| infection of soybean and pea nodules by rhizobium spp. purine auxotrophs in the presence of 5-aminoimidazole-4-carboxamide riboside. | purine auxotrophs of various rhizobium species are symbiotically defective, usually unable to initiate or complete the infection process. earlier studies demonstrated that, in the rhizobium etli-bean symbiosis, infection by purine auxotrophs is partially restored by supplementation of the plant medium with 5-amino-imidazole-4-carboxamide (aica) riboside, the unphosphorylated form of the purine biosynthetic intermediate aicar. the addition of purine to the root environment does not have this effe ... | 1994 | 8195084 |
| nodulation protein nodl of rhizobium leguminosarum o-acetylates lipo-oligosaccharides, chitin fragments and n-acetylglucosamine in vitro. | upon induction of their nodulation genes, the root nodule-inducing rhizobium bacteria produce lipo-oligosaccharide signal molecules. all lipo-oligosaccharides identified from rhizobium leguminosarum bv. viciae carry an o-acetyl group at the c-6 position of the non-reducing terminal sugar, the presence of which is important for biological activity and host specificity. previously we showed that a functional nodl gene product is required for the presence of this o-acetyl moiety. the production of ... | 1994 | 8196551 |
| trai, a luxi homologue, is responsible for production of conjugation factor, the ti plasmid n-acylhomoserine lactone autoinducer. | conjugal transfer of the nopaline-type agrobacterium ti plasmid ptic58 is regulated by a transcriptional activator, trar, and a diffusible signal molecule, conjugation factor (cf). cf is a member of a family of substituted homoserine lactones (hsls) that act as coinducers for regulating gene expression in diverse gram-negative bacteria by a mechanism called autoinduction. in vibrio fischeri hsl production is conferred by the luxi gene. homologues of this gene are responsible for hsl production b ... | 1994 | 8197112 |
| molecular cloning and sequence analysis of an azospirillum brasilense indole-3-pyruvate decarboxylase gene. | azospirillum brasilense isolated from the rhizosphere of different plants has the ability to excrete indole-3-acetic acid (iaa) into the culture media. cosmid p0.2, isolated from an a. brasilense sp245 genome library in plafr1, complements the tn5-induced mutant spm7918 of a. brasilense sp6 which excretes reduced amounts of iaa. restriction mapping and gene expression studies identified a bglii-ecori 4.3 kb fragment of p0.2 sufficient for the restoration of high levels of iaa production in mutan ... | 1994 | 8202090 |
| intramolecular signal transduction within the fixj transcriptional activator: in vitro evidence for the inhibitory effect of the phosphorylatable regulatory domain. | fixj is a phosphorylatable 'response regulator' controlling the transcription of the key nitrogen fixation genes nifa and fixk in rhizobium meliloti. sequence and genetic analyses indicated that fixj comprises an n-terminal phosphorylatable regulatory domain, fixjn, and a c-terminal transcriptional activator domain, fixjc. we have now overexpressed and purified the fixjc protein and show that it is fully active in an in vitro transcription system with purified rna polymerase. fixjc appeared to a ... | 1994 | 8202354 |
| identification of plant genetic loci involved in a posttranscriptional mechanism for meiotically reversible transgene silencing. | numerous reports describe phenomena of transgene silencing in plants, yet the underlying genetic and molecular mechanisms are poorly understood. we observed that regeneration of arabidopsis thaliana plants transgenic for the rolb gene of agrobacterium rhizogenes results in a selection for transgene silencing. transgene silencing could be monitored in this system by reversion of the visible rolb phenotype. we report a phenotypic, molecular, and genetic characterization of a meiotically reversible ... | 1994 | 8202523 |
| the cobt gene of salmonella typhimurium encodes the namn: 5,6-dimethylbenzimidazole phosphoribosyltransferase responsible for the synthesis of n1-(5-phospho-alpha-d-ribosyl)-5,6-dimethylbenzimidazole, an intermediate in the synthesis of the nucleotide loop of cobalamin. | we present in vitro evidence which demonstrates that cobt is the nicotinate nucleotide:5,6-dimethylbenzimidazole (dmb) phosphoribosyltransferase (ec 2.4.2.21) that catalyzes the synthesis of n1-(5-phospho-alpha-d-ribosyl)-5,6-dimethylbenzimidazole, a biosynthetic intermediate of the pathway that assembles the nucleotide loop of cobalamin in salmonella typhimurium. mutants previously isolated as dmb auxotrophs are shown by physical and genetic mapping studies and complementation studies to carry ... | 1994 | 8206834 |
| functional role of the ti plasmid-encoded catabolic mannopine cyclase in mannityl opine catabolism by agrobacterium spp. | catabolic mannopine (mop) cyclase encoded by ti or ri plasmids lactonizes mop to agropine (agr). the gene of the octopine-type ti plasmid pti15955 encoding the catabolic mop cyclase enzyme previously was localized to a 1.6-kb segment within a cosmid clone, pydh208. a subclone containing only this region complemented the agr catabolism-negative phenotype conferred by a derivative of the octopine-type plasmid ptib6s3 containing a tn7 insertion in the region encoding the mop cyclase enzyme. uptake ... | 1994 | 8206835 |
| genetic complementation analysis of the agrobacterium tumefaciens virb operon: virb2 through virb11 are essential virulence genes. | the agrobacterium tumefaciens virb gene products are proposed to assemble into a transport system capable of exporting complexes of dna and protein across the bacterial envelope en route to plant cells. nonpolar null mutations were constructed in each of the 11 virb genes of the a. tumefaciens ptia6nc plasmid. in tumorigenicity assays, delta virb1 mutants exhibited severely attenuated virulence and delta virb2 through delta virb11 mutants exhibited avirulence. ndei restriction sites introduced a ... | 1994 | 8206843 |
| characterization of the gene encoding the autotrophic atp sulfurylase from the bacterial endosymbiont of the hydrothermal vent tubeworm riftia pachyptila. | atp sulfurylase is a key enzyme in the energy-generating sulfur oxidation pathways of many chemoautotrophic bacteria. the utilization of reduced sulfur compounds to fuel co2 fixation by the still-uncultured bacterial endosymbionts provides the basis of nutrition in invertebrates, such as the tubeworm riftia pachyptila, found at deep-sea hydrothermal vents. the symbiont-containing trophosome tissue contains high levels of atp sulfurylase activity, facilitating the recent purification of the enzym ... | 1994 | 8206850 |
| cloning and analysis of a gene cluster from streptomyces coelicolor that causes accelerated aerial mycelium formation in streptomyces lividans. | we describe the cloning and analysis of two overlapping dna fragments from streptomyces coelicolor that cause aerial mycelium to appear more rapidly than usual when introduced into streptomyces lividans on a low-copy-number plasmid vector. colonies of s. lividans tk64 harboring either clone produce visible aerial mycelia after only 48 h of growth, rather than the usual 72 to 96 h. from deletion and sequence analysis, this rapid aerial mycelium (ram) phenotype appears to be due to a cluster of th ... | 1994 | 8206859 |
| rhicadhesin-mediated attachment and virulence of an agrobacterium tumefaciens chvb mutant can be restored by growth in a highly osmotic medium. | cyclic beta-1,2-glucan is considered to play a role in osmoadaptation of members of the family rhizobiaceae in hypotonic media. agrobacterium tumefaciens chvb mutants, lacking beta-1,2-glucan, exhibit a pleiotropic phenotype, including nonmotility, attachment deficiency, and avirulence. here we report that by growth of chvb mutant cells in tryptone-yeast extract medium supplemented with 7 mm cacl2 and 100 mm nacl, the mutant cells become motile, attach to pea root hair tips, and are virulent on ... | 1994 | 8206861 |
