Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| pathways for phosphatidylcholine biosynthesis in bacteria. | phosphatidylcholine (pc) is the major membrane-forming phospholipid in eukaryotes with important structural and signalling functions. although many prokaryotes lack pc, it can be found in significant amounts in membranes of rather diverse bacteria. two pathways for pc biosynthesis are known in bacteria, the methylation pathway and the phosphatidylcholine synthase (pcs) pathway. in the methylation pathway, phosphatidylethanolamine is methylated three times to yield pc, in reactions catalysed by o ... | 2003 | 14663079 |
| synthetic analogues of the histidine-chlorophyll complex: a nmr study to mimic structural features of the photosynthetic reaction center and the light-harvesting complex. | mg(ii)-porphyrin-ligand and (bacterio)chlorophyl-ligand coordination interactions have been studied by solution and solid-state mas nmr spectroscopy. (1)h, (13)c and (15)n coordination shifts due to ring currents, electronic perturbations and structural effects are resolved for imidazole (im) and 1-methylimidazole (1-meim) coordinated axially to mg(ii)-oep and (b)chl a. as a consequence of a single axial coordination of im or 1-meim to the mg(ii) ion, 0.9-5.2 ppm (1)h, 0.2-5.5 ppm (13)c and 2.1- ... | 2004 | 14663650 |
| protein film voltammetry of rhodobacter capsulatus xanthine dehydrogenase. | xanthine dehydrogenase (xdh) from the bacterium rhodobacter capsulatus catalyzes the hydroxylation of xanthine to uric acid with nad(+) as the electron acceptor. r. capsulatus xdh forms an (alphabeta)(2) heterotetramer and is highly homologous to homodimeric eukaryotic xdhs. the crystal structures of bovine xdh and r. capsulatus xdh showed that the two proteins have highly similar folds; however, r.capsulatus xdh is at least 5 times more active than bovine xdh and, unlike mammalian xdh, does not ... | 2003 | 14664579 |
| the mitochondrial and prokaryotic proton-translocating nadh:ubiquinone oxidoreductases: similarities and dissimilarities of the quinone-junction sites. | the catalytic properties of the rotenone-sensitive nadh:ubiquinone reductase (complex i) in bovine heart submitochondrial particles and in inside-out vesicles derived from paracoccus denitrificans and rhodobacter capsulatus were compared. the prokaryotic enzymes catalyze the nadh oxidase and nadh:quinone reductase reactions with similar kinetic parameters as those for the mammalian complex i, except for lower apparent affinities for the substrates--nucleotides. unidirectional competitive inhibit ... | 2003 | 14670598 |
| redox characteristics of the tungsten dmso reductase of rhodobacter capsulatus. | the dimethylsulfoxide reductase (dmsor) from rhodobacter capsulatus is known to retain its three-dimensional structure and enzymatic activity upon substitution of molybdenum, the metal that occurs naturally at the active site, by tungsten. the redox properties of tungsten-substituted dmsor (w-dmsor) have been investigated by a dye-mediated reductive titration with the concentration of the w(v) state monitored by epr spectroscopy. at ph 7.0, e(m)(w(vi)/w(v)) is -194 mv and e(m)(w(v)/w(iv)) is -13 ... | 2003 | 14675782 |
| redox-coupled proton translocation in biological systems: proton shuttling in cytochrome c oxidase. | in the respiratory chain free energy is conserved by linking the chemical reduction of dioxygen to the electrogenic translocation of protons across a membrane. cytochrome c oxidase (cco) is one of the sites where this linkage occurs. although intensively studied, the molecular mechanism of proton pumping by this enzyme remains unknown. here, we present data from an investigation of a mutant cco from rhodobacter sphaeroides [asn-139 --> asp, nd(i-139)] in which proton pumping is completely uncoup ... | 2003 | 14676323 |
| decolorization of azo dyes by rhodobacter sphaeroides. | rhodobacter sphaeroides as1.1737 decolorized more than 90% of several azo dyes (200 mg dyes l(-1)) in 24 h. the optimal culture conditions were: anaerobic illumination (1990 1x), peptone as carbon source, temperature 35-40 degrees c and ph 7-8. intracellular crude enzyme from this strain had azoreductase activity, optimized temperature as 45-50 degrees c, and decolorization kinetics which were consistent with a ping-pong mechanism. | 2003 | 14677704 |
| null mutation of hvra compensates for loss of an essential rela/spot-like gene in rhodobacter capsulatus. | we report that a single rela/spot-like gene exists on the rhodobacter capsulatus chromosome, and its mutational loss is lethal. this gene could be mutated only under a mutational background of a null mutation in the nucleoid protein hvra. this result suggests that there may be a direct link between hvra-regulated promoters and the ppgpp-related stringent response. | 2004 | 14679243 |
| site-directed mutagenesis of nnrr: a transcriptional regulator of nitrite and nitric oxide reductase in rhodobacter sphaeroides. | nnrr, a transcriptional activator and member of the crp/fnr family of regulators, is responsible for controlling the expression of a number of denitrification genes in rhodobacter sphaeroides 2.4.3. the apparent effector for nnrr is nitric oxide, and in its presence nnrr activates expression of the nirk gene and the nor operon, encoding nitrite reductase and nitric oxide reductase, respectively. whether nitric oxide directly interacts with nnrr to activate transcription is unknown. other denitri ... | 2003 | 14680695 |
| role of toll-like receptor 4 in induction of cell-mediated immunity and resistance to brucella abortus infection in mice. | initial host defense to bacterial infection is executed by innate immunity, and therefore the main goal of this study was to examine the contribution of toll-like receptors (tlrs) during brucella abortus infection. cho reporter cell lines transfected with cd14 and tlrs showed that b. abortus triggers both tlr2 and tlr4. in contrast, lipopolysaccharide (lps) and lipid a derived from brucella rough (r) and smooth (s) strains activate cho cells only through tlr4. consistently, macrophages from c3h/ ... | 2004 | 14688095 |
| role of the c-terminal extrinsic region of the alpha polypeptide of the light-harvesting 2 complex of rhodobacter sphaeroides: a domain swap study. | the lh1 and lh2 complexes of rhodobacter sphaeroides form ring structures of 16 and 9 protomers, respectively, comprising alpha and beta polypeptides, bacteriochlorophylls (bchl), and carotenoids. using the lh2 complex as a starting point, two chimeric lh complexes were constructed incorporating the alphac-terminal domain of either the rb. sphaeroides lh1 complex or the rhodospirillum molischianum lh2 complex. the lh1 domain swap produced a new red-shifted component that comprised approximately ... | 2003 | 14690421 |
| on the analysis of membrane protein circular dichroism spectra. | analysis of circular dichroism spectra of proteins provides information about protein secondary structure. analytical methods developed for such an analysis use structures and spectra of a set of reference proteins. the reference protein sets currently in use include soluble proteins with a wide range of secondary structures, and perform quite well in analyzing cd spectra of soluble proteins. the utility of soluble protein reference sets in analyzing membrane protein cd spectra, however, has bee ... | 2004 | 14691226 |
| structural, dynamic, and energetic aspects of long-range electron transfer in photosynthetic reaction centers. | intramolecular electron transfer within proteins plays an essential role in biological energy transduction. electron donor and acceptor cofactors are bound in the protein matrix at specific locations, and protein-cofactor interactions as well as protein conformational changes can markedly influence the electron transfer rates. to assess these effects, we have investigated charge recombination from the primary quinone acceptor to the special pair bacteriochlorophyll dimer in wild-type reaction ce ... | 2004 | 14691247 |
