| differential regulation of the expression in transgenic tobacco of the gene for beta-glucuronidase under the control of the 5'-upstream regions of two catalase genes from castor bean. | the regulatory functions of the 5'-flanking regions of two genes for catalase (cat1 and cat2) from castor bean were analyzed in transgenic tobacco plants that carried fusion constructs that included the gene for beta-glucuronidase (gus) for escherichia coli. dry mature seeds from transgenic plants carrying the cat1-gus or cat2-gus constructs, in which the gus gene was fused to the 5'-flanking region of cat1 or cat2, respectively, contained significant gus activity, indicating that the promoters ... | 1995 | 7767601 |
| characterization of the structural elements in lipid a required for binding of a recombinant fragment of bactericidal/permeability-increasing protein rbpi23. | both human bactericidal/permeability-increasing protein (bpi) and a recombinant amino-terminal fragment of bpi (rbpi23) have been shown to bind with high affinity to the lipid a region of lipopolysaccharide (lps) (h. gazzano-santoro, j. b. parent, l. grinna, a. horwitz, t. parsons, g. theofan, p. elsbach, j. weiss, and p. j. conlon, infect. immun. 60:4754-4761, 1992). in the present study, lipid a preparations derived from bacterial lps as well as synthetic lipid a's and various lipid a analogs ... | 1995 | 7768599 |
| fermentative and aerobic metabolism in rhizobium etli. | strains of rhizobium etli, rhizobium meliloti, and rhizobium tropici decreased their capacity to grow after successive subcultures in minimal medium, with a pattern characteristic for each species. during the growth of r. etli ce 3 in minimal medium (mm), a fermentation-like response was apparent: the o2 content was reduced and, simultaneously, organic acids and amino acids were excreted and poly-beta-hydroxybutyrate (phb) was accumulated. some of the organic acids excreted into the medium were ... | 1995 | 7768801 |
| characterization, nucleotide sequence, and conserved genomic locations of insertion sequence isrm5 in rhizobium meliloti. | a target for isrm3 transposition in rhizobium meliloti iz450 is another insertion sequence element, named isrm5. isrm5 is 1,340 bp in length and possesses terminal inverted repeats of unequal lengths (27 and 28 bp) and contain five mismatches. an open reading frame that spans 89% of the length of one dna strand encodes a putative transposase with significant similarity to the putative transposases of 11 insertion sequence elements from diverse bacterial species, including isrm3 from r. meliloti. ... | 1995 | 7768811 |
| isolation and characterisation of genes for sulphate activation and reduction in aspergillus nidulans: implications for evolution of an allosteric control region by gene duplication. | a region of the aspergillus nidulans genome carrying the sa and sc genes, encoding paps reductase and atp sulphurylase, respectively, was isolated by transformation of an sa mutant with a cosmid library. the genes were subcloned and their functions confirmed by retransformation and complementation of a. nidulans strains carrying sa and sc mutations. the physical distance of 2 kb between the genes corresponds to a genetic distance of 1 cm. while the deduced amino acid sequence of the sa gene prod ... | 1995 | 7770049 |
| transfer of t-dna from agrobacterium to the plant cell. | agrobacterium tumefaciens is the causative agent of crown gall, a disease of dicotyledonous plants characterized by a tumorous phenotype. earlier in this century, scientific interest in a. tumefaciens was based on the possibility that the study of plant tumors might reveal mechanisms that were also operating in animal neoplasia. in the recent past, the tumorous growth was shown to result from the expression of genes coded for by a dna segment of bacterial origin that was transferred and became s ... | 1995 | 7770515 |
| genetic regulation of nitrogen fixation in rhizobium meliloti. | the soil bacterium rhizobium meliloti fixes dinitrogen when associated with root nodules formed on its plant host, medicago sativa (alfalfa). the expression of most of the known genes required for nitrogen fixation (nif and fix genes), including the structural genes for nitrogenase, is induced in response to a decrease in oxygen concentration. induction of nif and fix gene expression by low oxygen is physiologically relevant because a low-oxygen environment is maintained in root nodules to preve ... | 1994 | 7772292 |
| the nods gene of rhizobium tropici strain ciat899 is necessary for nodulation on phaseolus vulgaris and on leucaena leucocephala. | rhizobium tropici strain ciat899 induces nitrogen-fixing nodules on the roots of a wide range of tropical legumes, including phaseolus vulgaris and leucaena leucocephala. previously, a dna region of the ciat899 psym plasmid containing the common nodulation genes nodabc and one of the nodd alleles was characterized (p. van rhijn, b. feys, c. verreth, and j. vanderleyden, j. bacteriol. 175: 438-447, 1993). as reported here, the region immediately downstream of nodc contains the nodsu genes. the nu ... | 1995 | 7772799 |
| broad resistance to tospoviruses in transgenic tobacco plants expressing three tospoviral nucleoprotein gene sequences. | transgenic tobacco plants have been obtained expressing nucleoprotein (n) gene sequences of three different tospoviruses known to affect vegetable crops: tomato spotted wilt virus (tswv), tomato chlorotic spot virus (tcsv), and groundnut ringspot virus (grsv). the chimeric plant transformation vector used comprised the three viral n gene sequences, each with a copy of the camv 35s promoter and the nos terminator. despite the high levels of homology between the different n gene sequences (74-82%) ... | 1995 | 7772807 |
| a novel ti-plasmid-convertible lambda phage vector system suitable for gene isolation by genetic complementation of arabidopsis thaliana mutants. | a new lambda phage vector system, lambda ti, has been constructed to facilitate genetic complementation of higher plant mutations. the lambda ti vectors are stable, and by using the cre-lox site-specific recombination, are automatically convertible into ti-plasmid binary vectors which are capable of expressing genes in higher plants. two lambda ti vectors were constructed: (i) lambda ti1, which can generate a ti-plasmid that contains the cauliflower mosaic virus (camv) 35s promoter and is suitab ... | 1995 | 7773312 |
| is292: a novel insertion element from agrobacterium. | a new insertion sequence, is292, located in the 6b gene of a nopaline-type agrobacterium strain (x88-292) isolated from poplar was identified and sequenced. is292 is 2494 bp long, has 21 bp inverted terminal repeats with two mismatches, and generates 10 bp direct repeats upon integration. no sequence similarity was found between is292 and other insertion elements associated with agrobacterium, but it shows strong similarity with isr/1 from rhizobium leguminosarum bv. viciae. the occurrence of is ... | 1995 | 7773388 |
| characterization of chitin synthase 2 of saccharomyces cerevisiae. implication of two highly conserved domains as possible catalytic sites. | chitin synthase 2 of saccharomyces cerevisiae was characterized by means of site-directed mutagenesis and subsequent expression of the mutant enzymes in yeast cells. chitin synthase 2 shares a region whose sequence is highly conserved in all chitin synthases. substitutions of conserved amino acids in this region with alanine (alanine scanning) identified two domains in which any conserved amino acid could not be replaced by alanine to retain enzyme activity. these two domains contained unique se ... | 1995 | 7775457 |
