Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
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
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
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 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
melissa: a potential experiment for a precursor mission to the moon.melissa (micro-ecological life support system alternative) has been conceived as a micro-organism based ecosystem intended as a tool for developing the technology for a future artificial ecosystem for long term space missions, as for example a lunar base. the driving element of melissa is the recovering of edible biomass from waste, co2, and minerals with the use of sun light as energy source. in this publication, we focus our attention on the potential applications of melissa for a precursor mi ...199611543311
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
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
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
cloning of the amphibolic calvin cycle/oppp enzyme d-ribulose-5-phosphate 3-epimerase (ec 5.1.3.1) 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 5.1.3.1), 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
occurrence and purification of the photoactive yellow protein of ectothiorhodospira halophila (pyp) and of immunologically related proteins of rhodospirillum salexigens and chromatium salexigens and intracellular localization of pyp.the photoactive yellow protein of ectothiohodospira halophila (pyp) was purified to homogeneity by an advanced method and applied as an affinity ligand for the isolation of an anti-pyp igg fraction which was used for immunoscreening. the distribution of proteins immunologically related to pyp was investigated in protein fractions of 51 strains from 38 species of non-halophilic and halophilic phototrophic and chemotrophic eubacteria and archaeobacteria. strong immunoreactive bands indicating the ...19958519800
direct observation of sub-picosecond equilibration of excitation energy in the light-harvesting antenna of rhodospirillum rubrum.excitation energy transfer in the light-harvesting antenna of rhodospirillum rubrum was studied at room temperature using sub-picosecond transient absorption measurements. upon excitation of rs. rubrum membranes with a 200 fs, 600 nm laser flash in the qx transition of the bacteriochlorophyll-a (bchl-a) absorption, the induced transient absorption changes in the qy region were monitored. in rs. rubrum membranes the observed delta od spectrum exhibits ground state bleaching, excited state absorpt ...19958519962
nonlinear annihilation of excitations in photosynthetic systems.the theory of the singlet-singlet annihilation in quasi-homogeneous photosynthetic antenna systems is developed further. in the new model, the following important contributions are taken into account: 1) the finite excitation pulse duration, 2) the occupation of higher excited states during the annihilation, 3) excitation correlation effects, and 4) the effect of local heating. the main emphasis is concentrated on the analysis of pump-probe kinetic measurements demonstrating the first two above ...19958519966
predicting the structure of the light-harvesting complex ii of rhodospirillum molischianum.we attempted to predict through computer modeling the structure of the light-harvesting complex ii (lh-ii) of rhodospirillum molischianum, before the impending publication of the structure of a homologous protein solved by means of x-ray diffraction. the protein studied is an integral membrane protein of 16 independent polypeptides, 8 alpha-apoproteins and 8 beta-apoproteins, which aggregate and bind to 24 bacteriochlorophyll-a's and 12 lycopenes. available diffraction data of a crystal of the p ...19958528066
characterization of an aerobic repressor that coordinately regulates bacteriochlorophyll, carotenoid, and light harvesting-ii expression in rhodobacter capsulatus.for most species of purple photosynthetic bacteria, the presence of molecular oxygen represses synthesis of carotenoids and bacteriochlorophyll. in this study we characterize a strain of rhodobacter capsulatus, db469, which contains a genomic disruption of an open reading frame in the photosynthesis gene cluster termed orf469. characterization of the steady-state level of bacteriochlorophyll synthesis demonstrates that disruption of orf469 results in a 2.5-fold increase in aerobic synthesis of b ...19957768793
posttranslational regulation of nitrogenase in rhodospirillum rubrum strains overexpressing the regulatory enzymes dinitrogenase reductase adp-ribosyltransferase and dinitrogenase reductase activating glycohydrolase.rhodospirillum rubrum strains that overexpress the enzymes involved in posttranslational nitrogenase regulation, dinitrogenase reductase adp-ribosyltransferase (drat) and dinitrogenase reductase activating glycohydrolase (drag), were constructed, and the effect of this overexpression on in vivo drat and drag regulation was investigated. broad-host-range plasmid constructs containing a fusion of the r. rubrum nifh promoter and translation initiation sequences to the second codon of drat, the firs ...19957836296
h+/ppi stoichiometry of membrane-bound pyrophosphatase of rhodospirillum rubrum.two kinetic methods have been used to measure the h+/ppi stoichiometry in the chromatophores of the photosynthetic bacteria rhodospirillum rubrum. in the first method, the fluorescent probe acridine orange was employed to infer the proton pump activity at the steady state of the delta ph generation. at this point the translocation of protons by the h(+)-ppiase in one direction is balanced exactly by the leak of protons in the opposite direction. pyrophosphatase activity was then quickly stopped ...19957840646
enzymatic and chemical cleavage of the core light-harvesting polypeptides of photosynthetic bacteria: determination of the minimal polypeptide size and structure required for subunit and light-harvesting complex formation.to ascertain the minimal structural requirements for formation of the subunit and core light-harvesting complex (lh1), the alpha- and beta-polypeptides of the lh1 from three purple photosynthetic bacteria were enzymatically or chemically truncated or modified. these polypeptides were then used in reconstitution experiments with bacteriochlorophyll a (bchla), and the formation of subunit and lh1 complexes was evaluated using absorbance and circular dichroism spectroscopies. truncation or modifica ...19957849015
the 8.5 a projection map of the light-harvesting complex i from rhodospirillum rubrum reveals a ring composed of 16 subunits.two-dimensional crystals from light-harvesting complex i (lhc i) of the purple non-sulfur bacterium rhodospirillum rubrum have been reconstituted from detergent-solubilized protein complexes. frozen-hydrated samples have been analysed by electron microscopy. the crystals diffract beyond 8 a and a projection map was calculated to 8.5 a. the projection map shows 16 subunits in a 116 a diameter ring with a 68 a hole in the centre. these dimensions are sufficient to incorporate a reaction centre in ...19957882966
