Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| 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 ... | 2001 | 11401579 |
| 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 ... | 2001 | 11412108 |
| 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 ... | 2001 | 11412114 |
| 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 ... | 2001 | 11416171 |
| 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 ... | 2001 | 11422366 |
| 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 ... | 2001 | 11487580 |
| 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 ... | 2001 | 11507093 |
| 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 ... | 2001 | 11522788 |
| 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 ... | 2001 | 11525385 |
| the dimerization of folded monomers of ribulose 1,5-bisphosphate carboxylase/oxygenase. | spontaneous refolding and reconstitution processes of dimeric ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) from rhodospirillum rubrum have been investigated using size-exclusion high performance liquid chromatography (hplc), spectroscopic, and activity measurements. when the unfolded rubisco in guanidine hydrochloride is diluted at 4 degrees c, a folding intermediate (rubisco-i) is rapidly formed, which remains in an unstable monomeric state and gradually develops into folded monome ... | 2001 | 11092881 |
| effects of specific amino acid substitutions on activities of dinitrogenase reductase-activating glycohydrolase from rhodospirillum rubrum. | site-directed mutagenesis of the drag gene was used to generate altered forms of dinitrogenase reductase-activating glycohydrolase (drag) with d123a, h142l, h158n, d243g, and e279r substitutions. the amino acid residues h142 and e279 are not required either for the coordination to the metal center or for catalysis since the variants h142l and e279r retained both catalytic and electron paramagnetic resonance spectral properties similar to those of the wild-type enzyme. since drag-h158n and drag-d ... | 2001 | 11544238 |
| the heme pocket afforded by gly117 is crucial for proper heme ligation and activity of cooa. | cooa, a co-sensing homodimeric transcription activator from rhodospirillum rubrum, undergoes a conformational change in response to co binding to its heme prosthetic group that allows it to bind specific dna sequences. in a recent structural study (lanzilotta, w. n., schuller, d. j., thorsteinsson, m. v., kerby, r. l., roberts, g. p., and poulos, t. l. (2000) nat. struct. biol. 7, 876-880), it was suggested that co binding to cooa results in a modest repositioning of the c-helices that serve as ... | 2001 | 11551932 |
| detection of bacteria in environmental samples by direct pcr without dna extraction. | cultured cells and environmental samples were used directly in pcrs without the isolation of dna. serial dilution was used to eliminate the inhibitory effect of materials in natural samples. primers specific for pmoa, which encodes a subunit of the particulate methane monooxygenase, were used to detect and quantify methanotrophic bacteria by direct most probable number pcr. phototrophic bacteria were detected in environmental samples by direct pcr with primers specific for pufm, and members of t ... | 2001 | 11570503 |
| fast hydride transfer in proton-translocating transhydrogenase revealed in a rapid mixing continuous flow device. | transhydrogenase couples the redox reaction between nad(h) and nadp(h) to proton translocation across a membrane. coupling is achieved through changes in protein conformation. upon mixing, the isolated nucleotide-binding components of transhydrogenase (di, which binds nad(h), and diii, which binds nadp(h)) form a catalytic di(2).diii(1) complex, the structure of which was recently solved by x-ray crystallography. the fluorescence from an engineered trp in diii changes when bound nadp(+) is reduc ... | 2001 | 11577115 |
| functional characterization of three glnb homologs in the photosynthetic bacterium rhodospirillum rubrum: roles in sensing ammonium and energy status. | the glnb (p(ii)) protein, the product of glnb, has been characterized previously in the photosynthetic bacterium rhodospirillum rubrum. here we describe identification of two other p(ii) homologs in this organism, glnk and glnj. although the sequences of these three homologs are very similar, the molecules have both distinct and overlapping functions in the cell. while glnb is required for activation of nifa activity in r. rubrum, glnk and glnj do not appear to be involved in this process. in co ... | 2001 | 11591658 |
| conformational dynamics of the transcriptional regulator cooa protein studied by subpicosecond mid-infrared vibrational spectroscopy. | cooa, which is a transcriptional regulator heme protein allosterically triggered by co, is studied by femtosecond visible-pump mid-ir-probe spectroscopy. transient bleaching upon excitation of the heme in the soret band is detected at approximately 1979 cm(-1), which is the absorption region of the co bound to the heme. the bleach signal shows a nonexponential decay with time constants of 56 and 290 ps, caused by the rebinding of the co to the heme. about 98% of dissociated co recombines geminat ... | 2001 | 11592884 |
| life on carbon monoxide: x-ray structure of rhodospirillum rubrum ni-fe-s carbon monoxide dehydrogenase. | a crystal structure of the anaerobic ni-fe-s carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum has been determined to 2.8-a resolution. the codh family, for which the r. rubrum enzyme is the prototype, catalyzes the biological oxidation of co at an unusual ni-fe-s cluster called the c-cluster. the ni-fe-s c-cluster contains a mononuclear site and a four-metal cubane. surprisingly, anomalous dispersion data suggest that the mononuclear site contains fe and not ni, and the four-metal ... | 2001 | 11593006 |
| time-dependent changes in the carotenoid composition and preferential binding of spirilloxanthin to the reaction center and anhydrorhodovibrin to the lh1 antenna complex in rhodobium marinum. | carotenoids were isolated from the cells of rhodobium marinum, and their structures were determined by mass spectrometry and 1h nuclear magnetic resonance spectroscopy; the carotenoids include lycopene, rhodopin, anhydrorhodovibrin, rhodovibrin and spirilloxanthin. time-dependent changes in the carotenoid composition in the reaction center (rc) and the light-harvesting complex 1 (lh1) were traced by high-performance liquid chromatography analysis of the extracts. the carotenoid composition chang ... | 2001 | 11594059 |
| a transcriptional regulator of a pristinamycin resistance gene in streptomyces coelicolor. | pip is a pristinamycin-induced transcriptional regulator protein detected in many streptomyces species by its ability to specifically bind sequence motifs within the promoter of a streptomyces pristinaespiralis multidrug resistance gene (ptr). to investigate the possible role of pip in regulating multidrug resistance, it was purified from a genetically characterized species, streptomyces coelicolor, utilizing an affinity matrix of the ptr promoter conjugated to magnetic beads. reverse genetics i ... | 2001 | 11050092 |
