| diverse proteins homologous to inositol monophosphatase. | bovine inositol monophosphatase (imp) and several homologous proteins were found to share two sequence motifs with bovine inositol polyphosphate 1-phosphatase (ipp). these motifs may correspond to binding sites within imp and ipp for inositol phosphates or for lithium, since both substances are bound by these proteins. this suggests that the proteins homologous to imp, which have diverse biological roles but whose function is not clear, may act by enhancing the synthesis or degradation of phosph ... | 1991 | 1660408 |
| mapping of the ros virulence regulatory gene of a. tumefaciens. | virulence functions associated with the oncogenicity of agrobacterium tumefaciens are encoded by vir genes contained in six major operons located on the ti plasmid. the virc and vird operons encode functions responsible for host range and t-intermediate processing. these two operons are regulated positively by the product of virg and negatively by the product of the chromosomal gene ros, which encodes a 15.5 kda repressor. to determine the location of the ros gene we have constructed a. tumefaci ... | 1991 | 1660566 |
| transcriptional interference in transgenic plants. | when a promoterless marker gene is transformed into the plant genome using the agrobacterium vector system, on average 30% of the t-dna inserts produce gene fusions. this suggests that the t-dna is preferentially integrated into transcribed regions. here, we proposed that this transcriptional activity is responsible for some of the variation in expression frequently observed among independent transformants. using hybrid gene constructions, we show that transcriptional readthrough into a downstre ... | 1991 | 1662656 |
| the products of rhizobium genes, psi and pss, which affect exopolysaccharide production, are associated with the bacterial cell surface. | translational fusions between a mutant phoa (lacking its promoter, ribosomal binding site and signal peptide sequence) and rhizobium 'symbiotic' genes were isolated. since these fusions expressed alkaline phosphatase (ap), the product of phoa, the genes into which phoa was inserted apparently specify proteins located in the bacterial periplasm or cell membrane, the compartment in which ap has activity. these genes were psia and genes upstream of psia (psia is required for normal nodule developme ... | 1991 | 1662758 |
| genetic transformation of arabidopsis thaliana zygotic embryos and identification of critical parameters influencing transformation efficiency. | an efficient procedure for agrobacterium-mediated transformation of zygotic embryos derived from three different arabidopsis thaliana ecotypes has been developed. this procedure yielded an average transformation rate of 76% for ecotype c24, and 15-20% for ecotypes landsberg-erecta and columbia. a critical step for optimal transformation was the preculture of embryos on a phytohormone-containing medium. light and electron microscopical studies showed that, during preculture, procambium cells of e ... | 1991 | 1662767 |
| insect resistance of transgenic tobacco plants expressing delta-endotoxin gene of bacillus thuringiensis. | the initiative b.thuringiensis delta-endotoxin (bt toxin) gene clones th12 and th48 contain two different classes of homologous genes, the 5.3 kb class and 6.6 kb class, respectively. bt toxin genes of both classes, modified at the 5'-end and truncated at the 3'-end, can still be expressed to produce the insecticidal, truncated toxin proteins in e. coli. the modified bt toxin genes were inserted into the plant binary expression vector pbin 437 (a derivative plasmid of pbin 19) and were transferr ... | 1991 | 1663400 |
| characterization of three soluble c-type cytochromes isolated from soybean root nodule bacteroids of bradyrhizobium japonicum strain cc705. | three soluble, low molecular mass cytochromes c (mr 8000-15,000) were isolated and purified from soybean root nodule bacteroids of bradyrhizobium japonicum strain cc705. on the basis of their alpha: absorbance peaks in the reduced forms, they were named cytochromes c550, c552 and c555. cytochrome c552 reacted very fast, c555 very slowly and c550 not at all with carbon monoxide. the complete amino acid sequence (73 residues) of cytochrome c552 was established which identifies it as a monoheme, cl ... | 1991 | 1663887 |
| [obtaining transgenic solanum tuberosum potato plants with active bacterial genes xyl and t-cyt effecting the phytohormone balance]. | the genetic constructions based on integrative vector pgv3850 were used to introduce bacterial genes xyl and t-cyt into potato cells. the transformation was carried out using the leaf-disc method with modifications. a special system for obtaining regenerants from explants of potato in vitro plants or calli has been designed that permitted the selection of transgenic shoots. the presence of the genes in potato genome has been proved by testing the nptii and glucoisomerase activities. the transgen ... | 1991 | 1667027 |
| nucleotide sequence of rhizobium meliloti insertion sequence isrm1: homology to is2 from escherichia coli and is426 from agrobacterium tumefaciens. | nucleotide sequencing of rhizobium meliloti insertion sequence isrm1 showed that it is 1319 nucleotides long and includes 32/31 nucleotide terminal inverted repeats. analysis of five different insertion sites using sequencing primers complementary to sequences within the left and right ends demonstrated that isrm1 generates five bp direct repeats at the sites of insertion. although isrm1 has shown a target preference for certain short regions (hot spots), there was no apparent similarity in the ... | 1991 | 1667984 |
| a cultivar-specific interaction between rhizobium leguminosarum bv. trifolii and subterranean clover is controlled by nodm, other bacterial cultivar specificity genes, and a single recessive host gene. | insertion mutagenesis identified two negatively acting gene loci which restrict the ability of rhizobium leguminosarum bv. trifolii ta1 to infect the homologous host trifolium subterraneum cv. woogenellup. one locus was confirmed by dna sequence analysis as the nodm gene, while the other locus, designated csn-1 (cultivar-specific nodulation), is not located on the symbiosis plasmid. the presence of these cultivar specificity loci could be suppressed by the introduction of the nodt gene from anu8 ... | 1991 | 1673458 |
| polymorphism of nopaline-type t-dnas from agrobacterium tumefaciens. | the structure of several t-dnas of agrobacterium tumefaciens was determined by molecular cloning and southern hybridization. the t-dnas cloned in escherichia coli vectors from four different nopaline type strains (pyte1, po31, po22, and ake10) showed various sizes of restriction enzyme fragments. comparative analysis of the restriction maps revealed that the t-dnas were composed of three distinct structural domains: (1) the region proximal to the right border (domain i) containing the portion es ... | 1991 | 1674610 |
| studies of the bradyrhizobium japonicum nodd1 promoter: a repeated structure for the nod box. | induction of nod genes in rhizobium and bradyrhizobium species is dependent on the presence of plant-produced flavonoids, the nodd protein, and the cis-acting nod box promoter sequence. although the nodd (nodd1) gene in rhizobium species is constitutively expressed, nodd1 expression in bradyrhizobium japonicum is inducible by isoflavones in a manner similar to that of the nodyabc operon. a consensus nod box sequence is found 5' of the nodyabc operon, whereas a presumptive, nod box-like sequence ... | 1991 | 1675210 |
