| monitoring and interpretation of photoinduced biochemical processes by rapid-scan ftir difference spectroscopy and hybrid hard and soft modeling. | natural photochemical processes often require special instrumentation to monitor them at a suitable time scale. rapid-scan ftir difference spectroscopy is one of the preferred techniques to obtain rich structural information in the scale of milliseconds about photochemical processes of complex natural systems. the difference spectra obtained by this technique enhance the fine spectroscopic changes undergone during the process but require powerful data analysis methodologies to take full advantag ... | 2009 | 19385692 |
| early succession of bacterial biofilms in paper machines. | formation of biofilms causes severe problems in paper machines, and hence financial costs. it would be preferable to prevent attachment of the primary-colonizing bacteria than to control the growth of secondary communities, which are sheltered by exopolysaccharide slime layers. we have therefore investigated the early succession of paper-machine biofilms by incubating stainless-steel test coupons in the process water-flow lines in two paper machines operating in slightly alkaline conditions in t ... | 2009 | 19390885 |
| in vivo sensitivity of blue-light-dependent signaling mediated by appa/ppsr or prrb/prra in rhodobacter sphaeroides. | formation of photosynthesis complexes in rhodobacter sphaeroides is regulated in a redox- and light-dependent manner by the appa/ppsr and prrb/prra systems. while on the one hand, blue light is sensed by the flavin adenine dinucleotide-binding bluf domain of appa, on the other, light is absorbed by bacteriochlorophyll signals through prrb/prra. we show that much smaller quantities initiate the appa-mediated response to blue light than the bacteriochlorophyll-mediated response. | 2009 | 19395480 |
| the relationship between delayed fluorescence and the carotenoid shift in chromatophores from rhodopseudomonas capsulata. | (1) the kinetics of the change in intensity of 1-ms delayed fluorescence following the onset of illumination have been studied in chromatophores of rhodopseudomonas capsulata and compared with the kinetics of the light-induced carotenoid shift, and of the change in fluorescence yield. the change in intensity of delayed fluorescence, when plotted on a logarithmic scale, followed closely the kinetics of carotenoid change, but not the change in fluorescence yield. (2) the antibiotics valinomycin, n ... | 1974 | 19396992 |
| redox-dependent conformational changes in cytochrome c oxidase suggest a gating mechanism for proton uptake. | a role for conformational change in the coupling mechanism of cytochrome c oxidase is the subject of controversy. relatively small conformational changes have been reported in comparisons of reduced and oxidized crystal structures of bovine oxidase but none in bacterial oxidases. comparing the x-ray crystal structures of the reduced (at 2.15 a resolution) and oxidized forms of cytochrome c oxidase from rhodobacter sphaeroides, we observe a displacement of heme a(3) involving both the porphyrin r ... | 2009 | 19397279 |
| the absolute quantum efficiency of bacteriochlorophyll photooxidation in reaction centres of rhodopseudomonas spheroides. | the widely assumed correspondence between fluorescence and photochemistry in photosynthetic systems has recently been challenged by observations on the triplet state of bacteriochlorophyll in reaction centres of rhodopseudomonas spheroides. in order to check this assumption we have conducted a precise determination of the quantum efficiency of bacteriochlorophyll photooxidation in reaction centres at room temperature. we find a quantum efficiency of 1.02 +/- 0.04 in contrast to a value of about ... | 1974 | 19400037 |
| characterization of primary reactants in bacterial photosynthesis. ii. kinetic studies of the light-induced epr signal (g = 2.0026) and the optical absorbance changes at cryogenic temperatures. | we have shown that the rise and decay kinetics of the light-induced epr signal are identical to the kinetics of the optical changes at 80 degrees k. this identity provides independent evidence that the epr signal is due to the oxidized primary electron donor which is bacteriochlorophyll. the epr and optical changes could be described by a model photochemical reaction scheme that takes into account spin-lattice relaxation. the optical decay rate was found to be temperature independent between 1.5 ... | 1974 | 19400038 |
| site directed mutagenesis of amino acid residues at the active site of mouse aldehyde oxidase aox1. | mouse aldehyde oxidase (maox1) forms a homodimer and belongs to the xanthine oxidase family of molybdoenzymes which are characterized by an essential equatorial sulfur ligand coordinated to the molybdenum atom. in general, mammalian aos are characterized by broad substrate specificity and an yet obscure physiological function. to define the physiological substrates and the enzymatic characteristics of maox1, we established a system for the heterologous expression of the enzyme in escherichia col ... | 2009 | 19401776 |
| expression of four pha genes involved in poly-beta-hydroxybutyrate production and accumulation in rhodobacter sphaeroides fj1. | a cluster of genes encoding polyhydroxybutyrate (phb) depolymerase (phaz), phb synthase (phac), phasin (phap), and the regulator protein (phar) was previously identified in rhodobacter sphaeroides fj1 (r. sphaeroides fj1). in this study, we investigated the role of the phar protein on the expression of the pha genes. immunoblot analysis revealed that the expressions of phap, phaz and phar genes in wild-type cells of r. sphaeroides fj1 are repressed during the active growth phase, with the except ... | 2009 | 19404680 |
| rhodobacter aestuarii sp. nov., a phototrophic alphaproteobacterium isolated from an estuarine environment. | an ovoid to rod-shaped, phototrophic, purple non-sulfur bacterium was isolated from a brown-coloured microbial mat from the brackish water of bhitarkanika mangrove forest, dangmal, orissa, india. cells of strain ja296(t) were gram-negative and motile, forming chains of four to eight cells. the colour of the cell suspension grown under anaerobic conditions in the light was yellowish green. bacteriochlorophyll a and the carotenoids spheroidene and spheroidenone of the spirilloxanthin series were p ... | 2009 | 19406806 |
| half-site dna sequence and spacing length contributions to prra binding to prra site 2 of rsp3361 in rhodobacter sphaeroides 2.4.1. | the consensus dna binding sequence for prra, a global regulator in rhodobacter sphaeroides 2.4.1, is poorly defined. we have performed mutational analysis of prra site 2, of the rsp3361 gene, to which prra binds in vitro (j. m. eraso and s. kaplan, j. bacteriol. 191:4341-4352, 2009), to further define the consensus sequence for dna binding. two half-sites of equal length, containing 6 nucleotides each, were required for prra binding to this dna sequence. systematic nucleotide substitutions in bo ... | 2009 | 19411326 |
| regulation of gene expression by prra in rhodobacter sphaeroides 2.4.1: role of polyamines and dna topology. | in the present study, we show in vitro binding of prra, a global regulator in rhodobacter sphaeroides 2.4.1, to the prra site 2, within the rsp3361 locus. specific binding, as shown by competition experiments, requires the phosphorylation of prra. the binding affinity of prra for site 2 was found to increase 4- to 10-fold when spermidine was added to the binding reaction. the presence of extracellular concentrations of spermidine in growing cultures of r. sphaeroides gave rise to a twofold incre ... | 2009 | 19411327 |
