| 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 ... | 1991 | 1660457 |
| 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 ... | 1991 | 1663887 |
| 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 ... | 1991 | 1663888 |
| 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 ... | 1991 | 1675210 |
| measurement of the human immune response to meningococcal lipooligosaccharide antigens by using serum to inhibit monoclonal antibody binding to purified lipooligosaccharide. | we developed a human inhibition monoclonal enzyme-linked immunosorbent assay (himelisa) to investigate the human immune response to the lipooligosaccharides (los) of neisseria meningitidis. monoclonal antibodies (mab) were used to define seven epitopes on four los molecules of a meningococcal strain (126e) previously shown to express immunogenic los epitopes. the assay could distinguish epitope-specific antibody within whole sera. neither the specificity nor the amount of the antibody measured b ... | 1990 | 1694820 |
| 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 ... | 1991 | 1717438 |
| 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 ... | 1992 | 1730597 |
| 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 ... | 1991 | 1768137 |
| 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 ... | 1991 | 1769537 |
| 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 ... | 1991 | 1779763 |
| 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 ... | 1991 | 1785925 |
| 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 ... | 1991 | 1785926 |
| codon usage and g + c content in bradyrhizobium japonicum genes are not uniform. | to 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 ... | 1991 | 1793334 |
| 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 ... | 1991 | 1793335 |
| 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 ... | 1991 | 1799697 |
| 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 ... | 1991 | 1799701 |
| 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 ... | 1991 | 1799702 |
| 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 ... | 1991 | 1829727 |
| 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 ... | 1991 | 1840912 |
| 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' ... | 1991 | 1846148 |
| 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 ... | 1991 | 1846857 |
| purification and properties of malonyl-coa synthetase from rhizobium japonicum. | a novel malonyl-coa synthetase was found in rhizobium japonicum bacteroid of the soybean nodule. the levels of the enzyme in the free-living cells grown on a variety of carbon sources including glucose were similar, indicating that this enzyme is not inducible. the malonyl-coa synthetase from glucose-grown rhizobium japonicum was purified to homogeneity. the mr of the enzyme was determined to be 58,000 by gel filtration on a sephacryl s-300 and by sds/page respectively, indicating a single polyp ... | 1991 | 1847615 |
| 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 ... | 1991 | 1850420 |
| 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 ... | 1991 | 1856182 |
| 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 ... | 1991 | 1856685 |
| 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 ... | 1991 | 1892378 |
| 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 ... | 1991 | 1892399 |
| 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) ... | 1991 | 1896009 |
| 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 ... | 1991 | 1912387 |
| 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 ... | 1990 | 1965217 |
| 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 ... | 1990 | 1970239 |
| molecular cloning, sequencing, and expression of the glutamine synthetase ii (glnii) gene from the actinomycete root nodule symbiont frankia sp. strain cpi1. | in 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 ... | 1990 | 1975584 |
| periplasmic metabolism of glutamate and aspartate by intact bradyrhizobium japonicum bacteroids. | in 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 ... | 1990 | 1976384 |
| detection of alternative nitrogenases in aerobic gram-negative nitrogen-fixing bacteria. | strains of aerobic, microaerobic, nonsymbiotic, and symbiotic dinitrogen-fixing bacteria were screened for the presence of alternative nitrogenase (n2ase) genes by dna hybridization between genomic dna and dna encoding structural genes for components 1 of three different enzymes. a nifdk gene probe was used as a control to test for the presence of the commonly occurring mo-fe n2ase, a vnfdgk gene probe was used to show the presence of v-fe n2ase, and an anfdgk probe was used to detect fe n2ase. ... | 1991 | 1987127 |
