| efficient transformation of agrobacterium spp. by high voltage electroporation. | | 1989 | 2682529 |
| genetic analysis and cellular localization of the rhizobium host specificity-determining node protein. | the nucleotide sequence of the node gene of rhizobium trifolii strain anu843 was determined. like the node gene of r. leguminosarum strain 248 it encodes a protein with a predicted mol. wt of 42.0 kd. the predicted node proteins of r.trifolii and r.leguminosarum have a homology of 78%. using antibodies raised against the node protein of r.trifolii it was shown that the node products of r.leguminosarum and r.trifolii are localized in the cytoplasmic membrane. furthermore, these node proteins are ... | 1989 | 2684629 |
| analysis of the nucleotide sequence of the streptomyces glaucescens tcmi genes provides key information about the enzymology of polyketide antibiotic biosynthesis. | key information about the biosynthesis of polyketide metabolites has been uncovered by sequence analysis of the tetracenomycin c polyketide synthase genes (tcml) from streptomyces glaucescens gla.0. the sequence data revealed the presence of three complete open reading frames (orfs). orf1 and orf2 appear to be translationally coupled and would encode proteins containing 426 and 405 amino acids, respectively. the two deduced proteins are homologous to known beta-ketoacyl synthases. orf3 begins 70 ... | 1989 | 2684656 |
| in vivo studies on the interaction of rna polymerase-sigma 54 with the klebsiella pneumoniae and rhizobium meliloti nifh promoters. the role of nifa in the formation of an open promoter complex. | transcription from the klebsiella pneumoniae and rhizobium meliloti nifh promoters requires the positive control protein nifa and the alternative sigma factor sigma 54, encoded by the rpon gene. transcription from the k. pneumoniae nifh promoter is fully dependent upon nifa bound at the upstream activator sequence (uas) whereas the r. meliloti nifh promoter can be efficiently activated in the absence of this sequence and can also be activated by a mutant form of nifa unable to bind the uas. the ... | 1989 | 2685331 |
| nucleotide sequence of the tzs gene from agrobacterium rhizogenes strain a4. | | 1989 | 2685753 |
| 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 |
| [crown gall tumor: molecular mechanism of t-dna transfer]. | | 1989 | 2690188 |
| nucleotide sequence of the regulatory nifa gene of rhizobium leguminosarum pre: transcriptional control sites and expression in escherichia coli. | we report the sequence of the regulatory nifa gene of rhizobium leguminosarum pre. the transcription initiation and termination sites of nifa were mapped and a potential promoter and a rho-independent terminator identified. the nifa gene has two possible translation start sites, both of which are used in an escherichia coli background, resulting in proteins with apparent molecular weights of 58 kd and 57 kd; initiation at the second site is preferred over initiation at the first. the nifa-nifb i ... | 1989 | 2693897 |
| a family of genes encoding a cell-killing function may be conserved in all gram-negative bacteria. | the relf gene in escherichia coli is related to the hok gene on plasmid r1. both genes encode small proteins which, when overexpressed in e. coli lead to collapse of the membrane potential and cell death. a third gene, designated gef, which encodes a homologous cell-toxic protein, has been isolated from e. coli dna. both gef and relf are transcribed in e. coli and subject to post-transcriptional regulation which, in the case of gef, is coupled to translation of a leader sequence. the finding of ... | 1989 | 2693900 |
| rhizobium genetics. | | 1989 | 2694941 |
| genetic analysis and regulation of the rhizobium meliloti genes controlling c4-dicarboxylic acid transport. | the genes controlling the transport of c4-dicarboxylic acids from rhizobium meliloti have been cloned and analysed. the nucleotide sequence of the control region of the structural dcta and the regulatory dctbd genes has been determined. comparison with the rhizobium leguminosarum dct genes revealed a high degree of homology. gene fusions to the enteric laczy reporter gene were constructed and the expression of the dcta and dctbd genes studied under various physiological conditions. in free-livin ... | 1989 | 2695394 |
| cloning and sequence analysis of the ntra (rpon) gene of pseudomonas putida. | the gene encoding a sigma factor ntra (rpon) was cloned from pseudomonas putida by cross-hybridization with a probe containing a part of the corresponding escherichia coli gene. the cloned gene complemented an ntra mutation of e. coli in activation of xyl genes on the tol plasmid. the predicted amino acid (aa) sequence of p. putida ntra (497 aa; mr 56,215) is highly homologous to ntra proteins from azotobacter vinelandii (81.7%), klebsiella pneumoniae (52.6%), and rhizobium meliloti (36.1%). the ... | 1989 | 2695395 |
| [leghemoglobins and leghemoglobin genes]. | | 1989 | 2699024 |
| identification of a gene linked to rhizobium meliloti ntra whose product is homologous to a family to atp-binding proteins. | the ntra gene of rhizobium meliloti has recently been identified and shown to be required for a diverse set of metabolic functions (c. w. ronson, b. t. nixon, l. m. albright, and f. m. ausubel, j. bacteriol. 169:2424-2431, 1987). as a result of sequencing the ntra gene and its flanking regions from r. meliloti, we identified an open reading frame directly upstream of ntra, orf1, whose predicted product is homologous to a superfamily of atp-binding proteins involved in transport, cell division, n ... | 1989 | 2703463 |