| intracellular autoregulation of the mycobacterium tuberculosis prra response regulator. | two-component systems are major regulatory systems for bacterial adaptation to environmental changes. during the infectious cycle of mycobacterium tuberculosis, adaptation to an intracellular environment is critical for multiplication and survival of the micro-organism within the host. the m. tuberculosis prra gene, encoding the regulator of the two-component system prra-prrb, has been shown to be induced upon macrophage phagocytosis and to be transiently required for the early stages of macroph ... | 2004 | 14702417 |
| purification of rhodobacter sphaeroides rna polymerase and its sigma factors. | this article summarized methods to obtain rna polymerase and sigma factors that can be used to analyze the in vitro control of gene expression by the facultative phototroph r. sphaeroides. while not a topic of this article, these purified components also allow one to analyze r. sphaeroides promoters that use activators to stimulate transcription. we expect that these approaches will be increasingly useful as investigators continue to dissect the number of unusual signal transduction pathways tha ... | 2003 | 14712633 |
| protein-template-driven formation of polynuclear iron species. | ferritins are iron-storage proteins capable of holding up to 4500 fe(3+) ions within a single water-soluble protein shell made from 24 polypeptide chains. the glu128arg/glu135arg mutants of escherichia coli and rhodobacter capsulatus bacterioferritins are unable to associate into 24-meric structures, with dimers of polypeptide chains being their stable forms. the aerobic addition to these of up to 8-10 or 14-20 fe(2+) ions per dimer, respectively, results in the oxidation of the added fe(2+) to ... | 2004 | 14719947 |
| rhodobacter capsulatus nifa1 promoter: high-gc -10 regions in high-gc bacteria and the basis for their transcription. | it was previously shown that the rhodobacter capsulatus ntrc enhancer-binding protein activates the r. capsulatus housekeeping rna polymerase but not the escherichia coli rna polymerase at the nifa1 promoter. we have tested the hypothesis that this activity is due to the high g+c content of the -10 sequence. a comparative analysis of r. capsulatus and other alpha-proteobacterial promoters with known transcription start sites suggests that the g+c content of the -10 region is higher than that for ... | 2004 | 14729700 |
| circe is not involved in heat-dependent transcription of groesl but in stabilization of the mrna 5'-end in rhodobacter capsulatus. | the circe element, an inverted dna repeat, is known to be involved in the temperature-dependent regulation of genes for heat shock proteins in a variety of organisms. the circe element was identified as the target for the hrca protein, which represses transcription of heat shock genes under normal growth temperature. our data reveal that the circe element is not involved in the temperature-dependent transcription of the groesl genes in rhodobacter capsulatus. apparently, r.capsulatus does not ha ... | 2004 | 14729923 |
| hydrogen bonds involved in binding the qi-site semiquinone in the bc1 complex, identified through deuterium exchange using pulsed epr. | exchangeable protons in the immediate neighborhood of the semiquinone (sq) at the qi-site of the bc1 complex (ubihydroquinone:cytochrome c oxidoreductase (ec 1.10.2.2)) from rhodobacter sphaeroides have been characterized using electron spin echo envelope modulation (eseem) and hyperfine sublevel correlation spectroscopy (hyscore) and visualized by substitution of h2o by 2h2o. three exchangeable protons interact with the electron spin of the sq. they possess different isotropic and anisotropic h ... | 2004 | 14736869 |
| determination of the topological shape of integral membrane protein light-harvesting complex lh2 from photosynthetic bacteria in the detergent solution by small-angle x-ray scattering. | the topological shape of the integral membrane protein light-harvesting complex lh2 from photosynthetic bacteria rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle x-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. the results indicate that the lh2 protein in aqueous solution is encapsulated by a monolayered detergent shell ... | 2004 | 14747343 |
| modeling charge transfer in the photosynthetic reaction center. | in this work, we present a model to elucidate the unidirectionality of the primary charge-separation process in the bacterial reaction centers. we have used a model of three sites/molecules with electron transfer beginning at site 1 with an option to proceed to site 2 or site 3. we used a stochastic model with arbitrary correlation functions. we get the quantum yields of electron escape via the sites 2,3 in two limiting cases that correspond to a spectral density of underdamped and overdamped br ... | 2003 | 14754228 |
| hydrophobic pockets at the membrane interface: an original mechanism for membrane protein interactions. | the effect of partial digestion by trypsin and gluc protease on the association of the membrane polypeptides of lh1 from rhodospirillum (rsp.) rubrum was studied. trypsin and gluc protease treatments of lh1 result in the cleavage of the first three amino acids from the alpha polypeptide and of the first 18 amino acids from the beta polypeptide, respectively, without any noticeable reorganization of their secondary structure, as measured by attenuated total reflectance fourier transform ir spectr ... | 2004 | 14756563 |
| stability and solubility of integral membrane proteins from photosynthetic bacteria solubilized in different detergents. | as a first step toward the establishment of practical guidelines for the search for crystallization conditions, stability and solubility were examined for integral membrane proteins from photosynthetic bacteria in the presence of different detergents. the results obtained from their stability provided practical information on the proper choice of detergent type in the preparation process and the subsequent crystallization experiment. in addition, the determination of a solubility diagram provide ... | 2004 | 14757223 |
| in rhodobacter sphaeroides respiratory nitrate reductase, the kinetics of substrate binding favors intramolecular electron transfer. | the respiratory nitrate reductase (napab) from rb. sphaeroides is a periplasmic molybdenum-containing enzyme which belongs to the dmso reductase family. we report a study of napab by protein film voltammetry (pfv), and we present the first quantitative interpretation of the complex redox-state dependence of activity that has also been observed with other related enzymes. the model we use to fit the data assumes that binding of substrate partly limits turnover and is faster and weaker when the mo ... | 2004 | 14759176 |
| differences in two pseudomonas aeruginosa cbb3 cytochrome oxidases. | bacterial cytochrome cbb3 oxidases are members of the haeme-copper oxidase superfamily that are important for energy conservation by a variety of proteobacteria under oxygen-limiting conditions. the opportunistic pathogen pseudomonas aeruginosa is unusual in possessing two operons that each potentially encode a cbb3 oxidase (cbb3-1 or cbb3-2). our results demonstrate that, unlike typical enzymes of this class, the cbb3-1 oxidase has an important metabolic function at high oxygen tensions. in hig ... | 2004 | 14763990 |