| a pyruvate-stimulated adenylate cyclase has a sequence related to the fes/fps oncogenes and to eukaryotic cyclases. | the pyruvate-stimulated adenylate cyclase from brevibacterium liquefaciens produces up to 450 microm cyclic amp in the culture medium when the bacterium is grown on glucose and alanine. in this paper we report the cloning, expression and sequencing of the gene for this enzyme. residues were identified, within the c-terminal domain, which are conserved in adenylate and guanylate cyclase sequences from eukaryotes and in the adenylate cyclase of the prokaryote rhizobium meliloti. we have also ident ... | 1991 | 1683468 |
| the early nodulin transcript enod2 is located in the nodule parenchyma (inner cortex) of pea and soybean root nodules. | a pea cdna clone homologous to the soybean early nodulin clone pgmenod2 that most probably encodes a cell wall protein was isolated. the derived amino acid sequence of the pea enod2 protein shows that it contains the same repeating pentapeptides, proprohisglulys and proproglutyrgln, as the soybean enod2 protein. by in situ hybridization the expression of the enod2 gene was shown to occur only in the inner cortex of the indeterminate pea nodule. the transcription of the pea enod2 gene starts when ... | 1990 | 1688528 |
| signal transduction pathway controlling synthesis of a class of degradative enzymes in bacillus subtilis: expression of the regulatory genes and analysis of mutations in degs and degu. | the rates of synthesis of a class of both secreted and intracellular degradative enzymes in bacillus subtilis are controlled by a signal transduction pathway defined by at least four regulatory genes: degs, degu, degq (formerly sacq), and degr (formerly prtr). the degs-degu proteins show amino acid similarities with two-component procaryotic modulator-effector pairs such as ntrb-ntrc, chea-chey, and envz-ompr. by analogy with these systems, it is possible that degs is a protein kinase which coul ... | 1990 | 1688843 |
| hypoosmotic adaptation in rhizobium meliloti requires beta-(1----2)-glucan. | beta-(1----2)-glucan, an unusual cyclic oligosaccharide, can be isolated from the periplasm of bacteria belonging to the family rhizobiaceae. data presented here suggest that the periplasmic beta-(1----2)-glucan of rhizobium meliloti plays a major role in osmotic adaptation. first, growth of r. meliloti in a low-osmolarity medium causes a large accumulation of periplasmic beta-(1----2)-glucan. second, mutations in the ndv genes, which prevent this accumulation of beta-(1----2)-glucan, reduce cel ... | 1990 | 1689716 |
| genetic structure of natural populations of the nitrogen-fixing bacterium rhizobium meliloti. | the genetic structure of populations of the symbiotic nitrogen-fixing soil bacterium rhizobium meliloti was examined by analysis of electrophoretically demonstrable allelic variation in 14 metabolic, presumably chromosomal, enzyme genes. a total of 232 strains were examined, most of which were isolated from southwest asia, where there is an unsurpassed number of indigenous host species for r. meliloti. the collection consisted of 115 isolates recovered from annual species of medicago in syria, t ... | 1990 | 1689982 |
| choline derivatives increase two different acid phosphatases in rhizobium meliloti and pseudomonas aeruginosa. | in pseudomonas aeruginosa and rhizobium meliloti several choline derivatives, utilized as the sole carbon and nitrogen source, increase acid phosphatase activity. the enzyme activity of both bacteria could be released into the surrounding medium by edta-lysozyme treatment. the r. meliloti acid phosphatase activity of crude periplasmic extracts measured with p-nitrophenylphosphate was not inhibited by the presence of 5 mm choline, betaine, trimethylammonium or phosphorylcholine. the activity coul ... | 1990 | 1695086 |
| production and epitope analysis of monoclonal antibodies against a rhizobium leguminosarum biovar trifolii strain. | heat-treated cells of rhizobium leguminosarum biovar trifolii strain 162x95 were used to produce monoclonal antibodies (mabs). the fusion produced three cross-reactive mabs and eight mabs specific for the immunizing strain and a group of five other r. trifolii strains from the same geographic region where 162x95 was isolated (california). seven mabs were analyzed by competitive enzyme-linked immunosorbent assay to determine the number of different epitopes detectable on strain 162x95. the result ... | 1990 | 1697150 |
| anti-sense rna efficiently inhibits formation of the 10 kd polypeptide of photosystem ii in transgenic potato plants: analysis of the role of the 10 kd protein. | a chimeric gene encoding an anti-sense rna of the 10 kd protein of the water-splitting apparatus of photosystem ii of higher plants under the control of the camv 35s promoter was introduced into potato using agrobacterium based vectors. the expression of the anti-sense rna led to a significant reduction of the amounts of the 10 kd protein and rna in a number of transgenic plants. in three out of 36 plants tested, the level of the 10 kd protein was only up to 1-3% compared with the wild-type cont ... | 1990 | 1697267 |
| cloning and sequence analysis of truncated t-dna inserts from nicotiana tabacum. | transgenic plants produced by agrobacterium-mediated transformation usually have one or a few stable and intact t-dna insertions. however, in a significant number of the transformants southern blot analysis has revealed the occurrence of aberrant t-dna insertions missing one or both ends. during the study of this phenomenon, we obtained kmr nicotiana tabacum clones after cocultivation with an agrobacterium strain containing a promoterless nptii gene located internally in the t-dna. expression of ... | 1990 | 1701747 |
| [system of transgenic plants and its application]. | | 1990 | 1702547 |
| genetic structure of a soil population of nonsymbiotic rhizobium leguminosarum. | the genetic structure of a population of nonsymbiotic rhizobium leguminosarum strains was determined by the electrophoretic mobilities of eight metabolic enzymes. nonsymbiotic strains were isolated from the rhizosphere of bean plants and characterized by growth on differential media and at different temperatures, intrinsic antibiotic resistance, the lack of homology to a nifh probe, and their inability to form nodules on bean roots. all the isolates clustered with r. leguminosarum bv. phaseoli r ... | 1991 | 1707606 |
| antigenic changes in lipopolysaccharide i of rhizobium leguminosarum bv. viciae in root nodules of vicia sativa subsp. nigra occur during release from infection threads. | three different monoclonal antibodies raised against the o antigen-containing lipopolysaccharide (lps i) of free-living cells were used in an immunocytochemical study to follow the fate of lps i on the outer membrane of rhizobium leguminosarum bv. viciae 248 during the nodulation of vicia sativa subsp. nigra. after immunogold labeling, the lps i epitopes were detected on the outer membrane of bacteria present in infection threads throughout the nodule. epitopes were not detectable on bacteria re ... | 1991 | 1708764 |
