Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
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| the rhodanese rhda helps azotobacter vinelandii in maintaining cellular redox balance. | the tandem domain rhodanese-homology protein rhda of azotobacter vinelandii shows an active-site loop structure that confers structural peculiarity in the environment of its catalytic cysteine residue. the in vivo effects of the lack of rhda were investigated using an a. vinelandii mutant strain (mv474) in which the rhda gene was disrupted by deletion. here, by combining analytical measurements and transcript profiles, we show that deletion of the rhda gene generates an oxidative stress conditio ... | 2010 | 20482308 |
| indole-3-acetic acid (iaa) production in symbiotic and non-symbiotic nitrogen-fixing bacteria and its optimization by taguchi design. | production of indole-3-acetic acid (iaa) in 35 different symbiotic and non-symbiotic nitrogen-fixing bacteria strains isolated from soil and plant roots was studied and assayed by chromatography and colorimetric methods. these bacteria included agrobacterium, paenibacillus, rhizobium, klebsiella oxytoca, and azotobacter. the best general medium and synergism effects of isolates for iaa production were investigated. effects of different variables containing physical parameters and key media compo ... | 2010 | 20526603 |
| fatty acids in an estuarine mangrove ecosystem. | fatty acids have been successfully used to trace the transfer of organic matter in coastal and estuarine food webs. to delineate these web connections, fatty acid profiles were analyzed in species of microbes (azotobacter vinelandii, and lactobacillus xylosus), prawns (metapenaeus monoceros and macrobrachium rosenbergii) and finfish (mugil cephalus), that are associated with decomposing leaves of two mangrove species, rhizophora apiculata and avicennia marina. the fatty acids, except long chain ... | 2010 | 20527460 |
| gain-of-function mutations cluster in distinct regions associated with the signalling pathway in the pas domain of the aerotaxis receptor, aer. | the aer receptor monitors internal energy (redox) levels in escherichia coli with an fad-containing pas domain. here, we randomly mutagenized the region encoding residues 14-119 of the pas domain and found 72 aerotaxis-defective mutants, 24 of which were gain-of-function, signal-on mutants. the mutations were mapped onto an aer homology model based on the structure of the pas-fad domain in nifl from azotobacter vinlandii. signal-on lesions clustered in the fad binding pocket, the beta-scaffoldin ... | 2010 | 20545849 |
| use of protein trans-splicing to produce active and segmentally (2)h, (15)n labeled mannuronan c5-epimerase alge4. | alginate epimerases are large multidomain proteins capable of epimerising c5 on beta-d-mannuronic acid (m) turning it into alpha-l-guluronic acid (g) in a polymeric alginate. azotobacter vinelandii secretes a family of seven epimerases, each of which is capable of producing alginates with characteristic g distribution patterns. all seven epimerases consist of two types of modules, denoted a and r, in varying numbers. attempts to study these enzymes with solution-state nmr are hampered by their s ... | 2010 | 20552686 |
| [biosynthesis of poly-3-hydroxybutyrate-3-hydroxyvalerate copolymer by azotobacter chroococcum strain 7b]. | the ability of azotobacter chroococcum strain 7b, producer of polyhydroxybutyrate (phb), to synthesize its copolymer poly-3-hydroxybutyrate-3-hydroxyvalerate (phb-hv) was studied. it was demonstrated, for the first time, that a. chroococcum strain 7b was able to synthesize phb-hv with various molar rates of hv in the polymer chain when cultivated on medium with sucrose and carboxylic acids as precursors of hv elements in the phb chain, namely, valeric (13.1-21.6 mol %), propanoic (3.1 mol %), an ... | 2010 | 20586284 |
| manipulating the molecular weight of alginate produced by azotobacter vinelandii in continuous cultures. | alginate production by azotobacter vinelandii in chemostat cultures was evaluated at different dilution rates (d) and inlet sucrose concentrations of 5 and 20 g l(-1). at the low inlet sucrose concentration, the molecular weight of alginate increased from 800 to 1800 kda when d increased from 0.05 to 0.10 h(-1), whereas the opposite trend was observed with the high inlet sucrose concentration. this behaviour can be explained by changes in specific sucrose uptake rate. thus, a decrease in alginat ... | 2010 | 20675122 |
| high-level expression and reconstitution of active cfr, a radical-sam rrna methyltransferase that confers resistance to ribosome-acting antibiotics. | cfr is a radical-sam (s-adenosyl-l-methionine) enzyme that methylates the 8 position of 23s rrna residue a2503 to confer resistance to multiple antibiotic classes acting upon the large subunit of the bacterial ribosome. radical-sam enzymes use an fe-s cluster to generate the 5'-deoxyadenosyl (doa) radical from sam, enabling them to modify intrinsically unreactive centres such as adenosine c8. however, despite its mechanistic interest and clinical relevance, until recently cfr remained little cha ... | 2010 | 20678576 |
| artificial tripartite symbiosis involving a green alga (chlamydomonas), a bacterium (azotobacter) and a fungus (alternaria): morphological and physiological characterization. | a long-living artificial tripartite symbiosis involving a green alga (chlamydomonas), a bacterium (azotobacter) and a fungus (alternaria) was established on carbon- and nitrogen-free medium. the basis of the interdependence is the complementation of photosynthetic co2 assimilation and atmospheric nitrogen fixation. green color of the colonies indicated that the algal cells had enough nitrogen to synthesize chlorophylls. the chlorophyll content was nearly 40% of the control cells. the relatively ... | 2010 | 20680580 |