| the bradyrhizobium japonicum nola gene and its involvement in the genotype-specific nodulation of soybeans. | several soybean genotypes have been identified which specifically exclude nodulation by members of bradyrhizobium japonicum serocluster 123. we have identified and sequenced a dna region from b. japonicum strain usda 110 which is involved in genotype-specific nodulation of soybeans. this 2.3-kilobase region, cloned in pmjs12, allows b. japonicum serocluster 123 isolates to form nodules on plants of serogroup 123-restricting genotypes. the nodules, however, were ineffective for symbiotic nitrogen ... | 1991 | 1988958 |
| 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 ... | 1991 | 1991712 |
| 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 ... | 1991 | 2000090 |
| 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 ... | 1991 | 2007543 |
| 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 ... | 1991 | 2007551 |
| 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 ... | 1991 | 2014004 |
| cloning and nucleotide sequence of the hema gene of agrobacterium radiobacter. | the hema gene of agrobacterium radiobacter atcc4718 was identified by hybridization with a hema probe from rhizobium meliloti and cloned by complementation of a hema mutant of escherichia coli k12. e. coli hema transformants carrying the hema gene of agrobacterium showed delta-aminolevulinic acid synthetase (delta-alas) activity in vitro. the hema gene was carried on a 4.4 kb ecori fragment which could be reduced to a 2.6 kb ecori-ssti fragment without affecting its complementing or delta-alas a ... | 1991 | 2034217 |
| 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 ... | 1991 | 2045365 |
| influence of oxygen on dna binding, positive control, and stability of the bradyrhizobium japonicum nifa regulatory protein. | central to the genetic regulatory circuit that controls bradyrhizobium japonicum nif and fix gene expression is the nifa protein. nifa activates transcription of several nif and fix genes and autoregulates its expression during symbiosis in soybean root nodules or in free-living microaerobic conditions. high o2 tensions result in the lack of nif expression, possibly by inactivation of nifa through oxidation of an essential metal cofactor. several b. japonicum nif and fix promoters have upstream ... | 1991 | 2045367 |
| 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 ... | 1991 | 2061281 |
| molecular biology studies of the uptake hydrogenase of rhodobacter capsulatus and rhodocyclus gelatinosus. | in the photosynthetic bacteria, as in other n2-fixing bacteria, two main enzymes are involved in h2 metabolism: nitrogenase, which catalyses the photoproduction of h2, and a membrane-bound (nife) hydrogenase, which functions as an h2-uptake enzyme. the structural genes for rhodobacter capsulatus and rhodocyclus gelatinosus uptake hydrogenases were isolated and sequenced. they present the same organization, with the gene encoding the small subunit (hups) (molecular masses 34.2 and 34.6 kda, respe ... | 1990 | 2094292 |
| 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 ... | 1990 | 2121729 |
| soluble hydrogenase of anabaena cylindrica. cloning and sequencing of a potential gene encoding the tritium exchange subunit. | a gene potentially encoding a subunit of the soluble hydrogenase of anabaena cylindrica was isolated from a genomic library by screening with a set of redundant oligonucleotides, the sequence of which was deduced from the amino acid sequence of the purified hydrogenase subunit that catalyses tritium exchange. the nucleotide sequence of the potential gene was determined from two overlapping dna fragments spanning 7237 bp of the a. cylindrica genome. the region sequenced contained an open reading ... | 1990 | 2129525 |
| 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 ... | 1990 | 2134855 |
| 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 ... | 1990 | 2134856 |
| citrate as a siderophore in bradyrhizobium japonicum. | under iron-limiting conditions, many bacteria secrete ferric iron-specific ligands, generically termed siderophores, to aid in the sequestering and transport of iron. one strain of the nitrogen-fixing soybean symbiont bradyrhizobium japonicum, 61a152, was shown to produce a siderophore when 20 b. japonicum strains were screened with all six chemical assays commonly used to detect such production. production by strain 61a152 was detected via the chrome azurol s assay, a general test for sideropho ... | 1990 | 2140566 |
| nucleotide sequence of the coxa gene encoding subunit i of cytochrome aa3 of bradyrhizobium japonicum. | | 1990 | 2172930 |
| 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 ... | 1990 | 2187405 |
