Publications

TitleAbstractYear(sorted ascending)
Filter
PMID
Filter
resonance raman studies of cytochrome c' support the binding of no and co to opposite sides of the heme: implications for ligand discrimination in heme-based sensors.resonance raman (rr) studies have been conducted on alcaligenes xylosoxidans cytochrome c', a mono-his ligated hemoprotein which reversibly binds no and co but not o(2). recent crystallographic characterization of this protein has revealed the first example of a hemoprotein which can utilize both sides of its heme (distal and proximal) for binding exogenous ligands to its fe center. the present rr investigation of the fe coordination and heme pocket environments of ferrous, carbonyl, and nitrosy ...200111300792
regulation of nitrogenase in the photosynthetic bacterium rhodobacter sphaeroides containing dratg and nifhdk genes from rhodobacter capsulatus.the photosynthetic bacteria rhodobacter capsulatus and rhodospirillum rubrum regulate their nitrogenase activity by the reversible adp-ribosylation of nitrogenase fe-protein in response to ammonium addition or darkness. this regulation is mediated by two enzymes, dinitrogenase reductase adp-ribosyl transferase (drat) and dinitrogenase reductase activating glycohydrolase (drag). recently, we demonstrated that another photosynthetic bacterium, rhodobacter sphaeroides, appears to have no dratg gene ...200111315111
evidence for protein dielectric relaxations in reaction centers associated with the primary charge separation detected from rhodospirillum rubrum chromatophores by combined photovoltage and absorption measurements in the 1-15 ns time range.fast photovoltage measurements in rhodospirillum rubrum chromatophores in the nanosecond time range, escorted by time-resolved absorption measurements, are described. under reducing conditions, the photovoltage decayed significantly faster than the spectroscopically detected charge recombination of the radical pair p(+)h(a)(-). this indicates the occurrence of considerable dielectric relaxations. our data and data from the literature were analyzed by means of a reaction scheme consisting of thre ...200111318653
taxonomic ambiguities: a case history. 200111321118
rhodocista centenaria vs rhodospirillum centenum: a reply to gest and favinger. 200111321119
equilibrium and kinetic parameters for the binding of inhibitors to the qb pocket in bacterial chromatophores: dependence on the state of qa.the equilibrium and kinetic parameters for the binding of various inhibitors to the q(b) pocket of the bacterial reaction center were investigated in chromatophores from rhodobacter capsulatus and rhodobacter sphaeroides. by monitoring the near-ir absorption changes specific to q(a)(-) and q(b)(-), we measured the fraction of inhibited centers in the dark and the kinetics and extent of inhibitor displacement after one flash due to the formation of the q(a)q(b)(-) state. the inhibitor release rat ...200111327844
a bacteriochlorophyll a antenna complex from purple bacteria absorbing at 963 nm.a recently isolated species of the photosynthetic purple sulfur bacteria, provisionally called strain 970, was investigated with respect to its antenna function by means of various spectroscopic techniques, including fluorescence and pump-probe absorption difference spectroscopy. the bacterium contains bacteriochlorophyll a and an as yet unidentified carotenoid, perhaps 3,4,3',4'-tetrahydrospirilloxanthin. it has a single antenna complex of the lh1 type, with a q(y) absorption band situated at t ...200111331023
role of the core region of the pufx protein in inhibition of reconstitution of the core light-harvesting complexes of rhodobacter sphaeroides and rhodobacter capsulatus.pufx, the protein encoded by the pufx gene of rhodobacter capsulatus and rhodobacter sphaeroides, has been further characterized. the mature forms of these proteins contain 9 and 12 fewer amino acids, respectively, at the c-terminal end of the protein than are encoded by their pufx genes. to identify the portion of pufx responsible for inhibition of lh1 formation in reconstitution experiments, different regions (n-terminus and several core regions containing different lengths of the c-terminus) ...200111341824
redox-mediated transcriptional activation in a cooa variant.cooa, the carbon monoxide-sensing transcription factor from rhodospirillum rubrum, binds co at a reduced (fe(ii)) heme moiety with resulting conformational changes that promote dna binding. in this study, we report a variant of cooa, m124r, that is active in transcriptional activation in a redox-dependent manner. where wild-type cooa is active only in the fe(ii) + co form, m124r cooa is active in both fe(ii) + co and fe(iii) forms. analysis of the ph dependence of the activity of fe(iii) m124r c ...200111359778
the heterotrimer of the membrane-peripheral components of transhydrogenase and the alternating-site mechanism of proton translocation.transhydrogenase undergoes conformational changes to couple the redox reaction between nad(h) and nadp(h) to proton translocation across a membrane. the protein comprises three components: di, which binds nad(h); diii, which binds nadp(h); and dii, which spans the membrane. experiments using isothermal titration calorimetry, analytical ultracentrifugation, and small angle x-ray scattering show that, as in the crystalline state, a mixture of recombinant di and diii from rhodospirillum rubrum tran ...200111399770
phosphorylation of lhi beta during membrane synthesis in the photosynthetic bacterium rhodovulum sulfidophilum.cells of rhv. sulfidophilum were grown under different conditions in the presence of 32p-phosphate and the corresponding h and l membrane fractions obtained and fractionated by sds-page. both membranes showed almost identical polypeptide composition. the bacteriochlorophyll (bchl) specific content in h was always lower that in l. as described before, oxygen did not regulate gene expression. under high light, an almost two- to threefold decrease of the cellular specific bchl content was observed. ...200111400052
soret-excited raman spectroscopy of the spinach cytochrome b6f complex. structures of the b- and c-type hemes, chlorophyll a, and beta-carotene.soret-excited resonance raman (rr) spectra of the spinach cytochrome b6f complex (cyt b6f) are reported for the oxidized, native, ascorbate-reduced, and dithionite-reduced forms. using excitations at 441.6, 413.1, and 406.7 nm, rr contributions of chlorophyll a, beta-carotene, the c-type heme of cytochrome f, and the b-type hemes of cytochrome b6 of the b6f complex were identified and the data compared to those previously obtained for the rhodospirillum rubrum bc1 complex [le moigne, c., schoepp ...200111401579
role of the atp synthase alpha-subunit in conferring sensitivity to tentoxin.tentoxin, produced by phytopathogenic fungi, selectively affects the function of the atp synthase enzymes of certain sensitive plant species. binding of tentoxin to a high affinity (k(i) approximately 10 nm) site on the chloroplast f(1) (cf(1)) strongly inhibits catalytic function, whereas binding to a second, lower affinity site (k(d) > 10 microm) leads to restoration and even stimulation of catalytic activity. sensitivity to tentoxin has been shown to be due, in part, to the nature of the amin ...200111412108