| evidence that the transcription activator encoded by the pseudomonas putida nahr gene is evolutionarily related to the transcription activators encoded by the rhizobium nodd genes. | the nahr gene of the 83-kilobase naphthalene degradation plasmid nah7 of pseudomonas putida encodes a 34-kilodalton polypeptide which binds to the nah and sal promoters to activate transcription of the degradation genes in response to the inducer salicylate. the dna sequence of the nahr gene was determined, and a derived amino acid sequence of the nahr protein was obtained. a computer search for homologous proteins showed that within the first 124 amino-terminal residues, nahr has approximately ... | 1989 | 2703465 |
| antibiotic inactivating enzymes from a clinical isolate of agrobacterium radiobacter. | | 1989 | 2708185 |
| nucleotide sequence and analysis of the plant-inducible locus pinf from agrobacterium tumefaciens. | several loci on the tumor-inducing plasmid from agrobacterium tumefaciens were transcriptionally activated in the presence of wounded plant tissue or extracts. the inducible virulence loci were required for efficient tumor formation. in contrast, the plant-inducible locus pinf was not observed to be absolutely essential for virulence. mutants in pinf showed an attenuated virulence on a variety of dicotyledonous hosts, and this attenuation became more pronounced with decreasing numbers of bacteri ... | 1989 | 2708311 |
| cooperative binding of agrobacterium tumefaciens vire2 protein to single-stranded dna. | the vire2 protein of agrobacterium tumefaciens ti plasmid ptia6 is a single-stranded-dna-binding protein. density gradient centrifugation studies showed that it exists as a tetramer in solution. monomeric vire2 active in dna binding could also be obtained by using a different protein isolation procedure. vire2 was found to be thermolabile; brief incubation at 37 degrees c abolished its dna-binding activity. it was insensitive to the sulfhydryl-specific reagent n-ethylmaleimide. removal of the ca ... | 1989 | 2708313 |
| biochemical characterization of avirulent agrobacterium tumefaciens chva mutants: synthesis and excretion of beta-(1-2)glucan. | the chva gene product of agrobacterium tumefaciens is required for virulence and attachment of bacteria to plant cells. three chva mutants were studied. in vivo, they were defective in the synthesis, accumulation, and secretion of beta-(1-2)glucan; however, the 235-kilodalton (kda) protein known to be involved in the synthesis of beta-(1-2)glucan (a. zorreguieta and r. ugalde, j. bacteriol. 167:947-951, 1986) was present and active in vitro. was present and active in vitro. two molecular forms o ... | 1989 | 2708321 |
| transcription of rhia, a gene on a rhizobium leguminosarum bv. viciae sym plasmid, requires rhir and is repressed by flavanoids that induce nod genes. | strains of rhizobium leguminosarum biovar viciae specifically make an abundant protein (rhi) in free-living culture but not in bacteroids. genes needed for rhi synthesis are on a sym plasmid and here we show that one of these genes, rhia, is the structural gene that specifies this polypeptide. transcription of rhia requires a regulatory gene, rhir, located close to rhia and to nod genes involved in nodulation. mutations in rhia or rhir do not appear to affect symbiotic nitrogen fixation. transcr ... | 1989 | 2716520 |
| a second exopolysaccharide of rhizobium meliloti strain su47 that can function in root nodule invasion. | rhizobium meliloti strain su47 produces the calcofluor-binding exopolysaccharide, succinoglycan, that is required for alfalfa root nodule invasion. strains derived from r. meliloti su47 secreted an acidic exopolysaccharide, epsb, that replaced succinoglycan in nodule invasion. epsb, which has not formerly been identified among the rhizobiaceae, consisted of the repeating unit 4,6-o-(1-carboxyethylidene)-alpha-d-galp1----3(x-o-ac)-beta-d-g lcp1----3. epsb synthesis occurred either in strains cont ... | 1989 | 2717610 |
| lipid a with 2,3-diamino-2,3-dideoxy-glucose in lipopolysaccharides from slow-growing members of rhizobiaceae and from "pseudomonas carboxydovorans". | lipid a's from two bradyrhizobium species and from the phylogenetically closely related species "pseudomonas carboxydovorans" were found to contain 2,3-diamino-2,3-dideoxy-glucose as lipid a backbone sugar. in contrast, three representatives of the genus rhizobium, as well as the phylogenetically related species agrobacterium tumefaciens, contain solely glucosamine as lipid a backbone sugar. these findings support independent studies on the phylogenetical relatedness based on 16s rrna-data of th ... | 1989 | 2719525 |
| recovery of agrobacterium tumefaciens t-dna molecules from whole plants early after transfer. | a system for the analysis of independent t-dna transfer events from agrobacterium to plants is described. the complete t-dna except for the 25 bp border sequences was replaced by one genome of a plant virus so that upon transfer to the plant, a viable replicon is produced by circularization. rescue of virus from such infected plants allowed analysis of dna sequences at or close to the ends of t-dna molecules. a rather conserved right border remnant of three nucleotides was found, whereas the seq ... | 1989 | 2720788 |