| the exor gene of rhizobium meliloti affects rna levels of other exo genes but lacks homology to known transcriptional regulators. | rhizobium meliloti strains mutant in the exor gene overproduce an exopolysaccharide called succinoglycan or eps i. protein fusions to several different exo genes required for eps i biosynthesis are expressed at a higher level in an exor strain than in a wild-type strain, showing that the overproduction of eps i in exor strains results at least in part from increased gene expression. this regulation is important to nodulation, since exor mutants fail to invade alfalfa nodules unless secondary sup ... | 1991 | 1711027 |
| phylogenetic analysis and evolution of rnase p rna in proteobacteria. | the secondary structures of the eubacterial rnase p rnas are being elucidated by a phylogenetic comparative approach. sequences of genes encoding rnase p rna from each of the recognized subgroups (alpha, beta, gamma, and delta) of the proteobacteria have now been determined. these sequences allow the refinement, to nearly the base pair level, of the phylogenetic model for rnase p rna secondary structure. evolutionary change among the rnase p rnas was found to occur primarily in four discrete str ... | 1991 | 1711030 |
| suppression of nodulation gene expression in bacteroids of rhizobium leguminosarum biovar viciae. | the expression of nod genes of rhizobium leguminosarum bv. viciae in nodules of pisum sativum was investigated at both the translational and transcriptional levels. by using immunoblots, it was found that the levels of noda, nodi, node, and nodo proteins were reduced at least 14-fold in bacteriods compared with cultured cells, whereas nodd protein was reduced only 3-fold. northern (rna) blot hybridization, rnase protection assays, and in situ rna hybridization together showed that, except for th ... | 1991 | 1712355 |
| transgenic rice cell lines and plants: expression of transferred chimeric genes. | cell suspension-derived rice (oryza sativa l.) protoplasts were transformed by direct gene uptake. peg-mediated transformation was more efficient than electroporation. plasmid dna containing a hygromycin phosphotransferase (hpt) gene (which confers hygromycin resistance) driven by the camv 35s promoter and a beta-d-glucuronidase (gus) gene under control of the 1', 2' double promoter of the mannopine synthase (mas) locus of agrobacterium tumefaciens was introduced into rice protoplasts. southern ... | 1991 | 1713479 |
| cross-talk between the virulence and phosphate regulons of agrobacterium tumefaciens caused by an unusual interaction of the transcriptional activator with a regulatory dna element. | transcription of a virulence gene on the hairy-root-inducing plasmid a4, which is induced by plant factors in agrobacterium tumefaciens, was also activated by phosphate limitation in both a. tumefaciens and escherichia coli. the starting site of rna synthesized under the two inducing conditions was the same, and an identical promoter was responsible for both inducible expressions. the response of the virulence gene to phosphate limitation did not require the positive regulator virg for the virul ... | 1991 | 1714035 |
| an altered constitutive peptide in sym 5 mutants of pisum sativum l. | mutational analysis of pisum sativum l. was used to search for constitutive proteins that might function in nodule formation. the sym 5 locus is a mutational hot spot, represented by seven independently derived mutant lines with decreased nodulation. comparison of two-dimensional polyacrylamide gels of in vitro-translated root rna showed a consistent difference in the migrational pattern of one peptide. in the nodulating parental cultivar 'sparkle', a 66 kda peptide had a pi of 5.9. in four of t ... | 1990 | 1714314 |
| integration and expression of a rabbit liver cytochrome p-450 gene in transgenic nicotiana tabacum. | cytochrome p-450 is involved in the oxidative metabolism of a broad range of substrates. we have made a chimeric construct, psn002, containing the cdna for rabbit liver cytochrome p-450 (iic14) under the control of the tr2' promoter for mannopine synthase in the agrobacterium ti plasmid. nicotiana tabacum was transformed with agrobacterium tumefaciens harboring a cointegrated plasmid psn002::pgv2260. the presence of mrna and of the translated protein from the chimeric cytochrome p-450 gene in tr ... | 1991 | 1714583 |
| rhizobium tropici, a novel species nodulating phaseolus vulgaris l. beans and leucaena sp. trees. | a new rhizobium species that nodulates phaseolus vulgaris l. and leucaena spp. is proposed on the basis of the results of multilocus enzyme electrophoresis, dna-dna hybridization, an analysis of ribosomal dna organization, a sequence analysis of 16s rdna, and an analysis of phenotypic characteristics. this taxon, rhizobium tropici sp. nov., was previously named rhizobium leguminosarum biovar phaseoli (type ii strains) and was recognized by its host range (which includes leucaena spp.) and nif ge ... | 1991 | 1715738 |
| characterization of the pea enod12b gene and expression analyses of the two enod12 genes in nodule, stem and flower tissue. | the enod12 gene family in pea consists of two different members. the cdna clone, ppsenod12, represents the psenod12a gene. the second enod12 gene, psenod12b, was selected from a genomic library using ppsenod12 as a probe and this gene was sequenced and characterized. the coding regions of the two genes are strikingly similar. both encode proteins having a signal peptide sequence and a region with pentapeptide units rich in prolines. enod12a has a series of rather conserved repeating pentapeptide ... | 1991 | 1715970 |
| 'phytoantibodies': a general vector for the expression of immunoglobulin domains in transgenic plants. | sequences encoding the immunoglobulin heavy-chain variable (vh) domains were engineered in a new general purpose vector to transform plants via agrobacterium. the expression of an isolated vh domain (ivd) after introduction into the plant genome has been monitored by northern, western and immunohistochemical analysis. immunoblotting showed that the polypeptide was stably expressed and accounted for up to 1% of the soluble protein fraction. it is therefore proposed that single immunoglobulin doma ... | 1991 | 1717050 |
| discovery of a rhizobial rna that is essential for symbiotic root nodule development. | all of the azorhizobium, bradyrhizobium, and rhizobium genes known to be involved in the development of nitrogen-fixing legume root nodules are genes that code for proteins. here we report the first exception to this rule: the sra gene; it was discovered during the genetic analysis of a bradyrhizobium japonicum tn5 mutant (strain 259) which had a severe deficiency in colonizing soybean nodules. a dna region as small as 0.56 kb cloned from the parental wild type restored a wild-type phenotype in ... | 1991 | 1717438 |
| is406 and is407, two gene-activating insertion sequences for pseudomonas cepacia. | we have determined the nucleotide sequences of is406 (1368 bp) and is407 (1236 bp), two insertion sequence (is) elements isolated from pseudomonas cepacia 249 on the basis of their abilities to activate the expression of the lac genes of tn951. is406 and is407 when inserted into the lac promoter/operator region of tn951 generated, respectively, duplications of 8 and 4 bp of target dna. is406 had 41-bp terminal inverted repeat (ir) sequences with eleven mismatches. ir-l (left) contained a 12-bp m ... | 1991 | 1718819 |
