| dietary karaya saponin and rhodobacter capsulatus exert hypocholesterolemic effects by suppression of hepatic cholesterol synthesis and promotion of bile acid synthesis in laying hens. | this study was conducted to elucidate the mechanism underlying the hypolipidemic action of karaya saponin or rhodobacter (r.) capsulatus. a total of 40 laying hens (20-week-old) were assigned into four dietary treatment groups and fed a basal diet (as a control) or basal diets supplemented with either karaya saponin, r. capsulatus, or both for 60 days. the level of serum low-density-lipoprotein cholesterol and the levels of cholesterol and triglycerides in the serum, liver, and egg yolk were red ... | 2010 | 21490913 |
| zinc inhibition of bacterial cytochrome bc(1) reveals the role of cytochrome b e295 in proton release at the q(o) site. | the cytochrome (cyt) bc(1) complex (cyt bc(1)) plays a major role in the electrogenic extrusion of protons across the membrane responsible for the proton motive force to produce atp. proton-coupled electron transfer underlying the catalysis of cyt bc(1) is generally accepted, but the molecular basis of coupling and associated proton efflux pathway(s) remains unclear. herein we studied zn(2+)-induced inhibition of rhodobacter capsulatus cyt bc(1) using enzyme kinetics, isothermal titration calori ... | 2011 | 21500804 |
| a bchd (magnesium chelatase) mutant of rhodobacter sphaeroides synthesizes zinc bacteriochlorophyll through novel zinc-containing intermediates. | heme and bacteriochlorophyll a (bchl) biosyntheses share the same pathway to protoporphyrin ix, which then branches as follows. fe(2+) chelation into the macrocycle by ferrochelatase results in heme formation, and mg(2+) addition by mg-chelatase commits the porphyrin to bchl synthesis. it was recently discovered that a bchd (mg-chelatase) mutant of rhodobacter sphaeroides produces an alternative bchl in which mg(2+) is substituted by zn(2+). zn-bchl has been found in only one other organism befo ... | 2011 | 21502322 |
| acetyl group orientation modulates the electronic ground-state asymmetry of the special pair in purple bacterial reaction centers. | recent experimental data point to an asymmetric ground-state electronic distribution in the special pair (p) of purple bacterial reaction centers, which acts as the primary electron donor in photosynthesis. we have performed a density functional theory investigation on an extended model including the bacteriochlorophyll dimer and a few relevant surrounding residues to explore the origin of this asymmetry. we find strong evidence that the ground-state electron density in p is intrinsically asymme ... | 2011 | 21512686 |
| the photosynthetic membrane proteome of rhodobacter sphaeroides r-26.1 exposed to cobalt. | cells of the carotenoidless strain r-26.1 of rhodobacter sphaeroides were grown in the presence of a high concentration (5 mm) of cobalt ions. the photosynthetic intracytoplasmic membranes were isolated and investigated by proteomic analysis using non-denaturating blue native electrophoresis in combination with lc-esi-ms/ms. comparison with intracytoplasmic membranes of cells grown under control conditions showed a change in the relative amount of proteins belonging to the photosynthetic apparat ... | 2011 | 21515364 |
| major phylogenetic groups of marine bacteria differ in growth response to natural phytoplankton blooms in the western north pacific. | growth and productivity of phytoplankton substantially change organic matter characteristics, which affect bacterial abundance, productivity, and community structure in aquatic ecosystems. we analyzed bacterial community structures and measured activities inside and outside of phytoplankton blooms in the northwest pacific ocean by using bromodeoxyuridine immunocytochemistry fluorescence in situ hybridization (bic-fish). roseobacter/rhodobacter, sar11, betaproteobacteria, alteromonas, sar86, and ... | 2011 | 21515719 |
| use of a new motion analysis system to characterise the chemosensory response kinetics of rhodobacter sphaeroides under different growth conditions. | we developed a new set of software tools which enable the speed and response kinetics of large numbers of tethered bacterial cells to be rapidly measured and analysed. the software provides precision, accuracy and good signal to noise ratio combined with ease of data handling and processing. the software was tested on the single-cell chemosensory response kinetics of large numbers of rhodobacter sphaeroides cells grown under either aerobic or photoheterotrophic conditions and either in chemostat ... | 2011 | 21515726 |
| [characteristics of biodegradation of triphenyltin by rhodopseudomonos spheroids]. | the biodegradation of triphenyltin (tpt) by rhodopseudomonos spheroids was investigated in this study. the results illuminated that r. spheroids was an effective strain for the biodegradation of tpt. the maximum removal ratio was attained when the growth temperature of r. spheroids was 30 degrees c. after treating for 3 hours, the removal ratios of 3 mg x l(-1) tpt were 13.82% to 47.29% using 0.49 g x l(-1) (based on dry weight) biomass of r. spheroids. the experiments on biodegradation of tpt w ... | 2011 | 21528580 |
| contribution of hfq to photooxidative stress resistance and global regulation in rhodobacter sphaeroides. | the photosynthetic alphaproteobacterium rhodobacter sphaeroides has to cope with photooxidative stress that is caused by the bacteriochlorophyll a-mediated formation of singlet oxygen ((1) o(2) ). exposure to (1) o(2) induces the alternative sigma factors rpoe and rpoh(ii) which then promote transcription of photooxidative stress-related genes, including small rnas (srnas). the ubiquitous rna chaperone hfq is well established to interact with and facilitate the base-pairing of srnas and target m ... | 2011 | 21535243 |
| direct visualization of exciton reequilibration in the lh1 and lh2 complexes of rhodobacter sphaeroides by multipulse spectroscopy. | the dynamics of the excited states of the light-harvesting complexes lh1 and lh2 of rhodobacter sphaeroides are governed, mainly, by the excitonic nature of these ring-systems. in a pump-dump-probe experiment, the first pulse promotes lh1 or lh2 to its excited state and the second pulse dumps a portion of the excited state. by selective dumping, we can disentangle the dynamics normally hidden in the excited-state manifold. we find that by using this multiple-excitation technique we can visualize ... | 2011 | 21539791 |
| single-shot ultrabroadband two-dimensional electronic spectroscopy of the light-harvesting complex lh2. | here we present two-dimensional (2d) electronic spectra of the light-harvesting complex lh2 from purple bacteria using coherent pulses with bandwidth of over 100 nm fwhm. this broadband excitation and detection has allowed the simultaneous capture of both the b800 and b850 bands using a single light source. we demonstrate that one laser pulse is sufficient to capture the entire 2d electronic spectrum with a high signal-to-noise ratio. at a waiting time of 800 fs, we observe population transfer f ... | 2011 | 21540962 |
| 2d-seira spectroscopy to highlight conformational changes of the cytochrome c oxidase induced by direct electron transfer. | potentiometric titrations of the cytochrome c oxidase (cco) immobilized in a biomimetic membrane system were followed by two-dimensional surface-enhanced ir absorption spectroscopy (2d seiras) in the atr-mode. direct electron transfer was employed to vary the redox state of the enzyme. the cco was shown to undergo a conformational transition from a non-activated to an activated state after it was allowed to turnover in the presence of oxygen. differences between the non-activated and activated s ... | 2011 | 21541411 |
