Publications

reexamination of the intracellular localization of de novo purine synthesis in cowpea nodules.	sucrose and percoll density gradient centrifugation were used to separate organelles from the central zone tissue of cowpea (vigna unguiculata l. walp. cv vita 3: bradyrhizobium strain cb 756) nodules. enzyme activity analysis has shown that both plastids and mitochondria have a full complement of enzymes for de novo purine synthesis. in vitro activities of individual component enzymes (glycinamide ribonucleotide synthetase, ec 6.3.4.13; glycinamide ribonucleotide transformylase, ec 2.1.2.2; ami ...	1997	12223595
the formation of nitrogen-fixing bacteroids is delayed but not abolished in soybean infected by an [alpha]-ketoglutarate dehydrogenase-deficient mutant of bradyrhizobium japonicum.	a mutant strain of bradyrhizobium japonicum usda 110 devoid of [alpha]-ketoglutarate dehydrogenase activity (lsg184) was used to test whether this tricarboxylic acid cycle enzyme is necessary to support nitrogen fixation during symbiosis with soybean (glycine max). lsg184 formed nodules about 5 d later than the wild-type strain, and the nodules, although otherwise normal in structure, contained many fewer infected host cells than is typical. at 19 d after inoculation cells infected with the muta ...	1997	12223774
lipopolysaccharide profiles from nodules as markers of bradyrhizobium strains nodulating wild legumes.	to develop the use of electrophoretic lipopolysaccharide profiles for bradyrhizobium strain identification, we studied the feasibility of using electrophoresis of whole legume nodule homogenates to obtain distinctive lipopolysaccharide profiles. the electrophoretic patterns were the same whether we used nodule extracts, bacteroids, or cultured bacteria as samples, and there was no evidence of changes in the ladder-like pattern during the nodulation process. to assess the reliability of using lip ...	1998	16349529
isolation and characterization of rhodobacter capsulatus mutants affected in cytochrome cbb3 oxidase activity.	the facultative phototrophic bacterium rhodobacter capsulatus contains only one form of cytochrome (cyt) c oxidase, which has recently been identified as a cbb3-type cyt c oxidase. this is unlike other related species, such as rhodobacter sphaeroides and paracoccus denitrificans, which contain an additional mitochondrial-like aa3-type cyt c oxidase. an extensive search for mutants affected in cyt c oxidase activity in r. capsulatus led to the isolation of at least five classes of mutants. plasmi ...	1998	9473054
how replacements of the 12 conserved histidines of subunit i affect assembly, cofactor binding, and enzymatic activity of the bradyrhizobium japonicum cbb3-type oxidase.	alignments of the amino acid sequences of subunit i (fixn or ccon) of the cbb3-type oxidases show 12 conserved histidines. six of them are diagnostic of heme-copper oxidases and are thought to bind the following cofactors: the low spin heme b and the binuclear high spin heme b-cub center. the other six are fixn(ccon)-specific and their function is unknown. to analyze the contribution of these 12 invariant histidines of fixn in cofactor binding and function of the bradyrhizobium japonicum cbb3-ty ...	1998	9497378
rhizobium etli cychjkl gene locus involved in c-type cytochrome biogenesis: sequence analysis and characterization of two cych mutants.	the cychjkl gene locus was cloned from rhizobium etli by the rescue of a tn5mob insertion of a mutant (ifc01) which was affected in the production of c-type cytochromes. the cych, cycj, cyck and cycl genes are proposed to code for different subunits of a haem lyase complex involved in the attachment of haem to cytochrome c apoproteins. cych of 365 aa shared 27, 36, 47 and 63% identity with cych from paracoccus denitrificans, bradyrhizobium japonicum, r. meliloti, and r. leguminosarum, respective ...	1998	9524269
the rhizobium etli rpon locus: dna sequence analysis and phenotypical characterization of rpon, ptsn, and ptsa mutants.	the rpon region of rhizobium etli was isolated by using the bradyrhizobium japonicum rpon1 gene as a probe. nucleotide sequence analysis of a 5,600-bp dna fragment of this region revealed the presence of four complete open reading frames (orfs), orf258, rpon, orf191, and ptsn, coding for proteins of 258, 520, 191, and 154 amino acids, respectively. the gene product of orf258 is homologous to members of the atp-binding cassette-type permeases. orf191 and ptsn are homologous to conserved orfs foun ...	1998	9537369
the active-site cysteines of the periplasmic thioredoxin-like protein ccmg of escherichia coli are important but not essential for cytochrome c maturation in vivo.	a new member of the family of periplasmic protein thiol:disulfide oxidoreductases, ccmg (also called dsbe), was characterized with regard to its role in cytochrome c maturation in escherichia coli. the ccmg protein was shown to be membrane bound, facing the periplasm with its c-terminal, hydrophilic domain. a chromosomal, nonpolar in-frame deletion in ccmg resulted in the complete absence of all c-type cytochromes. replacement of either one or both of the two cysteine residues of the predicted a ...	1998	9537397
roles of the bradyrhizobium japonicum terminal oxidase complexes in microaerobic h2-dependent growth	spectral, inhibitor, and o2-consumption studies on membranes from free-living and bacteroid forms of bradyrhizobium japonicum have revealed the existence of a number of terminal oxidases, and four terminal oxidase gene clusters within the heme-copper cytochrome family have been cloned. here the complexes encoded by coxmnop and coxwxyz, genes with homology to cua-containing cytochrome c oxidases and b-type ubiquinol oxidases respectively, are studied by analysis of mutants in each of the two oxid ...	1998	9554944
isocitrate dehydrogenase and glyoxylate cycle enzyme activities in bradyrhizobium japonicum under various growth conditions.	bradyrhizobium japonicum, the nitrogen-fixing symbiotic partner of soybean, was grown on various carbon substrates and assayed for the presence of the glyoxylate cycle enzymes, isocitrate lyase and malate synthase. the highest levels of isocitrate lyase [165-170 nmol min-1 (mg protein)-1] were found in cells grown on acetate or beta-hydroxybutyrate, intermediate activity was found after growth on pyruvate or galactose, and very little activity was found in cells grown on arabinose, malate, or gl ...	1998	9560426
the bradyrhizobium japonicum phob gene is required for phosphate-limited growth but not for symbiotic nitrogen fixation.	we identified by cloning and dna sequence analysis the phosphate regulatory gene phob of bradyrhizobium japonicum. the deduced gene product displayed pronounced similarity to the phob protein of sinorhizobium meliloti (71.4% identical amino acids). escherichia coli (50.2%) and other bacterial species. insertion of a kanamycin resistance cassette into phob led to impaired growth of the b. japonicum mutant in media containing approximately 25 microm phosphate or less. a standard plant infection te ...	1998	9561731
the rhizobium etli fixl protein differs in structure from other known fixl proteins.	the central heme-binding domain in the fixl proteins of sinorhizobium meliloti, bradyrhizobium japonicum, rhizobium leguminosarum biovar viciae and azorhizobium caulinodans, is highly conserved. the similarity with the corresponding domain in the rhizobium etli fixl protein is considerably less. this observation prompted us to analyze the heme-binding capacities of the r. etli fixl protein. the r. etli fixl gene was overexpressed in escherichia coli. in the presence of s. meliloti fixj, the over ...	1998	9563844
