| functional consequences of the organization of the photosynthetic apparatus in rhodobacter sphaeroides. i. quinone domains and excitation transfer in chromatophores and reaction center.antenna complexes. | the purpose of this study was to gain information on the functional consequences of the supramolecular organization of the photosynthetic apparatus in the bacterium rhodobacter sphaeroides. isolated complexes of the reaction center (rc) with its core antenna ring (light-harvesting complex 1 (lh1)) were studied in their dimeric (native) form or as monomers with respect to excitation transfer and distribution of the quinone pool. similar issues were examined in chromatophore membranes. the relatio ... | 2005 | 15632164 |
| energetics of proton transfer pathways in reaction centers from rhodobacter sphaeroides. the glu-h173 activated mutants. | electron transfer between the primary and secondary quinones (q(a), q(b)) in the bacterial photosynthetic reaction center (brc) is coupled with proton uptake at q(b). the protons are conducted from the cytoplasmic side, probably with the participation of two water channels. mutations of titratable residues like asp-l213 to asn (inhibited mutant) or the double mutant glu-l212 to ala/asp-l213 to ala inhibit these electron transfer-coupled proton uptake events. the inhibition of the proton transfer ... | 2005 | 15637063 |
| metabolically engineered rhodobacter sphaeroides rv strains for improved biohydrogen photoproduction combined with disposal of food wastes. | three differently metabolically engineered strains, 2 single pha- and hup- mutants and one double pha-/hup- mutant, of the purple nonsulfur photosynthetic bacterium rhodobacter sphaeroides rv, were constructed to improve a light-driven biohydrogen production process combined with the disposal of solid food wastes. these phenotypes were designed to abolish, singly or in combination, the competition of h2 photoproduction with polyhydroxyalkanoate (pha) accumulation by inactivating pha synthase act ... | 2004 | 15645340 |
| sspa, an outer membrane protein, is highly induced under salt-stressed conditions and is essential for growth under salt-stressed aerobic conditions in rhodobacter sphaeroides f. sp. denitrificans. | we have previously shown that an outer membrane protein, sspa, is prominently induced by salt stress in a photosynthetic bacterium, rhodobacter sphaeroides f. sp. denitrificans il106 (r. sphaeroides). in this study, we investigated the physiological role of sspa under various stress conditions. using recombinant sspa expressed in escherichia coli as an antigen, the polyclonal antiserum of sspa was prepared. western blot analysis demonstrated that sspa was highly induced by salt stress under both ... | 2005 | 15647934 |
| mechanistic studies of rhodobacter sphaeroides me2so reductase. | studies of the molybdenum-containing dimethyl sulfoxide reductase from rhodobacter sphaeroides have yielded new insight into its catalytic mechanism. a series of reductive titrations, performed over the ph range 6-10, reveal that the absorption spectrum of reduced enzyme is highly sensitive to ph. the reaction of reduced enzyme with dimethyl sulfoxide is found to be clearly biphasic throughout the ph range 6-8 with a fast, initial substrate-binding phase and substrate-concentration independent c ... | 2005 | 15649898 |
| combined afm and confocal fluorescence microscope for applications in bio-nanotechnology. | we present a custom-designed atomic force fluorescence microscope (affm), which can perform simultaneous optical and topographic measurements with single molecule sensitivity throughout the whole visible to near-infrared spectral region. integration of atomic force microscopy (afm) and confocal fluorescence microscopy combines the high-resolution topographical imaging of afm with the reliable (bio)-chemical identification capability of optical methods. the affm is equipped with a spectrograph en ... | 2005 | 15655068 |
| hydrogen production by rhodobacter sphaeroides strain o.u.001 using spent media of enterobacter cloacae strain dm11. | combined dark and photo-fermentation was carried out to study the feasibility of biological hydrogen production. in dark fermentation, hydrogen was produced by enterobacter cloacae strain dm11 using glucose as substrate. this was followed by a photo-fermentation process. here, the spent medium from the dark process (containing unconverted metabolites, mainly acetic acid etc.) underwent photo-fermentation by rhodobacter sphaeroides strain o.u.001 in a column photo-bioreactor. this combination cou ... | 2005 | 15666144 |
| light-induced structural changes of apoprotein and chromophore in the sensor of blue light using fad (bluf) domain of appa for a signaling state. | appa is a new class blue-light receptor controlling photosynthesis gene expression in the purple bacterium rhodobacter sphaeroides and retains a characteristic flavin adenine dinucleotide (fad)-binding domain named the "sensor of blue light using fad" (bluf). appa functions as an antirepressor controlling transcription of photosynthesis genes through the direct association with a transcriptional repressor ppsr in a blue-light-dependent manner [masuda and bauer (2002) cell 110, 613-623]. illumina ... | 2005 | 15667215 |
| specific triazine resistance in bacterial reaction centers induced by a single mutation in the qa protein pocket. | we report here the first example of a reaction center mutant from rhodobacter sphaeroides, where a single mutation (m266his --> leu) taking place in the primary quinone protein pocket confers selective resistance to triazine-type inhibitors (terbutryn, ametryn, and atrazine), which bind in the secondary quinone protein pocket, at about 13 a from the mutation site. the m266his --> leu mutation involves one of the iron atom ligands. interestingly, neither the secondary quinone nor the highly speci ... | 2005 | 15667227 |
| transcriptional regulation of the uptake [nife]hydrogenase genes in rhodobacter capsulatus. | transcription of the hupsl genes, which encode the uptake [nife]hydrogenase of rhodobacter capsulatus, is specifically activated by h(2). three proteins are involved, namely the h(2)-sensor hupuv, the histidine kinase hupt and the transcriptional activator hupr. hupt and hupuv mutants have the same phenotype, i.e. an increased level of hupsl expression (assayed by phups::lacz fusion) in the absence of h(2); they negatively control hupsl gene expression. hupt can autophosphorylate its conserved h ... | 2005 | 15667256 |
| anaerobic regulation of hydrogenase transcription in different bacteria. | hydrogen metabolism is closely related to other important metabolic and energetic processes of bacterial cells, such as photosynthesis, anaerobic respiration and sulphur metabolism. even small environmental changes influence these networks through different regulatory systems. the presence or absence of oxygen is one of the most important signals; how the cascades evolved to transmit this signal in different bacteria is summarized. in many instances, hydrogen is released only under anoxic condit ... | 2005 | 15667258 |
| interacting regulatory networks in the facultative photosynthetic bacterium, rhodobacter sphaeroides 2.4.1. | regulation of photosynthetic membrane synthesis in rhodobacter sphaeroides 2.4.1 is dependent on the interactions of numerous regulatory elements, with two of the most important being the cbb(3) terminal oxidase and the prrbac two-component regulatory system. here, we reveal that the cbb(3) terminal oxidase possesses extensive, additional regulatory activities under anaerobic conditions, and that the prrbac system is further involved in the regulation of the expression of more than 20% of the r. ... | 2005 | 15667262 |
