| unusual structure of the exopolysaccharide of rhizobium leguminosarum bv. viciae strain 248. | the exopolysaccharide from r. leguminosarum bv. viciae strain 248 differs from those of other rhizobium strains with similar symbiotic behavior. 13c-n.m.r. spectroscopy of fragments generated by partial hydrolysis, together with methylation analysis and 13c-n.m.r. spectroscopy of the enzymically depolymerised exopolysaccharide, indicated the following nonasaccharide repeating-unit: [formula: see text] the locations of the acetyl and 3-hydroxybutanoyl substituents in the exopolysaccharide are ass ... | 1991 | 1802384 |
| the relationship between nodulin gene expression and the rhizobium nod genes in vicia sativa root nodule development. | the role of the rhizobium nod genes in the induction of nodulin gene expression was examined by analyzing nodules formed on vetch roots by bacterial strains containing only the nod region. introduction of an 11-kb cloned nod region of the r. leguminosarum sym plasmid prl1ji into sym plasmid-cured rhizobia conferred on the recipient strains the ability to induce nodules in which all nodulin genes were expressed. this proves that from the sym plasmid only the nod region is involved in the inductio ... | 1989 | 2520161 |
| localization and symbiotic function of a region on the rhizobium leguminosarum sym plasmid prl1ji responsible for a secreted, flavonoid-inducible 50-kilodalton protein. | a previously described (r. a. de maagd, c. a. wijffelman, e. pees, and b. j. j. lugtenberg, j. bacteriol. 170:4424-4427, 1988) sym plasmid-dependent, naringenin-inducible 50-kilodalton protein of rhizobium leguminosarum biovar viciae is further characterized in this paper. the protein was overproduced by constructing a strain containing multiple copies of the r. meliloti nodd gene, which facilitated its purification. an antiserum was used to screen tn5 insertion mutants located in the prl1ji reg ... | 1989 | 2644226 |
| nodo, a new nod gene of the rhizobium leguminosarum biovar viciae sym plasmid prl1ji, encodes a secreted protein. | the region of the rhizobium leguminosarum biovar viciae sym plasmid prl1ji, responsible for the production and secretion of a previously described 50-kilodalton protein (r. a. de maagd, c. a. wijffelman, e. pees, and b. j. j. lugtenberg, j. bacteriol. 170:4424-4427, 1988), was cloned and its nucleotide sequence was determined. a new nod gene, nodo, preceded by a poorly conserved nod box, was identified and its transcriptional start site was determined. comparison of its predicted protein product ... | 1989 | 2687250 |
| 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 ... | 1988 | 2851702 |
| the nodi gene product of rhizobium leguminosarum is closely related to atp-binding bacterial transport proteins; nucleotide sequence analysis of the nodi and nodj genes. | the nucleotide sequence of a 2-kb fragment immediately downstream of the nodabc genes of the rhizobium leguminosarum symbiotic plasmid prl1ji has been determined. genes corresponding to the two open reading frames identified are named nodi and nodj. tn 5 insertions into these genes result in a "nodulation-delayed" phenotype. the predicted amino acid sequence of the nodi gene shows considerable homology to inner-membrane-located gene products involved in active transport systems in escherichia co ... | 1986 | 3019841 |
| induction of the noda promoter of rhizobium leguminosarum sym plasmid prl1ji by plant flavanones and flavones. | an expression vector containing the rhizobium leguminosarum noda promoter cloned in front of the escherichia coli lacz gene was used to characterize the properties of the r. leguminosarum noda gene-inducing compound(s) present in sterile root exudate of the host plant vicia sativa l. subsp. nigra (l.). the major inducing compound was flavonoid in nature, most likely a flavanone. the commercially available flavonoids naringenin (5,7,4'-trihydroxyflavanone), eriodictyol (5,7,3'4'-tetrahydroxyflava ... | 1987 | 3539915 |
| identification of a rhizosphere protein encoded by the symbiotic plasmid of rhizobium leguminosarum. | a protein was identified which was made by wild-type strains of rhizobium leguminosarum but not by nodulation-deficient derivatives which had deletions of their symbiotic plasmids. the protein, which had a subunit molecular weight of ca. 24,000 ( 24k ), was found to be present in large amounts within bacteria that had been reisolated from the surface of inoculated pea roots but was not detected in bacteroids isolated from nodules. the protein could also be induced during growth of r. leguminosar ... | 1984 | 6327615 |
