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storage of competent cells for agrobacterium transformation. 19883186459
role of the overdrive sequence in t-dna border cleavage in agrobacterium.the t-dna of the ti plasmid of agrobacterium is flanked by 25-base-pair imperfect direct repeats that are required in cis for transfer to the genome of the plant host. another sequence, designated overdrive, is located adjacent to the right-border repeats and functions in cis to enhance tumor formation. we have examined the effect of the overdrive sequence on the early steps in t-dna processing. we report here that overdrive greatly enhances cleavage by the site-specific endonuclease in agrobact ...19883186745
selective quantitative determination of tobramycin from fermentation broth.a derivative of rhizobium meliloti 41 was constructed (strain gy654) which was resistant to apramycin and kanamycin but remained sensitive to tobramycin. strain gy654 selectively measures tobramycin and 6"-o-carbamoyltobramycin in the presence of apramycin, kanamycin and 6"-o-carbamoylkanamycin b, therefore it is suitable for the rapid quantitation of 6"-o-carbamoyltobramycin and tobramycin in fermentation broths of streptomyces tenebrarius and solvents containing antibiotic mixtures.19883188834
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
glycine betaine allows enhanced induction of the agrobacterium tumefaciens vir genes by acetosyringone at low ph.we established growth conditions for efficient induction of the vir genes of agrobacterium tumefaciens by acetosyringone. optimal induction was attained at a ph below 5.2 in an ab minimal medium-derived high-osmotic-strength medium containing glycine betaine. this natural osmoprotectant accelerated the adaptation of the bacteria to these conditions. we established the kinetics of induction for virb, vird, vire, and virg by using lacz fusions, and we found that the virb mutant strain could not ad ...19883192516
vir-induced recombination in agrobacterium. physical characterization of precise and imprecise t-circle formation.induction of ti plasmid virulence (vir) gene expression during the early stages of plant cell transformation by agrobacterium tumefaciens initiates the generation of several t-dna-associated molecular events: (1) site-specific nicks at t-dna border sequences (border nicks); (2) free, unipolar, linear, single-stranded t-dna copies (t-strands); and (3) double-stranded, circular t-dna molecules (t-circles). the first two t-dna products have been detected in a. tumefaciens, while t-circles have only ...19883199438
effects of aldicarb on the biochemical composition of rhizobium meliloti. 19883207910
comparison of the chemotactic behaviour of rhizobium leguminosarum with and without the nodulation plasmid.the chemotactic behaviour of a strain of rhizobium leguminosarum biovar viciae was investigated. the flavanoids apigenin and naringenin, inducers of transcription of the nodulation (nod) genes, were both potent attractants but hesperitin, another flavone nod gene inducer, was not. the response of strains containing the sym plasmid prl1jl to apigenin and naringenin was significantly greater than the response of a strain cured of the plasmid, although both strains gave a positive response. additio ...19883210967
genetic diversity and relationships among isolates of rhizobium leguminosarum biovar phaseoli.fifty-one isolates of rhizobium leguminosarum biovar phaseoli from various geographic and ecological sources, largely in mexico, were characterized by the electrophoretic mobilities of 15 metabolic enzymes, and 46 distinctive multilocus genotypes (electrophoretic types [ets]) were distinguished on the basis of allele profiles at the enzyme loci. mean genetic diversity per enzyme locus among the 46 ets was 0.691, the highest value yet recorded for any species of bacterium. the occurrence of stron ...19883214160
characterization of the fixabc region of azorhizobium caulinodans ors571 and identification of a new nitrogen fixation gene.the fast growing strain, azorhizobium caulinodans ors571, isolated from stem nodules of the tropical legume sesbania rostrata, can grow in the free-living state at the expense of molecular nitrogen. five point mutants impaired in nitrogen fixation in the free-living state have been complemented by a plasmid containing the cloned fix-abc region of strain ors571. genetic analysis of the mutants showed that one was impaired in fixc, one in fixa and the three others in a new gene, located upstream f ...19883216855
respiration supported nitrogenase activity of isolated rhizobium meliloti bacteroids.bacteroids having a high level of respiration-supported nitrogenase activity were isolated from nitrogen-fixing alfalfa root nodules. gentle maceration under anaerobic conditions in the presence of sodium succinate and a fatty acid scavenging agent were employed in this method. a large proportion of isolated bacteroids retained a triple membrane structure as shown by transmission electron microscopy. dicarboxylic acids of the tca cycle (malate, fumarate, succinate), but not glutamate or aspartat ...19883220879
growth dependent enzymatic profiles of some gram-negative nonfermentative bacteria of clinical significance.a total of 734 strains of gram-negative nonfermentative bacteria (46 species and biochemically defined groups) of the genera pseudomonas, alcaligenes, bordetella, moraxella, acinetobacter, agrobacterium, and flavobacterium were investigated for their ability to hydrolyze 25 different chromogenic substrates. all tests were carried out in growth-stimulating media. results were read photometrically and evaluated automatically following a 24-h incubation. many of the 46 different species and biochem ...19883223128
studies on the toxicity of agrobacterium tumefaciens in mice. 19883235104
vird proteins of agrobacterium tumefaciens are required for the formation of a covalent dna--protein complex at the 5' terminus of t-strand molecules.the t-dna transfer process of agrobacterium tumefaciens is activated by the induction of the ti plasmid virulence (vir) loci by plant signal molecules such as acetosyringone. upon initiation of the t-dna transfer process, site-specific nicks occur at the 25-bp border sequences. this cleavage leads to the generation of a free, linear sst-dna molecule which is bound by sequence non-specific vire proteins. here we present evidence for the involvement of other acetosyringone-induced proteins in the ...19883243272
behaviour of expression of nif hdk and fix abcx promoters of rhizobium meliloti in r. leguminosarum. 19883243555
transgenic plants: horizontal transfer of nifhd dna to tobacco. 19883255666
