PC/104-form embedded electronics including a low power, IBM PC/386-compatible single board computer (SBC) with non-volatile flash memory. Application of a general purpose SBC and task oriented programming offers in situ data evaluation making process control possible. The capabilities of the instrument were demonstrated in monitoring soil phytoremediation processes. [References: 32] LG - English PT - Article SB - Current Contents(R)/Physical, Chemical & Earth Sciences Current Contents(R)/Engineering, Computing & Technology IN - Barocsi A Budapest Univ Technol & Econ, Dept Atom Phys Budafoki Ut 8 H-1111 Budapest Hungary Budapest Univ Technol & Econ, Dept Atom Phys H-1111 Budapest Hungary Szent Istvan Univ Godollo, Dept Bot & Plant Physiol, Ecophysiol Res Grp H-2103 Godollo Hungary 13 UI - 324KL-0016 AU - Wiencke C AU - Gomez I AU - Pakker H AU - Flores-Moya A AU - Altamirano M AU - Hanelt D AU - Bischof K AU - Figueroa FL TI - Impact of UV-radiation on viability, photosynthetic characteristics and DNA of brown algal zoospores: implications for depth zonation SO - Marine Ecology-Progress Series 2000;197:217-229 IS - 0171-8630 MH - Macroalgae MH - Laminaria MH - Arctic MH - Zoospores MH - Uv-radiation MH - Dna damage MH - Photosynthesis MH - Laminaria species phaeophyceae MH - Helgoland north-sea MH - Life-history stages MH - Ultraviolet-radiation MH - Chlorophyll fluorescence MH - Solar-radiation MH - B radiation MH - Marine-phytoplankton MH - Sublittoral region MH - Arctic macroalgae AB - Measurements of photosynthesis, germination capacity and assessment of DNA damage were carried out in the laboratory to determine the effect of different conditions of ultraviolet (UV) and photosynthetically active radiation (PAR) on zoospores of various large brown algae collected on Spitsbergen (Svalbard, High Arctic) and Tarifa (Cadiz, southern Spain). Results were correlated to in situ light conditions and indicated that zoospores suffer photoinhibition of photosynthesis, loss of viability and DNA damage in relation to the growth depth of parental sporophytes. At both sites, germination capacity of zoospores in species collected in deep waters was more strongly impaired after exposure to the same UV doses than in species from shallower waters. In general, zoospores exposed to PAR+UVA+UVB showed higher mortality rates than after exposure to PAR+UVA or PAR alone. For Laminaria digitata from Spitsbergen, it was found that the loss of zoospore viability is the result of DNA damage and photodamage of the photosynthetic apparatus. UVB irradiances occurring in southern Spain at water depths shallower than 7 m prevented the germination of spores of deep water Laminariales from this region. [References: 70] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences IN - Wiencke C Fdn Alfred Wegener Inst, Project Grp Solar UV Radiat D-27515 Bremerhaven Germany Fdn Alfred Wegener Inst, Project Grp Solar UV Radiat D-27515 Bremerhaven Germany Univ Groningen, Dept Marine Biol NL-9750 AA Haren Netherlands Univ Malaga, Dept Plant Biol E-29071 Malaga Spain Univ Malaga, Dept Ecol E-29071 Malaga Spain 14 UI - 324PA-0002 AU - Whittington J AU - Sherman B AU - Green D AU - Oliver RL TI - Growth of Ceratium hirundinella in a subtropical Australian reservoir: the role of vertical migration SO - Journal of Plankton Research 2000 Jun;22(6):1025-1045 IS - 0142-7873 MH - Small productive lake MH - Chlorophyll fluorescence MH - Phytoplankton MH - Photosynthesis MH - Constraints MH - Populations MH - Fluorometer MH - Cultures AB - A study into the photophysiology, growth and migration of Ceratium hirundinella in Chaffey Reservoir in subtropical northern New South Wales, Australia, revealed that a proportion of cells formed subsurface accumulations at depths that optimized light intensity (212-552 mu mol photons m(-2) s(-1)) for photosynthesis and cell growth. At high incident irradiance, Ceratium migrated downwards from the near-surface waters, avoiding high-light-induced, slow-recovering non-photochemical quenching of photosystem II. Overnight deepening of the surface mixed layer by convective cooling produced homogeneous distributions of Ceratium with a significant proportion of the population below the depth where light saturation of photosynthesis occurred. Ceratium migrated towards the surface from suboptimal light intensities, at a velocity of 1.6-2.7 x 10(-4) m s(-1). Subsurface accumulations occurred under a variety of turbulence intensities; however, accumulation was significantly reduced when the turbulent velocity scale in the mixed layer was >5 x 10(-3) m s(-1), beyond which turbulent diffusion dominated advection by swimming. The formation of subsurface accumulations with increased computed water column integral photosynthesis by 35% compared to a uniform cell distribution. [References: 28] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences IN - Sherman B CSIRO, Pye Lab Black Mt ACT 2601 Australia CSIRO, Pye Lab Black Mt ACT 2601 Australia Murray Darling Freshwater Res Ctr Albury NSW Australia Cooperat Res Ctr Freshwater Ecol Albury NSW Australia 15 UI - 325CP-0045 AU - Pettus EH AU - Betarbet R AU - Cottrell B AU - Wallace DC AU - Madyastha V AU - Greenamyre JT TI - Immunocytochemical characterization of the mitochondrially encoded ND1 subunit of complex I (NADH : ubiquinone oxidoreductase) in rat brain SO - Journal of Neurochemistry 2000 Jul;75(1):383-392 IS - 0022-3042 MH - Mitochondria MH - Complex i MH - Mitochondrially encoded subunit i of nadh dehydrogenase (complex i) MH - Immunocytochemistry MH - Complex iv MH - Hereditary optic neuropathy MH - Toxin 3-nitropropionic acid MH - Nadh-ubiquinone reductase MH - Electron-transport chain MH - Parkinsons-disease MH - Dihydrorotenone binding MH - Huntingtons-disease MH - Glutamate receptors MH - Neurospora-crassa MH - Dehydrogenase AB - In Parkinson's disease, there is a selective defect in complex I of the electron transfer chain. To better understand complex I and its involvement in neurodegenerative disease, we raised an antibody against a conserved epitope of the human mitochondrially encoded subunit 1 of complex I (ND1). Antibodies were affinity purified and assessed by ELISA, immunoblotting, and immunocytochemistry. Immunoblots of brain homogenates from mouse, rat, and monkey brain showed a single 33-kDa band consistent with the predicted molecular mass of the protein. Subcellular fractionation showed the protein to be enriched in mitochondria, Immunocytochemistry in rat brain revealed punctate labeling in cell bodies and processes of neurons. Immunoreactivity generally co-localized with subunit IV of complex IV. In striatum, ND1 immunoreactivity was greatly enriched in large cholinergic neurons and neurons containing nitric oxide synthase, two cell populations that are resistant to excitotoxic and metabolic insults. In substantia nigra, many dopaminergic neurons had little ND1 immunoreactivity, which may help to explain their sensitivity to complex I inhibitors. In spinal cord, ND1 immunoreactivity was enriched in motor neurons. We conclude that complex I is differentially distributed across brain regions, between neurons and glia, and between types of neurons. This antibody should provide a valuable tool for assessing complex I in normal and pathological conditions. [References: 45] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Greenamyre JT Emory Univ, Dept Neurol WMRB 6000,1639 Pierce Dr Atlanta, GA 30322 USA Emory Univ, Dept Neurol Atlanta, GA 30322 USA Emory Univ, Dept Pharmacol Atlanta, GA 30322 USA Emory Univ, Ctr Mol Med Atlanta, GA 30322 USA Emory Univ, Yerkes Reg Primate Res Ctr Atlanta, GA 30322 USA 16 UI - 325XM-0007 AU - Turunen M AU - Peters JM AU - Gonzalez FJ AU - Schedin S AU - Dallner G TI - Influence of peroxisome proliferator-activated receptor alpha on ubiquinone biosynthesis SO - Journal of Molecular Biology 2000 Mar 31;297(3):607-614 IS - 0022-2836 MH - Ubiquinone MH - Mevalonate pathway MH - Ppar alpha MH - Peroxisomal proliferators MH - Aminotriazole MH - Rat-liver microsomes MH - Ppar-alpha MH - Tissue distribution MH - Dolichyl-phosphate MH - Synthase gene MH - Mouse MH - Mechanism MH - Prenyltransferase MH - Methyltransferase MH - Expression AB - The control of ubiquinone biosynthesis by peroxisome proliferators was investigated using peroxisome proliferator activated receptor alpha (PPAR alpha)-null mice. Administration of 2-(diethylhexyl)phthalate to control mice resulted in elevated ubiquinone levels in the liver, while dolichol, dolichyl-P and cholesterol concentrations remained unchanged. In PPAR alpha-null mice, the level of these Lipids were similar to control levels and administration of the peroxisome proliferator did not increase the levels of ubiquinone. The increase in ubiquinone levels was the result of increased synthesis. Induction was most pronounced in Liver, kidney and heart, which have relatively high, levels of PPAR alpha. When the tissue concentration of hydrogen peroxide was elevated by inhibition of catalase activity with aminotriazole, the amount of ubiquinone was not increased, suggesting that the induction of ubiquinone synthesis occured through a direct mechanism. The activities of branch-point enzymes FPP-synthase, squalene synthase, cis-prenyltransferase, trans-prenyltransferase and NPHB-transferase were substantially increased in control but not in PPAR alpha-null mice after treatment with peroxisome proliferators. These data suggest that the induction of ubiquinone biosynthesis after administration of peroxisome proliferators is dependent on the PPAR alpha through regulation of some of the mevalonate pathway enzymes. (C) 2000 Academic Press. [References: 41] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Turunen M Stockholm Univ, Dept Biochem S-10691 Stockholm Sweden Stockholm Univ, Dept Biochem S-10691 Stockholm Sweden NCI, Lab Metab, NIH Bethesda, MD 20892 USA 17 UI - 324ED-0014 AU - Sander LC AU - Sharpless KE AU - Pursch M TI - C-30 stationary phases for the analysis of food by liquid chromatography [Review] SO - Journal of Chromatography 2000 Jun 2;880(1-2):189-202 IS - 0021-9673 MH - Stationary phase, lc MH - Food analysis MH - Reviews MH - Carotenoids MH - Retinoids MH - Tocopherols MH - Vitamins MH - Carotenes MH - Polycyclic aromatic-hydrocarbons MH - Pressure chemical-ionization MH - Solid-state nmr MH - Reversed-phase MH - Carotenoid isomers MH - Mass-spectrometry MH - Bonded-phase MH - Human serum MH - Zeaxanthin stereoisomers MH - Column selectivity AB - The introduction of a polymeric C-30 liquid chromatographic column by Sander et al. [Anal. Chem., 66 (1994) 1667] designed for the separation of carotenoid isomers, has led to the development of improved analytical methods for these compounds. Subsequent commercial availability of polymerically bonded C-30 columns has facilitated these advances, and applications to a wide variety of separation problems with biological samples have been described. This report provides a comprehensive review of applications of polymeric C-30 columns, utilized in the determination of carotenoids, retinoids, and other nutrients and related compounds in complex, natural-matrix samples. (C) 2000 Published by Elsevier Science B.V. [References: 74] LG - English PT - Review SB - Current Contents(R)/Life Sciences Current Contents(R)/Physical, Chemical & Earth Sciences IN - Sander LC NIST, Div Analyt Chem Gaithersburg, MD 20899 USA NIST, Div Analyt Chem Gaithersburg, MD 20899 USA 18 UI - 324ZK-0003 AU - Van Praag E AU - Agosti RD AU - Bachofen R TI - Rhythmic activity of uptake hydrogenase in the prokaryote Rhodospirillum