| high-level transcription of large gene regions: a novel t(7) rna-polymerase-based system for expression of functional hydrogenases in the phototrophic bacterium rhodobacter capsulatus. | high-level synthesis of complex enzymes like bacterial [nife] hydrogenases, in general, requires an expression system that allows concerted expression of a large number of genes. so far, it has not been possible to overproduce a hydrogenase in a stable and active form by using a customary expression system. therefore we started to establish a new, t(7)-based expression system in the phototrophic bacterium rhodobacter capsulatus. the beneficial properties of this bacterial host in combination wit ... | 2005 | 15667263 |
| tuning electron transfer by ester-group of chlorophylls in bacterial photosynthetic reaction center. | accessory chlorophylls (b(a/b)) in bacterial photosynthetic reaction center play a key role in charge-separation. although light-exposed and dark-adapted brc crystal structures are virtually identical, the calculated b(a) redox potentials for one-electron reduction differ. this can be traced back to different orientations of the b(a) ester-group. this tuning ability of chlorophyll redox potentials modulates the electron transfer from sp* to b(a). | 2005 | 15670833 |
| rhythmic gene expression in a purple photosynthetic bacterium, rhodobacter sphaeroides. | circadian rhythms are known to exist in all groups of eukaryotic organisms as well as oxygenic photosynthetic bacteria, cyanobacteria. however, little information is available regarding the existence of rhythmic behaviors in prokaryotes other than cyanobacteria. here we report biological rhythms of gene expression in a purple bacterium rhodobacter sphaeroides by using a luciferase reporter gene system. self-bioluminescent strains of rb. sphaeroides were constructed, which produced a bacterial lu ... | 2005 | 15670851 |
| the puhb protein of rhodobacter capsulatus functions in photosynthetic reaction center assembly with a secondary effect on light-harvesting complex 1. | the core of the photosynthetic apparatus of purple photosynthetic bacteria such as rhodobacter capsulatus consists of a reaction center (rc) intimately associated with light-harvesting complex 1 (lh1) and the pufx polypeptide. the abundance of the rc and lh1 components was previously shown to depend on the product of the puhb gene (formerly known as orf214). we report here that disruption of puhb diminishes rc assembly, with an indirect effect on lh1 assembly, and reduces the amount of pufx. und ... | 2005 | 15687197 |
| l-malyl-coenzyme a/beta-methylmalyl-coenzyme a lyase is involved in acetate assimilation of the isocitrate lyase-negative bacterium rhodobacter capsulatus. | cell extracts of rhodobacter capsulatus grown on acetate contained an apparent malate synthase activity but lacked isocitrate lyase activity. therefore, r. capsulatus cannot use the glyoxylate cycle for acetate assimilation, and a different pathway must exist. it is shown that the apparent malate synthase activity is due to the combination of a malyl-coenzyme a (coa) lyase and a malyl-coa-hydrolyzing enzyme. malyl-coa lyase activity was 20-fold up-regulated in acetate-grown cells versus glucose- ... | 2005 | 15687206 |
| fast oxidation of the primary electron acceptor under anaerobic conditions requires the organization of the photosynthetic chain of rhodobacter sphaeroides in supercomplexes. | the kinetics of reoxidation of the primary acceptor q(a) has been followed by measuring the changes in the fluorescence yield induced by a series of saturating flashes in intact cells of rhodobacter sphaeroides in anaerobic conditions. at 0 degrees c, about half of q(a)(-) is reoxidized in about 200 ms while reoxidation of the remaining fraction is completed in several seconds to minutes. the fast phase is associated with the transfer of ubiquinone formed at site q(o) of the cytochrome bc(1) com ... | 2005 | 15694348 |
| sequential assembly of photosynthetic units in rhodobacter sphaeroides as revealed by fast repetition rate analysis of variable bacteriochlorophyll a fluorescence. | the development of functional photosynthetic units in rhodobacter sphaeroides was followed by near infra-red fast repetition rate (irfrr) fluorescence measurements that were correlated to absorption spectroscopy, electron microscopy and pigment analyses. to induce the formation of intracytoplasmic membranes (icm) (greening), cells grown aerobically both in batch culture and in a carbon-limited chemostat were transferred to semiaerobic conditions. in both aerobic cultures, a low level of photosyn ... | 2005 | 15694350 |
| a1 reduction in intact cyanobacterial photosystem i particles studied by time-resolved step-scan fourier transform infrared difference spectroscopy and isotope labeling. | time-resolved step-scan fourier transform infrared (ftir) difference spectroscopy, with 5 mus time resolution, has been used to produce p700(+)a(1)(-)/p700a(1) ftir difference spectra in intact photosystem i particles from synechococcus sp. 7002 and synechocystis sp. 6803 at 77 k. corresponding spectra were also obtained for fully deuterated photosystem i particles from synechococcus sp. 7002 as well as fully (15)n- and (13)c-labeled photosystem i particles from synechocystis sp. 6803. static p7 ... | 2005 | 15697214 |
| annotation of genes involved in glycerolipid biosynthesis in chlamydomonas reinhardtii: discovery of the betaine lipid synthase bta1cr. | lipid metabolism in flowering plants has been intensely studied, and knowledge regarding the identities of genes encoding components of the major fatty acid and membrane lipid biosynthetic pathways is very extensive. we now present an in silico analysis of fatty acid and glycerolipid metabolism in an algal model, enabled by the recent availability of expressed sequence tag and genomic sequences of chlamydomonas reinhardtii. genes encoding proteins involved in membrane biogenesis were predicted o ... | 2005 | 15701786 |
| exoribonuclease r interacts with endoribonuclease e and an rna helicase in the psychrotrophic bacterium pseudomonas syringae lz4w. | endoribonuclease e, a key enzyme involved in rna decay and processing in bacteria, organizes a protein complex called degradosome. in escherichia coli, rhodobacter capsulatus, and streptomyces coelicolor, rnase e interacts with the phosphate-dependent exoribonuclease polynucleotide phosphorylase, dead-box helicase(s), and additional factors in an rna-degrading complex. to characterize the degradosome of the psychrotrophic bacterium pseudomonas syringae lz4w, rnase e was enriched by cation exchan ... | 2005 | 15705581 |
| characterization of a diesel sludge microbial consortia for bioremediation. | the organisms found growing in a mixed diesel sludge-chromium metal waste were characterized directly using environmental scanning electron microscopy (esem) and traditional fixation techniques with scanning electron microscopy (sem). an attempt to identify organisms genetically directly from the sludge failed because of interference from chemicals in the waste with polymerase chain reaction (pcr). the organisms were isolated using plate culture techniques and isolates were characterized by sem ... | 2005 | 15712752 |
| femtosecond dynamics of transition processes in reaction centers of rhodobacter sphaeroides. | | 2004 | 15714939 |
| experimental identification and quantification of glucose metabolism in seven bacterial species. | the structurally conserved and ubiquitous pathways of central carbon metabolism provide building blocks and cofactors for the biosynthesis of cellular macromolecules. the relative uses of pathways and reactions, however, vary widely among species and depend upon conditions, and some are not used at all. here we identify the network topology of glucose metabolism and its in vivo operation by quantification of intracellular carbon fluxes from 13c tracer experiments. specifically, we investigated a ... | 2005 | 15716428 |