a bacteriophage t4 expression cassette that functions efficiently in a wide range of gram-negative bacteria.we have constructed a derivative of the broad-host-range vector rsf1010. this plasmid, p alpha omega, contains an expression cassette derived from bacteriophage t4 gene 32, into which we have inserted the coding sequence for the xyle enzyme (c2,3o) of the tol plasmid pwwo. the composite plasmid, p alpha xyle omega, was transferred by conjugal mobilisation into a variety of gram-negative bacteria (agrobacter, paracoccus, erwinia, pseudomonas, rhizobium and xanthomonas). high levels of c2,3o activ ...19883259198
cloning and characterization of the 5-aminolevulinate synthase gene(s) from rhodobacter sphaeroides.the 5-aminolevulinate synthase gene (hema) from rhizobium meliloti was used to probe a genomic lambda bank derived from rhodobacter sphaeroides dna. two phage clones were found to bear homology to the rhizobium probe. southern hybridization analysis of the two lambda phage clones, which we designated lambda hem 10 and lambda hem 12, showed that the homology to the rhizobium hema gene was localized to a 3.1-kb sali fragment derived from lambda hem 10 and a 7.0-kb sali fragment derived from lambda ...19883266489
binding-protein-dependent glucose transport by agrobacterium radiobacter grown in glucose-limited continuous culture.agrobacterium radiobacter ncib 11883 was grown in glucose-limited continuous culture at low dilution rate. whole cells transported glucose using an energy-dependent mechanism which exhibited an accumulation ratio greater than 2000. three major periplasmic proteins were purified and their potential role as glucose-binding proteins (gbp) were investigated using equilibrium dialysis. two of these, gbp1 (mr 36,500) and gbp2 (mr 33,500), bound d-glucose with high affinity (kd 0.23 and 0.07 microm res ...19883269386
the relationship between glucose transport and the production of succinoglucan exopolysaccharide by agrobacterium radiobacter.agrobacterium radiobacter ncib 11883 was grown in ammonia-limited continuous culture at low dilution rate with glucose as the carbon source. under these conditions the organism produced an extracellular succinoglucan polysaccharide and transported glucose using the same periplasmic glucose-binding proteins (gbp1 and gbp2) as during glucose-limited growth. transition from glucose- to ammonia-limited growth was accompanied by a very rapid decrease in glucose uptake capacity, whereas the glucose-bi ...19883269387
ornithine cyclodeaminase from ti plasmid c58: dna sequence, enzyme properties and regulation of activity by arginine.nopaline, an abundant opine in plant cells transformed with nopaline-type ti plasmids, is catabolized in agrobacterium by three ti-plasmid-coded steps via arginine and ornithine to proline. the last enzyme, ornithine cyclodeaminase (ocd), converts ornithine directly into proline with release of ammonia. we describe the dna sequence of the ocd gene from ti plasmid c58, antiserum against an ocd fusion protein overexpressed in escherichia coli, induction and identification of the gene product in ag ...19883281832
characterization of the virb operon from an agrobacterium tumefaciens ti plasmid.the virulence genes of the agrobacterium tumefaciens ti plasmid are grouped into six transcription units and direct the transfer of t-dna into plant cells. we report here the nucleotide sequence of the largest vir operon, virb, from the ti plasmid ptia6nc. this operon contains 11 open reading frames, 7 of which show evidence of translational coupling. trpe::virb gene fusions were used to confirm the reading frames of genes virb2, 4, 5, 6, 7, 8, 10, and 11. in addition, the native gene products o ...19883281947
[transfer of hybrid plasmids prp1.2::mini-mu into agrobacterium and rhizobium cells].the study is devoted to determination of bacteriophage mu genome regions responsible for transfer limitation and instability of the plasmids in cells of strains of practically important microorganisms. with this aim in view, we determined the frequency of transfer into agrobacterium tumefaciens and rhizobium meliloti cells of plasmids with mini-mu phages carrying previously constructed deletions of various lengths. sharp decrease has been noted in the frequency of transfer into a. tumefaciens st ...19883288538
specific binding of proteins from rhizobium meliloti cell-free extracts containing nodd to dna sequences upstream of inducible nodulation genes.nodulation (nod) genes in rhizobium meliloti are transcriptionally induced by flavonoid signal molecules, such as luteolin, produced by its symbiotic host plant, alfalfa. this induction depends on expression of nodd. upstream of three inducible nod gene clusters, nodabc, nodfe, and nodh, is a highly conserved sequence referred to as a 'nod box.' the upstream sequences have no other obvious similarity. we have found that dna fragments containing the regions upstream of all three inducible transcr ...19883288541
osmotic control of glycine betaine biosynthesis and degradation in rhizobium meliloti.intracellular accumulation of glycine betaine has been shown to confer an enhanced level of osmotic stress tolerance in rhizobium meliloti. in this study, we used a physiological approach to investigate the mechanism by which glycine betaine is accumulated in osmotically stressed r. meliloti. results from growth experiments, 14c labeling of intermediates, and enzyme activity assays are presented. the results provide evidence for the pathway of biosynthesis and degradation of glycine betaine and ...19883290197
minimal region necessary for autonomous replication of ptar.the native 44-kilobase-pair plasmid ptar, discovered in a grapevine strain of agrobacterium tumefaciens, contains a single origin of dna replication confined to a 1.0-kilobase-pair region of the macromolecule. this region (ori) confers functions sufficient for replication in agrobacterium and rhizobium species but not in pseudomonas solanacearum, pseudomonas glumae, pseudomonas syringae pv. savastanoi, xanthomonas campestris pv. campestris, and escherichia coli. ori contains a repa gene that enc ...19883290199
identification and characterization of two nitrogen fixation regulatory regions, nifa and nfrx, in azotobacter vinelandii and azotobacter chroococcum.five tn5-induced nif- mutants of azotobacter vinelandii were characterized as regulatory mutants because they were restored to nif+ by the introduction of constitutively expressed nifa from klebsiella pneumoniae. the mutants fell into two different classes on the basis of hybridization to a rhizobium leguminosarum nifa gene probe and by complementation with cosmids isolated from plafri gene banks of a. vinelandii and azotobacter chroococcum. one mutant, mv3, was located in or near a nifa gene. t ...19883294559
