1 UI - 428LR-0020 AU - Mitchell-Innes BA AU - Pitcher GC AU - Probyn A TI - Productivity of dinoflagellate blooms on the west coast of South Africa, as measured by natural fluorescence SO - South African Journal of Marine Science-Suid-Afrikaanse Tydskrif vir Seewetenskap 2000;22:273-284 IS - 0257-7615 MH - Solar-stimulated fluorescence MH - Benguela upwelling system MH - Marine-phytoplankton MH - Red-tide MH - Photosynthesis MH - Pacific MH - Chlorophyll MH - Populations MH - Irradiance MH - Migration AB - The biomass and productivity of phytoplankton populations inshore on the west coast of South Africa were investigated towards the end of the upwelling season, a period when high-biomass dinoflagellate blooms are common. Productivity was estimated from natural fluorescence measurements (P-NP) using photosynthesis (P) v. irradiance (E) relationships (P-E) and by means of the in situ C-14-method (P-C). A linear regression of P-NF productivity against P-C and P-E productivities yielded a slope of 0.911 and an r(2) of 0.83 (n = 41). Physical and biological variability was high inshore. reflecting alternating periods of upwelling and quiescence. Mean chlorophyll inshore (within a 12 m water column) ranged from 0.7 to 57.8 (mean = 8.9) mg m(-3), mean P-NF productivity ranged from 8.4 to 51.0 (mean = 24.6) mgC.m(-3).h(-1) and daily integral P-NF productivity from 0.8 to 4.8 (mean = 2.3) gC.m(-2) day(-1). Transects sampled during active and relaxation phases of upwelling had different chlorophyll distributions. High chlorophyll concentrations (sometimes > 50 mg.m(-3)) were associated with surface blooms within the region of the upwelling front. Estimates of daily water-column PNF productivity within these frontal blooms ranged from 4.0 to 5.6 gC.m(-2) day(-1). With relaxation of wind stress, blooms dominated by dinoflagellates flooded shorewards and often formed red tides. Chlorophyll concentrations of > 175 mg.m(-3) and productivity rates > 500 mgC(.)m(-3.)h(-1) and 12 gC.m(-2.)day(-1) were measured during a particularly intense red tide. Offshore, the water column was highly stratified with a well-defined subsurface chlorophyll maximum layer within the pycnocline region. Estimates of daily water-column P-NF productivity ranged from 2.4 to 4.0 gC(.)m(-2)day(-1) offshore. The high productivity of shelf waters on the West Coast in late summer can be ascribed largely to dinoflagellate populations and their success in both upwelling systems and stratified conditions. [References: 35] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences IN - Mitchell-Innes BA Marine & Coastal Management Private Bag X2 ZA-8012 Cape Town South Africa Marine & Coastal Management ZA-8012 Cape Town South Africa 2 UI - 429NM-0001 AU - Pfannschmidt T AU - Allen JF AU - Oelmuller R TI - Principles of redox control in photosynthesis gene expression [Review] SO - Physiologia Plantarum 2001 May;112(1):1-9 IS - 0031-9317 MH - Chloroplast rna-polymerase MH - Mustard sinapis-alba MH - Phosphorelay signal-transduction MH - Electron-transport MH - Messenger-rna MH - Protein-phosphorylation MH - Response regulators MH - Plastoquinone pool MH - Light MH - Transcription AB - Light is one of the most important environmental factors influencing gene expression in photosynthetic organisms. In particular, genes for components of the photosynthetic machinery show light-dependent expression, In recent years, it has become clear that photosynthesis itself contributes important signals to this light control of gene expression by means of changes in the reduction/oxidation (redox) state of signalling molecules. Such changes in redox state are induced hy changes in quality and quantity of the incident light. Redox signalling mechanisms therefore provide photosynthesis with the possibility of acclimational changes in the structure of the photosynthetic apparatus via a feedback control of photosynthesis gene expression, The great variety of these signalling mechanisms is summarised under the term 'redox control'. In some cases, oxygen acts as a different environmental, light-independent stimulus of photosynthetic gene expression, providing an additional redox signal and a different kind of redox control. In this review, we summarise present knowledge about such redox control mechanisms and analyse common properties as well as differences in the various signalling pathways. We suggest that there is an urgent need for a clear distinction between different hinds of redox control. Accordingly, we propose a categorisation into perceptional and transductional redox control. These categories are defined and examples given. The generalisation and comparability of results obtained in different physiological test systems and species are critically discussed. [References: 73] LG - English PT - Review SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Oelmuller R Univ Jena, Dept Plant Physiol, Inst Gen Bot Dornburger Str 159 D-07743 Jena Germany Univ Jena, Dept Plant Physiol, Inst Gen Bot D-07743 Jena Germany Univ Lund SE-22100 Lund Sweden 3 UI - 429NM-0002 AU - Hideg E AU - Ogawa K AU - Kalai T AU - Hideg K TI - Singlet oxygen imaging in Arabidopsis thaliana leaves under photoinhibition by excess photosynthetically active radiation SO - Physiologia Plantarum 2001 May;112(1):10-14 IS - 0031-9317 MH - Reaction center protein MH - Photosystem-ii MH - Epr spectroscopy MH - Degradation MH - Involvement MH - Light MH - Inhibition MH - States AB - Arabidopsis thaliana leaves were infiltrated with DanePy (3-(N -diethylaminoethyl) -N- dansyl)aminomethyl - 2,5-dihydro - 2, 2,5,5-tetramethyl-1H-pyrrole), a double, fluorescent and spin sensor of singlet oxygen, DanePy fluorescence was imaged by laser scanning microscopy. We found that DanePy penetrated into chloroplasts but did not alter the functioning of the photosynthetic electron transport as assessed by chlorophyll fluorescence induction. In imaging, DanePy fluorescence was well distinct from chlorophyll fluorescence. Photoinhibition by excess photosynthetically active radiation caused quenching of DanePy fluorescence in the chloroplasts but not in other cell compartments. When leaves were infiltrated with dansyl, the fluorescent group in DanePy, there was no fluorescence quenching during photoinhibition, This shows that the fluorescence quenching of DanePy is caused by the conversion of its pyrrol group into nitroxide, i.e. it was caused by the reaction of singlet oxygen with the double sensor and not by artifacts, These data provide direct experimental evidence for the localization of singlet oxygen production to chloroplasts in vivo. [References: 26] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Hideg E Biol Res Ctr, Inst Plant Biol POB 521 H-6701 Szeged Hungary Biol Res Ctr, Inst Plant Biol H-6701 Szeged Hungary Res Inst Biol Sci Okayama Okayama 7161241 Japan Univ Pecs, Dept Organ & Med Chem H-7643 Pecs Hungary 4 UI - 429NM-0007 AU - Deo PM AU - Biswal B TI - Response of senescing cotyledons of clusterbean to water stress in moderate and low light: Possible photoprotective role of ss-carotnene SO - Physiologia Plantarum 2001 May;112(1):47-54 IS - 0031-9317 MH - Ii reaction centers MH - Photosystem-ii MH - Beta-carotene MH - D1 protein MH - Lipid-peroxidation MH - Rapid turnover MH - Plants MH - Photoinhibition MH - Chloroplasts MH - Senescence AB - Senescence of clusterbean (Cyamopsis tetragonoloba L,) cotyledons in moderate light (12 W m(-2)) brings about a loss in the pigments, enhanced lipid peroxidation and a decline in PS II photochemical activity without any loss either in D1 protein or in the level of beta -carotene, The senescence syndrome is aggravated in the cotyledons of water-stressed seedlings with an increase in thylakoid lipid peroxidation, a decline in the level of beta -carotene and a quantitative loss in the D1 protein, Loss of the protein, however, is arrested in the seedlings experiencing water stress at low light (3 W m-2) intensity that correlates with the stability in the level of beta -carotene and a slow rate of lipid peroxidation, Loss of the protein in moderate light is attributed to water-stress sensitized photoinhibitory damage. The data on changes in the components of xanthophyll cycle suggest the low activity of the cycle both during senescence and water stress, It is, therefore, concluded that beta -carotene may contribute to the assembly and stability of the D1 protein during senescence and water stress in clusterbean cotyledons. [References: 41] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Biswal B Sambalpur Univ, Sch Life Sci, Biochem Lab Jyoti Vihar 768019 Orissa India Sambalpur Univ, Sch Life Sci, Biochem Lab Jyoti Vihar 768019 Orissa India GM Autonomous Coll, Dept Bot Sambalpur 768004 Orissa India 5 UI - 429PJ-0061 AU - Trinkunas G AU - Herek JL AU - Polivka T AU - Sundstrom V AU - Pullerits T TI - Exciton delocalization