| doubly sensitivity-enhanced 3d tocsy-hsqc. | recently, strategies for double sensitivity enhancement in heteronuclear three-dimensional nmr experiments were introduced (krishnamurthy, v.v. (1995) j. magn. reson., b106, 170-177; sattler et al. (1995) j. biomol. nmr, 6, 11-22; sattler et al. (1995) j. magn. reson., b108, 235-242). since a sensitivity enhancement of a factor 2(1/2) can be achieved for each indirect dimension, nd spectra can theoretically be enhanced up to a factor of 2(((n-1)/2)). we propose and analyze a doubly enhanced thre ... | 1996 | 20686884 |
| vanadium nitrogenase reduces co. | vanadium nitrogenase not only reduces dinitrogen to ammonia but also reduces carbon monoxide to ethylene, ethane, and propane. the parallelism between the two reactions suggests a potential link in mechanism and evolution between the carbon and nitrogen cycles on earth. | 2010 | 20689010 |
| nmr assignments of 1h, 13c and 15n resonances of the c-terminal subunit from azotobacter vinelandii mannuronan c5-epimerase 6 (alge6r3). | the 19.9 kda c-terminal module (r3) from azotobacter vinelandii mannronan c5-epimerase alge6 has been (13)c, (15)n isotopically labelled and recombinantly expressed. we report here the (1)h, (13)c, (15)n resonance assignment of alge6r3. | 2011 | 20711760 |
| characterization of isolated nitrogenase fevco. | the cofactors of the mo- and v-nitrogenases (i.e., femoco and fevco) are homologous metal centers with distinct catalytic properties. so far, there has been only one report on the isolation of fevco from azotobacter chroococcum. however, this isolated fevco species did not carry the full substrate-reducing capacity, as it is unable to restore the n(2)-reducing ability of the cofactor-deficient mofe protein. here, we report the isolation and characterization of a fully active species of fevco fro ... | 2010 | 20718463 |
| studies on characterization of bioflocculant exopolysaccharide of azotobacter indicus and its potential for wastewater treatment. | partially characterized bioflocculant exopolysaccharide (eps) produced from an azotobacter indicus atcc 9540 strain reported in our previous study was further characterized, and its flocculant potential was investigated at different ph, temperature, and cations concentrations. flocculant activity at different concentrations of eps in the absence of cations was reanalyzed by slight modified flocculant assay. it revealed that flocculant activity increased in a concentration-dependent manner up to ... | 2011 | 20730607 |
| quantification of nitrogen reductase and nitrite reductase genes in soil of thinned and clear-cut douglas-fir stands by using real-time pcr. | the abundance of nifh, nirs, and nirk gene fragments involved in nitrogen (n) fixation and denitrification in thinned second-growth douglas-fir (pseudotsuga menziesii subsp. menziesii [mirb.] franco) forest soil was investigated by using quantitative real-time pcr. prokaryotic n cycling is an important aspect of n availability in forest soil. the abundance of universal nifh, azotobacter sp.-specific nifh (nifh-g1), nirs, and nirk gene fragments in unthinned control and 30, 90, and 100% thinning ... | 2010 | 20802070 |
| proteome analysis of azotobacter vinelandii ∆arrf mutant that overproduces poly-β-hydroxybutyrate polymer. | azotobacter vinelandii arrf is an iron-responsive small rna that is under negative control of ferric uptake regulator protein. a. vinelandii ∆arrf mutant that had a deletion of the entire arrf gene was known to overproduce poly-β-hydroxybutyrate (phb). proteins differentially expressed in the mutant were identified by gel-based proteomics and confirmed by real-time rt-pcr. 6-phosphogluconolactonase and e(1) component of pyruvate dehydrogenase complex, which leads to the production of nadph and a ... | 2010 | 20803137 |
| effect of yeast extract on the growth and respiration of azotobacter chroococcum. | 1945 | 20985081 | |
| [not available]. | 1946 | 20991707 | |
| symbiosis between myxobacteria and nitrifying bacteria. | 1946 | 20991726 | |
| [chemical aspect of the fixation of nitrogen by azotobacter; influence of surface active substances.]. | 1945 | 21001000 | |
| [the nitrifying bacteria and myxobacteria]. | 1945 | 21001004 | |
| effect of molybdenum on nitrogen fixation by clostridium butyricum. | 1946 | 21001937 | |
| a study of the effect of growth substrate on the respiration of azotobacter. | 1946 | 21010885 | |
| intensity of fixation of atmospheric nitrogen by azotobacter on different sources of carbon. | 1945 | 21026754 | |
| exploring novel non-leloir β-glucosyltransferases from proteobacteria for modifying linear (β1->3)-linked gluco-oligosaccharide chains. | over the years several β-glucan transferases from yeast and fungi have been reported, but enzymes with such an activity from bacteria have not been characterized so far. in this work, we describe the cloning and expression of genes encoding β-glucosyltransferase domains of glycosyl hydrolase family gh17 from three species of proteobacteria: pseudomonas aeruginosa pao1, p. putida kt2440 and azotobacter vinelandii atcc baa-1303. the encoded enzymes of these gh17 domains turned out to have a non-le ... | 2010 | 21030539 |
| enhancement of wood waste decomposition by microbial inoculation prior to vermicomposting. | to investigate the feasibility of microbial pre-decomposition of timber wastes to quality production of vermicompost with higher agronomic value, timber wastes were inoculated with different combinations of the fungi phanerochete chrysosporium, trichoderma reesei, aspergillus niger and the bacteria azotobacter chroococcum (mtcc 3853) and bacillus cereus (mtcc 4079) and incubated at 28-30 °c in a mechanical composter. the inoculation enhanced the degradation of timber wastes, increased total nitr ... | 2010 | 21036037 |
