| nosx function connects to nitrous oxide (n2o) reduction by affecting the cu(z) center of nosz and its activity in vivo. | the effect of loss of the 34-kda periplasmic nosx protein on the properties of n2o reductase was investigated with an n2o-respiration negative, double mutant of the paralogous genes nosx and nirx of paracoccus denitrificans. in spite of absence of whole-cell n2o-reducing activity, the purified reductase was catalytically active, which attributes nosx a physiological role in sustaining the reaction cycle. n2o reductase exhibited the spectroscopic features of cu(a) and the redox-inert, paramagneti ... | 2005 | 16087179 |
| energy coupling to nitrate uptake into the denitrifying cells of paracoccus denitrificans. | this study deals with the effects of the agents that dissipate the individual components of the proton motive force (short-chain fatty acids, nigericin, and valinomycin) upon the methyl viologen-coupled nitrate reductase activity in intact cells. substitution of butyrate or acetate for chloride in tris-buffered assay media resulted in a marked inhibition at ph 7. in a tris--chloride buffer of neutral ph, the reaction was almost fully inhibitable by nigericin. alkalinisation increased the ic(50) ... | 2005 | 16112075 |
| multifrequency epr analysis of the dimanganese cluster of the putative sulfate thiohydrolase soxb of paracoccus pantotrophus. | a detailed analysis of the epr signatures at x-band and q-band of an enzyme (soxb) involved in sulfur oxidation from paracoccus pantotrophus is presented. epr spectra are attributed to an exchange-coupled dimanganese mn(2)(ii,ii) complex. an antiferromagnetic exchange interaction of j=-7.0 (+/-1) cm(-1) (h=-2js ( 1 ) s ( 2 )) is evidenced by a careful examination of the temperature dependence of the epr spectra. the spin hamiltonian parameters for a total spin of s ( t ) =1, 2 and 3 are obtained ... | 2005 | 16133204 |
| inhibition of no3- and no2- reduction by microbial fe(iii) reduction: evidence of a reaction between no2- and cell surface-bound fe2+. | a recent study (d. c. cooper, f. w. picardal, a. schimmelmann, and a. j. coby, appl. environ. microbiol. 69:3517-3525, 2003) has shown that no(3)(-) and no(2)(-) (no(x)(-)) reduction by shewanella putrefaciens 200 is inhibited in the presence of goethite. the hypothetical mechanism offered to explain this finding involved the formation of a fe(iii) (hydr)oxide coating on the cell via the surface-catalyzed, abiotic reaction between fe(2+) and no(2)(-). this coating could then inhibit reduction of ... | 2005 | 16151113 |
| a structural model for the adduct between cytochrome c and cytochrome c oxidase. | an ensemble of structural models of the adduct between cytochrome c and cytochrome c oxidase from paracoccus denitrificans has been calculated based on the experimental data from site-directed mutagenesis and nmr experiments that have accumulated over the last years of research on this system. the residues from each protein that are at the protein-protein interface have been identified by the above experimental work, and this information has been converted in a series of restraints explicitly us ... | 2005 | 16151864 |
| cytochrome c oxidase as a calcium binding protein. studies on the role of a conserved aspartate in helices xi-xii cytoplasmic loop in cation binding. | the aa(3)-type cytochrome c oxidases from mitochondria and bacteria contain a cation-binding site located in subunit i near heme a. in the oxidases from paracoccus denitrificans or rhodobacter sphaeroides, the site is occupied by tightly bound calcium, whereas the mitochondrial oxidase binds reversibly calcium or sodium that compete with each other. the functional role of the site has not yet been established. d477a mutation in subunit i of p. denitrificans oxidase converts the cation-binding si ... | 2005 | 16156652 |
| titration behavior of residues at the entrance of the d-pathway of cytochrome c oxidase from paracoccus denitrificans investigated by continuum electrostatic calculations. | continuum electrostatic calculations were employed to investigate the titration curves of the fully oxidized state of wild type and several variants of cytochrome c oxidase from paracoccus denitrificans (n131d, n131c, n131v, and d124n) for different values of the dielectric constant of the protein. the effects of the mutations at the entrance of the d-proton transfer pathway were found to be quite localized to their immediate surroundings. the results can be well interpreted in the light of the ... | 2005 | 16192282 |
| pcr amplification from single dna molecules on magnetic beads in emulsion: application for high-throughput screening of transcription factor targets. | we have developed a novel method of genetic library construction on magnetic microbeads based on solid-phase single-molecule pcr in a fine and robust water-phase compartment formed in water-in-oil (w/o) emulsions. in this method, critically diluted dna fragments were distributed over the emulsion as templates, where beads crosslinked with multiple primers and other pcr components were encapsulated to form multiple reaction compartments. the delivered dna was then amplified and covalently immobil ... | 2005 | 16214800 |
| transcriptional regulation of nir and nor operons of paracoccus denitrificans. | transcripts of nitrite reductase (nir) and nitric oxide reductase (nor) operons of paracoccus denitrificans were expressed only under anaerobic conditions in the presence of potassium nitrite. the nir and nor operons produced at least two transcription products. large transcripts seemed to contain whole operons and small ones seemed to contain the genes encoding denitrifying enzymes. all transcription start sites were detected 41.5 or 42.5 bp downstream from the center of fnr boxes. | 2000 | 16232764 |
| development of chitosan-magnetite aggregates containing nitrosomonas europaea cells for nitrification enhancement. | a cell suspension of the nitrifying bacterium nitrosomonas europaea obtained after 96-h cultivation was subjected to magnetic separation using chitosan-conjugated magnetite particles (chitosan-magnetite), which have the ability to form aggregates with microbial cells. an equilibrium condition was obtained at room temperature after 30 min and over 90% of the cells were recovered when the chitosan-magnetite concentration was 200 mg/l. the relationship between the cell concentration in the supernat ... | 2000 | 16232771 |
| effect of oxygen concentration on nitrogen removal by nitrosomonas europaea and paracoccus denitrificans immobilized within tubular polymeric gel. | tubular gel reactors containing nitrosomonas europaea and paracoccus denitrificans, which remove nitrogen from solutions through a process of nitrification and denitrification, require oxygen for ammonia oxidation, the first and rate-limiting step in the process. to accelerate ammonia oxidation, high concentrations of oxygen were applied to the reactors instead of air. although a 50% o2:n2 gas mixture and pure oxygen were both toxic to free n. europaea cells, they actually accelerated ammonia ox ... | 2000 | 16232927 |
| asymmetric reduction of ethyl acetoacetate to ethyl (r)-3-hydroxybutyrate coupled with nitrate reduction by paracoccus denitrificans. | we found that the asymmetric reduction of ethyl acetoacetate (eaa) to ethyl (r)-3-hydroxybutyrate (ehb) by paracoccus denitrificans could be induced by nitrate addition under anaerobic conditions. however, the addition of electron donors such as glucose, ethanol, and methanol together with nitrate did not stimulate ehb production from eaa. when the reaction was carried out under optimum conditions (cell concentration, 10 g-d.w.l(-1); eaa, 150 mm; no3-, 100 mm), after 8 h of reaction 49 mm of ehb ... | 2001 | 16233006 |