| symbiotic induction of a mads-box gene during development of alfalfa root nodules. | in response to infection by rhizobium, highly differentiated organs called nodules form on legume roots. within these organs, the symbiotic association between the host plant and bacteria is established. a putative plant transcription factor, nmh7, has been identified in alfalfa root nodules. nmh7 contains a mads-box dna-binding region and shows homology to flower homeotic genes. this gene is a member of a multigene family in alfalfa and was identified on the basis of nucleic acid homology to pl ... | 1995 | 7777496 |
| recombination between prokaryotic and eukaryotic dna: integration of agrobacterium tumefaciens t-dna into the plant genome. | | 1995 | 7779513 |
| rhizobial lipo-oligosaccharide nodulation factors: multidimensional chromatographic analysis of symbiotic signals involved in the development of legume root nodules. | nod factors are a group of biologically active oligosaccharide signals that are secreted by symbiotically competent bacteria of the family rhizobiaceae. their biosynthesis is determined by rhizobial nodulation (nod) genes, and is specifically induced in response to flavonoids secreted from the roots of host leguminous plants. the biological activity of nod factors on these host legumes dramatically mimics the early developmental symptoms of the rhizobium-legume symbiosis including, amongst other ... | 1995 | 7780198 |
| pleiotropic effect of fluoranthene on anthocyanin synthesis and nodulation of medicago sativa is reversed by the plant flavone luteolin. | | 1995 | 7780203 |
| ntrbc-dependent expression from the rhizobium meliloti dcta promoter in escherichia coli. | effects of the two-component sensor-regulator pairs dctbd and ntrbc upon the expression of a dcta::phoa fusion from rhizobium meliloti were determined under excess and limiting nitrogen concentrations in escherichia coli. results indicated that ntrbc affected transcription from the dcta promoter on a number of regulatory levels and under different physiological conditions in the heterologous host. however, ntrbc-dependent cross-talk was not observed in free-living r. meliloti under the condition ... | 1995 | 7781970 |
| construction and characterization of a rhizobium leguminosarum biovar viciae strain designed to assess horizontal gene transfer in the environment. | an integration vector was developed which inserts cloned dna in a non-essential site of the rhizobium leguminosarum biovar viciae chromosome. the expression of integrated genes is under the control of the constitutive neomycin phosphotransferase ii (nptii) promoter of transposon tn5. the design of the vector ensures that loss of vector sequences can be detected, enabling selection of progeny containing only the requisite dna. the newly constructed vector was employed to insert the escherichia co ... | 1995 | 7781972 |
| structural identification of the lipo-chitin oligosaccharide nodulation signals of rhizobium loti. | rhizobium loti is a fast-growing rhizobium species that has been described as a microsymbiont of plants of the genus lotus. nodulation studies show that lotus plants are nodulated by r. loti, but not by most other rhizobium strains, indicating that r. loti produces specific lipo-chitin oligosaccharides (lcos) which are necessary for the nodulation of lotus plants. the lcos produced by five different rhizobium loti strains have been purified and were shown to be n-acetylglucosamine pentasaccharid ... | 1995 | 7783635 |
| nolr controls expression of the rhizobium meliloti nodulation genes involved in the core nod factor synthesis. | the synthesis of rhizobium meliloti nod signal molecules, encoded by the nod gene products, is finely regulated. a negative control of plasmid-borne nod gene expression is provided by the nolr repressor encoded by the chromosomal nolr gene. nolr was previously shown to downregulate the expression of the activator nodd1 gene and the common nodabc operon by binding to an overlapping region of the two promoters adjacent to the n1 nod-box (kondorosi et al., 1989). we demonstrate here that nolr also ... | 1995 | 7783644 |
| expression of agrobacterium rhizogenes auxin biosynthesis genes in transgenic tobacco plants. | plant oncogenes aux1 and aux2 carried by the tr-dna of agrobacterium rhizogenes strain a4 encode two enzymes involved in the auxin biosynthesis pathway in transformed plant cells. the short divergent promoter region between the two aux-coding sequences contains the main regulatory elements. this region was fused to the uida reporter gene and introduced into nicotiana tabacum in order to investigate the regulation and the tissue specificity of these genes. neither wound nor hormone induction coul ... | 1995 | 7787177 |
| a general method for detecting and sizing large plasmids. | we have devised a method for detecting and estimating the sizes of large bacterial plasmids in the presence of genomic dna by pulsed-field gel electrophoresis (pfge). bacteria harboring plasmids were embedded in agarose and lysed using a rapid protocol. plugs were incubated with s1 nuclease and subjected to pfge in agarose gels. s1 nuclease converted supercoiled plasmids into full-length linear molecules. large plasmids migrated as discrete bands that were readily observed after ethidium stainin ... | 1995 | 7793624 |
| chemical characterization of two lipopolysaccharide species isolated from rhizobium loti nzp2213. | phenol-water extraction of rhizobium loti nzp2213 cells allowed a simultaneous isolation of two structurally different lipopolysaccharides from the aqueous (lps-w) and phenol (lps-p) phase that differed in their sodium deoxycholate-page pattern and composition. lps-w showed a profile indicating an r-type lps; lps-p had a cluster of poorly resolved bands in the high-molecular-weight region. lps-p contained large amounts of 6-deoxy-l-talose (6dtal), and a small amount of 2-o-methyl-6-deoxy-talose ... | 1995 | 7794102 |
| behavior of rhizobium meliloti in oxygen gradients. | rhizobium meliloti cells responded to an abrupt change in oxygen concentration by changing the cell speed (chemokinesis), but they did not alter the frequency at which swimming cells stopped briefly (aerotaxis). changes in cell speed upon stimulation with oxygen coincided with changes in membrane potential. the cells did not form an aerotactic band in a spatial gradient of oxygen as do the cells of other bacterial species. the fixl and fixj genes which encode a heme-containing protein kinase tha ... | 1995 | 7796916 |
| agrobacterium tumefaciens virb11 protein requires a consensus nucleotide-binding site for function in virulence. | virb11, one of the 11 genes of the virb operon, is absolutely required for transport of t-dna from agrobacterium tumefaciens into plant cells. previous studies reported that virb11 is an atpase with autophosphorylation activity and localizes to the inner membrane even though the protein does not contain the consensus n-terminal export sequence. in this report, we show that virb11 localizes to the inner membrane even in the absence of other tumor-inducing (ti) plasmid-encoded proteins. to facilit ... | 1995 | 7798144 |
