| definition and distinction between assimilatory, dissimilatory and respiratory pathways. | | 1998 | 9720883 |
| expression of glnb and a glnb-like gene (glnk) in a ribulose bisphosphate carboxylase/oxygenase-deficient mutant of rhodobacter sphaeroides. | in a ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco)-deficient mutant of rhodobacter sphaeroides, strain 16phc, nitrogenase activity was derepressed in the presence of ammonia under photoheterotrophic growth conditions. previous studies also showed that reintroduction of a functional rubisco and calvin-benson-bassham (cbb) pathway suppressed the deregulation of nitrogenase synthesis in this strain. in this study, the derepression of nitrogenase synthesis in the presence of ammonia in s ... | 1998 | 9721307 |
| topological model of the rhodobacter capsulatus light-harvesting complex i assembly protein lhaa (previously known as orf1696). | a theoretical topology of the rhodobacter capsulatus membrane protein lhaa was formulated and evaluated by gene fusion experiments. the apparent topological locations of fusion enzymes were compared with the theoretically derived structure, and a model of lhaa is suggested that consists of 12 transmembrane segments, with the n and c termini residing in the cytoplasm. | 1998 | 9721320 |
| control of the unidirectional topological orientation of a cross-linked complex composed of the bacterial photosynthetic reaction center and horse heart cytochrome c reconstituted into proteoliposomes. | control of the unidirectional topological orientation was achieved for a cross-linked complex composed of the bacterial photosynthetic reaction center and horse heart cytochrome c (rc/cyt c) reconstituted into proteoliposomes. using the method of ueno et al. [ueno et al. (1995) mater. sci. eng. c3, 1-6], we prepared rc/cyt c by conjugating cyt c to the h-subunit of rc of rhodobacter sphaeroides r-26 using a bifunctional cross-linking reagent, n-succinimidyl 3-(2-pyridyldithio)propionate (spdp), ... | 1998 | 9722656 |
| two functionally distinct regions upstream of the cbbi operon of rhodobacter sphaeroides regulate gene expression. | a number of cbbfi::lacz translational fusion plasmids containing various lengths of sequence 5' to the form i (cbbi) calvin-benson-bassham cycle operon (cbbficbbpicbbaicbblicbbsi) of rhodobacter sphaeroides were constructed. expression of beta-galactosidase was monitored under a variety of growth conditions. it was found that 103 bp of sequence upstream of the cbbfi transcription start was sufficient to confer low levels of regulated cbbi promoter expression; this activity was dependent on the p ... | 1998 | 9733694 |
| cytochrome c oxidase from eucaryotes but not from procaryotes is allosterically inhibited by atp. | the activity of reconstituted cytochrome c oxidase from bovine heart but not from rhodobacter sphaeroides is allosterically inhibited by intraliposomal atp, which binds to subunit iv. the activity of cytochrome c oxidase of wild-type yeast and of a subunit via-deleted yeast mutant, measured with tween 20-solubilized mitochondria in the presence of an atp-regenerating system, was also allosterically inhibited by atp, indicating the general validity of this mechanism of "respiratory control" in eu ... | 1998 | 9739469 |
| different cleavage specificities of rnases iii from rhodobacter capsulatus and escherichia coli. | 23s rrna in rhodobacter capsulatus shows endoribonuclease iii (rnase iii)-dependent fragmentation in vivo at a unique extra stem-loop extending from position 1271 to 1331. rnase iii is a double strand (ds)-specific endoribonuclease. this substrate preference is mediated by a double-stranded rna binding domain (dsrbd) within the protein. although a certain degree of double strandedness is a prerequisite, the question arises what structural features exactly make this extra stem-loop an rnase iii c ... | 1998 | 9742248 |
| plasmid content and localization of the genes encoding the denitrification enzymes in two strains of rhodobacter sphaeroides. | plasmid content and localization of the genes encoding the reductases of the denitrification pathway were determined in the photosynthetic bacterium rhodobacter sphaeroides forma sp. denitrificans by transverse alternating-field electrophoresis (tafe) and hybridization with digoxigenin-labeled homologous probes. two large plasmids of 102 and 115 kb were found. the genes encoding the various reductases are not clustered on a single genetic unit. the nap locus (localized with a napa probe), the ni ... | 1998 | 9742704 |
| projection structures of three photosynthetic complexes from rhodobacter sphaeroides: lh2 at 6 a, lh1 and rc-lh1 at 25 a. | three photosynthetic complexes, light-harvesting complex 2 (lh2), light-harvesting complex 1 (lh1), and the reaction centre-light-harvesting complex 1 photounit (rc-lh1), were purified from a single species of a purple bacterium, rhodobacter sphaeroides, and reconstituted into two-dimensional (2-d) crystals. vesicular 2-d crystals of lh1 and rc-lh1 were imaged in negative stain and projection maps at 25 a resolution were produced. the rings formed by lh1 have approximately the same mean diameter ... | 1998 | 9743630 |
| imidazole binding to rhodobacter capsulatus cytochrome c2. effect of site-directed mutants on ligand binding. | although ligand binding in c-type cytochromes is not directly related to their physiological function, it has the potential to provide valuable information on protein stability and dynamics, particularly in the region of the methionine sixth heme ligand and the nearby peptide chain that has been implicated in electron transfer. thus, we have measured the equilibrium and kinetics of binding of imidazole to eight mutants of rhodobacter capsulatus cytochrome c2 that differ in overall protein stabil ... | 1998 | 9748230 |
| a conformational change of the photoactive bacteriopheophytin in reaction centers from rhodobacter sphaeroides. | it is demonstrated by endor and special triple spectroscopy that two distinct radical anion states of the intermediate electron acceptor (i), a bacteriopheophytin, can be freeze-trapped in isolated photosynthetic reaction centers of rhodobacter sphaeroides. the formation of these states depends on the illumination time prior to freezing and the temperature. the first state, i1.-, is metastable and relaxes irreversibly at t approximately 160 k to the second state, i2.-. experiments on quinone dep ... | 1998 | 9748312 |
| the primary structures of the low-redox potential diheme cytochromes c from the phototrophic bacteria rhodobacter sphaeroides and rhodobacter adriaticus reveal a new structural family of c-type cytochromes. | the complete amino acid sequence of the low-redox potential cytochrome c-551.5 from rhodobacter sphaeroides was determined by automated edman degradation combined with mass spectroscopy. there are 139 residues and two typical cys-x-x-cys-his heme-binding sites. a homologous low-redox potential cytochrome was also sequenced from rhodobacter adriaticus and was found to contain 126 residues. it is 53% identical to that of rb. sphaeroides and has two internal deletions of one and five residues. the ... | 1998 | 9748313 |
| electrocatalytic reduction of s-nitrosoglutathione at electrodes modified with an electropolymerized film of a pyrrole-derived viologen system and their application to cellular s-nitrosoglutathione determinations. | the preparation, electrochemical characterization, and analytical applications of glassy carbon (gc) electrodes modified with electropolymerized films of the cation n,n'-di(3-pyrrol-1-yl-propyl)-4,4'-bipyridine (dppb) are described. electropolymerized films of dppb on gc electrodes exhibit two one-electron redox processes centered at -0.45 and -0.85 v, respectively. s-nitrosoglutathione (gsno) can be electrocatalytically reduced at electrodes modified with electropolymerized films of dppb at app ... | 1998 | 9750150 |