new bradyrhizobium japonicum strains that possess high copy numbers of the repeated sequence rs alpha.	in a survey of dna fingerprints of indigenous bradyrhizobium japonicum with the species-specific repeated sequences rs alpha and rs beta, 21 isolates from three field sites showed numerous rs-specific hybridization bands. the isolates were designated highly reiterated sequence-possessing (hrs) isolates, and their dna hybridization profiles were easily distinguished from the normal patterns. some hrs isolates from two field sites possessed extremely high numbers of rs alpha copies, ranging from 8 ...	1998	9572961
regulation of lipid synthesis in bradyrhizobium japonicum: low oxygen concentrations trigger phosphatidylinositol biosynthesis.	lowering oxygen tension in free-living bradyrhizobium japonicum resulted in a dramatic switch of membrane chemistry in which phosphatidylcholine, the predominant lipid in aerated cultures, was no longer synthesized and phosphatidylethanolamine became the major lipid. besides this change, phosphatidylinositol, a typical plant lipid rarely found in bacteria, was also synthesized.	1998	9572982
promoter selectivity of the bradyrhizobium japonicum rpoh transcription factors in vivo and in vitro.	expression of the dnakj and groesl1 heat shock operons of bradyrhizobium japonicum depends on a sigma32-like transcription factor. three such factors (rpoh1, rpoh2, and rpoh3) have previously been identified in this organism. we report here that they direct transcription from some but not all sigma32-type promoters when the respective rpoh genes are expressed in escherichia coli. all three rpoh factors were purified as soluble c-terminally histidine-tagged proteins, although the bulk of overprod ...	1998	9573191
nolo and noei (hsniii) of rhizobium sp. ngr234 are involved in 3-o-carbamoylation and 2-o-methylation of nod factors.	loci unique to specific rhizobia direct the adjunction of special groups to the core lipo-oligosaccharide nod factors. host-specificity of nodulation (hsn) genes are thus essential for interaction with certain legumes. rhizobium sp. ngr234, which can nodulate >110 genera of legumes, possesses three hsn loci and secretes a large family of nod factors carrying specific substituents. among them are 3-o (or 4-o)- and 6-o-carbamoyl groups, an n-methyl group, and a 2-o-methylfucose residue which may b ...	1998	9575146
characterization of bradyrhizobium japonicum pcabdc genes involved in 4-hydroxybenzoate degradation.	the pca structural genes encode enzymes that participate in the conversion of protocatechuate to succinate and acetylcoenzyme a. a 3. 05-kb region of the bradyrhizobium japonicum strain usda110 genome has been characterized, which contains the pcab, pcad and pcac genes. the predicted protein sequences of the three genes have extensive homologies with beta-carboxy-cis,cis-muconate cycloisomerase (pcab), beta-ketodiapate enol-lactone hydrolase (pcad), and gamma-carboxymuconolactone decarboxylase ( ...	1998	9582432
partial characterization of the lipopolysaccharides of peanut specific bradyrhizobium strains.	hexoses, heptose, hexuronic acids, 2-keto-3-deoxyoctonic acid (kdo) contents of the lipopolysaccharides (lps) isolated from peanut (a. hypogaea) specific bradyrhizobium strains nc 92, igr 92, igr 40 and igr 6 were found to vary considerably. sodium dodecyl sulphate polyacrylamide gel electrophoresis showed a heterogeneous lps population and distinct heterogeneity was observed in nc and igr strains. sepharose gel filtration chromatography removed the hexose contaminants from nc 92 lps. polysaccha ...	1998	9584991
purification of two lectins from a nopalin agrobacterium tumefaciens strain.	lectins were evidenced on the surface of one agrobacterium tumefaciens wild strain (82,139) by agglutination test and neoglycoprotein labelling. bacteria were incubated in the presence of various fluorescein-labelled neoglycoproteins and the binding was assessed by a fluorimetric method. among the fluorescein-labelled neoglycoproteins tested, the one bearing alpha-d-galactosyl residues was the most efficient. the labelling was optimal at ph 5.0 and naught at ph above 7. the binding was specifica ...	1998	9587666
in vivo studies on the positive control function of nifa: a conserved hydrophobic amino acid patch at the central domain involved in transcriptional activation.	the eubacterial enhancer-binding proteins activate transcription by binding to distant sites and, simultaneously, contacting the rna polymerase r54 promoter complex (esigma54). the positive control function is located at the central domain of these proteins, but it is not know which specific region has the determinants for the interaction with esigma54. here, we present genetic evidence that a small region of hydrophobic amino acids, previously denominated c3, at the central domain of bradyrhizo ...	1998	9593296
genotypic characterization of bradyrhizobium strains nodulating endemic woody legumes of the canary islands by pcr-restriction fragment length polymorphism analysis of genes encoding 16s rrna (16s rdna) and 16s-23s rdna intergenic spacers, repetitive extragenic palindromic pcr genomic fingerprinting, and partial 16s rdna sequencing.	we present a phylogenetic analysis of nine strains of symbiotic nitrogen-fixing bacteria isolated from nodules of tagasaste (chamaecytisus proliferus) and other endemic woody legumes of the canary islands, spain. these and several reference strains were characterized genotypically at different levels of taxonomic resolution by computer-assisted analysis of 16s ribosomal dna (rdna) pcr-restriction fragment length polymorphisms (pcr-rflps), 16s-23s rdna intergenic spacer (igs) rflps, and repetitiv ...	1998	9603820
the bradyrhizobium japonicum noed gene: a negatively acting, genotype-specific nodulation gene for soybean.	bradyrhizobium japonicum strain usda 110 is restricted for nodulation by soybean genotype pi 417566. we previously reported the identification of a usda 110 tn5 mutant, strain d4.2-5, that had the ability to overcome nodulation restriction conditioned by pi 417566 (s. m. lohrke, j. h. orf, e. martínez-romero, and m. j. sadowsky, appl. environ. microbiol. 61:2378-2383, 1995). in this study, we report the cloning and characterization of the negatively acting dna region mutated in strain d4.2-5 tha ...	1998	9612946
the fixk2 protein is involved in regulation of symbiotic hydrogenase expression in bradyrhizobium japonicum.	the roles of the nitrogen fixation regulatory proteins nifa, fixk1, and fixk2 in the symbiotic regulation of hydrogenase structural gene expression in bradyrhizobium japonicum have been investigated. bacteroids from fixj and fixk2 mutants have little or no hydrogenase activity, and extracts from these mutant bacteroids contain no hydrogenase protein. bacteroids from a fixk1 mutant exhibit wild-type levels of hydrogenase activity. in beta-galactosidase transcriptional assays with nifa and fixk2 e ...	1998	9620982
a novel dna element that controls bacterial heat shock gene expression.	the hsparpoh1 and hspbcdegp heat shock operons of bradyrhizobium japonicum are preceded by a novel, conserved dna element of approximately 100 bp, which is responsible for the temperature-regulated transcription of their sigma70-type promoters. we designated this motif rose for repression of heat shock gene expression and found additional rose elements upstream of two newly identified heat shock operons. a critical core region in the hspa-associated rose1 was defined by introducing insertions or ...	1998	9622356
in vitro sulfotransferase activity of noee, a nodulation protein of rhizobium sp. ngr234.	soil bacteria of the genera azorhizobium, bradyrhizobium, and rhizobium liberate morphogenetic lipochitin-oligosaccharides (nod factors) into legume rhizospheres. nod factors, which are synthesized by the products of rhizobial nodulation (nod) genes, vary in core length as well as in the number and type of substitutions. in rhizobium sp. ngr234, the n-acylated pentamers of n-acetyl-d-glucosamine carry an o-methylfucose group on the reducing terminus that is substituted, on a mutually exclusive b ...	1998	9650293