| molecular architecture of photosynthetic membranes in rhodobacter sphaeroides: the role of pufx. | the effects of the pufx polypeptide on membrane architecture were investigated by comparing the composition and structures of photosynthetic membranes from pufx+ and pufx- strains of rhodobacter sphaeroides. we show that this single polypeptide profoundly affects membrane morphology, leading to highly elongated cells containing extended tubular membranes. purified tubular membranes contain helical arrays composed solely of dimeric rc-lh1-pufx (rc, reaction centre; lh, light harvesting) complexes ... | 2004 | 14765115 |
| proton and electron transfer in the acceptor quinone complex of photosynthetic reaction centers from rhodobacter sphaeroides. | for twenty years the photosynthetic reaction center (rc) has been the premier testing ground for theoretical understanding of electron transfer in aperiodic systems, with special, but not unique, reference to long distance biological electron transport. in addition to the known structure, many of the attributes that make rcs so well suited to studying electron transfer function equally well for any charge movement, including protons. these include the presence of intrinsic reporter groups (elect ... | 2004 | 14766369 |
| modular broad-host-range expression vectors for single-protein and protein complex purification. | a set of modular broad-host-range expression vectors with various affinity tags (six-his-tag, flag-tag, strep-tag ii, t7-tag) was created. the complete nucleotide sequences of the vectors are known, and these small vectors can be mobilized by conjugation. they are useful in the purification of proteins and protein complexes from gram-negative bacterial species. the plasmids were easily customized for thiocapsa roseopersicina, rhodobacter capsulatus, and methylococcus capsulatus by inserting an a ... | 2004 | 14766546 |
| the extra fragment of the iron-sulfur protein (residues 96-107) of rhodobacter sphaeroides cytochrome bc1 complex is required for protein stability. | sequence alignment of the rieske iron-sulfur protein (isp) of cytochrome bc(1) complex from various sources reveals that bacterial isps contain an extra fragment. to study the role of this fragment in bacterial cytochrome bc(1) complex, rhodobacter sphaeroides mutants expressing his-tagged cytochrome bc(1) complexes with deletion or single- or multiple-alanine substitution at various positions of this fragment (residues 96-107) were generated and characterized. the ispdelta(96-107), isp(96-107)a ... | 2004 | 14769025 |
| endor of spin-correlated radical pairs in photosynthesis at high magnetic field: a tool for mapping electron transfer pathways. | a new phenomenon has been detected in the time-resolved electron-nuclear double resonance (endor) spectra of the spin-correlated radical pairs in photosynthetic reaction center proteins. the observed effects result from both increased resolution and orientational selectivity provided by high magnetic field epr and are manifest as specific, derivative-type lines in the endor spectrum. importantly, the positions and amplitudes of these lines contain information on the interaction of a particular n ... | 2004 | 14871090 |
| reversible redox energy coupling in electron transfer chains. | reversibility is a common theme in respiratory and photosynthetic systems that couple electron transfer with a transmembrane proton gradient driving atp production. this includes the intensely studied cytochrome bc1, which catalyses electron transfer between quinone and cytochrome c. to understand how efficient reversible energy coupling works, here we have progressively inactivated individual cofactors comprising cytochrome bc1. we have resolved millisecond reversibility in all electron-tunnell ... | 2004 | 14961113 |
| rhodobacter capsulatus photoactive yellow protein: genetic context, spectral and kinetics characterization, and mutagenesis. | a gene for photoactive yellow protein (pyp) was previously cloned from rhodobacter capsulatus (rc), and we have now found it to be associated with genes for gas vesicle formation in the recently completed genome sequence. however, the pyp had not been characterized as a protein. we have now produced the recombinant rcpyp in escherichia coli as a glutathione-s-transferase (gst) fusion protein, along with the biosynthetic enzymes, resulting in the formation of holo-rcpyp following cleavage of the ... | 2004 | 14967022 |
| multichannel flash spectroscopy of the reaction centers of wild-type and mutant rhodobacter sphaeroides: bacteriochlorophyllb-mediated interaction between the carotenoid triplet and the special pair. | multichannel flash spectroscopy (with microsecond time resolution) has been applied to carotenoid (car)-containing and car-less reaction centers (rc) of rhodobacter sphaeroides with a view to investigate the interaction between the car and its neighboring pigments at room temperature. under neutral redox potential conditions, where the primary quinone acceptor (qa) is oxidized, the light-induced spectral changes in the 350-1000 nm region are attributed to the photochemical oxidation of the speci ... | 2004 | 14974718 |
| the raised midpoint potential of the [2fe2s] cluster of cytochrome bc1 is mediated by both the qo site occupants and the head domain position of the fe-s protein subunit. | we have previously reported that mutant strains of rhodobacter capsulatus that have alanine insertions (+nala mutants) in the hinge region of the iron sulfur (fe-s) containing subunit of the bc(1) complex have increased redox midpoint potentials (e(m)) for their [2fe2s] clusters. the alteration of the e(m) in these strains, which contain mutations far from the metal binding site, implied that the local environment of the metal center is indirectly altered by a change in the interaction of this s ... | 2004 | 14979718 |
| the electron conduction of photosynthetic protein complexes embedded in a membrane. | the conductivity of two photosynthetic protein-pigment complexes, a light harvesting 2 complex and a reaction center, was measured with an atomic force microscope capable of performing electrical measurements. current-voltage measurements were performed on complexes embedded in their natural environment. embedding the complexes in lipid bilayers made it possible to discuss the different conduction behaviors of the two complexes in light of their atomic structure. | 2004 | 14988007 |
| the effect of internal voids in membrane proteins: high-pressure study of two photochemical reaction centres from rhodobacter sphaeroides. | the effect of application of high pressure on the carotenoid-containing bacterial reaction centre from rhodobacter sphaeroides strain 2.4.1 was studied, and compared to recent experiments performed on its carotenoid-less counterpart, isolated from strain r26.1. our results indicate that the cavity created by the absence of carotenoid contributes to localised differences in protein compressibility when using the intrinsic chromophores as molecular probes. differential stability of the electronic ... | 2004 | 14988026 |
| temperature-dependent processing of the cspa mrna in rhodobacter capsulatus. | the expression of genes for cold-shock proteins is proposed to be regulated primarily at the post-transcriptional level by increase of mrna stability after transition to low temperatures. destabilization of the escherichia coli cold-induced cspa transcript at 37 degrees c as well as stabilization upon cold shock is known to depend on the unusually long (159 nt) 5'-untranslated region. determination of the cspa mrna 5'-end from rhodobacter capsulatus revealed a shorter distance between the start ... | 2004 | 14993318 |
