| detection of alternative nitrogenases in aerobic gram-negative nitrogen-fixing bacteria. | strains of aerobic, microaerobic, nonsymbiotic, and symbiotic dinitrogen-fixing bacteria were screened for the presence of alternative nitrogenase (n2ase) genes by dna hybridization between genomic dna and dna encoding structural genes for components 1 of three different enzymes. a nifdk gene probe was used as a control to test for the presence of the commonly occurring mo-fe n2ase, a vnfdgk gene probe was used to show the presence of v-fe n2ase, and an anfdgk probe was used to detect fe n2ase. ... | 1991 | 1987127 |
| the exod gene of rhizobium meliloti encodes a novel function needed for alfalfa nodule invasion. | during the symbiotic interaction between alfalfa and the nitrogen-fixing bacterium rhizobium meliloti, the bacterium induces the formation of nodules on the plant roots and then invades these nodules. among the bacterial genes required for nodule invasion are the exo genes, involved in production of an extracellular polysaccharide, and the ndv genes, needed for production of a periplasmic cyclic glucan. mutations in the exod gene result in altered exopolysaccharide production and in a nodule inv ... | 1991 | 1987158 |
| exopolysaccharide mutants of rhizobium loti are fully effective on a determinate nodulating host but are ineffective on an indeterminate nodulating host. | by tn5 mutagenesis of rhizobium loti pn184 (nzp2037 str-1) and selection for nonfluorescence of colonies on calcofluor agar, eight independently generated expolysaccharide (eps) mutants (three smooth and five rough) were isolated. the parent strain, pn184, was found to produce an acidic eps. this eps was produced. with reduced o acetylation, by the smooth eps mutants but not by the rough eps mutants. lipopolysaccharide was isolated from all mutants and was identical to that of pn184 as defined b ... | 1991 | 1987168 |
| transport of nonmetabolizable opines by agrobacterium tumefaciens. | we have examined the uptake of [14c]octopine and [14c]nopaline by agrobacterium tumefaciens strains containing the c58 chromosomal background in medium suitable for the induction of vir genes. all strains tested could transport both of these opines, regardless of the presence or type of ti plasmid (octopine or nopaline) present in the bacterium. the transport of these opines required active cellular metabolism. nonradioactive octopine, nopaline, and arginine competed effectively with [14c]octopi ... | 1991 | 1987170 |
| visualization of bacterial flagella by video-enhanced light microscopy. | we have imaged individual flagellar filaments of escherichia coli, a motile streptococcus sp., and rhizobium meliloti by video-enhanced differential interference-contrast microscopy (nomarski dic) and computer-based image processing. this approach has advantages over existing methods in that filaments on living cells can be seen over their entire lengths. | 1991 | 1987174 |
| bradyrhizobium japonicum has two differentially regulated, functional homologs of the sigma 54 gene (rpon). | recognition of -24/-12-type promoters by rna polymerase requires a special sigma factor, sigma 54 (rpon ntra glnf). in the nitrogen-fixing soybean symbiont bradyrhizobium japonicum, two functional, highly conserved rpon genes (rpon1 and rpon2) were identified and sequenced. the two predicted b. japonicum rpon protein sequences were 87% identical, and both showed different levels of homology to the rpon proteins of other bacteria. downstream of rpon2 (but not of rpon1), two additional open readin ... | 1991 | 1991712 |
| controlled expression of the transcriptional activator gene virg in agrobacterium tumefaciens by using the escherichia coli lac promoter. | the agrobacterium virg protein is normally expressed from two promoters in response to multiple stimuli, including plant-released phenolics (at promoter p1) and acidic growth media (at promoter p2). to simplify the analysis of vir gene induction, we sought to create agrobacterium strains in which virg could be expressed in a controllable fashion. to study the possibility of using the lac promoter and repressor, we constructed a plasmid containing the lac promoter fused to the lacz structural gen ... | 1991 | 1991713 |
| novel organization of the common nodulation genes in rhizobium leguminosarum bv. phaseoli strains. | nodulation by rhizobium, bradyrhizobium, and azorhizobium species in the roots of legumes and nonlegumes requires the proper expression of plant genes and of both common and specific bacterial nodulation genes. the common nodabc genes form an operon or are physically mapped together in all species studied thus far. rhizobium leguminosarum bv. phaseoli strains are classified in two groups. the type i group has reiterated nifhdk genes and a narrow host range of nodulation. the type ii group has a ... | 1991 | 1991718 |
| high-frequency rearrangements in rhizobium leguminosarum bv. phaseoli plasmids. | high-frequency genomic rearrangements affecting the plasmids of rhizobium leguminosarum bv. phaseoli cfn42 were analyzed. this strain contains six large plasmids ranging in size from 200 to 600 kb. in the absence of any selective pressure, we found 11 strains from 320 analyzed colonies that presented different kinds of plasmid-borne rearrangements, including sequence amplification, deletion, cointegration, and loss of plasmids. these data support the concept that the r. leguminosarum bv. phaseol ... | 1991 | 1991727 |
| illegitimate recombination in plants: a model for t-dna integration. | agrobacterium tumefaciens is a soil bacterium capable of transferring dna (the t-dna) to the genome of higher plants, where it is then stably integrated. six t-dna inserts and their corresponding preinsertion sites were cloned from arabidopsis thaliana and analyzed. two t-dna integration events from nicotiana tabacum were included in the analysis. nucleotide sequence comparison of plant target sites before and after t-dna integration showed that the t-dna usually causes only a small (13-28 bp) d ... | 1991 | 1995418 |
| sequence identity in the nick regions of incp plasmid transfer origins and t-dna borders of agrobacterium ti plasmids. | the incp antibiotic-resistance plasmids transfer to a broad range of bacterial species. the rk2 origin of dna transfer (orit) consists of a 250-base-pair segment including the single-stranded cleavage site (nic) needed to generate the dna strand believed to be transferred. deletion derivatives and a bank of hydroxylamine-generated orit mutants were screened for loss of transferability. dna regions flanking both sides of nic are required for optimal transfer of the orit clone. of the chemically i ... | 1991 | 1996345 |
| the regulatory status of the fixl- and fixj-like genes in bradyrhizobium japonicum may be different from that in rhizobium meliloti. | the cloning, sequencing and mutational analysis of the bradyrhizobium japonicum symbiotic nitrogen fixation genes fixl and fixj are reported here. the two genes were adjacent and probably formed an operon, fixlj. the predicted fixl and fixj proteins, members of the two-component sensor/regulator family, were homologous over almost their entire lengths to the corresponding rhizobium meliloti proteins (approx. 50% identity). downstream of the b. japonicum fixj gene was found an open reading frame ... | 1991 | 2000090 |
