PMID(sorted descending)
steric and hydrophobic effects in alkyl isocyanide binding to rhodospirillum molischianum cytochrome c'.equilibrium constants for the binding of a series of alkyl isocyanides to ferrous cytochrome c' from rhodospirillum molischianum have been measured spectrophotometrically. the equilibrium constants range from 3.3 m-1 to 2.6 x 10(2) m-1 and follow the order methyl greater than ethyl less than n-propyl less than tert-butyl less than n-butyl less than amyl less than cyclohexyl less than n-hexyl. the decrease in equilibrium constant from methyl to ethyl isocyanide provides evidence for a steric inte ...19892541775
extended x-ray absorption fine structure study of rhodospirillum rubrum and rhodospirillum molischianum cytochromes c': relationship between heme stereochemistry and spin exafs study on the oxidized and reduced forms of cytochromes c' from rhodospirillum rubrum and rhodospirillum molischianum was performed at ph 7. the cytochromes c' have an apparent coordination number of 5 in both oxidation states. average fe-ligand bond lengths of 2.02 +/- 0.025 and 2.06 +/- 0.025 a are obtained in their oxidized and reduced forms, respectively. by use of suitable values for the fe-nhis bond length and fe out-of-plane displacement, as determined by small molecule crystallog ...19892541757
the effect of equisetin on energy-linked reactions in rhodospirillum rubrum chromatophores.light-induced proton uptake, light-induced carotenoid absorbance shift, photophosphorylation, and hydrolysis of mg-atp, ca-atp, and ppi in rhodospirillum rubrum chromatophores are shown to be inhibited by the antibiotic equisetin. the mg- and ca-atpase activities of purified f0f1-atpase are inhibited by equisetin. in contrast, only the ca-atpase activity of purified f1-atpase is decreased by equisetin, whereas the mg-atpase is stimulated. both equisetin and n,n'-dicyclohexylcarbodiimide (dccd) i ...19892536535
f1-atpase from rhodopseudomonas blastica. 19892535110
amount and turnover rate of the f0f1-atpase and the stoichiometry of its inhibition by oligomycin in rhodospirillum rubrum chromatophores.the amount of f1-atpase in chromatophores from rhodospirillum rubrum was determined by western blotting using anti-rrf1 rabbit antibodies. 9.1 mmol f1 (mol bacteriochlorophyll)-1 was obtained or 14% of the total protein content of the chromatophores. the turnover rate of the f0f1-atpase was 17 molecules atp s-1 during synthesis, 2 molecules atp s-1 during hydrolysis under coupled conditions with mg2+ as the divalent cation, and 7 molecules atp s-1 during hydrolysis in the presence of carbonyl cy ...19892532130
atp-synthesis by proteoliposomes incorporating rhodospirillum rubrum f0f1 as measured with firefly luciferase: dependence on delta psi and delta ph.atp-synthesis catalyzed by proteoliposomes incorporating rhodospirillum rubrum f0f1 was driven by artificially applied electrochemical proton gradients. the time-course of atp-synthesis was followed continuously by means of firefly luciferase. correction methods were developed which allow one to calculate the initial rate of atp-synthesis from the observed luminescence kinetics. the following results were obtained: (1) atp-synthesis occurred above a threshold delta mu h+ of 90 mv; this threshold ...19892528991
ability of the phototrophic bacterium rhodospirillum rubrum to produce various poly (beta-hydroxyalkanoates): potential sources for biodegradable polyesters.studies have been carried out in order to optimize growth and culture conditions for the intracellular formation of poly(beta-hydroxyalkanoates) (pha) in the phototrophic, purple, non-sulphur bacterium rhodospirilum rubrum. its potential to produce novel copolymers was investigated. recently, it has become of industrial interest to evaluate these polyesters as potentially biodegradable plastics for a wide range of possible applications. on an industrial scale, the use of photosynthetic bacteria ...19892518731
functional expression of a rhodospirillum rubrum gene encoding dinitrogenase reductase adp-ribosyltransferase in enteric bacteria.the function of the cloned drat gene of rhodospirillum rubrum was studied by placing it under the control of the tac promoter in the vector, pkk223-3. after induction with isopropyl-beta-d-thiogalactopyranoside, dinitrogenase reductase adp-ribosyltransferase (drat) activity was detected in crude extracts of the heterologous hosts escherichia coli and klebsiella pneumoniae. in addition, the expression of drat produced a nif- phenotype in the otherwise wild-type k. pneumoniae strains, the result o ...19892515993
evolution of antioxidant mechanisms: thiol-dependent peroxidases and thioltransferase among procaryotes.glutathione peroxidase and glutathione s-transferase both utilize glutathione (gsh) to destroy organic hydroperoxides, and these enzymes are thought to serve an antioxidant function in mammalian cells by catalyzing the destruction of lipid hydroperoxides. only two groups of procaryotes, the purple bacteria and the cyanobacteria, produce gsh, and we show in the present work that representatives from these two groups (escherichia coli, beneckea alginolytica, rhodospirillum rubrum, chromatium vinos ...19892515292
protein phosphorylation in purple photosynthetic bacteria.endogenous protein phosphorylation was shown in both in vitro and in vivo experiments in r. rubrum and in other purple photosynthetic bacteria. among the substrates of this protein kinase activity the apoproteins of the light harvesting complex were tentatively identified. phosphoamino acid analysis revealed the presence of phosphoserine, phosphothreonine and phosphotyrosine in r. rubrum. a tyrosine kinase was partially purified in the same bacteria.19892512995
protein phosphorylation and control of excitation energy transfer in photosynthetic purple bacteria and cyanobacteria.the function of phosphorylation of light-harvesting polypeptides is well characterised in chloroplasts of green plants, but the prokaryotic cyanobacteria and purple photosynthetic bacteria have quite different light-harvesting polypeptides whose structure and function cannot be controlled in precisely the same way. nevertheless, cyanobacteria show light-dependent phosphorylation of membrane polypeptides associated with photosystem ii and with the light-harvesting phycobilisome, and purple bacter ...19892512993
coupling of atp hydrolysis to phosphate uptake in rhodospirillum rubrum chromatophores under the influence of ca2+ and mg2+.the pi-atp exchange and atp hydrolytic reactions, by the f0f1 complex, were studied in rhodospirillum rubrum chromatophores in the dark. an optimal ph between 7.0 and 8.5 was determined for the hydrolytic and exchange reactions. under these conditions, the hydrolysis/exchange ratio was approximately 2. the kinetic analysis of the hydrolytic and exchange reactions using mg-atp as substrate showed a change in the hydrolysis/exchange ratio that varied between 2.0 and 2.8 as the substrate concentrat ...19892512287
carbonyl sulfide inhibition of co dehydrogenase from rhodospirillum rubrum.carbonyl sulfide (cos) has been investigated as a rapid-equilibrium inhibitor of co oxidation by the co dehydrogenase purified from rhodospirillum rubrum. the kinetic evidence suggests that the inhibition by cos is largely competitive versus co (ki = 2.3 microm) and uncompetitive versus methylviologen as electron acceptor (ki = 15.8 microm). the data are compatible with a ping-pong mechanism for co oxidation and cos inhibition. unlike the substrate co, cos does not reduce the iron-sulfur centers ...19892510818
