Publications

TitleAbstractYear(sorted ascending)
Filter
PMID
Filter
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
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
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
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
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
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
the alpha beta dimer-catalytic unit of the f1-atpase. 19958654713
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
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
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
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
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
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
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
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
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
spectroscopic characterization of nitrosylheme in nitric oxide complexes of ferric and ferrous cytochrome c' from photosynthetic bacteria.reactions of ferric and ferrous cytochromes c' from four photosynthetic bacteria (rhodobacter capsulatus atcc 11166, rhodopseudomonas palustris atcc 17001, rhodospirillum rubrum atcc 11170, and chromatium vinosum atcc 17899) with nitric oxide have been investigated by electronic absorption and electron paramagnetic resonance spectroscopies. the heme iron(iii) of these ferric cytochromes c' has been recently reported to be in a quantum mechanically admixed (s = 5/2, 3/2) state [fujii, s., yoshimu ...19968547347
characterization of a co-responsive transcriptional activator from rhodospirillum rubrum.in rhodospirillum rubrum, co induces the expression of at least two transcripts that encode an enzyme system for co oxidation. this regulon is positively regulated by cooa, which is a member of the camp receptor protein family of transcriptional regulators. the transcriptional start site of one of the transcripts (coofsctj) has been identified by primer extension. the ability of cooa to bind to this promoter in vitro was characterized with dnase i footprinting experiments using extracts of a coo ...19968550545
estimation of the h+/h- ratio of the reaction catalysed by the nicotinamide nucleotide transhydrogenase in chromatophores from over-expressing strains of rhodospirillum rubrum and in liposomes inlaid with the purified bovine enzyme.two strains of rhodospirillum rubrum were constructed in which, by a gene dosage effect, the transhydrogenase activity of isolated chromatophores was increased 7-10-fold and 15-20-fold, respectively. the h+/h- ratio (the ratio of protons translocated per hydride ion equivalent transferred from nadph to an nad+ analogue, acetyl pyridine adenine dinucleotide), determined by a spectroscopic technique, was approximately 1.0 for chromatophores from the over-expressing strains, but was only approximat ...19968573594
occurrence of polyhydroxyalkanoic acid granule-associated proteins related to the alcaligenes eutrophus h16 ga24 protein in other bacteria.fifty different polyhydroxyalkanoic acid (pha)-accumulating bacterial strains were investigated for the occurrence of phasin proteins bound to pha granules and related to the ga24 protein of alcaligenes eutrophus h16, by isolating pha granules and western blot analysis of granule-associated proteins employing antibodies raised against the ga24 protein. it could be demonstrated that th pha granules of many poly(3-hydroxybutyrate)-accumulating bacteria exhibited a similar protein pattern, and a pr ...19968598273
comparison of the structural requirements for bacteriochlorophyll binding in the core light-harvesting complexes of rhodospirillum rubrum and rhodospirillum sphaeroides using reconstitution methodology with bacteriochlorophyll analogs.bacteriochlorophyll (bchl) structural requirements for formation of the core light-harvesting complex (lh1) and its structural subunit complex were examined by reconstitution with bchl analogs and the alpha- and beta-polypeptides of rhodospirillum rubrum and rhodobacter sphaeroides. comparable results were obtained with most of the bchl analogs and the polypeptides of each bacterium, indicating the conservation of bchl binding sites. these systems showed the following common requirements for for ...19968608148