| [on the influence of local molecular environment on the redox potential of electron transfer cofactors in bacterial photosynthetic reaction centers]. | the addition of cryosolvents (glycerol, dimethylsulfoxide) to a water solution containing bacterial photosynthetic reaction centers changes the redox potential of the bacteriochlorophyll dimer, but does not affect the redox potential of the quinone primary acceptor. it has been shown that the change in redox potential can be produced by changes of the electrostatic interactions between cofactors and the local molecular environment modified by additives entered into the solution. the degree of in ... | 2011 | 21542354 |
| coral-associated bacterial assemblages: current knowledge and the potential for climate-driven impacts. | the importance of associations between microorganisms and their invertebrate hosts is becoming increasingly apparent. an emerging field, driven by the necessity to understand the microbial relationships that both maximize coral health and cause coral disease, is the study of coral-bacteria interactions. in this article, we review our current understanding of the diversity, specificity, development, and functions of coral-associated bacteria. we also summarize what is known regarding the role of ... | 2010 | 21558231 |
| light-induced conformational changes in photosynthetic reaction centers: impact of detergents and lipids on the electronic structure of the primary electron donor. | light-induced hypsochromic shifts of the q(y) absorption band of the bacteriochlorophyll dimer (p) from 865 to 850 nm were identified using continuous illumination of dark-adapted reaction centers (rcs) from rhodobacter capsulatus when dispersed in the most commonly used detergent, the zwitterionic lauryl n-dimethylamine-n-oxide. such a shift is known to be the consequence of the decreased degree of delocalization of p. a 2-fold acceleration of the recovery kinetics of p(+) was found in rcs that ... | 2011 | 21561160 |
| phylotype-specific productivity of marine bacterial populations in eutrophic seawater, as revealed by bromodeoxyuridine immunocytochemistry combined with fluorescence in situ hybridization. | among the fundamental questions in marine microbial ecology are which taxa or phylogenetic groups account for total bacterial productivity and what is the relative contribution of each. we combined bromodeoxyuridine (brdu) immunocytochemistry and fluorescence in situ hybridization (bic-fish) to examine phylotype-specific contributions to total bacterial productivity in eutrophic seawater. we also examined year-round changes in phylotype-specific contributions and explored the factors controlling ... | 2009 | 21566391 |
| stepwise increase of resveratrol biosynthesis in yeast saccharomyces cerevisiae by metabolic engineering. | resveratrol is a unique, natural polyphenolic compound with diverse health benefits. in the present study, we attempted to improve resveratrol biosynthesis in yeast by different methods of metabolic engineering. we first mutated and then re-synthesized tyrosine ammonia lyase (tal) by replacing the bacteria codons with yeast-preferred codons, which increased translation and improved p-coumaric acid and resveratrol biosynthesis drastically. we then demonstrated that low-affinity, high-capacity bac ... | 2011 | 21570474 |
| coordinated, long-range, solid substrate movement of the purple photosynthetic bacterium rhodobacter capsulatus. | the long-range movement of rhodobacter capsulatus cells in the glass-agar interstitial region of borosilicate petri plates was found to be due to a subset of the cells inoculated into plates. the macroscopic appearance of plates indicated that a small group of cells moved in a coordinated manner to form a visible satellite cluster of cells. satellite clusters were initially separated from the point of inoculation by the absence of visible cell density, but after 20 to 24 hours this space was col ... | 2011 | 21573194 |
| feedback control architecture and the bacterial chemotaxis network. | bacteria move towards favourable and away from toxic environments by changing their swimming pattern. this response is regulated by the chemotaxis signalling pathway, which has an important feature: it uses feedback to 'reset' (adapt) the bacterial sensing ability, which allows the bacteria to sense a range of background environmental changes. the role of this feedback has been studied extensively in the simple chemotaxis pathway of escherichia coli. however it has been recently found that the m ... | 2011 | 21573199 |
| modeling the light- and redox-dependent interaction of ppsr/appa in rhodobacter sphaeroides. | facultative photosynthetic bacteria switch their energy generation mechanism from respiration to photosynthesis depending on oxygen tension and light. part of this transition is mediated by the aerobic transcriptional repressor ppsr. in rhodobacter sphaeroides, the repressive action of ppsr is antagonized by the redox- and blue-light-sensitive flavoprotein appa which results in a unique phenotype: the repression of photosynthesis genes at intermediate oxygen levels and high light intensity, whic ... | 2011 | 21575568 |
| properties of rhodobacter sphaeroides photosynthetic reaction center with double amino acid substitution i(l177)h+h(m182)l. | histidine m182 in the reaction center (rc) of rhodobacter sphaeroides serves as the fifth ligand of the bacteriochlorophyll (bchl) b(b) mg atom. when this his is substituted by an amino acid that is not able to coordinate mg, bacteriopheophytin appears in the b(b) binding site instead of bchl (katilius, e., et al. (1999) j. phys. chem. b, 103, 7386-7389). we have shown that in the presence of the additional mutation i(l177)h the coordination of the bchl b(b) mg atom in the double mutant i(l177)h ... | 2011 | 21585320 |
| insights into structure and function of the active site of soxax cytochromes. | soxax cytochromes catalyze the formation of heterodisulfide bonds between inorganic sulfur compounds and a carrier protein, soxyz. they contain unusual his/cys ligated heme groups with complex spectroscopic signatures. the heme ligating cysteine has been implicated in soxax-catalysis, but neither the soxax spectroscopic properties nor its catalysis are fully understood at present. we have solved the first crystal structure for a group2 soxax protein (snsoxax), where an n-terminal extension of so ... | 2011 | 21592966 |
| reconstitution of bacterial photosynthetic unit in a lipid bilayer studied by single-molecule spectroscopy at 5 k. | as a model of photosynthetic unit (psu), self-assembled aggregates of pigment-protein complexes from photosynthetic bacteria were prepared in a lipid bilayer by reconstitution of the light-harvesting 2 (lh2) complex and light-harvesting 1-reaction center (lh1-rc) complex through detergent removal of their micelles in the presence of lipids. by performing polarization-controlled fluorescence and fluorescence-excitation spectroscopy on single aggregates at a temperature of 5 k, the composition of ... | 2011 | 21597611 |
| mapping lipid and detergent molecules at the surface of membrane proteins. | electron-density maps for the crystal structures of membrane proteins often show features suggesting binding of lipids and/or detergent molecules on the hydrophobic surface, but usually it is difficult to identify the bound molecules. in our studies, heavy-atom-labelled phospholipids and detergents have been used to unequivocally identify these binding sites at the surfaces of test membrane proteins, the reaction centres from rhodobacter sphaeroides and blastochloris viridis. the generality of t ... | 2011 | 21599648 |
| modification of the genome of rhodobacter sphaeroides and construction of synthetic operons. | the α-proteobacterium rhodobacter sphaeroides is an exemplary model organism for the creation and study of novel protein expression systems, especially membrane protein complexes that harvest light energy to yield electrical energy. advantages of this organism include a sequenced genome, tools for genetic engineering, a well-characterized metabolism, and a large membrane surface area when grown under hypoxic or anoxic conditions. this chapter provides a framework for the utilization of r. sphaer ... | 2011 | 21601102 |