| canonical ordered cosmid library of the symbiotic plasmid of rhizobium species ngr234. | many of the bacterial genes involved in nodulation (nod) and nitrogen fixation (nif) are dispersed over the 500-kilobase plasmid pngr234a of the broad host-range rhizobium species ngr234. as a first step toward generating a complete physical and genetic map of the plasmid, a full overlapping collection of cosmids was derived from a total genomic library. clones were aligned by combining fingerprinting, hybridization, and pulsed-field gel electrophoresis data. symbiotic loci were localized by pro ... | 1991 | 2000397 |
| t-dna integration: a mode of illegitimate recombination in plants. | transferred dna (t-dna) insertions of agrobacterium gene fusion vectors and corresponding insertional target sites were isolated from transgenic and wild type arabidopsis thaliana plants. nucleotide sequence comparison of wild type and t-dna-tagged genomic loci showed that t-dna integration resulted in target site deletions of 29-73 bp. in those cases where integrated t-dna segments turned out to be smaller than canonical ones, the break-points of target deletions and t-dna insertions overlapped ... | 1991 | 2001683 |
| a diffusible compound can enhance conjugal transfer of the ti plasmid in agrobacterium tumefaciens. | several octopine strains of agrobacterium tumefaciens were tested for ti plasmid (pti) transfer after induction by 400 micrograms of octopine per ml for 24 h. the strains could be divided into two groups, transfer efficient (trae) and transfer inefficient (traie); the respective rates of transfer were 0.77 x 10(-2) to 1.14 x 10(-2) and 0.33 x 10(-6) to 9.8 x 10(-6) plasmid transconjugant per donor cell. transfer efficiencies of traie strains were greatly increased when the time of induction was ... | 1991 | 2001991 |
| expression of two rhizobium meliloti flagellin genes and their contribution to the complex filament structure. | the complex flagellar filaments of rhizobium meliloti are composed of two related (87% identical) flagellins that are encoded by closely linked, separately transcribed genes, flaa and flab (e. pleier and r. schmitt, j. bacteriol. 171:1467-1475, 1989). to elucidate the role of the subunits, a and b, in assembling the complex filament, the wild-type alleles were replaced with defective ones containing a 2,249-bp deletion (accompanied by substitution of a kanamycin resistance cartridge), which elim ... | 1991 | 2002009 |
| inhibition of the expression of the gene for granule-bound starch synthase in potato by antisense constructs. | granule-bound starch synthase [gbss; ec 24.1.21] determines the presence of amylose in reserve starches. potato plants were transformed to produce antisense rna from a gene construct containing a full-length granule-bound starch synthase cdna in reverse orientation, fused between the cauliflower mosaic virus 35s promoter and the nopaline synthase terminator. the construct was integrated into the potato genome by agrobacterium rhizogenes-mediated transformation. inhibition of gbss activity in pot ... | 1991 | 2005870 |
| occurrence of lipid a variants with 27-hydroxyoctacosanoic acid in lipopolysaccharides from members of the family rhizobiaceae. | lipopolysaccharides (lpss) isolated from several strains of rhizobium, bradyrhizobium, agrobacterium, and azorhizobium were screened for the presence of 27-hydroxyoctacosanoic acid. the lpss from all strains, with the exception of azorhizobium caulinodans, contained various amounts of this long-chain hydroxy fatty acid in the lipid a fractions. analysis of the lipid a sugars revealed three types of backbones: those containing glucosamine (as found in rhizobium meliloti and rhizobium fredii), tho ... | 1991 | 2007543 |
| phylogeny of the phototrophic rhizobium strain btai1 by polymerase chain reaction-based sequencing of a 16s rrna gene segment. | a 260-bp segment of the dna that encodes 16s rrna, corresponding to positions 44 to 337 in the escherichia coli sequence, was amplified by the polymerase chain reaction and sequenced from each of 13 bacteria (rhizobia and purple phototrophs) in the alpha subdivision of the class proteobacteria. the phylogenetic tree calculated from differences in the sequenced segment conforms well to our expectations based on other previously published data. the sequence from btai1 (a recently described phototr ... | 1991 | 2007551 |
| nucleotide sequence analysis of a chloramphenicol-resistance determinant from agrobacterium tumefaciens and identification of its gene product. | the nucleotide sequence of a chloramphenicol-resistance (cmr) determinant from the gram- soil bacterium agrobacterium tumefaciens was determined, and its gene product was identified as cm acetyltransferase (cat). comparison of the amino acid sequences of the a. tumefaciens cat and various cat proteins of gram+ and gram- origin shows no homology between this and the other enzymes. | 1991 | 2013403 |
| construction of a mobilizable cloning vector for site-directed mutagenesis of gram-negative bacteria: application to rhizobium leguminosarum. | a mobilizable cloning vector was constructed from defined fragments to serve as a suicide plasmid for site-directed mutagenesis. the new vector, pkok4, closely resembles plasmid pbr325. however, the inverted duplication existing in the latter was not introduced. the useful cloning sites of pbr325 (ecori, hindiii, ecorv, bamhi, sali, psti and pvui) were retained and are located in one of the three resistance markers, apr, cmr or tcr, respectively. also, in pkok4 the cmr gene retains its own promo ... | 1991 | 2013412 |
| structural complexity of the symbiotic plasmid of rhizobium leguminosarum bv. phaseoli. | the complete physical map of the symbiotic plasmid of rhizobium leguminosarum bv. phaseoli strain cfn42 was established. the data support the concept that rhizobium symbiotic genes are part of a complex genomic structure which contains a large amount of reiterated dna sequences. this plasmid is a circular structure of 390 kb with approximately 10 families of internally reiterated dna sequences of two to three elements each. one family includes two directly oriented nitrogenase operons situated 1 ... | 1991 | 2013564 |
| amplification and deletion of a nod-nif region in the symbiotic plasmid of rhizobium phaseoli. | one remarkable characteristic of the genomes of some rhizobium species is the frequent occurrence of rearrangements. in some instances these rearrangements alter the symbiotic properties of the strains. however, no detailed molecular mechanisms have been proposed for the generation of these rearrangements. to understand the mechanisms involved in the formation of rearrangements in the genome of rhizobium phaseoli, we have designed a system which allows the positive selection for amplification an ... | 1991 | 2013567 |
| the virc and vird operons of the agrobacterium ti plasmid are regulated by the ros chromosomal gene: analysis of the cloned ros gene. | the ros chromosomal gene is present in octopine and nopaline strains of agrobacterium tumefaciens as well as in rhizobium meliloti. this gene encodes a 15.5-kda protein that specifically represses the virc and vird operons in the virulence region of the ti plasmid. the ros gene was cloned from a genomic bank by electroporation and complementation in agrobacterium cells. reporter fusion to the ros gene indicates that the level of transcription is controlled in part by autoregulation. a consensus ... | 1991 | 2013576 |
