sequence evidence for strong conservation of the photoactive yellow proteins from the halophilic phototrophic bacteria chromatium salexigens and rhodospirillum salexigens.the photoactive yellow proteins (pyp) have been found to date only in three species of halophilic purple phototrophic bacteria. they have photochemical activity remarkably similar to that of the bacteria rhodopsins. in contrast to rhodopsins, however, the pyps are small water-soluble proteins. we now report the complete amino acid sequences of rhodospirillum salexigens and chromatium salexigens pyp which allow comparison with the known sequence and three-dimensional structure of the prototypic p ...19968611556
cloning of the amphibolic calvin cycle/oppp enzyme d-ribulose-5-phosphate 3-epimerase (ec from spinach chloroplasts: functional and evolutionary aspects.exploiting the differential expression of genes for calvin cycle enzymes in bundle-sheath and mesophyll cells of the c4 plant sorghum bicolor l., we isolated via subtractive hybridization a molecular probe for the calvin cycle enzyme d-ribulose-5-phosphate 3-epimerase (r5p3e)(ec, with the help of which several full-size cdnas were isolated from spinach. functional identity of the encoded mature subunit was shown by r5p3e activity found in affinity-purified glutatione s-transferase fusio ...19958616224
cloning, sequencing and transcriptional regulation of the drat and drag genes of azospirillum lipoferum fs.from azospirillum lipoferum (al) fs, a nitrogen-fixing bacterium isolated from the rhizosphere of rice, we cloned and sequenced drat, encoding dinitrogenase reductase adp-ribosyltransferase, and drag, encoding dinitrogenase reductase-activating glycohydrolase. the nucleotide sequences of dratg showed extensive similarity to the same genes from azospirillum brasilense, rhodospirillum rubrum and rhodobacter capsulatus, and they are assumed to be co-transcribed as a single operon. when this dratg o ...19968621068
kinetic characterization of the hydrolytic activity of the h+-pyrophosphatase of rhodospirillum rubrum in membrane-bound and isolated states.substrate hydrolysis by the h+-pyrophosphatase (pyrophosphate phosphohydrolase, h+-ppase) of the photosynthetic bacterium rhodospirillum rubrum follows a two-pathway reaction scheme in which preformed 1:1 and 1:2 . enzyme . mg2+ complexes (emg and emg2) convert dimagnesium pyrophosphate (the substrate). this scheme is applicable to isolated enzyme, uncoupled chromatophores and chromatophores energized by a k+/valinomycin diffusion potential. tris and other amine buffers exert a specific effect o ...19968617255
characterization of the co-induced, co-tolerant hydrogenase from rhodospirillum rubrum and the gene encoding the large subunit of the the presence of carbon monoxide, the photosynthetic bacterium rhodospirillum rubrum induces expression of proteins which allow the organism to metabolize carbon monoxide in the net reaction co + h2o --> co2 + h2. these proteins include the enzymes carbon monoxide dehydrogenase (codh) and a co-tolerant hydrogenase. in this paper, we present the complete amino acid sequence for the large subunit of this hydrogenase and describe the properties of the crude enzyme in relation to other known hydro ...19968626276
spectroelectrochemical characterization of the metal centers in carbon monoxide dehydrogenase (codh) and nickel-deficient codh from rhodospirillum rubrum.carbon-monoxide dehydrogenase (codh) from rhodospirillum rubrum contains two metal centers: a ni-x-[fe4s4]2+/1+ cluster (c-center) that serves as the cooxidation site and a standard [fe4s4]2+/1+ cluster (b-center) that mediates electron flow from the c-center to external electron acceptors. four states of the c-center were previously identified in electron paramagnetic resonance (epr) and mössbauer studies. in this report, epr-redox titrations demonstrate that the fully oxidized, diamagnetic for ...19968626477
consequences for the organization of reaction center-light harvesting antenna 1 (lh1) core complexes of rhodobacter sphaeroides arising from deletion of amino acid residues from the c terminus of the lh1 alpha polypeptide.the light harvesting antenna 1 (lh1) complex of rhodobacter sphaeroides is intimately associated with the reaction center (rc) as part of the reaction center rc-lh1 core complex. the pufa gene has been modified such that between 5 and 16 amino acid residues were progressively deleted from the c terminus of the lh1 alpha polypeptide. the two largest deletions produced strains which were deficient in lh1. the remaining four deletion mutants exhibited significant reductions in the average level of ...19968621732
interaction of nucleotides with the nad(h)-binding domain of the proton-translocating transhydrogenase of rhodospirillum rubrum.transhydrogenase catalyzes the reduction of nadp+ by nadh coupled to the translocation of protons across a membrane. the polypeptide composition of the enzyme in rhodospirillum rubrum is unique in that the nad(h)-binding domain (called ths) exists as a separate polypeptide. ths was expressed in escherichia coli and purified. the binding of nucleotide substrates and analogues to ths was examined by one-dimensional proton nuclear magnetic resonance (nmr) spectroscopy and by measuring the quenching ...19968626568
presence of a second mechanism for the posttranslational regulation of nitrogenase activity in azospirillum brasilense in response to ammonium.although adp-ribosylation of dinitrogenase reductase plays a significant role in the regulation of nitrogenase activity in azospirillum brasilense, it is not the only mechanism of that regulation. the replacement of an arginine residue at position 101 in the dinitrogenase reductase eliminated this adp-ribosylation and revealed another regulatory system. while the constructed mutants had a low nitrogenase activity, nh4+ still partially inhibited their nitrogenase activity, independent of the dini ...19968631686
purification and characterization of the alternative nitrogenase from the photosynthetic bacterium rhodospirillum rubrum.the alternative nitrogenase from a nifh mutant of the photosynthetic bacterium rhodospirillum rubrum has been purified and characterized. the dinitrogenase protein (anf1) contains three subunits in an apparent alpha2beta2gamma2 structure and contains fe but no mo or v. a factor capable of activating apo-dinitrogenase (lacking the femo cofactor) from azotobacter vinelandii was extracted from the alternative dinitrogenase protein with n-methylformamide. the electron paramagnetic resonance (epr) si ...19968631723
directed mutagenesis of the rhodobacter capsulatus puha gene and orf 214: pleiotropic effects on photosynthetic reaction center and light-harvesting 1 complexes.rhodobacter capsulatus puha mutant strains containing either a nonpolar, translationally in-frame deletion or a polar insertion of an antibiotic resistance cartridge were constructed and evaluated for their photosynthetic growth properties, absorption spectroscopy profiles, and chromatophore protein compositions. both types of mutants were found to be incapable of photosynthetic growth and deficient in the reaction center (rc) and light-harvesting 1 (lh1) complexes. the translationally in-frame ...19968636035
mutation of tyr235 in the nad(h)-binding subunit of the proton-translocating nicotinamide nucleotide transhydrogenase of rhodospirillum rubrum affects the conformational dynamics of a mobile loop and lowers the catalytic activity of the enzyme.the tyr residue in the mobile loop region of the soluble, domain i polypeptide (called ths) of the proton-translocating transhydrogenase from rhodospirillum rubrum has been substituted by asn and by phe. the recombinant proteins were expressed at high levels in escherichia coli and purified to homogeneity. the two well defined resonances at 6.82 and 7.12ppm, observed in the one-dimensional proton nmr spectrum of wild-type protein, and previously attributed to the tyr residue, were absent in both ...19968626569