| the oac gene encoding a lipopolysaccharide o-antigen acetylase maps adjacent to the integrase-encoding gene on the genome of shigella flexneri bacteriophage sf6. | lysogens of shigella flexneri harbouring the temperate bacteriophage, sf6, have been previously shown to undergo a serotype conversion due to o-acetylation of the o-antigen of the lipopolysaccharide. a partial physical map of the phage genome has been constructed. analysis of the phage dna suggests that the phage packages by a headful mechanism and that the mature dna molecules are terminally redundant. cloning of the psti fragments of sf6 enabled the region encoding the serotype conversion to b ... | 1991 | 1720755 |
| site-directed mutagenesis and dna sequence of pcka of rhizobium ngr234, encoding phosphoenolpyruvate carboxykinase: gluconeogenesis and host-dependent symbiotic phenotype. | we have cloned and sequenced the pcka gene of rhizobium sp. ngr234, a broad host-range strain. the gene encodes phosphoenolpyruvate carboxykinase (pepck), a key enzyme of gluconeogenesis. the locus was isolated and subcloned from a genomic library of ngr234 employing hybridization with an r. meliloti pck gene probe and complementation of a tn5 mutant in this species. the dna sequence of pcka (ngr234) was determined and encoded a pepck protein of 535 amino acids with a molecular weight of 58.4 kd ... | 1991 | 1720862 |
| biological activity of rhizobial siderophore. | non-nodulating mutant of rhizobium leguminosarum biovar trifolli produces the phenolate type of siderophore consisting of 2,3-dihydroxybenzoic acid and threonine. the activity of this compound against the various bacteria was tested. only, the growth of r. leguminosarum strains was stimulated by siderophore. the other species of rhizobium, especially r. meliloti, were sensitive to this agent. the growth of r. meliloti was also inhibited by agrobactin and pseudobactin. this effect was reversed by ... | 1991 | 1726625 |
| distribution of an l-isoaspartyl protein methyltransferase in eubacteria. | a protein carboxyl methyltransferase (ec 2.1.1.77) that recognizes age-damaged proteins for potential repair or degradation reactions has been found in all vertebrate tissues and cells examined to date. this enzyme catalyzes the transfer of methyl groups from s-adenosylmethionine to the carboxyl groups of d-aspartyl or l-isoaspartyl residues that are formed spontaneously from normal l-aspartyl and l-asparaginyl residues. a similar methyltransferase has been found in two bacterial species, escher ... | 1992 | 1729230 |
| rhizobium meliloti produces a family of sulfated lipooligosaccharides exhibiting different degrees of plant host specificity. | we have shown that a rhizobium meliloti strain overexpressing nodulation genes excreted high amounts of a family of n-acylated and 6-o-sulfated n-acetyl-beta-1,4-d-glucosamine penta-, tetra-, and trisaccharide nod factors. either a c(16:2) or a c(16:3) acyl chain is attached to the nonreducing end subunit, whereas the sulfate group is bound to the reducing glucosamine. one of the tetrasaccharides is identical to the previously described nodrm-1 factor. the two pentasaccharides as well as nodrm-1 ... | 1992 | 1729688 |
| opine catabolism and conjugal transfer of the nopaline ti plasmid ptic58 are coordinately regulated by a single repressor. | the ti plasmids of agrobacterium tumefaciens are conjugal elements whose transfer is strongly repressed. transfer is induced by the conjugal opines, a group of unique carbon compounds synthesized in crown gall tumors. the opines also induce ti plasmid-encoded genes required by the bacteria for opine catabolism. we have cloned and sequenced a gene from the ti plasmid ptic58, whose product mediates the opine-dependent regulation of conjugal transfer and catabolism of the conjugal opines, agrocinop ... | 1992 | 1731335 |
| the vird2 protein of a. tumefaciens contains a c-terminal bipartite nuclear localization signal: implications for nuclear uptake of dna in plant cells. | here we show that the vird2 protein of a. tumefaciens functions as a nuclear localizing protein in plant cells. the nuclear localization signal of vird2 consists of two regions containing 4-5 basic amino acids (krpr and rkrer), located within the c-terminal 34 amino acids. these regions conform to the kr/kxr/k motif required for numerous nuclear localized nonplant eukaryotic proteins. each region independently directs a beta-glucuronidase reporter protein to the nucleus; however, both regions ar ... | 1992 | 1732061 |
| opine transport genes in the octopine (occ) and nopaline (noc) catabolic regions in ti plasmids of agrobacterium tumefaciens. | the occ and noc regions of octopine and nopaline ti plasmids in agrobacterium tumefaciens are responsible for the catabolic utilization of octopine and nopaline, respectively. opine-inducible promoters, genes for regulatory proteins and for catabolic enzymes, had been identified in previous work. however, both regions contained additional dna stretches which were under the control of opine-inducible promoters, but the functions were unknown. we investigated these stretches by dna sequence and fu ... | 1992 | 1732218 |
| characterization of the agrobacterium tumefaciens heat shock response: evidence for a sigma 32-like sigma factor. | we have characterized the heat shock response of agrobacterium tumefaciens and compared it with the well-characterized escherichia coli heat shock response. four major heat shock proteins with apparent molecular masses of 98, 75, 65, and 20 kda were identified by pulse-labelling cultures after temperature upshift. the three largest proteins comigrated with proteins that were antigenically related to the e. coli heat shock proteins sigma 70, dnak, and groel, respectively. the heat shock proteins ... | 1992 | 1732231 |
| mutation of the miaa gene of agrobacterium tumefaciens results in reduced vir gene expression. | vir regulon expression in agrobacterium tumefaciens involves both chromosome- and ti-plasmid-encoded gene products. we have isolated and characterized a new chromosomal gene that when mutated results in a 2- to 10-fold reduction in the induced expression of vir genes by acetosyringone. this reduced expression occurs in ab minimal medium (ph 5.5) containing either sucrose or glucose and containing phosphate at high or low concentrations. the locus was cloned and used to complement a. tumefaciens ... | 1992 | 1735704 |
| a self-transmissible, narrow-host-range endogenous plasmid of rhodobacter sphaeroides 2.4.1: physical structure, incompatibility determinants, origin of replication, and transfer functions. | rhodobacter sphaeroides 2.4.1 naturally harbors five cryptic endogenous plasmids (c. s. fornari, m. watkins, and s. kaplan, plasmid 11:39-47, 1984). the smallest plasmid (prs241e), with a molecular size of 42 kb, was observed to be a self-transmissible plasmid which can transfer only to certain strains of r. sphaeroides. transfer frequencies can be as high as 10(-2) to 10(-3) per donor under optimal mating conditions in liquid media in the absence of oxygen. prs241e, designated the s factor, was ... | 1992 | 1735707 |