| variable-temperature, variable-field magnetic circular dichroism spectroscopic study of nifen-bound precursor and "femoco". | nifen plays a key role in the biosynthesis of the iron-molybdenum cofactor (femoco) of nitrogenase. a scaffold protein that hosts the conversion of a femoco precursor to a mature cofactor, nifen can assume three conformations during the process of femoco maturation. one, designated δnifb nifen, contains only two permanent [fe(4)s(4)]-like clusters. the second, designated nifen(precursor), contains the permanent clusters and a precursor form of femoco. the third, designated nifen("femoco"), conta ... | 2010 | 21038112 |
| cloning, characterization and transcriptional analysis of two phosphate acetyltransferase isoforms from azotobacter vinelandii. | acetate is abundant in soil contributing to a great extent on carbon cycling in nature. phosphate acetyltransferase (pta, ec 2.3.1.8) catalyzes the reversible transfer of the acetyl group from acetyl-p to coa forming acetyl-coa and inorganic phosphate, participating to acetate assimilation/dissimilation reactions. in the present study, we demonstrate that azotobacter vinelandii, a nitrogen-fixing, free-living, soil bacterium, possesses two class ii phosphate acetyltransferase isoforms, avpta-1 a ... | 2010 | 21104132 |
| [influence of natural minerals on growth of azotobacter vinelandii imv b-7076]. | it was shown that the cultivation of azotobacter vinelandii imv b-7076 in the presence of natural minerals significantly increased the growth of bacteria activity. adding in the medium glauconite and saponite in optimal concentration (10 g/l) conditioned the increase of cell growth six and four times compared with control, accordingly. the maximum stimulating effect was observed when the concentration of phosphates was 5.0 g/l, herewith the number of viable cells increased 5 times. the presence ... | 2010 | 21117294 |
| a sterile alpha-motif domain in nafy targets apo-nifdk for iron-molybdenum cofactor delivery via a tethered domain. | nafy participates in the final steps of nitrogenase maturation, having a dual role as iron-molybdenum cofactor (femo-co) carrier and as chaperone to the femo-co-deficient apo-nifdk (apo-dinitrogenase). nafy contains an n-terminal domain of unknown function (n-nafy) and a c-terminal domain (core-nafy) necessary for femo-co binding. we show here that n-nafy and core-nafy have very weak interactions in intact nafy. the nmr structure of n-nafy reveals that it belongs to the sterile α-motif (sam) fam ... | 2010 | 21156797 |
| (1)h, (13)c and (15)n resonances of the alge62 subunit from azotobacter vinelandii mannuronan c5-epimerase. | the 17.7 kda r2 module from azotobacter vinelandii mannronan c5-epimerase alge6 has been isotopically labeled ((13)c,(15)n) and recombinantly expressed. here we report the (1)h, (13)c, (15)n resonance assignment of alge6r2. | 2010 | 21188559 |
| cloning, expression, purification, crystallization and preliminary crystallographic analysis of nifh2 from methanocaldococcus jannaschii. | nitrogenases are protein complexes that are only found in azotobacter and are required for biological nitrogen fixation. they are made up of a nitrogenase, which is a nifd2/nifk2 heterotetramer, and a nitrogenase reductase, which is a homodimer of nifh. many homologues of nitrogenase have been found in various non-nitrogen-fixing prokaryotes; in particular, they are found in all known methanogens. this indicates that these homologues may play a role in methane production. here, the cloning of ni ... | 2010 | 21206044 |
| unraveling the molecular mechanisms of nitrogenase conformational protection against oxygen in diazotrophic bacteria. | g. diazotrophicus and a. vinelandii are aerobic nitrogen-fixing bacteria. although oxygen is essential for the survival of these organisms, it irreversibly inhibits nitrogenase, the complex responsible for nitrogen fixation. both microorganisms deal with this paradox through compensatory mechanisms. in a. vinelandii a conformational protection mechanism occurs through the interaction between the nitrogenase complex and the fesii protein. previous studies suggested the existence of a similar syst ... | 2010 | 21210973 |
| structure of precursor-bound nifen: a nitrogenase femo cofactor maturase/insertase. | nifen plays an essential role in the biosynthesis of the nitrogenase iron-molybdenum (femo) cofactor (m cluster). it is an α(2)β(2) tetramer that is homologous to the catalytic molybdenum-iron (mofe) protein (nifdk) component of nitrogenase. nifen serves as a scaffold for the conversion of an iron-only precursor to a matured form of the m cluster before delivering the latter to its target location within nifdk. here, we present the structure of the precursor-bound nifen of azotobacter vinelandii ... | 2011 | 21212358 |
| nifb and nifen protein levels are regulated by clpx2 under nitrogen fixation conditions in azotobacter vinelandii. | the major part of biological nitrogen fixation is catalysed by the molybdenum nitrogenase that carries at its active site the iron and molybdenum cofactor (femo-co). the nitrogen fixation (nif) genes required for the biosynthesis of femo-co are derepressed in the absence of a source of fixed nitrogen. the nifb gene product is remarkable because it assembles nifb-co, a complex cluster proposed to comprise a [6fe-9s-x] cluster, from simpler [fe-s] clusters common to other metabolic pathways. nifb- ... | 2011 | 21231969 |
| transgenic expression of glucose dehydrogenase in azotobacter vinelandii enhances mineral phosphate solubilization and growth of sorghum seedlings. | the enzyme quinoprotein glucose dehydrogenase (gdh) catalyses the oxidation of glucose to gluconic acid by direct oxidation in the periplasmic space of several gram-negative bacteria. acidification of the external environment with the release of gluconic acid contributes to the solubilization of the inorganic phosphate by biofertilizer strains of the phosphate-solubilizing bacteria. glucose dehydrogenase (gcd) gene from escherichia coli, and azotobacter-specific glutamine synthetase (glna) and p ... | 2009 | 21255283 |