| transcriptional regulation of photosynthesis operons in rhodobacter sphaeroides 2.4.1. | | 1998 | 9750207 |
| conformational gating of the electron transfer reaction qa-.qb --> qaqb-. in bacterial reaction centers of rhodobacter sphaeroides determined by a driving force assay. | the mechanism of the electron transfer reaction, qa-.qb --> qaqb-., was studied in isolated reaction centers from the photosynthetic bacterium rhodobacter sphaeroides by replacing the native q10 in the qa binding site with quinones having different redox potentials. these substitutions are expected to change the intrinsic electron transfer rate by changing the redox free energy (i.e., driving force) for electron transfer without affecting other events that may be associated with the electron tra ... | 1998 | 9751725 |
| triplet energy transfer in bacterial photosynthetic reaction centres. | [3-vinyl]-132-oh-bacteriochlorophyll a has been selectively exchanged against native bacteriochlorophyll a in the monomer binding sites at the a- and b-branch of the photosynthetic reaction centre from rhodobacter sphaeroides. transient absorption difference measurements were performed on these samples over a temperature range from 4.2 to 300 k with 20 ns time resolution. specifically the decay of the primary donor triplet state, 3p870, as well as the rise and decay rates of the carotenoid tripl ... | 1998 | 9757082 |
| flash-induced changes in buffering capacity of reaction centers from photosynthetic bacteria reveal complex interaction between quinone pockets. | a novel method was applied to determine light-induced protonation in reaction centers from photosynthetic purple bacteria. changes in buffering capacities upon flash excitation were detected in (0.03% triton x-100) detergent solution of reaction centers from rhodobacter (rb.) sphaeroides and rb. capsulatus wild type and mutant strains with empty or occupied secondary quinone (qb) binding sites in the presence of an external electron donor. the light-induced differences in buffering capacities be ... | 1998 | 9757083 |
| a rapid method for the isolation of intracytoplasmic membranes from rhodopseudomonas sphaeroides using an air-driven ultracentrifuge. | a method has been developed for the isolation intracytoplasmic (icm) vesicles (chromatophores) from rhodopseudomonas sphaeroides using an air-driven ultracentrifuge. application of conventional techniques used for preparative scale equipment to the air-driven ultracentrifuge allows the rapid isolation of icm vesicles from reduced quantities of starting material. sodium dodecyl sulfatepolyacrylamide gel electrophoresis profiles of icm vesicles isolated in this fashion are essentially indistinguis ... | 1978 | 9762099 |
| molecular cloning and expression analysis of the rhodobacter capsulatus sodb gene, encoding an iron superoxide dismutase. | genetic complementation of a soda sodb escherichia coli mutant strain was used to clone rhodobacter capsulatus genes involved in detoxification of superoxide radicals. after sequence analysis, 1 of the 16 identical clones obtained by this selection procedure was shown to contain an open reading frame with sequence similarity to that coding for fe-containing superoxide dismutases (sodb). the r. capsulatus sodb gene was expressed in e. coli, and the nature of the metal ligand was confirmed by inhi ... | 1998 | 9765573 |
| dimethylsulphoxide reductase from purple phototrophic bacteria: structures and mechanism(s). | | 1998 | 9765885 |
| protein engineering of the photoreaction centre from rhodobacter sphaeroides. | | 1998 | 9765891 |
| modification of the binding pocket for the qa ubiquinone in the reaction centre from rhodobacter sphaeroides. | | 1998 | 9765928 |
| stopped-flow studies on dimethylsulphoxide reductase from rhodobacter capsulatus: kinetic competence of the dimethylsulphide-reduced intermediate. | | 1998 | 9765930 |
| the periplasmic nitrate reductase of escherichia coli--a comparison with the nap systems of other bacteria. | | 1998 | 9765936 |
| a chemotaxis cluster from agrobacterium tumefaciens. | we report the dna sequence of a 9.6-kb region of the agrobacterium tumefaciens chromosome containing a putative 8-kb chemotaxis operon. the putative operon begins with orf1, whose predicted protein product shows strong sequence identity to methyl-accepting chemotaxis proteins (mcps), followed by orf2, chey1, chea, cher, cheb, chey2, orf9, orf10. all of the identified homologues show a high degree of sequence conservation with their counterparts in the che operons from sinorhizobium meliloti and ... | 1998 | 9767126 |
| charge displacements in interfacial layers containing reaction centers. | reaction centers from the photosynthetic bacterium rhodobacter sphaeroides were oriented in phospholipid interfacial layers adsorbed to a teflon film separating two electrolyte-filled compartments of a teflon cell. light-induced voltage changes were measured as a function of time across electrodes immersed in the cell compartments. the experimental system is characterized both experimentally and theoretically to relate the measured signals to the light-induced displacement currents in the reacti ... | 1998 | 9767675 |
| low frequency vibrational modes in proteins: changes induced by point-mutations in the protein-cofactor matrix of bacterial reaction centers. | as a step toward understanding their functional role, the low frequency vibrational motions (<300 cm-1) that are coupled to optical excitation of the primary donor bacteriochlorophyll cofactors in the reaction center from rhodobacter sphaeroides were investigated. the pattern of hydrogen-bonding interaction between these bacteriochlorophylls and the surrounding protein was altered in several ways by mutation of single amino acids. the spectrum of low frequency vibrational modes identified by fem ... | 1998 | 9770482 |
| proton uptake by carboxylic acid groups upon photoreduction of the secondary quinone (qb) in bacterial reaction centers from rhodobacter sphaeroides: ftir studies on the effects of replacing glu h173. | in the photosynthetic reaction center (rc) from rhodobacter sphaeroides, glu h173, located approximately 7 a from the center of the secondary quinone acceptor qb, is expected to contribute to proton uptake upon qb- formation in response to the movement of an electron in its vicinity. steady-state ftir difference spectroscopy provides a method to monitor proton uptake by carboxylic acids upon photochemical changes. the ftir spectra corresponding to the photoreduction of qb were obtained at ph 7 f ... | 1998 | 9772172 |
| the post-translational modification in cytochrome c oxidase is required to establish a functional environment of the catalytic site. | mutation of tyrosine-288 to a phenylalanine in cytochrome c oxidase from rhodobacter sphaeroides drastically alters its properties. tyr-288 lies in the cub-cytochrome a3 binuclear catalytic site and forms a hydrogen bond with the hydroxy group on the farnesyl side chain of the heme. in addition, through a post-translational modification, y288 is covalently linked to one of the histidine ligands that is coordinated to cub. in the y288f mutant enzyme, the "as-isolated" preparation is a mixture of ... | 1998 | 9772174 |