| expression profiles of polyhydroxyalkanoate synthesis-related genes in paracoccus denitrificans. | a facultative methylotrophic bacterium, paracoccus denitrificans can synthesize polyhydroxyalkanoate acids (pha) from various alcohols. recently, six genes, phaa, b, c, p, r, and z, related to pha synthesis have been cloned and characterized. pha synthesis and the expression of phaa, b, c, p, r, and z in p. denitrificans were examined at the transcriptional and translational levels under both nitrogen-sufficient and nitrogen-deficient conditions. the results showed that pha synthesis is not regu ... | 2004 | 16233588 |
| formation of a cytochrome c-nitrous oxide reductase complex is obligatory for n2o reduction by paracoccus pantotrophus. | nitrous oxide reductase (n2or) catalyses the final step of bacterial denitrification, the two-electron reduction of nitrous oxide (n2o) to dinitrogen (n2). n2or contains two metal centers; a binuclear copper center, cua, that serves to receive electrons from soluble donors, and a tetranuclear copper-sulfide center, cuz, at the active site. stopped flow experiments at low ionic strengths reveal rapid electron transfer (kobs=150 s-1) between reduced horse heart (hh) cytochrome c and the cua center ... | 2005 | 16234931 |
| reductive activation of nitrate reductases. | protein film voltammetry of paracoccus pantotrophus respiratory nitrate reductase (nargh) and synechococcus elongatus assimilatory nitrate reductase (narb) shows that reductive activation of these enzymes may be required before steady state catalysis is observed. for nargh complementary spectroscopic studies suggest a structural context for the activation. catalytic protein film voltammetry at a range of temperatures has allowed quantitation of the activation energies for nitrate reduction. for ... | 2005 | 16234941 |
| analysis of the kinetics of the membrane potential generated by cytochrome c oxidase upon single electron injection. | in a recent work from this group (popovic, d. m.; stuchebrukhov a. a. febs lett. 2004, 566, 126), a model of proton pumping by cytochrome c oxidase (cco) was proposed. the key element of the model is his291 (bovine notation), a histidine ligand to enzyme's cub redox center, which plays the role of the pump element. the model assumes that upon electron transfer between heme a and the binuclear catalytic center of the enzyme, two sequential proton transfers occur: first, a proton from glu242 is tr ... | 2005 | 16242114 |
| gating of proton and water transfer in the respiratory enzyme cytochrome c oxidase. | the membrane-bound enzyme cytochrome c oxidase is responsible for cell respiration in aerobic organisms and conserves free energy from o2 reduction into an electrochemical proton gradient by coupling the redox reaction to proton-pumping across the membrane. o2 reduction produces water at the bimetallic heme a3/cub active site next to a hydrophobic cavity deep within the membrane. water molecules in this cavity have been suggested to play an important role in the proton-pumping mechanism. here, w ... | 2005 | 16014708 |
| introducing a novel human mtdna mutation into the paracoccus denitrificans cox i gene explains functional deficits in a patient. | we identified a novel mutation (s142f) in the human mtdna co i gene in a patient with a clinical phenotype resembling mitochondrial cardioencephalomyopathy. to substantiate pathogenicity, we modeled the identified mutation in the homologous gene in paracoccus denitrificans and analyzed the biochemical consequences. we observed a deleterious effect on enzyme activity, with a lack of heme a3. taking advantage of the extensive structural homology between the bacterial enzyme and the mammalian core ... | 2006 | 16284789 |
| the ligand geometry of copper determines the stability of amicyanin. | solution differential scanning calorimetry (dsc) of oxidized amicyanin, a type i copper protein, at ph 7.5 reveals two thermal transitions. the major transition at 67.7 degrees c corresponds to the disruption of the cys(92) thiolate to cu(ii) charge transfer as evidenced by a corresponding temperature-dependent loss of amicyanin visible absorbance. a minor transition at 75.5 degrees c describes the further irreversible protein unfolding. reduced amicyanin exhibits a ph-dependent change of the co ... | 2005 | 16289023 |
| isolation of pah-degrading bacteria from mangrove sediments and their biodegradation potential. | surface sediment samples were collected from seven mangrove swamps in hong kong sar with different degrees of contamination. the total concentrations of 16 pahs in these sediments ranged from 169.41 to 1058.37 ng g(-1) with the highest concentration found in ma wan and the lowest in kei ling ha lo wai mangrove swamp. in each swamp, three bacterial consortia were enriched from sediments using phenanthrene (phe) as the sole carbon and energy source, and individual bacterial colony showing phe degr ... | 2005 | 16291206 |
| is a third proton-conducting pathway operative in bacterial cytochrome c oxidase? | despite the existence of several three-dimensional structures of cytochrome c oxidases, a detailed understanding of pathways involved in proton movements through the complex remains largely elusive. next to the two well-established pathways (termed d and k), an additional proton-conducting network ('h-channel') has been proposed for the beef heart enzyme. yet, our recent mutational studies on corresponding residues of the paracoccus denitrificans cytochrome c oxidase provide no clues that such a ... | 2005 | 16042608 |
| regulation of the nap operon encoding the periplasmic nitrate reductase of paracoccus pantotrophus: delineation of dna sequences required for redox control. | expression of the nap operon, encoding the periplasmic nitrate reductase in paracoccus pantotrophus, is maximal when cells are grown aerobically, but not anaerobically, with butyrate. two promoters, termed p1 and p2, control operon expression and the operon-proximal p2 promoter is primarily responsible for increased nap expression in the presence of butyrate. a near-perfect palindromic sequence is centred at +7, relative to the p2 transcription start site. mutation of this palindrome demonstrate ... | 2006 | 16333617 |
| electron/proton coupling in bacterial nitric oxide reductase during reduction of oxygen. | the respiratory nitric oxide reductase (nor) from paracoccus denitrificans catalyzes the two-electron reduction of no to n(2)o (2no + 2h(+) + 2e(-) --> n(2)o + h(2)o), which is an obligatory step in the sequential reduction of nitrate to dinitrogen known as denitrification. nor has four redox-active cofactors, namely, two low-spin hemes c and b, one high-spin heme b(3), and a non-heme iron fe(b), and belongs to same superfamily as the oxygen-reducing heme-copper oxidases. nor can also use oxygen ... | 2005 | 16060680 |
| an elementary reaction step of the proton pump is revealed by mutation of tryptophan-164 to phenylalanine in cytochrome c oxidase from paracoccus denitrificans. | cytochrome c oxidase couples reduction of dioxygen to water to translocation of protons over the inner mitochondrial or bacterial membrane. a likely proton acceptor for pumped protons is the delta-propionate of heme a(3), which may receive the proton via water molecules from a conserved glutamic acid (e278 in subunit i of the paracoccus denitrificans enzyme) and which receives a hydrogen bond from a conserved tryptophan, w164. here, w164 was mutated to phenylalanine (w164f) to further explore th ... | 2005 | 16342941 |
| tryptophan tryptophylquinone cofactor biogenesis in the aromatic amine dehydrogenase of alcaligenes faecalis. cofactor assembly and catalytic properties of recombinant enzyme expressed in paracoccus denitrificans. | the heterologous expression of tryptophan trytophylquinone (ttq)-dependent aromatic amine dehydrogenase (aadh) has been achieved in paracoccus denitrificans. the aaubeda genes and orf-2 from the aromatic amine utilization (aau) gene cluster of alcaligenes faecalis were placed under the regulatory control of the mauf promoter from p. denitrificans and introduced into p. denitrificans using a broad-host-range vector. the physical, spectroscopic and kinetic properties of the recombinant aadh were i ... | 2005 | 16279953 |