| 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 ... | 1990 | 2198262 |
| nickel accumulation and storage in bradyrhizobium japonicum. | hydrogenase-derepressed (chemolithotrophic growth conditions) and heterotrophically grown cultures of bradyrhizobium japonicum accumulated nickel about equally over a 3-h period. both types of cultures accumulated nickel primarily in a form that was not exchangeable with nicl2, and they accumulated much more ni than would be needed for the ni-containing hydrogenase. the nickel accumulated by heterotrophically incubated cultures could later be mobilized to allow active hydrogenase synthesis durin ... | 1990 | 2200341 |
| 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 ... | 1990 | 2200721 |
| carbohydrate binding activities of bradyrhizobium japonicum. i. saccharide-specific inhibition of homotypic and heterotypic adhesion. | bradyrhizobium japonicum (r110d) exhibited four saccharide-specific binding activities: (a) adsorption to sepharose beads containing covalently coupled lactose; (b) homotypic agglutination through one pole of the cell (star formation); (c) heterotypic adhesion to the cultured soybean cell line, sb-1; and (d) attachment to roots of soybean plants. each of these binding activities can be inhibited by the addition of galactose or lactose, but not by derivatives such as n-acetyl-d-galactosamine or m ... | 1990 | 2211829 |
| 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 ... | 1990 | 2211830 |
| 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 ... | 1990 | 2215219 |
| fluorescence studies with malate dehydrogenase from bradyrhizobium japonicum 3i1b-143 bacteroids: a two-tryptophan containing protein. | a number of fluorescence studies, both of trp residues and bound nadh, have been reported for porcine malate dehydrogenase (mdh). the large number of trp residues (six) complicates the interpretation of some studies. to circumvent this we have performed studies with a two-tryptophan (per subunit) mdh from bradyrhizobium japonicum 3i1b-143 bacteroids. we have performed phase/modulation fluorescence lifetime measurements, as a function of temperature and added quencher ki, in order to resolved the ... | 1990 | 2241162 |
| 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. | 1990 | 2250656 |
| cloning and sequence of the salmonella typhimurium heml gene and identification of the missing enzyme in heml mutants as glutamate-1-semialdehyde aminotransferase. | salmonella typhimurium forms the heme precursor delta-aminolevulinic acid (ala) exclusively from glutamate via the five-carbon pathway, which also occurs in plants and some bacteria including escherichia coli, rather than by ala synthase-catalyzed condensation of glycine and succinyl-coenzyme a, which occurs in yeasts, fungi, animal cells, and some bacteria including bradyrhizobium japonicum and rhodobacter capsulatus. ala-auxotrophic heml mutant s. typhimurium cells are deficient in glutamate-1 ... | 1990 | 2254275 |
| 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 ... | 1990 | 2266945 |
| cell-associated oligosaccharides of bradyrhizobium spp. | we report the initial characterization of the cell-associated oligosaccharides produced by four bradyrhizobium strains: bradyrhizobium japonicum usda 110, usda 94, and atcc 10324 and bradyrhizobium sp. strain 32h1. the cell-associated oligosaccharides of these strains were found to be composed solely of glucose and were predominantly smaller than the cyclic beta-1,2-glucans produced by agrobacterium and rhizobium species. linkage studies and nuclear magnetic resonance analyses demonstrated that ... | 1990 | 2294083 |
| isolation and characterization of the lipopolysaccharides from bradyrhizobium japonicum. | the lipopolysaccharide (lps) of bradyrhizobium japonicum 61a123 was isolated and partially characterized. phenol-water extraction of strain 61a123 yielded lps exclusively in the phenol phase. the water phase contained low-molecular-weight glucans and extracellular or capsular polysaccharides. the lpss from b. japonicum 61a76, 61a135, and 61a101c were also extracted exclusively into the phenol phase. the lpss from strain usda 110 and its nod- mutant hs123 were found in both the phenol and water p ... | 1990 | 2318801 |
| 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 ... | 1990 | 2320582 |
| cloning and sequencing the genes encoding uptake-hydrogenase subunits of rhodocyclus gelatinosus. | rhodocyclus gelatinosus grew photosynthetically in the light and consumed h2 at a rate of about 665 nmol/min per mg protein. the uptake-hydrogenase (h2ase) was found to be membrane bound and insensitive to inhibition by co. the structural genes of r. gelatinosus uptake-h2ase were isolated from a 40 kb cosmid gene library of r. gelatinosus dna by hybridization with the structural genes of uptake-h2ase of bradyrhizobium japonicum and rhodobacter capsulatus. the r. gelatinosus genes were localized ... | 1990 | 2325631 |