genetic analysis of the vire operon of the agrobacterium ti plasmid ptia6.the vire operon of the agrobacterium tumefaciens ti plasmid ptia6 encodes at least one trans-acting protein involved in the expression of virulence. two open reading frames designated vire1 and vire2 code for polypeptides of 7 and 60 kilodaltons (kda), respectively, that can be visualized after expression in escherichia coli minicells. to determine which vire sequences are required for virulence, a strain deleted for the entire locus [strain ke1(ptia6 delta e)] was constructed and tested for the ...19882832362
virulence genes, borders, and overdrive generate single-stranded t-dna molecules from the a6 ti plasmid of agrobacterium tumefaciens.agrobacterium tumefaciens transfers the t-dna portion of its ti plasmid to the nuclear genome of plant cells. upon cocultivation of a. tumefaciens a348 with regenerating tobacco leaf protoplasts, six distinct single-stranded t-dna molecules (t strands) were generated in addition to double-stranded t-dna border cleavages which we have previously reported (k. veluthambi, r.k. jayaswal, and s.b. gelvin, proc. natl. acad. sci. usa 84:1881-1885, 1987). the t region of an octopine-type ti plasmid has ...19882832367
characterization and mapping of the agrocinopine-agrocin 84 locus on the nopaline ti plasmid ptic58.overlapping segments of ptic58 inserted into cosmid vectors were used to characterize the agrocinopine-agrocin 84 locus from the nopaline/agrocinopine a and b agrobacterium tumefaciens strain c58. all of the clones conferring agrocin 84 sensitivity on agrobacteria also conferred uptake of agrocin 84 and agrocinopines a and b. transposon tn3-hoho1 insertion mutations of one such clone were generated that simultaneously abolished agrocin 84 sensitivity and transport of agrocinopines a and b and ag ...19882832379
induction of pathogenic-like responses in the legume macroptilium atropurpureum by a transposon-induced mutant of the fast-growing, broad-host-range rhizobium strain ngr234.mutant strain anu2861, a transposon tn5 mutant of the fast-growing, broad-host-range rhizobium strain anu280 (ngr234 smr rfr) overproduces polysaccharide, is an ade auxotroph, and induces poorly developed nodules on leucaena leucocephala and lablab purpureus (h.c. chen, m. batley, j.w. redmond, and b.g. rolfe, j. plant physiol. 120:331-349, 1985). strain anu2861 cannot form nodules on macroptilium atropurpureum urb. (siratro) or on desmodium intortum and d. uncinatum and the nonlegume parasponia ...19882832384
enumeration of tn5 mutant bacteria in soil by using a most- probable-number-dna hybridization procedure and antibiotic resistance.investigations were made into the utility of dna hybridization in conjunction with a microdilution most-probable-number procedure for the enumeration of rhizobium spp. and pseudomonas putida in soil. isolates of rhizobium spp. and p. putida carrying the transposon tn5 were added to sterile and nonsterile burbank sandy loam soil and enumerated over time. soil populations of rhizobia were enumerated by colony hybridization, most-probable-number-dna hybridization procedure, plate counts, plant infe ...19882833161
common regulatory elements control symbiotic and microaerobic induction of nifa in rhizobium meliloti.we have previously demonstrated that the nifa promoter (nifap) of rhizobium meliloti is inducible under microaerobic conditions in the absence of alfalfa. here we show that microaerobic activation of nifap involves both cis- and trans-acting regulatory controls identical to those used symbiotically. the start site for nifa mrna synthesis was found to be the same during symbiosis and microaerobiosis, and a deletion analysis of nifap demonstrated that dna between positions -62 and -45 is essential ...19882834732
the agrobacterium tumefaciens vire2 gene product is a single-stranded-dna-binding protein that associates with t-dna.agrobacterium tumefaciens transfers t-dna into the plant genome by a process mediated by ti plasmid-encoded vir genes. cleavage at t-dna border sequences by the vird endonuclease generates linear, single-stranded t-dna molecules. in the work described in this report, we used electrophoretic mobility shift assays to show that the purified vire2 gene product binds to single-stranded dna. vire2 protein associates with t-dna as shown by immunoprecipitation studies with vire2-specific antiserum. the ...19882836366
genetic characterization and sequence analysis of the duplicated nifa/nifb gene region of rhodobacter capsulatus.a dna region showing homology to klebsiella pneumoniae nifa and nifb is duplicated in rhodobacter capsulatus. the two copies of this region are called nifa/nifb copy i and nifa/nifb copy ii. deletion mutagenesis demonstrated that either of the two copies is sufficient for growth in nitrogen-free medium. in contrast, a double deletion mutant turned out to be deficient in nitrogen fixation. the complete nucleotide sequence of a 4838 bp fragment containing nifa/nifb copy i was determined. two open ...19882836706
analysis of the complete nucleotide sequence of the agrobacterium tumefaciens virb operon.the complete nucleotide sequence of the virb locus, from the octopine ti plasmid of agrobacterium tumefaciens strain 15955, has been determined. in the large virb-operon (9600 nucleotides) we have identified eleven open reading frames, designated virb1 to virb11. from dna sequence analysis it is proposed that nearly all virb products, i.e. virb1 to virb9, are secreted or membrane associated proteins. interestingly, both a membrane protein (virb4) and a potential cytoplasmic protein (virb11) cont ...19882837739
mini-mulac transposons with broad-host-range origins of conjugal transfer and replication designed for gene regulation studies in rhizobiaceae.novel mini-mu derivatives were constructed, carrying a truncated laczya operon fused to the terminal 117 bp of the mu s-end, for the isolation of translational lac fusions by mini-mu-mediated insertion mutagenesis. different selectable markers (chloramphenicol resistance; gentamycin resistance) were introduced to allow selection for mini-mu insertions in different replicons and bacterial strains. a mini-mulac derivative carrying the site for conjugal transfer of plasmid rp4 (orit) and the origin ...19882838383