| redox property and regulation of ppsr, a transcriptional repressor of photosystem gene expression in rhodobacter sphaeroides. | ppsr from rhodobacter sphaeroides is involved in the repression of photosystem gene expression. the ppsr protein was heterologously overexpressed and purified to homogeneity. gel mobility shift assay showed that the purified ppsr has dna-binding activity. sds-page analysis showed that some portions of ppsr were oxidized, indicating that intramolecular or intermolecular disulphide bonds were formed between the two cysteines in each subunit. when the disulphide bond of ppsr was reduced by dtt, the ... | 2004 | 14993319 |
| effect of lipopolysaccharides of various structures on the adhesion of and generation of active oxygen species by human neutrophils. | 2003 | 14994530 | |
| manganese(ii) zero-field interaction in cambialistic and manganese superoxide dismutases and its relationship to the structure of the metal binding site. | the mn(ii) high-magnetic-field electron paramagnetic resonance (hfepr) spectra of five different superoxide dismutases (sods) were measured at 190 and 285 ghz. the native e. coli manganese sod was found to be distinct from the other sods by virtue of its large zero-field e-value. the two wild-type cambialistic proteins from porphyromonas gingivalis and rhodobacter capsulatus were also distinct. however, the gly155thr mutant of the p. gingivalis sod changed the mn(ii) spectrum so that it closely ... | 2004 | 14995187 |
| high-diversity biofilm for the oxidation of sulfide-containing effluents. | in the present work, we describe for the first time the utilization of a complex microbial biofilm for the treatment of sulfide-containing effluents. a non-aerated packed-column reactor was inoculated with anoxic lake sediment and exposed to light. a biofilm developed in the column and showed a stable oxidation performance for several weeks. microbial species composition was analyzed by microscopy, pigment analysis and a bacterial 16s rrna gene clone library. colorless sulfur bacteria, green alg ... | 2004 | 14997354 |
| oxygen intervention in the regulation of gene expression: the photosynthetic bacterial paradigm. | the means by which oxygen intervenes in gene expression has been examined in considerable detail in the metabolically versatile bacterium rhodobacter sphaeroides. three regulatory systems are now known in this organism, which are used singly and in combination to modulate genes in response to changing oxygen availability. the outcome of these regulatory events is that the molecular machinery is present for the cell to obtain energy by means that are best suited to prevailing conditions, while at ... | 2004 | 14999403 |
| visualization of the phylogenetic content of five genomes using dekapentagonal maps. | the methods presented here summarize phylogenetic relationships of genomes in visually appealing and informative figures. dekapentagonal maps depict phylogenetic information for orthologous genes present in five genomes, and provide a pre-screen for putatively horizontally transferred genes. if the majority of individual gene phylogenies are unresolved, bipartition histograms provide a means of uncovering and analyzing the plurality consensus. analyses of genomes representing five photosynthetic ... | 2004 | 15003123 |
| iron(ii) carboxylate complexes based on a tetraimidazole ligand as models of the photosynthetic non-heme ferrous sites: synthesis, crystal structure, and mössbauer and magnetic studies. | the preparations, x-ray structures, and detailed physical characterization are presented for new complexes involving an iron(ii) center, a tetraimidazole ligand (tim), and different carboxylates. [fe(tim)(c(6)h(5)ch(2)co(2))](clo(4)) (1) crystallizes in the pbca space group with a = 10.8947(13), b = 20.343(2), and c = 22.833(3) a, z = 8, and v = 5060.6(11) a(3). [fe(tim)(ch(3)co(2))](clo(4)) (2) crystallizes in the ia space group with a = 17.117(2), b = 10.3358(12), and c = 25.658(3) a, beta = 9 ... | 2004 | 15018534 |
| sulfitobacter delicatus sp. nov. and sulfitobacter dubius sp. nov., respectively from a starfish (stellaster equestris) and sea grass (zostera marina). | on the basis of data from phenotypic and genotypic characterization and analysis of 16s rrna gene sequences, two novel species belonging to the genus sulfitobacter are described. strains kmm 3584(t), a pale-yellowish, non-motile strain isolated from a starfish (stellaster equestris), and kmm 3554(t), which is motile by means of a single subpolar flagellum and was isolated from sea grass (zostera marina), are marine, gram-negative, aerobic, rod-shaped organisms. both strains have the ability to d ... | 2004 | 15023963 |
| dna sequence duplication in rhodobacter sphaeroides 2.4.1: evidence of an ancient partnership between chromosomes i and ii. | the complex genome of rhodobacter sphaeroides 2.4.1, composed of chromosomes i (ci) and ii (cii), has been sequenced and assembled. we present data demonstrating that the r. sphaeroides genome possesses an extensive amount of exact dna sequence duplication, 111 kb or approximately 2.7% of the total chromosomal dna. the chromosomal dna sequence duplications were aligned to each other by using mummer. frequency and size distribution analyses of the exact dna duplications revealed that the interchr ... | 2004 | 15028685 |
| [features of transformation of phosphates in rhodobacter sphaeroides chromatophores]. | we have found the atp production in the rhodobacter sphaeroides chromatophores illuminated by single short light flash, that is under conditions when the proton gradient formed as a result of electron transport after the second flash, is absent. the atp synthesis was accompanied by the h2o2 formation. simultaneous formation of h2o2 is indicative of the oxidative activation of phosphate during the atp synthesis, as in the model systems with isolated chlorophyll. these data provide a theoretical b ... | 2004 | 15029701 |
| absence of large-scale displacement of quinone qb in bacterial photosynthetic reaction centers. | photosynthesis transforms light into chemical energy by coupling electron transfer to proton uptake at the quinone q(b). the possibility of initiating this process with a brief pulse of light and the known x-ray structure makes the photosynthetic bacterial reaction center a paradigm for studying coupled electron-proton transfer in biology. it has been established that electron transfer from the primary quinone q(a) to q(b) is gated by a protein conformational change. on the basis of a dramatic d ... | 2004 | 15035603 |
| em single particle analysis of the atp-dependent bchi complex of magnesium chelatase: an aaa+ hexamer. | bchi, belonging to the aaa+ -protein family, forms the enzyme magnesium chelatase together with bchd and bchh. this enzyme catalyses the insertion of mg2+ into protoporphyrin ix upon atp hydrolysis. previous studies have indicated that bchi forms atp-dependent complexes and it is a member of the aaa+ -protein family (atpases associated with various cellular activities) and it was suggested based on structural homology that the bchi formed hexameric complexes. aaa+ -proteins are mg2+ -dependent a ... | 2004 | 15037253 |
| potential energy landscape for conformationally gated secondary ubiquinone binding in the photosynthetic reaction center of rhodobacter sphaeroides. | 2004 | 15038289 | |
| in vitro self-assembly of the light harvesting pigment-protein lh2 revealed by ultrafast spectroscopy and electron microscopy. | controlled ensemble formation of protein-surfactant systems provides a fundamental concept for the realization of nanoscale devices with self-organizing capability. in this context, spectroscopic monitoring of pigment-containing proteins yields detailed structural information. here we have studied the association behavior of the bacterial light-harvesting protein lh2 from rhodobacter spheroides in an n,n-dimethyldodecylamine-n-oxide/water environment. time-resolved studies of the excitation anni ... | 2004 | 15041674 |