| bismuth subsalicylate in the prevention of colonization of infant mice with campylobacter jejuni. | infant mice were used for the evaluation of the efficacy of bismuth subsalicylate (bss) in the prevention of the growth of campylobacter jejuni in the intestine. the mic90 of ten c. jejuni strains was 900 micrograms/ml. of three dosage regimens tested, continuous treatment before and after the bacterial challenge, mimicking the way bss is used in the prevention of traveller's diarrhoea, was the most effective. growth inhibition was dose dependent; the high dose of 2000 micrograms per day was mor ... | 1990 | 2347383 |
| a model of nitrogen flow by malonamate in rhizobium japonicum-soybean symbiosis. | two types of novel malonamidases were found in soybean nodules. one (e1) catalyzes the formation of malonamate from malonate and its hydrolysis to ammonia, whereas the other (e2) acts mainly on the hydrolysis of malonamate. e1 and e2 were found in bacteroids, but only e2 was found in the plant cytosol of the nodule. the substrate requirements of e1 and e2 were highly specific for malonate and malonamate, respectively. from these and other results reported previously, we propose that malonamate p ... | 1990 | 2357226 |
| effects of the photobleaching herbicide, acifluorfen-methyl, on protoporphyrinogen oxidation in barley organelles, soybean root mitochondria, soybean root nodules, and bacteria. | the photobleaching herbicide, acifluorfen-methyl (afm), has been reported to be an inhibitor of the heme and chlorophyll biosynthetic enzyme protoporphyrinogen oxidase (protox) in several plant species. however, afm had no effect on the levels of protox activity measured in a mitochondrial fraction from soybean roots. in contrast, afm inhibited protox activity in etioplasts from barley leaves and in mitochondria from barley roots, but the extent of inhibition varied depending upon the assay cond ... | 1990 | 2369128 |
| 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 ... | 1990 | 2383015 |
| genetic organization of the hydrogen uptake (hup) cluster from rhizobium leguminosarum. | in 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 ... | 1990 | 2407728 |
| differential transcription of the two glutamine synthetase genes of bradyrhizobium japonicum. | bradyrhizobium japonicum induces the formation of nitrogen-fixing symbiotic root nodules on soybean plants. the b. japonicum genome encodes two isoforms of glutamine synthetase (gs). one form, gsi, encoded by the gene glna, is similar in structure and activity to the enzyme found in all other bacteria. the second form, gsii, encoded by glnii, is structurally related to the eucaryotic enzyme. genetic analyses indicate that glna or glnii alone is sufficient to provide glutamine prototrophy, wherea ... | 1987 | 2445733 |
| relationship between raman spectroscopic lines and growth of rhizobium japonicum. | the raman spectroscopic lines of liquid cultures of rhizobium japonicum have been compared with electron microscopic examinations and growth measurements of these cells. the results showed that the significant raman lines are related to the reproduction activities of the procaryotic cells. | 1987 | 2446767 |
| 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 ... | 1988 | 2447061 |
| immunological relationship among hydrogenases. | we examined the immunological cross-reactions of 11 different hydrogenase antigens with 9 different hydrogenase antibodies. included were antibodies and antigens of both subunits of the hydrogenases of bradyrhizobium japonicum and thiocapsa roseopersicina. the results showed a strong relationship among the ni-fe dimeric hydrogenases. the two subunits of ni-fe dimeric hydrogenases appeared immunologically distinct: specific interactions occurred only when antibodies to the 60- and 30-kilodalton s ... | 1989 | 2464579 |
| o-antigen from bradyrhizobium japonicum lipopolysaccharide inhibits intercellular (symplast) communication between soybean (glycine max) cells. | the technique of fluorescence redistribution after photobleaching was utilized to measure intercellular movement of low molecular weight fluorescent hydrophilic substances across the cell wall/membrane interface between contiguous soybean (glycine max (l.) merr. cv. mandarin) root cells (sb-1 cell line) in tissue culture. lipopolysaccharide (lps) purified from bradyrhizobium japonicum r110d, a gram-negative bacterium that normally infects and induces nodulation in soybean roots in vivo, inhibits ... | 1989 | 2473070 |
