investigation of the role of the n-terminal proline, the distal heme ligand in the co sensor cooa.a unique feature of cooa, a heme-containing transcription factor, is that the n-terminal proline is the distal heme ligand in the ferrous state, and this ligand is displaced upon co binding. to investigate the importance of pro(2) in co-dependent dna binding, several cooa variants that alter n-terminal ligation were characterized. electronic absorption, electron paramagnetic resonance, and magnetic circular dichroism spectra of these variants provide the most definitive evidence that pro(2) is t ...200415518565
spectroscopic and redox properties of a cooa homologue from carboxydothermus hydrogenoformans.cooa is a co-sensing transcriptional activator that contains a b-type heme as the active site for sensing its physiological effector, co. in this study, the spectroscopic and redox properties of a new cooa homologue from carboxydothermus hydrogenoformans (ch-cooa) were studied. spectroscopic and mutagenesis studies revealed that his-82 and the n-terminal alpha-amino group were the axial ligands of the fe(iii) and fe(ii) hemes in ch-cooa and that the n-terminal alpha-amino group was replaced by c ...200515537640
cooa, a paradigm for gas sensing regulatory proteins.the heme-containing transcriptional factor cooa regulates the expression of genes involved in the oxidation of carbon monoxide (co) in the bacterium rhodospirillum rubrum. cooa is both a redox sensor and a specific co sensor, a combination of properties that is unique among heme proteins. extensive biochemical and genetic analyses, interpreted in the context of a crystal structure of one form of the protein, have allowed the creation of hypotheses concerning the mechanism of cooa activation by c ...200515598507
carotenoid-induced cooperative formation of bacterial photosynthetic lh1 complex.a simple reconstitution technique has been developed and then applied to prepare a series of light-harvesting antenna 1 (lh1) complexes with a programmed carotenoid composition, not available from native photosynthetic membranes. the complexes were reconstituted with different c(40) carotenoids, having two structural parameters variable: the functional side groups and the number of conjugated c-c double bonds, systematically increasing from 9 to 13. the complexes, differing only in the type of c ...200415610043
combined afm and confocal fluorescence microscope for applications in bio-nanotechnology.we present a custom-designed atomic force fluorescence microscope (affm), which can perform simultaneous optical and topographic measurements with single molecule sensitivity throughout the whole visible to near-infrared spectral region. integration of atomic force microscopy (afm) and confocal fluorescence microscopy combines the high-resolution topographical imaging of afm with the reliable (bio)-chemical identification capability of optical methods. the affm is equipped with a spectrograph en ...200515655068
conformational diversity in nad(h) and interacting transhydrogenase nicotinamide nucleotide binding domains.transhydrogenase (th) couples direct and stereospecific hydride transfer between nad(h) and nadp(h), bound within soluble domains i and iii, respectively, to proton translocation across membrane bound domain ii. the cocrystal structure of rhodospirillum rubrum th domains i and iii has been determined in the presence of limiting nadh, under conditions in which the subunits reach equilibrium during crystallization. the crystals contain three heterotrimeric complexes, di(2)diii, in the asymmetric u ...200415670609
glnd is essential for nifa activation, ntrb/ntrc-regulated gene expression, and posttranslational regulation of nitrogenase activity in the photosynthetic, nitrogen-fixing bacterium rhodospirillum rubrum.glnd is a bifunctional uridylyltransferase/uridylyl-removing enzyme and is thought to be the primary sensor of nitrogen status in the cell. it plays an important role in nitrogen assimilation and metabolism by reversibly regulating the modification of p(ii) proteins, which in turn regulate a variety of other proteins. we report here the characterization of glnd mutants from the photosynthetic, nitrogen-fixing bacterium rhodospirillum rubrum and the analysis of the roles of glnd in the regulation ...200515687189
the puhb protein of rhodobacter capsulatus functions in photosynthetic reaction center assembly with a secondary effect on light-harvesting complex 1.the core of the photosynthetic apparatus of purple photosynthetic bacteria such as rhodobacter capsulatus consists of a reaction center (rc) intimately associated with light-harvesting complex 1 (lh1) and the pufx polypeptide. the abundance of the rc and lh1 components was previously shown to depend on the product of the puhb gene (formerly known as orf214). we report here that disruption of puhb diminishes rc assembly, with an indirect effect on lh1 assembly, and reduces the amount of pufx. und ...200515687197
l-malyl-coenzyme a/beta-methylmalyl-coenzyme a lyase is involved in acetate assimilation of the isocitrate lyase-negative bacterium rhodobacter capsulatus.cell extracts of rhodobacter capsulatus grown on acetate contained an apparent malate synthase activity but lacked isocitrate lyase activity. therefore, r. capsulatus cannot use the glyoxylate cycle for acetate assimilation, and a different pathway must exist. it is shown that the apparent malate synthase activity is due to the combination of a malyl-coenzyme a (coa) lyase and a malyl-coa-hydrolyzing enzyme. malyl-coa lyase activity was 20-fold up-regulated in acetate-grown cells versus glucose- ...200515687206
no evidence for a forced-unfolding mechanism during atp/groes binding to substrate-bound groel: no observable protection of metastable rubisco intermediate or groel-bound rubisco from tritium tritium-hydrogen exchange experiments, the large groel substrate rubisco was unfolded and exchanged in urea/acid/tritiated water, then diluted into either protic buffer or protic buffer containing groel. the respective rubisco metastable folding intermediate or rubisco-groel binary complex was then separated from residual tritium after varying times of exchange by centrifugation through p-10 or g-25 resin. no significant tritium was recovered in either case, in contrast to an earlier report. ...200515710410
a che-like signal transduction cascade involved in controlling flagella biosynthesis in rhodospirillum centenum.rhodospirillum centenum is a photosynthetic bacterium capable of undergoing swim cell to swarm cell differentiation that allows this species to be motile on both liquid and solid media. previous experiments have demonstrated that the che1 operon is required for the control of chemotactic and phototactic behaviour of both swim and swarm cells. in this report, we analyse the function of a second che-like gene cluster in r. centenum, the che2 gene cluster. in-frame deletion mutants of chew2, cheb2, ...200515720548
