Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| light induced epr spectra of reaction centers from rhodobacter sphaeroides at 80k: evidence for reduction of q(b) by b-branch electron transfer in native reaction centers. | photosynthetic reaction centers (rcs) from rhodobacter sphaeroides capture solar energy by electron transfer from primary donor, d, to quinone acceptor, q(b,) through the active a-branch of electron acceptors, but not the inactive b-branch. the light induced epr spectrum from native rcs that had fe(2+) replaced by zn(2+) was investigated at cryogenic temperature (80k, 35 ghz). in addition to the light induced signal due to formation of d(+*)q(a) (-*) observed previously, a small fraction (~5%) o ... | 2007 | 18163156 |
| secondary structures and functional requirements for thim riboswitches from desulfovibrio vulgaris, erwinia carotovora and rhodobacter spheroides. | abstract bacterial thim riboswitches contain aptamer domains that bind the metabolite thiamine pyrophosphate (tpp). binding of tpp to the aptamer domain induces structural rearrangements that are relayed to the expression domain, thereby interfering with gene expression. here, we report identification of three putative thim riboswitches from different bacteria and analysis of their secondary structures. chemical probing revealed that the riboswitches share similar secondary structures in their a ... | 2008 | 18163882 |
| site-directed mutagenesis of substrate binding sites of azoreductase from rhodobacter sphaeroides. | comparison of three-dimensional structures of flavin-dependent azoreductases revealed two conserved loops around the flavin mononucleotide (fmn) cofactor. tyr74, his75 and lys109 in the two loops of azoreductase azr from rhodobacter sphaeroides were replaced with trp, asn and ala/his by site-directed mutagenesis, respectively. the optimal ph values of k109h and h75n were ph 6, and those of k109a and y74w were ph 9. the optimal temperature (30 degrees c) was not affected by mutation. positively c ... | 2008 | 18165868 |
| identification of proteins involved in formaldehyde metabolism by rhodobacter sphaeroides. | formaldehyde is an intermediate formed during the metabolism of methanol or other methylated compounds. many gram-negative bacteria generate formaldehyde from methanol via a periplasmic pyrroloquinoline quinone (pqq)-dependent dehydrogenase in which the alpha subunit of an alpha(2)beta(2) tetramer has catalytic activity. the genome of the facultative formaldehyde-oxidizing bacterium rhodobacter sphaeroides encodes xoxf, a homologue of the catalytic subunit of a proposed pqq-containing dehydrogen ... | 2008 | 18174148 |
| overproduction or absence of the periplasmic protease degp severely compromises bacterial growth in the absence of the dithiol: disulfide oxidoreductase dsba. | facultative phototrophic bacterium rhodobacter capsulatus dsba-null mutants are proficient in photosynthesis but are defective in respiration especially in enriched growth medium at 35 degrees c. they also exhibit severe pleiotropic phenotypes extending from motility defects to osmofragility and oxidative stresses. in this work, using a combined proteomics and molecular genetics approach, we demonstrated that the respiratory defect of r. capsulatus dsba-null mutants originates from the overprodu ... | 2008 | 18174153 |
| comparative study of catalase-peroxidases (katgs). | catalase-peroxidases or katgs from seven different organisms, including archaeoglobus fulgidus,bacillus stearothermophilus, burkholderia pseudomallei, escherichia coli, mycobacterium tuberculosis, rhodobacter capsulatus and synechocystis pcc 6803, have been characterized to provide a comparative picture of their respective properties. collectively, the enzymes exhibit similar turnover rates with the catalase and peroxidase reactions varying between 4900 and 15,900s(-1) and 8-25s(-1), respectivel ... | 2008 | 18178143 |
| energetics and role of the hydrophobic interaction during photoreaction of the bluf domain of appa. | a recently developed method for time-resolved thermodynamic measurements was used to study the photochemical reaction(s) of the bluf domain of appa (appa-bluf), which has a dimeric form in the ground state, in terms of the energetics and heat capacity changes (deltac(p)) in different time domains. the enthalpy change (deltah) of the first intermediate that forms within 1 ns after photoexcitation was 38 (+/-8) kj mol(-1) at 298 k. the heat capacity change (deltac(p)) upon formation of this interm ... | 2008 | 18189382 |
| photoactive yellow protein from the halophilic bacterium salinibacter ruber. | a gene for photoactive yellow protein (pyp) was identified from the genome sequence of the extremely halophilic aerobic bacterium salinibacter ruber (sr). the sequence is distantly related to the prototypic pyp from halorhodospira halophila (hh) (37% identity) and contains most of the amino acid residues identified as necessary for function. however, the sr pyp gene is not flanked by its two biosynthetic genes as in other species. to determine as to whether the sr pyp gene encodes a functional p ... | 2008 | 18198898 |
| wide turn diversity in protein transmembrane helices implications for g-protein-coupled receptor and other polytopic membrane protein structure and function. | previously, we showed that perturbations of protein transmembrane helices are manifested as one of three types of noncanonical structures (wide turns, tight turns, and kinks), which, compared with alpha-helices, are evident by distinctive calpha(i)-->calpha(x) distances. in this study, we report the analysis of more than 3000 transmembrane helices in 244 crystal structures from which we identified 70 wide turns (29 proline- and 41 nonproline-induced). based on differences in the calpha(i)-->calp ... | 2008 | 18202304 |
| primary radical pair p(+)h(-) lifetime in rhodobacter sphaeroides with blocked electron transfer to q(a). effect of o-phenanthroline. | transient absorption spectroscopy with a time resolution of approximately 1 ns was applied to study the decay of the primary radical pair p+h- in rhodobacter sphaeroides r-26 reaction centers with blocked electron transfer from h- to qa. the block in the electron transfer was realized in two ways: by either reducing or removing qa. we found very different kinetics of the p+h- decay in these two cases. convolution of the multiexponential decay with the instrument response function allowed resolut ... | 2008 | 18215032 |
| the human gastric pathogen helicobacter pylori has a potential acetone carboxylase that enhances its ability to colonize mice. | helicobacter pylori colonizes the human stomach and is the etiological agent of peptic ulcer disease. all three h. pylori strains that have been sequenced to date contain a potential operon whose products share homology with the subunits of acetone carboxylase (encoded by acxabc) from xanthobacter autotrophicus strain py2 and rhodobacter capsulatus strain b10. acetone carboxylase catalyzes the conversion of acetone to acetoacetate. genes upstream of the putative acxabc operon encode enzymes that ... | 2008 | 18215283 |
| electronic wiring of a multi-redox site membrane protein in a biomimetic surface architecture. | bioelectronic coupling of multi-redox-site membrane proteins was accomplished with cytochrome c oxidase (cco) as an example. a biomimetic membrane system was used for the oriented immobilization of the cco oxidase on a metal electrode. when the protein is immobilized with the cco binding side directed toward the electrode and reconstituted in situ into a lipid bilayer, it is addressable by direct electron transfer to the redox centers. electron transfer to the enzyme via the spacer, referred to ... | 2008 | 18222995 |