| structure of the cytochrome complex soxxa of paracoccus pantotrophus, a heme enzyme initiating chemotrophic sulfur oxidation. | the sulfur-oxidizing enzyme system (sox) of the chemotroph paracoccus pantotrophus is composed of several proteins, which together oxidize hydrogen sulfide, sulfur, thiosulfate or sulfite and transfers the gained electrons to the respiratory chain. the hetero-dimeric cytochrome c complex soxxa functions as heme enzyme and links covalently the sulfur substrate to the thiol of the cysteine-138 residue of the soxy protein of the soxyz complex. here, we report the crystal structure of the c-type cyt ... | 2005 | 16297640 |
| synthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) from methanol and n-amyl alcohol by the methylotrophic bacteria paracoccus denitrificans and methylobacterium extorquens. | strains of two types of methylotrophic bacteria, paracoccus denitrificans and methylobacterium extorquens, synthesized the copolyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) when methanol and n-amyl alcohol were added together to nitrogen-limited medium. the composition of the copolyester differed considerably between the two strains: the copolyester from p. denitrificans was comparatively rich in 3-hydroxyvalerate (3hv). the 3hv content of the copolyester synthesized by this strain increa ... | 1992 | 16348804 |
| effect of medium composition on the denitrification of nitrate by paracoccus denitrificans. | the course of denitrification of nitrate in static cultures of paracoccus denitrificans was studied. reduction of nitrate to gaseous nitrogen without accumulation of nitrite because of parallel and balanced activities of nitrate and nitrite reductases was observed in nutrient broth. in minimal liquid cultures supplemented with either methanol, acetate, or ethanol as a sole carbon source, substantial amounts of nitrite (up to 70%) accumulated. the reduction in nitrite concentration began just aft ... | 1993 | 16349097 |
| mass spectrometric studies of the effect of ph on the accumulation of intermediates in denitrification by paracoccus denitrificans. | we have used a quadrupole mass spectrometer with a gas-permeable membrane inlet for continuous measurements of the production of n(2)o and n(2) from nitrate or nitrite by cell suspensions of paracoccus denitrificans. the use of nitrate and nitrite labeled with n was shown to simplify the interpretation of the results when these gases were measured. this approach was used to study the effect of ph on the production of denitrification intermediates from nitrate and nitrite under anoxic conditions. ... | 1994 | 16349183 |
| autotrophic, hydrogen-oxidizing, denitrifying bacteria in groundwater, potential agents for bioremediation of nitrate contamination. | addition of hydrogen or formate significantly enhanced the rate of consumption of nitrate in slurried core samples obtained from an active zone of denitrification in a nitrate-contaminated sand and gravel aquifer (cape cod, mass.). hydrogen uptake by the core material was immediate and rapid, with an apparent k(m) of 0.45 to 0.60 mum and a v(max) of 18.7 nmol cm h at 30 degrees c. nine strains of hydrogen-oxidizing denitrifying bacteria were subsequently isolated from the aquifer. eight of the s ... | 1994 | 16349284 |
| rates and equilibrium of cua to heme a electron transfer in paracoccus denitrificans cytochrome c oxidase. | intramolecular electron transfer between cua and heme a in solubilized bacterial (paracoccus denitrificans) cytochrome c oxidase was investigated by pulse radiolysis. cua, the initial electron acceptor, was reduced by 1-methylnicotinamide radicals in a diffusion-controlled reaction, as monitored by absorption changes at 825 nm, followed by partial restoration of the absorption and paralleled by an increase in the heme a absorption at 605 nm. the latter observations indicate partial reoxidation o ... | 2006 | 16387770 |
| activation and catalysis of the di-heme cytochrome c peroxidase from paracoccus pantotrophus. | bacterial cytochrome c peroxidases contain an electron transferring (e) heme domain and a peroxidatic (p) heme domain. all but one of these enzymes are isolated in an inactive oxidized state and require reduction of the e heme by a small redox donor protein in order to activate the p heme. here we present the structures of the inactive oxidized and active mixed valence enzyme from paracoccus pantotrophus. chain flexibility in the former, as expressed by the crystallographic temperature factors, ... | 2006 | 16407070 |
| structure-function correlation of outer membrane protein porin from paracoccus denitrificans. | porins from outer membrane of gram-negative bacteria have a highly stable structure. our previous studies on porin from paracoccus denitrificans showed that the outer membrane protein porin is extremely stable toward heat, ph, and chemical denaturants. the major question we have addressed in this paper is whether the high stability of porin is a consequence of the beta-barrel structure and whether it is required for its function. to explain this we have analyzed two cases: first, we used porin w ... | 2006 | 16345000 |
| specificity of fnr-type regulators in paracoccus denitrificans. | the three fnr (fumarate and nitrate reductase regulatory protein)-type transcription activators of paracoccus denitrificans, narr, nnrr and fnrp, appear to have specific tasks in gene regulation during the switch from aerobic growth to denitrification. we here set out a series of experiments to get a fundamental understanding of the mechanism underlying this specificity. in one of these, we changed the nucleotide sequence of an nnrr box, the binding site for nnrr, into one found in fnrp-regulate ... | 2006 | 16417491 |
| low-temperature kinetic measurements of microsecond freeze-hyperquench (mhq) cytochrome oxidase monitored by uv-visible spectroscopy with a newly designed cuvette. | a special cuvette was designed to measure optical changes of mhq (microsecond freeze-hyperquench) powder samples at temperatures below approx. 250 k. reduced cytochrome c oxidase from paracoccus denitrificans was reacted with o(2) for 100 micros, frozen as a powder and transferred to the cuvette. subsequently, cytochrome oxidase was allowed to react further following stepwise increments of the temperature from 100 k up to 250 k while recording spectra between 300 and 700 nm. the temperature was ... | 2006 | 16417503 |
| proton transfer in bacterial nitric oxide reductase. | the nor (nitric oxide reductase) from paracoccus denitrificans catalyses the two-electron reduction of no to n(2)o (2no+2h(+)+2e(-)-->n(2)o+h(2)o). the nor is a divergent member of the superfamily of haem-copper oxidases, oxygen-reducing enzymes which couple the reduction of oxygen with translocation of protons across the membrane. in contrast, reduction of no catalysed by nor is non-electrogenic which, since electrons are supplied from the periplasmic side of the membrane, implies that the prot ... | 2006 | 16417518 |
| cloning and characterization of the astaxanthin biosynthesis gene cluster from the marine bacterium paracoccus haeundaensis. | carotenoids are important natural pigments produced by many microorganisms and plants. in a previous study, we isolated and characterized a marine bacterium, paracoccus haeundaensis, which produces carotenoids, mainly astaxanthin. in the present study, a carotenoid biosynthesis gene cluster involved in the production of astaxanthin was isolated and characterized from this marine bacterium. the cluster contained six carotenogenic genes, five of which, with the same orientation, were designated cr ... | 2006 | 16434154 |
