| a chromosomal agrobacterium tumefaciens gene required for effective plant signal transduction. | the vir gene products of agrobacterium tumefaciens carry out the transfer of t-dna to the plant genome. effective transcriptional induction of the vir genes by plant signal molecules is controlled by two vir gene products, vira and virg. in this study we have identified and cloned a chromosomal region which is also required for vir gene induction. transposon insertions within this region reduce induction significantly and strongly attenuate virulence, resulting in a restricted host range for inf ... | 1990 | 2156804 |
| overexpression of vird1 and vird2 genes in agrobacterium tumefaciens enhances t-complex formation and plant transformation. | the vird1 and vird2 proteins encoded by an inducible locus of the virulence (vir) region of the agrobacterium tumefaciens ti plasmid are required for site-specific nicking at t-dna border sites. we have determined the nucleotide sequence of a 3.6-kilobase-pair fragment carrying the vird locus from nopaline ti plasmid ptic58. in contrast to the previous report (hagiya et al., proc. natl. acad. sci. usa 82:2669-2673, 1985), we found that the first three open reading frames were capable of encoding ... | 1990 | 2165478 |
| re-examination of cellular cyclic beta-1,2-glucans of rhizobiaceae: distribution of ring sizes and degrees of glycerol-1-phosphate substitution. | gel-filtration and thin layer chromatography of low molecular weight carbohydrates from culture filtrates of agrobacterium radiobacter, isolate ii, have shown, that next to the neutral beta-1,2-glucan fraction a major acidic fraction was present which was found to be glycerophosphorylated cyclic beta-1,2-glucans. re-examination of cyclic beta-1,2-glucan preparations which had been obtained by extraction of rhizobium cells with hot phenol-water also showed these acidic modified beta-1,2-glucans t ... | 1990 | 2321938 |
| efficient transformation of agrobacterium tumefaciens by electroporation. | high-voltage electroporation was used to transform agrobacterium tumefaciens strains a136 and a348, reaching the efficiency of 1-3 x 10(8) transformants/micrograms dna. transformation frequency was dependent on the electrical field strength and the pulse length. no significant reduction in transformation efficiency was observed when the transforming dna contained sites sensitive to endonuclease atuci of a. tumefaciens. | 1990 | 2165971 |
| expression of the agrobacterium tumefaciens chvb virulence region in azospirillum spp. | inner membranes of azospirillum brasilense incubated with udp-glucose were unable to synthesize beta-(1-2) glucan and lacked the 235-kilodalton intermediate protein known to be involved in the synthesis of beta-(1-2) glucan in agrobacterium tumefaciens and rhizobium meliloti. inner membranes of a. brasilense strains carrying a cosmid containing the chromosomal virulence genes chva and chvb of agrobacterium tumefaciens formed beta-(1-2) glucan in vitro and synthesized the 235-kilodalton intermedi ... | 1990 | 2332404 |
| in vitro antibacterial activities of three plants used in traditional medicine in sierra leone. | the antibacterial activities of the methanol and hot and cold aqueous extracts of the leaves of aspilia africana, ficus exasperata and mareya micrantha were bioassayed against three gram-negative and three gram-positive bacterial species: aerobacter aerogenes, agrobacterium tumefaciens, bacillus subtilis, clostridium sporogenes, escherichia coli and staphylococcus aureus. the methanol and aqueous extracts of the leaves of aspilia africana and mareya micrantha and the undiluted oil of m. micranth ... | 1990 | 2335960 |
| selection for wild type size derivatives of tomato golden mosaic virus during systemic infection. | a chimeric tomato golden mosaic virus (tgmv) a component dna, which results from replacement of the coding region of the viral coat protein gene (cp) with the larger bacterial beta-glucuronidase coding sequence (gus), can replicate in agroinoculated leaf discs but is unstable in systemically infected plants (1). we have made similar replacements of the tgmv cp gene with the gus coding sequence in both the sense and antisense orientations. both derivatives replicated in leaf discs inoculated via ... | 1990 | 2336387 |
| pica, a novel plant-inducible locus on the agrobacterium tumefaciens chromosome. | we used the transposon mu di1681 to identify genes on the agrobacterium tumefaciens chromosome that are inducible by extracts from carrot roots. one such locus (pica, for plant inducible chromosomal), harbored by a. tumefaciens at156, was inducible 10- to 50-fold by these extracts. mutation of pica had no detectable effect upon bacterial growth or virulence under laboratory assay conditions. however, a. tumefaciens cells harboring a mutated pica locus aggregated into long "ropes" when incubated ... | 1990 | 2170328 |
| plant chromosome/marker gene fusion assay for study of normal and truncated t-dna integration events. | during agrobacterium tumefaciens infection, the t-dna flanked by 24 bp imperfect direct repeats is transferred and stably integrated into the plant chromosome at random positions. here we measured the frequency with which a promoterless reporter gene is activated after insertion into the nicotiana tabacum sr1 genome. when adjacent to the right or left t-dna border sequences, at least 35% of the transformants express the marker gene, suggesting preferential t-dna insertion (greater than 70%) in t ... | 1990 | 2177527 |