probed by excitation annihilation in the light-harvesting antenna LH2 SO - Physical Review Letters 2001 Apr 30;86(18):4167-4170 IS - 0031-9007 MH - Rhodobacter-sphaeroides MH - Photosynthetic system MH - Rhodospirillum-rubrum MH - Purple bacteria MH - Complex MH - Transition MH - Energy AB - Singlet-singlet annihilation is used to study exciton delocalization in the light harvesting antenna complex LH2 (B800-B850) from the photosynthetic purple bacterium Rhodobacter sphaeroides. The characteristic femtosecond decay constants of the high intensity isotropic and the low intensity anisotropy kinetics of the B850 ring are related to the hopping time tau (h) and the coherence length N-coh Of the exciton. Our analysis yields Ncoh = 2.8 +/- 0.4 and tau (h) = 0.27 +/- 0.05 ps. This approach can be seen as an extension to the concept of the spectroscopic ruler. [References: 23] LG - English PT - Article SB - Current Contents(R)/Physical, Chemical & Earth Sciences IN - Pullerits T Univ Lund, Dept Chem Phys POB 124 S-22100 Lund Sweden Univ Lund, Dept Chem Phys S-22100 Lund Sweden Inst Phys LT-2600 Vilnius Lithuania 6 UI - 429ZK-0014 AU - Strong GL AU - Bannister P AU - Burritt DJ TI - New Zealand mistletoes have equal or lower capacities for electron transport than their hosts SO - New Zealand Journal of Botany 2001 Mar;39(1):171-174 IS - 0028-825X MH - Loranthaceae MH - Viscaceae MH - New zealand MH - Mistletoe MH - Chlorophyll florescence MH - Electron transport rate MH - Photon flux density MH - Par MH - Co2 assimilation MH - Xylem-tapping mistletoes AB - Previous work on the New Zealand mistletoes Ileostylus micranthus and Tupeia antarctica indicates that these mistletoes have lower maximum electron transport rates (ETRmax) than their hosts. We extend this research by testing seven of the eight extant endemic New Zealand mistletoes using chlorophyll fluorescence measurements. In addition, we examined whether loranthaceous (Alepis flavida, Ileostylus micranthus, Peraxilla colensoi, P. tetrapetala, Tupeia antarctica) and viscaceous mistletoes (Korthalsella lindsayi, K. salicornioides) differed in their capacities for electron transport. Electron transport rates were significantly related to photosynthetically active photon flux densities (PPFD), Overall, mistletoes had significantly lower (110 +/- 18 mol m(-2) s(-1)) ETRmax than their hosts (219 +/- 43 mol m(-2) s(-1)), but some specific host-mistletoes pairs showed no significant difference in ETRmax. There was no clear distinction in ETRmax between mistletoe families. We conclude that New Zealand mistletoes generally have lower electron transport rates at the same PPFD and, usually, lower photosynthetic capacities than their hosts. [References: 11] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences IN - Strong GL Univ Otago, Dept Bot POB 56 Dunedin New Zealand Univ Otago, Dept Bot Dunedin New Zealand 7 UI - 429JN-0027 AU - Tanamoto K AU - Iida T AU - Haishima Y AU - Azumi S TI - Endotoxic properties of lipid A from Comamonas testosteroni SO - MICROBIOLOGY-SGM 2001 May;147(Part 5):1087-1094 IS - 1350-0872 MH - Lipopolysaccharide MH - Lps MH - Biological activity of lipid a MH - Endotoxin MH - Porphyromonas-gingivalis lipopolysaccharide MH - Rhodopseudomonas-sphaeroides MH - Nontoxic lipopolysaccharide MH - Human monocytes MH - C3h/hej mice MH - A component MH - Antagonist MH - Induction MH - Analogs MH - Line AB - The lipid A from comamonas testosteroni has been isolated and its complete chemical structure determined [Iida, T., Haishima, Y., Tanaka, A., Nishijima, K., Saito, S. & Tanamoto, K. (1996). Eur J Biochem 237, 468-475]. In this work, the relationship between its chemical structure and biological activity was studied. The lipid A was highly homogeneous chemically and was characterized by the relatively short chain length (C-10) of the 3-hydroxy fatty acid components directly bound to the glucosamine disaccharide backbone by either amide or ester linkages. The lipid A exhibited endotoxic activity in all of the assay systems tested (mitogenicity in mouse spleen cells; induction of tumour necrosis factor alpha release from both mouse peritoneal macrophages and mouse macrophage-like cell line J774-1, as well as from the human monocytic cell line THP-1; induction of nitric oxide release from J774-1 cells; Limulus gelation activity and lethal toxicity in galactosamine-sensitized mice) to the same extent as did 'Salmonella minnesota' lipid A or Escherichia coil LPS used as controls. The strong endotoxic activity of the C. testosteroni lipid A indicates that the composition of 3-hydroxydecanoic acid is not responsible for the low endotoxicity of the lipid A observed in members of the genus Rhodopseudomonas, as has previously been suggested. Furthermore, both the lack of a second acylation of the 3-hydroxy fatty acid attached at the 3' position, and the substitution of the hydroxyl group of the 3-hydroxy fatty acid attached at position 2, do not affect the manifestation of endotoxic activity or species specificity. [References: 30] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Tanamoto K Natl Inst Hlth Sci, Div Microbiol, Setagaya Ku 1-18-1 Kamiyoga Tokyo 1588501 Japan Natl Inst Hlth Sci, Div Microbiol, Setagaya Ku Tokyo 1588501 Japan 8 UI - 429MA-0003 AU - Aguirre-von-Wobeser E AU - Figueroa FL AU - Cabello-Pasini A TI - Photosynthesis and growth of red and green morphotypes of Kappaphycus alvarezii (Rhodophyta) from the Philippines SO - Marine Biology 2001 Apr;138(4):679-686 IS - 0025-3162 MH - Chlorophyll fluorescence MH - Solar-radiation MH - Eucheuma-denticulatum MH - Marine macrophytes MH - Doty doty MH - Photoinhibition MH - Light MH - Phycobilisomes MH - Responses MH - Plants AB - The effect of photosynthetic available radiation (PAR) levels, light quality, ultraviolet (UV) radiation, and temperature on photosynthesis, growth, and chlorophyll fluorescence was evaluated in red and green morphotypes of the rhodophyte Kappaphycus alvarezii (Doty) Doty under controlled conditions. Chlorophyll a and phycoerythrin (PE) levels were similar in the red and green morphotypes cultured under the same conditions, but phycocyanin (PC) and allophycocyanin (APC) levels were 2-fold greater in the green than in the red morphotype. Pigment characterization indicated that the overexpression of PC and APC masked the red pigmentation in the green morphotype, Maximum photosynthesis and photosynthetic efficiency were similar between the two morphotypes assayed at a wide temperature range, which was reflected in the similar growth rates observed in outdoor culture systems. In the green morphotype, photosynthetic efficiency increased 2-fold relative to the red morphotype when assayed with red light (lambda > 600 nm), indicating that photosynthetic characteristics are modified as a result of pigment variation in these morphotypes. Such increase in photosynthetic efficiency in the green morphotype, however, did not result in greater growth rates when cultured under white light. Short exposure to high levels of solar radiation (UV-A + UV-B + PAR), and filtered solar radiation (UV-A; PAR or PAR) decreased effective quantum yield (DeltaF/F-m') in both morphotypes. The reduction of DeltaF/F-m' values in the red and green morphotypes was accounted for by high levels of PAR and not by the UV-A + UV-B + PAR and UV-A + PAR treatments. Photoinhibition caused by UV-A, UV-B, or PAR was completely reversed within 30 h after incubations. Recovery rates from photoinhibition, however, were significantly reduced in the green morphotype when incubated with UV-B radiation. The results here suggest that the overexpression of pigments do not necessarily increase photosynthesis and growth in these morphotypes. [References: 30] LG - English PT - Article SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences IN - Cabello-Pasini A Univ Autonoma Baja California, Inst Invest Oceanol AP 453 Ensenada 22800 Baja California Mexico Univ Autonoma Baja California, Inst Invest Oceanol Ensenada 22800 Baja California Mexico Univ Autonoma Baja California, Fac Ciencias Marinas Ensenada 22800 Baja California Mexico Univ Malaga, Fac Ciencias, Dept Ecol E-29071 Malaga Spain 9 UI - 429BH-0014 AU - Link G AU - Berthold T AU - Bechtold M AU - Weidner JU AU - Ohmes E AU - Tang J AU - Poluektov O AU - Utschig L AU - Schlesselman SL AU - Thurnauer MC AU - Kothe G TI - Structure of the P-700(+) A(1)(-) radical pair intermediate in photosystem I by high time resolution multifrequency electron paramagnetic resonance: Analysis of quantum beat oscillations SO - Journal of the American Chemical Society 2001 May 9;123(18):4211-4222 IS - 0002-7863 MH - Photosynthetic reaction centers MH - Bacterial reaction centers MH - Rhodobacter-sphaeroides r-26 MH - Transient epr spectroscopy MH - Field-induced orientation MH - W-band epr MH - Primary donor MH - State