Publications

TitleAbstractYear(sorted ascending)
Filter
PMID
Filter
variability in molybdenum uptake activity in bradyrhizobium japonicum strains.twenty naturally occurring strains of bradyrhizobium japonicum in 11 serogroups were screened for the ability to take up mo as bacteroids from soybean root nodules. the strains varied greatly in their ability to take up mo in a 1-min period. the best strain was usda 136, which had an mo uptake activity of almost 3.0 pmol/min per mg of bacteroid (dry weight). in contrast, the poorest strain, usda 62, had an mo uptake activity of 0.35 pmol of mo per min per mg of bacteroid. there were similarities ...19873473064
bradyrhizobium japonicum mutants defective in nitrogen fixation and molybdenum metabolism.bradyrhizobium japonicum jh mutants deficient in molybdenum metabolism into the enzymes nitrogenase and nitrate reductase were isolated by using the vector psup1011, which carries transposon tn5 (streptomycin and kanamycin resistance). mutants in mo metabolism were obtained at a frequency of 3.6 x 10(-3) (per kan strr colony). the mutants were detected by their poor ability to grow in nitrate-containing medium without added mo. one of the mutant types required 10(5) times more molybdate than the ...19873473063
effect of ph on tritium exchange and hydrogen production and uptake in free-living cells and in bacteroids of bradyrhizobium japonicum.soybean nodule bacteroids and bradyrhizobium japonicum free-living cells induced for h2-uptake hydrogenase, actively catalyze the evolution of h2 in a reaction highly dependent on the ph. the optimal phs for the evolution and uptake reactions were 4.0 and 7.5-8.0, respectively. no differences were found between free-living cells and bacteroids with respect to hydrogen acceptor specificity, although absolute rates of h2 uptake were higher for free-living cells. both types of cells were able to ev ...19873322198
expression of uptake hydrogenase and hydrogen oxidation during heterotrophic growth of bradyrhizobium japonicum.strains i-110 ars, sr, usda 136, usda 137, and ak13 1c of bradyrhizobium japonicum induced hup activity when growing heterotrophically in medium with carbon substrate and nh4cl in the presence of 2% h2 and 2% o2. hup activity was induced during heterotrophic growth in the presence of carbon substrates, which were assimilated during the time of h2 oxidation. strains i-110 ars and sr grown heterotrophically or chemoautotrophically for 3 days had similar rates of h2 oxidation. similar rates of hup ...19873115959
analysis of lectin binding by bradyrhizobium japonicum strains grown on nitrocellulose filters using peroxidase-labeled lectin.a procedure was developed to assess the ability of wild-type and mutant strains of bradyrhizobium japonicum to bind soybean lectin. the lectin-binding ability of bacteria grown on nitrocellulose filters was determined using peroxidase-labeled soybean lectin. the assay produced clear differences between strains known to be unable to bind soybean lectin and those which can. the assay gave results identical to those of the fluorescein isothiocyanate-soybean lectin-binding assay of t. v. bhuvaneswar ...19873118739
cell surface polysaccharides from bradyrhizobium japonicum and a nonnodulating mutant.the cell surface polysaccharides of wild-type bradyrhizobium japonicum usda 110 and a nonnodulating mutant, strain hs123, were analyzed. the capsular polysaccharide (cps) and exopolysaccharide (eps) of the wild type and the mutant strain do not differ in their sugar composition. cps and eps are composed of mannose, 4-o-methylgalactose/galactose, glucose, and galacturonic acid in a ratio of 1:1:2:1, respectively. h nuclear magnetic resonance spectra of the eps and cps of the wild type and mutant ...19873793715
mapping and nucleotide sequence of the nifs promoter of bradyrhizobium japonicum. 19873684606
nucleotide sequence of the gene encoding the nitrogenase iron protein of thiobacillus ferrooxidans.the dna sequence was determined for the cloned thiobacillus ferrooxidans nifh and part of the nifd genes. a putative t. ferrooxidans nifh promoter was identified whose sequences showed perfect consensus with those of the klebsiella pneumoniae nif promoter. two putative consensus upstream activator sequences were also identified. the amino acid sequence was deduced from the dna sequence. in a comparison of nifh dna sequences from t. ferrooxidans and eight other nitrogen-fixing microbes, a rhizobi ...19873539923
nickel uptake in bradyrhizobium japonicum.free-living bradyrhizobium japonicum grown heterotrophically with 1 microm 63ni2+ accumulated label. strain sr470, a hupc mutant, accumulated almost 10-fold more 63ni2+ on a per-cell basis than did strain sr, the wild type. nongrowing cells were also able to accumulate nickel over a 2-h period, with the hupc mutant strain sr470 again accumulating significantly more 63ni2+ than strain sr. these results suggest that this mutant is constitutive for nickel uptake as well as for hydrogenase expressio ...19873558318
transposon-induced symbiotic mutants of bradyrhizobium japonicum: isolation of two gene regions essential for nodulation.two strains of the soybean endosymbiont bradyrhizobium japonicum, usda 110 and 61 a101 c, were mutagenized with transposon tn5. after plant infection tests of a total of 6,926 kanamycin and streptomycin resistant transconjugants, 25 mutants were identified that are defective in nodule formation (nod-) or nitrogen fixation (fix-). seven nod- mutants were isolated from strain usda110 and from strain 61 a101 c, 4 nod- mutants and 14 fix- mutants were identified. subsequent auxotrophic tests on thes ...19873037278
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.19872446767
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
