| a novel response-regulator is able to suppress the nodulation defect of a bradyrhizobium japonicum nodw mutant. | the two-component regulatory system nod-vw of bradyrhizobium japonicum is essential for the nodulation of the legume host plants vigna radiata, v. unguiculata and macroptilium atropurpureum. the nodv protein shares homology with the sensor-kinases, whereas the nodw protein is a member of the response-regulator class. we report here the identification of a new b. japonicum dna region that is able to suppress the phenotypic defect of a nodw mutant, provided that this region is expressed from a for ... | 1993 | 8264528 |
| identification and cloning of a cyclic beta-(1-->3), beta-(1-->6)-d-glucan synthesis locus from bradyrhizobium japonicum. | a cosmid clone complementing a cyclic beta-(1-->2)-glucan biosynthesis (ndvb) mutant of rhizobium meliloti was isolated from a bradyrhizobium japonicum gene library. this clone specified synthesis of beta-(1-->3), beta-(1-->6)-linked glucans in r. meliloti. the complemented strain was osmotically tolerant and symbiotically competent on alfalfa. thus, beta-(1-->3), beta-(1-->6)-glucans can substitute functionally for beta-(1-->2)-glucans in r. meliloti. | 1993 | 8282182 |
| steady-state kinetics of malonyl-coa synthetase from bradyrhizobium japonicum and evidence for malonyl-amp formation in the reaction. | malonyl-coa synthetase catalyses the formation of malonyl-coa directly from malonate and coa with hydrolysis of atp into amp and pp1. the catalytic mechanism of malonyl-coa synthetase from bradyrhizobium japonicum was investigated by steady-state kinetics. initial-velocity studies and the product-inhibition studies with amp and ppi strongly suggested ordered bi uni uni bi ping pong ter ter system as the most probable steady-state kinetic mechanism of malonyl-coa synthetase. michaelis constants w ... | 1994 | 8297339 |
| nucleotide sequence analysis of four genes, hupc, hupd, hupf and hupg, downstream of the hydrogenase structural genes in bradyrhizobium japonicum. | the nucleotide sequence of a 2.2 kb region downstream of the hydrogenase structural genes in bradyrhizobium japonicum was determined. four genes encoding predicted polypeptides of 27.8 (hupc), 21.4 (hupd), 10.6 (hupf) and 15.8 (hupg) kda were identified, of which the first three probably belong to the same operon as the hup structural genes, hups and hupl. hupc is homologous to the hydrophobic polypeptides with four potential transmembrane regions that are encoded by open reading frames followin ... | 1993 | 8230232 |
| common soybean inoculant strains in brazil are members of bradyrhizobium elkanii. | the brazilian inoculant strains 29w and 587 were found to be members of bradyrhizobium elkanii primarily on the basis of 16s rrna gene sequences identical to that of b. elkanii usda76 and on the basis of reactivity with antibodies against serogroups 76 and 31, respectively. the agronomic consequences of using strains of b. elkanii as soybean inoculants are discussed. | 1993 | 8285723 |
| formation of several bacterial c-type cytochromes requires a novel membrane-anchored protein that faces the periplasm. | we report here the discovery of a novel bacterial gene (cych) whose product is involved in the biogenesis of most of the cellular cytochromes c. the cych gene was detected in the course of characterizing a cytochrome oxidase-deficient bradyrhizobium japonicum tn5 mutant (strain cox3) in which the transposon insertion disrupted cych. all of the c-type cytochromes detectable in aerobically grown b. japonicum wild-type cells were absent in the cox3 mutant, with the exception of cytochrome c1. a sec ... | 1993 | 8231805 |
| proposal for rejection of agrobacterium tumefaciens and revised descriptions for the genus agrobacterium and for agrobacterium radiobacter and agrobacterium rhizogenes. | the 16s rrna sequences of seven representative agrobacterium strains, eight representative rhizobium strains, and the type strains of azorhizobium caulinodans and bradyrhizobium japonicum were determined. these strains included the type strains of agrobacterium tumefaciens, agrobacterium rhizogenes, agrobacterium radiobacter, agrobacterium vitis, agrobacterium rubi, rhizobium fredii, rhizobium galegae, rhizobium huakuii, rhizobium leguminosarum, rhizobium loti, rhizobium meliloti, and rhizobium ... | 1993 | 8240952 |
| bacterial genes involved in incorporation of nickel into a hydrogenase enzyme. | nickel is an essential component of all h2-uptake hydrogenases. a fragment of dna that complements a h2-uptake-deficient but nickel-cured mutant strain (jhk7) of bradyrhizobium japonicum was isolated and sequenced. this 4.5-kb dna fragment contains four open reading frames designated as orf1, hupn, hupo, and hupp, which encode polypeptides with predicted masses of 17, 40, 19, and 63.5 kda, respectively. the last three open reading frames (hupnop) are most likely organized as an operon with a put ... | 1994 | 8197192 |
| characterization of the soybean early nodulin cdna clone gmenod55. | two cdna clones of the soybean early nodulin gmenod55 were characterized. these clones may represent two members of the soybean early nodulin gene family gmenod55. gmenod55 has an n-terminal signal peptide and it contains an internal domain consisting of proline and serine residues. analyses of nodules lacking infection threads and intracellular bacteria suggest that the gmenod55 gene is first expressed after release of bradyrhizobium japonicum in plant cells. this conclusion is supported by in ... | 1993 | 8400132 |
| identification of nodsuij genes in nod locus 1 of azorhizobium caulinodans: evidence that nods encodes a methyltransferase involved in nod factor modification. | the azorhizobium caulinodans strain ors571 nodulation genes nodsuij were located downstream from nodabc. complementation data and transcriptional analysis suggest that nodabcsuij form a single operon. mutants with tn5 insertions in the genes nods, nodu, and nodj were delayed in nodulation of sesbania rostrata roots and stems. the nods amino acid sequences of ors571, bradyrhizobium japonicum, and rhizobium sp. strain ngr234, contain a consensus with similarity to s-adenosylmethionine (sam)-utiliz ... | 1993 | 8412659 |
| isolation, dna sequence analysis, and mutagenesis of a proline dehydrogenase gene (puta) from bradyrhizobium japonicum. | we report here the cloning and sequencing of the gene for proline dehydrogenase (puta) of bradyrhizobium japonicum. an open reading frame coding for 1,016 amino acids was identified. the b. japonicum gene codes for a bifunctional protein with proline dehydrogenase and pyrroline-5-carboxylate (p5c) dehydrogenase activities, as it does in escherichia coli and salmonella typhimurium. comparison of the sequences of these proteins with other proline and p5c dehydrogenase sequences identified proline ... | 1996 | 8572700 |
| a genetic region downstream of the hydrogenase structural genes of bradyrhizobium japonicum that is required for hydrogenase processing. | deletion of a 2.9-kb chromosomal ecori fragment of dna located 2.2 kb downstream from the end of the hydrogenase structural genes resulted in the complete loss of hydrogenase activity. the normal 65- and 35-kda hydrogenase subunits were absent in the deletion mutants. instead, two peptides of 66.5 and 41 kda were identified in the mutants by use of anti-hydrogenase subunit-specific antibody. a hydrogenase structural gene mutant did not synthesize either the normal hydrogenase subunits or the lar ... | 1993 | 8416905 |
| levels and identities of nonrhizobial microorganisms found in commercial legume inoculant made with nonsterile peat carrier. | sixty samples of commercial north american legume inoculants manufactured for sale in 1994 using nonsterile peat as carrier were tested for rhizobium (or bradyrhizobium) content and non-rhizobium biological contaminant load. products of three major producers of such inoculants for sale in canada were examined. viable rhizobium content varied from 5.6 x 10(5) to 8.1 x 10(9) cells/g, while the contaminant load varied from 1.8 x 10(8) to 5.5 x 10(10) cfu/g. most of the inoculants contained more non ... | 1996 | 8595599 |