| expression of agrobacterium rhizogenes rolb gene fusions in escherichia coli: production of antibodies against the rolb protein. | expression of the rolb gene of agrobacterium rhizogenes tl-dna is sufficient to trigger root differentiation in transformed plant cells. to investigate the role of rolb in differentiation, a large portion of rolb, comprising about 90% of its c-terminal coding sequence, was cloned into vectors pex34 and pea305 in frame with the truncated n termini of the pl-ms2 phage dna polymerase and, respectively, the ptac-c its phage lambda repressor gene. hybrid proteins were expressed from both fusions and ... | 1990 | 2185136 |
| transcriptional induction of an agrobacterium regulatory gene at tandem promoters by plant-released phenolic compounds, phosphate starvation, and acidic growth media. | transcription of the virg gene of agrobacterium tumefaciens was previously shown to be expressed from two tandem promoters and to be responsive to three stimuli: plant-released phenolic compounds, phosphate starvation, and acidic media. in this report, i describe a set of deletions and other alterations of the 5' end of virg that show that the upstream promoter (p1) is necessary for induction by phenolic compounds and by phosphate starvation, whereas the downstream promoter (p2) is induced by ac ... | 1990 | 2185220 |
| characteristics of the nopaline catabolic plasmid in agrobacterium strains k84 and k1026 used for biological control of crown gall disease. | wild-type agrobacterium radiobacter strain 84 and its tra- derivative k1026, used for biological control of crown gall disease, each contain the plasmid patk84b. it confers incompatibility to tumor-inducing (ti) plasmids of pathogenic a. tumefaciens, thus preventing transfer of ti plasmids into k84 and k1026, and the consequent development of pathogens resistant to the specific antibiotic, agrocin 84 produced by k84 and k1026. patk84b also resembles one group of ti plasmids in its capacity for d ... | 1990 | 2194227 |
| complementation analysis of agrobacterium tumefaciens ti plasmid virb genes by use of a vir promoter expression vector: virb9, virb10, and virb11 are essential virulence genes. | the virb gene products of the agrobacterium tumefaciens tumor-inducing (ti) plasmid have been proposed to mediate t-dna transport through the bacterial cell wall into plant cells. previous genetic analysis of the approximately 9.5-kilobase-pair virb operon has been limited to transposon insertion mutagenesis. due to the polarity of the transposon insertions, only the last gene in the operon, virb11, is known to provide an essential virulence function. we have now begun to assess the contribution ... | 1990 | 2203743 |
| extrachromosomal homologous recombination and gene targeting in plant cells after agrobacterium mediated transformation. | we determined whether t-dna molecules introduced into plant cells using agrobacterium are suitable substrates for homologous recombination. for the detection of such recombination events different mutant versions of a nptii construct were used. in a first set of experiments protoplasts of nicotiana tabacum sr1 were cocultivated with two agrobacterium tumefaciens strains. each strain contained a different t-dna, one carrying a 5' deleted nptii gene and the other a nptii gene with a 3' deletion. a ... | 1990 | 2209538 |
| techniques in plant molecular biology--progress and problems. | progress in plant molecular biology has been dependent on efficient methods of introducing foreign dna into plant cells. gene transfer into plant cells can be achieved by either direct uptake of dna or the natural process of gene transfer carried out by the soil bacterium agrobacterium. versatile gene-transfer vectors have been developed for use with agrobacterium and more recently vectors based on the genomes of plant viruses have become available. using this technology the expression of foreig ... | 1990 | 2209611 |
| inhibition by agrobacterium tumefaciens and pseudomonas savastanoi of development of the hypersensitive response elicited by pseudomonas syringae pv. phaseolicola. | injection into tobacco leaves of biotype 1 agrobacterium tumefaciens or of pseudomonas savastanoi inhibited the development of a visible hypersensitive response to the subsequent injection at the same site of pseudomonas syringae pv. phaseolicola. this interference with the hypersensitive response was not seen with injection of bacterial growth medium or escherichia coli cells. live a. tumefaciens cells were required for the inhibitory effect. various mutants and strains of a. tumefaciens were e ... | 1990 | 2211508 |
| genetic and sequence analysis of an 8.7-kilobase pseudomonas denitrificans fragment carrying eight genes involved in transformation of precorrin-2 to cobyrinic acid. | a 8.7-kilobase dna fragment carrying pseudomonas denitrificans cob genes has been sequenced. the nucleotide sequence and the genetic analysis revealed that this fragment carries eight different cob genes (cobf to cobm). six of these genes have the characteristics of translationally coupled genes. cobi has been identified as s-adenosyl-l-methionine (sam):precorrin-2 methyltransferase structural gene because the encoded protein has the same nh2 terminus and molecular weight as those of the purifie ... | 1990 | 2211521 |
| mutational analysis of the virg protein, a transcriptional activator of agrobacterium tumefaciens virulence genes. | the virg protein of agrobacterium tumefaciens is required in conjunction with the vira protein for transcriptional activation of the virulence (vir) genes in response to plant phenolic compounds. these proteins are members of a family of two component regulatory systems. vir genes are activated via a cascade of phosphorylation reactions involving a specific aspartic acid residue of the virg protein. we have conducted a mutational analysis of the virg protein. by mutating conserved and nonconserv ... | 1990 | 2211523 |