solution structures of the core light-harvesting alpha and beta polypeptides from rhodospirillum rubrum: implications for the pigment-protein and protein-protein interactions.we have determined the solution structures of the core light-harvesting (lh1) alpha and beta-polypeptides from wild-type purple photosynthetic bacterium rhodospirillum rubrum using multidimensional nmr spectroscopy. the two polypeptides form stable alpha helices in organic solution. the structure of alpha-polypeptide consists of a long helix of 32 amino acid residues over the central transmembrane domain and a short helical segment at the n terminus that is followed by a three-residue loop. pigm ...200515740753
fluorescence microscopical investigation of poly(3-hydroxybutyrate) granule formation in bacteria.the early stages of poly(3-hydroxybutyrate) (phb) accumulation were analyzed in vivo by fluorescence microscopy in rhodospirillum rubrum, ralstonia eutropha, and in recombinant escherichia coli harboring the phb biosynthesis genes phacab of r. eutropha. phb granules were stained with nile red and by expression of a phasin-enhanced yellow fluorescent protein fusion protein. distribution of phb granules at the early stages of phb accumulation frequently occurred near the cell poles and near the ce ...200515762619
the presumptive magnetosome protein mms16 is a poly(3-hydroxybutyrate) granule-bound protein (phasin) in magnetospirillum gryphiswaldense.the mms16 protein has been previously found to be associated with isolated magnetosomes from two magnetospirillum strains. a function of this protein as a magnetosome-specific gtpase involved in the formation of intracellular magnetosome membrane vesicles was suggested. here we present a study of the mms16 protein from magnetospirillum gryphiswaldense to clarify its function. insertion-duplication mutagenesis of the mms16 gene did not affect the formation of magnetosome particles but resulted in ...200515774885
near-ir absorption and fluorescence spectra and afm observation of the light-harvesting 1 complex on a mica substrate refolded from the subunit light-harvesting 1 complexes of photosynthetic bacteria rhodospirillum rubrum.the subunit light-harvesting 1 (lh 1) complexes isolated from photosynthetic bacteria rhodospirillum rubrum using n-octyl-beta-glucoside were reassociated and adsorbed on a mica substrate using spin-coat methods with the aim of using this lh complex in a nanodevice. the near-ir absorption and fluorescence spectra of the lh 1 complexes indicated that the lh 1 complex on the mica was stable, and efficient energy transfer from a carotenoid to a bacteriochlorophyll a was observed. atomic force micro ...200515779986
trapping of an assembly intermediate of photosynthetic lh1 antenna beyond b820 subunit. significance for the assembly of photosynthetic lh1 antenna.most photosynthetic lh1 antennae undergo dissociation into b820 subunits, suggesting their universal character as structural modules. however, dissociation into subunits seems to occur reversibly only in the absence of carotenoids and the subunits were never found to bind carotenoids. the interactions of carotenoids with b820 have been studied in a newly developed reconstitution assay of the lh1 antenna from rhodospirillum rubrum (fiedor, l., akahane, j., and koyama, y. (2004) biochemistry 43, 1 ...200515788392
dual roles of an e-helix residue, glu167, in the transcriptional activator function of cooa.cooa is a transcriptional activator that mediates co-dependent expression of the genes responsible for co oxidation in rhodospirillum rubrum. in this study, we suggest in vitro and in vivo models explaining an unusual requirement of cooa for millimolar levels of divalent cations for high-affinity dna binding. several lines of evidence indicate that an e-helix residue, glu167, plays a central role in this requirement by inhibiting sequence-specific dna binding via charge repulsion in the absence ...200515805503
electron transport to nitrogenase in rhodospirillum rubrum: identification of a new fdxn gene encoding the primary electron donor to our efforts to determine the components participating in the electron transport to nitrogenase in rhodospirillum rubrum, we have identified a gene encoding a new ferredoxin. we have generated mutants in both the new ferredoxin and ferredoxin i and demonstrate that the new ferredoxin, fdn and not the previously identified fdi is the main donor of electrons to nitrogenase.200515837392
titration of e. coli transhydrogenase domain iii with bound nadp+ or nadph studied by nmr reveals no ph-dependent conformational change in the physiological ph range.a ph-titration 2d nmr study of escherichia coli transhydrogenase domain iii with bound nadp(+) or nadph has been carried out, in which the ph was varied between 5.4 and 12. in this analysis, individual amide protons served as reporter groups. the apparent pk(a) values of the amide protons, determined from the ph-dependent chemical shift changes, were attributed to actual pk(a) values for several titrating residues in the protein. the essential asp392 is shown to be protonated at neutral ph in bo ...200415863102
zinc ions selectively inhibit steps associated with binding and release of nadp(h) during turnover of proton-translocating transhydrogenase.transhydrogenase couples the redox reaction between nad(h) and nadp(h) to proton translocation across a membrane. in membrane vesicles from escherichia coli and rhodospirillum rubrum, the transhydrogenase reaction (measured in the direction driving inward proton translocation) was inhibited by zn(2+) and cd(2+). however, depending on ph, the metal ions either had no effect on, or stimulated, "cyclic" transhydrogenation. they must, therefore, interfere specifically with steps involving binding/re ...200515878164
involvement of a che-like signal transduction cascade in regulating cyst cell development in rhodospirillum centenum.homologues of the e. coli chemotaxis (che) signal transduction pathway are present in nearly all motile bacteria. although e. coli contains only one che cascade, many other bacteria are known to possess multiple sets of che genes. the role of multiple che-like gene clusters could potentially code for parallel che-like signal transduction pathways that have distinctly different input and output functions. in this study, we describe a che-like gene cluster in rhodospirillum centenum that controls ...200515916598
watching the components of photosynthetic bacterial membranes and their in situ organisation by atomic force microscopy.the atomic force microscope has developed into a powerful tool in structural biology allowing information to be acquired at submolecular resolution on the protruding structures of membrane proteins. it is now a complementary technique to x-ray crystallography and electron microscopy for structure determination of individual membrane proteins after extraction, purification and reconstitution into lipid bilayers. moving on from the structures of individual components of biological membranes, atomi ...200515919049