| the central domain of rhizobium meliloti nifa is sufficient to activate transcription from the r. meliloti nifh promoter. | the rhizobium meliloti nifa product (nifa) shares extensive homology in its central region and at its c-terminal end with rhizobium leguminosarum dctd and with ntrc from several species. all three proteins are transcriptional activators of ntra (rpon)-rna polymerase-dependent promoters. several large deletions of r. meliloti nifa were constructed to investigate the role of the conserved and divergent domains of nifa in transcriptional activity and posttranscriptional regulation by oxygen. the ab ... | 1989 | 2722751 |
| a new core tetrasaccharide component from the lipopolysaccharide of rhizobium trifolii anu 843. | a second core oligosaccharide fragment has been isolated and characterized from the lipopolysaccharide (lps) of rhizobium trifolii anu 843. the oligosaccharide is a tetrasaccharide composed of galactose, galacturonic acid, mannose, and 3-deoxy-d-manno-2-octulosonic acid. the mannose residue is alpha-linked to the 4-position of 3-deoxy-d-manno-2-octulosonic acid and the galacturonic acid residue is alpha-linked to the 6-position of mannose. the galactose residue, which is acetylated at the 4-posi ... | 1989 | 2722833 |
| 27-hydroxyoctacosanoic acid is a major structural fatty acyl component of the lipopolysaccharide of rhizobium trifolii anu 843. | a new hydroxylated, very long-chain fatty acid has been isolated and characterized from the lipopolysaccharide (lps) of rhizobium trifolii anu 843. the lipid a of the organism was degraded by mild alkali and borohydride and the products methylated, peracetylated, and fractionated on a c18 reverse-phase column. the major lipid fraction was reduced with lithium triethylborohydride, methylated, peracetylated, and subjected to thin layer chromatography. the methylated peracetylated acid and the redu ... | 1989 | 2722834 |
| a family of activator genes regulates expression of rhizobium meliloti nodulation genes. | nodulation (nod) gene expression in rhizobium meliloti requires plant inducers and the activating protein product of the nodd gene. we have examined three genes in r. meliloti which have nodd activity and sequence homology. these three nodd genes are designated nodd1, nodd2 and nodd3, and have distinctive properties. the nodd1 gene product activates expression of the nodabc operon, as measured by a nodc-lacz fusion or by transcript analysis, in the presence of crude seed or plant wash or the ind ... | 1989 | 2731734 |
| opines stimulate induction of the vir genes of the agrobacterium tumefaciens ti plasmid. | upon incubation of agrobacterium tumefaciens a348 with acetosyringone, the vir genes encoded by the ti (tumor-inducing) plasmid are induced. the addition of certain opines, including octopine, nopaline, leucinopine, and succinamopine, enhanced this induction 2- to 10-fold. the compounds mannopine, acetopine, arginine, pyruvate, and leucine did not stimulate the induction of the vir genes to such an extent. the enhancement of vir gene induction by opines depended on acetosyringone and the genes v ... | 1989 | 2738020 |
| lipopolysaccharide mutants of rhizobium meliloti are not defective in symbiosis. | mutants of rhizobium meliloti selected primarily for bacteriophage resistance fall into 13 groups. mutants in the four best-characterized groups (class a, lpsb, lpsc, and class d), which map to the rhizobial chromosome, appear to affect lipopolysaccharide (lps) as judged by the reactivity with monoclonal antibodies and behavior on sodium dodecyl sulfate-polyacrylamide gels of extracted lps. mutations in all 13 groups, in an otherwise wild-type genetic background, are fix+ on alfalfa. this sugges ... | 1989 | 2738026 |
| purification and partial characterization of the rhizobium leguminosarum biovar viciae ca2+-dependent adhesin, which mediates the first step in attachment of cells of the family rhizobiaceae to plant root hair tips. | the ca2+-dependent adhesin which mediates the first step in attachment of bacteria of the family rhizobiaceae to plant root hair tips was isolated from the surface of rhizobium leguminosarum biovar viciae cells; its ability to inhibit attachment of r. leguminosarum to pea root hair tips was used as a bioassay. isolated adhesin was found to be able to inhibit attachment of both carbon-limited and manganese-limited r. leguminosarum cells. a multicolumn purification procedure was developed which re ... | 1989 | 2738027 |
| structural and functional analysis of nitrogenase genes from the broad-host-range rhizobium strain anu240. | the genes encoding the structural components of nitrogenase, nifh, nifd and nifk, from the fast-growing, broad-host-range rhizobium strain anu240 have been identified and characterized. they are duplicated and linked in an operon nifhdk in both copies. sequence analysis of the nifh gene from each copy, together with partial sequence analysis of the nifd and nifk genes, and restriction endonuclease analysis suggested that the duplication is precise. comparison of the fe-protein sequence from stra ... | 1989 | 2744485 |
| the rhizobium meliloti fdxn gene encoding a ferredoxin-like protein is necessary for nitrogen fixation and is cotranscribed with nifa and nifb. | sequencing of the rhizobium meliloti dna region downstream of nifa revealed the existence of nifb, fdxn and orf3. the molecular weight of the fdxn protein (mr 6830) and the distribution of cysteine residues in its deduced amino acid sequence is typical for low molecular weight bacterial ferredoxins. interposon insertion and plasmid integration mutagenesis demonstrated that fdxn is essential for nitrogen fixation in r. meliloti, whereas the predicted translation product of orf3 (mr 8708) is not n ... | 1989 | 2747618 |