axial heme ligation in the cytochrome bc1 complexes of mitochondrial and photosynthetic membranes. a near-infrared magnetic circular dichroism and electron paramagnetic resonance study.the combination of epr and low-temperature near-ir magnetic circular dichroism spectroscopies have been used to investigate the axial ligation of the cytochromes in the cytochrome bc1 complexes from bovine heart mitochondria, rhodobacter capsulatus, rhodobacter sphaeroides, and rhodospirillum rubrum, and the purified cytochromes c1 from bovine heart mitochondria, rb. capsulatus and rb. sphaeroides. the possibility of axial ligation of cytochrome c1 by the amino terminus of the polypeptide was al ...19968645697
a role for the epsilon-amino group of lysine-334 of ribulose-1,5-bisphosphate carboxylase in the addition of carbon dioxide to the 2,3-enediol(ate) of ribulose 1,5-bisphosphate.earlier structural and functional studies of ribulose-1,5-bisphosphate carboxylase/oxygenase imply that k334 facilitates the addition of gaseous substrate to the 2,3-enediol(ate) derived from ribulose 1,5-bisphosphate. crystallographic analysis of the activated spinach enzyme [knight et al. (1990) j. mol. biol. 215, 113-160] shows that the lysyl side chain is appropriately positioned to stabilize the transition state for the addition of co2 to the enediol(ate). furthermore, despite total impairm ...19938369274
excitonic interactions in the light-harvesting antenna of photosynthetic purple bacteria and their influence on picosecond absorbance difference spectra.a new model of the light-harvesting antenna (core complex) of purple photosynthetic bacteria is proposed based on excitonic interactions in circular aggregates of bacteriochlorophyll molecules. the calculated absorbance difference spectra of circular aggregates demonstrate all special features observed in the experimental spectra of purple bacteria. in particular, the absorption changes with high amplitude of bleaching at the long-wavelength side of the absorption band at different excitation en ...19938370458
deletion of a b800-850 light-harvesting complex in rhodospirillum molischianum dsm119 leads to "revertants" expressing a b800-820 complex: insights into pigment binding.a b800-850 light-harvesting complex (also called lh2) deficient strain of rhodospirillum molischianum was constructed by replacing a portion of the lh2 gene cluster by a kanamycin resistance gene cartridge. the lh2 deficient strain was characterized spectroscopically and by southern blot analysis. surprisingly, pseudorevertants were obtained which express a b800-820 complex which could not be observed in the wild type. this b800-820 complex was isolated and characterized. it consists of an alpha ...19968639597
the alpha beta dimer-catalytic unit of the f1-atpase. 19958654713
a peptidoglycan binding domain in the porin-associated protein (pap) of rhodospirillum rubrum fr1.the porin-associated protein of rhodospirillum rubrum fr1 was found to contain a peptidoglycan binding motif. a partial fragment of 179 amino acids, obtained by cleavage of pap with trypsin, asp-n protease, and cnbr, was sequenced. substantial sequence homology was found of the c-terminal part (residues 126-179) of porin-associated protein with ompa, the peptidoglycan-associated lipoprotein of several bacteria, protein f of pseudomonas aeruginosa, and piii of neisseria gonorrhoeae, the latter be ...19968674970
high-resolution crystal structures of two polymorphs of cytochrome c' from the purple phototrophic bacterium rhodobacter capsulatus.the structures of two polymorphs of cytochrome c' from rhodobacter capsulatus (rccp) strain m110 have been determined by the molecular replacement method. iron anomalous scattering data were used to confirm the molecular replacement solution. the structures were refined at 1.72 angstrom and 2.0 angstrom resolution to r-values of 15.0% and 16.3%, respectively. the rccp molecule is a dimer and each of the identical 129 residue subunits folds as a four-helical bundle with a covalently bound heme gr ...19968676382
molecular cloning, dna sequence and transcriptional analysis of the rhodospirillum molischianum b800/850 light-harvesting genes.the amino acid sequences of the b800/850 light-harvesting proteins from rhodospirillum molischianum were determined by edman degradation. on the basis of these amino acid sequences, two degenerated oligonucleotides were synthesized and used for pcr of genomic dna. the resulting 150 bp dna fragment was cloned, sequenced and used for subsequent southern blot analysis of digested genomic dna. a 2.3 kbp ecori fragment strongly hybridized to the probe and a size selected genomic library from genomic ...19968695630
rubisco, an old challenge with new perspectives. 19968663895
evidence for a proximal histidine interaction in the structure of cytochromes c in solution: a resonance raman study.soret-excited resonance raman (rr) spectra of oxidized and reduced cytochromes ć from rhodospirillum molischianum and rhodobacter sphaeroides, in solution, are reported. the spectra of the type i ferricytochromes ć in both species contain different extents of two forms. one of these is readily assignable to a "normal" five-coordinated high-spin heme. the second species with v3 and v10 modes at 1502 and 1635 cm-1, respectively, is attributed to a five-coordinated intermediate-spin heme. the rr da ...19968703928
the xanthopsins: a new family of eubacterial blue-light photoreceptors.photoactive yellow protein (pyp) is a photoreceptor that has been isolated from three halophilic phototrophic purple bacteria. the pyp from ectothiorhodospira halophila bn9626 is the only member for which the sequence has been reported at the dna level. here we describe the cloning and sequencing of the genes encoding the pyps from e.halophila sl-1 (type strain) and rhodospirillum salexigens. the latter protein contains, like the e.halophila pyp, the chromophore trans p-coumaric acid, as we show ...19968670821
expression of the puf operon in an aerobic photosynthetic bacterium, roseobacter denitrificans.the effects of oxygen and light on the expression of the puf operon were investigated in roseobacter denitrificans in a comparison with those in rhodobacter sphaeroides. in darkness, the levels of the total puf mrna in ros. denitrificans were about 1.3 times those in rb. sphaeroides at low concentrations of oxygen, reflecting the accumulation of bacteriochlorophyll and carotenoids. the oxygen tension, up to 94% saturation of dissolved oxygen, did not affect the levels of the total puf transcript ...19968665093
identification and sequence of a nifj-like gene in rhodospirillum rubrum: partial characterization of a mutant unaffected in nitrogen fixation.a nifj-like gene was identified in the photosynthetic purple non-sulphur bacterium rhodospirillum rubrum. a dna segment hybridizing to klebsiella pneumoniae nifj was isolated, the gene was inactivated, and a mutant strain, snj-1, was constructed by allele replacement. the mutation was confirmed by dna sequencing. northern blotting and by the lack of pyruvate oxidoreductase activity. this is the first report of a nifj-like gene in photosynthetic bacteria. unexpectedly, snj-1 was capable of nitrog ...19968736535
the crystal structure of the light-harvesting complex ii (b800-850) from rhodospirillum molischianum.the light-harvesting complexes ii (lh-2s) are integral membrane proteins that form ring-like structures, oligomers of alpha beta-heterodimers, in the photosynthetic membranes of purple bacteria. they contain a large number of chromophores organized optimally for light absorption and rapid light energy migration. recently, the structure of the nonameric lh-2 of rhodopseudomonas acidophila has been determined; we report here the crystal structure of the octameric lh-2 from rhodospirillum molischia ...19968736556