| sorption of cadmium by microorganisms in competition with other soil constituents. | the fate of cadmium in soil is influenced to a great extent by microbial activity. microorganisms were compared with abiotic soil components for their ability to sorb cd from a liquid medium. when the same amount (on a dry weight basis) of bacterial cells (serratia marcescens and paracoccus sp.), clay (montmorillonite), or sand was separately incubated in 0.05 m phosphate buffer, ph 7.2, containing 10 ppm of cd (10 mug/ml), bacterial cells removed the largest quantity of cd. dead cells sorbed mu ... | 1982 | 16346002 |
| isolation and analysis of the genes for cytochrome c oxidase in paracoccus denitrificans. | synthetic oligonucleotide probes were used to clone two loci from the chromosomal dna of paracoccus denitrificans that contain the genes for cytochrome c oxidase (cytochrome aa(3)). one locus seems to contain four or five genes probably forming an operon. two of these code for the oxidase subunits ii and iii. three open reading frames are found between the coii and coiii genes. the other locus codes for the subunit i. a short open reading frame is found upstream of this gene. all three subunits ... | 1987 | 16453796 |
| dissimilation of c3-sulfonates. | cysteate and sulfolactate are widespread natural products in the environment, while propanesulfonate, 3-aminopropanesulfonate and propane-1,3-disulfonate are xenobiotics. while some understanding of the bacterial assimilation of cysteate sulfur has been achieved, details of the dissimilation of cysteate and sulfolactate by microbes together with information on the degradation of the xenobiotics have only recently become available. this minireview centres on bacterial catabolism of the carbon moi ... | 2006 | 16341843 |
| assessing the impact of denitrifier-produced nitric oxide on other bacteria. | a series of experiments was undertaken to learn more about the impact on other bacteria of nitric oxide (no) produced during denitrification. the denitrifier rhodobacter sphaeroides 2.4.3 was chosen as a denitrifier for these experiments. to learn more about no production by this bacterium, no levels during denitrification were measured by using differential mass spectrometry. this revealed that no levels produced during nitrate respiration by this bacterium were in the low mum range. this conce ... | 2006 | 16517672 |
| growth-associated production of poly(3-hydroxyvalerate) from n-pentanol by a methylotrophic bacterium, paracoccus denitrificans. | paracoccus denitrificans accumulated a polyester in its cells during growth on n-pentanol. the composition of the polyester varied during the cultivation: the level of the 3-hydroxyvalerate unit in the polyester increased, and eventually a homopolymeric poly(3-hydroxyvalerate) [p(3hv)] accumulated to an amount 22 to 24% of the cell dry weight. growth-associated polyester synthesis was considerably affected by n-pentanol when its concentration was controlled at several levels. maximum accumulatio ... | 1996 | 16535226 |
| involvement of a putative [fe-s]-cluster-binding protein in the biogenesis of quinohemoprotein amine dehydrogenase. | quinohemoprotein amine dehydrogenase (qhndh) of paracoccus denitrificans contains a peptidyl quinone cofactor, cysteine tryptophylquinone, as well as intrapeptidyl thioether cross-links between cys and asp/glu residues within the smallestgamma-subunit of the alphabetagamma heterotrimeric protein. a putative [fe-s]-cluster-binding protein (orf2 protein) encoded between the structural genes for the alpha- and gamma-subunits of qhndh in the n-butylamine-utilizing operon likely belongs to a radical ... | 2006 | 16546999 |
| tracking the unfolding and refolding pathways of outer membrane protein porin from paracoccus denitrificans. | we have investigated outer membrane protein porin from paracoccus denitrificans for its stability against heat and ph. pathways of unfolding and refolding have been analyzed. porin incubated at ph 12.5 and above undergoes a slow unfolding into an unordered structure. the unfolded protein could be refolded into a nativelike structure that is functionally active but with distinct deviation from the native protein. this nativelike structure exhibited an entirely different thermal stability. althoug ... | 2006 | 16548524 |
| proton-coupled electron equilibrium in soluble and membrane-bound cytochrome c oxidase from paracoccus denitrificans. | the ph dependence of electron and proton re-equilibration upon co photolysis from two-electron-reduced aa3 oxidase was followed by time-resolved electrometry and optical spectroscopy. optical spectroscopy on soluble paracoccus denitrificans enzyme at alkaline ph revealed a slow (1 ms) component of electron re-equilibration coupled to the release of protons from the catalytic site. in the work [brändén, m., et al. (2003) biochemistry 42, 13178-13184], it was proposed that this proton is released ... | 2006 | 16548527 |
| soxv transfers electrons to the periplasm of paracoccus pantotrophus - an essential reaction for chemotrophic sulfur oxidation. | the soxvw genes are located upstream of the sox gene cluster encoding the sulfur-oxidizing ability of paracoccus pantotrophus. soxv is highly homologous to ccda, which is involved in cytochrome c maturation of p. pantotrophus. soxv was shown to function in reduction of the periplasmic soxw, which shows a cysxaaxaacys motif characteristic for thioredoxins. from strain gbomegav, which carries an omega-kanamycin-resistance-encoding interposon in soxv, and complementation analysis it was evident tha ... | 2006 | 16436434 |
| the role of tryptophan 272 in the paracoccus denitrificans cytochrome c oxidase. | the mechanism of electron coupled proton transfer in cytochrome c oxidase (cco) is still poorly understood. the p(m)-intermediate of the catalytic cycle is an oxoferryl state whose generation requires one additional electron, which cannot be provided by the two metal centres. the missing electron has been suggested to be donated to this binuclear site by a tyrosine residue. a tyrosine radical species has been detected in the p(m) and f* intermediates (formed by addition of h2o2) of the paraccocu ... | 2006 | 16460733 |
| performances and microbial features of an aerobic packed-bed biofilm reactor developed to post-treat an olive mill effluent from an anaerobic gac reactor. | olive mill wastewater (omw) is the aqueous effluent of olive oil producing processes. given its high cod and content of phenols, it has to be decontaminated before being discharged. anaerobic digestion is one of the most promising treatment process for such an effluent, as it combines high decontamination efficiency with methane production. the large scale anaerobic digestion of omws is normally conducted in dispersed-growth reactors, where however are generally achieved unsatisfactory cod remov ... | 2006 | 16595023 |
| evidence for redox cooperativity between c-type hemes of maug which is likely coupled to oxygen activation during tryptophan tryptophylquinone biosynthesis. | maug is a novel 42 kda diheme protein which is required for the biosynthesis of tryptophan tryptophylquinone, the prosthetic group of methylamine dehydrogenase. the visible absorption and resonance raman spectroscopic properties of each of the two c-type hemes and the overall redox properties of maug are described. the absorption maxima for the soret peaks of the oxidized and reduced hemes are 403 and 418 nm for the low-spin heme and 389 and 427 nm for the high-spin heme, respectively. the reson ... | 2006 | 16411758 |
| characterization of bacterial beta-carotene 3,3'-hydroxylases, crtz, and p450 in astaxanthin biosynthetic pathway and adonirubin production by gene combination in escherichia coli. | beta-carotene hydroxylase (crtz) is one of rate-limiting enzymes for astaxanthin production. a complementation analysis was conducted using escherichia coli transformants to compare the catalytic efficiency of bacterial crtz from brevundimonas sp. sd212, paracoccus sp. pc1 (formerly known as alcaligenes sp. pc-1), paracoccus sp. n81106 (agrobacterium aurantiacum), pantoea ananatis (erwinia uredovora 20d3), marine bacterium p99-3, and p450 monooxygenase (cyp175a1) from thermus thermophilus hb27. ... | 2006 | 16614859 |