| a gene that encodes a proline-rich nodulin with limited homology to psenod12 is expressed in the invasion zone of rhizobium meliloti-induced alfalfa root nodules. | to define the early stages of the interaction between rhizobium and host legumes, we have cloned and characterized three early nodulin-encoding sequences from an alfalfa (medicago sativa l.) cdna library by probing with a fragment of a cdna clone for psenod12, an infection-related nodulin from pea (pisum sativum l.). although the coding regions of the three clones are 95 to 98% homologous to each other, they are only 43% homologous to the pea clone. however, the putative signal peptide encoded b ... | 1993 | 8208847 |
| identification of methyl jasmonate and salicylic acid response elements from the nopaline synthase (nos) promoter. | transgenic tobacco plants carrying a fusion between the nopaline synthase (nos) promoter and chloramphenicol acetyltransferase (cat) reporter gene (cat) were studied for their inducibility by salicylic acid (sa) or methyl jasmonate (mj) treatments. either chemical significantly increased cat activity to a level much higher than that achieved by wounding. northern blot analysis showed a corresponding increase in mrna levels. after 20 h of induction of flowering plants, the response to mj treatmen ... | 1993 | 8208860 |
| increased production of cadaverine and anabasine in hairy root cultures of nicotiana tabacum expressing a bacterial lysine decarboxylase gene. | several hairy root cultures of nicotiana tabacum varieties, carrying two direct repeats of a bacterial lysine decarboxylase (ldc) gene controlled by the cauliflower mosaic virus (camv) 35s promoter expressed ldc activity up to 1 pkat/mg protein. such activity was, for example, sufficient to increase cadaverine levels of the best line sr3/1-k1,2 from ca. 50 micrograms (control cultures) to about 700 micrograms/g dry mass. some of the overproduced cadaverine of this line was used for the formation ... | 1993 | 8219043 |
| does the ocs-element occur as a functional component of the promoters of plant genes? | the structural requirements of the ocs-element, a promoter element in several genes transferred to the host plant nucleus by agrobacterium tumefaciens and certain dna viruses, have been further characterized both in vitro and in vivo. two adjacent and functionally identical protein-binding sites separated by an exact number of nucleotides are required for in vivo activity of the ocs-element. plant pathogens have presumably recruited cellular transcription factors that interact with these binding ... | 1993 | 8220489 |
| tissue-specific and wound-inducible pattern of expression of the mannopine synthase promoter is determined by the interaction between positive and negative cis-regulatory elements. | in transgenic tobacco plants the regulatory region of the agrobacterium genes involved in mannopine synthesis (pmas) directs expression in vascular tissues and is induced upon wounding. to identify cis-acting sequences required for the cell-type-specific and wound-inducible expression of this regulatory region, the expression pattern of chimeric genes in which 5' upstream deletions of the pmas 1' promoter direct the expression of the beta-glucuronidase coding sequence, was analyzed in transgenic ... | 1993 | 8220492 |
| interaction between the tobacco dna-binding activity cbf and the cyt-1 promoter element of the agrobacterium tumefaciens t-dna gene t-cyt correlates with cyt-1 directed gene expression in multiple tobacco tissue types. | a novel dna-binding activity, designated cbf, has been identified in nuclear extracts from tobacco leaf, stem and root tissue. cbf interacts specifically with a 30 bp promoter fragment, referred to as cyt-1, of the agrobacterium tumefaciens t-dna cytokinin (t-cyt) gene. the t-cyt promoter, although of bacterial origin is active in planta and the 30 bp cyt-1 element is located within a region that is essential for t-cyt promotor activity in leaf, stem and root cells of tobacco plants. gel retarda ... | 1993 | 8220494 |
| roles of plant homologs of rab1p and rab7p in the biogenesis of the peribacteroid membrane, a subcellular compartment formed de novo during root nodule symbiosis. | the peribacteroid membrane (pbm) in legume root nodules is derived from plasma membrane following endocytosis of rhizobium by fusion of newly synthesized vesicles. we studied the roles of plant rab1p and rab7p homologs, the small gtp-binding proteins involved in vesicular transport, in the biogenesis of the pbm. three cdnas encoding legume homologs of mammalian rab1p and rab7p were isolated from soybean (srab1p, srab7p) and vigna aconitifolia (vrab7p). srab1p was confirmed to be a functional cou ... | 1993 | 8223429 |
| the regulatory vira protein of agrobacterium tumefaciens does not function at elevated temperatures. | previous studies have shown that agrobacterium tumefaciens causes tumors on plants only at temperatures below 32 degrees c, and virulence gene expression is specifically inhibited at temperatures above 32 degrees c. we show here that this effect persists even when the vira and virg loci are expressed under the control of a lac promoter whose activity is temperature independent. this finding suggests that one or more steps in the signal transduction process mediated by the vira and virg proteins ... | 1993 | 8226624 |
| oxygen-regulated in vitro transcription of rhizobium meliloti nifa and fixk genes. | oxygen concentration regulates the expression of nitrogen fixation genes in the symbiotic bacterium rhizobium meliloti. we demonstrate that two proteins, fixl and fixj, that belong to the two-component family of regulatory proteins are necessary and sufficient for oxygen-regulated in vitro transcription of the two key regulatory genes, nifa and fixk. we show directly that fixj is a transcriptional activator, working in conjunction with the rna polymerase sigma 70 holoenzyme. addition of fixl122, ... | 1993 | 8226629 |
| physical map of the genome of rhizobium meliloti 1021. | a physical map of the genome of rhizobium meliloti 1021 is presented. the physical sizes of the three replicons in this genome had previously been determined and are as follows: the chromosome, 3.4 mb; psym-b, 1.7 mb; and psym-a, 1.4 mb. the physical maps for this gc-rich genome contain at-rich restriction sites for swai (5'-taaattta-3'), paci (5'-ttaattaa-3'), pmei (5'-gtttaaac-3'), and, for psym-b, spei (5'-actagt-3'). in addition, the endonuclease i-ceui cleaved the 23s rrna genes in this gen ... | 1993 | 8226638 |
| family of glycosyl transferases needed for the synthesis of succinoglycan by rhizobium meliloti. | rhizobium meliloti produces an acidic exopolysaccharide, termed succinoglycan or eps i, that is important for invasion of the nodules that it elicits on its host, medicago sativa. succinoglycan is a high-molecular-weight polymer composed of repeating octasaccharide subunits. these subunits are synthesized on membrane-bound isoprenoid lipid carriers, beginning with a galactose residue followed by seven glucose residues, and modified by the addition of acetate, succinate, and pyruvate. biochemical ... | 1993 | 8226645 |
| genes needed for the modification, polymerization, export, and processing of succinoglycan by rhizobium meliloti: a model for succinoglycan biosynthesis. | the major acidic exopolysaccharide of rhizobium meliloti, termed succinoglycan, is required for nodule invasion and possibly nodule development. succinoglycan is a polymer of octasaccharide subunits composed of one galactose residue, seven glucose residues, and acetyl, succinyl, and pyruvyl modifications, which is synthesized on an isoprenoid lipid carrier. a cluster of exo genes in r. meliloti are required for succinoglycan production, and the biosynthetic roles of their gene products have rece ... | 1993 | 8226646 |