rubisco in marine symbiotic dinoflagellates: form ii enzymes in eukaryotic oxygenic phototrophs encoded by a nuclear multigene family.genes encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) were cloned from dinoflagellate symbionts (symbiodinium spp) of the giant clam tridacna gigas and characterized. strikingly, symbiodinium rubisco is completely different from other eukaryotic (form i) rubiscos: it is a form ii enzyme that is approximately 65% identical to rubisco from rhodospirillum rubrum (rubisco forms i and ii are approximately 25 to 30% identical); it is nuclear encoded by a multigene family; and the pr ...19968721755
the binding of nucleotides to domain i proteins of the proton-translocating transhydrogenases from rhodospirillum rubrum and escherichia coli as measured by equilibrium dialysis.transhydrogenase catalyses the transfer of reducing equivalents between nad(h) and nadp(h) coupled to the translocation of protons across a membrane. the nad(h)-binding domain of transhydrogenase (domain i protein) from rhodospirillum rubrum and from escherichia coli were overexpressed and purified. nucleotide binding to the domain i proteins was determined by equilibrium dialysis. nadh and its analogue, acetylpyridine adenine dinucleotide (reduced form), bound with relatively high affinity (kd ...19968774721
light-harvesting mechanisms in purple photosynthetic bacteria.the processes by which photosynthetic bacteria capture light and transfer the energy to the reaction centre continue to be studied using an array of methodologies, both physical and biological. with the publication this year of the crystal structure of the lh2 complex from rhodopseudomonas acidophila and the projection structure of the lh1 complex from rhodospirillum rubrum, structural models now exist for all the components in the bacterial photosynthetic apparatus.19958749368
a perturbed two-level model for exciton trapping in small photosynthetic systems.the study of exciton trapping in photosynthetic systems provides significant information about migration kinetics within the light harvesting antenna (lha) and the reaction center (rc). we discuss two random walk models for systems with weakly coupled pigments, with a focus on the application to small systems (10-40 pigments/rc). details of the exciton transfer to and from the rc are taken into consideration, as well as migration within the lha and quenching in the rc. the first model is obtaine ...19968789084
posttranslational regulation of nitrogenase activity by fixed nitrogen in azotobacter chroococcum.using anti-(fe protein) antibody raised against the fe protein of the photosynthetic bacterium rhodospirillum rubrum, it was found that the fe protein component of nitrogenase (ec from azotobacter chroococcum cells subjected to an ammonium shock, and hence with an inactive nitrogenase, appeared as a doublet in western blot analysis of cell extracts. the fe protein incorporated [32p]phosphate and [3h]adenine in response to ammonium treatment, and l-methionine-dl-sulfoximine, an inhibito ...19968781527
formation of the light-harvesting complex i (b870) of anoxygenic phototrophic purple bacteria.the light-harvesting (lh) complex i (b870) of anoxygenic photosynthetic purple bacteria is the oligomeric form of its subunit b820 consisting of the low-molecular-weight polypeptides alpha, beta, bacteriochlorophyll (bchl), and carotenoids in the stoichiometric ratio [alpha1 beta1 (bchl2) crt1-2]n. lhi surrounds the photochemical reaction center (rc). the major absorption band of the lhi complex is species-specific and is found at 870-890 nm; those of the subunit and the monomeric bchl a (dissol ...19968703191
comparison of the hydrolysis of zn-ppi2- and the mgppi2- as substrates and the effect of free cations upon membrane-bound pyrophosphatase of rhodospirillum rubrum.the hydrolytic activity of chromatophore membrane-bound pyrophosphatase with zn-ppi2- as substrate was studied and compared with mg-ppi2- hydrolysis. the ph profile of zn-ppi2- hydrolysis is a bell shaped curve with an optimum at 5.25. this behavior is different from the sigmoidal profile obtained for mg-ppi2- hydrolysis, which has a plateau from ph 6.5 to 9.0. zn-ppi2- hydrolytic activity is inhibited by 1-butanol and methylene-diphosphate but not by naf. the enzyme has no activity when free zn ...19958834776
the effects of decyl aurachins c and d on the respiratory electron flow of facultative phototrophic bacteria.decyl aurachins c and d are two synthetic compounds related to the natural products aurachins c and d extracted from stigmatella aurantiaca. titrations of a range of partial respiratory activities in membranes from facultative phototrophs indicate that decyl aurachin c is more effective than aurachin d in inhibiting the quinol oxidase. decyl aurachin c also affects the nadh-ubiquinone oxidoreductase of rhodobacter capsulatus and the cytochrome bc1 complexes of rb.capsulatus and rhodospirillum ce ...19968843334
transcription of the glnb and glna genes in the photosynthetic bacterium rhodospirillum rubrum.the pii protein, encoded by glnb, has a central role in the control of nitrogen metabolism in nitrogen-fixing prokaryotes. the glnb gene of rhodospirillum rubrum was isolated and sequenced. the deduced amino acid sequence had very high sequence identity to other pii proteins. the glna gene, encoding glutamine synthetase, was located 135 bp downstream of glnb and was partially sequenced. glnb is cotranscribed with glna from a promoter with high similarity to the sigma 54-dependent promoter consen ...19968704966
effect of the pufq-pufb intercistronic region on puf mrna stability in rhodobacter capsulatus.differential expression of genes localized within the polycistronic puf operon of rhodobacter capsulatus is partly due to altered stabilities of individual mrna segments. we show that the 5' untranslated region (utr) of pufb contributes to the unusual longevity of the 0.5 kb light-harvesting (lh) i specific pufba mrna and of the 2.7 kb pufbalmx mrna. three stem-loop structures have been identified within the pufq-pufb intercistronic region by means of rna secondary-structure analysis in vitro an ...19968809769
two-dimensional structure of light harvesting complex ii (lhii) from the purple bacterium rhodovulum sulfidophilum and comparison with lhii from rhodopseudomonas acidophila.within the membranes of photosynthetic bacteria, up to three types of light harvesting complexes (lhi, lhii, lhiii) are found. these complexes absorb photons and transfer the excitation energy to the photosynthetic reaction centre. the lh complexes comprise units that contain alpha and beta polypeptides with associated pigment molecules.19968805531
development of gene transfer methods for rubrivivax gelatinosus s1: construction, characterization and complementation of a puf operon deletion strain.gene transfer systems were developed in rubrivivax (rx.) gelatinosus s1. first, a system for conjugative transfer of mobilizable plasmids from escherichia coli to rx. gelatinosus s1 was established. secondly, optimal conditions for the transformation of rx. gelatinosus s1 by electroporation were determined. a delta puf strain was constructed. complementation with the puf operon from a wild-type strain cloned in a replicative plasmid restored photosynthetic growth. two insertion strains were also ...19968879238