| expression of bradyrhizobium japonicum nodulation gene in rhizobium fredii nod mutants. | the b. japonicum usda 110 plafr1 gene library was transferred to tn5-induced rhizobium fredii usda 191-4 nod- mutants with helper plasmid prk2013. smr tcr transconjugants occurred with a frequency of 5 x 10(-4). the transconjugants were purified and used to inoculate germinated soybean seeds. seven nodules were obtained in the nodulation experiment. the fast-growing nod+ smr tcr rhizobium fredii strain was isolated from all nodules. each isolate had acquired a new plasmid with a molecular mass o ... | 1989 | 2491321 |
| characterization of hydrogen-uptake activity in the hyperthermophile pyrodictium brockii. | pyrodictium brockii is a hyperthermophilic archaebacterium with an optimal growth temperature of 105 degrees c. p. brockii is also a chemolithotroph, requiring h2 and co2 for growth. we have characterized p. brockii hydrogen-uptake activity with regard to temperature, ability to couple hydrogen oxidation to artificial electron acceptor reduction, sensitivity to o2, and cellular localization. the hydrogen-uptake activity was localized predominantly in a particulate fraction, was reversibly inhibi ... | 1989 | 2492097 |
| protein phosphorylation in bradyrhizobium japonicum bacteroids and cultures. | protein phosphorylation was demonstrated in bradyrhizobium japonicum bacteroids in vivo and in cultures in vivo and in vitro. comparison of in vivo-labeled phosphoproteins of bacteroids and of cultured cells showed differences in both the pattern and intensity of labeling. in cultured cells, comparison of the labeling patterns and intensities of in vivo- and in vitro-labeled phosphoproteins showed a number of similarities; however, several phosphoproteins were found only after one of the two lab ... | 1989 | 2498290 |
| 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 ... | 1989 | 2503674 |
| fine-tuning of nif and fix gene expression by upstream activator sequences in bradyrhizobium japonicum. | the significance of bradyrhizobium japonicum upstream activator sequences (uass) for differential nifa-mediated fix and nif gene expression was investigated by two means: (i) hybrid fixa- and fixb-lacz fusions were constructed by transposing a nifh-uas cartridge in front of their promoters; and (ii) b. japonicum mutants were generated carrying specific chromosomal deletions or uas cartridge insertions within the fixa, fixb or nifh promoter-upstream regions. expression of fixa was not affected, a ... | 1989 | 2503675 |
| 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 ... | 1989 | 2506807 |
| nodule-specific kinases phosphorylating nuclear factors in isolated nuclei. | in vitro phosphorylation of total nuclear proteins from soybean (glycine max l) nodules formed by bradyrhizobium japonicum 61a76 showed several differences in comparison with those from uninfected roots or embryonic-axes nuclei. three types of protein phosphorylations were observed in nodule nuclei: ca(2+)- and calmodulin-independent, ca(2+)- and calmodulin-dependent, and ca(2+)-dependent but calmodulin-independent. in addition, ca(2+)-dependent dephosphorylation of some nuclear proteins was obs ... | 1989 | 2535508 |
| identification and isolation of genes essential for h2 oxidation in rhodobacter capsulatus. | mutants of rhodobacter capsulatus unable to grow photoautotrophically with h2 and co2 were isolated. those lacking uptake hydrogenase activity as measured by h2-dependent methylene blue reduction were analyzed genetically and used in complementation studies for the isolation of the wild-type genes. results of further subcloning and transposon tn5 mutagenesis suggest the involvement of a minimum of five genes. hybridization to the 2.2-kilobase-pair ssti fragment that lies within the coding region ... | 1989 | 2536678 |
| an unusual gene cluster for the cytochrome bc1 complex in bradyrhizobium japonicum and its requirement for effective root nodule symbiosis. | two adjacent genes in bradyrhizobium japonicum, fbcf and fbch, encode the rieske iron sulfur protein and cytochromes b and c1, characteristic constituents of the respiratory complex iii. remarkably, fbch is a single gene of which the 5' half codes for cytochrome b and the 3' half codes for cytochrome c1. experimental evidence suggests that a large fbch precursor is posttranslationally processed into the two proteins. b. japonicum fbcf and fbch insertion mutants grow aerobically but are unable to ... | 1989 | 2541921 |