| polarized cells, polar actions. | the recognition of polar bacterial organization is just emerging. the examples of polar localization given here are from a variety of bacterial species and concern a disparate array of cellular functions. a number of well-characterized instances of polar localization of bacterial proteins, including the chemoreceptor complex in both c. crescentus and e. coli, the maltose-binding protein in e. coli, the b. japonicum surface attachment proteins, and the actin tail of l. monocytogenes within a mamm ... | 1993 | 8226658 |
| nucleotide sequence analysis of four genes, hupc, hupd, hupf and hupg, downstream of the hydrogenase structural genes in bradyrhizobium japonicum. | the nucleotide sequence of a 2.2 kb region downstream of the hydrogenase structural genes in bradyrhizobium japonicum was determined. four genes encoding predicted polypeptides of 27.8 (hupc), 21.4 (hupd), 10.6 (hupf) and 15.8 (hupg) kda were identified, of which the first three probably belong to the same operon as the hup structural genes, hups and hupl. hupc is homologous to the hydrophobic polypeptides with four potential transmembrane regions that are encoded by open reading frames followin ... | 1993 | 8230232 |
| the transcriptional activator hlyu of vibrio cholerae: nucleotide sequence and role in virulence gene expression. | hlyu upregulates expression of the haemolysin, hlya, of vibrio cholerae. dna sequence analysis indicates that hlyu is an 11.9 kda protein containing a putative helix-turn-helix motif and belonging to a family of small regulatory proteins, including noir (rhizobium meliloti), smtb (synechococcus pcc 7942) and arsr (plasmids r773, escherichia coli; pi258, staphylococcus aureus; and psx267, staphylococcus xylosus). an hlyu mutant was constructed by insertional inactivation, and found to be deficien ... | 1993 | 8231807 |
| the vird4 gene is required for virulence while vird3 and orf5 are not required for virulence of agrobacterium tumefaciens. | the vird operon of the resident ti plasmid of agrobacterium tumefaciens contains loci involved in t-dna processing and undefined virulence functions. nucleotide sequence of the entire vird operon of ptic58 revealed similarities to the vird operon of the root-inducing plasmid pria4b and to that of the octopine-type plasmid ptia6nc. however, comparative sequence data show that vird of ptic58 is more akin to that of the pria4b than to that of the ptia6nc. t7f10::vird gene fusions were used to gener ... | 1993 | 8231811 |
| sequence and molecular analysis of the nifl gene of azotobacter vinelandii. | in both klebsiella pneumoniae and azotobacter vinelandii the nifl gene, which encodes a negative regulator of nitrogen fixation, lies immediately upstream of nifa. we have sequenced the a. vinelandii nifl gene and found that it is more homologous in its c-terminal domain to the histidine protein kinases (hpks) than is k. pneumoniae nifl. in particular a. vinelandii nifl contains a conserved histidine at a position shown to be phosphorylated in other systems. both nifl proteins are homologous in ... | 1993 | 8231815 |
| the membrane topology of the rhizobium meliloti c4-dicarboxylate permease (dcta) as derived from protein fusions with escherichia coli k12 alkaline phosphatase (phoa) and beta-galactosidase (lacz). | the rhizobium meliloti dcta gene encodes the c4-dicarboxylate permease which mediates uptake of c4-dicarboxylates, both in free-living and symbiotic cells. based on the hydrophobicity of the dcta protein, 12 putative membrane spanning regions were predicted. the membrane topology was further analysed by isolating in vivo fusions of dcta to escherichia coli alkaline phosphatase (phoa) and e. coli beta-galactosidase (lacz). of 10 different fusions 7 indicated a periplasmic and 3 a cytoplasmic loca ... | 1993 | 8232193 |
| nopaline causes a conformational change in the nocr regulatory protein-nocr promoter complex of agrobacterium tumefaciens ti plasmid ptit37. | the nocr gene of agrobacterium tumefaciens ti plasmid ptit37 is the regulatory gene of the nopaline catabolism (noc) operon of ptit37. we have cloned and sequenced nocr, which encodes a dna-binding protein. the deduced amino acid sequence is similar to those of members of the lysr family of prokaryotic activator proteins. gel retardation experiments demonstrated that the nocr protein binds to the nocr promoter in both the presence and absence of nopaline. the increased mobility of the complex an ... | 1993 | 8232213 |
| preformed dimeric state of the sensor protein vira is involved in plant--agrobacterium signal transduction. | plant signal molecules such as acetosyringone and certain monosaccharides induce the expression of agrobacterium tumefaciens virulence (vir) genes, which are required for the processing, transfer, and possibly integration of a piece of the bacterial plasmid dna (t-dna) into the plant genome. two fo the vir genes, vira and virg, belonging to the bacterial two-component regulatory system family, control the induction of vir genes by plant signals. vira encodes a membrane-bound sensor kinase protei ... | 1993 | 8234338 |
| proposal for rejection of agrobacterium tumefaciens and revised descriptions for the genus agrobacterium and for agrobacterium radiobacter and agrobacterium rhizogenes. | the 16s rrna sequences of seven representative agrobacterium strains, eight representative rhizobium strains, and the type strains of azorhizobium caulinodans and bradyrhizobium japonicum were determined. these strains included the type strains of agrobacterium tumefaciens, agrobacterium rhizogenes, agrobacterium radiobacter, agrobacterium vitis, agrobacterium rubi, rhizobium fredii, rhizobium galegae, rhizobium huakuii, rhizobium leguminosarum, rhizobium loti, rhizobium meliloti, and rhizobium ... | 1993 | 8240952 |
| genomic heterogeneity among french rhizobium strains isolated from phaseolus vulgaris l. | levels of dna relatedness between strains isolated from root nodules of phaseolus vulgaris and reference strains of different rhizobium species were determined by performing dna-dna hybridization experiments (s1 nuclease method). the nine strains examined were members of three genomic groups previously delineated by a restriction fragment length polymorphism analysis among strains isolated from p. vulgaris at different sites in france. in agreement with the results of the restriction fragment le ... | 1993 | 8240956 |
| transcription in vitro promoted by the agrobacterium virg protein. | expression of the virulence genes (vir) on the hairy-root-inducing plasmid pria4 is induced by plant signals in agrobacterium cells through a two-component regulatory system, the vira-virg system. we constructed an in vitro transcription system that consisted of the purified virg protein and the agrobacterium rna polymerase holoenzyme. both versions of virg, the non-phosphorylated form and the vira-phosphorylated form, were active but showed different patterns of the ph-dependency for transcript ... | 1993 | 8243632 |
| altered-function mutations in the agrobacterium tumefaciens occr protein and in an occr-regulated promoter. | occr is a lysr-type transcriptional activator that controls the occq and trar promoters of octopine-type ti plasmids. the opine octopine converts occr from a repressor to an activator of occq, shortens the protein's dnase i footprint, and decreases the angle of an occr-caused dna bend at the occq promoter. in this study we first localized the cis-acting dna sequences required for regulated expression of occq. to understand better the mechanism of activation of occr, we isolated mutations both in ... | 1993 | 8244944 |