| determination of the spectral diffusion kernel of a protein by single-molecule spectroscopy. | the spectral dynamics of individual bacterial light-harvesting-2 pigment-protein complexes have been studied at 1.4 k. the data provided the spectral diffusion kernel of the optical transitions of the embedded b800 bacteriochlorophyll a pigments. this kernel can be described by either a single gaussian function or a superposition of gaussian functions. moreover, we found that the chromophores interact with two classes of tlss that can be distinguished by their distance from the chromophore and a ... | 2008 | 18232828 |
| molecular genetic analysis of a dimethylsulfoniopropionate lyase that liberates the climate-changing gas dimethylsulfide in several marine alpha-proteobacteria and rhodobacter sphaeroides. | the alpha-proteobacterium sulfitobacter ee-36 makes the gas dimethylsulfide (dms) from dimethylsulfoniopropionate (dmsp), an abundant antistress molecule made by many marine phytoplankton. we screened a cosmid library of sulfitobacter for clones that conferred to other bacteria the ability to make dms. one gene, termed dddl, was sufficient for this phenotype when cloned in pet21a and introduced into escherichia coli. close dddl homologues exist in the marine alpha-proteobacteria fulvimarina, lok ... | 2008 | 18237308 |
| delivery of nitric oxide for analysis of the function of cytochrome c'. | on delivery of nitric oxide (no) to protein samples (e.g., cytochrome c'), for spectroscopic experiments it is important to avoid exposure to oxygen and to remove contaminants from the no gas. we describe a number of techniques for steady-state uv/vis spectrophotometry and pre-steady-state stopped-flow spectrophotometry analysis of cytochrome c'. | 2008 | 18237625 |
| formation of engineered intersubunit disulfide bond in cytochrome bc1 complex disrupts electron transfer activity in the complex. | protein domain movement of the rieske iron-sulfur protein has been speculated to play an essential role in the bifurcated oxidation of ubiquinol catalyzed by the cytochrome bc1 complex. to better understand the electron transfer mechanism of the bifurcated ubiquinol oxidation at qp site, we fixed the head domain of isp at the cyt c1 position by creating an intersubunit disulfide bond between two genetically engineered cysteine residues: one at position 141 of isp and the other at position 180 of ... | 2008 | 18258178 |
| substrate-binding model of the chlorophyll biosynthetic magnesium chelatase bchh subunit. | photosynthetic organisms require chlorophyll and bacteriochlorophyll to harness light energy and to transform water and carbon dioxide into carbohydrates and oxygen. the biosynthesis of these pigments is initiated by magnesium chelatase, an enzyme composed of bchi, bchd, and bchh proteins, which catalyzes the insertion of mg(2+) into protoporphyrin ix (proto) to produce mg-protoporphyrin ix. bchi and bchd form an atp-dependent aaa(+) complex that transiently interacts with the proto-binding bchh ... | 2008 | 18263581 |
| molecular models predict light-induced glutamine tautomerization in bluf photoreceptors. | the recently discovered photoreceptor proteins containing bluf (sensor of blue light using fad) domains mediate physiological responses to blue light in bacteria and euglena. in bluf domains, blue light activates the flavin chromophore yielding a signaling state characterized by a approximately 10 nm red-shifted absorption. we developed molecular models for the dark and light states of the bluf domain of the rhodobacter sphaeroides appa protein, which are based on the crystal structures and quan ... | 2008 | 18263659 |
| partial site-specific assignment of a uniformly (13)c, (15)n enriched membrane protein, light-harvesting complex 1 (lh1), by solid state nmr. | partial site-specific assignments are reported for the solid state nmr spectra of light-harvesting complex 1, a 160 kda integral membrane protein. the assignments were derived from 600 mhz (15)n-(13)co-(13)calpha and (15)n-(13)calpha-(13)cx correlation spectra, using uniformly (13)c, (15)n enriched hydrated material, in an intact and precipitated form. sequential assignments were verified using characteristic (15)n-(13)calpha-(13)cbeta side chain chemical shifts observed in 3d experiments. terti ... | 2008 | 18267103 |
| role of the n-terminal region in the function of the photosynthetic bacterium transcription regulator ppsr. | ppsr is a transcription repressor for the gene cluster encoding photosystem genes in rhodobacter sphaeroides. repression activity is accomplished by dna binding on the promoter regions of the photosystem gene clusters, and depends on both the redox potential and the presence of antirepressor protein appa. to understand dna repression regulation by ppsr, we investigated the function of ppsr domains in self-association for dna binding. we constructed domain-deletion mutants and verified dna-bindin ... | 2008 | 18282179 |
| singlet oxygen generation in the reaction centers of rhodobacter sphaeroides. | singlet oxygen (1o2) generation in the reaction centers (rcs) of rhodobacter sphaeroides wild type was characterized by luminescent emission in the near infrared region (time resolved transients and emission spectra) and quantified to have quantum yield of 0.03 +/- 0.005. 1o2 emission was measured as a function of temperature, ascorbate, urea and potassium ferricyanide concentrations and as a function of incubation time in h2o:d2o mixtures. 1o2 was shown to be affected by the rc dynamics and to ... | 2008 | 18286272 |
| biological synthesis of gold nanowires using extract of rhodopseudomonas capsulata. | an environmentally friendly method using a cell-free extract (cfe) of rhodopseudomonas capsulata is proposed to synthesize gold nanowires with a network structure. this procedure offers control over the shapes of gold nanoparticles with the change of haucl4 concentration. the cfe solutions were added with different concentrations of haucl4, resulting in the bioreduction of gold ions and biosynthesis of morphologies of gold nanostructures. it is probable that proteins acted as the major biomolecu ... | 2008 | 18293997 |
| genes of rhodobacter sphaeroides 2.4.1 regulated by innate quorum-sensing signal, 7,8-cis-n-(tetradecenoyl) homoserine lactone. | the free-living photoheterotrophic gram-negative bacterium rhodobacter sphaeroides possesses a quorumsensing (qs) regulatory system mediated by cerr-ceri, a member of the luxr-luxi family. to identify the genes affected by the regulatory system, random lacz fusions were generated in the genome of r. sphaeroides strain 2.4.1 using a promoter-trapping vector, psg2. about 20,000 clones were screened and 23 showed a significantly different level of beta- gal activities upon the addition of synthetic ... | 2008 | 18309264 |
| three-dimensional reconstruction of a membrane-bending complex: the rc-lh1-pufx core dimer of rhodobacter sphaeroides. | a three-dimensional model of the dimeric reaction center-light harvesting i-pufx (rc-lh1-pufx) complex from rhodobacter sphaeroides, calculated from electron microscope single particle analysis of negatively stained complexes, shows that the two halves of the dimer molecule incline toward each other on the periplasmic side, creating a remarkable v-shaped structure. the distribution of negative stain is consistent with loose packing of the lh1 ring near the 14th lh1 alpha/beta pair, which could f ... | 2008 | 18326046 |
| effect of clay pretreatment on photofermentative hydrogen production from olive mill wastewater. | the aim of this paper was to gain further insight into the effect of the clay pretreatment process on photofermentative hydrogen production. this two-stage process involved a clay pretreatment step followed by photofermentation which was performed under anaerobic conditions with the illumination by tungsten lamps. rhodobacter sphaeroides o.u.001 was used for photofermentation. higher amounts of color (65%), total phenol (81%) and chemical oxygen demand (31%) removal efficiencies were achieved af ... | 2008 | 18334289 |