stability of the asymmetric escherichia coli chaperonin complex. guanidine chloride causes rapid dissociation.the chaperonin proteins, groel14 and groes7, inhibit protein aggregation and assist in protein folding in a potassium/atp-dependent manner. in vitro, assays for chaperonin activity typically involve adding a denatured substrate protein to the chaperonins and measuring the appearance of correctly folded substrate protein. the influence of denaturant is generally ignored. low concentrations of guanidinium chloride (< 100 mm) had a profound effect on the activity/structure of the chaperonins. guani ...19957890652
reconstitution of the bacterial core light-harvesting complexes of rhodobacter sphaeroides and rhodospirillum rubrum with isolated alpha- and beta-polypeptides, bacteriochlorophyll alpha, and carotenoid.methodology has been developed to reconstitute carotenoids and bacteriochlorophyll alpha with isolated light-harvesting complex i (lhi) polypeptides of both rhodobacter sphaeroides and rhodospirillum rubrum. reconstitution techniques first developed in this laboratory using the lhi polypeptides of r. rubrum, r. sphaeroides, and rhodobacter capsulatus reproduced bacteriochlorophyll alpha spectral properties characteristic of lhi complexes lacking carotenoids. in this study, carotenoids are suppli ...19957890709
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
the alpha beta dimer-catalytic unit of the f1-atpase. 19958654713
use of iron anomalous scattering with multiple models and data sets to identify and refine a weak molecular replacement solution: structure analysis of cytochrome c' from two bacterial species.the structure of cytochrome c' from two bacterial species, alcaligenes sp and alcaligenes denitrificans, have been determined from x-ray diffraction data to 3.0 a resolution using the anomalous scattering of the single fe atom in each to identify and refine a weak molecular-replacement solution. molecular-replacement studies, with the program amore, used two isomorphous data sets (from the two species), two independent search models (the cytochromes c' from rhodospirillum molischianum and rhodos ...199515299294
4-hydroxyphenethyl alcohol--a new cytokinin-like substance from the phototrophic purple bacterium rhodospirillum rubrum 1r.three compounds with cytokinin activity have been isolated from the medium of rhodospirillum rubrum grown photosynthetically. two n-6 aminopurine cytokinins revealed in the medium were identical with those obtained from r. rubrum cells previously. the third compound with cytokinin activity in amaranthus caudatus bioassay proved to be a simple phenolic compound with elemental composition c8h10o2. this cytokinin-like substance according to absorption spectra, mass spectrometry and 1h nmr spectra d ...19957539770
conformational dynamics of a mobile loop in the nad(h)-binding subunit of proton-translocating transhydrogenases from rhodospirillum rubrum and escherichia coli.transhydrogenase catalyses the reversible transfer of reducing equivalents between nad(h) and nadp(h) to the translocation of protons across a membrane. uniquely in rhodospirillum rubrum, the nad(h)-binding subunit (called ths) exists as a separate subunit which can be reversibly dissociated from the membrane-located subunits. we have expressed the gene for r. rubrum ths in escherichia coli to yield large quantities of protein. low concentrations of either trypsin or endoproteinase lys-c lead to ...19957556167
purification, primary structure, and evolution of cytochrome c-550 from the magnetic bacterium, magnetospirillum magnetotacticum.cytochrome c-550 was purified from magnetospirillum magnetotacticum to an electrophoretically homogeneous state, and some of its properties were determined. the cytochrome showed absorption peaks at 528 and 409 nm in the oxidized form, and at 550, 521, and 414 nm in the reduced form. its midpoint redox potential at ph 7.0 was determined to be +289 mv. the primary structure of cytochrome c-550 was determined. cytochrome c is composed of 97 amino acid residues, and its molecular weight was calcula ...19957575096
influence of charge and polarity on the redox potentials of high-potential iron-sulfur proteins: evidence for the existence of two groups.we have investigated the hipips from ectothiorhodospira vacuolata (iso-1 and iso-2), chromatium vinosum, rhodocyclus gelatinosus, rhodocyclus tenuis (strain 2761), rhodopila globiformis, and rhodospirillum salinarum (iso-2) by direct electrochemistry. using a glassy carbon electrode with a negatively charged surface, direct, unpromoted electrochemistry is possible with the positively charged hipips. with the negatively charged hipips, the positively charged and flexible bridging promoter poly(l- ...19957578075
the single-ring thermoanaerobacter brockii chaperonin 60 (tbr-el7) dimerizes to tbr-el14.tbr-es7 under protein folding conditions.chaperone proteins assist in the folding of some newly synthesized proteins and inhibit protein aggregation. the thermoanaerobacter brockii chaperonin proteins (tbr-el and tbr-es) have recently been purified and characterized [truscott, w.n., høj, p. b., & scopes, r. k. (1994) eur. j. biochem. 222, 277-284]; tbr-el was a single seven-membered toroid, unlike most groels which exist as double toroids. using high-resolution gel filtration chromatography, we have resolved the purified tbr-el into si ...19957578105
reversible super-reduction of the cubane [4fe-4s](3+;2+;1+) in the high-potential iron-sulfur protein under non-denaturing conditions. epr spectroscopic and electrochemical studies.the reversible 2 x 1 e- reduction of the cubane cluster from oxidized to reduced to super-reduced states ([4fe-4s]3+<-->[4fe-4s]2+<-->[4fe-4s]1+) was studied in high-potential iron-sulfur proteins (hipips). super-reduction to the 1+ state was not observed in any of the seven hipips tested during cyclic voltammetry (down to -0.95 v). however, equilibration at low potential (ph 7.5) of rhodopila globiformis hipip yields a transient peak around -0.47 v due to the oxidation of super-reduced hipip ad ...19957588720
construction of a 2.8-megabase yeast artificial chromosome contig and cloning of the human methylthioadenosine phosphorylase gene from the tumor suppressor region on 9p21.many human malignant cells lack methylthioadenosine phosphorylase (mtap) enzyme activity. the gene (mtap) encoding this enzyme was previously mapped to the short arm of chromosome 9, band p21-22, a region that is frequently deleted in multiple tumor types. to clone candidate tumor suppressor genes from the deleted region on 9p21-22, we have constructed a long-range physical map of 2.8 megabases for 9p21 by using overlapping yeast artificial chromosome and cosmid clones. this map includes the typ ...19957604019
direct evidence for secondary loss of mitochondria in entamoeba histolytica.archezoan protists are though to represent lineages that diverged from other eukaryotes before acquisition of the mitochondrion and other organelles. the parasite entamoeba histolytica was originally included in this group. ribosomal rna based phylogenies, however, place e. histolytica on a comparatively recent branch of the eukaryotic tree, implying that its ancestors had these structures. in this study, direct evidence for secondary loss of mitochondrial function was obtained by isolating two ...19957604025