genes coding for the reversible adp-ribosylation system of dinitrogenase reductase from rhodospirillum rubrum.nitrogen fixation activity in the photosynthetic bacterium rhodospirillum rubrum is controlled by the reversible adp-ribosylation of the dinitrogenase reductase component of the nitrogenase enzyme complex. this report describes the cloning and characterization of the genes encoding the adp-ribosyltransferase (drat) and the adp-ribosylglycohydrolase (drag) involved in this regulation. these genes are shown to be contiguous on the r. rubrum chromosome and highly linked to the nifhdk genes. sequenc ...19892506427
demonstration and partial characterization of adp-ribosylation in pseudomonas maltophilia.adp-ribosylation of proteins occurs in many eukaryotes, and it is also the mechanism of action of a growing number of important bacterial toxins. to date, however, there is only one well-characterized adp-ribosylation system where the adp-ribosyltransferase and the substrate protein are both bacterial in origin, namely within the nitrogen-fixing bacterium rhodospirillum rubrum. the present paper demonstrates the endogenous adp-ribosylation of two proteins of mr 32,000 and 20,000 within pseudomon ...19892505752
delta ph driven energy-linked nad+ reduction in rhodospirillum rubrum artificial proton gradient provided sufficient energy to drive reverse electron transport from succinate to nadh:ubiquinone oxidoreductase in chromatophores isolated from rhodospirillum rubrum. the ph gradient created was able to reduce nad+. in chromatophores, the optimal rate of nad+ reduction was about 0.4-0.45 mumol nadh formed/min.mumol bacteriochlorophyll at delta ph 3. the presence of oligomycin was an obligate factor in the assay in order to observe the maximal rate of nad+ reduction. ...19892505679
reversible adp-ribosylation of dinitrogenase reductase in a nifd- mutant of rhodospirillum rubrum.dinitrogenase reductase from a rhodospirillum rubrum strain lacking dinitrogenase was reversibly adp-ribosylated in vivo in response to dark-light transitions. addition of ammonia also led to adp-ribosylation in this strain. these results demonstrate that reduced dinitrogenase is a satisfactory substrate for the reversible adp-ribosylation system of r. rubrum in vivo.19892504701
posttranslational regulatory system for nitrogenase activity in azospirillum spp.the mechanism for "nh4+ switch-off/on" of nitrogenase activity in azospirillum brasilense and a. lipoferum was investigated. a correlation was established between the in vivo regulation of nitrogenase activity by nh4cl or glutamine and the reversible covalent modification of dinitrogenase reductase. dinitrogenase reductase adp-ribosyltransferase (drat) activity was detected in extracts of a. brasilense with nad as the donor molecule. dinitrogenase reductase-activating glycohydrolase (drag) activ ...19892504694
nickel-specific, slow-binding inhibition of carbon monoxide dehydrogenase from rhodospirillum rubrum by cyanide.the inhibition of purified carbon monoxide dehydrogenase from rhodospirillum rubrum by cyanide was investigated in both the presence and absence of co and electron acceptor. the inhibition was a time-dependent process exhibiting pseudo-first-order kinetics under both sets of conditions. the true second-order rate constants for inhibition were 72.2 m-1 s-1 with both substrates present and 48.9 and 79.5 m-1 s-1, respectively, for the reduced and oxidized enzymes incubated with cyanide. co partiall ...19892504285
nickel is required for the transfer of electrons from carbon monoxide to the iron-sulfur center(s) of carbon monoxide dehydrogenase from rhodospirillum rubrum.the role of nickel in co oxidation and electron flow was investigated in carbon monoxide dehydrogenase from rhodospirillum rubrum. the fe-s centers of oxidized, nickel-containing (holo) co dehydrogenase were completely reduced within 1 min of exposure to co. the fe-s centers of oxidized, nickel-deficient (apo) co dehydrogenase were not reduced during a 35-min incubation in the presence of co. apo-co dehydrogenase fe-s centers were reduced by dithionite. the fe-s centers of cyanide-inhibited, hol ...19892504284
effect of nucleotides on the activity of dinitrogenase reductase adp-ribosyltransferase from rhodospirillum rubrum.the mechanism by which mgadp stimulates the activity of dinitrogenase reductase adp-ribosyltransferase (drat) has been examined by using dinitrogenase reductases from rhodospirillum rubrum, klebsiella pneumoniae, and azotobacter vinelandii as acceptor substrates. in the presence of 0.2 mm nad, maximal rates of adp-ribosylation of all three acceptors were observed at an adp concentration of 150 microm; in the absence of added adp, drat activity with the dinitrogenase reductases from r. rubrum and ...19892504283
a cyanobacterial mutant requiring the expression of ribulose bisphosphate carboxylase from a photosynthetic anaerobe.ribulose bisphosphate carboxylase is essential for both photoautotrophic and photoheterotrophic growth of the cyanobacterium synechocystis 6803. however, a mutant lacking cyanobacterial carboxylase could be obtained by replacing the natural carboxylase gene with the corresponding gene from rhodospirillum rubrum, a photosynthetic anaerobe. this treatment produced an organism whose growth depended on the activity of the structurally and functionally dissimilar foreign carboxylase. as a further con ...19892503824
examination of subunit interactions at the active site of ribulose 1,5-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum by hybridization of site-directed mutants.the two active sites of homodimeric ribulose bisphosphate carboxylase/oxygenase from rhodospirillum rubrum are constituted by interacting domains of adjacent subunits, in which residues from each are required for catalytic activity. active-site residues include lys-166 of one domain and glu-48 of the interacting domain from the adjacent subunit. whereas all substitutions for lys-166, introduced by site-directed mutagenesis, abolished catalytic activity, only a negatively charged residue (e.g., a ...19892500136
mapping of the puh messenger rnas from rhodospirillum rubrum. evidence for tandem promoters.the mrna transcripts of rhodospirillum rubrum gene puh, coding for the h subunit of the photoreaction center, and of genes flanking puh were analyzed by blot hybridization. open reading frame g115, upstream of structural gene puh, is transcribed as a 2.25-kilobase mrna. gene puh itself is transcribed as two mrnas of 1118 and 1032 nucleotides. mung bean nuclease protection analysis shows that the puh transcripts have different 5' termini within open reading frame g115 and a unique rho-independent ...19892499583
the orientation of substrate and reaction intermediates in the active site of ribulose-1,5-bisphosphate carboxylase.there are four possible orientations of the substrate ribulose 1,5-bisphosphate in the active site of ribulose-1,5-bisphosphate carboxylase. distinction between these four possible orientations has been made on the basis of 31p nmr and borohydride-trapping experiments. the orientation of the reaction-intermediate analog, 2'-carboxy-d-arabinitol 1,5-bisphosphate with respect to the divalent metal ion was determined by 31p nmr studies of the quaternary complex, enzyme.co2.ni2+.2'-carboxyarabinitol ...19892498340