| isolation and characterization of an ipt gene from the ti plasmid bo542. | a 1.9 kb clone of the t-dna region of the agrobacterium tumefaciens ti plasmid bo542 which exhibited homology to the isopentenyl transferase (ipt) locus of ptia6 was identified by low stringency dna hybridization. introduction of this segment of ptibo542 dna into cells of nicotiana tabacum or n. glauca caused tumor formation in vivo, and allowed hormone independent growth in vitro. furthermore, this dna segment complemented ipt mutant strains of a. tumefaciens, restoring their ability to cause t ... | 1989 | 2747621 |
| delineation of the regulatory region sequences of agrobacterium tumefaciens virb operon. | a virb-lacz translational fusion was constructed to monitor expression of the agrobacterium tumefaciens virb operon. expression of the fusion gene was dependent on the presence of ptia6 vira, virg, and a plant factor acetosyringone. analysis of deletion mutants, constructed by exonuclease bal31 digestion, showed that 68 residues upstream of the virb transcription initiation site was necessary for its expression. a tt----cc substitution at positions -62 and -61 led to a 7 fold reduction in virb e ... | 1989 | 2748333 |
| accumulation of a nod gene inducer, the flavonoid naringenin, in the cytoplasmic membrane of rhizobium leguminosarum biovar viciae is caused by the ph-dependent hydrophobicity of naringenin. | most sym plasmid-localized nodulation genes of rhizobium leguminosarum bv. viciae are only expressed upon activation of the nodd protein by plant flavonoids, e.g., naringenin (s. a. j. zaat, c. a. wijffelman, h. p. spaink, a. a. n. van brussel, and b. j. j. lugtenberg, j. bacteriol, 169:198-204, 1987). as part of a study on the mechanism of nodd protein activation, the mechanism of uptake and the intracellular fate of [3h]naringenin were studied. naringenin was accumulated by rhizobium cells wit ... | 1989 | 2753859 |
| isolation and characterization of the unusual lipopolysaccharide component, 2-amino-2-deoxy-2-n-(27-hydroxyoctacosanoyl)-3-o-(3-hydroxy- tetradecanoyl)-gluco-hexuronic acid, and its de-o-acylation product from the free lipid a of rhizobium trifolii anu843. | two new, unusual lipid a components have been isolated and characterized from the free lipid a of rhizobium trifolii anu843. 2-amino-2-deoxy-2-n-(27-hydroxyoctacosanoyl)-3-o-(3-hydroxy- tetradecanoyl)-gluco-hexuronic acid and its de-o-acylation product were purified from the chloroform/methanol extract of a mild acid hydrolysate of the lipopolysaccharide by chromatography on c18 reverse-phase columns and layers. the compositions of the two compounds were determined by releasing the acyl componen ... | 1989 | 2760055 |
| developmental regulation of a rhizobium cell surface antigen during growth of pea root nodules. | a monoclonal antibody, afrc mac 203, was used to examine the expression of a nodule-induced cell surface antigen associated with lipopolysaccharide in rhizobium leguminosarum bv. viciae 3841. silver-enhanced immunogold-labeled tissue sections revealed that, in very young tissues of pea root nodules, the nodule-induced form of lipopolysaccharide antigen was not expressed either by rhizobia in the infection thread or by bacteria recently released into the plant cell cytoplasm. in the more mature r ... | 1989 | 2768180 |
| expression of a cell surface antigen from rhizobium leguminosarum 3841 is regulated by oxygen and ph. | rhizobium leguminosarum bv. viciae 3841 was grown in liquid suspension culture to investigate how culture conditions could affect the expression of a developmentally regulated cell surface antigen associated with lipopolysaccharide. the antigen, which is recognized by monoclonal antibody afrc mac 203, was expressed when cultures were grown at neutral ph under low-oxygen conditions (less than 7.5% [vol/vol] o2 in the gas phase). antigen was also expressed in aerobically grown cultures at ph value ... | 1989 | 2768181 |
| genetic derepression of a developmentally regulated lipopolysaccharide antigen from rhizobium leguminosarum 3841. | monoclonal antibody afrc mac 203 recognizes a developmentally regulated lipopolysaccharide antigen in rhizobium leguminosarum bv. viciae 3841. transposon-induced mutants that constitutively expressed mac 203 antigen were isolated. these strains were morphologically normal, showed no gross abnormalities in lipopolysaccharide size distribution on sodium dodecyl sulfate-polyacrylamide gels, and induced normal nitrogen-fixing nodules. however, the mutants lacked lipopolysaccharide epitopes recognize ... | 1989 | 2768182 |
| immunogold localization of the nodc and noda proteins of rhizobium meliloti. | monospecific, polyclonal antibodies to the nodc and noda gene products of rhizobium meliloti were used in combination with immunogold labeling and transmission electron microscopy to localize the nodc and noda proteins in cultures of r. meliloti. both nodc and noda were detected in the cytoplasm and cell envelope in thin sections of free-living rhizobia treated with luteolin, a known inducer of nod gene expression; however, only nodc was detected on cell surfaces when immunolabeling was performe ... | 1989 | 2768184 |
| an osmoregulated dipeptide in stressed rhizobium meliloti. | one common mechanism of cellular adaptation to osmotic stress is the accumulation of organic solutes in the cytosol. we have used natural-abundance 13c nuclear magnetic resonance to identify all organic solutes that accumulate to significant levels in rhizobium meliloti. our studies led to the discovery of a new dipeptide, n-acetylglutaminylglutamine amide (naggn), which is accumulated during osmotic stress. only rarely have peptides been shown to function in bacteria, and furthermore, this is t ... | 1989 | 2768187 |