| multiple copies of nodd in rhizobium tropici ciat899 and br816. | rhizobium tropici strains are able to nodulate a wide range of host plants: phaseolus vulgaris, leucaena spp., and macroptilium atropurpureum. we studied the nodd regulatory gene for nodulation of two r. tropici strains: ciat899, the reference r. tropici type iib strain, and br816, a heat-tolerant strain isolated from leucaena leucocephala. a survey revealed several nodd-hybridizing dna regions in both strains: five distinct regions in ciat899 and four distinct regions in br816. induction experi ... | 1993 | 8419293 |
| correlated physical and genetic map of the bradyrhizobium japonicum 110 genome. | we describe a compilation of 79 known genes of bradyrhizobium japonicum 110, 63 of which were placed on a correlated physical and genetic map of the chromosome. genomic dna was restricted with enzymes paci, pmei, and swai, which yielded two, five, and nine fragments, respectively. linkage of some of the fragments was established by performing southern blot hybridization experiments. for probes we used isolated, labelled fragments that were produced either by pmei or by swai. genes were mapped on ... | 1993 | 8423135 |
| expression and regulation of bradyrhizobium japonicum and xanthobacter flavus co2 fixation genes in a photosynthetic bacterial host. | calvin cycle carbon dioxide fixation genes encoded on dna fragments from two nonphotosynthetic, chemolithoautotrophic bacteria, bradyrhizobium japonicum and xanthobacter flavus, were found to complement and support photosynthetic growth of a ribulose 1,5-bisphosphate carboxylase-oxygenase (rubisco) deletion mutant of the purple nonsulfur bacterium rhodobacter sphaeroides. the regulation of rubisco expression was analyzed in the complemented r. sphaeroides rubisco deletion mutant. distinct differ ... | 1993 | 8423157 |
| biosynthesis of cyclic beta-(1-3),beta-(1-6) glucan in bradyrhizobium spp. | inner membranes of bradyrhizobium japonicum strain usda 110 produced in vitro soluble and insoluble beta-(1-3),beta-(1-6) glucans. the reaction proceeded through a 90 kda inner membrane intermediate protein; used udp-glucose as sugar donor and required mg2+. gel chromatography of soluble glucans resolved a cyclic beta-(1-3) glucan with a degree of polymerization of eleven from a family of beta-(1-3),beta-(1-6) glucans with variable degree of polymerization higher than eleven. bradyrhizobium stra ... | 1993 | 8427547 |
| the oxygen sensor fixl of rhizobium meliloti is a membrane protein containing four possible transmembrane segments. | regulation of nitrogen fixation genes in rhizobium meliloti is mediated by two proteins, fixl and fixj, in response to oxygen availability. fixl is an oxygen-binding hemoprotein with kinase and phosphatase activities that is thought to sense oxygen levels directly and to transmit this signal to fixj via phosphorylation-dephosphorylation reactions. fixj controls the expression of other regulatory genes, including nifa, that regulate the transcription of genes required for symbiotic nitrogen fixat ... | 1993 | 8432704 |
| sequence and characterisation of a ribosomal rna operon from agrobacterium vitis. | one of the four ribosomal rna operons (rrna) from the agrobacterium vitis vitopine strain s4 was sequenced, rrna is most closely related to the rrn operons of bradyrhizobium japonicum and rhodobacter sphaeroides and carries an fmet-trna gene downstream of its 5s gene, as in the case of r. sphaeroides. the 16s rrna sequence of s4 differs from the a. vitis k309 type strain sequence by only one nucleotide, in spite of the fact that s4 and k309 have very different ti plasmids. the predicted secondar ... | 1996 | 8628253 |
| nodz, a unique host-specific nodulation gene, is involved in the fucosylation of the lipooligosaccharide nodulation signal of bradyrhizobium japonicum. | the nodulation genes of rhizobia are regulated by the nodd gene product in response to host-produced flavonoids and appear to encode enzymes involved in the production of a lipo-chitose signal molecule required for infection and nodule formation. we have identified the nodz gene of bradyrhizobium japonicum, whose product is required for the addition of a 2-o-methylfucose residue to the terminal reducing n-acetylglucosamine of the nodulation signal. this substitution is essential for the biologic ... | 1994 | 8300517 |
| bradyrhizobium japonicum rhizobitoxine genes and putative enzyme functions: expression requires a translational frameshift. | some strains of bradyrhizobium japonicum produce rhizobitoxine, a phytotoxin that causes foliar chlorosis on susceptible host plants. we have previously obtained tn5-induced rhizobitoxine null mutants of b. japonicum. dna sequence analysis of the region surrounding two tn5 insertions identifies two overlapping open reading frames. the first open reading frame (rtxa) predicts a 54-kda protein for which the n-terminal 280 residues have sequence similarity to serine: pyruvate aminotransferase. the ... | 1993 | 8464870 |
| nucleotide sequences of two hydrogenase-related genes (hypa and hypb) from bradyrhizobium japonicum, one of which (hypb) encodes an extremely histidine-rich region and guanine nucleotide-binding domains. | sequencing of a 1359-bp (nrui-acci) dna fragment located approximately 5.2 kb downstream from the end of the hydrogenase structural genes of bradyrhizobium japonicum revealed two open reading frames designated hypa and hypb, encoding polypeptides with predicted molecular masses of 12.3 and 32.8 kda, respectively. both hypa and hypb showed strong homology with other genes in hydrogenase-containing bacteria. two 'c-x-x-c' motifs were contained in the deduced amino acid sequence of hypa, a motif th ... | 1994 | 8305450 |
| requirements for maturation of bradyrhizobium japonicum cytochrome c550 in escherichia coli. | various forms of bradyrhizobium japonicum cytochrome c550 (the cyca gene product) were overexpressed in escherichia coli cells grown under different conditions. antibodies directed against a synthetic cytochrome c550 peptide were used as tools to detect both, apoprotein and holoprotein. complete maturation of the apoprotein into its holo form with haem covalently bound to the polypeptide was observed only under anaerobic growth conditions and in e. coli k12 derivatives, whereas haem binding did ... | 1996 | 8654426 |
| purification and characterization of the hydrogenase from thiobacillus ferrooxidans. | hydrogenase of thiobacillus ferrooxidans atcc 19859 was purified from cells grown lithoautotrophically with 80% hydrogen, 8.6% carbon dioxide, and 11.4% air. hydrogenase was located in the 140,000 x g supernatant in cell-free extracts. the enzyme was purified 7.3-fold after chromatography on procion red and q-sepharose with a yield of 19%, resulting in a 85% pure preparation with a specific activity of 6.0 u (mg protein)-1. with native page, a mol. mass of 100 and 200 kda was determined. with sd ... | 1996 | 8661919 |
| the bradyrhizobium japonicum fixghis genes are required for the formation of the high-affinity cbb3-type cytochrome oxidase. | we report structural and functional analyses of the bradyrhizobium japonicum fixghis genes, which map immediately downstream of the fixnoqp operon for the symbiotically essential cbb3-type heme-copper oxidase complex. expression of fixghis, like that of fixnoqp, is strongly induced in cells grown microaerobically or anaerobically. a fixghi deletion led to the same prominent phenotypes as those known from a fixnoqp deletion: defective symbiotic nitrogen fixation (fix-) and decreased cytochrome ox ... | 1996 | 8661920 |