ammonium inhibition of nitrogenase activity in herbaspirillum seropedicae.the effect of oxygen, ammonium ion, and amino acids on nitrogenase activity in the root-associated n2-fixing bacterium herbaspirillum seropedicae was investigated in comparison with azospirillum spp. and rhodospirillum rubrum. h. seropedicae is microaerophilic, and its optimal dissolved oxygen level is from 0.04 to 0.2 kpa for dinitrogen fixation but higher when it is supplied with fixed nitrogen. no nitrogenase activity was detected when the dissolved o2 level corresponded to 4.0 kpa. ammonium, ...19892498287
regulation of carbon monoxide dehydrogenase and hydrogenase in rhodospirillum rubrum: effects of co and oxygen on synthesis and activity.exposure of the photosynthetic bacterium rhodospirillum rubrum to carbon monoxide led to increased carbon monoxide dehydrogenase and hydrogenase activities due to de novo protein synthesis of both enzymes. two-dimensional gels of [35s]methionine-pulse-labeled cells showed that induction of co dehydrogenase synthesis was rapidly initiated (less than 5 min upon exposure to co) and was inhibited by oxygen. both co dehydrogenase and the co-induced hydrogenase were inactivated by oxygen in vivo and i ...19892498285
crystal structure of the binary complex of ribulose-1,5-bisphosphate carboxylase and its product, 3-phospho-d-glycerate.the crystal structure of the binary complex of non-activated ribulose-1,5-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum and its product 3-phospho-d-glycerate has been determined to 2.9-a resolution. this structure determination confirms the proposed location of the active site (schneider, g., lindqvist, y., brändén, c.-i., and lorimer, g. (1986) embo j. 5, 3409-3415) at the carboxyl end of the beta-strands of the alpha/beta-barrel in the carboxyl-terminal domain. one molecule of ...19892492987
carbonyl sulfide: an alternate substrate for but not an activator of ribulose-1,5-bisphosphate carboxylase.carbonyl sulfide, a competitive inhibitor of ribulose-bisphosphate carboxylase with respect to co2 (laing, w. a., and christeller, j. t. (1980) arch. biochem. biophys. 202, 592-600), is an alternate substrate. thiocarboxylation was monitored by mass spectrometry as the stoichiometric consumption of carbonyl sulfide. the product, 1-thio-3-phosphoglycerate, was identified by 13c nmr and uv absorption spectroscopy and measured by enzymic conversion to thiolactate, coupled to the oxidation of nadh. ...19892492523
division of divalent cations into two groups in relation to their effect on the coupling of the f0f1-atpase of rhodospirillum rubrum to the protonmotive force.divalent cations are divided into two groups in relation to their ability to promote atp synthase catalyzed reactions. in the presence of mg2+, the following pattern rules: (i) uncoupler-stimulated atp hydrolysis of rhodospirillum rubrum chromatophores which shows an optimum concentration of the divalent cation; (ii) atp-induced proton pumping in chromatophores; (iii) light-induced atp synthesis in chromatophores; (iv) no or very low atpase activity of purified f1-atpase unmasked by diethylstilb ...19892482079
determination of the functional homology of beta subunits isolated from various f1-atpase complexes: their role in catalysis and coupled proton-translocation. 19882458598
role of water in processes of energy transduction: ca2+-transport atpase and inorganic pyrophosphatase.after the proposal of the chemiosmotic theory by mitchell (1966, 1979) it has been recognized that different membrane-bound enzymes are able to use the energy derived from ionic gradients for the synthesis of atp. these include the f1-atpases of mitochondria and chloroplasts, the ca2+-dependent atpase of sarcoplasmic reticulum and the (na+,k+)-atpase of plasma membrane. in these systems the process of energy transduction is fully reversible. the enzyme can use the energy derived from the hydroly ...19852428374
reconstitution of the h+-atpase complex of rhodospirillum rubrum by the beta subunit of the chloroplast coupling factor 1.a method is described for isolating the beta subunit from spinach chloroplast f1 (cf1). the isolated beta subunit reconstituted an active f1 hybrid with the f1 of rhodospirillum rubrum chromatophores from which the beta subunit had been removed. the cf1 beta subunit was similar to the isolated beta subunit of escherichia coli f1 (gromet-elhanan, z., khananshivili, d., weiss, s., kanazawa, h., and futai, m. (1985) j. biol. chem. 260, 12635-12640) in that it restored a substantial rate of atp hydr ...19862427516
purification of a light-harvesting b880 complex from wild-type rhodospirillum rubrum.the light-harvesting b880 complex of rhodospirillum rubrum was purified by a new method which allowed recovery of 66% of the amount present in the crude solubilized extract. electrophoretic analysis of the isolated complex, followed by either coomassie brilliant blue or silver staining, revealed only two low-molecular-weight polypeptides. when compared to a previously described preparation, the stability of the complex was considerably increased. in addition, the new procedure yielded b880 of hi ...19862420229
isolation and partial characterization of the messenger rna encoding the b880 holochrome protein of rhodospirillum rubrum.the b880 holochrome messenger rna was extracted from cultures of the photosynthetic bacterium rhodospirillum rubrum. it was purified by chromatography on sepharose 4b followed by sucrose density gradient centrifugation. the purified fractions were shown to program an escherichia coli cell-free system into synthesizing both the alpha and the beta polypeptides of the holochrome. the translation products were identified by immunoprecipitation with specific antibodies raised against these polypeptid ...19852416565
nitrogenase in the archaebacterium methanosarcina barkeri 227.the discovery of nitrogen fixation in the archaebacterium methanosarcina barkeri 227 raises questions concerning the similarity of archaebacterial nitrogenases to mo and alternative nitrogenases in eubacteria. a scheme for achieving a 20- to 40-fold partial purification of nitrogenase components from strain 227 was developed by using protamine sulfate precipitation, followed by using a fast protein liquid chromatography apparatus operated inside an anaerobic glove box. as in eubacteria, the nitr ...19902254255
the pet genes of rhodospirillum rubrum: cloning and sequencing of the genes for the cytochrome bc1-complex.a cytochrome bc1-complex of rs. rubrum was isolated and the three subunits were purified to homogeneity. the n-terminal amino acid sequence of the purified subunits was determined by automatic edman degradation. the pet genes of rhodospirillum rubrum coding for the three subunits of the cytochrome bc1-complex were isolated from a genomic library of rs. rubrum using oligonucleotides specific for conserved regions of the subunits from other organisms and a heterologous probe derived from the genes ...19902176269
proton nmr study of the comparative electronic/magnetic properties and dynamics of the acid in equilibrium with alkaline transition in a series of ferricytochromes c'.the proton nmr spectra of ferricytochrome c' from rhodopseudomonas palustris, rhodospirillum molischianum, rhodospirillum rubrum, and chromatium vinosum have been investigated for the purpose of further elucidating the common spectral and/or structural properties for this subclass of cytochromes in the acidic and alkaline forms, and to characterize in detail the dynamics and structural basis for this acid in equilibrium with alkaline transition. the identification of strongly upfield-shifted mes ...19902168882