| the agrobacterium tumefaciens vir gene transcriptional activator virg is transcriptionally induced by acid ph and other stress stimuli. | a set of agrobacterium tumefaciens operons required for pathogenesis is coordinately induced during plant infection by the vira and virg proteins. the intracellular concentration of virg increases in response to acidic media, and this response was proposed to be regulated at the level of transcription at a promoter (p2) that resembles the escherichia coli heat shock promoters. to test this hypothesis, we first constructed a virg-lacz transcriptional fusion. a strain containing this fusion had hi ... | 1992 | 1735712 |
| the central domain of rhizobium leguminosarum dctd functions independently to activate transcription. | sigma 54-dependent transcriptional activators such as escherichia coli ntrc, rhizobium meliloti nifa, and rhizobium leguminosarum dctd share similar central and carboxy-terminal domains but differ in the structure and function of their amino-terminal domains. we have deleted the amino-terminal and carboxy-terminal domains of r. leguminosarum dctd and have demonstrated that the central domain of dctd, like that of nifa, is transcriptionally competent. | 1992 | 1735730 |
| plant genetic control of nodulation. | | 1991 | 1741618 |
| the product of the rhizobium meliloti ilvc gene is required for isoleucine and valine synthesis and nodulation of alfalfa. | tn5-induced mutants of rhizobium meliloti that require the amino acids isoleucine and valine for growth on minimal medium were studied. in one mutant, 1028, the defect is associated with an inability to induce nodules on alfalfa. the tn5 mutation in 1028 is located in a chromosomal 5.5-kb ecori fragment. complementation analysis with cloned dna indicated that 2.0 kb of dna from the 5.5-kb ecori fragment restored the wild-type phenotype in the ilv- nod- mutant. this region was further characteriz ... | 1991 | 1744032 |
| characterization of the supervirulent virg gene of the agrobacterium tumefaciens plasmid ptibo542. | the virg gene of the agrobacterium tumefaciens ti plasmid ptibo542 has previously been reported to elicit stronger vir gene expression than its counterpart in the ptia6 plasmid, a property we call the "superactivator" phenotype. the dna sequence of the ptibo542 virg gene was determined and compared to that of the ptia6 gene. the dna sequences of these genes differ at 16 positions: two differences are in the promoter regions, 12 are in the coding regions, and two are in the 3' untranslated region ... | 1991 | 1745238 |
| expression and quantification of firefly luciferase under control of rhizobium meliloti symbiotic promoters. | we have tested the use of firefly luciferase for monitoring regulated symbiotic nitrogen fixation gene expression. broad-host-range plasmids carrying translational fusions of rhizobium meliloti nifh, fixa and nifa promoters were constructed. despite low levels of promoter activity the absence of escherichia coli endogenous luminescence and the high sensitivity of the bioluminescent assay for firefly luciferase allowed rapid screening for functional luciferase expression. plasmids containing symb ... | 1991 | 1746317 |
| acidic conditions permit effective nodulation of alfalfa by invasion-deficient rhizobium meliloti exod mutants. | rhizobium meliloti exod mutants are deficient in invasion of alfalfa nodules and, as a consequence, the nodules that exod strains induce fail to fix nitrogen. these nodules appear to be arrested at the same stage as nodules induced by other exo mutants, which do not make an acidic exopolysaccharide called eps i, or by ndv mutants, which do not produce a periplasmic cyclic beta(1,2) glucan. however previous genetic and biochemical evidence suggested that the nodule invasion defect of exod mutants ... | 1991 | 1748284 |
| expression of the gene encoding the coat protein of cucumber mosaic virus (cmv) strain wl appears to provide protection to tobacco plants against infection by several different cmv strains. | the gene (cp) encoding the coat protein (cp) of cucumber mosaic virus (cmv) strain wl (cmv-wl, which belongs to cmv subgroup ii) was custom polymerase chain reaction (cpcr)-engineered for expression as described by slightom [gene 100 (1991) 251-255]. cpcr amplification was used to add 5'- and 3'-flanking ncoi sites to the cmv-wl cp gene, and cp was cloned into the expression vector, puc18cpexp. this cmv-wl cp expression cassette was transferred into the genome of tobacco (nicotiana tabacum cv. h ... | 1991 | 1748291 |
| t-dna gene 5 of agrobacterium modulates auxin response by autoregulated synthesis of a growth hormone antagonist in plants. | oncogenes carried by the transferred dna (t-dna) of agrobacterium ti plasmids encode the synthesis of plant growth factors, auxin and cytokinin, and induce tumour development in plants. other t-dna genes regulate the tumorous growth in ways that are not yet understood. to determine the function of t-dna gene 5, its coding region was expressed in escherichia coli. synthesis of the gene 5 encoded protein (26 kda) correlated with a 28-fold increase in conversion of tryptophan to indole-3-lactate (i ... | 1991 | 1756712 |
| molecular basis of symbiotic host specificity in rhizobium meliloti: nodh and nodpq genes encode the sulfation of lipo-oligosaccharide signals. | the symbiosis between rhizobium and legumes is highly specific. for example, r. meliloti elicits the formation of root nodules on alfalfa and not on vetch. we recently reported that r. meliloti nodulation (nod) genes determine the production of acylated and sulfated glucosamine oligosaccharide signals. we now show that the biochemical function of the major host-range genes, nodh and nodpq, is to specify the 6-o-sulfation of the reducing terminal glucosamine. purified nod factors (sulfated or not ... | 1991 | 1760841 |
| a novel strategy for production of a highly expressed recombinant protein in an active form. | under standard growth conditions, e. coli transformed with the high-level expression vector pmon5525 produces recombinant dmapp/amp transferase in inactive, insoluble complexes. we have produced large amounts of active, soluble protein by growing and inducing the cells under osmotic stress in the presence of sorbitol and glycyl betaine. this caused an increase of up to 427-fold in the active yield, and the disappearance of the protein from the pelletable fraction of cell extracts. this treatment ... | 1991 | 1765138 |
| nodules elicited by rhizobium meliloti heme mutants are arrested at an early stage of development. | heme-deficient mutants of rhizobium and bradyrhizobium have been found to exhibit diverse phenotypes with respect to symbiotic interactions with plant hosts. we observed that r. meliloti hema mutants elicit nodules that do not contain intracellular bacteria; the nodules contain either no infection threads ("empty" nodule phenotype) or aberrant infection threads that failed to release bacteria (bar- phenotype). these mutant nodules expressed nodulin genes associated with nodules arrested at an ea ... | 1991 | 1766439 |