redox-dependent co2 reduction activity of co dehydrogenase from rhodospirillum rubrum.carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum catalyzes both the oxidation of co and the reduction of co(2). studies of the redox dependence of co(2) reduction by r. rubrum codh show that (1) codh is unable to catalyze co(2) reduction at potentials greater than -300 mv; (2) the maximum activity is observed at potentials less than -480 mv; and (3) the midpoint potential (e(m)) of the transition from minimum to maximum co(2) reduction activity occurs at approximately -339 mv. the ...200111412114
redox-dependent activation of co dehydrogenase from rhodospirillum rubrum.studies of initial activities of carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum show that codh is mostly inactive at redox potentials higher than -300 mv. initial activities measured at a wide range of redox potentials (0--500 mv) fit a function corresponding to the nernst equation with a midpoint potential of -316 mv. previously, extensive epr studies of codh have suggested that codh has three distinct redox states: (i) a spin-coupled state at -60 to -300 mv that gives rise to ...200111416171
methionine oxidation and its effect on the stability of a reconstituted subunit of the light-harvesting complex from rhodospirillum rubrum.an additional component in the purified core light-harvesting complex (lh1) from wild-type purple photosynthetic bacterium rhodospirillum rubrum has been identified as an oxidized species of alpha-polypeptide by maldi-tof mass spectrometry. this component appears as a slightly earlier-eluting peak in the rp-hplc chromatogram compared with the authentic alpha-polypeptide. the oxidation site has been determined to be the n-terminal methionine residue by high-resolution nmr spectroscopy, where the ...200111422366
ligand-switching intermediates for the co-sensing transcriptional activator cooa measured by pulse radiolysis.cooa is a heme-containing and co-sensing transcriptional activator whose activity is regulated by co. the protoheme that acts as a co sensor in cooa shows unique properties for its coordination structure. the cys75 axial ligand of the ferric heme is replaced by his77 upon the reduction of the heme iron and vice versa. in this work, the ligand-switching process induced by the reduction of the heme was investigated by the technique of pulse radiolysis. hydrated electron reduced the heme iron in fe ...200111487580
purification and characterization of membrane-associated cooc protein and its functional role in the insertion of nickel into carbon monoxide dehydrogenase from rhodospirillum rubrum.the accessory protein cooc, which contains a nucleotide-binding domain (p-loop) near the n terminus, participates in the maturation of the nickel center of carbon monoxide dehydrogenase (codh). in this study, cooc was purified from the chromatophore membranes of rhodospirillum rubrum with a 3,464-fold purification and a 0.8% recovery, and its biochemical properties were characterized. cooc is a homodimer with a molecular mass of 61-63 kda, contains less than 0.1 atom of ni(2+) or fe(2+) per dime ...200111507093
mapping cooa.rna polymerase interactions. identification of activating regions 2 and 3 in cooa, the co-sensing transcriptional activator.cooa is a co-sensing protein that activates the transcription of genes encoding the co-oxidation (coo) regulon, whose polypeptide products are required for utilizing co as an energy source in rhodospirillum rubrum. cooa binds to a position overlapping the -35 element of the p(coof) promoter, similar to the arrangement of class ii crp (camp receptor protein)- and fnr (fumarate and nitrate reductase activator protein)-dependent promoters when expressed in escherichia coli. gain-of-function cooa va ...200111522788
cooa: a heme-containing regulatory protein that serves as a specific sensor of both carbon monoxide and redox state.cooa, the heme-containing carbon monoxide (co) sensor from the bacterium rhodospirillum rubrum, is a transcriptional factor that activates expression of certain genes in response to co. as with other heme proteins, cooa is unable to bind co when the fe heme is oxidized, consistent with the fact that some of the regulated gene products are oxygen-labile. upon reduction, there is an unusual switch of protein ligands to the six-coordinate heme and the reduced heme is able to bind co. co binding sta ...200111525385
re-identification of the n-terminal amino acid residue and its modification of +/-bbeta-polypeptide of light-harvesting complex i from rhodospirillum rubrum. 200116252177
spectroscopic studies of nickel-deficient carbon monoxide dehydrogenase from rhodospirillum rubrum: nature of the iron-sulfur clusters.carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum utilizes three types of fe-s clusters to catalyze the reversible oxidation of co to co(2): a novel [ni4fe5s] active site (c cluster) and two distinct [4fe4s] electron-transfer sites (b and d clusters). while recent x-ray data show the geometric arrangement of the five metal centers at the c cluster, electronic structures of the various [ni4fe5s] oxidation states remain ambiguous. these studies report magnetic circular dichroism (mcd ...200211814363
unsuspected diversity among marine aerobic anoxygenic phototrophs.aerobic, anoxygenic, phototrophic bacteria containing bacteriochlorophyll a (bchla) require oxygen for both growth and bchla synthesis. recent reports suggest that these bacteria are widely distributed in marine plankton, and that they may account for up to 5% of surface ocean photosynthetic electron transport and 11% of the total microbial community. known planktonic anoxygenic phototrophs belong to only a few restricted groups within the proteobacteria alpha-subclass. here we report genomic an ...200211832943
calculability analysis in underdetermined metabolic networks illustrated by a model of the central metabolism in purple nonsulfur bacteria.metabolite balancing has turned out to be a powerful computational tool in metabolic engineering. however, the linear equation systems occurring in this analysis are often underdetermined. if it is difficult or impossible to find the missing constraints, it is nevertheless feasible in some cases to determine the values of a subset of the unknown rates. here, a procedure for finding out which reaction rates can be uniquely calculated in underdetermined metabolic networks and computing these rates ...200211835134
rhodospirillum rubrum possesses a variant of the bchp gene, encoding geranylgeranyl-bacteriopheophytin reductase.the bchp gene product of rhodobacter sphaeroides is responsible for the reduction of the isoprenoid moiety of bacteriochlorophyll (bchl) from geranylgeraniol (gg) to phytol; here, we show that this enzyme also catalyzes the reduction of the isoprenoid moiety of bacteriopheophytin (bphe). in contrast, we demonstrate that a newly identified homolog of this gene in rhodospirillum rubrum encodes an enzyme, gg-bphe reductase, capable of reducing the isoprenoid moiety of bphe only. we propose that rho ...200211872709
general random matrix approach to account for the effect of static disorder on the spectral properties of light harvesting systems.we develop a random matrix model approach to study static disorder in pigment-protein complexes in photosynthetic organisms. as a case study, we examine the ring of b850 bacteriochlorophylls in the peripheral light-harvesting complex of rhodospirillum molischianum, formulated in terms of an effective hamiltonian describing the collective electronic excitations of the system. we numerically examine and compare various models of disorder and observe that both the density of states and the absorpti ...200211909118