| magnetic interactions sense changes in distance between heme b(l) and the iron-sulfur cluster in cytochrome bc(1). | during the operation of cytochrome bc(1), a key enzyme of biological energy conversion, the iron-sulfur head domain of one of the subunits of the catalytic core undergoes a large-scale movement from the catalytic quinone oxidation q(o) site to cytochrome c(1). this changes a distance between the two iron-two sulfur (fes) cluster and other cofactors of the redox chains. although the role and the mechanism of this movement have been intensely studied, they both remain poorly understood, partly bec ... | 2009 | 19415898 |
| phylogenetic classification of heterotrophic bacteria associated with filamentous marine cyanobacteria in culture. | fifty-one heterotrophic bacterial strains were isolated from the marine cyanobacterial cultures of heterocystous nodularia harveyana strain bo53 and non-heterocystous oscillatoria brevis strain bo10. fluorescence in situ hybridisation and fingerprinting methods were used for a preliminary taxonomical classification of 44 of the 51 isolates. the strains obtained from bo53 were mostly alphaproteobacteria (10/24), followed by bacteroidetes (7/24), and gammaproteobacteria (3/24). the affiliation of ... | 2009 | 19423262 |
| an improved escherichia coli donor strain for diparental mating. | we present a new method for diparental mating with the outstanding advantage that counterselection of the escherichia coli donor strain is not required. this improved method uses a new donor strain, e. coli st18, a hema deletion mutant defective in tetrapyrrole biosynthesis. the hema mutation can be complemented by addition of 5-aminolevulinic acid. therefore, counterselection is carried out only using standard media and growth conditions optimal for the recipient strain. consequently, recipient ... | 2009 | 19431232 |
| effect of integral membrane proteins on the lateral mobility of plastoquinone in phosphatidylcholine proteoliposomes. | pyrene fluorescence quenching by plastoquinone was used to estimate the rate of plastoquinone lateral diffusion in soybean phosphatidylcholine proteoliposomes containing the following integral membrane proteins: gramicidin d, spinach cytochrome bf complex, spinach cytochrome f, reaction centers from rhodobacter sphaeroides, beef heart mitochondrial cytochrome bc(1), and beef heart mitochondrial cytochrome oxidase. the measured plastoquinone lateral diffusion coefficient varied between 1 and 3 . ... | 1990 | 19431774 |
| polarized fluorescence measurements on ordered photosynthetic antenna complexes: chlorosomes of chloroflexus aurantiacus and b800-b850 antenna complexes of rhodobacter sphaeroides. | we have used a new and relatively easy approach to study the pigment-organization in chlorosomes from the photosynthetic bacterium chloroflexus aurantiacus and in b800-850 antenna complexes of the photosynthetic purple bacterium rhodobacter sphaeroides. these particles were embedded in compressed and uncompressed gels and the polarized fluorescence was determined in a 90 degrees setup. assuming both a rotational symmetric distribution of the particles in the gel and of the transition dipole mome ... | 1991 | 19431792 |
| pathways of energy flow through the light-harvesting antenna of the photosynthetic purple bacterium rhodobacter sphaeroides. | using low intensity picosecond absorption spectroscopy with independently tunable excitation and probing infrared pulses, we have studied the pathways of energy transport through the light-harvesting antenna pigments of the photosynthetic purple bacterium rhodobacter sphaeroides. from the observed excited-state rise time of the red-most pigment b896 as a function of excitation wavelength it is concluded that the b850 pigment of lh2 is spectrally heterogeneous. for excitations originating in the ... | 1992 | 19431825 |
| on the long-wavelength component of the light-harvesting complex of some photosynthetic bacteria. | the effect of the presence of a minor antenna component in light-harvesting complexes of photosynthetic bacteria is investigated with numerical simulation employing the transition probability matrix method. a model antenna system of hexagonal symmetry is adopted, using as a working hypothesis that the minor component forms a ring around the trap. three cases have been considered: (a) the minor component is isoenergetic with the trap, which is at lower energy than the antennas (the "supertrap"), ... | 1992 | 19431850 |
| electron transfer in the rhodobacter sphaeroides reaction center assembled with zinc bacteriochlorophyll. | the cofactor composition and electron-transfer kinetics of the reaction center (rc) from a magnesium chelatase (bchd) mutant of rhodobacter sphaeroides were characterized. in this rc, the special pair (p) and accessory (b) bacteriochlorophyll (bchl) -binding sites contain zn-bchl rather than bchl a. spectroscopic measurements reveal that zn-bchl also occupies the h sites that are normally occupied by bacteriopheophytin in wild type, and at least 1 of these zn-bchl molecules is involved in electr ... | 2009 | 19439660 |
| the electronic behavior of a photosynthetic reaction center monitored by conductive atomic force microscopy. | the conductivity of a photosynthetic reaction center (rc) from rhodobacter sphaeroides was measured with conductive atomic force microscopy (cafm) on sam-modified au(111) substrates. 2-mercaptoethanol (2me), 2-mercaptoacetic acid (mac), 2-mercaptopyridine (2mp) and 4-mercaptopyridine (4mp) were prepared as sam materials to investigate the stability and morphology of rcs on the substrate by using near-ir absorption spectroscopy and afm, respectively. the clear presence of the three well known rc ... | 2009 | 19441283 |
| modelling mitochondrial dna mutations in bacterial cytochrome c oxidase: link to colon cancer? | | 2009 | 19447926 |
| plasmon-waveguide resonance studies of ligand binding to integral proteins in membrane fragments derived from bacterial and mammalian cells. | a procedure has been developed for directly depositing membrane fragments derived from bacterial cells (chromatophores from rhodopseudomonas sphaeroides) and mammalian cells (mu-opioid receptor- and mc4 receptor-transfected human embryonic kidney (hek) cells and rat trigeminal ganglion cells) on the silica surface of a plasmon-waveguide resonance (pwr) spectrometer. binding of ligands (cytochrome c(2) for the chromatophores, the peptide agonists damgo and melanotan-ii that are specific for the m ... | 2009 | 19454250 |
| properties of mutant reaction centers of rhodobacter sphaeroides with substitutions of histidine l153, the axial mg2+ ligand of bacteriochlorophyll b(a). | mutant reaction centers (rc) from rhodobacter sphaeroides have been studied in which histidine l153, the axial ligand of the central mg atom of bacteriochlorophyll b(a) molecule, was substituted by cysteine, methionine, tyrosine, or leucine. none of the mutations resulted in conversion of the bacteriochlorophyll b(a) to a bacteriopheophytin molecule. isolated h(l153)c and h(l153)m rcs demonstrated spectral properties similar to those of the wild-type rc, indicating the ability of cysteine and me ... | 2009 | 19463100 |
| critical structural role of r481 in cytochrome c oxidase from rhodobacter sphaeroides. | the r481 residue in cytochrome c oxidase from rhodobacter sphaeroides forms hydrogen bonds with the propionate groups of both heme a and heme a(3). it has been postulated that r481 is the proton loading site in the proton exit pathway essential for proton translocation. a recent functional study showed that the mutations of r481 to his, leu and gln cause the reduction of the activity to approximately 5-18% of the native level, and the absence of proton pumping in r481q but retention of approxima ... | 2009 | 19463779 |