resonance raman spectroscopy of cytochrome bc1 complexes from rhodospirillum rubrum: initial characterization and reductive titrations.resonance raman spectra of bc1 complexes from rhodospirillum rubrum have been obtained. various resonance conditions and the stoichiometric redox titration of the complex were used to isolate and identify the contributions of the heme c1 and heme b active sites to the observed spectra. the complex was found to partially photoreduce when exposed to laser excitation.19902165419
characterization of ph-dependent conformational heterogeneity in rhodospirillum rubrum cytochrome c2 using 15n and 1h nmr.the 15n-enriched ferricytochrome c2 from rhodospirillum rubrum has been studied by 15n and 1h nmr spectroscopy as a function of ph. the 15n resonances of the heme and ligand tau nitrogen are broadened beyond detection because of paramagnetic relaxation. the 15n resonance of the ligand histidine phi nitrogen was unambiguously identified at 184 ppm (ph 5.6). the 15n resonances of the single nonligand histidine are observed only at low ph, as in the ferrocytochrome because of the severe broadening ...19902159779
assignments of 15n and 1h nmr resonances and a neutral ph ionization in rhodospirillum rubrum cytochrome c2.the phi nh proton and 15n resonances of the ligand histidine of rhodospirillum rubrum fericytochrome c2 are found at 14.7 and 184 ppm, respectively, contradicting the proposal that this proton is absent in the r. rubrum ferricytochrome. substitution of the deuterium atom for this proton causes small upfield shifts of the phi nitrogen in both oxidation states, indicating that the phi nh-peptide carboxyl hydrogen bond is not substantially weakened by the substitution. the proton and 15n resonances ...19902159778
soluble cytochromes and a photoactive yellow protein isolated from the moderately halophilic purple phototrophic bacterium, rhodospirillum salexigens.three soluble cytochromes were found in two strains of the halophilic non-sulfur purple bacterium rhodospirillum salexigens. these are cytochromes c2, c and c-551. cytochrome c2 was recognized by the presence of positive charge at the site of electron transfer (measured by laser flash photolysis), although the protein has an overall negative charge (pi = 4.7). cytochrome c2 has a high redox potential (300 mv) and is monomeric (13 kda). cytochrome c was recognized from its characteristic absorpti ...19902158819
versatile protein engineering vectors for mutagenesis, expression and hybrid enzyme formation. 19902158660
molecular cloning, sequencing and expression of cytochrome c2 from rhodospirillum rubrum.cytochrome c2 (mr 12,840) of the purple photosynthetic bacterium rhodospirillum rubrum functions as a mobile electron carrier in the cyclic photosynthetic electron-transport system of this organism. it acts as the electron donor to photochemically oxidized reaction centres and is reduced in turn by electrons from the cytochrome bc1 complex. by using synthetic oligonucleotides based on the known amino acid sequence of the protein, the structural gene (cyca) has been identified and isolated. dna s ...19902154194
chromatographic and protein chemical analysis of the ubiquinol-cytochrome c2 oxidoreductase isolated from rhodobacter sphaeroides.the ubiquinol-cytochrome c2 oxidoreductase (cytochrome bc1 complex) purified from chromatophores of rhodobacter sphaeroides consists of four polypeptide subunits corresponding to cytochrome b, c1, and the rieske iron-sulfur protein, as well as a 14-kda polypeptide of unknown function, respectively. in contrast, the complex isolated from rhodospirillum rubrum by the same procedure lacked a polypeptide corresponding to the 14-kda subunit. gel-permeation chromatography of the r. sphaeroides cytochr ...19902153104
the contribution of the carotenoid to the visible circular dichroism of the light-harvesting antenna of rhodospirillum rubrum.the visible c.d. spectrum of wild-type rhodospirillum rubrum shows positive bands [dratz, schultz & sauer (1966) brookhaven symp. biol. 19, 303-318] that are largely due to the b880 antenna pigments, bacteriochlorophyll a and carotenoids. the bacteriochlorophyll c.d. band was absent from the spectrum of r. rubrum g9, a mutant unable to synthesize coloured carotenoids, and could be partly restored by adding extracted carotenoids to freeze-dried membrane vesicles isolated from that mutant. therefo ...19902119174
carboxylterminal deletion mutants of ribulosebisphosphate carboxylase from rhodospirillum rubrum.the carboxylterminal octapeptide of ribulosebisphosphate carboxylase from rhodospirillum rubrum, which lacks small subunits, shows homology to a highly conserved region near the amino terminus of the small subunits of hexadecameric ribulosebisphosphate carboxylases, which are composed of large and small subunits. truncations of the r. rubrum enzyme, which partially or completely deleted the region of homology, demonstrated that the region is not an important determinant of the catalytic efficien ...19902114311
comparison of the crystal structures of l2 and l8s8 rubisco suggests a functional role for the small subunit.comparison of the crystal structures of the l2 and l8s8 forms of ribulose-1,5-bisphosphate carboxylase from rhodospirillum rubrum and spinach respectively, reveals a remarkable similarity in the overall architecture of the l2 building blocks in the two enzymes. within the l subunits, no large conformational differences such as domain-domain rotations were found. in spite of a somewhat different packing of the l subunits in the l2 dimer, the active sites of the two enzymes are highly conserved. s ...19902113466
[the surface membrane charge of bacteria and its role in serine proteinase secretion by bacillus subtilis cells].univalent, bivalent and trivalent metal cations increase the fluorescence yield of 9-aminoacridine in the suspensions of chromatophores of the purple nonsulfur bacterium rhodospirillum rubrum isolated thylakoid membranes and cells of cyanobacterium anabaena variabilis, cells bacillus subtilis. the active cation concentrations increase about in 10 times with the decrease of their valency by one. it points to the fact that the changes in 9-aminoacridine fluorescence serve for the monitoring of the ...19902112959
electron transfer between primary and secondary donors in rhodospirillum rubrum: evidence for a dimeric association of reaction centers.light-induced oxidation of the primary electron donor p and of the secondary donor cytochrome c2 was studied in whole cells of rhodospirillum rubrum in the presence of myxothiazole to slow down their reduction. 1. the primary and secondary electron donors are close to thermodynamic equilibrium during continuous illumination when the rate of the electron transfer is light-limited. this implies a long-range thermodynamic equilibration involving the diffusible cytochrome c2. a different behavior is ...19902112407