conformational changes in the membrane-bound hydrogenase of bradyrhizobium japonicum. evidence that the redox state of the enzyme affects its accessibility to protease and membrane-impermeant reagents.the sensitivity of the membrane-bound hydrogenase of bradyrhizobium japonicum to inactivation by proteases and membrane-impermeant protein modification reagents was compared under hydrogen versus oxygen. in membrane vesicles, the half-life of enzyme inactivation by trypsin of the h2-reduced enzyme was approximately 10 min, whereas o2-oxidized enzyme was much less sensitive to trypsin inactivation (half-life of over 90 min). diazobenzene sulfonate (dabs) affected the enzyme activity in a manner s ...19883053719
nucleotide sequence of the genetic loci encoding subunits of bradyrhizobium japonicum uptake hydrogenase.an indispensable part of the hydrogen-recycling system in bradyrhizobium japonicum is the uptake hydrogenase, which is composed of 34.5- and 65.9-kda subunits. the gene encoding the large subunit is located on a 5.9-kilobase fragment of the h2-uptake-complementing cosmid phu52 [zuber, m., harker, a.r., sultana, m.a. & evans, h.j. (1986) proc. natl. acad. sci. usa 83, 7668-7672]. we have now determined that the structural genes for both subunits are present on this fragment. two open reading fram ...19883054886
selenium increases hydrogenase expression in autotrophically cultured bradyrhizobium japonicum and is a constituent of the purified enzyme.we have investigated the effect of added selenite on autotrophic growth and the time course of hydrogen oxidation derepression in bradyrhizobium japonicum 122des cultured in a medium purified to remove selenium compounds. in addition, hydrogenase was purified to near homogeneity and examined for the specific incorporation of se into the enzyme. the addition of se at 0.1 microm significantly increased total cell protein and hydrogenase specific activity of harvested cells. also, the addition of s ...19883056905
rhizobium japonicum usda 191 has two nodd genes that differ in primary structure and function.several rhizobium genes (designated nod genes) are involved in early steps in nodule formation. here we present the results of dna sequence and functional analysis of two nodd genes from the symbiotic plasmid of usda 191, a fast-growing strain that forms nitrogen-fixing nodules on soybeans. both genes encoded full-length nodd-related polypeptides, which were 69% homologous to each other. one of these genes, nodd1, complemented a rhizobium trifolii nodd::tn5 mutant for clover nodulation; the othe ...19882826389
cloning and sequencing of the genes encoding the large and the small subunits of the h2 uptake hydrogenase (hup) of rhodobacter capsulatus.the structural genes (hup) of the h2 uptake hydrogenase of rhodobacter capsulatus were isolated from a cosmid gene library of r. capsulatus dna by hybridization of bradyrhizobium japonicum. the r. capsulatus genes were localized on a 3.5 kb hindiii fragment. the fragment, cloned onto plasmid pac76, restored hydrogenase activity and autotrophic growth of the r. capsulatus mutant jp91, deficient in hydrogenase activity (hup-). the nucleotide sequence, determined by the dideoxy chain termination me ...19883067084
characterization of the rhizobium leguminosarum genes nodlmn involved in efficient host-specific nodulation.three nodulation genes, nodl, nodm and nodn, were isolated from rhizobium leguminosarum and their dna sequences were determined. the three genes are in the same orientation as the previously described nodfe genes and the predicted molecular weights of their products are 20,105 (nodl), 65,795 (nodm) and 18,031 (nodn). analysis of gene regulation using operon fusions showed that nodl, nodm and nodn are induced in response to flavanone molecules and that this induction is nodd-dependent. in additio ...19883132583
regulation of the fixa gene and fixbc operon in bradyrhizobium japonicum.the transcriptional start site of the bradyrhizobium japonicum fixbc operon was identified by nuclease s1 mapping. it was located approximately 700 base pairs upstream of fixb and was preceded by a promoter sequence that showed strong homology to the b. japonicum fixa promoter and thus to the general nif consensus promoter sequence. further transcript mapping experiments revealed that fixa and fixbc transcription in b. japonicum strictly depended on the presence of the regulatory gene nifa and o ...19883343218
lack of carbon substrate repression of uptake hydrogenase activity in bradyrhizobium japonicum sr.the expression of ex planta uptake hydrogenase (hup) activity in bradyrhizobium japonicum sr induced in the absence or presence of carbon substrates was compared. hup activity was influenced by ph, indicating that acidification of induction medium with low buffering capacity resulting from carbon substrate metabolism inhibited hup activity. cell suspensions in medium with adequate buffering capacity and carbon substrate were limited in o2; increasing o2 availability to cells during induction sti ...19883350794
regulation of nod gene expression in bradyrhizobium japonicum.the best inducers of nod::lacz translational fusions in bradyrhizobium japonicum are isoflavones, primarily genistein and daidzein. upstream of the nodabc genes in b. japonicum is a novel gene, nody, which is coregulated with nodabc. measurements of the activity of lacz fusions to the nodd gene of b. japonicum show that this gene is inducible by soybean seed extract and selected flavonoid chemicals. the induction of the nody abc and nodd operons appears to require a functional nodd gene, indicat ...19883146016