| a chimeric n-terminal escherichia coli--c-terminal rhodobacter sphaeroides flig rotor protein supports bidirectional e. coli flagellar rotation and chemotaxis. | flagellate bacteria such as escherichia coli and salmonella enterica serovar typhimurium typically express 5 to 12 flagellar filaments over their cell surface that rotate in clockwise (cw) and counterclockwise directions. these bacteria modulate their swimming direction towards favorable environments by biasing the direction of flagellar rotation in response to various stimuli. in contrast, rhodobacter sphaeroides expresses a single subpolar flagellum that rotates only cw and responds tactically ... | 2005 | 15716440 |
| magnetic field effect on singlet oxygen production in a biochemical system. | the yield of singlet oxygen sensitized by chemically modified, carotenoidless bacterial photosynthetic reaction centres and the ensuing oxidative damage are both shown to be magnetic field-dependent. | 2004 | 15724176 |
| production of a novel indole ester from 2-aminobenzoate by rhodobacter sphaeroides ou5. | culture supernatants of rhodobacter sphaeroides ou5 grown in the presence of 2-aminobenzoate gave an orange-red color-reaction with salper's reagent, suggesting the presence of an indole derivative. this production was light-dependent and inducible only with 2-aminobenzoate. replacement of 2-aminobenzoate with other 2-substituted benzoates did not result in the formation of indole. fumarate appeared to be the conjugating molecule with 2-aminobenzoate, resulting in the formation of an indole deri ... | 2005 | 15726442 |
| solution structures of the core light-harvesting alpha and beta polypeptides from rhodospirillum rubrum: implications for the pigment-protein and protein-protein interactions. | we have determined the solution structures of the core light-harvesting (lh1) alpha and beta-polypeptides from wild-type purple photosynthetic bacterium rhodospirillum rubrum using multidimensional nmr spectroscopy. the two polypeptides form stable alpha helices in organic solution. the structure of alpha-polypeptide consists of a long helix of 32 amino acid residues over the central transmembrane domain and a short helical segment at the n terminus that is followed by a three-residue loop. pigm ... | 2005 | 15740753 |
| transcriptome analysis of the rhodobacter sphaeroides ppsr regulon: ppsr as a master regulator of photosystem development. | ppsr from the anoxygenic phototrophic bacterium rhodobacter sphaeroides has been known as an oxygen- and light-dependent repressor of bacteriochlorophyll and carotenoid biosynthesis genes and puc operons involved in photosystem development. however, the putative ppsr-binding sites, tgtn12aca, are also located upstream of numerous nonphotosystem genes, thus raising the possibility that the role of ppsr is broader. to characterize the ppsr regulon, transcriptome profiling was performed on the wild ... | 2005 | 15743963 |
| photocycle of the flavin-binding photoreceptor appa, a bacterial transcriptional antirepressor of photosynthesis genes. | the flavoprotein appa from rhodobacter sphaeroides contains an n-terminal domain belonging to a new class of photoreceptors designated bluf domains. appa was shown to control photosynthesis gene expression in response to blue light and oxygen tension. we have investigated the photocycle of the appa bluf domain by ultrafast fluorescence, femtosecond transient absorption, and nanosecond flash-photolysis spectroscopy. time-resolved fluorescence experiments revealed four components of flavin adenine ... | 2005 | 15751942 |
| assembly of cytochrome-c oxidase in the absence of assembly protein surf1p leads to loss of the active site heme. | surf1p is a protein of the inner membrane of mitochondria that functions in the assembly of cytochrome-c oxidase. the specifics of the role of surf1p have remained unresolved. numerous mutations in human surf1p lead to severe mitochondrial disease. a homolog of human surf1p is encoded by the genome of the alpha-proteobacterium rhodobacter sphaeroides, which synthesizes a mitochondrial-like aa(3)-type cytochrome-c oxidase. the gene for surf1p was deleted from the genome of r. sphaeroides. the res ... | 2005 | 15764605 |
| direct observation of redox-linked histidine protonation changes in the iron-sulfur protein of the cytochrome bc1 complex by atr-ftir spectroscopy. | the redox-linked protonation chemistry of the iron-sulfur protein (isp) of the cytochrome bc(1) complex was studied by analysis of the ph dependencies of redox difference spectra using perfusion/electrochemically induced attenuated total reflection-fourier transform infrared (atr-ftir) spectroscopy. the isp of rhodobacter capsulatus within the intact cytochrome bc(1) complex was analyzed in a mutant form in which the midpoint potential of cytochrome c(1) was lower than that of the isp. this was ... | 2005 | 15766251 |
| electron transfer pathways and protein response to charge separation in photosynthetic reaction centers: time-resolved high-field endor of the spin-correlated radical pair p865(+)qa(-). | recently we reported the first observation of time-resolved (tr) high-frequency (hf) electron nuclear double resonance (endor) of the transient charge separated state p865(+)q(-)a in purple photosynthetic bacterial reaction centers (rc) (poluektov, o. g., et al. j. am. chem. soc. 2004, 126, 1644-1645). the high resolution and orientational selectivity of hf endor allows us to directly probe protein environments by spectrally selecting specific nuclei in isotopically labeled samples. a new phenom ... | 2005 | 15771542 |
| slow proton transfer through the pathways for pumped protons in cytochrome c oxidase induces suicide inactivation of the enzyme. | in the absence of subunit iii the aa(3)-type cytochrome c oxidase exhibits a shortened catalytic life span (total number of turnovers) due to an increased probability of undergoing irreversible inactivation during steady-state turnover. inactivation results from structural alteration of the heme a(3)-cu(b) active site in subunit i [hosler (2004) biochim. biophys. acta 1655, 332-339]. the absence of subunit iii also dramatically slows proton uptake to the active site via the d proton pathway, as ... | 2005 | 15779892 |
| design and expression of cysteine-bearing hydrophobic polypeptides and their self-assembling properties with bacteriochlorophyll a derivatives as a mimic of bacterial photosynthetic antenna complexes. effect of steric confinement and orientation of the polypeptides on the pigment/polypeptide assembly process. | a series of cysteine-bearing hydrophobic polypeptides analogous to a light-harvesting one betapolypeptide (lh1beta) from the lh1 complex from the purple photosynthetic bacterium, rhodobacter sphaeroides, was synthesized using an escherichia coli expression system. the cysteine was placed in the c- or n-terminal regions of the polypeptide to investigate the influence of steric confinement and orientation of the polypeptides via disulfide linkages as they were self-assembled with zinc-substituted ... | 2005 | 15794650 |
| structure of zinc-independent sorbitol dehydrogenase from rhodobacter sphaeroides at 2.4 a resolution. | recombinant sorbitol dehydrogenase (sdh) from rhodobacter sphaeroides has been crystallized in the absence of the cofactor nad(h) and its structure determined to 2.4 a resolution using molecular replacement (refined r and r free factors of 18.8 and 23.8%, respectively). as expected from the sequence and shown by the conserved fold, sdh can be assigned to the short-chain dehydrogenase/reductase protein family. the cofactor nad and the substrate sorbitol have been modelled into the structure and t ... | 2005 | 15805591 |