| identification and analysis of the rhizobium meliloti exoamonp genes involved in exopolysaccharide biosynthesis and mapping of promoters located on the exohklamonp fragment. | sequence analysis of a 7.494 kb dna fragment from megaplasmid 2 of rhizobium meliloti 2011 involved in exopolysaccharide i (eps i) biosynthesis revealed the presence of five exo genes designated exoa, exom, exon, exoo, and exop. exon was found to show strong homology to a udp-glucose pyrophosphorylase from acetobacter xylinum, whereas exoo displayed weak homologies to the nodc proteins from r. meliloti and r. loti. surprisingly, different mutations in exop resulted in divergent phenotypes. one e ... | 1993 | 8246891 |
| construction of multiple copy of alpha-domain gene fragment of human liver metallothionein ia in tandem arrays and its expression in transgenic tobacco plants. | metallothioneins (mt) are low molecular weight, cysteine-rich, metal-binding proteins. an mt molecule contains two domains which appear to act independently--an alpha-domain, which is characterized by cadmium-binding, and a beta-domain, which binds preferentially to copper. based on this conception, dna duplex encoding the alpha-domain (106 bp) of human mt-ia was constructed from a chemically-synthesized oligomer by repair synthesis and enzymatic ligation and cloned into puc19. the genes cloned ... | 1993 | 8248099 |
| constitutive or light-regulated expression of the rolc gene in transgenic potato plants has different effects on yield attributes and tuber carbohydrate composition. | tetraploid potato clones, transgenic for the rolc gene of agrobacterium rhizogenes under control of the light-inducible ribulose bisphosphate carboxylase small subunit promoter (rbcs-rolc), were compared, with respect to yield attributes and tuber carbohydrates, with transformed and untransformed controls and with 35s-rolc transgenic potato plants. in rbcs-rolc plants, the expression of the rolc gene was located mainly in leaves, while in 35s-rolc plant transcripts were detected as well in shoot ... | 1993 | 8251628 |
| single-copy t-dna insertions in arabidopsis are the predominant form of integration in root-derived transgenics, whereas multiple insertions are found in leaf discs. | different patterns of t-dna integration in arabidopsis were obtained that depended on whether a root or a leaf-disc transformation method was used. an examination of 82 individual transgenic arabidopsis plants, derived from 15 independent agrobacterium-mediated transformations in which different cointegrate and binary constructs were used, indicated that the transformation method had a significant influence on the type and copy number of t-dna integration events. southern hybridizations showed t ... | 1993 | 8251637 |
| lipo-oligosaccharides of rhizobium induce infection-related early nodulin gene expression in pea root hairs. | this paper shows that lipo-oligosaccharides (nod factors) synthesized by rhizobium bacteria elicit the induction of infection-related early nodulin genes (psenod5 and psenod12) in pea root hairs. r. leguminosarum bv. viciae secretes a mixture of nod factors containing a c18 fatty acid chain with 4 (c18:4) or 1 double bond (c18:1). purified nod factors harbouring either a c18:4 or a c18:1 acyl moiety induce the expression of the pea early nodulin genes, psenod5 and psenod12, but the kinetics of i ... | 1993 | 8252073 |
| presence of one linear and one circular chromosome in the agrobacterium tumefaciens c58 genome. | analysis of the entire agrobacterium tumefaciens c58 genome by pulsed-field gel electrophoresis (pfge) reveals four replicons: two large molecules of 3,000 and 2,100 kb, the 450-kb cryptic plasmid, and the 200-kb ti plasmid. digestion by paci or swai generated 12 or 14 fragments, respectively. the two megabase-sized replicons, used as probes, hybridize with different restriction fragments, showing that these replicons are two independent genetic entities. a 16s rrna probe and genes encoding func ... | 1993 | 8253676 |
| the chromosomal virulence gene, chve, of agrobacterium tumefaciens is regulated by a lysr family member. | certain plant phenolic compounds and monosaccharides induce the transcription of virulence (vir) genes of agrobacterium tumefaciens through the vira-virg two-component regulatory system. the product of the chromosomal virulence gene chve is homologous to galactose-binding protein of escherichia coli and is required for vir gene induction by sugars. adjacent to, but divergent in transcription from, chve is an open reading frame, now termed gbpr (galactose-binding protein regulator), that is homol ... | 1993 | 8253677 |
| genetic evidence for an interaction between the vira sensor protein and the chve sugar-binding protein of agrobacterium. | most vir genes of agrobacterium, which are required for tumorigenicity of the bacterium, are expressed in response to plant phenolics. the induction of vir is markedly enhanced by specific monosaccharides. signals generated by both types of compound are transduced into agrobacterium cells via the functions of the vira membrane-bound sensor protein. a putative sugar-binding protein, known as chve, also functions at a step of the enhancement of vir induction by monosaccharides. to investigate the ... | 1993 | 8253785 |
| transport of nucleic acids through membrane channels: snaking through small holes. | transport of nucleic acids through cell membranes is an essential biological process that occurs in all living organisms. this review focuses on two plant systems in which nucleic acid molecules are transported through membrane channels: transport of agrobacterium t-dna through nuclear pores and movement of plant viruses through intracellular connections. to provide a broader perspective, nuclear uptake of animal viruses and nuclear import/export of small nuclear (sn) rna and messenger (m) rna a ... | 1993 | 8257097 |
| identification of the sata gene encoding a streptogramin a acetyltransferase in enterococcus faecium bm4145. | enterococcus faecium bm4145, a clinical isolate from urine, was resistant to streptogramin group a antibiotics by inactivation. the strain harbored a plasmid containing a gene, sata, responsible for this resistance; this gene was cloned and sequenced. it encoded sata, a protein deduced to be 23,634 da in mass and homologous with a new family of chloramphenicol acetyltransferases described in agrobacterium tumefaciens, escherichia coli, pseudomonas aeruginosa, and staphylococcus aureus. the simil ... | 1993 | 8257133 |
| mutants of the two-component regulatory protein fixj of rhizobium meliloti that have increased activity at the nifa promoter. | fixl and fixj belong to a two-component regulatory system in rhizobium meliloti that induces the expression of numerous nitrogen-fixation genes during symbiosis with alfalfa. fixj is a positive activator required for transcription of the regulatory genes nifa and fixk, while fixl is an oxygen-binding hemoprotein capable of regulating the phosphorylation status of both itself and fixj, in response to oxygen availability. in this study, we isolated four fixj mutants that display increased activity ... | 1993 | 8262372 |
| site-specific cleavage and joining of single-stranded dna by vird2 protein of agrobacterium tumefaciens ti plasmids: analogy to bacterial conjugation. | as an early stage of plant transformation by agrobacterium tumefaciens, the ti plasmid is nicked at the border sequences that delimit the t-dna. cleavage results in covalent attachment of vird2 to the 5' terminal of the nicked strand by a process resembling initiation of dna transfer that occurs in the donor cell during bacterial conjugation. we demonstrate that this cleavage can be reproduced in vitro: vird2 protein, the border-cleaving enzyme, was overproduced and purified. cleavage assays wer ... | 1993 | 8265585 |