probing the bacteriochlorophyll binding site by reconstitution of the light-harvesting complex of rhodospirillum rubrum with bacteriochlorophyll a analogues.structural features of bacteriochlorophyll (bchl) a that are required for binding to the light-harvesting proteins of rhodospirillum rubrum were determined by testing for reconstitution of the b873 or b820 (structural subunit of b873) light-harvesting complexes with bchl a analogues. the results indicate that the binding site is very specific; of the analogues tested, only derivatives of bchl a with ethyl, phytyl, and geranylgeranyl esterifying alcohols and bchl b (phytyl) successfully reconstit ...19902110819
truncation of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) from rhodospirillum rubrum affects the holoenzyme assembly and activity.truncations of the subunit of ribulose bisphosphate carboxylase/oxygenase (rubisco) from rhodospirillum rubrum were generated by site-directed mutagenesis to examine the role of the c-terminal tail section. removal of the last and the penultimate alpha-helices in the tail section changes the quaternary structure of the protein. electrophoretic and electron microscope analysis revealed that the truncated subunits assemble into an octamer, whereas the wild-type enzyme has a dimeric structure. the ...19902109693
activation of the nickel-deficient carbon monoxide dehydrogenase from rhodospirillum rubrum: kinetic characterization and reductant requirement.the requirements for and kinetics of the activation of the nickel-deficient (apo) co dehydrogenase from rhodospirillum rubrum by exogenous nickel have been investigated. the activation is strictly dependent upon the presence of a low-potential one-electron reductant. sodium dithionite and reduced methylviologen (e degrees' = -440 mv) are suitable reductants, whereas reduced indigo carmine (e degrees' = -125 mv) and the two-electron reductants sodium borohydride, nadh, and dithiothreitol are inef ...19902109635
determination of hopanoid levels in bacteria using high-performance liquid chromatography.a reverse-phase hplc method to detect and quantify levels of hopanoids in bacteria has been developed. chromophores have been introduced by derivatization and the levels of the c35 hopanoids and their conjugates can be measured in bacterial lipid extracts down to picomole levels. some structural variations of the complex lipids were detected after derivatization and were easily purified using the same hplc system. zymomonas mobilis and rhodospirillum rubrum extracts were examined using this syst ...19902109551
crystallographic refinement and structure of ribulose-1,5-bisphosphate carboxylase from rhodospirillum rubrum at 1.7 a resolution.the amino acid sequence of ribulose-1,5-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum has been fitted to the electron density maps. the resulting protein model has been refined to a nominal resolution of 1.7 a using the constrained-restrained least-squares refinement program of sussman and the restrained least-squares refinement program of hendrickson & konnert. the crystallographic refinement, based on 76,452 reflections with f greater than sigma (f) in the resolution range 5.5 ...19902107319
cloning and expression of dratg genes from azospirillum lipoferum.a genomic library of azospirillum lipoferum was constructed with phage lambda embl4 as vector. from this library, the genes encoding dinitrogenase reductase adp-ribosyltransferase (drat), drat, and dinitrogenase reductase-activating glycohydrolase (drag), drag, were cloned by hybridization with the heterologous probes of rhodospirillum rubrum. as in r. rubrum, drat is located between drag and nifh, the gene encoding dinitrogenase reductase (a substrate for the drag/drat system). in the crude ext ...19902107127
reversible adp-ribosylation is demonstrated to be a regulatory mechanism in prokaryotes by heterologous expression.the primary product of biological nitrogen fixation, ammonia, reversibly regulates nitrogenase activity in a variety of diazotrophs by a process called "nh4(+)-switch-off/on." strong correlative evidence from work in azospirillum lipoferum and rhodospirillum rubrum indicates that this regulation involves both the inactivation of dinitrogenase reductase by dinitrogenase reductase adp-ribosyltransferase and the reactivation by dinitrogenase reductase activating glycohydrolase. the genes encoding t ...19902106680
spectroscopic characterization of the light-harvesting complex of rhodospirillum rubrum and its structural subunit.the spectroscopic properties of the light-harvesting complex of rhodospirillum rubrum, b873, and a detergent-isolated subunit form, b820, are presented. absorption and circular dichroism spectra suggest excitonically interacting bacteriochlorophyll alpha (bchl alpha) molecules give b820 its unique spectroscopic properties. resonance raman results indicate that bchl alpha is 5-coordinate in both b820 and b873 but that the interactions with the bchl c2 acetyl in b820 and b873 are different. the re ...19902105744
an engineered change in substrate specificity of ribulosebisphosphate carboxylase/oxygenase.the potential for altering the specificity of ribulosebisphosphate carboxylase/oxygenase toward gaseous substrates is explored through a modest perturbation of the active site microenvironment. specifically, replacement of active site glu-48 with carboxy-methylcysteine is achieved in a two-step process in which the catalytically incompetent cys-48 mutant protein is first generated and then treated with iodoacetic acid. this regimen of concerted site-directed mutagenesis and chemical modification ...19902104836
cellular differentiation in the process of generation of the eukaryotic cell.primitive atmosphere of the earth did not contain oxygen gas (o2) when the proto-cells were generated successfully as the result of chemical evolution and then evolved. therefore, they first had acquired anaerobic energy metabolism, fermentation. the cellular metabolisms have often been formed by reorganizing to combine or recombinate between pre-existing metabolisms and newly born bioreactions. photosynthetic metabolism in eukaryotic chloroplast consists of an electron-transfer photosystem and ...19902103939
isolation and characterization of a structural subunit from the core light-harvesting complex of rhodobacter sphaeroides 2.4.1 and puc705-ba.a method for isolating a structural subunit, b825, from the b875 core light-harvesting complex (lhc) of rhodobacter sphaeroides 2.4.1 (wild-type) and a b800-b850(-) mutant, puc705-ba, is presented. this method, based on one developed to prepare a similar subunit, b820, from the core lhc of rhodospirillum rubrum [miller et al., biochemistry 26, 5055-5062 (1987)], requires the dissociation of treated chromatophores with the detergent, octyl-glucoside. a subsequent gel filtration step separates b80 ...19902089436
possible role of the highly conserved amino acids trp-8 and pro-13 in the n-terminal segment of the pigment-binding polypeptide lhi alpha of rhodobacter capsulatus.trp-8 and pro-13 of the rhodobacter capsulatus light-harvesting (lh) i alpha polypeptide are highly conserved among lhi and lhii alpha proteins of several species of the rhodospirillaceae. exchange of trp-8 and pro-13 to other amino acyl residues similar in structure and/or hydrophobicity indicates that trp-8 is involved in the insertion of the lhi alpha polypeptide into the intracytoplasmic membrane (icm). pro-13, however, seems not to participate in the integration process of the lhi alpha pro ...19912065784