p(700)(center-dot+)a(1)(center-dot-) MH - Single-crystals MH - Spin-resonance AB - The geometry of the secondary radical pair, P(700)(+)A(1)(-), in photosystem I (PSI) from the deuterated and N-15-substituted cyanobacterium Synechococcus lividus has been determined by high time resolution electron paramagnetic resonance (EPR), performed at three different microwave frequencies. Structural information is extracted from light-induced quantum bents observed in the transverse magnetization of P(700)(+)A(1)(-) at early times after laser excitation. A computer analysis of the two-dimensional Q-band experiment provides the orientation of the various magnetic tensors of P(700)(+)A(1)(-) with respect to a magnetic reference frame. The orientation of the cofactors of the primary donor in the g-tensor system of P-700(+) is then evaluated by analyzing time-dependent X-band EPR spectra, extracted from a two-dimensional data set. Finally, the cofactor arrangement of P(700)(+)A(1)(-) in the photosynthetic membrane is deduced from angular-dependent W-band spectra, observed fora magnetically aligned sample. Thus, the orientation of the g-tensor of P-700(+) with respect to a chlorophyll based reference system could be determined. The angle between the g(1)(Z) axis and the chlorophyll plane normal is found to be 29 +/- 7 degrees, while the g(1)(Y) axis lies in the chlorophyll plane. In addition, a complete structural model for the reduced quinone acceptor, A;, is evaluated. In this model, the quinone plane of Ar is found to be inclined by 68 +/- 7 degrees relative to the membrane plane, while the P-700(+)-A(1)(-) axis makes an angle of 35 +/- 6 degrees with the membrane normal. All of these values refer to the charge separated state, P(700)(+)A(1)(-), observed at low temperatures, where forward electron transfer to the iron-sulfur centers is partially blocked. Preliminary room temperature studies of P(700)(+)A(1)(-), employing X-band quantum beat oscillations, indicate a different orientation of A(-)(1); in its binding pocket. A comparison with crystallographic data provides information on the electron-transfer pathway in PSI. It appears that quantum beats represent excellent structural probes for the short-lived intermediates in the primary energy conversion steps of photosynthesis. [References: 63] LG - English PT - Article SB - Current Contents(R)/Life Sciences Current Contents(R)/Physical, Chemical & Earth Sciences IN - Kothe G Univ Freiburg, Dept Phys Chem Albertstr 21 D-79104 Freiburg Germany Univ Freiburg, Dept Phys Chem D-79104 Freiburg Germany Argonne Natl Lab, Div Chem Argonne, IL 60439 USA 10 UI - 430AV-0016 AU - Gordon-Smith DJ AU - Carbajo RJ AU - Yang JC AU - Videler H AU - Runswick MJ AU - Walker JE AU - Neuhaus D TI - Solution structure of a C-terminal coiled-coil domain from bovine IF1: The inhibitor protein of F-1 ATPase SO - Journal of Molecular Biology 2001 Apr 27;308(2):325-339 IS - 0022-2836 MH - Protein structure MH - Nmr spectroscopy MH - Coiled-coil MH - F-1 atpase MH - Inhibitor protein MH - Mitochondrial adenosine-triphosphatase MH - Amino-acid-sequence MH - Crystal-structure MH - Escherichia-coli MH - Electrostatic interactions MH - Oligomerization-state MH - Alpha MH - Purification MH - Orientation MH - Binding AB - Bovine IF1 is a basic, 84 amino acid residue protein that inhibits the hydrolytic action of the F1F0 ATP synthase in mitochondria under anaerobic conditions. Its oligomerization state is dependent on pH. At a pH value below 6.5 it forms an active dimer. At higher pH values, two dimers associate to form an inactive tetramer. Here, we present the solution structure of a C-terminal fragment of IF1 (44-84) containing all fire of the histidine residues present in the sequence. Most unusually, the molecule forms an anti-parallel coiled-coil in which three of the five histidine residues occupy key positions at the dimer interface. (C) 2001 Academic Press. [References: 50] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Neuhaus D MRC, Mol Biol Lab Hills Rd Cambridge CB2 2QH England MRC, Mol Biol Lab Cambridge CB2 2QH England MRC, Dunn Human Nutr Unit Cambridge CB2 2XY England 11 UI - 430AV-0018 AU - Brennan L AU - Turner DL AU - Fareleira P AU - Santos H TI - Solution structure of Methylophilus methylotrophus cytochrome c '': Insights into the structural basis of haem-ligand detachment SO - Journal of Molecular Biology 2001 Apr 27;308(2):353-365 IS - 0022-2836 MH - Cytochrome c '' MH - Ligand detachment MH - Disulfide bridge MH - Redox-bohr effect MH - Proton pump MH - C-type cytochromes MH - Rhodobacter-sphaeroides MH - Chemical-shifts MH - Paramagnetic metalloprotein MH - Perpendicular orientation MH - Relaxation measurements MH - Protein structures MH - Tocsy experiments MH - Cross relaxation MH - Proton-transfer AB - Cytochrome c" from Methylophilus methylotrophus is a monohaem protein with 124 amino acid residues. The iron has two histidine ligands in the oxidised form, one of which detaches and picks up a proton when the protein is reduced. Thus, both forms are paramagnetic. The structure of the oxidised form in solution, determined from NMR data is presented. The family of structures has an average backbone rmsd value of 0.53 Angstrom, and a heavy atom rmsd value of 0.95 Angstrom, within a target function range of 32 %. This structure is related to class I cytochromes with an additional helix at the N terminus. The haem-binding site occurs in a domain essentially lacking secondary structure motifs and the axial histidinyl residues were found in an unusual near perpendicular orientation. Moreover, a disulfide bridge is present, an uncommon structural feature among c-type cytochromes. The disulfide bridge, linking cysteine residues 96 and 104, forms a loop that confers rigidity and is essential to the detachment of the axial histidine (His95) as demonstrated by chemical disruption of the S-S bond. A route for protonation of the distal histidine involving haem propionate 17 is proposed and discussed in the light of available models for complex membrane proton pumps. (C) 2001 Academic Press. [References: 56] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Santos H Univ Nova Lisboa, Inst Tecnol Quim & Biol Rua Quinta Grande 6,Apt 127 P-2780156 Oeiras Portugal Univ Nova Lisboa, Inst Tecnol Quim & Biol P-2780156 Oeiras Portugal Univ Southampton, Dept Chem Southampton SO17 1BJ Hants England 12 UI - 429QF-0007 AU - Daneshvar MI AU - Hollis DG AU - Steigerwalt AG AU - Whitney AM AU - Spangler L AU - Douglas MP AU - Jordan JG AU - MacGregor JP AU - Hill BC AU - Tenover FC AU - Brenner DJ AU - Weyant RS TI - Assignment of CDC weak oxidizer group 2 (WO-2) to the genus Pandoraea and characterization of three new Pandoraea genomospecies SO - Journal of Clinical Microbiology 2001 May;39(5):1819-1826 IS - 0095-1137 MH - Fatty-acid composition MH - Isoprenoid quinone content MH - Sp-nov MH - Burkholderia-cepacia MH - Cystic-fibrosis MH - Comb-nov MH - Pseudomonas MH - Proposal AB - CDC weak oxidizer group 2 (WO-2) consists of nine phenotypically similar human clinical isolates received by the Centers for Disease Control and Prevention between 1989 and 1998. Four of the isolates were from blood, three were from sputum, and one each was from bronchial fluid and maxillary sinus. All are aerobic nonfermentative, motile gram-negative rods with one to eight polar flagella per cell. All grew at 25 and 35 degreesC and were positive for catalase, urease (usually delayed 3 to 7 days), citrate, alkalinization of litmus milk, oxidization of glycerol (weakly), and growth on MacConkey agar and in nutrient broth,without NaCl. All except one strain were oxidase positive with the Kovacs method, and all except one isolate weakly oxidized D-glucose. All were negative for oxidation of D-xylose, D-mannitol, lactose, sucrose, maltose, and 20 other carbohydrates, esculin hydrolysis, indole production, arginine dihydrolase, and lysine and ornithine decarboxylase. Only two of nine isolates reduced nitrate. Broth microdilution susceptibilities were determined for all strains against 13 antimicrobial agents. Most of the strains were resistant to ampicillin, extended spectrum cephalosporins, and aminoglycosides, including gentamicin, tobramycin, and amikacin, but they varied in their susceptibility to fluoroquinolones. High-performance liquid chromatographic and mass spectrometric analyses of the WO-2 group identified ubiquinone-8 as the major quinone component. The percent G+C of the WO-2 strains ranged from 65.2 to 70.7% (thermal denaturation method). All shared a common cellular fatty acid (CFA) profile, which was characterized by relatively large amounts (7 to 22%) of 16:1 omega 7c, 16:0, 17:0cyc, 18:1 omega 7c, and 19:0cyc(11-12); small amounts (1 to 3%) of 12:0 and 14:0; and eight hydroxy acids, 2-OH-12:0 (4%), 2-OH-14:0 (trace), 3-OH-14:0 (12%), 2-OH-16:1 (1%), 2 OH-16:0 (3%), 3-OH-16:0 (4%), 2-OH-18:1 (2%), and 2-011-19: 0cyc (3%). This profile is similar to the CFA profile of Pandoraea, a recently described genus associated with respiratory infections in cystic fibrosis patients (T. Coenye et al., Int. J. Syst. Evol. Microbiol., 50:887-899, 2000). Sequencing of the 16S rRNA gene (1,300 bp) for all nine strains indicated a high level (greater than or equal to 98.8%) of homogeneity with Pandoraea spp. type strains. DNA-DNA hybridization analysis (hydroxyapatite method; 70 degreesC) confirmed the identity of WO-2 with the genus Pandoraea and assigned three strains to Pandoraea apista and three to Pandoraea pnomenusa, and identified three additional ne,v genomospecies containing one strain each (ATCC BAA-108, ATCC BAA-109, ATCC BAA-110). This study also shows that Pandoraea isolates may be encountered in blood cultures from patients without cystic fibrosis. [References: 24] LG - English PT - Article SB - Current Contents(R)/Clinical Medicine Current Contents(R)/Life Sciences IN - Daneshvar MI CDCP, Div Bacterial & Mycot Dis, Natl Ctr Infect Dis, PHS,US Dept HHS 1600 Clifton Rd,Mailstop D11 Atlanta, GA 30333 USA CDCP, Div Bacterial & Mycot Dis, Natl Ctr Infect Dis, PHS,US Dept HHS Atlanta, GA 30333 USA CDCP, Hosp Infect Program, Natl Ctr Infect Dis, PHS,US Dept HHS Atlanta, GA 30333 USA 13 UI - 429QL-0003 AU - Conry RR AU - Tipton AA TI - A mononuclear molybdenum(V) mono-oxo biphenyl-2,2 '-dithiolate complex in which the metal resides within a cleft formed by the ligands and that exhibits N-(HS)-S-center dot center dot center dot hydrogen bonding in the solid state [Review] SO - Journal of Biological Inorganic Chemistry 2001 Apr;6(4):359-366 IS - 0949-8257 MH - Crystal structure MH - Molybdenum(v)-oxothiolate complex MH - Hydrogen bonding MH - X-ray-absorption MH - Dimethyl-sulfoxide reductase MH - Crystal-structure MH - Xanthine-oxidase MH - Sulfite oxidase MH - Dmso reductase MH - Rhodobacter-capsulatus MH - Escherichia-coli MH - Active-sites MH - Spectroscopic characterization AB - The reaction of Mo(O)(2)(acac)(2), H2L (2,2'-dimercaptobiphenyl), and NEt3 produced the mononuclear Mo(V) complex Et3NH[Mo(O)(L)(2)] (1). Molybdenum mono-ore tetrathiolate complexes such as 1 are studied as potential structural or functional models for pyranopterin-containing molybdoenzymes. Complex 1 has been crystallographically characterized. The solid-state structure reveals that the molybdenum ion sits within a cleft formed by the biphenyl backbone of the ligands, providing some steric protection. In addition, there is a hydrogen bond between the amine hydrogen of [Et3NH](+) and one of the thiolate sulfur atoms. A difference in solution reactivity between 1 and a derivative without a hydrogen-bonding counterion suggests that hydrogen bonding occurs in solution also. There are two short S-S contacts End small S-Mo-S angles in the structure of 1 that may reflect a slight bonding interaction. Such short S-S distances and small angles have been found in a couple of other Mo-thiolate complexes and in many of the molybdoenzyme crystal structures. Further characterization df 1 by EPR, IR, and UV-vis spectroscopies, as well a's by cyclic voltammetry, is discussed and compared to known Mo(V)-oxo-tetrathiolate complexes as well as to relevant molybdoenzyme data. Reactions to generate Mo(VI) complexes from 1 resulted in net oxidation at the ligand to form its disulfide derivative, which dissociated from the metal center. This result suggests that modifications to the ligand to prevent this process are needed. [References: 107] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Conry RR Colby Coll, Dept Chem 5764 Mayflower Hill Waterville, ME 04901 USA Colby Coll, Dept Chem Waterville, ME 04901 USA Univ Nevada, Dept Chem Reno, NV 89557 USA 14 UI - 429QL-0010 AU - Albela B AU - Chottard G AU - Girerd JJ TI - Biomimetic approach to the oxygen evolving center: resonance Raman investigation of a manganese mu-oxo dimer in three oxidation states SO - Journal of Biological Inorganic Chemistry 2001 Apr;6(4):430-434 IS - 0949-8257 MH - Photosystem ii MH - Oxygen evolving center MH - Resonance raman MH - Manganese mu-oxo complexes MH - Phenolate MH - Spectroscopic properties MH - Crystal-structures MH - Complexes MH - Photosynthesis MH - Relevance MH - Dioxygen MH - Proteins MH - Spectra MH - Storage MH - Models AB - A biologically relevant dinuclear manganese mono-mu -oxo complex with a bound phenolate ligand in three oxidation states, (III,III), (III,TV) and (IV,IV), was studied using resonance Raman spectroscopy. Depending upon the excitation frequency, phenolate vibrations or mu -oxo vibrations were enhanced, which allowed us to assign the UV-visible absorption spectra. In the case of the mixed valence species (III,IV), the mu -oxo vibration at 854 cm(-1) has been assigned by isotopic substitution ((H2O)-O-18) to v(as)(Mn-O-Mn). This preferential enhancement of the asymmetric vibration stresses the asymmetric character of the bridge. [References: 18] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Chottard G Univ Paris 06, Lab Chim Inorgan & Mat Mol, CNRS, ESA 7071 F-75252 Paris 05 France Univ Paris Sud, Chim Inorgan Lab, CNRS, UMR 8613 F-91405 Orsay France 15 UI - 429QL-0012 AU - Kummerle R AU - Gaillard J AU - Kyritsis P AU - Moulis JM TI - Intramolecular electron transfer in [4Fe-4S] proteins: estimates of the reorganization energy and electronic coupling in Chromatium vinosum ferredoxin SO - Journal of Biological Inorganic Chemistry 2001 Apr;6(4):446-451 IS - 0949-8257 MH - Chromatium vinosum MH - Ferredoxins MH - Electron transfer MH - Iron-sulfur proteins MH - Iron-sulfur proteins MH - 2<4fe-4s> ferredoxin MH - Rhodobacter-sphaeroides MH - Photosystem-i MH - Clostridium-pasteurianum MH - Temperature-dependence MH - Rate-constant MH - Clusters MH - Reduction MH - Resolution AB - The semi-classical electron transfer theory has been very successful in describing reactions occurring in biological systems, but the relevant parameters in the case of iron-sulfur proteins remain unknown. The recent discovery that 2[4Fe-4S] proteins homologous to Chromatium vinosum ferredoxin contain clusters with different reduction potentials now gives the opportunity to study the dependence of the intramolecular electron transfer rate between these clusters as a function of the driving force. This work shows how decreasing the reduction potential difference between the clusters by site-directed mutagenesis of C. vinosum ferredoxin modifies the rate of electron hopping between the two redox sites of the protein by measuring the line broadening of selected H-1 NMR signals. Beside the shifts of the reduction potentials, no signs of large structural changes or of significant alterations of the intrinsic kinetic parameters among the different variants of C. vinosum ferredoxin have been found. A reorganization energy of less than 0.5 eV was deduced from the dependence of the electron transfer rates with the reduction potential difference, This small value is associated with a weak electronic coupling between the two closely spaced clusters. This set of parameters, determined for the first time in an iron-sulfur protein, may help to explain how efficient vectorial electron transfer occurs with a small driving force in the many enzymatic systems containing a 2[4Fe-4S] domain. [References: 44] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Moulis JM CEA Grenoble, DBMS MEP 17 Ave Martyrs F-38054 Grenoble 9 France CEA Grenoble, DBMS MEP F-38054 Grenoble 9 France CEA Grenoble, DRFMC SCIB F-38054 Grenoble France Univ Florence, CERM, Magnet Resonance Ctr I-50019 Sesto Fiorentino Italy Univ Athens, Dept Chem, Inorgan Chem Lab Athens 15771 Greece 16 UI - 429QQ-0067 AU - Tanabe M AU - Nishio K AU - Iko Y AU - Sambongi Y AU - Iwamoto-Kihara A AU - Wada Y AU - Futai M TI - Rotation of a complex of the gamma subunit and c ring of Escherichia coli ATP synthase - The rotor and stator are interchangeable SO - Journal of Biological Chemistry 2001 May 4;276(18):15269-15274 IS - 0021-9258 MH - H+-atpase MH - Proton translocation MH - Epsilon-subunit MH - Cross-linking MH - F-atpase MH - Energy transduction MH - Structural-changes MH - Molecular machine MH - F1f0 MH - Oligomer AB - ATP synthase (F0F1) transforms an electrochemical proton gradient into chemical energy (ATP) through the rotation of a subunit assembly. It has been suggested that a complex of the gamma subunit and c ring (c(10-14)) of F0F1 could rotate together during ATP hydrolysis and synthesis (Sambongi, Y., Iko, Y., Tanabe, M., Omote, H., Iwamoto-Kihara, A., Ueda, I., Yanagida, T,, Wade, Y., and Futai, M. (1899) Science 286, 1722-1724), We observed that the rotation of the c ring with the cI28T mutation (c subunit cIle-28 replaced by Thr) was less sensitive to venturicidin than that of the wild type, consistent with the