| autoregulatory response of phaseolus vulgaris l. to symbiotic mutants of rhizobium leguminosarum bv. phaseoli. | in rhizobium-legume symbiosis, the plant host controls and optimizes the nodulation process by autoregulation. tn5 mutants of rhizobium leguminosarum bv. phaseoli tal 182 which are impaired at various stages of symbiotic development, were used to examine autoregulation in the common bean (phaseolus vulgaris l.). class i mutants were nonnodulating, class ii mutants induced small, distinct swellings on the roots, and a class iii mutant formed pink, bacterium-containing, but ineffective nodules. a ... | 1991 | 1768143 |
| do rhizobia produce cytokinins? | two rhizobium strains were cultured on a defined medium; one was a normal strain of the cowpea group (anu240) while the other (ic3342) was an unusual but related strain of the same group which induced abnormal shoot development, including proliferation of lateral buds, in nodulated plants. culture supernatants were examined for the presence of cytokinins by mass spectrometry using deuterium-labelled internal standards and by radioimmunoassay. in culture supernatants of both strains a range of cy ... | 1991 | 1768251 |
| agrobacterium mediated genetic transformation of chickpea, cicer arietinum l. | in leaf and stem explants of chickpea, wild type strains of agrobacteria were able to induce tumors. these tumors were capable of phytohormone independent growth. a supervirulent strain a281 was found to be most effective. thus, using an agrobacterium r1601, which carries genes conferring supervirulent phenotype along with a plant selectable marker gene (npt ii), transformed calli of chickpea were selected in the presence of 100 micrograms/ml level of kanamycin. molecular analyses of genomic dna ... | 1991 | 1769719 |
| swimming against the tide: chemotaxis in agrobacterium. | chemotaxis in bacteria is an excellent model for signal transduction processes. in agrobacterium tumefaciens, the causative agent of crown gall tumour on wounded plants, it is a vital part of the organism's biology. a chromosomally-determined chemotaxis system causes the bacterium to be attracted into the rhizosphere by chemoattractants in plant exudates. by interfacing with this system, the multifunctional products of two ti-plasmid encoded genes, vira and virg, allow the sensing of specific wo ... | 1991 | 1772407 |
| transduction of plant signal molecules by the rhizobium nodd proteins. | the regulatory nodd proteins of rhizobium bacteria mediate the activation of a gene set responsible for symbiotic nodule formation by plant signal molecules. here we discuss the signal recognition and gene activation properties of nodd and present a model summarizing the current knowledge on nodd action. | 1991 | 1772413 |
| identification of a nifa-like regulatory gene of azospirillum brasilense sp7 expressed under conditions of nitrogen fixation and in the presence of air and ammonia. | a gene bank of azospirillum lipoferum br17 constructed in the vector lambda gem11 was screened with a bradyrhizobium japonicum nifa gene probe. a 7.3 kb ecori fragment carrying a nifa-like gene was thereby isolated and subsequently used to screen a gene bank of azospirillum brasilense sp7 constructed in puc18. two ecori fragments of 5.6 kb and 3.6 kb covering the nifa-homology region were found. mutants with nif- phenotype were obtained by site-directed tn5 mutagenesis of the 5.6 kb fragment and ... | 1991 | 1779763 |
| rhizobium meliloti exopolysaccharides: genetic analyses and symbiotic importance. | genetic experiments have indicated that succinoglycan (eps i), the acidic calcofluor-binding exopolysaccharide, of the nitrogen-fixing bacterium rhizobium meliloti strain rm1021 is required for nodule invasion and possibly for later events in nodule development on alfalfa and other hosts. fourteen exo loci on the second megaplasmid have been identified that are required for, or affect, the synthesis of eps i. mutations in certain of these loci completely abolish the production of eps i and resul ... | 1991 | 1783190 |
| plant cell culture in the production of flavour compounds. | | 1991 | 1783202 |
| the rhizobium meliloti exozl exob fragment of megaplasmid 2: exob functions as a udp-glucose 4-epimerase and exoz shows homology to nodx of rhizobium leguminosarum biovar viciae strain tom. | a 2.6 kb clai-bamhi dna fragment of megaplasmid 2 of rhizobium meliloti 2011 was found to carry genes involved in exopolysaccharide synthesis and infection of alfalfa nodules. the analysis of the nucleotide sequence of this dna fragment revealed the existence of two open reading frames (orfs) running in opposite directions. plasmid integration mutagenesis showed that these orfs are organized as two monocistronic transcription units. one of the orfs represents a new exo gene designated exoz, whic ... | 1991 | 1787800 |
| an agrobacterium two-component regulatory system for the detection of chemicals released from plant wounds. | crown gall tumorigenesis by agrobacterium tumefaciens requires the co-ordinate transcriptional induction of a set of pathogenesis genes. at least three classes of environmental stimuli act synergistically to induce these genes: (i) monocyclic aromatic hydrocarbons such as acetosyringone, coniferyl alcohol, and vanillin, (ii) neutral or acidic monosaccharides such as glucose and glucuronic acid, and (iii) acidic ph. three proteins are required to sense and respond to these stimuli: (i) vira, a tr ... | 1991 | 1791750 |
| microbial metabolism of quinoline and related compounds. xi. degradation of quinoline-4-carboxylic acid by microbacterium sp. h2, agrobacterium sp. 1b and pimelobacter simplex 4b and 5b. | from soil enrichment cultures four strains, using quinoline-4-carboxylic acid as sole source of energy and carbon, have been isolated. according to their physiological properties these bacteria have been identified as microbacterium sp. designated h2, as agrobacterium sp. designated 1b and pimelobacter simplex designated 4b and 5b. metabolites of the degradation pathway of quinoline-4-carboxylic acid have been isolated and identified. with pimelobacter simplex 4b and 5b 2-oxo-1,2-dihydroquinolin ... | 1991 | 1793516 |
| positive regulators of opine-inducible promoters in the nopaline and octopine catabolism regions of ti plasmids. | the noc and occ regions of nopaline and octopine ti plasmids in agrobacterium tumefaciens contain genes for the catabolism of nopaline and octopine, respectively. we investigated the transcriptional organization and regulation of both regions. the noc region of ptic58 contains two nopaline-inducible promoters, and one octopine-inducible promoter was identified in the occ region of ptiach5. all three promoters are positively regulated in trans by constitutively expressed genes localized at the ri ... | 1991 | 1799698 |
| transcription of the octopine catabolism operon of the agrobacterium tumor-inducing plasmid ptia6 is activated by a lysr-type regulatory protein. | agrobacterium tumefaciens incites crown gall tumors on plant hosts by conjugally transferring a discrete fragment of oncogenic dna. in addition to oncogenes, the transferred dna contains genes that direct the synthesis and exudation of opines, which are used as nutrients by the bacteria. the bacterium contains one or more operons of ti plasmid-encoded genes that are required for the internalization and utilization of opines, and transcription of these catabolic genes is induced by cognate opines ... | 1991 | 1799699 |