complementation of a pleiotropic nif-gln regulatory mutant of rhodospirillum rubrum by a previously unrecognized azotobacter vinelandii regulatory locus.a spontaneous pleiotropic nif- mutation in rhodospirillum rubrum has been partially characterized biochemically and by complementation analysis with recombinant plasmids carrying azotobacter vinelandii dna in the vicinity of orf12 [jacobson et al. (1989) j. bacteriol 171: 1017-1027]. in addition to being unable to grow on n2 as a nitrogen source the phenotypic characterization of this and other metronidazole enriched spontaneous mutants showed (a) no nitrogenase activity, (b) the absence of nifh ...19901980582
the cloning and functional characterization of the nifh gene of rhodospirillum rubrum.dinitrogenase reductase (the nifh product) from rhodospirillum rubrum is regulated by a post-translational modification system encoded by dratg. as demonstrated in this report, the cloning, sequencing, and functional characterization of the nifh gene provides a basis for further analysis as well as revealing interesting features of gene organization. the coding regions of nifh and drat are separated by only 400 bp, though the genes are divergently transcribed and differentially regulated. the co ...19901979299
identification of a groes-like chaperonin in mitochondria that facilitates protein folding.mitochondria contain a polypeptide that is functionally equivalent to escherichia coli chaperonin 10 (cpn10; also known as groes). this mitochondrial cpn10 has been identified in beef and rat liver and is able to replace bacterial cpn10 in the chaperonin-dependent reconstitution of chemically denatured ribulose-1,5-bisphosphate carboxylase. thus, like the bacterial homologue, mitochondrial cpn10 facilitates a k(+)- and mg.atp-dependent discharge of unfolded (or partially folded) ribulose bisphos ...19901977163
atp-dependent and nad-dependent modification of glutamine synthetase from rhodospirillum rubrum in vitro.glutamine synthetase from the photosynthetic bacterium rhodospirillum rubrum is the target of both atp- and nad-dependent modification. incubation of r. rubrum cell supernatant with [alpha-32p]nad results in the labeling of glutamine synthetase and two other unidentified proteins. dinitrogenase reductase adp-ribosyltransferase does not appear to be responsible for the modification of glutamine synthetase or the unidentified proteins. the [alpha-32p]atp- and [alpha-32p] nad-dependent modification ...19901974253
examination of the intersubunit interaction between glutamate-48 and lysine-168 of ribulose-bisphosphate carboxylase/oxygenase by site-directed mutagenesis.the active site of ribulose-bisphosphate carboxylase/oxygenase is constituted from domains of adjacent subunits and includes an intersubunit electrostatic interaction between lys 168 and glu48, which has been recently identified by x-ray crystallography (andersson, i., knight, s., schneider, g., lindqvist, y., lundqvist, t., brändén, c.-i., and lorimer, g.h. (1989) nature 337, 229-234; lundqvist, t., and schneider, g. (1989) j. biol. chem. 264, 7078-7083). to examine the structural and functiona ...19901969412
mutations in the drat and drag genes of rhodospirillum rubrum result in loss of regulation of nitrogenase by reversible adp-ribosylation.reversible adp-ribosylation of dinitrogenase reductase forms the basis of posttranslational regulation of nitrogenase activity in rhodospirillum rubrum. this report describes the physiological effects of mutations in the genes encoding the enzymes that add and remove the adp-ribosyl moiety. mutants lacking a functional drat gene had no dinitrogenase reductase adp-ribosyltransferase (drat, the drat gene product) activity in vitro and were incapable of modifying dinitrogenase reductase with adp-ri ...19911938894
purification and partial characterization of a pyruvate oxidoreductase from the photosynthetic bacterium rhodospirillum rubrum grown under nitrogen-fixing conditions.a pyruvate oxidoreductase with the capacity to support pyruvate-dependent nitrogenase activity in vitro has been purified from the photosynthetic bacterium rhodospirillum rubrum. the enzyme requires coa for activity and is irreversibly inactivated by oxygen. the molecular properties and km values for the substrates have been studied. in supporting nitrogenase activity addition of ferredoxin is required. overall the enzyme is similar to the nif-specific pyruvate: flavodoxin oxidoreductase purifie ...19911930134
purification and partial characterization of glutamate synthase from rhodospirillum rubrum grown under nitrogen-fixing conditions.glutamate synthase, a key enzyme in ammonia assimilation, has been purified from the photosynthetic bacterium rhodospirillum rubrum. the purification procedure involves ion-exchange chromatography, affinity chromatography and gel filtration. the recovery in the procedure is high (62%) and the specific activity is 21 mumol of nadph oxidized/min per mg. the enzyme is specific for its substrates, and no activity was demonstrated with nadh or nh4+ ions substituting for nadph and glutamine respective ...19911930133
cos degradation by selected co-utilizing bacteria. scientific note. 19911929384
performance of trickle-bed bioreactors for converting synthesis gas to methane.carbon monoxide, h2, and co2 in synthesis gas can be converted to ch4 by employing a triculture of rhodospirillum rubrum, methanosarcina barkeri, and methanobacterium formicicum. trickle-bed reactors have been found to be effective for this conversion because of their high mass-transfer coefficients. this paper compares results obtained for the conversion of synthesis gas to ch4 in 5-cm- and 16.5-cm-diameter trickle-bed reactors. mass-transfer and scale-up parameters are defined, and light requi ...19911929378
characterization of the co oxidation/h2 evolution system of rhodospirillum rubrum. role of a 22-kda iron-sulfur protein in mediating electron transfer between carbon monoxide dehydrogenase and hydrogenase.the response of the membrane-associated carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum to solubilization by detergents and organic solvents, the properties of solubilized codh, and the mechanism for coupling co oxidation to hydrogen evolution via a co-induced hydrogenase activity have been investigated. the release of codh by a variety of ionic and nonionic detergents occurs in a redox-dependent fashion: codh is solubilized in the presence of low-potential reductants (dithionite ...19911917963
glycine 100 in the dinitrogenase reductase of rhodospirillum rubrum is required for nitrogen fixation but not for adp-ribosylation.dinitrogenase reductase (rr2) is required for reduction of the molybdenum dinitrogenase in the nitrogen fixation reaction and is the target of posttranslational regulation in rhodospirillum rubrum. this posttranslational regulation involves the adp-ribosylation of rr2. to study the structural requirements for these two functions of rr2, i.e., activity and regulation, two site-directed mutations in nifh, the gene encoding rr2, were constructed and analyzed. the mutations both affected a region of ...19911917849
identification of an alternative nitrogenase system in rhodospirillum rubrum.a second nitrogenase activity has been demonstrated in rhodospirillum rubrum. this nitrogenase is expressed whenever a strain lacks an active mo nitrogenase because of physiological or genetic inactivation. the alternative nitrogenase is able to support growth on n2 in the absence of fixed n. v does not stimulate, nor does mo or w inhibit, growth or activity under the conditions tested. the proteins responsible for this activity were identified by electrophoretic and immunological properties. th ...19911909322