identification of a new bradyrhizobium japonicum gene (frxa) encoding a ferredoxinlike protein.an open reading frame of 74 codons was identified downstream of the nifb gene of bradyrhizobium japonicum 110. the predicted amino acid sequence shared 63% similarity with the rhodopseudomonas palustris ferredoxin i sequence. we propose to name the gene frxa. the frxa gene was found to be cotranscribed with the nifb gene. an insertion mutation within frxa hardly affected nitrogen fixation activity.19883350797
dicarboxylic acid transport in bradyrhizobium japonicum: use of rhizobium meliloti dct gene(s) to enhance nitrogen fixation.a recombinant plasmid encoding rhizobium meliloti sequences involved in dicarboxylic acid transport (plasmid prk290:4:46) (e. bolton, b. higgisson, a. harrington, and f. o'gara, arch. microbiol. 144:142-146, 1986) was used to study the relationship between dicarboxylic acid transport and nitrogen fixation in bradyrhizobium japonicum. the expression of the dct sequences on plasmid prk290:4:46 in b. japonicum cj1 resulted in increased growth rates in media containing dicarboxylic acids as the sole ...19883422072
quantitative assay for binding of bradyrhizobium japonicum to cultured soybean cells.incubation of bradyrhizobium japonicum with the cultured soybean cell line sb-1 resulted in the adhesion of the bacteria to the plant cells. an antiserum was raised against b. japonicum, and the 125i-labeled immunoglobulin fraction was used to quantitate the number of bacteria bound to the soybean cells. the measurement of 125i-labeled antibody binding correlated well with parallel assays by microscopic observation. using this quantitation, we have optimized the parameters of the assay in terms ...19883410819
role of the bradyrhizobium japonicum ntrc gene product in differential regulation of the glutamine synthetase ii gene (glnii).we isolated the ntrc gene from bradyrhizobium japonicum, the endosymbiont of soybean (glycine max), and examined its role in regulating nitrogen assimilation. two independent ntrc mutants were constructed by gene replacement techniques. one mutant was unable to produce ntrc protein, while the other constitutively produced a stable, truncated ntrc protein. both ntrc mutants were unable to utilize potassium nitrate as a sole nitrogen source. in contrast to wild-type b. japonicum, the ntrc null mut ...19882903856
essential and non-essential domains in the bradyrhizobium japonicum nifa protein: identification of indispensable cysteine residues potentially involved in redox reactivity and/or metal binding.the amino acid sequence of the bradyrhizobium japonicum nitrogen fixation regulatory protein nifa, as derived from the nucleotide sequence of the nifa gene, was aligned to the corresponding protein sequences from klebsiella pneumoniae, rhizobium meliloti and rhizobium leguminosarum biovar viciae. high conservation was found in the central domain and in the cooh-terminal, putative dna binding domain, whereas very little homology was present within the first 250 amino acids from the nh2-terminus. ...19883357773
molybdate transport by bradyrhizobium japonicum bacteroids.bacteroid suspensions of bradyrhizobium japonicum usda 136 isolated from soybeans grown in mo-deficient conditions were able to transport molybdate at a nearly constant rate for up to 1 min. the apparent km for molybdate was 0.1 microm, and the vmax was about 5 pmol/min per mg (dry weight) of bacteroid. supplementation of bacteroid suspensions with oxidizable carbon sources did not markedly increase molybdate uptake rates. anaerobically isolated bacteroids accumulated twice as much mo in 1 h as ...19883192511
in vitro and in vivo antibacterial activities of me1207, a new oral cephalosporin.me1207 (pivaloyloxymethyl ester of me1206) is a new oral cephalosporin. me1206 is (6r,7r)-7-[(z)-2-(2-aminothiazol-4-yl)-2-(methoxyimino)- acetamido]-3-[(z)-2-(4-methylthiazol-5-yl)-ethyl]-cephem-4-carboxy lic acid. the susceptibilities of about 1,600 clinical isolates to me1206 were determined by the agar dilution method. me1206 showed a broad spectrum of activity against gram-positive and gram-negative bacteria. me1206 was more active than cefaclor, t-2525, and cefixime against staphylococcus ...19883264132
identification of the klebsiella pneumoniae glnb gene: nucleotide sequence of wild-type and mutant alleles.the glnb gene of klebsiella pneumoniae, which encodes the nitrogen regulation protein pii, has been cloned and sequenced. the gene encodes a 12429 dalton polypeptide and is highly homologous to the escherichia coli glnb gene. the sequences of a glnb mutation which causes glutamine auxotrophy and of a tn5 induced gln+ suppressor of this mutation were also determined. the glutamine auxotrophy was deduced to be the result of a modification of the uridylylation site of pii, and the suppression was s ...19882907369
distinct structural features of the alpha and beta subunits of nitrogenase molybdenum-iron protein of clostridium pasteurianum: an analysis of amino acid sequences.nitrogenase is composed of two separately purified proteins, a molybdenum-iron (mofe) protein and an iron (fe) protein. structural genes (nifd and nifk) encoding alpha and beta subunits of the mofe protein of clostridium pasteurianum (cp) have been cloned and sequenced. the deduced amino acid sequences were analyzed for structures that could be related to the unique properties of the cp protein, particularly its low capacity to form an active enzyme with a heterologous fe protein. cp nifk is loc ...19882840948
nodulation, nitrogen fixation, and hydrogen oxidation by pigeon pea bradyrhizobium spp. in symbiotic association with pigeon pea, cowpea, and soybean.the pigeon pea strains of bradyrhizobium cc-1, cc-8, uasgr(s), and f4 were evaluated for nodulation, effectiveness for n(2) fixation, and h(2) oxidation with homologous and nonhomologous host plants. strain cc-1 nodulated macroptilium atropurpureum, vigna unguiculata, glycine max, and g. soja but did not nodulate pisum sativum, phaseolus vulgaris, trigonella foenum-graecum, and trifolium repens. strain f4 nodulated g. max cv. peking and pi 434937 (malayan), but the symbioses formed were poor. si ...198816347542