| rapid and efficient selection of recombinant site-directed mutants of bradyrhizobium japonicum by colony hybridization. | due to the high incidence of spontaneous antibiotic resistance and slow growth of bradyrhizobium japonicum strains, screening for site-directed mutants is cumbersome and time-consuming. a rapid method for selection of recombinant site-directed mutants of b. japonicum was developed. a kanamycin (km) and a spectinomycin (sp) cassette were each used to replace dna fragments in the chromosome by homologous recombination. the primary new features of this method involve a simple plate selection for th ... | 1993 | 8319882 |
| use of a promoter-probe vector system in the cloning of a new nifa-dependent promoter (ndp) from bradyrhizobium japonicum. | many of the symbiotic nitrogen-fixation genes in the soybean root nodule bacterium, bradyrhizobium japonicum, are transcribed from -24/-12 promoters that are recognized by the sigma 54-rna polymerase and activated by the transcriptional regulator protein, nifa. several lines of evidence suggest that the b. japonicum genome has more than those seven nifa-regulated promoters which were characterized previously. here, we present a strategy aimed at the cloning of new nifa-activated promoters. it ma ... | 1993 | 8335258 |
| the structures and biological activities of the lipo-oligosaccharide nodulation signals produced by type i and ii strains of bradyrhizobium japonicum. | bradyrhizobium japonicum produces lipo-oligosaccharide signal molecules that induce deformation of root hairs and meristematic activity on soybeans. b. japonicum usda135 (a type i strain) produces modified chitin pentasaccharide molecules with either a terminal n-c16:0- or n-c18:1-glucosamine with and without an o-acetyl group at c-6 and with 2-o-methylfucose linked to c-6 of the reducing n-acetylglucosamine. an additional molecule has n-c16:1-glucosamine and no o-acetyl group. all of these mole ... | 1993 | 8349712 |
| hydrogen-ubiquinone oxidoreductase activity by the bradyrhizobium japonicum membrane-bound hydrogenase. | the bradyrhizobium japonicum heterodimeric nickel-iron hydrogenase efficiently catalyzed h2-ubiquinone-1 oxidoreductase activity at rates up to 47% of the maximal rates obtained using the artificial electron acceptor methylene blue. gel filtration chromatography and sds-polyacrylamide gel electrophoresis experiments demonstrated that the purified enzyme was a heterodimer containing only the 65 kda and 33 kda subunits. reduced minus oxidized absorption difference spectra demonstrated the absence ... | 1993 | 8354459 |
| beta-glucan synthesis in bradyrhizobium japonicum: characterization of a new locus (ndvc) influencing beta-(1-->6) linkages. | bradyrhizobium japonicum synthesizes periplasmic cyclic beta-(1-->3),beta-(1-->6)-d-glucans during growth in hypoosmotic environments, and evidence is growing that these molecules may have a specific function during plant-microbe interactions in addition to osmoregulation. site-directed tn5 mutagenesis of the dna region upstream of ndvb resulted in identification of a new gene (ndvc) involved in beta-(1--> 3), beta-(1-->6)-glucan synthesis and in nodule development. the predicted translation pro ... | 1996 | 8755895 |
| characterization of the ntrbc genes of azospirillum brasilense sp7: their involvement in the regulation of nitrogenase synthesis and activity. | a 7.1 kb ecori fragment from azospirillum brasilense, that hybridized with a probe carrying the ntrbc genes from bradyrhizobium japonicum, was cloned. the nucleotide sequence of a 3.8 kb subfragment was established. this led to the identification of two open reading frames, encoding polypeptides of 401 and 481 amino acids, that were similar to ntrb and ntrc, respectively. a broad host range plasmid containing the putative azospirillum ntrc gene was shown to restore nitrogen fixation under free-l ... | 1993 | 8355653 |
| phylogenetic grouping and identification of rhizobium isolates on the basis of random amplified polymorphic dna profiles. | through the use of a single, random 15mer as a primer, between 1 and 12 dna amplification products were obtained per strain from a selection of 84 rhizobium and bradyrhizobium isolates. a principal-coordinate analysis was used to analyse the resulting amplified dna profiles and it was possible to assign isolates to specific groupings. within the species rhizobium leguminosarum, the biovar phaseoli formed a distinct group from the other biovars of the species, viciae and trifolii, which grouped t ... | 1993 | 8364802 |
| analysis of the bradyrhizobium japonicum hemh gene and its expression in escherichia coli. | complementation analysis showed that the bradyrhizobium japonicum hemh gene was both necessary and sufficient to rescue mutant strains i110ek4 and i110bk2 in trans with respect to hemin auxotrophy, protoporphyrin accumulation, and the deficiency in ferrochelatase activity. the b. japonicum hemh gene was expressed in an escherichia coli t7 expression system and yielded a 39-kda protein, which was consistent with the predicted size of the deduced product. the overexpressed protein was purified and ... | 1993 | 8368826 |
| carbohydrate binding activities of bradyrhizobium japonicum: unipolar localization of the lectin bj38 on the bacterial cell surface. | a polyclonal antiserum generated against the bradyrhizobium japonicum lectin bj38 was characterized to be specifically directed against the protein. treatment of b. japonicum cells with this antiserum and subsequent visualization with transmission electron microscopy and both conventional and confocal fluorescence microscopy revealed bj38 at only one pole of the bacterium. bj38 appeared to be organized in a tuft-like mass, separated from the bacterial outer membrane. bj38 localization was coinci ... | 1993 | 8464919 |
| oxygen-dependent transcriptional regulation of cytochrome aa3 in bradyrhizobium japonicum. | cytochrome aa3 is one of two terminal oxidases expressed in free-living bradyrhizobium japonicum but not symbiotically in bacteroids. difference spectra (dithionite reduced minus ferricyanide oxidized) for membranes from cells incubated with progressively lower o2 concentrations showed a concomitant decrease in the a603, the absorption peak characteristic of cytochrome aa3. the level of n,n,n',n'-tetramethyl-p-phenylenediamine oxidase activity, a measure of cytochrome aa3 activity, was also foun ... | 1993 | 8380149 |
| characterization of rfrs9, a second member of the rhizobium fredii repetitive sequence family from the nitrogen-fixing symbiont r. fredii usda257. | the genome of the nitrogen-fixing symbiont, rhizobium fredii usda257, contains nine copies of repetitive sequences known as the r. fredii repetitive sequence (rfrs) family. we previously sequenced rfrs3, which is linked to symbiosis plasmid-borne nodulation genes of this organism and has substantial homology to the t-dna of agrobacterium rhizogenes and lesser homology to reiterated sequences of bradyrhizobium japonicum. here we characterize a second family member, rfrs9. the ecori fragment conta ... | 1993 | 8382462 |
| genes for a microaerobically induced oxidase complex in bradyrhizobium japonicum are essential for a nitrogen-fixing endosymbiosis. | we report the discovery of a bradyrhizobium japonicum gene cluster (fixnoqp) in which mutations resulted in defective soybean root-nodule bacteroid development and symbiotic nitrogen fixation. the predicted, dna-derived protein sequences suggested that fixn is a heme b and copper-binding oxidase subunit, fixo a monoheme cytochrome c, fixq a polypeptide of 54 amino acids, and fixp a diheme cytochrome c and that they are all membrane-bound. the isolation and analysis of membrane proteins from b. j ... | 1993 | 8386371 |
| the bradyrhizobium japonicum serocluster 123 hyperreiterated dna region, hrs1, has dna and amino acid sequence homology to is1380, an insertion sequence from acetobacter pasteurianus. | we have sequenced and analyzed the hyperreiterated dna region, hrs1, from bradyrhizobium japonicum usda 424. the 2.1-kb hrs1 fragment is closely linked to the b. japonicum common and genotype-specific nodulation genes in serogroup 123 and 127 strains. southern hybridization analyses indicated that one copy of hrs1 is also located next to the fixrnifa locus in b. japonicum usda 424. nucleotide sequence analysis revealed the presence of a 4-bp target site duplication in hrs1 which is identical to ... | 1993 | 8390818 |