rubrum SO - Journal of Biological Rhythms 2000 Jun;15(3):218-224 IS - 0748-7304 MH - Rhodospirillum rubrum MH - Prokaryote MH - Uptake hydrogenase MH - Rhythmic activity MH - Anoxic conditions MH - Lomb-scargle power spectra MH - Cyanobacterium synechococcus sp MH - Circadian-rhythm MH - Gene-expression MH - Light MH - Rf-1 MH - Nitrogenase MH - Cultivation MH - Temperature MH - Membranes MH - Subunit AB - Growth of Rhodospirillum rubrum was followed in cultures kept under anoxic conditions at constant temperature in either continuous light (LL, 32 degrees C) or continuous darkness (DD, 32 degrees C and 16 degrees C). In DD, only small modifications of the turbidity were detected; linear regression analysis nevertheless gives a very significant slope! (t(34) = 13.07, p < 10(-14), with R-2 Of 0.834). Mean generation times reflected these differences of growth with 11.9 +/- 0.5 h in LL and 43.2 +/- 1.1 h in DD at 32 degrees C and 37.4 +/- 1.0 h at 16 degrees C cultures. The uptake hydrogenase (Hup) activity has been followed in situ in whole cells of A. rubrum grown in the same conditions, and a clear ultradian rhythm of activity has been observed. Indeed, after about 12 h in the new media, a rapid rise of hydrogenase activity was observed in both LL and :DD cultures after which it decreased again to very low values. The activity of Hup continued to show such fluctuations during the rest of the experiment, both in DD and in LL, during the growth and stationary phases. The Lomb-Scargle power periodogram method demonstrates the presence of a clear rhythmic Hu:p activity both in LL and DD. In the LL-grown cultures, the oscillating activity is faster and continues throughout the growth and the stationary phases, with an ultradian period of 12.1 +/- 0.5 h. In DD, the slow-growing bacteria showed an ultradian oscillatory pattern of Hup activity with periods of 15.2 +/- 0.5 h at 32 degrees C anti 23.4 +/- 2.0 h at 16 degrees C. The different periods obtained for LL- and DD-grown bacteria are significantly different. [References: 32] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Van Praag E Winterthurerst 667 CH-8051 Zurich Switzerland Univ Zurich, Inst Plant Biol CH-8008 Zurich Switzerland Univ Genoa, Dept Plant Biochem & Physiol CH-1206 Geneva 6 Switzerland 19 UI - 325CU-0050 AU - Baumer S AU - Ide T AU - Jacobi C AU - Johann A AU - Gottschalk G AU - Deppenmeier U TI - The F420H2 dehydrogenase from Methanosarcina mazei is a redox-driven proton pump closely related to NADH dehydrogenases SO - Journal of Biological Chemistry 2000 Jun 16;275(24):17968-17973 IS - 0021-9258 MH - Iron-sulfur clusters MH - Complete genome sequence MH - Bound electron-transport MH - Ubiquinone oxidoreductase MH - Methanogenic archaea MH - Energy-conservation MH - Escherichia-coli MH - Heterodisulfide oxidoreductase MH - Methanolobus-tindarius MH - Archaeoglobus-fulgidus AB - The F420H2 dehydrogenase is part of the energy conserving electron transport system of the methanogenic archaeon Methanosarcina mazei Gal, Here it is shown that cofactor F420H2-dependent reduction of 2-hydroxy-phenazine as catalyzed by the membrane-bound enzyme is coupled to proton translocation across the cytoplasmic membrane, exhibiting a stoichiometry of 0.9 H+ translocated per two electrons transferred. The electrochemical proton gradient thereby generated was shown to drive ATP synthesis from ADP + Pi. The gene cluster encoding the F420H2 dehydrogenase of M. mazei Gol comprises 12 genes that are referred to as fpoA, B, C, D, H, I, J, K, L, M, N, and O. Analysis of the deduced amino acid sequences revealed that the enzyme is closely related to proton translocating NADH dehydrogenases of respiratory chains from bacteria (NDH-1) and eukarya (complex I). Like the NADH-dependent enzymes, the F420H2 dehydrogenase is composed of three subcomplexes. The gene products FpoA, EF, J, K, L, M, and N are highly hydrophobic and are homologous to subunits that form the membrane integral module of NDH-1. FpoB, C, D, and I have their counterparts in the amphipathic membrane-associated module of NDH-1. Homologues to the hydrophilic NADH-oxidizing input module are not present in M. mazei Gill, Instead, the gene product FpoF maS be responsible for F420H2 oxidation and may function as the electron input part, Thus, the F420H2 dehydrogenase from M. mazei Gol resembles eukaryotic and bacterial proton transiocating NADH dehydrogenases in many ways. The enzyme from the methanogenic archaeon functions as a NDB-1/complex I homologue and is equipped with an alternative electron input unit for the oxidation of reduced cofactor F-420 and a modified output module adopted to the reduction of methanophenazine. [References: 32] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Deppenmeier U Univ Gottingen, Abt Allgemeine Mikrobiol Grisebachstr 8 D-37077 Gottingen Germany Univ Gottingen, Abt Allgemeine Mikrobiol D-37077 Gottingen Germany Univ Gottingen, Gottingen Genom Lab, Inst Mikrobiol & Genet D-37077 Gottingen Germany 20 UI - 325CU-0051 AU - Cruciat CM AU - Brunner S AU - Baumann F AU - Neupert W AU - Stuart RA TI - The cytochrome bc(1) and cytochrome c oxidase complexes associate to form a single supracomplex in yeast mitochondria SO - Journal of Biological Chemistry 2000 Jun 16;275(24):18093-18098 IS - 0021-9258 MH - Coenzyme qh2-cytochrome-c reductase MH - Saccharomyces-cerevisiae MH - Nuclear gene MH - Respiratory-chain MH - Membrane system MH - Bc1 complex MH - Protein MH - Identification MH - Resolution MH - Synthase AB - The mitochondrial electron transport chain complexes are large multisubunit complexes embedded in the inner membrane. We report here that in the yeast Saccharomyces cerevisiae, the cytochrome be, and cytochrome c oxidase complexes co-exist as a larger complex of similar to 1000 kDa in the mitochondrial membrane. Following solubilization with a mild detergent, the cytochrome bc(1)-cytochrome c oxidase complex remains stable. It was analyzed using the techniques of gel filtration and blue native-polyacrylamide gel electrophoresis. Direct physical. association of subunits of the cytochrome be, complex with those of the cytochrome c oxidase complex was verified by co-immunoprecipitation analysis. Our data indicate that the cytochrome be, complex is exclusively in association with the cytochrome c oxidase complex in yeast mitochondria. We term this complex the cytochrome bc(1)-cytochrome c oxidase supracomplex. [References: 31] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Stuart RA Marquette Univ, Dept Biol POB 1881 Milwaukee, WI 53051 USA Marquette Univ, Dept Biol Milwaukee, WI 53051 USA Univ Munich, Inst Physiol Chem D-80336 Munich Germany 21 UI - 325MT-0001 AU - Karim MA AU - Fracheboud Y AU - Stamp P TI - Effect of high temperature on seedling growth and photosynthesis of tropical maize genotypes SO - Journal of Agronomy & Crop Science-Zeitschrift fur Acker und Pflanzenbau 2000 Jun;184(4):217-223 IS - 0931-2250 MH - Growth MH - High temperature MH - Leaf extension rate MH - Maize (zea mays l.) MH - Photosynthesis MH - Chlorophyll fluorescence MH - Heat tolerance MH - Adaptation MH - Extension MH - Plants MH - Leaves MH - Lines MH - Zone AB - Genotypic variability in relation to growth and photosynthetic CO2 assimilation rate (P-n) is well known for maize (Zea mays L.) under heat stress conditions. This study was, however, initiated to test whether genotypic growth variation is related to variations in individual leaf size, leaf extension rate (LER), and photosynthesis of the single leaf at high temperature. Six tropical maize genotypes selected from the International Maize and Wheat Improvement Centre (CIMMYT) with contrasting growth responses were grown for 9 days after emergence (DAE) in the first and for 15 DAE in the second experiment at 25/22 degrees C and 42/30 degrees C. High temperature caused a marked decrease in the growth parameters, and the genotypes showed high growth variations irrespective of temperature levels. Interestingly, genotypes did not follow a similar ranking in relation to biomass production between 9 DAE (heterotrophic growth phase) and 15 DAE (autotrophic growth phase) at 25/22 degrees C, but the pattern was similar at 42/30 degrees C. Total leaf area and daytime LER of leaves 2 (l(2)), 3 (l(3)), and 4 (l(4)) showed a tight correlation with biomass production at both temperatures, while the LER of the youngest leaf (l(4)) at night also showed the same correlation at 42/30 degrees C. A significant relationship between the areas i, and i, and biomass was observed only at high temperature and not at 25/22 degrees C. The P-n decreased markedly at high temperature and genotypic variability was pronounced. The genotypes maintained a similar ranking of P-n measured from l(2) at 8 DAE and from l(3) at 13 DAE under unfavourable conditions only and not at 25 degrees C. Of the six genotypes, F250 outperformed the others in relation to growth and P-n activity. A tight correlation between photosynthesis of different leaves and growth was detected at high temperature but not at the optimal temperature for growth. It is concluded that the areas i, or i,, daytime LER and P-n, all measured at high temperature stress conditions, can be regarded as good indicators of the thermo-tolerance of tropical maize genotypes at the seedling stage. [References: 25] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences IN - Karim MA Inst Postgrad Studies Agr PO IPSA Gazipur 1703 Bangladesh ETH Zurich, Inst Plant Sci CH-8092 Zurich Switzerland 22 UI - 327LU-0016 AU - Pastore D AU - Greco M AU - Passarella S TI - Specific helium-neon laser sensitivity of the purified cytochrome c oxidase SO - International Journal of Radiation Biology 2000 Jun;76(6):863-870 IS - 0955-3002 MH - Rat-liver mitochondria MH - Irradiated invitro MH - Atp synthesis MH - Increase MH - Light MH - Stimulation MH - Reduction MH - Oxidation MH - Dioxygen MH - Peroxy AB - Purpose: In order to gain some insight into the mechanism of interaction between Helium-Neon (He-Ne) laser light and mitochondrial cytochromes, the sensitivity of cytochrome electron transfer activity to He-Ne laser was tested. Materials and methods: Irradiation of solutions containing either purified cytochromes or dissolved rat liver mitochondria was carried out (wavelength 632.8 nm, fluence rate 10mW cm(-2), fluence 2 J cm(-2)); the irradiation conditions were the ones able to affect cytochrome c oxidase (COX) activity in mitochondria (Pastore et at, 1994). Results: Cytochrome c oxidation catalysed by COX was affected by He-Ne laser irradiation of the purified enzyme. This result was obtained from measurements of the pseudo-first-order kinetic constant and from determinations of the turnover number of the enzyme, performed at different cytochrome c/COX ratios. Consistently, the kinetic parameters of COX changed. On the contrary, no alteration in the rate of electron transfer catalysed by either cytochrome c or bc(1) complex was found. Conclusions: This study shows that purified COX is a specific target of He-Ne laser light; therefore, COX may be considered to be a mitochondrial photo-acceptor. [References: 34] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Passarella S Univ Molise, Dipartimento Sci Anim Vegetali & Ambiente Via De Sanctis I-86100 Campobasso Italy Univ Molise, Dipartimento Sci Anim Vegetali & Ambiente I-86100 Campobasso Italy CNR, Ctr Studio Mitocondri & Metab Energet I-70126 Bari Italy 23 UI - 326VK-0001 AU - Schweigert FJ AU - Hurtienne A AU - Bathe K TI - Improved extraction procedure for carotenoids from human milk SO - International