| efficient pathogen-derived resistance induced by integrated potato virus y coat protein gene in tobacco. | the coat protein (cp) gene from potato virus y (hungarian isolate, pvy-h) was engineered into agrobacterium tumefaciens binary vector for expression in different tobacco lines. three different nicotiana tabacum breeding lines were transformed and the integration of the cp gene was confirmed by pcr technique using genomic dna preparations. the transcription and expression of the integrated cp gene was detected by northern and western blots. pathogen-derived resistance was demonstrated by inoculat ... | 1993 | 8268262 |
| influence of growth conditions on production of capsular and extracellular polysaccharides by rhizobium leguminosarum. | the influence of growth rate and medium composition on exopolymer production by rhizobium leguminosarum was studied. when grown in medium containing 10 g/l mannitol and 1 g/l glutamic acid, rhizobium leguminosarum biovar trifolii ta-1 synthesized up to 2.0 g/l of extracellular polysaccharide (eps), and up to 1.6 g/l of capsular polysaccharide (cps). under non-growing cell conditions in medium without glutamic acid, cps synthesis by strain ta-1 could proceed to 2.1 g/l, while eps-production remai ... | 1993 | 8273998 |
| the persistence of engineered agrobacterium tumefaciens in agroinfected plants. | several plant species, including tomato (lycopersicon esculentum), gynura aurantiaca, avocado (persea americana), and grapefruit (citrus paradisi) grafted on troyer citrange (poncirus trifoliata x c. sinensis) were "agro-infected" with agrobacterium tumefaciens strain lba-4404, carrying a mini-ti plasmid with a dimeric cdna of citrus exocortis viroid (cevd). extracts prepared from tissues of the agroinfected plants 38-90 days after inoculation were plated on selective media and found to contain ... | 1993 | 8274776 |
| two binding sites for the plant transcription factor asf-1 can respond to auxin treatments in transgenic tobacco. | the hormone, auxin, plays an important role in the differentiation and growth of plant cells. a number of auxin-responsive genes have been characterized but until now minimal auxin-responsive cis-elements within these promoter regions have not been identified. here we show that two related dna sequences of 21 base pairs can respond to auxin treatment in transgenic tobacco. in contrast, treatments with cytokinin or abscisic acid do not cause any apparent increase in promoter activity of these cis ... | 1994 | 8276868 |
| phospholipid and fatty acid compositions of rhizobium leguminosarum biovar trifolii anu843 in relation to flavone-activated psym nod gene expression. | the phospholipid and associated fatty acid compositions of the bacterial symbiont of clover, rhizobium leguminosarum biovar trifolii wild-type anu843, was analyzed by two-dimensional silica thin-layer chromatography, fast atom bombardment-mass spectrometry, flame-ionization detection gas-liquid chromatography and combined gas-liquid chromatography/mass spectrometry. the phospholipid composition included phosphatidylethanolamine (15%), n-methylphosphatidylethanolamine (47%), n,n-dimethylphosphati ... | 1993 | 8277828 |
| molecular cloning, sequence and regulation of expression of the reca gene of the phototrophic bacterium rhodobacter sphaeroides. | the reca gene of rhodobacter sphaeroides 2.4.1 has been isolated by complementation of a uv-sensitive reca- mutant of pseudomonas aeruginosa. its complete nucleotide sequence consists of 1032 bp, encoding a polypeptide of 343 amino acids. the deduced amino acid sequence displayed highest identity to the reca proteins from rhizobium meliloti, rhizobium phaseoli, and agrobacterium tumefaciens. an escherichia coli-like sos consensus region, which functions as a binding site for the lexa repressor m ... | 1994 | 8277942 |
| molecular characterization and expression of alfalfa isoliquiritigenin 2'-o-methyltransferase, an enzyme specifically involved in the biosynthesis of an inducer of rhizobium meliloti nodulation genes. | a cdna clone encoding an o-methyltransferase (omt) from alfalfa has been isolated, which methylates the 2'-hydroxyl of isoliquiritigenin (2',4,4'-trihydroxychalcone) to form 4,4'-dihydroxy-2'-methoxychalcone, the most potent of the nod-gene-inducing flavonoid derivatives released from alfalfa roots. the cdna clone was identified on the basis of n-terminal sequence identity to purified s-adenosyl-l-methionine:isoliquiritigenin 2'-o-methyltransferase (chalcone omt) and expression of enzymatically ... | 1993 | 8281189 |
| identification and cloning of a cyclic beta-(1-->3), beta-(1-->6)-d-glucan synthesis locus from bradyrhizobium japonicum. | a cosmid clone complementing a cyclic beta-(1-->2)-glucan biosynthesis (ndvb) mutant of rhizobium meliloti was isolated from a bradyrhizobium japonicum gene library. this clone specified synthesis of beta-(1-->3), beta-(1-->6)-linked glucans in r. meliloti. the complemented strain was osmotically tolerant and symbiotically competent on alfalfa. thus, beta-(1-->3), beta-(1-->6)-glucans can substitute functionally for beta-(1-->2)-glucans in r. meliloti. | 1993 | 8282182 |
| role of the fixghi region of azorhizobium caulinodans in free-living and symbiotic nitrogen fixation. | a 19-kb dna region containing genes sharing homology with rhizobium meliloti fixnoqp and fixghi was isolated from a genomic library of azorhizobium caulinodans. identity of fixg was confirmed by partial nucleotide sequencing. mutant strains in the fixghi region were constructed by deletion or tn5 insertions. in contrast with the situation in r. meliloti, the mutants still displayed a significant nitrogenase activity in symbiosis. | 1993 | 8282187 |
| molecular characterization, nucleotide sequence, and expression of the flio, flip, fliq, and flir genes of escherichia coli. | the flil operon of escherichia coli contains seven genes that are involved in the biosynthesis and functioning of the flagellar organelle. dna sequences for the first three genes of this operon have been reported previously. a 2.2-kb psti restriction fragment was shown to complement known mutant alleles of the flio, flip, fliq, and flir genes, the four remaining genes of the flil operon. four open reading frames were identified by dna sequence analysis and correlated to their corresponding genes ... | 1994 | 8282695 |
| how does the t-dna of agrobacterium tumefaciens find its way into the plant cell nucleus? | agrobacterium tumefaciens causes the crown gall disease in plants by transferring a piece of dna, the t-dna, into the genome of the plant cell. the virulence protein vird2, tightly linked to the t-dna, is thought to direct it to the plant cell nucleus and to assist it in integration. the vird2 protein contains two nuclear localization signals (nls) which are functional both in yeast and in plant cells. one signal is located in the n-terminal part of the protein and resembles a single-cluster typ ... | 1993 | 8286434 |
| opine-regulated promoters and lysr-type regulators in the nopaline (noc) and octopine (occ) catabolic regions of ti plasmids of agrobacterium tumefaciens. | essential steps in the uptake and catabolism of the plant tumor metabolites nopaline and octopine in agrobacterium spp. are performed by proteins encoded in the nopaline catabolic (noc) and octopine catabolic (occ) regions of ti plasmids. we investigated the opine activation of the genes by using (i) promoter studies of agrobacterium spp. and (ii) analysis of the promoter interaction with the regulatory proteins nocr (noc) and occr (occ). the noc region contained two nopaline-induced promoters ( ... | 1994 | 8288543 |