sequence evidence for strong conservation of the photoactive yellow proteins from the halophilic phototrophic bacteria chromatium salexigens and rhodospirillum salexigens.the photoactive yellow proteins (pyp) have been found to date only in three species of halophilic purple phototrophic bacteria. they have photochemical activity remarkably similar to that of the bacteria rhodopsins. in contrast to rhodopsins, however, the pyps are small water-soluble proteins. we now report the complete amino acid sequences of rhodospirillum salexigens and chromatium salexigens pyp which allow comparison with the known sequence and three-dimensional structure of the prototypic p ...19968611556
development of gene transfer methods for rubrivivax gelatinosus s1: construction, characterization and complementation of a puf operon deletion strain.gene transfer systems were developed in rubrivivax (rx.) gelatinosus s1. first, a system for conjugative transfer of mobilizable plasmids from escherichia coli to rx. gelatinosus s1 was established. secondly, optimal conditions for the transformation of rx. gelatinosus s1 by electroporation were determined. a delta puf strain was constructed. complementation with the puf operon from a wild-type strain cloned in a replicative plasmid restored photosynthetic growth. two insertion strains were also ...19968879238
mutants that show increased sensitivity to hydrogen peroxide reveal an important role for the pentose phosphate pathway in protection of yeast against oxidative stress.we have isolated several mutants of saccharomyces cerevisiae that are sensitive to oxidative stress in a screen for elevated sensitivity to hydrogen peroxide. two of the sixteen complementation groups obtained correspond to structural genes encoding enzymes of the pentose phosphate pathway. allelism of the pos10 mutation (pos for peroxide sensitivity) to the zwf1/met1 mutants in the structural gene for glucose 6-phosphate dehydrogenase was reported previously. the second mutation, pos18, was com ...19968879247
characterization of the region encoding the co-induced hydrogenase of rhodospirillum rubrum.in the photosynthetic bacterium rhodospirillum rubrum, the presence of carbon monoxide (co) induces expression of several proteins. these include carbon monoxide dehydrogenase (codh) and a co-tolerant hydrogenase. together these enzymes catalyze the following conversion: co + h2o --> co2 + h2. this system enables r. rubrum to grow in the dark on co as the sole energy source. expression of this system has been shown previously to be regulated at the transcriptional level by co. we have now identi ...19968892819
properties of the purified, recombinant, nadp(h)-binding domain iii of the proton-translocating nicotinamide nucleotide transhydrogenase from rhodospirillum rubrum.transhydrogenase comprises three domains. domains i and iii are peripheral to the membrane and possess the nad(h)- and nadp(h)-binding sites, respectively, and domain ii spans the membrane. domain iii of transhydrogenase from rhodospirillum rubrum was expressed at high levels in escherichia coli, and purified. the purified protein was associated with substoichiometric quantities of tightly bound nadp+ and nadph. fluorescence spectra of the domain iii protein revealed emissions due to tyr residue ...19968898902
facilitation of the terminal proton transfer reaction of ribulose 1,5-bisphosphate carboxylase/oxygenase by active-site lys166.the terminal step in the carboxylation pathway catalyzed by ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) is stereospecific protonation of the c-2 aci-acid of 3-phosphoglycerate (pga). x-ray crystallographic results favor the epsilon-amino group of lys166 as the proton donor in this step [knight et al. (1990) j. mol. biol. 215, 113]. nonetheless, position-166 mutants are able to catalyze forward processing of isolated 2-carboxy-3-ketoarabinitol 1,5-bisphosphate (ckabp), the carboxyla ...19968909282
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
rubisco, an old challenge with new perspectives. 19968663895
expression of the puf operon in an aerobic photosynthetic bacterium, roseobacter denitrificans.the effects of oxygen and light on the expression of the puf operon were investigated in roseobacter denitrificans in a comparison with those in rhodobacter sphaeroides. in darkness, the levels of the total puf mrna in ros. denitrificans were about 1.3 times those in rb. sphaeroides at low concentrations of oxygen, reflecting the accumulation of bacteriochlorophyll and carotenoids. the oxygen tension, up to 94% saturation of dissolved oxygen, did not affect the levels of the total puf transcript ...19968665093