| modeling the active-site structure of the cbb3-type oxidase from rhodobacter sphaeroides. | the active site of the heme-copper oxidases comprises a redox-active high-spin heme and a tris-histidine copper center cu b. two amino acids in the close vicinity of the metals, a tyrosine and a tryptophan from helix 6, have been shown to be absolutely required for the catalytic function and should be considered part of the active site. additionally, amino acid residues from interhelical loops strongly modify the activity. in a separate subfamily of heme-copper oxidases, the cbb 3-type oxidases, ... | 2008 | 18338855 |
| on the signaling mechanism and the absence of photoreversibility in the appa bluf domain. | the flavoprotein appa from rhodobacter sphaeroides contains an n-terminal, fad-binding bluf photoreceptor domain. upon illumination, the appa bluf domain forms a signaling state that is characterized by red-shifted absorbance by 10 nm, a state known as appa(red). we have applied ultrafast spectroscopy on the photoaccumulated appa(red) state to investigate the photoreversible properties of the appa bluf domain. on light absorption by appa(red), the fad singlet excited state fad(red)* decays monoe ... | 2008 | 18339766 |
| cytochrome bc1-cy fusion complexes reveal the distance constraints for functional electron transfer between photosynthesis components. | photosynthetic (ps) growth of purple non-sulfur bacteria such as rhodobacter capsulatus depends on the cyclic electron transfer (et) between the ubihydroquinone (qh2): cytochrome (cyt) c oxidoreductases (cyt bc1 complex), and the photochemical reaction centers (rc), mediated by either a membrane-bound (cyt c(y)) or a freely diffusible (cyt c2) electron carrier. previously, we constructed a functional cyt bc1-c(y) fusion complex that supported ps growth solely relying on membrane-confined et ( le ... | 2008 | 18343816 |
| soluble variants of rhodobacter capsulatus membrane-anchored cytochrome cy are efficient photosynthetic electron carriers. | photosynthetic (ps) electron transport pathways often contain multiple electron carriers with overlapping functions. here we focus on two c-type cytochromes (cyt) in facultative phototrophic bacteria of the rhodobacter genus: the diffusible cyt c2 and the membrane-anchored cyt c(y). in species like r. capsulatus, cyt c(y) functions in both ps and respiratory electron transport chains, whereas in other species like r. sphaeroides, it does so only in respiration. the molecular bases of this differ ... | 2008 | 18343817 |
| contributions of conserved serine and tyrosine residues to catalysis, ligand binding, and cofactor processing in the active site of tyrosine ammonia lyase. | tyrosine ammonia lyase (tal) catalyzes the conversion of l-tyrosine to p-coumaric acid using a 3,5-dihydro-5-methylidene-4h-imidazole-4-one (mio) prosthetic group. in bacteria, tal is used for production of the photoactive yellow protein chromophore and for caffeic acid biosynthesis in certain actinomycetes. here we biochemically examine wild-type and mutant forms of tal from rhodobacter sphaeroides (rstal). kinetic analysis of rstal shows that the enzyme displays a 90-fold preference for l-tyro ... | 2008 | 18346767 |
| the redox midpoint potential of the primary quinone of reaction centers in chromatophores of rhodobacter sphaeroides is ph independent. | the redox midpoint potential (em) of the primary quinone of bacterial reaction centers, q(a), in native membranes (chromatophores) measured by redox potentiometry is reported to be ph dependent (-60 mv/ph) up to a highly distinctive pka (9.8 in rba. sphaeroides) for the reduced state. in contrast, the em of q(a) in isolated rcs of rba. sphaeroides, although more variable, has been found to be essentially ph-independent by both redox potentiometry and by delayed fluorescence, which determines the ... | 2008 | 18351330 |
| kinetics and yields of bacteriochlorophyll fluorescence: redox and conformation changes in reaction center of rhodobacter sphaeroides. | induction of the bacteriochlorophyll fluorescence under rectangular shape of intense laser diode illumination (1 w cm(-2), 808 nm) was measured over wide time range from 10 microseconds to 4 s in whole cells, chromatophore and isolated reaction center protein of wild type and carotenoid-less mutant (r-26.1) of purple photosynthetic bacterium rhodobacter sphaeroides. while the antenna-containing species showed large and positive variable fluorescence (fv) to initial fluorescence (f0) (fv/f0 appro ... | 2008 | 18351331 |
| the npra nitroreductase required for 2,4-dinitrophenol reduction in rhodobacter capsulatus is a dihydropteridine reductase. | the rhodobacter capsulatus npra gene codes for a putative nitroreductase. a recombinant his(6)-npra protein was overproduced in escherichia coli and purified by affinity chromatography. this protein contained fmn and showed nitroreductase activity with a wide range of nitroaromatic compounds, such as 2-nitrophenol, 2,4-dinitrophenol, 2,6-dinitrophenol, 2,4,6-trinitrophenol (picric acid), 2,4-dinitrobenzoate and 2,4-dinitrotoluene, and with the nitrofuran derivatives nitrofurazone and furazolidon ... | 2008 | 18355323 |
| bioremediation of cadmium by growing rhodobacter sphaeroides: kinetic characteristic and mechanism studies. | the removal kinetic characteristic and mechanism of cadmium by growing rhodobacter sphaeroides were investigated. the removal data were fitted to the second-order equation, with a correlation coefficient, r2=0.9790-0.9916. furthermore, it was found that the removal mechanism of cadmium was predominantly governed by bioprecipitation as cadmium sulfide with biosorption contributing to a minor extent. also, the results revealed that the activities of cysteine desulfhydrase in strains grown in the p ... | 2008 | 18358716 |
| nb-protein (bchn-bchb) of dark-operative protochlorophyllide reductase is the catalytic component containing oxygen-tolerant fe-s clusters. | dark-operative protochlorophyllide (pchlide) oxidoreductase is a nitrogenase-like enzyme consisting of the two components, l-protein (bchl-dimer) and nb-protein (bchn-bchb-heterotetramer). here, we show that nb-protein is the catalytic component with fe-s clusters. nb-protein purified from rhodobacter capsulatus bound pchlide that was readily converted to chlorophyllide a upon the addition of l-protein and mg-atp. the activity of nb-protein was resistant to the exposure to air. a pchlide-free fo ... | 2008 | 18358835 |
| fine tuning of the spectral properties of lh2 by single amino acid residues. | the peripheral light-harvesting complex, lh2, of rhodobacter sphaeroides consists of an assembly of membrane-spanning alpha and beta polypeptides which assemble the photoactive bacteriochlorophyll and carotenoid molecules. in this study we systematically investigated bacteriochlorophyll-protein interactions and their effect on functional bacteriochlorophyll assembly by site-directed mutations of the lh2 alpha-subunit. the amino acid residues, isoleucine at position -1 and serine at position -4 w ... | 2008 | 18365764 |
| turnover of ubiquinone-0 at the acceptor side of photosynthetic reaction center. | the steady-state operation of photosynthetic reaction center from rhodobacter sphaeroides was investigated by measuring the rate of cytochrome photo-oxidation under intensive continuous illumination (808 nm, 5 w cm(-2)). the native quinone uq10 in q(b) binding site of the reaction center was substituted by tailless uq0 and the binding parameters and the turnover rate of the uq0 was studied to test the recently discovered light-intensity dependent acceptor side effect (gerencsér and maróti 2006). ... | 2008 | 18368404 |