| structural and functional analysis of the fixlj genes of rhizobium leguminosarum biovar phaseoli cnpaf512. | the fixlj genes of rhizobium leguminosarum biovar phaseoli cnpaf512 were identified by dna hybridization of a genomic library with an internal fragment of the rhizobium meliloti fixj gene. the nucleotide sequence was determined and the corresponding amino acid sequence was aligned with the amino acid sequences of the fixl proteins of r. meliloti, bradyrhizobium japonicum and azorhizobium caulinodans. while the fixj protein and the carboxy-terminal part of the fixl protein are highly homologous t ... | 1995 | 8552028 |
| bradyrhizobium japonicum possesses two discrete sets of electron transfer flavoprotein genes: fixa, fixb and etfs, etfl. | a group of four co-regulated genes (fixa, fixb, fixc, fixx) essential for symbiotic nitrogen fixation has been described in several rhizobial species, including bradyrhizobium japonicum. the complete nucleotide sequence of the b. japonicum fixa, fixb and fixc, genes is reported here. the derived amino acid sequences confirmed the previously noted sequence similarity between fixa and the beta-subunit and between fixb and the alpha-subunit of mammalian and paracoccus denitrificans electron transfe ... | 1996 | 8599534 |
| bradyrhizobium japonicum porphobilinogen synthase uses two mg(ii) and monovalent cations. | bradyrhizobium japonicum porphobilinogen synthase (b. japonicum pbgs) has been purified and characterized from an overexpression system in an escherichia coli host (chauhan, s., and o'brian, m. r. (1995) j. biol. chem. 270, 19823-19827). b. japonicum pbgs defines a new class of pbgs protein, type iv (classified by metal ion content), which utilizes a catalytic mga present at a stoichiometry of 4/octamer, an allosteric mgc present at a stoichiometry of 8/octamer, and a monovalent metal ion, k+. h ... | 1996 | 8621501 |
| assembly and function of the cytochrome cbb3 oxidase subunits in bradyrhizobium japonicum. | the bradyrhizobium japonicum cbb3-type cytochrome oxidase, which supports microaerobic respiration, is a multisubunit enzyme encoded by the genes of the fixnoqp operon. we investigated the contribution of the individual subunits to function and assembly of the membrane-bound complex. in-frame deletion mutants of fixn, fixo, and fixq, and an insertion mutant of fixp were constructed. all mutants, except the fixq mutant, showed clearly altered absorption difference spectra of their membranes and d ... | 1996 | 8621562 |
| a high-affinity cbb3-type cytochrome oxidase terminates the symbiosis-specific respiratory chain of bradyrhizobium japonicum. | it has been a long-standing hypothesis that the endosymbiotic rhizobia (bacteroids) cope with a concentration of 10 to 20 nm free o2 in legume root nodules by the use of a specialized respiratory electron transport chain terminating with an oxidase that ought to have a high affinity for o2. previously, we suggested that the microaerobically and anaerobically induced fixnoqp operon of bradyrhizobium japonicum might code for such a special oxidase. here we report the biochemical characteristics of ... | 1996 | 8626278 |
| rhizobium nodulation protein noda is a host-specific determinant of the transfer of fatty acids in nod factor biosynthesis. | in the biosynthesis of lipochitin oligosaccharides (lcos) the rhizobium nodulation protein noda plays an essential role in the transfer of an acyl chain to the chitin oligosaccharide acceptor molecule. the presence of noda in the nodabcij operon makes genetic studies difficult to interpret. in order to be able to investigate the biological and biochemical functions of noda, we have constructed a test system in which the noda, nodb and nodc genes are separately present on different plasmids. effi ... | 1996 | 8628246 |
| isolation of monoclonal antibodies reacting with the core component of lipopolysaccharide from rhizobium leguminosarum strain 3841 and mutant derivatives. | monoclonal antibodies reacting with the core oligosaccharide or lipid a component of rhizobium lipopolysaccharide (lps) could be useful for the elucidation of the structure and biosynthesis of this group of macromolecules. mutant derivatives of rhizobium leguminosarum 3841 with lps structures lacking the major o-antigen moiety were used as immunogens, and eight antibodies were selected for further study. all the antibodies reacted with the fast-migrating species known as lps-2 following gel elec ... | 1996 | 8631658 |
| bradyrhizobium (arachis) sp. strain nc92 contains two nodd genes involved in the repression of noda and a nola gene required for the efficient nodulation of host plants. | the common nodulation locus and closely linked nodulation genes of bradyrhizobium (arachis) sp. strain nc92 have been isolated on an 11.0-kb ecori restriction fragment. the nucleotide sequence of a 7.0-kb ecorv-ecori subclone was determined and found to contain open reading frames (orfs) homologous to the noda, nodb, nodd1, nodd2, and nola genes of bradyrhizobium japonicum and bradyrhizobium elkanii. nodulation assays of nodd1, nodd2, or nola deletion mutants on the host plants macroptilium atro ... | 1996 | 8631662 |
| a new hemoglobin gene from soybean: a role for hemoglobin in all plants. | we have isolated a new hemoglobin gene from soybean. it is expressed in cotyledons, stems of seedlings, roots, young leaves, and in some cells in the nodules that are associated with the nitrogen-fixing bradyrhizobium symbiont. this contrasts with the expression of the leghemoglobins, which are active only in the infected cells of the nodules. the deduced protein sequence of the new gene shows only 58% similarity to one of the soybean leghemoglobins, but 85-87% similarity to hemoglobins from the ... | 1996 | 8650152 |
| genetic and physical mapping in brassica diploid species of a gene cluster defined in arabidopsis thaliana. | we report the genetic and physical analysis by pulse field gel electrophoresis (pfge) in three brassica diploid genomes for a cluster of five genes characterized in a selected segment of 15 kb on chromosome 3 of arabidopsis thaliana, encoding a bradyrhizobium cycj homologue (at1), a rat p67 translation factor homologue (at2), an em-like (early methionine) protein (at3), chlorophyll synthase (at4) and a yeast sac1 homologue (a5). the arabidopsis gene array was found to be conserved on a single li ... | 1996 | 8676872 |
| metal sensitivity of some symbiotic n2-fixing bacteria and pseudomonas strains. | an investigation was carried out to determine the sensitivity of different soil microbes (rhizobium, bradyrhizobium and pseudomonas) to various metals (cu2+, zn2+, co2+, mn2+, mo2+ and fe2+) in vitro. sulphate and chloride forms of these microelements were used (except mo2+ as na2mo04) in 0.1, 1.0 and 10 micrograms/ml concentrations in modified yem and nutrient broth. growth (optical density, od550 and od640) of bacterium inoculated (approx. 10(6) cfu/ml) tubes, was measured spectrophotometrical ... | 1995 | 8714759 |
| dissection of the transcription machinery for housekeeping genes of bradyrhizobium japonicum. | by using a pcr approach, the bradyrhizobium japonicum siga gene, which encodes the primary rna polymerase sigma factor, sigma80, was cloned and its nucleotide sequence was established. the deduced protein is highly homologous to the siga protein of rhizobium meliloti (72% amino acid sequence identity) but less so to rpod of escherichia coli (51% identity). well conserved is the c-terminal end of the protein, which is probably involved in promoter recognition and binding of the rna polymerase cor ... | 1997 | 8990287 |