| identification of bradyrhizobium nod genes involved in host-specific nodulation. | three loci important for soybean nodulation by bradyrhizobium japonicum were delimited by tn5 mutagenesis on a 5.3-kilobase ecori fragment adjacent to the nodabc genes. results of hybridization studies suggested that this region is conserved in bradyrhizobium species but absent in all rhizobium species. lacz translational fusions of two of the loci contained in this region were found to be inducible by host-produced flavonoid chemicals via a mechanism requiring a functional nodd gene product. a ... | 1989 | 2542223 |
| hydrogenase synthesis in bradyrhizobium japonicum hupc mutants is altered in sensitivity to dna gyrase inhibitors. | in the hupc mutants of bradyrhizobium japonicum sr, regulation of expression of hydrogenase is altered; the mutants synthesize hydrogenase constitutively in the presence of atmospheric levels of oxygen. the dna gyrase inhibitors nalidixic acid, novobiocin, and coumermycin were used to inhibit growth of wild-type and mutant cells. for each inhibitor tested, growth of mutant and wild-type strains was equally sensitive. however, in contrast to the wild type, the hupc mutants synthesized hydrogenase ... | 1989 | 2547335 |
| adenylate cyclase and cyclic amp phosphodiesterase in bradyrhizobium japonicum bacteroids. | adenylate cyclase and cyclic amp (camp) phosphodiesterase have been identified and partially characterized in bacteroids of bradyrhizobium japonicum 3i1b-143. adenylate cyclase activity was found in the bacteroid membrane fraction, whereas camp phosphodiesterase activity was located in both the membrane and the cytosol. in contrast to other microorganisms, b. japonicum adenylate cyclase remained firmly bound to the membrane during treatment with detergents. adenylate cyclase was activated four- ... | 1989 | 2548992 |
| the nifa gene product from rhizobium leguminosarum biovar trifolii lacks the n-terminal domain found in other nifa proteins. | the nifa gene has been identified between the fixx and nifb genes in the clover microsymbiont rhizobium leguminosarum biovar trifolii (r.i. bv. trifolii) strain anu843. expression of the nifa gene is induced in the symbiotic state and site-directed mutagenesis experiments indicate that nifa expression is essential for symbiotic nitrogen fixation. interestingly, the predicted r.i. bv. trifolii nifa protein lacks an n-terminal domain that is present in the homologous proteins from r.i. bv. viciae, ... | 1989 | 2552256 |
| expression of the adenyl cyclase-encoding gene (cya) of rhizobium meliloti f34: existence of two cya genes? | to gain insight into the role of cyclic amp (camp) in gram-negative soil bacteria, we have studied the expression of an adenyl cyclase-encoding gene 'cya' of rhizobium meliloti f34. in both escherichia coli and bradyrhizobium japonicum, the gene is expressed from a promoter(s) contained on a 2.6-kb fragment of the cloned insert, which may indicate the presence of a functional 'cya' promoter or the coincidental presence of sequences which can function as promoters in these two species. the study ... | 1989 | 2555267 |
| identification of a regulatory nifa type gene and physical mapping of cloned new nif regions of azospirillum brasilense. | three new tn5-mutagenized nif genes of azospirillum brasilense were characterized. the sizes of the restriction fragments and the restriction maps of the cloned nif dna regions showed that these nif genes are distinct from those reported earlier, e.g. nifhdk, nife, nifus, fixabc. the nif27 mutant was identified as a nifa type regulatory gene of a. brasilense (a) by genetic complementation with nifa of klebsiella pneumoniae, (b) by the absence of nitrogenase iron protein in western protein blots ... | 1989 | 2559312 |
| rhizobium meliloti 1021 has three differentially regulated loci involved in glutamine biosynthesis, none of which is essential for symbiotic nitrogen fixation. | we have cloned and characterized three distinct rhizobium meliloti loci involved in glutamine biosynthesis (glna, glnii, and glnt). the glna locus shares dna homology with the glna gene of klebsiella pneumoniae, encodes a 55,000-dalton monomer subunit of the heat-stable glutamine synthetase (gs) protein (gsi), and complemented an escherichia coli glna mutation. the glnii locus shares dna homology with the glnii gene of bradyrhizobium japonicum and encodes a 36,000-dalton monomer subunit of the h ... | 1989 | 2563998 |
| glutamine synthetase ii in rhizobium: reexamination of the proposed horizontal transfer of dna from eukaryotes to prokaryotes. | we have determined the dna sequence of a rhizobium meliloti gene that encodes glutamine synthetase ii (gsii). the deduced amino acid sequence was compared to that of bradyrhizobium japonicum gsii and those of various plant and mammalian glutamine synthetases (gs) in order to evaluate a proposal that the gene for this enzyme was recently transferred from plants to their symbiotic bacteria. there is 83.6% identity between the r. meliloti and b. japonicum proteins. the bacterial gsii proteins avera ... | 1989 | 2575672 |