| direct measurement of photoinduced charge separation distances in donor-acceptor systems for artificial photosynthesis using oop-eseem. | the distance over which two photogenerated charges are separated in electron donor-acceptor systems for artificial photosynthesis depends on the structure of the system, while the lifetime of the charge separation and, ultimately, its ability to carry out useful redox chemistry depend on the electronic coupling between the oxidized donor and reduced acceptor. the radical ions produced by charge separation are frequently delocalized over the pi systems of the final oxidized donor and reduced acce ... | 2009 | 19476357 |
| genetic determinants of silicibacter sp. tm1040 motility. | silicibacter sp. tm1040 is a member of the marine roseobacter clade of alphaproteobacteria that forms symbioses with unicellular eukaryotic phytoplankton, such as dinoflagellates. the symbiosis is complex and involves a series of steps that physiologically change highly motile bacteria into cells that readily form biofilms on the surface of the host. the initial phases of symbiosis require bacterial motility and chemotaxis that drive the swimming bacteria toward their planktonic host. cells lack ... | 2009 | 19482930 |
| kinetic model of hydrogen generation by rhodobacter sphaeroides in the presence of nh ions. | to examine the effects of ammonium ion concentration and illumination intensity on the effectivness of the hydrogen generation process of rhodobacter sphaeroides. | 2009 | 19486388 |
| proton-transfer reactions in reaction center of photosynthetic bacteria rhodobacter sphaeroides. | the mechanism of proton uptakes by the secondary ubiquinone (q(b)) in the reaction center of the photosynthetic bacteria rhodobacter sphaeroides is investigated theoretically. two protons are transferred to the secondary ubiquinone (q(b)) upon two electron transfers to it. the pathways of the proton transfers are explored through molecular dynamics and free-energy calculations by a molecular mechanical method and potential energy surface calculations by a hybrid ab initio quantum mechanical/mole ... | 2009 | 19496556 |
| specific interactions between four molybdenum-binding proteins contribute to mo-dependent gene regulation in rhodobacter capsulatus. | the phototrophic purple bacterium rhodobacter capsulatus encodes two transcriptional regulators, mopa and mopb, with partially overlapping and specific functions in molybdate-dependent gene regulation. both mopa and mopb consist of an n-terminal dna-binding helix-turn-helix domain and a c-terminal molybdate-binding di-mop domain. they formed homodimers as apo-proteins and in the molybdate-bound state as shown by yeast two-hybrid (y2h) studies, glutaraldehyde cross-linking, gel filtration chromat ... | 2009 | 19502397 |
| characterization of an unusual lov domain protein in the alpha-proteobacterium rhodobacter sphaeroides. | the facultatively phototrophic purple bacterium rhodobacter sphaeroides 2.4.1 harbors a lov (light, oxygen and voltage) domain protein, which shows a particular structure. lov domains perceive blue light by a noncovalently bound flavin and transmit the signal to various coupled output domains. proteins, that harbor a lov core, function e.g. as phototropins or circadian clock regulators. jalpha helices, which act as linker between the lov core and the output domain, were shown to be involved in t ... | 2009 | 19508644 |
| identification of the intermediate charge-separated state p+betal- in a leucine m214 to histidine mutant of the rhodobacter sphaeroides reaction center using femtosecond midinfrared spectroscopy. | energy and electron transfer in a leu m214 to his (lm214h) mutant of the rhodobacter sphaeroides reaction center (rc) were investigated by applying time-resolved visible pump/midinfrared probe spectroscopy at room temperature. this mutant replacement of the leu at position m214 resulted in the incorporation of a bacteriochlorophyll (bchl) in place of the native bacteriopheophytin in the l-branch of cofactors (denoted betal). purified lm214h rcs were excited at 600 nm (unselective excitation), at ... | 2009 | 19527655 |
| [degradation of dichlorvos by rhodobacter sphaeroides]. | rhodobacter sphaeroides possesses an extensive range of energy acquiring mechanisms including photosynthesis, lithotrophy, aerobic and anaerobic respiration. it can produce 5-aminolevulinic acid, coq10, carotenoids, hydrogen, etc. by fermentation. a rhodobacter sphaeroides strain was isolated, designated as ebl0706, from soil. the degradation of dichlorvos (ddvp) by the rhodobacter sphaeroides was investigated. 98% of ddvp could be degraded in water solution in 12 h when 5 x 10(8) cfu/ml rhodoba ... | 2009 | 19545029 |
| differential charge polarization of axial histidines in bacterial reaction centers balances the asymmetry of the special pair. | in photosynthesis, light energy is transformed into chemical energy that sustains most forms of life on earth. solid-state nmr spectroscopy in conjunction with density functional theory modeling can resolve electronic structure down to the atomic level in large membrane proteins. in this work, we have used this technique to address the mechanisms underlying the photochemical reactivity of the special pair in the bacterial reaction center. for charge separation, the electrostatics is important, a ... | 2009 | 19548676 |
| export or recombination of charges in reaction centers in intact cells of photosynthetic bacteria. | the kinetics and thermodynamics of forward and reverse electron transfer around the reaction center of purple bacterium rhodobacter sphaeroides were studied in vivo by flash-excited delayed fluorescence, prompt fluorescence (induction) and kinetic difference absorption. by protection of the photomultiplier from intense bacteriochlorophyll prompt fluorescence evoked by laser excitation, the time resolution of the fluorometer was reduced typically 10 micros. two precursor states of the delayed flu ... | 2009 | 19555655 |
| expression and regulation of ribulose 1,5-bisphosphate carboxylase/oxygenase genes in mycobacterium sp. strain jc1 dsm 3803. | ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) is the key enzyme of the calvin reductive pentose phosphate cycle. two sets of structural genes (cbbls-1 and -2) for form i rubisco have been previously identified in the mycobacterium sp. strain jc1, which is able to grow on carbon monoxide (co) or methanol as sole sources of carbon and energy. northern blot and reverse transcriptase pcr showed that the cbbls-1 and -2 genes are expressed in cells grown on either carbon monoxide (co) or m ... | 2009 | 19557347 |
| arg-85 and thr-430 in murine 5-aminolevulinate synthase coordinate acyl-coa-binding and contribute to substrate specificity. | 5-aminolevulinate synthase (alas) controls the rate-limiting step of heme biosynthesis in mammals by catalyzing the condensation of succinyl-coenzyme a and glycine to produce 5-aminolevulinate, coenzyme-a (coa), and carbon dioxide. alas is a member of the alpha-oxoamine synthase family of pyridoxal 5'-phosphate (plp)-dependent enzymes and shares high degree of structural similarity and reaction mechanism with the other members of the family. the x-ray crystal structure of alas from rhodobacter c ... | 2009 | 19562746 |
| identification of heme propionate vibrational modes in the resonance raman spectra of cytochrome c oxidase. | the propionate groups of heme a and a(3) in cytochrome c oxidase (cco) have been postulated to mediate both the electron and proton transfer within the enzyme. to establish structural markers for the propionate groups, their associated vibrational modes were identified in the resonance raman spectra of cco from bovine (bcco) and rhodobacter sphaeroides (rscco). the distinction between the modes from the propionates of heme a and heme a(3), as well as those from the propionates on the pyrrole rin ... | 2009 | 19563766 |