| studies on the extracellular polysaccharide from agrobacterium radiobacter biovar i s-1231. | a strain s-1231 isolated from specimen of soil around beijing area is gram-negative, non-sporing, motile by peritrichous flagella. it produces exopolysaccharide succinoglycan from carbohydrates as its carbon source but not starch and cellulose. acid is produced during fermentation of glucose. growing for 12-24 hr, the cells are rods 0.7-0.8 x 1.3-1.5 microns, round ended, single or in pairs. colonies on nutrient agar plate are unpigmented, circular, raised, smooth and moist-glistening, edge enti ... | 1994 | 7803689 |
| synthetic studies toward pyruvate acetal-containing saccharides: en route to the efficient synthesis of rhizobium-related exopolysaccharide fragments. | the disaccharide building block benzyl o-(2,3-di-o-benzoyl-4,6-o-[(r)-1-(methoxycarbonyl) ethylidene]-beta-d-galactopyranosyl)-(1-->3)-2-o-benzoyl-4,6-o-[(s)-1- (methoxycarbonyl)ethylidene]-alpha-d-glucopyranoside (13), related to a rhizobium exopolysaccharide, was prepared by coupling various 4,6-o-[(r)-1-(methoxycarbonyl)ethylidene]-d-galactosyl donors (benzoyl-protected chloride 1, pivaloyl-protected chloride 2, and benzoyl-protected fluorides 3 and 4, and trichloroacetimidate 5) with benzyl ... | 1994 | 7805064 |
| structure of the unusual trisaccharide lipopolysaccharide component produced by a symbiotically defective mutant of rhizobium leguminosarum biovar viciae. | the structure of an unusual trisaccharide component isolated from the lipopolysaccharide (lps) of a tn5 mutant of rhizobium leguminosarum biovar viciae vf39 which is defective in infection of its host plant has been elucidated. this mutant also appears to be defective in the synthesis of a tetrasaccharide component normally synthesized by the wild-type organism. the three glycosyl components are galactose, mannose, and 3-deoxy-d-manno-2-octulosonic acid (kdo). mannose is linked to the 5-position ... | 1994 | 7805065 |
| agrobacterium vitis nopaline ti plasmid ptiab4: relationship to other ti plasmids and t-dna structure. | the ti plasmid of the agrobacterium vitis nopaline-type strain ab4 was subcloned and mapped. several regions of the 157 kb ti plasmid are similar or identical to parts of the a. vitis octopine/cucumopine (o/c)-type ti plasmids, and other regions are homologous to the nopaline-type ti plasmid ptic58. the t-dna of ptiab4 is a chimaeric structure of recent origin: the left part is 99.2% homologous to the left part of the ta-dna of the o/c-type ti plasmids, while the right part is 97.1% homologous t ... | 1994 | 7808399 |
| interspecies regulation of the reca gene of gram-negative bacteria lacking an e. coli-like sos operator. | the reca genes of agrobacterium tumefaciens, rhizobium meliloti, rhizobium phaseoli and rhodobacter sphaeroides, species belonging to the alpha-group bacteria of the proteobacteria class, have been fused in vitro to the lacz gene of escherichia coli. by using a mini-tn5 transposon derivative, each of these reca-lacz fusions was introduced into the chromosome of each of the four species, and into that of e. coli. the reca genes of three of the alpha bacteria are induced by dna damage when inserte ... | 1994 | 7808403 |
| the urease structural gene urea in rhizobium meliloti is preceded by an open reading frame necessary for urease activity. | an open reading frame (orf1) located upstream of the urease structural gene urea in rhizobium meliloti strain ak631 was cloned and characterized by dna sequencing. comparison of the amino acid sequence revealed partial homology with the urease accessory gene ured of klebsiella aerogenes and proteus mirabilis. mutational analysis of orf1 showed that the gene is necessary for urease activity. its function is still unknown. | 1994 | 7813887 |
| a new regulatory element modulates homoserine lactone-mediated autoinduction of ti plasmid conjugal transfer. | conjugal transfer of the agrobacterium tumefaciens nopaline-type ti plasmid ptic58 is induced by agrocinopines a and b, opines secreted by crown gall tumors induced by the bacterium. this regulation functions through the transcriptional repressor, accr. however, actual transcription of the tra genes is regulated by autoinduction through the activator trar and the substituted homoserine lactone second messenger, agrobacterium autoinducer (aai). we have identified a new regulatory element that mod ... | 1995 | 7814335 |
| phylogeny of sym plasmids of rhizobia by pcr-based sequencing of a nodc segment. | to understand the host specificity of rhizobia and the relationship between the evolution of sym plasmids and that of host plants, we determined partial nodc sequences of 10 representative rhizobium strains and then constructed an evolutionary tree for the deduced amino acid sequences with four published sequences. these coding sequences yield a phylogenetic tree similar to that for leghemoglobin of host plants, suggesting that the evolution of common nodulation genes may be linked to host legum ... | 1995 | 7814339 |
| molecular characterization of the cai operon necessary for carnitine metabolism in escherichia coli. | the sequence encompassing the cai genes of escherichia coli, which encode the carnitine pathway, has been determined. apart from the already identified caib gene coding for the carnitine dehydratase, five additional open reading frames were identified. they belong to the caitabcde operon, which was shown to be located at the first minute on the chromosome and transcribed during anaerobic growth in the presence of carnitine. the activity of carnitine dehydratase was dependent on the crp regulator ... | 1994 | 7815937 |
| structural identification of metabolites produced by the nodb and nodc proteins of rhizobium leguminosarum. | the rhizobium nodulation genes nodabc are involved in the synthesis of lipo-chitin oligosaccharides. we have analysed the metabolites which are produced in vivo and in vitro by rhizobium strains which express the single noda, nodb and nodc genes or combinations of the three. in vivo radioactive labelling experiments, in which d-[1-14c]-glucosamine was used as a precursor, followed by mass spectrometric analysis of the purified radiolabelled metabolic products, showed that rhizobium strains that ... | 1994 | 7815941 |
| oxygen sensitivity and metal ion-dependent transcriptional activation by nifa protein from rhizobium leguminosarum biovar trifolii. | the nifa protein from rhizobium leguminosarum biovar trifolii (r. trifolii) strain anu843 lacks an n-terminal domain present in homologous nifa proteins from other diazotrophs. the r. trifolii nifa gene product is unstable when expressed in escherichia coli under both aerobic and microaerobic conditions. stability is increased by fusion of additional amino acids to the n-terminus of the protein or by expression of nifa in sno mutant (presumed protease deficient) strains of e. coli. transcription ... | 1994 | 7816041 |
| in planta transformation of arabidopsis thaliana. | transformants of arabidopsis thaliana can be generated without using tissue culture techniques by cutting primary and secondary inflorescence shoots at their bases and inoculating the wound sites with agrobacterium tumefaciens suspensions. after three successive inoculations, treated plants are grown to maturity, harvested and the progeny screened for transformants on a selective medium. we have investigated the reproducibility and the overall efficiency of this simple in planta transformation p ... | 1994 | 7816046 |