| transgenic nicotiana debneyii expressing viral coat protein are resistant to potato virus s infection. | the coat protein gene from potato virus s (pvs) was introduced into nicotiana debneyii by leaf disc transformation using agrobacterium tumefaciens. transgenic plants expressing the viral coat protein were highly resistant to subsequent infection by the me strain of pvs as indicated by an absence of symptom development and a lack of accumulation of virus in both the inoculated and upper leaves. as in reported experiments with plants expressing potato virus x coat protein, plants expressing pvs co ... | 1990 | 2212996 |
| isolation of the replication dna region from a rhizobium plasmid and examination of its potential as a replicon for rhizobiaceae cloning vectors. | the dna region essential for replication and stability of a native plasmid (ptm5) from rhizobium sp. (hedysarum) has been identified and isolated within a 5.4-kb psti restriction fragment. the isolation of this region was accomplished by cloning endonuclease-restricted ptm5 dna into a cole1-type replicon and selecting the recombinant plasmids containing the ptm5 replicator (ptm5 derivative plasmids) by their ability to replicate in rhizobium. dna homology studies revealed that ptm5-like replicon ... | 1990 | 2217572 |
| analysis of cell division gene ftsz (sulb) from gram-negative and gram-positive bacteria. | the ftsz (sulb) gene of escherichia coli codes for a 40,000-dalton protein that carries out a key step in the cell division pathway. the presence of an ftsz gene protein in other bacterial species was examined by a combination of southern blot and western blot analyses. southern blot analysis of genomic restriction digests revealed that many bacteria, including species from six members of the family enterobacteriaceae and from pseudomonas aeruginosa and agrobacterium tumefaciens, contained seque ... | 1987 | 2432055 |
| agrobacterium rhizogenes mutants that fail to bind to plant cells. | transposon insertion mutants of agrobacterium rhizogenes were screened to obtain mutant bacteria that failed to bind to carrot suspension culture cells. a light microscope binding assay was used. the bacterial isolates that were reduced in binding to carrot cells were all avirulent on bryophyllum diagremontiana leaves and on carrot root disks. the mutants did not appear to be altered in cellulose production. the composition of the medium affected the ability of the parent and mutant bacteria to ... | 1990 | 2228955 |
| genes responsible for the supervirulence phenotype of agrobacterium tumefaciens a281. | agrobacterium tumefaciens a281 induces large, rapidly appearing tumors on a variety of plants and has a wider host range than other strains of a. tumefaciens. by using tn3hoho1 transposon mutagenesis and complementation analysis, a 2.5-kilobase dna fragment which is responsible for the supervirulence phenotype was identified in the virulence (vir) region of the ti plasmid. this fragment contains the virg locus, as well as the 3' end of the virb operon. a clone of this fragment conferred the supe ... | 1987 | 2443480 |
| binding of the regulatory protein virg to the phased signal sequences upstream from virulence genes on the hairy-root-inducing plasmid. | the virg protein is a positive regulator for the virulence genes of which expression is induced by a plant factor, and is essential for agrobacterium pathogenicity on dicotyledonous plants. the virg protein of the hairy-root-inducing plasmid a4 was overproduced in escherichia coli cells, and purified to homogeneity. dnase i footprinting experiments revealed that the purified virg protein was bound to the upstream region of virulence genes including the phased vir box sequences, which had been pr ... | 1990 | 2231718 |
| enhancer sequences from arabidopsis thaliana obtained by library transformation of nicotiana tabacum. | in this paper we report on the use of a bidirectional enhancer cloning vehicle to isolate and characterize new enhancer sequences from arabidopsis thaliana. a library of a. thaliana genomic sau3a segments was constructed in escherichia coli in the binary plasmid enhancer cloning vehicle proa97. the t-dna based vector carries abbreviated tata regions from the cauliflower mosaic virus 35s transcription unit upstream of two genes. the library was transferred via triparental mating into agrobacteriu ... | 1990 | 2250645 |
| selective recovery of foreign gene transcripts as virus-like particles in tmv-infected transgenic tobaccos. | a short origin-of-assembly sequence (oas) located in the 30kda movement protein gene, about 1.0kb from the 3'-end of the common strain of tobacco mosaic virus (tmv) rna, nucleates encapsidation of the 6395-nucleotide-long genome by tmv coat protein in vitro, and presumably also in vivo. single-stranded rnas containing a foreign reporter gene sequence and the tmv oas at their 5' - and 3' -ends, respectively, can be synthesized in vitro from recombinant sp6-transcription plasmids and will assemble ... | 1988 | 2453837 |
| agrobacterium in plant disease, biological disease control and plant genetic engineering. | plant pathogenic strains of agrobacterium cause crown gall and hairy-root diseases. the abnormal cell proliferation of diseased tissues results from elevated plant hormonal levels within them. these levels are consequent upon the transfer of dna portions (t-dna) from agrobacterium plasmids to host nuclei where they are integrated and where genes for hormone synthesis, borne on the t-dna, are expressed in transformed host cells. this process has been exploited in plant genetic engineering by prod ... | 1990 | 2267572 |