| mutants of the agrobacterium tumefaciens vira gene exhibiting acetosyringone-independent expression of the vir regulon. | hydroxylamine-induced mutations in the vira gene of agrobacterium tumefaciens that do not require the plant phenolic-inducing compound acetosyringone for vir regulon induction were isolated. the isolation was based on the activation of both virb::lacz and vire::cat fusions by mutant vira loci in the absence of acetosyringone. three of these vira(ais) (acetosyringone-independent signaling) mutants were characterized. all three mutants expressed a virb::lacz fusion at high levels in the absence of ... | 1991 | 1799700 |
| sequence and analysis of the nodabc region of rhizobium fredii usda257, a nitrogen-fixing symbiont of soybean and other legumes. | we cloned and analyzed nodabc from rhizobium fredii usda257. these genes are thought to have common functions in initiation of nitrogen-fixing nodules by all rhizobia. in usda257, they were located in a 9.2-kb ecori fragment that was not closely linked to either of two copies of the regulatory gene, nodd. nodabc was present in a 3,094-base pair (bp) sequenced region, which also included a consensus nod-box promoter. the three open reading frames contained 654, 642, and 1,239 bp, respectively, an ... | 1991 | 1799701 |
| repetitive sequences with homology to bradyrhizobium japonicum dna and the t-dna of agrobacterium rhizogenes are closely linked to nodabc of rhizobium fredii usda257. | we have detected strong homology between a 9.2-kb ecori restriction fragment from rhizobium fredii usda257 that contains nodabc and eight additional ecori fragments in dna digests from this organism. a series of repetitive sequences responsible for this hybridization lies within a 0.95-kb hindiii/sali subfragment about 1-kb upstream of noda. this subfragment also hybridizes to multiple restriction fragments from nine other strains of r. fredii, but only one is common to all strains. the 0.95-kb ... | 1991 | 1799702 |
| 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 |
| expression of rhizobium galegae common nod clones in various backgrounds. | the cosmid clone prg30, carrying common nodulation genes of rhizobium galegae hambi 1174, and prg33, a subclone of prg30 that contains a 5.7-kb clai insert carrying noddabc were conjugated into various rhizobium nod- mutant strains and into a ti plasmid-cured agrobacterium tumefaciens. complementation and expression of the nodabc genes of r. galegae were studied by following microscopically the infection process and the nodulation on different test plants. the nodabc genes of r. galegae compleme ... | 1991 | 1804401 |
| betaine use by rhizosphere bacteria: genes essential for trigonelline, stachydrine, and carnitine catabolism in rhizobium meliloti are located on psym in the symbiotic region. | rhizobium meliloti is known to use betaines synthesized by its host, medicago sativa, as osmoprotectants and sources of energy. it is shown in the present report that the symbiotic megaplasmid (psym) of r. meliloti rcr2011 encodes functions essential to the catabolism of three betaines, trigonelline (nicotinic acid n-methylbetaine), stachydrine (proline betaine or dimethylproline), and carnitine (gamma-trimethyl-beta-hydroxybutyrobetaine). preliminary evidence is presented showing that functions ... | 1991 | 1804402 |
| identification of 3-deoxy-lyxo-2-heptulosaric acid in the core region of lipopolysaccharides from rhizobiaceae. | a 3-deoxy-2-heptulosaric acid (dha), very probably with the lyxo-configuration, was identified in the r-core region of lipopolysaccharides from nodulating strains of rhizobium leguminosarum, rhizobium meliloti and from all three biovars of the phytopathogenic agrobacterium tumefaciens. its structure could be deduced from the fragmentation pattern of the corresponding alditol acetates obtained after reduction of the 2-keto and the 1.7-carboxy groups by sodium borohydride or sodium borodeuteride. ... | 1991 | 1804765 |
| synergistic action of phenolic signal compounds and carbohydrates in the induction of virulence gene expression of agrobacterium tumefaciens. | virulence (vir) gene expression of agrobacterium tumefaciens is activated by plant phenolic compounds such as alpha-hydroxyacetosyringone (hoas), acetosyringone (as), methyl syringate, coniferyl alcohol and sinapyl alcohol. inositol was found to be a potentiating factor of vir-inducing activity, which enhanced the vir-inducing activity of as and hoas in a synergistic manner, in particular at a low concentrations of as and hoas. of the other sugars tested d-glucose, l-rhamnose, d-xylose and d-gal ... | 1991 | 1806280 |
| application of a metabolic balancing technique to the analysis of microbial fermentation data. | a general method for the development of fermentation models, based on elemental and metabolic balances, is illustrated with three examples from the literature. physiological parameters such as the (maximal) yield on atp, the energetic maintenance coefficient, the p/o ratio and others are estimated by fitting model equations to experimental data. further, phenomenological relations concerning kinetics of product formation and limiting enzyme activities are assessed. the results are compared with ... | 1991 | 1807198 |
| rhizobium meliloti exopolysaccharides. structures, genetic analyses, and symbiotic roles. | | 1991 | 1809206 |
| development of the legume root nodule. | | 1991 | 1809347 |
| involvement of the syrm and nodd3 genes of rhizobium meliloti in nod gene activation and in optimal nodulation of the plant host. | we identified and sequenced the regulatory syrm and nodd3 genes of rhizobium meliloti 41. both genes were shown to contribute to optimal nodulation of alfalfa. in r. meliloti strains carrying syrm and nodd3 on plasmid, the nod genes are expressed constitutively, resulting in host-range extension to siratro. this is due to the presence of multiple syrm copies, suggesting that syrm participates directly in nod gene activation. nodd3 activates nod genes in conjunction with flavonoids and enhances s ... | 1991 | 1809842 |
| re-examination of the structures of the lipopolysaccharide core oligosaccharides from rhizobium leguminosarum biovar phaseoli. | | 1991 | 1811857 |
| [pea (pisum sativum) genes participating in symbiosis with nitrogen-fixing bacteria. ii. nucleotide sequence of cdna and parts of the late nodulin-6 (psnod6) gene]. | certain characteristics of late noduline gene from pea-nod6 were investigated as part of works of characterization of higher plant genes taking part in symbiotic nitrogen fixation. the complete 450 b.p. long cdna was sequenced, it's coding sequence includes the open reading frame. the part of dna containing the corresponding gene from the genomic clone was also sequenced. the predicted nod6 amino acid sequence has been analyzed and do not reveal the significant homology with any known protein. | 1991 | 1813810 |
| the region for exopolysaccharide synthesis in rhizobium leguminosarum biovar trifolii is located on the non-symbiotic plasmid. | an exo- mutant of rhizobium leguminosarum biovar trifolii was isolated which did not produce acidic exopolysaccharide and induced defective, non-fixing nodules on clover plants. the nodules were defective at a late stage of development, they contained infection threads and bacteria were released into the host cells. cosmid parf136 capable of complementing the exo- mutation was isolated from a cosmid bank made from total r. trifolii dna. hybridization between dna of parf136 and plasmids of r. tri ... | 1991 | 1814135 |