| flexibility of the neck region of the rieske iron-sulfur protein is functionally important in the cytochrome bc1 complex. | the crystal structure of the mitochondrial cytochrome bc1 complex suggests that movement of the extramembrane (head) domain of the rieske iron-sulfur protein (isp) is involved in electron transfer. such movement requires flexibility in the neck region of isp. to test this hypothesis, rhodobacter sphaeroides mutants expressing his-tagged cytochrome bc1 complexes with altered isp necks (residues 39-48) were generated and characterized. mutants with increased rigidity of the neck, generated by a do ... | 1998 | 9774409 |
| single electron reduction of cytochrome c oxidase compound f: resolution of partial steps by transient spectroscopy. | the final step of the catalytic cycle of cytochrome oxidase, the reduction of oxyferryl heme a3 in compound f, was investigated using a binuclear polypyridine ruthenium complex (ru2c) as a photoactive reducing agent. the net charge of +4 on ru2c allows it to bind electrostatically near cua in subunit ii of cytochrome oxidase. photoexcitation of ru2c with a laser flash results in formation of a metal-to-ligand charge-transfer excited state, ru2c, which rapidly transfers an electron to cua of cyto ... | 1998 | 9778367 |
| crystallographic analysis of freeze-fractured three-dimensionally ordered specimens. | we describe here an original approach for solving the structure of three-dimensionally ordered specimens at low and medium resolutions. it combines freeze-fracture electron microscopy and quantitative image processing and has been first successfully applied to the crystallographic study of different lipid-containing cubic phases. the structure preservation during cryofixation is controlled by recording x-ray diffraction before and after freezing. well frozen cubic phases show fracture planes whi ... | 1998 | 9782393 |
| helicobacter pylori lipopolysaccharide binds to cd14 and stimulates release of interleukin-8, epithelial neutrophil-activating peptide 78, and monocyte chemotactic protein 1 by human monocytes. | helicobacter pylori gastritis is characterized by leukocyte infiltration of the gastric mucosa. the aims of this study were to determine whether h. pylori-derived factors stimulate chemokine release from human monocytes and to ascertain whether h. pylori lipopolysaccharide (lps) may be responsible for this effect. human peripheral blood monocytes were exposed to an h. pylori water extract (hpe) or to purified h. pylori lps. levels of the chemokines interleukin-8 (il-8), epithelial neutrophil-act ... | 1998 | 9784544 |
| factors determining electron-transfer rates in cytochrome c oxidase: investigation of the oxygen reaction in the r. sphaeroides enzyme. | we have investigated the kinetics of the single-turnover reaction of fully reduced solubilised cytochrome c oxidase (cytochrome aa3) from rhodobacter sphaeroides with dioxygen using the flow-flash methodology and compared the results to those obtained with the well-characterised bovine mitochondrial enzyme. the overall reaction sequence was the same in the two enzymes, but the extents and rates of the electron-transfer reactions differed, implying differences in redox potentials, and/or interact ... | 1998 | 9784618 |
| redox-dependent gene regulation in rhodobacter sphaeroides 2.4.1(t): effects on dimethyl sulfoxide reductase (dor) gene expression. | the ability of rhodobacter sphaeroides 2.4.1(t) to respire anaerobically with the alternative electron acceptor dimethyl sulfoxide (dmso) or trimethylamine n-oxide (tmao) is manifested by the molybdoenzyme dmso reductase, which is encoded by genes of the dor locus. previously, we have demonstrated that dor expression is regulated in response to lowered oxygen tensions and the presence of dmso or tmao in the growth medium. several regulatory proteins have been identified as key players in this re ... | 1998 | 9791109 |
| molecular detection, isolation, and physiological characterization of functionally dominant phenol-degrading bacteria in activated sludge. | dna was isolated from phenol-digesting activated sludge, and partial fragments of the 16s ribosomal dna (rdna) and the gene encoding the largest subunit of multicomponent phenol hydroxylase (lmph) were amplified by pcr. an analysis of the amplified fragments by temperature gradient gel electrophoresis (tgge) demonstrated that two major 16s rdna bands (bands r2 and r3) and two major lmph gene bands (bands p2 and p3) appeared after the activated sludge became acclimated to phenol. the nucleotide s ... | 1998 | 9797297 |
| biosynthesis of the 3-acetyl and 13(1)-oxo groups of bacteriochlorophyll a in the facultative aerobic bacterium, rhodovulum sulfidophilum--the presence of both oxygenase and hydratase pathways for isocyclic ring formation. | using (18)o-labelling and mass spectrometry, we have examined bacteriochlorophyll a formation in rhodovulum sulfidophilum, formerly known as rhodobacter sulfidophilus, which forms large amounts of bch1 a both aerobically in the dark and anaerobically in the light. r. sulfidophilum, growing under strict anaerobiosis in the light, possesses hydratases which incorporate (18)o label from h2(18)o into both the 13(1)-oxo and 3-acetyl oxygens; in addition, the four carboxyl oxygens at c13(3) and c17(3) ... | 1998 | 9799118 |
| quenching of chlorophyll fluorescence by quinones. | quinones caused quenching of chl a fluorescence in native and model systems. menadione quenched twofold the fluorescence of chl a and bchl a in pea chloroplasts, chromatophores of purple bacteria, and liposomes at concentrations of 50-80 microm. to obtain twofold quenching in triton x-100 micelles and in ethanol, the addition of 1.3 mm and 11 mm menadione was required, respectively. a proportional decrease in the lifetime and yield of chl a fluorescence in chloroplasts, observed as the menadione ... | 1998 | 9801801 |
| aerobic repression of the rhodobacter capsulatus bchc promoter involves cooperative interactions between crtj bound to neighboring palindromes. | previous studies demonstrated that bacteriochlorophyll, carotenoid, and light harvesting gene expression in rhodobacter capsulatus is repressed under aerobic growth conditions by the repressor crtj. isolated crtj is known to bind to the palindrome tgtn12aca, which is present in two copies in the bchc promoter, one of which spans the -35 and the other the -10 sigma-70 recognition sequences. in this study, we demonstrate that crtj binds to the two palindromic sites in the bchc promoter in a cooper ... | 1998 | 9804852 |
| crtj bound to distant binding sites interacts cooperatively to aerobically repress photopigment biosynthesis and light harvesting ii gene expression in rhodobacter capsulatus. | expression of light harvesting ii genes and of bacteriochlorophyll and carotenoid biosynthesis genes in rhodobacter capsulatus is repressed under aerobic growth conditions by the transcription factor crtj. in this study, we demonstrate that the crta-crti intergenic region contains divergent promoters that initiate transcription 116 base pairs apart, based on primer extension analyses. dnase i protection assays demonstrate that purified crtj binds to one palindrome that overlaps the crta -10 prom ... | 1998 | 9804853 |
| purification and characterization of pyruvate oxidoreductase from the photosynthetic bacterium rhodobacter capsulatus. | pyruvate:ferredoxin (flavodoxin) oxidoreductase (por) was purified 3050-fold to apparent homogeneity from the photosynthetic bacterium rhodobacter capsulatus using ion-exchange, reactive red, and gel filtration chromatography. the isolated enzyme was sensitive to dilution and oxygen (especially when in dilute solution). the molecular mass of the native enzyme was determined by high performance liquid chromatography gel filtration to be 270+/-20 kda. since a subunit molecular mass of 130+/-5 kda ... | 1998 | 9804883 |