opine utilization by agrobacterium spp.: octopine-type ti plasmids encode two pathways for mannopinic acid degradation.octopine-type strains of agrobacterium tumefaciens degrade the opine mannopinic acid through a specific pathway which involves cleavage of the molecule at the c--n bond between the amino acid and the sugar moieties. mannose was identified as a product of the reaction. this pathway was inducible by mannopinic and agropinic acids, but not by mannopine or agropine, the two other mannityl opines. the transport system for this pathway appeared to be specific for mannopinic acid. a second, nonspecific ...19882838452
cosmid cloning of five zymomonas trp genes by complementation of escherichia coli and pseudomonas putida trp mutants.a library of zymomonas mobilis genomic dna was constructed in the broad-host-range cosmid plafr1. the library was mobilized into a variety of escherichia coli and pseudomonas putida trp mutants by using the helper plasmid prk2013. five z. mobilis trp genes were identified by the ability to complement the trp mutants. the trpf, trpb, and trpa genes were on one cosmid, while the trpd and trpc genes were on two separate cosmids. the organization of the z. mobilis trp genes seems to be similar to th ...19882838460
regulation of the virc and vird promoters of ptic58 by the ros chromosomal mutation of agrobacterium tumefaciens.the virc and vird operons of the virulence region of the ti plasmid are highly regulated, requiring a transcriptional regulator that is encoded by virg and is activated by the product of vira and plant phenolics such as acetosyringone. full expression of virc and vird of octopine and nopaline ti plasmids is also obtained by a mutation in the ros gene of the agrobacterium tumefaciens chromosome. s1-nuclease analysis, in vitro transcription, and dnase i protection experiments with a. tumefaciens r ...19882840554
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
mutants of rhizobium meliloti defective in succinate metabolism.we characterized mutants of rhizobium meliloti su47 that were unable to grow on succinate as the carbon source. the mutants fell into five groups based on complementation of the succinate mutations by individual recombinant plasmids isolated from a r. meliloti clone bank. enzyme analysis showed that mutants in the following groups lacked the indicated common enzyme activities: group ii, enolase (eno); group iii, phosphoenolpyruvate carboxykinase (pck); group iv, glyceraldehyde-3-phosphate dehydr ...19882841284
cascade regulation of nif gene expression in rhizobium meliloti.we report the discovery of two genes from rhizobium meliloti, fixl and fixj, which are positive regulators of symbiotic expression of diverse nitrogen fixation (nif and fix) genes. nif gene regulation is shown to consist of a cascade: the fixlj genes activate nifa, which in turn activates nifhdk and fixabcx. like nifa, fixn can be induced in free-living microaerobic cultures of r. meliloti, indicating a major physiological role for oxygen in nif and fix gene regulation. microaerobic expression o ...19882842062
transcriptional regulation of the vira and virg genes of agrobacterium tumefaciens.we have used transcriptional and translational fusions between various vir gene promoters and the lacz gene to study the regulation of vir genes. like other vir promoters, the vira promoter was induced by acetosyringone in a vira virg-dependent fashion. in addition to being induced by acetosyringone, the virg promoter was partially induced by acidic growth conditions and by starvation for inorganic phosphate. these two conditions appeared to act synergistically. the response to low ph and to pho ...19882842300
genetic analysis of a cluster of genes required for synthesis of the calcofluor-binding exopolysaccharide of rhizobium meliloti.rhizobium meliloti produces an acidic, calcofluor-binding exopolysaccharide which plays a role in nodulation of alfalfa plants by this bacterium. we constructed and mapped 102 transposon insertions in a 48-kilobase (kb) region previously shown to contain several exo genes. mutations affecting production of the calcofluor-binding exopolysaccharide were clustered in a 22-kb region and fell into 12 complementation groups. strains carrying mutations in seven of the complementation groups (exoa, exob ...19882842306
rhizobium meliloti mutants that overproduce the r. meliloti acidic calcofluor-binding exopolysaccharide.the acidic calcofluor-binding exopolysaccharide of rhizobium meliloti rm1021 plays one or more critical roles in nodule invasion and possibly in nodule development. two loci, exor and exos, that affect the regulation of synthesis of this exopolysaccharide were identified by screening for derivatives of strain rm1021 that formed mucoid colonies that fluoresced extremely brightly under uv light when grown on medium containing calcofluor. the exopolysaccharide produced in large quantities by the ex ...19882842307
symbiotic loci of rhizobium meliloti identified by random tnphoa mutagenesis.we have developed a system for using tnphoa (tnphoa is tn5 is50l::phoa), which generates fusions to alkaline phosphatase (c. manoil and j. beckwith, proc. natl. acad. sci. usa 82:8129-8133, 1985), in rhizobium meliloti. active fusions expressing alkaline phosphatase can arise only when this transposon inserts in genes encoding secreted or membrane-spanning proteins. by confining our screening to 1,250 tnphoa-generated mutants of r. meliloti that expressed alkaline phosphatase, we efficiently ide ...19882842308
bacterial-type ferredoxin genes in the nitrogen fixation regions of the cyanobacterium anabaena sp. strain pcc 7120 and rhizobium meliloti.the nucleotide sequence of a region located downstream of the nifb gene, both in the cyanobacterium anabaena sp. strain pcc 7120 and in rhizobium meliloti, has been determined. this region contains a gene (fdxn) whose predicted polypeptide product strongly resembles typical bacterial ferredoxins. cyanobacteria have not previously been shown to contain bacterial-type ferredoxins. the presence of this gene suggests that nitrogen-fixing cyanobacteria have at least four distinct ferredoxins.19882842320
homology mapping of t-dna regions on three agrobacterium rhizogenes ri plasmids by electron microscope heteroduplex studies.recombinant plasmids carrying segments of the agrobacterium rhizogenes t-dna regions of the three ri plasmids 1855 (tl-dna only), 8196, and 2659 were used for establishing homology maps by electron microscope examination of heteroduplexes. plasmid dna was linearized by digestion with suitable restriction endonucleases in order to generate large t-dna segments. heteroduplexes were prepared in 50% formamide and spread under standard conditions. measurements of double and single strands allowed the ...19882843937
