isolation and characterization of rhizobitoxine mutants of bradyrhizobium explore the role of rhizobitoxine in bradyrhizobium-legume symbiosis, 11 rhizobitoxine mutants of b. japonicum usda61 were isolated on the basis of their inability to synthesize the toxin in culture. each mutant is prototrophic and symbiotically effective on soybean, cowpea, siratro, and glycine soja. the rhizobitoxine mutants differ in their chlorosis phenotypes and rhizobitoxine production in planta. as expected, one group of mutant fail to make toxin in planta, resulting in the absence of ...19921317377
dissociation by nh4cl treatment of the enzymic activities of glutamine synthetase ii from rhizobium leguminosarum biovar viceae.glutamine synthetase ii (gsii) was purified to homogeneity from rhizobium leguminosarum biovar viceae and characterized. the sequence of 26 amino acid residues from the amino-terminal end of the protein showed high similarity with the sequence of gsii from bradyrhizobium japonicum or from rhizobium meliloti. non-denaturing page showed that gsii, either in crude extracts or in the pure state, was a mixture of an octamer and a tetramer and that under specific conditions the octamer/tetramer ratio ...19921355107
phylogeny of fast-growing soybean-nodulating rhizobia support synonymy of sinorhizobium and rhizobium and assignment to rhizobium fredii.we determined the sequences for a 260-base segment amplified by the polymerase chain reaction (corresponding to positions 44 to 337 in the escherichia coli 16s rrna sequence) from seven strains of fast-growing soybean-nodulating rhizobia (including the type strains of rhizobium fredii chemovar fredii, rhizobium fredii chemovar siensis, sinorhizobium fredii, and sinorhizobium xinjiangensis) and broad-host-range rhizobium sp. strain ngr 234. these sequences were compared with the corresponding pre ...19921371066
identification and cloning of bradyrhizobium japonicum genes expressed strain selectively in soil and rhizosphere.the growth of bradyrhizobium japonicum usda 110 and usda 438 in soil extract-supplemented medium led to transcription of a large amount of dna not expressed in basal medium. strain usda 438 was more competitive for the nodulation of soybean than strain usda 110. to identify and isolate dna regions which were expressed specifically in strain usda 438 but not in strain usda 110 in response to soil extract or soybean root exudate, we developed a subtractive rna hybridization procedure. several cosm ...19921377899
evidence for a close genealogical relationship between afipia (the causal organism of cat scratch disease), bradyrhizobium japonicum and blastobacter denitrificans.the primary structures of the small subunit rrna of bradyrhizobium japonicum and blastobacter denitrificans were determined by direct sequencing of enzymatically amplified dna. comparative sequence analysis revealed that bradyrhizobium japonicum and blastobacter denitrificans are members of the alpha-2 subgroup of the proteobacteria and show a very close phylogenetic relationship with the genus afipia.19921383084
siderophore and organic acid production in root nodule bacteria.nineteen strains of root nodule bacteria were grown under various iron regimes (0.1, 1.0 and 20 microm added iron) and tested for catechol and hydroxamate siderophore production and the excretion of malate and citrate. the growth response of the strains to iron differed markedly. for 12 strains (bradyrhizobium strains nc92b and 32h1, b. japonicum usda110 and cb1809, b. lupini wu8, cowpea rhizobium ngr234, rhizobium meliloti strains u45 and cc169, rhizobium leguminosarum bv viciae wu235 and rhizo ...19921387306
a succinate transport mutant of bradyrhizobium japonicum forms ineffective nodules on soybeans.biochemical evidence has shown that dicarboxylic acids actively support symbiotic nitrogen fixation by both fast- and slow-growing rhizobium. mutants defective in the active uptake of succinate have been previously described only in species of the fast-growing rhizobium. this article is a report on the isolation of mutants defective in dicarboxylate transport in a slow-growing species of rhizobium, bradyrhizobium japonicum. one of these presumptive dicarboxylate transport mutants, gts, was chara ...19921393826
structures of the oligosaccharides obtained from the core regions of the lipopolysaccharides of bradyrhizobium japonicum 61a101c and its symbiotically defective lipopolysaccharide mutant, js314.the only core oligosaccharide released from the lipopolysaccharide (lps) of bradyrhizobium japonicum 61a101c by prolonged (5 h) mild hydrolysis with acid, and the major core oligosaccharide obtained from its symbiotic and lps-defective mutant, js314, was the trisaccharide alpha-d-man p-(1----4)-alpha-d-glc p-(1----4)-2,7-anhydro-alpha-kdof. the 2,7-anhydro-3-deoxy-alpha-d-manno-2- octulofuranosonic acid moiety was probably formed during the prolonged mild hydrolysis with acid. a disaccharide cor ...19921394315
role of integration host factor in stimulating transcription from the sigma 54-dependent nifh a wide variety of nitrogen-fixing organisms among the purple bacteria (large division of gram-negative bacteria) the nitrogen fixation (nif) operons are transcribed by an alternative holoenzyme form of rna polymerase, sigma 54-holoenzyme. transcription depends on the activator protein nifa (nitrogen fixation protein a), which catalyzes isomerization of closed complexes between this polymerase and a promoter to transcriptionally productive open complexes. nifa-mediated activation of transcript ...19921404379
structural and functional analysis of two different nodd genes in bradyrhizobium japonicum usda110.bradyrhizobium japonicum has two closely linked homologs of the nodulation regulatory gene, nodd; these homologs are located upstream of and in divergent orientation to the nodyabcsuij gene cluster. we report here the nucleotide sequence and mutational analyses of both nodd copies. the predicted nodd1 and nodd2 proteins shared 62% identical amino acid residues at corresponding positions and exhibited different degrees of homology with nodd proteins of other bradyrhizobium, azorhizobium, and rhiz ...19921421512
[the growth of some bradyrhizobium strains in uremic conditions in the presence of antimicrobial substances].the growth rate of bradyrhizobium japonicum usda 110 and its strr and ampr mutant strains (resistant to streptomycin and ampicillin respectively), as well as tal 945 and tal 946, tal 947 (mutants of usda 110 and usda 138 respectively) on yeast extract mannitol agar (yema) containing different concentrations of crystal violet and brilliant green. according to our results only the growth of bacillus megaterium b17 was effected from crystal violet while the others were not effected from both of dye ...19921435367
genes for a second terminal oxidase in bradyrhizobium japonicum.bradyrhizobium japonicum possesses a mitochondria-like respiratory chain terminating with an aa3-type cytochrome c oxidase. the gene for subunit i of this enzyme (coxa) had been identified and cloned previously via heterologous hybridization using a paracoccus denitrificans dna probe. in the course of these studies, another b. japonicum dna region was discovered which apparently encoded a second terminal oxidase that was different from cytochrome aa3 but also belonged to the superfamily of heme/ ...19921444719
the rhizobium, bradyrhizobium, and azorhizobium nodc proteins are homologous to yeast chitin synthases.the nodabc genes of rhizobia are essential for the synthesis of lipo-oligosaccharidic (n-acylated chitin oligomers) nodulation signals. nodc gene products from rhizobium, bradyrhizobium, and azorhizobium exhibit extensive homology with chitin synthases, suggesting that the nodc proteins are involved in the synthesis of the chitin oligomer backbone by catalyzing the beta-1,4-linkage between n-acetyl-d-glucosamine residues.19921472721
