| pathways involved in reductant distribution during photobiological h(2) production by rhodobacter sphaeroides. | we used global transcript analyses and mutant studies to investigate the pathways that impact h(2) production in the photosynthetic bacterium rhodobacter sphaeroides. we found that h(2) production capacity is related to the levels of expression of the nitrogenase and hydrogenase enzymes and the enzymes of the calvin-benson-bassham pathway. | 2011 | 21856820 |
| Functional and structural effects of seven-residue deletions on the coiled-coil cytoplasmic domain of a chemoreceptor. | Chemoreceptors transmit signals from the environment to the flagellar motors via a histidine kinase that controls the phosphorylation level of the effector protein CheY. The cytoplasmic domain of chemoreceptors is strongly conserved and consists of a long alpha-helical hairpin that forms, in the dimer, a coiled-coil four-helix bundle. Changes in this domain during evolution are characterized by the presence of seven-residue insertions/deletions located symmetrically with respect to the hairpin t ... | 2012 | 22111959 |
| entrance of the proton pathway in cbb3-type heme-copper oxidases. | heme-copper oxidases (hcuos) are the last components of the respiratory chain in mitochondria and many bacteria. they catalyze o(2) reduction and couple it to the maintenance of a proton-motive force across the membrane in which they are embedded. in the mitochondrial-like, a family of hcuos, there are two well established proton transfer pathways leading from the cytosol to the active site, the d and the k pathways. in the c family (cbb(3)) hcuos, recent work indicated the use of only one pathw ... | 2011 | 21997215 |
| monoolein lipid phases as incorporation and enrichment materials for membrane protein crystallization. | the crystallization of membrane proteins in amphiphile-rich materials such as lipidic cubic phases is an established methodology in many structural biology laboratories. the standard procedure employed with this methodology requires the generation of a highly viscous lipidic material by mixing lipid, for instance monoolein, with a solution of the detergent solubilized membrane protein. this preparation is often carried out with specialized mixing tools that allow handling of the highly viscous m ... | 2011 | 21909395 |
| methods for the preparation of chlorophyllide a: an intermediate of the chlorophyll biosynthetic pathway. | chlorophyllide a is a metabolite late in the biosynthesis of chlorophylls and bacteriochlorophylls. isolation procedures for chlorophyllide a from rhodobacter capsulatus cb1200 and barley (hordeum vulgare l.) are described and compared. r. capsulatus cb1200 is a double mutant in the bacteriochlorophyllide a biosynthetic pathway, and chlorophyllide a is excreted by the cells when grown in tween 80-containing liquid medium. it was purified by liquid or solid phase extraction, yielding 7 mg of chlo ... | 2011 | 21925479 |
| Metabolic network modeling of redox balancing and biohydrogen production in purple nonsulfur bacteria. | Purple nonsulfur bacteria (PNSB) are facultative photosynthetic bacteria and exhibit an extremely versatile metabolism. A central focus of research on PNSB dealt with the elucidation of mechanisms by which they manage to balance cellular redox under diverse conditions, in particular under photoheterotrophic growth. | 2011 | 21943387 |
| Cross-species investigation of the functions of the Rhodobacter PufX polypeptide and the composition of the RC-LH1 core complex. | In well-characterised species of the Rhodobacter (Rba.) genus of purple photosynthetic bacteria it is known that the photochemical reaction centre (RC) is intimately-associated with an encircling LH1 antenna pigment protein, and this LH1 antenna is prevented from completely surrounding the RC by a single copy of the PufX protein. In Rba. veldkampii only monomeric RC-LH1 complexes are assembled in the photosynthetic membrane, whereas in Rba. sphaeroides and Rba. blasticus a dimeric form is also a ... | 2012 | 22079525 |
| Theoretical Study of the Electronic-Vibrational Coupling in the Q_Y States of the Photosynthetic Reaction Center in Purple Bacteria. | Inspired by the recent observation of correlated excitation energy fluctuations of neighboring chromophores (Lee et al. Science 316, 1462 (2007)), quantum chemistry calculations and molecular dynamics simulations were employed to calculate the electronic-vibrational coupling in the excited states of photosynthetic reaction center of purple bacteria Rhodobacter (Rb.) sphaeroides. The ground states and lowest excited (Qy) states of isolated bacteriochlorophyll a (BChla) and bacteriopheophytin (BPh ... | 2011 | 22188530 |