| bacterial ortholog of mammalian translocator protein (tspo) with virulence regulating activity. | the translocator protein (tspo), previously designated as peripheral-type benzodiazepine receptor, is a protein mainly located in the outer mitochondrial membrane of eukaryotic cells. tspo is implicated in major physiological functions and functionally associated with other proteins such as the voltage-dependent anionic channel, also designated as mitochondrial porin. surprisingly, a tspo-related protein was identified in the photosynthetic bacterium rhodobacter sphaeroides but it was initially ... | 2009 | 19564920 |
| mutational analysis of three bchh paralogs in (bacterio-)chlorophyll biosynthesis in chlorobaculum tepidum. | the first committed step in the biosynthesis of (bacterio-)chlorophyll is the insertion of mg2+ into protoporphyrin ix by mg-chelatase. in all known (b)chl-synthesizing organisms, mg-chelatase is encoded by three genes that are homologous to bchh, bchd, and bchi of rhodobacter spp. the genomes of all sequenced strains of green sulfur bacteria (chlorobi) encode multiple bchh paralogs, and in the genome of chlorobaculum tepidum, there are three bchh paralogs, denoted ct1295 (bcht), ct1955 (bchs), ... | 2009 | 19568953 |
| [the analysis of kinetics of recombination of photodivided charges in the rhodobacter sphaeroides photosynthetic reaction centers using relaxation time constant distribution method]. | the kinetics of dark recombination of charges photodivided between the bacteriochlorophyll dimer (p) and the quinone acceptors of the photosynthetic reaction centers (rcs) of rhodobacter sphaeroides has been studied. the electron transfer between p and the quinone acceptors of times of light activation from 1 to 60 s was investigated. the relaxation time constant distribution was computed from experimental kinetic curves of charge recombination using an original method developed by the authors. ... | 2009 | 19569501 |
| a molecular brake, not a clutch, stops the rhodobacter sphaeroides flagellar motor. | many bacterial species swim by employing ion-driven molecular motors that power the rotation of helical filaments. signals are transmitted to the motor from the external environment via the chemotaxis pathway. in bidirectional motors, the binding of phosphorylated chey (chey-p) to the motor is presumed to instigate conformational changes that result in a different rotor-stator interface, resulting in rotation in the alternative direction. controlling when this switch occurs enables bacteria to a ... | 2009 | 19571004 |
| revealing linear aggregates of light harvesting antenna proteins in photosynthetic membranes. | how light energy is harvested in a natural photosynthetic membrane through energy transfer is closely related to the stoichiometry and arrangement of light harvesting antenna proteins in the membrane. the specific photosynthetic architecture facilitates a rapid and efficient energy transfer among the light harvesting proteins (lh2 and lh1) and to the reaction center. here we report the identification of linear aggregates of light harvesting proteins, lh2, in the photosynthetic membranes under am ... | 2010 | 19572507 |
| understanding the spectroscopic properties of the photosynthetic reaction center of rhodobacter sphaeroides by a combined theoretical study of absorption and circular dichroism spectra. | in the present study, we calculate eight low-lying (1.3-1.7 ev energy region) electronic excited states in well accordance with the absorption and cd spectroscopic properties of psrc from rb. shpaeroides by using time-dependent density functional theory (tddft). our present calculations demonstrate that, only when the interactions among the prosthetic groups have been taken into account, a set of satisfactory assignments for both absorption and cd spectra of psrc from rb. sphaeroides can be achi ... | 2009 | 19572670 |
| properties of arg481 mutants of the aa3-type cytochrome c oxidase from rhodobacter sphaeroides suggest that neither r481 nor the nearby d-propionate of heme a3 is likely to be the proton loading site of the proton pump. | cytochrome c oxidase utilizes the energy from electron transfer and reduction of oxygen to water and pumps protons across the membrane, generating a proton motive force. a large body of biochemical work has shown that all the pumped protons enter the enzyme through the d-channel, which is apparent in x-ray structures as a chain of water molecules connecting d132 at the cytoplasmic surface of the enzyme to e286, near the enzyme active site. the exit pathway utilized by pumped protons beyond this ... | 2009 | 19575527 |
| equilibration kinetics in isolated and membrane-bound photosynthetic reaction centers upon illumination: a method to determine the photoexcitation rate. | kinetics of electron transfer, following variation of actinic light intensity, for photosynthetic reaction centers (rcs) of purple bacteria (isolated and membrane-bound) were analyzed by measuring absorbance changes in the primary photoelectron donor absorption band at 865 nm. the bleaching of the primary photoelectron donor absorption band in rcs, following a sudden increase of illumination from the dark to an actinic light intensity of i(exp), obeys a simple exponential law with the rate const ... | 2009 | 19578969 |
| protein-induced membrane curvature investigated through molecular dynamics flexible fitting. | in the photosynthetic purple bacterium rhodobacter (rba.) sphaeroides, light is absorbed by membrane-bound light-harvesting (lh) proteins lh1 and lh2. lh1 directly surrounds the reaction center (rc) and, together with pufx, forms a dimeric (rc-lh1-pufx)2 protein complex. in lh2-deficient rba. sphaeroides mutants, rc-lh1-pufx dimers aggregate into tubular vesicles with a radius of approximately 250-550 a, making rc-lh1-pufx one of the few integral membrane proteins known to actively induce membra ... | 2009 | 19580770 |
| charge recombination kinetics and protein dynamics in wild type and carotenoid-less bacterial reaction centers: studies in trehalose glasses. | the coupling between electron transfer and protein dynamics has been investigated in reaction centers (rcs) from the wild type (wt) and the carotenoid-less strain r26 of the photosynthetic bacterium rhodobacter sphaeroides. recombination kinetics between the primary photoreduced quinone acceptor (qa-) and photoxidized donor (p+) have been analyzed at room temperature in rcs incorporated into glassy trehalose matrices of different water/sugar ratios. as previously found in r26 rcs, also in the wt ... | 2009 | 19585969 |
| extracellular iron biomineralization by photoautotrophic iron-oxidizing bacteria. | iron oxidation at neutral ph by the phototrophic anaerobic iron-oxidizing bacterium rhodobacter sp. strain sw2 leads to the formation of iron-rich minerals. these minerals consist mainly of nano-goethite (alpha-feooh), which precipitates exclusively outside cells, mostly on polymer fibers emerging from the cells. scanning transmission x-ray microscopy analyses performed at the c k-edge suggest that these fibers are composed of a mixture of lipids and polysaccharides or of lipopolysaccharides. th ... | 2009 | 19592528 |