the xanthopsins: a new family of eubacterial blue-light photoreceptors.photoactive yellow protein (pyp) is a photoreceptor that has been isolated from three halophilic phototrophic purple bacteria. the pyp from ectothiorhodospira halophila bn9626 is the only member for which the sequence has been reported at the dna level. here we describe the cloning and sequencing of the genes encoding the pyps from e.halophila sl-1 (type strain) and rhodospirillum salexigens. the latter protein contains, like the e.halophila pyp, the chromophore trans p-coumaric acid, as we show ...19968670821
a peptidoglycan binding domain in the porin-associated protein (pap) of rhodospirillum rubrum fr1.the porin-associated protein of rhodospirillum rubrum fr1 was found to contain a peptidoglycan binding motif. a partial fragment of 179 amino acids, obtained by cleavage of pap with trypsin, asp-n protease, and cnbr, was sequenced. substantial sequence homology was found of the c-terminal part (residues 126-179) of porin-associated protein with ompa, the peptidoglycan-associated lipoprotein of several bacteria, protein f of pseudomonas aeruginosa, and piii of neisseria gonorrhoeae, the latter be ...19968674970
high-resolution crystal structures of two polymorphs of cytochrome c' from the purple phototrophic bacterium rhodobacter capsulatus.the structures of two polymorphs of cytochrome c' from rhodobacter capsulatus (rccp) strain m110 have been determined by the molecular replacement method. iron anomalous scattering data were used to confirm the molecular replacement solution. the structures were refined at 1.72 angstrom and 2.0 angstrom resolution to r-values of 15.0% and 16.3%, respectively. the rccp molecule is a dimer and each of the identical 129 residue subunits folds as a four-helical bundle with a covalently bound heme gr ...19968676382
molecular cloning, dna sequence and transcriptional analysis of the rhodospirillum molischianum b800/850 light-harvesting genes.the amino acid sequences of the b800/850 light-harvesting proteins from rhodospirillum molischianum were determined by edman degradation. on the basis of these amino acid sequences, two degenerated oligonucleotides were synthesized and used for pcr of genomic dna. the resulting 150 bp dna fragment was cloned, sequenced and used for subsequent southern blot analysis of digested genomic dna. a 2.3 kbp ecori fragment strongly hybridized to the probe and a size selected genomic library from genomic ...19968695630
formation of the light-harvesting complex i (b870) of anoxygenic phototrophic purple bacteria.the light-harvesting (lh) complex i (b870) of anoxygenic photosynthetic purple bacteria is the oligomeric form of its subunit b820 consisting of the low-molecular-weight polypeptides alpha, beta, bacteriochlorophyll (bchl), and carotenoids in the stoichiometric ratio [alpha1 beta1 (bchl2) crt1-2]n. lhi surrounds the photochemical reaction center (rc). the major absorption band of the lhi complex is species-specific and is found at 870-890 nm; those of the subunit and the monomeric bchl a (dissol ...19968703191
evidence for a proximal histidine interaction in the structure of cytochromes c in solution: a resonance raman study.soret-excited resonance raman (rr) spectra of oxidized and reduced cytochromes ć from rhodospirillum molischianum and rhodobacter sphaeroides, in solution, are reported. the spectra of the type i ferricytochromes ć in both species contain different extents of two forms. one of these is readily assignable to a "normal" five-coordinated high-spin heme. the second species with v3 and v10 modes at 1502 and 1635 cm-1, respectively, is attributed to a five-coordinated intermediate-spin heme. the rr da ...19968703928
transcription of the glnb and glna genes in the photosynthetic bacterium rhodospirillum rubrum.the pii protein, encoded by glnb, has a central role in the control of nitrogen metabolism in nitrogen-fixing prokaryotes. the glnb gene of rhodospirillum rubrum was isolated and sequenced. the deduced amino acid sequence had very high sequence identity to other pii proteins. the glna gene, encoding glutamine synthetase, was located 135 bp downstream of glnb and was partially sequenced. glnb is cotranscribed with glna from a promoter with high similarity to the sigma 54-dependent promoter consen ...19968704966