distribution of insertion sequence isrm1 in rhizobium meliloti and other gram-negative bacteria.an internal 0.9 kb segment of rhizobium meliloti insertion sequence isrm1 was used as a probe to determine the distribution of isrm1 in strains of r. meliloti and other gram-negative bacteria. the insertion sequence was detected in 80% (12/15) of r. meliloti strains from different parts of the world. its copy number ranged from one to at least eleven. the isrm1 copies detected showed variation in their internal restriction sites and their degree of homology to the probe. isrm1 was found in a var ...19882846753
genetic analysis of carbamoylphosphate synthesis in rhizobium meliloti 104a14.we have previously isolated ineffective (fix-) mutants of rhizobium meliloti 104a14 requiring both arginine and uracil, and thus probably defective in carbamoylphosphate synthetase. we describe here the molecular and genetic analysis of the r. meliloti genes coding for carbamoylphosphate synthetase. plasmids that complement the mutations were isolated from a r. meliloti gene bank. restriction analysis of these plasmids indicated that complementation involved two unlinked regions of the r. melilo ...19882846756
interference between rhizobium meliloti and rhizobium trifolii nodulation genes: genetic basis of r. meliloti dominance.transfer of an incp plasmid carrying the rhizobium meliloti nodfe, nodg, and nodh genes to rhizobium trifolii enabled r. trifolii to nodulate alfalfa (medicago sativa), the normal host of r. meliloti. using transposon tn5-linked mutations and in vitro-constructed deletions of the r. meliloti nodfe, nodg, and nodh genes, we showed that r. meliloti nodh was required for r. trifolii to elicit both root hair curling and nodule initiation on alfalfa and that nodh, nodfe, and nodg were required for r. ...19882848012
synthesis of an opine-like compound, a rhizopine, in alfalfa nodules is symbiotically regulated.we show that the promoter of the mos locus, which encodes genes required for the synthesis of a nodule-specific, opine-like compound, a rhizopine, in alfalfa nodules is regulated by the symbiotic nitrogen-fixation regulatory gene nifa. the 5'-regulatory region and amino-terminal end of the first open reading frame of the mos locus are highly homologous to the 5'-regulatory region and amino-terminal portion of the rhizobium meliloti nifh gene. the coordinate regulation of mos and nif genes sugges ...19882848255
analysis of pss genes of rhizobium leguminosarum required for exopolysaccharide synthesis and nodulation of peas: their primary structure and their interaction with psi and other nodulation genes.strains of rhizobium leguminosarum (r.l.) biovar viciae containing pss mutations fail to make the acidic exopolysaccharides (eps) and are unable to nodulate peas. it was found that they also failed to nodulate vicia hirsuta, another host of this biovar. when peas were co-inoculated with pss mutant derivatives of a strain of r.l. by viciae containing a sym plasmid plus a cured strain lacking a sym plasmid (and which is thus nod-, but for different reasons) but which makes the acidic eps, normal n ...19882851702
construction of a tn5 derivative encoding bioluminescence and its introduction in pseudomonas, agrobacterium and rhizobium.a simple method based upon the use of a tn5 derivative, tn5-lux, has been devised for the introduction and stable expression of the character of bioluminescence in a variety of gram-negative bacteria. in tn5-lux, the luxab genes of vibrio harveyi encoding luciferase are inserted on a sali--bglii fragment between the kanamycin resistance (kmr) gene and the right insertion sequence. the transposon derivative was placed on a transposition suicide vehicle by in situ recombination with the tn5 suicid ...19882851709
map location on agrobacterium root-inducing plasmids of homologies with the virulence region of tumor-inducing plasmids.southern-type hybridizations were carried out in order to identify sequence homologies with the pti vir loci, on an agropine-type plasmid (prihri) and a mannopine-type plasmid (pri8196) of agrobacterium rhizogenes. the localization of the sequences hybridizing with subcloned fragments containing vir a, b, g, c, and d from ptiach5 indicated a similar linear organization of the pti vir loci and their homologies on prihri and pri8196, though no homology was detected on both pri with a 1.1-kb intern ...19882852815
mobilization and transfer of azospirillum lipoferum plasmid by the tn5-mob transposon into a plasmid-free agrobacterium tumefaciens strain.azospirillum lipoferum 4b harbors five cryptic plasmids. several suicide plasmids were used to transfer tn5-mob to a. lipoferum 4b. tn5-mob insertion mutations of this strain could be obtained at frequencies of 10(-8)-10(-7) per recipient cell. one hundred tn5-mob a. lipoferum 4b mutants were used in bacterial matings with a plasmid-free agrobacterium tumefaciens recipient strain. this is the first report of mobilization, transfer, and replication of an azospirillum plasmid in agrobacterium tume ...19882852995
construction of transposons carrying the transfer functions of rp4.the transfer genes and origin of transfer of the wide host range plasmid rp4 have been cloned into the transposons tn1 and tn5. the newly constructed transposons can be used to mutagenize bacterial plasmids or the chromosome in species such as escherichia coli or rhizobium. it is then possible to mobilize the plasmid or chromosome using the transfer functions provided in cis by the transposon. these constructs may aid chromosome mapping in many gram-negative species by allowing the wider use of ...19882854282
[deletional and insertional analysis of the antitumorigenicity of the plasmid r388 in agrobacterium tumefaciens].the study of the plasmid r388 deletional derivatives has shown the antitumorigenicity determinant of the plasmid to be contained by the tra-operon. transposon tn5 has been used for selection of a number of insertional mutants having lost the antitumorigenic properties. the difference in the locations of tn5 inserts was found, all of the latter being localized within the tra-operon. the data obtained suggest the locus of the plasmid r388 responsible for its antitumorigenic properties to be locate ...19882855090
[mutation, transfer and location of symbiotic genes of rhizobium leguminosarum biovar phaseoli by insertion of tn5-mob]. 19882856224
identification of the product of an agrobacterium tumefaciens chromosomal virulence gene.the chvb operon of agrobacterium tumefaciens is required for bacterial attachment to plant cells and for efficient crown gall tumor formation. as defined by the virulence phenotypes of mutants with transposon insertions mapping in the region, the operon was previously mapped to a 5-kilobase (kb) stretch of chromosomal dna. we report here that the operon is actually about 8.5 kb long and that it contains a 7-kb gene coding for a large membrane protein involved in the synthesis of cyclic beta-1,2- ...19882856522