excitons in a photosynthetic light-harvesting system: a combined molecular dynamics, quantum chemistry, and polaron model study.the dynamics of pigment-pigment and pigment-protein interactions in light-harvesting complexes is studied with an approach that combines molecular dynamics simulations with quantum chemistry calculations and a polaron model analysis. the molecular dynamics simulation of light-harvesting (lh) complexes was performed on an 87 055 atom system comprised of a lh-ii complex of rhodospirillum molischianum embedded in a lipid bilayer and surrounded with appropriate water layers. for each of the 16 b850 ...200211909121
photosynthetic apparatus in roseateles depolymerans 61a is transcriptionally induced by carbon limitation.production of a photosynthetic apparatus in roseateles depolymerans 61a, a recently discovered freshwater beta-proteobacterium showing characteristics of aerobic phototrophic bacteria, was observed when the cells were subjected to a sudden decrease in carbon sources (e.g., when cells grown with 0.1 to 0.4% casamino acids were diluted or transferred into medium containing <or=0.04% casamino acids). accumulation of bacteriochlorophyll (bchl) a was observed in the presence of oxygen and was enhance ...200211916683
absorption and cd spectroscopy and modeling of various lh2 complexes from purple bacteria.the absorption (od) and circular dichroism (cd) spectra of lh2 complexes from various purple bacteria have been measured and modeled. based on the lineshapes of the spectra we can sort the lh2 complexes into two distinguishable groups: "acidophila"-like (type 1) and "molischianum"-like (type 2). starting from the known geometric structures of rhodopseudomonas (rps.) acidophila and rhodospirillum (rsp.) molischianum we can model the od and cd spectra of all species by just slightly varying some k ...200211916874
structure of the rhodobacter sphaeroides light-harvesting 1 beta subunit in detergent micelles.the light harvesting 1 antenna (lh1) complex from rhodobacter sphaeroides funnels excitation energy to the photosynthetic reaction center. our ultimate goal is to build up the structure of lh1 from structures of its individual subunits, much as the antenna can self-assemble from its components in membrane-mimicking detergent micelles. the beta subunit adopts a nativelike conformation in zwittergent 3:12 micelles as demonstrated by its ability to take the first step of assembly, binding bchl a. m ...200211772000
the 7.5-a electron density and spectroscopic properties of a novel low-light b800 lh2 from rhodopseudomonas palustris.a novel low-light (ll) adapted light-harvesting complex ii has been isolated from rhodopseudomonas palustris. previous work has identified a ll b800-850 complex with a heterogeneous peptide composition and reduced absorption at 850 nm. the work presented here shows the 850 nm absorption to be contamination from a high-light b800-850 complex and that the true ll light-harvesting complex ii is a novel b800 complex composed of eight alpha beta(d) peptide pairs that exhibits unique absorption and ci ...200211806936
cloning a gene encoding a light-harvesting i polypeptide from ectothiorhodospira sp.trying to detect the genes coding for light harvesting ii polypeptides of the purple bacteria ectothiorhodospira sp. a gene corresponding to a light harvesting i polypeptide was cloned. this paper discusses the probable reasons of this result. the sequence of this polypeptide underlines the strong similarity with light harvesting complexes from bacteria such as rhodospirillum molischianum and chromatium vinosum.200212240998
biochemical characterization of the dissociated forms from the core antenna proteins from purple bacteria.the core light-harvesting protein from rhodospirillum rubrum is of particular interest for studying membrane polypeptide association, as it can be reversibly dissociated in the presence of n-octyl-beta-d-glucopyranoside (betaog) into smaller subunit forms, which exhibit dramatically blue-shifted absorption properties (miller et al. (1987) biochemistry 26, 5055-5062). during this dissociation/reassociation process, two main spectroscopic forms are observed, absorbing at 820 (b820) and 777 (b777) ...200212269824
spectroscopic characterisation of a tetrameric subunit form of the core antenna protein from rhodospirillum rubrum.the core light-harvesting complex (lh1) of rhodospirillum rubrum is constituted of multiple heterodimeric subunits, each containing two transmembrane polypeptides, alpha and beta. the detergent octylglucoside induces the stepwise dissociation of lh1 into b820 (an alphabeta dimer) and b777 (monomeric polypeptides), both of which still retain their bound bacteriochlorophyll molecules. we have investigated the absorption properties of b820 as a function of temperature, whereby a spectral population ...200212297309
converting the nifes carbon monoxide dehydrogenase to a hydrogenase and a hydroxylamine reductase.substitution of one amino acid for another at the active site of an enzyme usually diminishes or eliminates the activity of the enzyme. in some cases, however, the specificity of the enzyme is changed. in this study, we report that the changing of a metal ligand at the active site of the nifes-containing carbon monoxide dehydrogenase (codh) converts the enzyme to a hydrogenase or a hydroxylamine reductase. codh with alanine substituted for cys(531) exhibits substantial uptake hydrogenase activit ...200212374822
characterization of three spiral-shaped purple nonsulfur bacteria isolated from coastal lagoon sediments, saline sulfur springs, and microbial mats: emended description of the genus roseospira and description of roseospira marina sp. nov., roseospira navarrensis sp. nov., and roseospira thiosulfatophila sp. nov.three new spirilloid phototrophic purple nonsulfur bacteria were isolated in pure culture from three different environments: strain ce2105 from a brackish lagoon in the arcachon bay (atlantic coast, france), strain se3104 from a saline sulfur spring in the pyrenees (navarra, spain), and strain at2115 a microbial mat (tetiaroa atoll, society islands). single cells of the three strains were spiral-shaped and highly motile. their intracellular photosynthetic membranes were of the vesicular type. ba ...200212375098
crystal structures of transhydrogenase domain i with and without bound nadh.transhydrogenase (th) is a dimeric integral membrane enzyme in mitochondria and prokaryotes that couples proton translocation across a membrane with hydride transfer between nad(h) and nadp(h) in soluble domains. crystal structures of the nad(h) binding alpha1 subunit (domain i) of rhodospirillum rubrum th have been determined at 1.8 a resolution in the absence of dinucleotide and at 1.9 a resolution with nadh bound. each structure contains two domain i dimers in the asymmetric unit (ab and cd); ...200212379117
inhibition of acetate and propionate assimilation by itaconate via propionyl-coa carboxylase in isocitrate lyase-negative purple bacterium rhodospirillum rubrum.itaconate is known as a potent inhibitor of isocitrate lyase. unexpectedly, itaconate was a strong inhibitor of acetate and propionate assimilation in isocitrate lyase-negative purple non-sulfur bacterium rhodospirillum rubrum. it was shown that in cell extracts of r. rubrum itaconate inhibited propionyl-coa carboxylase (pcc) activity. the participation of pcc in propionate assimilation in r. rubrum is well-documented, but the inhibition of acetate assimilation suggests that pcc is also involved ...200212423751