| sequences downstream from the transcriptional start site are essential for microaerobic, but not symbiotic, expression of the rhizobium meliloti nifhdk promoter. | deletion analysis studies have been carried out on the nifhdk promoter (p1) of r. meliloti in an attempt to determine sequences involved in the expression of this promoter under both free-living microaerobic and symbiotic conditions. deletion of a region downstream (+17 to +61) from the promoter element resulted in low levels of expression under free-living microaerobic conditions. however, wild-type levels of expression were obtained during symbiosis with alfalfa plants. the sequences in this r ... | 1991 | 2013999 |
| partial deletion of the rhizobium phaseoli cfn23 symbiotic plasmid implies a concomitant amplification of plasmid dna sequences. | rhizobium leguminosarum biovar phaseoli cfn23 loses its ability to nodulate beans at a high frequency because of a deletion of part of its symbiotic (psym) plasmid (soberón-chávez et al., 1986). we report here that at least 80 kb of psym are deleted upon loss of the symbiotic phenotype; the deletion removes the nitrogenase structural nifhdk and the common nodabc genes. the size of the deleted psym is not reduced, since it is accompanied by an amplification of other psym plasmid sequences. this g ... | 1991 | 2014006 |
| studies on heterologous expression of rhizobium meliloti nifa gene and oxygen sensitivity of its product. | when the r. meliloti (rm) nifa'-lacz fusion-carrying plasmids were introduced into the strains of agrobacterium tumefaciens, r. trifolii and r. astragalus, beta-galactosidase activity was demonstrated. however, activity was not induced by microaerobiosis. furthermore, r. meliloti nifa'-lacz fusion was also not expressed in the nodule bacteroids of r. trifolii and r. astragalus. we speculate that some factor(s) important for the induction of rm nifa presumed to be the fixlj regulatory system woul ... | 1991 | 2015065 |
| genetic and physical analysis of the nodd3 region of rhizobium meliloti. | the nodulation (nod) genes of the symbiont rhizobium meliloti are transcriptionally controlled by protein activators in the nodd gene family. while nodd1 and nodd2 act in concert with small molecular weight inducers provided by the host legume plant, nodd3 is an inducer-independent activator of the nod promoters. we determined the sequence of the nodd3 gene, confirmed the expression of a 35 kda protein in vitro, and determined the insertion points of five tn5 insertions in the region of the nodd ... | 1991 | 2017373 |
| isolation of the rhizobium leguminosarum nodf nodulation protein: nodf carries a 4'-phosphopantetheine prosthetic group. | rhizobium species produce a protein product of the nodf gene that has a limited but recognizable homology to the well-characterized acyl carrier protein (acp) of escherichia coli. nodf functions together with node in generating a host-specific response to the plant host in the interchange of signals leading to the effective nodulation of roots (h.p. spaink, j. weinman, m.a. djordjevic, c.a. wijffelman, r.j.h. okker, and b. j.j. lugtenberg, embo j. 8:2811-2818, 1989; b. scheres, c. van de wiel, a ... | 1991 | 2019559 |
| aspartate aminotransferase activity is required for aspartate catabolism and symbiotic nitrogen fixation in rhizobium meliloti. | a mutant of rhizobium meliloti, 4r3, which is unable to grow on aspartate has been isolated. the defect is specific to aspartate utilization, since 4r3 is not an auxotroph and grows as well as its parent strain on other carbon and nitrogen sources. the defect was correlated with an inability to fix nitrogen within nodules formed on alfalfa. transport of aspartate into the mutant cells was found to be normal. analysis of enzymes involved in aspartate catabolism showed a significantly lower level ... | 1991 | 2019560 |
| biosynthesis and excretion of cyclic glucans by rhizobium meliloti 1021. | cyclic beta-1,2-glucans produced by agrobacterium and rhizobium species play an important role in the interaction of these bacteria with plant hosts. in this study, we show that (i) the neutral cyclic glucans are the biosynthetic precursors of anionic cyclic glucans; (ii) the conversion of neutral to anionic glucans is much more rapid and more extensive in exponentially growing cultures than in cultures in the stationary phase, although the latter synthesize large amounts of glucan; and (iii) th ... | 1991 | 2019565 |
| molecular cloning and characterization of the reca gene of rhizobium phaseoli and construction of reca mutants. | the rhizobium phaseoli reca gene has been cloned by interspecific complementation of the fec phenotype of bacteriophage lambda. the cloned gene restored the recombination proficiency and conferred resistance to dna-damaging agents (methyl methanesulfonate and nitrofurantoin) to an escherichia coli reca mutant. the direction of transcription and the localization of the reca gene were determined by mutagenesis with phage mudiipr13 and heterologous hybridization with an e. coli reca probe. an r. ph ... | 1991 | 2022610 |
| heterologous exopolysaccharide production in rhizobium sp. strain ngr234 and consequences for nodule development. | rhizobium sp. strain ngr234 produces large amounts of acidic exopolysaccharide. mutants that fail to synthesize this exopolysaccharide are also unable to nodulate the host plant leucaena leucocephala. a hybrid strain of rhizobium sp. strain ngr234 containing exo genes from rhizobium meliloti was constructed. the background genetics and nod genes of rhizobium sp. strain ngr234 are retained, but the cluster of genes involved in exopolysaccharide biosynthesis was deleted. these exo genes were repla ... | 1991 | 2022612 |
| lpsz, a lipopolysaccharide gene involved in symbiosis of rhizobium meliloti. | lpsz+ is an allele that allows exo (exopolysaccharide-deficient) mutants of rhizobium meliloti to invade nodules by modifying rhizobial lipopolysaccharide. we have cloned and sequenced the lpsz gene. the predicted lpsz protein has a molecular weight of 48,589 and is probably localized in the cytoplasm. a beta-glucuronidase fusion in the lpsz gene indicates that lpsz is not regulated by oxygen or nitrogen. | 1991 | 2022621 |
| stimulation of indole-3-acetic acid production in rhizobium by flavonoids. | flavonoids activate nod gene expression in rhizobium resulting in the synthesis of nod signals which trigger organogenesis in the host plant. this paper shows that nod-inducers also stimulate the production of the phytohormone iaa (indole-3-acetic acid). | 1991 | 2026265 |
| cellulose biosynthesis and function in bacteria. | the current model of cellulose biogenesis in plants, as well as bacteria, holds that the membranous cellulose synthase complex polymerizes glucose moieties from udp-glc into beta-1,4-glucan chains which give rise to rigid crystalline fibrils upon extrusion at the outer surface of the cell. the distinct arrangement and degree of association of the polymerizing enzyme units presumably govern extracellular chain assembly in addition to the pattern and width of cellulose fibril deposition. most evid ... | 1991 | 2030672 |