| configuration of spheroidene in the photosynthetic reaction center of rhodobacter sphaeroides : a comparison of wild-type and reconstituted r26. | we compare the resonance raman spectra acquired at two excitation wavelengths, 496.5 and 514.5 nm, of spheroidene in the wild-type reaction center of rhodobacter sphaeroides and reconstituted into the reaction center of the rhodobacter sphaeroides mutant r26. our earlier work showed that the reconstituted r26 reaction center holds spheroidene in two configurations: 15,15'-cis and another configuration. here we show that in the wild-type reaction center only 15,15'-cis spheroidene is present. in ... | 2011 | 21604722 |
| molecular basis of proton uptake in single and double mutants of cytochrome c oxidase. | cytochrome c oxidase, the terminal enzyme of the respiratory chain, utilizes the reduction of dioxygen into water to pump protons across the mitochondrial inner membrane. the principal pathway of proton uptake into the enzyme, the d channel, is a 2.5 nm long channel-like cavity named after a conserved, negatively charged aspartic acid (d) residue thought to help recruiting protons to its entrance (d132 in the first subunit of the s. sphaeroides enzyme). the single-point mutation of d132 to aspar ... | 2011 | 21613706 |
| genome sequence of rhodobacter sphaeroides strain ws8n. | r. sphaeroides is a metabolically diverse photosynthetic alpha-proteobacterium found ubiquitously in soil and in fresh water habitats. here we present the annotated genome sequence of rhodobacter sphaeroides ws8n. | 2011 | 21622735 |
| the hydrogen-bond switch reaction of the blrb bluf domain of rhodobacter sphaeroides. | the blrb protein from rhodobacter sphaeroides is a small 136 amino acid photoreceptor belonging to the bluf family of blue light receptors. it contains merely the conserved bluf fold responsible for binding the flavin pigment and a short c-terminal extension of unknown function. we investigated the primary photoreactions of blrb by picosecond fluorescence and transient absorption spectroscopy. after excitation of the flavin the fluorescence decays in an h/d isotope independent manner with time c ... | 2011 | 21627064 |
| electronic pathway in reaction centers from rhodobacter sphaeroides and chloroflexus aurantiacus. | the reaction centers (rc) of chloroflexus aurantiacus and rhodobacter sphaeroidesh(m182)l mutant were investigated. prediction for electron transfer (et) at very low temperatures was also performed. to describe the kinetics of the c. aurantiacus rcs, the incoherent model of electron transfer was used. it was shown that the asymmetry in electronic coupling parameters must be included to explain the experiments. for the description of r. sphaeroidesh(m182)l mutant rcs, the coherent and incoherent ... | 2010 | 21629589 |
| identification of unsaturated n-acylhomoserine lactones in bacterial isolates of rhodobacter sphaeroides by liquid chromatography coupled to electrospray ionization-hybrid linear ion trap-fourier transform ion cyclotron resonance mass spectrometry. | the identification of two unsaturated n-acylhomoserine lactones (ahls) produced by rhodobacter sphaeroides bacteria, based on liquid chromatography (lc) coupled to a hybrid quadrupole linear ion trap (ltq)-fourier transform ion cyclotron resonance (fticr) mass spectrometer upon electrospray ionization (esi), is presented. besides the confirmation of the signaling molecule already described in the literature, i.e. (z)-n-tetradec-7-enoyl-homoserine lactone (c(14:1) -hsl), we have discovered the oc ... | 2011 | 21638357 |
| ftir spectroscopy of the reaction center of chloroflexus aurantiacus: photoreduction of the bacteriopheophytin electron acceptor. | mid-infrared spectral changes associated with the photoreduction of the bacteriopheophytin electron acceptor h(a) in reaction centers (rcs) of the filamentous anoxygenic phototrophic bacterium chloroflexus (cfl.) aurantiacus are examined by light-induced fourier transform infrared (ftir) spectroscopy. the light-induced h(a)(-)/h(a) ftir (1800-1200cm(-1)) difference spectrum of cfl. aurantiacus rcs is compared to that of the previously well characterized purple bacterium rhodobacter (rba.) sphaer ... | 2011 | 21641333 |
| regulation of flagella number by flia and flgm and the role in biofilm formation of rhodobacter sphaeroides. | the flgm secretion checkpoint plays a crucial role in coordinating bacterial flagellar assembly. here we identify a new role for flgm and flia as part of a complex regulatory network which controls flagella number and is essential for efficient swimming and biofilm formation in the monotrichous bacterium rhodobacter sphaeroides. | 2011 | 21642454 |
| carotenoids are essential for normal levels of dimerisation of the rc-lh1-pufx core complex of rhodobacter sphaeroides: characterisation of r-26 as a crtb (phytoene synthase) mutant. | carotenoids play important roles in photosynthesis where they are involved in light-harvesting, in photo-protection and in the assembly and structural stability of light-harvesting and reaction centre complexes. in order to examine the effects of carotenoids on the oligomeric state of the reaction centre-light-harvesting 1 -pufx (rc-lh1-pufx) core complex of rhodobacter sphaeroides two carotenoid-less mutants, tc70 and r-26, were studied. detergent fractionation showed that in the absence of car ... | 2011 | 21651888 |
| monomeric rc-lh1 core complexes retard lh2 assembly and intracytoplasmic membrane formation in pufx-minus mutants of rhodobacter sphaeroides. | in the model photosynthetic bacterium rhodobacter sphaeroides domains of light-harvesting 2 (lh2) complexes surround and interconnect dimeric reaction centre-light-harvesting 1-pufx (rc-lh1-pufx) 'core' complexes, forming extensive networks for energy transfer and trapping. these complexes are housed in spherical intracytoplasmic membranes (icms), which are assembled in a stepwise process where biosynthesis of core complexes tends to dominate the early stages of membrane invagination. the kineti ... | 2011 | 21663730 |
| use of engineered unique cysteine residues to facilitate oriented coupling of proteins directly to a gold substrate. | a prerequisite for any "lab on a chip" device that utilizes an electrical signal from the sensor protein is the ability to attach the protein in a specific orientation onto a conducting substrate. here, we demonstrate the covalent attachment to a gold surface of light-harvesting membrane proteins, from rhodobacter sphaeroides, via cysteine (cys) residues engineered on either the cytoplasmic or periplasmic face. this simple directed attachment is superior in its ability to retain light-harvesting ... | 2011 | 21668872 |
| calculated vibrational properties of pigments in protein binding sites. | ftir difference spectroscopy is widely used to probe molecular bonding interactions of protein-bound electron transfer cofactors. the technique is particularly attractive because it provides information on both neutral and radical cofactor states. such dual information is not easily obtainable using other techniques. although ftir difference spectroscopy has been used to study cofactors in biological protein complexes, in nearly all cases interpretation of the spectra has been purely qualitative ... | 2011 | 21670247 |
| charge recombination time distributions in photosynthetic reaction centers exposed to alternating intervals of photoexcitation and dark relaxation. | the charge recombination lifetime of photosynthetic reaction centers (rcs) increases significantly upon lengthy illumination, revealing nonequilibrium structural transitions in the protein-cofactor system. this paper analyzes the charge recombination kinetics measured in isolated rcs following a systematic variation of actinic illumination times (pulses) from 0.1 s to hundreds of seconds. the maximum entropy method (mem) was utilized for optimizing the fitting procedure to retrieve the relaxatio ... | 2011 | 21671683 |