| the huptuv operon is involved in negative control of hydrogenase synthesis in rhodobacter capsulatus. | the hupt, hupu, and hupv genes, which are located upstream from the hupslc and hypf genes in the chromosome of rhodobacter capsulatus, form the huptuv operon expressed from the hupt promoter. the hupu and hupv genes, previously thought to belong to a single open reading frame, encode hupu, of 34.5 kda (332 amino acids), and hupv, of 50.4 kda (476 amino acids), which are >/= 50% identical to the homologous bradyrhizobium japonicum hupu and hupv proteins and rhodobacter sphaeroides hupu1 and hupu2 ... | 1996 | 8752335 |
| sequence and mutational analysis of the common nodbcij region of rhizobium sp. (oxytropis arctobia) strain n33, a nitrogen-fixing microsymbiont of both arctic and temperate legumes. | by heterologous hybridization, we have identified the common nodulation genes nodbcij of rhizobium sp. strain n33 within a 8.2-kb psti fragment. the nodbcij genes are located within a 4,620-bp region which also included a consensus nod box promoter. the four open reading frames coding for the nodbcij genes contain 657, 1,353, 915, and 789 nucleotides, respectively. we found that the noda gene was not adjacent to the nodb gene, unlike the situation in many rhizobia. the dna of the nodbcij genes o ... | 1996 | 8755627 |
| expression of the early nodulin, enod40, in soybean roots in response to various lipo-chitin signal molecules. | the lipo-chitin (lco) nodulation signal (nod signal) purified from bradyrhizobium japonicum induced nodule primordia on soybean (i.e. glycine soja) roots. these primordia were characterized by a bifurcated vascular connection, cortical cell division, and the accumulation of mrna of the early nodulin gene, enod40. a chemically synthesized lco identical in structure to the nod signal purified from b. japonicum cultures showed the same activity when inoculated on to soybean roots. surprisingly, syn ... | 1996 | 8758977 |
| purification and characterization of the membrane-bound nitrate reductase isoenzymes of bradyrhizobium japonicum. | two respiratory membrane-bound nitrate reductase (nr) isoenzymes, nri and nrii, have been purified for the first time from one single microorganism. triton x-100-solubilized nrs were purified by a three-step procedure of differential centrifugation, q-sepharose chromatography, and gel filtration on sephacryl s-300. both isoenzymes were purified to homogeneity by the criteria of nr activity staining in polyacrylamide gels run under non-denaturating conditions and coincident staining of the protei ... | 1996 | 8769303 |
| the bradyrhizobium japonicum rpoh1 gene encoding a sigma 32-like protein is part of a unique heat shock gene cluster together with groesl1 and three small heat shock genes. | the heat shock response of bradyrhizobium japonicum is controlled by a complex network involving two known regulatory systems. while some heat shock genes are controlled by a highly conserved inverted-repeat structure (circe), others depend on a sigma 32-type heat shock sigma factor. using western blot (immunoblot) analysis, we confirmed the presence of a sigma 32-like protein in b. japonicum and defined its induction pattern after heat shock. a b. japonicum rpoh-like gene (rpoh1) was cloned by ... | 1996 | 8808920 |
| nodule development induced by mutants of bradyrhizobium japonicum defective in cyclic b-glucan synthesis. | the soybean response to inoculation with b. japonicum mutants defective in cyclic beta-(1-->3), beta-(1-->6) glucan synthesis was examined by electron microscopy and by monitoring the expression of early and late nodulin genes. two mutants were examined. strain ab-14 is an ndvb mutant and is unable to synthesize beta-glucans. strain ab-1 is an ndvc mutant and produces cyclic glucans containing 95 to 100% beta-(1-->3) glycosidic linkages. nodules formed by either mutant were defective in nitrogen ... | 1996 | 8810069 |
| phenotypic characterization and regulation of the nola gene of bradyrhizobium japonicum. | two bradyrhizobium japonicum nola mutants were constructed and used to test the functional role of nola in nodulation. contrary to the previous hypothesis that nola acts as a repressor of nod gene transcription, the expression of a nodd1-lacz or nody-lacz fusion in the nola mutant strains was similar to that found in the wild type. however, nola does appear to act as a transcriptional regulatory protein since it is required for its own expression, as well as that of nodd2. expression of nodd2 fr ... | 1996 | 8810078 |
| two different mechanisms are involved in the heat-shock regulation of chaperonin gene expression in bradyrhizobium japonicum. | heat-shock regulation was detected for three out of the five members of the groesl multigene family in bradyrhizobium japonicum. the results uncovered the simultaneous presence of two distinct heat-shock control systems which so far have not been reported to co-exist in a single prokaryotic organism. the first system concerns groesl1 whose transcription is controlled in a sigma32-dependent manner similar to that known from work done with escherichia coli. heat-shock control of groesl4 is mediate ... | 1996 | 8820652 |
| phylogenetic analysis of rhizobia and agrobacteria based on 16s rrna gene sequences. | the phylogenetic relationships of members of the genera rhizobium, agrobacterium, bradyrhizobium, and azorhizobium were studied by direct sequencing of their amplified 16s rrna genes. comparative analysis of the sequence data confirmed that the genera bradyrhizobium and azorhizobium belong to distinct phylogenetic lineages. the genera rhizobium and agrobacterium were found to be phylogenetically heterogeneous, and several subgroupings in which rhizobium and agrobacterium species were intermixed ... | 1993 | 8494742 |
| identification of a potential transcriptional regulator of hydrogenase activity in free-living bradyrhizobium japonicum strains. | in bradyrhizobium japonicum, tn5 insertions in a particular chromosomal dna fragment result in a hup- phenotype in free-living conditions without affecting hydrogenase (hup) activity in the symbiotic state. by determination of the nucleotide sequence of this region, we were able to identify the nature of the inactivated genes. the fragment is located 9 kb downstream of the hydrogenase structural genes and contains one incomplete and three complete open reading frames. they are designated hypd', ... | 1993 | 8510650 |
| molecular studies on a new genetic locus linked to the common nodulation genes in bradyrhizobium japonicum. | orfa, an actively transcribed genetic locus linked to the common nodulation genes in bradyrhizobium japonicum usda110, was sequenced and analysed. the expression of orfa is neither dependent on the regulatory proteins nifa, ntrc, ntrb and nodd1 nor on either copy of sigma 54, rpon1 and rpon2. the transcriptional start site of orfa was determined and found to overlap the oppositely transcribed nodz gene by 224 nucleotides. an appropriately located -10 sequence identical to the consensus proposed ... | 1997 | 9084141 |
| nodz of bradyrhizobium extends the nodulation host range of rhizobium by adding a fucosyl residue to nodulation signals. | the nodulation genes of rhizobia are involved in the production of the lipo-chitin oligosaccharides (lco), which are signal molecules required for nodule formation. a mutation in nodz of bradyrhizobium japonicum results in the synthesis of nodulation signals lacking the wild-type 2-o-methylfucose residue at the reducting-terminal n-acetylglucosamine. this phenotype is correlated with a defective nodulation of siratro (macroptilium atropurpureum). here we show that transfer of nodz to rhizobium l ... | 1996 | 8858593 |
| modulation of carbohydrate-binding capacities and attachment ability of bradyrhizobium sp. (lupinus) to white lupin roots. | the attachment of bradyrhizobium sp. (lupinus) strain msdj718 to excised roots of white lupin was examined. maximal attachment occurred at early to middle log phases of bacterial growth. this binding was ph dependent, with an optimal value reached at 6.6. irrespective of the culture age, the attachment was strongly affected by the calcium concentration of the growth medium: a ca2+ limitation in the bergersen medium led to optimal attachment of the bacteria. when l-fucose was added during the att ... | 1996 | 8868230 |