| diversity and evolution of repabc type plasmids in rhodobacterales. | the repabc operon is the prevalent replication unit of alphaproteobacterial plasmids. their semi-autonomy is ensured by the essential replicase gene repc as well as the repab partitioning cassette. while conserved repab modules are widespread among bacterial plasmids and homologues are even responsible for chromosome partitioning, repc genes are exclusively present in alphaproteobacteria. repabc operons contain two strong incompatibility regions, namely a small regulative antisense rna gene (inc ... | 2009 | 19601964 |
| internal electrostatic control of the primary charge separation and recombination in reaction centers from rhodobacter sphaeroides revealed by femtosecond transient absorption. | we report the observation of two conformational states of closed rcs from rhodobacter sphaeroides characterized by different p(+)h(a)(-) --> ph(a) charge recombination lifetimes, one of which is of subnanosecond value (700 +/- 200 ps). these states are also characterized by different primary charge separation lifetimes. it is proposed that the distinct conformations are related to two protonation states either of reduced secondary electron acceptor, q(a)(-), or of a titratable amino acid residue ... | 2009 | 19603803 |
| [regulation mechanism of photopigments biosynthesis via light and oxygen in rhodobacter azotoformans 134k20]. | to provided a reliable and sensitive method and a series of specific absorption spectra data of different carotenoids and bacteriochlorophylla in anxoygenic phototrophic bacteria, and reveal mechanism of regulation of photosynthetic pigments by light and oxygen in rhodobacter azotoformans 134k20. | 2009 | 19623956 |
| exploration of the hydrogen producing potential of rhodobacter capsulatus chemostat cultures: the application of deceleration-stat and gradient-stat methodology. | in this work, the dependency of the volumetric hydrogen production rate of ammonium-limited rhodobacter capsulatus chemostat cultures on their imposed biomass concentration and dilution rate was investigated. a deceleration-stat experiment was performed by lowering the dilution rate from 1.0 d(-1) to zero aimed at a constant biomass concentration of 4.0 g l(-1) at constant incident light intensity. the results displayed a maximal volumetric hydrogen production rate of 0.6 mmol m(-3) s(-1), well ... | 2009 | 19626702 |
| m234glu is a component of the proton sponge in the reaction center from photosynthetic bacteria. | bacterial reaction centers use light energy to couple the uptake of protons to the successive semi-reduction of two quinones, namely q(a) and q(b). these molecules are situated symmetrically in regard to a non-heme iron atom. four histidines and one glutamic acid, m234glu, constitute the five ligands of this atom. by flash-induced absorption spectroscopy and delayed fluorescence we have studied in the m234eh and m234el variants the role played by this acidic residue on the energetic balance betw ... | 2009 | 19632193 |
| nmr assignment of the rhodobacter sphaeroides fasciclin-1 domain protein (fdp). | we report the almost complete assignment of 1h, 13c and 15n nuclei in the 137-residue his-tagged fasciclin domain protein (fdp) from rhodobacter sphaeroides. fdp is homologous to fasciclin i domains, including drosophila fas1 and m. tuberculosis mpb70 and plays a role in cell adhesion. | 2007 | 19636813 |
| two-photon excitation spectroscopy of carotenoid-containing and carotenoid-depleted lh2 complexes from purple bacteria. | we applied two-photon fluorescence excitation spectroscopy to lh2 complex from purple bacteria allochromatium minutissimum and rhodobacter sphaeroides . bacteriochlorophyll fluorescence was measured under two-photon excitation of the samples within the 1200-1500 nm region. spectra were obtained for both carotenoid-containing and -depleted complexes of each bacterium to allow their direct comparison. the depletion of carotenoids did not alter the two-photon excitation spectra of either bacteria. ... | 2009 | 19650635 |
| a membrane-reconstituted multisubunit functional proton pump on mesoporous silica particles. | we have investigated formation of a proteolipid membrane surrounding mesoporous silica particles with a diameter of 550 nm and pore sizes of 3.0 nm. a multisubunit redox-driven proton pump, cytochrome c oxidase, was incorporated into the membrane, and we show that the enzyme is functional, both with respect to catalysis of o(2) reduction to water, and charge separation across the membrane. the orientation of cytochrome c oxidase in the membrane was found to be the same ( approximately 70%) in th ... | 2009 | 19653679 |
| copper acquisition by the senc protein regulates aerobic respiration in pseudomonas aeruginosa pao1. | aerobic respiration of pseudomonas aeruginosa involves four terminal oxidases belonging to the heme-copper family (that is, three cytochrome c oxidases and one quinol oxidase) plus one copper-independent, cyanide-insensitive quinol oxidase (cio). the pa0114 gene encoding an sco1/senc-type protein, which is known to be important for copper delivery to cytochrome c in yeast, rhodobacter spp. and agrobacterium tumefaciens, was found to be important for copper acquisition and aerobic respiration in ... | 2009 | 19659575 |
| inducible-expression plasmid for rhodobacter sphaeroides and paracoccus denitrificans. | we have developed a stable isopropyl-beta-d-thiogalactopyranoside (iptg)-inducible-expression plasmid, pind4, which allows graduated levels of protein expression in the alphaproteobacteria rhodobacter sphaeroides and paracoccus denitrificans. pind4 confers kanamycin resistance and combines the stable replicon of pmg160 with the laci(q) gene from pyanni3 and the lac promoter, p(a1/04/03), from pjba24. | 2009 | 19684165 |
| the role of arginine-127 at the proximal no-binding site in determining the electronic structure and function of 5-coordinate no-heme in cytochrome c' of rhodobacter sphaeroides. | cytochrome c' is a heme protein from a denitrifying variant of rhodobacter sphaeroides which may serve to store and transport metabolic no while protecting against no toxicity. its heme site bears resemblance through its 5-coordinate no-binding capability to the regulatory site in soluble guanylate cyclase. a conserved arginine (arg-127) abuts the 5-coordinate no-heme binding site, and the alanine mutant r127a provided insight into the role of the arg-127 in establishing the electronic structure ... | 2009 | 19685879 |
| energetics of bacterial photosynthesis. | we report the results of extensive numerical simulations and theoretical calculations of electronic transitions in the reaction center of rhodobacter sphaeroides photosynthetic bacterium. the energetics and kinetics of five electronic transitions related to the kinetic scheme of primary charge separation have been analyzed and compared to experimental observations. nonergodic formulation of the reaction kinetics is required for the calculation of the rates due to a severe breakdown of the system ... | 2009 | 19691308 |
| (2s)-methylsuccinyl-coa dehydrogenase closes the ethylmalonyl-coa pathway for acetyl-coa assimilation. | many organic substrates are metabolized via acetyl-coenzyme a (coa) and enter central carbon metabolism at the level of this compound. we recently described the outlines of the ethylmalonyl-coa pathway, a new acetyl-coa assimilation strategy that operates in a number of bacteria such as rhodobacter sphaeroides, methylobacterium extorquens and streptomycetes and replaces the glyoxylate cycle. this new pathway involves a unique central reaction sequence catalysed by characteristic enzymes. here, w ... | 2009 | 19703103 |
| a rubisco mutant that confers growth under a normally "inhibitory" oxygen concentration. | ribulose-1,5-bisphosphate (rubp) carboxylase/oxygenase (rubisco) is a globally significant biocatalyst that facilitates the removal and sequestration of co2 from the biosphere. rubisco-catalyzed co2 reduction thus provides virtually all of the organic carbon utilized by living organisms. despite catalyzing the rate-limiting step of photosynthetic and chemoautotrophic co2 assimilation, rubisco is markedly inefficient as the competition between o2 and co2 for the same substrate limits the ability ... | 2009 | 19705820 |