| the maize en-1/spm element transposes in potato. | the maize transposable element en-1 has been introduced into a diploid potato line via transformation with agrobacterium tumefaciens. the element is transcriptionally active in potato. numerous en specific rnas are observed, including a 6 kb transcript characteristic of an active en-1 element in maize. in contrast to maize, where the 6.0 kb transcript is hardly detectable, this transcript is very abundant in the transgenic potato. transposition of en-1 in the potato clone was analysed by souther ... | 1989 | 2475754 |
| overproduction of alfalfa glutamine synthetase in transgenic tobacco plants. | we have obtained transgenic tobacco plants overexpressing the enzyme glutamine synthetase (gs) by fusing an alfalfa gs gene to the cauliflower mosaic virus 35s promotor and integrating it into nicotiana tabacum var. w38 plants by agrobacterium tumefaciens mediated gene transfer. the amount of rna specific to alfalfa gs was about 10 times higher in transgenic tobacco plants than in alfalfa. the alfalfa gs produced by these transgenic plants was identified by western blotting and represented 5% of ... | 1989 | 2475755 |
| identification and quantitation of corrinoid precursors of cobalamin from pseudomonas denitrificans by high-performance liquid chromatography. | after initial pretreatment for removal of interfering substances, corrinoid precursors of cobalamin from cultures of pseudomonas denitrificans were separated by hplc with a gradient elution system. in this system, all the following compounds are separated in their dicyano form, and retention times are given: cobyrinic acid; cobyrinic acid a-amide; cobyrinic acid c-amide; cobyrinic acid g-amide; cobyrinic acid a,g-diamide; cobyrinic acid c,g-diamide; cobyrinic acid a,c-diamide; cobyrinic acid a,c ... | 1990 | 2278386 |
| characterization of two genes encoding small heat-shock proteins in arabidopsis thaliana. | using the technique of differential hybridization screening, we have isolated the cdnas for two low-molecular-mass heat-shock proteins and their corresponding genes, hsp17.4 and hsp18.2, from arabidopsis thaliana. these two genes encode polypeptides that are 79.2% identical to each other with respect to amino acid sequence, and contain several overlapping sequences that are similar to the consensus sequences for the heat-shock elements (hse) in drosophila in the regions upstream from the promote ... | 1989 | 2482931 |
| isolation, expression and phylogenetic inheritance of an acetolactate synthase gene from brassica napus. | an acetolactate synthase gene was isolated and characterized from brassica napus. this b. napus acetolactate synthase gene encodes a deduced polypeptide sequence of 637 amino acids which is 85% homologous to the corresponding proposed gene product from arabidopsis thaliana. peptide domains recently associated with herbicide resistance/sensitivity are conserved between the two sequences. from southern analysis we conclude that the gene isolated is one member of a multigene acetolactate synthase g ... | 1989 | 2482934 |
| biochemical characterization of avirulent exoc mutants of agrobacterium tumefaciens. | the synthesis of periplasmic beta(1-2)glucan is required for crown gall tumor formation by agrobacterium tumefaciens and for effective nodulation of alfalfa by rhizobium meliloti. the exoc (psca) gene is required for this synthesis by both bacteria as well as for the synthesis of capsular polysaccharide and normal lipopolysaccharide. we tested the possibility that the pleiotropic exoc phenotype is due to a defect in the synthesis of an intermediate common to several polysaccharide biosynthetic p ... | 1990 | 2307661 |
| correction: characterization of the virb operon from agrobacterium tumefaciens ti plasmid. | | 1990 | 2307685 |
| binding-protein-dependent lactose transport in agrobacterium radiobacter. | agrobacterium radiobacter ncib 11883 was grown in lactose-limited continuous culture at a dilution rate of 0.045/h. washed cells transported [14c]lactose and [methyl-14c]beta-d-thiogalactoside, a nonmetabolisable analog of lactose, at similar rates and with similar affinities (km for transport, less than 1 microm). transport was inhibited to various extents by the uncoupling agent carbonyl cyanide p-trifluoromethoxyphenylhydrazone, by unlabeled beta-galactosides and d-galactose, and by osmotic s ... | 1990 | 2318800 |
| osmosensitivity phenotypes of agrobacterium tumefaciens mutants that lack periplasmic beta-1,2-glucan. | the periplasmic cyclic beta-1,2-glucan of agrobacterium tumefaciens is believed to maintain high osmolarity in the periplasm during growth of the bacteria on low-osmotic-strength media. strains with mutations in the chva or chvb gene do not accumulate beta-1,2-glucan in their periplasm and exhibit pleiotropic phenotypes, including inability to form crown gall tumors on plants. we examined the effects of medium osmolarity to determine whether some or all of these phenotypes result from suboptimal ... | 1990 | 2318812 |
| transformation of plant cells via agrobacterium. | | 1989 | 2491660 |
| antisense rna inhibition of beta-glucuronidase gene expression in transgenic tobacco plants. | antisense rna was used to specifically inhibit the expression of a gus gene introduced in a transgenic plant. a tobacco transformant containing a single intact copy of the gus gene and showing relatively high constitutive levels of gus activity (gus +) was re-transformed with an agrobacterium ti-derived binary vector containing an antisense version of this reporter gene. the sense and antisense gus genes were each under the regulation of the camv 35s promoter. re-transformed plants contained 1-5 ... | 1989 | 2491663 |