phylogeny of the genus azospirillum based on 16s rdna sequence.the 16s rdna of 17 strains of azospirillum, 14 assigned to one of the known species a. amazonense, a. brasilense, a. halopraeferens, a. irakense and a. lipoferum, and the other three of uncertain taxonomic position, was sequenced after polymerase chain reaction amplification and analysed in order to investigate the phylogenetic relationships at the intra-generic and super-generic level. the phylogenetic analysis confirms that the genus azospirillum constitutes a phylogenetically separate entity ...19957607400
spectroscopic properties of the light-harvesting complexes from rhodospirillum molischianum.spectroscopic properties, including low-temperature absorbance, linear and circular dichroism and site-selection fluorescence of the antenna complexes from rhodospirillum molischianum have been determined. the unique 'lh1-like' character of the amino acid sequence from lh2 of this bacterium is reflected in the circular dichroism of the b850 band of this complex. the wavelength dependence of the polarization of the lh2 complex shows an unusual shape that is attributed to the octameric state of th ...19957619833
mutation of the ser2 codon of the light-harvesting b870 alpha polypeptide of rhodobacter capsulatus partially suppresses the pufx phenotype.the exact function of the pufx gene product of rhodobacter capsulatus is uncertain, but deletion of the pufx gene renders cells incapable of phototrophic growth on a minimal medium, and photosynthetic electron transfer is impaired in vitro. however, suppressor mutants that are able to grow phototropically are readily isolated. two such suppressor mutants were characterized as to their phototrophic growth properties, their fluorescence at different incident light intensities, the integrity of the ...19957642484
theory of fluorescence induction in photosystem ii: derivation of analytical expressions in a model including exciton-radical-pair equilibrium and restricted energy transfer between photosynthetic units.the theoretical relationships between the fluorescence and photochemical yields of ps ii and the fraction of open reaction centers are examined in a general model endowed with the following features: i) a homogeneous, infinite ps ii domain; ii) exciton-radical-pair equilibrium; and iii) different rates of exciton transfer between core and peripheral antenna beds. simple analytical relations are derived for the yields and their time courses in induction experiments. the introduction of the excito ...19957647250
effect of an ntrbc mutation on the posttranslational regulation of nitrogenase activity in rhodospirillum rubrum.homologs of ntrb and ntrc genes from rhodospirillum rubrum were cloned and sequenced. a mutant lacking ntrbc was constructed, and this mutant has normal nitrogenase activity under nif-derepressing conditions, indicating that ntrbc are not necessary for the expression of the nif genes in r. rubrum. however, the post-translational regulation of nitrogenase activity by adp-ribosylation in response to nh4+ was partially abolished in this mutant. more surprisingly, the regulation of nitrogenase activ ...19957665521
oxygenation mechanism of ribulose-bisphosphate carboxylase/oxygenase. structure and origin of 2-carboxytetritol 1,4-bisphosphate, a novel o2-dependent side product generated by a site-directed mutant.site-directed mutagenesis has implicated active-site lys329 of rhodospirillum rubrum ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) in promoting the reaction of co2 with the 2,3-enediol of ribulose bisphosphate and in stabilizing carboxylation intermediates [hartman, f. c., & lee, e. h. (1989) j. biol. chem. 264, 11784-11789; lorimer, g. h., chen, y.-r., & hartman, f. c. (1993) biochemistry 32, 9018-9024]. although the k329a mutant is greatly impaired in carboxylation, it catalyzes fo ...19957669788
electron paramagnetic resonance studies of ferric cytochrome c' from photosynthetic bacteria.electronic ground nature of ferric cytochromes c' isolated from five photosynthetic bacteria. chromatium vinosum atcc 17899, rhodobacter capsulatus atcc 11166, rhodopseudomonas palustris atcc 17001, rhodospirillum molischianum atcc 14031, and rhodospirillum rubrum atcc 11170 has been investigated by electron paramagnetic resonance (epr) spectroscopy. epr spectra indicate that the electronic ground state of five ferric cytochromes c' is a quantum mechanical admixed-spin state of a high spin (s = ...19957669805
lipopolysaccharide of rhodospirillum salinarum 40: structural studies on the core and lipid a region.the structural elucidation of lipid a of the cell wall lipopolysaccharide (lps) of rhodospirillum salinarum 40 by chemical methods and laser desorption mass spectrometry revealed the presence of a mixed lipid a composed of three different 1,4'bisphosphorylated beta (1 --> 6)-linked backbone hexosaminyl-hexosamine disaccharides, i.e. those composed of glcn --> glcn, 2,3-diamino-2,3-dideoxy-d-glc-(dag --> dag, and dag --> glcn. lipid a of r. salinarum contained preferentially 3-oh-18:0 and 3-oh-14 ...19957487334
proton-translocating nicotinamide nucleotide transhydrogenase. reconstitution of the extramembranous nucleotide-binding domains.the nicotinamide nucleotide transhydrogenase of bovine mitochondria is a homodimer of monomer m(r) = 109,065. the monomer is composed of three domains, an nh2-terminal 430-residue-long hydrophilic domain i that binds nad(h), a central 400-residue-long hydrophobic domain ii that is largely membrane intercalated and carries the enzyme's proton channel, and a cooh-terminal 200-residue-long hydrophilic domain iii that binds nadp(h). domains i and iii protrude into the mitochondrial matrix, where the ...19957499307
macroscopic phototactic behavior of the purple photosynthetic bacterium rhodospirillum centenum.most photosynthetic microorganisms have the capability of photosensing light quality and intensity. movement of motile photosynthetic microorganisms to locales that offer optimal physical and chemical conditions for light-dependent growth provides obvious selective advantages. among phototrophs, many cyanobacteria and algae migrate towards or away from the direction of light, a process termed phototaxis. in contrast, anoxygenic photosynthetic bacteria are believed to respond to changes in light ...19957710317
mechanistic insights provided by deletion of a flexible loop at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase.to evaluate the functions of flexible loop 6 at the active site of rhodospirillum rubrum d-ribulose-1,5-bisphosphate carboxylase/oxygenase, the loop was truncated by cassette mutagenesis, whereby seven residues of the twelve-residue loop were excised and replaced by two glycyl residues. the purified loop-deletion mutant was totally devoid of carboxylase activity, but retained substantial catalytic competency in the enolization of ribulose bisphosphate (the initial step in the overall carboxylase ...19957718555