transposon tn5-generated bradyrhizobium japonicum mutants unable to grow chemoautotrophically with h(2).twelve tn5-induced mutants of bradyrhizobium japonicum unable to grow chemoautotrophically with co(2) and h(2) (aut) were isolated. five aut mutants lacked hydrogen uptake activity (hup). the other seven aut mutants possessed wild-type levels of hydrogen uptake activity (hup), both in free-living culture and symbiotically. three of the hup mutants lacked hydrogenase activity both in free-living culture and as nodule bacteroids. the other two mutants were hup only in free-living culture. the latt ...198816347549
expression and functional analysis of the rhizobium meliloti nifa gene.the translational initiation point for rhizobium meliloti nifa, the specific activator for nitrogen fixation (nif) genes, was determined. when expressed in an escherichia coli linked transcriptional-translational system the dna coding for the r.meliloti nifa gene produced four polypeptide bands of 71 000, 67 000, 62 000 and 59 000 daltons. there are three in-frame atg codons at the n-terminus of the gene; by replacing the poor ribosome binding sites of the native dna with a synthetic consensus r ...198816453824
effects of bradyrhizobium japonicum and soybean (glycine max (l.) merr.) phosphorus nutrition on nodulation and dinitrogen fixation.cells of bradyrhizobium japonicum were grown in media containing either 1.0 mm or 0.5 mum phosphorus. in growth pouch experiments, infection of the primary root of soybean (glycine max (l.) merr.) by b. japonicum usda 31, 110, and 142 was significantly delayed when p-limited cells were applied to the root. in a greenhouse experiment, b. japonicum usda 31, 110, 122, and 142 grown with sufficient and limiting p were used to inoculate soybeans which were grown with either 5 mum or 1 mm p nutrient s ...198816347750
stability of bradyrhizobium japonicum inoculants after introduction into soil.bradyrhizobium japonicum usda 125-sp, usda 138, and usda 138-sm had been used as inoculants for soybean (glycine max (l.) merr.) in soils previously free of b. japonicum. at 8 to 13 years after their release, these strains were reisolated from soil samples. a total of 115 isolates were obtained through nodules, and seven colonies were obtained directly by a serological method. the stability of the inoculants was confirmed by comparing the reisolated cultures with their respective parental strain ...198816347768
dna probe method for the detection of specific microorganisms in the soil bacterial community.we developed a protocol which yields purified bacterial dna from the soil bacterial community. the bacteria were first dispersed and separated from soil particles in the presence of polyvinylpolypyrrolidone, which removes humic acid contaminants by adsorption to this insoluble polymer. the soil bacteria were then collected by centrifugation and lysed by using a comprehensive protocol designed to maximize disruption of the various types of bacteria present. total bacterial dna was purified from t ...198816347582
synthesis of exopolysaccharide by bradyrhizobium japonicum during growth on hydroaromatic substrates.the hydroaromatic acids shikimate and quinate, which may be available as carbon sources in the soil, supported production of only low levels of acidic exopolysaccharide by bradyrhizobium japonicum. exopolysaccharide production (micrograms per 10 cells) was 4.9 on quinate and 4.5 on shikimate; in comparison, it was 128 on adipate, 18 on l-arabinose, and 39 on d-glucose.198816347670
early infection and competition for nodulation of soybean by bradyrhizobium japonicum 123 and 138.interactions of soybean with bradyrhizobium japonicum 123 (serogroup 123) and 138 (serogroup c1) were used to examine the relationship between early infection rates, competition for nodulation, and patterns of nodule occupancy. both strains formed more infections in autoclaved soil (sterile soil) than in untreated soil (unsterile soil). inoculation did not increase numbers of infection threads in unsterile soil-grown plants, where infection of proximal portions of primary roots was complete by 5 ...198816347710
cloning and mapping of a novel nodulation region from bradyrhizobium japonicum by genetic complementation of a deletion mutant.the phenotypes of a set of bradyrhizobium japonicum 110 mutants with large deletions in the region of symbiotic gene cluster i were tested. the majority of the mutants showed a delayed nodulation on soybean and, by mixed-infection experiments, were found to be strongly reduced in their competitiveness. phenotypic comparison of mutants with different deletion endpoints allowed a preliminary localization of two genomic regions, called nod-1 and nod-2, which were required for normal nodulation on s ...198816347539
influence of glycine spp. on competitiveness of bradyrhizobium japonicum and rhizobium fredii.the displacement of indigenous bradyrhizobium japonicum in soybean nodules with more effective strains offers the possibility of enhanced n(2) fixation in soybean (glycine max (l.) merr.). our objective was to determine whether the wild soybean (g. soja sieb. & zucc.) genotype pi 468397 would cause reduced competitiveness of important indigenous b. japonicum strains usda 31, 76, and 123 and thereby permit nodulation by rhizobium fredii, the fast-growing microsymbiont of soybean. in an initial ex ...198816347589