tributyl phosphate degradation by rhodopseudomonas palustris and other photosynthetic bacteria.tributyl phosphate (tbp) is widely used in nuclear fuel processing and other waste generating chemical industries. although tbp is bacteriostatic, some microbes are resistant to it and may degrade it. under dark aerobiosis, purple non-sulfur photosynthetic bacteria degraded up to 0.6 mm tbp, initially present at 2 mm, within 3 weeks and under photosynthetic conditions, rhodopseudomonas palustris degraded 1.6 mm tbp within 3 weeks. the curing of the rhodopseudomonas palustris endogenous plasmid d ...200515973490
chromatic adaptation of photosynthetic membranes.many biological membranes adapt in response to environmental conditions. we investigated how the composition and architecture of photosynthetic membranes of a bacterium change in response to light, using atomic force microscopy. despite large modifications in the membrane composition, the local environment of core complexes remained unaltered, whereas specialized paracrystalline light-harvesting antenna domains grew under low-light conditions. thus, the protein mixture in the membrane shows eute ...200516020739
detecting proton flux across chromatophores driven by f0f1-atpase using n-(fluorescein-5-thiocarbamoyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine, triethylammonium salt.n-(fluorescein-5-thiocarbamoyl)-1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine, triethylammonium salt (f-dhpe) is a lipid fluorescence dye sensitive to ph changes and is used in this study for detecting proton flux through f0f1-atpase within chromatophores driven by atp hydrolysis. f-dhpe is easily labeled to the outer surface of chromatophores. in the range of ph 7.0 to 9.0, fluorescence intensity is sensitive to ph changes. the sensitivity is especially great in the range of ph 8.2 to 9.0 ...200516043113
x-ray structure of domain i of the proton-pumping membrane protein transhydrogenase from escherichia coli.the dimeric integral membrane protein nicotinamide nucleotide transhydrogenase is required for cellular regeneration of nadph in mitochondria and prokaryotes, for detoxification and biosynthesis purposes. under physiological conditions, transhydrogenase couples the reversible reduction of nadp+ by nadh to an inward proton translocation across the membrane. here, we present crystal structures of the nad(h)-binding domain i of transhydrogenase from escherichia coli, in the absence as well as in th ...200516083909
multivariate analysis of single-molecule spectra: surpassing spectral diffusion.the full exploitation of single-molecule spectroscopy in disordered systems is often hampered by spectral diffusion processes of the optical transitions due to structural fluctuations in the local environment of the probe molecule which leads to temporal averaging of the signal. multivariate statistical pattern recognition techniques, originally developed for single-molecule cryoelectron microscopy, allow us to retrieve detailed information from optical single-molecule spectra. as an example, we ...200516090183
[the mechanism of acetate assimilation in purple nonsulfur bacteria lacking the glyoxylate pathway: enzymes of the citramalate cycle in rhodobacter sphaeroides].the mechanism of acetate assimilation by the purple nonsulfur bacterium rhodobacter sphaeroides, which lacks the glyoxylate shortcut, has been studied. in a previous work, proceeding from data on acetate assimilation by rba. sphaeroides cell suspensions, a suggestion was made regarding the operation, in this bacterium, of the citramalate cycle. this cycle was earlier found in rhodospirillum rubrum in the form of an anaplerotic reaction sequence that operates during growth on acetate instead of t ...200516119844
whole-genome shotgun optical mapping of rhodospirillum rubrum.rhodospirillum rubrum is a phototrophic purple nonsulfur bacterium known for its unique and well-studied nitrogen fixation and carbon monoxide oxidation systems and as a source of hydrogen and biodegradable plastic production. to better understand this organism and to facilitate assembly of its sequence, three whole-genome restriction endonuclease maps (xbai, nhei, and hindiii) of r. rubrum strain atcc 11170 were created by optical mapping. optical mapping is a system for creating whole-genome o ...200516151144
defluvicoccus vanus gen. nov., sp. nov., a novel gram-negative coccus/coccobacillus in the 'alphaproteobacteria' from activated sludge.a novel gram-negative coccus/coccobacillus, strain ben 114(t), growing in tetrads, clusters or aggregates, was isolated from activated sludge by micromanipulation. 16s rrna gene sequence analysis revealed that it belonged to the 'alphaproteobacteria', with no close relatives among cultured bacterial isolates. on the basis of phylogenetic data, this organism is considered to belong to a new genus, defluvicoccus, represented by the species defluvicoccus vanus sp. nov., a name chosen because of the ...200516166717
heme-thiolate proteins.cytochrome p450 was the first hemoprotein found to have a thiolate anion as the axial ligand of the heme. several other heme-thiolate proteins, including nitric oxide synthase, were later found in animals, plants, and microorganisms. both cytochrome p450 and nitric oxide synthase, two major members of the heme-thiolate protein family, catalyze monooxygenase reactions, but the physiological functions of other heme-thiolate proteins are apparently highly diverse. chloroperoxidase of a mold, caldar ...200516198303
the pufx protein of rhodobacter capsulatus affects the properties of bacteriochlorophyll a and carotenoid pigments of light-harvesting complex 1.a pufx gene deletion in the purple bacterium rhodobacter capsulatus causes a severe photosynthetic defect and increases core light-harvesting complex (lh1) protein and bacteriochlorophyll a (bchl) levels. it was suggested that pufx interrupts the lh1 alpha/beta ring around the reaction centre, allowing quinone/quinol exchange. however, naturally pufx(-) purple bacteria grow photosynthetically with an uninterrupted lh1. we discovered that substitutions of the rhodobacter-specific lh1 alpha seryl- ...200516212932
nad-, nmn-, and nadp-dependent modification of dinitrogenase reductases from rhodospirillum rubrum and azotobacter vinelandii.nitrogenase activity in the photosynthetic bacterium rhodospirillum rubrum is reversibly regulated by adp-ribosylation of a specific arginine residue of dinitrogenase reductase based on the cellular nitrogen or energy status. in this paper, we have investigated the ability of nicotinamide adenine dinucleotide, nad (the physiological adp-ribose donor), and its analogs to support covalent modification of dinitrogenase reductase in vitro. r. rubrum dinitrogenase reductase can be modified by drat in ...200516225869