| a novel t7 rna polymerase dependent expression system for high-level protein production in the phototrophic bacterium rhodobacter capsulatus. | the functional expression of heterologous genes using standard bacterial expression hosts such as escherichia coli is often limited, e.g. by incorrect folding, assembly or targeting of recombinant proteins. consequently, alternative bacterial expression systems have to be developed to provide novel strategies for protein synthesis exceeding the repertoire of the standard expression host e. coli. here, we report on the construction of a novel expression system that combines the high processivity ... | 2010 | 19706327 |
| stark realities. | electric fields affect any process or transition that involves the movement of charge. stark spectroscopy is a general term describing the study of spectral changes in the presence of electric fields, and it has proven to be a broadly useful approach for characterizing the change in dipole moment and polarizability for electronic and vibrational transitions. this article focuses primarily on the evolution of the approach and interconnected applications in diverse fields from our laboratory and p ... | 2009 | 19708160 |
| rhodobacter capsulatus catalyzes light-dependent fe(ii) oxidation under anaerobic conditions as a potential detoxification mechanism. | diverse bacteria are known to oxidize millimolar concentrations of ferrous iron [fe(ii)] under anaerobic conditions, both phototrophically and chemotrophically. yet whether they can do this under conditions that are relevant to natural systems is understood less well. in this study, we tested how light, fe(ii) speciation, ph, and salinity affected the rate of fe(ii) oxidation by rhodobacter capsulatus sb1003. although r. capsulatus cannot grow photoautotrophically on fe(ii), it oxidizes fe(ii) a ... | 2009 | 19717624 |
| spin labeling epr. | site-directed spin labeling in combination with electron paramagnetic resonance spectroscopy has emerged as an efficient tool to elucidate the structure and conformational dynamics of biomolecules under native-like conditions. this article summarizes the basics as well as recent progress of site-directed spin labeling. continuous wave epr spectra analyses and pulse epr techniques are reviewed with special emphasis on applications to the sensory rhodopsin-transducer complex mediating the photopho ... | 2009 | 19728138 |
| modification of a french pressure cell to improve microbial cell disruption. | a procedure for modification of the valve stem of a 40 k french pressure cell is described. the modification should be done by a machinist and requires a metalworking lathe. after modification of the valve stem, a torlon 4203 plastic ball is used between the valve stem and valve seat to control the pressure within the cell. the torlon plastic ball is a key component needed to obtain the high pressures required for efficient disruption of microbial cells. | 2009 | 19731071 |
| rapid and sensitive kinetic assay for characterization of omega-transaminases. | for the biocatalytic preparation of optically active amines, omega-transaminases (omega-ta) are of special interest since they allow the asymmetric synthesis starting from prostereogenic ketones with 100% yield. to facilitate the purification and characterization of novel omega-ta, a fast kinetic assay was developed based on the conversion of the widely used model substrate alpha-methylbenzylamine, which is commonly accepted by most of the known omega-tas. the product from this reaction, acetoph ... | 2009 | 19739593 |
| spectroscopic studies of the appa bluf domain from rhodobacter sphaeroides: addressing movement of tryptophan 104 in the signaling state. | previous crystallographic studies of the appa bluf domain indicated that trp104 is capable of undertaking alternate conformations depending on the length of the bluf domain. a bluf domain containing a c-terminal deletion (appa1-126) reveals that trp104 is partially solvent exposed while a bluf domain containing a slightly longer carboxyl terminal region (appa17-133) shows that trp104 is deeply buried. this observation has led to a model proposing that trp104 moves from a deeply buried position i ... | 2009 | 19746968 |
| features of structural organization and expression regulation of malate dehydrogenase isoforms from rhodobacter sphaeroides strain 2r. | two isoforms of malate dehydrogenase (mdh), dimeric and tetrameric, have been found in the purple non-sulfur bacterium rhodobacter sphaeroides strain 2r, devoid of the glyoxylate shunt, which assimilate acetate via the citramalate cycle. inhibitory analysis showed that the 74-kda protein is involved in tricarboxylic acid cycle, while the 148-kda mdh takes part in the citramalate pathway. a single gene encoding synthesis of the isologous subunits of the mdh isoforms was found during molecular-bio ... | 2009 | 19747101 |
| characteristics of light-harvesting complex ii mutant of rhodobacter sphaeroides with alterations at the transmembrane helices of beta-subunit. | the peripheral light-harvesting complex ii (lhii) is an important component of the photosynthetic apparatus of rhodobacter sphaeroides. in this study, genetic, biochemical, and spectroscopic approaches were applied to investigate the spectral properties and functions of lhii in which two amino acid residues phe32 and leu42 in the transmembrane helix domain of pucb-encoded beta-apoprotein were replaced by leu and pro. the mutated lhii complex showed blue shift of absorbance peaks in the near infr ... | 2009 | 19747103 |
| prokaryotic phototaxis. | microorganisms have various mechanisms at their disposal to react to (changes in) their ambient light climate (i.e., intensity, color, direction, and degree of polarization). of these, one of the best studied mechanisms is the process of phototaxis. this process can be described as a behavioral migration-response of an organism toward a change in illumination regime. in this chapter we discuss three of these migration responses, based on swimming, swarming, and twitching motility, respectively. ... | 2009 | 19763957 |
| effects of impurities on membrane-protein crystallization in different systems. | when starting a protein-crystallization project, scientists are faced with several unknowns. amongst them are these questions: (i) is the purity of the starting material sufficient? and (ii) which type of crystallization experiment is the most promising to conduct? the difficulty in purifying active membrane-protein samples for crystallization trials and the high costs associated with producing such samples require an extremely pragmatic approach. additionally, practical guidelines are needed to ... | 2009 | 19770503 |
| modification of galactitol dehydrogenase from rhodobacter sphaeroides d for immobilization on polycrystalline gold surfaces. | galactitol dehydrogenase (gatdh) from rhodobacter sphaeroides is a multifunctional enzyme that catalyzes in the presence of oxidized beta-nicotinamide adenine dinucleotide (nad(+)) the interconversion of various multivalent aliphatic alcohols to the corresponding ketones. the recombinant gatdh was provided with an n-terminal his(6)-tag to which distally up to three cysteine residues were attached. this protein construct maintained nearly full enzymatic activity, and it could be covalently immobi ... | 2009 | 19778027 |