| overexpression of rhodobacter sphaeroides pufx-bearing maltose-binding protein and its effect on the stability of reconstituted light-harvesting core antenna complex. | the pufx protein, encoded by the pufx gene of rhodobacter sphaeroides, plays a key role in the organization and function of the core antenna (lh1)-reaction centre (rc) complex, which collects photons and triggers primary photochemical reactions. we synthesized a pufx/maltose-binding protein (mbp) fusion protein to study the effect of the pufx protein on the reconstitution of b820 subunit-type and lh1-type complexes. the fusion protein was synthesized using an escherichia coli expression system a ... | 2011 | 21809113 |
| anti-hiv siamycin i directly inhibits autophosphorylation activity of the bacterial fsrc quorum sensor and other atp-dependent enzyme activities. | siamycin i disrupts growth and quorum sensing in enterococcus faecalis. using purified intact protein, we demonstrate here that quorum membrane sensor kinase fsrc is a direct target of siamycin i, reducing pheromone-stimulated autophosphorylation activity by up to 91%. inhibition was non-competitive with atp as substrate. other atp-binding enzymes were also inhibited, including nine other membrane sensor kinases of e. faecalis, rhodobacter sphaeroides prrb, porcine na(+)-dependent atpase and the ... | 2011 | 21803040 |
| oligomerization state of photosynthetic core complexes is correlated with the dimerization affinity of a transmembrane helix. | in the <i>rhodobacter</i> (<i>rba.</i>) species of photosynthetic purple bacteria, a single transmembrane a-helix, pufx, is found within the core complex, an essential photosynthetic macromolecular assembly that performs the absorption and the initial processing of light energy. despite its structural simplicity, many unresolved questions surround pufx, the most important of which is its location within the photosynthetic core complex. one proposed placement of pufx is at the center of a core co ... | 2011 | 21790140 |
| [triplet state of the primary donor in reaction centers of the phototrophic bacterium rhodobacter sphaeroides r26 with active photoinduced electron transfer]. | epr characteristics of transient paramagnetic states photoinduced in isolated reaction centers of rhodobacter sphaeroides r26 with intact electron transfer have been studied. it was demonstrated that the detected weak triplet state epr signal belongs to the primary donor molecule and is populated via the conventional mechanism of radical pair s-t0 mixing. the distortion of the spectral shape of this signal is explained by the triplet quantum yield anisotropy brought about by the short lifetime o ... | 2011 | 21786698 |
| effects of the measuring light on the photochemistry of the bacterial photosynthetic reaction center from rhodobacter sphaeroides. | the bacterial reaction center (rc) has become a reference model in the study of the diverse interactions of quinones with electron transfer complexes. in these studies, the rc functionality was probed through flash-induced absorption changes where the state of the primary donor is probed by means of a continuous measuring beam and the electron transfer is triggered by a short intense light pulse. the single-beam set-up implies the use as reference of the transmittance measured before the light p ... | 2011 | 21785991 |
| electron transport in acetate-grown methanosarcina acetivorans. | abstract: background: acetate is the major source of methane in nature. the majority of investigations have focused on acetotrophic methanogens for which energy-conserving electron transport is dependent on the production and consumption of h2 as an intermediate, although the great majority of acetotrophs are unable to metabolize h2. the presence of cytochrome c and a complex (ma-rnf) homologous to the rnf (rhodobacter nitrogen fixation) complexes distributed in the domain bacteria distinguishes ... | 2011 | 21781343 |
| irsp1095: a genome-scale reconstruction of the rhodobacter sphaeroides metabolic network. | abstract: background: rhodobacter sphaeroides is one of the best studied purple non-sulfur photosynthetic bacteria and serves as an excellent model for the study of photosynthesis and the metabolic capabilities of this and related facultative organisms. the ability of r. sphaeroides to produce hydrogen (h2), polyhydroxybutyrate (phb) or other hydrocarbons, as well as its ability to utilize atmospheric carbon dioxide (co2) as a carbon source under defined conditions, make it an excellent candidat ... | 2011 | 21777427 |
| immobilized purple bacteria for light-driven h(2) production from starch and potato fermentation effluents. | the goal of the study was to show that immobilized purple bacteria could photoproduce h(2) using dark fermentation effluent (fe) as substrate. simple pretreatment of an inexpensive glass-fiber matrix accelerated the immobilization process. photobioreactors (phbr) containing immobilized rhodobacter sphaeroides gl produced 0.128 l h(2) h(-1) l(-1) of phbr volume (0.570 l h(-1) l(-1) of matrix) for up to 3 months when continuously fed artificial media with volatile fatty acids (vfas) or fe from pot ... | 2011 | 21751433 |
| electron transfer in reaction centers of rhodopseudomonas sphaeroides. ii. free energy and kinetic relations between the acceptor states q(a-) q(b-) and q(a)q(2-b). | thermodynamic equilibria and electron transfer kinetics involving the quinone acceptor complex in reaction centers from rhodopseudomonas sphaeroides were investigated. we focussed on reactions involving the two-electron states qa qn and qaq~-, described by the schemedqaqa~-d +x,~~a- , ~~a- ~k~ .~d+ "r~~ ak~'la2- - k~2~ k~lk o~ (2)d+~d the equilibrium partitioning between qa q n and qaq 2n- was determined spectroscopically from either the concentration of oxidized cytochrome c or the concentratio ... | 1985 | 21780325 |
| fructose increases the resistance of rhodobacter capsulatus to the toxic oxyanion tellurite through repression of acetate permease (actp). | the highly toxic oxyanion tellurite (teo(3) (2-)) enters the cells of the facultative photosynthetic bacterium rhodobacter capsulatus through an acetate permease. here we show that actp gene expression is down-regulated by fructose and this in turn determines a strong decrease of tellurite uptake and a parallel increase in the cells resistance to the toxic metalloid (from a minimal inhibitory concentration of 8-á++m up to 400-á++m tellurite under aerobic growth conditions). this demonstrates tha ... | 2011 | 21735076 |
| the effects of protein crowding in bacterial photosynthetic membranes on the flow of quinone redox species between the photochemical reaction center and the ubiquinol-cytochrome c(2) oxidoreductase. | atomic force microscopy (afm) of the native architecture of the intracytoplasmic membrane (icm) of a variety of species of purple photosynthetic bacteria, obtained at submolecular resolution, shows a tightly packed arrangement of light harvesting (lh) and reaction center (rc) complexes. since there are no unattributed structures or gaps with space sufficient for the cytochrome bc(1) or atpase complexes, they are localized in membrane domains distinct from the flat regions imaged by afm. this has ... | 2011 | 21691621 |
| directed assembly of functional light harvesting antenna complexes onto chemically patterned surfaces. | we report the directed assembly of the photosynthetic membrane proteins lh1 and lh2 isolated from the purple bacterium rhodobacter sphaeroides onto chemically patterned substrates. nanoimprint lithography was used to pattern discrete regions of amino--áand fluoro-terminated or poly(ethylene glycol) self-assembled monolayers onto a glass substrate. densely packed layers of assembled protein complexes were observed with atomic force microscopy. the protein complexes attached selectively to the ami ... | 2008 | 21817532 |