| redox driven metabolic tuning: carbon source and aeration affect synthesis of poly(3-hydroxybutyrate) in escherichia coli. | growth and polymer synthesis were studied in a recombinant e. coli strain carrying phabac and phap of azotobacter sp. strain fa8 using different carbon sources and oxygen availability conditions. the results obtained with glucose or glycerol were completely different, demonstrating that the metabolic routes leading to the synthesis of the polymer when using glycerol do not respond to environmental conditions such as oxygen availability in the same way as they do when other substrates, such as gl ... | 2010 | 21327064 |
| a new phenol oxidase produced during melanogenesis and encystment stage in the nitrogen-fixing soil bacterium azotobacter chroococcum. | laccases are copper-containing phenol oxidases that are commonly found in many types of plant, insect, fungi and bacteria. whilst phenol oxidases have been well characterized in fungal species, laccase-type enzymes originating from bacteria have been much less well defined. bacteria belonging to the family azotobacteraceae share many morphological characteristics with strains already known to exhibit polyphenol and phenol oxidase activity; and hence the aim of this work was to identify and chara ... | 2011 | 21327414 |
| co-ordination and fine-tuning of nitrogen fixation in azotobacter vinelandii. | nitrogen fixation by the free-living organism azotobacter vinelandii can occur through the activity of three different systems that are genetically distinct but mechanistically related. a combination of bioinformatic and biochemical-genetic studies has revealed that at least 82 different genes are likely to be associated with the formation and regulation of these systems. studies performed over many years have established that cross-talk occurs between the various nitrogen fixation systems, and ... | 2011 | 21338415 |
| oxygen transfer rate during the production of alginate by azotobacter vinelandii under oxygen-limited and non oxygen-limited conditions. | the oxygen transfer rate (otr) and dissolved oxygen tension (dot) play an important role in determining alginate production and its composition; however, no systematic study has been reported about the independent influence of the otr and dot. in this paper, we report a study about alginate production and the evolution of the molecular mass of the polymer produced by a wild-type a. vinelandii strain atcc 9046, in terms of the maximum oxygen transfer rate (otrmax) in cultures where the dissolved ... | 2011 | 21352581 |
| essential metals for nitrogen fixation in a free-living nôéé-fixing bacterium: chelation, homeostasis and high use efficiency. | biological nitrogen fixation, the main source of new nitrogen to the earth's ecosystems, is catalysed by the enzyme nitrogenase. there are three nitrogenase isoenzymes: the mo-nitrogenase, the v-nitrogenase and the fe-only nitrogenase. all three types require iron, and two of them also require mo or v. metal bioavailability has been shown to limit nitrogen fixation in natural and managed ecosystems. here, we report the results of a study on the metal (mo, v, fe) requirements of azotobacter vinel ... | 2011 | 21392197 |
| removal of arsenic from aqueous solution using pottery granules coated with cyst of azotobacter and portland cement: characterization, kinetics and modeling. | a new low cost adsorbents, pottery granules coated with cyst of azotobacter and portland cement has been developed for aqueous arsenic removal. the developed granule is solid and porous structure forms a stable complex of fe-al-si-o(2) allied with cyst biomass. batch experiments were revealed that as removal was up to 96% using pgac beads, whereas 65% by cyst biomass. immobilization of cyst biomass to pottery granules through portland cement improved the stability of granules and adsorption capa ... | 2011 | 21392969 |
| a general approach for detecting folding intermediates from steady-state and time-resolved fluorescence of single-tryptophan-containing proteins. | during denaturant-induced equilibrium (un)folding of wild-type apoflavodoxin from azotobacter vinelandii, a molten globule-like folding intermediate is formed. this wild-type protein contains three tryptophans. in this study, we use a general approach to analyze time-resolved fluorescence and steady-state fluorescence data that are obtained upon denaturant-induced unfolding of a single-tryptophan-containing variant of apoflavodoxin [i.e., w74/f128/f167 (wff) apoflavodoxin]. the experimental data ... | 2011 | 21425856 |
| [the antioxidant effect of bacillus subtilis and azotobacter vinelandii on the seeds of crops]. | strong inhibitory effect of hydrogen peroxide on the germination of cereals seeds depending on concentration and effect time has been established. it has been established that culture mediums of azotobacter vinelandii imv b-7076 and bacillus subtilis imv b-7023 are capable to antioxidant influence on the germination index of these seeds. this evidences for the capacity of these bacteria to produce bioregulators with the protection effect. aminoacids: lysine, arginine, cystine, metionine, that ha ... | 2011 | 21442952 |
| endophytic bacteria of mammillaria fraileana, an endemic rock-colonizing cactus of the southern sonoran desert. | the small cactus mammillaria fraileana is a pioneer rock-colonizing plant harboring endophytic bacteria with the potential for nitrogen fixation and rock weathering (phosphate solubilization and rock degradation). in seeds, only a combination of culture-independent methods, such as fluorescence in situ hybridization, scanning electron microscopy, and fluorescence vital staining, detected significant amounts of non-culturable, but living, endophytic bacteria distributed underneath the membrane co ... | 2011 | 21445557 |