| estimation of binding constants for the substrate and activator of rhodobacter sphaeroides adenosine 5'-diphosphate-glucose pyrophosphorylase using affinity capillary electrophoresis. | binding constants were determined for the activator fructose-6-phosphate (f6p) and substrate adenosine 5'-triphosphate (atp) (in the presence and absence of f6p) to the recombinant wild-type (wt) rhodobacter sphaeroides adenosine 5'-diphosphate-(adp)-glucose pyrophosphorylase (adpglc ppase) using affinity capillary electrophoresis (ace). in these binding studies, the capillary is initially injected with a plug of sample containing adpglc ppase and noninteracting standards. the sample is then sub ... | 2004 | 15051543 |
| a unified description of the electrochemical, charge distribution, and spectroscopic properties of the special-pair radical cation in bacterial photosynthesis. | we apply our four-state 70-vibration vibronic-coupling model for the properties of the photosynthetic special-pair radical cation to: (1) interpret the observed correlations between the midpoint potential and the distribution of spin density between the two bacteriochlorophylls for 30 mutants of rhodobacter sphaeroides, (2) interpret the observed average intervalence hole-transfer absorption energies as a function of spin density for six mutants, and (3) simulate the recently obtained intervalen ... | 2004 | 15053603 |
| effect of oxygen on temporary stabilization of photoreduced quinone acceptors in rhodobacter sphaeroides reaction centers. | the effect of molecular oxygen on the photochemical activity of the rhodobacter sphaeroides reaction centers frozen to 160 k under actinic illumination was investigated by the esr method. about 90% of initially photochemically active bacteriochlorophyll (p) were fixed at 160 k for a long time in aerobic samples in an inactive form. in anaerobic samples, not more than 65% were fixed in an inactive form under the same conditions. in aerobic preparations, a small portion of photochemically active b ... | 2004 | 15061694 |
| x-ray structure determination of three mutants of the bacterial photosynthetic reaction centers from rb. sphaeroides; altered proton transfer pathways. | in the photosynthetic reaction center (rc) from rhodobacter sphaeroides, the reduction of a bound quinone molecule q(b) is coupled with proton uptake. when asp-l213 is replaced by asn, proton transfer is inhibited. proton transfer was restored by two second-site revertant mutations, arg-m233-->cys and arg-h177-->his. kinetic effects of cd(2+) on proton transfer showed that the entry point in revertant rcs to be the same as in the native rc. the structures of the parental and two revertant rcs we ... | 2004 | 15062092 |
| the critical role of tryptophan-116 in the catalytic cycle of dimethylsulfoxide reductase from rhodobacter capsulatus. | in dimethylsulfoxide reductase of rhodobacter capsulatus tryptophan-116 forms a hydrogen bond with a single oxo ligand bound to the molybdenum ion. mutation of this residue to phenylalanine affected the uv/visible spectrum of the purified mo(vi) form of dimethylsulfoxide reductase resulting in the loss of the characteristic transition at 720 nm. results of steady-state kinetic analysis and electrochemical studies suggest that tryptophan 116 plays a critical role in stabilizing the hexacoordinate ... | 2004 | 15063748 |
| glycine 176 affects catalytic properties and stability of the synechococcus sp. strain pcc6301 ribulose-1,5-bisphosphate carboxylase/oxygenase. | a previously described system for biological selection of randomly mutagenized ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) employing the phototrophic bacterium rhodobacter capsulatus was used to select a catalytically altered form of a cyanobacterial (synechococcus sp. strain pcc6301) enzyme. this mutant rubisco, in which conserved glycine 176 was replaced with an aspartate residue, was not able to support co(2)-dependent growth of the host strain. site-directed mutant proteins wer ... | 2004 | 15067012 |
| enzymes and genes of taurine and isethionate dissimilation in paracoccus denitrificans. | growth of the alpha-proteobacterium paracoccus denitrificans nknis with taurine or isethionate as sole source of carbon involves sulfoacetaldehyde acetyltransferase (xsc), which is presumably encoded by an xsc gene in subgroup 3, none of whose gene products has been characterized. the genome of the alpha-proteobacterium rhodobacter sphaeroides 2.4.1 was interpreted to contain a nine-gene cluster encoding the inducible dissimilation of taurine, and this deduced pathway included a regulator, a tri ... | 2004 | 15073291 |
| characterization of the ph-dependent resonance raman transitions of archaeal and bacterial rieske [2fe-2s] proteins. | the ph-dependent resonance raman (rr) spectral changes of the cytochrome bc1-associated, high-potential rieske proteins have frequently been invoked to explain the redox-linked ionization behavior. we report herein rr spectral data of archaeal and bacterial rieske proteins that directly demonstrate the ph-dependent changes near and above pka,ox2, but not around pka,ox1, of the visible circular dichroism (cd) transitions. the rr spectral changes are attributed to modification of the immediate [2f ... | 2004 | 15080677 |
| formation of a semiquinone at the qb site by a- or b-branch electron transfer in the reaction center from rhodobacter sphaeroides. | in rhodobacter sphaeroides reaction centers containing the mutation ala m260 to trp (am260w), transmembrane electron transfer along the a-branch of cofactors is prevented by the loss of the qa ubiquinone. reaction centers that contain this am260w mutation are proposed to photoaccumulate the p(+)qb- radical pair following transmembrane electron transfer along the b-branch of cofactors (wakeham, m. c., goodwin, m. g., mckibbin, c., and jones, m. r. (2003) photoaccumulation of the p(+)qb- radical p ... | 2004 | 15096044 |
| novel cyanide inhibition at cytochrome c1 of rhodobacter capsulatus cytochrome bc1. | oxidized cytochrome c(1) in photosynthetic bacterium rhodobacter capsulatus cytochrome bc(1) reversibly binds cyanide with surprisingly high, micromolar affinity. the binding dramatically lowers the redox midpoint potential of heme c(1) and inhibits steady-state turnover activity of the enzyme. as cytochrome c(1), an auxiliary redox center of the high-potential chain of cytochrome bc(1), does not interact directly with the catalytic quinone/quinol binding sites q(o) and q(i), cyanide introduces ... | 2004 | 15100019 |
| proton-coupled electron transfer at the qo-site of the bc1 complex controls the rate of ubihydroquinone oxidation. | the rate-limiting reaction of the bc(1) complex from rhodobacter sphaeroides is transfer of the first electron from ubihydroquinone (quinol, qh(2)) to the [2fe-2s] cluster of the rieske iron-sulfur protein (isp) at the q(o)-site. formation of the es-complex requires participation of two substrates (s), qh(2) and isp(ox). from the variation of rate with [s], the binding constants for both substrates involved in formation of the complex can be estimated. the configuration of the es-complex likely ... | 2004 | 15100020 |