| expression of a c3 plant rubisco ssu gene in regenerated c4 flaveria plants. | we report the successful transformation, via agrobacterium tumefaciens infection, and regeneration of two species of the genus flaveria: f. brownii and f. palmeri. we document the expression of a c3 plant gene, an abundantly expressed ribulose 1,5-bisphosphate carboxylase/oxygenase small subunit gene isolated from petunia, in these c4 plants. the organ-specific expression of this petunia gene in flaveria brownii is qualitatively identical to its endogenous pattern of expression. | 1989 | 2491665 |
| virulence genes promote conjugative transfer of the ti plasmid between agrobacterium strains. | certain virulence region operons of the agrobacterium tumefaciens ti plasmid promoted conjugative ti plasmid transfer. mutations in the vir region of ptic58 inhibited conjugative plasmid transfer between a. tumefaciens strains. mutations in vira, virg, 5' virb, and vire had the greatest effect on plasmid transfer, and mutations in virc had no effect. transfer inhibition in vir mutants occurred in the presence or absence of acetosyringone. | 1990 | 2318813 |
| construction of an intron-containing marker gene: splicing of the intron in transgenic plants and its use in monitoring early events in agrobacterium-mediated plant transformation. | agrobacterium tumefaciens is a commonly used tool for transforming dicotyledonous plants. the underlying mechanism of transformation however is not very well understood. one problem complicating the analysis of this mechanism is the fact that most indicator genes are already active in agrobacterium, thereby preventing the precise determination of timing and localisation of t-dna transfer to plant cells. in order to overcome this obstacle a modified prokaryotic indicator gene was constructed. the ... | 1990 | 2325623 |
| single-stranded dna used as an efficient new vehicle for transformation of plant protoplasts. | in relation to the question which dna form (single- or double-stranded) is transferred by agrobacterium tumefaciens to plant cells, we studied the behaviour of single-stranded dna, as compared to double-stranded dna, when it is introduced into plant protoplasts by electroporation. to this end, we cloned a construct with a plant nptii gene as well as a cat gene in the m13 vectors tg130 and tg131. we found that both complementary single-stranded molecules gave rise to substantial cat activity in p ... | 1989 | 2491686 |
| small, stable shuttle vectors for use in xanthomonas. | plasmids from three broad-host-range (bhr) incompatibility groups (inc) were evaluated for use as cloning vectors in xanthomonas campestris pv. malvacearum (xcm), the causal agent of bacterial blight of cotton. the incp vectors plafr3 and pvk102 could not be introduced into xcm at a significant frequency (less than 1 x 10(-10] and incq vectors such as pkt210 were unstable in their maintenance and tended to delete cloned inserts. incw vectors such as psa747 also were lost readily from xcm in the ... | 1990 | 2341039 |
| structure and expression of the lactococcus lactis gene for phospho-beta-galactosidase (lacg) in escherichia coli and l. lactis. | the lactococcus lactis subsp. lactis 712 lacg gene encoding phospho-beta-galactosidase was isolated from the lactose mini-plasmid pmg820 and cloned and expressed in escherichia coli and l. lactis. the low phospho-beta-galactosidase activity in l. lactis transformed with high-copy-number plasmids containing the lacg gene contrasted with the high activity found in l. lactis containing the original, low-copy-number lactose plasmid pmg820, and indicated that the original lactose promoter was absent ... | 1989 | 2515252 |
| plant nuclear factor asf-1 binds to an essential region of the nopaline synthase promoter. | we have characterized a tobacco nuclear factor that binds to the -118 region of the nopaline synthase (nos) promoter from the ti plasmid of agrobacterium tumefaciens. the binding site for this factor, identified by dnase i footprinting, encompasses the region from -138 to -103 of the nos promoter. this region, which contains a potential z-dna-forming sequence, was previously shown to be essential for nos promoter activity in transgenic tobacco. a synthetic 21-base pair sequence from the protecte ... | 1990 | 2351681 |
| the virb operon of agrobacterium tumefaciens ptic58 encodes 11 open reading frames. | agrobacterium tumefaciens genetically transforms plant cells by transferring a copy of its t-dna to the plant where it is integrated and stably maintained. in the presence of wounded plant cells this process is activated and mediated by the products of the vir genes which are grouped into six distinct loci. the largest is the virb locus spanning 9.5 kb. transposon mutagenesis studies have shown that virb gene products are required for virulence but their functions remain largely unknown. to prov ... | 1990 | 2370849 |
| osmotic regulation of beta(1-2) glucan synthesis in members of the family rhizobiaceae. | high osmolarity in the culture medium of growing agrobacterium tumefaciens strongly inhibited the accumulation of cellular beta(1-2) glucan. however, the enzymatic system required for the synthesis of this polysaccharide from udp-glucose was not repressed by high osmolarity. mutants of a. tumefaciens and rhizobium meliloti affected in beta(1-2) glucan synthesis were unable to grow normally in low-osmolarity media. | 1990 | 2376569 |
| growth of agrobacterium tumefaciens under octopine limitation in chemostats. | agrobacterium tumefaciens b6 and atcc 15955 were grown under octopine or glutamate limitation in chemostats. examination of the maximum specific growth rate (mu max) and substrate affinity (ks) for each strain indicated that strain b6 was highly inefficient in its use of octopine as either a nitrogen or carbon source compared with strain atcc 15955. examination of the yield coefficients showed that in both strains octopine was used more efficiently as a nitrogen source than as a carbon source. t ... | 1990 | 2383013 |
