| spectropotentiometric and structural analysis of the periplasmic nitrate reductase from escherichia coli. | the escherichia coli napa (periplasmic nitrate reductase) contains a [4fe-4s] cluster and a mo-bis-molybdopterin guanine dinucleotide cofactor. the napa holoenzyme associates with a di-heme c-type cytochrome redox partner (napb). these proteins have been purified and studied by spectropotentiometry, and the structure of napa has been determined. in contrast to the well characterized heterodimeric napab systems ofalpha-proteobacteria, such as rhodobacter sphaeroides and paracoccus pantotrophus, t ... | 2007 | 17130127 |
| two conserved non-canonical histidines are essential for activity of the cbb (3)-type oxidase in rhodobacter capsulatus: non-canonical histidines are essential for cbb (3)-type oxidase activity in r. capsulatus. | cytochrome cbb (3) oxidase, a member of the heme-copper oxidase superfamily, catalyses the reduction of oxygen to water and generates a proton gradient. cytochrome c oxidases are characterized by a catalytic subunit (subunit i) containing two hemes and one copper ion ligated by six invariant histidine residues, which are diagnostic of heme-copper oxidases in all type of the heme-copper oxidase superfamily. alignments of the amino acid sequences of subunit i (fixn or ccon) of the cbb (3)-type oxi ... | 2007 | 17143652 |
| ph dependence of copper geometry, reduction potential, and nitrite affinity in nitrite reductase. | many properties of copper-containing nitrite reductase are ph-dependent, such as gene expression, enzyme activity, and substrate affinity. here we use x-ray diffraction to investigate the structural basis for the ph dependence of activity and nitrite affinity by examining the type 2 copper site and its immediate surroundings in nitrite reductase from rhodobacter sphaeroides 2.4.3. at active ph the geometry of the substrate-free oxidized type 2 copper site shows a near perfect tetrahedral geometr ... | 2007 | 17148448 |
| characterization of a plant-like protochlorophyllide a divinyl reductase in green sulfur bacteria. | the green sulfur bacterium chlorobium tepidum synthesizes three types of (bacterio)chlorophyll ((b)chl): bchl a(p), chl a(pd), and bchl c(f). during the synthesis of all three molecules, a c-8 vinyl substituent is reduced to an ethyl group, and in the case of bchl c(f), the c-8(2) carbon of this ethyl group is subsequently methylated once or twice by the radical s-adenosylmethionine enzyme bchq. the c. tepidum genome contains homologs of two genes, bchj (ct2014) and ct1063, that are highly homol ... | 2007 | 17148453 |
| protein-cofactor interactions in bacterial reaction centers from rhodobacter sphaeroides r-26: effect of hydrogen bonding on the electronic and geometric structure of the primary quinone. a density functional theory study. | the effect of hydrogen bonding to the primary quinone (q(a) and q(*)(-)(a)) in bacterial reaction centers was studied using density functional theory (dft) calculations. the charge neutral state q(a) was investigated by optimizing the hydrogen atom positions of model systems extracted from 15 different x-ray structures. from this analysis, mean values of the h-bond lengths and directions were derived. it was found that the n(delta)-h of his m219 forms a shorter h-bond to q(a) than the n-h of ala ... | 2006 | 17149487 |
| altering conserved lipid binding sites in cytochrome c oxidase of rhodobacter sphaeroides perturbs the interaction between subunits i and iii and promotes suicide inactivation of the enzyme. | subunit iii of the three-subunit catalytic core of cytochrome c oxidase (cco) contains no metal centers, but it does bind two lipids, within a deep cleft, in binding sites conserved from bacteria to humans. subunit iii binds to subunit i, where it prevents the spontaneous suicide inactivation of cco by decreasing the probability of side reactions at the heme-cu o2 reduction site in subunit i. subunit iii prevents suicide inactivation by (1) maintaining adequate rates of proton delivery to the he ... | 2006 | 17154527 |
| recessiveness and dominance in barley mutants deficient in mg-chelatase subunit d, an aaa protein involved in chlorophyll biosynthesis. | mg-chelatase catalyzes the insertion of mg2+ into protoporphyrin ix at the first committed step of the chlorophyll biosynthetic pathway. it consists of three subunits: i, d, and h. the i subunit belongs to the aaa protein superfamily (atpases associated with various cellular activities) that is known to form hexameric ring structures in an atp-dependant fashion. dominant mutations in the i subunit revealed that it functions in a cooperative manner. we demonstrated that the d subunit forms atp-in ... | 2006 | 17158606 |
| the solution structure of the pufx polypeptide from rhodobacter sphaeroides. | pufx organizes the photosynthetic reaction centre-light harvesting complex 1 (rc-lh1) core complex of rhodobacter sphaeroides and facilitates quinol/quinone exchange between the rc and cytochrome bc(1) complexes. the structure of pufx in organic solvent reveals two hydrophobic helices flanked by unstructured termini and connected by a helical bend. the proposed location of basic residues and tryptophans at the membrane interface orients the c-terminal helix along the membrane normal, with the gx ... | 2006 | 17161397 |
| energy and electron transfer in the photosynthetic reaction center complex of acidiphilium rubrum containing zn-bacteriochlorophyll a studied by femtosecond up-conversion spectroscopy. | a photosynthetic reaction center (rc) complex was isolated from a purple bacterium, acidiphilium rubrum. the rc contains bacteriochlorophyll a containing zn as a central metal (zn-bchl a) and bacteriopheophytin a (bphe a) but no mg-bchl a. the absorption peaks of the zn-bchl a dimer (p(zn)), the accessory zn-bchl a (b(zn)), and bphe a (h) at 4 k in the rc showed peaks at 875, 792, and 753 nm, respectively. these peaks were shorter than the corresponding peaks in rhodobacter sphaeroides rc that h ... | 2007 | 17169326 |
| genome analyses of three strains of rhodobacter sphaeroides: evidence of rapid evolution of chromosome ii. | three strains of rhodobacter sphaeroides of diverse origin have been under investigation in our laboratory for their genome complexities, including the presence of multiple chromosomes and the distribution of essential genes within their genomes. the genome of r. sphaeroides 2.4.1 has been completely sequenced and fully annotated, and now two additional strains (atcc 17019 and atcc 17025) of r. sphaeroides have been sequenced. thus, genome comparisons have become a useful approach in determining ... | 2007 | 17172323 |
| evolutionary migration of a post-translationally modified active-site residue in the proton-pumping heme-copper oxygen reductases. | in the respiratory chains of aerobic organisms, oxygen reductase members of the heme-copper superfamily couple the reduction of o2 to proton pumping, generating an electrochemical gradient. there are three distinct families of heme-copper oxygen reductases: a, b, and c types. the a- and b-type oxygen reductases have an active-site tyrosine that forms a unique cross-linked histidine-tyrosine cofactor. in the c-type oxygen reductases (also called cbb3 oxidases), an analogous active-site tyrosine h ... | 2006 | 17176062 |
| global regulation of photosynthesis and respiration by fnrl: the first two targets in the tetrapyrrole pathway. | fnr is a regulator that controls the expression of a variety of genes in response to oxygen limitation in bacteria. to assess the role of fnr in photosynthesis in rubrivivax gelatinosus, a strain carrying a null mutation in fnrl was constructed. it was unable to grow anaerobically in the light, but, intriguingly, it was able to produce photosynthetic complexes under high oxygenation conditions. the mutant lacked all c-type cytochromes normally detectable in microaerobically-grown wild type cells ... | 2007 | 17178720 |