| an insertional point mutation inactivates nolr repressor in rhizobium meliloti 1021. | in the majority of rhizobium meliloti isolates, nod gene expression is controlled by nolr, but this is not the case in a few strains including the widely used laboratory strain 1021. in 1021, the lack of nolr function was shown to be due to a single insertional mutation in the c-terminal coding sequence which abolished the dna-binding ability, though the helix-turn-helix motif remained intact. this indicates that the c-terminal part of the protein is also essential for dna binding. we conclude t ... | 1994 | 8288547 |
| agrobacterium t-strand production in vitro: sequence-specific cleavage and 5' protection of single-stranded dna templates by purified vird2 protein. | virulence proteins vird1 and vird2 are subunits of a relaxosome-like protein complex that mediates conjugational transfer of a ti plasmid segment, the t-dna, from agrobacterium into higher plants. the vird1-vird2 complex binds to 25-bp repeats at the borders of the t-dna and catalyzes sequence-specific nicking of the conjugative dna strand (the t-strand) at the third base of these repeats. nuclear localization signals present in vird2 target the t-strand to plant cell nuclei. in addition, vird2 ... | 1994 | 8290583 |
| phenotype and hormonal status of transgenic tobacco plants overexpressing the rola gene of agrobacterium rhizogenes t-dna. | the rola gene of the tl-dna of agrobacterium rhizogenes ri-plasmid plays a major role in establishing the hairy root syndrome in transgenic plants. transgenic tobacco plants (nicotiana tabacum l.) expressing constitutively the rola gene under the transcriptional control of the 35s rna promoter show pronounced phenotypical alterations. p35s-rola transgenic tobacco plants are characterized by stunted growth, dark green wrinkled leaves with an altered length-to-width ratio, condensed influorescence ... | 1993 | 8292784 |
| transgenic plants that express genes including the 3' untranslated region of the turnip yellow mosaic virus (tymv) genome are partially protected against tymv infection. | in order to evaluate new possibilities for protecting plants against virus infection by interference with viral replication, two chimeric genes were constructed in which the (+) strand 3'-terminal 100 nucleotides (nt) of the noncoding region of the turnip yellow mosaic virus (tymv) genome were placed downstream from the sense or antisense cat coding region. the two chimeric genes were then introduced into the genome of rapeseed (brassica napus) using an agrobacterium rhizogenes vector system. pl ... | 1993 | 8294045 |
| the survival of bacteria exposed to desiccation on surfaces associated with farm buildings. | the survival of 11 species of gram-negative and gram-positive bacteria was examined on different surfaces exposed to desiccation. there were large variations between species; pseudomonas spp. and rhizobium leguminosarum biovars survived for less than 2 d, whilst enterococcus spp. survived for more than 11 weeks. the type of surface on to which the bacteria were deposited affected survival, but with different effects between species. in addition the survival of spontaneous nalidixic acid-resistan ... | 1993 | 8294304 |
| mutants of agrobacterium vira that activate vir gene expression in the absence of the inducer acetosyringone. | in the presence of inducer molecules produced by wounded plants, the vira/virg two-component positive regulatory system of agrobacterium tumefaciens initiates transcription of virulence genes required for crown gall tumor formation. exactly how this system enables the bacterium to respond to an environmental signal is not known, but phosphorylation of vira and virg plays a role. to analyze further the function of vira, we chemically mutagenized the vira gene. two mutants that activate vir transc ... | 1994 | 8300595 |
| abc transporters: bacterial exporters. | the abc transporters (also called traffic atpases) make up a large superfamily of proteins which share a common function and a common atp-binding domain. abc transporters are classified into three major groups: bacterial importers (the periplasmic permeases), eukaryotic transporters, and bacterial exporters. we present a comprehensive review of the bacterial abc exporter group, which currently includes over 40 systems. the bacterial abc exporter systems are functionally subdivided on the basis o ... | 1993 | 8302219 |
| the binding site of the transcriptional activator virg from agrobacterium comprises both conserved and specific nonconserved sequences. | virulence genes of agrobacterium tumefaciens are transcriptionally activated in response to phenolic compounds and certain sugars. the transcription activator virg specifically binds to fragments containing the conserved vir box sequence present in the promoter region of all vir genes. this study shows that both the vir box as well as specific nonconserved sequences downstream of the vir box are required for virg binding and transcriptional activation. insertion of the identified virg binding si ... | 1994 | 8307169 |
| a widely conserved developmental sensor in bacteria? | | 1993 | 8310532 |
| rna-directed de novo methylation of genomic sequences in plants. | one monomeric and three oligomeric potato spindle tuber viroid (pstvd) cdna units were introduced into the tobacco genome via the agrobacterium-mediated leaf-disc transformation. southern analysis of the integrates revealed that only their pstvd-specific sequences become fully methylated, whereas the flanking t-dna and the genomic plant dna remain unaltered. viroid cdna methylation could only be observed after autonomous viroid rna-rna replication had taken place in these plants. these findings ... | 1994 | 8313476 |
| the nodl and nodj proteins from rhizobium and bradyrhizobium strains are similar to capsular polysaccharide secretion proteins from gram-negative bacteria. | the nodl and nodj nodulation proteins have been described in different rhizobium and bradyrhizobium species. the nodlj genes belong to the nod regulon. other genes from this regulon are involved in the biosynthesis and modification of lipo-oligosaccharide molecule(s) which are morphogenic signals when acting on legume roots. it has been proposed that the nodl and nodj proteins belong to a bacterial inner membrane transport system of small molecules. nucleotide sequencing of mudll pr13 insertions ... | 1993 | 8316086 |
| evidence that the nodulation regulatory gene nodd3 of rhizobium meliloti is transcribed from two separate promoters. | the bgl ii fragment carried in plasmid pmh903, which covers the nodd3 region of rhizobium meliloti, has been sequenced. by using both s1 nuclease mapping and primer extension, two transcription start sites were demonstrated in the sequence. after the first transcription start site, there were two open reading frames (orf) followed by the nodd3 coding sequence which was also preceded by the second promoter. the nodd3 gene under the first promoter mediated high, constitutive expression of nodc-lac ... | 1993 | 8318154 |
| the rhizobium-legume symbiosis: plant morphogenesis in a nodule. | development of the legume root nodule can be divided conceptually into two parallel processes. on the one hand, there is the induction of a nodule meristem and the progressive differentiation of specialised cells and tissues. on the other hand, there is cell and tissue invasion by rhizobium, which leads ultimately to the differentiation of intracellular bacteroids as specialised nitrogen-fixing endosymbionts. the early stages of plant-microbe communication seem to be mostly mediated by the excha ... | 1993 | 8318698 |
| flavonoid inducers of nodulation genes stimulate rhizobium fredii usda257 to export proteins into the environment. | | 1993 | 8318713 |