| taxonomic ambiguities: a case history. | 2001 | 11321118 | |
| rhodocista centenaria vs rhodospirillum centenum: a reply to gest and favinger. | 2001 | 11321119 | |
| 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 ... | 2002 | 11835134 |
| 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 ... | 2002 | 11872709 |
| 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 ... | 2002 | 11909118 |
| 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 ... | 2002 | 12484747 |
| 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. | 2002 | 12240998 |
| 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) ... | 2002 | 12269824 |
| 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 ... | 2002 | 12297309 |
| 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 ... | 2002 | 12374822 |
| 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 ... | 2002 | 12375098 |
| 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); ... | 2002 | 12379117 |
| 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 ... | 2002 | 12423751 |
| 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 ... | 2002 | 11814363 |
| 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 ... | 2002 | 11832943 |
| 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 ... | 2002 | 11909121 |
| 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 ... | 2002 | 11916683 |
| 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 ... | 2002 | 11916874 |
| 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 ... | 2002 | 11772000 |
| 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 ... | 2002 | 11806936 |
| 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 ... | 2002 | 11948156 |
| 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 ... | 2002 | 11956221 |
| 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 ... | 2002 | 11959099 |
| [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 ... | 2002 | 11969165 |
| 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. ... | 2002 | 11972067 |
| photosynthetic apparatus of purple bacteria. | 2002 | 11997980 | |
| 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 ... | 2002 | 12000965 |
| 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 ... | 2002 | 12018287 |
| 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 ... | 2002 | 12023037 |
| 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 ... | 2002 | 12056804 |
| 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 ... | 2002 | 12105926 |
| 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 ... | 2002 | 12121986 |
| 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 ... | 2002 | 12145194 |
| 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 ... | 2002 | 12148640 |
| 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 ... | 2002 | 12202393 |
| 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 ... | 2002 | 12203017 |
| 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 ... | 2002 | 12206884 |
| 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 ... | 2002 | 12206892 |
| 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. | 2002 | 16245111 |
| 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 ... | 2003 | 16245044 |
| 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 ... | 2003 | 16228601 |
| 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 ... | 2003 | 16228604 |
| 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 ... | 2003 | 12433917 |
| 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 ... | 2003 | 12507482 |
| 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 ... | 2003 | 12524297 |
| 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 ... | 2003 | 12538050 |
| 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 ... | 2003 | 12563032 |
| 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 ... | 2003 | 12564924 |
| 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 ... | 2003 | 12570608 |
| 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 ... | 2003 | 12570988 |
| 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 ... | 2003 | 12604603 |
| [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 ... | 2003 | 12630112 |
| 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 ... | 2003 | 12636267 |
| 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 ... | 2003 | 12658333 |
| ni and co: more surprises. | 2003 | 12660715 | |
| 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 ... | 2003 | 12669192 |
| 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 ... | 2003 | 12679860 |
| 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 ... | 2003 | 12708850 |
| 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 ... | 2003 | 12719425 |
| 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 ... | 2003 | 12796503 |
| 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. ... | 2003 | 12876344 |
| 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 ... | 2003 | 12882553 |
| 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 ... | 2003 | 12892484 |
| 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 ... | 2003 | 12945578 |
| 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 ... | 2003 | 12950162 |
| 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 ... | 2003 | 12970494 |
| 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 ... | 2003 | 12972415 |
| 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 ... | 2003 | 14516073 |
| 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 ... | 2003 | 14602616 |
| 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 ... | 2003 | 14690421 |
| proton translocation by transhydrogenase. | 2003 | 14630339 | |
| 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 ... | 2003 | 14660342 |
| 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 ... | 2003 | 14670604 |
| 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 ... | 2003 | 14671325 |
| 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 ... | 2003 | 14551435 |
| 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 ... | 2003 | 14510225 |
| 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) ... | 2003 | 14567675 |
| 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 ... | 2003 | 14622029 |
| 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 ... | 2003 | 14516207 |
| 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 ... | 2004 | 14578348 |
| dual flagellar systems enable motility under different circumstances. | flagella are extremely effective organelles of locomotion used by a variety of bacteria and archaea. some bacteria, including aeromonas, azospirillum, rhodospirillum, and vibrio species, possess dual flagellar systems that are suited for movement under different circumstances. swimming in liquid is promoted by a single polar flagellum. swarming over surfaces or in viscous environments is enabled by the production of numerous peritrichous, or lateral, flagella. the polar flagellum is produced con ... | 2004 | 15170400 |