mutants that show increased sensitivity to hydrogen peroxide reveal an important role for the pentose phosphate pathway in protection of yeast against oxidative stress.we have isolated several mutants of saccharomyces cerevisiae that are sensitive to oxidative stress in a screen for elevated sensitivity to hydrogen peroxide. two of the sixteen complementation groups obtained correspond to structural genes encoding enzymes of the pentose phosphate pathway. allelism of the pos10 mutation (pos for peroxide sensitivity) to the zwf1/met1 mutants in the structural gene for glucose 6-phosphate dehydrogenase was reported previously. the second mutation, pos18, was com ...19968879247
biological electron transfer.many oxidoreductases are constructed from (a) local sites of strongly coupled substrate-redox cofactor partners participating in exchange of electron pairs, (b) electron pair/single electron transducing redox centers, and (c) nonadiabatic, long-distance, single-electron tunneling between weakly coupled redox centers. the latter is the subject of an expanding experimental program that seeks to manipulate, test, and apply the parameters of theory. new results from the photosynthetic reaction cente ...19958847340
characterization of the region encoding the co-induced hydrogenase of rhodospirillum the photosynthetic bacterium rhodospirillum rubrum, the presence of carbon monoxide (co) induces expression of several proteins. these include carbon monoxide dehydrogenase (codh) and a co-tolerant hydrogenase. together these enzymes catalyze the following conversion: co + h2o --> co2 + h2. this system enables r. rubrum to grow in the dark on co as the sole energy source. expression of this system has been shown previously to be regulated at the transcriptional level by co. we have now identi ...19968892819
a novel heme protein that acts as a carbon monoxide-dependent transcriptional activator in rhodospirillum rubrum.the gene coding for a carbon monoxide-dependent transcriptional activator (cooa) in rhodospirillum rubrum has been expressed in e. coli, and the recombinant cooa has been purified. cooa contains b-type heme which may act as a co sensor in vivo. co-bound cooa was formed when reduced cooa was reacted with co, but not in the case of oxidized cooa. cooa is the first example of the heme protein acting as a dna-binding transcriptional activator.19968941349
melatonin immunoreactivity in the photosynthetic prokaryote rhodospirillum rubrum: implications for an ancient antioxidant system.rhodospirillum rubrum is a spiral anoxygenic photosynthetic bacterium that can exist under either aerobic or anaerobic conditions. the organism thrives in the presence of light or complete darkness and represents one of the oldest species of living organisms, possibly 2-3.5 billion years old. the success of this prokaryotic species may be attributed to the evolution of certain indole compounds that offer protection against life-threatening oxygen radicals produced by an evolutionary harsh enviro ...19958867786
properties of the purified, recombinant, nadp(h)-binding domain iii of the proton-translocating nicotinamide nucleotide transhydrogenase from rhodospirillum rubrum.transhydrogenase comprises three domains. domains i and iii are peripheral to the membrane and possess the nad(h)- and nadp(h)-binding sites, respectively, and domain ii spans the membrane. domain iii of transhydrogenase from rhodospirillum rubrum was expressed at high levels in escherichia coli, and purified. the purified protein was associated with substoichiometric quantities of tightly bound nadp+ and nadph. fluorescence spectra of the domain iii protein revealed emissions due to tyr residue ...19968898902
a global two component signal transduction system that integrates the control of photosynthesis, carbon dioxide assimilation, and nitrogen fixation.photosynthesis, biological nitrogen fixation, and carbon dioxide assimilation are three fundamental biological processes catalyzed by photosynthetic bacteria. in the present study, it is shown that mutant strains of the nonsulfur purple photosynthetic bacteria rhodospirillum rubrum and rhodobacter sphaeroides, containing a blockage in the primary co2 assimilatory pathway, derepress the synthesis of components of the nitrogen fixation enzyme complex and abrogate normal control mechanisms. the abs ...19968962083
control of nitrogen fixation by oxygen in purple nonsulfur bacteriasome members of the facultatively phototrophic bacteria are able to grow diazotrophically in the presence of oxygen. as in other diazotrophs, the nitrogenase of the phototrophic bacteria is highly sensitive to oxygen; therefore, both the function and the expression of nitrogenase are strictly controlled by oxygen. this review focuses on the different levels of oxygen control in the two most extensively studied facultatively phototrophic bacteria, rhodospirillum rubrum and rhodobacter capsulatus. ...19968952942
facilitation of the terminal proton transfer reaction of ribulose 1,5-bisphosphate carboxylase/oxygenase by active-site lys166.the terminal step in the carboxylation pathway catalyzed by ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) is stereospecific protonation of the c-2 aci-acid of 3-phosphoglycerate (pga). x-ray crystallographic results favor the epsilon-amino group of lys166 as the proton donor in this step [knight et al. (1990) j. mol. biol. 215, 113]. nonetheless, position-166 mutants are able to catalyze forward processing of isolated 2-carboxy-3-ketoarabinitol 1,5-bisphosphate (ckabp), the carboxyla ...19968909282
unleashing hydrogenase activity in carbon monoxide dehydrogenase/acetyl-coa synthase and pyruvate:ferredoxin oxidoreductase.these results demonstrate that two well-studied metalloenzymes, carbon monoxide dehydrogenase/acetyl-coa synthase (codh/acs) and pyruvate:ferredoxin oxidoreductase (pfor), can reduce protons to h2 and, at much lower rates, oxidize h2 to protons and electrons. to our knowledge, this if the first time that pfor has been shown to have hydrogenase activity. codh/acs and pfor evolved h2 at maximum rates when co and pyruvate were the electron donors, respectively, and when electron acceptors are absen ...19968961945
a 3-hydroxy-3-methylglutaryl-coa lyase gene in the photosynthetic bacterium rhodospirillum rubrum.a 1.2 kb long dna segment from rhodospirillum rubrum has been sequenced (embl/genbank accession number: u41280). this dna segment includes the first sequenced gene for a putative 3-hydroxy-3-methylglutaryl-coa (hmg-coa) lyase, termed hmgl, from a photosynthetic organism. the sequenced segment also contains a ribosome-binding site and two clusters of possible-35 and -10 promotor sequences preceding the hmgl gene. translation of the gene would yield a 303 amino-acid-long protein with a calculated ...19979003443
high cyclic transhydrogenase activity catalyzed by expressed and reconstituted nucleotide-binding domains of rhodospirillum rubrum transhydrogenase.the hydrophilic, extramembranous domains i (alpha 1 subunit) and iii of the rhodospirillum rubrum nicotinamide nucleotide transhydrogenase were expressed in escherichia coli and purified therefrom as soluble proteins. these domains bind nad(h) and nadp(h). respectively, and together they form the enzyme's catalytic site. we have demonstrated recently that the isolated domains i and iii of the bovine transhydrogenase (or domain i of r. rubrum plus domain iii of the bovine enzyme) reconstitute to ...19979030266
quinolones and their n-oxides as inhibitors of mitochondrial complexes i and iii.4(1h)-quinolones (2-alkyl- (1), 2-alkyl-3-methyl- (2), 2-methyl-3-alkyl- (3), 1-hydroxy-2-methyl-3-alkyl- (4) and 1-hydroxy-2-alkyl- (5)) with n-alkyl side chains varying from c5 to c17 have been synthesized and tested for biological activity in mitochondrial complexes. whereas all quinolones were efficient inhibitors of electron transport in the cytochrome b/c1-complex from either beef heart or rhodospirillum rubrum, in complex i from beef heart quinolones 1 and 2 only were highly active. in a ...19979030270