rubisco in marine symbiotic dinoflagellates: form ii enzymes in eukaryotic oxygenic phototrophs encoded by a nuclear multigene family.genes encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) were cloned from dinoflagellate symbionts (symbiodinium spp) of the giant clam tridacna gigas and characterized. strikingly, symbiodinium rubisco is completely different from other eukaryotic (form i) rubiscos: it is a form ii enzyme that is approximately 65% identical to rubisco from rhodospirillum rubrum (rubisco forms i and ii are approximately 25 to 30% identical); it is nuclear encoded by a multigene family; and the pr ...19968721755
identification and sequence of a nifj-like gene in rhodospirillum rubrum: partial characterization of a mutant unaffected in nitrogen fixation.a nifj-like gene was identified in the photosynthetic purple non-sulphur bacterium rhodospirillum rubrum. a dna segment hybridizing to klebsiella pneumoniae nifj was isolated, the gene was inactivated, and a mutant strain, snj-1, was constructed by allele replacement. the mutation was confirmed by dna sequencing. northern blotting and by the lack of pyruvate oxidoreductase activity. this is the first report of a nifj-like gene in photosynthetic bacteria. unexpectedly, snj-1 was capable of nitrog ...19968736535
the crystal structure of the light-harvesting complex ii (b800-850) from rhodospirillum molischianum.the light-harvesting complexes ii (lh-2s) are integral membrane proteins that form ring-like structures, oligomers of alpha beta-heterodimers, in the photosynthetic membranes of purple bacteria. they contain a large number of chromophores organized optimally for light absorption and rapid light energy migration. recently, the structure of the nonameric lh-2 of rhodopseudomonas acidophila has been determined; we report here the crystal structure of the octameric lh-2 from rhodospirillum molischia ...19968736556
kinetic characterization of the hydrolytic activity of the h+-pyrophosphatase of rhodospirillum rubrum in membrane-bound and isolated states.substrate hydrolysis by the h+-pyrophosphatase (pyrophosphate phosphohydrolase, h+-ppase) of the photosynthetic bacterium rhodospirillum rubrum follows a two-pathway reaction scheme in which preformed 1:1 and 1:2 . enzyme . mg2+ complexes (emg and emg2) convert dimagnesium pyrophosphate (the substrate). this scheme is applicable to isolated enzyme, uncoupled chromatophores and chromatophores energized by a k+/valinomycin diffusion potential. tris and other amine buffers exert a specific effect o ...19968617255
cloning, sequencing and transcriptional regulation of the drat and drag genes of azospirillum lipoferum fs.from azospirillum lipoferum (al) fs, a nitrogen-fixing bacterium isolated from the rhizosphere of rice, we cloned and sequenced drat, encoding dinitrogenase reductase adp-ribosyltransferase, and drag, encoding dinitrogenase reductase-activating glycohydrolase. the nucleotide sequences of dratg showed extensive similarity to the same genes from azospirillum brasilense, rhodospirillum rubrum and rhodobacter capsulatus, and they are assumed to be co-transcribed as a single operon. when this dratg o ...19968621068
consequences for the organization of reaction center-light harvesting antenna 1 (lh1) core complexes of rhodobacter sphaeroides arising from deletion of amino acid residues from the c terminus of the lh1 alpha polypeptide.the light harvesting antenna 1 (lh1) complex of rhodobacter sphaeroides is intimately associated with the reaction center (rc) as part of the reaction center rc-lh1 core complex. the pufa gene has been modified such that between 5 and 16 amino acid residues were progressively deleted from the c terminus of the lh1 alpha polypeptide. the two largest deletions produced strains which were deficient in lh1. the remaining four deletion mutants exhibited significant reductions in the average level of ...19968621732
characterization of the co-induced, co-tolerant hydrogenase from rhodospirillum rubrum and the gene encoding the large subunit of the enzyme.in the presence of carbon monoxide, the photosynthetic bacterium rhodospirillum rubrum induces expression of proteins which allow the organism to metabolize carbon monoxide in the net reaction co + h2o --> co2 + h2. these proteins include the enzymes carbon monoxide dehydrogenase (codh) and a co-tolerant hydrogenase. in this paper, we present the complete amino acid sequence for the large subunit of this hydrogenase and describe the properties of the crude enzyme in relation to other known hydro ...19968626276