carbon monoxide-induced activation of gene expression in rhodospirillum rubrum requires the product of cooa, a member of the cyclic amp receptor protein family of transcriptional regulators.induction of the co-oxidizing system of the photosynthetic bacterium rhodospirillum rubrum is regulated at the level of gene expression by the presence of co. in this paper, we describe the identification of a gene that is required for co-induced gene expression. an 11-kb deletion of the region adjacent to the previously characterized coofsctj region resulted in a mutant unable to synthesize co dehydrogenase in response to co and unable to grow utilizing co as an energy source. a 2.5-kb region t ...19957721706
carbon monoxide-dependent growth of rhodospirillum rubrum.under dark, anaerobic conditions in the presence of sufficient nickel, rhodospirillum rubrum grows with a doubling time of under 5 h by coupling the oxidation of co to the reduction of h+ to h2. co-dependent growth of r. rubrum ur294, bearing a kanamycin resistance cassette in cooc, depends on a medium nickel level ninefold higher than that required for optimal growth of coo+ strains.19957721719
reactivity of carbon monoxide dehydrogenase from rhodospirillum rubrum with carbon dioxide, carbonyl sulfide, and carbon disulfide.the reactivities of co2 and the related compounds cos and cs2 with the nickel- and iron- sulfur-containing carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum have been investigated. both co2 and cos were substrates for codh in a reductant-dependent reaction resulting in the formation of co. co2 was reduced to co and h2o, while cos was reduced to co and h2s. co was a potent inhibitor of co2 reduction at dissolved concentrations as low as 1 microm, but this inhibition could be prevent ...19957727395
comparison studies of dinitrogenase reductase adp-ribosyl transferase/dinitrogenase reductase activating glycohydrolase regulatory systems in rhodospirillum rubrum and azospirillum brasilense.reversible adp ribosylation of dinitrogenase reductase, catalyzed by the dinitrogenase reductase adp-ribosyl transferase (drat)/dinitrogenase reductase activating glycohydrolase (drag) regulatory system, has been characterized in both rhodospirillum rubrum and azospirillum brasilense. although the general functions of drat and drag are very similar in these two organisms, there are a number of interesting differences, e.g., in the timing and extent of the regulatory response to different stimuli ...19957730264
properties of the soluble polypeptide of the proton-translocating transhydrogenase from rhodospirillum rubrum obtained by expression in escherichia coli.transhydrogenase, which catalyses the reduction of nadp+ by nadh coupled to proton translocation across a membrane, may be unique in the photosynthetic bacterium rhodospirillum rubrum. unlike the homologous enzyme from animal mitochondria and other bacterial sources, it has a water-soluble polypeptide, which exists as a dimer (ths), that can be reversibly dissociated from the membrane component [williams, r., cotton, n. p. j., thomas, c. m. & jackson, j. b. (1994) microbiology, 140, 1595-1604]. ...19957737169
evidence that some dinoflagellates contain a ribulose-1,5-bisphosphate carboxylase/oxygenase related to that of the alpha-proteobacteria.the ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) large subunit from several dinoflagellates has a structure similar to that of the form ii enzyme from rhodospirillum and rhodobacter species rather than the form i rubisco of eukaryotic algae and higher plants. the dinoflagellate rubisco was identified on native polyacrylamide gels by autoradiographic detection of the stable rubisco-[2'-14c]-2-carboxy-d-arabinitol 1,5-bisphosphate complex. the antibody to the symbiodinium sp. large su ...19957740046
a signature of the oxygenase intermediate in catalysis by ribulose-bisphosphate carboxylase/oxygenase as provided by a site-directed mutant.an uncharacterized minor transient product, observed in our earlier studies of substrate turnover by the e48q mutant of rhodospirillum rubrum ribulose-bisphosphate carboxylase/oxygenase (lee, e. h., harpel, m. r., chen, y.-r., and hartman, f. c. (1993) j. biol. chem. 268, 26583-26591), becomes a major product when it is trapped and stabilized with borate as an additive to the reaction mixture. chemical characterization establishes this novel product as d-glycero-2,3-pentodiulose 1,5-bisphosphate ...19957744819
conformational properties of four peptides corresponding to alpha-helical regions of rhodospirillum cytochrome c2 and bovine calcium binding protein.four peptides corresponding to alpha-helical regions delimited by residues 63-73 and 97-112 of cytochrome c2 (rhodospirillum) and residues 24-36 and 45-55 of bovine calcium binding protein are predicted to be alpha-helical by a recently developed method [rooman, m., kocher, j.p., & wodak, s.j. (1991) j. mol. biol. 221, 961-979], synthesized by solid phase methods, and purified by hplc, and their solution conformations are determined by nmr and cd. the observed conformational properties of these ...19947727367
ionic channel activity induced by fusion of rhodospirillum rubrum chromatophores with a planar bilayer lipid membrane.the present work concerns mechanisms of ionic conductivity of photosynthetic membranes. it is shown that reconstitution of vesicles of photosynthetic membranes (chromatophores) of purple bacteria rhodospirillum rubrum into a planar bilayer lipid membrane leads to fluctuations of current showing the existence of a channel with a predominant conductance of approximately 230 ps in the presence of 100 mm kcl. measurements under the conditions of kcl gradient prove that this channel is cation selecti ...19947506216
expression of tfx and sensitivity to the rhizobial peptide antibiotic trifolitoxin in a taxonomically distinct group of alpha-proteobacteria including the animal pathogen brucella abortus.three phylogenetically distinct groups within the alpha-proteobacteria which differ in trifolitoxin sensitivity are described. trifolitoxin sensitivity was found in strains of agrobacterium, brucella, mycoplana, ochrobactrum, phyllobacterium, rhodobacter, rhodopseudomonas, rhodospirillum, and rhizobium. strains of agrobacterium, brucella, phyllobacterium, rhizobium, and rhodospirillum were capable of producing trifolitoxin upon conjugal transfer of tfxabcdefg.19947527627
picosecond absorbance difference spectra of the antenna of photosynthetic purple bacteria. the influence of exciton interactions and librations.the influence of exciton interactions and pseudolocal librational modes on the relaxation of photo-induced absorption changes of the light-harvesting antenna of the photosynthetic purple bacterium, rhodospirillum rubrum, was studied in the ps time domain. a hypothesis is put forward that the long-lived librational modes can occur in the circular aggregate of light-harvesting bacteriochlorophyll molecules of the core antenna. the model spectra obtained quantitatively fit the shape of the photo-in ...19948200456
synthesis of quinolones and acridones and their inhibitory activity in nadh-dehydrogenases and cytochrome b/c1-complexes. 19948206292