| [utilization test-systems "novastreak" for speeded analys of contamination microorganism food products]. | the comparative studies of biological properties of test-systems "novastreak" (novamed ltd, israel) were made. the sensitivity of these systems allows to detect total bacterial count in food products. to assess microbial cleanliness for other groups of microorganisms (coliforms, salmonella, fungi) them sensitivity is not enough and in case a negative results during analysis of samples are obtained additional control by means of traditional methods should be made. | 2008 | 18368854 |
| the mechanism of assembly and cofactor insertion into rhodobacter capsulatus xanthine dehydrogenase. | rhodobacter capsulatus xanthine dehydrogenase (xdh) is a molybdo-flavoprotein that is highly homologous to the homodimeric mammalian xanthine oxidoreductase. however, the bacterial enzyme has an (alphabeta)(2) heterotetrameric structure, and the cofactors were identified to be located on two different polypeptides. we have analyzed the mechanism of cofactor insertion and subunit assembly of r. capsulatus xdh, using engineered subunits with appropriate substitutions in the interfaces. in an (alph ... | 2008 | 18390908 |
| charge transfer in the k proton pathway linked to electron transfer to the catalytic site in cytochrome c oxidase. | cytochrome c oxidase couples electron transfer from cytochrome c to o 2 to proton pumping across the membrane. in the initial part of the reaction of the reduced cytochrome c oxidase with o 2, an electron is transferred from heme a to the catalytic site, parallel to the membrane surface. even though this electron transfer is not linked to proton uptake from solution, recently belevich et al. [(2006) nature 440, 829] showed that it is linked to transfer of charge perpendicular to the membrane sur ... | 2008 | 18393448 |
| kinetic study approach of remazol black-b use for the development of two-stage anoxic-oxic reactor for decolorization/biodegradation of azo dyes by activated bacterial consortium. | the laboratory-isolated strains pseudomonas aeruginosa, rhodobacter sphaeroides, proteus mirabilis, bacillus circulance, nad 1 and nad 6 were observed to be predominant in the bacterial consortium responsible for effective decolorization of the azo dyes. the kinetic characteristics of azo dye decolorization by bacterial consortium were determined quantitatively using reactive vinyl sulfonated diazo dye, remazol black-b (rb-b) as a model substrate. effects of substrate (rb-b) concentration as wel ... | 2008 | 18394798 |
| identification of six new photoactive yellow proteins--diversity and structure-function relationships in a bacterial blue light photoreceptor. | photoactive yellow proteins (pyp) are bacterial photoreceptors with a per-arnt-sim (pas) domain fold. we report the identification of six new pyps, thus nearly doubling the size of this protein family. this extends the taxonomic diversity of pyp-containing bacteria from photosynthetic to nonphotosynthetic bacteria, from aquatic to soil-dwelling organisms, and from proteobacteria to salinibacter ruber from the phylum bacteriodetes. the new pyps greatly increase the sequence diversity of the pyp f ... | 2008 | 18399917 |
| temperature dependence of electron transfer to the m-side bacteriopheophytin in rhodobacter capsulatus reaction centers. | subpicosecond time-resolved absorption measurements at 77 k on two reaction center (rc) mutants of rhodobacter capsulatus are reported. in the d(ll) mutant the d helix of the m subunit has been substituted with the d helix from the l subunit, and in the d(ll)-fy(l)f(m) mutant, three additional mutations are incorporated that facilitate electron transfer to the m side of the rc. in both cases the helix swap has been shown to yield isolated rcs that are devoid of the native bacteriopheophytin elec ... | 2008 | 18402487 |
| identification of the first steps in charge separation in bacterial photosynthetic reaction centers of rhodobacter sphaeroides by ultrafast mid-infrared spectroscopy: electron transfer and protein dynamics. | time-resolved visible pump/mid-infrared (mid-ir) probe spectroscopy in the region between 1600 and 1800 cm(-1) was used to investigate electron transfer, radical pair relaxation, and protein relaxation at room temperature in the rhodobacter sphaeroides reaction center (rc). wild-type rcs both with and without the quinone electron acceptor q(a), were excited at 600 nm (nonselective excitation), 800 nm (direct excitation of the monomeric bacteriochlorophyll (bchl) cofactors), and 860 nm (direct ex ... | 2008 | 18424493 |
| rhodobacter sphaeroides: complexity in chemotactic signalling. | most bacteria have much more complex chemosensory systems than those of the extensively studied escherichia coli. rhodobacter sphaeroides, for example, has multiple homologues of the e. coli chemosensory proteins. the roles of these homologues have been extensively investigated using a combination of deletion, subcellular localization and phosphorylation assays. these studies have shown that the homologues have specific roles in the sensory pathway, and they differ in their cellular localization ... | 2008 | 18440816 |
| a computational strategy to analyze label-free temporal bottom-up proteomics data. | biological systems are in a continual state of flux, which necessitates an understanding of the dynamic nature of protein abundances. the study of protein abundance dynamics has become feasible with recent improvements in mass spectrometry-based quantitative proteomics. however, a number of challenges still remain related to how best to extract biological information from dynamic proteomics data, for example, challenges related to extraneous variability, missing abundance values, and the identif ... | 2008 | 18442284 |
| crystallization of a flavodoxin involved in nitrogen fixation in rhodobacter capsulatus. | flavodoxins are small electron-transfer proteins that contain one molecule of noncovalently bound flavin mononucleotide (fmn). the flavodoxin niff from the photosynthetic bacterium rhodobacter capsulatus is reduced by one electron from ferredoxin/flavodoxin:nadp(h) reductase and was postulated to be an electron donor to nitrogenase in vivo. niff was cloned and overexpressed in escherichia coli, purified and concentrated for crystallization using the hanging-drop vapour-diffusion method at 291 k. ... | 2008 | 18453705 |
| the fe2+ site of photosynthetic reaction centers probed by multiple scattering x-ray absorption fine structure spectroscopy: improving structure resolution in dry matrices. | we report on the x-ray absorption fine structure of the fe(2+) site in photosynthetic reaction centers from rhodobacter sphaeroides. crystallographic studies show that fe(2+) is ligated with four n(epsilon) atoms from four histidine (his) residues and two o(epsilon) atoms from a glu residue. by considering multiple scattering contributions to the x-ray absorption fine structure function, we improved the structural resolution of the site: his residues were split into two groups, characterized by ... | 2008 | 18456824 |
| impaired proton pumping in cytochrome c oxidase upon structural alteration of the d pathway. | cytochrome c oxidase is a membrane-bound enzyme, which catalyses the one-electron oxidation of four molecules of cytochrome c and the four-electron reduction of o(2) to water. electron transfer through the enzyme is coupled to proton pumping across the membrane. protons that are pumped as well as those that are used for o(2) reduction are transferred though a specific intraprotein (d) pathway. results from earlier studies have shown that replacement of residue asn139 by an asp, at the beginning ... | 2008 | 18457654 |