| the predicted protein product of a pathogenicity locus from pseudomonas syringae pv. phaseolicola is homologous to a highly conserved domain of several procaryotic regulatory proteins. | a ca. 20-kilobase (kb) region (hrp) that controls the interaction of pseudomonas syringae pv. phaseolicola with its host (pathogenicity) and nonhost plants (hypersensitive reaction) was previously cloned and partially characterized. in this study we defined the limits and determined the nucleotide sequence of a hrp locus (hrps), located near the right end of the hrp cluster. the largest open reading frame (orf302) in hrps has a coding capacity for a 302-amino-acid polypeptide. the predicted amin ... | 1989 | 2768197 |
| properties of l-lysine epsilon-dehydrogenase from agrobacterium tumefaciens. | lysine epsilon-dehydrogenase, which has been purified to homogeneity from the extract of agrobacterium tumefaciens icr 1600, had a molecular weight of approximately 78,000 and consisted of two subunits identical in molecular weight (about 39,000). the enzyme showed a high substrate specificity. in addition to l-lysine, s-(beta-aminoethyl)-l-cysteine was deaminated by the enzyme, but to a far lesser extent. nad+ and some nad+ analogs (deamino-nad+ and 3-acetylpyridine-nad+) served as a cofactor. ... | 1989 | 2768207 |
| application of gas-liquid chromatography to the routine identification of nonfermenting gram-negative bacteria in clinical specimens. | a total of 430 strains of glucose-nonfermenting gram-negative bacteria representing 35 species were analyzed for their cellular fatty acid composition by gas-liquid chromatography (glc). on the basis of qualitative differences in their cellular fatty acid composition, these bacteria could be divided into 19 distinct chromatographic groups. eight pseudomonas species, achromobacter xylosoxidans, group vd, and agrobacterium radiobacter were identified from their fatty acid compositions alone. the o ... | 1989 | 2768442 |
| dna transfer from agrobacterium to zea mays or brassica by agroinfection is dependent on bacterial virulence functions. | dna transfer from agrobacterium tumefaciens, a soil bacterium, to the non-host graminaceous monocotyle-donous plant zea mays, was analysed using the recently developed technique of agroinfection. agroinfection of z. mays with maize streak virus using strains of a. tumefaciens carrying mutations in the ptic58 virulence region showed an almost absolute dependence on the products of the bacterial virc genes. in contrast, agroinfection of the control host brassica rapa with cauliflower mosaic virus ... | 1989 | 2770696 |
| enzymes of carbohydrate metabolism in fast-growing rhizobium grown on hexoses or succinate. | enzymatic evidence supports that succinate mediates repression of hexose-catabolising enzymes in fast-growing rhizobium sp. (cicer arietinum). enzymes of the embden-myerhof-parnas, entner-doudoroff and pentose phosphate pathways were found present in hexose-grown cells but not in succinate-grown cells. these however could be induced by the presence of hexoses. | 1989 | 2777319 |
| activation of l-lysine epsilon-dehydrogenase from agrobacterium tumefaciens by several amino acids and monocarboxylates. | the activation of lysine epsilon-dehydrogenase [ec 1.4.1.] by l-lysine was dependent on lysine concentration and was accompanied by association of the dimeric enzymes to a tetramer. the lysine concentration required for the half-maximal activation was 0.28 mm, which was lower than the km value for l-lysine. in addition to l-lysine, several compounds, which were neither substrates nor inhibitors, activated the enzyme. the compounds which activated the enzyme have common structural characteristics ... | 1989 | 2777754 |
| catheter infection caused by an unusual pathogen, agrobacterium radiobacter. | the genus agrobacterium is composed of several phytopathogenic species occurring worldwide in soils. one nontumorigenic species, agrobacterium radiobacter, has occasionally been isolated from clinical specimens, but its pathogenic role in these cases has been difficult to ascertain since agrobacteria are usually isolated in association with other bacteria. we report the case of a central venous catheter infection and present the characteristics of a. radiobacter. | 1989 | 2778076 |
| binding of the citrobacter freundii ampr regulator to a single dna site provides both autoregulation and activation of the inducible ampc beta-lactamase gene. | citrobacter freundii encodes an inducible chromosomal beta-lactamase. induction requires the product of the ampr gene, which is transcribed in the opposite orientation from the ampc beta-lactamase gene. we show here that the ampr protein acts as a transcriptional activator by binding to a dna region immediately upstream of the ampc promoter. the dnase i footprint pattern was not affected by growth in the presence of beta-lactam inducer or by the use of extracts prepared from cells carrying the a ... | 1989 | 2786868 |