| modulation of the free energy of the primary quinone acceptor (qa) in reaction centers from rhodobacter sphaeroides: contributions from the protein and protein-lipid(cardiolipin) interactions. | the redox midpoint potential (e(m)) of q(a), the primary quinone of bacterial reaction centers, is substantially modulated by the protein environment. quite subtle mutations in the q(a) binding site, e.g., at residues m218, m252 and m265, cause significant increases in the equilibrium constant for electron transfer to q(b), which indicate relative lowering of the e(m) of q(a). however, reports of functional linkage between the q(a) and q(b) sites make it difficult to partition such effects betwe ... | 2004 | 15100021 |
| surface-mediated proton-transfer reactions in membrane-bound proteins. | as outlined by peter mitchell in the chemiosmotic theory, an intermediate in energy conversion in biological systems is a proton electrochemical potential difference ("proton gradient") across a membrane, generated by membrane-bound protein complexes. these protein complexes accommodate proton-transfer pathways through which protons are conducted. in this review, we focus specifically on the role of the protein-membrane surface and the surface-bulk water interface in the dynamics of proton deliv ... | 2004 | 15100022 |
| the use of stable isotopes and spectroscopy to investigate the energy transducing function of cytochrome c oxidase. | we have used epr and ftir spectroscopy in combination with (17)o and (15)n stable isotopes to investigate the mechanism of cytochrome c oxidase (cco). a high-spin state of heme a(3) was found in high yield by epr, achieved upon turning over the enzyme until it was anaerobic, and shown to be a mixture of heme with a coordinated oxygen-based ligand and five-coordinate heme. allowing the enzyme to consume (17)o(2) for a few milliseconds before freezing, we also showed that the product h(2)(17)o exi ... | 2004 | 15100039 |
| the influence of subunit iii of cytochrome c oxidase on the d pathway, the proton exit pathway and mechanism-based inactivation in subunit i. | although subunit iii of cytochrome c oxidase is part of the catalytic core of the enzyme, its function has remained enigmatic. comparison of the wild-type oxidase and forms lacking subunit iii shows that the presence of subunit iii maintains rapid proton uptake into the d pathway at the ph of the bacterial cytoplasm or mitochondrial matrix, apparently by contributing to the protein environment of d132, the initial proton acceptor of the d pathway. subunit iii also appears to contribute to the co ... | 2004 | 15100048 |
| mass spectrometric detection of protein, lipid and heme components of cytochrome c oxidase from r. sphaeroides and the stabilization of non-covalent complexes from the enzyme. | the cytochrome c oxidase enzyme from the rhodobacter sphaeroides bacteria exists as a complex of four peptide subunits, two hemes, and a variety of lipids and metal ions held together by non-covalent forces. while the native enzyme functions as an associated unit, this complex usually dissociates during maldi- tof analysis. through the use of matrix additives such as sucrose, the complete complex and partial complexes can be stabilized in the maldi-tof experiment. the dissociation of the complex ... | 2004 | 15103107 |
| electron transfer kinetics in photosynthetic reaction centers embedded in polyvinyl alcohol films. | the coupling between electron transfer and protein dynamics has been studied at room temperature in isolated reaction centers (rcs) from the photosynthetic bacterium rhodobacter sphaeroides by incorporating the protein in polyvinyl alcohol (pva) films of different water/rc ratios. the kinetic analysis of charge recombination shows that dehydration of rc-containing pva films causes reversible, inhomogeneous inhibition of electron transfer from the reduced primary quinone acceptor (q(a)(-)) to the ... | 2004 | 15110251 |
| ph-sensitive fluorescent dye as probe for proton uptake in photosynthetic reaction centers. | isolated and purified reaction centers (rc) from rhodobacter sphaeroides r-26.1 were solubilised in detergent with excess quinone and external electron donors and illuminated in the presence of pyranine. the ph change accompanying the reaction center photocycle was monitored by recording the variation of the pyranine fluorescence intensity. using q(b)-depleted reaction centers or blocking the photocycle with terbutryne strongly reduced the ph change. the usefulness and limits of this technique i ... | 2004 | 15110262 |
| noninvasive auto-photoreduction used as a tool for studying structural changes in heme-copper oxidases by ftir spectroscopy. | we demonstrate an efficient fourier transform infrared (ftir) spectroscopic method, termed "auto-photoreduction," that uses anaerobic photo-induced internal electron transfer to monitor reaction-initiated changes of heme-copper oxidases. it can be applied without the use of either expensive electrochemical equipment, or caged compounds, which cause significant background signals. at high irradiation power, carbon monoxide is released from high-spin heme a of cytochrome c oxidase and heme o from ... | 2004 | 15111436 |
| substitution of isoleucine m206 residue by histidine in the rhodobacter sphaeroides reaction centers causes changes in the structure of the special bacteriochlorophyll pair molecule. | 2004 | 15116562 | |
| light-induced structural changes in a putative blue-light receptor with a novel fad binding fold sensor of blue-light using fad (bluf); slr1694 of synechocystis sp. pcc6803. | the sensor of blue-light using fad (bluf) domain is the flavin-binding fold categorized to a new class of blue-light sensing domain found in appa from rhodobacter sphaeroides and pac from euglena gracilis, but little is known concerning the mechanism of blue-light perception. an open reading frame slr1694 in a cyanobacterium synechocystis sp. pcc6803 encodes a protein possessing the bluf domain. here, a full-length slr1694 protein retaining fad was expressed and purified and found to be present ... | 2004 | 15122896 |
| [effect of photosynthetic bacteria and compost on degradation of petroleum products in soil]. | addition of diesel fuel and waste engine oil to soil was found to cause biostimulation of hydrocarbon-oxidizing microorganisms. corynebacteria constitute a large group of hydrocarbon-oxidizing microorganisms. addition of a liquid culture of photosynthetic bacteria to soil not only facilitates degradation of petroleum products, but also stimulates growth of hydrocarbon-oxidizing microorganisms. combined addition of photosynthetic bacteria and compost to soil polluted with petroleum products cause ... | 2004 | 15125200 |
| regulation of photosynthesis genes in rubrivivax gelatinosus: transcription factor ppsr is involved in both negative and positive control. | induction of biosynthesis of the photosystem in anoxygenic photosynthetic bacteria occurs when the oxygen concentration drops. control of this induction takes place primarily at the transcriptional level, with photosynthesis genes expressed preferentially under anaerobic conditions. here, we report analysis of the transcriptional control of two photosynthesis promoters, pucba and crti, by the ppsr factor in rubrivivax gelatinosus. this was accomplished by analyzing the photosystem production in ... | 2004 | 15126475 |
| involvement of the c-terminal extension of the alpha polypeptide and of the pucc protein in lh2 complex biosynthesis in rubrivivax gelatinosus. | the facultative phototrophic nonsulfur bacterium rubrivivax gelatinosus exhibits several differences from other species of purple bacteria in the organization of its photosynthetic genes. in particular, the puc operon contains only the pucb and puca genes encoding the beta and alpha polypeptides of the light-harvesting 2 (lh2) complex. downstream of the pucba operon is the pucc gene in the opposite transcriptional orientation. the transcription of pucba and pucc has been studied. no pucc transcr ... | 2004 | 15126476 |