| automatic structure determination based on the single-wavelength anomalous diffraction technique away from an absorption edge. | the phasing of macromolecular structures based on the use of the single-wavelength anomalous diffraction method has recently enjoyed a revival. here, additional evidence is provided that the method may be successfully applied at wavelengths remote from the absorption edge of interest and that it is in principle applicable to a large number of systems. this opens up the possibility of rapid and reliable automatic de novo structure determination using simple experimental configurations with no nee ... | 2005 | 15805593 |
| protein structural deformation induced lifetime shortening of photosynthetic bacteria light-harvesting complex lh2 excited state. | photosynthetic bacterial light-harvesting antenna complex lh2 was immobilized on the surface of tio(2) nanoparticles in the colloidal solution. the lh2/tio(2) assembly was investigated by the time-resolved spectroscopic methods. the excited-state lifetimes for carotenoid-containing and carotenoidless lh2 have been measured, showing a decrease in the excited-state lifetime of b850 when lh2 was immobilized on tio(2). the possibility that the decrease of the lh2 excited-state lifetime being caused ... | 2005 | 15821161 |
| how does nitrous oxide reductase interact with its electron donors?--a docking study. | electron transfer reactions are crucial for respiration and denitrification. in this article, we analyze the interaction of nitrous oxide reductase with its electron donors cytochrome c550 and pseudoazurin. our docking protocol comprises generation of candidate complexes followed by a selection step based on the distance of the donor and acceptor groups in each partner protein. finally, the structures of the candidate complexes were optimized using a force field calculation, together with a seco ... | 2005 | 15822112 |
| chrr, a soluble quinone reductase of pseudomonas putida that defends against h2o2. | most bacteria contain soluble quinone-reducing flavoenzymes. however, no biological benefit for this activity has previously been demonstrated. chrr of pseudomonas putida is one such enzyme that has also been characterized as a chromate reductase; yet we propose that it is the quinone-reducing activity of chrr that has the greatest biological significance. chrr reduces quinones by simultaneous two-electron transfer, avoiding formation of highly reactive semiquinone intermediates and producing qu ... | 2005 | 15840577 |
| a recombinant diheme soxax cytochrome - implications for the relationship between epr signals and modified heme-ligands. | the multiheme soxax proteins are notable for their unusual heme ligation (his/cys-persulfide in the soxa subunit) and the complexity of their epr spectra. the diheme soxax protein from starkeya novella has been expressed using rhodobacter capsulatus as a host expression system. rsoxax was correctly formed in the periplasm of the host and contained heme c in similar amounts as the native soxax. esi-ms showed that the full length rsoxa, in spite of never having undergone catalytic turnover, existe ... | 2005 | 15848194 |
| cloning and characterization of a region responsible for the maintenance of megaplasmid ptav3 of paracoccus versutus uw1. | using cointegrate formation, we constructed a basic replicon of the megaplasmid/mini-chromosome ptav3 of paracoccus versutus uw1. it is composed of two adjacent modules, responsible for plasmid replication (rep) and partitioning (par). functional analysis of the par region identified a determinant of incompatibility (inc2), whose presence is crucial for proper partitioning (the partitioning site). database searches revealed that the only known replicon with significant homology to that of ptav3 ... | 2005 | 15848227 |
| the puhe gene of rhodobacter capsulatus is needed for optimal transition from aerobic to photosynthetic growth and encodes a putative negative modulator of bacteriochlorophyll production. | a conserved orf of previously unknown function (herein designated as puhe) is located 3' of the reaction centre h (puha) gene in purple photosynthetic bacteria, in the order puhabce in rhodobacter capsulatus. disruptions of r. capsulatus puhe resulted in a long lag in the growth of photosynthetic cultures inoculated with cells grown under high aeration, and increased the level of the peripheral antenna, light-harvesting complex 2 (lh2). the amount of the photosynthetic reaction centre (rc) and i ... | 2005 | 15850558 |
| a transcriptional response to singlet oxygen, a toxic byproduct of photosynthesis. | the ability of phototrophs to convert light into biological energy is critical for life on earth. however, there can be deleterious consequences associated with this bioenergetic conversion, including the production of toxic byproducts. for example, singlet oxygen (1o2) can be formed during photosynthesis by energy transfer from excited triplet-state chlorophyll pigments to o2. by monitoring gene expression and growth in the presence of 1o2, we show that the phototrophic bacterium rhodobacter sp ... | 2005 | 15855269 |
| investigation of b-branch electron transfer by femtosecond time resolved spectroscopy in a rhodobacter sphaeroides reaction centre that lacks the q(a) ubiquinone. | the dynamics of electron transfer in a membrane-bound rhodobacter sphaeroides reaction centre containing a combination of four mutations were investigated by transient absorption spectroscopy. the reaction centre, named waah, has a mutation that causes the reaction centre to assemble without a q(a) ubiquinone (ala m260 to trp), a mutation that causes the replacement of the h(a) bacteriopheophytin with a bacteriochlorophyll (leu m214 to his) and two mutations that remove acidic groups close to th ... | 2005 | 15863097 |
| quinone (qb) reduction by b-branch electron transfer in mutant bacterial reaction centers from rhodobacter sphaeroides: quantum efficiency and x-ray structure. | the photosynthetic reaction center (rc) from purple bacteria converts light into chemical energy. although the rc shows two nearly structurally symmetric branches, a and b, light-induced electron transfer in the native rc occurs almost exclusively along the a-branch to a primary quinone electron acceptor q(a). subsequent electron and proton transfer to a mobile quinone molecule q(b) converts it to a quinol, q(b)h(2). we report the construction and characterization of a series of mutants in rhodo ... | 2005 | 15865437 |
| the iron-sulfur cluster of the rieske iron-sulfur protein functions as a proton-exiting gate in the cytochrome bc(1) complex. | the destruction of the rieske iron-sulfur cluster ([2fe-2s]) in the bc(1) complex by hematoporphyrin-promoted photoinactivation resulted in the complex becoming proton-permeable. to study further the role of this [2fe-2s] cluster in proton translocation of the bc(1) complex, rhodobacter sphaeroides mutants expressing his-tagged cytochrome bc(1) complexes with mutations at the histidine ligands of the [2fe-2s] cluster were generated and characterized. these mutants lacked the [2fe-2s] cluster and ... | 2005 | 15878858 |
| thioclava pacifica gen. nov., sp. nov., a novel facultatively autotrophic, marine, sulfur-oxidizing bacterium from a near-shore sulfidic hydrothermal area. | strain tl 2(t) was isolated on mineral medium with thiosulfate from a near-shore sulfidic hydrothermal area in matupi harbour on the island of new britain, papua new guinea. the cells varied from long filaments with swollen ends, often aggregated, to short rods, depending on the growth conditions. the bacterium was obligately aerobic and grew autotrophically with thiosulfate as energy source or heterotrophically with organic acids and sugars. in thiosulfate-limited continuous culture, mu(max) an ... | 2005 | 15879235 |
| dinoroseobacter shibae gen. nov., sp. nov., a new aerobic phototrophic bacterium isolated from dinoflagellates. | a novel group of aerobic anoxygenic phototrophic bacteria was isolated from marine dinoflagellates, and two strains were characterized in detail. cells were gram-negative cocci or ovoid rods and were motile by means of a single, polarly inserted flagellum. they were obligate aerobes requiring 1-7 % salinity. the optimal ph range for growth was 6.5-9.0 and the temperature optimum was 33 degrees c. the bacteria contained bacteriochlorophyll a and spheroidenone as the only carotenoid. the in vivo a ... | 2005 | 15879238 |