Journal for Vitamin & Nutrition Research 2000 May;70(3):79-83 IS - 0300-9831 MH - Xanthophylls MH - Saponification MH - Milk MH - Human MH - Method MH - Performance liquid-chromatography MH - Beta-carotene MH - Breast-milk MH - Retinol MH - Serum MH - Quantitation MH - Separation AB - An improves method for the extraction of the major carotenoids from human milk is described. Carotenoids were extracted from milk first with ethanol and n-hexane. Then, polar xanthophylls were extracted from n-hexane into ethanol/water. The remaining n-hexane was evaporated, the residue combined with the ethanolic milk fraction and the mixture briefly saponified. Carotenoids were extracted from the hydrolysate with n-hexane, combined with the polar xanthophylls from the non-saponified ethanol/water-extract and separated by HPLC. Using this method we were able to significantly improve the recovery of xanthophylls such as lutein and zeaxanthin from human milk. The recovery rate of all carotenoids was > 90%. This method might not only be of value for milk but should be especially useful in the extraction of carotenoids from human tissues such as the adipose tissue. [References: 10] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Schweigert FJ Univ Potsdam, Inst Nutrit Sci Arthur Scheunert Allee 114-116 D-14558 Potsdam Germany Univ Potsdam, Inst Nutrit Sci D-14558 Potsdam Germany 24 UI - 327NF-0004 AU - Muhlenhoff U TI - The FAPY-DNA glycosylase (Fpg) is required for survival of the cyanobacterium Synechococcus elongatus under high light irradiance SO - FEMS Microbiology Letters 2000 Jun 15;187(2):127-132 IS - 0378-1097 MH - Cyanobacterium MH - Dna repair MH - Fpg protein MH - Oxidative stress MH - Photosynthesis MH - Photosystem i MH - Escherichia-coli MH - Substrate-specificity MH - Purine lesions MH - Protein MH - Excision MH - Repair MH - 8-oxoguanine MH - Damage MH - Genes AB - The gene for the DNA repair enzyme Fpg from Synechococcus elongatus was detected immediately downstream of the photosystem I gene psaE. fpg is likely expressed together with psaE by transcriptional readover while psaE is mostly expressed independently. Segregated psaE and fpg deletion strains were obtained upon insertional inactivation of both genes in S. elongatus. These mutants are viable under photoautotrophic conditions, but fail to grow under high light regimes that likely cause oxidative stress. These high light sensitive phenotypes suggest that the Fpg protein, which has been shown to repair DNA lesions caused by reactive oxygen species in Escherichia coli, may be involved in the photoprotection of cyanobacteria against oxidative damage caused under high irradiance. (C) 2000 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved. [References: 20] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Muhlenhoff U Univ Marburg Klinikum, Inst Klin Zytobiol Robert-Koch-Str 5 D-35037 Marburg Germany Univ Marburg Klinikum, Inst Klin Zytobiol D-35037 Marburg Germany 25 UI - 327BK-0007 AU - Christen G AU - Steffen R AU - Renger G TI - Delayed fluorescence emitted from light harvesting complex II and photosystem II of higher plants in the 100 ns-5 mu s time domain SO - FEBS Letters 2000 Jun 16;475(2):103-106 IS - 0014-5793 MH - Delayed fluorescence MH - Quantum yield MH - Photosystem iii MH - Light harvesting complex MH - Water oxidizing complex MH - Water oxidizing complex MH - Chlorophyll-alpha MH - P680(+center-dot) reduction MH - Membrane-fragments MH - Oxygen evolution MH - Isotope-exchange MH - Reaction centers MH - Kinetics MH - Spinach MH - System AB - This study presents the first report on delayed fluorescence (DF) emitted from spinach thylakoids, D1/D2/ Cytb-559 preparations and solubilized light harvesting complex II (LHCII) in the ns time domain after excitation with saturating laser flashes. The use of a new commercially available multichannel plate with rapid gating permitted a sufficient suppression of detector distortions due to the strong prompt fluorescence. The following results were obtained: (a) in dark-adapted thylakoids, the DP amplitudes at 100 ns and 5 mu s after each flash of a train of saturating actinic pulses exhibit characteristic period four oscillations of opposite sign: the DF amplitudes at 100 ns oscillate in the same manner as the quantum yield of prompt fluorescence, whereas those at 5 mu s resemble the oscillation of the mu s kinetics of P680+(.) reduction in samples with an intact water oxidizing complex, (b) the quantum yield of total DF emission in the range up to a few mu s is estimated to be < 10(-4) for thylakoids, (c) the DF of D1/D2/Cytb-559 exhibits a monophasic decay with tau approximate to 50 ns, (d) DF emission is also observed in isolated LHCII with biphasic decay kinetics characterized by tau values of 65 ns and about 800 ns, (e) in contrast to thylakoids, the amplitudes of DE in D1/D2/Cytb-559 preparations and solubilized LHCII do not exhibit any oscillation pattern and (f) all spectra of DF from the different sample types are characteristic for emission from the lowest excited singlet state of chlorophyll a. The implications of these findings and problems to be addressed in future research are briefly discussed. (C) 2000 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved. [References: 42] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Renger G Tech Univ Berlin, Max Volmer Inst Biophys Chem & Biochem Str 17 Juni 135 D-10623 Berlin Germany Tech Univ Berlin, Max Volmer Inst Biophys Chem & Biochem D-10623 Berlin Germany 26 UI - 326NW-0006 AU - Kulakowska J AU - Kucharski S TI - New chromophoric monomers with nonlinear optical properties SO - European Polymer Journal 2000 Sep;36(9):1805-1815 IS - 0014-3057 MH - Chromophoric monomers MH - Nonlinear optics MH - First hyperpotarizability MH - Azobenzene derivatives MH - Sulfonamide chromophores MH - Langmuir-blodgett-films MH - Cis-trans isomerization MH - Photosynthetic reaction center MH - Hyper-rayleigh scattering MH - Side-chain MH - Rhodopseudomonas-viridis MH - Azo polymers MH - First hyperpolarizability MH - 2nd-harmonic generation MH - Theoretical-examination AB - The first hyperpolarizability (FH) of maleimides and acrylates of the chromophoric derivatives containing azo and sulfonyl or a nitro group, was evaluated by ab initio (GAMESS and GAUSSIAN) and semiempirical (INDO1/S) quantum-chemical calculation. The monomeric compounds contained a sulfonyl or nitro group as an electron acceptor and amine or imide nitrogen as an electron donor. It was found that a carbonyl group of the imide structure reduced the electron donor ability of the imide nitrogen atom resulting in low values of FH of the maleimides. The results obtained for acrylates with the carbonyl group separated from an electron donating nitrogen atom by two methylene groups appeared to be almost three times higher than those of the maleimides. The values of beta(0) were in the range 186.3 x 10(-40)-203.7 x 10(-40) m(4)/V, while beta(SHG) in the range 308.1 x 10(-40)-327.6 x 10(-40) m(4)/V. The agreement between the results obtained from ab initio and semiempirical calculation was good except for the compounds with a nitro group. The acrylate monomers which exhibited promising FH values were synthesised in the condensation reaction of N-methyl-N-phenylamino-2-ethanol with acryloyl chloride followed by diazonium salts preparation and coupling. The monomers were obtained with high yield of ca. 95%. (C) 2000 Elsevier Science Ltd. All rights reserved. [References: 51] LG - English PT - Article SB - Current Contents(R)/Physical, Chemical & Earth Sciences IN - Kucharski S Wroclaw Tech Univ, Inst Organ & Polymer Technol PL-50370 Wroclaw Poland Wroclaw Tech Univ, Inst Organ & Polymer Technol PL-50370 Wroclaw Poland 27 UI - 324MC-0041 AU - Rodgers S AU - Moser C AU - Martinez-Julvez M AU - Sinning I TI - Deletion of the 6-kDa subunit affects the activity and yield of the bc(1) complex from Rhodovulum sulfidophilum SO - European Journal of Biochemistry 2000 Jun;267(12):3753-3761 IS - 0014-2956 MH - Cytochrome bc(1) complex MH - Transmembrane helix MH - Fbc operon MH - Quinone binding MH - Cytochrome b(6)f complex MH - Open reading frame MH - Rhodobacter-sphaeroides MH - Bc1 complex MH - Chlamydomonas-reinhardtii MH - Rhodopseudomonas-capsulata MH - Paracoccus-denitrificans MH - Electron-transfer MH - C-oxidase MH - Iv AB - The cytochrome bc(1) complex from Rhodovulum sulfidophilum purifies as a four-subunit complex: the cytochrome b, cytochrome c(1) and Rieske iron-sulphur proteins, which are encoded together in the fbc operon, as well as a 6-kDa protein. The gene encoding the 6-kDa protein, named fbcS, has been identified. It is located within the sox operon, which encodes the subunits of sarcosine oxidase. The encoded 6-kDa protein is very hydrophobic and is predicted to form a single transmembrane helix. It shows no sequence homology to any known protein. The gene has been knocked-out of the genome and a three-subunit complex can be purified. This deletion leads to a large reduction in the yield of the isolated complex and in its activity compared to wild-type. The high quinone content found in the wild-type complex is, however, maintained after removal of the 6-kDa protein. Surprisingly, a fourth subunit of approximately 6 kDa is again found to copurify with the Rhv. sulfidophilum bc(1) complex when only the fbc operon is expressed heterologously in a near-relative, Rhodobacter capsulatus, which lacks this small subunit in its own bc(1) complex. [References: 42] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Sinning I European Mol Biol Lab, Struct Biol Programme Meyerhofstr 1 D-69012 Heidelberg Germany European Mol Biol Lab, Struct Biol Programme D-69012 Heidelberg Germany Biochem Ctr Heidleberg Heidelberg Germany 28 UI - 327GT-0024 AU - Iida K AU - Kashiwada A AU - Nango M TI - Construction of Langmuir-Blodgett films from light-harvesting complex I isolated from photosynthetic bacteria SO - Colloids & Surfaces A-Physicochemical & Engineering Aspects 2000 Sep 10;169(1-3):199-208 IS - 0927-7757 MH - Light-harvesting complex MH - Langmuir-blodgett film MH - Membrane materials MH - Bacteriochlorophyll a MH - Cytochrome-c-oxidase MH - Air-water-interface MH - Amino-acid-sequence MH - Rhodospirillum-rubrum MH - Rhodopseudomonas-viridis MH - Rhodobacter-sphaeroides MH - Electron-transfer MH - Reaction centers MH - Bacteriochlorophyll-a MH - Subunit form AB - Langmuir-Blodgett (LB) films of the light-harvesting (LH) polypeptides/bacteriochlorophyll a (BChl a) complex isolated from photosynthetic bacteria, Rhodospirillum rubrum, were constructed. The monolayers of the core LH /BChl a complex were prepared from octyl beta-glycoside suspensions at an air/water interface and then the monolayer was transferred to glass slides using LB technique multilayer films. UV-vis absorption spectra of the LB layer films absorbing 870 nm at the Qy absorption of BChl a indicated that the LH/BChl a complex in the multilayer films was more stable than the subunit complex absorbing 820 nm at the Qy absorption. Analysis of Fourier transform infrared reflection absorption spectroscopy (FTIR-RAS) spectra showed that the tilt angle of the transmembrane axis of the LH/BChl a complex in the multilayer films was 40 degrees to the normal. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 41] LG - English PT - Article SB - Current Contents(R)/Physical, Chemical & Earth Sciences IN - Iida K Nagoya Municipal Ind Res Inst, Atsuta Ku Rokuban 3 Chome 4-41 Nagoya Aichi 4560058 Japan Nagoya Municipal Ind Res Inst, Atsuta Ku Nagoya Aichi 4560058 Japan Nagoya Inst Technol, Dept Appl Chem, Showa Ku Nagoya Aichi 4668555 Japan 29 UI - 324XF-0018 AU - Hamachi I AU - Takashima H AU - Hu YZ AU - Shinkai S AU - Oishi S TI - Cyclodextrin-appended myoglobin as a tool for construction of a donor-sensitizer-acceptor triad on a protein surface SO - Chemical Communications 2000;(13):1127-1128 IS - 1359-7345 MH - Intramolecular electron-transfer MH - Photosynthetic reaction-center MH - Cofactor-reconstitution MH - Nobel lecture AB - A protein-based and noncovalently-linked donor-sensitizer-acceptor triad has been prepared by self-assembly via mechanical linkages and hydrophobic interactions, and its photoinduced electron transfer properties have been studied. [References: 14] LG - English PT - Article SB - Current Contents(R)/Physical, Chemical & Earth Sciences IN - Hamachi I Inst Mol Sci Okazaki Aichi 4448585 Japan Kyushu Univ, Grad Sch Engn, Dept Chem & Biochem Fukuoka 8128581 Japan Kitasato Univ, Sch Sci, Dept Chem Sagamihara Kanagawa 2288520 Japan 30 UI - 324ZX-0004 AU - Luparello C AU - Santamaria F AU - Schilling T TI - Regulation of PTHrP and PTH/PTHrP receptor by extracellular Ca2+ concentration and hormones in the breast cancer cell line 8701-BC SO - Biological Chemistry 2000 Apr;381(4):303-308 IS - 1431-6730 MH - Gene expression MH - Hydrocortisone MH - Microenvironment MH - Progesterone MH - Mammary epithelial-cells MH - Normal human keratinocytes MH - Invasion in-vitro MH - Parathyroid-hormone MH - Messenger-rna MH - Protein-production MH - Growth-factors MH - Peptide MH - Expression MH - Carcinoma AB - It was previously reported that 8701-BC breast tumour cells express the gene for parathyroid hormone-related peptide (PTHrP) and PTH/PTHrP receptor (PTHrPR) and release immunoreactive PTHrP (iPTHrP) into the extracellular medium. Since the regulation of PTHrP and PTHrP-R by breast cancer cells has been poorly investigated so far, we have chosen the 8701-BC cell line as a model system to investigate whether alterations in the extracellular Ca2+ concentration ([Ca2+](e)) and treatment with some well-known differentiation agents for breast cells, such as dimethyl sulfoxide, hydrocortisone, progesterone, prolactin, alltrans retinoic acid and transforming growth factor-beta 1 might (i) modulate quantitatively the release of iPTHrP, (ii) affect the PTHrP promoter usage and mRNA splicing patterns, and (iii) modify the expression of PTHrP-R. The data obtained indicate that 8701-BC cells are potentially able to utilise different start sites and mRNA splicing patterns for PTHrP transcription, and respond to variations of [Ca2+](e) and to the addition of two hormones, hydrocortisone and progesterone, with modifications in the extracellular amount of iPTHrP, Moreover, expression of PTHrP-R is also modulated by changes of [Ca2+](e) or treatment with hydrocortisone, This indicates that the 8701-BC cell line is a suitable in vitro model for further studies on the complex molecular regulation of the PTHrP/PTHrP-R pair in breast cancer. [References: 39] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Luparello C Univ Palermo, Dipartimento Biol Cellulare & Sviluppo Viale Sci I-90128 Palermo Italy Univ Palermo, Dipartimento Biol Cellulare & Sviluppo I-90128 Palermo Italy Univ Heidelberg, Dept Internal Med 1, DKFZ D-69115 Heidelberg Germany 31 UI - 327HX-0002 AU - Berden JA AU - Hartog AF TI - Analysis of the nucleotide binding sites of mitochondrial ATP synthase provides evidence for a two-site catalytic mechanism [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):234-251 IS - 0005-2728 MH - Beef-heart f1-atpase MH - Coupling factor-i MH - 3'-o-(4-benzoyl)benzoyl adenosine 5'-diphosphate MH - Proton-translocating atpase MH - Escherichia-coli f1-atpase MH - Beta-subunit MH - Noncatalytic sites MH - F1-adenosine triphosphatase MH - Oxidative-phosphorylation MH - Negative cooperativity LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Berden JA Univ Amsterdam, EC Slater Inst Biochem Res, Bioctr Plantage Muidergracht 12 NL-1018 TV Amsterdam Netherlands Univ Amsterdam, EC Slater Inst Biochem Res, Bioctr NL-1018 TV Amsterdam Netherlands 32 UI - 327HX-0003 AU - Boyer PD TI - Catalytic site forms and controls in ATP synthase catalysis [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):252-262 IS - 0005-2728 MH - Atp synthase MH - Binding change MH - Rotational catalysis MH - Phosphorylation MH - Heart mitochondrial atpase MH - Oxidative-phosphorylation MH - Nucleotide-binding MH - Bacillus ps3 MH - H+-atpase MH - F0f1-atp synthase MH - Substrate-binding MH - Epsilon-subunit MH - Molecular motor MH - Mechanism AB - A suggested minimal scheme for substrate binding by and interconversion of three forms of the catalytic sites of the ATP synthase is presented. Each binding change, that drives simultaneous interchange of the three catalytic site forms, requires a 120 degrees rotation of the gamma with respect to the beta subunits. The binding of substrate(s) at two catalytic sites is regarded as sufficing for near maximal catalytic rates to be attained. Although three sites do not need to be filled for rapid catalysis, during rapid bisite catalysis some enzyme may be transiently present with three sites filled. Forms with preferential binding for ADP and Pi or for ATP are considered to arise from the transition state and participate in other steps of the catalysis. Intermediate forms and steps that may be involved are evaluated. Experimental evidence for energy-dependent steps and for control of coupling to proton translocation and transition state forms are reviewed. Impact of relevant past data on present understanding of catalytic events is considered. In synthesis a key step is suggested in which proton translocation begins to deform an open site so as to increase the affinity for ADP and P-i, that then bind and pass through the transition state, and yield tightly bound ATP in one binding change. ADP binding appears to be a key parameter controlling rotation during synthesis. In hydrolysis ATP binding to a loose site likely precedes any proton translocation, with proton movement occurring as the tight site form develops. Aspects needing further study are noted. Characteristics of the related MgADP inhibition of the F-1 ATPases that have undermined many observations are summarized. and relations of three-site filling to catalysis are assessed. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 56] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Boyer PD Univ Calif Los Angeles, Inst Mol Biol Los Angeles, CA 90095 USA Univ Calif Los Angeles, Inst Mol Biol Los Angeles, CA 90095 USA 33 UI - 327HX-0004 AU - Capaldi RA AU - Schulenberg B TI - The epsilon subunit of bacterial and chloroplast F1F0 ATPases - Structure, arrangement, and role of the epsilon subunit in energy coupling within the complex [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):263-269 IS - 0005-2728 MH - F1f0 atpase MH - Epsilon subunit MH - Rotary motor MH - Cross linking MH - Coli atp synthase MH - Escherichia-coli MH - Gamma-subunit MH - Cross-linking MH - Conformational-changes MH - Cysteine residues MH - F0f1-atp synthase MH - Catalytic sites MH - Delta-subunit MH - Rotation AB - Recent studies show that the epsilon subunit of bacterial and chloroplast F1F0 ATPases is a component of the central stalk that links the F-1 and F-0 parts. This subunit interacts with alpha, beta and gamma subunits of F-1 and the c subunit ring of F-0. Along with the gamma subunit, epsilon is a part of the rotor that couples events at the three catalytic sites sequentially with proton translocation through the F-0 part. Structural data on the epsilon subunit when separated from the complex and in situ are reviewed, and the functioning of this polypeptide in coupling within the ATP synthase is considered. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 30] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Capaldi RA Univ Oregon, Inst Mol Biol Eugene, OR 97403 USA Univ Oregon, Inst Mol Biol Eugene, OR 97403 USA 34 UI - 327HX-0005 AU - Cross RL TI - The rotary binding change mechanism of ATP synthases [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):270-275 IS - 0005-2728 MH - F0f1 atp synthase MH - Binding change mechanism MH - Rotational catalysis MH - Oxidative phosphorylation MH - Escherichia-coli f1-atpase MH - Bovine heart-mitochondria MH - Oxygen-exchange reactions MH - Epsilon-subunit MH - Cross-linking MH - F-atpase MH - Oxidative-phosphorylation MH - Catalytic sites MH - Gamma-subunit MH - Alpha-subunit AB - The F0F1 ATP synthase functions as a rotary motor where subunit rotation driven by a current of protons flowing through F-0 drives the binding changes in F-1 that are required for net ATP synthesis. Recent work that has led to the identification of components of the rotor and stator is reviewed. In addition, a model is proposed to describe the transmission of energy from four proton transport steps to the synthesis of one ATP. Finally, some of the requirements for efficient energy coupling by a rotary binding change mechanism are considered. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 59] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Cross RL SUNY Hlth Sci Ctr, Dept Biochem & Mol Biol Syracuse, NY 13210 USA SUNY Hlth Sci Ctr, Dept Biochem & Mol Biol Syracuse, NY 13210 USA 35 UI - 327HX-0006 AU - Futai M AU - Omote H AU - Sambongi Y AU - Wada Y TI - Synthase (H+ ATPase): coupling between catalysis, mechanical work, and proton translocation [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):276-288 IS - 0005-2728 MH - F0f1 MH - Catalytic site MH - Atp synthesis MH - Proton transport MH - Hc atpase MH - Rotational catalysis MH - Escherichia-coli f1-atpase MH - Carboxyl-terminal region MH - Glycine-rich sequence MH - Heart mitochondrial atpase MH - Amino-acid residues MH - Beta-subunit MH - Gamma-subunit MH - Alpha-subunit MH - Nucleotide-binding MH - F0f1-atp synthase AB - Coupling with electrochemical proton gradient, ATP synthase (F0F1) synthesizes ATP from ADP and phosphate. Mutational studies on high-resolution structure have been useful in understanding this complicated membrane enzyme. We discuss mainly the mechanism of catalysis in the beta subunit of F-1 sector and roles of the gamma subunit in energy coupling. The gamma-subunit rotation during catalysis is also discussed. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 73] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Futai M Osaka Univ, Inst Sci & Ind Res, Div Biol Sci, Japan Sci & Technol Corp,CREST Osaka 5670047 Japan Osaka Univ, Inst Sci & Ind Res, Div Biol Sci, Japan Sci & Technol Corp,CREST Osaka 5670047 Japan 36 UI - 327HX-0007 AU - Nakamoto RK AU - Ketchum CJ AU - Kuo PH AU - Peskova YB AU - Al-Shawi MK TI - Molecular mechanisms of rotational catalysis in the F0F1 ATP synthase [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):289-299 IS - 0005-2728 MH - Adenosine triphosphate synthase MH - Coupling MH - F0f1 MH - Mutational analysis MH - Subunit interaction MH - Transition state thermodynamics MH - Escherichia-coli f1-atpase MH - Carboxyl-terminal region MH - Disulfide bond formation MH - Gamma-subunit MH - Epsilon-subunit MH - Alpha-subunit MH - Beta-subunit MH - Nucleotide-binding MH - Oxidative-phosphorylation MH - Adenosine-triphosphatase AB - Rotation of the F0F1 ATP synthase gamma subunit drives each of the three catalytic sites through their reaction pathways. The enzyme completes three cycles and synthesizes or hydrolyzes three ATP for each 360 degrees rotation of the gamma subunit. Mutagenesis studies have yielded considerable information on the roles of interactions between the rotor gamma subunit and the catalytic beta subunits. Amino acid substitutions, such as replacement of the conserved gamma Met-23 by Lys, cause altered interactions between gamma and beta subunits that have dramatic effects on the transition state of the steady state ATP synthesis and hydrolysis reactions. The mutations also perturb transmission of specific conformational information between subunits which is important for efficient conversion of energy between rotation and catalysis, and render the coupling between catalysis and transport inefficient. Amino acid replacements in the transport domain also affect the steady state catalytic transition state indicating that rotation is involved in coupling to transport. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 75] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Nakamoto RK Univ Virginia, Dept Mol Physiol & Biol Phys POB 10011 Charlottesville, VA 22906 USA Univ Virginia, Dept Mol Physiol & Biol Phys Charlottesville, VA 22906 USA 37 UI - 327HX-0008 AU - Weber J AU - Senior AE TI - ATP synthase: what we know about ATP hydrolysis and what we do not know about ATP synthesis [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):300-309 IS - 0005-2728 MH - Atp synthase MH - Proton pumping MH - Oxidative phosphorylation MH - Escherichia-coli f1-atpase MH - F-1-atpase catalytic sites MH - Thermophilic bacillus ps3 MH - Nucleotide-binding MH - Gamma-subunit MH - Adenosine-triphosphatase MH - Mitochondrial f1-atpase MH - Molecular motor MH - Epsilon-subunit MH - Beta-subunit AB - In ATP synthase. X-ray structures, demonstration of ATP-driven gamma-subunit rotation, and tryptophan fluorescence techniques to determine catalytic site occupancy and nucleotide binding affinities have resulted in pronounced progress in understanding ATP hydrolysis, for which a mechanism is presented here. In contrast, ATP synthesis remains enigmatic. The molecular mechanism by which ADP is bound in presence of a high ATP/ADP concentration ratio is a fundamental unknown: similarly P-i binding is not understood. Techniques to measure catalytic site occupancy and ligand binding affinity changes during net ATP synthesis are much needed. Relation of these parameters to gamma-rotation is a further goal. A speculative model for ATP synthesis is offered. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 44] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Senior AE Univ Rochester, Med Ctr, Dept Biochem & Biophys Box 712 Rochester, NY 14642 USA Univ Rochester, Med Ctr, Dept Biochem & Biophys Rochester, NY 14642 USA 38 UI - 327HX-0009 AU - Frasch WD TI - The participation of metals in the mechanism of the F-1-ATPase [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):310-325 IS - 0005-2728 MH - F1f0 atp synthase MH - F-1 atpase MH - Vanadyl MH - Chloroplast coupling factor MH - Escherichia-coli f1-atpase MH - Nucleotide binding-sites MH - S-adenosylmethionine synthetase MH - Heart mitochondrial f1-atpase MH - Echo envelope modulation MH - Atpase atp synthase MH - Tightly bound adp MH - Beta-subunit MH - Factor-i AB - The Mg2+ cofactor of the F1F0 ATP synthase is required for the asymmetry of the catalytic sites that leads to the differences in affinity for nucleotides, Vanadyl (V-IV = O)(2+) is a functional surrogate For Mg2+ in the F-1-ATPase, The V-51-hyperfine parameters derived from EPR spectra of VO2+ bound to specific sites on the enzyme provide a direct probe of the metal ligands at each site. Site-directed mutations of residues that serve as metal ligands were found to cause measurable changes in the V-51-hyperfine parameters of the bound VO2+. thereby providing a means by which metal ligands were identified in the functional enzyme in several conformations. At the low-affinity catalytic site comparable to beta(E) in mitochondrial F-1. activation of the chloroplast F-1-ATPase activity induces a conformational change that inserts the P-loop threonine and catch-loop tyrosine hydroxyl groups into the metal coordination sphere thereby displacing an amino group and the Walker homology B aspartate. Kinetic evidence suggests that coordination of this tyrosine by the metal when the empty site binds substrate may provide an escapement mechanism that allows the gamma subunit to rotate and the conformation of the catalytic sites to change, thereby allowing rotation only when the catalytic sites are filled. In the high-affinity conformation analogous to the beta(DP) site of mitochondrial F-1, the catch-loop tyrosine has been displaced by carboxyl groups from the Walker homology B aspartate and from beta E197 in Chlamydomonas CF1 . Coordination of the metal by these carboxyl groups contributes significantly to the ability of the enzyme to bind the nucleotide with high affinity. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 60] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Frasch WD Arizona State Univ, Dept Plant Biol, Ctr Study Early Events Photosynth Tempe, AZ 85287 USA Arizona State Univ, Dept Plant Biol, Ctr Study Early Events Photosynth Tempe, AZ 85287 USA 39 UI - 327HX-0010 AU - Richter ML AU - Hein R AU - Huchzermeyer B TI - Important subunit interactions in the chloroplast ATP synthase [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):326-342 IS - 0005-2728 MH - Chloroplast MH - Atp synthase MH - Bi-site mechanism MH - Coupling factor-i MH - Nucleotide binding-sites MH - Escherichia-coli f1-atpase MH - Gamma-subunit MH - Epsilon-subunit MH - Delta-subunit MH - Electron-microscopy MH - Cross-linking MH - Spinach-chloroplasts MH - Change mechanism AB - General structural features of the chloroplast ATP synthase are summarized highlighting differences between the chloroplast enzyme and other ATP syntheses. Much of the review is focused on the important interactions between the epsilon and gamma subunits of the chloroplast coupling factor 1 (CF1) which are involved in regulating the ATP hydrolytic activity of the enzyme and also in transferring energy from the membrane segment, chloroplast coupling factor 0 (CF0). to the catalytic sites on CF1. A simple model is presented which summarizes propel ties of three known states of activation of the membrane bound form of CF1. The three states can be explained in terms of three different bound conformational states of the epsilon Subunit. One of the three slates, the fully active state, is only found in the membrane-bound form of CF1. The lack of this state in the isolated form of CF1, together with the confirmed presence of permanent asymmetry among the alpha, beta and gamma subunits of isolated CF1, indicate that ATP hydrolysis by isolated CF1 may involve only two of the three potential catalytic sires on the enzyme. Thus isolated CF1 may be different from other Fl enzymes in that it only operates on two cylinders whereby the gamma subunit does not relate through a full 360 degrees during the catalytic cycle. On the membrane in the presence of a light-induced proton gradient the enzyme assumes a conformation which may involve all three catalytic sites and a full 360 degrees rotation of gamma during catalysis. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 113] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Richter ML Univ Kansas, Dept Mol Biosci Lawrence, KS 66045 USA Univ Kansas, Dept Mol Biosci Lawrence, KS 66045 USA Tierarztliche Hsch, Inst Tieroekol & Zellbiol D-30559 Hannover Germany 40 UI - 327HX-0012 AU - Dunn SD AU - McLachlin DT AU - Revington M TI - The second stalk of Escherichia coli ATP synthase [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):356-363 IS - 0005-2728 MH - Adenosine triphosphate synthase MH - Stator MH - B subunit MH - Delta subunit MH - Stalk MH - Sensitivity-conferring protein MH - Proton-translocating atpase MH - Bovine heart-mitochondria MH - C-terminal end MH - B-subunit MH - Delta-subunit MH - Cross-linking MH - 2nd stalk MH - F1 atpase MH - H+-atpase AB - Two stalks link the F-1 and F-0 sectors of ATP synthase. The central stalk contains the gamma and epsilon subunits and is thought to function in rotational catalysis as a rotor driving conformational changes in the catalytic alpha(3)beta(3) complex. The two b subunits and the delta subunit associate to form b(2)delta, a second, peripheral stalk extending from the membrane up the side of alpha(3)beta(3) and binding to the N-terminal regions of the a subunits, which are approx. 125 Angstrom from the membrane. This second stalk is essential for binding F-1 to F-0 and is believed to function as a stator during rotational catalysis. In vitro, b(2)delta is a highly extended complex held together by weak interactions. Recent work has identified the domains of b which are essential for dimerization and for interaction with delta. Disulphide cross-linking studies imply that the second stalk is a permanent structure which remains associated with one alpha subunit or alpha beta pair. However, the weak interactions between the polypeptides in b2 delta pose a challenge for the proposed stator function. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 50] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Dunn SD Univ Western Ontario, Dept Biochem London ON N6A 5C1 Canada Univ Western Ontario, Dept Biochem London ON N6A 5C1 Canada 41 UI - 327HX-0013 AU - Deckers-Hebestreit G AU - Greie JC AU - Stalz WD AU - Altendorf K TI - The ATP synthase of Escherichia coli: structure and function of F-0 subunits [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):364-373 IS - 0005-2728 MH - F0f1-atpase MH - F-0 complex MH - Topology MH - Monoclonal antibody MH - Circular dichroism MH - Escherichia coli MH - Bovine heart-mitochondria MH - Carboxyl-terminal region MH - H+/atp coupling ratio MH - Polar loop region MH - B-subunit MH - H+-atpase MH - Alpha-subunit MH - Cross-linking MH - Delta-subunit MH - F1f0-atp synthase AB - In this review we discuss recent work from our laboratory concerning the structure and/or function of the F-0 subunits of the proton-translocating ATP synthase of Escherichia coli. For the topology of subunit tr a brief discussion gives (i) a detailed picture of the C-terminal two-thirds of the protein with four transmembrane helices and the C terminus exposed to the cytoplasm and (ii) an evaluation of the controversial results obtained for the localization of the N-terminal region of subunit a including its consequences on the number of transmembrane helices. The structure of membrane-bound subunit b has been determined by circular dichroism spectroscopy to be at least 75% alpha-helical, For this purpose a method was developed, which allows the determination of the structure composition of membrane proteins in protroliposomes. Subunit b, was purified to homogeneity by preparative SDS gel electrophoresis, precipitated with acetone, and redissolved in cholate-containing buffer, thereby retaining its native conformation as shown by functional coreconstitution with an ne subcomplex. Monoclonal antibodies, which have their epitopes located within the hydrophilic loop region of subunit c, and the F-1 part are bound simultaneously to the F-0 complex without an effect on the function of F-0, indicating that not all c subunits are involved in F-1 interaction. Consequences on the coupling mechanism between ATP synthesis/hydrolysis and proton translocation are discussed. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 103] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Deckers-Hebestreit G Univ Osnabruck, Fachbereich Biol Chem, Abt Mikrobiol D-49069 Osnabruck Germany Univ Osnabruck, Fachbereich Biol Chem, Abt Mikrobiol D-49069 Osnabruck Germany 42 UI - 327HX-0014 AU - Dimroth P TI - Operation of the F-0 motor of the ATP synthase [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):374-386 IS - 0005-2728 MH - Adenosine triphosphate synthase MH - F-0 motor MH - Ion translocation mechanism MH - Subunit c structure MH - Obligatory role of delta psi in atp synthesis MH - Escherichia-coli f0f1-atpase MH - Propionigenium-modestum MH - Subunit-c MH - F1f0 atpase MH - Proton translocation MH - Alpha-subunit MH - A-subunit MH - F-atpase MH - Adenosine-triphosphatase MH - Energy transduction AB - ATP, the universal carrier of cell energy is manufactured from ADP and phosphate by the enzyme ATF synthase using the energy stored in a transmembrane ion gradient. The two components of the ion gradient (Delta pH or Delta pNa(+)) and the electrical potential difference Delta psi are thermodynamically but not kinetically equivalent. In contrast to accepted wisdom, the electrical component is kinetically indispensable not only for bacterial ATP synthases but also for that from chloroplasts. Recent biochemical studies with the Na+-translocating ATP synthase of Propionigenium modestum have given a good idea of the ion translocation pathway in the F-0 motor. Taken together with biophysical data, the operating principles of the motor have been delineated. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 63] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Dimroth P ETH Zentrum, Inst Mikrobiol CH-8092 Zurich Switzerland ETH Zentrum, Inst Mikrobiol CH-8092 Zurich Switzerland 43 UI - 327HX-0015 AU - Fillingame RH AU - Jiang W AU - Dmitriev OY AU - Jones PC TI - Structural interpretations of F-0 rotary function in the Escherichia coli F1F0 ATP synthase [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):387-403 IS - 0005-2728 MH - Adenosine triphosphate synthase MH - Proton transport MH - Rotary motor MH - Subunit c MH - F-0 structure MH - Subunit-c MH - Propionigenium-modestum MH - H+-atpase MH - Suppressor mutations MH - Cross-linking MH - Proteolipid subunit MH - Crystal-structure MH - Membrane domain MH - Epsilon-subunit MH - Molecular-basis AB - F1F0 ATP synthases are known to synthesize ATP by rotary catalysis in the Fl sector of the enzyme. Proton translocation through the F-0 membrane sector is now proposed to drive rotation of an oligomer of c subunits, which in turn drives rotation of subunit gamma in F-1. The primary emphasis of this review will be on recent work from our laboratory on the structural organization of F-0, which proves to be consistent with the concept of a c(12) oligomeric rotor. From the NMR structure of subunit c and cross-linking studies, we call now suggest a detailed model for the organization of the c(12) oligomer in F-0 and some of the transmembrane interactions with subunits a and b. The structural model indicates that the H+-carrying carboxyl of subunit c is located between subunits of the c(12) oligomer and that two c subunits pack in a front-to-back manner to form the proton (cation) binding site. The proton carrying Asp61 side chain is occluded between subunits and access to it, for protonation and deprotonation via alternate entrance and exit half-channels, requires a swiveled opening of the packed c subunits and stepwise association with different transmembrane helices of subunit a. We suggest how some of the structural information can be incorporated into models of rotary movement of the c(12) oligomer during coupled synthesis of ATP in the Fl portion of the molecule. (C) 2000 Elsevier Science B,V. All rights reserved. [References: 78] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Fillingame RH Univ Wisconsin, Sch Med, Dept Biomol Chem 1300 Univ Ave Madison, WI 53706 USA Univ Wisconsin, Sch Med, Dept Biomol Chem Madison, WI 53706 USA 44 UI - 327HX-0016 AU - Bottcher B AU - Graber P TI - The structure of the H+-ATP synthase from chloroplasts and its subcomplexes as revealed by electron microscopy [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):404-416 IS - 0005-2728 MH - Chloroplast MH - H+-atpase MH - Adenosine triphosphate synthase MH - H+-translocating atpase from chloroplast MH - Electron microscopy MH - Escherichia-coli f1-atpase MH - Atomic-force microscopy MH - Coupling factor-i MH - Epsilon-subunit MH - Cryoelectron microscopy MH - Cross-linking MH - Immunoelectron microscopy MH - Mitochondrial f1-atpase MH - Monoclonal-antibodies MH - Spinach-chloroplasts AB - The electron microscopic data available on CF0F1 and its subcomplexes, CF0, CF1, subunit III complex are collected and the CF1 data are compared with the high resolution structure of MF1. The data are based on electron microscopic investigation of negatively stained isolated CF1, CF0F1 and subunit III complex. In addition, two-dimensional crystals of CF0F1 and CF0F1 reconstituted liposomes were investigated by cryo-electron microscopy. Progress in the interpretation of electron microscopic data from biological samples has been made with the introduction of image analysis. Multi-reference alignment and classification of images have led to the differentiation between different conformational states and to the detection of a second stalk. Recently, the calculation of three-dimensional mars from the class averages led to the understanding of the spatial organisation of the enzyme. Such three-dimensional maps give evidence of the existence of a third connection between the F-0 part and F-1 part. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 72] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Graber P Inst Phys Chem Albertstr 23A D-79104 Freiburg Germany Inst Phys Chem D-79104 Freiburg Germany European Mol Biol Lab D-69012 Heidelberg Germany 45 UI - 327HX-0017 AU - Groth G TI - Molecular models of the structural arrangement of subunits and the mechanism of proton translocation in the membrane domain of F1F0 ATP synthase [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):417-427 IS - 0005-2728 MH - Atp synthase MH - F-0 domain MH - Interacting subunit MH - Subunit c MH - Molecular model MH - Molecular mechanism MH - Proton translocation MH - Polar loop region MH - Tryptophan-scanning mutagenesis MH - Escherichia-coli f1-atpase MH - Cross-linking MH - B-subunit MH - H+-atpase MH - C-subunit MH - Transmembrane topology MH - F-0 complex MH - Intersubunit rotation AB - Subunit c of the proton-transporting ATP synthase of Escherichia coli forms an oligomeric complex in the membrane domain that functions in transmembrane proton conduction. The arrangement of subunit c monomers in this oligomeric complex was studied by scanning mutagenesis. On the basis of these studies and structural information on subunit c, different molecular models for the potential arrangement of monomers in the c-oligomer are discussed. Intersubunit contacts in the F-0 domain that have been analysed in the past by chemical modification and mutagenesis studies are summarised. Transient contacts of the c-oligomer with subunit a might play a crucial role in the mechanism of proton translocation. Schematic models presented by several authors that interpret proton transport in the F-0 domain by a relative rotation of the c-subunit oligomer against subunit a are reviewed against the background of the molecular models of the oligomer. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 73] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Groth G Univ Dusseldorf Univ Str 1 D-40225 Dusseldorf Germany Univ Dusseldorf D-40225 Dusseldorf Germany 46 UI - 327HX-0018 AU - Devenish RJ AU - Prescott M AU - Roucou X AU - Nagley P TI - Insights into ATP synthase assembly and function through the molecular genetic manipulation of subunits of the yeast mitochondrial enzyme complex [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):428-442 IS - 0005-2728 MH - Yeast mitochondrial atp synthase MH - F-0 subunit organization MH - Proton channel MH - Stator stalk MH - Stoichiometry MH - Green fluorescent protein fusion MH - Sensitivity-conferring protein MH - Bovine heart-mitochondria MH - Central hydrophobic domain MH - Cytochrome-c-oxidase MH - Escherichia-coli MH - Saccharomyces-cerevisiae MH - H+-atpase MH - Delta-subunit MH - Membrane topography MH - F1f0-atp synthase AB - Development of an increasingly detailed understanding of the eucaryotic mitochondrial ATP synthase requires a detailed knowledge of the stoichiometry, structure and function of F-0 sector subunits in the contexts of the proton channel and the stator stalk. Still to be resolved are the precise locations and roles of other supernumerary subunits present in mitochondrial ATP synthase complexes, but not found in the bacterial or chloroplast enzymes. The highly developed system of molecular genetic manipulation available in the yeast Saccharomyces cerevisiae, a unicellular eucaryote, permits testing for gene function based on the effects of gene disruption or deletion. In addition, the genes encoding ATP synthase subunits can be manipulated to introduce specific amino acids at desired positions within a subunit, or to add epitope or affinity tags at the C-terminus, enabling questions of stoichiometry, structure and function to be addressed. Newly emerging technologies, such as fusions of subunits with GFP are being applied to probe the dynamic interactions within mitochondrial ATP synthase, between ATP synthase complexes, and between ATP synthase and other mitochondrial enzyme complexes. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 97] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Nagley P Monash Univ, Dept Biochem & Mol Biol POB 13D Clayton Vic 3800 Australia Monash Univ, Dept Biochem & Mol Biol Clayton Vic 3800 Australia 47 UI - 327HX-0019 AU - Velours J AU - Paumard P AU - Soubannier V AU - Spannagel C AU - Vaillier J AU - Arselin G AU - Graves PV TI - Organisation of the yeast ATP synthase F-0: a study based on cysteine mutants, thiol modification and cross-linking reagents [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):443-456 IS - 0005-2728 MH - Yeast MH - Mitochondria MH - Atp synthase MH - Subunit 4 MH - Subunit 6 MH - Subunit i MH - Subunit f MH - Subunit oscp MH - Cross-linking MH - Bovine heart-mitochondria MH - Subunit-4 subunit-b MH - Escherichia-coli MH - F1f0-atp synthase MH - Structural gene MH - Sequence-analysis MH - Terminal region MH - H+-atpase MH - Membrane MH - F1-atpase AB - A topological study of the yeast ATP synthase membranous domain was undertaken by means of chemical modifications and cross-linking experiments on the wild-type complex and on mutated enzymes obtained by site-directed mutagenesis of genes encoding ATP synthase subunits, The modification by non-permeant maleimide reagents of the Cys-54 of mutated subunit 4 (subunit b), of the Cys-23 in the N-terminus of subunit 6 (subunit a) and of the Cys-91 in the C-terminus of mutated subunit f demonstrated their location in the mitochondrial intermembrane space. Near-neighbour relationships between subunits of the complex were demonstrated by means of homobifunctional and heterobifunctional reagents. Our data suggest interactions between the first transmembranous alpha-helix of subunit 6, the two hydrophobic segments of subunit 4 and the unique membrane-spanning segments of subunits i and f. The amino acid residue 174 of subunit 4 is close to both oscp and the beta-subunit, and the residue 209 is close to oscp. The dimerisation of subunit 4 in the membrane revealed that this component is located in the periphery of the enzyme and interacts with other ATP synthase complexes. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 57] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Velours J CNRS, Inst Biochim & Genet Cellulaires 1 Rue Camille St Saens F-33077 Bordeaux France CNRS, Inst Biochim & Genet Cellulaires F-33077 Bordeaux France 48 UI - 327HX-0020 AU - Vik SB AU - Long JC AU - Wada T AU - Zhang D TI - A model for the structure of subunit a of the Escherichia coli ATP synthase and its role in proton translocation [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):457-466 IS - 0005-2728 MH - Atp synthase MH - Proton translocation MH - Subunit a MH - Mutagenesis MH - F-0 structure MH - Amino-acid insertions MH - Coupling h+ transport MH - Alpha-subunit MH - A-subunit MH - Cross-linking MH - F-0 sector MH - F1f0-atp synthase MH - Delta-subunit MH - B-subunit MH - F(1)f(0)-atp synthase AB - Most of what is known about the structure and function of subunit a, of the ATP synthase, has come from the construction and isolation of mutations, and their analysis in the context of the ATP synthase complex. Three classes of mutants will be considered in this review. (1) Cys substitutions have been used for structural analysis of subunit a, and its interactions with subunit c. (2) Functional residues have been identified by extensive mutagenesis. These studies have included the identification of second-site suppressors within subunit a. (3) Disruptive mutations include deletions at both termini, internal deletions, and single amino acid insertions. The results of these studies, in conjunction with information about subunits b and c: can be incorporated into a model for the mechanism of proton translocation in the Escherichia coli ATP synthase. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 79] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Vik SB So Methodist Univ, Dept Biol Sci Dallas, TX 75275 USA So Methodist Univ, Dept Biol Sci Dallas, TX 75275 USA 49 UI - 327HX-0021 AU - Muneyuki E AU - Noji H AU - Amano T AU - Masaike T AU - Yoshida M TI - F0F1-ATP synthase: general structural features of 'ATP-engine' and a problem on free energy transduction [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):467-481 IS - 0005-2728 MH - Escherichia-coli f1-atpase MH - Steady-state kinetics MH - Heart mitochondrial atpase MH - Chloroplast coupling factor MH - Catalytic sites MH - Beta-subunit MH - Nucleotide-binding MH - Adenosine-triphosphatase MH - Thermophilic bacterium MH - H+-atpase LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Yoshida M Tokyo Inst Technol, Resources Utilizat Res Lab, Midori Ku R-1,4259 Nagatsuta Yokohama Kanagawa 2268503 Japan Tokyo Inst Technol, Resources Utilizat Res Lab, Midori Ku Yokohama Kanagawa 2268503 Japan Teikyo Univ, Biotechnol Res Ctr 3F, CREST Genet Programming Team 13, Miyamae Ku Kawasaki Kanagawa 2160001 Japan 50 UI - 327HX-0022 AU - Oster G AU - Wang HY TI - Reverse engineering a protein: the mechanochemistry of ATP synthase [Review] SO - Biochimica et Biophysica Acta - Bioenergetics 2000 May 31;1458(2-3):482-510 IS - 0005-2728 MH - Atp synthase MH - Bioenergetics MH - Mechanochemistry MH - Modeling MH - Atp hydrolysis MH - Bacterial flagellar motor MH - Binding change mechanism MH - Escherichia-coli MH - Propionigenium-modestum MH - Energy transduction MH - Crystal-structure MH - Rna-polymerase MH - Subunit-c MH - F1-atpase MH - Kinesin AB - ATP synthase comprises two rotary motors in one. The F-1 motor can generate a mechanical torque using the hydrolysis energy of ATP. The F-0 motor generates a rotary torque in the opposite direction, but it employs a transmembrane proton motive force. Each motor can be reversed: The F-0 motor can drive the F-1 motor in reverse to synthesize ATP, and the F-1 motor can drive the F-0 motor in reverse to pump protons. Thus ATP synthase exhibits two of the major energy transduction pathways employed by the cell to convert chemical energy into mechanical force. Here we show how a physical analysis of the F-1 and F-0 motors can provide a unified view of the mechanochemical principles underlying these energy transducers. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 49] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Oster G Univ Calif Berkeley, Dept Mol & Cellular Biol Berkeley, CA 94720 USA Univ Calif Berkeley, Dept Mol & Cellular Biol Berkeley, CA 94720 USA Univ Calif Berkeley, Coll Nat Resources Berkeley, CA 94720 USA 51 UI - 324PR-0001 AU - Matysik J AU - Alia AU - Nachtegaal G AU - van Gorkom HJ AU - Hoff AJ AU - de Groot HJM TI - Exploring the calcium-binding site in photosystem II membranes by solid-state Cd-113 NMR SO - Biochemistry 2000 Jun 13;39(23):6751-6755 IS - 0006-2960 MH - Nuclear-magnetic-resonance MH - Photosynthetic oxygen evolution MH - S-1-state manganese cluster MH - Alkaline-phosphatase MH - Molecular-structure MH - Carboxypeptidase-a MH - Evolving complex MH - Proteins MH - Resolution MH - Spectroscopy AB - Calcium (Ca2+) is an essential cofactor for photosynthetic oxygen evolution. Although the involvement of Ca2+ at the oxidizing side of photosystem II of plants has been known for a long time, its ligand interactions and mode of action have remained unclear. In the study presented here, Cd-113 magic angle spinning solid-state NMR spectroscopy is used to probe the Ca2+-binding site in the water-oxidizing complex of Cd-113(2+)-substituted PS2. A single NMR signal 142 ppm downfield from Cd(CIO4)(2). 2H(2)O was recorded from Cd2+ present at the Ca2+-binding site. The anisotropy of the signal is small, as indicated by the absence of spinning side bands. The signal intensity is at its maximum at a temperature of -60 degrees C. The line width of the proton signal in a WISE (wide-line separation) two-dimensional H-1-Cd-113 NMR experiment demonstrates that the signal arises from Cd2+ in a solid and magnetically undisturbed environment. The chemical shift, the small anisotropy, and the narrow line of the Cd-113 NMR signal provide convincing evidence for a 6-fold coordination, which is achieved partially by oxygen and partially by nitrogen or chlorine atoms in otherwise a symmetric octahedral environment. The absence of a Cd-113 signal below -70 degrees C suggests that the Ca2+-binding site is close enough to the tetramanganese cluster to be affected by its electron spin state. To our knowledge, this is the first report for the application of solid-state NMR in the study of the membrane-bound PS2 protein complex. [References: 47] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - de Groot HJM Leiden Univ, Leiden Inst Chem, Gorlaeus Lab NL-2300 RA Leiden Netherlands Leiden Univ, Leiden Inst Chem, Gorlaeus Lab NL-2300 RA Leiden Netherlands Leiden Univ, Huygens Lab, Dept Biophys NL-2300 RA Leiden Netherlands Univ Nijmegen, NWO CW HF NMR Facil NL-6525 ED Nijmegen Netherlands 52 UI - 324PR-0002 AU - Pfitzner U AU - Hoffmeier K AU - Harrenga A AU - Kannt A AU - Michel H AU - Bamberg E AU - Richter OMH AU - Ludwig B TI - Tracing the D-pathway in reconstituted site-directed mutants of cytochrome c oxidase from Paracoccus denitrificans SO - Biochemistry 2000 Jun 13;39(23):6756-6762 IS - 0006-2960 MH - Bo ubiquinol oxidase MH - Proton-pumping activity MH - Escherichia-coli MH - Subunit-i MH - Rhodobacter-sphaeroides MH - Electron-transfer MH - 2.8 angstrom MH - Translocation MH - Spectroscopy MH - Resolution AB - Heme-copper terminal oxidases use the free energy of oxygen reduction to establish a transmembrane proton gradient. While the molecular mechanism of coupling electron transfer to proton pumping is still under debate, recent structure determinations and mutagenesis studies have provided evidence for two pathways for protons within subunit I of this class of enzymes. Here, we probe the D-pathway by mutagenesis of the cytochrome c oxidase of the bacterium Paracoccus denitrificans; amino acid replacements were selected with the rationale of interfering with the hydrophilic lining of the pathway, in particular its assumed chain of water molecules. Proton pumping was assayed in the reconstituted vesicle system by a stopped-flow spectroscopic approach, allowing a reliable assessment of proton translocation efficiency even at low turnover rates. Several mutations at positions above the cytoplasmic pathway entrance (Asn 131, Asn 199) and at the periplasmic exit region (Asp 399) led to complete inhibition of proton pumping; one of these mutants, N13 ID, exhibited an ideal decoupled phenotype, with a turnover comparable to that of the wild-type enzyme. Since sets of mutations in other positions along the presumed course of the pathway showed normal proton translocation stoichiometries, we conclude that the D-pathway is too wide in most areas above positions 131/199 to be disturbed by single amino acid replacements. [References: 50] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Ludwig B Univ Frankfurt, Inst Biochem, Biozentrum Marie Curie Str 9 D-60439 Frankfurt Germany Univ Frankfurt, Inst Biochem, Biozentrum D-60439 Frankfurt Germany Max Planck Inst Biophys, Abt Mol Membranbiol D-60528 Frankfurt Germany Max Planck Inst Biophys, Biophys Chem Abt D-60496 Frankfurt Germany 53 UI - 324PR-0003 AU - Geijer P AU - Deak Z AU - Styring S TI - Proton equilibria in the manganese cluster of photosystem II control the intensities of the S-0 and S-2 state g approximate to 2 electron paramagnetic resonance signals SO - Biochemistry 2000 Jun 13;39(23):6763-6772 IS - 0006-2960 MH - Oxygen-evolving complex MH - Photosynthetic water oxidation MH - Tyrosine y-z MH - Epr signal MH - Donor side MH - Reduction kinetics MH - Acid-residues MH - Ph MH - Acetate MH - Evolution AB - We have studied the pH effect on the So and S-2 multiline electron paramagnetic resonance (EPR) signals from the water-oxidizing complex of photosystem II. Around pH 6, the maximum signal intensities were detected. On both the acidic and alkaline sides of pH 6, the intensities of the EPR signals decreased. Two pKs were determined for the So multiline signal; pK(1) = 4.2 +/- 0.2 and pK(2) = 8.0 +/- 0.1, and for the S2 multiline signal the pKs were pK(1) = 4.5 +/- 0.1 and pK(2) = 7.6 +/- 0.1. The intensity of the So-state: EPR signal was partly restored when the pH was changed from acidic or alkaline pH back to pH approximate to 6. In the S2 State we observed partial recovery of the multiline signal when going from alkaline pH back to pH approximate to 6, whereas no significant recovery of the S2 multiline signal was observed when the pH was changed from acidic pH back to pH approximate to 6. Several possible explanations for the intensity changes as a function of pH are discussed. Some are ruled out, such as disintegration of the Mn cluster or decay of the S states and formal Cl- and Ca2+ depletion. The altered EPR signal intensities probably reflect the protonation/deprotonation of ligands to the Mn cluster or the oxo bridges between the Mn ions. Also, the possibility of decreased multiline signal intensities at alkaline pH as an effect of changed redox potential of Yz is put forward. [References: 78] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Styring S Univ Lund, Ctr Chem & Chem Engn POB 124 S-22100 Lund Sweden Univ Lund, Ctr Chem & Chem Engn S-22100 Lund Sweden Hungarian Acad Sci, Biol Res Ctr, Inst Plant Biol H-6701 Szeged Hungary 54 UI - 324PR-0013 AU - Karpefors M AU - Adelroth P AU - Brzezinski P TI - Localized control of proton transfer through the D-pathway in cytochrome c oxidase: Application of the proton-inventory technique SO - Biochemistry 2000 Jun 13;39(23):6850-6856 IS - 0006-2960 MH - Electron-transfer MH - Rhodobacter-sphaeroides MH - R-sphaeroides MH - Dioxygen MH - Oxygen MH - Mechanism MH - Translocation MH - Enzyme