| importance of widespread gene transfer agent genes in alpha-proteobacteria. | the gene transfer agent produced by rhodobacter capsulatus (rcgta) is a model for several virus-like elements that seem to function solely for mediating gene exchange. several genes that encode rcgta are clearly related to bacteriophage genes but the cellular regulatory mechanisms that control rcgta production indicate that rcgta is more than just a defective prophage. genome sequencing projects show that seemingly functional rcgta-like structural gene clusters are present in many other species ... | 2007 | 17184993 |
| structural determinants and modulation of substrate specificity in phenylalanine-tyrosine ammonia-lyases. | aromatic amino acid ammonia-lyases catalyze the deamination of l-his, l-phe, and l-tyr, yielding ammonia plus aryl acids bearing an alpha,beta-unsaturated propenoic acid. we report crystallographic analyses of unliganded rhodobacter sphaeroides tyrosine ammonia-lyase (rstal) and rstal bound to p-coumarate and caffeate. his 89 of rstal forms a hydrogen bond with the p-hydroxyl moieties of coumarate and caffeate. his 89 is conserved in tals but replaced in phenylalanine ammonia-lyases (pals) and h ... | 2006 | 17185228 |
| the fox operon from rhodobacter strain sw2 promotes phototrophic fe(ii) oxidation in rhodobacter capsulatus sb1003. | anoxygenic photosynthesis based on fe(ii) is thought to be one of the most ancient forms of metabolism and is hypothesized to represent a transition step in the evolution of oxygenic photosynthesis. however, little is known about the molecular basis of this process because, until recently (y. jiao and d. k. newman, j. bacteriol. 189:1765-1773, 2007), most phototrophic fe(ii)-oxidizing bacteria have been genetically intractable. in this study, we circumvented this problem by taking a heterologous ... | 2007 | 17189371 |
| x-ray absorption spectroscopic characterization of the molybdenum site of escherichia coli dimethyl sulfoxide reductase. | structural studies of dimethyl sulfoxide (dmso) reductases were hampered by modification of the active site during purification. we report an x-ray absorption spectroscopic analysis of the molybdenum active site of escherichia coli dmso reductase contained within its native membranes. the enzyme in these preparations is expected to be very close to the form found in vivo. the oxidized active site was found to have four mo-s ligands at 2.43 a, one mo=o at 1.71 a, and a longer mo-o at 1.90 a. we c ... | 2007 | 17198404 |
| proton translocation by the cytochrome bc1 complexes of phototrophic bacteria: introducing the activated q-cycle. | the cytochrome bc1 complexes are proton-translocating, dimeric membrane ubiquinol:cytochrome c oxidoreductases that serve as "hubs" in the vast majority of electron transfer chains. after each ubiquinol molecule is oxidized in the catalytic center p at the positively charged membrane side, the two liberated electrons head out, according to the mitchell's q-cycle mechanism, to different acceptors. one is taken by the [2fe-2s] iron-sulfur rieske protein to be passed further to cytochrome c1. the o ... | 2007 | 17200733 |
| multivariate curve resolution of rapid-scan ftir difference spectra of quinone photoreduction in bacterial photosynthetic membranes. | photosynthetic reaction centres and membranes are systems of particular interest and are often taken as models to investigate the molecular mechanisms of selected bioenergetic reactions. in this work, a multivariate curve resolution by alternating least squares procedure is detailed for resolution of time-resolved difference ftir spectra probing the evolution of quinone reduction in photosynthetic membranes from rhodobacter sphaeroides under photoexcitation. for this purpose, different data sets ... | 2007 | 17203250 |
| [an efficient mutational method for photosynthetic bacteria]. | the pigment and auxotrophic mutants of rhodobacter sphaeroides y6 were obtained by treatment with ethyl methanesulfonate (ems) followed by lithium chloride (lici). treatment with 0.081 m eps and subsequent treatment with 0.071 m lici resulted in 12% higher frequency of pigment mutations than application of 0.081 m ems alone; the frequency of auxotrophic mutations increased 2.5-fold when treatment with lithium chloride was applied. a blue shift 10 nm was recorded in the absorption spectrum of car ... | 2006 | 17205800 |
| the appa and ppsr proteins from rhodobacter sphaeroides can establish a redox-dependent signal chain but fail to transmit blue-light signals in other bacteria. | the appa protein of rhodobacter sphaeroides has the unique ability to sense and transmit redox and light signals. in response to decreasing oxygen tension, appa antagonizes the transcriptional regulator ppsr, which represses the expression of photosynthesis genes, including the puc operon. this mechanism, which is based on direct protein-protein interaction, is prevented by blue-light absorption of the bluf domain located in the n-terminal part of appa. in order to test whether appa and ppsr are ... | 2007 | 17209035 |
| construction of a dimethyl sulfoxide sensor based on dimethyl sulfoxide reductase immobilized on a au film electrode. | a novel dimethyl sulfoxide (dmso) sensor using dmso reductase and film electrodes was constructed. the au and ag electrodes were fabricated on slide glass by vacuum deposition and the application of a photolithographic technique. the micro-chamber (4 x 50 x 1 mm, volume 200 microl) was fabricated on a poly(dimethylsiloxane) (pdms) polymer. the pt electrode was implanted in a pdms polymer. dmso reductase was immobilized on a au film electrode with bovine serum albumin (bsa)-glutaraldehyde. this s ... | 2007 | 17213624 |
| ppsx: a novel vector for the cloning and heterologous expression of antitumor antibiotic gene clusters. | a cosmid cloning vector has been constructed that demonstrates high levels of segregational stability in escherichia coli k12. ppsx is a 14-kilobase vector derived from the incw plasmid pr388. ppsx is highly stable in e. coli in the absence of antibiotic selection, even while expressing the toxic indolocarbazole antitumor antibiotic violacein. the incorporation of the lambdacos sequence enables construction of cosmid libraries with inserts ranging from 24 to 36kb. the inclusion of a laczalpha mu ... | 2007 | 17218012 |
| atomic resolution structures of rieske iron-sulfur protein: role of hydrogen bonds in tuning the redox potential of iron-sulfur clusters. | the rieske [2fe-2s] iron-sulfur protein of cytochrome bc(1) functions as the initial electron acceptor in the rate-limiting step of the catalytic reaction. prior studies have established roles for a number of conserved residues that hydrogen bond to ligands of the [2fe-2s] cluster. we have constructed site-specific variants at two of these residues, measured their thermodynamic and functional properties, and determined atomic resolution x-ray crystal structures for the native protein at 1.2 a re ... | 2007 | 17223530 |
| following photoinduced dynamics in bacteriorhodopsin with 7-fs impulsive vibrational spectroscopy. | sub-10-fs laser pulses are used to impulsively photoexcite bacteriorhodopsin (br) suspensions and probe the evolution of the resulting vibrational wave packets. fourier analysis of the spectral modulations induced by transform-limited as well as linearly chirped excitation pulses allows the delineation of excited- and ground-state contributions to the data. on the basis of amplitude and phase variations of the modulations as a function of the dispersed probe wavelength, periodic modulations in a ... | 2007 | 17227016 |