| glu-286 rotation and water wire reorientation are unlikely the gating elements for proton pumping in cytochrome c oxidase. | one of the key unresolved issues regarding proton pumping in cytochrome c oxidase (cco) is the identity of the gating element that prevents the backflow of protons. in this study, we analyze two popular proposals for this element: isomerization of the key branching residue (glu-286) and (re)orientation of water molecules in the hydrophobic cavity. using a multifaceted set of computational analyses that involve cco embedded in either an implicit or explicit treatment of lipid membrane, we show th ... | 2011 | 21723815 |
| damping of oscillations in the semiquinone absorption in reaction centers after successive flashes determination of the equilibrium between q(a) -q(b) and q(a)q(b-). | a quantitative model for the damping of oscillations of the semiquinone absorption after successive light flashes is presented. it is based on the equilibrium between the states q(a)-q(b) and q(a) q(-b). a fit of the model to the experimental results obtained for reaction centers from rhodopseudomonas sphaeroides gave a value of +¦ = [q(a)-q(b)i/(iq(a)-q(bl)+ [q(a)q(-b)i) = 0.065 +/- 0.005 (t= 21-¦c, ph 8). | 1984 | 21780326 |
| kinetic design of the respiratory oxidases. | energy conservation in all kingdoms of life involves electron transfer, through a number of membrane-bound proteins, associated with proton transfer across the membrane. in aerobic organisms, the last component of this electron-transfer chain is a respiratory heme-copper oxidase that catalyzes reduction of o(2) to h(2)o, linking this process to transmembrane proton pumping. so far, the molecular mechanism of proton pumping is not known for any system that is driven by electron transfer. here, we ... | 2011 | 21690359 |
| differential effects of glutamate-286 mutations in the aa(3)-type cytochrome c oxidase from rhodobacter sphaeroides and the cytochrome bo(3) ubiquinol oxidase from escherichia coli. | both the aa(3)-type cytochrome c oxidase from rhodobacter sphaeroides (rscco(aa3)) and the closely related bo(3)-type ubiquinol oxidase from escherichia coli (ecqo(bo3)) possess a proton-conducting d-channel that terminates at a glutamic acid, e286, which is critical for controlling proton transfer to the active site for oxygen chemistry and to a proton loading site for proton pumping. e286 mutations in each enzyme block proton flux and, therefore, inhibit oxidase function. in the current work, ... | 2011 | 21684251 |
| atp-dependent fructose uptake system in deinococcus radiodurans. | the bacterial phosphoenolpyruvate (pep)-dependent group translocation system (pts) requires the presence of both membrane-bound and cytoplasmic components to phosphorylate and translocate sugar. deinococcus radiodurans has a functional frua gene coding for the membrane-bound components of the fructose-specific pts. however, frub gene coding for the fructose-specific cytosolic components of pts is a pseudogene. yet, this bacterium metabolized fructose readily. in vitro studies showed that both ce ... | 2011 | 21822900 |
| testosterone-mineralizing culture enriched from swine manure: characterization of degradation pathways and microbial community composition. | environmental releases and fate of steroid sex hormones from livestock and wastewater treatment plants are of increasing regulatory concern. despite the detection of these hormones in manures, biosolids, and the environment, little attention has been paid to characterization of fecal bacteria capable of hormone degradation. the enrichments of (swine) manure-borne bacteria capable of aerobic testosterone degradation were prepared and the testosterone mineralization pathway was elucidated. six dna ... | 2011 | 21740029 |
| deep-uv resonance raman analysis of the rhodobacter capsulatus cytochrome bc1 complex reveals a potential marker for the transmembrane peptide backbone. | classical strategies for structure analysis of proteins interacting with a lipid phase typically correlate ensemble secondary structure content measurements with changes in the spectroscopic responses of localized aromatic residues or reporter molecules to map regional solvent environments. deep-uv resonance raman (duvrr) spectroscopy probes the vibrational modes of the peptide backbone itself, is very sensitive to the ensemble secondary structures of a protein, and has been shown to be sensitiv ... | 2011 | 21718040 |
| galls on the marine red alga prionitislanceolata (halymeniaceae): specific induction and subsequentdevelopment of an algal-bacterial symbiosis. | gall formation in prionitis lanceolata is associated with aspecific eubacterium (proteobacteria [alphasubclass], rhodobacter grouping), which, typical ofbacterial symbionts, has not yet been cultivated or isolated in pureculture. this investigation tested the hypothesis that p.lanceolata gall formation was caused by the associated eubacteriumusing a species-specific rdna probe (s-s-p.l.sym-0949-a-a-25) toidentify and assay for symbiont presence during consecutive laboratoryinduction trials. gall ... | 1998 | 21719414 |
| comparing the temperature dependence of photosynthetic electron transfer in chloroflexus aurantiacus and rhodobactor sphaeroides reaction centers. | the process of electron transfer from the special pair, p, to the primary electron donor, h(a), in quinone-depleted reaction centers (rcs) of chloroflexus (cf.) aurantiacu s has been investigated over the temperature range from 10 to 295 k using time-resolved pump-probe spectroscopic techniques. the kinetics of the electron transfer reaction, p* ôåæ p(+)h(a)(-), was found to be nonexponential, and the degree of nonexponentiality increased strongly as temperature decreased. the temperature-depend ... | 2011 | 21827152 |
| singlet oxygen stress in microorganisms. | singlet oxygen is the primary agent of photooxidative stress in microorganisms. in photosynthetic microorganisms, sensitized generation by pigments of the photosystems is the main source of singlet oxygen and, in nonphotosynthetic microorganisms, cellular cofactors such as flavins, rhodopsins, quinones, and porphyrins serve as photosensitizer. singlet oxygen rapidly reacts with a wide range of cellular macromolecules including proteins, lipids, dna, and rna, and thereby further reactive substanc ... | 2011 | 21722793 |
| nitrate-dependent degradation of acetone by alicycliphilus and paracoccus strains and comparison of acetone carboxylase enzymes. | a novel acetone-degrading, nitrate-reducing bacterium, strain kn bun08, was isolated from an enrichment culture with butanone and nitrate as the sole sources of carbon and energy. the cells were motile short rods, 0.5 to 1 by 1 to 2 μm in size, which gave gram-positive staining results in the exponential growth phase and gram-negative staining results in the stationary-growth phase. based on 16s rrna gene sequence analysis, the isolate was assigned to the genus alicycliphilus. besides butanone a ... | 2011 | 21841031 |
| adaptation of aerobic respiration to low o2 environments. | aerobic respiration in bacteria, archaea, and mitochondria is performed by oxygen reductase members of the heme-copper oxidoreductase superfamily. these enzymes are redox-driven proton pumps which conserve part of the free energy released from oxygen reduction to generate a proton motive force. the oxygen reductases can be divided into three main families based on evolutionary and structural analyses (a-, b- and c-families), with the b- and c-families evolving after the a-family. the a-family ut ... | 2011 | 21844375 |