numerical taxonomic analysis of some strains of rhizobium spp. that uses a qualitative coding of immunodiffusion reactions.antigenic relationships among seven strains of bradyrhizobium japonicum were examined by immunodiffusion reactions, in which cells of each strain were reacted against each of the seven corresponding antisera. similar analyses were performed with rhizobium trifolii (28 strains), rhizobium meliloti (9 strains), and rhizobia of the cowpea miscellany (13 strains). antigens and antisera were reacted within each species only; serological interspecies cross-reactions were not performed. the results, sc ...198816347692
efficiency of nodule initiation in cowpea and soybean.when serial dilutions of a suspension of bradyrhizobium japonicum strain 138 were inoculated onto both soybean and cowpea roots, the formation of nodules in the initially susceptible region of the roots of both hosts was found to be linearly dependent on the log of the inoculum dosage until an optimum dosage was reached. approximately 30- to 100-fold higher dosages were required to elicit half-maximal nodulation on cowpea than on soybean in the initially susceptible zone of the root. however, at ...198816666056
isolation of genes involved in nodulation competitiveness from rhizobium leguminosarum bv. trifolii t24.rhizobium leguminosarum bv. trifolii t24 produces a potent anti-rhizobial compound, trifolitoxin, and exclusively nodulates clover roots when in mixed inoculum with trifolitoxin-sensitive strains of r. leguminosarum bv. trifolii [schwinghamer, e. a. & belkengren r. p. (1968) arch. mikrobiol. 64, 130-145]. in the present study, the isolation of trifolitoxin production and resistance genes is described. a cosmid genomic library of t24 was prepared in plafr3. no trifolitoxin expression was observed ...198816593933
the glycine-glomus-rhizobium symbiosis : vii. photosynthetic nutrient-use efficiency in nodulated, mycorrhizal soybeans.four consecutive trifoliate leaves of 56-day-old symbiotic or nonsymbiotic soybean plants were evaluated individually for co(2) exchange rates (cer), leaf area and dry weight, and leaf n, p, and starch concentrations. plants had been inoculated with the vesicular-arbuscular mycorrhizal (vam) fungus glomus mosseae and rhizobium japonicum, with either of the endophytes alone, or with neither at time of planting. plants lacking one or both endophytes received n and/or p fertilizers to produce plant ...198816666069
regulation of o(2) concentration in soybean nodules observed by in situ spectroscopic measurement of leghemoglobin oxygenation.a fiber optic spectrophotometric system was used to monitor the in vivo oxygenation of leghemoglobin in intact, attached soybean root nodules (glycine max l. merr. x usda 16 bradyrhizobium japonicum) which were flattened during development by growth in narrow, glass-walled cuvettes. when equilibrated at an external po(2) of 20 kilopascals, leghemoglobin was 36.6 +/- 5.4% oxygenated, a value estimated to represent an infected cell o(2) concentration of 21.5 nanomolar. increasing the external po(2 ...198816666136
when does the self-regulatory response elicited in soybean root after inoculation occur?the inoculation of soybean (glycine max l.) roots with bradyrhizobium japonicum produces a regulatory response that inhibits nodulation in the younger regions of the roots. by exposing the soybean roots to live homologous bacteria for only a short period of time, the question of whether or not early interactions of rhizobia with root cells, prior to infection, elicit this regulatory response has been explored. b. japonicum cells mixed with infective bacteriophages were applied to the roots and t ...198816666343
uniformity of the microsymbiont population from soybean nodules with respect to buoyant density.the microsymbiont population in soybean root nodules (glycine max l. cv williams 82 inoculated with bradyrhizobium japonicum 2143) was characterized during symbiotic development to determine the extent of heterogeneity in this population. the microsymbiont population was isolated by centrifugation through a continuous sucrose gradient (44 to 57% weight to weight ratio) and appeared homogeneous at each age examined up to 26 days after planting based on the symmetrical distribution of the populati ...198816665972
utilization of nitrate by bacteroids of bradyrhizobium japonicum in the soybean root nodule.bacteroids of bradyrhizobium japonicum strain cb1809, unlike cc705, do not have a high level of constitutive nitrate reductase (nr; ec 1.7.99.4) in the soybean (glycine max. merr.) nodule. ex planta both strains have a high activity of nr when cultured on 5 mm nitrate at 2% o2 (v/v). nitrite reductase (nir) was active in cultured cells of bradyrhizobia, but activity with succinate as electron donor was not detected in freshly-isolated bacteroids. a low activity was measured with reduced methyl v ...198824221417
enhanced nodule initiation on alfalfa by wild-typerhizobium meliloti co-inoculated withnod gene mutants and other bacteria.nodule formation on alfalfa (medicago sativa l.) roots was determined at different inoculum dosages for wild-typerhizobium meliloti strain rcr2011 and for various mutant derivatives with altered nodulation behavior. the number of nodules formed on the whole length of the primary roots was essentially constant regardless of initial inoculum dosage or subsequent bacterial multiplication, indicative of homeostatic regulation of total nodule number. in contrast, the number of nodules formed in just ...198824221521
particle density and protein composition of the peribacteroid membrane from soybean root nodules is affected by mutation in the microsymbiont bradyrhizobium japonicum.particle frequency of the peribacteroid membrane (pbm) from nodules of glycine max (l.) merr. cv. maple arrow infected with bradyrhizobium japonicum 61-a-101 (wild-type strain) was determined by freeze-fracturing to be about 2200·μm(-2) in the protoplasmic fracture face and 700·μm(-2) in the exoplasmic fracture face. in membranes isolated from nodules infected with the mutant rh 31-marburg of b. japonicum, the particle frequency was similar in both fracture faces with 1200-1300 particles·μm(-2). ...198824221484