| development of cyanobacterium-based biofilms and their in vitro evaluation for agriculturally useful traits. | the ability of cyanobacteria to be useful as matrices for agriculturally important bacteria was evaluated. biofilms were generated with the selected strain anabaena torulosa after co-culturing with azotobacter chroococcum, pseudomonas striata, serratia marcescens, and mesorhizobium ciceri. the biochemical attributes were compared with individual bacterial and cyanobacterial cultures. the biofilms were characterized in terms of proteins, chlorophyll, iaa production, acetylene-reducing activity, p ... | 2011 | 21448713 |
| roles of rpos and psra in cyst formation and alkylresorcinol synthesis in azotobacter vinelandii. | azotobacter vinelandii is a soil bacterium that undergoes differentiation to form cysts that are resistant to desiccation. upon induction of cyst formation, the bacterium synthesizes alkylresorcinols that are present in cysts but not in vegetative cells. alternative sigma factors play important roles in differentiation. in a. vinelandii, algu (sigma e) is involved in controlling the loss of flagella upon induction of encystment. we investigated the involvement of the sigma factor rpos in cyst fo ... | 2011 | 21454367 |
| molybdenum nitrogenase catalyzes the reduction and coupling of co to form hydrocarbons. | the molybdenum-dependent nitrogenase catalyzes the multi-electron reduction of protons and n(2) to yield h(2) and 2nh(3). it also catalyzes the reduction of a number of non-physiological doubly and triply bonded small molecules (e.g. c(2)h(2), n(2)o). carbon monoxide (co) is not reduced by the wild-type molybdenum nitrogenase but instead inhibits the reduction of all substrates catalyzed by nitrogenase except protons. here, we report that when the nitrogenase mofe protein a-val(70) residue is su ... | 2011 | 21454640 |
| enterococcus faecalis sufcdsub complements escherichia coli sufabcdse. | iron-sulfur [fe-s] clusters are inorganic prosthetic groups that play essential roles in all living organisms. iron and sulfur mobilization, formation of [fe-s] clusters, and delivery to its final protein targets involves a complex set of specific protein machinery. proteobacteria has three systems of [fe-s] biogenesis, designated nif, isc, and suf. in contrast, the firmicutes system is not well characterized and has only one system, formed mostly by suf homologs. the firmicutes phylum correspon ... | 2011 | 21480963 |
| a tale of two subunits: how the neomorphic r132h idh1 mutation enhances production of αhg. | heterozygously expressed single-point mutations in isocitrate dehydrogenase 1 and 2 (idh1 and idh2, respectively) render these dimeric enzymes capable of producing the novel metabolite α-hydroxyglutarate (αhg). accumulation of αhg is used as a biomarker for a number of cancer types, helping to identify tumors with similar idh mutations. with idh1, it has been shown that one role of the mutation is to increase the rate of conversion from αkg to αhg. to improve our understanding of the function of ... | 2011 | 21524095 |
| water-assisted proton transfer in ferredoxin i. | the role of water molecules in assisting proton transfer (pt) is investigated for the proton-pumping protein ferredoxin i (fdi) from azotobacter vinelandii. it was previously shown that individual water molecules can stabilize between asp15 and the buried [3fe-4s](0) cluster and thus can potentially act as a proton relay in transferring h(+) from the protein to the μ(2) sulfur atom. here, we generalize molecular mechanics with proton transfer (mmpt) to studying proton transfer reactions in the c ... | 2011 | 21531725 |
| cloning, expression, purification, crystallization and preliminary crystallographic analysis of nifh1 from methanocaldococcus jannaschii. | nitrogen fixation is catalyzed by the nitrogenase complex in azotobacter, which is composed of dinitrogenase and dinitrogenase reductase. dinitrogenase is an α(2)β(2) heterotetramer of the proteins nifd and nifk. dinitrogenase reductase is a homodimer of the protein nifh. the expression of nifd/k and nifh nitrogenase homologues (named nfld/k and nflh for nif-like d and h, respectively) has been detected in the non-nitrogen-fixing hyperthermophilic methanogen methanocaldococcus jannaschii. solvin ... | 2011 | 21543862 |
| nifen-b complex of azotobacter vinelandii is fully functional in nitrogenase femo cofactor assembly. | assembly of nitrogenase femoco is one of the key processes in bioinorganic chemistry. nifb and nifen are two essential elements immediately adjacent to each other along the biosynthetic pathway of femoco. previously, an 8fe-precursor of femoco was identified on nifen; however, the identity of the biosynthetic intermediate on nifb has remained elusive to date. here, we present a combined biochemical and spectroscopic investigation of a his-tagged nifen-b fusion protein of azotobacter vinelandii. ... | 2011 | 21551100 |
| impact of organic fertilizers with and without chemical fertilizers on soil chemical properties and the establishment of nitrogen-fixing bacteria in the rhizosphere. | effects of organic fertilizers with and without the application of chemical fertilizers for seven years as part of a wheat-pearl millet cropping sequence on soil chemical properties and the establishment of nitrogen fixing bacteria in the rhizosphere were examined. the application of farmyard manure, poultry manure, and sugarcane filter cake alone or in combination with chemical fertilizers improved the soil organic c, total n, p, and k status. larger populations of azotobacter chroococcum and r ... | 2008 | 21558724 |
| structural models of the [fe4s4] clusters of homologous nitrogenase fe proteins. | the iron (fe) proteins of molybdenum (mo)-, vanadium (v)-, and iron (fe)-only nitrogenases are encoded by nifh, vnfh, and anfh, respectively. while the nifh-encoded fe protein has been extensively studied over recent years, information regarding the properties of the vnfh- and anfh-encoded fe proteins has remained scarce. here, we present a combined biochemical, electron paramagnetic resonance (epr) and x-ray absorption spectroscopy (xas) analysis of the [fe(4)s(4)] clusters of nifh, vnfh, and a ... | 2011 | 21718019 |