| interaction of t-dna border sequences and ti-plasmid vir functions of agrobacterium results in differential single-stranded linear t-dna molecule production and plant transformation. | the mechanism of agrobacterium mediated genetic transformation of plants is dependent upon certain genetic function of the chromosome of the bacterium as well as on ti-plasmid borne vir loci and the border sequences of t-dna. the organisationally variable forms of the naturally occurring border sequences amongst ti-plasmid types are differentially responsive to gene products of vir loci concerned with t-strand production. additionally, the production of stable transformants is dependent upon vir ... | 1991 | 1816090 |
| [the role of phytoalexins in natural plant resistance]. | | 1991 | 1819793 |
| characterization of an agrobacterium tumefaciens lectin. | an agrobacterium tumefaciens suspension induces a strong agglutination of aldehyde-fixed pig erythrocytes at ph 5.0. the agglutination is inhibited by some polysaccharides, such as fucoidin, and also when the ph is raised to 7.0. lectins (sugar-binding proteins) associated with the bacterial cell wall of a. tumefaciens strain 84.5 were directly evidenced by spectrofluorimetry using fluoresceinylated neoglycoproteins. the specific binding of the fluorescein-labelled neoglycoprotein bearing alpha- ... | 1991 | 1822244 |
| production of tsr factor by rhizobium meliloti. | the root exudates of alfalfa (medicago sativa) and mungbean (vigna radiata) induced the tsr (thick and short roots) factor production in rhizobium meliloti. the factor caused a 30-40% reduction of root length in alfalfa seedlings. pea root exudate had no tsr induction activity. the flavonoid naringenin could replace the roots in inducing tsr production. naringenin-induced tsr factor caused 70% shortening of main roots. the tsr inducing property of naringenin was specific since quercetin and syri ... | 1991 | 1823653 |
| a novel membrane-bound glucosyltransferase from bradyrhizobium japonicum. | bacteria within the family rhizobiaceae are distinguished by their ability to infect higher plants. the cell envelope carbohydrates of these bacteria are believed to be involved in the plant infection process. one class of cell envelope carbohydrate, the cyclic beta-1,2-glucans, is synthesized by species within two genera of this family, agrobacterium and rhizobium. in contrast, species of the genus bradyrhizobium, a third genus within this family, appear to lack the capacity for cyclic beta-1,2 ... | 1991 | 1829727 |
| [establishing the substrate specificity of site-specific deoxyribonuclease rtri]. | | 1991 | 1830740 |
| the osa gene of psa encodes a 21.1-kilodalton protein that suppresses agrobacterium tumefaciens oncogenicity. | the incompatibility group w plasmid psa suppresses agrobacterium tumefaciens oncogenicity (j. loper and c. kado, j. bacteriol. 139:591-596, 1979). the oncogenic suppressive activity was localized to a 3.1-kb region of psa by tn5 mutagenesis and deletion analysis. within this fragment, a 1.1-kb subclone bearing oncogenic suppressive activity was subjected to further characterization. nucleotide sequencing of the 1.1-kb fragment revealed a 570-bp open reading frame (orf1) that has a coding capacit ... | 1991 | 1832152 |
| molecular cloning and nucleotide sequence of the rhizobium phaseoli reca gene. | a recombinant lambda phage carrying the reca gene of rhizobium phaseoli was isolated from a r. phaseoli genomic library by complementation of the fec- phenotype of the recombinant phage in escherichia coli. when expressed in e. coli, the cloned reca gene was shown to restore resistance to both uv irradiation and the dna alkylating agent methyl methanesulphonate (mms). the r. phaseoli reca gene also promoted homologous recombination in e. coli. the cloned reca gene was only weakly inducible in e. ... | 1991 | 1832737 |
| sequence and structural organization of a nif a-like gene and part of a nifb-like gene of herbaspirillum seropedicae strain z78. | the deduced amino acid sequence derived from the sequence of a fragment of dna from the free-living diazotroph herbaspirillum seropedicae was aligned to the homologous protein sequences encoded by the nifa genes from azorhizobium caulinodans, rhizobium leguminosarum, rhizobium meliloti and klebsiella pneumoniae. high similarity was found in the central domain and in the c-terminal region. the h. seropedicae putative nifa sequence was also found to contain an interdomain linker similar to that co ... | 1991 | 1840608 |
| identification of nolr, a negative transacting factor controlling the nod regulon in rhizobium meliloti. | in rhizobium meliloti, expression of the nodulation genes (nod and nol genes) is under both positive and negative controls. these genes are activated by the products of the three related nodd genes, in conjunction with signal molecules from the host plants. we showed that negative regulation is mediated by a repressor protein, binding to the overlapping nodd1 and noda as well as to the nodd2 promoters. the encoding gene, termed nolr, was identified and cloned from strain 41. by subcloning, delet ... | 1991 | 1840615 |
| tomato yellow leaf curl virus from sardinia is a whitefly-transmitted monopartite geminivirus. | the genome of an isolate of tomato yellow leaf curl virus from sardinia, italy (tylcv-s), a geminivirus transmitted by the whitefly bemisia tabaci, has been cloned and sequenced. the single circular dna molecule comprises 2770 nucleotides. genome organisation closely resembles that of the dna a component of the whitefly-transmitted geminiviruses with a bipartite genome. a 1.8 mer of the tylcv-s genome in a binary vector of agrobacterium tumefaciens is infectious upon agroinoculation of tomato pl ... | 1991 | 1840676 |
| a nodulin specifically expressed in senescent nodules of winged bean is a protease inhibitor. | nodule senescence is one aspect of nitrogen fixation that is important to study from the perspective of improving the host-bacteroid interaction. in winged bean nodules, a 21-kilodalton protein is specifically expressed when senescence begins. using subcellular fractionation, we observed that this plant protein interacts with the bacteroids. microsequencing of the protein allowed us to obtain a specific oligonucleotide that was used to isolate the corresponding nodule cdna. sequence analysis of ... | 1991 | 1840910 |
| comparative response of pisum sativum nodulated with indigenous soil rhizobium populations and/or co-inoculated with a rhizobium leguminosarum strain. i. acetylene-reducing, dihydrogen- and carbon dioxide-evolving activities. | no significant differences in the acetylene-reducing activity and evolution of h2 and co2 from nodulated roots of pisum sativum inoculated with soil rhizobium populations from two soils with different acidities (ruzynĕ soil 7.6; lukavec soil 4.9) were observed. rhizobium population from lukavec soil formed nodules, exhibiting a higher h2 evolution. co-inoculation with the hup+ strain 128c30 (7 x 10(7) cells per seedling) eliminated, to some extent, the effect of soil populations on physiological ... | 1991 | 1841862 |