the effect of respiration on the phototactic behavior of the purple nonsulfur bacterium rhodospirillum centenumthe effect of respiration on the positive phototactic movement of swarming agar colonies of the facultative phototroph rhodospirillum centenum was studied. when the electron flow was blocked at the bc1 complex level by myxothiazol, the oriented movement of the colonies was totally blocked. conversely, inhibition of respiration via the cytochrome c oxidase stimulated the phototactic response. no phototaxis was observed in a photosynthesis deficient mutant (yb707) lacking bacteriochlorophylls. ana ...19979042748
in vivo nickel insertion into the carbon monoxide dehydrogenase of rhodospirillum rubrum: molecular and physiological characterization of cooctj.the products of cooctj are involved in normal in vivo ni insertion into the carbon monoxide dehydrogenase (codh) of rhodospirillum rubrum. located on a 1.5-kb dna segment immediately downstream of the codh structural gene (coos), two of the genes encode proteins that bear motifs reminiscent of other (urease and hydrogenase) ni-insertion systems: a nucleoside triphosphate-binding motif near the n terminus of cooc and a run of 15 histidine residues regularly spaced over the last 30 amino acids of ...19979079911
two-dimensional crystallization of the light-harvesting i-reaction centre photounit from rhodospirillum rubrum.a stoichiometric unit of the light-harvesting complex i and the reaction centre (lhi-rc complex) has been isolated from a carotenoid-less mutant of the purple non-sulphur bacterium rhodospirillum rubrum by mild solubilization of photosynthetic membranes with the phospholipid detergent diheptylphosphatidylcholine. dialysis of the isolated lhi-rc complexes in the presence of added dioleoyl-sn-phosphatidylcholine produced ordered two-dimensional crystals. digital image processing revealed that the ...19979020974
role of isoleucine-164 at the active site of rubisco from rhodospirillum rubrum.isoleucine-164 is in van der waals contact with two ligands (lysine-191 and aspartate-193) of the activator magnesium ion at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum. to observe the effect of mutations in the second sphere of coordination of the metal ion, isoleucine-164 was replaced by threonine, asparagine, and aspartate. all the mutant enzymes obtained exhibit a low carboxylase activity. ile164asp has less than 0.1% of the wild-type carboxy ...19979125206
evaluation of structure-function relationships in the core light-harvesting complex of photosynthetic bacteria by reconstitution with mutant mutant lh1 polypeptides of rhodobactor sphaeroides have been isolated, and their behaviors in in vitro reconstitution of lh1 and its subunit complex have been characterized. two mutants were selected to address the increased stability of the subunit complex of rb. sphaeroides compared with that of rhodobacter capsulatus. we found that this difference can be largely ascribed to the existence of tyr at position +4 in the beta-polypeptide (the numbering system used assigns position 0 to the h ...19979132020
functions of conserved tryptophan residues of the core light-harvesting complex of rhodobacter sphaeroides.we have examined mutants in the core light-harvesting complex of rhodobacter sphaeroides in which the tryptophan residues located at positions alpha+11, beta+6, and beta+9 have been mutated to each of the three other aromatic amino acids, namely tyrosine, phenylalanine, and histidine. we confirm that the alpha+11 residue and show that the beta+9 residue each form a hydrogen bond to a c2-acetyl group of a bchl molecule. mutation of either of these residues to a phenylalanine results in a breakage ...19979062104
influence of asn/his l166 on the hydrogen-bonding pattern and redox potential of the primary donor of purple bacterial reaction centers.the primary electron donor (p) of the photosynthetic reaction center (rc) from the purple bacterium rhodobacter (rb.) sphaeroides is constituted of two bacteriochlorophyll molecules in excitonic interaction. the c2 acetyl carbonyl group of one of the two bacteriochlorophyll molecules (pl), the one more closely associated with the l polypeptide subunit, is engaged in a hydrogen bond with histidine l168, while the other pi-conjugated carbonyl groups of p are free from such hydrogen-bonding interac ...19979062134
nad-dependent cross-linking of dinitrogenase reductase and dinitrogenase reductase adp-ribosyltransferase from rhodospirillum rubrum.chemical cross-linking of dinitrogenase reductase and dinitrogenase reductase adp-ribosyltransferase (drat) from rhodospirillum rubrum has been investigated with a cross-linking system utilizing two reagents, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and sulfo-n-hydroxysuccinimide. cross-linking between dinitrogenase reductase and drat requires the presence of nad, the cellular adp-ribose donor, or a nad analog containing an unmodified nicotinamide group, such as nicotinamide hypoxanthine d ...19979150224
composition and primary structure of the f1f0 atp synthase from the obligately anaerobic bacterium clostridium thermoaceticum.the subunit composition and primary structure of the proton-translocating f1f0 atp synthase have been determined in clostridium thermoaceticum. the isolated enzyme has a subunit composition identical to that of the f1f0 atp synthase purified from clostridium thermoautotrophicum (a. das, d. m. ivey, and l. g. ljungdahl, j. bacteriol. 179:1714-1720, 1997), both having six different polypeptides. the molecular masses of the six subunits were 60, 50, 32, 17, 19, and 8 kda, and they were identified a ...19979171425
spectroscopy and structure of bacteriochlorophyll dimers. i. structural consequences of nonconservative circular dichroism spectra.the origin of the nonconservative nature of the circular dichroism (cd) spectrum of bacteriochlorophyll dimers is investigated. it is shown that coupling between the qy and qx transitions can, under rather restricting circumstances, lead to an asymmetrical cd spectrum: only for a limited set of relative orientations of the monomers within the dimer is the spectrum found to be asymmetrical. the relation between intensity and asymmetry of the cd spectrum is elucidated. the results are applied to t ...19979083687
the reduction of acetylpyridine adenine dinucleotide by nadh: is it a significant reaction of proton-translocating transhydrogenase, or an artefact?transhydrogenase is a proton pump. it has separate binding sites for nad+/nadh (on domain i of the protein) and for nadp+/nadph (on domain iii). purified, detergent-dispersed transhydrogenase from escherichia coli catalyses the reduction of the nad+ analogue, acetylpyridine adenine dinucleotide (acpdad+), by nadh at a slow rate in the absence of added nadp+ or nadph. although it is slow, this reaction is surprising, since transhydrogenase is generally thought to catalyse hydride transfer between ...19979186780
the effect of respiration on the phototactic behavior of the purple nonsulfur bacterium rhodospirillum centenum.the effect of respiration on the positive phototactic movement of swarming agar colonies of the facultative phototroph rhodospirillum centenum was studied. when the electron flow was blocked at the bc1 complex level by myxothiazol, the oriented movement of the colonies was totally blocked. conversely, inhibition of respiration via the cytochrome c oxidase stimulated the phototactic response. no phototaxis was observed in a photosynthesis deficient mutant (yb707) lacking bacteriochlorophylls. ana ...19979133331