| transcription factor nnr from paracoccus denitrificans is a sensor of both nitric oxide and oxygen: isolation of nnr* alleles encoding effector-independent proteins and evidence for a haem-based sensing mechanism. | the nitrite reductase and nitric oxide reductase regulator (nnr) from paracoccus denitrificans activates transcription in response to nitric oxide (no). the mechanism of no sensing has not been elucidated for nnr, or for any of its orthologues from the fnr/crp family of transcriptional regulators. using regulated expression of the nnr gene in escherichia coli, evidence has now been obtained to indicate that activation of nnr by no does not require de novo synthesis of the nnr polypeptide. in ana ... | 2006 | 16622062 |
| the flavoprotein soxf functions in chemotrophic thiosulfate oxidation of paracoccus pantotrophus in vivo and in vitro. | paracoccus pantotrophus strain gbsoxfdelta carries a deletion in the soxf gene that inactivates flavoprotein soxf-sulfide dehydrogenase. this strain grew with thiosulfate slower than the wild type. gbsoxfdelta cells oxidized thiosulfate at a rate of 40% and hydrogen sulfide at a rate of 45% of the wild type. complementation of gbsoxfdelta with plasmid prisoxf carrying the soxf gene increased these rates to 83% and 70%, respectively. however, gbsoxfdelta and gbsoxfdelta (prisoxf) oxidized thiosul ... | 2006 | 16630266 |
| the sulfonated osmolyte n-methyltaurine is dissimilated by alcaligenes faecalis and by paracoccus versutus with release of methylamine. | selective enrichments yielded bacterial cultures able to utilize the osmolyte n-methyltaurine as sole source of carbon and energy or as sole source of fixed nitrogen for aerobic growth. strain mt1, which degraded n-methyltaurine as a sole source of carbon concomitantly with growth, was identified as a strain of alcaligenes faecalis. stoichiometric amounts of methylamine, whose identity was confirmed by matrix-assisted, laser-desorption ionization time-of-flight mass spectrometry, and of sulfate ... | 2006 | 16549680 |
| oxidation of c-type cytochromes by the membrane-bound cytochrome oxidase (cytochrome aa(3)) of blue-green algae. | respiratory particles containing an aa(3)-type cytochrome oxidase were prepared from anacystis nidulans, synechocystis 6714, synechococcus lividus, anabaena variabilis, nostoc sp. strain mac, nostoc muscorum, and mastigocladus laminosus. oxidation of c-type cytochromes by membrane preparations of the different blue-green algae was observed using purified cytochromes from horse heart, candida krusei, tuna, saccharomyces oviformis, rhodospirillum rubrum, rhodospirillum molischianum, rhodopseudomon ... | 1982 | 16662253 |
| nitrate-dependent [fe(ii)edta]2- oxidation by paracoccus ferrooxidans sp. nov., isolated from a denitrifying bioreactor. | enrichments with [fe(ii)edta]2- as electron donor and nitrate or nitrite as electron acceptor were established using an inoculum from a bioreactor performing denitrification. a nitrate-reducing, [fe(ii)edta]2- oxidizing strain was isolated and named strain bdn-1. the g + c content of strain bdn-1 was 67%, and the organism was closely affiliated to paracoccus denitrificans, p. pantotrophus and p. versutus by 16s rrna sequence comparison. results from dna-dna hybridization, rep-pcr, and whole cell ... | 2006 | 16682296 |
| electron transfer among the cua-, heme b- and a3-centers of thermus thermophilus cytochrome ba3. | the 1-methyl-nicotinamide radical (mna(*)), produced by pulse radiolysis has previously been shown to reduce the cu(a)-site of cytochromes aa(3), a process followed by intramolecular electron transfer (et) to the heme a but not to the heme a(3) [farver, o., grell, e., ludwig, b., michel, h. and pecht, i. (2006) rates and equilibrium of cua to heme a electron transfer in paracoccus denitrificans cytochrome c oxidase. biophys. j. 90, 2131-2137]. investigating this process in the cytochrome ba(3) o ... | 2006 | 16712843 |
| effect of electromagnetic fields on the denitrification activity of paracoccus denitrificans. | enzymatic activity (denitrification) of paracoccus denitrificans was estimated electrochemically by reduction of duroquinone (dq). graphite electrodes covered with whole bacterial cells behind a dialysis membrane were used for measurement. p. denitrificans reduce nitrate and/or nitrite under anaerobic conditions to nitrogen gas. dq acts as an electron mediator. after donation of the electrons to the respiratory system of the bacteria, produced dq is reduced to durohydroquinone on the electrode s ... | 2007 | 16713381 |
| requirement of medium adp for the steady-state hydrolysis of atp by the proton-translocating paracoccus denitrificans fo.f1-atp synthase. | fo.f1-atp synthase in inside-out coupled vesicles derived from paracoccus denitrificans catalyzes pi-dependent proton-translocating atpase reaction if exposed to prior energization that relieves adp.mg2+ -induced inhibition (zharova, t.v. and vinogradov, a.d. (2004) j. biol. chem.,279, 12319-12324). here we present evidence that the presence of medium adp is required for the steady-state energetically self-sustained coupled atp hydrolysis. the initial rapid atpase activity is declined to a certa ... | 2006 | 16730637 |
| proton-coupled electron transfer drives the proton pump of cytochrome c oxidase. | electron transfer in cell respiration is coupled to proton translocation across mitochondrial and bacterial membranes, which is a primary event of biological energy transduction. the resulting electrochemical proton gradient is used to power energy-requiring reactions, such as atp synthesis. cytochrome c oxidase is a key component of the respiratory chain, which harnesses dioxygen as a sink for electrons and links o2 reduction to proton pumping. electrons from cytochrome c are transferred sequen ... | 2006 | 16598262 |
| in vitro selection of dna binding sites for transcription factor, phar, from paracoccus denitrificans using genetic library on microbeads and flow cytometry. | we attempted the selection of a site for dna binding to a transcription factor, phar, from paracoccus denitrificans expressed by cell-free protein synthesis, from a random oligonucleotide library on microbeads that was constructed by the emulsion pcr technique. phar is a repressor protein in p. denitrificans that binds to the phap promoter region. we acquired three types of phar-binding dna fragment using this system. the selected fragments contained a perfect phar binding consensus site (tgc i) ... | 2006 | 16781475 |
| functional expression of the astaxanthin biosynthesis genes from a marine bacterium, paracoccus haeundaensis. | the astaxanthin biosynthesis gene cluster in paracoccus haeundaensis consists of six genes: crtw, crtz, crty, crti, crtb, and crte contain 726, 486, 1158, 1503, 912, and 879 base pairs, respectively. individual carotenoid biosynthesis genes of p. haeundaensis have now been expressed in e. coli and each gene product has been purified to homogeneity. their molecular characteristics, including enzymatic activities, are reported here. | 2006 | 16799760 |
| identification of a transposable genomic island of paracoccus pantotrophus dsm 11072 by its transposition to a novel entrapment vector pmmb2. | a novel shuttle entrapment vector, pmmb2, was used to identify a large transposable element, tnppa1 (44.3 kb), of paracoccus pantotrophus dsm 11072. tnppa1 has a composite structure with divergently oriented copies of a cryptic transposon, tn3434 (tn3 family), located at both termini. the core region of the element contains a large set of putative genes, whose products show similarity to enzymes involved in central intermediary metabolism (e.g. tricarboxylic acid cycle or 2-methylcitrate cycle), ... | 2006 | 16549670 |