| isolation and characterization of a gene coding for a novel aspartate aminotransferase from rhizobium meliloti. | aspartate aminotransferase (aat) is an important enzyme in aspartate catabolism and biosynthesis and, by converting tricarboxylic acid cycle intermediates to amino acids, aat is also significant in linking carbon metabolism with nitrogen metabolism. to examine the role of aat in symbiotic nitrogen fixation further, plasmids encoding three different aminotransferases from rhizobium meliloti 104a14 were isolated by complementation of an escherichia coli auxotroph that lacks three aminotransferases ... | 1993 | 8320232 |
| regulation of syrm and nodd3 in rhizobium meliloti. | the early steps of symbiotic nodule formation by rhizobium on plants require coordinate expression of several nod gene operons, which is accomplished by the activating protein nodd. three different nodd proteins are encoded by sym plasmid genes in rhizobium meliloti, the alfalfa symbiont. nodd1 and nodd2 activate nod operons when rhizobium is exposed to host plant inducers. the third, nodd3, is an inducer-independent activator of nod operons. we previously observed that nodd3 carried on a multic ... | 1993 | 8325480 |
| pertussis toxin export requires accessory genes located downstream from the pertussis toxin operon. | pertussis toxin, a major virulence factor of bordetella pertussis, is an oligomeric protein composed of five different subunits that are exported individually to the periplasmic space by the signal peptide-dependent pathway. after assembly, the protein is exported from the periplasm to the extracellular compartment. we show that pertussis toxin secretion across the outer membrane requires the gene product of at least one gene (ptlc) that is located downstream from the pertussis toxin operon. the ... | 1993 | 8326857 |
| molecular analysis of a microaerobically induced operon required for hydrogenase synthesis in rhizobium leguminosarum biovar viciae. | the nucleotide sequence (6138 bp) of a microaerobically inducible region (hupv/vi) from the rhizobium leguminosarum bv. viciae hydrogenase gene cluster has been determined. six genes, arranged as a single operon, were identified, and designated hypa, b, f, c, d and e based on the sequence similarities of all of them, except hypf, to genes from the hydrogenase pleiotropic operon (hyp) from escherichia coli. the gene products from hypbfcde were identified by in vivo expression analysis in e. coli, ... | 1993 | 8326860 |
| enzyme polymorphism of azorhizobium strains and other stem- and root-nodulating bacteria isolated from sesbania rostrata. | relationships between bacterial groups nodulating sesbania rostrata were evaluated through examination of electrophoretic polymorphism of esterases and metabolic enzymes. the following conclusions were drawn: (i) the differentiation of two genomic species within azorhizobium strains and a group of non-identified strains (probably rhizobium) was strongly supported by enzyme electrophoresis; (ii) esterases were more electrophoretically polymorphic than metabolic enzymes, since 35 and 11 electropho ... | 1993 | 8327783 |
| enhancement of extracapsular polysaccharide synthesis in klebsiella pneumoniae by rmpa2, which shows homology to ntrc and fixj. | we determined the complete nucleotide sequence of a 2.1-kb hindiii-ecori fragment that was cloned from a resident large plasmid of klebsiella pneumoniae chedid, a highly virulent and mucoviscous strain of the o1:k2 serotype. this fragment encoded an ability to enhance k2 capsular polysaccharide synthesis in k. pneumoniae, and a 636-bp open reading frame (rmpa2) was found. the 411-bp rmpa reported to be involved in the virulence and mucoid phenotypes of k. pneumoniae by nassif et al. (mol. microb ... | 1993 | 8335346 |
| dynamic structure of agrobacterium tumefaciens ti plasmids. | agrobacterium tumefaciens c58f is a variant of strain c58 which generates a high proportion of avirulent mutants in the presence of the virulence (vir) gene inducer acetosyringone. these mutants are altered in the ti plasmid and do not respond to the acetosyringone signal (c. fortin, e. w. nester, and p. dion, j. bacteriol. 174:5676-5685, 1992). the physical organization of the ti plasmid was compared in strain c58 and its variant. one feature distinguishing ptic58f from its parent plasmid was t ... | 1993 | 8335635 |
| methoxylated fatty acids reported in rhizobium isolates arise from chemical alterations of common fatty acids upon acid-catalyzed transesterification procedures. | we obtained from a phospholipid extract of wild-type rhizobium leguminosarum bv. trifolii anu843 methoxylated fatty acids that had been previously reported as constitutive unusual rhizobium fatty acids. the use of deuterated reagents and subsequent gas-liquid chromatography-mass spectrometry analyses showed that these methoxylated fatty acid derivatives are the products of chemical alterations of common cyclopropane-containing and unsaturated fatty acids occurring during various acid-catalyzed t ... | 1993 | 8335647 |
| biosynthesis of succinoglycan, a symbiotically important exopolysaccharide of rhizobium meliloti. | the exo genes of rhizobium meliloti are needed for the synthesis of an acidic exopolysaccharide, succinoglycan. we have assigned biosynthetic roles to the products of the exo genes by characterizing succinoglycan biosynthetic intermediates from exo mutant strains. we propose a model of succinoglycan biosynthesis in which the products of the exoy and exof genes function in the addition of the first sugar, galactose, to the lipid carrier; the products of the exoa, exol, exom, exoo, exou, and exow ... | 1993 | 8343955 |
| nonreciprocal homologous recombination between agrobacterium transferred dna and a plant chromosomal locus. | previously, we demonstrated the occurrence of gene targeting in tobacco cells after agrobacterium-mediated transformation. in these experiments a defective kanamycin resistance (kmr) gene residing at a chromosomal location was restored via homologous recombination with an incoming transferred dna (t-dna) repair construct (psdm101) containing a different defective kmr gene. in this article we describe gene targeting experiments with the same target line, but using an improved repair construct, ps ... | 1993 | 8346254 |
| the rhizobium meliloti rhizopine mos locus is a mosaic structure facilitating its symbiotic regulation. | the rhizobium meliloti l5-30 mos locus, encoding biosynthesis of the rhizopine 3-o-methyl-scyllo-inosamine, is shown to be a mosaic structure. the mos locus consists of four open reading frames (orfs) (orf1 and mosabc) arranged in an operon structure. within this locus, several domains of homology with other prokaryotic symbiotic genes (nifh, fixa, fixu, and nift) are present, suggesting that this locus may represent a hot spot for rearrangement of symbiotic genes. unusually, these domains are p ... | 1993 | 8349559 |
| characterization of genes for synthesis and catabolism of a new rhizopine induced in nodules by rhizobium meliloti rm220-3: extension of the rhizopine concept. | rhizopines are selective growth substrates synthesized in nodules only by strains of rhizobia capable of their catabolism. we report the isolation and study of genes for the synthesis and catabolism of a new rhizopine, scyllo-inosamine (sia), from alfalfa nodules induced by rhizobium meliloti rm220-3. this compound is similar in structure to the previously described rhizopine 3-o-methyl-scyllo-inosamine from r. meliloti l5-30 (p.j. murphy, n. heycke, z. banfalvi, m.e. tate, f.j. de bruijn, a. ko ... | 1993 | 8349560 |