| proton uptake controls electron transfer in cytochrome c oxidase. | in cytochrome c oxidase, a requirement for proton pumping is a tight coupling between electron and proton transfer, which could be accomplished if internal electron-transfer rates were controlled by uptake of protons. during reaction of the fully reduced enzyme with oxygen, concomitant with the "peroxy" to "oxoferryl" transition, internal transfer of the fourth electron from cua to heme a has the same rate as proton uptake from the bulk solution (8,000 s-1). the question was therefore raised whe ... | 1998 | 9811847 |
| molecular analysis of the trimethylamine n-oxide (tmao) reductase respiratory system from a shewanella species. | trimethylamine n-oxide (tmao) is an abundant compound of tissues of marine fish and invertebrates. during fish spoilage, certain marine bacteria can reduce tmao to nauseous trimethylamine (tma). one such bacterium has been isolated and identified as a new shewanella species, and called shewanella massilia. the anaerobic growth of s. massilia is greatly increased when tmao is added, indicating that tmao reduction involves a respiratory pathway. the tora enzyme responsible for tmao reduction is a ... | 1998 | 9813127 |
| crystal structure of oxidized trimethylamine n-oxide reductase from shewanella massilia at 2.5 a resolution. | the periplasmic trimethylamine n-oxide (tmao) reductase from the marine bacteria shewanella massilia is involved in a respiratory chain, having trimethylamine n-oxide as terminal electron acceptor. this molybdoenzyme belongs to the dimethyl sulfoxide (dmso) reductase family, but has a different substrate specificity than its homologous enzyme. while the dmso reductases reduce a broad spectra of organic s-oxide and n-oxide compounds, tmao reductase from shewanella massilia reduces only tmao as th ... | 1998 | 9813128 |
| the lh1-rc core complex of rhodobacter sphaeroides: interaction between components, time-dependent assembly, and topology of the pufx protein. | mutant strains of the photosynthetic bacterium rhodobacter sphaeroides, lacking either lh1, the rc or pufx, were analysed by mild detergent fractionation of the cores. this reveals a hierarchy of binding of pufx in the order rc:lh1 > lh1 > rc. the assembly of photosynthetic membranes was studied by switching highly aerated cells to conditions of low aeration in the dark. the rc-h subunit appears before other components, followed by the pufbalmx then pufba transcripts. synthesis of the pufx polyp ... | 1998 | 9814844 |
| the atpibexf operon coding for the f0 sector of the atp synthase from the purple nonsulfur photosynthetic bacterium rhodobacter capsulatus. | the atpibexf operon coding for the f0 sector of the atp synthase from rhodobacter capsulatus was cloned and sequenced. the genes for the five subunits were present in the order: atpi (subunit i), atpb (subunit a), atpe (subunit c), atpx (subunit b'), and atpf (subunit b). the transcription initiation site was defined by primer-extension analysis. a duplicated and divergent copy of the b subunit gene (subunit b') was present. this duplication is found only in photosynthetic prokaryotes and in pla ... | 1998 | 9818357 |
| isolation and characterization of a two-subunit cytochrome b-c1 subcomplex from rhodobacter capsulatus and reconstitution of its ubihydroquinone oxidation (qo) site with purified fe-s protein subunit. | the presence of a two-subunit cytochrome (cyt) b-c1 subcomplex in chromatophore membranes of rhodobacter capsulatus mutants lacking the rieske iron-sulfur (fe-s) protein has been described previously [davidson, e., ohnishi, t., tokito, m., and daldal, f. (1992) biochemistry 31, 3351-3358]. here, this subcomplex was purified to homogeneity in large quantities, and its properties were characterized. as expected, it contained stoichiometric amounts of cyt b and cyt c1 subunits forming a stable enti ... | 1998 | 9819216 |
| steps toward constructing a cytochrome b6 f complex in the purple bacterium rhodobacter sphaeroides: an example of the structural plasticity of a membrane cytochrome. | we have modified the cytochrome b subunit of the cytochrome bc1 complex from the purple bacterium rhodobacter sphaeroides to introduce two distinctive features of cytochrome b6 f complexes. in the first one, we have split cyt b into two polypeptides thus mimicking the organization of cyt b6 and subunit iv in the b6 f complexes. in the second, an extra residue was added between his198 and phe199, thus extending the span between the histidine ligands for the two b-hemes in helix d. the properties ... | 1998 | 9819220 |
| basis for monomer stabilization in rhodopseudomonas palustris cytochrome c' derived from the crystal structure. | the crystal structure of an unusual monomeric cytochrome c' from rhodopseudomonas palustris (rpcp) has been determined at 2.3 a resolution. rpcp has the four-helix (helices a, b, c and d) bundle structure similar to dimeric cytochromes c'. however the amino acid composition of the surface of helices a and b in rpcp is remarkably different from that of the dimeric cytochromes c'. this surface forms the dimer interface in the latter proteins. rpcp has seven charged residues on this surface contrar ... | 1998 | 9826513 |
| short-term regulation of nitrogenase activity by nh4+ in rhodobacter capsulatus: multiple in vivo nitrogenase responses to nh4+ addition. | the photosynthetic bacterium rhodobacter capsulatus has been shown to carry out nitrogenase "switch-off," a rapid, reversible inhibition of in vivo activity. here, we demonstrate that highly nitrogen-limited cultures of both the wild-type strain and a drat drag mutant are capable of nitrogenase switch-off while moderately nitrogen-limited cultures show instead a "magnitude" response, with a decrease in in vivo nitrogenase activity that is proportional to the amount of added nh4+. | 1998 | 9829952 |
| proline-induced disruption of a transmembrane alpha-helix in its natural environment. | alpha-helix formation in globular proteins has been studied both theoretically and experimentally for decades, while a lack of both high-resolution structures and suitable experimental techniques has hampered the study of helices in membrane proteins. we have developed a new experimental approach, glycosylation mapping, where the active site of the lumenally exposed endoplasmic reticulum enzyme oligosaccharyl transferase is used as a point of reference against which the position of a transmembra ... | 1998 | 9837734 |
| ft-ir analysis of membranes of rhodobacter sphaeroides 2.4.3 grown under microaerobic and denitrifying conditions. | fourier transform infrared spectroscopic analysis of co binding proteins in rhodobacter sphaeroides reveals the presence of a membrane-bound nitric oxide reductase (nor). nor has been clearly distinguished from the cytochrome oxidases by the temperature-dependence of relaxation following photodissociation of the co complex at cryogenic temperatures. the center frequency and band shape, 1970 cm-1 and 20-30 cm-1 width at half-peak height, are similar to those reported for resonance raman spectra o ... | 1998 | 9838065 |
| molecular genetics of the genus paracoccus: metabolically versatile bacteria with bioenergetic flexibility. | paracoccus denitrificans and its near relative paracoccus versutus (formerly known as thiobacilllus versutus) have been attracting increasing attention because the aerobic respiratory system of p. denitrificans has long been regarded as a model for that of the mitochondrion, with which there are many components (e.g., cytochrome aa3 oxidase) in common. members of the genus exhibit a great range of metabolic flexibility, particularly with respect to processes involving respiration. prominent exam ... | 1998 | 9841665 |