crystal structure of activated ribulose-1,5-bisphosphate carboxylase complexed with its substrate, ribulose-1,5-bisphosphate.the three-dimensional structure of the complex of ribulose-1,5-bisphosphate carboxylase from rhodospirillum rubrum, co2, mg2+, and ribulose bisphosphate has been determined with x-ray crystallographic methods to 2.6-a resolution. ribulose-1,5-bisphosphate binds across the active site with the two phosphate groups in the two phosphate binding sites of the beta/alpha barrel. the oxygen atoms of the carbamate and the side chain of asp-193 provide the protein ligands to the bound mg2+ ion. the c2 an ...19911905726
fluorescence polarization and low-temperature absorption spectroscopy of a subunit form of light-harvesting complex i from purple photosynthetic bacteria.measurements of polarized fluorescence and cd were made on light-harvesting complex 1 and a subunit form of this complex from rhodospirillum rubrum, rhodobacter sphaeroides, and rhodobacter capsulatus. the subunit form of lh1, characterized by a near-infrared absorbance band at approximately 820 nm, was obtained by titration of carotenoid-depleted lh1 complexes with the detergent n-octyl beta-d-glucopyranoside as reported by miller et al. (1987) [miller j. f., hinchigeri, s. b., parkes-loach, p. ...19911904275
demonstration of a functional requirement for the carbamate nitrogen of ribulosebisphosphate carboxylase/oxygenase by chemical rescue.ribulosebisphosphate carboxylase/oxygenase is reversibly activated by the reaction of co2 with a specific lysyl residue (lys191 of the rhodospirillum rubrum enzyme) to form a carbamate that coordinates an essential mg2+ cation. surprisingly, the lys191----cys mutant protein, in the presence of co2 and mg2+, exhibits tight binding of the reaction intermediate analogue 2-carboxyarabinitol bisphosphate [smith, h. b., larimer, f. w., & hartman, f. c. (1988) biochem. biophys. res. commun. 152, 579-58 ...19911903652
pyruvate is a by-product of catalysis by ribulosebisphosphate carboxylase/oxygenase.pyruvate is a minor product of the reaction catalyzed by ribulosebisphosphate carboxylase/oxygenase from spinach leaves. labeled pyruvate was detected, in addition to the major labeled product, 3-phosphoglycerate, when 14co2 was the substrate. pyruvate production was also measured spectrophotometrically in the presence of lactate dehydrogenase and nadh. the km for co2 of the pyruvate-producing activity was 12.5 microm, similar to the co2 affinity of the 3-phosphoglycerate-producing activity. no ...19911903385
the puh structural gene coding for the h subunit of the rhodospirillum rubrum photoreaction center.the rhodospirillum rubrum structural gene puh, coding for the photoreaction center h polypeptide, and three other putative genes that surround puh were cloned and sequenced. the deduced 257 amino acid h polypeptide has a molecular weight of 27,909, in close agreement with polyacrylamide gel electrophoresis determination. hydropathy plots predict a single hydrophobic alpha helix. the h polypeptide of rhodospirillum rubrum shares only 23% of its residues with all three of the h polypeptides from r ...19911903263
dimeric carotenoid interaction in the light-harvesting antenna of purple phototrophic bacteria.the carotenoid content of intracytoplasmic membrane vesicles isolated from purple phototrophic bacteria was reduced to a variable extent by mild extraction with light petroleum. using preparations obtained from rhodobacter capsulatus strains that contained the light harvesting system i (lhi) complex as the only major photosynthetic holochrome, it was shown that the visible circular dichroism of the carotenoids increased with the square of the membrane carotenoid content, as expected from being c ...19911901490
expression of endogenous and foreign ribulose 1,5-bisphosphate carboxylase-oxygenase (rubisco) genes in a rubisco deletion mutant of rhodobacter sphaeroides.a rhodobacter sphaeroides ribulose 1,5-bisphosphate carboxylase-oxygenase (rubisco) deletion strain was constructed that was complemented by plasmids containing either the form i or form ii co2 fixation gene cluster. this strain was also complemented by genes encoding foreign rubisco enzymes expressed from a rhodospirillum rubrum rubisco promoter. in r. sphaeroides, the r. rubrum promoter was regulated, resulting in variable levels of disparate rubisco molecules under different growth conditions ...19911900508
probing the primary quinone environment in photosynthetic bacterial reaction centers by light-induced ftir difference spectroscopy.the photoreduction of the primary electron acceptor, qa, has been characterized by light-induced fourier transform infrared difference spectroscopy for rb. sphaeroides reaction centers and for rsp. rubrum and rp. viridis chromatophores. the samples were treated both with redox compounds, which rapidly reduce the photooxidized primary electron p+, and with inhibitors of electron transfer from qa- to the secondary quinone qb. this approach yields spectra free from p and p+ contributions which make ...19911899390
crystal structure of the ternary complex of ribulose-1,5-bisphosphate carboxylase, mg(ii), and activator co2 at 2.3-a resolution.the activated ternary complex, enzyme-co2-mg(ii), of the dimeric ribulose-1,5-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum can be prepared in the same crystal form that was used for the crystallographic structure determination of the native nonactivated enzyme (schneider, g., bränden, c.-i., & lorimer, g. (1986) j. mol. biol. 187, 141-143). the three-dimensional structure of the activated enzyme has been determined to a nominal resolution of 2.3 a by protein crystallographic met ...19911899197
rapid purification and characterization of homoserine dehydrogenase from saccharomyces cerevisiae.homoserine dehydrogenase of saccharomyces cerevisiae has been rapidly purified to homogeneity by heat and acid treatments, ammonium sulfate fractionation, and chromatography on matrex gel red a and q-sepharose columns. the final preparation migrated as a single entity upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a mr of 40,000. the mr of the native enzyme was 81,000 as determined by gel filtration, suggesting that the enzyme is composed of two identical subunits. this feat ...19911897932
[the role of propionyl-coa carboxylase in the biosynthesis of antibiotics]. 19911892432
attenuated effect of oxygen on photopigment synthesis in rhodospirillum centenum.rhodospirillum centenum resembles typical nonsulfur photosynthetic bacteria in a number of respects, including its ability to grow either anaerobically as a phototroph or aerobically as a heterotroph. we demonstrate, however, that r. centenum is unusual in its ability to synthesize a functional photosynthetic apparatus regardless of the presence of molecular oxygen. aerobically expressed photopigments were shown to be functionally active, as demonstrated by the ability of heterotrophically grown ...19911885527
purification and properties of the h(+)-nicotinamide nucleotide transhydrogenase from rhodobacter capsulatus.1. h(+)-transhydrogenase from rhodobacter capsulatus is an integral membrane protein which, unlike the enzyme from rhodospirillum rubrum, does not require the presence of a water-soluble component for activity. 2. the enzyme from rb. capsulatus was solubilised in triton x-100 and subjected to ion-exchange, hydroxyapatite and then gel-exclusion column chromatography. sds/page of the purified enzyme revealed the presence of two polypeptides with apparent mr 53,000 and 48,000. other minor component ...19911849819