| Role of PufX in Photochemical Charge Separation in the RC-LH1 Complex from Rhodobacter sphaeroides : An Ultrafast Mid-IR Pump-Probe Investigation. | Photochemical charge separation in isolated reaction center-light harvesting 1 (RC-LH1) complexes from Rhodobacter sphaeroides was examined using time-resolved mid-infrared pump-probe spectroscopy. Absorption difference spectra were recorded between 1760 and 1610 cm(-1) with subpicosecond time resolution to characterize excited-state and radical pair dynamics in these complexes, via the induced absorption changes in the keto carbonyl modes of the bacteriochlorophylls and bacteriopheophytins. E ... | 2011 | 22146012 |
| Fusing two cytochromes b of Rhodobacter capsulatus cytochrome bc1 using various linkers defines a set of protein templates for asymmetric mutagenesis. | Cytochrome bc(1) (mitochondrial complex III), one of the key enzymes of biological energy conversion, is a functional homodimer in which each monomer contains three catalytic subunits: cytochrome c(1), the iron-sulfur subunit and cytochrome b. The latter is composed of eight transmembrane a-helices which, in duplicate, form a hydrophobic core of a dimer. We show that two cytochromes b can be fused into one 16-helical subunit using a number of different peptide linkers that vary in length but all ... | 2012 | 22119789 |
| Bacterial nitrate assimilation: gene distribution and regulation. | In the context of the global nitrogen cycle, the importance of inorganic nitrate for the nutrition and growth of marine and freshwater autotrophic phytoplankton has long been recognized. In contrast, the utilization of nitrate by heterotrophic bacteria has historically received less attention because the primary role of these organisms has classically been considered to be the decomposition and mineralization of dissolved and particulate organic nitrogen. In the pre-genome sequence era, it was k ... | 2011 | 22103536 |
| Use of specific gene analysis to assess the effectiveness of surfactant-enhanced trichloroethylene cometabolism. | The objective of this study was to evaluate the effectiveness of in situ bioremediation of trichloroethylene (TCE)-contaminated groundwater using specific gene analyses under the following conditions: (1) pretreatment with biodegradable surfactants [Simple Green™ (SG) and soya lecithin (SL)] to enhance TCE desorption and dissolution, and (2) supplementation with SG, SL, and cane molasses as primary substrates to enhance the aerobic cometabolism of TCE. Polymerase chain reaction (PCR), denaturing ... | 2011 | 22071259 |
| Lipid binding to the carotenoid binding site in photosynthetic reaction centers. | Lipid binding to the carotenoid binding site near the inactive bacteriochlorophyll monomer was probed in the reaction centers of carotenoid-less mutant, R-26 from Rhodobacter sphaeroides. Recently, a marked light-induced change of the local dielectric constant in the vicinity of the inactive bacteriochlorophyll monomer was reported in wild type that was attributed to structural changes that ultimately lengthened the lifetime of the charge-separated state by 3 orders of magnitude (Deshmukh, S. S. ... | 2011 | 21894992 |
| role of a short lov protein in blue light- and singlet oxygen-dependent gene regulation in rhodobacter sphaeroides. | the facultatively photosynthetic bacterium rhodobacter sphaeroides harbors an unusual lov (light, oxygen, voltage) domain protein, rslov. while showing a characteristic photocycle, the protein misses a c-terminal output domain, similar to ppsb2 in pseudomonas putida. oxygen tension and light quantity are the two main responsible factors controlling the expression of photosynthesis genes in rhodobacter sphaeroides. two photoreceptor proteins are known to be involved in this regulation: the intens ... | 2011 | 22053008 |
| Efficient hydrogen production from acetate through isolated Rhodobacter sphaeroides. | Photosynthetic bacteria produce hydrogen from lactate and acetate that are products of hydrogen producing bacteria in the dark. Thus, their coculture is a promising method for hydrogen production. However, the hydrogen production yield from acetate of Rhodobacter sphaeroides RV, which has been shown to possess the highest yield and hydrogen production rate, is low as compared to that from lactate. Photosynthetic bacteria that produce hydrogen from acetate as well as lactate were screened from la ... | 2011 | 21903465 |
| proton transfer in ba(3) cytochrome c oxidase from thermus thermophilus. | the respiratory heme-copper oxidases catalyze reduction of o(2) to h(2)o, linking this process to transmembrane proton pumping. these oxidases have been classified according to the architecture, location and number of proton pathways. most structural and functional studies to date have been performed on the a-class oxidases, which includes those that are found in the inner mitochondrial membrane and bacteria such as rhodobacter sphaeroides and paracoccus denitrificans (aa(3)-type oxidases in the ... | 2011 | 22172736 |
| generation, characterization and crystallization of a cytochrome c(1)-subunit iv fused cytochrome bc(1) complex from rhodobacter sphaeroides. | cytochrome bc(1) complex catalyzes the reaction of electron transfer from ubiquinol to cytochrome c (or cytochrome c(2)) and couples this reaction to proton translocation across the membrane. crystallization of the rhodobacter sphaeroides bc(1) complex resulted in crystals containing only three core subunits. to mitigate the problem of subunit iv being dissociated from the three-subunit core complex during crystallization, we recently engineered an r. sphaeroides mutant in which the n-terminus o ... | 2012 | 22050933 |
| high-mobility group box-1 impairs memory in mice through both toll-like receptor 4 and receptor for advanced glycation end products. | high-mobility group box-1 (hmgb1) is a nuclear protein with cytokine-type functions upon its extracellular release. hmgb1 activates inflammatory pathways by stimulating multiple receptors, chiefly toll-like receptor 4 (tlr4) and receptor for advanced glycation end products (rage). tlr4 and rage activation has been implicated in memory impairments, although the endogenous ligand subserving these effects is unknown. we examined whether hmgb1 induced memory deficits using novel object recognition t ... | 2011 | 21884699 |
| cold adaptation of the mononuclear molybdoenzyme periplasmic nitrate reductase from the antarctic bacterium shewanella gelidimarina. | the reduction of nitrate to nitrite is catalysed in bacteria by periplasmic nitrate reductase (nap) which describes a system of variable protein subunits encoded by the nap operon. nitrate reduction occurs in the napa subunit, which contains a bis-molybdopterin guanine dinucleotide (mo-mgd) cofactor and one [4fe-4s] iron-sulfur cluster. the activity of periplasmic nitrate reductase (nap) isolated as native protein from the cold-adapted (psychrophilic) antarctic bacterium shewanella gelidimarina ... | 2011 | 22005463 |
| rhodobacter sphaeroides uses a reductive route via propionyl coenzyme a to assimilate 3-hydroxypropionate. | 3-hydroxypropionate is a product or intermediate of the carbon metabolism of organisms from all three domains of life. however, little is known about how carbon derived from 3-hydroxypropionate is assimilated by organisms that can utilize this c(3) compound as a carbon source. this work uses the model bacterium rhodobacter sphaeroides to begin to elucidate how 3-hydroxypropionate can be incorporated into cell constituents. to this end, a quantitative assay for 3-hydroxypropionate was developed b ... | 2012 | 22056933 |