| cytochrome c(2) exit strategy: dissociation studies and evolutionary implications. | small, water-soluble, type c cytochromes form a transient network connecting major bioenergetic membrane protein complexes in both photosynthesis and respiration. in the photosynthesis cycle of rhodobacter sphaeroides, cytochrome c2 (cyt c2) docks to the reaction center (rc), undergoes electron transfer, and exits for the cytochrome bc1 complex. translations of cyt c2 about the rc-cyt c2 docking interface and surrounding membrane reveal possible exit pathways. a pathway at a minimal elevation al ... | 2007 | 17228920 |
| biosynthesis of intracellular 5-aminolevulinic acid by a newly identified halotolerant rhodobacter sphaeroides. | of 23 strains of halotolerant (up to 12% w/v nacl) photosynthetic bacteria isolated from various sources, one isolate, sh5, accumulated intracellular 5-aminolevulinic acid (ala) at 0.45 microg/g dry cell wt (dcw) growing aerobically in the dark. the strain was identified as rhodobacter sphaeroides using 16s rdna sequencing. biosynthesis of ala was enhanced to 14 microg/g dcw using modified glutamate/glucose (50 mm) medium with the addition of 10 mm levulinic acid after 24 h cultivation. addition ... | 2007 | 17245554 |
| effect of mutations in the cytochrome b ef loop on the electron-transfer reactions of the rieske iron-sulfur protein in the cytochrome bc1 complex. | long-range movement of the rieske iron-sulfur protein (isp) between the cytochrome (cyt) b and cyt c1 redox centers plays a key role in electron transfer within the cyt bc1 complex. a series of 21 mutants in the cyt b ef loop of rhodobacter sphaeroides cyt bc1 were prepared to examine the role of this loop in controlling the capture and release of the isp from cyt b. electron transfer in the cyt bc1 complex was studied using a ruthenium dimer to rapidly photo-oxidize cyt c1 within 1 mus and init ... | 2007 | 17253777 |
| monitoring the ph dependence of ir carboxylic acid signals upon q(b)- formation in the glu-l212 --> asp/asp-l213 --> glu swap mutant reaction center from rhodobacter sphaeroides. | in the photosynthetic reaction center (rc) from the purple bacterium rhodobacter sphaeroides, proton-coupled electron-transfer reactions occur at the secondary quinone (qb) site. involved in the proton uptake steps are carboxylic acids, which have characteristic infrared vibrations in the 1770-1700 cm-1 spectral range that are sensitive to 1h/2h isotopic exchange. with respect to the native rc, a novel protonation pattern for carboxylic acids upon qb photoreduction has been identified in the glu ... | 2007 | 17260947 |
| investigation of total bacterial and ammonia-oxidizing bacterial community composition in a full-scale aerated submerged biofilm reactor for drinking water pretreatment in china. | the community composition of total bacteria and ammonia-oxidizing bacteria in a full-scale aerated submerged biofilm reactor for drinking water pretreatment was characterized by analysis of 16s rrna gene and the functional gene amoa, respectively. sampling was performed in february and in july. 16s rrna gene clone libraries revealed 13 bacterial divisions. at both sampling dates, the majority of clone sequences were related to the alpha- and betaproteobacteria. a minor proportion belonged to the ... | 2007 | 17263855 |
| do proteins at low temperature behave as glasses? a single-molecule study. | we have recorded long spectral diffusion trajectories from individual lh2 pigment-protein complexes from the purple bacterium rhodobacter sphaeroides at 1.4 k. from these data, the spectral cumulants of the absorption lines of individual, protein-embedded bchl a pigments have been evaluated. it appears that the first and second cumulants cannot be described by the predictions of the well tested standard two-level system (tls) model for spectral diffusion in glasses. the results of the present st ... | 2007 | 17266267 |
| molecular stochastic simulations of chromatophore vesicles from rhodobacter sphaeroides. | a kinetic model is presented for photosynthetic processes under varying illumination based on the recently introduced steady state model of the photosynthetic chromatophore vesicles of the purple bacterium rhodobacter sphaeroides. a stochastic simulation system is built up from independent copies of the different transmembrane proteins, each encapsulating its own set of binding sites and internal states. the proteins are then connected through pools for each of the metabolites. a number of stead ... | 2007 | 17276535 |
| identification of "haematobacter," a new genus of aerobic gram-negative rods isolated from clinical specimens, and reclassification of rhodobacter massiliensis as "haematobacter massiliensis comb. nov.". | twelve strains of gram-negative, nonfermenting rods recovered mainly from septicemic patients were studied using conventional and molecular methods. the phenotypic profiles of these strains most closely resembled psychrobacter phenylpyruvicus. they produced catalase, oxidase, urease, and h(2)s (lead acetate paper) but did not produce indole, reduce nitrate or nitrite, or hydrolyze gelatin or esculin. no acid production was observed in a king's oxidation-fermentation base containing d-glucose, d- ... | 2007 | 17287332 |
| photochemically induced dynamic nuclear polarization in the reaction center of the green sulphur bacterium chlorobium tepidum observed by 13c mas nmr. | photochemically induced dynamic nuclear polarization has been observed in reaction centres of the green sulphur bacterium chlorobium tepidum by (13)c magic-angle spinning solid-state nmr under continuous illumination with white light. an almost complete set of chemical shifts of the aromatic ring carbons of a bchl a molecule has been obtained. all light-induced (13)c nmr signals appear to be emissive, which is similar to the pattern observed in the reaction centers of plant photosystem i and pur ... | 2007 | 17292850 |
| a complete set of flagellar genes acquired by horizontal transfer coexists with the endogenous flagellar system in rhodobacter sphaeroides. | bacteria swim in liquid environments by means of a complex rotating structure known as the flagellum. approximately 40 proteins are required for the assembly and functionality of this structure. rhodobacter sphaeroides has two flagellar systems. one of these systems has been shown to be functional and is required for the synthesis of the well-characterized single subpolar flagellum, while the other was found only after the genome sequence of this bacterium was completed. in this work we found th ... | 2007 | 17293429 |
| biotin uptake in prokaryotes by solute transporters with an optional atp-binding cassette-containing module. | biomny proteins are considered to constitute tripartite biotin transporters in prokaryotes. recent comparative genomic and experimental analyses pointed to the similarity of biomn to homologous modules of prokaryotic transporters mediating uptake of metals, amino acids, and vitamins. these systems resemble atp-binding cassette-containing transporters and include typical atpases (e.g., biom). absence of extracytoplasmic solute-binding proteins among the members of this group, however, is a distin ... | 2007 | 17301237 |
| storage of an excess proton in the hydrogen-bonded network of the d-pathway of cytochrome c oxidase: identification of a protonated water cluster. | the mechanism of proton transport in the d-pathway of cytochrome c oxidase (cco) is further elucidated through examining a protonated water/hydroxyl cluster inside the channel. the second generation multi-state empirical valence bond (ms-evb2) model was employed in a molecular dynamics study based on a high-resolution x-ray structure to simulate the interaction of the excess proton with the channel environment. our results indicate that a hydrogen-bonded network consisting of about 5 water molec ... | 2007 | 17309257 |