| rubellimicrobium thermophilum gen. nov., sp. nov., a red-pigmented, moderately thermophilic bacterium isolated from coloured slime deposits in paper machines. | six red-pigmented strains of the alphaproteobacteria with optimal growth between 45 and 54 degrees c were previously isolated from coloured biofilms in two fine-paper machines and one pulp dryer. the strains were found to be resistant to 15 p.p.m. 2,2-dibromo-3-nitrilopropionamide, a common industrial biocide. 16s rna gene sequence similarity of the isolates was 99.7-100 %. ribotyping using the restriction enzymes pvuii and ecori showed that four of the isolates (c-lvk-r2a-1, c-lvk-r2a-2(t), c-r ... | 2006 | 16738114 |
| elementary steps of proton translocation in the catalytic cycle of cytochrome oxidase. | proton translocation in the catalytic cycle of cytochrome c oxidase (cco) proceeds sequentially in a four-stroke manner. every electron donated by cytochrome c drives the enzyme from one of four relatively stable intermediates to another, and each of these transitions is coupled to proton translocation across the membrane, and to uptake of another proton for production of water in the catalytic site. using cytochrome c oxidase from paracoccus denitrificans we have studied the kinetics of electro ... | 2006 | 16829227 |
| fluorescence-based siderophore biosensor for the determination of bioavailable iron in oceanic waters. | with direct evidence that iron is the chemical limitation of phytoplankton growth, particularly in the southern ocean, it is increasingly important to develop new tools that provide direct measurement of the bioavailable iron fraction in oceanic waters. here we report the development of a fluorescence quenching-based siderophore biosensor capable of the in situ measurement of this ultratrace fe(iii) fraction at ambient ph ( approximately 8). parabactin was extracted from cultures of paracoccus d ... | 2006 | 16841927 |
| redox titration of all electron carriers of cytochrome c oxidase by fourier transform infrared spectroscopy. | electrochemical redox titrations of cytochrome c oxidase from paraccocus denitrificans were performed by attenuated total reflectance fourier transform infrared (atr-ftir) spectroscopy. the majority of the differential infrared absorption features may be divided into four groups, which correlate with the redox transitions of the four redox centers of the enzyme. infrared spectroscopy has the advantage of allowing one to measure independent alterations in redox centers, which are not well separat ... | 2006 | 16634645 |
| performance of a reactor containing denitrifying immobilized biomass in removing ethanol and aromatic hydrocarbons (btex) in a short operating period. | a horizontal-flow anaerobic immobilized biomass reactor (haib) containing denitrifying biomass was evaluated with respect to its ability to remove, separately and in a short operating period (30 days), organic matter, nitrate, and the hydrocarbons benzene (41.4 mg l-1), toluene (27.8 mg l-1), ethylbenzene (31.1 mg l-1), o-xylene (28.5 mg l-1), m-xylene (28.4 mg l-1) and p-xylene (32.1 mg l-1). the purified culture, which was grown in the presence of the specific hydrocarbon, was used as the sour ... | 2007 | 16872740 |
| a cytochrome cd1-type nitrite reductase isolated from the marine denitrifier pseudomonas nautica 617: purification and characterization. | nitrite reductase (cytochrome cd1) was purified to electrophoretic homogeneity from the soluble extract of the marine denitrifying bacterium pseudomonas nautica strain 617. cells were anaerobically grown with 10 mm nitrate as final electron acceptor. the soluble fraction was purified by four successive chromatographic steps and the purest cytochrome cd1 exhibited an a280 nm(oxidized)/a410nm(oxidized) coefficient of 0.90. in the course of purification, cytochrome cd1 specific activity presented a ... | 1995 | 16887530 |
| the melas mutations 3946 and 3949 perturb the critical structure in a conserved loop of the nd1 subunit of mitochondrial complex i. | the nd1 subunit gene of the mitochondrial nadh-ubiquinone oxidoreductase (complex i) is a hot spot for mutations causing leber hereditary optic neuropathy and several mutations causing the mitochondrial encephalopathy, lactic acidosis and stroke-like episodes syndrome (melas). we have used escherichia coli and paracoccus denitrificans as model systems to study the effect of mutations 3946 and 3949, which change conserved residues in nd1 and cause melas. the vicinity of these mutations was also e ... | 2006 | 16849371 |
| effect of ph, temperature and substrate on n2o, no and co2 production by alcaligenes faecalis p. | to study the effect of ph, temperature and substrate on the magnitude of n(2)o and no production by heterotrophic nitrifiers. | 2006 | 16907816 |
| structural and chemical changes of the p(m) intermediate of paracoccus denitrificans cytochrome c oxidase revealed by ir spectroscopy with labeled tyrosines and histidine. | structural and chemical changes in the p(m) intermediate of paracoccus denitrificans cytochrome c oxidase have been investigated by attenuated total reflection-fourier transform infrared spectroscopy. prior studies of p(m) minus oxidized (o) ir difference spectra of unlabeled, universally (15)n-labeled and ring-d(4)-tyrosine-labeled proteins (iwaki, m., puustinen, a., wikström, m., and rich, p. r. (2004) biochemistry 43, 14370-14378). provided a basis for band assignments to changes in metal cen ... | 2006 | 16953573 |
| mutational and functional analysis of the beta-carotene ketolase involved in the production of canthaxanthin and astaxanthin. | biosynthesis of the commercial carotenoids canthaxanthin and astaxanthin requires beta-carotene ketolase. the functional importance of the conserved amino acid residues of this enzyme from paracoccus sp. strain n81106 (formerly classified as agrobacterium aurantiacum) was analyzed by alanine-scanning mutagenesis. mutations in the three highly conserved histidine motifs involved in iron coordination abolished its ability to catalyze the formation of ketocarotenoids. this supports the hypothesis t ... | 2006 | 16957201 |
| a new assay for nitric oxide reductase reveals two conserved glutamate residues form the entrance to a proton-conducting channel in the bacterial enzyme. | a specific amperometric assay was developed for the membrane-bound nor [no (nitric oxide) reductase] from the model denitrifying bacterium paracoccus denitrificans using its natural electron donor, pseudoazurin, as a co-substrate. the method allows the rapid and specific assay of no reduction catalysed by recombinant nor expressed in the cytoplasmic membranes of escherichia coli. the effect on enzyme activity of substituting alanine, aspartate or glutamine for two highly conserved glutamate resi ... | 2007 | 16961460 |
| site-directed mutagenesis of proline 52 to glycine in amicyanin converts a true electron transfer reaction into one that is conformationally gated. | amicyanin is a type i copper protein that is the natural electron acceptor for the quinoprotein methylamine dehydrogenase (madh). the conversion of proline52 of amicyanin to a glycine does not alter the physical and spectroscopic properties of the copper binding site, but it does alter the rate of electron transfer (et) from madh. the values of electronic coupling (h(ab)) and reorganization energy (lambda) that are associated with the true et reaction from the reduced o-quinol tryptophan tryptop ... | 2006 | 16819827 |
| isolation and characterization of a denitrifying monocrotophos-degrading paracoccus sp. m-1. | a bacterium strain, which is capable of degrading monocrotophos, was isolated from sludge collected from the bottom of a wastewater treatment system of a chemical factory, and named m-1. on the basis of the results of the cellular morphology, physiological and chemotaxonomic characteristics and phylogenetic similarity of 16s rdna gene sequences, the strain was identified as a paracoccus sp. the ability of the strain to mineralize monocrotophos was investigated under different culture conditions. ... | 2006 | 16978350 |