| internal dynamics and protein-matrix coupling in trehalose-coated proteins. | we review recent studies on the role played by non-liquid, water-containing matrices on the dynamics and structure of embedded proteins. two proteins were studied, in water-trehalose matrices: a water-soluble protein (carboxy derivative of horse heart myoglobin) and a membrane protein (reaction centre from rhodobacter sphaeroides). several experimental techniques were used: mossbauer spectroscopy, elastic neutron scattering, ftir spectroscopy, co recombination after flash photolysis in carboxy-m ... | 2005 | 15886079 |
| optimization of glutamate concentration and ph for h production from volatile fatty acids by rhodopseudomonas capsulata. | this study attempted to employ response surface methodology (rsm) to evaluate the effects of glutamate concentration and ph on h(2) production from volatile fatty acids by rhodopseudomonas capsulata. | 2005 | 15892733 |
| design of a redox-linked active metal site: manganese bound to bacterial reaction centers at a site resembling that of photosystem ii. | metals bound to proteins perform a number of crucial biological reactions, including the oxidation of water by a manganese cluster in photosystem ii. although evolutionarily related to photosystem ii, bacterial reaction centers lack both a strong oxidant and a manganese cluster for mediating the multielectron and proton transfer needed for water oxidation. in this study, carboxylate residues were introduced by mutagenesis into highly oxidizing reaction centers at a site homologous to the mangane ... | 2005 | 15895982 |
| isolation and characterization of heterotrophic bacteria able to grow aerobically with quaternary ammonium alcohols as sole source of carbon and nitrogen. | the quaternary ammonium alcohols (qaas) 2,3-dihydroxypropyl-trimethyl-ammonium (tm), dimethyl-diethanol-ammonium (dm) and methyl-triethanol-ammonium (mm) are hydrolysis products of their parent esterquat surfactants, which are widely used as softeners in fabric care. we isolated several bacteria growing with qaas as the sole source of carbon and nitrogen. the strains were compared with a previously isolated tm-degrading bacterium, which was identified as a representative of the species pseudomon ... | 2005 | 15900970 |
| the 8.5a projection structure of the core rc-lh1-pufx dimer of rhodobacter sphaeroides. | two-dimensional crystals of dimeric photosynthetic reaction centre-lh1-pufx complexes have been analysed by cryoelectron microscopy. the 8.5a resolution projection map extends previous analyses of complexes within native membranes to reveal the alpha-helical structure of two reaction centres and 28 lh1 alphabeta subunits within the dimer. for the first time, we have achieved sufficient resolution to suggest a possible location for the pufx transmembrane helix, the orientation of the rc and the a ... | 2005 | 15907932 |
| strong effects of an individual water molecule on the rate of light-driven charge separation in the rhodobacter sphaeroides reaction center. | the role of a water molecule (water a) located between the primary electron donor (p) and first electron acceptor bacteriochlorophyll (b(a)) in the purple bacterial reaction center was investigated by mutation of glycine m203 to leucine (gm203l). the x-ray crystal structure of the gm203l reaction center shows that the new leucine residue packs in such a way that water a is sterically excluded from the complex, but the structure of the protein-cofactor system around the mutation site is largely u ... | 2005 | 15908429 |
| investigation of ubiquinol formation in isolated photosynthetic reaction centers by rapid-scan fourier transform ir spectroscopy. | light-induced formation of ubiquinol-10 in rhodobacter sphaeroides reaction centers was followed by rapid-scan fourier transform ir difference spectroscopy, a technique that allows the course of the reaction to be monitored, providing simultaneously information on the redox states of cofactors and on protein response. the spectrum recorded between 4 and 29 ms after the second flash showed bands at 1,470 and 1,707 cm(-1), possibly due to a qh(-) intermediate state. spectra recorded at longer dela ... | 2005 | 15909199 |
| tlr4 antagonists for endotoxemia and beyond. | toll-like receptor 4 (tlr4) controls the major responding signaling system that detects the presence of gram-negative infectious pathogens, by responding to endotoxin from their outer membrane. normally, tlr-bearing cells signal the immune system to mount a pro-inflammatory, antibacterial response and resolve infection. however, tlr4 can also respond to a variety of 'endogenous' ligands, such as fibronectin and heat shock proteins. overstimulation or continued stimulation of tlr4 by any ligand c ... | 2005 | 15912963 |
| watching the components of photosynthetic bacterial membranes and their in situ organisation by atomic force microscopy. | the atomic force microscope has developed into a powerful tool in structural biology allowing information to be acquired at submolecular resolution on the protruding structures of membrane proteins. it is now a complementary technique to x-ray crystallography and electron microscopy for structure determination of individual membrane proteins after extraction, purification and reconstitution into lipid bilayers. moving on from the structures of individual components of biological membranes, atomi ... | 2005 | 15919049 |
| structure of a novel photoreceptor, the bluf domain of appa from rhodobacter sphaeroides. | the flavin-binding bluf domain of appa represents a new class of blue light photoreceptors that are present in a number of bacterial and algal species. the dark state x-ray structure of this domain was determined at 2.3 a resolution. the domain demonstrates a new function for the common ferredoxin-like fold; two long alpha-helices flank the flavin, which is bound with its isoalloxazine ring perpendicular to a five-stranded beta-sheet. the hydrogen bond network and the overall protein topology of ... | 2005 | 15924418 |
| sacb-5-fluoroorotic acid-pyre-based bidirectional selection for integration of unmarked alleles into the chromosome of rhodobacter capsulatus. | the gram-negative, purple nonsulfur, facultative photosynthetic bacterium rhodobacter capsulatus is a widely used model organism and has well-developed molecular genetics. in particular, interposon mutagenesis using selectable gene cartridges is frequently employed for construction of a variety of chromosomal knockout mutants. however, as the gene cartridges are often derived from antibiotic resistance-conferring genes, their numbers are limited, which restricts the construction of multiple knoc ... | 2005 | 15932997 |
| regulation and function of cytochrome c' in rhodobacter sphaeroides 2.4.3. | cytochrome c' (cyt c') is a c-type cytochrome with a pentacoordinate heme iron. the gene encoding this protein in rhodobacter sphaeroides 2.4.3, designated cycp, was isolated and sequenced. northern blot analysis and beta-galactosidase assays demonstrated that cycp transcription increased as oxygen levels decreased and was not repressed under denitrifying conditions as observed in another rhodobacter species. co difference spectra performed with extracts of cells grown under different conditions ... | 2005 | 15937170 |