| transcriptional profiling of nitrogen fixation in azotobacter vinelandii. | most biological nitrogen (n(2)) fixation results from the activity of a molybdenum-dependent nitrogenase, a complex iron-sulfur enzyme found associated with a diversity of bacteria and some methanogenic archaea. azotobacter vinelandii, an obligate aerobe, fixes nitrogen via the oxygen-sensitive mo nitrogenase but is also able to fix nitrogen through the activities of genetically distinct alternative forms of nitrogenase designated the vnf and anf systems when mo is limiting. the vnf system appea ... | 2011 | 21724999 |
| differential accumulation of nifstructural gene mrna in azotobacter vinelandii. | northern analysis was employed to investigate mrna produced by mutant strains of azotobacter vinelandiiwith defined deletions in the nifstructural genes and in the intergenic noncoding regions. the results indicate that intergenic rna secondary structures effect the differential accumulation of transcripts, supporting the high fe protein-to-mofe protein ratio required for optimal diazotrophic growth. | 2011 | 21725008 |
| gene expression and biochemical characterization of azotobacter vinelandii cyclophilins and protein interaction studies of the cytoplasmic isoform with dnak and lpxh. | the soil nitrogen-fixing bacterium azotobacter vinelandii possesses two cyclophilins, comprising putative cytoplasmic and periplasmic isoforms, designated as avppib and avppia, respectively. both recombinant cyclophilins have been purified and their peptidyl-prolyl cis/trans isomerase activity against suc-ala-xaa-pro-phe-pna synthetic peptides has been characterized. the substrate specificity of both cyclophilins is typical for bacterial cyclophilins, with suc-ala-ala-pro-phe-pna being the most ... | 2011 | 21734408 |
| the role of the gaf and central domains of the transcriptional activator vnfa in azotobacter vinelandii. | vnfa is a transcriptional activator required for the expression of the structural genes encoding nitrogenase-2 in azotobacter vinelandii. vnfa consists of three domains: an n-terminal regulatory domain termed gaf, including a cys-rich motif, a central domain from the aaa+ family, and a c-terminal domain for dna binding. previously, we reported that transcriptionally active vnfa harbored an fe-s cluster, presumably of the 3fe-4s type, as a prosthetic group, and the cys-rich motif were possibly as ... | 2011 | 21752196 |
| fate of nitrogen-fixing bacteria in crude oil contaminated wetland ultisol. | the effect of crude oil on the growth of legumes (calopogonium muconoides and centrosema pubescens) and fate of nitrogen-fixing bacteria in wetland ultisol was investigated using standard cultural techniques. the results revealed observable effects of oil on soil physico-chemistry, plant growth and nodulation as well as on densities of heterotrophic, hydrocarbonoclastic and nitrogen fixing bacteria. the effects however varied with different levels (0.5%, 1%, 5%, 10%, 15% and 20%) of pollution. a ... | 2011 | 21755289 |
| the cytoplasmic cyclophilin from azotobacter vinelandii interacts with phosphate acetyltransferase isoforms enhancing their in vitro activity. | cyclophilins belong to the peptidyl-prolyl cis/trans isomerase family of enzymes (ec 5.2.1.8), which accelerate protein folding by catalysing the cis/trans isomerisation of proline imidic peptide bonds. in the present study, by a combination of bioinformatics methods, we identify phosphate acetyltransferase isoforms, avpta-1 and avpta-2, as potential interacting partners of avppib, the cytoplasmic cyclophilin from azotobacter vinelandii, and demonstrate their physical interaction by co-expressio ... | 2011 | 21773943 |
| transcriptional activation of the azotobacter vinelandii polyhydroxybutyrate biosynthetic genes phbbac by phbr and rpos. | we previously showed that in azotobacter vinelandii accumulation of polyhydroxybutyrate (phb) occurs mainly during the stationary phase and that a mutation in phbr, encoding a transcriptional regulator of the arac family, reduced phb accumulation. in this study, we characterized the roles of phbr and rpos, a central regulator during stationary phase in bacteria, in the regulation of expression of the phb biosynthetic operon phbbac and phbr. we showed that inactivation of rpos reduced phb accumul ... | 2011 | 21778206 |
| phap, a poly(3-hydroxybutyrate) granule-associated protein, has an unexpected stress reducing effect in escherichia coli. | phasins (phap) are proteins normally associated with granules of poly(3-hydroxybutyrate) (phb), a biodegradable polymer accumulated by many bacteria as a reserve molecule. these proteins enhance growth and polymer production in natural and recombinant phb producers. it has been shown that the production of phb causes a stress in recombinant escherichia coli, revealed by an increase in the concentration of several heat stress proteins. in this work, qrt-pcr analysis was used to study the effect o ... | 2011 | 21784905 |
| [effect of phytohormones synthesized by rhizosphere bacteria on plants]. | new strains of rhizosphere microorganisms azotobacter chroococcum az d10, bacillus megaterium p1-04, and bacillus mucilaginosus b-1574 were found to be able to synthesize cytokinins (cks) and indolylacetic acid (iaa). three forms of cks-dihydrozeatin riboside, isopentenyl adenosine, and trans-zeatin riboside-were identified, whose ratio was different in the three bacterial cultures. inoculation of cucumber (cucumis sativus l.) plants increased the content of cks and iaa in them by 35.6 and 21.3% ... | 2011 | 21790030 |