| metabolism of l-phenylalanine and l-tyrosine by the phototrophic bacterium rhodobacter capsulatus. | the phototrophic bacterium rhodobacter capsulatus utilizes the aromatic amino acids l-phenylalanine and l-tyrosine as nitrogen source. l-phenylalanine is hydroxylated to l-tyrosine, which is further converted into p-hydroxyphenyl pyruvate (phpp) by a transamination reaction. the bacterium is unable to grow at the expense of these amino acids as the sole carbon source, although it is able to degrade them to homogentisate, probably by unspecific hydroxylation reactions. metabolization of l-phenyla ... | 1999 | 9841783 |
| molecular and functional analysis of ptav320, a repabc-type replicon of the paracoccus versutus composite plasmid ptav1. | the second replicator region of the native plasmid ptav1 of paracoccus versutus has been identified thus proving the composite nature of this replicon. the minimal replicon designated ptav320 (4.3 kb) was cloned and sequenced. ptav320 encodes three putative proteins--repa, repb and repc. this replicator region shows strong structural and functional similarity to repabc-type replicons found in several agrobacterium and rhizobium plasmids. the origin of replication appears to be localized within t ... | 1998 | 9846751 |
| rsgdb, the rhodobacter sphaeroides genome database. | this report provides a summary of the sequencing project of the small chromosome (cii) of rhodobacter sphaeroides 2.4.1(t),and introduces the first version of the genome database of this bacterium. the database organizes and describes diverse sets of biological information. the main role of the r.sphaeroides genome database (rsgdb) is to provide public access to the collected genomic information for r.sphaeroides via the world-wide web at http://utmmg.med.uth.tmc.edu/sphaeroides. the database al ... | 1999 | 9847142 |
| mass spectrometric mapping of ion channel proteins (porins) and identification of their supramolecular membrane assembly. | mass spectrometric peptide mapping, particularly by matrix-assisted laser desorption-ionization (maldi-ms), has recently been shown to be an efficient tool for the primary structure characterization of proteins. in combination with in situ proteolytic digestion of proteins separated by one- and two-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis (sds-page), mass spectrometric peptide mapping permits identification of proteins from complex mixtures such as cell lysates. in t ... | 1998 | 9849911 |
| characterization of cytochrome c-556 from the purple phototrophic bacterium rhodobacter capsulatus as a cytochrome-c peroxidase. | a cytochrome c-556 was purified from rhodobacter capsulatus and the complete amino acid sequence was determined. it contains 328 amino acid residues and two typical heme-binding sites at cysteine residues 54 and 57 and at residues 200 and 203. it is homologous to the family of bacterial cytochrome c peroxidases (bccp) with 69% identity to paracoccus denitrificans bccp and 60% identity to pseudomonas aeruginosa bccp for which there is a three-dimensional structure. there is lesser similarity to t ... | 1998 | 9851688 |
| heterologous expression of the rhodobacter capsulatus bchi, -d, and -h genes that encode magnesium chelatase subunits and characterization of the reconstituted enzyme. | magnesium chelatase inserts mg2+ into protoporphyrin ix in the chlorophyll and bacteriochlorophyll biosynthetic pathways. in photosynthetic bacteria, the products of three genes, bchi, bchd, and bchh, are required for magnesium chelatase activity. these genes from rhodobacter capsulatus were cloned separately into expression plasmids pet3a and pet15b. the pet15b constructs produced nh2-terminally his6-tagged proteins. all proteins were highly expressed and were purified to near homogeneity. the ... | 1998 | 9852082 |
| appa, a redox regulator of photosystem formation in rhodobacter sphaeroides 2.4.1, is a flavoprotein. identification of a novel fad binding domain. | the appa protein is required for increased photosystem gene expression upon transition of the facultatively photoheterotrophic bacterium rhodobacter sphaeroides 2.4.1 from aerobic to anaerobic photosynthetic conditions. appa shows no obvious similarity to proteins with established function. genetic evidence suggests that its effect is exerted through modulation of the activity of the repressor ppsr, which controls expression of multiple photosystem genes. to gain insight into the nature of appa ... | 1998 | 9857073 |
| in vitro reconstitution of the core and peripheral light-harvesting complexes of rhodospirillum molischianum from separately isolated components. | in most purple bacteria, the core light-harvesting complex (lh1) differs from the peripheral light-harvesting complex (lh2) in spectral properties and amino acid sequences. in rhodospirillum (rs. )molischianum, however, the lh2 closely resembles the lh1 of many species in amino acid sequence identity and in some spectral properties (e.g., circular dichroism and resonance raman). despite these similarities to lh1, the lh2 of rs. molischianum displays an absorption spectrum similar to the lh2 comp ... | 1998 | 9860861 |
| generation of triplet and cation-radical bacteriochlorophyll a in carotenoidless lh1 and lh2 antenna complexes from rhodobacter sphaeroides. | the lh1 antenna complex and a native form of the lh2 complex were isolated from the carotenoidless r26 and r26.1 mutants of rhodobacter sphaeroides by the use of a new detergent, sucrose monocholate. one-color, pump-and-probe transient raman spectroscopy of these complexes using 351 nm, approximately 50 ps pulses showed the generation of the triplet state of bacteriochlorophyll a (bchl a), whereas measurements using 355 nm, approximately 12 ns pulses showed the generation of bchl a cation radica ... | 1998 | 9860862 |
| cloning and characterization of the rpoh gene of rhodobacter capsulatus. | by using an oligonucleotide mixture corresponding to a region highly conserved among alternative sigma factors we identified a new sigma factor gene (rpoh) from rhodobacter capsulatus. this gene encodes a protein of 34 kda with strong similarity to the rpoh (sigma32) factors from other bacterial species. it was not possible to inactivate the r. capsulatus rpoh gene by introducing a resistance cassette, implying that it is essential for growth. the 5' ends of the mrnas were mapped to two sequence ... | 1998 | 9862474 |
| [nucleotide sequence of gltb gene encoding the large subunit of rhodobacter sphaeroides glutamate synthase]. | the complete nucleotide sequence of a 5.4-kb chromosomal ecori-sali fragment was determined, which contains the structural gene (gltb) for the large subunit of rhodobacter sphaeroides glutamate synthase, as well as the 5'- and 3'- flanking regions. a open reading frame of 4636 base pairs was identified as r. sphaeroides gltb gene. the mw of the large subunit, as deduced from the nucleotide sequence, was estimated as 164kd. comparision of the nucleotide sequences revealed a high similarity among ... | 1997 | 9863198 |
| [identification and expression of ribulose 1,5-bisphosphate carboxylase/oxygenase gene from thiobacillus versutus]. | the chromosomal dna of thiobacillus versutus was hybridized with various heterologous ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) gene as probes. only rhodobacter sphaeroides form i rubisco gene showed homology with t. versutus. the rubisco gene fragment of t. versutus was isolated using the rubisco gene of r. sphaeroides as a probe. and the rubisco gene of t. versutus can express in e. coli cell. | 1997 | 9863205 |