| subcellular localization of seven virb proteins of agrobacterium tumefaciens: implications for the formation of a t-dna transport structure. | plant cell transformation by agrobacterium tumefaciens involves the transfer of a single-stranded dna-protein complex (t-complex) from the bacterium to the plant cell. one of the least understood and important aspects of this process is how the t-complex exits the bacterium. the eleven virb gene products have been proposed to specify the dna export channel on the basis of their predicted hydrophobicity. to determine the cellular localization of the virb proteins, two different cell fractionation ... | 1993 | 8349563 |
| insect-resistant chrysanthemum calluses by introduction of a bacillus thuringiensis crystal protein gene. | a 3'-end truncated crystal protein gene, derived from bacillus thuringiensis (bt) subsp. aizawai 7.21, encoding the toxic fragment of the insecticidal protein cryia(b), was constructed. the gene was inserted into a transformation vector, also carrying the neomycin phosphotransferase ii (nptii) gene and the beta-glucuronidase (gus) gene, and introduced in the oncogenic agrobacterium tumefaciens strain a281, harbouring the ti-plasmid ptibo542. the recombinant agrobacterium strain was used to trans ... | 1993 | 8353535 |
| formation of a putative relaxation intermediate during t-dna processing directed by the agrobacterium tumefaciens vird1,d2 endonuclease. | during the initial stages of crown gall tumorigenesis, the t-dna region of the agrobacterium tumefaciens ti-plasmid is processed, resulting in the production of t-dna molecules that are subsequently transferred to the plant cell. processing of the t-dna in the bacterium involves the nicking of t-dna border sequences by an endonuclease encoded by the vird locus, and the subsequent tight (possibly covalent) association of the vird2 protein with the 5' end of the processed single-stranded or double ... | 1993 | 8355616 |
| fate of agrobacterium radiobacter k84 in the environment. | agrobacterium radiobacter k84 is an effective, commercially applied, biological control agent for the plant disease crown gall, yet little is known about the survival and dissemination of k84. to trace k84 in the environment, spontaneous antibiotic-resistant mutants were used. growth rates and phenotypes of streptomycin- or rifampin-resistant k84 were similar to those of the parental k84, except the rifampin-resistant mutant produced less agrocin 84 as determined by bioassay. k84 and a strain of ... | 1993 | 8357247 |
| expression of the arabidopsis ataux2-11 auxin-responsive gene in transgenic plants. | five constructions containing deletions of the promoter from an auxin-inducible gene of arabidopsis thaliana, ataux2-11, were fused to the coding region of the reporter gene lacz, which encodes beta-galactosidase, and a polyadenylation 3'-untranslated nopaline synthase sequence from agrobacterium. these chimeric genes were introduced into arabidopsis by agrobacterium tumefaciens-mediated transformation, and expression of the gene was examined by spectrophotometric and histochemical analyses. a 6 ... | 1993 | 8358026 |
| in planta analysis of the agrobacterium tumefaciens t-cyt gene promoter: identification of an upstream region essential for promoter activity in leaf, stem and root cells of transgenic tobacco. | the promoter region of the agrobacterium tumefaciens t-cyt gene was fused to a beta-glucuronidase (gusa) reporter gene and introduced into tobacco plants. detection of gusa expression in transgenic f1 progeny revealed that the t-cyt promoter is active in many, if not all, cell types in leaves, stems and roots of fully developed plants. developmental stage-dependent promoter activity was observed in seedlings. analysis of 5'-deleted promoter fragments showed that sequences located between positio ... | 1993 | 8358039 |
| [effect of synthesizing molecules of double-stranded rna in transgenic tobacco plants on resistance to tobacco mosaic virus]. | | 1993 | 8358319 |
| the presence of a novel type of surface polysaccharide in rhizobium meliloti requires a new fatty acid synthase-like gene cluster involved in symbiotic nodule development. | bacterial exopolysaccharide (eps) and lipopolysaccharide (lps) molecules have been shown to play important roles in plant-bacterium interactions. here we have demonstrated that the fix-23 loci, which compensate for exo mutations during symbiotic nodule development, are involved in the production of a novel polysaccharide that is rich in 3-deoxy-d-manno-2-octulosonic acid (kdo) but is not the classical lps. this molecule is likely to be a surface antigen since antiserum to whole rhizobium melilot ... | 1993 | 8361353 |
| phylogenetic grouping and identification of rhizobium isolates on the basis of random amplified polymorphic dna profiles. | through the use of a single, random 15mer as a primer, between 1 and 12 dna amplification products were obtained per strain from a selection of 84 rhizobium and bradyrhizobium isolates. a principal-coordinate analysis was used to analyse the resulting amplified dna profiles and it was possible to assign isolates to specific groupings. within the species rhizobium leguminosarum, the biovar phaseoli formed a distinct group from the other biovars of the species, viciae and trifolii, which grouped t ... | 1993 | 8364802 |
| melanin production by rhizobium meliloti gr4 is linked to nonsymbiotic plasmid prmegr4b: cloning, sequencing, and expression of the tyrosinase gene mepa. | melanin production by rhizobium meliloti gr4 is linked to nonsymbiotic plasmid prmegr4b (140 mda). transfer of this plasmid to gr4-cured derivatives or to agrobacterium tumefaciens enables these bacteria to produce melanin. sequence analysis of a 3.5-kb psti fragment of plasmid prmegr4b has revealed the presence of a open reading frame 1,481-bp that codes for a protein whose sequence shows strong homology to two conserved regions involved in copper binding in tyrosinases and hemocyanins. in vitr ... | 1993 | 8366027 |
| genetic analysis of the agrocinopine catabolic region of agrobacterium tumefaciens ti plasmid ptic58, which encodes genes required for opine and agrocin 84 transport. | the acc region, subcloned from ptic58 of classical nopaline and agrocinopine a and b agrobacterium tumefaciens c58, allowed agrobacteria to grow using agrocinopine b as the sole source of carbon and energy. acc is approximately 6 kb in size. it consists of at least five genes, acca through acce, as defined by complementation analysis using subcloned fragments and transposon insertion mutations of acc carried on different plasmids within the same cell. all five regions are required for agrocin 84 ... | 1993 | 8366042 |
| the chimeric vira-tar receptor protein is locked into a highly responsive state. | the wild-type vira protein is known to be responsive not only to phenolic compounds but also to sugars via the chve protein (g. a. cangelosi, r. g. ankenbauer, and e. w. nester, proc. natl. acad. sci. usa 87:6708-6712, 1990, and n. shimoda, a. toyoda-yamamoto, j. nagamine, s. usami, m. katayama, y. sakagami, and y. machida, proc. natl. acad. sci. usa 87:6684-6688, 1990). it is shown here that the mutant vira(ser-44, arg-45) protein and the chimeric vira-tar protein are no longer responsive to su ... | 1993 | 8366057 |
| molecular cloning, identification, and sequence of the hyaluronan synthase gene from group a streptococcus pyogenes. | the hyaluronan (ha) synthase of group a streptococci has been identified by transposon mutagenesis and deletion analysis. the genes for the ha synthase and a recently identified udp-glc dehydrogenase (dougherty, b. a., and van de rijn, i. (1993) j. biol. chem. 268, 7118-7124) reside on a contiguous stretch of 3.2-kilobase pair dna that can direct ha biosynthesis in enterococcus faecalis and escherichia coli as well as mutant streptococcus (deangelis, p. l., papaconstantinou, j., and weigel, p. h ... | 1993 | 8366070 |
| sequence of the rhizobium leguminosarum biovar phaseoli syrm gene. | | 1993 | 8367305 |