| impact of heavy metals on an arctic rhizobium. | | 1991 | 2032013 |
| the degree of esterification and points of substitution by o-acetyl and o-(3-hydroxybutanoyl) groups in the acidic extracellular polysaccharides secreted by rhizobium leguminosarum biovars viciae, trifolii, and phaseoli are not related to host range. | rhizobium leguminosarum biovars viciae, trifolii, and phaseoli have been grown in the presence and absence of 4',5,7-trihydroxyflavonone (naringenin) or 4',5,7-trihydroxyflavone (apigenin), which induce the expression of nodulation genes of the bacteria. the acidic polysaccharides secreted by the rhizobium were isolated from the culture media and purified. the polysaccharides were cleaved with a bacteriophage enzyme and the octasaccharide repeating units formed were isolated. the glycosyl sequen ... | 1991 | 2033051 |
| distribution of o-acetyl groups in the exopolysaccharide synthesized by rhizobium leguminosarum strains is not determined by the sym plasmid. | the patterns of o-acetylation of the exopolysaccharide (eps) from the sym plasmid-cured derivatives of rhizobium leguminosarum bv. trifolii strain lpr5, r. leguminosarum bv. trifolii strain anu843 and r. leguminosarum bv. viciae strain 248 were determined by 1h and 13c nmr spectroscopy. beside a site indicative of the chromosomal background, these strains have one site of o-acetylation in common, namely residue b of the repeating unit. the o-acetyl esterification pattern of eps of the sym plasmi ... | 1991 | 2033052 |
| cloning and nucleotide sequence of the hema gene of agrobacterium radiobacter. | the hema gene of agrobacterium radiobacter atcc4718 was identified by hybridization with a hema probe from rhizobium meliloti and cloned by complementation of a hema mutant of escherichia coli k12. e. coli hema transformants carrying the hema gene of agrobacterium showed delta-aminolevulinic acid synthetase (delta-alas) activity in vitro. the hema gene was carried on a 4.4 kb ecori fragment which could be reduced to a 2.6 kb ecori-ssti fragment without affecting its complementing or delta-alas a ... | 1991 | 2034217 |
| effect of the concentration of sodium chloride in the medium on the relative proportions of poly- and oligo-saccharides excreted by rhizobium meliloti strain ye-2sl. | rhizobium meliloti mutant strains have been found which, in the presence of low concentrations of nacl, produce a galactoglucan instead of the usual succinoglycan. when grown in a mannitol-glutamic acid-salts medium, the principal products secreted by r. meliloti ye-2s1 were comparable quantities of succinoglycan repeating-units and galactoglucan. as nacl was added progressively to the culture medium, the repeating units nearly completely disappeared and the galactoglucan was gradually replaced ... | 1991 | 2036651 |
| structural determination of bacterial nodulation factors involved in the rhizobium meliloti-alfalfa symbiosis. | extracellular signals produced by rhizobium meliloti are able to induce root hair deformations and nodule organogenesis on alfalfa. the production of these signals is controlled by bacterial nod genes. to enable their isolation in significant amounts, an overproducting strain was constructed. these nod factors were first extracted by butanol from the culture medium and further purified by reverse-phase high performance liquid chromatography, ion-exchange, and sephadex lh-20 chromatographies. the ... | 1991 | 2040610 |
| catechol degradation by immobilized rhizobium sp. | entrapped cells of rhizobium sp. isolated from lablab purpureus in calcium alginate degraded catechol (1,2-dihydroxybenzene) compared with the free cells. agitation enhanced its rapid degradation. the versatility of rhizobium sp. to degrade phenolic substances can be exploited in biotechnological application. | 1991 | 2042401 |
| genetic analysis of the attenuator of the rhizobium meliloti trpe(g) gene. | it was previously reported that transcription of the rhizobium meliloti trpe(g) gene starts at the adenine residue of the aug codon of the leader peptide coding sequence (trpl), suggesting that translation of the trpl sequence starts without the shine-dalgarno sequence. we constructed mutations replacing the aug codon of the trpl sequence with aag or acg. these mutations reduced the expression of a trpl'-'lacz fusion gene to 0.1 and 0.2% of the wild-type level, respectively, indicating that the ... | 1991 | 2045362 |
| isoflavonoid-inducible resistance to the phytoalexin glyceollin in soybean rhizobia. | the antibacterial effect of the soybean phytoalexin glyceollin was assayed using a liquid microculture technique. log-phase cells of bradyrhizobium japonicum and sinorhizobium fredii were sensitive to glyceollin. as revealed by growth rates and survival tests, these species were able to tolerate glyceollin after adaptation. incubation in low concentrations of the isoflavones genistein and daidzein induced resistance to potentially bactericidal concentrations of glyceollin. this inducible resista ... | 1991 | 2045365 |
| early recognition in the rhizobium meliloti-alfalfa symbiosis: root exudate factor stimulates root adsorption of homologous rhizobia. | adsorption of rhizobium meliloti to alfalfa roots before their infection and nodule formation shows the specificity of the symbiotic association (g. caetano-anollés and g. favelukes, appl. environ. microbiol. 52:377-382, 1986). the time course of specific adsorption of r. meliloti (10(3) to 10(4) cells per ml) to roots shows an initial lag period of 3 h, suggesting that either or both symbionts must become conditioned for the adsorption process. preincubation of r. meliloti l5-30 for 3 h with di ... | 1991 | 2045369 |
| rice tungro bacilliform virus dna independently infects rice after agrobacterium-mediated transfer. | in nature, rice tungro disease is caused by an rna and a dna virus complex, but we have obtained an independently infectious clone of rice tungro bacilliform virus (rtbv) dna. infectivity could be demonstrated only when a more than unit-length copy was cloned in the agrobacterium binary vector bin 19 and agroinoculated into rice plants. rice plants thus agroinfected with cloned rtbv dna showed typical symptoms of tungro disease, presence of viral dna and bacilliform particles, and could be used ... | 1991 | 2045788 |
| involvement of fixlj in the regulation of nitrogen fixation in azorhizobium caulinodans. | a gene bank of azorhizobium caulinodans dna constructed in the bacteriophage lambda gem11 was screened with rhizobium meliloti fixl and fixj genes as probes. one positive recombinant phage, ors lambda l, was isolated. the nucleotide sequence of a 3.7 kb fragment was established. two open reading frames of 1512bp and 613bp were identified as fixl and fixj. kanamycin cartridges were inserted into the cloned fixl and fixj genes and recombined into the host genome. the resulting mutants were nif- fi ... | 1991 | 2046550 |
| the isolated n-terminal dna binding domain of the c repressor of bacteriophage 16-3 is functional in dna binding in vivo and in vitro. | the 197 amino acid c repressor of the temperate rhizobium meliloti phage 16-3 still regulates the or operator of the phage after removal of its carboxyl terminal region. when cloned in the low-copy-number plasmid pga46, a severely truncated variant (r1-77), which retains only the first 77 amino acids of the intact protein, repressed in vivo transcription from the phage promoter pr. when the r1-77 repressor was fused to e. coli beta-galactosidase, the hybrid protein bound or operator dna in vitro ... | 1991 | 2046652 |