| activity of nitrogen fixation and nitrogen assimilation enzymes in soybean plants inoculated with bradyrhizobium japonicum strains. | in studying the symbiotic associations of 8 bradyrhizobium japonicum strains with two soybean varieties (ns-10 and ns-21), we determined the activity of nitrogen fixing (nitrogenase, ng) and nitrogen assimilation (glutamine synthetase, gs) and glutamate dehydrogenase (gdh) enzymes and the content of soluble proteins. the number of nodules was not in correlation with dry matter mass and nitrogen content. dry matter mass and nitrogen content in the nodules of the soybean varieties in association w ... | 1996 | 8876729 |
| nodv and nodw, a second flavonoid recognition system regulating nod gene expression in bradyrhizobium japonicum. | in bradyrhizobium japonicum, members of two global regulatory families, a lysr-type regulator, nodd1, and a two-component regulatory system, nodvw, positively regulate nod gene expression in response to plant-produced isoflavone signals. by analogy to other two-component systems, nodv and nodw are thought to activate transcription via a series of phosphorylation steps. these include the phosphorylation of nodv in response to the plant signal and the subsequent activation of nodw via the transfer ... | 1997 | 9139921 |
| a cytochrome c biogenesis gene involved in pyoverdine production in pseudomonas fluorescens atcc 17400. | pseudomonas fluorescens atcc 17400 produces pyoverdine under iron-limiting conditions. a tn5 mutant, 2g11, produced lower amounts of different pyoverdine forms and was unable to grow under iron limitation caused by ethylenediamine-di(o-hydroxy-phenylacetic acid) (eddha) or zinc. this mutant was complemented by a 9.6 kb hindiii-bamhi dna fragment that contained eight contiguous open reading frames (orfs cyta to cyth). the proteins possibly encoded by this polycistronic gene cluster were all simil ... | 1996 | 8878040 |
| the bradyrhizobium japonicum aconitase gene (acna) is important for free-living growth but not for an effective root nodule symbiosis. | the bradyrhizobium japonicum acna gene encoding the tricarboxylic acid cycle enzyme aconitase was cloned and characterized. the gene was mapped immediately upstream of the cytochrome c biogenesis gene cycv and found to be transcribed in the opposite direction. the nucleotide sequence of acna was determined; the derived amino acid sequence shared a significant similarity with bacterial aconitases and with the human iron-responsive-element-binding protein. the level of expression of the acna gene ... | 1996 | 8892815 |
| the genetic and biochemical basis for nodulation of legumes by rhizobia. | soil bacteria of the genera azorhizobium, bradyrhizobium, and rhizobium are collectively termed rhizobia. they share the ability to penetrate legume roots and elicit morphological responses that lead to the appearance of nodules. bacteria within these symbiotic structures fix atmosphere nitrogen and thus are of immense ecological and agricultural significance. although modern genetic analysis of rhizobia began less than 20 years ago, dozens of nodulation genes have now been identified, some in m ... | 1996 | 8935908 |
| roles of hoxx and hoxa in biosynthesis of hydrogenase in bradyrhizobium japonicum. | in-frame deletion mutagenesis was used to study the roles of two bradyrhizobium japonicum proteins, hoxx and hoxa, in hydrogenase biosynthesis; based on their sequences, these proteins were previously proposed to be sensor and regulator proteins, respectively, of a two-component regulatory system necessary for hydrogenase transcription. deletion of the hoxx gene resulted in a strain that expressed only 30 to 40% of wild-type hydrogenase activity. the inactive unprocessed form of the hydrogenase ... | 1997 | 9171416 |
| genetic diversity among bradyrhizobium isolates that effectively nodulate peanut (arachis hypogaea). | symbiotic gene diversity and other measures of genetic diversity were examined in bradyrhizobium isolates that form an effective symbiosis with peanut (arachis hypogaea). initially, restriction fragment length polymorphism (rflp) analysis using a nitrogenase (nif) gene probe was performed on 33 isolates along with one bradyrhizobium elkanii and two bradyrhizobium japonicum strains. considerable diversity was observed among the rflp patterns of many of the isolates, especially those from south am ... | 1996 | 8941988 |
| the bradyrhizobium japonicum fega gene encodes an iron-regulated outer membrane protein with similarity to hydroxamate-type siderophore receptors. | iron is important in the symbiosis between soybean and its nitrogen-fixing endosymbiont bradyrhizobium japonicum, yet little is known about rhizobial iron acquisition strategies. analysis of outer membrane proteins (omps) from b. japonicum 61a152 identified three iron-regulated omps in the size range of several known receptors for fe(iii)-scavenging siderophores. one of the iron-regulated proteins, fega, was purified and microsequenced, and a reverse genetics approach was used to clone a fega-co ... | 1996 | 8955412 |
| the isolation and characterisation of a gene encoding superoxide dismutase from bradyrhizobium sp. (parasponia) strain anu289. | bradyrhizobium sp. (parasponia) strain anu289 expresses a single mn-sod in both the vegetative and symbiotic states. a 500 bp sod-homologous sequence was amplified from genomic dna of strain anu289 using pcr. a 1.3 kb sali fragment was subsequently cloned which contained an orf, soda, encoding a 23 kd protein. this putative sod shares considerable homology with other mn-sods and analysis of the soda sequence predicts that it is expressed. a lacz-soda fusion complemented the sod-deficiency of e. ... | 1995 | 8595379 |
| cloning and sequence analysis of a novel insertion element from plasmids harbored by the carbofuran-degrading bacterium, sphingomonas sp. cfo6. | sphingomonas sp. cfo6 (a member of the alpha group of proteobacteria) was isolated from a washington soil by enrichment on the insecticide carbofuran as a sole source of carbon and energy. this strain has been shown to harbor five plasmids, at least some of which are required for catabolism of carbofuran. rearrangements, deletions, and loss of individual plasmids resulting in the loss of the carbofuran-degrading phenotype were observed following treatment with heat or introduction of tn5. severa ... | 1997 | 9200220 |
| bradyrhizobium japonicum does not require alpha-ketoglutarate dehydrogenase for growth on succinate or malate. | the suca gene, encoding the e1 component of alpha-ketoglutarate dehydrogenase, was cloned from bradyrhizobium japonicum usda110, and its nucleotide sequence was determined. the gene shows a codon usage bias typical of non-nif and non-fix genes from this bacterium, with 89.1% of the codons being g or c in the third position. a mutant strain of b. japonicum, lsg184, was constructed with the suca gene interrupted by a kanamycin resistance marker. lsg184 is devoid of alpha-ketoglutarate dehydrogenas ... | 1997 | 8981998 |
| genetic variability of the common nod gene in soybean bradyrhizobia isolated in thailand and japan. | to determine the taxonomic relationship between thai soybean bradyrhizobia and soybean bradyrhizobia from other regions, a total of 62 bradyrhizobium strains were isolated in thailand. the genetic diversity of the strains was examined with reference to 46 japanese and 15 usda strains. the degree of sequence divergence in and around common nod gene regions of the 123 strains was estimated by restriction fragment length polymorphism analysis using the bradyrhizobium japonicum usda 110 common noddy ... | 1996 | 8989861 |