characterization of the peribacteroid membrane atpase of lupin root nodules.peribacteroid membranes can be isolated in essentially pure form from 20-day lupin root nodules by osmotic shock of the purified membrane enclosed bacteroids. the atpase (ec 3.6.1.3) associated with this membrane has an acid ph optimum (5.25) and is specific for atp (mg-atp km = 0.16 mm). the enzyme activity requires magnesium or manganese ions, is slightly stimulated by the cations potassium and rubidium, and is inhibited by vanadate, diethylstilbestrol, n,n'-dicyclohexylcarbodiimide, fluoride, ...19882969700
siderophore containing 2,3-dihydroxybenzoic acid and threonine formed by rhizobium trifolli.an iron-binding compound was isolated from ethyl acetate extract of culture supernatant fluid of rhizobium trifolii ar6 and was purified by iron-exchange chromatography. the compound was characterized by uv and ir. it contained 2,3-dihydroxy-benzoic acid and threonine and was accumulated during stationary phase of growth in iron-deficient media. synthesis of the siderophore was repressed by fecl3. in iron limited medium the compound promoted growth of r. trifolii strains.19882976565
interaction of nod and exo rhizobium meliloti in alfalfa nodulation.among the genes of rhizobium meliloti su47 that affect nitrogen-fixing symbiosis with alfalfa are nod genes, in which mutations block nodule induction, and exo genes, in which mutations allow nodule formation but block rhizobial exopolysaccharide production as well as nodule invasion and nitrogen fixation. to investigate whether an exo+ bacterium can "help" (that is, reverse the symbiotic defect of) an exo mutant in trans, we have coinoculated alfalfa with pairs of rhizobia of different genotype ...19882979704
identification and characterization of the nodd gene in rhizobium leguminosarum strain 1001.a gene library of the symbiotic 240-kb plasmid of rhizobium leguminosarum strain 1001 was constructed in puc18. the clones showing homology with a 6.6-kb fragment containing nodefdabc from the sym plasmid prllji were detected by colony hybridization. additional probes from the symbiotic region of prllji were used to localize the corresponding genes on the map of prle1001a. the relative positions of nod and nif gene clusters are different than those of prllji. a comparison of the amino acid seque ...19882979909
identification of a nodd-dependent locus in the rhizobium strain ngr234 activated by phenolic factors secreted by soybeans and other legumes.transfer of the strain ngr234nodd 1 gene into the narrow host range r. trifolii strain anu843 on either a 6.7-kb hindiii or 17-kb xhoi fragment broadens the host range of this bacterium to include the tropical legumes vigna unguiculata, glycine ussuriensis, leucaena leucocephala, and siratro (macroptilium atropurpureum). contrary to previous data (bassam et al. 1986), mutagenesis of the 17-kb xhoi fragment with a mini-mu lac transposon (mu dii1734) showed that a functional nodd 1 gene was essent ...19882980201
inducible expression of cytokinin biosynthesis in agrobacterium tumefaciens by plant phenolics.nopaline strains of agrobacterium tumefaciens contain a gene, tzs, that encodes a cytokinin biosynthetic prenyl transferase. the gene is located adjacent to the ti plasmid virulence region and is constitutively expressed at low levels. as a result, bacteria containing tzs secrete low levels of zeatin into the medium. we find zeatin secretion to be induced more than 100-fold by acetosyringone, one of a number of naturally occurring phenolics produced by plants in response to wounding. induction w ...19882980282
a plasmid of rhizobium meliloti 41 encodes catabolism of two compounds from root exudate of calystegium sepium.our objectives were to identify substances produced by plant roots that might act as nutritional mediators of specific plant-bacterium relationships and to delineate the bacterial genes responsible for catabolizing these substances. we discovered new compounds, which we call calystegins, that have the characteristics of nutritional mediators. they were detected in only 3 of 105 species of higher plants examined: calystegia sepium, convolvulus arvensis (both of the convolvulaceae family), and atr ...19882981046
ammonium assimilation in rhizobium phaseoli by the glutamine synthetase-glutamate synthase pathway.evidence from in vitro and in vivo studies showed that in rhizobium phaseoli ammonium is assimilated by the glutamine synthetase (gs)-glutamate synthase nadph pathway. no glutamate dehydrogenase activity was detected. r. phaseoli has two gs enzymes, as do other rhizobia. the two gs activities are regulated on the basis of the requirement for low (gsi) or high (gsii) ammonium assimilation. when the 2-oxoglutarate/glutamine ratio decreases, gsi is adenylylated. when gsi is inactivated, gsii is ind ...19882892829
introduction of the escherichia coli gdha gene into rhizobium phaseoli: effect on nitrogen fixation.rhizobium phaseoli lacks glutamate dehydrogenase (gdh) and assimilates ammonium by the glutamine synthetase-glutamate synthase pathway. a strain of r. phaseoli harboring the escherichia coli gdh structural gene (gdha) was constructed. gdh activity was expressed in r. phaseoli in the free-living state and in symbiosis. nodules with bacteroids that expressed gdh activity had severe impairment of nitrogen fixation. also, r. phaseoli cells that lost gdh activity and assimilated ammonium by the gluta ...19882892830
unusual pathogens in neutropenic patients. 19882899595
both positive and negative regulatory elements mediate expression of a photoregulated cab gene from nicotiana plumbaginifolia.we have analyzed promoter regulatory elements from a photoregulated cab gene (cab-e) isolated from nicotiana plumbaginifolia. these studies have been performed by introducing chimeric gene constructs into tobacco cells via agrobacterium tumefaciens-mediated transformation. expression studies on the regenerated transgenic plants have allowed us to characterize three positive and one negative cis-acting elements that influence photoregulated expression of the cab-e gene. within the upstream sequen ...19882901343
the leghaemoglobins. 19882906540
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