antibiotic effect on the cI28T mutant and wild-type ATPase activities (Fillingame, R. H., Oldenburg, M., and Fraga, D, (1991) J, Biol. Chem. 266, 20934-20939), Furthermore, we engineered F0F1 to see the alpha (3)beta (3) hexamer rotation; a biotin tag was introduced into the alpha or beta subunit, and a His tag was introduced into the c subunit, The engineered enzymes could be purified by metal affinity chromatography and density gradient centrifugation. They were immobilized on a glass surface through the c subunit, and an actin filament was connected to the alpha or beta subunit, The filament rotated upon the addition of ATP and generated essentially the same frictional torque as one connected to the c ring. These results indicate that the gamma epsilonc(10-14) complex is a mechanical unit of the enzyme and that it can be used as a rotor or a stator experimentally, depending on the subunit immobilized. [References: 43] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Futai M Osaka Univ, ISIR, Div Biol Sci Osaka 5670047 Japan Osaka Univ, ISIR, Div Biol Sci Osaka 5670047 Japan Univ Tokyo, Grad Sch Arts & Sci, Dept Life Sci Tokyo 1538902 Japan 17 UI - 429UH-0029 AU - Poggio S AU - Osorio A AU - Corkidi G AU - Dreyfus G AU - Camarena L TI - The N terminus of FliM is essential to promote flagellar rotation in Rhodobacter sphaeroides SO - Journal of Bacteriology 2001 May;183(10):3142-3148 IS - 0021-9193 MH - Bacillus-subtilis chemotaxis MH - Gram-negative bacteria MH - Salmonella-typhimurium MH - Escherichia-coli MH - Switch protein MH - Basal body MH - Motor MH - Chey MH - Complex MH - Ring AB - FliM is part of the flagellar switch complex. Interaction of this protein with phospbo-CheY (CbeY-P) through its N terminus constitutes the main information relay point between the chemotactic system and the flagellum, In this work, we evaluated the role of the N terminus of FliM in the swimming behavior of Rhodobacter sphaeroides. Strains expressing the FliM protein with substitutions in residues previously reported in Escherichia coli as being important for interaction with CheY showed an increased stop frequency compared with wild-type cells. In accordance, we observed that R, sphaeroides cells expressing FliM lacking either the first 13 or 20 amino acids from the N terminus showed a stopped phenotype. We show evidence that FliM Delta 13 and FliM Delta 20 are stable proteins and that cells expressing them allow flagellin export at levels indistinguishable from those detected for the wild-type strain. These results suggest that the N-terminal region of FliM is required to promote swimming in this bacterium. The role of CheY in controlling flagellar rotation in this organism is discussed. [References: 45] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Camarena L Univ Nacl Autonoma Mexico, Inst Invest Biomed, Dept Mol Biol Ap Postal 70-228 Mexico City 04510 DF Mexico Univ Nacl Autonoma Mexico, Inst Invest Biomed, Dept Mol Biol Mexico City 04510 DF Mexico Univ Nacl Autonoma Mexico, Dept Mol Genet, Inst Fisiol Celular Mexico City 04510 DF Mexico UNAM, Ctr Instrumentos, Inst Biotecnol, Lab Procesamiento Imagenes & Vis Morelos Mexico 18 UI - 429UH-0033 AU - Cross R AU - Lloyd D AU - Poole RK AU - Moir JWB TI - Enzymatic removal of nitric oxide catalyzed by cytochrome c ' in Rhodobacter capsulatus SO - Journal of Bacteriology 2001 May;183(10):3050-3054 IS - 0021-9193 MH - Reversible binding MH - Complex MH - Flavohemoglobin MH - Respiration MH - Bacterium MH - Cells MH - Hmp AB - Cytochrome c' from Rhodobacter capsulatus has been shown to confer resistance to nitric oxide (NO). In this study, we demonstrated that the amount of cytochrome c' synthesized for buffering of NO is insufficient to account for the resistance to WO but that the cytochrome-dependent resistance mechanism involves the catalytic breakdown of NO, under aerobic and anaerobic conditions. Even under aerobic conditions, the NO removal is independent of molecular oxygen, suggesting cytochrome c' is a NO reductase, Indeed, we have measured the product of NO breakdown to be nitrous oxide (N2O), thus showing that cytochrome c' is behaving as a NO reductase, The increased resistance to NO conferred by cytochrome c is distinct from the NO reductase pathway that is involved in denitrification, Cytochrome c' is not required for denitrification, but it has a role in the removal of externally supplied NO. Cytochrome c' synthesis occurs aerobically and anaerobically but is partly repressed under denitrifying growth conditions when other NO removal systems are operative. The inhibition of respiratory oxidase activity of R, capsulatus by NO suggests that one role for cytochrome c' is to maintain oxidase activity when both NO and O-2 are present. [References: 18] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Moir JWB Univ Sheffield, Dept Mol Biol & Biotechnol Firth Court,Western Bank Sheffield S10 2TN S Yorkshire England Univ Sheffield, Dept Mol Biol & Biotechnol Sheffield S10 2TN S Yorkshire England Univ Wales, Sch Pure & Appl Biol Cardiff CF1 3TL S Glam Wales 19 UI - 430KV-0004 AU - Shen LL AU - Zhang XD AU - Zhang QY TI - Quantum chemistry study of proteins in bacterial photosynthetic reaction center SO - International Journal of Quantum Chemistry 2001 May 15;83(1):30-40 IS - 0020-7608 MH - Electronic structure of protein MH - Photosynthetic reaction center (prc) MH - Hf ab initio MH - Overlapping-dimer approximation (oda) MH - Extended negative factor counter (enfc) method MH - Bacteriochlorophyll-b dimer MH - Electron-transfer reactions MH - Induced structural-changes MH - Rhodopseudomonas-viridis MH - Hopping conductivity MH - Rhodobacter-sphaeroides MH - Proton-transfer MH - Pig insulin MH - Energy MH - Donor AB - Quantum chemistry study on proteins L and M in the Rhodopseudomononas viridis (Rh. viridis) photosynthetic reaction center (PRC) are presented. The calculations were performed at ab initio level with Clementi minimal basis set by means of the overlapping-dimer approximation (ODA)-extended negative factor counting (ENFC) method. Additional point charges were added to individual residues to simulated ionized aqueous environment of the proteins in the calculations. Meanwhile, the electronic structure of protein complex MH (protein M plus the alpha -helix segment of protein H) was studied as well to examine the weak interaction between proteins M and H. As the first case of global quantum chemistry calculation for proteins in PRC, details of the electronic structure and the influence of proteins on the electron transfer process (ET) were studied. Moreover, new three-dimensional structure plots of subunit L and M were given based on the distribution of the components of frontier orbitals in order to more clearly understand the structure-function relationship of the proteins in electron transfer reactions. Calculation results indicated that the components of frontier orbitals are extremely localized at individual residues. Amino acid residues, having contributed to the frontier orbitals of protein L, are located at the flexible random area of L, while those having contributed to the frontier orbitals of protein M are located at the rigid alpha -helix area. This asymmetry of proteins L, and M provides new understanding the ET reaction that takes place mainly along branch L in the PRC of Rh. viridis. Meanwhile, there is frontier orbital localized amino acid distribution around the V-shaped pocket areas of protein L (M) that were expected to have an important interaction with Q(A) (Q(B)) All results indicate that protein provided a heterogeneous environment for pigment molecules and some important interaction between protein residues and pigment molecules are worthy of further investigation. (C) 2001 John Wiley & Sons, Inc. [References: 39] LG - English PT - Article SB - Current Contents(R)/Physical, Chemical & Earth Sciences IN - Shen LL Chinese Acad Sci, Shanghai Inst Mat Med, DDDC Grp 294 Taiyuan Rd,Xuhui Dist Shanghai 200031 Peoples R China Chinese Acad Sci, Inst Chem, State Key Lab Struct Chem Unstable & Stable Speci, Ctr Mol Sci Beijing 100080 Peoples R China 20 UI - 430ED-0016 AU - Fathir I AU - Mori T AU - Nogi T AU - Kobayashi M AU - Miki K AU - Nozawa T TI - Structure of the H subunit of the photosynthetic reaction center from the thermophilic purple sulfur bacterium, Thermochromatium tepidum - Implications for the specific binding of the lipid molecule to the membrane protein complex SO - European Journal of Biochemistry 2001 May;268(9):2652-2657 IS - 0014-2956 MH - H subunit MH - Membrane protein MH - Thermochromatium MH - Puha MH - Q(b) site MH - Rhodobacter-sphaeroides MH - Chromatium-tepidum MH - Rhodopseudomonas-viridis MH - Proton-transfer MH - Rhodospirillum-rubrum MH - Crystal-structures MH - Electron-transfer MH - Resolution MH - Nucleotide MH - Antenna AB - The photosynthetic