| primary charge separation within p870* in wild type and heterodimer mutants in femtosecond time domain. | primary charge separation dynamics in the reaction center (rc) of purple bacterium rhodobacter sphaeroides and its p870 heterodimer mutants have been studied using femtosecond time-resolved spectroscopy with 20 and 40fs excitation at 870nm at 293k. absorbance increase in the 1060-1130nm region that is presumably attributed to p(a)(δ+) cation radical molecule as a part of mixed state with a charge transfer character p*(p(a)(δ+)p(b)(δ-)) was found. this state appears at 120-180fs time delay in the ... | 2011 | 22209778 |
| Characterization of a newly discovered Mu-like bacteriophage, RcapMu, in Rhodobacter capsulatus strain SB1003. | The a-proteobacterium Rhodobacter capsulatus is a model organism for the study of bacterial photosynthesis and the bacteriophage-like gene transfer agent. Characterization of phages that infect Rhodobacter is extremely rare, and scarce for the a-proteobacteria in general. Here, we describe the discovery of the only functional Mu-like transposing phage to have been identified in the a-proteobacteria, RcapMu, resident in the genome-sequenced R. capsulatus SB1003 strain. RcapMu packages ~42kb of to ... | 2011 | 22018635 |
| a comparative spectroscopic and kinetic study of photoexcitations in detergent-isolated and membrane-embedded lh2 light-harvesting complexes. | integral membrane proteins constitute more than third of the total number of proteins present in organisms. solubilization with mild detergents is a common technique to study the structure, dynamics, and catalytic activity of these proteins in purified form. however beneficial the use of detergents may be for protein extraction, the membrane proteins are often denatured by detergent solubilization as a result of native lipid membrane interactions having been modified. versatile investigations of ... | 2011 | 22172735 |
| evolutionary origin of the rhodobacter sphaeroides specialized rpon sigma factors. | gene duplication and horizontal gene transfer (hgt) are two events that enable the generation of new genes. rhodobacter sphaeroides (ws8 and 2.4.1 strains) has four copies of the rpon gene that are not functionally interchangeable. until now, this is the only example of specialization of this sigma factor. in this work, we aimed to determine whether the multiple copies of this gene originated from hgt or through gene duplication. our results suggest a multiplication origin of the different rpon ... | 2011 | 22093079 |
| Biogenesis of cbb(3)-type cytochrome c oxidase in Rhodobacter capsulatus. | The cbb(3)-type cytochrome c oxidases (cbb(3)-Cox) constitute the second most abundant cytochrome c oxidase (Cox) group after the mitochondrial-like aa(3)-type Cox. They are present in bacteria only, and are considered to represent a primordial innovation in the domain of Eubacteria due to their phylogenetic distribution and their similarity to nitric oxide (NO) reductases. They are crucial for the onset of many anaerobic biological processes, such as anoxygenic photosynthesis or nitrogen fixati ... | 2011 | 22079199 |
| network identification and flux quantification of glucose metabolism in rhodobacter sphaeroides under photoheterotrophic h2-producing conditions. | the nonsulfur purple bacteria that exhibit unusual metabolic versatility can produce hydrogen gas (h(2)) using the electrons derived from metabolism of organic compounds during photoheterotrophic growth. here, based on (13)c tracer experiments, we identified the network of glucose metabolism and quantified intracellular carbon fluxes in rhodobacter sphaeroides kd131 grown under h(2)-producing conditions. moreover, we investigated how the intracellular fluxes in r. sphaeroides responded to knocko ... | 2012 | 22056932 |
| the rsp_2889 gene product of rhodobacter sphaeroides is a cuer homologue controlling copper-responsive genes. | metal homeostasis is important in all living cells in order to provide sufficient amounts of metal ions for biological processes but to prevent toxic effects by excess amounts. here we show that the gene product of rsp_2889 of the facultatively photosynthetic bacterium rhodobacter sphaeroides is homologous to cuer, a regulator of copper metabolism in escherichia coli and other bacteria. cuer binds to the promoter regions of genes for a copper-translocating atpase and for a copper chaperone and i ... | 2011 | 21903751 |