visualization of bioluminescence as a marker of gene expression in rhizobium-infected soybean root nodules.the linked structural genes lux a and lux b, encoding bacterial luciferase of a marine bacterium vibrio harveyi, were fused with the nitrogenase nifd promoter from bradyrhizobium japonicum and with the p1 promoter of pbr322. both fusions were integrated into the b. japonicum chromosome by site-specific recombination. soybean roots infected with the two types of rhizobium transconjugants formed nitrogen-fixing nodules that produced bright blue-green light. cells containing the p1 promoter/lux ab ...198824277587
the occurrence of leghemoglobin protein in the uninfected interstitial cells of soybean root nodules.the distribution of leghemoglobin (lb) in resin-embedded root nodules of soybean (glycine max (l.) merr.) was investigated using immunogold labeling. using anti-lb immunoglobulin g and protein a-gold, lb or its apoprotein was detected both in cells infected by bradyrhizobium japonicum and in uninfected interstitial cells. leghemoglobin was present in the cytoplasm, exclusive of the organelles, and in the nuclei of both cell types. in a comparison of the density of labeling in adjacent pairs of i ...198824221924
pectate distribution and esterification in dubautia leaves and soybean nodules, studied with a fluorescent hybridization probe.carbohydrate-hybridization probes (vreeland and laetsch, 1989, planta (177, 423-434) were used to localize the homogalacturonan (pectate) component of pectins in the cell walls of leaves and soybean root nodules. leaves of two species of the dicotyledon dubautia were compared; these species contain much pectin but differ in their tissue water relations with respect to their cell-wall properties. maturation of the primary cell walls in nodules was studied in the bradyrhizobium japonicum-glycine m ...198924212485
peribacteroid membrane nodulin gene induction by bradyrhizobium japonicum mutants.seventeen translation products from glycine max root mrna precipitated with antiserum prepared against a peribacteroid membrane preparation from effective root nodules. messenger rna from fix (+) nodules coded for these 17 products plus 7 other nodule-specific polypeptides which bound to the antiserum. of these 7 nodulins only 4 were present when nodules were infected with bradyrhizobium japonicum 110 rif 15 2960, which induces the plant to produce 'empty' peribacteroid membranes. in nodules inf ...198924272866
occurrence of h(2)-uptake hydrogenases in bradyrhizobium sp. (lupinus) and their expression in nodules of lupinus spp. and ornithopus compressus.fifty-four strains of bradyrhizobium sp. (lupinus) from worldwide collections were screened by a colony hybridization method for the presence of dna sequences homologous to the structural genes of the bradyrhizobium japonicum hydrogenase. twelve strains exhibited strong colony hybridization signals, and subsequent southern blot hybridization experiments showed that they fell into two different groups on the basis of the pattern of ecori fragments containing the homology to the hup probe. all str ...198916666550
in vivop nmr spectroscopic studies of soybean bradyrhizobium symbiosis: i. optimization of parameters.(31)p nmr spectroscopy was used to study in vivo the symbiotic state established between soybean (glycine max [l.] merr. cv williams) and bradyrhizobium japonicum (usda 110 and 138). different experimental conditions were used to maintain perfused, respiring detached or attached nodules in an nmr magnet. the ph of the perfusion medium affected the cytoplasmic ph and the resolution of the spectra. the internal pi content and distribution were assessed as a function of nodule age and green-house g ...198916666690
cytokinin production by bradyrhizobium japonicum.although there is considerable circumstantial evidence for the involvement of cytokinins in legume nodulation, the cytokinins produced by rhizobia have not been well characterized. bradyrhizobium japonicum 61a68, a bacterium which nodulates soybean (glycine max [l.] merr.), was grown in defined medium. cytokinins were purified from the culture medium by amberlite xad-2 chromatography and fractionated by column chromatography on sephadex lh-20 in 35% ethanol. pooled fractions from the sephadex co ...198916666691
cytochrome mutants of bradyrhizobium induced by transposon tn5.transposon tn5 was used to mutate bradyrhizobium japonicum usda 61n. from over 5000 clones containing tn5, 12 were selected and purified using a chemical reaction to identify oxidase-deficient clones. four classes of mutants were identified based on the alterations in cytochromes. most of the mutants had alterations in more than one cytochrome. southern hybridization analysis of restricted genomic dna of a representative strain of each class demonstrated that each mutant had a single tn5 insert. ...198916666807
hydrogen inhibition of nitrogen reduction by nitrogenase in isolated soybean nodule bacteroids.dihydrogen, a by-product of biological nitrogen fixation, is a competitive inhibitor of n(2) reduction by nitrogenase. to evaluate the significance of h(2) inhibition in vivo, we have measured the apparent inhibition constant for h(2) inhibition of n(2) reduction in bradyrhizobium japonicum bacteroids isolated from soybean nodules. the rate of n(2) reduction was measured as ammonia production by bacteroids incubated in a buffer containing 200 micromolar leghemoglobin and 10 millimolar succinate ...198916667084