| distribution of delta-aminolevulinic acid biosynthetic pathways among phototrophic bacterial groups. | two biosynthetic pathways are known for the universal tetrapyrrole precursor, delta-aminolevulinic acid (ala). in the ala synthase pathway which was first described in animal and some bacterial cells, the pyridoxal phosphate-dependent enzyme ala synthase catalyzes condensation of glycine and succinyl-coa to form ala with the loss of c-1 of glycine as co2. in the five-carbon pathway which was first described in plant and algal cells, the carbon skeleton of glutamate is converted intact to ala in ... | 1989 | 2789025 |
| membrane topology and functional analysis of the sensory protein vira of agrobacterium tumefaciens. | the vira gene of agrobacterium tumefaciens encodes an inner membrane that mediates the transcriptional activation of virulence genes in response to plant signal molecules. we report here a functional analysis of the n-terminal, c-terminal and periplasmic domains of vira in transmembrane signalling. first, we show that vira has a transmembrane topology by analysis of the alkaline phosphatase activities, determined by several vira-phoa gene fusions. second, we report here the construction of sever ... | 1989 | 2792074 |
| critical spacing between two essential cysteine residues in the interdomain linker of the bradyrhizobium japonicum nifa protein. | a special sequence motif in the bradyrhizobium japonicum nifa protein, consisting of two functionally essential cysteines separated by four other amino acids (cys-aa4-cys), has been proposed to be part of a potential metal-binding site [(1988) nucleic acids res. 16, 2207-2224]. using the techniques of oligonucleotide-directed mutagenesis, we report here that several of the four intervening amino acids can be replaced by others without loss of nifa function. the deletion of one amino acid to give ... | 1989 | 2792368 |
| conservation between coding and regulatory elements of rhizobium meliloti and rhizobium leguminosarum dct genes. | complementation of rhizobium leguminosarum dct mutants with a cosmid bank yielded rhizobium meliloti homologs of the dcta, dctb, and dctd genes. the genes dctb and dctd are thought to form a two-component system which responds to the presence of c4-dicarboxylates to regulate expression of a transport protein encoded by dcta. dna sequence analysis showed that dct coding and intergenic regions, including putative binding sites for the dctd protein and sigma 54-rna polymerase, were highly conserved ... | 1989 | 2793824 |
| dna footprint analysis of the transcriptional activator proteins nodd1 and nodd3 on inducible nod gene promoters. | the rhizobium meliloti nodd1 and nodd3 gene products (nodd1 and nodd3) are members of the lysr-nodd gene regulator family. they are functionally distinct in that nodd1 transcriptionally activates other nod genes in the presence of a flavonoid inducer such as luteolin, while nodd3 is capable of activating nod gene expression at high levels in the absence of inducer. nodd1 and nodd3 are dna-binding proteins which interact with dna sequences situated upstream of the transcription initiation sites o ... | 1989 | 2793828 |
| requirement for chemotaxis in pathogenicity of agrobacterium tumefaciens on roots of soil-grown pea plants. | agrobacterium tumefaciens tn5 mutants deficient in chemotaxis to root exudates were used to study the significance of chemotaxis in crown gall pathogenesis. mutants deficient in motility and in chemotaxis were fully virulent when inoculated by direct immersion in inoculum, followed by growth for 2 weeks in moist growth pouches. ability of mutant bacteria to move through soil to infect roots was tested by planting wounded seedlings into air-dried soil or sand that had been infested with inoculum. ... | 1989 | 2793831 |
| specificity of signal molecules in the activation of agrobacterium virulence gene expression. | the activation of the agrobacterium virulence system is known to be induced by certain phenolic compounds. we have tested the vir-inducing ability of fifty compounds, by using a virb-lacz gene fusion, and analysed the relationship between structure and activity of these compounds. in this way we have identified several new vir-inducers: coniferylalcohol, 3,5-dimethoxy-4-hydroxybenzene, homovanillic acid, ferulic acid, 3-ethoxy-4-hydroxybenzaldehyde and guaiacol, all of which are compounds with s ... | 1989 | 2796734 |
| characterization of the vira virulence gene of the nopaline plasmid, ptic58, of agrobacterium tumefaciens. | we have determined the complete nucleotide sequence of a 4.8 kilobase fragment encompassing the vira locus of the nopaline-type plasmid, ptic58, of agrobacterium tumefaciens. vira is composed of a single open reading frame of 2499 nucleotides, capable of encoding a protein of 91.3 kilodaltons. a trpe::vira gene fusion was used to confirm the reading frame of vira. high nucleotide and amino acid sequence homologies were observed between ptic58 vira and the vira sequences of three octopine-type pl ... | 1989 | 2796735 |
| [utilization of nitrate by bacteroids and cytosol of nodules formed by rhizobium leguminosarum]. | nitrite production by nodules and roots of pea plants (pisum sativum l., cultivar alaska) inoculated with rhizobium leguminosarum strain 3855 has been studied. nitrate reductase (nr) activity and nitrite reductase (nir) activity of the bacteroidal and cytosolic fractions of the nodules were also determined, as well as the nitrite content of the nodules cytosol. nitrite production by nodules and roots from plants treated with 5 mm kno3 was higher than that of nodules and roots from plants not tre ... | 1989 | 2803636 |