| living without fur: the subtlety and complexity of iron-responsive gene regulation in the symbiotic bacterium rhizobium and other alpha-proteobacteria. | the alpha-proteobacteria include several important genera, including the symbiotic n(2)-fixing "rhizobia", the plant pathogen agrobacterium, the mammalian pathogens brucella, bartonella as well as many others that are of environmental or other interest--including rhodobacter, caulobacter and the hugely abundant marine genus pelagibacter. only a few species--mainly different members of the rhizobia--have been analyzed directly for their ability to use and to respond to iron. these studies, howeve ... | 2007 | 17310401 |
| brominated lipids identify lipid binding sites on the surface of the reaction center from rhodobacter sphaeroides. | this study describes the use of brominated phospholipids to distinguish between lipid and detergent binding sites on the surface of a typical alpha-helical membrane protein. reaction centers isolated from rhodobacter sphaeroides were cocrystallized with added brominated phospholipids. x-ray structural analysis of these crystals has revealed the presence of two lipid binding sites from the characteristic strong x-ray scattering from the bromine atoms. these results demonstrate the usefulness of t ... | 2007 | 17315985 |
| the role of arginine 310 in catalysis and substrate specificity in xanthine dehydrogenase from rhodobacter capsulatus. | the rapid reaction kinetics of wild-type xanthine dehydrogenase from rhodobacter capsulatus and variants at arg-310 in the active site have been characterized for a variety of purine substrates. with xanthine as substrate, k(red) (the limiting rate of enzyme reduction by substrate at high [s]) decreased approximately 20-fold in an r310k variant and 2 x 10(4)-fold in an r310m variant. although arg-310 lies on the opposite end of the substrate from the c-8 position that becomes hydroxylated, its i ... | 2007 | 17327224 |
| 5-aminolevulinate production with recombinant escherichia coli using a rare codon optimizer host strain. | the 5-aminolevulinate (ala) synthase gene (hema) containing several codons rarely used by escherichia coli was cloned from the genome of rhodobacter sphaeroides and optimized in two strains of escherichia coli: bl21(de3) and rosetta(de3), which is a rare codon optimizer strain. the effects of initial isopropyl-beta-d: -thiogalactopyranoside (iptg) concentration, induction time, and temperature on enzyme activity were studied and compared for two strains. the results indicated that the ala syntha ... | 2007 | 17333171 |
| solution structure of the rhodobacter sphaeroides pufx membrane protein: implications for the quinone exchange and protein-protein interactions. | pufx membrane protein is found in rhodobacter species of purple photosynthetic bacteria and has been known to play an essential role in ubiquinone/ubiquinol exchange between the reaction center and cytochrome bc1 complex and also contribute to the dimerization of the reaction center-light-harvesting core complex. we have determined the solution structure of the rhodobacter sphaeroides pufx using multidimensional nmr spectroscopy. the pufx, functionally expressed in escherichia coli, forms a stab ... | 2007 | 17335288 |
| the major vault protein is related to the toxic anion resistance protein (tela) family. | vaults are barrel-shaped ribonucleoprotein particles that are abundant in certain tumors and multidrug resistant cancer cells. prokaryotic relatives of the major vault protein, mvp, have not been identified. we used sequence analysis and molecular modeling to show that mvp and the toxic anion resistance protein, tela of rhodobacter sphaeroides strain 2.4.1, share a novel fold that consists of a three-stranded antiparallel beta-sheet. because of this strong structural correspondence, we examined ... | 2007 | 17337707 |
| regulation of hydrogen peroxide-dependent gene expression in rhodobacter sphaeroides: regulatory functions of oxyr. | genome-wide transcriptome profiling was used to reveal hydrogen peroxide (h(2)o(2))-dependent regulatory mechanisms in the facultatively photosynthetic bacterium rhodobacter sphaeroides. in this study we focused on the role of the oxyr protein, a known regulator of the h(2)o(2) response in bacteria. the transcriptome profiles of r. sphaeroides wild-type and oxyr mutant strains that were exposed to 1 mm h(2)o(2) for 7 min or were not exposed to h(2)o(2) were analyzed. three classes of oxyr-depend ... | 2007 | 17351037 |
| reporter proteins for in vivo fluorescence without oxygen. | fluorescent reporter proteins such as green fluorescent protein are valuable noninvasive molecular tools for in vivo real-time imaging of living specimens. however, their use is generally restricted to aerobic systems, as the formation of their chromophores strictly requires oxygen. starting with blue-light photoreceptors from bacillus subtilis and pseudomonas putida that contain light-oxygen-voltage-sensing domains, we engineered flavin mononucleotide-based fluorescent proteins that can be used ... | 2007 | 17351616 |
| interaction of product analogues with the active site of rhodobacter sphaeroides dimethyl sulfoxide reductase. | we report a structural characterization using x-ray absorption spectroscopy of rhodobacter sphaeroides dimethyl sulfoxide (dmso) reductase reduced with trimethylarsine and show that this is structurally analogous to the physiologically relevant dimethyl sulfide reduced dmso reductase. our data unambiguously indicate that these species should be regarded as formal moiv species and indicate a classical coordination complex of trimethylarsine oxide, with no special structural distortions. the simil ... | 2007 | 17361996 |
| crystal structures of an extracytoplasmic solute receptor from a trap transporter in its open and closed forms reveal a helix-swapped dimer requiring a cation for alpha-keto acid binding. | the import of solutes into the bacterial cytoplasm involves several types of membrane transporters, which may be driven by atp hydrolysis (abc transporters) or by an ion or h+ electrochemical membrane potential, as in the tripartite atp-independent periplasmic system (trap). in both the abc and trap systems, a specific periplasmic protein from the esr family (extracytoplasmic solute receptors) is often involved for the recruitment of the solute and its presentation to the membrane complex. in rh ... | 2007 | 17362499 |
| plasticity of proton pathway structure and water coordination in cytochrome c oxidase. | cytochrome c oxidase (cytco) is a redox-driven, membrane-bound proton pump. one of the proton transfer pathways of the enzyme, the d pathway, used for the transfer of both substrate and pumped protons, accommodates a network of hydrogen-bonded water molecules that span the distance between an aspartate (asp(132)), near the protein surface, and glutamate glu(286), which is an internal proton donor to the catalytic site. to investigate how changes in the environment around glu(286) affect the mech ... | 2007 | 17363369 |
| effect of dietary rhodobacter capsulatus on egg-yolk cholesterol and laying hen performance. | the present study was conducted to investigate the effects of dietary rhodobacter capsulatus on the laying hen. a total of forty 23-wk-old hy-line brown laying hens were randomly assigned into 4 treatment groups (10 laying hens/group) and fed diets supplemented with 0 (control), 0.01, 0.02, and 0.04% r. capsulatus during the 60-d feeding period. dietary supplementation of r. capsulatus (0.04%) reduced (p < 0.05) cholesterol and triglycerides concentration in serum (15 and 11%), as well as in egg ... | 2007 | 17369543 |
| structure-activity relationship among purpurinimides and bacteriopurpurinimides: trifluoromethyl substituent enhanced the photosensitizing efficacy. | at similar lipophilicity, compared to the nonfluorinated purpurinimide 11, the corresponding fluorinated analog 8 with a trifluoromethyl substituent at the lower half (position-132) of the molecule showed enhanced photosensitizing efficacy. the structural parameters established in purpurinimides (lambdamax: 700 nm) were successfully translated to the bacteriopurpurin imide system 19 (lambdamax: 792 nm) and within both series, a monotonic relationship between the lipophilicity and the in vivo pdt ... | 2007 | 17371002 |