| a novel 11-kda inhibitory subunit in the f1fo atp synthase of paracoccus denitrificans and related alpha-proteobacteria. | the f(1)f(o) and f(1)-atpase complexes of paracoccus denitrificans were isolated for the first time by ion exchange, gel filtration, and density gradient centrifugation into functional native preparations. the liposome-reconstituted holoenzyme preserves its tight coupling between f(1) and f(o) sectors, as evidenced by its high sensitivity to the f(o) inhibitors venturicidin and diciclohexylcarbodiimide. comparison and n-terminal sequencing of the band profile in sds-page of the f(1) and f(1)f(o) ... | 2010 | 19783785 |
| high-field epr spectroscopy applied to biological systems: characterization of molecular switches for electron and ion transfer. | the last decade witnessed a tremendous growth in combined efforts of biologists, chemists and physicists to understand the dominant factors determining the specificity and directionality of transmembrane transfer processes in proteins. a large variety of experimental techniques is being used including x-ray and neutron diffraction, but also time-resolved optical, infrared and magnetic resonance spectroscopy. this is done in conjunction with genetic engineering strategies to construct site-specif ... | 2005 | 19785170 |
| effect of detergent concentration on the thermal stability of a membrane protein: the case study of bacterial reaction center solubilized by n,n-dimethyldodecylamine-n-oxide. | we report on the response of reaction center (rc) from rhodobacter sphaeroides (an archetype of membrane proteins) to the exposure at high temperature. the rcs have been solubilized in aqueous solution of the detergent n,n-dimethyldodecylamine-n-oxide (ldao). changes in the protein conformation have been probed by monitoring the variation in the absorbance of the bacteriochlorine cofactors and modification in the efficiency of energy transfer from tryptophans to cofactors and among the cofactors ... | 2010 | 19786126 |
| theoretical examination of quantum coherence in a photosynthetic system at physiological temperature. | the observation of long-lived electronic coherence in a photosynthetic pigment-protein complex, the fenna-matthews-olson (fmo) complex, is suggestive that quantum coherence might play a significant role in achieving the remarkable efficiency of photosynthetic electronic energy transfer (eet), although the data were acquired at cryogenic temperature [engel gs, et al. (2007) evidence for wavelike energy transfer through quantum coherence in photosynthetic systems. nature 446:782-786]. in this pape ... | 2009 | 19815512 |
| femtosecond phase of charge separation in reaction centers of chloroflexus aurantiacus. | difference absorption spectroscopy with temporal resolution of approximately 20 fsec was used to study the primary phase of charge separation in isolated reaction centers (rcs) of chloroflexus aurantiacus at 90 k. an ensemble of difference (light-minus-dark) absorption spectra in the 730-795 nm region measured at -0.1 to 4 psec delays relative to the excitation pulse was analyzed. comparison with analogous data for rcs of hm182l mutant of rhodobacter sphaeroides having the same pigment compositi ... | 2009 | 19817684 |
| catellibacterium aquatile sp. nov., isolated from fresh water, and emended description of the genus catellibacterium tanaka et al. 2004. | a gram-negative, rod-shaped, non-pigmented, non-spore-forming bacterial strain that was motile by a single polar flagellum, designated a1-9(t), was isolated from daqing reservoir in north-east china and its taxonomic position was studied using a polyphasic approach. strain a1-9(t) was non-halophilic, strictly aerobic and heterotrophic and lacked carotenoids, internal membranes and genes for photosynthesis (puf genes). strain a1-9(t) grew at 10-40 degrees c (optimum, 25-30 degrees c) and ph 5.5-9 ... | 2010 | 19820000 |
| characterization of the photosynthetic apparatus and proteome of roseobacter denitrificans. | the phototrophic capacity of aerobic anoxygenic phototrophic bacteria endows them with a selective advantage over other heterotrophic bacteria in the oligotrophic ocean. here, we reported the phototrophic features and proteome of an aerobic phototrophic bacterium roseobacter denitrificans under starvation stress. the fluorescence induction and relaxation measurements suggested that the photosynthetic capacity in r. denitrificans was preserved but was lower than in the photoautotrophic bacterium ... | 2010 | 19826863 |
| production of phenols and alkyl gallate esters by rhodobacter sphaeroides ou5. | rhodobacter sphaeroides ou5 grows phototrophically with generation doubling time of 18 h on l-phenylalanine when used as sole source of nitrogen. phenols accumulated in the medium and gallate (0.5 mm) was identified as one of the major product. the others namely protocatechuate (0.2 mm) and caffeate (0.1 mm) and also three putative phenol alkyl esters were identified using liquid chromatography-mass spectroscopy (lc-ms) analysis from the culture supernatant. rhodobacter sphaeroides ou5 strain co ... | 2010 | 19826864 |
| development of qsar-models for classification and prediction of baseline toxicity and of uncoupling of energy transduction. | | 2007 | 19835067 |
| rhodobacter johrii sp. nov., an endospore-producing cryptic species isolated from semi-arid tropical soils. | an oval to rod-shaped, phototrophic, purple non-sulfur bacterium, strain ja192(t), was isolated from an enrichment culture of a pasteurized rhizosphere soil sample from a field cultivated with jowar (sorghum) collected from godumakunta village near hyderabad, india. strain ja192(t) is gram-negative, motile and produces endospores. phylogenetic analysis on the basis of 16s rrna gene sequences showed that the strain ja192(t) is closely related to rhodobacter sphaeroides 2.4.1(t) (99.9 % sequence s ... | 2010 | 19854875 |
| electron transfer from cytochrome c(2) to the reaction center: a transition state model for ionic strength effects due to neutral mutations. | interprotein electron transfer plays an important role in biological energy conversion. in this work, the electron transfer reaction between cytochrome c(2) (cyt) and the reaction center (rc) was studied to determine the mechanisms coupling association and electron transfer. previous studies have shown that mutation of hydrophobic residues in the reaction interface, particularly tyr l162, changes the binding affinity and rates of electron transfer at low ionic strengths. in this study, the effec ... | 2009 | 19877711 |
| a cryptochrome-like protein is involved in the regulation of photosynthesis genes in rhodobacter sphaeroides. | blue light receptors belonging to the cryptochrome/photolyase family are found in all kingdoms of life. the functions of photolyases in repair of uv-damaged dna as well as of cryptochromes in the light-dependent regulation of photomorphogenetic processes and in the circadian clock in plants and animals are well analysed. in prokaryotes, the only role of members of this protein family that could be demonstrated is dna repair. recently, we identified a gene for a cryptochrome-like protein (cryb) i ... | 2009 | 19878455 |
| a model invalidation-based approach for elucidating biological signalling pathways, applied to the chemotaxis pathway in r. sphaeroides. | developing methods for understanding the connectivity of signalling pathways is a major challenge in biological research. for this purpose, mathematical models are routinely developed based on experimental observations, which also allow the prediction of the system behaviour under different experimental conditions. often, however, the same experimental data can be represented by several competing network models. | 2009 | 19878602 |