| arginase of agrobacterium ti plasmid c58. dna sequence, properties, and comparison with eucaryotic enzymes. | agrobacterium nopaline ti plasmids code for three enzymes of nopaline [n2-(1,3-dicarboxypropyl)-l-arginine] degradation: nopaline oxidase, arginase, and ornithine cyclodeaminase. we describe the dna sequence of the arginase gene, a comparison of the deduced protein sequence with eucaryotic arginases, and properties of the procaryotic enzyme. the results show that the agrobacterial arginase is related with arginases from yeast, rat liver, and human liver (28-33% identity). the ti plasmid enzyme r ... | 1989 | 2806247 |
| ti plasmid-controlled chromosome transfer in agrobacterium tumefaciens. | in octopine-type a. tumefaciens r10, transfer of chromosomal arginine degradation genes (arc genes) was observed under conditions in which ti plasmid transfer took place. however, transconjugants that had acquired the arc genes but not the ti plasmid were recovered. during this process, several other chromosomal genes, such as genes encoding phage resistances or genes complementing a galactose utilization mutation or a glycine-serine auxotrophy, were transferred from strain r10 to the recipient. | 1989 | 2808306 |
| cloning and expression of rat cdna encoding corticosteroid 11 beta-dehydrogenase. | corticosteroid 11 beta-dehydrogenase (11-dh) catalyzes the conversion of cortisol to the inactive metabolite cortisone. absence of 11-dh activity leads to a potentially fatal form of childhood hypertension termed apparent mineralocorticoid excess. as a first step in elucidating the molecular basis of this disorder, we isolated and characterized a rat cdna clone encoding 11-dh. this clone hybridized to a single mrna species in liver, kidney, and testis rna but not to rna from heart. the insert wa ... | 1989 | 2808402 |
| regulatory elements within the agropine synthase promoter of t-dna. | dna sequences involved in the expression of the agropine synthase gene (ags) of t-dna were identified by analysis of transcriptional activity of promoter mutants in crown gall tumors of sunflower. precise quantification of activity was achieved using a homologous reference gene as an internal standard. analysis of 5'-deletion mutants demonstrated the requirement of 314 base pairs of upstream dna sequences for optimal activity. five regions involved in transcriptional regulation were identified i ... | 1989 | 2808432 |
| [transfer of the agrobacterial gene for cytokinin biosynthesis into tobacco plants]. | the gene transfer into plants using the genetic engineering methods gives us the possibility to obtain transgeneric plants having acquired the new traits. some bacterial genes can be used for this purpose. obtaining of a transgeneric plant harbouring the cytokinin synthesis gene ipt (gene 4) from the t-dna of agrobacterium tumefaciens ti-plasmid seems to be useful. the expression of tumor agrobacterial ipt gene in transformed plant cells interferes with the normal growth and regulation of the wh ... | 1989 | 2811903 |
| cloning and characterization of hydrogen uptake genes from rhizobium leguminosarum. | a gene library of genomic dna from the hydrogen uptake (hup)-positive strain 128c53 of rhizobium leguminosarum was constructed by using the broad-host-range mobilizable cosmid vector plafr1. the resulting recombinant cosmids contained insert dna averaging 21 kilobase pairs (kb) in length. two clones from the above gene library were identified by colony hybridization with dna sequences from plasmid phu1 containing hup genes of bradyhizobium japonicum. the corresponding recombinant cosmids, pal618 ... | 1987 | 2822654 |
| double-stranded cleavage of t-dna and generation of single-stranded t-dna molecules in escherichia coli by a vird-encoded border-specific endonuclease from agrobacterium tumefaciens. | the vird locus of agrobacterium tumefaciens ti plasmid ptia6 was sequenced. computer analysis of the sequence indicated five possible open reading frames (orfs) within this locus. two additional orfs were identified distal to this locus. however, only two polypeptides of apparent molecular masses 16 and 56 kilodaltons, the products of orfs 1 and 2, were detected in escherichia coli, both in vivo and in an in vitro coupled transcription-translation system. the vird locus was cloned in expression ... | 1987 | 2822660 |
| regulation of the vir genes of agrobacterium tumefaciens plasmid ptic58. | the virulence (vir) region of ptic58 was screened for promoter activities by using gene fusions to a promoterless lux operon in the broad-host-range vector pucd615. active vir fragments contained the strongly acetosyringone-inducible promoters of virb, virc, vird, and vire and the weakly inducible promoters of vira and virg. identical induction patterns were obtained with freshly sliced carrot disks, suggesting that an inducer is released after plant tissue is wounded. optimal conditions for vir ... | 1987 | 2822665 |
| rhizobium meliloti mutants that fail to succinylate their calcofluor-binding exopolysaccharide are defective in nodule invasion. | we have identified a set of tn5-generated mutants of rhizobium meliloti on the basis of their failure to form a fluorescent halo under uv light when grown on agar medium containing calcofluor. these mutations define a new genetic locus we have termed exoh. alfalfa seedlings inoculated with exoh mutants form ineffective nodules that do not contain intracellular bacteria or bacteroids. root hair curling is significantly delayed and infection threads abort in the nodule cortex. analyses of exopolys ... | 1987 | 2824062 |