| [biopolymer of alginate nature with a predominance of l-guluronic acid]. | highly viscous polysaccharide (250-350 kda) of an alginate nature with a predominance of alpha-l-guluronic acid (m/g = 0.22) was obtained from azotobacter vinelandi. the yield ofpolysaccharide was 20.5 +/- 0.5 g/l when cultured in a medium containing molasses at a viscosity of the cultural liquid of over 30000 cst. the biopolymer is stable at ph 4.0-9.0 in a wide temperature range and well soluble in highly mineralized water; it retains a high viscosity level and can be used in the petroleum ind ... | 2011 | 21790036 |
| azotobacter vinelandii gene clusters for two types of peptidic and catechol siderophores produced in response to molybdenum. | aim: to characterize the complementary production of two types of siderophores in azotobacter vinelandii. methods and results: in an iron-insufficient environment, nitrogen-fixing a. vinelandii produces peptidic (azotobactin) and catechol siderophores for iron uptake to be used as a nitrogenase cofactor. molybdenum, another nitrogenase cofactor, was also found to affect the production level of siderophores. wild-type cells excreted azotobactin into molybdenum-supplemented and iron-insufficient ... | 2011 | 21794033 |
| defining the pseudomonas genus: where do we draw the line with azotobacter? | the genus pseudomonas has gone through many taxonomic revisions over the past 100 years, going from a very large and diverse group of bacteria to a smaller, more refined and ordered list having specific properties. the relationship of the pseudomonas genus to azotobacter vinelandii is examined using three genomic sequence-based methods. first, using 16s rrna trees, it is shown that a. vinelandii groups within the pseudomonas close to pseudomonas aeruginosa. genomes from other related organisms ( ... | 2011 | 21811795 |
| extending the carbon chain: hydrocarbon formation catalyzed by vanadium/molybdenum nitrogenases. | in a small-scale reaction, vanadium-dependent nitrogenase has previously been shown to catalyze reductive catenation of carbon monoxide (co) to ethylene, ethane, propylene, and propane. here, we report the identification of additional hydrocarbon products [+¦-butylene, n-butane, and methane (ch(4))] in a scaled-up reaction featuring 20 milligrams of vanadium-iron protein, the catalytic component of vanadium nitrogenase. additionally, we show that the more common molybdenum-dependent nitrogenase ... | 2011 | 21817053 |
| assembly of nitrogenase mofe protein. | biosynthesis of mofe protein and, particularly, that of its associated p-cluster and femoco has raised a significant amount of interest because of the biological importance and chemical exclusiveness of these unique clusters. following a brief introduction to the properties of azotobacter vinelandii mofe protein, this chapter will focus on the recent progress toward understanding the assembly mechanism of mofe protein, with an emphasis on studies that provide important structural or spectroscopi ... | 2011 | 21833859 |
| genomic analysis of nitrogen fixation. | advances in sequencing technology in the past decade have enabled the sequencing of genomes of thousands of organisms including diazotrophs. genomics have enabled thorough analysis of the gene organization of nitrogen-fixing species, the identification of new genes involved in nitrogen fixation, and the identification of new diazotrophic species. this chapter reviews key characteristics of nitrogen-fixing genomes and methods to identify and analyze genomes of new diazotrophs using genome scannin ... | 2011 | 21833860 |
| molecular biology and genetic engineering in nitrogen fixation. | biological nitrogen fixation is a complex and tightly regulated process limited to a group of prokaryotic species known as diazotrophs. among well-studied diazotrophs, azotobacter vinelandii is the best studied for its convenience of aerobic growth, its high levels of nitrogenase expression, and its genetic tractability. this chapter includes protocols and strategies in the molecular biology and genetic engineering of a. vinelandii that have been used as valuable tools for advancing studies on t ... | 2011 | 21833862 |
| x-ray crystallography. | x-ray crystallography has been particularly important in the study of the enzyme nitrogenase, providing researchers with high-resolution structural models that have been essential to studying the enzyme's unique metal clusters and nucleotide-binding modes and protein interactions. while several important nitrogenase structures have already been determined using x-ray crystallography, the technique still holds great potential for future significant discoveries involving reaction intermediates and ... | 2011 | 21833866 |
| substitutions in the redox-sensing pas domain of the nifl regulatory protein define an inter-subunit pathway for redox signal transmission. | the per-arnt-sim (pas) domain is a conserved α/β fold present within a plethora of signalling proteins from all kingdoms of life. pas domains are often dimeric and act as versatile sensory and interaction modules to propagate environmental signals to effector domains. the nifl regulatory protein from azotobacter vinelandii senses the oxygen status of the cell via an fad cofactor accommodated within the first of two amino-terminal tandem pas domains, termed pas1 and pas2. the redox signal perceiv ... | 2011 | 21854469 |
| n(2) fixation estimates in real-time by cavity ring-down laser absorption spectroscopy. | the most common currency for estimating n(2) fixation is acetylene reduction to ethylene. real-time estimates of nitrogen fixation are needed to close the global nitrogen budget and these remain a critical gap in both laboratory and field experiments. we present a new method for continuous real-time measurements of ethylene production: acetylene reduction assays by cavity ring-down laser absorption spectroscopy (aracas). in aracas, air in the headspace of an incubation chamber is circulated with ... | 2011 | 21879367 |