identification and sequencing of a cytochrome p450 gene cluster from bradyrhizobium japonicum.	sequencing of a region from bradyrhizobium japonicum previously shown to encode for cytochromes p450 revealed a cluster of three complete p450 genes (cyp112, cyp114, and cyp117) plus a partial p450 gene fragment (cyp115p). present also are five additional open reading frames. the close positioning of the genes suggests that they comprise an operon. although the biochemical function of the gene products is uncertain, the similarities to other genes suggests an operon involved in terpenoid synthes ...	1998	9655913
expression of a soybean nodule-enhanced phosphoenolpyruvate carboxylase gene that shows striking similarity to another gene for a house-keeping isoform.	three different cdnas for phosphoenolpyruvate carboxylase (pepc) were isolated from soybean root nodules. the full-length cdna of the most abundant isoform (gmpepc7) was very similar to another one (gmpepc15), the nucleotide sequence of which is identical to that of a reported clone (gmppc1) (vazquez-tello, a., whittier, r.f., kawasaki, t., sugimoto, t., kawamura, y. and shibata, d. (1993) plant physiol. 103, 1025-1026). in the coding region, the newly isolated gmpepc7 and the previously reporte ...	1998	9680982
expression of the fixr-nifa operon in bradyrhizobium japonicum depends on a new response regulator, regr.	many nitrogen fixation-associated genes in the soybean symbiont bradyrhizobium japonicum are regulated by the transcriptional activator nifa, whose activity is inhibited by aerobiosis. nifa is encoded in the fixr-nifa operon, which is expressed at a low level under aerobic conditions and induced approximately fivefold under low-oxygen tension. this induction depends on a -24/-12-type promoter (fixrp1) that is recognized by the sigma54 rna polymerase and activated by nifa. low-level aerobic expre ...	1998	9683482
biodiversity of rhizobia isolated from a wide range of forest legumes in brazil.	tropical forests have a high diversity of plant species; are they associated with a correspondingly rich microbial flora? we addressed this question by examining the symbiotic rhizobium bacteria that nodulate a diverse pool of forest legume species in brazil. the 44 strains studied had been isolated from 29 legume tree species representing 13 tribes including all three subfamilies of the leguminosae, and were chosen to represent major groups from a larger sample that had previously been characte ...	1998	9691490
the bacterial irr protein is required for coordination of heme biosynthesis with iron availability.	heme is a ubiquitous macromolecule that serves as the active group of proteins involved in many cellular processes. the multienzyme pathway for heme formation culminates with the insertion of iron into a protoporphyrin ring. the cytotoxicity of porphyrins suggests the need for coordination of its biosynthesis with iron availability. we isolated a mutant strain of the bacterium bradyrhizobium japonicum that, under iron limitation, accumulated protoporphyrin and showed aberrantly high expression o ...	1998	9705301
lotus corniculatus nodulation specificity is changed by the presence of a soybean lectin gene	plant lectins have been implicated as playing an important role in mediating recognition and specificity in the rhizobium-legume nitrogen-fixing symbiosis. to test this hypothesis, we introduced the soybean lectin gene le1 either behind its own promoter or behind the cauliflower mosaic virus 35s promoter into lotus corniculatus, which is nodulated by r. loti. we found that nodulelike outgrowths developed on transgenic l. corniculatus plant roots in response to bradyrhizobium japonicum, which nod ...	1998	9707526
isolation of sinorhizobium meliloti tn5 mutants with altered cytochrome terminal oxidase expression and improved symbiotic performance.	the relationship between whole-cell redox potential, cytochrome composition in free-living culture and symbiotic activity of sinorhizobium meliloti was studied. three tn5-induced mutants with increased cellular redox potential were generated. stationary cultures of mutants tb9 and tb16 in contrast to the parental strain produced the b-type terminal oxidase that may be similar to the symbiotically essential cytochrome oxidase cbb3 of bradyrhizobium japonicum. increase in the symbiotic effectivene ...	1998	9711854
cloning of conserved genes from zymomonas mobilis and bradyrhizobium japonicum that function in the biosynthesis of hopanoid lipids.	the squalene-hopene cyclase (shc) is the only enzyme involved in the biosynthesis of hopanoid lipids that has been characterized on the genetic level. to investigate if additional genes involved in hopanoid biosynthesis are clustered with the shc gene, we cloned and analyzed the nucleotide sequences located immediately upstream of the shc genes from zymomonas mobilis and bradyrhizobium japonicum. in z. mobilis, five open reading frames (orfs, designated as hpna-e) were detected in a close arrang ...	1998	9714766
tricarboxylic acid cycle and anaplerotic enzymes in rhizobia.	rhizobia are a diverse group of gram-negative bacteria comprised of the genera rhizobium, bradyrhizobium, mesorhizobium, sinorhizobium and azorhizobium. a unifying characteristic of the rhizobia is their capacity to reduce (fix) atmospheric nitrogen in symbiotic association with a compatible plant host. symbiotic nitrogen fixation requires a substantial input of energy from the rhizobial symbiont. this review focuses on recent studies of rhizobial carbon metabolism which have demonstrated the im ...	1998	9729766
exopolysaccharide (eps) synthesis in bradyrhizobium japonicum: sequence, operon structure and mutational analysis of an exo gene cluster.	the nucleotide sequence of a 8330-bp dna fragment from bradyrhizobium japonicum 110spc4 was determined. sequence analysis revealed that six orfs were present and the deduced amino acid sequences were homologous to enzymes involved in exopolysaccharide (eps) biosynthesis. the genes appear to be organized into at least four different operons. one gene was found to be homologous to exob, which encodes a udp-galactose 4'-epimerase. other orfs were homologous to udp-hexose transferases and one orf sh ...	1998	9747707
bradyrhizobium japonicum fixk2, a crucial distributor in the fixlj-dependent regulatory cascade for control of genes inducible by low oxygen levels.	bradyrhizobium japonicum possesses a second fixk-like gene, fixk2, in addition to the previously identified fixk1 gene. the expression of both genes depends in a hierarchical fashion on the low-oxygen-responsive two-component regulatory system fixlj, whereby fixj first activates fixk2, whose product then activates fixk1. while the target genes for control by fixk1 are unknown, there is evidence for activation of the fixnoqp, fixghis, and rpon1 genes and some heme biosynthesis and nitrate respira ...	1998	9748464
molecular diversity of rhizobia occurring on native shrubby legumes in southeastern australia	the structure of rhizobial communities nodulating native shrubby legumes in open eucalypt forest of southeastern australia was investigated by a molecular approach. twenty-one genomic species were characterized by small-subunit ribosomal dna pcr-restriction fragment length polymorphism and phylogenetic analyses, among 745 rhizobial strains isolated from nodules sampled on 32 different legume host species at 12 sites. among these rhizobial genomic species, 16 belonged to the bradyrhizobium subgro ...	1998	9758831