| physical analysis of pb2, a temperate bacteriophage of agrobacterium tumefaciens. | we have constructed a detailed physical map of pb2, a temperate bacteriophage of agrobacterium tumefaciens. the restriction endonucleases bam hi (3 sites), eco ri (22 sites), hind iii (19 sites), hpa i (5 sites), xba i (1 site), and xho i (1 site) were used to elucidate the map of infectious pb2 dna. the map was generated by reciprocal sequential digestions and analysis of partial digestion products of isolated restriction fragments. we have determined the genome size as 66.35 +/- 1.71 kb. the p ... | 1987 | 2824148 |
| 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 ... | 1988 | 2826389 |
| 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 ... | 1988 | 2826395 |
| 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 ... | 1988 | 2826404 |
| similarities between nucleotide sequences of insertion elements of agrobacterium tumefaciens and pseudomonas savastanoi in relation to agrobacterium tumefaciens tc-dna. | | 1987 | 2827126 |
| physical map of the t-dna region of agrobacterium rhizogenes strain ncppb2659. | the t-dna region of the plasmid responsible for hairy root in the agrobacterium rhizogenes strain ncppb2659 is identified and characterized by its physical map. | 1987 | 2827205 |
| genetic analysis of the gentamicin resistance region of pph1ji and incorporation into a wide host range cloning vehicle. | a region of the incp plasmid pph1ji encoding resistance to gentamicin, spectinomycin, and streptomycin was characterized by subcloning, deletion, and insertion mutagenesis. approximate locations of these resistance determinants were established. a 1.6-kb hindiii-sphi segment of this region expresses gentamicin resistance (gmr) in escherichia coli when inserted into various plasmid vectors; this dna segment encodes a polypeptide of 17.5 kda. incorporation of this fragment into an incp cloning veh ... | 1987 | 2827208 |
| 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 ... | 1988 | 2828335 |
| site-directed tn5 and transplacement mutagenesis: methods to identify symbiotic nitrogen fixation genes in slow-growing rhizobium. | | 1987 | 2828853 |
| seed-transmissible expression of mammalian metallothionein in transgenic tobacco. | a binary plasmid was constructed to contain the mouse metallothionein c-dna, the constitutive 35s promoter from cauliflower mosaic virus, the polyadenylation signal from the pea rbcs-e9 gene and several selectable markers. the plasmid was transferred to agrobacterium tumefaciens and the leaf disc method was used to transform tobacco. callus and shoots were regenerated in the presence of kanamycin and transformed plants were obtained. southern, northern and western blot analysis demonstrated inte ... | 1988 | 2829879 |
| mapping of agrobacterium tumefaciens chromosomal genes affecting cellulose synthesis and bacterial attachment to host cells. | six chromosomal transposon mutations in agrobacterium tumefaciens which result in an inability to synthesize cellulose fibrils were mapped to the vicinity of trp-2 and met-6. mutations which result in an inability to attach to plant cells, attc43 and attc69, also mapped in this region, as did one tn5 mutation which caused overproduction of cellulose. another cellulose overproduction mutation mapped at a distance and was closely linked to ilv-13. the results suggest that there is a region of the ... | 1988 | 2830241 |
| studies on the introduction and mobility of the maize activator element in arabidopsis thaliana and daucus carota. | we have co-transformed carrot (daucus carota) and arabidopsis thaliana with an agrobacterium tumefaciens non-tumorigenic t-dna carrying the maize transposable element activator (ac) and an agrobacterium rhizogenes ri t-dna. we present evidence that the ac element transposes in transformed root or root-derived callus cultures of both species. we show that fertile plants can be regenerated from transformed, root-derived callus cultures of arabidopsis, demonstrating the utility of the ri plasmid fo ... | 1987 | 2832144 |
| 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 ... | 1988 | 2832362 |
| 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 ... | 1988 | 2832367 |
| 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 ... | 1988 | 2832379 |
| 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 ... | 1988 | 2832384 |
| 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 ... | 1988 | 2833161 |
| 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 ... | 1988 | 2834732 |
| 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 ... | 1988 | 2836366 |
| 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 ... | 1988 | 2836706 |
| 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 ... | 1988 | 2837739 |
| 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 ... | 1988 | 2838383 |
| 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 ... | 1988 | 2838452 |
| 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 ... | 1988 | 2838460 |
| 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 ... | 1988 | 2840554 |
| 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 ... | 1988 | 2840948 |
| 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 ... | 1988 | 2841284 |
| 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 ... | 1988 | 2842062 |
| 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 ... | 1988 | 2842300 |
| 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 ... | 1988 | 2842306 |
| 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 ... | 1988 | 2842307 |
| 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 ... | 1988 | 2842308 |
| 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. | 1988 | 2842320 |