rhodospirillum centenum utilizes separate motor and switch components to control lateral and polar flagellum rotation.rhodospirillum centenum is a purple photosynthetic bacterium that is capable of differentiating from vibrioid swimming cells that contain a single polar flagellum into rod-shaped swarming cells that have a polar flagellum plus numerous lateral flagella. microscopic studies have demonstrated that the polar flagellum is constitutively present and that the lateral flagella are found only when the cells are grown on solidified or viscous medium. in this study, we demonstrated that r. centenum contai ...200211948156
h+-pyrophosphatase of rhodospirillum rubrum. high yield expression in escherichia coli and identification of the cys residues responsible for inactivation my mersalyl.h(+)-translocating pyrophosphatase (h(+)-ppase) of the photosynthetic bacterium rhodospirillum rubrum was expressed in escherichia coli c43(de3) cells. recombinant h(+)-ppase was observed in inner membrane vesicles, where it catalyzed both pp(i) hydrolysis coupled with h(+) transport into the vesicles and pp(i) synthesis. the hydrolytic activity of h(+)-ppase in e. coli vesicles was eight times greater than that in r. rubrum chromatophores but exhibited similar sensitivity to the h(+)-ppase inhi ...200211956221
the reaction order of the dissociation reaction of the b820 subunit of rhodospirillum rubrum light-harvesting i complex.we have studied the equilibrium between the dissociated b777 form (absorbing at 777 nm) of the light-harvesting complex of rhodospirillum rubrum and the oligomeric b820 form. analysis of the reaction order for the b820 dissociation reaction to form b777 shows that this reaction depends on the concentration of octylglucoside detergent (n-octyl-beta-d-glucopyranoside (betaog)) present in the sample. at low betaog concentrations (less than 1.2%) this reaction requires two components, presumably one ...200211959099
[modeling of energy migration and trapping in purple bacteria. analysis of extreme formulae].homogeneous pigment ensembles similar to those of purple bacteria rhodospirillum rubrum were studied. two formulae were advanced for the limiting values of excitation lifetime and quantum yield of excitation trapping in these ensembles, provided all reaction centers are in an active state. it was demonstrated by mathematical modeling that these limiting values strictly depend on three parameters of molecular ensembles: the numbers of core-bacteriochlorophyll molecules per reaction center, the va ...200211969165
an alternative carotenoid-to-bacteriochlorophyll energy transfer pathway in photosynthetic light harvesting.blue and green sunlight become available for photosynthetic energy conversion through the light-harvesting (lh) function of carotenoids, which involves transfer of carotenoid singlet excited states to nearby (bacterio)chlorophylls (bchls). the excited-state manifold of carotenoids usually is described in terms of two singlet states, s(1) and s(2), of which only the latter can be populated from the ground state by the absorption of one photon. both states are capable of energy transfer to (b)chl. ...200211972067
photosynthetic apparatus of purple bacteria. 200211997980
bacteriophytochrome controls photosystem synthesis in anoxygenic bacteria.plants use a set of light sensors to control their growth and development in response to changes in ambient light. in particular, phytochromes exert their regulatory activity by switching between a biologically inactive red-light-absorbing form (pr) and an active far-red-light absorbing form (pfr). recently, biochemical and genetic studies have demonstrated the occurrence of phytochrome-like proteins in photosynthetic and non-photosynthetic bacteria--but little is known about their functions. he ...200212000965
bioreactor design studies for a hydrogen-producing bacterium.carbon monoxide (co) can be metabolized by a number of microorganisms along with water to produce hydrogen (h2) and carbon dioxide. national renewable energy laboratory researchers have isolated a number of bacteria that perform this so-called water-gas shift reaction at ambient temperatures. we performed experiments to measure the rate of co conversion and h2 production in a trickle-bed reactor (tbr). the liquid recirculation rate and the reactor support material both affected the mass transfer ...200212018287
n-terminal methylation of the core light-harvesting complex in purple photosynthetic bacteria.several core light-harvesting complexes from both sulfur and non-sulfur purple photosynthetic bacteria have been identified to be methylated at the n-terminal alpha-amino group of beta-polypeptides by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and nuclear magnetic resonance. monomethylation has been confirmed for the n-terminal alanine residues of the beta-polypeptides from rhodospirillum rubrum, thermochromatium tepidum and chromatium vinosum, but not for ...200212023037
evidence for a wide occurrence of proton-translocating pyrophosphatase genes in parasitic and free-living protozoa.proton-translocating inorganic pyrophosphatases (h(+)-ppase, ec 3.6.1.1) are integral membrane proteins that have been extensively studied in higher plants, the photosynthetic bacterium rhodospirillum rubrum and, more recently, in some human pathogenic protozoa. by using a pcr-based approach, fragments of genes coding for h(+)-ppases in a number of protists, both free-living and parasites of animals and plants, that belong to diverse taxonomic groups (trypanosomatids, ciliates, apicomplexans, eu ...200212056804
a quantum chemistry study of binding carotenoids in the bacterial light-harvesting complexes.carotenoids play the dual function of light harvesting and photoprotection in photosynthetic organisms. despite their functional importance, the molecular basis for binding of carotenoids in the photosynthetic proteins is poorly understood. we have discovered that all carotenoids are surrounded either by aromatic residues or by chlorophylls in all known crystal structures of the photosynthetic pigment-protein complexes. the intermolecular pi-pi stacking interactions between carotenoids and the s ...200212105926
analysis of the l116k variant of cooa, the heme-containing co sensor, suggests the presence of an unusual heme ligand resulting in novel activity.cooa is the co-sensing transcriptional activator from rhodospirillum rubrum, in which co binding to its heme prosthetic group triggers a conformational change of cooa that allows the protein to bind its cognate target dna sequence. by a powerful in vivo screening method following the simultaneous randomization of the codons for two c-helix residues, 113 and 116, near the distal heme pocket of cooa, we have isolated a series of novel cooa variants. in vivo, these show very high co-independent act ...200212121986
projection structure of the photosynthetic reaction centre-antenna complex of rhodospirillum rubrum at 8.5 a resolution.two-dimensional crystals of the reaction-centre-light-harvesting complex i (rc-lh1) of the purple non- sulfur bacterium rhodospirillum rubrum have been formed from detergent-solubilized and purified protein complexes. unstained samples of this intrinsic membrane protein complex have been analysed by electron cryomicroscopy (cryo em). projection maps were calculated to 8.5 a from two different crystal forms, and show a single reaction centre surrounded by 16 lh1 subunits in a ring of approximatel ...200212145194