analysis of dna sequences transcribed at high levels in bradyrhizobium japonicum bacteroids but not necessary for symbiotic effectiveness.five regions of the bradyrhizobium japonicum genome, which are transcribed at high levels in nitrogen-fixing soybean (glycine max) nodules, were identified. none of these regions contained previously identified genes (e.g., nif, nod, and fix genes) that are known to be essential for development of functional nitrogen-fixing nodules. to assess the role of these regions in the development of the b. japonicum-soybean symbiosis, we cloned and used them to construct b. japonicum strains, in which lar ...19921515666
structural studies of a phosphocholine substituted beta-(1,3);(1,6) macrocyclic glucan from bradyrhizobium japonicum usda our previous in vivo 31p study of intact nitrogen-fixing nodules (rolin, d.b., boswell, r.t., sloger, c., tu, s.i. and pfeffer, p.e., 1989 plant physiol. 89, 1238-1246), we observed an unknown phosphodiester. the compound was also observed in the spectra of isolated bacteroids as well as extracts of the colonizing bradyrhizobium japonicum usda 110. in order to characterize the phosphodiester in the present study, we took advantage of the relatively hydrophobic nature of the material and purif ...19921610877
isoliquiritigenin, a strong nod gene- and glyceollin resistance-inducing flavonoid from soybean root exudate.isoflavonoid signal molecules from soybean (glycine max (l.) merr.) seed and root exudate induce the transcription of nodulation (nod) genes in bradyrhizobium japonicum. in this study, a new compound with symbiotic activity was isolated from soybean root exudate. the isolated 2',4',4-trihydroxychalcone (isoliquiritigenin) is characterized by its strong inducing activity for the nod genes of b. japonicum. these genes are already induced at concentrations 1 order of magnitude below those required ...19921622242
hyperreiterated dna regions are conserved among bradyrhizobium japonicum serocluster 123 strains.we have identified and cloned two dna regions which are highly reiterated in bradyrhizobium japonicum serocluster 123 strains. while one of the reiterated dna regions, pfr2503, is closely linked to the b. japonicum common and genotype-specific nodulation genes in strain usda 424, the other, pmap9, is located next to a tn5 insertion site in a host-range extension mutant of b. japonicum usda 438. the dna cloned in pfr2503 and pmap9 are reiterated 18 to 21 times, respectively, in the genomes of b. ...19921622264
characterization of a bradyrhizobium japonicum ferrochelatase mutant and isolation of the hemh gene.a tn5-induced mutant of bradyrhizobium japonicum, strain lorbf1, was isolated on the basis of the formation of fluorescent colonies, and stable derivatives were constructed in backgrounds of strains lo and i110. the stable mutant strains loek4 and i110ek4 were strictly dependent upon the addition of exogenous hemin for growth in liquid culture and formed fluorescent colonies. the fluorescent compound was identified as protoporphyrin ix, the immediate precursor of protoheme. cell extracts of stra ...19921624416
characterization of a soluble catalase-peroxidase hemoprotein b-590, previously identified as 'cytochrome alpha 1' from bradyrhizobium japonicum bacteroids.the cytochrome "a1" or p-428, previously proposed to be a high affinity terminal oxidase in nitrogen-fixing bacteroids of bradyrhizobium japonicum has been purified. the water-soluble native hemoprotein has an mr of 136,000, lacks heme a and is a high-spin ferric protohemoprotein: it is slowly reduced with dithionite to give a species with an optical spectrum like that of hemoprotein b-590 (escherichia coli; peak at 555 nm, shoulder at 590 nm), and which reacts slowly with co. it has catalase an ...19911645695
polygalacturonase is a virulence factor in agrobacterium tumefaciens biovar 3.agrobacterium tumefaciens biovar 3 causes both crown gall and root decay of grapes. all biovar 3 strains, regardless of their tumorigenicity, produce in culture a single polygalacturonase with a pi around 4.5. a. tumefaciens biovar 3 strain cg49 was mutagenized with tn5 by using psup2021 as a suicide vector. a mutant strain, cg50, lacking polygalacturonase activity was isolated. the mutation was due to a single tn5 insertion in an 8.5-kb ecori fragment that also contained the polygalacturonase s ...19911655716
the bradyrhizobium japonicum cycm gene encodes a membrane-anchored homolog of mitochondrial cytochrome c.mitochondrial cytochrome c is a water-soluble protein in the intermembrane space which catalyzes electron transfer from the cytochrome bc1 complex to the terminal oxidase cytochrome aa3. in bradyrhizobium japonicum, a gene (cycm) which apparently encodes a membrane-anchored homolog of mitochondrial cytochrome c was discovered. the apoprotein deduced from the nucleotide sequence of the cycm gene consists of 184 amino acids with a calculated mr of 19,098 and an isoelectric point of 8.35. at the n- ...19911657867
identification of a novel composite transposable element, tn5280, carrying chlorobenzene dioxygenase genes of pseudomonas sp. strain p51.analysis of one of the regions of catabolic plasmid pp51 which encode chlorobenzene metabolism of pseudomonas sp. strain p51 revealed that the tcba and tcbb genes for chlorobenzene dioxygenase and dehydrogenase are located on a transposable element, tn5280. tn5280 showed the features of a composite bacterial transposon with iso-insertion elements (is1066 and is1067) at each end of the transposon oriented in an inverted position. when a 12-kb hindiii fragment of pp51 containing tn5280 was cloned ...19911657878
characterization of cytochromes c550 and c555 from bradyrhizobium japonicum: cloning, mutagenesis, and sequencing of the c555 gene (cycc).the major soluble c-type cytochromes in cultured cells of bradyrhizobium japonicum usda 110 comprised a co-reactive c555 (mr, approximately 15,500) and a non-co-reactive c550 (mr, approximately 12,500). levels of cytochrome per gram of soluble protein in aerobic, anaerobic, and symbiotic cells were 32, 21, and 30 nmol, respectively, for c555 and 31, 44, and 65 nmol, respectively, for c550. the midpoint redox potentials (em,7) of the purified cytochromes were +236 mv for c555 and +277 mv for c550 ...19911660457
discovery of a rhizobial rna that is essential for symbiotic root nodule development.all of the azorhizobium, bradyrhizobium, and rhizobium genes known to be involved in the development of nitrogen-fixing legume root nodules are genes that code for proteins. here we report the first exception to this rule: the sra gene; it was discovered during the genetic analysis of a bradyrhizobium japonicum tn5 mutant (strain 259) which had a severe deficiency in colonizing soybean nodules. a dna region as small as 0.56 kb cloned from the parental wild type restored a wild-type phenotype in ...19911717438
16s rrna sequences of bartonella bacilliformis and cat scratch disease bacillus reveal phylogenetic relationships with the alpha-2 subgroup of the class proteobacteria.the primary structures of 16s rrnas of bartonella bacilliformis, an isolate of the cat scratch disease (csd) bacillus, and a strain phenotypically similar to the csd bacillus were determined by reverse transcriptase sequencing. these microorganisms were found to be members of the alpha-2 subgroup of the class proteobacteria. the sequence from b. bacilliformis was most closely related to the rrna of rochalimaea quintana (91.7% homology), the etiologic agent of trench fever. the sequence from the ...19911719021