aminomethylenediphosphonate: a potent type-specific inhibitor of both plant and phototrophic bacterial h+-pyrophosphatases.the suitability of different pyrophosphate (ppi) analogs as inhibitors of the vacuolar h+-translocating inorganic pyrophosphatase (v-ppase; ec 3.6.1.1) of tonoplast vesicles isolated from etiolated hypocotyls of vigna radiata was investigated. five 1,1-diphosphonates and imidodiphosphate were tested for their effects on substrate hydrolysis by the v-ppase at a substrate concentration corresponding to the km of the enzyme. the order of inhibitory potency (apparent inhibition constants, kiapp valu ...199412232069
amino acid sequences of cytochromes c2 and c' from the moderately halophilic purple phototrophic bacterium rhodospirillum salexigens.rhodospirillum salexigens is a moderately halophilic purple phototrophic bacterium which grows optimally in 8% nacl. the amino acid sequences of the two principal soluble cytochromes c have been determined. one of these is a cytochrome c2, similar in size to mitochondrial cytochrome c. while clearly of the same sequence class as mitochondrial cytochrome c and the proteins from several other gram-negative bacteria, it does not show particular affinity to any already known sequence in terms of the ...19947893810
tight nucleotide binding sites and atpase activities of the rhodospirillum rubrum rrf1-atpase as compared to spinach chloroplast cf1-atpase.solubilized rhodospirillum rubrum rrf1-atpase, depleted of loosely bound nucleotides, retains 2.6 mol of tightly bound atp and adp/mol of enzyme. incubation of the depleted rrf1 with mg(2+)-atp or mg(2+)-amp-pnp, followed by passage through two successive sephadex centrifuge columns, results in retention of a maximal number of 4 mol of tightly bound nucleotides/mol of rrf1. they include 1.5 mol of nonexchangeable atp, whereas all tightly bound adp is fully exchangeable. a similar retention of on ...19947896772
reversible adp-ribosylation as a mechanism of enzyme regulation in procaryotes.several cases of adp-ribosylation of endogenous proteins in procaryotes have been discovered and investigated. the most thoroughly studied example is the reversible adp-ribosylation of the dinitrogenase reductase from the photosynthetic bacterium rhodospirillum rubrum and related bacteria. a dinitrogenase reductase adp-ribosyltransferase (drat) and a dinitrogenase reductase adp-ribose glycohydrolase (drag) from r. rubrum have been isolated and characterized. the genes for these proteins have bee ...19947898454
bacteriophage t4 encodes a co-chaperonin that can substitute for escherichia coli groes in protein folding.several bacteriophages use the escherichia coli groes and groel chaperonins for folding and assembly of their morphogenetic structures. bacteriophage t4 is unusual in that it encodes a specialized protein (gp31) that is thought to interact with the host groel and to be absolutely required for the correct assembly of the major capsid protein (gp23) in vivo. here we show that despite the absence of amino-acid sequence similarity between gp31 and groes, gp31 can functionally substitute for the groe ...19947908418
characterization of antimycin resistant mutants of rhodospirillum rubrum. 19947911439
comparative study of reaction centers from photosynthetic purple bacteria: electron paramagnetic resonance and electron nuclear double resonance spectroscopy.reaction centers (rcs) from four species of purple bacteria, rhodobacter sphaeroides, rhodobacter capsulatus, rhodospirillum rubrum, and the recently discovered bacterium rhodospirillum centenum, have been characterized by optical spectroscopy [wang, s., lin, x., woodbury, n. w., & allen, j. p. (1994) photosynth. res. (submitted for publication)] and magnetic resonance spectroscopy. all rcs contain a bacteriochlorophyll (bchl) a dimer as the primary donor. for rb. sphaeroides and rs. rubrum the ...19947918428
molecular characterization of two spontaneous antimycin a resistant mutants of rhodospirillum rubrum.antimycin a is an inhibitor of cytochrome bc1 complexes acting at the quinone reducing site (qi) of the cytochrome b subunit. we report here the isolation and molecular characterization of two spontaneous mutants of the purple non-sulfur bacterium rhodospirillum rubrum resistant to this inhibitor. in the two mutants antimycin a resistance was found to be conferred by replacement of an aspartate residue at position 243 of the cytochrome b polypeptide chain, in one case by histidine and in the oth ...19947918532
purification and characterization of an oxygen-stable form of dinitrogenase reductase-activating glycohydrolase from rhodospirillum rubrum.dinitrogenase reductase-activating glycohydrolase (drag) is responsible for removing the adp-ribose moiety from post-translationally inactivated nitrogenase of rhodospirillum rubrum. using drag purified from an overexpressing strain (ur276), further properties of this enzyme were studied, including its u.v.-visible and fluorescence spectra and its stability in air. drag appears to require no covalently bound inorganic cofactors for its activity or regulation. previously, purified drag was found ...19947945205
reconstitution of a functional photosynthetic receptor complex with isolated subunits of core light-harvesting complex and reaction centers.the b820 subunit form of the core light-harvesting complex lhi, isolated from the photosynthetic bacterium rhodospirillum rubrum, was combined in a reassociation assay with the reaction center (rc) isolated from the same or related bacteria. this reassociation produced a photoreceptor complex (prc) which appeared, by absorption spectroscopy, circular dichroism measurements, and kinetic absorption spectroscopy measuring transient photochanges, as analogous to the prc in the intact bacteria. energ ...19947947741
an improved procedure and new vectors for transposon tn5 mutagenesis of the phototrophic bacterium rhodospirillum rubrum.a detailed examination of vectors and procedures used for tn5 mutagenesis of the phototrophic purple non-sulfur bacterium rhodospirillum rubrum has been performed. the mobilizable tn5 suicide vectors currently available show a frequency of tn5 mutagenesis for r. rubrum of approx. 10(-7)-10(-8), approx. 100-1000-fold lower than observed for the related bacteria rhodobacter capsulatus and rhodobacter sphaeroides. using the blue-to-red reversion of a blue-green mutant, r. rubrum st6, containing a s ...19947959072
characterization of a light-responding trans-activator responsible for differentially controlling reaction center and light-harvesting-i gene expression in rhodobacter capsulatus.the purple nonsulfur photosynthetic bacterium rhodobacter capsulatus regulates synthesis of its photosystem in response to two environmental stimuli, oxygen tension and light intensity. here we describe the identification and characterization of the trans-acting regulatory gene hvra, which we show is involved in differentially controlling reaction center and light-harvesting gene expression in response to alterations in light intensity. an hvra mutant strain is shown to lack the capability to tr ...19947961455