purification and characterization of an nad-malic enzyme from bradyrhizobium japonicum a1017.	an nad-malic enzyme was purified to homogeneity from bradyrhizobium japonicum a1017, and its molecular characteristics were surveyed. the enzyme exhibited native and subunit molecular masses of 388 and 85 kda, respectively, suggesting that it exists as a homotetramer, and was activated by metabolic intermediates in glycolysis. the role of the enzyme in bacteroids' carbon metabolism is discussed.	1998	9758846
a stomatin-like protein encoded by the slp gene of rhizobium etli is required for nodulation competitiveness on the common bean.	rhizobium etli strain tal182 is a competitive strain for effective nodulation of beans. from this strain, a novel gene was isolated, slp, which is 669 bp in size and required for nodulation competition on the common bean. the slp knockout mutant of tal182 is defective in nodulation competition, shows reduced growth in the presence of 200 mm nacl, kcl or licl and is complemented by the cloned slp gene. the deduced amino acid sequence of slp shows 66-72% similarity to stomatin proteins of homo sap ...	1998	9782511
overproduction of the bradyrhizobium japonicum c-type cytochrome subunits of the cbb3 oxidase in escherichia coli.	we report on a system to improve expression of mature c-type cytochromes in escherichia coli. it is based on the use of plasmid pec86 that expresses the e. coli cytochrome c maturation genes ccmabcdefgh constitutively, whereby the production of both endogenous and foreign c-type cytochromes was increased substantially. the periplasmic soluble domains of the c-type cytochrome subunits fixo and fixp of the bradyrhizobium japonicum cbb3 oxidase could be expressed in e. coli only when pec86 was prov ...	1998	9790980
biochemical alterations in bradyrhizobium sp usda 3187 induced by the fungicide mancozeb.	we have previously shown that fungicide mancozeb causes a 50% decrease in bradyhizobium sp usda 3187 growth rate and affects the bacteria-root symbiotic interaction. in order to elucidate the fungicide toxicity mechanism we determined the effects of mancozeb on cell chemical composition, glutathione (gsh) content (molecule involved in the detoxification process), glutathione s-transferase (gst) activity and on polyamine, exopolysaccharides, capsular polysaccharides and lipopolysaccharides. manco ...	1998	9801766
allorhizobium undicola gen. nov., sp. nov., nitrogen-fixing bacteria that efficiently nodulate neptunia natans in senegal.	a group of nodule isolates from neptunia natans, an indigenous stemnodulated tropical legume found in waterlogged areas of senegal, was studied. polyphasic taxonomy was performed, including sds-page of total proteins, auxanography using api galleries, host-plant specificity, pcr-rflp of the internal transcribed spacer region between the 16s and the 23s rrna coding genes, 16s rrna gene sequencing and dna-dna hybridization. it was demonstrated that this group is phenotypically and phylogenetically ...	1998	9828428
detecting linkage disequilibrium in bacterial populations.	the distribution of the number of pairwise differences calculated from comparisons between n haploid genomes has frequently been used as a starting point for testing the hypothesis of linkage equilibrium. for this purpose the variance of the pairwise differences, vd, is used as a test statistic to evaluate the null hypothesis that all loci are in linkage equilibrium. the problem is to determine the critical value of the distribution of vd. this critical value can be estimated either by monte car ...	1998	9832514
electrophoretic behavior and size distribution of the acidic polysaccharides produced by the bacteria bradyrhizobium (chamaecytisus) strain bga-1 and bradyrhizobium japonicum usda 110.	the electrophoretic behavior in polyacrylamide gels of the acidic polysaccharides produced by the soil bacteria bradyrhizobium (chamaecytisus) strain bga1 and bradyrhizobiumjaponicum usda1 10 has been studied. both polysaccharides were polydisperse, producing a ladder-like pattern after fixation with alcian blue and silver staining of the gel. the polysaccharide molecules were separated according to their size, and they behaved as a collection of flexible random coils of different size and simil ...	1998	9848669
structure of a biological oxygen sensor: a new mechanism for heme-driven signal transduction.	the fixl proteins are biological oxygen sensors that restrict the expression of specific genes to hypoxic conditions. fixl's oxygen-detecting domain is a heme binding region that controls the activity of an attached histidine kinase. the fixl switch is regulated by binding of oxygen and other strong-field ligands. in the absence of bound ligand, the heme domain permits kinase activity. in the presence of bound ligand, this domain turns off kinase activity. comparison of the structures of two for ...	1998	9860942
identification of the bradyrhizobium japonicum degp gene as part of an operon containing small heat-shock protein genes.	a degp (htra)-like gene of bradyrhizobium japonicum was identified immediately downstream of two genes (hspb and hspc) coding for small heat-shock proteins. all three genes are oriented in the same direction and are separated by only 85 and 72 bp, and a heat-inducible transcript covering hspb, hspc, and degp was detected by rt-pcr. these results show that the genes are organized in an operon. two mutants, a degp insertion mutant and a deltahspbcdegp mutant, were constructed by marker replacement ...	1998	9446679
in vivo genomic footprinting analysis reveals that the complex bradyrhizobium japonicum fixrnifa promoter region is differently occupied by two distinct rna polymerase holoenzymes.	the bradyrhizobium japonicum fixrnifa operon is transcribed from two promoters: fixrp1, a -24/-12 promoter recognized by the sigma54-holoenzyme form of the rna polymerase, and fixrp2, a -35/-10 promoter that is transcribed by a second, unidentified, form of rna polymerase holoenzyme. the fixrp1 promoter is autoregulated during microaerobiosis by nifa, whereas fixrp2 is also activated, but by a different regulatory protein. the main transcription start sites for these promoters are just two nucle ...	1998	9448277
localization of nod, nif, and acidic exopolysaccharide determinants on a large plasmid in slow-growing cowpea rhizobium sp. s2.	slow-growing cowpea rhizobium sp. s2, a pigeon pea isolate, showed excessive synthesis of exopolysaccharide (eps) and nod factor(s) only when grown in the presence of corresponding host root exudate (re) or naringenin (a flavonoid present in re of pigeon pea). muc- strain, a plasmid-cured derivative of the parent strain, showed negligible eps production and failed to synthesize the nod factor(s) under similar growth conditions. the nod factor(s) was extracted and partially purified from the tota ...	1998	9405744
genes involved in the formation and assembly of rhizobial cytochromes and their role in symbiotic nitrogen fixation.	rhizobia fix nitrogen in a symbiotic association with leguminous plants and this occurs in nodules. a low-oxygen environment is needed for nitrogen fixation, which paradoxically has a requirement for rapid respiration to produce atp. these conflicting demands are met by control of oxygen flux and production of leghaemoglobin (an oxygen carrier) by the plant, coupled with the expression of a high-affinity oxidase by the nodule bacteria (bacteroids). many of the bacterial genes encoding cytochrome ...	1998	9889979