chemotaxis of bradyrhizobium japonicum to soybean exudates.the chemotactic response of bradyrhizobium japonicum toward soybean seed and root exudates was examined. assays using various isoflavones and fractionated exudate indicated that isoflavones are not the principal attractants in exudates. likewise, induction of nod genes with isoflavones or seed exudate before assay did not enhance chemotaxis. screening of numerous compounds revealed that only dicarboxylic acids and the amino acids glutamate and aspartate were strong attractants. the presence of g ...19911768137
molecular cloning of a gene region from bradyrhizobium japonicum essential for lipopolysaccharide synthesis.the gene region cloned from a lipopolysaccharide (lps) mutant carrying the tn5 and flanking dna sequences was used as a probe to screen a gene bank prepared from wild-type bradyrhizobium japonicum strain 61a101c and to isolate the corresponding wild-type lps-gene region. by cross-hybridization experiments the lps-gene region did not appear to be closely linked to previously cloned nodulation genes. a detailed restriction map of the lps-gene region (5.5-kb ecori genomic fragment) was established ...19911769537
identification of a nifa-like regulatory gene of azospirillum brasilense sp7 expressed under conditions of nitrogen fixation and in the presence of air and ammonia.a gene bank of azospirillum lipoferum br17 constructed in the vector lambda gem11 was screened with a bradyrhizobium japonicum nifa gene probe. a 7.3 kb ecori fragment carrying a nifa-like gene was thereby isolated and subsequently used to screen a gene bank of azospirillum brasilense sp7 constructed in puc18. two ecori fragments of 5.6 kb and 3.6 kb covering the nifa-homology region were found. mutants with nif- phenotype were obtained by site-directed tn5 mutagenesis of the 5.6 kb fragment and ...19911779763
structure and expression of the chlorobium vibrioforme hema gene.the green sulfur bacterium, chlorobium vibrioforme, synthesizes the tetrapyrrole precursor, delta-aminolevulinic acid (ala), from glutamate via the rna-dependent five-carbon pathway. a 1.9-kb clone of genomic dna from c. vibrioforme that is capable of transforming a glutamyl-trna reductase-deficient, ala-dependent, hema mutant of escherichia coli to prototrophy was sequenced. the transforming c. vibrioforme dna has significant sequence similarity to the e. coli, salmonella typhimurium, and bacil ...19911793335
a lipopolysaccharide mutant of bradyrhizobium japonicum that uncouples plant from bacterial differentiation.the tn5-containing fragment from a non-nodulating mutant of bradyrhizobium japonicum, strain ml142, was introduced into b. japonicum strain 61a101c by marker exchange to construct strain js314. strain js314 failed to nodulate several soybean varieties tested. however, on a few varieties nodulelike structures were induced to a frequency of 54% of the plants inoculated. the ultrastructure of these nodules was studied in detail by light and electron microscopy. the nodules were devoid of internal b ...19911799697
codon usage and g + c content in bradyrhizobium japonicum genes are not date, the sequences of 45 bradyrhizobium japonicum genes are known. this provides sufficient information to determine their codon usage and g + c content. surprisingly, b. japonicum nodulation and nifa-regulated genes were found to have a less biased codon usage and a lower g + c content than genes not belonging to these two groups. thus, the coding regions of nodulation genes and nifa-regulated genes could hardly be identified in codon preference plots whereas this was not difficult with oth ...19911793334
repetitive sequences with homology to bradyrhizobium japonicum dna and the t-dna of agrobacterium rhizogenes are closely linked to nodabc of rhizobium fredii usda257.we have detected strong homology between a 9.2-kb ecori restriction fragment from rhizobium fredii usda257 that contains nodabc and eight additional ecori fragments in dna digests from this organism. a series of repetitive sequences responsible for this hybridization lies within a 0.95-kb hindiii/sali subfragment about 1-kb upstream of noda. this subfragment also hybridizes to multiple restriction fragments from nine other strains of r. fredii, but only one is common to all strains. the 0.95-kb ...19911799702
a novel membrane-bound glucosyltransferase from bradyrhizobium japonicum.bacteria within the family rhizobiaceae are distinguished by their ability to infect higher plants. the cell envelope carbohydrates of these bacteria are believed to be involved in the plant infection process. one class of cell envelope carbohydrate, the cyclic beta-1,2-glucans, is synthesized by species within two genera of this family, agrobacterium and rhizobium. in contrast, species of the genus bradyrhizobium, a third genus within this family, appear to lack the capacity for cyclic beta-1,2 ...19911829727
nodules elicited by rhizobium meliloti heme mutants are arrested at an early stage of development.heme-deficient mutants of rhizobium and bradyrhizobium have been found to exhibit diverse phenotypes with respect to symbiotic interactions with plant hosts. we observed that r. meliloti hema mutants elicit nodules that do not contain intracellular bacteria; the nodules contain either no infection threads ("empty" nodule phenotype) or aberrant infection threads that failed to release bacteria (bar- phenotype). these mutant nodules expressed nodulin genes associated with nodules arrested at an ea ...19911766439
bradyrhizobium japonicum nodd1 can be specifically induced by soybean flavonoids that do not induce the nodyabcsuij operon.besides genistein and daidzein, which are active inducers of the nodyabcsuij operon in bradyrhizobium japonicum, soybean seeds also excrete compounds that are not inducers of the nodyabcsuij genes but enhance induction of this operon in the presence of a suboptimal genistein concentration. this synergism was studied in detail, and specific compounds were identified in seed exudate which specifically induce the nodd1 gene but not the nodyabcsuij operon. therefore, our current hypothesis is that t ...19921730597
studies of the bradyrhizobium japonicum nodd1 promoter: a repeated structure for the nod box.induction of nod genes in rhizobium and bradyrhizobium species is dependent on the presence of plant-produced flavonoids, the nodd protein, and the cis-acting nod box promoter sequence. although the nodd (nodd1) gene in rhizobium species is constitutively expressed, nodd1 expression in bradyrhizobium japonicum is inducible by isoflavones in a manner similar to that of the nodyabc operon. a consensus nod box sequence is found 5' of the nodyabc operon, whereas a presumptive, nod box-like sequence ...19911675210
nucleotide sequence of the fixabc region of azorhizobium caulinodans ors571: similarity of the fixb product with eukaryotic flavoproteins, characterization of fixx, and identification of nifw.the nucleotide sequence of a 4.1 kb dna fragment containing the fixabc region of azorhizobium caulinodans was established. the three gene products were very similar to the corresponding polypeptides of rhizobium meliloti. the c-terminal domains of both fixb products displayed a high degree of similarity with the alpha-subunits of rat and human electron transfer flavoproteins, suggesting a role for the fixb protein in a redox reaction. two open reading frames (orf) were found downstream of fixc. ...19911850088