| construction and characterization of a rhizobium leguminosarum biovar viciae strain designed to assess horizontal gene transfer in the environment. | an integration vector was developed which inserts cloned dna in a non-essential site of the rhizobium leguminosarum biovar viciae chromosome. the expression of integrated genes is under the control of the constitutive neomycin phosphotransferase ii (nptii) promoter of transposon tn5. the design of the vector ensures that loss of vector sequences can be detected, enabling selection of progeny containing only the requisite dna. the newly constructed vector was employed to insert the escherichia co ... | 1995 | 7781972 |
| cell-to-cell signaling in the symbiotic nitrogen-fixing bacterium rhizobium leguminosarum: autoinduction of a stationary phase and rhizosphere-expressed genes. | the sym plasmid prl1ji encodes functions for the formation of nitrogen-fixing pea root nodules by rhizobium leguminosarum. some of the nodulation genes are involved in recognition of chemical signals produced by the plant root, and others are required for production of chemical signals recognized by the plant. prl1ji also contains a regulatory gene, rhir, that is homologous to luxr, the transcriptional activator of luminescence genes in vibrio fischeri. luxr requires a signal compound, an autoin ... | 1996 | 8550455 |
| a rhizobium leguminosarum biovar trifolii locus not localized on the sym plasmid hinders effective nodulation on plants of the pea cross-inoculation group. | introduction of the sym plasmid prl1ji into the cured rhizobium leguminosarum bv. trifolii strain rcr5 resulted in a strain, designated rbl5523, that was expected to nodulate plants of the pea cross-inoculation group. however, effective nodulation occurred only on vicia sativa plants, not on v. hirsuta or pisum sativum. after random tn5 mutagenesis, a derivative of rbl5523 was isolated that effectively nodulated and fixed nitrogen on p. sativum and v. hirsuta. characterization of the mutant, rbl ... | 1997 | 9304865 |
| cloning and characterization of a rhizobium leguminosarum gene encoding a bacteriocin with similarities to rtx toxins. | a 3-kb region containing the determinant for bacteriocin activity from rhizobium leguminosarum 248 was isolated and characterized by tn5 insertional mutagenesis and dna sequencing. southern hybridizations showed that this bacteriocin was encoded on the plasmid prl1ji and that homologous loci were not found in other unrelated r. leguminosarum strains. tn5 insertional mutagenesis showed that mutations in the c-terminal half of the bacteriocin open reading frame apparently did not abolish bacterioc ... | 1999 | 10388672 |
| the regulatory locus cinri in rhizobium leguminosarum controls a network of quorum-sensing loci. | n-(3-hydroxy-7-cis-tetradecenoyl)-l-homoserine lactone (3oh, c14:1-hsl) is a quorum-sensing signalling molecule produced by rhizobium leguminosarum. it is unusual in that it inhibits the growth of several strains of r. leguminosarum and was previously known as 'small bacteriocin'. the cinri locus responsible for the production of 3oh,c14:1-hsl has been characterized; it is predicted to be on the chromosome, based on dna hybridization. the cinr and cini genes are in different transcriptional unit ... | 2000 | 10931307 |
| multiple n-acyl homoserine lactone signals of rhizobium leguminosarum are synthesized in a distinct temporal pattern. | a common form of bacterial quorum sensing involves the production and release of acyl homoserine lactone (ahl) signal metabolites. the nitrogen-fixing symbiont rhizobium leguminosarum reportedly produces at least six different ahls, but little is known about the regulation of biosynthesis of these molecules. we used a radiolabeling protocol to quantify the relative amounts of ahls synthesized over time by r. leguminosarum cells with and without the symbiosis plasmid prl1ji. cells containing prl1 ... | 2001 | 11698364 |