a second gene for type i signal peptidase in bradyrhizobium japonicum, sipf, is located near genes involved in rna processing and cell division.	the tnphoa-induced bradyrhizobium japonicum mutant 184 shows slow growth and aberrant colonization of soybean nodules. using a dna fragment adjacent to the transposon insertion site as a probe, a 3.4-kb bglii fragment of b. japonicum 110spc4 dna was identified and cloned. sequence analysis indicated that two truncated orfs and three complete orfs were encoded on this fragment. a database search revealed homologies to several other prokaryotic proteins: pdxj (an enzyme involved in vitamin b6 bios ...	1998	9870699
functional bradyrhizobium japonicum nifa expression under a hybrid nptii-nifh promoter in e. coli and acetobacter diazotrophicus srt4.	a hybrid promoter consisting of the in tandem fusion of the tn5 nptii and the klebsiella pneumoniae nifh promoters was constructed to study the functionality of the nif genes transcriptional activator nifa from bradyrhizobium japonicum in two different host bacteria. beta-galactosidase experiments in e. coli revealed that the hybrid nptii-nifh promoter can behave as a constitutive or a nifa-inducible promoter depending on the aeration conditions. expression of the b. japonicum nifa from the hybr ...	1998	10932742
diversity of bradyrhizobia from 27 tropical leguminosae species native of senegal	we isolated 71 slow-growing bacterial strains from nodules of 27 native leguminous plants species in senegal (west-africa) belonging to the genera abrus, alysicarpus, bryaspis, chamaecrista, cassia, crotalaria, desmodium, eriosema, indigofera, moghania, rhynchosia, sesbania, tephrosia, and zornia playing an ecological role and having agronomic potential in arid regions. the isolates were characterised by restriction fragment length polymorphism (rflp) analysis of pcr-amplified 16s rdna and compa ...	1999	10794153
symbiotic deficiencies associated with a coxwxyz mutant of bradyrhizobium japonicum	the terminal oxidase complexes encoded by coxmnop and coxwxyz were studied by analysis of mutations in each of the two oxidases. carbon monoxide difference spectra obtained from membranes of coxmnop mutant bacteroids were like those obtained for the wild type, whereas bacteroid membranes of a coxwxyz mutant were deficient in co-reactive cytochrome b. experiments involving cyanide inhibition of oxidase activity were consistent with the conclusion that the coxx mutant is deficient in a membrane-as ...	1999	9872805
closely related form i ribulose bisphosphate carboxylase/oxygenase molecules that possess different co2/o2 substrate specificities.	the deduced primary sequence (cbbl and cbbs) of form i ribulose 1, 5-bisphosphate carboxylase/oxygenase (rubisco) from bradyrhizobium japonicum places this enzyme within the type ic subgroup of red-like rubisco enzymes. in addition, b. japonicum appears to organize most of the structural genes of the calvin-benson-bassham (cbb) pathway in at least one major operon. functional expression and characterization of the b. japonicum and xanthobacter flavus enzymes from this group revealed that these m ...	1999	9882445
molecular evidence for shifts in polysaccharide composition associated with adaptation of soybean bradyrhizobium strains to the brazilian cerrado soils.	pyrolysis mass spectrometry (pyms) and dna fingerprinting (rapd and rsalpha hybridization) were used to characterize soybean inoculant strains and root nodule isolates of bradyrhizobia from the brazilian cerrado soils. most isolates were shown to be derived from the inoculant strains on the basis of genotype comparisons by dna fingerprinting. phenotypic analysis (using pyms) of the strains and separately of the polysaccharides derived from them showed that the nodule isolates differed from the p ...	1999	11207759
purification and functional reconstitution of soybean nodulin 26. an aquaporin with water and glycerol transport properties.	infection of soybean roots by nitrogen-fixing bradyrhizobium japonicum leads to expression of plant nodule-specific genes known as nodulins. nodulin 26, a member of the major intrinsic protein/aquaporin (aqp) channel family, is a major component of the soybean symbiosome membrane (sm) that encloses the rhizobium bacteroid. to investigate the water and solute transport characteristics of nodulin 26, we purified the protein from sms and reconstituted it into carboxyfluorescein-loaded liposomes for ...	1999	9890916
characterization of the escherichia coli ccmh protein reveals new insights into the redox pathway required for cytochrome c maturation.	the ccmh protein of escherichia coli is encoded by the last gene of the ccm gene cluster required for cytochrome c maturation. a mutant in which the entire ccmh gene was deleted failed to synthesize both indigenous and foreign c-type cytochromes. however, deletion of the c-terminal hydrophilic domain homologous to cych of other gram-negative bacteria affected neither the biogenesis of indigenous c-type cytochromes nor that of the bradyrhizobium japonicum cytochrome c550. this confirmed that only ...	1999	9914305
analysis of nifh gene pool complexity in soil and litter at a douglas fir forest site in the oregon cascade mountain range.	nitrogen-fixing microbial populations in a douglas fir forest on the western slope of the oregon cascade mountain range were analyzed. the complexity of the nifh gene pool (nifh is the marker gene which encodes nitrogenase reductase) was assessed by performing nested pcr with bulk dna extracted from plant litter and soil. the restriction fragment length polymorphisms (rflps) of pcr products obtained from litter were reproducibly different than the rflps of pcr products obtained from the underlyi ...	1999	9925556
new assay for rhizobitoxine based on inhibition of 1-aminocyclopropane-1-carboxylate synthase.	rhizobitoxine is synthesized by the legume symbiont bradyrhizobium elkanii and the plant pathogen burkholderia andropogonis. rhizobitoxine competitively inhibited 1-aminocyclopropane-1-carboxylate (acc) synthase ble-acs2 from the tomato, a key enzyme in the pathway of ethylene biosynthesis. based on this inhibition of acc synthase, we have developed a new assay for rhizobitoxine.	1999	9925628
the bradyrhizobium japonicum nola gene encodes three functionally distinct proteins.	examination of nola revealed that nola can be uniquely translated from three atg start codons. translation from the first atg (atg1) predicts a protein (nola1) having an n-terminal, helix-turn-helix dna-binding motif similar to the dna-binding domains of the merr-type regulatory proteins. translation from atg2 and atg3 would give the n-terminally truncated proteins nola2 and nola3, respectively, lacking the dna-binding domain. consistent with this, immunoblot analyses of bradyrhizobium japonicum ...	1999	10049387
a novel 53-kda nodulin of the symbiosome membrane of soybean nodules, controlled by bradyrhizobium japonicum.	a nodule-specific 53-kda protein (gmnod53b) of the symbiosome membrane from soybean was isolated and its lysc digestion products were microsequenced. cdna clones of this novel nodulin, obtained from cdna library screening with an rt-pcr (reverse-transcriptase polymerase chain reaction)-generated hybridization probe exhibited no homology to proteins identified so far. the expression of gmnod53b coincides with the onset of nitrogen fixation. therefore, it is a late nodulin. among other changes, th ...	1999	10065559
regulation of soybean nodulation independent of ethylene signaling	leguminous plants regulate the number of bradyrhizobium- or rhizobium-infected sites that develop into nitrogen-fixing root nodules. ethylene has been implicated in the regulation of nodule formation in some species, but this role has remained in question for soybean (glycine max). the present study used soybean mutants with decreased responsiveness to ethylene, soybean mutants with defective regulation of nodule number, and ag+ inhibition of ethylene perception to examine the role of ethylene i ...	1999	10069833