| similarity between the rhizobium meliloti flip gene and pathogenicity-associated genes from animal and plant pathogens. | the nucleotide sequence of the rhizobium meliloti (rm) flip gene was determined. rm strains carrying insertions within this gene were non-motile, lacked flagella and formed normal n2-fixing root nodules on alfalfa. the flip protein showed similarity to several bacterial gene products involved in pathogenicity in both plant and animal pathogens. it is likely that all of these proteins share a common functional role in the secretion of specific proteins from bacterial cells. | 1995 | 7828930 |
| adp-ribosylation of rhizobium meliloti glutamine synthetase iii in vivo. | the control of glutamine synthetase (gs), the first enzyme in the main pathway used by rhizobium meliloti to assimilate ammonia, is central to cellular nitrogen metabolism. r. meliloti is unusual in having three distinct types of gs, including a unique gs, gsiii, that differs considerably from both gsi, which resembles other bacterial gs proteins and gsii, which resembles the gs found in eukaryotes. we show here that gsiii can be post-translationally modified in vivo by adp-ribosylation at an ar ... | 1995 | 7829494 |
| an essential virulence protein of agrobacterium tumefaciens, virb4, requires an intact mononucleotide binding domain to function in transfer of t-dna. | the 11 gene products of the agrobacterium tumefaciens virb operon, together with the vird4 protein, are proposed to form a membrane complex which mediates the transfer of t-dna to plant cells. this study examined one putative component of that complex, virb4. a deletion of the virb4 gene on the ti plasmid ptia6nc was constructed by replacing the virb4 gene with the kanamycin resistance-conferring nptii gene. the virb4 gene was found to be necessary for virulence on plants and for the transfer of ... | 1994 | 7830718 |
| production of chemicals using genetically transformed plant organs. | | 1994 | 7832529 |
| shikonin production by extractive cultivation in transformed-suspension and hairy root cultures of lithospermum erythrorhizon. | effects of in situ extraction, fungal elicitation, a permeabilizing agent, and the oxygen transfer rate on shikonin production in transformed suspension and hairy root cultures of lithospermum erythrorhizon were studied. shikonin production with in situ extraction in transformed cell and hairy root cultures by n-hexadecane was 7.6 and 3 times higher than those of the control culture. shikonin production of transformed l. erythrohizon increased with the enhanced gas exchange, and in situ extracti ... | 1994 | 7832530 |
| initiation of agrobacterium tumefaciens t-dna processing. purified proteins vird1 and vird2 catalyze site- and strand-specific cleavage of superhelical t-border dna in vitro. | t-dna processing during agroinfection of plants is initiated by site- and strand-specific incision at the t-dna border sequences of the ti plasmid. two proteins are required for this reaction: vird2 (49.6 kda), catalyzing a site-specific cleaving-joining reaction on single-stranded dna in vitro (pansegrau, w., schoumacher, f., hohn, b., and lanka, e. (1993) proc. natl. acad. sci. u.s.a. 90, 11538-11542), and vird1 (16.1 kda), an accessory protein required for vird2-mediated specific cleavage of ... | 1995 | 7836390 |
| nmr analysis of succinoglycans from different microbial sources: partial assignment of their 1h and 13c nmr spectra and location of the succinate and the acetate groups. | in order to obtain information on the location of succinate and acetate groups, comparative nmr analyses were carried out on succinoglycans from different microbial sources by using conventional and advanced nmr techniques. in particular, one-dimensional, 1h and 13c nmr spectra were recorded for qualitative and quantitative analysis on native high-molecular-weight succinoglycans (both in the na+ salt and free-acid forms) from pseudomonas sp. ncib 11592, agrobacterium radiobacter a201-25, rhizobi ... | 1994 | 7842440 |
| molecular and genetic characterization of the rhizopine catabolism (mocabrc) genes of rhizobium meliloti l5-30. | rhizopine (l-3-o-methyl-scyllo-inosamine, 3-o-msi) is a symbiosis-specific compound, which is synthesized in nitrogen-fixing nodules of medicago sativa induced by rhizobium meliloti strain l5-30. 3-o-msi is thought to function as an unusual growth substrate for r. meliloti l5-30, which carries a locus (mos) responsible for its synthesis closely linked to a locus (moc) responsible for its degradation. here, the essential moc genes were delimited by tn5 mutagenesis and shown to be organized into t ... | 1994 | 7845353 |
| localization and topology of virb proteins of agrobacterium tumefaciens. | agrobacterium tumefaciens causes tumors on plants by transferring part of its ti (tumor inducing) plasmid, the t-dna or transferred dna, to plant cells. the virb operon, the largest operon of the virulence (vir) region located on the ti plasmid, is necessary for tumor induction on all plant species. previously, the complete nucleotide sequences of the virb operons of several ti plasmids of a. tumefaciens were determined. the 11 predicted proteins mostly have signal sequences and/or hydrophobic d ... | 1994 | 7846145 |
| construction and characterization of a chimeric beta-glucosidase. | the amino acid sequences of beta-glucosidases from cellvibrio gilvus and agrobacterium tumefaciens show significant similarity in most of the parts. however, the ph/temperature optima and stabilities of the two enzymes are quite different. c. gilvus beta-glucosidase exhibits an optimum ph of 6.2-6.4 and temperature of 35 degrees c, whereas the corresponding values for a. tumefaciens are 7.2-7.4 and 60 degrees c respectively. to analyse these properties further, a chimeric beta-glucosidase was co ... | 1995 | 7848268 |
| the in vitro biosynthesis of functional nodulation factors (nod rm) produced by rhizobium meliloti 1021. | rhizobium meliloti associates symbiotically with alfalfa by forming root nodules in which the bacteria reduce atmospheric n2 into products useful to both organisms. nod factors are signal molecules, lipooligosaccharides, produced by the bacteria that trigger nodule formation in the plant host. nod rm-1 consists of a beta-1,4-n-acetyl glucosamine tetrasaccharide from which the n-acetyl group at the non reducing end is replaced by a fatty acid and the n-acetyl glucosamine at the reducing end is su ... | 1994 | 7849552 |
| promoter tagging with a promoterless ipt gene leads to cytokinin-induced phenotypic variability in transgenic tobacco plants:implications of gene dosage effects. | tobacco plants have been transformed with a t-dna construct harboring a promoterless cytokinin-synthesizing ipt gene close to the right t-dna border. eighteen out of 85 transgenic clones displayed phenotypic alternations typical for an enhanced cytokinin production. northern blot analysis confirmed the transcriptional activation of the introduced gene by tagged plant promoters. the concentration of cytokinins, expressed as zeatinriboside equivalents, was increased up to sevenfold in transgenic t ... | 1994 | 7849758 |