| competitive inhibitions of the chlorophyll synthase of synechocystis sp. strain pcc 6803 by bacteriochlorophyllide a and the bacteriochlorophyll synthase of rhodobacter sphaeroides by chlorophyllide a. | the photosynthetic growth of synechocystis sp. strain pcc 6803 is hampered by exogenously added bacteriochlorophyllide a (bchlide a) in a dose-dependent manner. the growth inhibition caused by bchlide a, however, is relieved by an increased level of exogenously added chlorophyllide a (chlide a). the results are explained by the competitive inhibition of chlorophyll synthase by bchlide a, with inhibition constants (k(i)s) of 0.3 mm and 1.14 mm in the presence of sufficient geranylgeranyl pyrophos ... | 2010 | 19880605 |
| spectral diffusion and electron-phonon coupling of the b800 bchl a molecules in lh2 complexes from three different species of purple bacteria. | we have investigated the spectral diffusion and the electron-phonon coupling of b800 bacteriochlorophyll a molecules in the peripheral light-harvesting complex lh2 for three different species of purple bacteria, rhodobacter sphaeroides, rhodospirillum molischianum, and rhodopseudomonas acidophila. we come to the conclusion that b800 binding pockets for rhodobacter sphaeroides and rhodopseudomonas acidophila are rather similar with respect to the polarity of the protein environment but that the p ... | 2009 | 19883604 |
| a new system for heterologous expression of membrane proteins: rhodospirillum rubrum. | heterologous expression of membrane proteins has met with only limited success. this work presents a new host/vector system for the production of heterologous membrane proteins based on a mutant of the facultatively phototrophic bacterium rhodospirillum rubrum. under certain growth conditions, r. rubrum forms an intracytoplasmic membrane (icm) that houses the photosynthetic apparatus, the structural proteins of which are encoded by puha and pufbalm. the mutant r. rubrum h2, which was constructed ... | 2010 | 19887111 |
| the cobinamide amidohydrolase (cobyric acid-forming) cbiz enzyme: a critical activity of the cobamide remodelling system of rhodobacter sphaeroides. | the chemical structures of cobamides [cobalamin (cbl)-like compounds] are the same, except for the lower ligand, which in adenosylcobalamin (adocbl) is 5,6-dimethylbenzimidazole, and in adenosylpseudocobalamin (adopseudocbl) is adenine. why the lower ligand of cobamides varies and what the mechanism of lower ligand replacement is are long-standing questions in the field of b(12) biosynthesis. work reported here uncovers the strategy used by the photosynthetic alpha-proteobacterium rhodobacter sp ... | 2009 | 19889098 |
| excitation and electron transfer in reaction centers from rhodobacter sphaeroides probed and analyzed globally in the 1-nanosecond temporal window from 330 to 700 nm. | global analysis of a set of room temperature transient absorption spectra of rhodobacter sphaeroides reaction centers, recorded in wide temporal and spectral ranges and triggered by femtosecond excitation of accessory bacteriochlorophylls at 800 nm, is presented. the data give a comprehensive review of all spectral dynamics features in the visible and near uv, from 330 to 700 nm, related to the primary events in the rb. sphaeroides reaction center: excitation energy transfer from the accessory b ... | 2009 | 19890535 |
| a glycophorin a-like framework for the dimerization of photosynthetic core complexes. | the core complex in photosynthetic bacteria plays a central role in photosynthesis. this molecular assembly is composed of two protein complexes, viz., the light-harvesting complex i (lh1), which absorbs sunlight by means of the protein-bound bacteriochlorophylls, and the reaction center (rc), which uses the light-excitation energy absorbed by the lh complexes to produce a transmembrane (tm) charge gradient, subsequently employed for energy conversion. in rhodobacter (rba.) sphaeroides, the core ... | 2009 | 19891482 |
| oligomeric characterization of the photosynthetic apparatus of rhodobacter sphaeroides r26.1 by nondenaturing electrophoresis methods. | blue and colorless native gel electrophoresis in combination with lc-esi-ms/ms are powerful tools in the analysis of protein networks in biological membranes. we used these techniques in the present study to generate a comprehensive overview on a proteome-wide scale of intracytoplasmic membrane (icm) associated proteins in order to investigate the native supramolecular organization of rhodobacter sphaeroides r26.1 photosynthetic apparatus. the results obtained were compared with past proteomic d ... | 2010 | 19899738 |
| photooxidative stress-induced and abundant small rnas in rhodobacter sphaeroides. | exposure to oxygen and light generates photooxidative stress by the bacteriochlorophyll a mediated formation of singlet oxygen ((1)o(2)) in rhodobacter sphaeroides. our study reports the genome-wide search for small rnas (srnas) involved in the regulatory response to (1)o(2). by using 454 pyrosequencing and northern blot analysis, we identified 20 srnas from r. sphaeroides aerobic cultures or following treatment with (1)o(2) or superoxide (o(-)(2)). one srna was specifically induced by (1)o(2) a ... | 2009 | 19906181 |
| primary processes of charge separation in reaction centers of ym210l/fm197y and ym210l mutants of rhodobacter sphaeroides. | difference femtosecond absorption spectroscopy with 20-fsec temporal resolution was applied to study a primary stage of charge separation and transfer processes in reaction centers of ym210l and ym210l/fm197y site-directed mutants of the purple bacterium rhodobacter sphaeroides at 90 k. photoexcitation was tuned to the absorption band of the primary electron donor p at 880 nm. coherent oscillations in the kinetics of stimulated emission of p* excited state at 940 nm and of anion absorption of mo ... | 2009 | 19916934 |
| visualizing changes in electron distribution in coupled chains of cytochrome bc(1) by modifying barrier for electron transfer between the fes cluster and heme c(1). | cytochrome c(1) of rhodobacter (rba.) species provides a series of mutants which change barriers for electron transfer through the cofactor chains of cytochrome bc(1) by modifying heme c(1) redox midpoint potential. analysis of post-flash electron distribution in such systems can provide useful information about the contribution of individual reactions to the overall electron flow. in rba. capsulatus, the non-functional low-potential forms of cytochrome c(1) which are devoid of the disulfide bon ... | 2010 | 19917265 |
| serine 254 enhances an induced fit mechanism in murine 5-aminolevulinate synthase. | 5-aminolevulinate synthase (ec 2.3.1.37) (alas), a pyridoxal 5'-phosphate (plp)-dependent enzyme, catalyzes the initial step of heme biosynthesis in animals, fungi, and some bacteria. condensation of glycine and succinyl coenzyme a produces 5-aminolevulinate, coenzyme a, and carbon dioxide. x-ray crystal structures of rhodobacter capsulatus alas reveal that a conserved active site serine moves to within hydrogen bonding distance of the phenolic oxygen of the plp cofactor in the closed substrate- ... | 2010 | 19917609 |
| analyses of binding sequences of the phar protein of rhodobacter sphaeroides fj1. | the phac, phap, phar, and phaz genes are involved in the synthesis, accumulation, and degradation of poly-beta-hydroxybutyrate (phb). these genes encode the phb synthase, phasin, regulatory protein, and phb depolymerase, respectively, and are located in the same locus in the genome of rhodobacter sphaeroides fj1, a purple nonsulfur bacterium capable of producing phb. we have previously found that the phar protein binds to the promoter regions of phap, phar, and phaz and represses their expressio ... | 2010 | 19925635 |