| phosphorylation of the virg protein of agrobacterium tumefaciens by the autophosphorylated vira protein: essential role in biological activity of virg. | agrobacterium tumefaciens virulence genes are induced by plant signals through the vira-virg two-component regulatory system. the vira protein is a membrane-spanning sensor molecule that possesses an autophosphorylating activity, and the virg protein is a sequence-specific dna-binding protein. in this report, we demonstrate that the virg protein is phosphorylated by the vira protein and that the phosphate is directly transferred from the phosphorylated vira molecule (phosphohistidine) to the vir ... | 1990 | 2394678 |
| identification of a virb10 protein aggregate in the inner membrane of agrobacterium tumefaciens. | products of the virb operon are proposed components of a membrane-associated t-dna transport apparatus in agrobacterium tumefaciens. here we identified the virb10 gene product and raised specific antiserum to the protein. while the virb10 reading frame contains two potential atg translation start sites located 32 codons apart, we found that only the downstream atg was required for efficient virb10 synthesis. cellular localization studies and analysis of translational fusions with the escherichia ... | 1990 | 2394684 |
| promoters of the rola, b, and c genes of agrobacterium rhizogenesare differentially regulated in transgenic plants. | chimeric genes containing the beta-glucuronidase reporter gene under the control of the rola, b, and c promoters of agrobacterium rhizogenes are expressed in a regulated manner in transgenic plants. the intergenic region separating the rolb and c genes represents a bidirectional promoter. this bidirectional promoter regulates transcription for both genes in a similar fashion in aerial organs of the plants, but in a distinct way in roots. moreover, both rolb and c promoter activities differ from ... | 1989 | 2535517 |
| multiple domains exist within the upstream activator sequence of the octopine synthase gene. | it is known that a 16-base pair palindrome (acgtaagcgcttacgt) located upstream of the ocs gene can activate a maize adh1 promoter in a transient expression system [ellis et al. (1987). embo j. 6, 11-16; ellis et al. (1987). embo j. 6, 3203-3208]. we have determined that this palindrome is also essential for ocs promoter activity in tobacco calli. in addition, sequences immediately adjacent to this palindrome, both 5' and 3', modulate its activity. the palindrome is sensitive to the differentiate ... | 1989 | 2535532 |
| the vira protein of agrobacterium tumefaciens is autophosphorylated and is essential for vir gene regulation. | the vira and virg gene products are required for the regulation of the vir regulon on the tumor-inducing (ti) plasmid of agrobacterium tumefaciens. vira is a membrane-associated protein which is homologous to the sensor molecules of other two-component regulatory systems. we overproduced truncated vira proteins in escherichia coli by deleting different lengths of the 5'-coding region of the vira gene and placing these genes under lacz control. these proteins were purified from polyacrylamide gel ... | 1990 | 2404940 |
| the regulatory virg protein specifically binds to a cis-acting regulatory sequence involved in transcriptional activation of agrobacterium tumefaciens virulence genes. | virulence genes of agrobacterium tumefaciens are induced in parallel in the presence of plant phenolic compounds such as acetosyringone and the two regulatory vir genes vira and virg. in this study we identified a cis-acting regulatory sequence in the 5'-noncoding region of the vire operon that is essential for this activation. to do this, we constructed a series of deletion mutants by using exonuclease bal 31. western blot (immunoblot) analysis showed that the 70 base pairs upstream of the tran ... | 1990 | 2404941 |
| nucleotide sequence, secondary structure and evolution of the 5s ribosomal rna from five bacterial species. | the nucleotide sequences of the 5s ribosomal rnas of the bacteria agrobacterium tumefaciens, alcaligenes faecalis, pseudomonas cepacia, aquaspirillum serpens and acinetobacter calcoaceticus have been determined. the sequences fit in a generally accepted model for 5s rna secondary structure. however, a closer comparative examination of these and other bacterial 5s rna primary structures reveals the potential of additional base pairing and of multiple equilibria between a set of slightly different ... | 1985 | 2408888 |
| natural relationship between bacteroides and flavobacteria. | comparisons among 16s rrna sequences from various eubacteria reveal a natural relationship between the bacteroides (represented by the bacteroides fragilis sequence) and a phylogenetic unit that comprises the flavobacteria, cytophagae, flexibacteria, and others (represented by the flavobacterium heparinum sequence). although the relationship is not a close one, it is, nevertheless, specific. rrnas from these two organisms are not only closer to one another in overall sequence than they are to ou ... | 1985 | 2413007 |
| expression of a potyvirus non-structural protein in transgenic tobacco. | a cdna fragment encoding the cytoplasmic inclusion protein of tobacco vein mottling virus was inserted into the plant expression cassette of a ti plasmid-based binary vector. the vector was transferred to agrobacterium tumifaciens, and following a modified leaf disc procedure, transformed tobacco plants were obtained. analysis of poly(a)+ rna from transgenic plants revealed a novel rna of approximately 2100 nucleotides possessing tobacco vein mottling virus sequences. also, immunoprecipitation o ... | 1989 | 2541699 |