| metabolic and structural changes in pseudomonas aeruginosa, achromobacter cdc and agrobacterium radiobacter cells injured in parenteral fluids. | the long term metabolic changes of three oxidase positive microorganisms (pseudomonas aeruginosa, agrobacterium radiobacter and achromobacter cdc) all isolated from aquatic environment, were defined after they were inoculated in three parenteral fluids: lactated ringer's solution, sodium chloride 0.9% and dextrose 5%. the number of microorganisms introduced into the parenteral products was adjusted to 10(5) bacteria/ml and left at room temperature (20-22 degrees c) for 30 days. their enzymatic a ... | 1994 | 7850451 |
| differentiation of brucella abortus bv. 1, 2, and 4, brucella melitensis, brucella ovis, and brucella suis bv. 1 by pcr. | several pcr assays which identify the genus brucella but do not discriminate among species have been reported. we describe a pcr assay that comprises five oligonucleotide primers which can identify selected biovars of four species of brucella. individual biovars within a species are not differentiated. the assay can identify three biovars (1, 2, and 4) of b. abortus, all three biovars of b. melitensis, biovar 1 of b. suis, and all b. ovis biovars. these biovars include all of the brucella specie ... | 1994 | 7852552 |
| replication of the broad-host-range plasmid rk2: isolation and characterization of a spontaneous deletion mutant that can replicate in agrobacterium tumefaciens but not in escherichia coli. | two spontaneous deletions of a derivative of the broad-host-range plasmid rk2 were isolated from agrobacterium tumefaciens. the two deletions have lost 56 and 505 bp, respectively, near the origin of replication (oriv). of the eight 17-bp repeats present in the rk2 oriv, the smaller deletion has lost the first two while the larger one has lost the first three. the deletions led to a significant increase (3- to 7-fold) in plasmid copy number in a. tumefaciens, indicating their importance in copy ... | 1995 | 7854315 |
| oxygen regulation of expression of nitrogen fixation genes in rhizobium meliloti. | the sensor kinase fixl and the response regulator fixj induce the expression of the nitrogen fixation genes of rhizobium meliloti in response to microaerobiosis, which is a characteristic feature of the plant root nodule interior where the bacteria fix nitrogen. the kinase activity of a purified, soluble derivative of the membrane-bound hemoprotein fixl, designated fixl*, is stimulated under low oxygen conditions, thus increasing fixj-phosphate levels. fixj-phosphate is a potent transcriptional ... | 1994 | 7855432 |
| host recognition by the vira, virg two-component regulatory proteins of agrobacterium tumefaciens. | agrobacterium tumefaciens contains about 25 vir genes localized on a 200-kb tumour-inducing (ti) plasmid that direct a conjugation-like transfer of tumorigenic dna from the bacterium to the nuclei of infected plant cells. these genes are strongly and coordinately induced during infection in response to three different classes of stimuli which are thought to be key chemical features of a typical wound site. these stimuli are (i) guaiacol and syringol derivatives such as acetosyringone, (ii) sugar ... | 1994 | 7855433 |
| characteristics of rhizobium tianshanense sp. nov., a moderately and slowly growing root nodule bacterium isolated from an arid saline environment in xinjiang, people's republic of china. | we performed a numerical analysis of 148 phenotypic characteristics of 20 strains of root nodule bacteria isolated from an arid saline desert soil in the xinjiang region of northwestern people's republic of china and compared these organisms with 28 rhizobium and bradyrhizobium strains obtained from different regions of the people's republic of china and from other countries, including nine type strains of different species. all of the strains examined clustered into two groups at a similarity l ... | 1995 | 7857795 |
| signal molecules involved in plant embryogenesis. | in plant embryogenesis, inductive interactions mediated by diffusable signal molecules are most likely of great importance. evidence has been presented that at late globular stages in plant embryogenesis, perturbation of the polar auxin transport results in abberrant embryo morphology. rhizobium lipooligosaccharides or nod factors are a newly discovered class of bacterial molecules that are able to trigger initial steps in root nodule development in legumes. part of the activity of nod factors m ... | 1994 | 7858192 |
| role of rhizobial lipo-chitin oligosaccharide signal molecules in root nodule organogenesis. | the role of oligosaccharide molecules in plant development is discussed. in particular the role of the rhizobial lipo-chitin oligosaccharide (lco) signal molecules in the development of the root nodule indicates that oligosaccharides play an important role in organogenesis in plants. recent results of the analyses of structures and of the biosynthesis of the lco molecules are summarized in this paper. the knowledge and technologies that resulted from these studies will be important tools for fur ... | 1994 | 7858197 |
| cytokinin metabolism: implications for regulation of plant growth and development. | | 1994 | 7858201 |
| the expression of a chimeric phaseolus vulgaris nodulin 30-gus gene is restricted to the rhizobially infected cells in transgenic lotus corniculatus nodules. | in phaseolus vulgaris there is a nodulin family, npv30, of ca. 30 kda, as detected in an in vitro translation assay [2]. we isolated a gene (npv30-1) for one of the members of this family. the nucleotide sequence of the promoter of npv30-1 contains nodule-specific motifs common to other late nodulin genes. the promoter was fused to the gus reporter gene; this chimeric fusion was introduced into lotus corniculatus via agrobacterium rhizogenes transformation. gus activity was only detected in the ... | 1994 | 7858234 |
| the genetic and chemical basis of recognition in the agrobacterium: plant interaction. | | 1994 | 7859503 |
| does rhizobium avoid the host response? | | 1994 | 7859504 |
| genes required for cellulose synthesis in agrobacterium tumefaciens. | a region of the chromosome of agrobacterium tumefaciens 11 kb long containing two operons required for cellulose synthesis and a part of a gene homologous to the fixr gene of bradyrhizobium japonicum has been sequenced. one of the cellulose synthesis operons contained a gene (cela) homologous to the cellulose synthase (bsca) gene of acetobacter xylinum. the same operon also contained a gene (celc) homologous to endoglucanase genes from a. xylinum, cellulomonas uda, and erwinia chrysanthemi. the ... | 1995 | 7860585 |
| mechanism of cellulose synthesis in agrobacterium tumefaciens. | extracts of agrobacterium tumefaciens incorporated udp-[14c]glucose into cellulose. when the extracts were fractionated into membrane and soluble components, neither fraction was able to synthesize cellulose. a combination of the membrane and soluble fractions restored the activity found in the original extracts. extracts of cellulose-minus mutants showed no significant incorporation of udp-glucose into cellulose. when mixtures of the extracts were made, the mutants were found to fall into two g ... | 1995 | 7860586 |
| the octopine-type ti plasmid ptia6 of agrobacterium tumefaciens contains a gene homologous to the chromosomal virulence gene acvb. | although the majority of genes required for the transfer of t-dna from agrobacterium tumefaciens to plant nuclei are located on the ti plasmid, some chromosomal genes, including the recently described acvb gene, are also required. we show that acvb shows 50% identity with the product of an open reading frame, designated virj, that is found between the vira and virb genes in the octopine-type ti plasmid ptia6. this reading frame is not found in the nopaline-type ti plasmid ptic58. acvb is require ... | 1995 | 7860597 |