| [homology analysis of rubisco gene of thiobacillus versutus with extremelly acidophilic thiobacilli]. | the chromosomal dna of thiobacillus thiooxidans and t. versutus was digested with restriction enzymes, blotted to nylon membrane by the way of southern, and hybridized with the gene probe of ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) from t. ferrooxidans. the result showed that t. thiooxidans exhibited high homology with the probe anc t. versutus was less homology with it. however t. versutus can hybridize with the gene probe of rubisco from rhodobacter sphaeroides, which indicate ... | 1997 | 9863211 |
| roles of chemosensory pathways in transient changes in swimming speed of rhodobacter sphaeroides induced by changes in photosynthetic electron transport. | the response of free-swimming rhodobacter sphaeroides to increases and decreases in the intensity of light of different wavelengths was analyzed. there was a transient (1 to 2 s) increase in swimming speed in response to an increase in light intensity, and there was a similar transient stop when the light intensity decreased. measurement of changes in membrane potential and the use of electron transport inhibitors showed that the transient increase in swimming speed, following an increase in lig ... | 1999 | 9864309 |
| thioredoxin is involved in oxygen-regulated formation of the photosynthetic apparatus of rhodobacter sphaeroides. | thioredoxin, a redox active protein, has been previously demonstrated to be essential for growth of the anoxygenic photosynthetic bacterium rhodobacter sphaeroides. in the present study, the involvement of thioredoxin in the formation of the photosynthetic apparatus of r. sphaeroides ws8 was investigated by construction and analysis of a mutant strain disrupted for the chromosomal trxa copy and carrying a plasmid-borne copy of trxa under the control of the hybrid ptrc promoter inducible by iptg ... | 1999 | 9864318 |
| cd-monitored redox titration of the rieske fe-s protein of rhodobacter sphaeroides: ph dependence of the midpoint potential in isolated bc1 complex and in membranes. | the redox potential of the rieske fe-s protein has been investigated using circular dichroism (cd)-spectroscopy. the cd features characteristic of the purified bc1 complex and membranes of rhodobacter sphaeroides were found in the region between 450 and 550 nm. the difference between reduced and oxidized cd-spectra shows a negative band at about 500 nm with a half of width 30 nm that corresponds to the specific dichroic absorption of the reduced rieske protein (fee, j.a. et al. (1984) j. biol. c ... | 1998 | 9872412 |
| heterologous expression of genes encoding bacterial light-harvesting complex ii in rhodobacter capsulatus and rhodovulum sulfidophilum. | in the present work we report the high-level expression of foreign genes encoding the light-harvesting (lhii) membrane-spanning polypeptides in photosynthetic bacteria. to do this we first constructed three deletion strains of rhodovulum (rhv.) sulfidophilum in which all or part of the puc operon, encoding the peripheral light-harvesting proteins, is missing. to investigate the heterologous expression of the light-harvesting polypeptides from rb. capsulatus in rhv. sulfidophilum and vice versa w ... | 1998 | 9880926 |
| magnesium chelatase from rhodobacter sphaeroides: initial characterization of the enzyme using purified subunits and evidence for a bchi-bchd complex. | the enzyme magnesium-protoporphyrin ix chelatase (mg chelatase) catalyses the insertion of mg into protoporphyrin ix, the first committed step in (bacterio)chlorophyll biosynthesis. in the photosynthetic bacterium rhodobacter sphaeroides, this reaction is catalysed by the products of the bchi, bchd and bchh genes. these genes have been expressed in escherichia coli so that the bchi, bchd and bchh proteins are produced with n-terminal his6 affinity tags, which has led to the production of large a ... | 1999 | 9882621 |
| mutations in the environment of the primary quinone facilitate proton delivery to the secondary quinone in bacterial photosynthetic reaction centers. | in rhodobacter capsulatus, we constructed a quadruple mutant that reversed a structural asymmetry that contributes to the functional asymmetry of the two quinone sites. in the photosynthetically incompetent quadruple mutant rq, two acidic residues near qb, l212glu and l213asp, have been mutated to ala; conversely, in the qa pocket, the symmetry-related residues m246ala and m247ala have been mutated to glu and asp. we have selected photocompetent phenotypic revertants (designated rqrev3 and rqrev ... | 1999 | 9890921 |
| rhodobacter capsulatus dna topoisomerase i purification and characterization. | a 30-kda dna topoisomerase has been purified to near homogeneity from the purple nonsulfur photosynthetic bacterium rhodobacter capsulatus. the enzyme is recognized by an antibody against a 16-mer peptide sequence from human dna topoisomerase i. the purified enzyme is a type i topoisomerase. consistent with the properties of other prokaryotic type i dna topoisomerases, the isolated enzyme is unable to relax positively supercoiled dna and absolutely requires divalent cations for its relaxation ac ... | 1999 | 9917336 |
| supramolecular organization of the photosynthetic apparatus of rhodobacter sphaeroides. | native tubular membranes were purified from the purple non-sulfur bacterium rhodobacter sphaeroides. these tubular structures contain all the membrane components of the photosynthetic apparatus, in the relative ratio of one cytochrome bc1 complex to two reaction centers, and approximately 24 bacteriochlorophyll molecules per reaction center. electron micrographs of negative-stained membranes diffract up to 25 a and allow the calculation of a projection map at 20 a. the unit cell (a = 198 a, b = ... | 1999 | 9927413 |
| identification of culturable oligotrophic bacteria within naturally occurring bacterioplankton communities of the ligurian sea by 16s rrna sequencing and probing. | > abstract typical marine bacteria (i.e., obligately oligotrophic) that were numerically dominant members of naturally occurring marine communities were identified by cloning and sequencing the amplified 16s rrna genes obtained from dilution cultures of the original samples. the data reported here refer to two different habitats of a marine pelagic environment (28 miles offshore, in the northwestern mediterranean sea). the samples were taken from the water column at two representative layers, i. ... | 1999 | 9929396 |
| [induction of early endotoxin tolerance with atoxic endotoxin--a new method for preventing sepsis syndrome]. | the induction of early-phase endotoxin tolerance in a procine endotoxin shock model by atoxic lps from rhodobacter sphaeroides led to a significant extension of the survival time (p < 0.0179). the protective effect of the non-specific tolerant state also led to an enhancement of cardiorespiratory parameters during the continuous endotoxin challenge. non-specific stimulation of host defense mechanisms with atoxic endotoxin as prophylactic agent in surgical patients at risk may prove to be benefic ... | 1998 | 9931792 |