| evidence for delocalized anticooperative flash induced proton binding as revealed by mutants at the m266his iron ligand in bacterial reaction centers. | bacterial reaction centers (rcs) convert light energy into chemical free energy via the double reduction and protonation of the secondary quinone electron acceptor, qb, to the dihydroquinone qbh2. two rc mutants (m266his --> leu and m266his --> ala) with a modified ligand of the non-heme iron have been studied by flash-induced absorbance change spectroscopy. no important changes were observed for the rate constants of the first and second electron transfers between the first quinone electron acc ... | 2007 | 17378585 |
| steady-state ftir spectra of the photoreduction of qa and qb in rhodobacter sphaeroides reaction centers provide evidence against the presence of a proposed transient electron acceptor x between the two quinones. | in the reaction center (rc) of the photosynthetic bacterium rhodobacter sphaeroides, two ubiquinone molecules, qa and qb, play a pivotal role in the conversion of light energy into chemical free energy by coupling electron transfer to proton uptake. in native rcs, the transfer of an electron from qa to qb takes place in the time range of 5-200 micros. on the basis of time-resolved ftir step-scan measurements in native rcs, a new and unconventional mechanism has been proposed in which qb- formati ... | 2007 | 17381130 |
| functionality of photosynthetic reaction centers in polyelectrolyte multilayers: toward an herbicide biosensor. | the bacterial reaction center (rc), a membrane photosynthetic protein, has been adsorbed onto a glass surface by alternating deposition with the cationic polymer poly(dimethyldiallylammonium chloride) (pdda) obtaining as an end result an ordinate polyelectrolyte multilayer (pem) where the protein retains its integrity and photoactivity over a period of several months. such a system has been characterized from the functional point of view by checking the protein photoactivity at different hydrati ... | 2007 | 17388474 |
| mechanism of quinol oxidation by ferricenium produced by light excitation in reaction centers of photosynthetic bacteria. | the kinetics and thermodynamics of cyclic electron transfer through the isolated reaction center protein of photosynthetic bacterium rhodobacter sphaeroides were determined in detergent (triton x-100) solution. the redox reactions between the reducing (ubiquinol-0 or ubiquinol-10) and oxidizing species (ferricenium, ferricytochrome, or ferricyanide) produced chemically or by light excitation of the protein were monitored by absorption changes of the reactants and by acidification of the solution ... | 2007 | 17394306 |
| the critical role of a hydrogen bond between gln63 and trp104 in the blue-light sensing bluf domain that controls appa activity. | appa is a novel blue-light receptor that controls photosynthetic gene expression in the purple bacterium rhodobacter sphaeroides. the photocycle reaction of the light-sensing domain, bluf, is unique in the sense that a few hydrogen bond rearrangements are accompanied by only slight structural changes of the bound chromophore. however, the exact features of the hydrogen bond network around the active site are still the subject of some controversy. here we present biochemical and genetic evidence ... | 2007 | 17399741 |
| in vitro assembly of a prohead-like structure of the rhodobacter capsulatus gene transfer agent. | the gene transfer agent (gta) is a phage-like particle capable of exchanging double-stranded dna fragments between cells of the photosynthetic bacterium rhodobacter capsulatus. here we show that the major capsid protein of gta, expressed in e. coli, can be assembled into prohead-like structures in the presence of calcium ions in vitro. transmission electron microscopy (tem) of uranyl acetate staining material and thin sections of glutaraldehyde-fixed material demonstrates that these associates h ... | 2007 | 17408713 |
| symmetry matters for the electronic structure of core complexes from rhodopseudomonas palustris and rhodobacter sphaeroides pufx-. | low-temperature (1.4 k), single-molecule fluorescence-excitation spectra have been recorded for individual reaction center-light-harvesting 1 complexes from rhodopseudomonas palustris and the pufx(-) strain of rhodobacter sphaeroides. more than 80% of the complexes from rb. sphaeroides show only broad absorption bands, whereas nearly all of the complexes from rps. palustris also have a narrow line at the low-energy end of their spectrum. we describe how the presence of this narrow feature indica ... | 2007 | 17416676 |
| kinetic variations determine the product pattern of phytoene desaturase from rubrivivax gelatinosus. | in bacteria and fungi, the degree of carotenoid desaturation is determined by a single enzyme, the crti-type phytoene desaturase. in different organisms, this enzyme can carry out either three, four or even five desaturation steps. the purple bacterium rubrivivax gelatinosus is the only known species in which reaction products of a 3-step and a 4-step desaturation (i.e. neurosporene and lycopene derivatives) accumulate simultaneously. the properties of this phytoene desaturation to catalyze neur ... | 2007 | 17428435 |
| formation and geminate quenching of singlet oxygen in purple bacterial reaction center. | the phosphorescence of singlet oxygen ((1)x( *)) photosensitized by the carotenoidless reaction center (rc) of rhodobacter sphaeroides r26.1 has been investigated, using h(2)o and d(2)o as the suspending media. to enhance (under neutral conditions) the triplet quantum yield of the special pair p(870) (p) by the radical pair mechanism, the quinone acceptor q(a) was removed by means of a chemical treatment. the phosphorescence signal fits the functional form p(0)[exp (-t/tau)-exp(-t/zeta)], regard ... | 2007 | 17434743 |
| [screening and identification of a photosynthetic bacterium reducing selenite to red elemental selenium]. | selenium is essential element for humans and animals but is very toxic at higher concentrations. in four inorganic states of selenate [seo4 2- ( vi)], selenite [seo3 2- (iv)], elemental selenium [se (0)] and selenide [se2- (- ii )], selenite is well known to be more soluble and higher toxic than other three forms. many microorganisms have the capacity to reduce selenite to red elemental selenium, which provide the potential to cope with the detoxification of pollution and to use the biological a ... | 2007 | 17436622 |
| ultrafast dynamics and excited state spectra of open-chain carotenoids at room and low temperatures. | many of the spectroscopic features and photophysical properties of carotenoids are explained using a three-state model in which the strong visible absorption of the molecules is associated with an s0 (1(1)ag-) --> s2 (1(1)bu+) transition, and the lowest lying singlet state, s1 (2(1)ag-), is a state into which absorption from the ground state is forbidden by symmetry. however, semiempirical and ab initio quantum calculations have suggested additional excited singlet states may lie either between ... | 2007 | 17441762 |
| the influence of hydrogen bonds on electron transfer rate in photosynthetic rcs. | hydrogen bonds formed between photosynthetic reaction centers (rcs) and their cofactors were shown to affect the efficacy of electron transfer. the mechanism of such influence is determined by sensitivity of hydrogen bonds to electron density rearrangements, which alter hydrogen bonds potential energy surface. quantum chemistry calculations were carried out on a system consisting of a primary quinone q(a), non-heme fe(2+) ion and neighboring residues(.) the primary quinone forms two hydrogen bon ... | 2007 | 17442262 |