changes in the nad(p)h concentration caused by addition of nitrogenase 'switch-off' effectors in rhodospirillum rubrum g-9, as measured by fluorescence.the effect of nitrogenase 'switch-off' effectors on the concentration of nad(p)h in rhodospirillum rubrum g-9 was investigated by fluorescence. a rapid decrease in fluorescence was observed when cells, either n2-grown or nitrogen-starved, were subjected to the effectors, but not when sodium chloride or tris buffer was added. no effects on the fluorescence were observed in non-nitrogen fixing cultures except when nad+ was added. the results strongly indicate that the redox state of the pyridine n ...19947988717
the effect of sulfite on the atp hydrolysis and synthesis activity of membrane-bound h(+)-atp synthase from various species.the action of sulfite on atp hydrolysis and synthesis activities is investigated in membrane vesicles prepared from the cyanobacterium synechococcus 6716, chromatophores from the photosynthetic purple bacterium rhodospirillum rubrum, membrane vesicles from the related non-photosynthetic bacterium paracoccus denitrificans, and bovine heart submitochondrial particles. without any further pretreatment atp hydrolysis is stimulated by sulfite in all four membrane preparations. typically atp synthesis ...19948002977
a structural role for arginine in proteins: multiple hydrogen bonds to backbone carbonyl oxygens.we propose that arginine side chains often play a previously unappreciated general structural role in the maintenance of tertiary structure in proteins, wherein the positively charged guanidinium group forms multiple hydrogen bonds to backbone carbonyl oxygens. using as a criterion for a "structural" arginine one that forms 4 or more hydrogen bonds to 3 or more backbone carbonyl oxygens, we have used molecular graphics to locate arginines of interest in 4 proteins: arg 180 in thermus thermophilu ...19948003972
the photoactive yellow protein from ectothiorhodospira halophila as studied with a highly specific polyclonal antiserum: (intra)cellular localization, regulation of expression, and taxonomic distribution of cross-reacting proteins.a rabbit antiserum was raised against the photoactive yellow protein (pyp) from ectothiorhodospira halophila and purified by adsorption experiments to obtain a highly specific polyclonal antiserum. this antiserum was used to obtain the following results. (i) in e. halophila, pyp can be isolated from the fraction of soluble proteins. in the intact cell, however, pyp appeared to be associated with (intra)cytoplasmic membranes, as was concluded from analysis of immunogold-labelled thin sections of ...19948021174
interaction between cytochrome c2 and reaction centers from purple bacteria.the kinetics of electron transfer of cytochrome c2 from rhodobacter sphaeroides, rhodobacter capsulatus, and rhodospirillum centenum to reaction centers from rb. sphaeroides and rb. capsulatus have been measured. observed in the kinetics of decay of the oxidized donor are a rapid first-order rate and one or more slower rates that are due to diffusion-limited complex formation. for reaction centers from rb. sphaeroides, the fast component had time constants of 1.0 and 0.5 microsecond for cytochro ...19948031763
energy migration and trapping in a spectrally and spatially inhomogeneous light-harvesting antenna.in this paper, we analyze the process of excitation energy migration and trapping by reaction centres in photosynthesis and discuss the mechanisms that may provide an overall description of this process in the photosynthetic bacterium rhodospirillum (rs.) rubrum and related organisms. a wide range of values have been published for the pigment to pigment transfer rate varying from less than 1 ps up to 10 ps. these differences occur because the interpretation of trapping measurements depend on the ...19948061207
photosynthetic deficiency of a pufx deletion mutant of rhodobacter sphaeroides is suppressed by point mutations in the light-harvesting complex genes pufb or pufa.the pufx gene of the facultative phototroph rhodobacter sphaeroides encodes a membrane protein that is required for photoheterotrophic growth. deletion of pufx impairs the photosynthetic generation of a transmembrane potential, suggesting a role for the pufx protein in light-driven cyclic electron transfer [farchaus, j. w., et al. (1992) embo j. 11, 2779-2788]. here we describe the isolation and characterization of 65 spontaneous suppressor mutants in which photosynthetic competence was restored ...19948068653
cloning and sequencing of the genes for the proton-translocating nicotinamide nucleotide transhydrogenase from rhodospirillum rubrum and the implications for the domain structure of the enzyme.the genes for the proton-translocating nicotinamide nucleotide transhydrogenase from rhodospirillum rubrum have been cloned using a probe constructed with the polymerase chain reaction, genomic dna as target and oligonucleotide primers corresponding to amino acid sequence obtained from the purified soluble subunit. there is a cluster of three genes, designated pntaa, pntab and pntb, whose translation products indicate polypeptides of 384, 139 and 464 amino acids, respectively. this contrasts wit ...19948075801
posttranslational modification of nitrogenase. differences between the purple bacterium rhodospirillum rubrum and the cyanobacterium anabaena variabilis.in the photosynthetic bacteria rhodospirillum rubrum and rhodopseudomonas capsulatus post-translational regulation of nitrogenase is due to adp-ribosylation of the fe-protein, the dinitrogenase reductase [burris, r. h. (1991) j. biol. chem. 266, 9339-9342]. this mechanism has been assumed to be responsible for nitrogenase modification in a variety of organisms. in the present study, we examined whether adp-ribosylation holds true for the filamentous cyanobacterium anabaena variabilis. genes codi ...19948119279
identification of the myxococcus xanthus 59-kda membrane-associated gtp-binding protein as a proton-translocating atpase.five gtp-binding proteins have been detected in myxococcus xanthus by photoaffinity cross-linking with azido-gtp [muñoz-dorado et al., j. biol. chem. 265 (1990a) 2702-2706]. one of them, the 59-kda membrane-associated gtp-binding protein, has been purified. the n-terminal sequence of a 10-kda fragment from the protease v8 digestion of the purified protein has been determined and degenerate oligodeoxyribonucleotides based on that sequence have been used to isolate and clone the gene that encodes ...19948125291
energy transfer in the inhomogeneously broadened core antenna of purple bacteria: a simultaneous fit of low-intensity picosecond absorption and fluorescence kinetics.the excited state decay kinetics of chromatophores of the purple photosynthetic bacterium rhodospirillum rubrum have been recorded at 77 k using picosecond absorption difference spectroscopy under strict annihilation free conditions. the kinetics are shown to be strongly detection wavelength dependent. a simultaneous kinetic modeling of these experiments together with earlier fluorescence kinetics by numerical integration of the appropriate master equation is performed. this model, which account ...19948130341