| mutations in the two flagellin genes of rhizobium meliloti. | the previously cloned dna fragment which complements the behavioral defects of the che-1 and che-3 mutations of rhizobium meliloti codes for two nearly identical (93%) flagellin genes. a wild-type copy of one of the two genes (flaa) but not the other (flab) can complement the mutations. the behavior and flagellar morphology of newly isolated strains carrying insertion and deletion mutations or various combinations of these mutations demonstrated that either gene product alone can form functional ... | 1991 | 2050631 |
| rhizobium meliloti exog and exoj mutations affect the exox-exoy system for modulation of exopolysaccharide production. | r. meliloti rm1021 normally produces an acidic calcofluor-binding exopolysaccharide, called succinoglycan or eps i, which is required for successful nodulation of alfalfa by this strain. at least 13 loci affecting production of eps i were previously mapped to a cluster on the second of two symbiotic megaplasmids in rm1021, prmesu47b. a putative regulatory region was originally defined by the exog and exoj mutations. exog and exoj mutants produced less exopolysaccharide than wild-type strains and ... | 1991 | 2050634 |
| in vivo analysis of plant pre-mrna splicing using an autonomously replicating vector. | in this paper, we demonstrate that an autonomously replicating plant expression vector can be used for analysis of pre-mrna splicing determinants in intact dicot cells. this vector system relies on the agrobacterium-mediated transfection of leaf discs with the a component of the geminivirus tomato golden mosaic virus (tgmv). insertion of intron sequences between viral promoter and terminator sequences results in the production of high levels of pre-mrna transcripts that are effectively and accur ... | 1991 | 2057358 |
| agrobacterium radiobacter bacteremia in a child with human immunodeficiency virus infection. | | 1991 | 2062633 |
| genetic analysis of functional differences among distinct ferredoxins in rhodobacter capsulatus. | rhodobacter capsulatus has been known to possess two ferredoxins (i and ii) with distinct physicochemical and structural properties: ferredoxin i is a 2[4fe-4s] type and the other is a [3fe-4s] [4fe-4s] type. to analyze their possible functional differences, their genes (fdxn and fdxa) were cloned, sequenced, and subjected to interposon mutagenesis experiments. the former gene was adjacent to a gene encoding a chloroplast-type [2fe-2s] ferredoxin (fdxc). mutants with inactivated fdxn and/or fdxc ... | 1991 | 2071578 |
| density dependent diffusional model of an infective population. | in this work, we present a density-dependent diffusional model which, coupled to three different types of growth, permitted us to study the infective potential of a bacteria species. the results show that those species with strong internal competency have the higher colonizing capacity in terms of invasion speed. here, we also advanced a model for the static spatial inhomogeneous distribution that some species establish after migration. it is proposed that the origin of these patterns is the res ... | 1990 | 2073542 |
| transcriptional analysis of the glnb-glna region of rhizobium leguminosarum biovar viciae. | we report that the glnb and glna genes of rhizobium leguminosarum biovar viciae are preceded by promoters located upstream of each gene. we find the presence of a glnb-glna and a glna mrna whose intracellular concentration changes two- to three-fold when r. leguminosarum is grown on different nitrogen sources. primer extension analysis shows unique transcriptional initiation sites upstream of glnb and glna. the glnb promoter is rpon(ntra)-dependent, while the glna promoter does not contain a typ ... | 1990 | 2077357 |
| genetic analyses of rhizobium meliloti exopolysaccharides. | we have recently obtained strong genetic evidence that the acidic calcofluor-binding exopolysaccharide (eps i) of rhizobium meliloti rm1021 is required for nodule invasion and possibly for later events in nodule development. thirteen loci on the second megaplasmid have been identified that are required for, or affect, the synthesis of eps i. mutations in certain of these loci completely abolish the production of eps i and result in mutants that form empty fix- nodules. exoh mutants fail to succi ... | 1990 | 2078533 |
| identification and cloning of nodulation genes and host specificity determinants of the broad host-range rhizobium leguminosarum biovar phaseoli strain ciat899. | rhizobium leguminosarum biovar phaseoli type ii strain ciat899 nodulates a wide range of hosts: phaseolus vulgaris (beans), leucaena esculenta (leucaena) and macroptilium atropurpureum (siratro). a nodulation region from the symbiotic plasmid has been isolated and characterized. this region, which is contained in the overlapping cosmid clones pcv38 and pcv117, is able to induce nodules in beans, leucaena and siratro roots when introduced in strains cured for the symbiotic plasmid, psym. in addit ... | 1990 | 2082147 |
| nine years after. molecular communication in higher plants, sponsored by the european molecular biology organization, heidelberg, frg, september 18-21, 1989. | | 1990 | 2083248 |
| a permanent endoparasite of man. 1. the silent zoogleal/symplasm/l-form phase. | | 1990 | 2084495 |
| gene transfer methods for plants and cell cultures. | agrobacterium-mediated gene transfer provides a routine and efficient gene transfer system for a variety of plant species. as this biological vector does not, however, function with important plant species, numerous alternative approaches have been studied. of those, direct gene transfer into protoplasts, microinjection and biolistics have been demonstrated to be effective. others, for example, viral vectors, agroinfection, liposome injection and electrophoresis may have special merits, although ... | 1990 | 2086036 |
| specific binding of virg to the vir box requires a c-terminal domain and exhibits a minimum concentration threshold. | the positive regulatory protein virg from the virulence region of the ti plasmid of agrobacterium tumefaciens was first demonstrated to possess dna-binding capabilities using chromatographically purified protein and in vitro assays (powell et al., 1989). this paper is an extension of that research and presents evidence on the in vivo dna-binding properties of virg using a transcription interference assay. virg protein bound specifically to a 'vir box' response element and repressed transcription ... | 1990 | 2089226 |
| expression of a rice glutelin promoter in transgenic tobacco. | a chimeric gene consisting of the 5' flanking sequences of a rice glutelin gene (gt3) linked to the chloramphenicol acetyltransferase (cat) coding segment was introduced into tobacco via agrobacterium tumefaciens-mediated transformation. cat enzyme activity could be detected in extracts from seeds as early as 8 days after flowering and obtained a maximum level at 16 days after flowering, the onset of overall protein accumulation. significant expression of cat activity in non-seed tissues occurre ... | 1990 | 2101310 |