spectroelectrochemical characterization of the metal centers in carbon monoxide dehydrogenase (codh) and nickel-deficient codh from rhodospirillum rubrum.carbon-monoxide dehydrogenase (codh) from rhodospirillum rubrum contains two metal centers: a ni-x-[fe4s4]2+/1+ cluster (c-center) that serves as the cooxidation site and a standard [fe4s4]2+/1+ cluster (b-center) that mediates electron flow from the c-center to external electron acceptors. four states of the c-center were previously identified in electron paramagnetic resonance (epr) and mössbauer studies. in this report, epr-redox titrations demonstrate that the fully oxidized, diamagnetic for ...19968626477
interaction of nucleotides with the nad(h)-binding domain of the proton-translocating transhydrogenase of rhodospirillum rubrum.transhydrogenase catalyzes the reduction of nadp+ by nadh coupled to the translocation of protons across a membrane. the polypeptide composition of the enzyme in rhodospirillum rubrum is unique in that the nad(h)-binding domain (called ths) exists as a separate polypeptide. ths was expressed in escherichia coli and purified. the binding of nucleotide substrates and analogues to ths was examined by one-dimensional proton nuclear magnetic resonance (nmr) spectroscopy and by measuring the quenching ...19968626568
mutation of tyr235 in the nad(h)-binding subunit of the proton-translocating nicotinamide nucleotide transhydrogenase of rhodospirillum rubrum affects the conformational dynamics of a mobile loop and lowers the catalytic activity of the enzyme.the tyr residue in the mobile loop region of the soluble, domain i polypeptide (called ths) of the proton-translocating transhydrogenase from rhodospirillum rubrum has been substituted by asn and by phe. the recombinant proteins were expressed at high levels in escherichia coli and purified to homogeneity. the two well defined resonances at 6.82 and 7.12ppm, observed in the one-dimensional proton nmr spectrum of wild-type protein, and previously attributed to the tyr residue, were absent in both ...19968626569
presence of a second mechanism for the posttranslational regulation of nitrogenase activity in azospirillum brasilense in response to ammonium.although adp-ribosylation of dinitrogenase reductase plays a significant role in the regulation of nitrogenase activity in azospirillum brasilense, it is not the only mechanism of that regulation. the replacement of an arginine residue at position 101 in the dinitrogenase reductase eliminated this adp-ribosylation and revealed another regulatory system. while the constructed mutants had a low nitrogenase activity, nh4+ still partially inhibited their nitrogenase activity, independent of the dini ...19968631686
purification and characterization of the alternative nitrogenase from the photosynthetic bacterium rhodospirillum rubrum.the alternative nitrogenase from a nifh mutant of the photosynthetic bacterium rhodospirillum rubrum has been purified and characterized. the dinitrogenase protein (anf1) contains three subunits in an apparent alpha2beta2gamma2 structure and contains fe but no mo or v. a factor capable of activating apo-dinitrogenase (lacking the femo cofactor) from azotobacter vinelandii was extracted from the alternative dinitrogenase protein with n-methylformamide. the electron paramagnetic resonance (epr) si ...19968631723
directed mutagenesis of the rhodobacter capsulatus puha gene and orf 214: pleiotropic effects on photosynthetic reaction center and light-harvesting 1 complexes.rhodobacter capsulatus puha mutant strains containing either a nonpolar, translationally in-frame deletion or a polar insertion of an antibiotic resistance cartridge were constructed and evaluated for their photosynthetic growth properties, absorption spectroscopy profiles, and chromatophore protein compositions. both types of mutants were found to be incapable of photosynthetic growth and deficient in the reaction center (rc) and light-harvesting 1 (lh1) complexes. the translationally in-frame ...19968636035
deletion of a b800-850 light-harvesting complex in rhodospirillum molischianum dsm119 leads to "revertants" expressing a b800-820 complex: insights into pigment binding.a b800-850 light-harvesting complex (also called lh2) deficient strain of rhodospirillum molischianum was constructed by replacing a portion of the lh2 gene cluster by a kanamycin resistance gene cartridge. the lh2 deficient strain was characterized spectroscopically and by southern blot analysis. surprisingly, pseudorevertants were obtained which express a b800-820 complex which could not be observed in the wild type. this b800-820 complex was isolated and characterized. it consists of an alpha ...19968639597