efficient light harvesting through carotenoids.we review the factors that control the efficiency of carotenoid-chlorophyll excitation transfer in photosynthetic light harvesting. for this we summarize first the recently developed theory that describes electronic couplings between carotenoids and chlorophylls and we outline in particular the influence of length of conjugated system and of symmetry breaking on the couplings. we focus hereby on the structurally solved lycopene-bchl system of lh 2 from rhodospirillum molischianum and the peridin ...200016228415
cloning, sequencing and analysis of the pucc genes from rubrivivax gelatinosus strain 151 and rhodopseudomonas acidophila strain 10050.the pucc genes of rubrivivax gelatinosus strain 151 and rhodopseudomonas acidophila strain 10050 have been identified, cloned and sequenced. in rubrivivax gelatinosus the arrangement of the pucc gene with regard to the pucba genes was shown to differ from that found in other species of photosynthetic bacteria. the rhodopseudomonas acidophila pucc was found downstream of four new pucba gene pairs, bringing the sequenced pucba pairs to a total of eight in this strain. the predicted pucc protein se ...200016228472
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
reversible membrane association of dinitrogenase reductase activating glycohydrolase in the regulation of nitrogenase activity in rhodospirillum rubrum; dependence on glnj and the photosynthetic bacterium rhodospirillum rubrum nitrogenase activity is regulated by reversible adp-ribosylation of dinitrogenase reductase in response to external so called "switch-off" effectors. activation of the modified, inactive form is catalyzed by dinitrogenase reductase activating glycohydrolase (drag) which removes the adp-ribose moiety. this study addresses the signal transduction between external effectors and drag. r. rubrum, wild-type and p(ii) mutant strains, were studied wi ...200516243452
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
nitrogen fixation by photosynthetic 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
re-identification of the n-terminal amino acid residue and its modification of +/-bbeta-polypeptide of light-harvesting complex i from rhodospirillum rubrum. 200116252177
isotopic labeling of proteins by utilizing photosynthetic bacteria. 200516259936
new insights into the mechanism of nickel insertion into carbon monoxide dehydrogenase: analysis of rhodospirillum rubrum carbon monoxide dehydrogenase variants with substituted ligands to the [fe3s4] portion of the active-site c-cluster.carbon monoxide dehydrogenase (codh) from rhodospirillum rubrum catalyzes the oxidation of co to co2. a unique [nife4s4] cluster, known as the c-cluster, constitutes the active site of the enzyme. when grown in ni-deficient medium r. rubrum accumulates a ni-deficient apo form of codh that is readily activated by ni. it has been previously shown that activation of apo-codh by ni is a two-step process involving the rapid formation of an inactive apo-codh*ni complex prior to conversion to the activ ...200516283394
architecture of the native photosynthetic apparatus of phaeospirillum molischianum.the ubiquity and importance of photosynthetic organisms in nature has made the molecular mechanisms of photosynthesis a widely studied subject at both structural and functional levels. a current challenge is to understand the supramolecular assembly of the proteins involved in photosynthesis in native membranes. we have used atomic force microscopy to study the architecture of the photosynthetic apparatus and analyze the structure of single molecules in chromatophores of phaeospirillum molischia ...200516330228
hydrogen production by the photosynthetic bacterium rhodospirillum rubrum.continuous photosynthetic production of hydrogen by rhodospirillum rubrum in batch cultures was observed up to 80 days with the hydrogen donor, pure lactate or lactic acid-containing wastes, supplied periodically. hydrogen was produced at an average rate of 6 ml/h per g (dry weight) of cells with whey as a hydrogen donor. in continuous cultures with glutamate as a growth-limiting nitrogen source and lactate as a hydrogen donor, hydrogen was evolved at a rate of 20 ml/h per g (dry weight). the co ...197916345375
populations of anaerobic phototrophic bacteria in a spartina alterniflora salt marsh.habitat-simulating media were used with the hungate anaerobic roll tube technique to enumerate culturable anaerobic photosynthetic bacteria in sediment, tidal waters, and spartina alterniflora plant samples collected from the salt marsh at sapelo island, ga. no phototrophs were detected in samples of creekside (low marsh) sediment or in tidal waters in creekside regions. in the high marsh region, 90% of anaerobic phototrophic bacteria occurred in the top 5 mm of sediment and none were detected b ...198816347646
modification of the fe protein of nitrogenase in natural populations of trichodesmium thiebautii.the fe protein of nitrogenase in the marine nonheterocystous cyanobacterium trichodesmium thiebautii is interconverted between two forms, which is reminiscent of the adp-ribosylation described in the purple bacterium rhodospirillum rubrum. in natural populations of t. thiebautii during the day, when nitrogenase activity (na) is present and while photosynthetic rates are high, a low-molecular-mass form of the fe protein is present. in the late afternoon, the low-molecular-mass form is partially c ...199316348883
optimization of the sistrom culture medium for large-scale batch cultivation of rhodospirillum rubrum under semiaerobic conditions with maximal yield of photosynthetic membranes.the defined medium a of w. r. sistrom (w. r. sistrom, j. gen. microbiol. 22:77-85, 1960) has been modified to allow the growth of rhodospirillum rubrum in large-scale batch cultures under dark, semiaerobic conditions. the simultaneous use of two substrates, nh(4)-succinate (46 mm) and fructose (0.3%), which are utilized in aerobic and fermentative metabolism, respectively, leads to very high cell densities with a maximal yield of photosynthetic membranes.199416349265
increased nitrogenase-dependent h(2) photoproduction by hup mutants of rhodospirillum rubrum.transposon tn5 mutagenesis was used to isolate mutants of rhodospirillum rubrum which lack uptake hydrogenase (hup) activity. three tn5 insertions mapped at different positions within the same 13-kb ecori fragment (fragment e1). hybridization experiments revealed homology to the structural hydrogenase genes hupslm from rhodobacter capsulatus and hupsl from bradyrhizobium japonicum in a 3.8-kb ecori-clai subfragment of fragment e1. it is suggested that this region contains at least some of the st ...199416349271