| identification and characterization of a two-component sensor-kinase and response-regulator system (dcus-dcur) controlling gene expression in response to c4-dicarboxylates in escherichia coli. | the dcub gene of escherichia coli encodes an anaerobic c4-dicarboxylate transporter that is induced anaerobically by fnr, activated by the cyclic amp receptor protein, and repressed in the presence of nitrate by narl. in addition, dcub expression is strongly induced by c4-dicarboxylates, suggesting the presence of a novel c4-dicarboxylate-responsive regulator in e. coli. this paper describes the isolation of a tn10 mutant in which the 160-fold induction of dcub expression by c4-dicarboxylates is ... | 1999 | 9973351 |
| the structural and functional organization of h-ns-like proteins is evolutionarily conserved in gram-negative bacteria. | the structural gene of the h-ns protein, a global regulator of bacterial metabolism, has been identified in the group of enterobacteria as well as in closely related bacteria, such as erwinia chrysanthemi and haemophilus influenzae. isolated outside these groups, the bph3 protein of bordetella pertussis exhibits a low amino acid conservation with h-ns, particularly in the n-terminal domain. to obtain information on the structure, function and/or evolution of h-ns, we searched for other h-ns-rela ... | 1999 | 9987132 |
| a consensus sequence for the rhodospirillaceae sos operators. | the sequences controlling the expression of the rhodobacter capsulatus reca and uvra genes belonging to the sos dna repair system have been identified by pcr mutagenesis. data obtained demonstrated that the gttcn7gtac and gaacn7gaac motifs present upstream of the reca gene and the gttcn7gttc motif found upstream of the uvra gene are required for their respective dna damage-mediated induction. alignment of reca promoters of r. capsulatus, rhodobacter sphaeroides and rhodopseudomonas viridis with ... | 1999 | 9987839 |
| in vivo transposition of mariner-based elements in enteric bacteria and mycobacteria. | mariner family transposons are widespread among eukaryotic organisms. these transposons are apparently horizontally transmitted among diverse eukaryotes and can also transpose in vitro in the absence of added cofactors. here we show that transposons derived from the mariner element himar1 can efficiently transpose in bacteria in vivo. we have developed simple transposition systems by using minitransposons, made up of short inverted repeats flanking antibiotic resistance markers. these elements c ... | 1999 | 9990078 |
| structure and organization of a 25 kbp region of the genome of the photosynthetic green sulfur bacterium chlorobium vibrioforme containing mg-chelatase encoding genes. | a region comprising approximately 25 kbp of the genome of the strictly anaerobic and obligate photosynthetic green sulfur bacterium chlorobium vibrioforme has been mapped, subcloned and partly sequenced. approximately 15 kbp have been sequenced in it's entirety and three genes with significant homology and feature similarity to the bchi, -d and -h genes and the chli, -d and -h genes of rhodobacter and synechocystis strain pcc6803, respectively, which encode magnesium chelatase subunits, have bee ... | 1998 | 10022081 |
| localization and environmental regulation of mcp-like proteins in rhodobacter sphaeroides. | chemotaxis to many compounds by rhodobacter sphaeroides requires transport and at least partial metabolism of the chemoeffector. previous investigations using phototrophically grown cells have failed to find any homologues of the mcp chemoreceptors identified in escherichia coli. however, using an antibody raised against the highly conserved domain of e. coli tsr, mcp-like proteins were identified in r. sphaeroides ws8n. analysis using western blotting and immunogold electron microscopy showed t ... | 1999 | 10048031 |
| genomic complexity among strains of the facultative photoheterotrophic bacterium rhodobacter sphaeroides. | pulsed-field gel electrophoresis following the use of rare cutting restriction endonucleases together with southern hybridization, using markers distributed on chromosomes i and ii of rhodobacter sphaeroides 2.4.1, has been used to examine approximately 25 strains of r. sphaeroides in an effort to assess the occurrence of genome complexity in these strains. the results suggest that genome complexity is widespread and is accompanied by substantial genomic heterogeneity. | 1999 | 10049404 |
| multiple pathways for ultrafast transduction of light energy in the photosynthetic reaction center of rhodobacter sphaeroides. | a pathway of electron transfer is described that operates in the wild-type reaction center (rc) of the photosynthetic bacterium rhodobacter sphaeroides. the pathway does not involve the excited state of the special pair dimer of bacteriochlorophylls (p*), but instead is driven by the excited state of the monomeric bacteriochlorophyll (ba*) present in the active branch of pigments along which electron transfer occurs. pump-probe experiments were performed at 77 k on membrane-bound rcs by using di ... | 1999 | 10051593 |
| the cbb3 terminal oxidase of rhodobacter sphaeroides 2.4.1: structural and functional implications for the regulation of spectral complex formation. | we have previously shown that the flow of reductant through the cbb3 terminal cytochrome c oxidase of rhodobacter sphaeroides is essential to the repression of photosynthesis (ps) gene expression in the presence of oxygen by inhibiting the functional activity of the prr two-component activation system. to gain further insight into the role of the cbb3 oxidase and the cognate cconoqp operon in the oxygen regulation of ps gene expression, we constructed nonpolar, in-frame deletions within the ccon ... | 1999 | 10052939 |
| evidence for the head domain movement of the rieske iron-sulfur protein in electron transfer reaction of the cytochrome bc1 complex. | the three-dimensional structure of the mitochondrial cytochrome bc1 complex suggests that movement of the extramembrane domain (head) of the rieske iron-sulfur protein (isp) may play an important role in electron transfer. such movement requires flexibility in the neck region of isp, since the head and transmembrane domains of the protein are rather rigid. to test this hypothesis, rhodobacter sphaeroides mutants expressing his-tagged cytochrome bc1 complexes with cysteine substitution at various ... | 1999 | 10066773 |
| molecular approaches to probe differential nadh activation of phosphoribulokinase isozymes from rhodobacter sphaeroides. | the cbbpi and cbbpii genes from rhodobacter sphaeroides, encoding highly similar phosphoribulokinase (prk) isozymes, prk i and prk ii, respectively, exhibited differential allosteric activation by nadh. the two cbbp genes were cloned into expression vectors and homogeneous recombinant protein prepared. prk ii was found to be inherently less stable than prk i; however, the addition of substrate atp resulted in the complete protection of both isozymes to a 15-min incubation at 50 degrees c. the re ... | 1999 | 10068449 |
| repression of nitrogenase by ethanol in nitrogen-deprived cultures of rhodovulum sulfidophilum. | light-dependent h2 evolution did not occur in nitrogen-deprived cultures of rhodovulum sulfidophilum in the presence of ethanol. when ethanol was added to cells which had been grown with ammonia, derepression of the nitrogen fixation genes (nifhd) was inhibited at an ethanol concentration of 1 mm. on the other hand, when cells had nitrogenase-catalyzed proton-reducing activity prior to ethanol addition, reduction of the nifhd transcript level did not occur after the addition. in cells grown with ... | 1999 | 10077835 |