| discrete amplifiable regions (amplicons) in the symbiotic plasmid of rhizobium etli cfn42. | frequent tandem amplification of defined regions of the genome, called amplicons, is a common characteristic in the genomes of some rhizobium species, such as rhizobium etli. in order to map these zones in a model rhizobium replicon, we undertook an analysis of the plasticity patterns fostered by amplicons in the psym (390 kb) of r. etli cfn42. data presented in this article indicate the presence of four amplicons in psym, used for the generation of tandem amplifications and deletions. the ampli ... | 1995 | 7860608 |
| enzymatic radiolabelling to a high specific activity of legume lipo-oligosaccharidic nodulation factors from rhizobium meliloti. | in this paper we describe the two-step coupled 35s-radiolabelling of the lipo-oligosaccharidic nodulation (nod) factors of the bacterium rhizobium meliloti to a specific radioactivity of 800 ci/mmol. these radiolabelled nod factors bind to a particulate fraction from roots of the bacterium's symbiotic host, medicago truncatula, with an equilibrium dissociation constant (kd) of 117 nm, similar to that observed with a synthetic tritiated ligand. the first step of the 35s-labelling involves the syn ... | 1995 | 7864819 |
| identification of several soybean cytosolic glutamine synthetase transcripts highly or specifically expressed in nodules: expression studies using one of the corresponding genes in transgenic lotus corniculatus. | a dna fragment containing sequences hybridizing to the 5' region of gs15, a gene encoding soybean cytosolic glutamine synthetase, was isolated from a soybean genomic library. mapping and partial sequence analysis of the genomic clone revealed that it encodes a cytosolic gs gene, gs21, which is different from gs15. in parallel, a number of cdna clones encoding cytosolic gs were isolated using the coding region of pgs20 as a probe (pgs20 is a cdna clone which corresponds to a transcript of the gs1 ... | 1995 | 7865779 |
| identification of the agrobacterium tumefaciens c58 t-dna genes e and f and their impact on crown gall tumour formation. | dna sequence analysis of the 4.4 kilobases (kb) eco ri fragment 14 from t-dna of agrobacterium tumefaciens c58 revealed three open reading frames. one of them (945 bp) was supposed to encode the transcript e, the function of which has not been identified to date. furthermore, a so far undescribed open reading frame (1035 bp) was identified, located in the centre of the eco ri fragment 14 and termed gene f. the third open reading frame encoded the carboxy-terminal part of the agrocinopine synthas ... | 1995 | 7865795 |
| activity of the agrobacterium ti plasmid conjugal transfer regulator trar is inhibited by the product of the tram gene. | the agrobacterium ti plasmid tra regulon was previously found to be positively regulated by the trar protein in the presence of a diffusible n-acyl homoserine lactone designated agrobacterium autoinducer (aai). trar and aai are similar to luxr from vibrio fischeri and the vibrio autoinducer (vai), which regulate target bioluminescence (lux) genes in a cell density-dependent manner. we now show that tra genes are also regulated by a second protein, designated tram, which acts to antagonize trar-d ... | 1995 | 7868612 |
| the biosynthesis of rhizobial lipo-oligosaccharide nodulation signal molecules. | while a great deal has been learned concerning the biosynthesis of nod factors, there is much that remains to be determined. the functions of many nod proteins involved in adding the host-specific modifications to the nod factors remain to be unequivocally identified. some of the genes required for these modifications have not yet been isolated, e.g., those involved in carbamylation, or addition of d-ara. additionally the cellular location of most of the nod proteins and, concomitantly, the modi ... | 1994 | 7873777 |
| identification of a novel rhizobium meliloti nodulation efficiency nfe gene homolog of agrobacterium ornithine cyclodeaminase. | the nfe genes located on the large plasmid prmegr4b are involved in the nodulation efficiency and competitiveness of rhizobium meliloti gr4 on alfalfa roots. one hundred twenty-eight base-pairs downstream of nfe2 gene we found an open reading frame designated orfc, 970 bp long and potentially coding for a 320 amino acid long protein. the amino acid sequence of the putatively encoded orfc product shows similarity with ornithine cyclodeaminase (ocd) of agrobacterium tumefaciens an unusual enzyme t ... | 1994 | 7873778 |
| the regulation of exopolysaccharide production is important at two levels of nodule development in rhizobium meliloti. | we show that two exopolysaccharide overproducing tn5 mutants of rhizobium meliloti, exor and exos, have distinct symbiotic defects. while the exor mutant is unable to colonize nodules, the exos mutant retains that ability but varies in its ability to produce nitrogen-fixing nodules. we correlate these defects with different degrees of exopolysaccharide overproduction and growth impairment. we further show that the exor mutant is able to enter developing infection threads but is unable to invade ... | 1994 | 7873780 |
| acquisition and transmission of agrobacterium by the whitefly bemisia tabaci. | whiteflies transmit many different plant pathogens. we show here that the whitefly bemisia tabaci can also acquire agrobacterium tumefaciens from liquid cultures and from crown galls, and transmit it to plants. cloned tomato yellow leaf curl virus (tylcv) dna and a. tumefaciens tumor-inducing functions were used as reporter genes. whiteflies were fed through membranes on cultures of agrobacterium at::pty4 containing a dimeric copy of an infectious tylcv genomic clone between the t-dna borders of ... | 1994 | 7873782 |
| structure and transcription of genes within the beta-hbd-adh1 region of clostridium acetobutylicum p262. | the 1.2-kb dna fragment upstream of the linked beta-hbd (3-hydroxybutyryl-coa dehydrogenase) and adh1 (nadph-dependent alcohol dehydrogenase) genes from clostridium acetobutylicum p262 was sequenced. the upstream region contained an open reading frame (orfb) which was found to have 44% amino acid identity to the fixb gene products of rhizobium and azorhizobium. the beta-hbd and orfb genes were expressed during the acidogenic and solventogenic phases. the beta-hbd gene was transcribed on a single ... | 1995 | 7875566 |
| molecular and expression analysis of the rhizobium meliloti phosphoenolpyruvate carboxykinase (pcka) gene. | the pcka gene of rhizobium meliloti, encoding phosphoenolpyruvate carboxykinase, was isolated from a genomic cosmid library by complementation of the succinate growth phenotype of a pck- mutant. the gene region was mapped by subcloning and tn5 insertion mutagenesis. the dna sequence for a 2-kb region containing the structural gene and its promoter was determined. the pcka gene encodes as 536-amino-acid protein that shows homology with other atp-dependent pck enzymes. the promoter was identified ... | 1995 | 7883700 |