| [mechanism of charge separation and their stabilization in bacterial reaction centers]. | the nuclear wavepacket formed by 20-fs excitation on the p* potential energy surface in native and mutant (ym210w and ym210l) reaction centers of rhodobacter (rb.) sphaeroides and chloroflexus (c.) aurantiacus rcs was found to be reversibly transferred to the p+ba- surface at 120, 380, and 640-fs delays (monitored by measurements of ba- absorption at 1020-1028 nm). the reaction centers of ym210w(l) mutant show the most simple pattern of fs oscillations with a period of 230 fs in stimulated emiss ... | 2004 | 15129622 |
| secrets of carotenoid binding. | 2004 | 15130464 | |
| protein regulation of carotenoid binding; gatekeeper and locking amino acid residues in reaction centers of rhodobacter sphaeroides. | x-ray diffraction was used to determine high-resolution structures of the reaction center (rc) complex from the carotenoidless mutant, rb. sphaeroides r-26.1, without or reconstituted with carotenoids. the results are compared with the structure of the rc from a semiaerobically grown rb. sphaeroides strain 2.4.1. the investigation reveals the structure of the carotenoid in the different protein preparations, the nature of its binding site, and a plausible mechanism by which the carotenoid is inc ... | 2004 | 15130469 |
| the role of cysteine 160 in thiamine diphosphate binding of the calvin-benson-bassham cycle transketolase of rhodobacter sphaeroides. | the transketolase gene (cbbt) that encodes the calvin-benson-bassham pathway transketolase (cbbt) of rhodobacter sphaeroides was overexpressed in escherichia coli and the recombinant protein purified to homogeneity. like other transketolases, r. sphaeroides cbbt was found to be inactivated in the presence of oxygen. at its optimal ph of 7.8, cbbt displays a specific activity of 37 u/mg, a kr5p of 949 microm, a kxu5p of 11 microm, and a kthdp of 1.8 microm. cysteine 160, equivalent to cys159 of t ... | 2004 | 15130781 |
| systematic 16s rrna gene sequencing of atypical clinical isolates identified 27 new bacterial species associated with humans. | clinical microorganisms isolated during a 5-year study in our hospital that could not be identified by conventional criteria were studied by 16s rrna gene sequence analysis. each isolate yielded a > or =1,400-bp sequence containing <5 ambiguities which was compared with the genbank 16s rrna gene library; 1,404 such isolates were tested, and 120 were considered unique (27 isolates) or rare (< or =10 cases reported in the literature) human pathogens. eleven new species, "actinobaculum massiliae," ... | 2004 | 15131188 |
| role of the conserved arginine pair in proton and electron transfer in cytochrome c oxidase. | a hydrogen-bonded network is observed above the hemes in all of the high-resolution crystal structures of cytochrome oxidases. it includes water and a pair of arginines, r481 and r482 (rhodobacter sphaeroides numbering), that interact directly with heme a and the heme a(3) propionates. the hydrogen-bonded network provides potential pathways for proton release. the arginines, and the backbone peptide bond between them, have also been proposed to form part of a facilitated electron transfer route ... | 2004 | 15134449 |
| characterization of cu- and zn-containing superoxide dismutase of rhodobacter sphaeroides. | rhodobacter sphaeroides has a cuprozinc-containing superoxide dismutase (cuznsod) in its periplasm in addition to the cytoplasmic sod that appears to contain iron (fesod). the fesod is constitutively expressed under the growth conditions examined, whereas the cuznsod is detected only when the light-harvesting complexes are found. the cuznsod expression is regulated post-transcriptionally, and the enzyme appears to protect the photoheterotrophic cells from periplasmic superoxide that may be gener ... | 2004 | 15135531 |
| investigation of the thermal stability of porin from paracoccus denitrificans by site-directed mutagenesis and fourier transform infrared spectroscopy. | the folding of membrane proteins was addressed using outer membrane protein porin from the soil bacterium paracoccus denitrificans (p. den.). ir spectroscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) analysis were used to probe the effect of mutagenesis on the thermal stability of the protein. secondary structure analysis by amide i ir spectroscopy showed that the wild-type protein was predominantly composed of beta-sheet, which supports the x-ray crystal structure ... | 2004 | 15137100 |
| delayed fluorescence from the photosynthetic reaction center measured by electronic gating of the photomultiplier. | the decay of the delayed fluorescence (920 nm) of reaction centers from the photosynthetic bacterium rhodobacter sphaeroides r26 in the p(+)q(a)(-) charge-separated state (p and q(a) are the primary donor and quinone, respectively) has been monitored in a wide (100 ns to 100 ms) time range. the photomultiplier (hamamatsu r3310-03) was protected from the intense prompt fluorescence by application of gating potential pulses (-280 v) to the first, third, and fifth dynodes during the laser pulse. th ... | 2004 | 15137102 |
| anomalous acceleration of the photocycle in photosynthetic reaction centers inhibited on the acceptor side. | the rate of the photocycle (quinone reduction cycle) was measured under continuous light excitation in an isolated reaction center protein of the photosynthetic bacterium rhodobacter sphaeroides. the rate is determined by the slowest step of the photocycle, which could be the photochemistry (charge separation), the quinone/quinol and cytochrome c(2+)/c(3+) exchanges, or proton delivery to the secondary quinone. the photocycle was driven by high light intensity of a laser diode (5 w/cm(2) at 808 ... | 2004 | 15137103 |
| orientated binding of photosynthetic reaction centers on gold using ni-nta self-assembled monolayers. | coupling of photosynthetic reaction centers (rcs) with inorganic surfaces is attractive for the identification of the mechanisms of interprotein electron transfer (et) and for possible applications in construction of photo- and chemosensors. here we show that rcs from rhodobacter sphaeroides can be immobilized on gold surfaces with the rc primary donor looking towards the substrate by using a genetically engineered poly-histidine tag (his(7)) at the c-terminal end of the m-subunit and a ni-nta t ... | 2004 | 15142599 |
| catellibacterium nectariphilum gen. nov., sp. nov., which requires a diffusible compound from a strain related to the genus sphingomonas for vigorous growth. | a bacterial strain, designated ast4(t), was isolated from activated sludge. the bacterium did not show significant growth on nutrient broth, but growth was clearly stimulated by addition of supernatant from other bacterial cultures. culture filtrate of a strain related to the genus sphingomonas in particular increased the cell yield and growth rate of strain ast4(t). phylogenetic analysis based on the 16s rrna gene sequences showed that strain ast4(t) is located within the 'rhodobacter group' in ... | 2004 | 15143049 |
| protein splicing and auto-cleavage of bacterial intein-like domains lacking a c'-flanking nucleophilic residue. | bacterial intein-like (bil) domains are newly identified homologs of intein protein-splicing domains. the two known types of bil domains together with inteins and hedgehog (hog) auto-processing domains form the hog/intein (hint) superfamily. bil domains are distinct from inteins and hogs in sequence, phylogenetic distribution, and host protein type, but little is known about their biochemical activity. here we experimentally study the auto-processing activity of four bil domains. an a-type bil d ... | 2004 | 15150275 |