lack of systemic suppression of nodulation in split root systems of supernodulating soybean (glycine max [l.] merr.) mutants.wild-type soybean (glycine max [l] merr. cv bragg) and a nitrate-tolerant supernodulating mutant (nts382) were grown in split root systems to investigate the involvement of the autoregulation response and the effect of timing of inoculation on nodule suppression. in bragg, nodulation of the root portion receiving the delayed inoculation was suppressed nearly 100% by a 7-day prior inoculation of the other root portion with bradyrhizobium japonicum strain usda 110. significant suppression was also ...198916666934
selection and initial characterization of partially nitrate tolerant nodulation mutants of soybean.since no(3) (-) availability in the rooting medium seriously limits symbiotic n(2) fixation by soybean (glycine max [l.] merr.), studies were initiated to select nodulation mutants which were more tolerant to no(3) (-) and were adapted to the midwest area of the united states. three independent mutants were selected in the m(2) generation from ethyl methanesulfonate or n-nitroso-n-methylurea mutagenized williams seed. all three mutants (designated nod1-3, nod2-4, and nod3-7) were more extensivel ...198916666510
bradyrhizobium japonicum survival in and soybean inoculation with fluid gels.the utilization of gels, which are used for fluid drilling of seeds, as carriers of bradyrhizobium japonicum for soybean (glycine max (l.) merr.) inoculation was studied. gels of various chemical composition (magnesium silicate, potassium acrylate-acrylamide, grafted starch, and hydroxyethyl cellulose) were used, although the hydroxyethyl cellulose gels were more extensively investigated. gel inocula were prepared by mixing gel powder with liquid cultures of b. japonicum (2% [wt/vol]). the popul ...198916347870
identification of a locus upstream from the hydrogenase structural genes that is involved in hydrogenase expression in bradyrhizobium japonicum.a locus involved in the expression of the uptake hydrogenase system of bradyrhizobium japonicum was identified adjacent to genes encoding the hydrogenase subunits. a cloned fragment of dna was used to complement to autotrophy a hup putative regulatory mutant of b. japonicum. the mutant strain lacked hydrogenase activity and synthesized low levels of the large subunit of hydrogenase as determined by western gels. tn5-induced mutagenesis located the region within the fragment which was necessary f ...198916348066
nodulation of glycine max by six bradyrhizobium japonicum strains with different competitive abilities.the root nodule locations of six bradyrhizobium japonicum strains were examined to determine if there were any differences which might explain their varying competitiveness for nodule occupancy on glycine max. when five strains were added to soybeans in plastic growth pouches in equal proportions with a reference strain (u.s. department of agriculture, strain 110), north carolina strain 1028 and strain 110 were the most competitive for nodule occupancy, followed by u.s. department of agriculture ...198916347987
bradyrhizobium japonicum inoculant mobility, nodule occupancy, and acetylene reduction in the soybean root system.in the american midwest, superior inoculant rhizobia applied to soybeans usually occupy only 5 to 20% of nodules, and response to inoculation is the exception rather than the rule. attempts to overcome this problem have met with limited success. we evaluated the ability of bradyrhizobium japonicum, supplied as a seed coat inoculant, to stay abreast of the infectible region of the developing soybean root system. the rhizoplane population of the inoculant strain declined with distance from site of ...198916348026
acetate-activating enzymes of bradyrhizobium japonicum bacteroids.acetyl coenzyme a (acetyl-coa) synthetase and acetate kinase were localized within the soluble portion of bradyrhizobium japonicum bacteroids, and no appreciable activity was found elsewhere in the nodule. the presence of each acetate-activating enzyme was confirmed by separation of the two enzyme activities on a hydroxylapatite column, by substrate dependence of each enzyme in both the forward and reverse directions, by substrate specificity, by inhibition patterns, and also by identification o ...198916347818
host plant effects on nodulation and competitiveness of the bradyrhizobium japonicum serotype strains constituting serocluster 123.strains in bradyrhizobium japonicum serocluster 123 are the major indigenous competitors for nodulation in a large portion of the soybean production area of the united states. serocluster 123 is defined by the serotype strains usda 123, usda 127, and usda 129. the objective of the work reported here was to evaluate the ability of two soybean genotypes, pi 377578 and pi 417566, to restrict the nodulation and reduce the competitiveness of serotype strains usda 123, usda 127, and usda 129 in favor ...198916348029
improvement of rhizobium inoculants.a practical approach was used to develop a rhizobium (bradyrhizobium) japonicum inoculant that increases soybean (glycine max (l.) merr.) yield in fields with indigenous rhizobium populations, which typically outcompete strains present in existing commercial inoculants and therefore decrease the value of inoculant use. field tests managed by several universities in the mississippi delta region averaged a 169-kg/ha (p < 0.01) grain yield increase. the inoculant contains a mixture of mutants selec ...198916347891
nodulating competitiveness of a nonmotile tn7 mutant of bradyrhizobium japonicum in nonsterile soil.a nonmotile mutant of bradyrhizobium japonicum serogroup 127 was generated by tn7 mutagenesis and matched with the wild type against a common competitor in studies of soybean nodulation in nonsterile soil. the tn7 mutant was very similar to the wild type in growth rate in culture, soybean lectin-binding ability, flagellar morphology, and nodulating capability, but it had a longer lag phase. competing strains were distributed uniformly in soil in various ratios and at different population densiti ...198916347986