| the rieske protein from paracoccus denitrificans is inserted into the cytoplasmic membrane by the twin-arginine translocase. | the rieske [2fe-2s] protein (isp) is an essential subunit of cytochrome bc(1) complexes in mitochondrial and bacterial respiratory chains. based on the presence of two consecutive arginines, it was argued that the isp of paracoccus denitrificans, a gram-negative soil bacterium, is inserted into the cytoplasmic membrane via the twin-arginine translocation (tat) pathway. here, we provide experimental evidence that membrane integration of the bacterial isp indeed relies on the tat translocon. we sh ... | 2006 | 16987314 |
| thiosulphate oxidation in the phototrophic sulphur bacterium allochromatium vinosum. | two different pathways for thiosulphate oxidation are present in the purple sulphur bacterium allochromatium vinosum: oxidation to tetrathionate and complete oxidation to sulphate with obligatory formation of sulphur globules as intermediates. the tetrathionate:sulphate ratio is strongly ph-dependent with tetrathionate formation being preferred under acidic conditions. thiosulphate dehydrogenase, a constitutively expressed monomeric 30 kda c-type cytochrome with a ph optimum at ph 4.2 catalyses ... | 2006 | 16995898 |
| paracoccus homiensis sp. nov., isolated from a sea-sand sample. | strain dd-r11(t), isolated from a sea-sand sample from homi cape, pohang city, south korea, was a gram-negative, aerobic, motile, non-spore-forming, rod- to ovoid-shaped bacterium. colonies grown on marine agar were circular, convex and colourless to creamy white. growth occurred between 10 and 40 degrees c (optimum 25-30 degrees c) and at ph 5.0-9.0 (optimum ph 6.0-8.0). the strain could grow in up to 15 % nacl (optimum 3-5 % nacl). according to 16s rrna gene sequence analysis, the strain was a ... | 2006 | 17012567 |
| redefining paracoccus denitrificans and paracoccus pantotrophus and the case for a reassessment of the strains held by international culture collections. | an outline of the current taxonomic diversity of the genus paracoccus is presented. a definitive summary is given of the valid type strains of paracoccus denitrificans and paracoccus pantotrophus and of culture collection strains that can be assigned to these species. the case is established for a critical reassessment of the p. denitrificans strains held by international culture collections, to ensure that they are assigned to the correct species. | 2006 | 17012585 |
| inhibitory effects of sulfamic acid on three thiosulfate-oxidizing chemolithotrophs. | sulfamate is an analogue of thiosulfate, and the sodium and potassium salts of sulfamic acid inhibited the chemolithoautotrophic growth on thiosulfate of acidithiobacillus ferrooxidans and halothiobacillus neapolitanus. the chemo-organotrophic growth of paracoccus versutus on sucrose was similarly inhibited by sulfamate. thiosulfate oxidation by suspensions of h. neapolitanus was, however, unaffected by sulfamate, showing that sulfamate did not directly affect thiosulfate uptake, activation or o ... | 2006 | 17020550 |
| respiratory transformation of nitrous oxide (n2o) to dinitrogen by bacteria and archaea. | n2o is a potent greenhouse gas and stratospheric reactant that has been steadily on the rise since the beginning of industrialization. it is an obligatory inorganic metabolite of denitrifying bacteria, and some production of n2o is also found in nitrifying and methanotrophic bacteria. we focus this review on the respiratory aspect of n2o transformation catalysed by the multicopper enzyme nitrous oxide reductase (n2or) that provides the bacterial cell with an electron sink for anaerobic growth. t ... | 2007 | 17027372 |
| paracoccus bengalensis sp. nov., a novel sulfur-oxidizing chemolithoautotroph from the rhizospheric soil of an indian tropical leguminous plant. | paracoccus versutus-like isolates from the rhizosphere of clitoria ternatea, a slender leguminous herb (family--papilionaceae), found ubiquitously in waste places and village forests of the lower gangetic plains of india, presented a case of graduated infraspecific variation that was capped by the identification of a new species paracoccus bengalensis (type strain jjj(t) = lmg 22700(t) = mtcc 7003(t)). the diverged phenetic and genetic structure of these sulfur-oxidizing chemolithoautotrophs pre ... | 2006 | 16824961 |
| probing the unusual oxidation/reduction behavior of paracoccus pantotrophus cytochrome cd1 nitrite reductase by replacing a switchable methionine heme iron ligand with histidine. | a m106h variant, where m106 is a c-type heme iron axial ligand, of cytochrome cd(1) nitrite reductase is an inactive protein in vivo. expression of the holoprotein in paracoccus pantotrophus required generation of nitric oxide during cell growth through simultaneous expression of an exogenous copper nitrite reductase from alcaligenes faecalis. in the absence of the latter protein, only a semi-apo form of m106h cytochrome cd(1) was formed. thus it was demonstrated that expression of the chromosom ... | 2006 | 16964982 |
| identification of acetate- or methanol-assimilating bacteria under nitrate-reducing conditions by stable-isotope probing. | stable-isotope probing (sip) was used to identify acetate- or methanol-assimilating bacteria under nitrate-reducing conditions in activated sludge. a sludge sample obtained from wastewater treatment systems was incubated in a denitrifying batch reactor fed with synthetic wastewater containing [(13)c]acetate or [(13)c]methanol as the main carbon source and nitrate as the electron acceptor. we analyzed how growth of bacterial populations was stimulated by acetate or methanol as the external carbon ... | 2006 | 16897304 |
| autoregulator protein phar for biosynthesis of polyhydroxybutyrate [p(3hb)] possibly has two separate domains that bind to the target dna and p(3hb): functional mapping of amino acid residues responsible for dna binding. | phar from paracoccus denitrificans functions as a repressor or autoregulator of the expression of genes encoding phasin protein (phap) and phar itself, both of which are components of polyhydroxyalkanoate (pha) granules (a. maehara, s. taguchi, t. nishiyama, t. yamane, and y. doi, j. bacteriol. 184:3992-4002, 2002). phar is a unique regulatory protein in that it also has the ability to bind tightly to an effector molecule, pha polyester. in this study, by using a quartz crystal microbalance, we ... | 2007 | 17122335 |
| astaxanthin formation in the marine photosynthetic bacterium rhodovulum sulfidophilum expressing crti, crty, crtw and crtz. | this study reports the production of astaxanthin in the photosynthetic bacterium rhodovulum sulfidophilum, which has adequate precursor pools and storage capabilities for heterologous carotenoid production. chemical mutagenesis was carried out using ethylmethane sulfonate to produce mutants with a modified carotenoid biosynthesis pathway downstream of phytoene. stable green- and gray-colored mutants were selected. green mutants contained neurosporene or chloroxanthin as their major carotenoid (> ... | 2006 | 17107420 |
| conformation of the c552:aa3 electron transfer complex in paracoccus denitrificans studied by epr on oriented samples. | the epr spectral parameters of aa(3) oxidase and cyt c(552) from paracoccus denitrificans were studied in purified oxidase and enriched cyt c(552). the orientation of the g-tensors of hemes a and c(552) were determined on partially ordered membranes, enriched cyt c(552) and a c(552):aa(3) subcomplex. the known correlation of g-tensor to molecular axes in histidine/methionine ligated hemes permits us to position cyt c(552) with respect to the parent membrane. taken together with previous data on ... | 2006 | 17052714 |