| localized transient expression of gus in leaf discs following cocultivation with agrobacterium. | a chimaeric gene has been constructed that expresses beta-d-glucuronidase (gus) in transformed plant tissues, but not in bacterial cells. this gene has proved extremely useful for monitoring transformation during the period immediately following gene transfer from agrobacterium tumefaciens. gus expression was detectable 2 days after inoculation, peaked at 3-4 days and then declined; if selection was imposed expression increased again after 10-14 days. the extent of transient expression after 4 d ... | 1990 | 2101312 |
| t-dna presence and opine production in tumors of picea abies (l.) karst induced by agrobacterium tumefaciens a281. | the hypervirulent agrobacterium tumefaciens strain a281 formed frequent tumors (31%) on picea abies (norway spruce), an economically important tree species in swedish forests. three-month-old seedlings were inoculated and tumors were established that grew hormone-independently in culture. tumors contained agropine and mannopine/mannopinic acid as determined by acid ph paper electrophoresis. in addition, dna hybridization studies showed that the dna from these tumor lines contained sequences homo ... | 1990 | 2101685 |
| functional analysis of a complex oncogene arrangement in biotype iii agrobacterium tumefaciens strains. | the ubiquitous grapevine-associated octopine/cucumopine ti plasmids of biotype iii agrobacterium tumefaciens strains carry two t regions, ta and tb, with a complex oncogene arrangement. within the octopine/cucumopine group, two main strain types were identified: 'large ta' strains with a ta region resembling the tl region of the biotype i octopine strain ach5 and 'small ta' strains with a similar t region organization as the 'large ta' strains but with a large internal ta deletion. structural an ... | 1990 | 2101690 |
| synthesis and accumulation of pea plastocyanin in transgenic tobacco plants. | the pea plastocyanin gene in a 3.5 kbp eco ri fragment of pea nuclear dna was introduced into tobacco by agrobacterium-mediated transformation. regenerated plants contained pea plastocyanin located within the chloroplast thylakoid membrane system. analysis of seedlings from a self-pollinated transgenic plant containing a single copy of the pea plastocyanin gene indicated that seedlings homozygous for the pea gene contained almost twice as much pea plastocyanin as seedlings hemizygous for the pea ... | 1990 | 2101692 |
| octopine and nopaline strains of agrobacterium tumefaciens differ in virulence; molecular characterization of the virf locus. | octopine and nopaline strains of agrobacterium tumefaciens were found to differ in virulence on nicotiana glauca. this difference is due to the absence of a functional virf locus, which is necessary for efficient tumorigenesis on n. glauca, from the nopaline ti plasmids. genetic studies and dna sequence analysis of the virf locus revealed that virf embraces one open reading frame coding for a hydrophilic protein with a molecular mass of 22,437 da. transcription of virf is directed from left to r ... | 1990 | 2101693 |
| regulation of expression of a wound-inducible tomato inhibitor i gene in transgenic nightshade plants. | a wound-inducible proteinase inhibitor i gene from tomato containing 725 bp of the 5' region and 2.5 kbp of the 3' region was stably incorporated into the genome of black nightshade plants (solanum nigrum) using an agrobacterium ti plasmid-derived vector. transgenic nightshade plants were selected that expressed the tomato inhibitor i protein in leaf tissue. the leaves of the plants contained constitutive levels of the inhibitor protein of up to 60 micrograms/g tissue. these levels increased by ... | 1990 | 2102819 |
| characteristics of a strong promoter from figwort mosaic virus: comparison with the analogous 35s promoter from cauliflower mosaic virus and the regulated mannopine synthase promoter. | a segment of dna from the genome of figwort mosaic virus (fmv) strain m3 possesses promoter activity when tested in electroporated protoplasts from, and transgenic plants of, nicotiana tabacum cv. xanthi nc. the 1.1 kb dna segment, designated the '34s' promoter, is derived from a position on the fmv genome comparable to the position on the cauliflower mosaic virus (camv) genome containing the 35s promoter. the 34s and 35s promoters show approximately 63% nucleotide homology in the tata, ccact, a ... | 1990 | 2102823 |
| identification and cdna cloning of a new nodule-specific gene, nms-25 (nodulin-25) of medicago sativa. | a new nodule-specific gene, nms-25 (nodulin-25), was identified in cdna clones isolated from a nodule-specific cdna library of medicago sativa. the first transcript of this gene appeared 9 days after inoculation of the roots with rhizobium meliloti. the time of expression and the quantity of the transcripts of the nms-25 gene was similar to that of leghemoglobin genes suggesting a similar regulation. a protein of 246 amino acids could be deduced from a full-length cdna clone. the first 24 amino ... | 1990 | 2102828 |
| identification of a putative rol b gene on the tr-dna of the agrobacterium rhizogenes a4 ri plasmid. | | 1990 | 2102840 |
| the ptic58 tzs gene promotes high-efficiency root induction by agropine strain 1855 of agrobacterium rhizogenes. | root induction on flax (linum usitatissimum l.) cotyledon explants by agrobacterium rhizogenes strain 1855 is markedly increased by co-inoculation with disarmed a. tumefaciens strain lba 4404 containing a plasmid carrying the tzs gene of ptic58. most of the roots (estimated to be more than 90%) were transformed. this effect is most likely due to the secretion of trans-zeatin by a. tumefaciens stimulating the division of plant cells making them more receptive to transformation by a. rhizogenes, a ... | 1990 | 2102856 |
| transformation and regeneration of the self-incompatible species nicotiana alata link & otto. | a transformation and regeneration system has been developed for nicotiana alata, a plant which is being intensively studied as a model of gametophytic self-incompatibility. plantlets can be regenerated efficiently from seedling hypocotyls. kanamycin-resistant, transformed plants have been obtained by cocultivation of regenerating hypocotyls with agrobacterium tumefaciens strain lba4404 containing a binary vector. the transformation frequency was low with less than 1% of tissue explants regenerat ... | 1990 | 2102859 |
| the non-conserved region of cucumopine-type agrobacterium rhizogenes t-dna is responsible for hairy root induction. | the t-dna regions of three strains of ri plasmids 1855, 8196, 2659 (agropine, mannopine and cucumopine type respectively) share two highly conserved regions flanking a non-homologous central part. we have cloned segments of the cucumopine ri plasmid 2659 t-dna in the binary vector system bin 19 and infected carrot discs with recombinant agrobacterium strains. we show here that the central non-conserved region is crucial in hairy root induction as it is sufficient to induce rooting on the apical ... | 1990 | 2102883 |