spectral trends in the fluorescence of single bacterial light-harvesting complexes: experiments and modified redfield this work we present and discuss the single-molecule fluorescence spectra of a variety of species of light-harvesting complexes: lh2 of rhodopseudomonas acidophila, rhodobacter sphaeroides, and rhodospirillum molischianum and lh1 of rhodobacter sphaeroides. the emission spectrum of these complexes varies as a function of time as was described in earlier work. for each type of complex, we observe a pronounced and well-reproducible characteristic relationship between the fluorescence spectral p ...200616399834
comparative study of spectral flexibilities of bacterial light-harvesting complexes: structural implications.this work presents a comparative study of the frequencies of spectral jumping of individual light-harvesting complexes of six different types: lh2 of rhodopseudomonas acidophila, rhodobacter sphaeroides, and rhodospirillum molischianum; lh1 of rhodobacter sphaeroides; and two "domain swap mutants" of lh2 of rhodobacter sphaeroides: paclh1 and paclh2mol, in which the alpha-polypeptide c-terminus is exchanged with the corresponding sequence from lh1 of rhodobacter sphaeroides or lh2 of rhodospiril ...200616399835
unexpected no-dependent dna binding by the cooa homolog from carboxydothermus hydrogenoformans.cooa, the co-sensing heme protein from rhodospirillum rubrum, regulates the expression of genes that encode a co-oxidation system, allowing r. rubrum to use co as a sole energy source. to better understand the gas-sensing regulation mechanism used by r. rubrum cooa and its homologs in other organisms, we characterized spectroscopically and functionally the fe(ii), fe(ii)-no, and fe(ii)-co forms of cooa from carboxydothermus hydrogenoformans. surprisingly, and unlike r. rubrum cooa, c. hydrogenof ...200616410360
metabolic regulation of nitrogen fixation in rhodospirillum rubrum.nitrogenase activity in rhodospirillum rubrum is post-translationally regulated by drag (dinitrogenase reductase glycohydrolase) and drat (dinitrogenase reductase adp-ribosylation transferase). when a sudden increase in fixed nitrogen concentration or energy depletion is sensed by the cells, drag is inactivated and drat activated. we propose that the regulation of drag is dependent on its location in the cell and the presence of an ammonium-sensing protein.200616417510
evidence for displacements of the c-helix by co ligation and dna binding to cooa revealed by uv resonance raman spectroscopy.the uv and visible resonance raman spectra are reported for cooa from rhodospirillum rubrum, which is a transcriptional regulator activated by growth in a co atmosphere. co binding to heme in its sensor domain causes rearrangement of its dna-binding domain, allowing binding of dna with a specific sequence. the sensor and dna-binding domains are linked by a hinge region that follows a long c-helix. uv resonance raman bands arising from trp-110 in the c-helix revealed local movement around trp-110 ...200616439368
micro-scale open-tube capillary separations of functional proteins.this article describes a novel technique whereby fully functional proteins or multiprotein complexes are efficiently extracted from biological samples to chemically derivatized walls of fused-silica open-tube capillary columns. proteins are eluted with very high yields into elution volumes that are smaller in volume than the internal volume of the open-tube capillary column itself, thereby achieving 100-fold increases in target protein concentrations from starting samples of less than 1 ml. the ...200616448620
a site-specific mutation within the active site of ribulose-1,5-bisphosphate carboxylase of rhodospirillum vitro mutagenic techniques have generated an asp-->glu substitution at residue 198 adjacent to the carbamate-divalent metal ion binding site of rhodospirillum rubrum ribulose 1,5-bisphosphate carboxylase. a single c-->a nucleotide change in the coding strand created the mutant and introduced a new ecori restriction site on the expression plasmid prr2119. although the carboxylase:oxygenase ratio remained the same, the mutant enzyme had slightly altered kinetic properties. the e.p.r. spectra of ...198416453576
three-dimensional structure of ribulose-1,5-bisphosphate carboxylase/oxygenase from rhodospirillum rubrum at 2.9 a resolution.the three-dimensional structure of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) from rhodospirillum rubrum has been determined at 2.9 a resolution by x-ray crystallographic methods. the mir-electron density map was substantially improved by two-fold non-crystallographic symmetry averaging. the polypeptide chains in the dimer were traced using a graphics display system with the help of the bones option in frodo. the dimer has approximate dimensions of 50 x 72 x 105 a. the enzyme subu ...198616453738
hexacoordination of bacteriochlorophyll in photosynthetic antenna lh1.the ability of chlorophylls to coordinate ligands is of fundamental structural importance for photosynthetic pigment-protein complexes, where in virtually all cases the pigment is thought to be in a pentacoordinated state. in this study, the correlation of the q(x) transition energy with the coordination state of the central metal in bacteriochlorophyll is applied in investigating the pigment coordination state in bacterial photosynthetic antenna lh1. to facilitate a detailed spectral analysis i ...200616460037
design of a minimal polypeptide unit for bacteriochlorophyll binding and self-assembly based on photosynthetic bacterial light-harvesting proteins.we introduce lh1beta24, a minimal 24 amino acid polypeptide that binds and assembles bacteriochlorophylls (bchls) in micelles of octyl beta-glucoside (og) into complexes with spectral properties that resemble those of b820, a universal intermediate in the assembly of native purple bacterial light-harvesting complexes (lhs). lh1beta24 was designed by a survey of sequences and crystal structures of bacterial lh proteins from different organisms combined with currently available information from in ...200616475799
quantum chemical simulation of excited states of chlorophylls, bacteriochlorophylls and their complexes.the present review describes the use of quantum chemical methods in estimation of structures and electronic transition energies of photosynthetic pigments in vacuum, in solution and imbedded in proteins. monomeric mg-porphyrins, chlorophylls and bacteriochlorophylls and their solvent 1:1 and 1:2 complexes were studied. calculations were performed for mg-porphyrin, mg-chlorin, mg-bacteriochlorin, mesochlorophyll a, chlorophylls a, b, c(1), c(2), c(3), d and bacteriochlorophylls a, b, c, d, e, f, ...200616482307
identification of rhodospirillum rubrum glnb variants that are altered in their ability to interact with different targets in response to nitrogen status rhodospirillum rubrum, nifa, the transcriptional activator for the nif genes, is posttranslationally activated only by the uridylylated form of glnb, one of three p(ii) homologs in the organism. we have used the yeast two-hybrid system to detect variants of glnb that interact better with nifa than does wild-type glnb. when examined for physiological effects in r. rubrum, these glnb* variants activated nifa in the presence of nh(4)(+), which normally blocks nifa activation completely, and in t ...200616484197