| structure, function and interactions of the pufx protein. | the pufx protein is an important component of the reaction centre-light-harvesting 1 (rc-lh1) complex of rhodobacter species of purple photosynthetic bacteria. early studies showed that removal of the pufx protein causes changes in the structure of the rc-lh1 complex that result in a loss of the capacity for photosynthetic growth, and that this loss can be overcome though further mutations that change the structure of the lh1 antenna. more recent studies have examined interactions of the pufx pr ... | 2008 | 18460337 |
| diversity and distribution of ecotypes of the aerobic anoxygenic phototrophy gene pufm in the delaware estuary. | the diversity of aerobic anoxygenic phototrophic (aap) bacteria has been examined in marine habitats, but the types of aap bacteria in estuarine waters and distribution of ecotypes in any environment are not well known. the goal of this study was to determine the diversity of aap bacteria in the delaware estuary and to examine the distribution of select ecotypes using quantitative pcr (qpcr) assays for the pufm gene, which encodes a protein in the light reaction center of aap bacteria. in pcr li ... | 2008 | 18469118 |
| the 2-methoxy group of ubiquinone is essential for function of the acceptor quinones in reaction centers from rba. sphaeroides. | the orientation of a methoxy substituent is known to substantially influence the electron affinity and vibrational spectroscopy of benzoquinones, and has been suggested to be important in determining the function of ubiquinone as a redox cofactor in bioenergetics. ubiquinone functions as both the primary (q(a)) and secondary (q(b)) quinone in the reaction centers of many purple photosynthetic bacteria, and is almost unique in its ability to establish the necessary redox free energy gap for 1-ele ... | 2008 | 18474215 |
| dimers of light-harvesting complex 2 from rhodobacter sphaeroides characterized in reconstituted 2d crystals with atomic force microscopy. | microscopic and light spectroscopic investigations on the supramolecular architecture of bacterial photosynthetic membranes have revealed the photosynthetic protein complexes to be arranged in a densely packed energy-transducing network. protein packing may play a determining role in the formation of functional photosynthetic domains and membrane curvature. to further investigate in detail the packing effects of like-protein photosynthetic complexes, we report an atomic force microscopy investig ... | 2008 | 18479459 |
| evolution of taxis responses in virtual bacteria: non-adaptive dynamics. | bacteria are able to sense and respond to a variety of external stimuli, with responses that vary from stimuli to stimuli and from species to species. the best-understood is chemotaxis in the model organism escherichia coli, where the dynamics and the structure of the underlying pathway are well characterised. it is not clear, however, how well this detailed knowledge applies to mechanisms mediating responses to other stimuli or to pathways in other species. furthermore, there is increasing expe ... | 2008 | 18483577 |
| role of the global transcriptional regulator prra in rhodobacter sphaeroides 2.4.1: combined transcriptome and proteome analysis. | the prrba two-component regulatory system is a major global regulator in rhodobacter sphaeroides 2.4.1. here we have compared the transcriptome and proteome profiles of the wild-type (wt) and mutant prra2 cells grown anaerobically in the dark with dimethyl sulfoxide as an electron acceptor. approximately 25% of the genes present in the prra2 genome are regulated by prra at the transcriptional level, either directly or indirectly, by twofold or more relative to the wt. the genes affected are wide ... | 2008 | 18487335 |
| dynamics of rhodobacter capsulatus [2fe-2s] ferredoxin vi and aquifex aeolicus ferredoxin 5 via nuclear resonance vibrational spectroscopy (nrvs) and resonance raman spectroscopy. | we have used (57)fe nuclear resonance vibrational spectroscopy (nrvs) to study the fe(2)s(2)(cys)(4) sites in oxidized and reduced [2fe-2s] ferredoxins from rhodobacter capsulatus (rc fdvi) and aquifex aeolicus (aa fd5). in the oxidized forms, nearly identical nrvs patterns are observed, with strong bands from fe-s stretching modes peaking around 335 cm(-1), and additional features observed as high as the b(2u) mode at approximately 421 cm(-1). both forms of rc fdvi have also been investigated b ... | 2008 | 18512953 |
| [rhodobaca barguzinensis sp. nov., a new alkaliphilic purple nonsulfur bacterium isolated from a soda lake of the barguzin valley (buryat republic, eastern siberia)]. | a novel strain, alga-05, of alkaliphilic purple nonsulfur bacteria was isolated from sediments of a small saline (60 g/l) soda lake near lake algin (barguzin valley, buryat republic, russia). these bacteria contain bacteriochlorophyll a and carotenoids of the alternative spirilloxanthin group with predominating demethylspheroidenone. they are facultative anaerobes; their photosynthetic structures are of the vesicular type and arranged along the cell periphery. growth of this strain is possible i ... | 2008 | 18522327 |
| rhodobacter ovatus sp. nov., a phototrophic alphaproteobacterium isolated from a polluted pond. | a novel ovoid, phototrophic, purple non-sulfur bacterium was isolated in pure culture from a sample of sediment from an industrially polluted pond (noor mohammad kunta) in hyderabad, india. strain ja234(t) was found to be gram-negative and non-motile and grew photoheterotrophically with a number of organic compounds serving as carbon source/electron donor. photo-organoheterotrophic and chemo-organoheterotrophic growth were demonstrated. biotin and thiamine were required for growth of strain ja23 ... | 2008 | 18523181 |
| stability of integral membrane proteins under high hydrostatic pressure: the lh2 and lh3 antenna pigment-protein complexes from photosynthetic bacteria. | the bacteriochlorophyll a-containing lh2 and lh3 antenna complexes are the integral membrane proteins that catalyze the photosynthetic process in purple photosynthetic bacteria. the lh2 complex from rhodobacter sphaeroides shows characteristic strong absorbance at 800 and 850 nm due to the pigment molecules confined in two separate areas of the protein. in the lh3 complex from rhodopesudomonas acidophila the corresponding bands peak at 800 and 820 nm. using the bacteriochlorophyll a cofactors as ... | 2008 | 18537288 |
| isolation of a thermotolerant photosynthetic bacterium, rhodobacter sphaeroides strain, nat, and its capacity for oil and chemical oxygen demand removal at high temperatures. | a thermotolerant photosynthetic bacterium nat identified as rhodobacter sphaeroides was isolated. when alginate-immobilized cells of strain nat were used in high-temperature treatment of artificial sewage wastewater containing oil, the chemical oxygen demand (cod) decreased by 80% and 76% of the oil was removed after 96 h of treatment at 55 degrees c. lipase activity was observed in the culture. | 2008 | 18540094 |
| theoretical and computational analysis of the membrane potential generated by cytochrome c oxidase upon single electron injection into the enzyme. | we have developed theory and the computational scheme for the analysis of the kinetics of the membrane potential generated by cytochrome c oxidase upon single electron injection into the enzyme. the theory allows one to connect the charge motions inside the enzyme to the membrane potential observed in the experiments by using data from the "dielectric topography" map of the enzyme that we have created. the developed theory is applied for the analysis of the potentiometric data recently reported ... | 2008 | 18541140 |