| overproduction of ccmg and ccmfh(rc) fully suppresses the c-type cytochrome biogenesis defect of rhodobacter capsulatus ccmi-null mutants. | gram-negative bacteria like rhodobacter capsulatus use intertwined pathways to carry out the posttranslational maturation of c-type cytochromes (cyts). this periplasmic process requires at least 10 essential components for apo-cyt c chaperoning, thio-oxidoreduction, and the delivery of heme and its covalent ligation. one of these components, ccmi (also called cych), is thought to act as an apo-cyt c chaperone. in r. capsulatus, ccmi-null mutants are unable to produce c-type cyts and thus sustain ... | 2005 | 15937187 |
| conformational regulation of charge recombination reactions in a photosynthetic bacterial reaction center. | in bright light the photosynthetic reaction center (rc) of rhodobacter sphaeroides stabilizes the p(+)(870).q(-)(a) charge-separated state and thereby minimizes the potentially harmful effects of light saturation. using x-ray diffraction we report a conformational change that occurs within the cytoplasmic domain of this rc in response to prolonged illumination with bright light. our observations suggest a novel structural mechanism for the regulation of electron transfer reactions in photosynthe ... | 2005 | 15937492 |
| atp-dependent enolization of acetone by acetone carboxylase from rhodobacter capsulatus. | acetone carboxylase catalyzes the carboxylation of acetone to acetoacetate with concomitant hydrolysis of atp to amp and two inorganic phosphates. the biochemical, molecular, and genetic properties of acetone carboxylase suggest it represents a fundamentally new class of carboxylase. as the initial step in catalysis, an alpha-proton from an inherently basic (pk(a) = 20) methyl group is abstracted to generate the requisite carbanion for attack on co(2). in the present study alpha-proton abstracti ... | 2005 | 15938645 |
| pentaplot: a software tool for the illustration of genome mosaicism. | dekapentagonal maps depict the phylogenetic relationships of five genomes in a visually appealing diagram and can be viewed as an alternative to a single evolutionary consensus tree. in particular, the generated maps focus attention on those gene families that significantly deviate from the consensus or plurality phylogeny. pentaplot is a software tool that computes such dekapentagonal maps given an appropriate probability support matrix. | 2005 | 15938752 |
| photo-oxidative stress in rhodobacter sphaeroides: protective role of carotenoids and expression of selected genes. | in rhodobacter sphaeroides, carotenoids are essential constituents of the photosynthetic apparatus and are assumed to prevent the formation of singlet oxygen by quenching of triplet bacteriochlorophyll a (bchl a) in vivo. it was shown that small amounts of singlet oxygen are generated in vivo by incubation of r. sphaeroides under high light conditions. however, growth and survival rates were not affected. higher amounts of singlet oxygen were generated by bchl a in a carotenoid-deficient strain ... | 2005 | 15942000 |
| tellurite effects on rhodobacter capsulatus cell viability and superoxide dismutase activity under oxidative stress conditions. | cells of the facultative photosynthetic bacterium rhodobacter capsulatus (mt1131 strain) incubated with 10 microg ml-1 of the toxic oxyanion tellurite (teo2-(3)) exhibited an increase in superoxide dismutase activity. the latter effect was also seen upon incubation with sublethal amounts of paraquat, a cytosolic generator of superoxide anions (o2-), in parallel with a strong increase in tellurite resistance (ter). a mutant strain (cw10) deficient in senc, a protein with similarities to peroxired ... | 2005 | 15946826 |
| ppsr: a multifaceted regulator of photosynthesis gene expression in purple bacteria. | purple bacteria control the level of expression and the composition of their photosystem according to light and redox conditions. this control involves several regulatory systems that have been now well characterized. among them, the ppsr regulator plays a central role, because it directly or indirectly controls the synthesis of all of the different components of the photosystem. in this review, we report our knowledge of the ppsr protein, highlighting the diversity of its mode of action and foc ... | 2005 | 15948946 |
| the ppsr regulator family. | under aerobic conditions, phototrophic bacteria repress the formation of pigments to protect cells in the presence of light from the damaging effects of reactive oxygen species and consume oxygen through respiratory complexes. members of the ppsr family regulate the transcription of bch, crt, puc, and hem genes in respond to redox or light conditions. this mini-review focuses on the function and distribution of ppsr proteins. | 2005 | 15950121 |
| accessibility of the distal heme face, rather than fe-his bond strength, determines the heme-nitrosyl coordination number of cytochromes c': evidence from spectroscopic studies. | the heme coordination chemistry and spectroscopic properties of rhodobacter capsulatus cytochrome c' (rccp) have been compared to data from alcaligenes xylosoxidans (axcp), with the aim of understanding the basis for their different reactivities with nitric oxide (no). whereas ferrous axcp reacts with no to form a predominantly five-coordinate heme-nitrosyl complex via a six-coordinate intermediate, rccp forms an equilibrium mixture of six-coordinate and five-coordinate heme-nitrosyl species in ... | 2005 | 15952773 |
| overexpression and characterization of dark-operative protochlorophyllide reductase from rhodobacter capsulatus. | dark-operative protochlorophyllide oxidoreductase (dpor) plays a crucial role in light-independent (bacterio)chlorophyll biosynthesis in most photosynthetic organisms. however, the biochemical properties of dpor are still largely undefined. here, we constructed an overexpression system of two separable components of dpor, l-protein (bchl) and nb-protein (bchn-bchb), in the broad-host-range vector pjrd215 in rhodobacter capsulatus. we established a stable dpor assay system by mixing crude extract ... | 2005 | 15953479 |
| tributyl phosphate degradation by rhodopseudomonas palustris and other photosynthetic bacteria. | tributyl phosphate (tbp) is widely used in nuclear fuel processing and other waste generating chemical industries. although tbp is bacteriostatic, some microbes are resistant to it and may degrade it. under dark aerobiosis, purple non-sulfur photosynthetic bacteria degraded up to 0.6 mm tbp, initially present at 2 mm, within 3 weeks and under photosynthetic conditions, rhodopseudomonas palustris degraded 1.6 mm tbp within 3 weeks. the curing of the rhodopseudomonas palustris endogenous plasmid d ... | 2005 | 15973490 |
| the structure and function of the cytochrome c2: reaction center electron transfer complex from rhodobacter sphaeroides. | in the photosynthetic bacterium, rhodobacter sphaeroides, the mobile electron carrier, cytochrome c2 (cyt c2) transfers an electron from reduced heme to the photooxidized bacteriochlorophyll dimer in the membrane bound reaction center (rc) as part of the light induced cyclic electron transfer chain. a complex between these two proteins that is active in electron transfer has been crystallized and its structure determined by x-ray diffraction. the structure of the cyt:rc complex shows the cyt c2 ... | 2005 | 15977062 |
| endor investigation of the liganding environment of mixed-spin ferric cytochrome c'. | the electronic structure of the 5-coordinate quantum-mechanically mixed-spin (sextet-quartet) heme center in cytochrome c' was investigated by electron nuclear double resonance (endor), a technique not previously applied to this mixed-spin system. cytochrome c' was obtained from overexpressing variants of rhodobacter sphaeroides 2.4.3. endor for this study was done at the g(//) = 2.00 extremum where single-crystal-like, well-resolved spectra prevail. the heme meso protons of cytochrome c' showed ... | 2005 | 15984875 |