| n-acyl-homoserine lactone inhibition of rhizobial growth is mediated by two quorum-sensing genes that regulate plasmid transfer. | the growth of some strains of rhizobium leguminosarum bv. viciae is inhibited by n-(3-hydroxy-7-cis tetradecenoyl)-l-homoserine lactone (3oh-c(14:1)-hsl), which was previously known as the small bacteriocin before its characterization as an n-acyl homoserine lactone (ahl). tn5-induced mutants of r. leguminosarum bv. viciae resistant to 3oh-c(14:1)-hsl were isolated, and mutations in two genes were identified. these genes, bisr and trir, which both encode luxr-type regulators required for plasmid ... | 2002 | 12142421 |
| quorum-sensing in rhizobium. | quorum-sensing signals are found in many species of legume-nodulating rhizobia. in a well-characterized strain of r. leguminosarum biovar viciae, a variety of autoinducers are synthesised, and all have been identified as n-acyl-homoserine lactones. one of these n-acyl-homoserine lactones, is n-(3-hydroxy-7-cis-tetradecenoyl)-l-homoserine lactone, previously known as small bacteriocin, which inhibits the growth of several r. leguminosarum strains. the cinri locus is responsible for the production ... | 2002 | 12448738 |
| the influence of the symbiotic plasmid prl1ji on the distribution of gm rhizobia in soil and crop rhizospheres, and implications for gene flow. | the distribution of two genetically modified rhizobium leguminosarum strains was investigated in the field. one, rsm2004, released in 1987, carries a tns marker on its conjugative symbiotic plasmid (psym). the second, ct0370, released at the same site in 1994, has a gusa gene integrated into its chromosome but no psym. plate counts indicated that the ct0370 population became established at a higher level than rsm2004. however, when peas, alfalfa and barley were grown, rsm2004 was found to outnum ... | 2002 | 12448756 |
| recipient-induced transfer of the symbiotic plasmid prl1ji in rhizobium leguminosarum bv. viciae is regulated by a quorum-sensing relay. | analysis of the regulation of plasmid transfer genes on the symbiotic plasmid prl1ji in rhizobium leguminosarum bv. viciae has revealed a novel regulatory relay that is specifically poised to detect an n-acyl-homoserine lactone (ahl) made by different cells (potential recipients of prl1ji). adjacent to the trai-trbbcdejklfghi plasmid transfer operon on prl1ji are two regulatory genes, bisr and trar, which encode luxr-type quorum-sensing regulators required for conjugation. potential recipients o ... | 2003 | 14617175 |
| cloning of the symbiotic region of rhizobium leguminosarum: the nodulation genes are between the nitrogenase genes and a nifa-like gene. | the region of the rhizobium leguminosarum plasmid prl1ji involved in nodulation and nitrogen fixation has been cloned on a series of four overlapping cosmid clones. these clones represent 60 kb of prl1ji dna on which a series of tn5-induced fix and nod alleles have been identified, with the two most distant alleles being separated by 45 kb of dna. the mutant alleles fell into three groups, two clusters of fix alleles separated by one cluster of nod alleles. within one group of fix alleles, dna h ... | 1983 | 16453461 |
| the rhizobium leguminosarum nodulation gene nodf encodes a polypeptide similar to acyl-carrier protein and is regulated by nodd plus a factor in pea root exudate. | the dna sequence of approximately 3.5 kb of the nodulation (nod) region of the rhizobium leguminosarum symbiotic plasmid prl1ji was determined. three open reading frames were identified; genes corresponding to these have been called nodd, node and nodf.nodd is adjacent to noda and is transcribed in the opposite direction. the nodf and node genes are downstream of, and transcribed in the same direction as, nodd with 667 nucleotides between nodd and nodf and three nucleotides separating nodf and n ... | 1986 | 16453679 |
| quorum-sensing-regulated transcriptional initiation of plasmid transfer and replication genes in rhizobium leguminosarum biovar viciae. | transfer of the rhizobium leguminosarum biovar viciae symbiosis plasmid prl1ji is regulated by a cascade of gene induction involving three luxr-type quorum-sensing regulators, trar, bisr and cinr. trar induces the plasmid transfer trai-trb operon in a population-density-dependent manner in response to n-acylhomoserine lactones (ahls) made by trai. expression of the trar gene is primarily induced by bisr in response to ahls made by cini, and expression of cini is induced by cinr and repressed by ... | 2007 | 17600052 |