cloning, sequencing and mutational analysis of the cytochrome c552 gene (cycb) from bradyrhizobium japonicum strain 110.we report the cloning and nucleotide sequence analysis of the cytochrome c552 gene (cycb) of bradyrhizobium japonicum strain 110. the gene was identified with help of an oligonucleotide that was designed on the basis of the amino acid sequence determined for purified cytochrome c552 of b. japonicum strain cc705. the cycb gene product has an n-terminal 23-amino acid signal peptide that is missing in the mature cytochrome c552 protein. a b. japonicum cycb insertion mutant was constructed which had ...19911663888
oxygen-dependent catabolism of indole-3-acetic acid in bradyrhizobium japonicum.some strains of bradyrhizobium japonicum have the ability to catabolize indole-3-acetic acid (iaa). examination of this catabolism in strain 110 by in vivo experiments has revealed an enzymatic activity catalyzing the degradation of iaa and 5-hydroxy-indole-3-acetic acid. the activity requires addition of the substrates for induction and is oxygen dependent. the highest activity is obtained when the concentration of inducer is 0.2 mm. spectrophotometric data are consistent with the suggestion th ...19911856182
characterization of three soluble c-type cytochromes isolated from soybean root nodule bacteroids of bradyrhizobium japonicum strain cc705.three soluble, low molecular mass cytochromes c (mr 8000-15,000) were isolated and purified from soybean root nodule bacteroids of bradyrhizobium japonicum strain cc705. on the basis of their alpha: absorbance peaks in the reduced forms, they were named cytochromes c550, c552 and c555. cytochrome c552 reacted very fast, c555 very slowly and c550 not at all with carbon monoxide. the complete amino acid sequence (73 residues) of cytochrome c552 was established which identifies it as a monoheme, cl ...19911663887
from one gene to two proteins: the biogenesis of cytochromes b and c1 in bradyrhizobium japonicum.genes coding for polyproteins that are cleaved posttranslationally into two or more functional proteins are rarely found in prokaryotes. one example concerns the biogenesis of the bradyrhizobium japonicum cytochromes b and c1, two of the three constituent subunits of ubiquinol-cytochrome-c reductase (ubiquinol:ferricytochrome-c oxidoreductase, ec; the respective apoproteins for these subunits are encoded by the 5' and 3' halves of a single gene, fbch. these two halves are linked by an ...19911647023
rapid and sensitive assay for the phytotoxin rhizobitoxine.rhizobitoxine is a phytotoxin synthesized by some strains of the legume symbiont genus bradyrhizobium and the plant pathogen pseudomonas andropogonis. we demonstrate here a new enzymatic assay which is 100-fold more sensitive than previous assays and can detect as little as 1.0 pmol of rhizobitoxine. the assay is based on the inhibition of salmonella typhimurium beta-cystathionase by rhizobitoxine. interestingly, beta-cystathionase from bradyrhizobium japonicum is insensitive to rhizobitoxine at ...19911892399
functional analysis of the cysteine motifs in the ferredoxin-like protein fdxn of rhizobium meliloti involved in symbiotic nitrogen fixation.the rhizobium meliloti fdxn gene, which is part of the nifa-nifb-fdxn operon, is absolutely required for symbiotic nitrogen fixation. the deduced sequence of the fdxn protein is characterized by two cysteine motifs typical of bacterial-type ferredoxins. the fix-phenotype of an r. meliloti fdxn::[tc] mutant could be rescued by the r. leguminosarum fdxn gene, whereas no complementation was observed with nif-associated genes encoding ferredoxins from bradyrhizobium japonicum, azotobacter vinelandii ...19921603075
elevated levels of stress proteins associated with bacterial symbiosis in amoeba proteus and soybean root nodule cells.obligatory bacterial endosymbionts of amoeba proteus and symbiotic bradyrhizobium japonicum bacteroids in soybean-root nodules contained large amounts of 67-kda and 65-kda proteins, respectively, antigenically related to groel of e. coli and the 58-kda heat-shock protein of tetrahymena. monoclonal antibodies against the 67-kda protein recognized groel analogs from several different organisms. the quantity of the stress protein in symbiotic b. japonicum bacteroids was augmented seven times that i ...19911912387
detection and separation of rhizobium and bradyrhizobium nod metabolites using thin-layer chromatography.using radioactive acetate as a precursor, it was shown that the common nodabc genes of rhizobium and bradyrhizobium strains are involved in the production of one or more metabolites that are excreted into the growth medium. a rapid thin-layer chromatography (tlc) system has been developed to separate these so-called nod metabolites that can then be visualized by autoradiography. different patterns of nod metabolites were observed in the tested strains of the cross-inoculation groups of r. legumi ...19921600238
purification and properties of acetyl-coa synthetase from bradyrhizobium japonicum bacteroids.acetyl-coa synthetase was purified 800-fold from bradyrhizobium japonicum bacteroids. a specific activity of 16 mumol/min per mg of protein was achieved, with a 30-40% yield. the purification scheme consisted of only three consecutive chromatography steps. the enzyme has a native mr of 150,000, estimated by gel-permeation chromatography, and a subunit mr of 72,000, determined by sds/polyacrylamide-gel electrophoresis. the optimum ph and temperature are 8.5 and 50 degrees c respectively. the km v ...19901970239
characterization of a fixlj-regulated bradyrhizobium japonicum gene sharing similarity with the escherichia coli fnr and rhizobium meliloti fixk genes.we describe the cloning, sequencing, regulation, and mutational analysis of a bradyrhizobium japonicum fixk-like gene whose product belongs to the family of fnr-crp-related regulatory proteins. the predicted 237-amino-acid fixk protein was found to share between 28 and 38% sequence identity with the escherichia coli fnr protein, other bacterial fnr-like proteins (fnrn, anr, and hlyx), and two rhizobial fixk proteins. the b. japonicum fixk-like gene, when expressed from a lac promoter, could func ...19921551834
conserved motifs in a divergent nod box of azorhizobium caulinodans ors571 reveal a common structure in promoters regulated by lysr-type proteins.nodulation of leguminous plants by rhizobium, bradyrhizobium, and azorhizobium spp. is dependent on the induction by the plant host of different bacterial nodulation (nod) loci. the transcription of these nod loci is activated in the presence of plant-produced flavonoids upon binding of the nodd protein--a lysr-type activator--to specific sequences present in the nod promoters. originally, a 47-base-pair (bp) region called the nod box was shown to be the target sequence for binding of nodd. from ...19921542656
periplasmic metabolism of glutamate and aspartate by intact bradyrhizobium japonicum studies on the uptake and metabolism of [14c]glutamate by bradyrhizobium japonicum bacteroids we found that, in the presence of unlabeled malate, succinate or alpha-ketoglutarate, substantial label was recovered in alpha-ketoglutarate in the reaction mixtures. as much as 30% of the total 14c supplied could be found in alpha-ketoglutarate in the reaction mixtures after 30 min and this occurred in the absence of detectable labeling of alpha-ketoglutarate in the cells. the labeling of alpha-keto ...19901976384
a 2-o-methylfucose moiety is present in the lipo-oligosaccharide nodulation signal of bradyrhizobium japonicum.bradyrhizobium japonicum is a soil bacterium that forms nitrogen-fixing nodules on the roots of the agronomically important legume soybean. microscopic observation of plant roots showed that butanol extract of b. japonicum strain usda110 cultures induced for nod gene expression elicited root hair deformation, an early event in the nodulation process. the metabolite produced by b. japonicum responsible for root hair deformation activity was purified. chemical analysis of the compound revealed it ...19921528893