beta-elimination of phosphate from reaction intermediates by site-directed mutants of ribulose-bisphosphate carboxylase/oxygenase.five residues (thr-53, asn-54, gly-370, gly-393, and gly-394) of rhodospirillum rubrum ribulose-bisphosphate carboxylase/oxygenase are positioned to serve as hydrogen-bond donors for the c1 phosphate of ribulose bisphosphate and thereby constrain conformational flexibility of the initial enediol(ate) intermediate (knight, s., andersson, i., and brändén, c.-i. (1990) j. mol. biol. 215, 113-160). to study the functional contributions of the residues implicated in ribulose bisphosphate binding and ...19948157638
thermodynamics of membrane polypeptide oligomerization in light-harvesting complexes and associated structural changes.investigation of the equilibrium between the dissociated b777 form of the light-harvesting complex of rhodospirillum rubrum and the oligomeric b820 form demonstrates that the b777 form consists of bacteriochlorophyll a (bchl) bound to the alpha or beta polypeptide chains; this binding appears to be reasonably stable at room temperature with little dissociation to free bchl and polypeptides. analysis of the reaction order for the b777 association reaction to form b820 shows that this reaction req ...19948176735
anaerobic bacteria from hypersaline environments.strictly anaerobic halophiles, namely fermentative, sulfate-reducing, homoacetogenic, phototrophic, and methanogenic bacteria are involved in the oxidation of organic carbon in hypersaline environments. to date, six anaerobic fermentative genera, containing nine species, have been described. two of them are homoacetogens. six species belong to the family haloanaerobiaceae, as indicated by their unique 16s rrna oligonucleotide sequences. desulfohalobium retbaense and desulfovibrio halophilus repr ...19948177169
chemical rescue by exogenous amines of a site-directed mutant of ribulose 1,5-bisphosphate carboxylase/oxygenase that lacks a key lysyl residue.ligand binding to ribulose 1,5-bisphosphate carboxylase/oxygenase immobilizes the flexible loop 6 of the beta/alpha barrel domain in its closed conformation. lys329, located at the apex of this loop, interacts electrostatically with glu48 of the adjacent subunit and with the co2-derived carboxylate of the carboxylated reaction intermediate [knight et al. (1990) j. mol. biol. 215, 113-160]. previous studies have implicated lys329 in the addition of co2 to the initial enediol(ate) intermediate: mu ...19948180178
differentiation of brucella abortus bv. 1, 2, and 4, brucella melitensis, brucella ovis, and brucella suis bv. 1 by pcr.several pcr assays which identify the genus brucella but do not discriminate among species have been reported. we describe a pcr assay that comprises five oligonucleotide primers which can identify selected biovars of four species of brucella. individual biovars within a species are not differentiated. the assay can identify three biovars (1, 2, and 4) of b. abortus, all three biovars of b. melitensis, biovar 1 of b. suis, and all b. ovis biovars. these biovars include all of the brucella specie ...19947852552
molecular relationship of an atypical azospirillum strain 4t to other azospirillum species.dna/dna hybridization, plasmid content and partial 16s rdna sequence were determined to confirm the relationship between two azospirillum strains, 4b and 4t, isolated from the same rice rhizosphere. the partial 16s rdna sequence was determined for 9 strains belonging to 5 azospirillum species which included azospirillum lipoferum strains 4b and 4t, and was compared to a set of ribosomal sequences from other bacteria of the alpha subdivision of the proteobacteria. four azospirillum species sequen ...19947871242
studies on reconstitution of the rhodospirillum rubrum nicotinamide nucleotide transhydrogenase.the energy-transducing nicotinamide nucleotide transhydrogenase of rhodospirillum rubrum is composed of 3 subunits alpha 1, alpha 2 and beta, with m(r) values, respectively, of 40.3, 14.9 and 47.8 kda. subunit alpha 1 is water-soluble, loosely bound to chromatophores, and can be easily and reversibly removed. subunits alpha 2 and beta are integral membrane proteins, and their removal from chromatophores requires the use of detergents. treatment of chromatophores with various detergents inhibited ...19947696982
energy-transducing nicotinamide nucleotide transhydrogenase: nucleotide sequences of the genes and predicted amino acid sequences of the subunits of the enzyme from rhodospirillum rubrum.based on the amino acid sequence of the n-terminus of the soluble subunit of the rhodospirillum rubrum nicotinamide nucleotide transhydrogenase, two oligonucleotide primers were synthesized and used to amplify the corresponding dna segment (110 base pairs) by the polymerase chain reaction. using this pcr product as a probe, one clone with the insert of 6.4 kbp was isolated from a genomic library of r. rubrum and sequenced. this sequence contained three open reading frames, constituting the genes ...19947844118
cloning and sequence of the l2 form of rubisco from a marine obligately autotrophic hydrogen-oxidizing bacterium, hydrogenovibrio marinus strain mh-110.a form ii ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) gene was isolated and sequenced from a marine hydrogen-oxidizing bacterium, hydrogenovibrio marinus strain mh-110. to our knowledge, this is the first report for the sequence of a form ii (l2-form) rubisco gene derived from a chemolithoautotrophic bacterium. the form ii rubisco gene coded for 463 amino acid residues (1389 bp, m(r) = 50,655). the deduced amino acid sequence had high homology with those of the l2-form rubisco of r ...19947765489
optimization of the sistrom culture medium for large-scale batch cultivation of rhodospirillum rubrum under semiaerobic conditions with maximal yield of photosynthetic membranes.the defined medium a of w. r. sistrom (w. r. sistrom, j. gen. microbiol. 22:77-85, 1960) has been modified to allow the growth of rhodospirillum rubrum in large-scale batch cultures under dark, semiaerobic conditions. the simultaneous use of two substrates, nh(4)-succinate (46 mm) and fructose (0.3%), which are utilized in aerobic and fermentative metabolism, respectively, leads to very high cell densities with a maximal yield of photosynthetic membranes.199416349265
increased nitrogenase-dependent h(2) photoproduction by hup mutants of rhodospirillum rubrum.transposon tn5 mutagenesis was used to isolate mutants of rhodospirillum rubrum which lack uptake hydrogenase (hup) activity. three tn5 insertions mapped at different positions within the same 13-kb ecori fragment (fragment e1). hybridization experiments revealed homology to the structural hydrogenase genes hupslm from rhodobacter capsulatus and hupsl from bradyrhizobium japonicum in a 3.8-kb ecori-clai subfragment of fragment e1. it is suggested that this region contains at least some of the st ...199416349271
modification of the fe protein of nitrogenase in natural populations of trichodesmium thiebautii.the fe protein of nitrogenase in the marine nonheterocystous cyanobacterium trichodesmium thiebautii is interconverted between two forms, which is reminiscent of the adp-ribosylation described in the purple bacterium rhodospirillum rubrum. in natural populations of t. thiebautii during the day, when nitrogenase activity (na) is present and while photosynthetic rates are high, a low-molecular-mass form of the fe protein is present. in the late afternoon, the low-molecular-mass form is partially c ...199316348883