| agrobacterium-mediated plant transformation by novel mini-t vectors in conjunction with a high-copy vir region helper plasmid. | a new binary vector system for agrobacterium-mediated plant transformation was developed. a set of four mini-t vectors comprised of t-dna border sequences from nopaline-type ti-plasmid ptic58 flanking a chimaeric hygromycin-resistance gene for selection of transformants and up to eight unique restriction sites for cloning foreign dna was constructed on a broad-host replicon containing the oriv of plasmid psa. in two of the constructs these multiple cloning sites are flanked by a strong promoter ... | 1990 | 2103448 |
| nucleotide sequence of the hydrogenase structural genes from rhizobium leguminosarum. | | 1990 | 2103457 |
| novel and useful properties of a chimeric plant promoter combining camv 35s and mas elements. | the camv 35s and ti plasmid mannopine synthetase (mas) promoters are commonly used by plant genetic engineers. to combine their useful properties, we constructed hybrid promoters incorporating elements from both. these promoters were spliced to the beta-glucuronidase reporter gene and introduced into tobacco and tomato plants by agrobacterium cocultivation. t1 and t2 transgenic plant populations transformed with different constructs were assayed for the marker enzyme. comparisons were made based ... | 1990 | 2103458 |
| restoration of shooty morphology of a nontumorous mutant of nicotiana glauca x n. langsdorffii by cytokinin and the isopentenyltransferase gene. | the shooty morphology of a nontumorous amphidiploid mutant of nicotiana glauca grah. x n. langsdorffii weinm. was restored by cytokinins, whether exogenously applied or endogenously produced by transformation of the mutant with a transfer dna (t-dna) cytokinin-biosynthesis gene (isopentenyltransferase; ipt). auxins alone did not confer this effect. similar transformation was not achieved for the parental species. in the case of transformation with the ipt gene, selection of the transformed tissu ... | 1990 | 2103461 |
| manipulation of beta-glucuronidase for use as a reporter in vacuolar targeting studies. | it has been documented that when furnished with an endomembrane signal sequence for the endoplasmic reticulum, beta-glucuronidase (gus) is n-glycosylated, resulting in the nearly complete loss of enzymatic activity. to enable use of beta-glucuronidase as a reporter protein in secretory and vacuolar targeting studies, one of the two putative n-linked glycosylation sites within the gus gene was altered by site-directed mutagenesis. the second n-linked glycosylation site was not altered because seq ... | 1990 | 2103475 |
| the effect of t-dna copy number, position and methylation on reporter gene expression in tobacco transformants. | inter-transformant variability in the expression of introduced genes was studied in the r1 and r2 generations of 10 tobacco transformants, produced by agrobacterium-mediated transformation. in replicated and physiologically equivalent material, tranformants showed considerable variability in the expression of the reporter gene uida as shown by transcript levels and beta-glucuronidase (gus) activity. however, homozygous r2 material could be investigated for seven of the transformants and among th ... | 1990 | 2103477 |
| a 268 bp upstream sequence mediates the circadian clock-regulated transcription of the wheat cab-1 gene in transgenic plants. | we previously reported that the expression of the wheat cab-1 gene is regulated by an endogenous circadian rhythm and by the photoreceptor phytochrome both in wheat and in transgenic tobacco plants. to define regulatory elements necessary for the circadian rhythm-regulated cab-1 gene expression, we now analysed the fluctuation of steady-state mrna levels in a series of 5' deletion mutants in transgenic tobacco plants. we found that the expression of a deletion mutant containing 211 bp upstream s ... | 1990 | 2103481 |
| plant regeneration from ri t-dna transformed roots of cabbage. | ri t-dna transformed roots were induced out on hypocotyl segments of cabbage infected with agrobacterium rhizogenes. after cultured for four months on solid ms medium without hormones, some parts of a few of transformed roots were dedifferentiated into callus clumps, and then redifferentiated into shoot buds. on solid ms medium supplemented with kinetin, shoot buds were differentiated directly from transformed roots without callus formation. among several concentrations of kinetin, 14 microm gav ... | 1990 | 2104201 |
| [demonstration of 3 functional domains responsible for a kinase activity in vira, a transmembrane sensory protein encoded by the ti plasmid of agrobacterium tumefaciens]. | high-level expression of chimeric vira genes were obtained by replacing the first codons of vira with the first codons of trpe. the fusion proteins encoded by these constructs were partially purified and one of them exhibited autokinase activity. therefore, protein phosphorylation may be an important feature of vira function. this allowed us to define the existence of three functional domains inside vira. | 1990 | 2105145 |
| effectiveness of pseudomonas aeruginosa for detoxification of tetramethylthiuram disulfide (tmtd) from contaminated soil. | | 1990 | 2108742 |
| stereospecific abstraction of epsilon-pro-r-hydrogen of l-lysine by l-lysine epsilon-dehydrogenase from agrobacterium tumefaciens. | the stereochemical aspects of the l-lysine epsilon-dehydrogenase reaction were examined with (6r)-l-[6-3h]lysine and (6s)-dl-[6-3h]lysine. when (6s)-dl-[6-3h]lysine was used as a substrate, the tritium was found in the product, delta 1-piperideine-6-carboxylate. in contrast, the radioactivity from (6r)-l-[6-3h]lysine was not retained in the product. thus, the pro-r hydrogen at the prochiral c-6 carbon of l-lysine is specifically abstracted by the enzyme: the enzyme behaves stereochemically as an ... | 1990 | 2110154 |
| identification of an agrobacterium tumefaciens virulence gene inducer from the pinaceous gymnosperm pseudotsuga menziesii. | inducible t-strand mobilization from the ti plasmid of agrobacterium tumefaciens to the genome of a plant host is mediated by the activation of a cascade of bacterial virulence genes. it is initiated when the bacterium senses the presence of a low molecular weight inducer secreted by the plant. although many hydroxyphenylpropanoid and phenolic compounds can activate the virulence cascade, the only native inducers that have been identified to date are acetosyringone and hydroxyacetosyringone. a n ... | 1990 | 2110367 |
| the rhizobium meliloti trpe(g) gene is regulated by attenuation, and its product, anthranilate synthase, is regulated by feedback inhibition. | in rhizobium meliloti, the genes involved in biosynthesis of the amino acid tryptophan are found at three separate chromosomal locations. of the three gene clusters, trpe(g), trpdc, and trpfba, only the trpe(g) gene is regulated by the end product of the pathway, tryptophan. we found that trpe(g) mrna contains a leader transcript that terminates at a stem-loop structure in a putative transcription attenuator. the level of this leader transcript was constant regardless of the amount of tryptophan ... | 1990 | 2111807 |