uridylylation of the p(ii) protein in the photosynthetic bacterium rhodospirillum rubrum.the regulatory protein p(ii) has been studied in great detail in enteric bacteria; however, its function in photosynthetic bacteria has not been clearly established. as a number of these bacteria have been shown to regulate nitrogenase activity by a metabolic control system, it is of special interest to establish the role of p(ii) in these diazotrophs. in this study, we show that p(ii) in rhodospirillum rubrum is modified in response to the n status in the cell and that addition of ammonium or g ...19979209032
adp-ribosylarginine hydrolases and adp-ribosyltransferases. partners in adp-ribosylation cycles.mono-adp-ribosylation is a reversible modification of arginine residues in proteins, with nad:arginine adp-ribosyltransferases and adp-ribosylarginine hydrolases constituting opposing arms of a putative adp-ribosylation cycle. the enzymatic components of an adp-ribosylation cycle have been identified in both prokaryotic and eukaryotic systems. the regulatory significance of the cycle has been best documented in prokaryotes. as shown by ludden and coworkers, adp-ribosylation controls the activity ...19979193633
rhodospira trueperi gen. nov., spec. nov., a new phototrophic proteobacterium of the alpha group.a new phototrophic purple bacterium was isolated from a flat, laminated microbial mat in a salt marsh near woods hole, mass., usa. the spiral-shaped bacterium was highly motile and had bipolar tufts of flagella and intracytoplasmic membranes of the vesicular type. the major photosynthetic pigments were identified as the carotenoid tetrahydrospirilloxanthin and bacteriochlorophyll b. the long wavelength in vivo absorption maximum of the bacteriochlorophyll was at 986 nm. the marine bacterium show ...19979211712
mutations at tyrosine-235 in the mobile loop region of domain i protein of transhydrogenase from rhodospirillum rubrum strongly inhibit hydride transfer.transhydrogenase from mitochondrial and bacterial membranes couples proton translocation to hydride transfer between nad(h) and nadp(h). the enzyme has three domains, of which domains i and iii protrude from the membrane. these possess the nad(h)- and nadp(h)-binding sites, respectively, whereas domain ii spans the membrane. in domain i there is a mobile loop which emanates from the surface of the protein, but which closes down upon nad(h) binding. in this report we show that the nadp(h)-depende ...19979230921
regulation of nitrogen fixation in azospirillum brasilense.the regulation of nitrogen fixation in azospirillum brasilense is very complicated, and it responds to exogenous fixed nitrogen or a change of oxygen concentration. this regulation occurs at both transcriptional and posttranslational levels. unlike regulation seen in klebsiella pneumoniae, transcription of nifa does not require ntrb/ntrc in a. brasilense and the expression of nifhdk is controlled by posttranslational regulation of nifa activity. addition of nh4+ or a shift from microaerobic to a ...19979231412
the role of nad+ as a signal during nitrogenase switch-off in rhodospirillum rubrum.the role of nad+ in the metabolic regulation of nitrogenase, the 'switch-off' effect, in rhodospirillum rubrum has been studied. we now show that the decrease in nitrogenase activity upon addition of nad+ to r. rubrum is due to modification of dinitrogenase reductase. there was no effect when nad+ was added to a mutant of r. rubrum devoid of dinitrogenase reductase adp-ribosyltransferase, indicating that nad+ 'switch-off' is an effect of the same regulatory system as ammonium 'switch-off'. we al ...19979148756
the effect of ring currents on carbon chemical shifts in cytochromes.calculations suggest that some carbon chemical shifts in proteins should have large ring current shifts (> 1 ppm). we present 13c, 15n and 1h assignments for cytochrome c2 from rhodospirillum rubrum, compare these with shifts for other cytochromes c, and show that the calculated ring current shifts are similar to experimentally observed shifts, but that there remain substantial conformation-dependent shifts of side-chain carbons. ring current shifts as large as 6 ppm are observed. we show that t ...19979255943
a single mutation in the m-subunit of rhodospirillum rubrum confers herbicide resistance.cells of the photosynthetic bacterium rhodospirillum rubrum were rendered resistant against the inhibitor 2-(1-phenyl)ethylamino-3-propionylamino-4-cyano-thiazole (ppcth). electron transport in reaction centers prepared from one of the mutants (m6) was neither inhibited by ppcth and other nh-thiazoles nor terbutryn. these inhibitors are known to bind at the q(b) site of the l-subunit. compared to the wild type, chromatophores from m6 exhibited strongly altered q(b)- fe2+ and q(a)- fe2+ epr signa ...19979224686
reductive dehalogenation of halocarboxylic acids by the phototrophic genera rhodospirillum and rhodopseudomonas.type strains of the purple nonsulfur species rhodospirillum rubrum, rhodospirillum photometricum, and rhodopseudomonas palustris grew phototrophically on a number of two- and three-carbon halocarboxylic acids in the presence of co2, by reductive dehalogenation and assimilation of the resulting acid. strains of each of these species were able to grow on chloroacetic, 2-bromopropionic, 2-chloropropionic, and 3-chloropropionic acids at a concentration of 2 mm. only r. palustris dsm 123 was able to ...19979251226
structure of the puf operon of the obligately aerobic, bacteriochlorophyll alpha-containing bacterium roseobacter denitrificans och114 and its expression in a rhodobacter capsulatus puf puc deletion mutant.roseobacter denitrificans (erythrobacter species strain och114) synthesizes bacteriochlorophyll a (bchl) and the photosynthetic apparatus only in the presence of oxygen and is unable to carry out primary photosynthetic reactions and to grow photosynthetically under anoxic conditions. the puf operon of r. denitrificans has the same five genes in the same order as in many photosynthetic bacteria, i.e., pufbalmc. pufc, the tetraheme subunit of the reaction center (rc), consists of 352 amino acids ( ...19979286973
antenna excited state decay kinetics establish primary electron transfer in reaction centers as heterogeneous.the decay of the excited primary electron donor p* in bacterial photosynthetic reaction centers (both membrane-bound and detergent-isolated) has been observed to be nonexponential on a time scale of some tens of picoseconds. although the multipicosecond nonexponentiality of p* has been ascribed to heterogeneity in teh rate of primary electron transfer (pet), the decay kinetics can be interpreted equally well using homogeneous models. to address this ambiguity, we studied the decay of excited bac ...19979289013
analysis of a chemotaxis operon from rhodospirillum centenum.a chemotaxis gene cluster from the photosynthetic bacterium rhodospirillum centenum has been cloned, sequenced, and analyzed for the control of transcription during swimmer-to-swarm cell differentiation. the first gene of the operon (cheay) codes for a large 108-kda polypeptide with an amino-terminal domain that is homologous to chea and a carboxyl terminus that is homologous to chey. cheay is followed by chew, an additional homolog of chey, cheb, and cher. sequence analysis indicated that all o ...19979294426
chemosensory and photosensory perception in purple photosynthetic bacteria utilize common signal transduction components.the chemotaxis gene cluster from the photosynthetic bacterium rhodospirillum centenum contains five open reading frames (orfs) that have significant sequence homology to chemotaxis genes from other bacteria. to elucidate the functions of each orf, we have made various mutations in the gene cluster and analyzed their phenotypic defects. deletion of the entire che operon (delta che), as well as nonpolar disruptions of cheay, chew, and cher, resulted in a smooth-swimming phenotype, whereas disrupti ...19979294427