| a novel transporter involved in cobalt uptake. | cobalt is an essential component of a low molecular-mass nitrile hydratase (l-nhase) from rhodococcus rhodochrous j1. we have found a new gene, nhlf, in the dna region sandwiched between nhlba encoding l-nhase and amda encoding amidase, which are involved in the degradation of nitriles. the product of nhlf, nhlf, shows a significant sequence similarity with those of hoxn from alcaligenes eutrophus, hupn from bradyrhizobium japonicum, nixa from helicobacter pylori, and ureh from bacillus sp., whi ... | 1997 | 8990157 |
| the bradyrhizobium japonicum coxwxyz gene cluster encodes a bb3-type ubiquinol oxidase. | bradyrhizobium japonicum, a symbiotic nitrogen-fixing bacterium, has a complex respiratory electron-transport chain, capable of functioning throughout a wide range of oxygen tensions. it does so by synthesizing a number of terminal oxidases, each appropriate for different environmental conditions. we have previously described the cloning of the large catalytic subunit, coxx, from one of the terminal oxidases from b. japonicum [surpin, m.a., moshiri, f., murphy, a.m. and maier, r.j. (1994) geneti ... | 1996 | 8996107 |
| isolation and classification of a family of cyclin gene homologues in lupinus luteus. | the lupine (lupinus luteus cv. ventus) cdna clones encoding homologues of cyclin (cycb1;2, cycb1;3, cycb1;4) have been isolated from cdna library prepared from roots inoculated with bradyrhizobium lupini. comparison of the deduced amino-acid sequences of cycb1;2, cycb1;3, cycb1;4 and previously described cycb1;1 (deckert et al. 1996, biochimie 78, 90-94) showed that they share 46-65% of identical amino acids. the presence of conserved residues (renaudin et. al., in the plant cell cycle, in the p ... | 1997 | 9241352 |
| the rhizobium meliloti puta gene: its role in the establishment of the symbiotic interaction with alfalfa. | little is known about the energy sources used by rhizobia during colonization, invasion and root nodule formation on leguminous plants. we have recently reported that an impaired proline metabolism in rhizobium meliloti leads to a reduced nodulation efficiency and competitiveness on alfalfa roots. in the present study we have characterized the r. meliloti proline dehydrogenase gene (puta) and addressed the question of its role in symbiosis. this rhizobial gene encodes a 1224-amino-acid-long poly ... | 1997 | 9004223 |
| the cytochrome bc1 complex but not cycm is necessary for symbiotic nitrogen fixation by rhizobium leguminosarum. | following tn5 mutagenesis of rhizobium leguminosarum biovar viciae, two mutants in one complementation group were identified as being unable to fix nitrogen in pea nodules. spectroscopic analysis revealed that the mutants had lowered levels of c-type cytochromes and cytochromes aa3, but increased levels of cytochrome d. cells of the mutants were greatly reduced in their ability to oxidize the artificial electron donor n,n,n',n'-tetramethyl-p-phenylenediamine but membranes prepared from them had ... | 1996 | 9004501 |
| characterization of two plasmid-borne lps beta loci of rhizobium etli required for lipopolysaccharide synthesis and for optimal interaction with plants. | in rhizobium etli cfn42, both the symbiotic plasmid (pd) and plasmid b (pb) are required for effective bean nodulation. this is due to the presence on pb of a region (lps beta) involved in lipopolysaccharide (lps) biosynthesis. we report here the genetic array and functional features of this plasmid-borne region. the sequence analysis of a 3,595-bp fragment revealed the presence of a transcriptional unit integrated by two open reading frames (lps beta 1 and lps beta 2) essential for lps biosynth ... | 1997 | 9304861 |
| cyclolaminarinose. a new biologically active beta-(1-->3) cyclic glucan. | a unique glucan has been isolated from a recombinant strain of a rhizobium meliloti ty7, a cyclic beta-(1-->2) glucan mutant carrying a locus specifying beta-(1-->3; 1-->6) glucan synthesis from bradyrhizobium japonicum usda110. this compound, which appears to have considerable hydrophobic affinity, was separated from a perchloric acid cell extract by adsorption to a c-18 silica column. unlike those cyclic glucans previously isolated from rhizobium meliloti or bradyrhizobium japonicum, this mole ... | 1996 | 9008841 |
| characterization of the bradyrhizobium japonicum cycy protein, a membrane-anchored periplasmic thioredoxin that may play a role as a reductant in the biogenesis of c-type cytochromes. | a new member of membrane-anchored periplasmic thioredoxin-like proteins was identified in bradyrhizobium japonicum. it is the product of cycy, the last gene in a cluster of cytochrome c biogenesis genes. mutational analysis revealed that cycy is essential for the biosynthesis of all c-type cytochromes in this bacterium. the cycy protein was shown to be exported to the periplasm by its n-terminal signal sequence-like domain. results from western blot analyses of membrane and soluble fractions ind ... | 1997 | 9020171 |
| a hydrogen-sensing system in transcriptional regulation of hydrogenase gene expression in alcaligenes species. | heterologous complementation studies using alcaligenes eutrophus h16 as a recipient identified a hydrogenase-specific regulatory dna region on megaplasmid phg21-a of the related species alcaligenes hydrogenophilus. nucleotide sequence analysis revealed four open reading frames on the subcloned dna, designated hoxa, hoxb, hoxc, and hoxj. the product of hoxa is homologous to a transcriptional activator of the family of two-component regulatory systems present in a number of h2-oxidizing bacteria. ... | 1997 | 9045826 |
| identification of the lrp gene in bradyrhizobium japonicum and its role in regulation of delta-aminolevulinic acid uptake. | the heme precursor delta-aminolevulinic acid (ala) is taken up by the dipeptide permease (dpp) system in escherichia coli. in this study, we identified a bradyrhizobium japonicum genomic library clone that complemented both ala and dipeptide uptake activities in e. coli dpp mutants. the complementing b. japonicum dna encoded a product with 58% identity to the e. coli global transcriptional regulator lrp (leucine-responsive regulatory protein), implying the presence of dpp-independent ala uptake ... | 1997 | 9045849 |
| purification and characterization of the nadp-malic enzyme from bradyrhizobium japonicum a1017. | an nadp-malic enzyme [ec 1.1.1.40] was purified to homogeneity from bradyrhizobium japonicum a1017, and the molecular and physiological characteristics were surveyed. the molecular mass of one subunit of the purified enzyme was evaluated to be 77,600 da by sds-page, and the native enzyme was a tetramer in ph 7.0 and dimer in ph 8.0 conditions, showing complex oligomeric characteristics corresponding to ph value. | 1997 | 9058984 |
| the sequence of a symbiotically essential bradyrhizobium japonicum operon consisting of trpd, trpc and a moac-like gene. | the 2767 bp bamhi-hindiii fragment specifying the trpdc genes of b. japonicum i-110 was sequenced. the trpd and trpc genes each have three highly conserved 'crawford' consensus sequences and are part of an operon with three open reading frames (orfs). the third orf has a predicted product with 58% amino-acid sequence identity with the gene product of e. coli moac, a gene encoding an enzyme involved in biosynthesis of the molybdenum cofactor required for the activity of nitrate reductase and othe ... | 1997 | 9061023 |
| a tnphoa insertion within the bradyrhizobium japonicum sips gene, homologous to prokaryotic signal peptidases, results in extensive changes in the expression of pbm-specific nodulins of infected soybean (glycine max) cells. | bradyrhizobium japonicum mutant 132 was obtained by random tnphoa mutagenesis of strain 110spc4. a 6.5 kb bamhi kanamycin-resistance-coding dna fragment of mutant 132 was used as a hybridization probe to clone the corresponding wild-type fragment. dna sequence analysis of a 3213 bp bamhi-clai fragment revealed that three open reading frames (orfs) were encoded in the same orientation. based on sequence similarities to other proteins in the database, the second orf was called sips (signal peptida ... | 1995 | 8825087 |