| the inside ph determines rates of electron and proton transfer in vesicle-reconstituted cytochrome c oxidase. | cytochrome c oxidase is the terminal enzyme in the respiratory chains of mitochondria and many bacteria where it translocates protons across a membrane thereby maintaining an electrochemical proton gradient. results from earlier studies on detergent-solubilized cytochrome c oxidase have shown that individual reaction steps associated with proton pumping display ph-dependent kinetics. here, we investigated the effect of ph on the kinetics of these reaction steps with membrane-reconstituted cytoch ... | 2007 | 17466260 |
| histidine 282 in 5-aminolevulinate synthase affects substrate binding and catalysis. | 5-aminolevulinate synthase (alas), the first enzyme of the heme biosynthetic pathway in mammalian cells, is a member of the alpha-oxoamine synthase family of pyridoxal 5'-phosphate (plp)-dependent enzymes. in all structures of the enzymes of the -oxoamine synthase family, a conserved histidine hydrogen bonds with the phenolic oxygen of the plp cofactor and may be significant for substrate binding, plp positioning, and maintenance of the pka of the imine nitrogen. in alas, replacing the equivalen ... | 2007 | 17469798 |
| cloning and characterization of the ddsa gene encoding decaprenyl diphosphate synthase from rhodobacter capsulatus b10. | a decaprenyl diphosphate synthase gene (ddsa, genbank accession no. dq191802) was cloned from rhodobacter capsulatus b10 by constructing and screening the genome library. an open reading frame of 1002 bp was revealed from sequence analysis. the deduced polypeptide consisted of 333 amino acids residues with an molecular mass of about 37 kda. the ddsa protein contained the conserved amino acid sequence (ddxxd) of e-type polyprenyl diphosphate synthase and showed high similarity to others. in contr ... | 2006 | 17473883 |
| [synthesis of bacteriochlorophyll a by the purple nonsulfur bacterium rhodobacter capsulatus]. | the ability of purple nonsulfur bacteria rhodobacter capsulatus b10 to synthesize bacteriochlorophyll under phototrophic and dark conditions was studied. the modes for cultivation in the dark with oxygen limitation in a continuous culture at d = 0.1 h(-1) were selected. the yield of biomass reached 20 g/l; the bacteriochlorophyll a output of the process amounted to 16.6 mg/l h(-1). | 2007 | 17476808 |
| crystallographic location and mutational analysis of zn and cd inhibitory sites and role of lipidic carboxylates in rescuing proton path mutants in cytochrome c oxidase. | cytochrome c oxidase (cco) transfers protons from the inner surface of the enzyme to the buried o2 reduction site through two different pathways, termed k and d, and from the outer surface via an undefined route. these proton paths can be inhibited by metals such as zinc or cadmium, but the sites of inhibition have not been established. anomalous difference fourier analyses of rhodobacter sphaeroides cco crystals, with cadmium added, reveal metal binding sites that include the proposed initial p ... | 2007 | 17477548 |
| biochemistry. photosynthesis from the protein's perspective. | | 2007 | 17478711 |
| protein dynamics control the kinetics of initial electron transfer in photosynthesis. | the initial electron transfer dynamics during photosynthesis have been studied in rhodobacter sphaeroides reaction centers from wild type and 14 mutants in which the driving force and the kinetics of charge separation vary over a broad range. surprisingly, the protein relaxation kinetics, as measured by tryptophan absorbance changes, are invariant in these mutants. by applying a reaction-diffusion model, we can fit the complex electron transfer kinetics of each mutant quantitatively, varying onl ... | 2007 | 17478721 |
| orientation-resolving pulsed electron dipolar high-field epr spectroscopy on disordered solids: i. structure of spin-correlated radical pairs in bacterial photosynthetic reaction centers. | distance and relative orientation of functional groups within protein domains and their changes during chemical reactions determine the efficiency of biological processes. in this work on disordered solid-state electron-transfer proteins, it is demonstrated that the combination of pulsed high-field epr spectroscopy at the w band (95 ghz, 3.4 t) with its extensions to peldor (pulsed electron-electron double resonance) and ridme (relaxation-induced dipolar modulation enhancement) offers a powerful ... | 2007 | 17497913 |
| the unusually strong hydrogen bond between the carbonyl of q(a) and his m219 in the rhodobacter sphaeroides reaction center is not essential for efficient electron transfer from q(a)(-) to q(b). | in native reaction centers (rcs) from photosynthetic purple bacteria the primary quinone (qa) and the secondary quinone (qb) are interconnected via a specific his-fe-his bridge. in rhodobacter sphaeroides rcs the c4=o carbonyl of qa forms a very strong hydrogen bond with the protonated npi of his m219, and the ntau of this residue is in turn coordinated to the non-heme iron atom. the second carbonyl of qa is engaged in a much weaker hydrogen bond with the backbone n-h of ala m260. in previous wo ... | 2007 | 17497939 |
| a haem cofactor is required for redox and light signalling by the appa protein of rhodobacter sphaeroides. | the appa protein of rhodobacter sphaeroides is unique in its ability to sense and transmit redox signals as well as light signals. by functioning as antagonist to the ppsr transcriptional repressor, it regulates the expression of photosynthesis genes in response to these environmental stimuli. here we show binding of the cofactor haem to a domain in the c-terminal part of appa and redox activity of bound haem. this is supported by the findings that: (i) the c-terminal domain of appa (appadeltan) ... | 2007 | 17501930 |
| light-dependent assimilation of trans-cinnamate by rhodobacter sphaeroides ou5. | we present a novel light-dependent metabolism of an aromatic compound (trans-cinnamate) that is assimilatory rather than dissimilatory. light-dependent assimilation of trans-cinnamate was observed by both growing and resting cells of rhodobacter sphaeroides ou5. trans-cinnamate assimilation could be correlated with simultaneous formation of both phenylalanine and tyrosine at near-stoichiometric ratios. trans-cinnamate assimilation was promoted by carbon source and electron donors, such as glucos ... | 2007 | 17503150 |
| postgenomic adventures with rhodobacter sphaeroides. | this review describes some of the recent highlights taken from the studies of rhodobacter sphaeroides 2.4.1. the review is not intended to be comprehensive, but to reflect the bias of the authors as to how the availability of a sequenced and annotated genome, a gene-chip, and proteomic profile as well as comparative genomic analyses can direct the progress of future research in this system. | 2007 | 17506668 |
| bacterial symbionts in the hepatopancreas of isopods: diversity and environmental transmission. | the midgut glands (hepatopancreas) of terrestrial isopods contain bacterial symbionts. we analysed the phylogenetic diversity of hepatopancreatic bacteria in isopod species from various suborders colonizing marine, semiterrestrial, terrestrial and freshwater habitats. hepatopancreatic bacteria were absent in the marine isopod idotea balthica (valvifera). the symbiotic bacteria present in the midgut glands of the freshwater isopod asellus aquaticus (asellota) were closely related to members of th ... | 2007 | 17506824 |
| prophage-like gene transfer agents-novel mechanisms of gene exchange for methanococcus, desulfovibrio, brachyspira, and rhodobacter species. | gene transfer agents (gtas) are novel mechanisms for bacterial gene transfer. they resemble small, tailed bacteriophages in ultrastructure and act like generalized transducing prophages. in contrast to functional prophages, gtas package random fragments of bacterial genomes and incomplete copies of their own genomes. the packaged dna content is characteristic of the gta and ranges in size from 4.4 to 13.6kb. gtas have been reported in species of brachyspira, methanococcus, desulfovibrio, and rho ... | 2007 | 17513139 |