similarities between legume-rhizobium communication and steroid-mediated intercellular communication in vertebrates.regulation of the actions of flavonoids and nod factors in legume-rhizobia communication has several interesting similarities with that of steroid-mediated actions in vertebrates. oxidation or reduction of flavonoids and nod factors modifies their biological activity just as, for example, oxidation of an alcohol at c11 on hydrocortisone regulates its biological activity. second, some flavonoids are anti-inducers, functioning like steroid antagonists to negate the actions of inducer flavonoids. a ...19921504919
bradyrhizobium japonicum has two differentially regulated, functional homologs of the sigma 54 gene (rpon).recognition of -24/-12-type promoters by rna polymerase requires a special sigma factor, sigma 54 (rpon ntra glnf). in the nitrogen-fixing soybean symbiont bradyrhizobium japonicum, two functional, highly conserved rpon genes (rpon1 and rpon2) were identified and sequenced. the two predicted b. japonicum rpon protein sequences were 87% identical, and both showed different levels of homology to the rpon proteins of other bacteria. downstream of rpon2 (but not of rpon1), two additional open readin ...19911991712
novel organization of the common nodulation genes in rhizobium leguminosarum bv. phaseoli strains.nodulation by rhizobium, bradyrhizobium, and azorhizobium species in the roots of legumes and nonlegumes requires the proper expression of plant genes and of both common and specific bacterial nodulation genes. the common nodabc genes form an operon or are physically mapped together in all species studied thus far. rhizobium leguminosarum bv. phaseoli strains are classified in two groups. the type i group has reiterated nifhdk genes and a narrow host range of nodulation. the type ii group has a ...19911991718
the regulatory status of the fixl- and fixj-like genes in bradyrhizobium japonicum may be different from that in rhizobium meliloti.the cloning, sequencing and mutational analysis of the bradyrhizobium japonicum symbiotic nitrogen fixation genes fixl and fixj are reported here. the two genes were adjacent and probably formed an operon, fixlj. the predicted fixl and fixj proteins, members of the two-component sensor/regulator family, were homologous over almost their entire lengths to the corresponding rhizobium meliloti proteins (approx. 50% identity). downstream of the b. japonicum fixj gene was found an open reading frame ...19912000090
occurrence of lipid a variants with 27-hydroxyoctacosanoic acid in lipopolysaccharides from members of the family rhizobiaceae.lipopolysaccharides (lpss) isolated from several strains of rhizobium, bradyrhizobium, agrobacterium, and azorhizobium were screened for the presence of 27-hydroxyoctacosanoic acid. the lpss from all strains, with the exception of azorhizobium caulinodans, contained various amounts of this long-chain hydroxy fatty acid in the lipid a fractions. analysis of the lipid a sugars revealed three types of backbones: those containing glucosamine (as found in rhizobium meliloti and rhizobium fredii), tho ...19912007543
phylogeny of the phototrophic rhizobium strain btai1 by polymerase chain reaction-based sequencing of a 16s rrna gene segment.a 260-bp segment of the dna that encodes 16s rrna, corresponding to positions 44 to 337 in the escherichia coli sequence, was amplified by the polymerase chain reaction and sequenced from each of 13 bacteria (rhizobia and purple phototrophs) in the alpha subdivision of the class proteobacteria. the phylogenetic tree calculated from differences in the sequenced segment conforms well to our expectations based on other previously published data. the sequence from btai1 (a recently described phototr ...19912007551
identification of glya as a symbiotically essential gene in bradyrhizobium japonicum.a bradyrhizobium japonicum tn5 mutant (strain 3160) induced numerous, tiny, white nodules which were dispersed over the whole root system of its natural host plant, soybean (glycine max). these ineffective, nitrogen non-fixing pseudonodules were disturbed at a very early step of bacteroid and nodule development. subsequent cloning and sequencing of the dna region mutated in strain 3160 revealed that the tn5 insertion mapped in a gene that had 60% homology to the escherichia coli glya gene coding ...19912014004
nickel-dependent reconstitution of hydrogenase apoprotein in bradyrhizobium japonicum hupc mutants and direct evidence for a nickel metabolism locus involved in nickel incorporation into the enzyme.a double mutant (jh103k10) was created from hydrogenase constitutive mutant (jh103) by replacement of a chromosomal 0.60 kb nickel metabolism related locus with a kanamycin resistance gene. the double mutant required 10 to 20 times more nickel (ni) to achieve near parental strain levels of hydrogenase activity. in the absence of nickel, both jh103k10 and jh103 synthesized high levels of (inactive) hydrogenase apoprotein (large subunit, 65 kda). with nickel, the double mutant jh103k10 synthesized ...19921503531
isoflavonoid-inducible resistance to the phytoalexin glyceollin in soybean rhizobia.the antibacterial effect of the soybean phytoalexin glyceollin was assayed using a liquid microculture technique. log-phase cells of bradyrhizobium japonicum and sinorhizobium fredii were sensitive to glyceollin. as revealed by growth rates and survival tests, these species were able to tolerate glyceollin after adaptation. incubation in low concentrations of the isoflavones genistein and daidzein induced resistance to potentially bactericidal concentrations of glyceollin. this inducible resista ...19912045365
differential expression of nods accounts for the varied abilities of rhizobium fredii usda257 and rhizobium sp. strain ngr234 to nodulate leucaena spp.transfer of a cosmid containing nodsu from rhizobium sp. ngr234 to rhizobium fredii usda257 expands the host range for nodulation to include the perennial tropical legumes, leucaena leucocephala and leucaena diversifolia. complementation experiments with a series of subclones established that nods and its associated nod-box promoter from ngr234 are sufficient to confer this extended host-range phenotype to l. leucocephala. strain usda257 contains its own copy of nodsu, including upstream nod-box ...19921484488
common cis-acting region responsible for transcriptional regulation of bradyrhizobium japonicum hydrogenase by nickel, oxygen, and hydrogen.bradyrhizobium japonicum expresses hydrogenase in microaerophilic free-living conditions in the presence of nickel. plasmid-borne hup-lacz transcriptional fusion constructs were used to study the regulation of the hydrogenase gene. the hydrogenase gene was transcriptionally induced under microaerobic conditions (0.1 to 3.0% partial pressure o2). the hydrogenase gene was not transcribed or was poorly transcribed in strictly anaerobic conditions or conditions above 3.0% o2. hydrogen gas at levels ...19912061281
cell surface carbohydrates of microaerobic, nitrogenase-active, continuous cultures of bradyrhizobium sp. strain 32h1.a continuous culture system was developed to examine the cell surface carbohydrates of bradyrhizobium sp. strain 32h1. when cultures were shifted from aerobic to microaerobic growth conditions, nitrogenase activity was induced and extracellular polysaccharide levels were greatly reduced; however, the levels of cell-associated cyclic beta-1,6 -1,3 glucans were found to be essentially unchanged.19921447152