| histidine 131, not histidine 43, of the bradyrhizobium japonicum fixn protein is exposed towards the periplasm and essential for the function of the cbb3-type cytochrome oxidase. | in subunit i (fixn) of the bradyrhizobium japonicum cbb3-type oxidase, only five instead of the normal six strictly conserved histidines (h) could be unambiguously assigned as the putative heme or copper ligands. the ambiguity concerned h43 or h131 as the presumptive n-terminal ligands of the low-spin heme b. we report here that a h43a replacement had a wild-type phenotype, whereas the h131a mutant was defective in oxidase function and subunit assembly or stability, suggesting that h131 serves a ... | 1996 | 8830672 |
| the hydrogenase gene cluster of rhizobium leguminosarum bv. viciae contains an additional gene (hypx), which encodes a protein with sequence similarity to the n10-formyltetrahydrofolate-dependent enzyme family and is required for nickel-dependent hydrogenase processing and activity. | plasmid pal618 contains the genetic determinants for h2 uptake (hup) from rhizobium leguminosarum bv. viciae, including a cluster of 17 genes named hupslcdefghijk-hypabfcde. a 1.7-kb segment of insert dna located downstream of hype has now been sequenced, thus completing the sequence of the 20441-bp insert dna in plasmid pal618. an open reading frame (designated hypx) encoding a protein with a calculated m(r) of 62300 that exhibits extensive sequence similarity with hoxx from alcaligenes eutroph ... | 1996 | 8842143 |
| hoxa is a transcriptional regulator for expression of the hup structural genes in free-living bradyrhizobium japonicum. | a chromosomally integrated bradyrhizobium japonicum hoxa mutant is unable to oxidize hydrogen in free-living conditions. derepressing conditions that induce hydrogenase activity in free-living, wild-type b. japonicum cells cannot induce expression of the hydrogenase structural genes in the hoxa mutant. the dna-binding capacity of hoxa at the hup promoter region was studied by means of gel retardation. both heterotrophically growing cells and cells induced to express hydrogenase activity contain ... | 1997 | 9076733 |
| the dnakj operon belongs to the sigma32-dependent class of heat shock genes in bradyrhizobium japonicum. | the dnakj genes of bradyrhizobium japonicum were cloned and sequenced. they map adjacent to each other, as in other proteobacteria of the alpha and gamma subgroups. primer extension experiments identified two strongly heat-inducible transcripts starting 99 bp (t1) and 204 bp (t2) upstream of dnak. synthesis of the shorter transcript t1 in escherichia coli required the presence of a recently characterized sigma32 homologue (rpoh1) from b. japonicum. the -35 and -10 regions of the promoters associ ... | 1997 | 9108282 |
| bacterial nodulation protein nodz is a chitin oligosaccharide fucosyltransferase which can also recognize related substrates of animal origin. | the nodz gene, which is present in various soil bacteria such as bradyrhizobium japonicum, azorhizobium caulinodans, and rhizobium loti, is involved in the addition of a fucosyl residue to the reducing n-acetylglucosamine residue of lipochitin oligosaccharide (lco) signal molecules. using an escherichia coli strain that produces large quantities of the nodz protein of b. japonicum, we have purified the nodz protein to homogeneity. the purified nodz protein appears to be active in an in vitro tra ... | 1997 | 9113990 |
| replacement of pro109 by his in tlpa, a thioredoxin-like protein from bradyrhizobium japonicum, alters its redox properties but not its in vivo functions. | tlpa, the membrane-anchored, thioredoxin-like protein from bradyrhizobium japonicum, is essential for cytochrome aa3 biogenesis. the periplasmic domain of tlpa was previously shown to have protein thiol:disulfide oxidoreductase activity and reducing properties similar to those of cytoplasmic thioredoxins. here, we replaced the proline-109 in its active-site sequence c107 v108 p109 c110 by a histidine residue. the resulting active-site motif (cvhc) resembles that of oxidizing thiol:disulfide oxid ... | 1997 | 9136895 |
| three disparately regulated genes for sigma 32-like transcription factors in bradyrhizobium japonicum. | bradyrhizobium japonicum possesses a subclass of heat-shock genes whose members are transcribed from a sigma 32 consensus promoter. having identified previously one gene (rpoh1) encoding a sigma 32-like rna polymerase transcription factor, we report here the characterization of two additional rpoh-like genes (rpoh2 and rpoh3). b. japonicum thus represents the first example of an organism possessing an rpoh multigene family. all three rpoh genes encode functional proteins that are able to initiat ... | 1997 | 9140968 |
| the hypb protein from bradyrhizobium japonicum can store nickel and is required for the nickel-dependent transcriptional regulation of hydrogenase. | the hypb protein from bradyrhizobium japonicum is a metal-binding gtpase required for hydrogenase expression. in-frame mutagenesis of hypb resulted in strains that were partially or completely deficient in hydrogenase expression, depending on the degree of disruption of the gene. complete deletion of the gene yielded a strain (jh delta eg) which lacked hydrogenase activity under all conditions tested, including the situation as bacteroids from soybean nodules. mutant strain jh delta 23h lacking ... | 1997 | 9140970 |
| squalene-hopene cyclase from bradyrhizobium japonicum: cloning, expression, sequence analysis and comparison to other triterpenoid cyclases. | with the help of a pcr-based screening method, the gene encoding squalenehopene cyclase (shc) of bradyrhizobium japonicum usda 110 was isolated from a cosmid library. the shc catalyses the cyclization of squalene to hopanoids, a class of triterpenoid lipids recently discovered in nitrogen-fixing, root-nodule-forming bradyrhizobium bacteria. hybridization experiments showed that the gene is present in bacteria of all bradyrhizobium strains tested and in photosynthetic bacteria forming stem nodule ... | 1997 | 9141686 |
| transcriptional regulation of delta-aminolevulinic acid dehydratase synthesis by oxygen in bradyrhizobium japonicum and evidence for developmental control of the hemb gene. | an increased demand for cytochromes is associated with symbiotic development and microaerobic metabolism in the bacterium bradyrhizobium japonicum, and evidence suggests that hemb, rather than hema, is the first essential bacterial heme synthesis gene in symbiosis with soybean. steady-state levels of mrna and protein encoded by hemb were strongly and rapidly induced by o2 deprivation as determined by rnase protection and immunoblot analyses, but hemh message was not induced. oxygen limitation re ... | 1997 | 9171420 |
| pristine environments harbor a new group of oligotrophic 2,4-dichlorophenoxyacetic acid-degrading bacteria. | 2,4-dichlorophenoxyacetic acid (2,4-d)-degrading bacteria were isolated from pristine environments which had no history of 2,4-d exposure. by using 2,4-d dye indicator medium or 14c-labeled 2,4-d medium, six strains were isolated from eight enrichment cultures capable of degrading 2,4-d. phylogenetic analyses based on 16s ribosomal dna (rdna) sequencing and physiological properties revealed that one isolate from hawaiian volcanic soil could be classified in the genus variovorax (a member of the ... | 1997 | 9172346 |
| genetic evidence for 5-aminoimidazole-4-carboxamide ribonucleotide (aicar) as a negative effector of cytochrome terminal oxidase cbb3 production in rhizobium etli. | a rhizobium etli tn5mob-induced mutant (cfn035) exhibits an enhanced capacity to oxidize n,n,n',n', tetramethyl-p -phenylenediamine (tmpd), a presumptive indicator of elevated cytochrome c terminal oxidase activity. sequencing of the mutated gene in cfn035 revealed that it codes for the amidophosphoribosyl transferase enzyme (purf) that catalyzes the first step in the purine biosynthetic pathway. two c-type cytochromes with molecular weights of 32 and 27 kda were produced in strain cfn035, which ... | 1997 | 9202382 |