| enhancing survival of escherichia coli by expression of azoreductase azr possessing quinone reductase activity. | quinone reductase activity of azoreductase azr from rhodobacter sphaeroides was reported. high homologies were found in the cofactor/substrate-binding regions of quinone reductases from different domains. 3d structure comparison revealed that azr shared a common overall topology with mammal nad(p)h/quinone oxidoreductase nqo1. with menadione as substrate, the optimal ph value and temperature were ph 8-9 and 50 degrees c, respectively. following the ping-pong kinetics, azr transferred two electro ... | 2008 | 18548247 |
| stability of the cbb3-type cytochrome oxidase requires specific ccoq-ccop interactions. | cytochrome cbb(3)-type oxidases are members of the heme copper oxidase superfamily and are composed of four subunits. ccon contains the heme b-cu(b) binuclear center where oxygen is reduced, while ccop and ccoo are membrane-bound c-type cytochromes thought to channel electrons from the donor cytochrome into the binuclear center. like many other bacterial members of this superfamily, the cytochrome cbb(3)-type oxidase contains a fourth, non-cofactor-containing subunit, which is termed ccoq. in th ... | 2008 | 18556791 |
| biotransformation of beta-amyrin acetate by rhodobacter sphaeroides. | the microbial transformation of beta-amyrin acetate (compound 1) occurred in the culture of rhodobacter sphaeroides producing three metabolites. the metabolites were purified and identified as beta-amyrin (compound 2), (3beta)-olean-12-ene-3, 23-diol (compound 3), and erythrodiol (compound 4). initially, it was found that beta-amyrin acetate could be deacetylated and hydroxylated by microbial methods. | 2008 | 18558349 |
| nanometer arrays of functional light harvesting antenna complexes by nanoimprint lithography and host-guest interactions. | we show an approach based on a combination of site-directed mutagenesis, nil and multivalent host-guest interactions for the realization of engineered ordered functional arrays of purified components of the photosynthetic system, the membrane-bound lh2 complex. in addition to micrometer-scale patterned structures, we demonstrated the use of nanometer-scale hard nil stamps to generate functional protein arrays approaching molecular dimensions. | 2008 | 18570413 |
| spiral tubular bioreactors for hydrogen production by photosynthetic microorganisms : design and operation. | spiral tubular bioreactors were constructed out of transparent pvc tubing for h2 production applications. both a cyanobacterial anabaena variabilis mutant that lacks uptake hydrogenase activity and the photosynthetic bacterium rhodobacter sp. cbs were tested in the bioreactors. continuous h2 photoproduction at an average rate of 19 ml min-2.h-1 was observed using the a. variabilis mutant under an air atmosphere (without argon sparging or application of a partial vacuum). the cyanobacterial photo ... | 1997 | 18576112 |
| glycotripod amphiphiles for solubilization and stabilization of a membrane-protein superassembly: importance of branching in the hydrophilic portion. | 2008 | 18576450 | |
| water activity regulates the q(a)(-) to q(b) electron transfer in photosynthetic reaction centers from rhodobacter sphaeroides. | we report on the effects of water activity and surrounding viscosity on electron transfer reactions taking place within a membrane protein: the reaction center (rc) from the photosynthetic bacterium rhodobacter sphaeroides. we measured the kinetics of charge recombination between the primary photoxidized donor (p(+)) and the reduced quinone acceptors. water activity (aw) and viscosity (eta) have been tuned by changing the concentration of cosolutes (trehalose, sucrose, glucose, and glycerol) and ... | 2008 | 18576650 |
| conformational control of the q(a) to q(b) electron transfer in bacterial reaction centers: evidence for a frozen conformational landscape below -25 degrees c. | the competition between the p(+)q(a)(-) --> pq(a) charge recombination (p, bacteriochlorophyll pair acting as primary photochemical electron donor) and the electron transfer to the secondary quinone acceptor q(a)(-)q(b) --> q(a)q(b)(-) (q(a) and q(b), primary and secondary electron accepting quinones) was investigated in chromatophores of rb. capsulatus, varying the temperature down to -65 degrees c. the analysis of the flash-induced pattern for the formation of p(+)q(a)q(b)(-) shows that the di ... | 2008 | 18588291 |
| rhodobacter maris sp. nov., a phototrophic alphaproteobacterium isolated from a marine habitat of india. | during investigations into the diversity of anoxygenic phototrophic bacteria in marine habitats, an ovoid to rod-shaped purple non-sulfur bacterium, designated strain ja276(t), was isolated from enrichments under photoheterotrophic conditions from a marine sediment sampled from the seashore of cochin, india. strain ja276(t) is a gram-negative, motile, chain-forming bacterium that shows optimum growth under photoheterotrophic conditions and is also able to grow chemoorganotrophically. thiamine is ... | 2008 | 18599723 |
| genetic analysis of trimethylamine n-oxide reductases in the light organ symbiont vibrio fischeri es114. | trimethylamine n-oxide (tmao) reductases are widespread in bacteria and often function in anaerobic respiration. the regulation and expression of tmao reductase operons have been well studied in model genera such as escherichia, shewanella, and rhodobacter, although tmao reductases are present in many other bacteria, including the marine vibrio species. the genome sequence of vibrio fischeri revealed three putative tmao reductase operons, and a previous report identified tmao reductase activity ... | 2008 | 18606737 |
| protein-matrix coupling/uncoupling in "dry" systems of photosynthetic reaction center embedded in trehalose/sucrose: the origin of trehalose peculiarity. | trehalose is a nonreducing disaccharide of glucose found in organisms, which can survive adverse conditions such as extreme drought and high temperatures. furthermore, isolated structures, as enzymes or liposomes, embedded in trehalose are preserved against stressing conditions [see, e.g., crowe, l. m. comp. biochem. physiol. a 2002, 131, 505-513]. among other hypotheses, such protective effect has been suggested to stem, in the case of proteins, from the formation of a water-mediated, hydrogen ... | 2008 | 18611016 |
| increasing efficiency of photoelectronic conversion by encapsulation of photosynthetic reaction center proteins in arrayed carbon nanotube electrode. | the construction of efficient light energy converting (photovoltaic and photoelectronic) devices is a current and great challenge in science and technology and one that will have important economic consequences. here we show that the efficiency of these devices can be improved by the utilization of a new type of nano-organized material having photosynthetic reaction center proteins encapsulated inside carbon nanotube arrayed electrodes. in this work, a generically engineered bacterial photosynth ... | 2008 | 18616302 |
| demonstration of short-lived complexes of cytochrome c with cytochrome bc1 by epr spectroscopy: implications for the mechanism of interprotein electron transfer. | one of the steps of a common pathway for biological energy conversion involves electron transfer between cytochrome c and cytochrome bc1. to clarify the mechanism of this reaction, we examined the structural association of those two proteins using the electron transfer-independent electron paramagnetic resonance (epr) techniques. drawing on the differences in the continuous wave epr spectra and saturation recoveries of spin-labeled bacterial and mitochondrial cytochromes c recorded in the absenc ... | 2008 | 18617515 |