investigation of the effects of different carotenoids on the absorption and cd signals of light harvesting 1 complexes.absorption and circular dichroism (cd) spectra of light-harvesting (lh)1 complexes from the purple bacteria rhodobacter (rba.) sphaeroides and rhodospirillum (rsp.) rubrum are presented. the complexes exhibit very low intensity, highly nonconservative, near-infrared (nir) cd spectra. absorption and cd spectra from several mutant and reconstituted lh1 complexes, with the carotenoid neurosporene and the precursor phytoene replacing the wild-type (wt) carotenoids, are also examined. the experiments ...200616494350
calculation of absorption spectra for light-harvesting systems using non-markovian approaches as well as modified redfield theory.for an ensemble of b850 rings of the light-harvesting system lh2 of purple bacteria the linear absorption spectrum is calculated. using different markovian and non-markovian, time-dependent and time-independent methods based on second-order perturbation theory in the coupling between the excitonic system and its surrounding environment as well as the modified redfield theory, the influence of the shape of the spectral density on the linear absorption spectrum is demonstrated for single samples a ...200616512738
enzymic systems proposed to be involved in the dissimilatory reduction of selenite in the purple non-sulfur bacteria rhodospirillum rubrum and rhodobacter capsulatus.various enzymic systems, such as nitrite reductase, sulfite reductase and glutathione reductase, have been proposed for, or suspected to be involved in, the reduction of selenite in bacteria. as alphaproteobacteria have been shown to be highly tolerant to transition metal oxyanions, it seemed interesting to investigate the hypothetical involvement of these different enzymes in the reduction of selenite in the purple non-sulfur bacteria rhodospirillum rubrum and rhodobacter capsulatus. the hypoth ...200616514153
the role of invariant amino acid residues at the hydride transfer site of proton-translocating transhydrogenase.transhydrogenase couples proton translocation across a membrane to hydride transfer between nadh and nadp+. previous x-ray structures of complexes of the nucleotide-binding components of transhydrogenase ("di2diii1" complexes) indicate that the dihydronicotinamide ring of nadh can move from a distal position relative to the nicotinamide ring of nadp+ to a proximal position. the movement might be responsible for gating hydride transfer during proton translocation. we have mutated three invariant ...200616533815
subcellular particulate systems and the photochemical apparatus of rhodospirillum rubrum. 195916590502
some observations on the synthesis and function of the photosynthetic apparatus in rhodospirillum rubrum. 196016590780
epr in chromatophores from rhodospirillum rubrum and in quantasomes from spinach chloroplasts. 196216590952
regulation of l-isoleucine biosynthesis in the photosynthetic bacterium rhodospirillum rubrum. 196616591426
c nuclear magnetic resonance study of the co(2) activation of ribulosebisphosphate carboxylase from rhodospirillum rubrum.ribulosebisphosphate carboxylase [3-phospho-d-glycerate carboxy-lyase (dimerizing), ec] from rhodospirillum rubrum is activated by co(2) and mg(2+). (13)c nmr spectra were determined for the unactivated enzyme and for enzyme that had been activated by (13)co(2) and mg(2+). in addition to the expected resonance for h(13)co(3) (-)/co(3) (2-) at 161.8 ppm downfield from tetramethylsilane, the spectrum of the activated enzyme shows a broad resonance at 164.9 ppm. analogy with previous nmr s ...197916592618
structural studies of the primary donor cation radical p(870) in reaction centers of rhodospirillum rubrum by electron-nuclear double resonance in solution.the light-induced cation radical of the primary electron donor, p(870) (+.), in photosynthetic reaction centers from rhodospirillum rubrum g-9, has been investigated by electron-nuclear double resonance (endor) in liquid aqueous solution. the measured hyperfine coupling constants are assigned to specific molecular positions by partial deuteration. comparison with the bacteriochlorophyll a cation radical shows different reduction factors of the individual coupling constants deviating from the val ...198416593428
distance between two active-site lysines of ribulose bisphosphate carboxylase from rhodospirillum the absence of a three-dimensional structure of ribulose-bisphosphate carboxylase/oxygenase [3-phospho-d-glycerate carboxy-lyase(dimerizing), ec], we have probed the distance between two active-site lysyl residues (lys-166 and lys-329) of the rhodospirillum rubrum enzyme with 4,4'-diisothiocyano-2,2'-disulfonate stilbene, a covalent cross-linking reagent that spans 12 a. the reagent rapidly inactivated the carboxylase, and a competitive inhibitor provided substantial protection. to r ...198616593786
a hybrid of the transhydrogenases from rhodospirillum rubrum and mycobacterium tuberculosis catalyses rapid hydride transfer but not the complete, proton-translocating reaction.all transhydrogenases appear to have three components: di, which binds nad(h), and diii, which binds nadp(h), protrude from the membrane, and dii spans the membrane. however, the polypeptide composition of the enzymes varies amongst species. the transhydrogenases of mycobacterium tuberculosis and of rhodospirillum rubrum have three polypeptides. sequence analysis indicates that an ancestral three-polypeptide enzyme evolved into transhydrogenases with either two polypeptides (such as the escheric ...200616624251
the effect of light on the oxygen metabolism of the photosynthetic bacterium, rhodospirillum rubrum. 195416654634
studies on nitrogen fixation and photosynthesis of rhodospirillum rubrum. 195916655226
photooxidase activity of heated chromatophores of rhodospirillum rubrum. 196216655619
biosynthesis of the methoxylated carotenoids in rhodospirillum rubrum. 196416655991
influence of light intensity on reductive pentose phosphate cycle activity during photoheterotrophic growth of rhodospirillum rubrum.light intensity during growth affects the proportion of carbon dioxide fixed by the reductive pentose phosphate cycle relative to that incorporated via c(4) acids in acetate phototrophs of rhodospirillum rubrum. with cells grown at high light intensity (9000 lux) the specific activities of ribulose-1, 5-diphosphate and propionyl coa carboxylases were increased compared with cells grown at low light intensity (1500 lux), although pyruvate carboxylase activity was unaltered.kinetic experiments wit ...197216658151