| atpase activity of magnesium chelatase subunit i is required to maintain subunit d in vivo. | during biosynthesis of chlorophyll, mg(2+) is inserted into protoporphyrin ix by magnesium chelatase. this enzyme consists of three different subunits of approximately 40, 70 and 140 kda. seven barley mutants deficient in the 40 kda magnesium chelatase subunit were analysed and it was found that this subunit is essential for the maintenance of the 70 kda subunit, but not the 140 kda subunit. the 40 kda subunit has been shown to belong to the family of proteins called "atpases associated with var ... | 2004 | 15153108 |
| interactions stabilizing the structure of the core light-harvesting complex (lh1) of photosynthetic bacteria and its subunit (b820). | reconstitution experiments with a chemically synthesized core light-harvesting (lh1) beta-polypeptide analogue having 3-methylhistidine instead of histidine in the position that normally donates the coordinating ligand to bacteriochlorophyll (bchl) have provided the experimental data needed to assign to b820 one of the two possible alphabeta.2bchl pairs that are observed in the crystal structure of lh2 from phaeospirillum (formerly rhodospirillum) molischianum, the one with rings iii and v of bc ... | 2004 | 15170338 |
| photoactive yellow protein, bacteriophytochrome, and sensory rhodopsin in purple phototrophic bacteria. | the purple photosynthetic bacteria contain a large variety of sensory and regulatory proteins, and those responding to light are among the most interesting. these currently include bacteriophytochrome (bph), sensory rhodopsin (sr), and photoactive yellow protein (pyp), which all appear to function as light sensors. we herein interpret new findings within the context of current knowledge. for greater detail, the reader is referred to comprehensive reviews on these topics. of the three proteins, o ... | 2004 | 15170480 |
| effects of light intensity distribution on growth of rhodobacter capsulatus. | for cultivation of photosynthetic cells under defined light intensity distributions, the repeated batch culture, in which a part of culture broth containing grown cells was repeatedly replaced at predetermined time intervals with a fresh medium to keep the cell concentration constant at an initial value, was employed. by use of this method the effects of the light intensity distribution on the growth characteristics of rhodobacter capsulatus were studied. unexpected decreases in the specific gro ... | 2004 | 15176912 |
| characterization of the bonding interactions of q(b) upon photoreduction via a-branch or b-branch electron transfer in mutant reaction centers from rhodobacter sphaeroides. | in rhodobacter sphaeroides reaction centers (rcs) containing the mutation ala m260 to trp (am260w), transmembrane electron transfer along the full-length of the a-branch of cofactors is prevented by the loss of the q(a) ubiquinone, but it is possible to generate the radical pair p(+)h(a)(-) by a-branch electron transfer or the radical pair p(+)q(b)(-) by b-branch electron transfer. in the present study, ftir spectroscopy was used to provide direct evidence for the complete absence of the q(a) ub ... | 2004 | 15178474 |
| quantum molecular dynamics simulation of proton transfer in cytochrome c oxidase. | proton transfer/translocation is studied in cytochrome c oxidase (cco) by a combination of quantum mechanics (qm) for the transferring protons and classical molecular dynamics (md) for the protein and solvent. the possibility of a glutamate, glu286 in the rhodobacter sphaeroides numbering scheme, acting as a rely point for proton translocation is investigated. the md finds a hydrogen-bonded cycle of two waters and the carboxylate oxygens of glu286. the possibility of protonating glu286 to form n ... | 2004 | 15178480 |
| identification of a novel protonation pattern for carboxylic acids upon q(b) photoreduction in rhodobacter sphaeroides reaction center mutants at asp-l213 and glu-l212 sites. | in the reaction center from the photosynthetic purple bacterium rhodobacter sphaeroides, light energy is rapidly converted to chemical energy through coupled electron-proton transfer to a buried quinone molecule q(b). involved in the proton uptake steps are carboxylic acids, which have characteristic infrared vibrations that are observable using light-induced fourier transform infrared (ftir) difference spectroscopy. upon formation, q(b)(-) induces protonation of glu-l212, located within 5 a of ... | 2004 | 15182169 |
| genome organization and localization of the puflm genes of the photosynthesis reaction center in phylogenetically diverse marine alphaproteobacteria. | genome organization, plasmid content and localization of the puflm genes of the photosynthesis reaction center were studied by pulsed-field gel electrophoresis (pfge) in marine phototrophic alphaproteobacteria. both anaerobic phototrophs (rhodobacter veldkampii and rhodobacter sphaeroides) and strictly aerobic anoxygenic phototrophs from the roseobacter-sulfitobacter-silicibacter clade (roseivivax halodurans, roseobacter litoralis, staleya guttiformis, roseovarius tolerans, and five new strains ... | 2004 | 15184132 |
| use of sinorhizobium meliloti as an indicator for specific detection of long-chain n-acyl homoserine lactones. | population-density-dependent gene expression in gram-negative bacteria involves the production of signal molecules characterized as n-acyl homoserine lactones (ahls). the synthesis of ahls by numerous microorganisms has been identified by using biosensor strains based on the agrobacterium tumefaciens and chromobacterium violaceum quorum-sensing systems. the symbiotic nitrogen-fixing bacterium sinorhizobium meliloti is rapidly becoming a model organism for the study of quorum sensing. this organi ... | 2004 | 15184178 |
| phototrophic utilization of taurine by the purple nonsulfur bacteria rhodopseudomonas palustris and rhodobacter sphaeroides. | taurine metabolism by two phototrophically grown purple nonsulfur bacteria enrichment isolates has been examined. rhodopseudomonas palustris (strain tau1) grows with taurine as a sole electron donor, sulfur and nitrogen source during photoautotrophic growth. rhodobacter sphaeroides (strain tau3) grows on the compound as sole electron donor, sulfur and nitrogen source, and partial carbon source, in the presence of co(2) during photoheterotrophic growth. both organisms utilize an inducible taurine ... | 2004 | 15184574 |
| the role of dor gene products in controlling the p2 promoter of the cytochrome c2 gene, cyca, in rhodobacter sphaeroides. | this study explores the regulatory networks controlling anaerobic energy production by the facultative phototroph rhodobacter sphaeroides. the specific aim was to determine why activity of the p2 promoter for the gene (cyca) encoding the essential photosynthetic electron carrier, cytochrome c(2), is decreased when the alternative electron acceptor dmso is added to photosynthetically grown cells. the presence of dmso is believed to activate the dorr response regulator, which controls expression o ... | 2004 | 15184575 |
| autodisplay of active sorbitol dehydrogenase (sdh) yields a whole cell biocatalyst for the synthesis of rare sugars. | whole cell biocatalysts are attractive technological tools for the regio- and enantioselective synthesis of products, especially from substrates with several identical reactive groups. in the present study, a whole cell biocatalyst for the synthesis of rare sugars from polyalcohols was constructed. for this purpose, sorbitol dehydrogenase (sdh) from rhodobacter sphaeroides, a member of the short-chain dehydrogenase/reductase (sdr) family, was expressed on the surface of escherichia coli using au ... | 2004 | 15185373 |