transcriptional regulation of hydrogenase synthesis by nickel in bradyrhizobium japonicum.nickel is a component of the h2-oxidizing hydrogenase of many bacteria. we report that nickel is required not only for the activity of the bradyrhizobium japonicum h2 uptake (hup) enzyme but also for the initiation of its transcription. a much greater level of hydrogenase-specific mrna was detected in cells that were derepressed for hydrogenase in the presence of 5 microm nickel than in the absence of nickel. control experiments involving probing of mrna with a b. japonicum gene encoding a non-n ...19902121729
genetic relatedness of bradyrhizobium japonicum field isolates as revealed by repeated sequences and various other characteristics.forty-nine isolates of bradyrhizobium japonicum indigenous to a field where soybeans were grown for 45 years without inoculation were characterized by using four dna hybridization probes from b. japonicum. nifdk-specific hybridization clearly divided the isolates into two divergent groups. diversity in repeated-sequence (rs)-specific hybridization was observed; 44 isolates derived from 41 nodules were divided into 33 different rs fingerprint groups. cluster analysis showed that the rs fingerprin ...19921444394
identification of nods and nodu, two inducible genes inserted between the bradyrhizobium japonicum nodyabc and nodij genes.the so-called common nodulation (nod) gene cluster of bradyrhizobium japonicum is characterized by a unique composition of genes that are arranged in the following order: nody, noda, nodb, nodc, nods, nodu, nodi, nodj. as reported here, the identification of the two new genes nods and nodu resulted from the dna sequencing of a 4.5-kilobase nodc-downstream region covering nods, nodu, nodi, and nodj. the predicted nods, nodu, nodi, and nodj proteins had the following respective amino acid (aa) len ...19902134855
nodsu, two new nod genes of the broad host range rhizobium strain ngr234 encode host-specific nodulation of the tropical tree leucaena leucocephala.rhizobium species strain ngr234 nodulates at least 35 diverse genera of legumes as well as the nonlegume parasponia andersonii. most nodulation genes are located on the 500-kilobase pair symbiotic plasmid, pngr234a. previously, three plasmid-borne host range determinants (hsni, hsnii, and hsniii) were identified by their ability to extend the nodulation capacity of heterologous rhizobia to include vigna unguiculata. in this study, we show that hsnii contains two new nod-box linked hsn genes, nod ...19902134856
signaling and host range variation in nodulation.rhizobium, bradyrhizobium, and azorhizobium strains, collectively referred to as rhizobia, elicit on their leguminous hosts, in a specific manner, the formation of nodules in which they fix nitrogen. rhizobial nod genes, which determine host specificity, infection, and nodulation, are involved in the exchange of low molecular weight signal molecules between the plant and the bacteria as follows. transcription of the nod operons is under the control of nodd regulatory proteins, which are specific ...19921444265
nucleotide sequence of the coxa gene encoding subunit i of cytochrome aa3 of bradyrhizobium japonicum. 19902172930
efficient dna transformation of bradyrhizobium japonicum by electroporation.intact cells of bradyrhizobium japonicum usda 110 were transformed with a 30-kilobase plasmid to efficiencies of 10(6) to 10(7) transformants per microgram by high-voltage electroporation. the technique was reliable and simple, with single colonies arising from transformed cells within 5 days of antibiotic selection. plasmid dna from b. japonicum transformed the bradyrhizobium (arachis) sp. with high efficiency, while the same plasmid extracted from escherichia coli transformed b. japonicum at v ...19902187405
rhizobitoxine inhibition of hydrogenase synthesis in free-living bradyrhizobium japonicum.rhizobitoxine produced by bradyrhizobium species strongly prevented derepression of hydrogenase expression in free-living bradyrhizobium japonicum, although the toxin had no effect on the activity of cells which had already synthesized hydrogenase protein. dihydrorhizobitoxine, a structural analog of rhizobitoxine, proved to be a less potent inhibitor of hydrogenase derepression. rhizobitoxine did not cause cell death at a concentration sufficient to eliminate hydrogenase expression. the large s ...19902198262
isolation and characterization of an ndvb locus from rhizobium fredii.a gene (ndvb) in rhizobium meliloti that is essential for nodule development in medicago sativa (alfalfa), specifies synthesis of a large membrane protein. this protein appears to be an intermediate in beta-1,2-glucan synthesis by the microsymbiont. southern hybridization analysis showed strong homology between an ndvb (chvb) probe and genomic dna of r. fredii but not from bradyrhizobium japonicum. a cosmid clone containing the putative ndvb locus was isolated from a rhizobium fredii gene librar ...19921406255
nitrogen fixation genes involved in the bradyrhizobium japonicum-soybean symbiosis.the symbiotic nitrogen fixation genes (nif, fix) of bradyrhizobium japonicum, the root nodule endosymbiont of soybean, are organized in at least two separate chromosomal gene clusters. these genes code for proteins of the nitrogenase complex, for proteins involved in their assembly with cofactors and for putative electron transport functions. one gene, nifa, codes for a transcriptional regulatory protein that plays a central role in the control of expression of the other genes in response to the ...19902200721
incorporation of a bacterial membrane-bound hydrogenase into proteoliposomes.membrane-bound nickel-iron hydrogenases from diverse genera of bacteria have been previously characterized and they are closely related. we report the reconstitution of purified bradyrhizobium japonicum hydrogenase into proteoliposomes by a detergent dialysis method followed by two or three cycles of freeze-thaw. sedimentation experiments revealed that more than 60% of the h2-uptake activity was particulate when reconstituted into escherichia coli phospholipids. sucrose-gradient centrifugation s ...19921384385
carbohydrate binding activities of bradyrhizobium japonicum. ii. isolation and characterization of a galactose-specific lectin.extracts of bradyrhizobium japonicum were fractionated on sepharose columns covalently derivatized with lactose. elution of the material that was specifically bound to the affinity column with lactose yielded a protein of mr approximately 38,000. isoelectric focusing of this sample yielded two spots with pi values of 6.4 and 6.8. this protein specifically bound to galactose-containing glycoconjugates, but did not bind either to glucose or mannose. derivatives of galactose at the c-2 position sho ...19902211830
the identification, characterization, sequencing and mutagenesis of the genes (hupsl) encoding the small and large subunits of the h2-uptake hydrogenase of azotobacter chroococcum.the structural genes (hupsl) of the membrane-bound nife-containing h2-uptake hydrogenase (hup) of azotobacter chroococcum were identified by oligonucleotide screening and sequenced. the small subunit gene (hups) encodes a signal sequence of 34 amino acids followed by a 310-amino-acid, 34156d protein containing 12 cysteine residues. the large subunit gene (hupl) overlaps hups by one base and codes for a predicted 601-amino-acid, 66433d protein. there are two regions of strong homology with other ...19902215219