further studies of the role of cyclic beta-glucans in symbiosis. an ndvc mutant of bradyrhizobium japonicum synthesizes cyclodecakis-(1-->3)-beta-glucosyl.	the cyclic beta-(1-->3),beta-(1-->6)-d-glucan synthesis locus of bradyrhizobium japonicum is composed of at least two genes, ndvb and ndvc. mutation in either gene affects glucan synthesis, as well as the ability of the bacterium to establish a successful symbiotic interaction with the legume host soybean (glycine max). b. japonicum strain ab-14 (ndvb::tn5) does not synthesize beta-glucans, and strain ab-1 (ndvc::tn5) synthesizes a cyclic beta-glucan lacking beta-(1-->6)-glycosidic bonds. we det ...	1999	10069844
cuma, a gene encoding a multicopper oxidase, is involved in mn2+ oxidation in pseudomonas putida gb-1.	pseudomonas putida gb-1-002 catalyzes the oxidation of mn2+. nucleotide sequence analysis of the transposon insertion site of a nonoxidizing mutant revealed a gene (designated cuma) encoding a protein homologous to multicopper oxidases. addition of cu2+ increased the mn2+-oxidizing activity of the p. putida wild type by a factor of approximately 5. the growth rates of the wild type and the mutant were not affected by added cu2+. a second open reading frame (designated cumb) is located downstream ...	1999	10103278
acid tolerance in root nodule bacteria.	biological nitrogen fixation, especially via the legume rhizobium symbiosis, is important for world agriculture. the productivity of legume crops and pastures is significantly affected by soil acidity; in some cases it is the prokaryotic partner that is ph sensitive. growth of rhizobium is adversely affected by low ph, especially in the 'acid stress zone'. rhizobia exhibit an adaptive acid tolerance response (atr) that is influenced by calcium concentration. using tn5-mutagenesis, gusa fusions a ...	1999	10207916
enhanced nitrogen fixation in a rhizobium etli ntrc mutant that overproduces the bradyrhizobium japonicum symbiotic terminal oxidase cbb3	the ntrc gene codes for a transcriptional activator protein that modulates gene expression in response to nitrogen. the cytochrome production pattern of a rhizobium etli ntrc mutant (cfn2012) was studied. co difference spectral analysis of membranes showed that cfn2012 produced a terminal oxidase similar to the symbiotic terminal oxidase of bacteroids in free-living cells under aerobic conditions, with a characteristic trough at 553 nm. cfn2012 produced two c-type cytochromes with molecular mass ...	1999	10223993
occurrence of choline and glycine betaine uptake and metabolism in the family rhizobiaceae and their roles in osmoprotection	the role of glycine betaine and choline in osmoprotection of various rhizobium, sinorhizobium, mesorhizobium, agrobacterium, and bradyrhizobium reference strains which display a large variation in salt tolerance was investigated. when externally provided, both compounds enhanced the growth of rhizobium tropici, sinorhizobium meliloti, sinorhizobium fredii, rhizobium galegae, agrobacterium tumefaciens, mesorhizobium loti, and mesorhizobium huakuii, demonstrating their utilization as osmoprotectan ...	1999	10224003
heme-based sensors in biological systems.	the past several years have been witness to a staggering rate of advancement in the understanding of how organisms respond to changes in the availability of diatomic molecules that are toxic and/or crucial to survival. heme-based sensors presently constitute the majority of the proteins known to sense no, o2 and co and to initiate the chemistry required to adapt to changes in their availabilities. knowledge of the three characterized members of this class, soluble guanylate cyclase, fixl and coo ...	1999	10226051
susceptibility to hydrogen peroxide and catalase activity of root nodule bacteria.	the root nodule bacteria (free-living cells) tested had higher susceptibility to hydrogen peroxide (h2o2) than the other genera of aerobic or facultative anaerobic bacteria tested. the catalase activities tended to have a positive correlation with h2o2 resistance among all bacteria tested. addition of a catalase inhibitor such as 3-amino-1, 2, 4-triazole increased the susceptibility to h2o2. these results suggest that the lower catalase activity brings about the higher susceptibility of root nod ...	1999	10227131
photosynthetic bradyrhizobia from aeschynomene spp. are specific to stem-nodulated species and form a separate 16s ribosomal dna restriction fragment length polymorphism group.	we obtained nine bacterial isolates from root or collar nodules of the non-stem-nodulated aeschynomene species a. elaphroxylon, a. uniflora, or a. schimperi and 69 root or stem nodule isolates from the stem-nodulated aeschynomene species a. afraspera, a. ciliata, a. indica, a. nilotica, a. sensitiva, and a. tambacoundensis from various places in senegal. these isolates, together with 45 previous isolates from various aeschynomene species, were studied for host-specific nodulation within the genu ...	1999	10388707
phosphorylation, dephosphorylation and dna-binding of the bradyrhizobium japonicum regsr two-component regulatory proteins.	under low oxygen conditions, induction of many genes required for nitrogen fixation in bradyrhizobium japonicum depends on the redox-responsive transcriptional activator nifa which is encoded in the fixr-nifa operon. basal expression of this operon depends on the response regulator regr and a dna element located around position -68 in the fixr-nifa promoter region. to investigate the functional properties of regr and the interaction with its putative cognate kinase, regs, we overproduced and aff ...	1999	10406954
succinate dehydrogenase (sdh) from bradyrhizobium japonicum is closely related to mitochondrial sdh.	the sdhcdab operon, encoding succinate dehydrogenase, was cloned from the soybean symbiont bradyrhizobium japonicum. sdh from b. japonicum is phylogenetically related to sdh from mitochondria. this is the first example of a mitochondrion-like sdh functionally expressed in escherichia coli.	1999	10419971
[effect of pesticides on bacillus thuringiensis strains under controlled conditions].	little is known about native populations of bacillus thuringiensis (bt) isolated from soils of argentina. we undertook this study to determine the resistance to different pesticides of two commercial and fourteen native strains of bt under in vitro conditions. an agar plate bioassay test conducted with ten pesticides and sixteen strains of bt showed that basagran, scepter, fungoxan and decis were not toxic for the bioinsecticide bacteria at recommended application rates (rar). in contrast, low c ...	1999	10425660
is1631 occurrence in bradyrhizobium japonicum highly reiterated sequence-possessing strains with high copy numbers of repeated sequences rsalpha and rsbeta.	from bradyrhizobium japonicum highly reiterated sequence-possessing (hrs) strains indigenous to niigata and tokachi in japan with high copy numbers of the repeated sequences rsalpha and rsbeta (k. minamisawa, t. isawa, y. nakatsuka, and n. ichikawa, appl. environ. microbiol. 64:1845-1851, 1998), several insertion sequence (is)-like elements were isolated by using the formation of dna duplexes by denaturation and renaturation of total dna, followed by treatment with s1 nuclease. most of these seq ...	1999	10427040
sequence analysis, characterization and co-specific transcription of the cox gene cluster on the megaplasmid phcg3 of oligotropha carboxidovorans.	sequence, transcriptional, mutational and physiological analyses indicate that the carbon monoxide (co) dehydrogenase of oligotropha carboxidovorans is an integral and unique part of an elaborate co oxidizing system. it is encoded by the 14.5kb gene cluster coxbcmsldefghik residing on the 128kb megaplasmid phcg3. the co dehydrogenase structural genes coxmsl are flanked by nine accessory genes arranged as the cox gene cluster. the cox genes are specifically and coordinately transcribed under chem ...	1999	10433972