MH - Purification MH - Activation AB - In the reaction cycle of cytochrome c oxidase from Rhodobacter sphaeroides, one of the steps that are coupled to proton pumping, the oxo-ferryl-to-oxidized transition (F --> O), displays a large kinetic deuterium isotope effect of about 7, In this study we have investigated in detail the dependence of the kinetics of this reaction step [k(FO)(chi)] on the fraction (chi) D2O in the enzyme solution (proton-inventory technique). According to a simplified version of the Gross-Butler equation, from the shape of the graph describing k(FO)(chi)/k(FO)(0), conclusions can be drawn concerning the number of protonatable sites involved in the rare-limiting proton-transfer reaction step. Even though the proton-transfer reaction during the F --> O transition takes place over a distance of at least 30 Angstrom and involves a large number of protonatable sites, the proton-inventory analysis displayed a linear dependence, which indicates that the entire deuterium isotope effect of 7 is associated with a single protonatable site. On the basis of experiments with site-directed mutants of cytochrome c oxidase, this localized proton-transfer rate control is proposed to be associated with glutamate (I-286) in the D-pathway, Consequently, the results indicate that proton transfer from the glutamate controls the rate of all events during the F --> O reaction step. The proton-inventory analysis of the overall enzyme turnover reveals a nonlinear plot characteristic of at least two protonatable sites involved in the rate-limiting step in the transition state, which indicates that this step does not involve proton transfer through the same pathway (or through the same mechanism) as during the F --> O transition. [References: 45] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Brzezinski P Stockholm Univ, Arrhenius Labs Nat Sci, Dept Biochem SE-10691 Stockholm Sweden Stockholm Univ, Arrhenius Labs Nat Sci, Dept Biochem SE-10691 Stockholm Sweden Univ Gothenburg, Dept Biochem & Biophys SE-40530 Gothenburg Sweden 55 UI - 327DQ-0001 AU - Meinke C AU - Sole VA AU - Pospisil P AU - Dau H TI - Does the structure of the water-oxidizing Photosystem II-manganese complex at room temperature differ from its low-temperature structure? A comparative X-ray absorption study SO - Biochemistry 2000 Jun 20;39(24):7033-7040 IS - 0006-2960 MH - Oxygen-evolving complex MH - Linear dichroism spectroscopy MH - Fine-structure exafs MH - Esrf beamline id26 MH - Photosynthetic apparatus MH - Membrane-particles MH - Model compounds MH - Calcium MH - Cluster MH - Evolution AB - Detailed information on room-temperature structure and oxidation state of the Photosystem II (PS II) manganese complex is needed to put mechanistic considerations on solid grounds. Because previously this information had not been available, the tetranuclear manganese complex was investigated by X-ray absorption spectroscopy (XAS) on PS II membrane particles at 290 K. Due to methodical progress (collection of XAS spectra within 10 s or less), significant X-ray radiation damage can be avoided; room-temperature XAS investigations on the PS II in its native membrane environment become feasible. Thus, the ambiguity with respect to the mechanistic relevance of low-temperature XAS results is avoidable. At 290 K as well as at 18 K, the manganese complex in its dark-stable state (S-1-state) seemingly is a Mn(III)(2)Mn(IV)(2) complex comprising two di-mu(2)-oxo bridged binuclear manganese units characterized by the same Mn-Mn distance of 2.71-2.72 Angstrom at both temperatures. Most likely, manganese oxidation states and the protonation state of the bridging oxides are fully temperature independent. Remarkably, at room-temperature manganese-ligand distances of 3.10 and 3.65 Angstrom are clearly discernible in the EXAFS spectra. The type of bridging assumed to result in Mn-Mn or Mn-Ca distances around 3.1 Angstrom is, possibly, temperature-dependent as suggested by distance lengthening upon cooling by 0.13 Angstrom. However, mechanistic proposals on photosynthetic water oxidation, which involve the dimer-of-dimers model [Yachandra, V. K., ct al. (1993) Science 260, 675-679] are not invalidated by the presented results. [References: 45] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Dau H Free Univ Berlin, Fachbereich Phys Arnimallee 14 D-14195 Berlin Germany Univ Marburg, FB Biol D-35032 Marburg Germany 56 UI - 327DQ-0021 AU - Schmidt KA AU - Neerken S AU - Permentier HP AU - Hager-Braun C AU - Amesz J TI - Electron transfer in reaction center core complexes from the green sulfur bacteria Prosthecochloris aestuarii and Chlorobium tepidum SO - Biochemistry 2000 Jun 20;39(24):7212-7220 IS - 0006-2960 MH - Photosynthetic reaction-center MH - Bound cytochrome-c MH - Excited-states MH - Photosystem-i MH - Resonance spectroscopy MH - Charge separation MH - Triplet formation MH - Vibrioforme MH - Acceptor MH - Limicola AB - Electron transfer in reaction center core (RCC) complexes from the green sulfur bacteria Prosthecochloris aestuarii and Chlorobium tepidum was studied by measuring flash-induced absorbance changes. The first preparation contained approximately three iron-sulfur centers, indicating that the three putative electron accepters F-X, F-A, and F-B were present; the Chl. tepidum complex contained on the average only one. In the RCC complex of Ptc. aestuarii at 277 K essentially all of the oxidized primary donor (Ps40(+)) created by a flash was rereduced in several seconds by N-methylphenazonium methosulfate. In RCC complexes of Chl. tepidum two decay components, one of 0.7 ms and a smaller one of about 2 s, with identical absorbance difference spectra were observed. The fast component might be due to a back reaction of P840(+) with a reduced electron acceptor, in agreement with the notion that the terminal electron accepters, F-A and F-B, were lost in most of the Chl. tepidum complexes. In both complexes the terminal electron acceptor (F-A or F-B) could be reduced by dithionite, yielding a back reaction of 170 ms with P840(+). At 10 K in the RCC complexes of both species P840(+) was rereduced in 40 ms, presumably by a back reaction with F-X(-). In addition, a 350 mu s component occurred that can be ascribed to decay of the triplet of P840, formed in part of the complexes. For P840(+) rereduction a pronounced temperature dependence was observed, indicating that electron transfer is blocked after F-X at temperatures below 200 K. [References: 43] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Amesz J Leiden Univ, Huygens Lab, Dept Biophys POB 9504 NL-2300 RA Leiden Netherlands Leiden Univ, Huygens Lab, Dept Biophys NL-2300 RA Leiden Netherlands Univ So Denmark, Inst Biochem DK-5230 Odense Denmark 57 UI - 327DQ-0023 AU - Sazanov LA AU - Peak-Chew SY AU - Fearnley IM AU - Walker JE TI - Resolution of the membrane domain of bovine complex I into subcomplexes: Implications for the structural organization of the enzyme SO - Biochemistry 2000 Jun 20;39(24):7229-7235 IS - 0006-2960 MH - Nadh-ubiquinone oxidoreductase MH - Cytochrome bc(1) complex MH - Heart-mitochondria MH - 3-dimensional structure MH - 2.8-angstrom resolution MH - Electron-microscopy MH - Proteins MH - Subunit MH - Dehydrogenase MH - Reductase AB - Complex I (NADH:ubiquinone oxidoreductase) purified from bovine heart mitochondria was treated with the detergent N,N-dimethyldodecylamine N-oxide (LDAO), The enzyme dissociated into two known subcomplexes, I alpha and I beta, containing mostly hydrophilic and hydrophobic subunits, and a previously undetected fragment referred to as I gamma. Subcomplex I gamma contains the hydrophobic subunits ND1, ND2, ND3, and ND4L which are encoded in the mitochondrial genome, and the nuclear-encoded subunit KFYI. During size-exclusion chromatography in the presence of LDAO, subcomplex I alpha lost several subunits and formed another characterized subcomplex known as I lambda, Similarly, subcomplex I beta dissociated into two smaller subcomplexes, one of which contains the hydrophobic subunits ND4 and ND5; subcomplex I gamma released a fragment containing ND1 and ND2. These results suggest that in the intact complex subunits ND1 and ND2 are likely to be in a different region of the membrane domain than subunits ND4 and ND5. The compositions of the various subcomplexes and fragments of complex I provide an organization of the subunits of the enzyme in the framework of the known low resolution structure of the enzyme. [References: 37] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Walker JE MRC, Dunn Human Nutr Unit Hills Rd Cambridge CB2 2XY England MRC, Dunn Human Nutr Unit Cambridge CB2 2XY England MRC, Mol Biol Lab Cambridge CB2 2QH England 58 UI - 326CF-0022 AU - Doran E AU - Halestrap AP TI - Cytochrome c release from isolated rat liver mitochondria can occur independently of outer-membrane rupture: possible role of contact sites SO - Biochemical Journal 2000 Jun 1;348(Part 2):343-350 IS - 0264-6021 MH - Adenylate kinase MH - Apoptosis MH - Bax MH - Mitochondrial permeability transition MH - Vdac MH - Adenine-nucleotide translocase MH - Permeability transition pore MH - Dependent anion channel MH - Cell-death MH - Caspase activation MH - Heart-mitochondria MH - Cyclophilin-d MH - Triton x-100 MH - Apoptosis MH - Bax AB - Percoll-purified rat liver mitochondria were shown to contain BAX dimer and rapidly (<2 min) release 5-10% of their cytochrome c when incubated in a standard KCl incubation medium under energized conditions. This release was not accompanied by release of adenylate kinase (AK), another intermembrane protein, and was not inhibited by Mg2+, dATP, inhibitors of the permeability transition or ligands of the peripheral benzodiazepine receptor. However, release was greatly reduced by the presence of 5% (w/v) dextran (40 kDa), which caused a decrease in the light scattering (A(520)) of mitochondrial suspensions. Dextran also inhibited both mitochondrial oxidation of exogenous ferrocytochrome c in the presence of rotenone and antimycin, and respiratory-chain-driven reduction of exogenous ferricytochrome c. Hypo-osmotic medium or digitonin treatment of mitochondria caused a large additional release of both cytochrome c and AK that was not blocked by dextran. Polyaspartate, which stabilizes the low conductance state of the voltage-dependent anion channel (VDAC), increased cytochrome c release. VDAC and BAX are both found at the contact sites between the inner and outer membranes and dextran is known to stabilize these contact sites in isolated mitochondria. Thus our data suggest that regulation of a specific permeability pathway for cytochrome c may be mediated by changes in protein-protein interactions within contact sites. The adenine nucleotide translocase is known to bind to VDAC and thus provides an additional link between the specific cytochrome c release pathway and the permeability transition. [References: 45] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Halestrap AP Univ Bristol, Sch Med Sci, Dept Biochem Bristol BS8 1TD Avon England Univ Bristol, Sch Med Sci, Dept Biochem Bristol BS8 1TD Avon England 59 UI - 327HD-0001 AU - Nath S AU - Jain S TI - Kinetic modeling of ATP synthesis by ATP synthase and its mechanistic implications SO - Biochemical & Biophysical Research Communications 2000 Jun 16;272(3):629-633 IS - 0006-291X MH - Atp synthase MH - F1f0 MH - Kinetic model MH - Molecular mechanism MH - Torsional mechanism MH - Kinetic parameters MH - Competitive inhibition MH - Biological implications MH - Rotation MH - F-1-atpase MH - F1-atpase MH - F1 MH - Unisite MH - Sub