| influence of the degree and mode of light limitation on growth characteristics of the rhodobacter capsulatus continuous cultures. | the influence of the degree and mode of light limitation on growth characteristics of turbidostat cultures of rhodobacter capsulatus was investigated using mass and energy balance regularities. light limitation was achieved by increasing the steady-state biomass concentration at constant incident light intensity ( approximately 100 w/m(2)) or by decreasing the incident light intensity at constant steady-state biomass concentration ( approximately 500 mg of dry biomass/l). it was shown that under ... | 1996 | 18629825 |
| average electron tunneling route of the electron transfer in protein media. | we present a new theoretical method to determine and visualize the average tunneling route of the electron transfer (et) in protein media. in this, we properly took into account the fluctuation of the tunneling currents and the quantum-interference effect. the route was correlated with the electronic factor <tda(2)> in the case of et by the elastic tunneling mechanism. we expanded <tda(2)> by the interatomic tunneling currents <jab(2)>'s. incorporating the quantum-interference effect into the me ... | 2008 | 18630851 |
| [effect of energy status of hydrogen bond protons on the rate of electron transfer in photosynthetic reaction centers]. | we present here a theoretical interpretation of the temperature dependence of the rate of dark recombination which takes place in rhodobacter sphaeroides reaction centers between a primary quinone (q(a)) and a bacteriochlorophyll dimer. taking the energy of interaction between hydrogen bond protons and an excessive electron into account, we described qualitative by this nonmonotonous dependence. we considered a molecular model of the primary quinone from rb. sphaeroides reaction centers. in addi ... | 2008 | 18634315 |
| energetics and kinetics of primary charge separation in bacterial photosynthesis. | we report the results of molecular dynamics (md) simulations and formal modeling of the free-energy surfaces and reaction rates of primary charge separation in the reaction center of rhodobacter sphaeroides. two simulation protocols were used to produce md trajectories. standard force-field potentials were employed in the first protocol. in the second protocol, the special pair was made polarizable to reproduce a high polarizability of its photoexcited state observed by stark spectroscopy. the c ... | 2008 | 18636767 |
| the role of aromatic phenylalanine residues in binding carotenoid to light-harvesting model and wild-type complexes. | the mode of carotenoid (crt) binding to polypeptide and specifying its function is as yet largely unknown. statistical analysis of major photosystems i and ii suggests that aromatic residues make up a significant part of the crt binding pockets. phenylalanine residues ensure approximately 25%--at some carbon atoms even up to 40%--of the total contacts with crts. by use of an alanine-leucine model transmembrane helix that replaces the native helix of the bacterial light-harvesting complex 2 (lh2) ... | 2008 | 18640123 |
| light-induced hydrogen bonding pattern and driving force of electron transfer in appa bluf domain photoreceptor. | the appa bluf (blue light sensing using fad) domain from rhodobacter sphaeroides serves as a blue light-sensing photoreceptor. the charge separation process between tyr-21 and flavin plays an important role in the light signaling state by transforming the dark state conformation to the light state one. by solving the linearized poisson-boltzmann equation, i calculated e(m) for tyr-21, flavin, and redox-active trp-104 and revealed the electron transfer (et) driving energy. rotation of the gln-63 ... | 2008 | 18647748 |
| ultrafast time-resolved carotenoid to-bacteriochlorophyll energy transfer in lh2 complexes from photosynthetic bacteria. | steady-state and ultrafast time-resolved optical spectroscopic investigations have been carried out at 293 and 10 k on lh2 pigment-protein complexes isolated from three different strains of photosynthetic bacteria: rhodobacter (rb.) sphaeroides g1c, rb. sphaeroides 2.4.1 (anaerobically and aerobically grown), and rps. acidophila 10050. the lh2 complexes obtained from these strains contain the carotenoids, neurosporene, spheroidene, spheroidenone, and rhodopin glucoside, respectively. these molec ... | 2008 | 18671366 |
| coupling of electron transfer to proton uptake at the q(b) site of the bacterial reaction center: a perspective from ftir difference spectroscopy. | ftir difference spectroscopy provides a unique approach to study directly protonation/deprotonation events of carboxylic acids involved in the photochemical cycle of membrane proteins, such as the bacterial photosynthetic reaction center (rc). in this work, we review the data obtained by light-induced ftir difference spectroscopy on the first electron transfer to the secondary quinone q(b) in native rcs and a series of mutant rcs. we first examine the approach of isotope-edited ftir spectroscopy ... | 2008 | 18671937 |
| the iron-sulfur cluster of electron transfer flavoprotein-ubiquinone oxidoreductase is the electron acceptor for electron transfer flavoprotein. | electron transfer flavoprotein-ubiquinone oxidoreductase (etf-qo) accepts electrons from electron transfer flavoprotein (etf) and reduces ubiquinone from the ubiquinone pool. it contains one [4fe-4s] (2+,1+) and one fad, which are diamagnetic in the isolated oxidized enzyme and can be reduced to paramagnetic forms by enzymatic donors or dithionite. in the porcine protein, threonine 367 is hydrogen bonded to n1 and o2 of the flavin ring of the fad. the analogous site in rhodobacter sphaeroides et ... | 2008 | 18672901 |
| rhodobacter megalophilus sp. nov., a phototroph from the indian himalayas possessing a wide temperature range for growth. | two strains of phototrophic, purple non-sulfur bacteria capable of growing at low temperatures (5 degrees c) were isolated from the himalayas. the two strains showed positive phototaxis and grew over a relatively wide temperature range (5-40 degrees c). phylogenetic analysis based on 16s rrna gene sequences showed that strain ja194t clustered with members of the genus rhodobacter. strain ja194t showed highest 16s rrna gene sequence similarity with rhodobacter sphaeroides dsm 158t (99 %). however ... | 2008 | 18676458 |
| photophysical properties of quinones and their interaction with the photosynthetic reaction centre. | photophysical properties of tetramethyl-1,4-benzoquinone (tmbq) and 2,6-dimethoxy-1,4-benzoquinone (dmobq) in solution and their interactions with the photosynthetic reaction centre (rc) isolated from the photosynthetic bacterium rhodobacter sphaeroides have been investigated in this work. for these two benzoquinone derivatives an efficient isc process which leads to the population of the lowest triplet state of the molecules upon direct excitation was observed. the presence of rc does not alter ... | 2008 | 18688505 |
| regulation of the rhodobacter sphaeroides 2.4.1 hema gene by prra and fnrl. | part of the oxygen responsiveness of rhodobacter sphaeroides 2.4.1 tetrapyrrole production involves changes in transcription of the hema gene, which codes for one of two isoenzymes catalyzing 5-aminolevulinic acid synthesis. regulation of hema transcription from its two promoters is mediated by the dna binding proteins fnrl and prra. the two prra binding sites, binding sites i and ii, which are located upstream of the more-5' hema promoter (p1), are equally important to transcription under aerob ... | 2008 | 18689483 |
| the use of chromatin immunoprecipitation to define ppsr binding activity in rhodobacter sphaeroides 2.4.1. | the expression of genes involved in photosystem development in rhodobacter sphaeroides is dependent upon three major regulatory networks: fnrl, the prrba (regba) two-component system, and the transcriptional repressor/antirepressor ppsr/appa. of the three regulators, ppsr appears to have the narrowest range of physiological effects, which are limited to effects on the structural and pigment biosynthetic activities involved in photosynthetic membrane function. although a prra(-) mutant is unable ... | 2008 | 18689484 |