physiological characterization of dicarboxylate-induced pleomorphic forms of bradyrhizobium japonicum.when bradyrhizobium japonicum i-110 was transferred into medium containing 40 mm succinate or 40 mm fumarate, over 90% of the bacteria acquired a swollen, pleomorphic form similar to that of bacteroids. the induction of pleomorphism was dependent on the carbon substrate and concentration but was independent of the hydrogen ion and sodium ion concentration. cell extracts of rod-shaped and pleomorphic cells contained enzymes required for sugar catabolism and gluconeogenesis. variations in these en ...198916347873
influence of bradyrhizobium japonicum location and movement on nodulation and nitrogen fixation in soybeans.the influence of seed and soil inoculation on bradyrhizobial migration, nodulation, and n(2) fixation was examined by using two bradyrhizobium japonicum strains of contrasting effectiveness in n(2) fixation. seed-inoculated strains formed fewer nodules on soybeans (mostly restricted to the tap and crown roots within 0 to 5 cm from the stem base) than did bradyrhizobia distributed throughout the soil or inoculated at specific depths. nodulation was greater below the depths at which bradyrhizobial ...198916347964
bradyrhizobium japonicum glnb, a putative nitrogen-regulatory gene, is regulated by ntrc at tandem promoters.the glnb gene from bradyrhizobium japonicum, the endosymbiont of soybeans (glycine max), was isolated and sequenced, and its expression was examined under various culture conditions and in soybean nodules. the b. japonicum glnb gene encodes a 12,237-dalton polypeptide that is highly homologous to the glnb gene products from klebsiella pneumoniae and escherichia coli. the gene is located directly upstream from glna (encoding glutamine synthetase), a linkage not observed in enteric bacteria. the g ...19892793830
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 ...19892498290
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 ...19892655535
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 ...19892664422
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 ...19892664425
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 ...19892695597
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
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 ...19892503675
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
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 ...19892535508
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 ...19892559312
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 ...19892563998
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, ...19892552256
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 ...19892624465
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 ...19892473070
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 ...19892491321
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 ...19892492097
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 ...19892536678
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- ...19892548992
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 ...19892555267
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 ...19892575672
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 ...19892542223
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 ...19892547335
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 ...19892541921
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 ...19892597153
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 ...19892646294
mutational analysis of the bradyrhizobium japonicum common nod genes and further nod box-linked genomic dna regions.by insertional and deletional marker replacement mutagenesis the common nod region of bradyrhizobium japonicum was examined for the presence of additional, essential nodulation genes. an open reading frame located in the 800 bp large intergenic region between nodd1 and noda did not appear to be essential for nodulation of soybean. furthermore, a strain with a deletion of the nodi- and nodj-like genes downstream of nodc had a nod+ phenotype. a mutant with a 1.7 kb deletion immediately downstream ...19892710106
dual control of the bradyrhizobium japonicum symbiotic nitrogen fixation regulatory operon fixr nifa: analysis of cis- and trans-acting elements.aerobic expression of the fixr nifa operon in bradyrhizobium japonicum was shown to depend on a cis-acting, promoter-upstream dna sequence located between the -24/-12 promoter and position -86 relative to the transcription start site. an adenine at position -66 was essential for maximal expression. a chromosomal deletion of the upstream activator sequence (uas) led to a symbiotically defective phenotype which was typical of nifa mutants. b. japonicum crude extracts contained a protein that bound ...19892753853
cytoplasmic membrane systems involved in bacterium release into soybean nodule cells as studied with two bradyrhizobium japonicum mutant strains.two bradyrhizobium japonicum, tn5-induced, mutant strains, ml126 and ml150, were studied. both induce host cell division to form normal-sized nodules that do not fix nitrogen and whose cells have very few bacteroids (bar-). early-infection (15 days post infection) cells have much endoplasmic reticulum (er), numerous golgi bodies, and large vacuoles that are probably secondary lysosomes. later the cytoplasm of the host cells of both are dominated by hundreds of vesicles containing only finely fib ...19892759102
Refresh
firstprev
12345678910...
nextlast
Displaying items 401 - 500 of 3597