axial heme ligation in the cytochrome bc1 complexes of mitochondrial and photosynthetic membranes. a near-infrared magnetic circular dichroism and electron paramagnetic resonance study.the combination of epr and low-temperature near-ir magnetic circular dichroism spectroscopies have been used to investigate the axial ligation of the cytochromes in the cytochrome bc1 complexes from bovine heart mitochondria, rhodobacter capsulatus, rhodobacter sphaeroides, and rhodospirillum rubrum, and the purified cytochromes c1 from bovine heart mitochondria, rb. capsulatus and rb. sphaeroides. the possibility of axial ligation of cytochrome c1 by the amino terminus of the polypeptide was al ...19968645697
the binding of nucleotides to domain i proteins of the proton-translocating transhydrogenases from rhodospirillum rubrum and escherichia coli as measured by equilibrium dialysis.transhydrogenase catalyses the transfer of reducing equivalents between nad(h) and nadp(h) coupled to the translocation of protons across a membrane. the nad(h)-binding domain of transhydrogenase (domain i protein) from rhodospirillum rubrum and from escherichia coli were overexpressed and purified. nucleotide binding to the domain i proteins was determined by equilibrium dialysis. nadh and its analogue, acetylpyridine adenine dinucleotide (reduced form), bound with relatively high affinity (kd ...19968774721
posttranslational regulation of nitrogenase activity by fixed nitrogen in azotobacter chroococcum.using anti-(fe protein) antibody raised against the fe protein of the photosynthetic bacterium rhodospirillum rubrum, it was found that the fe protein component of nitrogenase (ec 1.18.2.1) from azotobacter chroococcum cells subjected to an ammonium shock, and hence with an inactive nitrogenase, appeared as a doublet in western blot analysis of cell extracts. the fe protein incorporated [32p]phosphate and [3h]adenine in response to ammonium treatment, and l-methionine-dl-sulfoximine, an inhibito ...19968781527
a perturbed two-level model for exciton trapping in small photosynthetic systems.the study of exciton trapping in photosynthetic systems provides significant information about migration kinetics within the light harvesting antenna (lha) and the reaction center (rc). we discuss two random walk models for systems with weakly coupled pigments, with a focus on the application to small systems (10-40 pigments/rc). details of the exciton transfer to and from the rc are taken into consideration, as well as migration within the lha and quenching in the rc. the first model is obtaine ...19968789084
two-dimensional structure of light harvesting complex ii (lhii) from the purple bacterium rhodovulum sulfidophilum and comparison with lhii from rhodopseudomonas acidophila.within the membranes of photosynthetic bacteria, up to three types of light harvesting complexes (lhi, lhii, lhiii) are found. these complexes absorb photons and transfer the excitation energy to the photosynthetic reaction centre. the lh complexes comprise units that contain alpha and beta polypeptides with associated pigment molecules.19968805531
effect of the pufq-pufb intercistronic region on puf mrna stability in rhodobacter capsulatus.differential expression of genes localized within the polycistronic puf operon of rhodobacter capsulatus is partly due to altered stabilities of individual mrna segments. we show that the 5' untranslated region (utr) of pufb contributes to the unusual longevity of the 0.5 kb light-harvesting (lh) i specific pufba mrna and of the 2.7 kb pufbalmx mrna. three stem-loop structures have been identified within the pufq-pufb intercistronic region by means of rna secondary-structure analysis in vitro an ...19968809769
the effects of decyl aurachins c and d on the respiratory electron flow of facultative phototrophic bacteria.decyl aurachins c and d are two synthetic compounds related to the natural products aurachins c and d extracted from stigmatella aurantiaca. titrations of a range of partial respiratory activities in membranes from facultative phototrophs indicate that decyl aurachin c is more effective than aurachin d in inhibiting the quinol oxidase. decyl aurachin c also affects the nadh-ubiquinone oxidoreductase of rhodobacter capsulatus and the cytochrome bc1 complexes of rb.capsulatus and rhodospirillum ce ...19968843334
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