cytokine induction by lipopolysaccharide (lps) corresponds to lethal toxicity and is inhibited by nontoxic rhodobacter capsulatus lps.many pathological effects of gram-negative bacteria are produced by their cell wall-derived lipopolysaccharides (lpss). differing pathogenicity of gram-negative lpss, however, may depend on their capacities to induce cytokines. thus, we studied the lethal toxicity of four nonenterobacterial lpss and compared it with their capacity to induce mononuclear cell (mnc)-derived interleukin-1 (il-1), interleukin-6 (il-6), and tumor necrosis factor (tnf). unstimulated mnc did not release these cytokines. ...19902228245
isolation and characterization of a ntrc mutant of bradyrhizobium (parasponia) sp. anu289.a mutant of bradyrhizobium (parasponia) sp. anu289 affected in the regulation of nitrogen metabolism was isolated. the mutant, designated anu293, was unable to induce ammonium transport (amt), nitrate reductase (nr) or glutamine synthetase ii (gsii) activities under conditions that induce these activities in the wild-type. however, glutamine synthetase i (gsi), which is expressed constitutively in the wild-type, was present at normal levels in the mutant. the mutant also retained the ability to ...19921353784
ammonia regulation of nod genes in bradyrhizobium japonicum.the expression of the nodd and nodyabc operons of bradyrhizobium japonicum is repressed by the addition of ammonia. repression of nodyabc expression is probably due to the effect on nodd since nodd positively regulates itself, as well as other nod operons. the effect of ammonia is independent of the known nitrogen regulatory protein, ntrc, and another regulatory protein for nitrogen fixation, nifa.19902250656
nucleotide sequences of membrane-bound hydrogenase gene in alcaligenes hydrogenophilus.the nucleotide sequences of membrane-bound hydrogenase small (hups) and large (hupl) subunit genes of hydrogen bacterium alcaligenes hydrogenophilus were determined. the hups and hupl genes encoded polypeptides of 363 and 619 amino acids, respectively. the hups was located upstream of hupl with 35bp of intergenic region. the consensus ribosome-binding sequences were identified upstream of the start codons of hups and hupl. amino acid sequence of hups is very similar to that of rhodobacter capsul ...19921294332
the nifen genes participating in femo cofactor biosynthesis and genes encoding dinitrogenase are part of the same operon in bradyrhizobium species.the nucleotide sequences of genes homologous to the klebsiella pneumoniae nifen genes have been determined in bradyrhizobium japonicum 110. the coding regions for the nife and nifn consist, respectively, of 1641 and 1407 nucleotides. the nifd gene (coding for the beta-subunit of dinitrogenase) and nife are linked, and separated by 95 nucleotides. in the region of 12 nucleotides that separates nife from nifn the stop codon for nife overlaps the putative ribosome binding site for nifn. in contrast ...19902266945
sequence and analysis of the nodabc region of rhizobium fredii usda257, a nitrogen-fixing symbiont of soybean and other legumes.we cloned and analyzed nodabc from rhizobium fredii usda257. these genes are thought to have common functions in initiation of nitrogen-fixing nodules by all rhizobia. in usda257, they were located in a 9.2-kb ecori fragment that was not closely linked to either of two copies of the regulatory gene, nodd. nodabc was present in a 3,094-base pair (bp) sequenced region, which also included a consensus nod-box promoter. the three open reading frames contained 654, 642, and 1,239 bp, respectively, an ...19911799701
differential expression of phenylalanine ammonia-lyase and chalcone synthase during soybean nodule development.we have used conserved and nonconserved regions of cdna clones for phenylalanine ammonia-lyase (pal) and chalcone synthase (chs) isolated from a soybean-nodule cdna library to monitor the expression of members of the two gene families during the early stages of the soybean-bradyrhizobium japonicum symbiosis. our results demonstrate that subsets of the pal and chs gene families are specifically induced in soybean roots after infection with b. japonicum. furthermore, by analyzing a supernodulating ...19911840912
proposed regulatory pathway encoded by the nodv and nodw genes, determinants of host specificity in bradyrhizobium japonicum.bradyrhizobium japonicum is the root nodule endosymbiont of soybean (glycine max), mung bean (vigna radiata), cowpea (vigna unguiculata), and siratro (macroptilium atropurpureum). we report the characteristics of a nodulation-gene region of b. japonicum that contributes only marginally to the bacterium's ability to nodulate soybean but is essential for the nodulation of the three alternative hosts. this dna region consists of two open reading frames designated nodv and nodw. the predicted amino ...19902320582
competitive inhibition of an energy-dependent nickel transport system by divalent cations in bradyrhizobium japonicum jh.both nickel-specific transport and nickel transport by a magnesium transporter have been described previously for a variety of nickel-utilizing bacteria. the derepression of hydrogenase activity in bradyzhizobium japonicum jh and in a gene-directed mutant of strain jh (in an intracellular ni metabolism locus), strain jhk7, was inhibited by mgso4. for both strains, ni2+ uptake was also markedly inhibited by mg2+, and the mg(2+)-mediated inhibition could be overcome by high levels of ni2+ provided ...19911785926
identification of a locus within the hydrogenase gene cluster involved in intracellular nickel metabolism in bradyrhizobium japonicum.a 0.6-kb fragment of dna involved in intracellular ni metabolism was isolated and cloned from a cosmid containing 23.2 kb of hydrogenase-related genes of bradyrhizobium japonicum. this locus is located 8.3 kb upstream of the hydrogenase structural genes. the hydrogenase activity of a mutant with a gene-directed mutation at this locus (strain jhk7) showed dependency on nickel provided during hydrogenase derepression. the hydrogenase activity was only 20% of that in the wild-type strain, jh, at a ...19911785925
the genomes of the family rhizobiaceae: size, stability, and rarely cutting restriction endonucleases.the lack of high-resolution genetic or physical maps for the family rhizobiaceae limits our understanding of this agronomically important bacterial family. on the basis of statistical analyses of dna sequences of the rhizobiaceae and direct evaluation by pulsed-field agarose gel electrophoresis (pfe), five restriction endonucleases with at-rich target sites were identified as the most rarely cutting: asei (5'-attaat-3'), drai (5'-tttaaa-3'), spei (5'-actagt-3'), sspi (5'-aataat-3'), and xbai (5' ...19911846148
genome analysis of bradyrhizobium japonicum serocluster 123 field isolates by using field inversion gel electrophoresis.the genomes of 11 bradyrhizobium japonicum serocluster 123 field isolates were analyzed by using field inversion gel electrophoresis. genomic fingerprints produced by digestion of intact genomic dna in agarose plugs with the rare-cutting restriction enzymes asei, drai, spei, and xbai showed that the isolates were genetically diverse. few (30 to 50%) isolates exhibited the same fingerprint as the usda serogroup strain with which they are antigenically related. southern hybridization with a nifhd ...19902383015
genetic organization of the hydrogen uptake (hup) cluster from rhizobium symbiosis with peas, rhizobium leguminosarum upm791 induces the synthesis of a hydrogen uptake (hup) system that recycles hydrogen generated in nodules by nitrogenase. a cosmid (pal618) containing hup genes from this strain on a 20-kilobase-pair (kb) dna insert has previously been isolated in our laboratory (a. leyva, j. m. palacios, t. mozo, and t.ruiz-argüeso, j. bacteriol. 169:4929-4934, 1987). here we show that cosmid pal618 contains all of the genetic information required to confer high ...19902407728