carbon isotope fractionation by ribulose-1,5-bisophosphate carboxylase from various organisms.carbon isotope fractionation by structurally and catalytically distinct ribulose-1,5-bisphosphate carboxylases from one eucaryotic and four procaryotic organisms has been measured under nitrogen. the average fractionation for 40 experiments was -34.1 per thousand with respect to the delta(13)c of the dissolved co(2) used, although average fractionations for each enzyme varied slightly: spinach carboxylase, -36.5 per thousand; hydrogenomonas eutropha, -38.7 per thousand; agmenellum quadruplicatum ...197816660363
oxidation of c-type cytochromes by the membrane-bound cytochrome oxidase (cytochrome aa(3)) of blue-green algae.respiratory particles containing an aa(3)-type cytochrome oxidase were prepared from anacystis nidulans, synechocystis 6714, synechococcus lividus, anabaena variabilis, nostoc sp. strain mac, nostoc muscorum, and mastigocladus laminosus. oxidation of c-type cytochromes by membrane preparations of the different blue-green algae was observed using purified cytochromes from horse heart, candida krusei, tuna, saccharomyces oviformis, rhodospirillum rubrum, rhodospirillum molischianum, rhodopseudomon ...198216662253
phosphofructokinase activities in photosynthetic organisms : the occurrence of pyrophosphate-dependent 6-phosphofructokinase in plants and algae.a pyrophosphate-dependent phosphofructokinase (ppi-pfk) activity is detectable in extracts of a wide variety of primitive and advanced plants, the charalean algae, and in the photosynthetic bacterium, rhodospirillum rubrum. angiosperms with extractable ppi-pfk activities 4- to 70-fold higher than the respective atp-pfk activities tend to be succulent and to exhibit cam. even though ppi-pfk activity is not detected in crude extracts of some well known cam plants, e.g. plants in the crassulaceae, ...198316662776
kinetic variance of ribulose-1,5-bisphosphate carboxylase/oxygenase isolated from diverse taxonomic sources : ii. analysis by two dual label methods.two dual label methods were used to investigate kinetic variability of ribulose 1,5-bisphosphate (rubp) carboxylase/oxygenase (ec in addition to using [1-(14)c,5-(3)h]rubp (method 1), we describe here the detailed assay with (14)co(2) and [5-(3)h]rubp (method 2), which generates [(3)h,(14)c]3-phosphoglyceric acid and unlabeled (noncontaminating) phosphoglycolate; the carboxylase/oxygenase activity ratio (v(c)/v(o)) is calculated from (3)h/(14)c ratios of substrates and products. v(c)/ ...198416663680
effect of betaine on enzyme activity and subunit interaction of ribulose-1,5-bisphosphate carboxylase/oxygenase from aphanothece halophytica.the presence of betaine, a quaternary ammonium compound, at a concentration (0.5 molar) reported to accumulate inside aphanothece halophytica in response to increasing external salinity, slightly promoted ribulose-1,5-bisphosphate (rubp) carboxylase activity. kcl at 0.25 molar inhibited rubp carboxylase about 55%. betaine relieved the inhibition by 0.25 m kcl and the original uninhibited activity was restored at 1 m betaine. other osmoregulatory solutes such as sucrose and glycerol also reduced ...198616664941
analysis of chromophytic and rhodophytic ribulose-1,5-bisphosphate carboxylase indicates extensive structural and functional similarities among evolutionarily diverse algae.ribulose-1,5-bisphosphate carboxylase (rubisco) from the algae olisthodiscus luteus (chromophyte) and griffithsia pacifica (rhodophyte) are remarkably similar to each other. however, both enzymes differ significantly in the structure and function when compared to rubisco from green algae and land plants. analysis of purified rubisco from o. luteus and g. pacifica indicates that the size of the holoenzyme and stoichiometry of the 55 and 15 kilodalton subunit polypeptides are approximately 550 kil ...198916667160
nitrogenase activity and amounts of nitrogenase proteins in a frankia-alnus incana symbiosis subjected to darkness.effects of prolonged darkness on nitrogenase activity in vivo, nitrogenase activity in vitro, and the amounts of nitrogenase proteins were studied in symbiotic frankia. plants of alnus incana (l.) moench in symbiosis with a local source of frankia were grown for 9 to 10 weeks in an 18/6 hour light/darkness cycle. after 12 hours of a light period, the plants were exposed to darkness for up to 40 hours. nitrogenase activity (acetylene reduction activity) of intact plants was measured repeatedly. f ...199116668058
simple determination of the co(2)/o(2) specificity of ribulose-1,5-bisphosphate carboxylase/oxygenase by the specific radioactivity of [c]glycerate 3-phosphate.a new method is presented for measurement of the co(2)/o(2) specificity factor of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). the [(14)c]3-phosphoglycerate (pga) from the rubisco carboxylase reaction and its dilution by the rubisco oxygenase reaction was monitored by directly measuring the specific radioactivity of pga. (14)co(2) fixation with rubisco occurred under two reaction conditions: carboxylase with oxygenase with 40 micromolar co(2) in o(2)-saturated water and carboxylase ...199216668709
modeling proline ligation in the heme-dependent co sensor, cooa, using small-molecule analogs.cooa, the only protein known to employ proline as a heme ligand, is a co-activated transcription factor found in the bacterium rhodospirillum rubrum. proline is a heme ligand in both the fe(iii) and fe(ii) states; the sixth ligand is cysteinate in fe(iii) cooa and histidine in fe(ii) cooa. when co binds to fe(ii) cooa, it selectively replaces the proline ligand, activating the protein. the proposed roles of proline are to stabilize the heme pocket during the redox-mediated ligand switch and to f ...200616724227
purification and characterization of a catalase from photosynthetic bacterium rhodospirillum rubrum s1 grown under anaerobic conditions.the photosynthetic bacterium, rhodospirillum rubrum s1, when grown under anaerobic conditions, generated three different types of catalases. in this study, we purified and characterized the highest molecular weight catalase from the three catalases. the total specific catalase activity of the crude cell extracts was 88 u/mg. after the completion of the final purification step, the specific activity of the purified catalase was 1,256 u/mg. the purified catalase evidenced an estimated molecular ma ...200616728955
a conserved mechanism controls translation of rubisco large subunit in different photosynthetic organisms.we previously proposed a mechanism for control of rubisco expression and assembly during oxidative stress in chlamydomonas reinhardtii. the n terminus of the large subunit (lsu) comprises an rna recognition motif (rrm) that is normally buried in the protein, but becomes exposed under oxidizing conditions when the glutathione pool shifts toward its oxidized form. thus, de novo translation and assembly of rubisco lsu stop with similar kinetics and the unpaired small subunit (ssu) is rapidly degrad ...200616731581