| identification of insertion sequence element is427 in ptit37 plasmid dna of an agrobacterium tumefaciens t37 isolate. | the isolation and characterization of an insertion sequence (is) element, is427, from agrobacterium tumefaciens t37 is described. is427 is present in three nonidentical copies on the ptit37 plasmid. the copy that was isolated through transposition on the entrapment vector pucd800 contains at its ends a 16-bp imperfect inverted repeat and generates a 2-bp duplication of the target dna. is427 does not show homology with previously characterized is elements of a. tumefaciens, based on hybridization ... | 1989 | 2544912 |
| urinary tract infection probably caused by agrobacterium radiobacter. | | 1985 | 2419130 |
| structure and expression of ri t-dna from agrobacterium rhizogenes in nicotiana tabacum. organ and phenotypic specificity. | the incorporation of transferred dna (t-dna) from the ri plasmid of agrobacterium rhizogenes into the chromosomal dna of higher plants is correlated with the appearance of a complex phenotype. the transformed genotype and phenotype undergo mendelian inheritance. through studies of ri t-dna content and transcription in nicotiana tabacum, we have delineated a particular part of this foreign dna as the likely source of the transformed phenotype. one inducible/repressible aspect of the transformed p ... | 1985 | 2419571 |
| mutational analysis of the virion-sense genes of maize streak virus. | insertion and deletion mutagenesis of the two virion-sense genes, v1 and v2, of maize streak virus (msv) prevents symptomatic infections following agrobacterium-mediated 'agroinoculation' of maize seedlings. these genes code for an mr 10900 protein and for coat protein, respectively. mutants containing insertions or deletions in the coat protein gene, v2, were able to replicate to low levels, producing dsdna although virion ssdna was not detected and symptoms were not observed. hence, unlike the ... | 1989 | 2550570 |
| genetic analysis of agrocin 84 production and immunity in agrobacterium spp. | mutations affecting agrocin production on the 48-kilobase (kb) plasmid, pagk84, can be complemented in trans with cloned portions of the plasmid. five complementation groups ranging in minimum size from 1.2 to 5.6 kb were identified within a 14-kb segment. plasmid pagk84-encoded immunity to agrocin 84 was located to two separate regions of the plasmid. either region alone was sufficient to protect sensitive strains, and both loci mapped to the agrocin 84 biosynthesis region. one region is locate ... | 1987 | 2442139 |
| expression of an agrobacterium ti plasmid gene involved in cytokinin biosynthesis is regulated by virulence loci and induced by plant phenolic compounds. | the nopaline-type ti plasmid t37 of agrobacterium tumefaciens carries two distinct genes that encode enzymes involved in cytokinin biosynthesis. in this report, we show that the level of expression of one of these genes was increased dramatically by culture conditions that increased the expression of ti plasmid virulence genes, including coculture with plant cells or treatment with acetosyringone, a plant phenolic compound. when this nopaline-type ti plasmid gene was introduced into agrobacteriu ... | 1988 | 2448293 |
| cyclic diguanylic acid and cellulose synthesis in agrobacterium tumefaciens. | the occurrence of the novel regulatory nucleotide bis(3',5')-cyclic diguanylic acid (c-di-gmp) and its relation to cellulose biogenesis in the plant pathogen agrobacterium tumefaciens was studied. c-di-gmp was detected in acid extracts of 32p-labeled cells grown in various media, and an enzyme responsible for its formation from gtp was found to be present in cell-free preparations. cellulose synthesis in vivo was quantitatively assessed with [14c]glucose as a tracer. the organism produced cellul ... | 1989 | 2556370 |
| covalently bound vird2 protein of agrobacterium tumefaciens protects the t-dna from exonucleolytic degradation. | we show that upon induction of agrobacterium tumefaciens, free linear double-stranded t-dna molecules as well as the previously described t-strands are generated from the ti plasmid. a majority of these molecules are bound to a protein. we show that this protein is the product of the virulence gene vird2. this protein was found to be attached to the 5' terminus of processed t-dna at the right border and to the rest of the ti plasmid at the left border. the protein remnant after pronase digestion ... | 1989 | 2556703 |
| a comparative study of tam3 and ac transposition in transgenic tobacco and petunia plants. | transposition of the anthirrinum majus tam3 element and the zea mays ac element has been monitored in petunia and tobacco plants. plant vectors were constructed with the transposable elements cloned into the leader sequence of a marker gene. agrobacterium tumefaciens-mediated leaf disc transformation was used to introduce the transposable element constructs into plant cells. in transgenic plants, excision of the transposable element restores gene expression and results in a clearly distinguishab ... | 1989 | 2562396 |
| transposable elements can be used to study cell lineages in transgenic plants. | the beta-glucuronidase reporter gene has been used to develop a sensitive assay for the excision of transposable elements introduced into transgenic plants. the reporter gene, inactivated by the insertion of the maize transposable element activator (ac) into the 5'-untranslated leader, was introduced into the genome of tobacco by agrobacterium-mediated transformation. reactivation of the beta-glucuronidase gene was detected in transgenic plants using a fluorometric or histochemical assay. reacti ... | 1989 | 2562511 |