| rhizobium meliloti suhr suppresses the phenotype of an escherichia coli rna polymerase sigma 32 mutant. | sigma 32, the product of the escherichia coli rpoh locus, is an alternative rna polymerase sigma factor utilized to express heat shock genes upon a sudden rise in temperature. e. coli k165 [rpoh165(am) supc(ts)] is temperature sensitive for growth and does not induce heat shock protein synthesis. we have isolated a locus from rhizobium meliloti called suhr that allows e. coli k165 to grow at high temperature and induce heat shock protein synthesis. r. meliloti suhr mutants were viable and symbio ... | 1990 | 2113906 |
| a new family of rsf1010-derived expression and lac-fusion broad-host-range vectors for gram-negative bacteria. | a series of broad-host-range expression and lac fusion vectors, based on rsf1010 derivatives, was constructed. the expression vectors contain various promoters (pnm, plac, ptac and ps1) for expression of foreign genes. the efficiency of the promoters was determined in escherichia coli, rhizobium meliloti, rhizobium leguminosarum and pseudomonas putida by beta-galactosidase activity measurements. of the promoters assayed in e. coli, the most effective is the tac promoter, whereas in soil bacteria ... | 1990 | 2115488 |
| rhizobium meliloti fix l is an oxygen sensor and regulates r. meliloti nifa and fixk genes differently in escherichia coli. | in rhizobium meliloti, nif and fix genes, involved in nitrogen fixation during symbiosis with alfalfa, are under the control of two transcriptional regulators encoded by nifa and fixk. expression of nifa and fixk is under the control of fixl/j, a two-component regulatory system. we showed, using escherichia coli as a heterologous host, that fixl/j controls nifa and fixk expression in response to microaerobiosis. furthermore, expression of the sensor gene fixl and of the activator gene fixj under ... | 1990 | 2115865 |
| excessive excretion of cyclic beta-(1,2)-glucan by rhizobium trifolii ta-1. | at 25 degrees c, the optimal temperature for growth of rhizobium trifolii ta-1, extracellular and capsular polysaccharide (eps and cps) were the main carbohydrate products synthesized in mannitol-rich medium (10 g of mannitol and 1 g of glutamic acid per liter). in the same medium at 33 degrees c, eps and cps production was inhibited, and up to 3.9 g of cyclic beta-(1,2)-glucan was produced during an incubation period of 20 days with a total biomass of 0.55 g of protein. in a medium containing 5 ... | 1990 | 2117876 |
| thymidylate synthase gene from lactococcus lactis as a genetic marker: an alternative to antibiotic resistance genes. | the potential of the thymidylate synthase thya gene cloned from lactococcus lactis subsp. lactis as a possible alternative selectable marker gene to antibiotic resistance markers has been examined. the thya mutation is a recessive lethal one; thya mutants cannot survive in environments containing low amounts of thymidine or thymine (such as luria-bertani medium) unless complemented by the thya gene. the cloned thya gene was strongly expressed in l. lactis subsp. lactis, escherichia coli, rhizobi ... | 1990 | 2117883 |
| two genes that regulate exopolysaccharide production in rhizobium meliloti. | we describe a new rhizobium meliloti gene, exox, that regulates the synthesis of the exopolysaccharide, succinoglycan, exox resembled the psi gene of r. leguminosarum bv. phaseoli and the exox gene of rhizobium sp. strain ngr234 in its ability to inhibit exopolysaccharide synthesis when present in multiple copies, exox did not appear to regulate the expression of exop. the effect of exox was counterbalanced by another r. meliloti gene, exof. exof is equivalent to rhizobium sp. strain ngr234 exoy ... | 1990 | 2118508 |
| sugars induce the agrobacterium virulence genes through a periplasmic binding protein and a transmembrane signal protein. | phenolic plant metabolites such as acetosyringone induce transcription of the virulence (vir) genes of agrobacterium tumefaciens through the transmembrane vira protein. we report here that certain sugars induce the vir genes synergistically with phenolic inducers by way of a distinct regulatory pathway that includes vira and a chromosomally encoded virulence protein, chve. sequence comparison showed that chve is a periplasmic galactose-binding protein corresponding to the gbp1 protein isolated f ... | 1990 | 2118656 |
| glutamyl-trna synthetases of bacillus subtilis 168t and of bacillus stearothermophilus. cloning and sequencing of the gltx genes and comparison with other aminoacyl-trna synthetases. | the glutamyl-trna synthetase (glurs) of bacillus subtilis 168t aminoacylates with glutamate its homologous trna(glu) and trna(gln) in vivo and escherichia coli trna(1gln) in vitro (lapointe, j., duplain, l., and proulx, m. (1986) j. bacteriol. 165, 88-93). the gltx gene encoding this enzyme was cloned and sequenced. it encodes a protein of 483 amino acids with a mr of 55,671. alignment of the amino acid sequences of four bacterial glurss (from b. subtilis, bacillus stearothermophilus, e. coli, a ... | 1990 | 2120226 |
| regulatory functions of the three nodd genes of rhizobium leguminosarum biovar phaseoli. | the three nodd genes of a strain of rhizobium leguminosarum biovar phaseoli were cloned to study their effects on transcription of themselves and of the nodc genes of biovars phaseoli and viciae. efficient transcription of nodd1 required nodd1 and was enhanced by exposure of the cells to bean exudate consistent with the presence of a nod-box preceding the noie-nodd1 operon. transcription of nodd2 and nodd3 was constitutive. nodc of r. leguminosarum biovar phaseoli was activated by each of the no ... | 1990 | 2120543 |
| [structural-functional organization of the incompatibility group p plasmid pbs221]. | plasmid pbs221 was physically mapped for restriction endonucleases ecori, bamhi, bglii, hindiii. the regions essential for the plasmid existence and participating in replication (oriv trfa*) and mobilization (mob) were cloned. the tet determinant and oriv trfa* regions were localized on the physical map of the plasmid. a dna sequence homologous to genes of tn501 mer operon was detected in this plasmid. the studies on homology of plasmids rp4 (incp alpha), r751 (incp beta) and pbs221 plasmid sugg ... | 1990 | 2121599 |
| genetic characterization of the stabilizing functions of a region of broad-host-range plasmid rk2. | one of the regions responsible for the stable inheritance of the broad-host-range plasmid rk2 is contained within the psti c fragment, located from coordinates 30.8 to 37.0 kb (p.n. saurugger, o. hrabak, h. schwab, and r.m. lafferty, j. biotechnol. 4:333-343, 1986). genetic analysis of this 6.2-kb region demonstrated that no function was present that stabilized by selectively killing plasmid-free segregants. the sequence from 36.0 to 37.0 kb mediated a twofold increase in plasmid copy number, bu ... | 1990 | 2121707 |
| sugar-mediated induction of agrobacterium tumefaciens virulence genes: structural specificity and activities of monosaccharides. | the virulence genes of agrobacterium tumefaciens are induced by specific plant phenolic metabolites and sugars (g. a. cangelosi, r. g. ankenbauer, and e. w. nester, proc. natl. acad. sci. usa, in press). in this report, monosaccharides, derivatives, and analogs which induce the vir regulon have been identified and the structural requirements for monosaccharide-mediated induction have been determined. pyranose sugars with equatorial hydroxyls at c-1, c-2, and c-3 displayed strong vir gene-inducin ... | 1990 | 2121715 |