developmental regulation of nodule-specific genes in alfalfa root nodules.we have cloned alfalfa nodule-specific cdnas that code for leghemoglobin (lb), glutamine synthetase (gs), and three unidentified nodulins. hybrid-select translation of nodule rna followed by 2-d gel electrophoresis showed that the lb-specific cdna corresponded to at least four lb species of 12 kda. one of the unidentified cdna clones (n-32/34) corresponded to at least five polypeptides of 32-34 kda; a second unidentified cdna clone (n-14) corresponded to an individual polypeptide of 14 kda. the ...19882908768
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
structure and transcription analysis of the gene encoding a cellobiase from agrobacterium sp. strain atcc 21400.the dna sequence was determined for the cloned agrobacterium sp. strain atcc 21400 beta-glucosidase gene, abg. high-resolution nuclease s1 protection studies were used to map the abg mrna 5' and 3' termini. a putative abg promoter was identified whose sequence shows similarities to the consensus promoter of escherichia coli and with the nif promoter regions of klebsiella. the abg coding sequence was 1,374 nucleotides long. the molecular weight of the enzyme, based on the predicted amino acid seq ...19882826395
genetic and physical analyses of group e exo- mutants of rhizobium meliloti.mutants of rhizobium meliloti which are deficient in exopolysaccharide synthesis have been classified into six different genetic groups (a through f) (j. a. leigh, e. r. signer, and g. c. walker, proc. natl. acad. sci. usa 82:6231-6235, 1985). using physical and genetic techniques, we have demonstrated that the group e exo- mutants carry deletions in the exoa-exob region of the megaplasmid prmesu47b. we have constructed strains carrying defined deletions which remove up to 200 kilobases of prmes ...19882826404
rhizobium meliloti genes required for c4-dicarboxylate transport and symbiotic nitrogen fixation are located on a megaplasmid.a mutant of rhizobium meliloti unable to transport c4 dicarboxylates (dct) was isolated after tn5 mutagenesis. the mutant, 4f6, could not grow on aspartate or the tricarboxylic acid cycle intermediates succinate, fumarate, or malate. it produced symbiotically ineffective nodules on medicago sativa in which bacteroids appeared normal, but the symbiotic zone was reduced and the plant cells contained numerous starch granules at their peripheries. cosmids containing the dct region were obtained by s ...19882828335
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
rhizobium meliloti noda and nodb genes are involved in generating compounds that stimulate mitosis of plant cells.the nodb gene of rhizobium meliloti encodes a 23.8-kda protein that is conserved in several rhizobium species. monospecific polyclonal antibodies against nodb were used to localize this protein in the cytosol of r. meliloti and escherichia coli cells containing nodabc genes. in comparison to the noda and nodc proteins, nodb is synthesized in a disproportionately low amount. the noda and nodb proteins are involved in generating small, heat-stable compounds that stimulate the mitosis of various pl ...198816593994
the habits of roots: what's up down under?defining interactions of roots with the surrounding soil environment has been the focus of many recent investigations. as a result of these efforts, we are gaining an appreciation of the varied and often surprising strategies whereby roots adjust to and condition their soil environment for optimal growth and development. this article summarizes current knowledge of the often complex interactions between roots and biotic and abiotic factors within the soil. these interactions are interpreted i ...198811537857
high survivability of cheese whey-grown rhizobium meliloti cells upon exposure to physical stress.whey, a by-product of the dairy industry, has been found to protect the rhizobia cells during freezing and thawing. cells of rhizobia grown on whey sustained freezing better at -18 degrees c than did cells grown on mannitol or sucrose. suspensions of cells grown on whey or mannitol that were suspended in whey performed equally well at -18 and -80 degrees c, with 94 and 100% survival, respectively. whey-grown rhizobia in pellets withstood desiccation better than did their mannitol-grown equivalen ...198816347524
a study of 33 bacteriophages of rhizobium meliloti.a total of 33 rhizobium meliloti bacteriophages were studied. of those, 21 were isolated in northern france from field soil in which medicago sativa l. was grown. the other 12 phages were obtained by uv light and mitomycin c induction from 46 r. meliloti strains. rhizobiophages were characterized by their morphology, host range, serological properties, restriction endonuclease patterns, dna-dna homologies, and dna molecular weights. five morphotypes were observed showing tailed phages with icosa ...198816347525
growth of indigenous rhizobium leguminosarum and rhizobium meliloti in soils amended with organic nutrients.the ability of indigenous rhizobium leguminosarum and rhizobium meliloti to use organic nutrients as growth substrates in soil was assessed by indirect bacteriophage analysis. a total of 17 organic compounds, including 9 carbohydrates, 3 organic acids, and 5 amino acids, were tested (1,000 mug g) in three soils with different cropping histories. four additional soils were screened with a glucose amendment. nutrient amendments stimulated growth of indigenous rhizobia, allowing subsequent replicat ...198816347530
induction of symbiotically defective auxotrophic mutants of rhizobium fredii hh303 by transposon mutagenesis.symbiotically defective auxotrophic mutants were isolated by transposon tn5 mutagenesis of rhizobium fredii hh303, a fast-growing microsymbiont of north american commercial soybean cultivars such as glycine max cv. williams. three different tn5-carrying suicide vectors, pblk1-2, psup1011, and pgs9, were used for mutagenesis with transposition frequencies of 4 x 10, 3 x 10, and 1 x 10, respectively, while the frequency of background mutation resistant to 500 mug of kanamycin per ml was 1 x 10. fr ...198816347555
a positive strain identification method for rhizobium meliloti.about 80% of rhizobium meliloti strains contain 1 to 11 copies of insertion sequence isrm1 in their genomes (r. wheatcroft and r. j. watson, j. gen. microbiol. 134:113-121, 1988). hybridization to separated genomic dna fragments with an isrm1-specific probe produces patterns of hybridization bands which are distinctive for each strain. these patterns can be compared between strains to prove or disprove common identity. in most cases relatedness can be inferred despite phenotypic differences or m ...198816347567
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