| electron paramagnetic resonance study of radiation damage in photosynthetic reaction center crystals. | electron paramagnetic resonance (epr) was used to simultaneously study radiation-induced cofactor reduction and damaging radical formation in single crystals of the bacterial reaction center (rc). crystals of fe-removed/zn-replaced rc protein from rhodobacter ( r.) sphaeroides r26 were irradiated with varied radiation doses at cryogenic temperature and analyzed for radiation-induced free radical formation and alteration of light-induced photosynthetic electron transfer activity using high-field ... | 2008 | 18690706 |
| production of lipases by four anoxygenic purple non-sulphur phototrophic bacteria. | production of lipases by rhodopseudomonas palustris, rhodobacter sphaeroides, rhodocyclus gelatinosus and rhodocyclus tenuis in different synthetic media was investigated. rc. gelatinosus followed by rb. sphaeroides were good producers of lipases, while rps. palustris and rc. tenuis were poor in lipase secretion. lipase secretion by rc. gelatinosus was adaptive in nature, while other three bacterial behavior was inconsistent. no positive correlation could be observed between growth and lipase pr ... | 2005 | 18697729 |
| intracellular signalling during bacterial chemotaxis. | 2008 | 18709741 | |
| on the mechanism of quinol oxidation at the qp site in the cytochrome bc1 complex: studied using mutants lacking cytochrome bl or bh. | to elucidate the mechanism of bifurcated oxidation of quinol in the cytochrome bc1 complex, rhodobacter sphaeroides mutants, h198n and h111n, lacking heme bl and heme bh, respectively, were constructed and characterized. purified mutant complexes have the same subunit composition as that of the wild-type complex, but have only 9-11% of the electron transfer activity, which is sensitive to stigmatellin or myxothiazol. the em values for hemes bl and bh in the h111n and h198n complexes are -95 and ... | 2008 | 18713733 |
| cardiolipin increases in chromatophores isolated from rhodobacter sphaeroides after osmotic stress: structural and functional roles. | chromatophores isolated from cells of rhodobacter sphaeroides exposed to hypertonic solutions were enriched in cardiolipin (cl). because cl levels are raised by increasing the incubation time of r. sphaeroides in hypertonic solutions, it was possible to isolate chromatophores containing different cl amounts by starting from cells incubated in hypertonic solutions for different times. the functionality and stability of the photosynthetic proteins in chromatophore membranes having different cl lev ... | 2009 | 18716316 |
| a conclusive mechanism of the photoinduced reaction cascade in blue light using flavin photoreceptors. | on the basis of extensive first-principle calculations within the framework of quantum mechanics/molecular mechanics (qm/mm), a conclusive mechanism for the formation of the signaling state of blue light using flavin (bluf) domain proteins is proposed which is compatible with the experimental data presently available. time-dependent density functional, as well as advanced coupled cluster response theory was employed for the qm part in order to describe the relevant excited states. one of the key ... | 2008 | 18722438 |
| organization and evolution of the biological response to singlet oxygen stress. | the appearance of atmospheric oxygen from photosynthetic activity led to the evolution of aerobic respiration and responses to the resulting reactive oxygen species. in rhodobacter sphaeroides, a photosynthetic alpha-proteobacterium, a transcriptional response to the reactive oxygen species singlet oxygen ((1)o(2)) is controlled by the group iv sigma factor sigma(e) and the anti-sigma factor chrr. in this study, we integrated various large datasets to identify genes within the (1)o(2) stress res ... | 2008 | 18723027 |
| the organization of lh2 complexes in membranes from rhodobacter sphaeroides. | the mapping of the photosynthetic membrane of rhodobacter sphaeroides by atomic force microscopy (afm) revealed a unique organization of arrays of dimeric reaction center-light harvesting i-pufx (rc-lh1-pufx) core complexes surrounded and interconnected by light-harvesting lh2 complexes (bahatyrova, s., frese, r. n., siebert, c. a., olsen, j. d., van der werf, k. o., van grondelle, r., niederman, r. a., bullough, p. a., otto, c., and hunter, c. n. (2004) nature 430, 1058-1062). however, membrane ... | 2008 | 18723509 |
| structural analysis of a periplasmic binding protein in the tripartite atp-independent transporter family reveals a tetrameric assembly that may have a role in ligand transport. | several bacterial solute transport mechanisms involve members of the periplasmic binding protein (pbp) superfamily that bind and deliver ligand to integral membrane transport proteins in the atp-binding cassette, tripartite tricarboxylate transporter, or tripartite atp-independent (trap) families. pbps involved in atp-binding cassette transport systems have been well characterized, but only a few pbps involved in trap transport have been studied. we have measured the thermal stability, determine ... | 2008 | 18723845 |
| influence of pigment substitution on the electrochemical properties of rhodobacter sphaeroides 601 reaction centers. | with the help of pigment substitution, self-assembled monolayer film and square wave voltammetry, the influence of pigment substitution on the electrochemical properties of rhodobacter sphaeroides 601 reaction centers was investigated. results showed that the charge separation could also be driven by externally electric field, similar to the primary photochemical reaction in purple bacterial reaction center. on the surface of au electrode, a self-assembled monolayer film (the rc-pdda-dmsa film) ... | 2001 | 18726398 |
| electron and proton transfer in the ba(3) oxidase from thermus thermophilus. | the ba(3)-type cytochrome c oxidase from thermus thermophilus is phylogenetically very distant from the aa(3)-type cytochrome c oxidases. nevertheless, both types of oxidases have the same number of redox-active metal sites and the reduction of o(2) to water is catalysed at a haem a(3)-cu(b) catalytic site. the three-dimensional structure of the ba(3) oxidase reveals three possible proton-conducting pathways showing very low homology compared to those of the mitochondrial, rhodobacter sphaeroide ... | 2008 | 18752061 |
| the cytochrome c maturation components ccmf, ccmh, and ccmi form a membrane-integral multisubunit heme ligation complex. | cytochrome c maturation (ccm) is a post-translational and post-export protein modification process that involves ten (ccmabcdefghi and ccda or dsbd) components in most gram-negative bacteria. the absence of any of these components abolishes the ability of cells to form cytochrome c, leading in the case of rhodobacter capsulatus to the loss of photosynthetic proficiency and respiratory cytochrome oxidase activity. based on earlier molecular genetic studies, we inferred that r. capsulatus ccmf, cc ... | 2008 | 18753134 |
| a conserved steroid binding site in cytochrome c oxidase. | micromolar concentrations of the bile salt deoxycholate are shown to rescue the activity of an inactive mutant, e101a, in the k proton pathway of rhodobacter sphaeroides cytochrome c oxidase. a crystal structure of the wild-type enzyme reveals, as predicted, deoxycholate bound with its carboxyl group at the entrance of the k path. since cholate is a known potent inhibitor of bovine oxidase and is seen in a similar position in the bovine structure, the crystallographically defined, conserved ster ... | 2008 | 18759498 |