| paracoccus sulfuroxidans sp. nov., a sulfur oxidizer from activated sludge. | bacterial strain lw36t was isolated from activated sludge of a wastewater-treatment bioreactor. cells of strain lw36t were gram-negative coccoids to short rods, 1.0-1.2x0.5 microm in size. colonies were cream-coloured, smooth and circular. strain lw36t was hetero-organotrophic and chemolithotrophic and was able to use reduced sulfur as an energy resource. growth was observed at 25-36 degrees c and ph 5-10. the most abundant cellular fatty acid of strain lw36t was c18:1omega7c (64.2%). the sole r ... | 2006 | 17082413 |
| energy-linked binding of pi is required for continuous steady-state proton-translocating atp hydrolysis catalyzed by f0.f1 atp synthase. | the presence of medium pi (half-maximal concentration of 20 microm at ph 8.0) was found to be required for the prevention of the rapid decline in the rate of proton-motive force (pmf)-induced atp hydrolysis by fo.f1 atp synthase in coupled vesicles derived from paracoccus denitrificans. the initial rate of the reaction was independent of pi. the apparent affinity of pi for its "atpase-protecting" site was strongly decreased with partial uncoupling of the vesicles. pi did not reactivate atpase wh ... | 2006 | 17128994 |
| the sxt conjugative element and linear prophage n15 encode toxin-antitoxin-stabilizing systems homologous to the tad-ata module of the paracoccus aminophilus plasmid pami2. | a group of proteic toxin-antitoxin (ta) cassettes whose representatives are widely distributed among bacterial genomes has been identified. these cassettes occur in chromosomes, plasmids, bacteriophages, and noncomposite transposons, as well as in the sxt conjugative element of vibrio cholerae. the following four homologous loci were subjected to detailed comparative studies: (i) tad-ata from plasmid pami2 of paracoccus aminophilus (the prototype of this group), (ii) gp49-gp48 from the linear ba ... | 2007 | 17158670 |
| interference of chlorate and chlorite with nitrate reduction in resting cells of paracoccus denitrificans. | when grown anaerobically on a succinate+nitrate (sn) medium, paracoccus denitrificans forms the membrane-bound, cytoplasmically oriented, chlorate-reducing nitrate reductase nar, while the periplasmic enzyme nap is expressed during aerobic growth on butyrate+oxygen (bo) medium. preincubation of sn cells with chlorate produced a concentration-dependent decrease in nitrate utilization, which could be ascribed to nar inactivation. toluenization rendered nar less sensitive to chlorate, but more sens ... | 2006 | 17159204 |
| isolation of the epsilon-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene resin. | epsilon-caprolactam has high cod and toxicity, so its discharge to natural water and soil systems may lead to an adverse environmental effect on water quality, endangering public health and welfare. this investigation attempts to isolate epsilon-caprolactam denitrifying bacteria from a wastewater treatment system manufactured with acrylonitrile-butadiene-styrene (abs) resin. the goal is to elucidate the effectiveness of isolated pure strain and abs mixed strains in treating epsilon-caprolactam f ... | 2007 | 17161908 |
| effect of carbon substrate on electron acceptor diauxic lag and anoxic maximum specific growth rate in species with and without periplasmic enzyme. | the effect of oxidation state of carbon substrate on the diauxic lag of facultative anaerobic denitrifying bacteria growing aerobically upon switching to anoxic growth was studied. also studied was the effect on the anoxic maximum specific growth rate. two pure bacteria cultures were used, paracoccus pantotrophus, denitrifying bacteria containing a periplasmic nitrate reductase (nap), and pseudomonas denitrificans, denitrifying bacteria lacking the periplasmic nitrate reductase. the anoxic maxim ... | 2007 | 17129955 |
| culturable and vbnc vibrio cholerae: interactions with chironomid egg masses and their bacterial population. | vibrio cholerae, the etiologic agent of cholera, is autochthonous to various aquatic environments. recently, it was found that chironomid (nonbiting midges) egg masses serve as a reservoir for the cholera bacterium and that flying chironomid adults are possible windborne carriers of v. cholerae non-o1 non-o139. chironomids are the most widely distributed insect in freshwater. females deposit egg masses at the water's edge, and each egg mass contains eggs embedded in a gelatinous matrix. hemagglu ... | 2007 | 17186156 |
| major carotenoid isolated from paracoccus schoinia nbrc 100637t is adonixanthin diglucoside. | the structure of a novel major carotenoid glycoside (nearly 80% of total carotenoids) from a newly isolated bacterium, paracoccus schoinia nbrc 100637t, was determined to be adonixanthin diglucoside using spectral data. by contrast, carotenoid diglycosides are rare and are usually minor carotenoids in nature. the minor carotenoids in this bacterium included astaxanthin diglucoside, zeaxanthin diglucoside, canthaxanthin, echinenone, zeaxanthin, beta-cryptoxanthin, and beta-carotene. | 2006 | 17190471 |
| spectropotentiometric and structural analysis of the periplasmic nitrate reductase from escherichia coli. | the escherichia coli napa (periplasmic nitrate reductase) contains a [4fe-4s] cluster and a mo-bis-molybdopterin guanine dinucleotide cofactor. the napa holoenzyme associates with a di-heme c-type cytochrome redox partner (napb). these proteins have been purified and studied by spectropotentiometry, and the structure of napa has been determined. in contrast to the well characterized heterodimeric napab systems ofalpha-proteobacteria, such as rhodobacter sphaeroides and paracoccus pantotrophus, t ... | 2007 | 17130127 |
| growth yields in bacterial denitrification and nitrate ammonification. | denitrification and nitrate ammonification are considered the highest-energy-yielding respiration systems in anoxic environments after oxygen has been consumed. the corresponding free energy changes are 7 and 35% lower than that of aerobic respiration, respectively. growth yield determinations with pure cultures of paracoccus denitrificans and pseudomonas stutzeri revealed that far less energy is converted via atp into cell mass than expected from the above calculations. denitrification with for ... | 2007 | 17209072 |
| tracking x-ray-derived redox changes in crystals of a methylamine dehydrogenase/amicyanin complex using single-crystal uv/vis microspectrophotometry. | x-ray exposure during crystallographic data collection can result in unintended redox changes in proteins containing functionally important redox centers. in order to directly monitor x-ray-derived redox changes in trapped oxidative half-reaction intermediates of paracoccus denitrificans methylamine dehydrogenase, a commercially available single-crystal uv/vis microspectrophotometer was installed on-line at the biocars beamline 14-bm-c at the advanced photon source, argonne, usa. monitoring the ... | 2007 | 17211075 |
| molecular dissection of diheme cytochrome c gene from soil isolate of a gram negative, facultative chemolithotrophic sulfur oxidizer. | a gram negative chemolithotrophic bacterium (rpi) with facultative mode of nutrition was isolated from the soil. enzymological studies confirmed presence of thiosulphate oxidase, sulphite oxidase and rhodanese, all of which play role in sulfur metabolism pathway. a set of degenerate oligonucleotide primer pairs was used for thermal amplification of a major part of the coding region of the cytochrome c gene locus of this bacterium. nucleotide and translated amino acid sequence revealed the gene t ... | 2004 | 17240791 |
| bacteria associated with orchid roots and microbial production of auxin. | associative bacteria of terrestrial (paphiopedilum appletonianum) and epiphytic (pholidota articulata) tropical orchids were investigated. microbial community of epiphytic plant differed from that of the terrestrial one. streptomyces, bacillus, pseudomonas, burkholderia, erwinia and nocardia strains populated paphiopedilum roots, whereas pseudomonas, flavobacterium, stenotrophomonas, pantoea, chryseobacterium, bacillus, agrobacterium, erwinia, burkholderia and paracoccus strains colonized pholid ... | 2007 | 17140781 |