| a new agrobacterium strain isolated from aerial tumors on ficus benjamina l. | crown gall tumors, collected from branches of 1-year-old weeping fig (ficus benjamina l.) trees, yielded both tumorigenic and nonpathogenic agrobacteria. on the basis of classical diagnostic tests, the nonpathogenic strains were identified as agrobacterium tumefaciens, whereas the tumorigenic strains could not be assigned to any of the known terrestrial agrobacterium spp. the tumorigenic strains also differed from other members of the genus by producing more acid from mannitol. according to clus ... | 1995 | 7887626 |
| light-induced expression of ipt from agrobacterium tumefaciens results in cytokinin accumulation and osmotic stress symptoms in transgenic tobacco. | cytokinins are plant growth regulators that induce shoot formation, inhibit senescence and root growth. experiments with hydroponically grown tobacco plants, however, indicated that exogenously applied cytokinin led to the accumulation of proline and osmotin. these responses were also associated with environmental stress reactions, such as salt stress, in many plant species. to test whether increased endogenous cytokinin accumulation led to nacl stress symptoms, the gene ipt from agrobacterium t ... | 1995 | 7888614 |
| the oxygen sensor protein, fixl, of rhizobium meliloti. role of histidine residues in heme binding, phosphorylation, and signal transduction. | the two-component system sensor/response regulator pair, fixl/fixj, controls the expression of rhizobium meliloti nitrogen fixation (nif and fix) genes in response to changes in oxygen concentration. a truncated version of fixl, fixl*, is an oxygen-binding hemoprotein kinase that phosphorylates and dephosphorylates the nif and fix gene transcriptional activator, fixj. phosphorylation of fixj is required for optimal transcriptional activation, and anaerobic conditions in vitro result in a substan ... | 1995 | 7890634 |
| wild type rhizobium etli, a bean symbiont, produces acetyl-fucosylated, n-methylated, and carbamoylated nodulation factors. | phaseolus vulgaris (common bean) can be nodulated by different rhizobium species. a new species has been recently proposed: rhizobium etli. following transcriptional activation of the bacterial nodulation genes using naringenin or bean seed exudate, we have isolated, purified, and characterized r. etli extracellular nodulation factors. they are chitopentameric compounds that are n-methyl-n-vaccenoylated at their non-reducing end. at position 6 of the reducing n-acetyl-d-glucosamine, they are 4-o ... | 1995 | 7890737 |
| common ancestry between incn conjugal transfer genes and macromolecular export systems of plant and animal pathogens. | the dna sequence of a cluster of pkm101 conjugal transfer genes was determined and aligned with the genetic map of the plasmid. eighteen genes were identified, at least eight and probably 11 of which are required for efficient conjugation. these tra genes are homologous to and colinear with genes found in the virb operon of agrobacterium tumefaciens ti plasmids. seven pkm101 tra genes are also homologous to ptl genes of bordetella pertussis, which direct the export of pertussis toxin. we used tn ... | 1994 | 7891554 |
| the cconoqp gene cluster codes for a cb-type cytochrome oxidase that functions in aerobic respiration of rhodobacter capsulatus. | the genes for a new type of a haem-copper cytochrome oxidase were cloned from rhodobacter capsulatus strain 37b4, using the bradyrhizobium japonicum fixnoqp gene region as a hybridizing probe. four genes, probably organized in an operon (cconoqp), were identified; their products share extensive amino acid sequence similarity with the fixn, o, q and p proteins that have recently been shown to be the subunits of a cb-type oxidase. ccon is a b-type cytochrome, ccoo and ccop are membrane-bound mono- ... | 1994 | 7891558 |
| electrifying symbiosis. | | 1995 | 7892178 |
| structurally diverse chitolipooligosaccharide nod factors accumulate primarily in membranes of wild type rhizobium leguminosarum biovar trifolii. | the general view on rhizobium chitolipooligosaccharides (clos) is that they are made in very low levels as diffusible molecules and are primarily secreted by the bacteria into the extracellular milieu where they interact with the host. however, the structural and predicted physicochemical properties of these amphiphilic molecules led us to postulate that they should normally be targeted to bacterial membranes after synthesis. thus, we analyzed membrane lipid extracts of rhizobium leguminosarum b ... | 1995 | 7893680 |
| suspension culture of catharanthus roseus crown gall cell induced by agrobacterium c58. | in comparison with calli from leaf or stem, catharanthus roseus crown gall cell cultured on ms basic medium was superior in growth, total indole alkaloids and ajmalicine contents. the effects of illumination, cultural temperature, sucrose level of the medium and exogenous l-trp on the growth, total indole alkaloids and ajmalicine contents of c. roseus crown gall cell cultures were studied. the results will provide a theoretical basis for the attempt of using suspension cultures of c. roseus crow ... | 1994 | 7893941 |
| targeted recombination in plants using agrobacterium coincides with additional rearrangements at the target locus. | the use of agrobacterium for gene targeting in plants has been investigated. leaf protoplasts of five transgenic tobacco lines, containing a t-dna insertion with a defective npt-ii gene at different positions in the plant genome, were transformed via agrobacterium with a t-dna containing a npt-ii repair gene. after selection for kanamycin resistance and pcr analysis six recombinants were derived from four of the target lines. the recombination frequencies were similar for the different target li ... | 1995 | 7894502 |
| dna rearrangement associated with the integration of t-dna in tobacco: an example for multiple duplications of dna around the integration target. | transferred dna (t-dna) of the tumor-inducing (ti) plasmid is transferred from agrobacterium tumefaciens to plant cells and is stably integrated into the plant nuclear genome. by the inverse polymerase chain reaction dna fragments were amplified that contained the t-dna/plant dna junctions from the total dna of a transgenic tobacco plant that had a single copy of the t-dna in a repetitive region of its genome. a dna fragment containing the target site was amplified from the total dna of non-tran ... | 1995 | 7894506 |
| rhizobium leguminosarum nodulation gene (nod) expression is lowered by an allele-specific mutation in the dicarboxylate transport gene dctb. | to identify host genes that might influence nod (nodulation) gene expression in rhizobium leguminosarum, a nodc-phoa reporter plasmid (carrying nodd) was introduced into a chemically mutagenized population of a r. leguminosarum strain lacking a symbiotic plasmid. the transconjugants were screened for expression of alkaline phosphatase (phoa) on plates containing hesperetin, an inducer of nod genes, and a mutant with reduced expression was identified. when the nodc-phoa plasmid was cured from the ... | 1995 | 7894701 |
| signal transduction in the rhizobium meliloti dicarboxylic acid transport system. | the gene products of the rhizobium meliloti dctb and dctd genes, which control the expression of the c4-dicarboxylic acid transporter dcta, were overproduced in escherichia coli and purified. the purified sensor protein, dctb, was shown to have autophosphorylation activity in vitro and could subsequently phosphorylate the transcriptional activator, dctd. the presence of c4-dicarboxylic acids did not affect either reaction. in vitro experiments aimed at investigating 'crosstalk' between cognate c ... | 1995 | 7896073 |