| ubiquinone binding capacity of the rhodobacter capsulatus cytochrome bc1 complex: effect of diphenylamine, a weak binding qo site inhibitor. | diphenylamine (dpa), a known inhibitor of polyene and isoprene biosynthesis, is shown to inhibit flash-activatable electron transfer in photosynthetic membranes of rhodobacter capsulatus. dpa is specific to the qo site of ubihydroquinone:cytochrome c oxidoreductase, where it inhibits not only reduction of the [2fe-2s]2+ cluster in the fes subunit and subsequent cytochrome c reduction but also heme bl reduction in the cytochrome b subunit. in both cases, the kinetic inhibition constant (ki) is 25 ... | 1999 | 10079091 |
| q-band resonance raman investigation of turnip cytochrome f and rhodobacter capsulatus cytochrome c1. | the results of a comprehensive q-band resonance raman investigation of cytochrome c1 and cytochrome f subunits of bc1 and b6f complexes are presented. q-band excitation provides a particularly effective probe of the local heme environments of these species. the effects of protein conformation (particularly axial ligation) on heme structure and function were further investigated by comparison of spectra obtained from native subunits to those of a site directed c1 mutant (m183l) and various ph-dep ... | 1999 | 10082948 |
| lipopolysaccharides (lps) of oral black-pigmented bacteria induce tumor necrosis factor production by lps-refractory c3h/hej macrophages in a way different from that of salmonella lps. | some lipopolysaccharide (lps) preparations from s- or r-form members of the family enterobacteriaceae and oral black-pigmented bacteria (porphyromonas gingivalis and prevotella intermedia) are known to activate lps-refractory c3h/hej macrophages. when contaminating proteins are removed from r-form lps of enterobacteriaceae by repurification, however, this ability is lost. in the present study, we investigated the capacity of lps from p. gingivalis, p. intermedia, salmonella minnesota, and salmon ... | 1999 | 10085012 |
| re-design of rhodobacter sphaeroides dimethyl sulfoxide reductase. enhancement of adenosine n1-oxide reductase activity. | the periplasmic dmso reductase from rhodobacter sphaeroides f. sp. denitrificans has been expressed in escherichia coli bl21(de3) cells in its mature form and with the r. sphaeroides or e. coli n-terminal signal sequence. whereas the r. sphaeroides signal sequence prevents formation of active enzyme, addition of a 6x his-tag at the n terminus of the mature peptide maximizes production of active enzyme and allows for affinity purification. the recombinant protein contains 1.7-1.9 guanines and gre ... | 1999 | 10085074 |
| crystallization and preliminary x-ray analysis of the rhodobacter capsulatus magnesium chelatase bchi subunit. | the rhodobacter capsulatus bchi protein is one of three subunits of mg chelatase, the enzyme which catalyzes the first committed step of chlorophyll and bacteriochlorophyll biosynthesis. the bchi protein was produced with an inducible t7 rna polymerase expression system in escherichia coli. the protein was purified from the soluble cell-extract fraction and crystallized from polyethylene glycol solution. the crystals diffract to a minimum bragg spacing of 2.1 a. the space group is p63 with unit- ... | 1999 | 10089453 |
| expression and one-step purification of a fully active polyhistidine-tagged cytochrome bc1 complex from rhodobacter sphaeroides. | the fbcb and fbcc genes encoding cytochromes b and c1 of the bc1 complex were extended with a segment to encode a polyhistidine tag linked to their c-terminal sequence allowing a one-step affinity purification of the complex. constructions were made in vitro in a puc-derived background using pcr amplification. the modified fbc operons were transferred to a prk derivative plasmid, and this was used to transform the fbc- strain of rhodobacter sphaeroides, bc17. the transformants showed normal rate ... | 1999 | 10092497 |
| limited role of ceramide in lipopolysaccharide-mediated mitogen-activated protein kinase activation, transcription factor induction, and cytokine release. | the involvement of ceramide in lipopolysaccharide-mediated activation of mouse macrophages was studied. lipopolysaccharide, cell-permeable ceramide analogs, and bacterial sphingomyelinase led to phosphorylation of the extracellular signal-regulated kinases, c-jun nh2-terminal kinases, and p38 kinase and induced ap-1 dna binding in c3h/ouj (lpsn) but not in c3h/hej (lpsd) macrophages. lipopolysaccharide and ceramide mimetics showed distinct kinetics of mitogen-activated protein kinase phosphoryla ... | 1999 | 10092612 |
| the cytochrome bc1 complex from rhodovulum sulfidophilum is a dimer with six quinones per monomer and an additional 6-kda component. | a highly active, large-scale preparation of cytochrome bc1 complex has been obtained from the photosynthetic purple bacterium rhodovulum (rhv.) sulfidophilum. it has been characterized using mass spectrometry, quinone and lipid analysis as well as inhibitor binding. about 35 mg of pure complex can be obtained from 1 g of membrane protein. epr spectroscopy and optical titrations have been used to obtain the redox midpoint potentials of the cofactors. the em-value of 310 mv for the rieske protein ... | 1999 | 10092855 |
| atp-synthase of rhodobacter capsulatus: coupling of proton flow through f0 to reactions in f1 under the atp synthesis and slip conditions. | a stepwise increasing membrane potential was generated in chromatophores of the phototrophic bacterium rhodobacter capsulatus by illumination with short flashes of light. proton transfer through atp-synthase (measured by electrochromic carotenoid bandshift and by ph-indicators) and atp release (measured by luminescence of luciferin-luciferase) were monitored. the ratio between the amount of protons translocated by f0f1 and the atp yield decreased with the flash number from an apparent value of 1 ... | 1999 | 10094498 |
| the presence of adp-ribosylated fe protein of nitrogenase in rhodobacter capsulatus is correlated with cellular nitrogen status. | the photosynthetic bacterium rhodobacter capsulatus has been shown to regulate its nitrogenase by covalent modification via the reversible adp-ribosylation of fe protein in response to darkness or the addition of external nh4+. here we demonstrate the presence of adp-ribosylated fe protein under a variety of steady-state growth conditions. we examined the modification of fe protein and nitrogenase activity under three different growth conditions that establish different levels of cellular nitrog ... | 1999 | 10094674 |
| a light-harvesting antenna protein retains its folded conformation in the absence of protein-lipid and protein-pigment interactions. | the first study by nmr of the integral membrane protein, the bacterial light-harvesting (lh) antenna protein lh1 beta, is reported. the photosynthetic apparatus of purple bacteria contains two different kinds of antenna complexes (lh1 and lh2), which consist of two small integral membrane proteins alpha and beta, each of approximately 6 kda, and bacteriochlorophyll and carotenoid pigments. we have purified the antenna polypeptide lh1 beta from rhodobacter sphaeroides, and have recorded cd spectr ... | 1999 | 10101971 |
| characterization of dorc from rhodobacter capsulatus, a c-type cytochrome involved in electron transfer to dimethyl sulfoxide reductase. | the dorc gene of the dimethyl sulfoxide respiratory (dor) operon of rhodobacter capsulatus encodes a pentaheme c-type cytochrome that is involved in electron transfer from ubiquinol to periplasmic dimethyl sulfoxide reductase. dorc was expressed as a c-terminal fusion to an 8-amino acid flag epitope and was purified from detergent-solubilized membranes by ion exchange chromatography and immunoaffinity chromatography. the dorc protein had a subunit mr = 46,000, and pyridine hemochrome analysis in ... | 1999 | 10187763 |