| Transcriptional and biochemical characterization of two Azotobacter vinelandii FKBP family members. | Peptidyl-prolyl cis/trans isomerases (PPIases, EC: 5.2.1.8), a class of enzymes that catalyse the rate-limiting step of the cis/trans isomerization in protein folding, are divided into three structurally unrelated families: cyclophilins, FK506-binding proteins (FKBPs), and parvulins. Two recombinant FKBPs from the soil nitrogen-fixing bacterium Azotobacter vinelandii, designated as AvfkbX and AvfkbB, have been purified and their peptidyl-prolyl cis/trans isomerase activity against Suc-Ala-Xaa-Pr ... | 2011 | 21887648 |
| Study of enzymatic properties of phenol oxidase from nitrogen-fixing Azotobacter chroococcum. | ABSTRACT: Azotobacter chroococcum is a widespread free-living soil bacterium within the genus of Azotobacter known for assimilation of atmospheric nitrogen and subsequent conversion into nitrogenous compounds, which henceforth enrich the nitrogen content of soils. A. chroococcum SBUG 1484, isolated from composted earth, exhibits phenol oxidase (PO) activity when growing under nitrogen-fixing conditions. In the present study we provide incipient analysis of the crude PO activity expressed by A. c ... | 2011 | 21906365 |
| Structure of a highly NADP+-specific isocitrate dehydrogenase. | Isocitrate dehydrogenase catalyzes the first oxidative and decarboxylation steps in the citric acid cycle. It also lies at a crucial bifurcation point between CO2-generating steps in the cycle and carbon-conserving steps in the glyoxylate bypass. Hence, the enzyme is a focus of regulation. The bacterial enzyme is typically dependent on the coenzyme nicotinamide adenine dinucleotide phosphate. The monomeric enzyme from Corynebacterium glutamicum is highly specific towards this coenzyme and the su ... | 2011 | 21931217 |
| electron transfer within nitrogenase: evidence for a deficit-spending mechanism. | the reduction of substrates catalyzed by nitrogenase utilizes an electron transfer (et) chain comprised of three metalloclusters distributed between the two component proteins, designated as the fe protein and the mofe protein. the flow of electrons through these three metalloclusters involves et from the [4fe-4s] cluster located within the fe protein to an [8fe-7s] cluster, called the p cluster, located within the mofe protein and et from the p cluster to the active site [7fe-9s-x-mo-homocitrat ... | 2011 | 21939270 |
| An investigation of agitation speed as a factor affecting the quantity and monomer distribution of alginate from Azotobacter vinelandii ATCC(®) 9046. | Alginate is a copolymer of ß-D: -mannuronic and a-L: -guluronic acids. Distribution of these monomers in the alginate structure is one of the important characteristics that affect the commercial value of the polymer. In the present work, the effect of agitation speed in the range of 200-700 rpm on alginate production by Azotobacter vinelandii ATCC(®) 9046 was investigated at a dissolved oxygen tension of 5% of air saturation. Experiments were conducted in a fermentor operated in batch mode for 7 ... | 2011 | 22009058 |
| In Vitro effects of various xenobiotics on Azotobacter chroococcum strains isolated from soils of southern Poland. | Fourteen Azotobacter chroococcum strains isolated from soils of Southern Poland were studied concerning resistance to various xenobiotics: heavy metal ions: Cd(2+,) Cu(2+), Fe(3+), Mn(2+), Pb(2+), Zn(2+), pesticides: herbicides linuron (3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea) and combination of mecoprop ((RS)-2-(4-chloro-2-methylphenoxy)propanoic acid), dicamba (3,6-dichloro-2-methoxybenzoic acid) and MCPA (2-methyl-4-chlorophenoxyacetic acid), fungicide copper oxychloride, insecticide fe ... | 2012 | 22022783 |
| isolation of an endosulfan-degrading bacterium from a coffee farm soil: persistence and inhibitory effect on its biological functions. | endosulfan is a lypophilic persistent organic pollutant (pop) that has caused widespread concern due to its persistence in the environment, toxicity and bioaccumulation in living organisms. the aim of this study is to isolate endosulfan-degrading bacteria taken from five coffee farms historically exposed to this insecticide which could be used in future remediation strategies. the biodegradation capability of the isolated strain as well as endosulfan's impact on some of the strain's biological f ... | 2011 | 22033355 |
| alginate production and alg8 gene expression by azotobacter vinelandii in continuous cultures. | alginates are polysaccharides that are used as thickening agents, stabilizers, and emulsifiers in various industries. these biopolymers are produced by fermentation with a limited understanding of the processes occurring at the cellular level. the objective of this study was to evaluate the effects of agitation rate and inlet sucrose concentrations (isc) on alginate production and the expression of the genes encoding for alginate-lyases (algl) and the catalytic subunit of the alginate polymerase ... | 2011 | 22072437 |
| Biochemistry. One atom makes all the difference. | 2011 | 22096179 | |
| evidence for interstitial carbon in nitrogenase femo cofactor. | the identity of the interstitial light atom in the center of the femo cofactor of nitrogenase has been enigmatic since its discovery. atomic-resolution x-ray diffraction data and an electron spin echo envelope modulation (eseem) analysis now provide direct evidence that the ligand is a carbon species. | 2011 | 22096190 |
| x-ray emission spectroscopy evidences a central carbon in the nitrogenase iron-molybdenum cofactor. | nitrogenase is a complex enzyme that catalyzes the reduction of dinitrogen to ammonia. despite insight from structural and biochemical studies, its structure and mechanism await full characterization. an iron-molybdenum cofactor (femoco) is thought to be the site of dinitrogen reduction, but the identity of a central atom in this cofactor remains unknown. fe kβ x-ray emission spectroscopy (xes) of intact nitrogenase mofe protein, isolated femoco, and the femoco-deficient nifb protein indicates t ... | 2011 | 22096198 |
| 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 |