| bacterial plant oncogenes: the rol genes' saga. | the rol genes are part of the t-dna which is transferred by agrobacterium rhizogenes in plant cells, causing neoplastic growth and differentiation. each of these bacterial oncogenes deeply influences plant development and is finely regulated once transferred into the plant host. both from the study of the effects and biochemical function of the rol genes and from the analysis of their regulation, important insight in plant development can be derived. some of the most intriguing aspects of past, ... | 1994 | 7896140 |
| factors affecting the inhibition by antisense rna of granule-bound starch synthase gene expression in potato. | inhibition of expression of specific genes by means of antisense rna is widely used, although little information is available regarding conditions that affect the efficacy of inhibition. in this study, inhibition of granule-bound starch synthase (gbss), a key enzyme in starch biosynthesis, is used as a model system. eleven antisense constructs derived from the full-length gbss cdna, the genomic gbss coding region (gdna) or fragments of each of these sequences, were analysed with respect to their ... | 1995 | 7898444 |
| reversible adp-ribosylation as a mechanism of enzyme regulation in procaryotes. | several cases of adp-ribosylation of endogenous proteins in procaryotes have been discovered and investigated. the most thoroughly studied example is the reversible adp-ribosylation of the dinitrogenase reductase from the photosynthetic bacterium rhodospirillum rubrum and related bacteria. a dinitrogenase reductase adp-ribosyltransferase (drat) and a dinitrogenase reductase adp-ribose glycohydrolase (drag) from r. rubrum have been isolated and characterized. the genes for these proteins have bee ... | 1994 | 7898454 |
| cloning and expression of flavonol synthase from petunia hybrida. | flavonols are important co-pigments in flower colour and are also essential for pollen tube growth. in petunia, flavonol synthesis is controlled by the fl locus. flavonol synthase (fls) belongs to the 2-oxoglutarate-dependent dioxygenase family. dioxygenase gene fragments were amplified by pcr on cdna made from flfl and flfl flowers using degenerate primers designed from conserved dioxygenase sequences. a petunia petal cdna library was screened for clones that hybridized more strongly to the fl ... | 1993 | 7904213 |
| a protein involved in stabilization of a large non-symbiotic plasmid of rhizobium meliloti shows homology to eukaryotic cytoskeletal proteins and dna-binding proteins. | an open reading frame, denoted orf2, present in the replication and stabilization region of plasmid prmegr4a of rhizobium meliloti gr4, was identified by sequence analysis. this 1068-bp orf2 potentially codes for a 356-amino-acid protein that seems to play a role in prmegr4a stabilization. similarities of the orf2-encoded protein with eukaryotic cytoskeletal proteins and dna-binding proteins were found. | 1994 | 7906665 |
| analysis of the chromosomal distribution of transposon-carrying t-dnas in tomato using the inverse polymerase chain reaction. | we are developing a system for isolating tomato genes by transposon mutagenesis. in maize and tobacco, the transposon activator (ac) transposes preferentially to genetically linked sites. to identify transposons linked to various target genes, we have determined the rflp map locations of ac- and dissociation (ds)-carrying t-dnas in a number of transformants. t-dna flanking sequences were isolated using the inverse polymerase chain reaction (ipcr) and located on the rflp map of tomato. the authen ... | 1994 | 7907167 |
| rhizobium leguminosarum contains multiple chaperonin (cpn60) genes. | we have examined the heat shock response of rhizobium leguminosarum. after normal growth at 28 degrees c, a 10 min heat shock at 37 degrees c induced the synthesis of proteins with approximate m(r) values of 90,000, 70,000, 60,000, 58,000, 19,000, 17,000 and 13,000. a monoclonal antibody raised against the e. coli cpn60 cross-reacted with proteins of m(r) 60,000 and 58,000 in r. leguminosarum, suggesting that both were cpn60 homologues. hybridization of an e. coli cpn60 probe to total dna from r ... | 1994 | 7909257 |
| regulation of nitrogen metabolism is altered in a glnb mutant strain of rhizobium leguminosarum. | we isolated a rhizobium leguminosarum mutant strain altered in the glnb gene. this event, which has never been described in the rhizobiaceae, is rare in comparison to mutants isolated in the contiguous gene, glna. the glnb mutation removes the glnba promoter but in vivo does not prevent glna expression from its own promoter, which is not nitrogen regulated. the glnb mutant strain does not grow on nitrate as a sole nitrogen source and it is nod+, fix+. two -24/-12 promoters, for the glnii and gln ... | 1994 | 7910937 |
| identification of agrobacterium strains by pcr-rflp analysis of pti and chromosomal regions. | chromosomes and ti plasmids of 41 agrobacterium strains, belonging to biovars 1, 2, 3, and agrobacterium rubi species were characterized by the restriction fragment length polymorphism of pcr-amplified dnas. profiles that were obtained by the analysis of the amplified 16s rdna confirmed the grouping of the strains according to their species. higher polymorphism was detected in the intergenic spacer between the 16s rdna and 23s rdna genes, allowing efficient discrimination of strains. identificat ... | 1994 | 7911654 |
| rhizobium meliloti adenylate cyclase: probing of a ntp-binding site common to cyclases and cation transporters. | alignments between amino acid sequences of eukaryotic adenylate (acase) and guanylate (gcase) cyclases and the prokaryotic rhizobium meliloti acase revealed four conserved regions. two were the target of site-directed mutagenesis. a positive charge at position 44 converted the enzyme to gcase, a negative charge at this position had no effect. a second modification indicated that residues 107 and 124 contribute to the nucleoside triphosphate binding pocket's conformation. this latter region was u ... | 1993 | 7912636 |
| promiscuous dna transfer system of agrobacterium tumefaciens: role of the virb operon in sex pilus assembly and synthesis. | conjugative transfer of dna that occurs between bacteria also operates between bacteria and higher organisms. the transfer of dna between gram-negative bacteria requires initial contact by a sex pilus followed by dna traversing four membranes (donor plus recipient) using a transmembrane pore. accumulating evidence suggests that transfer of the t-dna from agrobacterium tumefaciens to plants may also occur via a conjugative mechanism. the virb operon of the ti plasmid exhibits close homologies to ... | 1994 | 7914664 |
| genotypic and phenotypic diversity of rhizobium isolated from chickpea (cicer arietinum l.). | the diversity of 16 strains of chickpea-infective rhizobia from various geographical origins was analysed using genotypic and phenotypic approaches. multilocus enzyme electrophoresis was performed, and restriction fragment length polymorphisms of the amplified 16s + igs (intergenic spacer) rrna gene, assimilation of 147 carbon sources, antibiotic resistance, and tolerance to nacl and extreme ph values and temperatures were tested. these approaches had different discriminating powers. esterase po ... | 1994 | 7915190 |