| semi-continuous photo-fermentative h2 production by rhodobacter sphaeroides: effect of decanting volume ratio. | in this study, a semi-continuous operation of photo-fermentative h2-producing reactor was attempted at various decanting volume ratios (dvr, decanting volume per day/total working volume, %), ranging 30-70%, using rhodobacter sphaeroides kd131. h2 production was not efficient with showing low h2 yields of 0.2 and 0.5 mol h2/mol succinate(added) at 30% and 40% dvr, respectively. the low performance ascribed to the fact that over 70% of substrate electrons were diverted towards cell growth under t ... | 2012 | 22036913 |
| Coupling between Electron Transfer and Protein-Solvent Dynamics: FTIR and Laser-Flash Spectroscopy Studies in Photosynthetic Reaction Center Films at Different Hydration Levels. | We report on the relationship between electron transfer, conformational dynamics, and hydration in photosynthetic reaction centers (RCs) from Rhodobacter sphaeroides. The kinetics of electron transfer from the photoreduced quinone acceptor (Q(A)(-)) to the photo-oxidized primary donor (P(+)), a charge recombination process sensitive to the conformational dynamics of the RC, has been analyzed at room temperature in dehydrated RC-detergent films as a function of the residual water content under co ... | 2011 | 22017517 |
| heterologous high-level gene expression in the photosynthetic bacterium rhodobacter capsulatus. | the functional expression of heterologous genes in standard hosts such as escherichia coli is often hampered by various limitations including improper folding, incomplete targeting, and missassembly of the corresponding enzymes. this observation led to the development of numerous expression systems that are based on alternative, metabolic versatile hosts. one such organism is the gram-negative phototrophic nonsulfur purple bacterium rhodobacter capsulatus. during photosynthetic growth, r. capsul ... | 2012 | 22160903 |
| Defluviimonas denitrificans gen. nov., sp. nov., and Pararhodobacter aggregans gen. nov., sp. nov., non-phototrophic Rhodobacteraceae from the biofilter of a marine aquaculture. | Three Gram-negative bacterial strains were isolated from the biofilter of a recirculating marine aquaculture. They were non-pigmented rods, mesophiles, moderately halophilic, and showed chemo-organoheterotrophic growth on various sugars, fatty acids, and amino acids, with oxygen as electron acceptor; strains D9-3(T) and D11-58 were in addition able to denitrify. Phototrophic or fermentative growth could not be demonstrated. Phylogenetic analysis of the 16S rRNA gene sequences placed D9-3(T) and ... | 2011 | 21959289 |
| CcmI subunit of CcmFHI heme ligation complex functions as an apocytochrome c chaperone during c-type cytochrome maturation. | Cytochrome c maturation (Ccm) is a sophisticated post-translational process. It occurs after translocation of apocytochromes c to the p side of energy transducing membranes and forms stereo-specific thioether bonds between the vinyl groups of heme b (protoporphyrin IX-Fe) and the thiol groups of cysteines at their conserved heme binding sites. In many organisms this process involves up to 10 (CcmABCDEFGHI and CcdA) membrane proteins. One of these proteins is CcmI, which has an N-terminal membran ... | 2011 | 21956106 |
| X-ray structure of the dimeric cytochrome bc(1) complex from the soil bacterium Paracoccus denitrificans at 2.7-Å resolution. | The respiratory cytochrome bc(1) complex is a fundamental enzyme in biological energy conversion. It couples electron transfer from ubiquinol to cytochrome c with generation of proton motive force which fuels ATP synthesis. The complex from the a-proteobacterium Paracoccus denitrificans, a model for the medically relevant mitochondrial complexes, lacked structural characterization. We show by LILBID mass spectrometry that truncation of the organism-specific, acidic N-terminus of cytochrome c(1) ... | 2011 | 21996020 |
| Physiological roles for two periplasmic nitrate reductases in Rhodobacter sphaeroides 2.4.3 (ATCC 17025). | The metabolically versatile purple bacterium Rhodobacter sphaeroides 2.4.3 is a denitrifier whose genome contains two periplasmic nitrate reductase-encoding gene clusters. This work demonstrates nonredundant physiological roles for these two enzymes. One cluster is expressed aerobically and repressed under low oxygen while the second is maximally expressed under low oxygen. Insertional inactivation of the aerobically expressed nitrate reductase eliminated aerobic nitrate reduction, but cells of ... | 2011 | 21949073 |
| theoretical study of electron transfer in rhodobacter sphaeroides reaction center. | we investigate the substitution effects on electron transfer in rhodobacter (rb.) sphaeroides reaction center using ab initio calculations. the overlap of molecular orbitals in the x-ray structure of 1pcr of the protein data bank using gaussian09 can qualitatively explain the tendency of the experimental transition time. the charge effects of proteins on electron transfer in rb. sphaeroides reaction center are also investigated, by employing a simple point charge approximation for proteins. we h ... | 2011 | 21895666 |
| effects of mo(vi) on phototrophic hydrogen production by rhodobacter sphaeroides. | effects of mo(6+) concentration on phototrophic hydrogen production of rhodobacter sphaeroides were investigated using lactate as the sole carbon source. results showed that an increase of mo(6+) from nil to 1000 microg l(-1) led to increases in hydrogen yield, maximum production rate, conversion efficiency, biomass yield and lactate removal. at 100 microg-mo l(-1), the maximum rate was 12.0 ml h(-1) with a conversion efficiency of 36.1%, the cell yields were 1.11 g-cell g(-1) -lactate and 2.4 g ... | 2011 | 21970170 |
| role of protein dynamics in guiding electron-transfer pathways in reaction centers from rhodobacter sphaeroides. | the role of protein dynamics in guiding multistep electron transfer is explored in the photosynthetic reaction center of rhodobacter sphaeroides . the energetics of the charge-separated intermediates, p(+)b(a)(-) and p(+)h(a)(-) (p is the initial electron donor bacteriochlorophyll pair and b(a) and h(a) are early bacteriochlorophyll and bacteriopheophytin acceptors, respectively), were systematically varied in a series of mutants. a fast phase of p(+)h(a)(-) recombination was resolved that is v ... | 2011 | 22148392 |
| differential assembly of polypeptides of the light-harvesting 2 complex encoded by distinct operons during acclimation of rhodobacter sphaeroides to low light intensity. | in order to obtain an improved understanding of the assembly of the bacterial photosynthetic apparatus, we have conducted a proteomic analysis of pigment-protein complexes isolated from the purple bacterium rhodobacter sphaeroides undergoing acclimation to reduced incident light intensity. photoheterotrophically growing cells were shifted from 1,100 to 100 w/m(2) and intracytoplasmic membrane (icm) vesicles isolated over 24-h were subjected to clear native polyacrylamide gel electrophoresis. ban ... | 2011 | 21863386 |
| investigation of the redox interaction between mn-bicarbonate complexes and reaction centers from rhodobacter sphaeroides r-26, chromatium minutissimum, and chloroflexus aurantiacus. | the change in the dark reduction rate of photooxidized reaction centers (rc) of type ii from three anoxygenic bacteria (rhodobacter sphaeroides r-26, chromatium minutissimum, and chloroflexus aurantiacus) having different redox potentials of the p(+)/p pair and availability of rc for exogenous electron donors was investigated upon the addition of mn(2+) and hco(3)(-). it was found that the dark reduction of p(870)(+) from rb. sphaeroides r-26 is considerably accelerated upon the combined additio ... | 2011 | 22150281 |
| spinal tlr4 mediates the transition to a persistent mechanical hypersensitivity after the resolution of inflammation in serum-transferred arthritis. | persistent pain after resolution of clinically appreciable signs of arthritis poses a therapeutic challenge, and immunosuppressive therapies do not meet this medical need. to investigate this conversion to persistent pain, we utilized the k/bxn serum transfer arthritis model, which has persistent mechanical hypersensitivity despite the resolution of visible inflammation. toll-like receptor (tlr) 4 has been implicated as a potential therapeutic target in neuropathic and other pain models. we comp ... | 2011 | 22019135 |