photosynthetic fractionation of the stable isotopes of oxygen and carbon.isotope discrimination during photosynthetic exchange of o2 and co2 was measured using enzyme, thylakoid, and whole cell preparations. evolved oxygen from isolated spinach thylakoids was isotopically identical (within analytical error) to its source water. similar results were obtained with anacystis nidulans richter and phaeodactylum tricornutum bohlin cultures purged with helium. for consumptive reactions, discrimination ([delta], where 1 + [delta]/1000 equals the isotope effect, k16/k18 or k1 ...199312231663
amino acid sequence similarities between the vacuolar proton-pumping inorganic pyrophosphatase and the c-subunit of f0f1-atpases.comparison of the arabidopsis thaliana vacuolar proton-pumping inorganic pyrophosphatase with three f0f1-atpase c-subunits revealed a strong similarity between a stretch containing amino acids 227-245 of the h(+)-ppase and a transmembrane alpha-helix of the c-subunits which contains the glutamate which binds n,n'-dicyclohexylcarbodiimide.19938199778
construction of a synechocystis pcc6803 mutant suitable for the study of variant hexadecameric ribulose bisphosphate carboxylase/oxygenase enzymes.the cyanobacterium synechocystis pcc6803 was chosen as a target organism for construction of a suitable photosynthetic host to enable selection of variant plant-like ribulose bisphosphate carboxylase/oxygenase (rubisco) enzymes. the dna region containing the operon encoding rubisco (rbc) was cloned, sequenced and used for the construction of a transformation vector bearing flanking sequences to the rbc genes. this vector was utilized for the construction of a cyanobacterial rbc null mutant in wh ...19938219082
surface charge modifications do not affect the hydrolytic activity of membrane-bound pyrophosphatase of rhodospirillum rubrum.the surface charge of the membrane of chromatophores of rhodospirillum rubrum was modified by two methods: fusion of liposomes with the membrane of the chromatophore by changing the ph and by incubating chromatophores in the presence of cationic or anionic detergents. the hydrolytic activity of membrane-bound pyrophosphatase, on surface charge modified chromatophores, did not change the km of the enzyme for its substrate (mg-ppi2-) nor the activation effect of free mg2+ on the hydrolytic activit ...19938220258
the ratio of protons translocated/hydride ion equivalent transferred by nicotinamide nucleotide transhydrogenase in chromatophores from rhodospirillum rubrum.the reduction of acetylpyridine adenine dinucleotide (acpdad+, an nad+ analogue) by nadph, in chromatophores treated with valinomycin, was accompanied by alkalinisation of the external medium, as measured by the absorbance change of added cresol red, a simple, non-binding ph indicator. experiments with a stopped-flow spectrophotometer showed that initial (linear) rates of alkalinisation persisted for 1-2s. from the results of experiments in which h+ uptake was driven by a series of short flashes ...19938223619
photolithoautotrophic growth and control of co2 fixation in rhodobacter sphaeroides and rhodospirillum rubrum in the absence of ribulose bisphosphate carboxylase-oxygenase.rhodospirillum rubrum and rhodobacter sphaeroides were shown to be capable of photolithoautotrophic growth in the absence of the reductive pentose phosphate (calvin) cycle. ribulose 1,5-bisphosphate carboxylase-oxygenase (rubisco) deletion strains were incapable of photolithoautotrophic growth using hydrogen as an electron donor but were able to grow in the absence of organic carbon using less reduced inorganic electron donors, i.e., thiosulfate or sulfide. wild-type r. rubrum grown in the prese ...19938226655
atomic structure of a cytochrome c' with an unusual ligand-controlled dimer dissociation at 1.8 a resolution.the crystallographic structure of cytochrome c' from the purple phototrophic bacterium chromatium vinosum (cvcp) has been determined at 1.8 a resolution using multiple isomorphous replacement. the molecule is a dimer, with each 131-residue chain folding as a four-helical bundle incorporating a covalently bound heme group at the core. this structure is the third of the ubiquitous cytochromes c' to be solved and is similar to the known structures of cytochrome c' from r. molischianum (rmcp) and r. ...19938230224
perturbation of reaction-intermediate partitioning by a site-directed mutant of ribulose-bisphosphate carboxylase/oxygenase.to explore the roles of active-site glu48 of ribulose-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum, the e48q mutant has been characterized with respect to kinetics and product distribution. although the kcat for carboxylase activity is only 0.6% of the wild-type value, the mutant retains full activity in catalyzing the conversion of the carboxylated reaction intermediate to 3-phosphoglycerate and retains 10% of the normal activity in catalyzing the enolization of ribulose bispho ...19938253788
atpase of rhodospirillum rubrum requires three functional copies of beta subunit as determined by radiation inactivation analysis.radiation inactivation analysis yielded a functional unit of 170 +/- 26 kda as beta subunit of atpase was irradiated and then reconstituted to beta-depleted chromatophores of rhodospirillum rubrum. a functional size of 132 +/- 17 kda for the beta-depleted atpase moiety involved in atp hydrolysis reaction was also determined. when both purified beta subunit and beta-depleted chromatophore were irradiated separately, reconstituted, and then activity measured, the functional mass was 312 +/- 50 kda ...19938260936
the dratg gene region of rhodobacter capsulatus is required for post-translational regulation of both the molybdenum and the alternative nitrogenase.synthetic oligonucleotides, which were designed according to amino acid sequences conserved between rhodospirillum rubrum and azospirillum brasilense drat and drag, respectively, were used to identify the corresponding genes of rhodobacter capsulatus. sequence analysis of a 1904 bp dna fragment proved the existence of r. capsulatus drat and drag. these two genes were separated by 11 bp only, suggesting that r. capsulatus drat and drag were part of one transcriptional unit. in contrast to r. rubr ...19938277250
the source and characteristics of chemiluminescence associated with the oxygenase reaction catalyzed by mn(2+)-ribulosebisphosphate carboxylase.we confirm the observation of mogel and mcfadden (mogel, s.n., and mcfadden, b. a. (1990) biochemistry 29, 8333-8337) that ribulosebisphosphate carboxylase/oxygenase (rubisco) exhibits chemiluminescence while catalyzing its oxygenase reaction in the presence of mn2+. however, our results with the spinach and rhodospirillum rubrum enzymes differ markedly in the following respects. 1) chemiluminescence intensity was directly proportional to enzyme concentration and behaved as if representing the r ...19938314755
Displaying items 601 - 700 of 2252