thalassospira lucentensis gen. nov., sp. nov., a new marine member of the alpha-proteobacteria.a novel bacterium from the mediterranean sea was isolated under oligotrophic conditions at in situ temperature after prolonged continuous culture. the isolates were initially characterized by partial 16s rrna gene sequencing. similarity searches of one of the isolates, qmt2t, indicated high sequence identity to the well-characterized rhodospirillum rubrum, [aquaspirillum] itersonii and [oceanospirillum] pusillum micro-organisms, which are representatives of the alpha-subclass of the proteobacter ...200212148640
spectroscopy on individual light-harvesting 1 complexes of rhodopseudomonas acidophila.in this paper the fluorescence-excitation spectra of individual lh1-rc complexes (rhodopseudomonas acidophila) at 1.2 k are presented. all spectra show a limited number of broad bands with a characteristic polarization behavior, indicating that the excitations are delocalized over a large number of pigments. a significant variation in the number of bands, their bandwidths, and polarization behavior is observed. only 30% of the spectra carry a clear signature of delocalized excited states of a ci ...200212202393
carbon monoxide dehydrogenase from rhodospirillum rubrum produces formate.carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum reversibly catalyzes the oxidation of co to co(2) at the active site c-cluster. in this article, the reduction of co(2) to formate is reported as a slow side reaction catalyzed by both ni-containing codh and ni-deficient codh. recently, the structures of r. rubrum codh and its active site nifes cluster (the c-cluster) have been solved. the data in this manuscript describe the formate-producing capability of codh with or without ni i ...200212203017
a conformational change in the isolated nadp(h)-binding component (diii) of transhydrogenase induced by low ph: a reflection of events during proton translocation by the complete enzyme?transhydrogenase couples the reduction of nadp(+) by nadh to inward proton translocation across the bacterial (or mitochondrial) membrane. conformational changes in the nadp(h)-binding component of the enzyme (diii) are central to the coupling mechanism. in the "open" state, nadp(h) bound to diii can readily exchange with nucleotides in the solvent but hydride transfer [to/from nad(h) bound to di] is prevented. in the "occluded" state, bound nadp(h) cannot exchange with solvent nucleotides but t ...200212206884
supramolecular organisation of the photosynthetic chain in anoxygenic bacteria.this minireview summarizes our present view of the supramolecular organization of the photosynthetic apparatus of rhodobacter sphaeroides and rhodobacter capsulatus. these two species present a close association between two reaction centers (rcs), one cytochrome (cyt) bc(1) and one cyt c. in r. sphaeroides, the rcs are only partially surrounded by lh1 complexes. this open ring of lh1 complexes is required for an efficient photoinduced cyclic electron transfer only under conditions where the quin ...200212206892
time-resolved dissociation of the light-harvesting 1 complex of rhodospirillum rubrum, studied by infrared laser temperature jump.for the first time, data are presented on the time-resolved disassembly reaction of a highly organized membrane protein complex in vitro. the photosynthetic core light-harvesting complex of the bacterial strain rhodospirillum rubrum g9 consists of 12-16 dimeric subunits that in vivo are associated with the photosynthetic reaction center in a ringlike manner. isolated in a detergent solution, its appearance either as a ringlike complex (called b873 and absorbing at 873 nm), subunit dimer (called ...200212484747
nitrogen fixation by photosynthetic bacteria.in 1949, howard gest and martin kamen published two brief papers in science that changed our perceptions about the metabolic capabilities of photosynthetic bacteria. their discovery of photoproduction of hydrogen and the ability of rhodospirillum rubrum to fix nitrogen led to a greater understanding of both processes.200216245111
purification and characterization of the polypeptides of core light-harvesting complexes from purple sulfur bacteria.although the polypeptides of core light-harvesting complexes (lh1) from many purple nonsulfur bacteria have been well characterized, little information is available on the polypeptides of lh1 from purple sulfur photosynthetic organisms. we present here the results of isolation and characterization of lh1 polypeptides from two purple sulfur bacteria, thermochromatium (tch.) tepidum and allochromatium (ach.) vinosum. native lh1 complexes were extracted and purified in a reaction center (rc)-associ ...200316245044
interaction of bacteriochlorophyll with the lh1 and pufx polypeptides of photosynthetic bacteria: use of chemically synthesized analogs and covalently attached fluorescent probes.the protein components of the reaction center (rc) and core light-harvesting (lh 1) complexes of photosynthetic bacteria have evolved to specifically, but non-covalently, bind bacteriochlorophyll (bchl). the contribution to binding of specific structural elements in the protein and bchl may be determined for the lh 1 complex because its subunit can be studied by reconstitution under equilibrium conditions. important to the determination and utilization of such information is the characterization ...200316228601
investigations of intermediates appearing in the reassociation of the light-harvesting 1 complex of rhodospirillum rubrum.we investigated the temperature-mediated reassociation of the b820 subunit of rs. rubrum to form a light-harvesting 1 complex (lh 1). by combining several spectroscopic techniques with global spectral data analysis fitting, we present evidence for the occurence of two spectral intermediates that appear during the reassociation process. at high temperatures, halfway the reassociation reaction, a prominent intermediate appears that has an absorption maximum around 850 nm, a fluorescence maximum ar ...200316228604
microaerophilic cooperation of reductive and oxidative pathways allows maximal photosynthetic membrane biosynthesis in rhodospirillum rubrum.the purple nonsulfur bacterium rhodospirillum rubrum has been employed to study physiological adaptation to limiting oxygen tensions (microaerophilic conditions). r. rubrum produces maximal levels of photosynthetic membranes when grown with both succinate and fructose as carbon sources under microaerophilic conditions in comparison to the level (only about 20% of the maximum) seen in the absence of fructose. employing a unique partial o(2) pressure (po(2)) control strategy to reliably adjust the ...200314602616
biochemical and biophysical properties of the co-sensing transcriptional activator cooa.studies of heme-containing gas sensor proteins have revealed a novel function for heme, which acts as an active site for sensing the corresponding gas molecule of a physiological effector. heme-based o(2), no, and co sensor proteins have now been described in which these gas molecules act as a signaling factor that regulates the functional activity of the sensor proteins. cooa is a co-sensing transcriptional activator found in the photosynthetic bacterium rhodospirillum rubrum. the binding of co ...200314622029