reaction center (RC) is a transmembrane protein complex that catalyzes light-driven electron transport across the photosynthetic membrane. The complete amino-acid sequence of the H subunit of the RC from a thermophilic purple sulfur bacterium, Thermochromatium tepidum, has been determined for the first time among purple sulfur bacteria. The H subunit consists of 259 amino acids and has a molecular mass of 28 187. The deduced amino-acid sequences of this H subunit showed a significant (40%) degree of identity with those from mesophilic purple nonsulfur bacteria. The determined primary structure of the H subunit was compared with the structures of mesophilic B. viridis and R. sphaeroides based on the three-dimensional structure of the H subunit from T. tepidum, which has been recently determined by X-ray crystallography. One lipid molecule was found in the crystal structure of the T. tepidum RC, and the head group of the lipid appears to be stabilized by the electrostatic interactions with the conserved basic residues in the H subunit. The above comparison has suggested the existence of a lipid-binding site on the molecular surface at which a lipid molecule can interact with the RC in a specific manner. [References: 28] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Nozawa T Grad Sch Engn, Dept Biomol Engn, Aoba Ku Aobayama 07 Sendai Miyagi 9808579 Japan Grad Sch Engn, Dept Biomol Engn, Aoba Ku Sendai Miyagi 9808579 Japan Kyoto Univ, Grad Sch Sci, Dept Chem, Sakyo Ku Kyoto Japan Tohoku Univ, Ctr Interdisciplinary Sci, Aoba Ku Sendai Miyagi Japan RIKEN, Harima Inst SPring 8 Mikazuki Hyogo Japan 21 UI - 430ED-0026 AU - Ruan KC AU - Xu CH AU - Yu Y AU - Li J AU - Lange R AU - Bec N AU - Balny C TI - Pressure-exploration of the 33-kDa protein from the spinach photosystem II particle SO - European Journal of Biochemistry 2001 May;268(9):2742-2750 IS - 0014-2956 MH - Conformational changes MH - Hydrostatic pressure MH - Spinach particle MH - Protein denaturation MH - Photosynthetic oxygen-evolution MH - Derivative uv-spectroscopy MH - High hydrostatic-pressure MH - Conformational drift MH - Ribonuclease-a MH - Dehydrogenase MH - Denaturation MH - Chymotrypsinogen MH - Cryoinactivation MH - Reconstitution AB - The 33-kDa protein isolated from the spinach photosystem II particle is an ideal model to explore high-pressure protein-unfolding. The protein has a very low free energy as previously reported by chemical unfolding studies, suggesting that it must be easy to modulate its unfolding transition by rather mild pressure. Moreover, the protein molecule consists of only one tryptophan residue (Trp241) and eight tyrosine residues, which can be conveniently used to probe the protein conformation and structural changes under pressure using either fluorescence spectroscopy or fourth derivative UV absorbance spectroscopy. The different experimental methods used in the present study indicate that at 20 degreesC and pH 6, the 33-kDa protein shows a reversible two-state unfolding transition from atmospheric pressure to about 180 MPa. This value is much lower than those found for the unfolding of most proteins studied so far. The unfolding transition induces a large red shift of the maximum fluorescence emission of 34 nm (from 316 nm to 350 nm). The change in standard free energy (DeltaG(o)) and in volume (DeltaV) for the transition at pH 6.0 and 20 degreesC are -14.6 kJ.mol(-1) and -120 mL.mol(-1), respectively, in which the DeltaG(o) value is consistent with that obtained by chemical denaturation. We found that pressure-induced protein unfolding is promoted by elevated temperatures, which seem largely attributed to the decrease in the absolute value of DeltaG(o) (only a minor variation was observed for the DeltaV value). However, the promotion of the unfolding by alkaline pH seems mainly related to the increase in DeltaV without any significant changes in DeltaG(o). It was also found that NaCl significantly protects the protein from pressure-induced unfolding. In the presence of 1 m NaCl, the pressure needed to induce the half-unfold of the protein is shifted to a higher value (shift of 75 MPa) in comparison with that observed without NaCl. Interestingly, in the presence of NaCl, the value of DeltaV is significantly reduced whilst that of DeltaG(o) remains as before. The unfolding-refolding kinetics of the protein has also been studied by pressure-jump, in which it was revealed that both reactions are a two-state transition process with a relatively slow relaxation time of about 10(2) s. [References: 39] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Ruan KC Chinese Acad Sci, Shanghai Inst Biochem & Cell Biol 320 Yue Yang Rd Shanghai 200031 Peoples R China Chinese Acad Sci, Shanghai Inst Biol Sci, Inst Plant Physiol Beijing 100864 Peoples R China CNRS, IFR 24, INSERM, U128 Montpellier France Chinese Acad Sci, Shanghai Inst Biol Sci, Inst Biochem & Cell Biol Beijing 100864 Peoples R China 22 UI - 429HL-0005 AU - Kashino Y AU - Koike H AU - Satoh K TI - An improved sodium dodecyl sulfate-polyacrylamide gel electrophoresis system for the analysis of membrane protein complexes SO - Electrophoresis 2001 Apr;22(6):1004-1007 IS - 0173-0835 MH - Sodium dodecyl sulfate-polyacrylamide gel MH - Electrophoresis MH - Low-molecular-weight polypeptide MH - Acrylamide MH - Protein complex MH - Photosystem-ii AB - Membrane protein complexes such as the reaction center complexes of oxygenic photosynthesis or the complex I of mitochondira are composed of many subunit polypeptides. To analyze their polypeptide compositions by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), a wide range of molecular sizes has to be resolved, especially in the low molecular mass range. We have improved the traditional Tris/HCl buffer systems adopting a Tris/2-(N-morpholino)ethanesulfonic acid (MES) buffer system containing 6 M urea. This gel system was used with an 18-24% acrylamide gradient for the separation of polypeptides with molecular masses from below 5 kDa to over 100 kDa. This buffer system can also be applied to the usual uniform concentration of acrylamide gel and also to minislab gels. [References: 11] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Kashino Y Himeji Inst Technol, Fac Sci, Dept Life Sci Harima Sci Garden City Hyogo 6781297 Japan Himeji Inst Technol, Fac Sci, Dept Life Sci Harima Sci Garden City Hyogo 6781297 Japan 23 UI - 429MN-0015 AU - Simonson T TI - Macromolecular electrostatics: continuum models and their growing pains [Review] SO - Current Opinion in Structural Biology 2001 Apr;11(2):243-252 IS - 0959-440X MH - Free-energy calculations MH - Photosynthetic reaction centers MH - Molecular-dynamics simulations MH - Protein-protein interactions MH - Poisson-boltzmann equation MH - Implicit solvation model MH - Generalized-born model MH - Enzyme active-site MH - Ligand-binding MH - Electron-transfer AB - Theoretical understanding of macromolecular electrostatics has advanced substantially over the past year. Continuum models have given promising results for calculating protein-ligand binding free energy differences, as well as pK(a)s and redox properties, particularly with explicit treatment of multiple conformers. Generalized Born and other techniques have led to the first molecular dynamics simulations of proteins and RNA with continuum solvent. Continuum and microscopic descriptions of dielectric relaxation have been critically compared. [References: 88] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Simonson T IGBMC, CNRS, Lab Struct Biol & Genom 1 Rue Laurent Fries F-67404 Strasbourg France IGBMC, CNRS, Lab Struct Biol & Genom F-67404 Strasbourg France 24 UI - 429CY-0013 AU - Estelle M TI - Proteases and cellular regulation in plants [Review] SO - Current Opinion in Plant Biology 2001 Jun;4(3):254-260 IS - 1369-5266 MH - Optimal photosynthetic performance MH - Carboxyl-terminal extension MH - Auxin response MH - Photosystem-ii MH - Ftsh protease MH - Arabidopsis-thaliana MH - Aux/iaa proteins MH - D1 protein MH - Degradation MH - Identification AB - Protein degradation is accomplished by a diverse collection of proteases. Recent studies have illustrated the importance of proteolysis in the control of many aspects of cellular regulation from photosynthesis to photomorphogenesis, in addition, new results point to a role for proteolysis in programmed cell death, circadian rhythm, and defense response in plants. [References: 44] LG - English PT - Review SB - Current Contents(R)/Agriculture, Biology & Environmental Sciences Current Contents(R)/Life Sciences IN - Estelle M Univ Texas, Inst Mol & Cellular Biol Austin, TX 78712 USA Univ Texas, Inst Mol & Cellular Biol Austin, TX 78712 USA 25 UI - 429CU-0015 AU - Borovykh IV AU - Kulik LV AU - Dzuba SA AU - Hoff AJ TI - Selective excitation in pulsed EPR of spin-correlated radical pairs: electron-electron interactions, zero-, single-, and double-quantum relaxation and spectral diffusion SO - Chemical Physics Letters 2001 Apr 20;338(2-3):173-179 IS - 0009-2614 MH - Photosynthetic reaction centers MH - Echo spectroscopy MH - Micelle MH - Tetraphenylhydrazine MH - Photolysis MH - Dependence MH - Lifetimes MH - Exchange MH - States MH - Eseem AB - Experiments are described in which a low-amplitude microwave pulse excites only one out of four allowed transitions of a spin-correlated radical pair (SCRP). A second high-amplitude pulse produces an FID whose temporal shape is strongly modulated with Frequencies determined by electron-electron spin-exchange and dipolar interactions. The dependence of the FID intensity on the delay between the two pulses is determined by the relaxation of populations of energy levels connected by allowed single-quantum transitions and by forbidden zero- and double-quantum transitions. The first direct measurement of the zero-quantum population relaxation rate for P(+)Q(A)(-) radical pairs in bacterial photosynthetic reaction centers shows it is temperature independent. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 21] LG - English PT - Article SB - Current Contents(R)/Physical, Chemical & Earth Sciences IN - Hoff AJ Leiden State Univ, Huygens Lab, Dept Biophys POB 9504 NL-2300 RA Leiden Netherlands Leiden State Univ, Huygens Lab, Dept Biophys NL-2300 RA Leiden Netherlands Russian Acad Sci, Inst Chem Kinet & Combust Novosibirsk 630090 Russia 26 UI - 430CR-0008 AU - Cormier A AU - Morin C AU - Zini R AU - Tillement JP AU - Lagrue G TI - In vitro effects of nicotine on mitochondrial respiration and superoxide anion generation SO - Brain Research 2001 May 4;900(1):72-79 IS - 0006-8993 MH - Nicotine MH - Mitochondria MH - Respiratory chain MH - Superoxide anion MH - Rat-brain MH - In-vivo MH - Electron-transport MH - Free-radicals MH - Smoking MH - Alzheimers MH - Pharmacology MH - Modulation MH - Receptors MH - Cotinine AB - In this study, we investigated the effects of nicotine on rat brain mitochondria. The polarographic studies determined the effects on the respiratory chain, whereas enzymatic assays and [H-3]-nicotine binding allowed us to precisely identify its target and site of action. The measurements of oxygen consumption showed a significantly concentration-dependent inhibition by nicotine (EC50 was 4.95x10(-11) M), and a maximal decrease of 23.90% at 10(-7) M. Nicotine bound to complex I of the respiratory chain and inhibited the NADH-Ubiquinone reductase activity. We also showed that nicotine and NADH were competitive on complex I. Effects of cotinine, the main nicotine metabolite, and nornicotine, were also investigated: nornicotine inhibited the mitochondrial respiration whereas cotinine did not. Because the complex I generates superoxide anion, we investigated the effects of nicotine, following NET oxidation, and showed that nicotine was able to inhibit this reactive oxygen species (ROS) generation by 15.74% with an EC50 of 2.02x10(-11) M. In conclusion, the present study shows that nicotine interacts with the complex I of brain mitochondrial respiratory chain and decreases ROS generation. This may explain a part of the beneficial and protective effects of nicotine in few neurodegenerative diseases, as suggested by many epidemiological studies. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 34] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Cormier A Fac Med Paris XII, Pharmacol Lab F-94010 Creteil France Fac Med Paris XII, Pharmacol Lab F-94010 Creteil France Hop A Chenevier, Ctr Tabacol F-94010 Creteil France 27 UI - 428YZ-0018 AU - Grosset AM AU - Gibney BR AU - Rabanal F AU - Moser CC AU - Dutton PL TI - Proof of principle in a de novo designed protein maquette: An allosterically regulated, charge-activated conformational switch in a tetra-alpha-helix bundle SO - Biochemistry 2001 May 8;40(18):5474-5487 IS - 0006-2960 MH - 4-helix bundle MH - Cytochrome bc(1) MH - Lactose permease MH - Domain movement MH - Heme-proteins MH - Lac repressor MH - Atp synthase MH - Native-like MH - Binding MH - Fluorescence AB - New understanding of the engineering and allosteric regulation of natural protein conformational switches (such as those that couple chemical and ionic signals, mechanical force, and electro/chemical free energy for biochemical activation, catalysis, and motion) can be derived from simple de novo designed synthetic protein models (maquettes). We demonstrate proof of principle of both reversible switch action and allosteric regulation in a tetra-alpha -helical bundle protein composed of two identical di-helical subunits containing heme coordinated at a specific position close to the disulfide loop region. Individual bundles assume one of two switch states related by large-scale mechanical changes: a syn-topology (helices of the different subunits parallel) or anti-topology (helices antiparallel). Both the spectral properties of a coproporphyrin probe appended to the loop region and the distance-dependent redox interaction between the hemes identify the topologies. Beginning from a syn-topology, introduction of ferric heme in each subunit (either binding or redox change) shifts the topological balance by 25-50-fold (1.9-2.3 kcal/mol) to an anti-dominance. Charge repulsion between the two internal cationic ferric hemes drives the syn- to anti-switch, as demonstrated in two ways. When fixed in the syn-topology, the second ferric heme binding is 25-80-fold (1.9-2.6 kcal/mol) weaker than the first, and adjacent heme redox potentials are split by 80 mV (1.85 kcal/mol), values that energetically match the shift in topological balance. Allosteric and cooperative regulation of the switch by ionic strength exploits the shielded charge interactions between the two hemes and the exposed, cooperative interactions between the coproporphyrin carboxylates. [References: 52] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Dutton PL Univ Penn, Dept Biochem & Biophys, Stellar Chance Labs 1005, Johnson Res Fdn Philadelphia, PA 19104 USA Univ Penn, Dept Biochem & Biophys, Stellar Chance Labs 1005, Johnson Res Fdn Philadelphia, PA 19104 USA 28 UI - 428YZ-0025 AU - Liu H AU - Hu YP AU - Savaraj N AU - Priebe W AU - Lampidis TJ TI - Hypersensitization of tumor cells to glycolytic inhibitors SO - Biochemistry 2001 May 8;40(18):5542-5547 IS - 0006-2960 MH - Drug-resistance MH - Rhodamine-123 MH - Mitochondria AB - The slow growth of cells in the inner core of solid tumors presents a form of multidrug resistance to most of the standard chemotherapeutic agents, which target the outer more rapidly dividing cells. However, the anaerobic environment of the more centrally located tumor cells also provides an opportunity to exploit their dependence on glycolysis for therapeutic gain. We have developed two in vitro models to investigate this possibility. Model A represents osteosarcoma wild-type (wt) cells treated with agents which inhibit mitochondrial oxidative phosphorylation (Oxphos) by interacting with complexes I, III, and V of the electron transport chain in different ways, i.e., rhodamine 123 (Rho 123), rotenone, antimycin A, and oligomycin. All of these agents were found to hypersensitize wt cells to the glycolytic inhibitor 2-deoxyglucose. Cells treated with Rho 123 also become hypersensitive to oxamate, an analogue of pyruvate, which blocks the step of glycolysis that converts pyruvate to lactic acid. Model B is rho (0) cells which have lost their mitochondrial DNA and therefore cannot undergo Oxphos. These cells are 10 and 4.9 times more sensitive to 2-deoxyglucose and oxamate, respectively, than wt cells. Lactic acid levels, which are a measure of anaerobic metabolism, were found to be >3 times higher in rho (0) than in wt cells. Moreover, when wt cells were treated with Rho 123, lactic acid amounts increased as a function of increasing Rho 123 doses. Under similar Rho 123 treatment, rho (0) cells did not increase their lactic acid levels. These data confirm that cell models A and B are similarly sensitive to glycolytic inhibitors due to their dependence on anaerobic metabolism. Overall, our in vitro results suggest that glycolytic inhibitors could be used to specifically target the slow-growing cells of a tumor and thereby increase the efficacy of current chemotherapeutic and irradiation protocols designed to kill rapidly dividing cells. Moreover, glycolytic inhibitors could be particularly useful in combination with anti-angiogenic agents, which, a priori, should make tumors more anaerobic. [References: 23] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Lampidis TJ Univ Miami, Sch Med, Dept Cell Biol & Anat POB 016960,Locater Code R-124 Miami, FL 33101 USA Univ Miami, Sch Med, Dept Cell Biol & Anat Miami, FL 33101 USA Sylvestor Comprehens Canc Ctr Miami, FL 33136 USA Univ Texas, MD Anderson Canc Ctr Houston, TX 