iron coordination structures of oxygen sensor fixl characterized by fe k-edge extended x-ray absorption fine structure and resonance raman spectroscopy.	fixl is a heme-based o(2) sensor protein involved in a two-component system of a symbiotic bacterium. in the present study, the iron coordination structure in the heme domain of rhizobium meliloti fixlt (rmfixlt, a soluble truncated fixl) was examined using fe k-edge extended x-ray absorption fine structure (exafs) and resonance raman spectroscopic techniques. in the exafs analyses, the interatomic distances and angles of the fe-ligand bond and the iron displacement from the heme plane were obta ...	1999	10438488
identification and characterization of hupt, a gene involved in negative regulation of hydrogen oxidation in bradyrhizobium japonicum.	the bradyrhizobium japonicum hupt gene was sequenced, and its gene product was found to be homologous to ntrb-like histidine kinases. a hupt mutant expresses higher levels of hydrogenase activity than the wild-type strain under hydrogenase-inducing conditions (i.e., microaerobiosis plus hydrogen, or symbiosis), whereas in noninduced hupt cells, hupsl expression is derepressed but does not lead to hydrogenase activity. we conclude that hupt is involved in the repression of hupsl synthesis at the ...	1999	10438783
proteome analysis of heat shock protein expression in bradyrhizobium japonicum.	a set of 19 heat shock proteins (hsp) was observed - by subtractive two-dimensional gel electrophoresis - to be induced when bradyrhizobium japonicum, the nitrogen-fixing root-nodule symbiont of soybean, was temperature up-shifted from 28 degrees c to 43 degrees c. up-regulated protein spots were excised from multiple two-dimensional gels. the proteins were concentrated using a funnel-gel device before being blotted onto poly(vinylidene difluoride) membranes for digestion with trypsin before ms ...	1999	10447671
structural characterisation of lipo-chitin oligosaccharides isolated from bradyrhizobium aspalati, microsymbionts of commercially important south african legumes.	the shoots of the south african legume aspalathus linearis spp. linearis (a. linearis) are used in the manufacture of an increasingly popular beverage that has acclaimed beneficial effects on health; this important export product is known as rooibos (or redbush) tea. three strains of bradyrhizobium aspalati, which are the nitrogen-fixing symbionts of aspalathus carnosa, a. hispida and a. linearis, were tested for the production of lipo-chitin oligosaccharide signal molecules using thin-layer chr ...	1999	10466212
identification of a functional fur gene in bradyrhizobium japonicum.	the recent identification of the iron response regulator (irr) in bradyrhizobium japonicum raised the question of whether the global regulator fur is present in that organism. a fur gene homolog was isolated by the functional complementation of an escherichia coli fur mutant. the b. japonicum fur bound to a fur box dna element in vitro, and a fur mutant grown in iron-replete medium was derepressed for iron uptake activity. thus, b. japonicum expresses at least two regulators of iron metabolism.	1999	10482529
aberrant nodulation response of vigna umbellata to a bradyrhizobium japonicum nodz mutant and nodulation signals.	the (brady)rhizobium nodulation gene products synthesize lipo-chitin oligosaccharide (lco) signal molecules that induce nodule primordia on legume roots. in spot inoculation assays with roots of vigna umbellata, bradyrhizobium elkanii lco and chemically synthesized lco induced aberrant nodule structures, similar to the activity of these lcos on glycine soja (soybean). lcos containing a pentameric chitin backbone and a reducing-end 2-o-methyl fucosyl moiety were active on v. umbellata. in contras ...	1999	10494629
carbohydrate analysis of bradyrhizobial (nc92) lipopolysaccharides by high performance-anion exchange chromatography with pulsed amperometric detection.	composition analysis of monosaccharides of sepharose 4b purified nc 92 lps and the polysaccharides fractions from sephadex g-50 chromatography was performed by high performance anion exchange chromatography using pulsed amperometric detection. rhamnose, mannose, galactose and glucose are present in a substantial amount in the purified lps (pk i). high molecular weight purified polysaccharides (ps i) obtained after sephadex gel filtration of the purified lps (pk i) acid hydrolysate showed an incr ...	1999	10513899
characterization of soybean bradyrhizobium strains adapted to the brazilian savannas.	brazilian soils are originally free from soybean bradyrhizobia and the first inoculants were brought to the country in this century, but a search for adapted strains started immediately and still continues. a strain selection program was established at embrapa based on the reisolation of strains after a long period of adaptation to the soils followed by a search for variant genotypes with higher n(2) fixation capacity and competitiveness. a second approach of this program consists of searching f ...	1999	10525182
phylogenetic analyses of bradyrhizobium strains nodulating soybean (glycine max) in thailand with reference to the usda strains of bradyrhizobium.	to elucidate the phylogenetic relationships between thai soybean bradyrhizobia and usda strains of bradyrhizobium, restriction fragment length polymorphism (rflp) analysis using the nifdk gene probe and sequencing of the partial 16s rrna gene were performed. in our previous work, thai isolates of bradyrhizobium sp. (glycine max) were separated clearly from bradyrhizobium japonicum and bradyrhizobium elkanii based on the rflp analysis using the noddyabc gene probe. rflp analysis using the nifdk g ...	1999	10528395
biosynthesis of trehalose from maltooligosaccharides in rhizobia.	previously, the enzymes for trehalose synthesis that are present in escherichia coli were demonstrated in bradyrhizobium japonicum and b. elkanii. an alternative mechanism recently reported for the synthesis of trehalose from maltooligosaccharides was considered based on the fact that high concentrations of sugars in liquid culture stimulated the accumulation of trehalose. an assay for the synthesis of trehalose from maltooligosaccharides using crude, gel-filtered protein preparations was develo ...	1999	10528404
relationships of bradyrhizobia from the legumes apios americana and desmodium glutinosum.	multilocus enzyme electrophoresis, partial 23s rrna sequences, and nearly full-length 16s rrna sequences all indicated high genetic similarity among root-nodule bacteria associated with apios americana, desmodium glutinosum, and amphicarpaea bracteata, three common herbaceous legumes whose native geographic ranges in eastern north america overlap extensively. a total of 19 distinct multilocus genotypes (electrophoretic types [ets]) were found among the 35 a. americana and 33 d. glutinosum isolat ...	1999	10543803
glyphosate effects on phenolic metabolism of nodulated soybean (glycine max l. merr.).	glyphosate is a herbicide that blocks the shikimic acid pathway. three bradyrhizobium japonicum strains with different sensitivities to glyphosate were used to test the effect of this herbicide on the phenolic metabolism of nodulated soybeans and on the bacteroid nitrogenase activity. glyphosate caused an inhibition in the bacteroid nitrogenase activity that was related with the sensitivity of the nodule-forming strains. both leaves and nodules accumulated huge amounts of shikimate and phenolic ...	1999	10552587