| solvation effect of bacteriochlorophyll excitons in light-harvesting complex lh2. | we have characterized the influence of the protein environment on the spectral properties of the bacteriochlorophyll (bchl) molecules of the peripheral light-harvesting (or lh2) complex from rhodobacter sphaeroides. the spectral density functions of the pigments responsible for the 800 and 850 nm electronic transitions were determined from the temperature dependence of the bchl absorption spectra in different environments (detergent micelles and native membranes). the spectral density function i ... | 2007 | 17513366 |
| plasmon waveguide resonance spectroscopic evidence for differential binding of oxidized and reduced rhodobacter capsulatus cytochrome c2 to the cytochrome bc1 complex mediated by the conformation of the rieske iron-sulfur protein. | the dissociation constants for the binding of rhodobacter capsulatus cytochrome c2 and its k93p mutant to the cytochrome bc1 complex embedded in a phospholipid bilayer were measured by plasmon waveguide resonance spectroscopy in the presence and absence of the inhibitor stigmatellin. the reduced form of cytochrome c2 strongly binds to reduced cytochrome bc1 (kd = 0.02 microm) but binds much more weakly to the oxidized form (kd = 3.1 microm). in contrast, oxidized cytochrome c2 binds to oxidized ... | 2007 | 17516628 |
| the structure of l-tyrosine 2,3-aminomutase from the c-1027 enediyne antitumor antibiotic biosynthetic pathway. | the sgcc4 l-tyrosine 2,3-aminomutase (sgtam) catalyzes the formation of (s)-beta-tyrosine in the biosynthetic pathway of the enediyne antitumor antibiotic c-1027. sgtam is homologous to the histidine ammonia lyase family of enzymes whose activity is dependent on the methylideneimidazole-5-one (mio) cofactor. unlike the lyase enzymes, sgtam catalyzes additional chemical transformations resulting in an overall stereospecific 1,2-amino shift in the substrate l-tyrosine to generate (s)-beta-tyrosine ... | 2007 | 17516659 |
| the phra gene of rhodobacter sphaeroides encodes a photolyase and is regulated by singlet oxygen and peroxide in a sigma(e)-dependent manner. | the genome of the facultatively photosynthetic bacterium rhodobacter sphaeroides encodes three proteins of the photolyase/cryptochrome family. this paper shows that phra (rsp2143) encodes a functional photolyase, which is an enzyme that repairs uv radiation-induced dna damage in a blue light dependent manner. expression of phra is upregulated in response to light, with no photoreceptor or the photosynthetic electron transport being involved. the results reveal that singlet oxygen and hydrogen pe ... | 2007 | 17526841 |
| measuring electronic coupling in the reaction center of purple photosynthetic bacteria by two-color, three-pulse photon echo peak shift spectroscopy. | one- and two-color, three-pulse photon echo peak shift spectroscopy (1c and 2c3peps) was used to estimate the electronic coupling between the accessory bacteriochlorophyll (b) and the bacteriopheophytin (h) in the reaction center of the purple photosynthetic bacterium rhodobacter sphaeroides as approximately 170 +/- 30 cm-1. this is the first direct experimental determination of this parameter; it is within the range of values found in previously published calculations. the 1c3peps signal of the ... | 2007 | 17530796 |
| protein synthesis patterns reveal a complex regulatory response to singlet oxygen in rhodobacter. | singlet oxygen (1o2) is a stress factor and signal in the facultative phototrophic bacterium rhodobacter sphaeroides. in vivo protein labeling with l-[35s]-methionine and analysis by two-dimensional gel electrophoresis revealed that the synthesis of 61 proteins was changed in response to 1o2. after 1o2 treatment, protein synthesis patterns were distinct from those after h2o2 treatment but similar to those after high light exposure. this indicates regulatory mechanisms selective for different rea ... | 2007 | 17536848 |
| a beta-galactosidase-based bacterial two-hybrid system to assess protein-protein interactions in the correct cellular environment. | the vast majority of proteins functions in complex with one or more of the same or other proteins, indicating that protein-protein interactions play crucial roles in biology. here, we present a beta-galactosidase reconstitution-based bacterial two-hybrid system in which two proteins of interest are fused to two non-functional but complementing beta-galactosidase truncations (delta alpha and delta omega). the level of complemented beta-galactosidase activity, driven by the protein-protein recogni ... | 2007 | 17539672 |
| on the role of aromatic side chains in the photoactivation of bluf domains. | bluf (blue-light sensing using fad) domain proteins are a novel group of blue-light sensing receptors found in many microorganisms. the role of the aromatic side chains y21 and w104, which are in close vicinity to the fad cofactor in the appa bluf domain from rhodobacter sphaeroides, is investigated through the introduction of several amino acid substitutions at these positions. nmr spectroscopy indicated that in the w104f mutant, the local structure of the fad binding pocket was not significant ... | 2007 | 17542622 |
| role of b800 in carotenoid-bacteriochlorophyll energy and electron transfer in lh2 complexes from the purple bacterium rhodobacter sphaeroides. | the role of the b800 in energy and electron transfer in lh2 complexes has been studied using femtosecond time-resolved transient absorption spectroscopy. the b800 site was perturbed by application of lithium dodecyl sulfate (lds), and comparison of treated and untreated lh2 complexes from rhodobacter sphaeroides incorporating carotenoids neurosporene, spheroidene, and spheroidenone was used to explore the role of b800 in carotenoid to bacteriochlorophyll-a (bchla) energy transfer and carotenoid ... | 2007 | 17547450 |
| synthesis of c5-dicarboxylic acids from c2-units involving crotonyl-coa carboxylase/reductase: the ethylmalonyl-coa pathway. | fifty years ago, kornberg and krebs established the glyoxylate cycle as the pathway for the synthesis of cell constituents from c2-units. however, since then, many bacteria have been described that do not contain isocitrate lyase, the key enzyme of this pathway. here, a pathway termed the ethylmalonyl-coa pathway operating in such organisms is described. isotopically labeled acetate and bicarbonate were transformed to ethylmalonyl-coa by cell extracts of acetate-grown, isocitrate lyase-negative ... | 2007 | 17548827 |
| biophysics. long live electronic coherence! | | 2007 | 17556574 |
| coherence dynamics in photosynthesis: protein protection of excitonic coherence. | the role of quantum coherence in promoting the efficiency of the initial stages of photosynthesis is an open and intriguing question. we performed a two-color photon echo experiment on a bacterial reaction center that enabled direct visualization of the coherence dynamics in the reaction center. the data revealed long-lasting coherence between two electronic states that are formed by mixing of the bacteriopheophytin and accessory bacteriochlorophyll excited states. this coherence can only be exp ... | 2007 | 17556580 |
| dominant role of the cbb3 oxidase in regulation of photosynthesis gene expression through the prrba system in rhodobacter sphaeroides 2.4.1. | in this study, the h303a mutant form of the cbb(3) oxidase (h303a oxidase), which has the h303a mutation in its catalytic subunit (ccon), was purified from rhodobacter sphaeroides. the h303a oxidase showed the same catalytic activity as did the wild-type form of the oxidase (wt oxidase). the heme contents of the mutant and wt forms of the cbb(3) oxidase were also comparable. however, the puf and puc operons, which are under the control of the prrba two-component system, were shown to be derepres ... | 2007 | 17557830 |