77030 USA 29 UI - 428YZ-0029 AU - Permentier HP AU - Neerken S AU - Overmann J AU - Amesz J TI - A bacteriochlorophyll a antenna complex from purple bacteria absorbing at 963 nm SO - Biochemistry 2001 May 8;40(18):5573-5578 IS - 0006-2960 MH - Light-harvesting antenna MH - Energy-transfer MH - Rhodopseudomonas-viridis MH - Rhodobacter-sphaeroides MH - Photosynthetic unit MH - Nonsulfur bacterium MH - Gen-nov MH - Roseospirillum-parvum MH - Phototrophic bacteria MH - Charge separation AB - A recently isolated species of the photosynthetic purple sulfur bacteria, provisionally called strain 970, was investigated with respect to its antenna function by means of various spectroscopic techniques, including fluorescence and pump-probe absorption difference spectroscopy. The bacterium contains bacteriochlorophyll a and an as yet unidentified carotenoid, perhaps 3,4,3 ' ,4 ' -tetrahydrospirilloxanthin. It has a single antenna complex of the LH1 type, with a Q(y) absorption band situated at the unusually long wavelength of 963 nm at room temperature and 990 nm at 6 K. In contrast to many other species, the reaction center showed two well-separated absorption bands of bacteriopheophytin at 6 K, located at 747 and 762 nm. The primary electron donor showed a bleaching band centered at 925 nm upon phstooxidation. Thus, the energy gap between LH1 and the primary electron donor is quite large in this strain: 425 cm(-1). Nevertheless, trapping occurred with a time constant of 65 +/- 5 ps, similar to the rates observed in other purple bacteria. As in other species, no back-transfer from the reaction center to the antenna was observed. Our results show that strain 970 is a unique subject for the study of antenna and reaction center function and organization. [References: 45] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Permentier HP 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 Oldenburg, Inst Chem & Biol Meeres D-26111 Oldenburg Germany 30 UI - 429MJ-0001 AU - Lang AS AU - Beatty JT TI - The gene transfer agent of Rhodobacter capsulatus and "constitutive transduction" in prokaryotes [Review] SO - Archives of Microbiology 2001 Apr;175(4):241-249 IS - 0302-8933 MH - Gta MH - Gene transfer MH - Transduction MH - Rhodobacter capsulatus MH - Ctra MH - Ccka MH - Cell-cycle control MH - Rhodopseudomonas-capsulata MH - Evolutionary relationships MH - Caulobacter-crescentus MH - Aquatic environments MH - Methanococcus-voltae MH - Signal-transduction MH - Bacteriophages MH - Bacteria MH - Phage AB - Transduction, bacteriophage-mediated gene transfer, is thought to play an important role in the evolution of prokaryote genomes. Several gene transfer agents that resemble transducing phages have been found in diverse prokaryotes. This mini-review discusses these interesting agents of genetic exchange with a focus on the gene transfer agent (GTA) of Rhodobacter capsulatus, at present the only member of this group for which genetic information exists about the production of transducing particles. Production of GTA results from expression of genes that are similar to phage genes, yet transcription of these genes is dependent upon cellular (two-component) signaling proteins. The significance of these relationships, as well as the finding of GTA gene homologues in the bacterium Rhodopseudomonas palustris, is discussed. [References: 42] LG - English PT - Review SB - Current Contents(R)/Life Sciences IN - Beatty JT Univ British Columbia, Dept Microbiol & Immunol 300-6174 Univ Blvd Vancouver BC V6T 1Z3 Canada Univ British Columbia, Dept Microbiol & Immunol Vancouver BC V6T 1Z3 Canada 31 UI - 429MJ-0006 AU - Niebisch A AU - Bott M TI - Molecular analysis of the cytochrome bc(1)-aa(3) branch of the Corynebacterium glutamicum respiratory chain containing an unusual diheme cytochrome c(1) SO - Archives of Microbiology 2001 Apr;175(4):282-294 IS - 0302-8933 MH - Corynebacterium glutamicum MH - C-type cytochromes MH - Cytochrome aa(3) oxidase MH - Cytochrome bc(1) complex MH - Respiratory chain MH - Iron-sulfur protein MH - Escherichia-coli MH - Paracoccus-denitrificans MH - C-oxidase MH - Bradyrhizobium-japonicum MH - Terminal oxidases MH - Cloning vectors MH - Bc(1) complex MH - Heat-shock MH - Dna AB - In this work, the genes for cytochrome aa(3) oxidase and the cytochrome bc(1) complex in the gram-positive soil bacterium Corynebacterium glutamicum were identified. The monocistronic ctaD gene encoded a 65-kDa protein with all features typical for subunit I of cytochrome aa: oxidases. A ctaD deletion mutant lacked the characteristic 600 nm peak in redox difference spectra. and growth in glucose minimal medium was strongly impaired. The genes encoding subunit III of cytochrome aa3 ctaE) and the three characteristic subunits of the cytochrome bc(1), complex (qcrABC) were clustered in the order ctaE-qcrCAB. Analysis of the deduced primary structures revealed a number of unusual features: (1) cytochrome c(1) (QcrC, 30 kDa) contained two Cys-X-X-Cys-His motifs for covalent heme attachment, indicating that it is a diheme c-type cytochrome: (2) the 'Rieske' iron-sulphur protein (QcrA, 45 kDa) contained three putative transmembrane helices in the N-terminal region rather than only one; and (3) cytochrome b (QcrB, 60 kDa) contained, in addition to the conserved part with eight trans membrane helices, a C-terminal extension of about 120 amino acids, which presumably is located in the cytoplasm. Staining of C. glutamicum proteins for covalently bound heme indicated the presence of a single, membrane-bound c-type cytochrome with an apparent molecular mass of about 31 kDa. Since this protein was missing in a qcrCAB deletion mutant, it most likely corresponds to cytochrome c(1). Similar to the Delta ctaD mutant, the Delta qcrCAB mutant showed strongly impaired growth in glucose minimal medium. which indicates that the bc(1)-aa(3) pathway is the main route of respiration under these conditions. [References: 56] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Bott M KFA Julich GmbH, Forschungszentrum, Inst Biotechnol 1 Postfach 1913 D-52425 Julich Germany KFA Julich GmbH, Forschungszentrum, Inst Biotechnol 1 D-52425 Julich Germany 32 UI - 428YG-0014 AU - Velazquez I AU - Pardo JP TI - Kinetic characterization of the rotenone-insensitive internal NADH: Ubiquinone oxidoreductase of mitochondria from Saccharomyces cerevisiae SO - Archives of Biochemistry & Biophysics 2001 May 1;389(1):7-14 IS - 0003-9861 MH - Mitochondria MH - Inner membrane MH - Nadh dehydrogenase MH - Saccharomyces cerevisiae MH - Flavone MH - Kinetic mechanism MH - Integrated rate-equations MH - Quinone oxidoreductase MH - Respiratory-chain MH - Escherichia-coli MH - Inner membrane MH - Dehydrogenase MH - Purification MH - Cells MH - Gene AB - Saccharomyces cerevisiae mitochondria contain an NADH:Q(6) oxidoreductase (internal NADH dehydrogenase) encoded by NDI1 gene in chromosome XIII. This enzyme catalyzes the transfer of electrons from NADH to ubiquinone without the translocation of protons across the membrane. From a structural point of view, the mature enzyme has a single subunit of 53 kDa with FAD as the only prosthetic group. Due to the fact that S. cerevisiae cells lack complex I, the expression of this protein is essential for cell growth under respiratory conditions. The results reported in this work show that the internal NADH dehydrogenase follows a ping-pong mechanism, with a K-m for NADH of 9.4 muM and a K-m for oxidized 2,6-dichorophenolindophenol (DCPIP) of 6.2 muM. NAD(+), one of the products of the reaction, did not inhibit the enzyme while the other product, reduced DCPIP, inhibited the enzyme with a Ki of 11.5 muM. Two dead-end inhibitors, AMP and flavone, were used to further characterize the kinetic mechanism of the enzyme. AMP was a linear competitive inhibitor of NADH (K-i = 5.5 mM) and a linear uncompetitive inhibitor of oxidized DCPIP (K-i = 11.5 mM), in agreement with the ping-pong mechanism. On the other hand, flavone was a partial inhibitor displaying a hyperbolic uncompetitive inhibition regarding NADH, and a hyperbolic noncompetitive inhibition with respect to oxidized DCPIP. The apparent intercept inhibition constant (K-ii = 5.4 muM) and the slope inhibition constant (K-is = 7.1 muM) were obtained by non linear regression analysis. The results indicate that the ternary complex F-DCPIPox-flavone catalyzes the reduction of DCPIP, although with lower efficiency. The effect of pH on V-max was studied. The V-max profile shows two groups with pK(a) values of 5.3 and 7.2 involved in the catalytic process. (C) 2001 Academic Press. [References: 23] LG - English PT - Article SB - Current Contents(R)/Life Sciences IN - Pardo JP Natl Autonomous Univ Mexico, Fac Med, Dept Bioquim Apartado Postal 70-159 Mexico City 04510 DF Mexico Natl Autonomous Univ Mexico, Fac Med, Dept Bioquim Mexico City 04510 DF Mexico