| [molecular analysis of the microbial communities of the dagang kongdian flooding bed oilfield]. | both pcr-tgge (temperature gradient gel electrophoresis, tgge) and 16s rrna gene clone library construction were used to comparatively analyze the microbial communities of a water injection well (ww) and an oil well (ow) in dagang oilfield. tgge analysis of the pcr amplified 16s rdna v3 region products showed great difference between these two microbial communities. six major bands were detected in the tgge profile of the ww sample, while only one predominant band in the ow sample was found. two ... | 2005 | 15989220 |
| [molecular diversity and phylogenetic analysis of nitrogen-fixing (nifh) genes in alp prairie soil of sanjiangyuan natural reserve]. | research on the diversity of microorganism community in natural environment has been concerned hot spot using the newly molecular biotechnology in the world now. this was the first description of the molecular diversity and phylogenetic analysis of nitrogen-fixing (nifh) genes in alp prairie soil of sanjiangyuan natural reserve. dna was directly extracted from the soil microorganism and amplified the nifh gene fragment using pcr by the primers of nifh-34f 5'-aaagg(c/t)gg(a/t) atcgg(c/t)aa(a/g) t ... | 2005 | 15989253 |
| photoresponsive flagellum-independent motility of the purple phototrophic bacterium rhodobacter capsulatus. | we report the discovery of photoresponsive, flagellum-independent motility of the alpha-proteobacterium rhodobacter capsulatus, a nonsulfur purple phototrophic bacterium. this motility takes place in the 1.5% agar-glass interface of petri plates but not in soft agar, and cells move toward a light source. the appearances of motility assay plates inoculated with wild-type or flagellum-deficient mutants indicate differential contributions from flagellar and flagellum-independent mechanisms. electro ... | 2005 | 15995225 |
| [effect of environmental factors on the composition of lipopolysaccharides released from the rhodobacter capsulatus cell wall]. | the goal of this study was to compare the environmental factors that determine viability of the gram-negative photosynthesizing bacteria rhodobacter capsulatus (specifically, light and growth medium composition) and to assess the effect of these factors on the synthesis and composition of lipopolysaccharides released from the cell wall. depletion of medium resulted in the release of lipopolysaccharides with a truncated polysaccharide fragment. it is concluded that, due to high viability of these ... | 2005 | 16004277 |
| interactions between cytochrome c2 and the photosynthetic reaction center from rhodobacter sphaeroides: the cation-pi interaction. | the cation-pi interaction between positively charged and aromatic groups is a common feature of many proteins and protein complexes. the structure of the complex between cytochrome c(2) (cyt c(2)) and the photosynthetic reaction center (rc) from rhodobacter sphaeroides exhibits a cation-pi complex formed between arg-c32 on cyt c(2) and tyr-m295 on the rc [axelrod, h. l., et al. (2002) j. mol. biol. 319, 501-515]. the importance of the cation-pi interaction for binding and electron transfer was s ... | 2005 | 16008347 |
| identification of genes required for recycling reducing power during photosynthetic growth. | photosynthetic organisms have the unique ability to transform light energy into reducing power. we study the requirements for photosynthesis in the alpha-proteobacterium rhodobacter sphaeroides. global gene expression analysis found that approximately 50 uncharacterized genes were regulated by changes in light intensity and o\2 tension, similar to the expression of genes known to be required for photosynthetic growth of this bacterium. these uncharacterized genes included rsp4157 to -4159, which ... | 2005 | 16030219 |
| x-ray structure of rhodobacter capsulatus cytochrome bc (1): comparison with its mitochondrial and chloroplast counterparts. | ubihydroquinone: cytochrome (cyt)c oxidoreductase, or cyt bc (1), is a widespread, membrane integral enzyme that plays a crucial role during photosynthesis and respiration. it is one of the major contributors of the electrochemical proton gradient, which is subsequently used for atp synthesis. the simplest form of the cyt bc (1) is found in bacteria, and it contains only the three ubiquitously conserved catalytic subunits: the fe-s protein, cyt b and cyt c (1). here we present a preliminary x-ra ... | 2004 | 16034531 |
| aerobic synthesis of vitamin b12: ring contraction and cobalt chelation. | the aerobic biosynthetic pathway for vitamin b12 (cobalamin) biosynthesis is reviewed. particular attention is focused on the ring contraction process, whereby an integral carbon atom of the tetrapyrrole-derived macrocycle is removed. previous work had established that this chemically demanding step is facilitated by the action of a mono-oxygenase called cobg, which generates a hydroxy lactone intermediate. this mono-oxygenase contains both a non-haem iron and an fe-s centre, but little informat ... | 2005 | 16042605 |
| ubiquinone reduction in the photosynthetic reaction centre of rhodobacter sphaeroides: interplay between electron transfer, proton binding and flips of the quinone ring. | this review is focused on reactions that gate (control) the electron transfer between the primary quinone q(a) and secondary quinone q(b) in the photosynthetic reaction centre of rhodobacter sphaeroides. the results on electron and proton transfer are discussed in relation to structural information and to the steered molecular dynamics simulations of the q(b) ring flip in its binding pocket. depending on the initial position of q(b) in the pocket and on certain conditions, the rate of electron t ... | 2005 | 16042612 |
| rewiring photosynthesis: engineering wrong-way electron transfer in the purple bacterial reaction centre. | the purple bacterial reaction centre uses light energy to separate charge across the cytoplasmic membrane, reducing ubiquinone and oxidizing a c-type cytochrome. the protein possesses a macroscopic structural two-fold symmetry but displays a strong functional asymmetry, with only one of two available membrane-spanning branches of cofactors (the so-called a-branch) being used to catalyse photochemical charge separation. the factors underlying this functional asymmetry have been the subject of stu ... | 2005 | 16042613 |
| active membrane transport and receptor proteins from bacteria. | a general strategy for the expression of bacterial membrane transport and receptor genes in escherichia coli is described. expression is amplified so that the encoded proteins comprise 5-35% of e. coli inner membrane protein. depending upon their topology, proteins are produced with rgsh6 or a strep tag at the c-terminus. these enable purification in mg quantities for crystallization and nmr studies. examples of one nutrient uptake and one multidrug extrusion protein from helicobacter pylori are ... | 2005 | 16042616 |
| enlarging the gas access channel to the active site renders the regulatory hydrogenase hupuv of rhodobacter capsulatus o2 sensitive without affecting its transductory activity. | in the photosynthetic bacterium rhodobacter capsulatus, the synthesis of the energy-producing hydrogenase, hupsl, is regulated by the substrate h2, which is detected by a regulatory hydrogenase, hupuv. the hupuv protein exhibits typical features of [nife] hydrogenases but, interestingly, is resistant to inactivation by o2. understanding the o2 resistance of hupuv will help in the design of hydrogenases with high potential for biotechnological applications. to test whether this property results f ... | 2005 | 16045760 |
| role of trehalose synthesis pathways in salt tolerance mechanism of rhodobacter sphaeroides f. sp. denitrificans il106. | the photosynthetic bacterium rhodobacter sphaeroides (r. sphaeroides) f. sp. denitrificans il106 accumulates trehalose as the major organic osmoprotectant in response to a salt stress. an analysis of the r. sphaeroides 2.4.1 genome sequence revealed the presence of five different genes encoding enzymes belonging to three putative trehalose biosynthesis pathways (otsa-otsb, trey-trez, and tres). the function of the different pathways of trehalose was studied by characterizing strains defective in ... | 2005 | 16052332 |