aerobic growth and respiration of a delta-aminolevulinic acid synthase (hema) mutant of bradyrhizobium japonicum.oxygen-dependent growth of the bradyrhizobium japonicum hema mutant mlg1 (m.l. guerinot and b.k. chelm, proc. natl. acad. sci. usa 83:1837-1841, 1986) was demonstrated in cultured cells in the absence of exogenous delta-aminolevulinic acid (ala), but growth of analogous mutants of rhizobium meliloti or of escherichia coli was not observed unless ala was added to the yeast extract-containing media. no heme could be detected in extracts of strain mlg1 cells as measured by the absorption or by the ...19911846857
two host-inducible genes of rhizobium fredii and characterization of the inducing compound.random transcription fusions with mu d1(kan lac) generated three mutants in rhizobium fredii (strain usda 201) which showed induction of beta-galactosidase when grown in root exudate of the host plants glycine max, phaseolus vulgaris, and vigna ungliculata. two genes were isolated from a library of total plasmid dna of one of the mutants, 3f1. these genes, present in tandem on a 4.2-kilobase hindiii fragment, appear in one copy each on the symbiotic plasmid and do not hybridize to the rhizobium ...19882447061
discovery and sequence analysis of bacterial genes involved in the biogenesis of c-type cytochromes.we report the dna sequence and mutational analysis of a novel cluster of six bradyrhizobium japonicum genes of which at least three (designated cycv, cycw, and cycx) are essential for the formation of all cellular c-type cytochromes. mutants having insertions in these genes were completely devoid of any soluble (periplasmic) or membrane-bound c-type cytochromes; even the apo form of cytochrome c1 was not detectable, neither in the membrane nor in the soluble fraction. as a consequence, the mutan ...19911850420
cloning, sequencing, and mutational analysis of the bradyrhizobium japonicum fumc-like gene: evidence for the existence of two different fumarases.the bradyrhizobium japonicum fumarase gene (fumc-like) was cloned and sequenced, and a fumc deletion mutant was constructed. this mutant had a nod+ fix+ phenotype in symbiosis with the host plant, soybean, and growth in minimal medium with fumarate as sole carbon source was also not affected. the cloned b. japonicum fumc gene fully complemented an escherichia coli fum- mutant, strain jh400, for growth in minimal medium with fumarate. the predicted amino acid sequence of the fumc protein showed s ...19911856685
chemical control of interstrain competition for soybean nodulation by bradyrhizobium japonicum.previous research has shown that a significant limitation to the agricultural use of improved rhizobial inoculant strains is competition from the indigenous soil population. in this work, we sought to test whether chemical inhibitors of flavonoid-induced nod gene expression in bradyrhizobium japonicum could be identified and utilized to affect interstrain competition for nodulation of soybeans. approximately 1,000 structural and functional analogs of the known, natural inducers of nod gene expre ...19911892378
isolation of bradyrhizobium japonicum dna sequences that are transcribed at high levels in bacteroids.dna sequences have been isolated that are expressed at high levels in bacteroids, the differentiated form of the soybean microsymbiont, bradyrhizobium japonicum. random-primed cdna was synthesized using total rna isolated from purified b. japonicum bacteroids or from cells grown in culture. when used directly to screen bacteriophage lambda libraries, these cdna probes produced a high background hybridization signal due to sequence similarity between b. japonicum and e. coli ribosomal dna (rdna) ...19911896009
genetic analysis of the cytochrome c-aa3 branch of the bradyrhizobium japonicum respiratory chain.further genetic evidence is provided here that bradyrhizobium japonicum possesses a mitochondria-like electron-transport pathway: 2[h]----uq----bc1----c----aa3----o2. two tn5-induced mutants, cox122 and cox132, having cytochrome c oxidase-negative phenotypes, were obtained and characterized. mutant cox122 was defective in a novel gene, named cycm, which was responsible for the synthesis of a c-type cytochrome with an mr of 20,000 (20k). this 20k cytochrome c appeared to catalyse electron transpo ...19901965217
the bradyrhizobium japonicum fixbcx operon: identification of fixx and of a 5' mrna region affecting the level of the fixbcx transcript.the bradyrhizobium japonicum fixx gene was identified and shown to be essential for symbiotic and free-living, microaerobic nitrogen fixation. the fixx gene encodes a ferredoxin-like protein which may be involved in a redox process (electron transport?) essential for nitrogenase activity. this gene was localized downstream of fixc and its expression was dependent on the fixb promoter, providing evidence for the existence of a fixbcx operon. mutagenesis and sequence analysis of the unusually long ...19892503674
molecular cloning, sequencing, and expression of the glutamine synthetase ii (glnii) gene from the actinomycete root nodule symbiont frankia sp. strain common with other plant symbionts, frankia spp., the actinomycete n2-fixing symbionts of certain nonleguminous woody plants, synthesize two glutamine synthetases, gsi and gsii. dna encoding the bradyrhizobium japonicum gene for gsii (glnii) hybridized to dna from three frankia strains. b. japonicum glnii was used as a probe to clone the glnii gene from a size-selected kpni library of frankia strain cpi1 dna. the region corresponding to the frankia sp. strain cpi1 glnii gene was sequenced, and ...19901975584
production of extracellular nucleic acids by genetically altered bacteria in aquatic-environment microcosms.the factors which affect the production of extracellular dna by genetically altered strains of escherichia coli, pseudomonas aeruginosa, pseudomonas cepacia, and bradyrhizobium japonicum in aquatic environments were investigated. cellular nucleic acids were labeled in vivo by incubation with [3h]thymidine or [3h]adenine, and production of extracellular dna in marine waters, artificial seawater, or minimal salts media was determined by detecting radiolabeled macromolecules in incubation filtrates ...19892506807
identification, cloning, and sequence analysis of the nitrogen regulation gene ntrc of agrobacterium tumefaciens c58.we describe the cloning of an ntrc gene of agrobacterium tumefaciens c58 by interspecific complementation of an escherichia coli ntrc mutant. restriction mapping and southern blot analysis of the complementing clone identified a 1.7-kb ecori-pvuii dna fragment whose sequence was determined. analysis of this sequence revealed coding regions corresponding to a complete ntrc gene and the c-terminal region of an ntrb gene. amino acid sequence comparisons of a. tumefaciens ntrc protein with ntrc sequ ...19892520824
streptomyces hygroscopicus has two glutamine synthetase genes.streptomyces hygroscopicus, which produces the glutamine synthetase inhibitor phosphinothricin, possesses at least two genes (glna and glnb) encoding distinct glutamine synthetase isoforms (gsi and gsii). the glnb gene was cloned from s. hygroscopicus dna by complementation in an escherichia coli glutamine auxotrophic mutant (glna). glnb was subcloned in streptomyces plasmids by insertion into pij486 (pmsg3) and pij702 (pmsg5). both constructions conferred resistance to the tripeptide form of ph ...19901975585
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