microbial diversity in maras salterns, a hypersaline environment in the peruvian andes.maras salterns are located 3,380 m above sea level in the peruvian andes. these salterns consist of more than 3,000 little ponds which are not interconnected and act as crystallizers where salt precipitates. these ponds are fed by hypersaline spring water rich in sodium and chloride. the microbiota inhabiting these salterns was examined by fluorescence in situ hybridization (fish), 16s rrna gene clone library analysis, and cultivation techniques. the total counts per milliliter in the ponds were ...200616751493
the role of the dna-binding domains in cooa activation.carbon monoxide oxidation activator protein (cooa) is a dimeric carbon monoxide (co) binding transcription factor that in the presence of co promotes the transcription of genes involved in co oxidation in rhodospirillum rubrum. the off state (inactive) of fe(ii) cooa has his and pro as the two axial heme ligands. in contrast, in the on state, which is active in dna binding, the pro ligand bond has been replaced by co. this occurs by the transient loss of the pro ligand, thus generating a pentaco ...200616752905
overexpression and characterization of the rhodobacter sphaeroides pufx membrane protein in escherichia coli.heterologous expression of the pufx membrane protein from purple photosynthetic bacterium rhodobacter sphaeroides was attempted by using escherichia (e.) coli cells. the pufx was overexpressed as a recombinant protein with a histidine tag added to the carboxyl terminus, and can be extracted from the cell membrane by various detergents. circular dichroism measurements showed that the expressed pufx protein had alpha-helix contents of 29% in organic solvents and 22-26% in 0.8-2.0% (w/v) n-octyl be ...200716752956
the poor growth of rhodospirillum rubrum mutants lacking pii proteins is due to an excess of glutamine synthetase activity.the p(ii) family of proteins is found in all three domains of life and serves as a central regulator of the function of proteins involved in nitrogen metabolism, reflecting the nitrogen and carbon balance in the cell. the genetic elimination of the genes encoding these proteins typically leads to severe growth problems, but the basis of this effect has been unknown except with escherichia coli. we have analysed a number of the suppressor mutations that correct such growth problems in rhodospiril ...200616762025
two pathways of electron transport to nitrogenase in rhodospirillum rubrum: the major pathway is dependent on the fix gene the photosynthetic bacterium rhodospirillum rubrum, as in many other diazotrophs, electron transport to nitrogenase has not been characterized in great detail. in this study, we show that there are two pathways operating in r. rubrum. the products of the fix genes constitute the major pathway operating under heterotrophic conditions, whereas a pyruvate:ferredoxin oxidoreductase, encoded by the nifj gene, may play a central role under anaerobic conditions in the dark. in both systems, ferredox ...200616790015
effect of amtb homologues on the post-translational regulation of nitrogenase activity in response to ammonium and energy signals in rhodospirillum rubrum.the amtb protein transports uncharged nh(3) into the cell, but it also interacts with the nitrogen regulatory protein p(ii), which in turn regulates a variety of proteins involved in nitrogen fixation and utilization. three p(ii) homologues, glnb, glnk and glnj, have been identified in the photosynthetic bacterium rhodospirillum rubrum, and they have roles in at least four overlapping and distinct functions, one of which is the post-translational regulation of nitrogenase activity. in r. rubrum, ...200616804182
catalytic by-product formation and ligand binding by ribulose bisphosphate carboxylases from different phylogenies.during catalysis, all rubisco (d-ribulose-1,5-bisphosphate carboxylase/oxygenase) enzymes produce traces of several by-products. some of these by-products are released slowly from the active site of rubisco from higher plants, thus progressively inhibiting turnover. prompted by observations that form i rubisco enzymes from cyanobacteria and red algae, and the form ii rubisco enzyme from bacteria, do not show inhibition over time, the production and binding of catalytic by-products was measured t ...200616822231
mechanically driven proton conduction in single delta-free order to observe mechanically driven proton flux in f(0)f(1)-atpase coupled with artificial driven rotation on f(1) simultaneously, a double channel observation system was established. an artificial delta-free f(0)f(1)-atpase was constructed with alpha(3), beta(3), epsilon, gamma, and c(n) subunits as rotator and a, b(2) as stator. the chromatophore was immobilized on the glass surface through biotin-streptavidin-biotin system, and the magnetic bead was attached to the beta subunit of delta-f ...200616844089
theoretical prediction of spectral and optical properties of bacteriochlorophylls in thermally disordered lh2 antenna complexes.a general approach for calculating spectral and optical properties of pigment-protein complexes of known atomic structure is presented. the method, that combines molecular dynamics simulations, quantum chemistry calculations, and statistical mechanical modeling, is demonstrated by calculating the absorption and circular dichroism spectra of the b800-b850 bacteriochlorophylls of the lh2 antenna complex from rs. molischianum at room temperature. the calculated spectra are found to be in good agree ...200616863329
effect of mutation on the dissociation and recombination dynamics of co in transcriptional regulator cooa: a picosecond infrared transient absorption study.the co ligation process in a mutant (h77g) of cooa, the co-sensing transcriptional regulator in rhodospirillum rubrum, is studied with femtosecond time-resolved transient absorption spectroscopy in the mid-infrared region. following photolyzing excitation, a transient bleach in the vibrational region of bound co due to the co photodissociation is detected. in contrast to the spectra of the wild-type (wt) cooa, the transient bleach spectra of h77g cooa show a bimodal shape with peaks shifting to ...200616866371
heme displacement mechanism of cooa activation: mutational and raman spectroscopic evidence.the heme-containing protein cooa of rhodospirillum rubrum regulates the expression of genes involved in co oxidation. cooa binds its target dna sequence in response to co binding to its heme. activity measurements and resonance raman (rr) spectra are reported for cooa variants that bind dna even in the absence of co, those in which the wild-type residues at the 121-126 positions, tscmrt, are replaced by the residues ayllrl or ryllrl, and also for variants that bind dna poorly in the presence of ...200616873369
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