effect of naturally occurring nif reiterations on symbiotic effectiveness in rhizobium phaseoli.most naturally occurring strains of rhizobium phaseoli possess reiteration of the nif genes. three regions contain nitrogenase structural genes in strain cfn42. two of these regions (a and b) have copies of nifh, nifd, and nifk, whereas the third region (c) contains only nifh. strains containing mutations in either nif region a or nif region b had significantly diminished symbiotic effectiveness compared with the wild-type strain on the basis of nodule mass, total nitrogenase activity per plant, ...198816347593
ecological indicators of native rhizobia in tropical soils.the relationship between environment and abundance of rhizobia was described by determining the populations of root nodule bacteria at 14 diverse sites on the island of maui. mean annual rainfall at the sites ranged from 320 to 1,875 mm, elevation from 37 to 1,650 m, and soil ph from 4.6 to 7.9. four different soil orders were represented in this study: inceptisols, mollisols, ultisols, and an oxisol. the rhizobial populations were determined by plant infection counts of five legumes (trifolium ...198816347624
diversity of plasmid profiles and conservation of symbiotic nitrogen fixation genes in newly isolated rhizobium strains nodulating sulla (hedysarum coronarium l.).forty-five rhizobium strains nodulating sulla (hedysarum coronarium l.), isolated from plants grown in different sites in menorca island and southern spain, were examined for plasmid content and the location and organization of nif (nitrogen fixation) and nod (nodulation) sequences. a great diversity in both number and size of the plasmids was observed in this native population of strains, which could be distributed among 19 different groups according to their plasmid profiles. no correlation wa ...198816347636
narrow- and broad-host-range symbiotic plasmids of rhizobium spp. strains that nodulate phaseolus vulgaris.agrobacterium transconjugants containing symbiotic plasmids from different rhizobium spp. strains that nodulate phaseolus vulgaris were obtained. all transconjugants conserved the parental nodulation host range. symbiotic (sym) plasmids of rhizobium strains isolated originally from p. vulgaris nodules, which had a broad nodulation host range, and single-copy nitrogenase genes conferred a fix phenotype to the agrobacterium transconjugants. a fix phenotype was obtained with sym plasmids of strains ...198816347637
reliability of the most-probable-number technique for enumerating rhizobia in tropical soils.we used six rhizobium-legume systems to test the reliability of the most-probable-number (mpn) technique for enumerating rhizobia introduced into 14 sites representing four soil orders. the range-of-transition values (the number of dilution steps between the first not-entirely-positive and the last not-entirely-negative growth units) were compared for each species and for each soil. the probability that the observed data were significantly different from theoretical values varied with the specie ...198816347661
melanin production by rhizobium strains.different rhizobium and bradyrhizobium strains were screened for their ability to produce melanin. pigment producers (mel) were found among strains of r. leguminosarum biovars viceae, trifolii, and phaseoli, r. meliloti, and r. fredii; none of 19 bradyrhizobium strains examined gave a positive response. melanin production and nod genes were plasmid borne in r. leguminosarum biovar trifolii rs24. in r. leguminosarum biovar phaseoli cfn42 and r. meliloti gr015, mel genes were located in the respec ...198816347690
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
nodulation and nitrogen fixation efficacy of rhizobium fredii with phaseolus vulgaris genotypes.phaseolus plant introduction (pi) genotypes (consisting of 684 p. vulgaris, 26 p. acutifolius, 39 p. lunatus, and 5 p. coccineus accessions) were evaluated for their ability to form effective symbioses with strains of six slow-growing (bradyrhizobium) and four fast-growing (rhizobium fredii) soybean rhizobia. of the 684 p. vulgaris genotypes examined, three pis were found to form effective nitrogen-fixing symbioses with the r. fredii strains. while none of the bradyrhizobium strains nodulated an ...198816347705
host ranges of the incn group plasmid pcu1 and its minireplicon in gram-negative purple bacteria.the bacterial host ranges of the conjugatively self-transmissible incn group plasmid pcu1 and its mobilizable miniderivative, pcu785, were examined. species of the gram-negative purple bacteria were chosen for this study. conjugative mobilization of pcu785 into a wide variety of bacteria was facilitated by the presence of orit of the broad-host-range plasmid rk2 in pcu785. although the host range of the incn tra system of pcu1 is broad, the host range of its replicon is limited. however, the pcu ...198816347740
expression of nodulation genes in rhizobium leguminosarum biovar trifolii is affected by low ph and by ca and al ions.early stages in the infection of leguminous plants by rhizobium spp. are restricted at low ph and are further influenced by the presence of ca and al ions. in the experiments reported here, transcriptional and translational fusions of the escherichia coli lacz gene to rhizobium leguminosarum biovar trifolii nodulation (nod) genes were used to investigate the effects of ph and of ca and al ions on nod gene expression. the regulatory nodd gene in r. leguminosarum biovar trifolii was constitutively ...198816347761
isolation of rhizobium loti strain-specific dna sequences by subtraction hybridization.mixed-phase (heterogeneous) and single-phase (homogeneous) dna subtraction-hybridization methods were used to isolate specific dna probes for closely related rhizobium loti strains. in the heterogeneous method, dna from the prospective probe strain was repeatedly hybridized to a mixture of dna from cross-hybridizing strains (subtracter dna) which was immobilized on an epoxy-activated cellulose matrix. probe strain sequences which shared homology with the matrix-bound subtracter dna hybridized to ...198816347782
identification and characterization of a bacteroid-specific dehydrogenase complex in rhizobium leguminosarum pre.in membranes of rhizobium leguminosarum bacteroids isolated from nitrogen-fixing pea root nodules, two different protein complexes with nadh dehydrogenase activity were detected. one of these complexes, with a molecular mass of 110 kilodaltons, was also found in membranes of free-living rhizobia, but the other, with a molecular mass of 550 kilodaltons, appeared to be present only in bacteroids. the bacteroid-specific complex, referred to as dh1, probably consists of at least four different subun ...198816347793
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