phylogeny and diversity of bradyrhizobium strains isolated from the root nodules of peanut (arachis hypogaea) in sichuan, china.	twenty-two rhizobial strains isolated from the root nodules of two chinese peanut cultivars (arachis hypogaea l. tianfu no. 3 and a local cultivar) growing at four different sites in the sichuan province, southwest china, were characterized by growth rate, rep-pcr, pcr-rflp of 16s rdna, partial sequencing of ribosomal genes, and fatty acid-methyl ester analysis (fame), and compared with strains representing bradyrhizobium japanicum, b. elkanii and other unclassified bradyrhizobium sp. all peanut ...	1999	10553290
diversity and relationships of bradyrhizobia from amphicarpaea bracteata based on partial nod and ribosomal sequences.	partial sequences of three nod genes (nodc, nodd1, and noda 5' flanking region) and of 16s and 23s rdna were obtained from isolates of bradyrhizobium sp. associated with the native north american legume amphicarpaea bracteata. isolates from amphicarpaea had identical sequences in the three nod gene regions, but differed from all other bradyrhizobium taxa at > 10% of nucleotide sites. parsimony analysis of all nod gene segments indicated a phylogenetic relationship of these bacteria to b. elkanii ...	1999	10553291
characterization of the bradyrhizobium japonicum ftsh gene and its product.	the bradyrhizobium japonicum ftsh gene was cloned by using a set of widely applicable degenerated oligonucleotides. western blot experiments indicated that the ftsh protein was produced under standard growth conditions and that it was not heat inducible. attempts to delete the ftsh gene in b. japonicum failed, suggesting a pivotal cellular function of this gene. the expression of b. japonicum ftsh in an ftsh-negative escherichia coli strain significantly enhanced the fitness of this mutant and r ...	1999	10572147
influence of growth phases and desiccation on the degrees of unsaturation of fatty acids and the survival rates of rhizobia	the influence of growth phase on the evolution of cellular fatty acids (cfa) and survival of sinorhizobium and bradyrhizobium during desiccation and storage at different levels of relative humidity (r. h.) was studied. lactobacillic, cis vaccenic and palmitic acids were the major fatty acids of s. meliloti rcr 2011, b. elkanii usda 120 and b. japonicum 3.2, whatever the growth phase. an exchange of cis vaccenic with lactobacillic acid was observed during the course of growth. the degree of unsat ...	1999	10583690
classifying symbiotic proteins from bradyrhizobium japonicum into functional groups by proteome analysis of altered gene expression levels.	the advent of whole genome sequences has brought with it a vast number of new potential proteins whose function is unknown. we describe an approach to sorting proteins into functional groups by comparative two-dimensional (2-d) gel mapping of cells grown under different physiological conditions. computerized image analysis selects the proteins whose expression levels change significantly for subsequent identification by mass spectrometry. the protein groupings are further subdivided by directed ...	1999	10612277
effectiveness of ascorbate and ascorbate peroxidase in promoting nitrogen fixation in model systems.	ascorbate and ascorbate peroxidase are important antioxidants that are abundant in n2-fixing legume root nodules. antioxidants are especially critical in root nodules because leghemoglobin, which is present at high concentrations in nodules, is prone to autoxidation and production of activated oxygen species such as o2.- and h2o2. the merits of ascorbate and ascorbate peroxidase for maintaining conditions favorable for n2 fixation were examined in two model systems containing oxygen-binding prot ...	1999	10647213
multiple small heat shock proteins in rhizobia.	seven genes coding for small heat shock proteins (shsps) in bradyrhizobium japonicum have been identified. they are organized in five operons that are coordinately regulated by rose, a negatively cis-acting dna element. the deduced shsps can be divided into two separate classes: class a, consisting of proteins that show similarity to escherichia coli ibpa and ibpb, and class b, whose members display significant similarity to other shsps from prokaryotes and eukaryotes. two-dimensional gel electr ...	1999	9864316
[study on polyphasic taxonomy of rhizobia isolated from lespedeza species].	the diversity of rhizobia isolated from lespedeza spp. was determined on the basis of numerical analysis of phenotypic characteristics, sodium dodecyl sulfate-polyacrylarmide gel electrophoresis (sds-page) of proteins, dna-dna homology and restriction fragment length polymorphism (rflp) analysis of 16s-ribosomal dna genes. according to numerical analysis of 125 phenotypic characteristics, strains were divided into two groups at a similarity level of 67%. group i included all the fast-growing str ...	1999	12555566
[genetic diversity among chinese peanut rhizobia by rep-pcr analysis].	repetitive sequences(repetitive extragenic palindromic[rep], and enterobacterial repetitive intergenic consensus [eric]) with the polymerase chain reaction(pcr) were used to fingerprint pure dna extracted from 79 bradyrhizobial strains. these strains included 59 peanut rhizobia [bradyrhizobium sp. (arachis)] isolated from root nodules of 24 peanut (arachis hypogaea l) cultivars from 23 sites in 11 provinces in china, 6 peanut rhizobial strains from other nations, and 14 reference strains of othe ...	1999	12555567
[phylogenetic analysis of two rhizobia new groups].	on the basis of numerical taxonomy, sds-page whole-cell protein analysis, 16s rdna pcr-rflp and dna-dna hybridization, the full length of 16srdna of two strains (xj96060, xj96408) were sequenced and compared with the 16s rdna sequences of other members of the alpha 2 subclass of the proteobacteria available from genbank. an unrooted tree was produced to determine the phylogenetic relationships of two groups. the results showed that all strains were clustered into 6 branches, they were sinorhizob ...	2000	12548870
[study on the improvement of plasmid stability in soybean rhizobia].	by using luxab as the report genes, 3.2 kb parcba/de gene fragment from ptr102 was inserted into plafr3 which contained a 3.7 kb enhancing fragment and deleted its cos site. recombinant plasmids phn155 and phn156 were obtained. contrasted plasmids phn157 and phn158 which contained cos site were also constructed. these four plasmids were transferred into sinorhizobium fredii hn01 by tri-parental mating, and plasmid phn155 and phn158 were introduced into bradyrhizobium japonicum ta11 by two-parent ...	2000	12548995
genetic snapshots of the rhizobium species ngr234 genome.	in nitrate-poor soils, many leguminous plants form nitrogen-fixing symbioses with members of the bacterial family rhizobiaceae. we selected rhizobium sp. ngr234 for its exceptionally broad host range, which includes more than i 12 genera of legumes. unlike the genome of bradyrhizobium japonicum, which is composed of a single 8.7 mb chromosome, that of ngr234 is partitioned into three replicons: a chromosome of about 3.5 mb, a megaplasmid of more than 2 mb (pngr234b) and pngr234a, a 536,165 bp pl ...	2000	11178268
characterization of an azospirillum brasilense tn5 mutant with enhanced n(2) fixation: the effect of orf280 on nifh expression.	disruption of an open reading frame (orf) of 840 bp (280 amino acids; orf280) in an azospirillum brasilense tn5 mutant resulted in a pleiotrophic phenotype. besides an enhanced n(2)-fixing capacity and altered expression pattern of a nifh-gusa fusion, growth on the charged polar amino acids glutamate and arginine was severely affected. orf280, similar to previously identified orfs present in bradyrhizobium japonicum (orf277), paracoccus denitrificans (orf278) and rhodobacter capsulatus (orf277), ...	2000	10650197