| rhodoferax-related pufm gene cluster dominates the aerobic anoxygenic phototrophic communities in german freshwater lakes. | the presence of aerobic anoxygenic phototrophs (aaps) has been repeatedly reported from various marine environments, but their distribution in freshwater lakes was neglected until recently. we investigated the phylogenetic composition of aap communities in 10 lakes in northeastern germany with different trophic status including oligotrophic lake stechlin and humic matter rich lake grosse fuchskuhle. the aap community was composed by members of alpha- and betaproteobacteria, but their contributio ... | 2011 | 21895915 |
| the resonance raman spectra of spheroidene revisited with a first-principles approach. | the resonance raman (rr) spectra of different configurations of spheroidene are calculated by means of quantum chemical methods to investigate the nature of the cis configuration of this carotenoid molecule in the photosynthetic reaction center (rc) of the purple bacterium rhodobacter sphaeroides. for validation of our methodology, we also calculate the spectrum of the all-trans structure present in the light-harvesting complexes of this bacterium. while former theoretical resonance raman studie ... | 2011 | 21954132 |
| Cytochrome c oxidase: Charge translocation coupled to single-electron partial steps of the catalytic cycle. | The paper presents a survey of time-resolved studies of charge translocation by cytochrome c oxidase coupled to transfer of the 1st, 2nd 3rd and 4th electrons in the catalytic cycle. Single-electron photoreduction experiments carried out with the A-class cytochrome c oxidases of aa(3) type from mitochondria, Rhodobacter sphaeroides and Paracoccus denitrificans as well as with the ba(3)-type oxidase from Thermus thermophilus indicate that the protonmotive mechanisms, although similar, may not be ... | 2011 | 21871433 |
| exploring the in situ accessibility of small subunit ribosomal rna of members of the domains bacteria and eukarya to oligonucleotide probes. | the principle that the small subunit ribosomal rna (ssu rrna) is generally accessible to oligonucleotide probes designed to have high thermodynamic affinity was tested with stenotrophomonas maltophilia, rhodobacter sphaeroides, bacillus subtilis, and saccharomyces cerevisiae. fluorescein-labeled probes, designed to have δg(overall)°=-14±1 and to avoid the potential of nucleobase-specific quenching, were used to target 20 randomly selected sites in each organism. a site was considered accessible ... | 2012 | 22264799 |
| photocurrent and electronic activities of oriented-his-tagged photosynthetic light-harvesting/reaction centre core complexes assembled onto a gold electrode. | a poly-histidine (his) tag was fused to the c- or n-terminus of the light-harvesting (lh1)-αchain of the photosynthetic antenna core complex (lh1-rc) from rhodobacter sphaeroides to allow immobilization of the complex on a solid substrate with defined orientation. his-tagged lh1-rcs were adsorbed onto a gold electrode modified with ni-nta. the lh1-rc with the c-terminal his-tag (c-his lh1-rc) on the modified electrode produced a photovoltaic response upon illumination. electron transfer is un ... | 2012 | 22239547 |
| effect of pumping on the spatio-temporal distribution of microbial communities in a water well field. | a water well field adjacent to the north saskatchewan river (city of north battleford, saskatchewan, canada) with a history of rapid deterioration of both well water quality and yield was selected to study the spatial and temporal distribution of subsurface microbial communities and their response to water pumping. a range of conventional cultural, microscopic and molecular techniques, including confocal laser scanning microscopy (clsm), biolog, qpcr and denaturing gradient gel electrophoresis ( ... | 2012 | 22227241 |
| transient absorption study of two-photon excitation mechanism in lh<sub>2</sub> complex from purple bacterium rhodobacter sphaeroides. | the mechanism of two-photon excitation of a peripheral light-harvesting complex lh2 (в800-850) from purple bacterium rhodobacter sphaeroides was explained on the basis of femtosecond transient absorption data. fast bleaching of the b850 absorption band was measured under two-photon excitation by 1350 nm femtosecond pulses, showing fast sub-picosecond arrival of excitation energy to b850 circular aggregates. any spectral changes connected with the b800 absorption band of b800-bchl molecules were ... | 2012 | 22268655 |