| adenosine diphosphate moiety does not participate in structural changes for the signaling state in the sensor of blue-light using fad domain of appa. | a sensor of blue light using fad (bluf) protein is a flavin adenine dinucleotide (fad) based new class blue-light sensory flavoprotein. the bluf domain of appa was reconstituted in vitro from apoprotein and flavin adenine dinucleotide, flavin adenine mononucleotide or riboflavin. the light-induced ftir spectra of the domain reconstituted from various flavins and the 13c-labeled apoprotein showed that identical light-induced structural changes occur in both the flavin chromophore and protein for ... | 2005 | 16055119 |
| an arginine to lysine mutation in the vicinity of the heme propionates affects the redox potentials of the hemes and associated electron and proton transfer in cytochrome c oxidase. | cytochrome c oxidase pumps protons across a membrane using energy from electron transfer and reduction of oxygen to water. it is postulated that an element of the energy transduction mechanism is the movement of protons to the vicinity of the hemes upon reduction, to favor charge neutrality. possible sites on which protons could reside, in addition to the conserved carboxylate e286, are the propionate groups of heme a and/or heme a(3). a highly conserved pair of arginines (r481 and r482) interac ... | 2005 | 16060654 |
| the protonation state of a heme propionate controls electron transfer in cytochrome c oxidase. | in cytochrome c oxidase (cco), exergonic electron transfer reactions from cytochrome c to oxygen drive proton pumping across the membrane. elucidation of the proton pumping mechanism requires identification of the molecular components involved in the proton transfer reactions and investigation of the coupling between internal electron and proton transfer reactions in cco. while the proton-input trajectory in cco is relatively well characterized, the components of the output pathway have not been ... | 2005 | 16060655 |
| water chain formation and possible proton pumping routes in rhodobacter sphaeroides cytochrome c oxidase: a molecular dynamics comparison of the wild type and r481k mutant. | cytochrome c oxidase (cco) converts the energy from redox and oxygen chemistry to support proton translocation and create a transmembrane deltamuh(+) used for atp production. molecular dynamics (md) simulations were carried out to probe for the formation water chains capable of participating in proton translocation. attention was focused on the region between and above the a and a(3) hemes where well-defined water chains have not been identified in crystallographic studies. an arginine (r481) (r ... | 2005 | 16060656 |
| binding dynamics at the quinone reduction (qi) site influence the equilibrium interactions of the iron sulfur protein and hydroquinone oxidation (qo) site of the cytochrome bc1 complex. | multiple instances of low-potential electron-transport pathway inhibitors that affect the structure of the cytochrome (cyt) bc(1) complex to varying degrees, ranging from changes in hydroquinone (qh(2)) oxidation and cyt c(1) reduction kinetics to proteolytic accessibility of the hinge region of the iron-sulfur-containing subunit (fe/s protein), have been reported. however, no instance has been documented of any ensuing change on the environment(s) of the [2fe-2s] cluster. in this work, this iss ... | 2005 | 16060661 |
| heavy metal ion influence on the photosynthetic growth of rhodobacter sphaeroides. | the potential of purple non-sulphur bacteria for bioremediation was assessed by investigating the ability of rhodobacter sphaeroides strain r26.1 to grow photosynthetically in heavy metal contaminated environments. bacterial cultures were carried out in artificially polluted media, enriched with the transition metal ions hg2+, cu2+, fe2+, ni2+, co2+, moo4(2-), and cro4(2-) in millimolar concentration range. for each investigated ion the effect on growth parameters was evaluated. the analysis of ... | 2006 | 16081134 |
| high pressure near infrared study of the mutated light-harvesting complex lh2. | the pressure sensitivities of the near infrared spectra of the light-harvesting (lh2) complex and a mutant complex with a simplified bchl-b850 binding pocket were compared. in the mutant an abrupt change in the spectral properties occurred at 250 mpa, which was not observed with the native sample. increased disorder due to collapse of the chromophore pocket is suggested. | 2005 | 16082470 |
| two enzymes, btaa and btab, are sufficient for betaine lipid biosynthesis in bacteria. | betaine lipids are non-phosphorous glycerolipid analogs of phosphatidylcholine. the biosynthesis of the betaine lipid diacylglyceryl-n,n,n-trimethylhomoserine has previously been studied in phosphate-starved cells of the purple bacterium rhodobacter sphaeroides, and a genetic approach identified two proteins that are necessary for this process. here, we show that all reactions of dgts biosynthesis in r. sphaeroides are attributable to rsbtaa and rsbtab, as co-expression of the respective genes l ... | 2005 | 16095555 |
| modeling binding kinetics at the q(a) site in bacterial reaction centers. | bacterial reaction centers (rcs) catalyze a series of electron-transfer reactions reducing a neutral quinone to a bound, anionic semiquinone. the dissociation constants and association rates of 13 tailless neutral and anionic benzo- and naphthoquinones for the q(a) site were measured and compared. the k(d) values for these quinones range from 0.08 to 90 microm. for the eight neutral quinones, including duroquinone (dq) and 2,3-dimethoxy-5-methyl-1,4-benzoquinone (uq(0)), the quinone concentratio ... | 2005 | 16101283 |
| residues that influence in vivo and in vitro cbbr function in rhodobacter sphaeroides and identification of a specific region critical for co-inducer recognition. | cbbr is a lysr-type transcriptional regulator (lttr) that is required to activate transcription of the cbb operons, responsible for co2 fixation, in rhodobacter sphaeroides. lttr proteins often require a co-inducer to regulate transcription. previous studies suggested that ribulose 1,5-bisphosphate (rubp) is a positive effector for cbbr function in this organism. in the current study, rubp was found to increase the electrophoretic mobility of the cbbr/cbb(i) promoter complex. to define and analy ... | 2005 | 16102008 |
| structure of a bacterial bluf photoreceptor: insights into blue light-mediated signal transduction. | light is an essential environmental factor, and many species have evolved the capability to respond to it. blue light is perceived through three flavin-containing photoreceptor families: cryptochromes, light-oxygen-voltage, and bluf (sensor of blue light using flavin adenine dinucleotide, fad) domain proteins. bluf domains are present in various proteins from bacteria and lower eukarya. they are fully modular and can relay signals to structurally and functionally diverse output units, most of wh ... | 2005 | 16107542 |
| identification of genes of vsh-1, a prophage-like gene transfer agent of brachyspira hyodysenteriae. | vsh-1 is a mitomycin c-inducible prophage of the anaerobic spirochete brachyspira hyodysenteriae. purified vsh-1 virions are noninfectious, contain random 7.5-kb fragments of the bacterial genome, and mediate generalized transduction of b. hyodysenteriae cells. in order to identify and sequence genes of this novel gene transfer agent (gta), proteins associated either with vsh-1 capsids or with tails were purified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the n-terminal amino ... | 2005 | 16109929 |