proton translocation by transhydrogenase. 200314630339
identification and distribution of insertion sequences of paracoccus solventivorans.three novel insertion sequences (iss) (ispso1, ispso2, and ispso3) of the soil bacterium paracoccus solventivorans dsm 11592 were identified by transposition into entrapment vector pmec1. ispso1 (1,400 bp) carries one large open reading frame (orf) encoding a putative basic protein (with a dde motif conserved among transposases [tnps] of elements belonging to the is256 family) with the highest levels of similarity with the hypothetical tnps of rhodospirillum rubrum and sphingopyxis macrogoltabid ...200314660342
properties of mutated rhodospirillum rubrum h+-pyrophosphatase expressed in escherichia coli.the membrane-bound proton pumping inorganic pyrophosphate synthase/pyrophosphatase (h(+)-ppi synthase/h(+)-ppase) from the photosynthetic bacterium rhodospirillum rubrum was functionally expressed in escherichia coli c43(de3) cells. based on a new topology model of the enzyme, charged residues predicted to be located near or within the membrane were selected for site-directed mutagenesis. several of these mutations resulted in an almost complete inactivation of the enzyme. four mutated residues ...200314670604
direct observation of tiers in the energy landscape of a chromoprotein: a single-molecule study.single-molecule spectroscopic techniques were applied to individual pigments embedded in a chromoprotein. a sensitive tool to monitor structural fluctuations of the protein backbone in the local environment of the chromophore is provided by recording the changes of the spectral positions of the pigment absorptions as a function of time. the data provide information about the organization of the energy landscape of the protein in tiers that can be characterized by an average barrier height. addit ...200314671325
role of the c-terminal extrinsic region of the alpha polypeptide of the light-harvesting 2 complex of rhodobacter sphaeroides: a domain swap study.the lh1 and lh2 complexes of rhodobacter sphaeroides form ring structures of 16 and 9 protomers, respectively, comprising alpha and beta polypeptides, bacteriochlorophylls (bchl), and carotenoids. using the lh2 complex as a starting point, two chimeric lh complexes were constructed incorporating the alphac-terminal domain of either the rb. sphaeroides lh1 complex or the rhodospirillum molischianum lh2 complex. the lh1 domain swap produced a new red-shifted component that comprised approximately ...200314690421
repositioning about the dimer interface of the transcription regulator cooa: a major signal transduction pathway between the effector and dna-binding domains.activation of the homodimeric transcriptional regulator cooa depends on the coupling of co binding at an effector domain heme with the allosteric repositioning of the dna-binding domain f-helix that promotes specific dna interaction. by analogy to the homologous camp receptor protein (crp), it has been proposed that effector binding elicits subunit reorientation about their coiled-coil c-helix interface, and that this effector domain reorientation stabilizes the active position of the dna-bindin ...200312507482
low-intensity pump-probe measurements on the b800 band of rhodospirillum molischianum.we have measured low-intensity, polarized one-color pump-probe traces in the b800 band of the light-harvesting complex lh2 of rhodospirillum molischianum at 77 k. the excitation/detection wavelength was tuned through the b800 band. a single-wavelength and a global target analysis of the data were performed with a model that accounts for excitation energy transfer among the b800 molecules and from b800 to b850. by including the anisotropy of the signals into the fitting procedure, both transfer p ...200312524297
identification and preliminary characterization of acsf, a putative ni-insertase used in the biosynthesis of acetyl-coa synthase from clostridium thermoaceticum.the acsabcde genes in the clostridium thermoaceticum genome are used for autotrophic acetyl-coa synthesis using the wood-ljungdahl pathway. a 2.8-kb region between acsc and acsd was cloned and sequenced. two open reading frames, orf7 (approximately 1.9 kb) and acsf (approximately 0.7 kb) were identified. orf7 appears to encode an fe-s protein, in that it contains five conserved cysteine residues, three of which are present in a motif (cggxxxcgxc) commonly used to coordinate fe-s clusters. howeve ...200312538050
crystal structure of a photoactive yellow protein from a sensor histidine kinase: conformational variability and signal transduction.photoactive yellow protein (e-pyp) is a blue light photoreceptor, implicated in a negative phototactic response in ectothiorhodospira halophila, that also serves as a model for the per-arnt-sim superfamily of signaling molecules. because no biological signaling partner for e-pyp has been identified, it has not been possible to correlate any of its photocycle intermediates with a relevant signaling state. however, the pyp domain (ppr-pyp) from the sensor histidine kinase ppr in rhodospirillum cen ...200312563032
glutamine 132 in the nad(h)-binding component of proton-translocating transhydrogenase tethers the nucleotides before hydride transfer.transhydrogenase, found in bacterial membranes and inner mitochondrial membranes of animal cells, couples the redox reaction between nad(h) and nadp(h) to proton translocation. in this work, the invariant gln132 in the nad(h)-binding component (di) of the rhodospirillum rubrum transhydrogenase was substituted with asn (to give di.q132n). mixtures of the mutant protein and the nadp(h)-binding component (diii) of the enzyme readily produced an asymmetric complex, (di.q132n)(2)diii(1). the x-ray st ...200312564924
single-molecule study of the electronic couplings in a circular array of molecules: light-harvesting-2 complex from rhodospirillum molischianum.applying single-molecule spectroscopic techniques allowed us to determine the mutual angles between the transition-dipole moments associated with optical transitions of the eight bacteriochlorophyll a molecules which form the so-called b800 ring of the light-harvesting-2 complex from rhodospirillum molischianum. the orientation of the transition-dipole moment is a sensitive probe for the strength of the local intermolecular interactions because of the well-defined arrangement of the individual m ...200312570608
isolation and molecular characterization of pmg160, a mobilizable cryptic plasmid from rhodobacter blasticus.a 3.4-kb cryptic plasmid was obtained from a new isolate of rhodobacter blasticus. this plasmid, designated pmg160, was mobilizable by the conjugative strain escherichia coli s17.1 into rhodobacter sphaeroides, rhodobacter capsulatus, and rhodopseudomonas palustris. it replicated in the latter strains but not in rhodospirillum rubrum, rhodocyclus gelatinosus, or bradyrhizobium species. plasmid pmg160 was stably maintained in r. sphaeroides for more than 100 generations in the absence of selectio ...200312570988