| fast-growing root nodule bacteria produce a novel polyamine, aminobutylhomospermidine. | polyamines in various root nodule bacteria including bradyrhizobium japonicum, rhizobium fredii, r. leguminosarum, r. meliloti and r. loti were identified by capillary gas chromatography. homospermidine was the polyamine present in highest concentration in all the rhizobia tested. in addition to putrescine and homospermidine, fast-growing type of rhizobial cells contained a novel polyamine, aminobutylhomospermidine, nh2(ch2)4nh(ch2)4nh(ch2)4nh2. the unusual tetraamine was not found in the cells ... | 1989 | 2597153 |
| immunological identification and distribution of dissimilatory heme cd1 and nonheme copper nitrite reductases in denitrifying bacteria. | polyclonal antibodies were used to identify heme or copper nitrite reductases in the following groups: 23 taxonomically diverse denitrifiers from culture collections, 100 numerically dominant denitrifiers from geographically diverse environments, and 51 denitrifiers from a culture collection not selected for denitrification. antisera were raised against heme nitrite reductases from pseudomonas aeruginosa and pseudomonas stutzeri and against copper nitrite reductase from achromobacter cycloclaste ... | 1989 | 2624465 |
| molecular cloning of a gene for indole-3-acetamide hydrolase from bradyrhizobium japonicum. | a plafr1 cosmid genomic library of wild-type bradyrhizobium japonicum j1063 was constructed. a cosmid clone designated pbjj4, containing a 26-kilobase (kb) dna insert, was identified as being able to confer the ability to convert alpha-naphthaleneacetamide acid on b. japonicum j1b7 rifr, which cannot perform this conversion. the gene coding for the enzyme that converts alpha-naphthaleneacetamide to alpha-naphthaleneacetic acid was localized in the 3.5-kb region of pbjj4 by recloning in plasmid p ... | 1989 | 2646294 |
| estimation of nitrogenase activity in the presence of ethylene biosynthesis by use of deuterated acetylene as a substrate. | nitrogenase reduces deuterated acetylene primarily to cis dideuterated ethylene. this can be distinguished from undeuterated ethylene by the use of fourier transform infrared spectroscopy. characteristic bands in the region from 800 to 3,500 cm-1 can be used to identify and quantitate levels of these products. this technique is applicable to field studies of nitrogen fixation where ethylene biosynthesis by plants or bacteria is occurring. we have verified the reaction stoichiometry by using kleb ... | 1989 | 2655535 |
| construction of chimaeric promoter regions by exchange of the upstream regulatory sequences from fdhf and nif genes. | hybrid 5' regulatory regions were constructed in which the upstream activator sequence (uas) and promoter of various nif genes were exchanged with the upstream regulatory sequence (urs) of the fdhf gene from escherichia coli. they were analysed for their regulatory response under different growth conditions with the aid of fdhf'-'lacz or nif'-'lacz fusions. placement of the uas from the bradyrhizobium japonicum nifh gene in front of the spacer (dna region between urs and promoter) plus promoter ... | 1989 | 2664422 |
| the azorhizobium caulinodans nitrogen-fixation regulatory gene, nifa, is controlled by the cellular nitrogen and oxygen status. | the nucleotide sequence of the azorhizobium caulinodans ors571 nifa locus was determined and the deduced nifa amino acid sequence compared with that of nifa from other nitrogen-fixing species. highly conserved domains, including helix-turn-helix and atp-binding motifs, and specific conserved residues, such as a cluster of cysteines, were identified. the nifa 5' upstream region was found to contain dna sequence motifs highly homologous to promoter elements involved in nifa/ntr-mediated control an ... | 1989 | 2664425 |
| identification of dna regions homologous to nitrogen fixation genes nife, nifus and fixabc in azospirillum brasilense sp7. | a 30 kb dna region from azospirillum brasilense sp7, containing the nitrogenase structural genes (nifhdk), has been cloned. the presence of nif genes, in the 20 kb located next to nifhdk, was explored by tn5 mutagenesis after subcloning various restriction fragments in the broad-host-range suicide vehicle psup202. over 25 mutations due to tn5 random insertions were obtained in the 20 kb and each recombined into the genome of strain sp7. four new nif loci were identified, located at about 4, 9, 1 ... | 1989 | 2695597 |