energy migration in the light-harvesting antenna of the photosynthetic bacterium rhodospirillum rubrum studied by time-resolved excitation annihilation at 77 k.the intensity dependence of picosecond kinetics in the light-harvesting antenna of the photosynthetic bacterium rhodospirillum rubrum is studied at 77 k. by changing either the average excitation intensity or the pulse intensity we have been able to discriminate singlet-singlet and singlet-triplet annihilation. it is shown that the kinetics of both annihilation types are well characterized by the concept of percolative excitation dynamics leading to the time-dependent annihilation rates. the tim ...19969172762
the reduction of acetylpyridine adenine dinucleotide by nadh: is it a significant reaction of proton-translocating transhydrogenase, or an artefact?transhydrogenase is a proton pump. it has separate binding sites for nad+/nadh (on domain i of the protein) and for nadp+/nadph (on domain iii). purified, detergent-dispersed transhydrogenase from escherichia coli catalyses the reduction of the nad+ analogue, acetylpyridine adenine dinucleotide (acpdad+), by nadh at a slow rate in the absence of added nadp+ or nadph. although it is slow, this reaction is surprising, since transhydrogenase is generally thought to catalyse hydride transfer between ...19979186780
adp-ribosylarginine hydrolases and adp-ribosyltransferases. partners in adp-ribosylation cycles.mono-adp-ribosylation is a reversible modification of arginine residues in proteins, with nad:arginine adp-ribosyltransferases and adp-ribosylarginine hydrolases constituting opposing arms of a putative adp-ribosylation cycle. the enzymatic components of an adp-ribosylation cycle have been identified in both prokaryotic and eukaryotic systems. the regulatory significance of the cycle has been best documented in prokaryotes. as shown by ludden and coworkers, adp-ribosylation controls the activity ...19979193633
uridylylation of the p(ii) protein in the photosynthetic bacterium rhodospirillum rubrum.the regulatory protein p(ii) has been studied in great detail in enteric bacteria; however, its function in photosynthetic bacteria has not been clearly established. as a number of these bacteria have been shown to regulate nitrogenase activity by a metabolic control system, it is of special interest to establish the role of p(ii) in these diazotrophs. in this study, we show that p(ii) in rhodospirillum rubrum is modified in response to the n status in the cell and that addition of ammonium or g ...19979209032
rhodospira trueperi gen. nov., spec. nov., a new phototrophic proteobacterium of the alpha group.a new phototrophic purple bacterium was isolated from a flat, laminated microbial mat in a salt marsh near woods hole, mass., usa. the spiral-shaped bacterium was highly motile and had bipolar tufts of flagella and intracytoplasmic membranes of the vesicular type. the major photosynthetic pigments were identified as the carotenoid tetrahydrospirilloxanthin and bacteriochlorophyll b. the long wavelength in vivo absorption maximum of the bacteriochlorophyll was at 986 nm. the marine bacterium show ...19979211712
a single mutation in the m-subunit of rhodospirillum rubrum confers herbicide resistance.cells of the photosynthetic bacterium rhodospirillum rubrum were rendered resistant against the inhibitor 2-(1-phenyl)ethylamino-3-propionylamino-4-cyano-thiazole (ppcth). electron transport in reaction centers prepared from one of the mutants (m6) was neither inhibited by ppcth and other nh-thiazoles nor terbutryn. these inhibitors are known to bind at the q(b) site of the l-subunit. compared to the wild type, chromatophores from m6 exhibited strongly altered q(b)- fe2+ and q(a)- fe2+ epr signa ...19979224686
mutations at tyrosine-235 in the mobile loop region of domain i protein of transhydrogenase from rhodospirillum rubrum strongly inhibit hydride transfer.transhydrogenase from mitochondrial and bacterial membranes couples proton translocation to hydride transfer between nad(h) and nadp(h). the enzyme has three domains, of which domains i and iii protrude from the membrane. these possess the nad(h)- and nadp(h)-binding sites, respectively, whereas domain ii spans the membrane. in domain i there is a mobile loop which emanates from the surface of the protein, but which closes down upon nad(h) binding. in this report we show that the nadp(h)-depende ...19979230921
Refresh
firstprev
...11121314151617181920...
nextlast
Displaying items 1601 - 1700 of 2252