complete spectra of the far-red chemiluminescence of the oxygenase reaction of mn2+-activated ribulose-bisphosphate carboxylase/oxygenase establish excited mn2+ as the source.chemiluminescence emitted by mn(2+)-activated ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) while catalyzing oxygenation was analyzed to clarify the source of the emission. using dual detectors capturing radiation over a wide range of visible and infrared wavelengths, we tested for radiation from singlet o(2) decay and found it to be essentially absent (less than 0.1% of the total luminescence intensity). spectra were determined between 647 and 885 nm with a very sensitive, charge-co ...200312604603
[two-level heterogenous energy migration. modeling and application to purple bacteria].the dynamics of migration of electronic excitations and the efficiency of their trapping in two-dimensional ensembles of molecules were analyzed. molecules were characterized using the following parameters: the width of long-wavelength bands, the values of extinction and rate constant of deactivation of electronic excitations, critical distances of migration close to those of dye molecules, in particular, bacteriochlorophyll a and purple bacteria. a comparative analysis of two-dimensional models ...200312630112
cd bioaccumulation by a freshwater bacterium, rhodospirillum rubrum.cd bioaccumulation by rhodospirillum rubrum, a gram-negative freshwater bacterium, was studied in a synthetic medium. the free ion (cd2+) was the best predictor of the cd internalization fluxes. representation of the short-term uptake fluxes as a function of [cd2+] in the medium demonstrated a linear relationship, as would be expected for a rate-limiting, first-order internalization with a single transporter. nonetheless, several different accumulation profiles were observed, depending on the cd ...200312636267
rhodospirillum rubrum has a family i pyrophosphatase: purification, cloning, and sequencing.the cytoplasmic pyrophosphatase of the photosynthetic bacterium rhodospirillum rubrum was purified to electrophoretic homogeneity. the enzyme is a homohexamer of 20-kda monomers. the gene was cloned and sequenced. alignment of the deduced 179-amino-acid protein with known bacterial pyrophosphatases revealed conservation of all residues in the active site. attempts to obtain an insertion mutant of the cytoplasmic pyrophosphatase gene did not yield any cell completely devoid of cytoplasmic pyropho ...200312658333
ni and co: more surprises. 200312660715
rhodobacter sphaeroides has a family ii pyrophosphatase: comparison with other species of photosynthetic bacteria.the cytoplasmic pyrophosphatase from rhodobacter sphaeroides was purified and characterized. the enzyme is a homodimer of 64 kda. the n-terminus was sequenced and used to obtain the complete pyrophosphatase sequence from the preliminary genome sequence of rba. sphaeroides, showing extensive sequence similarity to family ii or class c pyrophosphatases. the enzyme hydrolyzes only mg-pp(i) and mn-pp(i) with a k(m) of 0.35 mm for both substrates. it is not activated by free mg (2+), in contrast to t ...200312669192
electron transport dynamics at the quinone acceptor site of bacterial photosynthetic reaction centers as probed using fast temperature changes.methods of laser-induced temperature jumps and fast freezing were used for testing the rates of thermoinduced conformational transitions of reaction center (rc) complexes in chromatophores and isolated rc preparations of various photosynthesizing purple bacteria. an electron transfer reaction from primary to secondary quinone acceptors was used as a probe of electron transport efficiency. the thermoinduced transition of the acceptor complex to the conformational state facilitating electron trans ...200312679860
pulsed high-frequency epr study on the location of carotenoid and chlorophyll cation radicals in photosystem ii.when the primary electron-donation pathway from the water-oxidation complex in photosystem ii (ps ii) is inhibited, chlorophyll (chl(z) and chl(d)), beta-carotene (car) and cytochrome b(559) are alternate electron donors that are believed to function in a photoprotection mechanism. previous studies have demonstrated that high-frequency epr spectroscopy (at 130 ghz), together with deuteration of ps ii, yields resolved car(+) and chl(+) epr signals (lakshmi et al. j. phys. chem. b 2000, 104, 10 44 ...200312708850
a reaction center-light-harvesting 1 complex (rc-lh1) from a rhodospirillum rubrum mutant with altered esterifying pigments: characterization by optical spectroscopy and cryo-electron microscopy.introduction of the bchp gene from rhodobacter sphaeroides encoding geranylgeranyl reductase into rhodospirillum rubrum alters the esterification of the bacteriochlorophylls so that phytol is used instead of geranylgeraniol. the resulting transconjugant strain of rs. rubrum grows photosynthetically, showing that phytolated bchla can substitute for the native pigment in both the reaction center (rc) and the light-harvesting 1 (lh1) complexes. this genetic manipulation perturbs the native caroteno ...200312719425
activation mechanism of the co sensor cooa. mutational and resonance raman spectroscopic studies.cooa is a co-dependent heme protein transcription factor of the bacterium rhodospirillum rubrum. co binding to its heme causes cooa to bind dna and activate expression of genes for co metabolism. to understand the nature of co activation, several cooa mutational variants have been studied by resonance raman spectroscopy, in vivo activity measurements, and dna binding assays. analysis of the fe-c and c-o stretching raman spectroscopy bands permits the conclusion that when co displaces the pro2 he ...200312796503
the influence of detergents and amphiphiles on the solubility of the light-harvesting i complex.the effect of detergents and amphiphiles on protein solubility and their use in crystallization solutions was examined for an integral membrane protein, the light-harvesting i complex from rhodospirillum centenum. measurement by a centrifugation assay of the solubility of the protein in different detergents and amphiphiles showed high protein-solubility values when either octyl glucoside or lauryldimethylamine-n-oxide was present with heptanetriol or when deoxycholate was present with spermine. ...200312876344
modelling continuous culture of rhodospirillum rubrum in photobioreactor under light limited conditions.rhodospirillum rubrum was grown continuously and photoheterotrophically under light limitation using a cylindrical photobioreactor in which the steady state biomass concentration was varied between 0.4 to 4 kg m(-3) at a constant radiant incident flux of 100 w m(-2). kinetic and stoichiometric models for the growth are proposed. the biomass productivities, acetate consumption rate and the co2 production rate can be quantitatively predicted to a high level of accuracy by the proposed model calcul ...200312882553
modeling stability of photoheterotrophic continuous cultures in photobioreactors.continuous cultures of the purple non-sulfur bacterium rhodospirillum rubrum were grown in a cylindrical photobioreactor in photoheterotrophic conditions, using acetate as carbon source. a new kinetic and stoichiometric knowledge model was developed, and its ability to simulate experimental results obtained under varying incident light fluxes and residence times is discussed. the model accurately predicts the stable, unstable, or oscillating behavior observed for the reactor productivity. in par ...200312892484