| stable transduction of bovine tlr4 and bovine md-2 into lps-nonresponsive cells and soluble cd14 promote the ability to respond to lps. | the interaction of bovine cells with lipopolysaccharide (lps) was explored using human embryo kidney (hek) 293 cell line stably transduced with bovine toll-like receptor-4 (tlr4) alone or in combination with bovine md-2. these lines and mock-transduced hek293 cells were tested by flow cytometry for lps-fluorescein isothiocyanate (lps-fitc) binding, nuclear factor kappa b (nfkappab) activation, interleukin-8 (il-8) production and interferon-beta mrna expression/interferon (ifn) type i production. ... | 2007 | 17559944 |
| exposing the complex iii qo semiquinone radical. | complex iii qo site semiquinone has been assigned pivotal roles in productive energy-conversion and destructive superoxide generation. after a 30-year search, a genetic heme bh knockout arrests this transient semiquinone epr radical, revealing the natural engineering balance pitting energy-conserving, short-circuit minimizing, split electron transfer and catalytic speed against damaging oxygen reduction. | 2007 | 17560537 |
| pressure-induced spectral changes for the special-pair radical cation of the bacterial photosynthetic reaction center. | the effect of pressure up to 6 kbars on the near to mid infrared absorption spectrum (7500-14,300 cm(-1) or 1333-700 nm) of the oxidized reaction center of rhodobacter sphaeroides is measured and interpreted using density-functional b3lyp, indo, and pm5 calculations. two weak electronic transition origins at approximately 8010 and approximately 10,210 cm(-1) are unambiguously identified. the first transition is assigned to a qy tripdoublet band that involves, in the localized description of the ... | 2007 | 17567219 |
| ph modulates the quinone position in the photosynthetic reaction center from rhodobacter sphaeroides in the neutral and charge separated states. | the structure of the photosynthetic reaction-center from rhodobacter sphaeroides has been determined at four different ph values (6.5, 8.0, 9.0, 10.0) in the neutral and in charge separated states. at ph 8.0, in the neutral state, we obtain a resolution of 1.87 a, which is the best ever reported for the bacterial reaction center protein. our crystallographic data confirm the existence of two different binding positions of the secondary quinone (qb). we observe a new orientation of qb in its dist ... | 2007 | 17570397 |
| x-ray absorption studies of zn2+ binding sites in bacterial, avian, and bovine cytochrome bc1 complexes. | binding of zn2+ has been shown previously to inhibit the ubiquinol cytochrome c oxidoreductase (cyt bc1 complex). x-ray diffraction data in zn-treated crystals of the avian cyt bc1 complex identified two binding sites located close to the catalytic qo site of the enzyme. one of them (zn01) might interfere with the egress of protons from the qo site to the aqueous phase. using zn k-edge x-ray absorption fine-structure spectroscopy, we report here on the local structure of zn2+ bound stoichiometri ... | 2007 | 17573435 |
| [relations between the chemotype and the cell electrophoretic properties in rhodobacter capsulatus strains]. | the cells of two rhodobacter capsulatus strains, b10 and pg, and the lps of their cell walls were studied by electrophysical and biochemical methods. strain b10 was found to belong to the r chemotype, and strain pg, to the rs chemotype. a relation was revealed between the chemotype of the photosynthesizing bacteria rhodobacter capsulatus and the electrophoretic properties of their cells. | 2007 | 17583217 |
| membrane sequestration of pii proteins and nitrogenase regulation in the photosynthetic bacterium rhodobacter capsulatus. | both rhodobacter capsulatus pii homologs glnb and glnk were found to be necessary for the proper regulation of nitrogenase activity and modification in response to an ammonium shock. as previously reported for several other bacteria, ammonium addition triggered the amtb-dependent association of glnk with the r. capsulatus membrane. native polyacrylamide gel electrophoresis analysis indicates that the modification/demodification of one pii homolog is aberrant in the absence of the other. in a gln ... | 2007 | 17586647 |
| stabilization of charge separation and cardiolipin confinement in antenna-reaction center complexes purified from rhodobacter sphaeroides. | the reaction center-light harvesting complex 1 (rc-lh1) purified from the photosynthetic bacterium rhodobacter sphaeroides has been studied with respect to the kinetics of charge recombination and to the phospholipid and ubiquinone (uq) complements tightly associated with it. in the antenna-rc complexes, at 6.5<ph<9.0, p(+)q(b)(-) recombines with a ph independent average rate constant <k> more than three times smaller than that measured in lh1-deprived rcs. at increasing ph values, for which <k> ... | 2007 | 17588528 |
| endor spectroscopy reveals light induced movement of the h-bond from ser-l223 upon forming the semiquinone (q(b)(-)(*)) in reaction centers from rhodobacter sphaeroides. | proton endor spectroscopy was used to monitor local conformational changes in bacterial reaction centers (rc) associated with the electron-transfer reaction dqb --> d+*qb-* using mutant rcs capable of photoreducing qb at cryogenic temperatures. the charge separated state d+*qb-* was studied in mutant rcs formed by either (i) illuminating at low temperature (77 k) a sample frozen in the dark (ground state protein conformation) or (ii) illuminating at room temperature prior to and during freezing ... | 2007 | 17590017 |
| s-adenosyl-l-methionine:magnesium-protoporphyrin ix o-methyltransferase from rhodobacter capsulatus: mechanistic insights and stimulation with phospholipids. | the enzyme bchm (s-adenosyl-l-methionine:magnesium-protoporphyrin ix o-methyltransferase) from rhodobacter capsulatus catalyses an intermediate reaction in the bacteriochlorophyll biosynthetic pathway. overexpression of his(6)-tagged protein in escherichia coli resulted in the majority of polypeptide existing as inclusion bodies. purification from inclusion bodies was performed using metal-affinity chromatography after an elaborate wash step involving surfactant polysorbate-20. initial enzymatic ... | 2007 | 17594291 |
| identification, characterization and functional expression of a tyrosine ammonia-lyase and its mutants from the photosynthetic bacterium rhodobacter sphaeroides. | a tyrosine ammonia-lyase (tal) enzyme from the photosynthetic bacterium rhodobacter sphaeroides (rstal) was identified, cloned and functionally expressed in escherichia coli, where conversion of tyrosine to p-hydroxycinnamic acid (phca) was demonstrated. the rstal enzyme is implicated in production of phca, which serves as the cofactor for synthesis of the photoactive yellow protein (pyp) in photosynthetic bacteria. the wild type rstal enzyme, while accepting both tyrosine and phenylalanine as s ... | 2007 | 17602252 |
| identification of tetrapyrrole compounds excreted by rhodobacter sphaeroides and sources of the methyl hydrogens of bacteriochlorophyll a biosynthesized by r. sphaeroides, based on 13c-nmr spectral analysis of coproporphyrin iii tetramethyl ester. | red-fluorescent tetrapyrrole compounds excreted by rhodobacter sphaeroides into the culture broth were concluded to be coproporphyrinogen (copro'gen) iii and uroporphyrinogen (uro'gen) i, based on the (13)c-nmr spectral identification of coproporphyrin (copro) iii tetramethyl ester and uroproporphyrin (uro) i octamethyl ester. the sources of the methyl hydrogens of bacteriochlorophyll a were established by analysis of the (13)c-nmr spectra of (2)h,(13)c-copro iii tetramethyl ester chemically der ... | 2007 | 17603203 |