the electron transport system of the halophilic purple nonsulfur bacterium rhodospirillum salinarum. 1. a functional and thermodynamic analysis of the respiratory chain in aerobically and photosynthetically grown cells.plasma membranes isolated from cells of the halophilic purple nonsulfur bacterium rhodospirillum salinarum grown in light or in the dark were examined. membranes isolated from cells grown aerobically in the dark contained three b-type and two c-type membrane-bound cytochromes with em,7 of +180, +72 and -5 mv (561-575 nm), and +244 and +27 mv (551-540 nm), respectively. conversely, membranes isolated from cells grown anaerobically in the light contained two b-type and five c-type haems with em,7 ...19979297468
cooa, a co-sensing transcription factor from rhodospirillum rubrum, is a co-binding heme protein.biological sensing of small molecules such as no, o2, and co is an important area of research; however, little is know about how co is sensed biologically. the photosynthetic bacterium rhodospirillum rubrum responds to co by activating transcription of two operons that encode a co-oxidizing system. a protein, cooa, has been identified as necessary for this response. cooa is a member of a family of transcriptional regulators similar to the camp receptor protein and fumavate nitrate reduction from ...19979326589
effect of hydration on the structure, dynamics and function of photosynthetic membranes of purple bacteria.nmr spectra and relaxation times t1 and t2 for 31p in membranes of rhodobacter sphaeroides were investigated at different relative humidity levels. the results are compared to the hydration curves, fatty acid composition and the structure-dynamic and functional characteristics of the membranes of photosynthetic bacteria rb. sphaeroides, rhodospirillum rubrum and ectothiorhodospira shaposhnikovii. the differences in the state of lipid phase of these membranes are revealed under low humidity, and ...19979257278
evidence that the transfer of hydride ion equivalents between nucleotides by proton-translocating transhydrogenase is direct.the molecular masses of the purified, recombinant nucleotide-binding domains (domains i and iii) of transhydrogenase from rhodospirillum rubrum were determined by electrospray mass spectrometry. the values obtained, 40,273 and 21,469 da, for domains i and iii, respectively, are similar to those estimated from the amino acid sequences of the proteins. evidently, there are no prosthetic groups or metal centers that can serve as reducible intermediates in hydride transfer between nucleotides bound ...19979346886
energy migration in the light-harvesting antenna of the photosynthetic bacterium rhodospirillum rubrum studied by time-resolved excitation annihilation at 77 k.the intensity dependence of picosecond kinetics in the light-harvesting antenna of the photosynthetic bacterium rhodospirillum rubrum is studied at 77 k. by changing either the average excitation intensity or the pulse intensity we have been able to discriminate singlet-singlet and singlet-triplet annihilation. it is shown that the kinetics of both annihilation types are well characterized by the concept of percolative excitation dynamics leading to the time-dependent annihilation rates. the tim ...19969172762
distinct actions of cis and trans atp within the double ring of the chaperonin groel.the chaperonin groel is a double-ring structure with a central cavity in each ring that provides an environment for the efficient folding of proteins when capped by the co-chaperone groes in the presence of adenine nucleotides. productive folding of the substrate rhodanese has been observed in cis ternary complexes, where groes and polypeptide are bound to the same ring, formed with either atp, adp or non-hydrolysable atp analogues, suggesting that the specific requirement for atp is confined to ...19979285593
autofluorescence of live purple bacteria in the near infrared.we have developed a novel microscope with which to study the fluorescence of cells in the near-infrared region (lambda = 750-2500 nm). for one of its first applications we report on the autofluorescence of live purple bacteria, rhodospirillum rubrum, and suggest that the autofluorescent component is bacteriochlorophyll. the rapid fading of the autofluorescence of fixed bacteria and of purified bacteriochlorophyll suggests that the live bacteria are able to regenerate their pigment with a time co ...19979344583
role of methionine-239, an amino acid residue in the mobile-loop region of the nadh-binding domain (domain i) of proton-translocating transhydrogenase.transhydrogenase couples the transfer of hydride equivalents between nad(h) and nadp(h) to proton translocation across a membrane. the one-dimensional proton nmr spectrum of the recombinant nad(h)-binding domain (domain i) of transhydrogenase from rhodospirillum rubrum reveals well-defined resonances, several of which arise from a mobile loop at the protein surface. four have been assigned to met residues (meta-metd). substitution of met239 with either ile (di.m239i) or phe (di.m239f) resulted i ...19979398196
site-directed modification of the ligands to the bacteriochlorophylls of the light-harvesting lh1 and lh2 complexes of rhodobacter sphaeroides.the core light-harvesting lh1 complex of rhodobactersphaeroides consists of an assembly of membrane-spanning alpha and beta polypeptides, each of which binds one bacteriochlorophyll molecule. in this study we have used site-directed mutagenesis to demonstrate that the b880 bacteriochlorophyll binding site of lh1 shows a high degree of specificity for the residue that provides the ligand to the bchl mg2+ ion. alpha his0 (alphah0) was changed to asn, leu, and tyr, and beta his0 (betah0) to asn, gl ...19979376369
the ph dependences of reactions catalyzed by the complete proton-translocating transhydrogenase from rhodospirillum rubrum, and by the complex formed from its recombinant nucleotide-binding domains.transhydrogenase couples the translocation of protons across a membrane to the transfer of reducing equivalents between nad(h) and nadp(h). using transhydrogenase from rhodospirillum rubrum we have examined the ph dependences of the 'forward' and 'reverse' reactions, and of the 'cyclic' reaction (nadp(h)-dependent reduction of the analogue, acetyl pyridine adenine dinucleotide, by nadh). in the case of the membrane-bound protein in chromatophores, the imposition of a protonmotive force through t ...19979398076
cloning and sequencing of dratg genes and their downstream region of azospirillum brasilense 8-kb fragment was cloned by probing the gene library of azospirillum brasilense yu62 with the 4.0-kb dratg fragment of a. brasilense sp7. dna hybridization of this fragment demonstrated that dratg genes were located in a 3.0-kb ecor i-kpn i fragment, and were contiguous to the nifh gene. this 3.0-kb fragment was completely sequenced on both strands. sequence analysis of the fragment revealed that it included the full-length dratg genes and two orfs downstream of drag (orf3 and incomplete orf4 ...19979429775
demonstration of the key role played by the pufx protein in the functional and structural organization of native and hybrid bacterial photosynthetic core complexes.the role of a component of the bacterial photosystem, the pufx protein, was examined by heterologous expression of the pufx gene from rhodobacter capsulatus in a strain of r. sphaeroides that lacks the native pufx gene. the strain of r. sphaeroides containing the r. capsulatus pufx protein was capable of efficient transduction of light energy despite a low degree of sequence conservation between the pufx proteins from the two species. the organization of the hybrid reaction center/lh1 photosyste ...19989457869