proton-pumping n,n'-dicyclohexylcarbodiimide-sensitive inorganic pyrophosphate synthase from rhodospirillum rubrum: purification, characterization, and reconstitution.a new method has been developed for the isolation of the proton-pumping n,n'-dicyclohexylcarbodiimide-sensitive ppi synthase (h(+)-ppi synthase) from chromatophores of rhodospirillum rubrum. the h(+)-ppi synthase was purified by extraction of chromatophores with a mixture of nonanoyl-n-methylglucamide and cholate, by fractionation with poly(ethylene glycol) 4000, hydroxyapatite chromatography, and affinity chromatography. the purified enzyme is homogeneous and has a specific activity of 20.4 mum ...19911848779
electron spin echo envelope modulation spectroscopy supports the suggested coordination of two histidine ligands to the rieske fe-s centers of the cytochrome b6f complex of spinach and the cytochrome bc1 complexes of rhodospirillum rubrum, rhodobacter sphaeroides r-26, and bovine heart mitochondria.electron spin echo envelope modulation (eseem) experiments performed on the rieske fe-s clusters of the cytochrome b6f complex of spinach chloroplasts and of the cytochrome bc1 complexes of rhodospirillum rubrum, rhodobacter sphaeroides r-26, and bovine heart mitochondria show modulation components resulting from two distinct classes of 14n ligands. at the g = 1.92 region of the rieske epr spectrum of the cytochrome b6f complex, the measured hyperfine couplings for the two classes of coupled nit ...19911847076
proton-translocating transhydrogenase from photosynthetic bacteria. 19911838340
extraction and purification of the beta subunit and an active alpha beta-core complex from the spinach chloroplast cfof1-atp synthase.incubation of rhodospirillum rubrum chromatophores with 2 m licl in the presence of mgatp has been shown to remove their f1 beta subunit leaving inactive but fully reconstitutable beta-less chromatophores (gromet-elhanan, z., and khanashvili, d., (1986) methods enzymol, 126, 528-538). a similar treatment of thoroughly washed spinach thylakoids has now been shown to release the cf1 beta subunit (cf1 beta) together with a complex containing equal amounts of cf1 alpha and cf1 beta (cf1 (alpha beta] ...19911826683
dna sequencing and complementation/deletion analysis of the bcha-puf operon region of rhodobacter sphaeroides: in vivo mapping of the oxygen-regulated puf promoter.within the photosynthetic gene cluster of rhodobacter sphaeroides the genes encoding light-harvesting lhi and reaction-centre complexes are transcriptionally linked in the order pufbalmx. the region stretching 1.6 kb upstream of pufb has been examined by dna sequencing and by complementation/deletion analysis. these studies demonstrate that three open reading frames are located upstream of pufb. one open reading frame, designated bcha, terminates just inside pufq, which is located proximal to pu ...19911779756
protein engineering of rubisco.modification of the kinetic parameters of enzymes by protein engineering requires extensive knowledge of the structural details of the enzyme and its complexes with different reaction intermediate analogues. such structural studies are described here for rubisco, ribulose-1,5-bisphosphate carboxylase/oxygenase, which catalyzes the initial reactions of two important but competing physiological events in green plants; carbon dioxide fixation and photorespiration. observed functional changes in mut ...19911772628
functional analysis of the putative catalytic bases his-321 and ser-368 of rhodospirillum rubrum ribulose bisphosphate carboxylase/oxygenase by site-directed mutagenesis.numerous candidates have been suggested according to chemical and structural criteria for the active site base of ribulose bisphosphate carboxylase/oxygenase that catalyzes substrate enolization. we evaluate the functional significance of two such candidates, his-321 and ser-368 of the rhodospirillum rubrum enzyme, by site-directed mutagenesis. position 321 mutants retain 3-12% of wild-type rates of both overall carboxylation and the initial enolization, with little effect on km for co2 or ribul ...19911761567
mutations affecting nitrogenase switch-off in rhodobacter vivo 'switch-off' and subsequent reactivation of nitrogenase activity in rhodobacter capsulatus or rhodospirillum rubrum in response to a variety of environmental stimuli, including the addition of fixed nitrogen, is thought to be due to the action of two nitrogenase fe protein modifying activities; drat (dinitrogenase reductase adp-ribosyl transferase) and drag (dinitrogenase reductase-activating glycohydrolase). here it is demonstrated that strains, including one mutated in glnb, that const ...19921730034
construction, characterization, and complementation of rhodospirillum rubrum puf region mutants.rhodospirillum rubrum is a facultatively phototrophic bacterium that, under certain growth conditions, forms an intracytoplasmic chromatophore membrane (icm) housing the photochemical apparatus. the puf operon of r. rubrum encodes protein subunits of the photochemical reaction center and the b880 light-harvesting antenna complex. mutant strains of r. rubrum were constructed by interposon mutagenesis through which a kanamycin resistance gene cartridge was inserted into restriction sites and in pl ...19911715861
phylogenetic analysis and evolution of rnase p rna in proteobacteria.the secondary structures of the eubacterial rnase p rnas are being elucidated by a phylogenetic comparative approach. sequences of genes encoding rnase p rna from each of the recognized subgroups (alpha, beta, gamma, and delta) of the proteobacteria have now been determined. these sequences allow the refinement, to nearly the base pair level, of the phylogenetic model for rnase p rna secondary structure. evolutionary change among the rnase p rnas was found to occur primarily in four discrete str ...19911711030
antigenic sites on cytochrome c2 from rhodospirillum rubrum.the antigenic determinants for three monoclonal antibodies against cytochrome c2 from rhodospirillum rubrum were partially characterized by differential chemical modification of free and antibody-bound cytochrome c2 and by cross-reactivity analysis with different antigens. circular dichroism spectroscopy was used to probe the effect of antibody binding on the conformation of cytochrome c2. the binding of two antibodies was strongly dependent on the native folding of the antigen. the first antibo ...19901688799
low- and high-activity forms of glutamine synthetase from rhodospirillum rubrum: sensitivity to feed-back effectors and activation of the low-activity form.glutamine synthetase from rhodospirillum rubrum can be isolated in two forms, with low and high activity, respectively, depending on the concentration of combined nitrogen in the medium before harvest. the two forms have been studied with respect to their dependence on mn2+ and mg2+ in both the transferase and the biosynthetic assay. there is no difference in ph optimum between the forms in the biosynthetic assay. in addition the ph-optima for the two cations studied are very close, 7.4 (mg2+) a ...19911683256
Displaying items 1801 - 1900 of 2252