| salt stress-induced changes in the transcriptome, compatible solutes, and membrane lipids in the facultatively phototrophic bacterium rhodobacter sphaeroides. | responses to nacl stress were investigated in phototrophically grown alphaproteobacterium rhodobacter sphaeroides by transcriptome profiling, mutational analysis, and measurements of compatible solutes and membrane phospholipids. after exposure to salt stress, genes encoding two putative glycine betaine uptake systems, provwx and bets, were highly upregulated. mutational analysis revealed that bets, not provwx, was the primary transporter of this compatible solute. upon the addition of salt, exo ... | 2011 | 21908636 |
| coherent phenomena of charge separation in reaction centers of ll131h and ll131h/lm160h/fm197h mutants of rhodobacter sphaeroides. | primary stage of charge separation and transfer of charges was studied in reaction centers (rcs) of point mutants ll131h and ll131h/lm160h/fm197h of the purple bacterium rhodobacter sphaeroides by differential absorption spectroscopy with temporal resolution of 18 fsec at 90 k. difference absorption spectra measured at 0-4 psec delays after excitation of dimer p at 870 nm with 30 fsec step were obtained in the spectral range of 935-1060 nm. it was found that a decay of p* due to charge separatio ... | 2011 | 22098236 |
| structure and function of the aaa+ protein cbbx, a red-type rubisco activase. | ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) catalyses the fixation of atmospheric co(2) in photosynthesis, but tends to form inactive complexes with its substrate ribulose 1,5-bisphosphate (rubp). in plants, rubisco is reactivated by the aaa(+) (atpases associated with various cellular activities) protein rubisco activase (rca), but no such protein is known for the rubisco of red algae. here we identify the protein cbbx as an activase of red-type rubisco. the 3.0-å crystal structur ... | 2011 | 22048315 |
| [in process citation]. | | 2011 | 22168003 |
| effects of stimulation of copper bioleaching on microbial community in vineyard soil and copper mining waste. | long-term copper application in vineyards and copper mining activities cause heavy metal pollution sites. such sites need remediation to protect soil and water quality. bioremediation of contaminated areas through bioleaching can help to remove copper ions from the contaminated soils. thus, the aim of this work was to evaluate the effects of different treatments for copper bioleaching in two diverse copper-contaminated soils (a 40-year-old vineyard and a copper mining waste) and to evaluate the ... | 2011 | 21947860 |
| in rhodobacter sphaeroides, chemotactic operon 1 regulates rotation of the flagellar system 2. | rhodobacter sphaeroides is able to assemble two different flagella, the subpolar flagellum (fla1) and the polar flagella (fla2). in this work, we report the swimming behavior of r. sphaeroides fla2(+) cells lacking each of the proteins encoded by chemotactic operon 1. a model proposing how these proteins control fla2 rotation is presented. | 2011 | 21949068 |
| two-dimensional spectroscopy can distinguish between decoherence and dephasing of zero-quantum coherences. | recent experiments on a variety of photosynthetic antenna systems have revealed that coherences among electronic states persist longer than previously anticipated. in an ensemble measurement, the observed dephasing of a coherent state can occur because of either disorder across the ensemble or decoherence from interactions with the bath. distinguishing how much such disorder affects the experimentally observed dephasing rate is paramount for understanding the role that quantum coherence may play ... | 2011 | 22191993 |
| slow dissociation of a charged ligand: analysis of the primary quinone q(a) site of photosynthetic bacterial reaction centers. | reaction centers (rcs) are integral membrane proteins that undergo a series of electron transfer reactions during the process of photosynthesis. in the q(a) site of rcs from rhodobacter sphaeroides, ubiquinone-10 is reduced, by a single electron transfer, to its semiquinone. the neutral quinone and anionic semiquinone have similar affinities, which is required for correct in situ reaction thermodynamics. a previous study showed that despite similar affinities, anionic quinones associate and diss ... | 2011 | 21863833 |
| mechanism of recombination of the p+h(a)- radical pair in mutant rhodobacter sphaeroides reaction centers with modified free energy gaps between p+b(a)- and p+h(a)-. | the kinetics of recombination of the p(+)h(a)(-) radical pair were compared in wild-type reaction centers from rhodobacter sphaeroides and in seven mutants in which the free energy gap, δg, between the charge separated states p(+)b(a)(-) and p(+)h(a)(-) was either increased or decreased. five of the mutant rcs had been described previously, and x-ray crystal structures of two newly constructed complexes were determined by x-ray crystallography. the charge recombination reaction was accelerated i ... | 2011 | 21970763 |
| Efficient electricity generation from sewage sludge usingbiocathode microbial fuel cell. | Microbial fuel cells (MFCs) with abiotic cathodes require expensive catalyst (such as Pt) or catholyte (such as hexacynoferrate) to facilitate oxidation reactions. This study incorporated biocathodes into a three-chamber MFC to yield electricity from sewage sludge at maximum power output of 13.2±1.7W/m(3) during polarization, much higher than those previously reported. After 15d operation, the total chemical oxygen demand (TCOD) removal and coulombic efficiency (CE) of cell reached 40.8±9.0% and ... | 2012 | 22078254 |
| effect of dietary rhodobacter capsulatus on lipid fractions and egg-yolk fatty acid composition in laying hens. | the present study was conducted to investigate the effect of dietary rhodobacter capsulatus on lipid fractions and egg-yolk fatty acid composition in laying hens. thirty-six laying hens (30 weeks old) were randomly assigned into two dietary groups fed diets with (0.04%) or without (control) r. capsulatus for a 60-day feeding trial. dietary r. capsulatus decreased (p < 0.05) serum and hepatic cholesterol and increased (p < 0.05) the excreta cholesterol, and resultant lower (p < 0.05) cholesterol ... | 2011 | 21929698 |
| the phytoplankton nannochloropsis oculata enhances the ability of roseobacter clade bacteria to inhibit the growth of fish pathogen vibrio anguillarum. | phytoplankton cultures are widely used in aquaculture for a variety of applications, especially as feed for fish larvae. phytoplankton cultures are usually grown in outdoor tanks using natural seawater and contain probiotic or potentially pathogenic bacteria. some roseobacter clade isolates suppress growth of the fish pathogen vibrio anguillarum. however, most published information concerns interactions between probiotic and pathogenic bacteria, and little information is available regarding the ... | 2011 | 22053210 |
| a new nitrilase-producing strain named rhodobacter sphaeroides lhs-305: biocatalytic characterization and substrate specificity. | the characteristics of the new nitrilase-producing strain rhodobacter sphaeroides lhs-305 were investigated. by investigating several parameters influencing nitrilase production, the specific cell activity was ultimately increased from 24.5 to 75.0 μmol g(-1) min(-1), and hereinto, the choice of inducer proved the most important factor. the aromatic nitriles (such as 3-cyanopyridine and benzonitrile) were found to be the most favorable substrates of the nitrilase by analyzing the substrate spect ... | 2011 | 21938420 |