single transduction in the transcriptional activator cooa containing a heme-based co sensor: isolation of a dominant positive mutant which is active as the transcriptional activator even in the absence of co.we constructed an in vivo reporter system to measure the activity of cooa as the transcriptional activator and showed that the recombinant cooa was active as the transcriptional activator in the presence of co even in e. coli cells. a dominant positive mutant of cooa, in which met131 was replaced by leu, was isolated by a random mutagenesis with this reporter system. the electronic absorption spectra of m131l mutant were identical to those of wild type cooa in oxidized (fe3+), reduced (fe2+), an ...19979398645
dinitrogenase reductase-activating glycohydrolase can be released from chromatophores of rhodospirillum rubrum by treatment with mggdp.dinitrogenase reductase-activating glycohydrolase (drag), involved in the regulation of nitrogenase activity in rhodospirillum rubrum, is associated with chromatophore membranes in cell extracts. we show that drag can be specifically released by treatment with mggdp; other nucleotides studied had no effect. the drag activity released corresponds to the release of drag protein.19979401050
substitution of valine for histidine 265 in carbon monoxide dehydrogenase from rhodospirillum rubrum affects activity and spectroscopic carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum, histidine 265 was replaced with valine by site-directed mutagenesis of the coos gene. the altered form of codh (h265v) had a low nickel content and a dramatically reduced level of catalytic activity. although treatment with nicl2 and cocl2 increased the activity of h265v codh by severalfold, activity levels remained more than 1000-fold lower than that of wild-type codh. histidine 265 was not essential for the formation and stabi ...19989461598
isolation of rhodospirillum centenum mutants defective in phototactic colony motility by transposon mutagenesis.the purple photosynthetic bacterium rhodospirillum centenum is capable of forming swarm colonies that rapidly migrate toward or away from light, depending on the wavelength of excitation. to identify components specific for photoperception, we conducted mini-tn5-mediated mutagenesis and screened approximately 23,000 transposition events for mutants that failed to respond to either continuous illumination or to a step down in light intensity. a majority of the ca. 250 mutants identified lost the ...19989495765
photoresponses of the purple nonsulfur bacteria rhodospirillum centenum and rhodobacter sphaeroides.we have measured the photoresponse of two purple nonsulfur bacteria, rhodobacter sphaeroides and rhodospirillum centenum, under defined conditions in a light beam propagating at 90 degrees to the optical axis of the microscope. this beam presented cells with a steep gradient of intensity perpendicular to the direction of propagation and a shallow gradient in the direction of light propagation. r. centenum, a species that reverses to change direction, accumulated in the light beam, as expected fo ...19979352928
reconstitution of core light-harvesting complexes of photosynthetic bacteria using chemically synthesized polypeptides. 2. determination of structural features that stabilize complex formation and their implications for the structure of the subunit complex.chemically synthesized polypeptides have been utilized with a reconstitution assay to determine the role of specific amino acid side chains in stabilizing the core light-harvesting complex (lh1) of photosynthetic bacteria and its subunit complex. in the preceding paper [meadows, k. a., parkes-loach, p. s., kehoe, j. w., and loach, p. a. (1998) biochemistry 37, 3411-3417], it was demonstrated that 31-residue polypeptides (compared to 48 and 54 amino acids in the native polypeptides) having the sa ...19989521663
the rieske protein from purple sulfur bacteria is an extrinsic protein.the mode of membrane attachment of the rieske iron-sulfur protein from cytochrome bc1 complex of rhodospirillum rubrum has been studied using biochemical approaches. in contrast to cytochrome c1 the bacterial rieske protein was extracted from chromatophores using chaotropic agents (nascn, urea, guanidine), an alkaline ph and relatively low concentration of triton x-100. the results presented here lead to the conclusion, that the rieske protein from chromatophores is extrinsic and that their asso ...19989528121
reconstitution of core light-harvesting complexes of photosynthetic bacteria using chemically synthesized polypeptides. 1. minimal requirements for subunit formation.described are the chemical synthesis, isolation and characterization of each of three polypeptides whose amino acid sequences reproduce portions of the amino acid sequence of the beta-polypeptides of the core light-harvesting complex (lh1) of rhodobacter sphaeroides or rhodospirillum rubrum. the native beta-polypeptides of lh1 of these organisms contain 48 and 54 amino acids, respectively. the smallest synthetic polypeptide had an amino acid sequence identical to that of the last 16 amino acids ...19989521662
cloning and sequencing of a form ii ribulose-1,5-biphosphate carboxylase/oxygenase from the bacterial symbiont of the hydrothermal vent tubeworm riftia pachyptila.the bacterial symbiont of the hydrothermal vent tubeworm fixes carbon via the calvin-benson cycle and has been shown previously to express a form ii ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). the gene cbbm, which encodes this enzyme, has been cloned and sequenced. the gene has the highest identity with the cbbm gene from rhodospirillum rubrum, and analysis of the inferred amino acid sequence reveals that all active-site residues are conserved. this is the first form ii rubisco cl ...19989515935
transmembrane helix stability: the effect of helix-helix interactions studied by fourier transform infrared spectroscopy.we have measured, using infrared spectroscopy, the hydrogen/deuterium exchange rates of the amide protons in the photosynthetic antenna of rhodospirillum rubrum. these measurements were made not only on the intact protein in detergent solution but also on two dissociated forms (b820 and b777). we have, on the basis of our knowledge of the structure of this protein, been able to assign the various groups of amide protons that exchange with different time constants to distinct regions of the prote ...19989533710
the identification, purification, and characterization of cooj. a nickel-binding protein that is co-regulated with the ni-containing co dehydrogenase from rhodospirillum rubrum.cooj, a nickel-binding protein from the co dehydrogenase system of rhodospirillum rubrum, was purified by immobilized metal affinity chromatography. cooj is a co-induced protein predicted to contain a nickel binding motif composed of 16 histidine residues in the final 34 amino acids of the 12.5-kda protein. when cells grown in the presence of co were fractionated on an immobilized metal affinity chromatography column and analyzed by sds-polyacrylamide gel electrophoresis, the major protein obser ...19989545348
unisite atp hydrolysis by soluble rhodospirillum rubrum f1-atpase is accelerated by ca2+at saturating concentrations of atp, soluble f1 from the rhodospirillum rubrum (rf1) exhibits a higher rate of hydrolysis with ca2+ than with mg2+. the mechanisms involved in the expression of a higher catalytic activity with ca2+ were explored by measuring the atpase activity of rf1 at substiochiometric concentrations of atp (unisite conditions). at a ratio of 0.25 [gamma-32p]atp per rf1, the enzyme exhibited a 50 times higher hydrolytic rate with ca2+ than with mg2+. the rate of [gamma-32p]atp ...19989526049
Displaying items 1401 - 1500 of 2252