inter- and intraspecific variation in excited-state triplet energy transfer rates in reaction centers of photosynthetic bacteria.in protein-cofactor reaction center (rc) complexes of purple photosynthetic bacteria, the major role of the bound carotenoid (c) is to quench the triplet state formed on the primary electron donor (p) before its sensitization of the excited singlet state of molecular oxygen from its ground triplet state. this triplet energy is transferred from p to c via the bacteriochlorophyll monomer b(b). using time-resolved electron paramagnetic resonance (trepr), we have examined the temperature dependence ...200312945578
circular symmetry of the light-harvesting 1 complex from rhodospirillum rubrum is not perturbed by interaction with the reaction center.the effect of the interaction of the reaction center (rc) upon the geometrical arrangement of the bacteriochlorophyll a (bchla) pigments in the light-harvesting 1 complex (lh1) from rhodospirillum rubrum has been examined using single molecule spectroscopy. fluorescence excitation spectra at 1.8 k obtained from single detergent-solubilized as well as single membrane-reconstituted lh1-rc complexes showed predominantly (>70%) a single broad absorption maximum at 880-900 nm corresponding to the q(y ...200312950162
photosynthesis and growth of tobacco with a substituted bacterial rubisco mirror the properties of the introduced enzyme.complete replacement, by biolistic plastid transformation, of the hexadecameric ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) of tobacco (nicotiana tabacum) with the dimeric version from the bacterium, rhodospirillum rubrum, resulted in fully autotrophic and reproductive tobacco plants that required high co(2) concentrations to grow (whitney sm, andrews tj [2001] proc natl acad sci usa 98: 14738-14743). growth and photosynthesis of these plants was compared with that of nontransforme ...200312970494
tryptophan phosphorescence spectroscopy reveals that a domain in the nad(h)-binding component (di) of transhydrogenase from rhodospirillum rubrum has an extremely rigid and conformationally homogeneous protein core.the characteristics of tryptophan phosphorescence from the nad(h)-binding component (di) component of rhodospirillum rubrum transhydrogenase are described. this enzyme couples hydride transfer between nad(h) and nadp(h) to proton translocation across a membrane and is only active as a dimer. tryptophan phosphorescence spectroscopy is a sensitive technique for the detection of protein conformational changes and was used here to characterize di under mechanistically relevant conditions. our result ...200312972415
removal of organics and nutrients from tannery effluent by advanced integrated wastewater pond systems technology.in this study, a pilot-scale experiment was carried out on a pre-settled combined tannery effluent from modjo tannery, ethiopia, to evaluate the feasibility of the advanced integrated wastewater pond systems or aiwps technology, for the treatment of tannery effluent. the pilot-scale aiwps facility was comprised of an advanced facultative pond (afp), secondary facultative pond (sfp) and maturation pond (mp) all arranged in series. three feed phases with low, moderate and overloading organic loadi ...200314510225
probing the transmembrane potential of bacterial cells by voltage-sensitive dyes.fluorescent dyes have been widely employed as optical indicators of the membrane potential difference in cells, isolated organelles and lipid vesicles that are too small to make microelectrode measurements feasible. we describe here the application of a carbocyanine dye, 3,3'-dipropylthiodicarbocyanine iodide [dis-c3-(5)], to monitor the transmembrane potential changes induced by a variation of the k+ concentration for the cells of escherichia (e.) coli and photosynthetic bacterium rhodospirillu ...200314516073
determination of the b820 subunit size of a bacterial core light-harvesting complex by small-angle neutron scattering.the b820 subunit is an integral pigment-membrane protein complex and can be obtained by both dissociation of the core light-harvesting complex (lh1) in photosynthetic bacteria and reconstitution from its component parts in the presence of n-octyl beta-d-glucopyranoside (og). intrinsic size of the b820 subunit from rhodospirillum rubrum lh1 complex was measured by small-angle neutron scattering in perdeuterated og solution and evaluated by guinier analysis. both the b820 subunits prepared by diss ...200314516207
a functional link between rubisco-like protein of bacillus and photosynthetic rubisco.the genomes of several nonphotosynthetic bacteria, such as bacillus subtilis, and some archaea include genes for proteins with sequence homology to the large subunit of ribulose bisphosphate carboxylase/oxygenase (rubisco). we found that such a rubisco-like protein (rlp) from b. subtilis catalyzed the 2,3-diketo-5-methylthiopentyl-1-phosphate enolase reaction in the methionine salvage pathway. a growth-defective mutant, in which the gene for this rlp had been disrupted, was rescued by the gene f ...200314551435
conformational change in the nadp(h) binding domain of transhydrogenase defines four states.proton-translocating transhydrogenase (th) couples direct and stereospecific hydride transfer between nad(h) and nadp(h), bound to soluble domains di and diii, respectively, to proton translocation across a membrane bound domain, dii. the reaction occurs with proton-gradient coupled conformational changes, which affect the energetics of substrate binding and interdomain interactions. the crystal structure of th diii from rhodospirillum rubrum has been determined in the presence of nadph (2.4 a) ...200314567675
the role of the hydrophobic distal heme pocket of cooa in ligand sensing and response.cooa from rhodospirillum rubrum is a heme-containing transcriptional activator that becomes activated only upon binding co. the basis for this specificity has been probed in a cooa variant, termed deltap3r4 cooa, lacking two residues adjacent to the pro(2) heme ligand, which weakens that ligand. deltap3r4 cooa can bind imidazole and cn(-), as well as co, and form a 6-coordinate low spin adduct with each. however, in contrast to the case with co, imidazole and cn(-) do not stimulate the dna bindi ...200312433917
structural analysis of the reaction center light-harvesting complex i photosynthetic core complex of rhodospirillum rubrum using atomic force microscopy.the bacterium rhodospirillum rubrum contains a simple photosynthetic system, in which the reaction center (rc) receives energy from the light-harvesting (lh1) complex. we have used high-resolution atomic force microscopy (afm) to image two-dimensional crystals of the rc-lh1 complex of r. rubrum. the afm topographs show that the rc-lh1 complex is approximately 94 a in height, the rc-h subunit protrudes from the cytoplasmic face of the membrane by 40 a, and it sits 21 a above the highest point of ...200414578348
hydrophobic pockets at the membrane interface: an original mechanism for membrane protein interactions.the effect of partial digestion by trypsin and gluc protease on the association of the membrane polypeptides of lh1 from rhodospirillum (rsp.) rubrum was studied. trypsin and gluc protease treatments of lh1 result in the cleavage of the first three amino acids from the alpha polypeptide and of the first 18 amino acids from the beta polypeptide, respectively, without any noticeable reorganization of their secondary structure, as measured by attenuated total reflectance fourier transform ir spectr ...200414756563
Displaying items 1901 - 2000 of 2252