| cell-autonomous behavior of the rolc gene of agrobacterium rhizogenes during leaf development: a visual assay for transposon excision in transgenic plants. | we describe a genetic switch based on the ac transposable element of maize and the rolc gene of agrobacterium rhizogenes, a dominant gene, which has pleiotropic effects on plant growth and morphology. moreover, rolc gene expression under the control of the 35s cauliflower mosaic virus promoter decreases chlorophyll content in transgenic tobacco plants. chlorophyll is a visible cell-autonomous marker, and it is shown here that the reduction in chlorophyll content caused by the rolc gene product a ... | 1989 | 2562512 |
| extensive changes in dna methylation patterns accompany activation of a silent t-dna ipt gene in agrobacterium tumefaciens-transformed plant cells. | we crossed a male-sterile, agrobacterium-transformed nicotiana tabacum plant that contains a silent, hypermethylated t-dna ipt oncogene with a normal tobacco plant and found that the methylated state of the ipt gene was stably inherited through meiosis in the offspring. however, when tissues of these plants were placed in cell culture, the ipt gene was spontaneously reactivated in a very small fraction of the cells; if 5-azacytidine was added to the culture medium, ipt gene reactivation occurred ... | 1989 | 2479825 |
| phleomycin resistance as a dominant selectable marker for plant cell transformation. | tobacco cells are sensitive to bleomycin and phleomycin. the tn5 and the streptoalloteichus hindustanus (sh) bleomycin resistance ('ble') genes conferring resistance to these antibiotics have each been inserted into two plant expression vectors. they are flanked by the nopaline synthase (nos) or the cauliflower mosaic virus (camv) 35s promoters on one side, and by the nos polyadenylation signal on the other. these four chimaeric genes were introduced into the binary transformation vector pga 492 ... | 1989 | 2485087 |
| the nucleotide sequence of ribosomal 5s rna from rhizobium meliloti: comparison with 5s rrna of agrobacterium. | the complete nucleotide sequence of r. meliloti 5s ribosomal rna has been determined and compared with the already known sequence of a. tumefaciens 5s rrna (vandenberghe et al., 1985, eur. j. biochem., 149, 537-542) and of other 5s rrnas from rodobacteria alpha-2 (wolters et al., 1988, nucleic acids res., 16, rl-r70). the differences found at eight positions (23, 73, 83, 72 in helical fragments; 16, 40, 88 in loops; 54 in bulge), which might affect secondary structures of 5s rrna, are small. mor ... | 1989 | 2486005 |
| direct dna transfer to plant cells. | a range of somatic cell and molecular techniques are now available to supplement conventional plant breeding. the introduction and expression of foreign dna has been used to modify basic aspects of physiology and development, to introduce commercially important characteristics such as herbicide and insect resistance into plants and to insert genes suitable as dominant selectable markers for somatic hybridisation. several techniques for direct dna delivery are available, ranging from uptake of dn ... | 1989 | 2491654 |
| use of roots transformed by agrobacterium rhizogenes in rhizosphere research: applications in studies of cadmium assimilation from sewage sludges. | the use of roots transformed by agrobacterium rhizogenes in models for the rhizosphere is discussed. a list of species for which transformed root cultures have been obtained is provided and the example of studies of cadmium assimilation from sewage sludges is given to illustrate how transformed root cultures can be used in physiological tests under non-sterile conditions. | 1989 | 2491656 |
| binding-protein-dependent sugar transport by agrobacterium radiobacter and a. tumefaciens grown in continuous culture. | binding-protein-dependent sugar transport has been investigated in agrobacterium radiobacter and a. tumefaciens. a. radiobacter contained two high-affinity glucose-binding proteins (gbp1 and gbp2) that additionally bound d-galactose (kd 0.26 microm) and d-xylose (kd 0.04 microm) respectively and were involved in the transport of these sugars. partial sequencing of gbp1 and gbp2 showed that gbp2 exhibited significant homology with both the arabinose-binding protein (abp) and the galactose-binding ... | 1989 | 2614377 |
| a translational enhancer derived from tobacco mosaic virus is functionally equivalent to a shine-dalgarno sequence. | when present at the 5' end of mrnas, the untranslated leader sequence (omega) of tobacco mosaic virus rna significantly enhances translation in eukaryotes and prokaryotes. we have tested a deletion derivative of the omega sequence, omega delta 3, for its enhancing ability on gene constructs in which the ribosomal binding site was either present or deleted, in several gram-negative bacterial species including escherichia coli, agrobacterium tumefaciens, xanthomonas campestris pv. vitians, erwinia ... | 1989 | 2643095 |
| mutational analysis of the conserved domains of a t-region border repeat of agrobacterium tumefaciens. | left- and right-border repeats, which surround the t-region, contain two conserved regions separated by 5 bp that are not conserved. at the onset of t-dna processing vird-encoded proteins introduce a nick in the largest of these conserved regions (12 bp) at a specific position in the bottom strand between a guanine and thymine nucleotide [2, 33]. in this paper we describe the effect of several site-directed mutations in the right-border repeat on tumorigenicity of agrobacterium in plants. our da ... | 1989 | 2491670 |
| expression of a bacterial gene in transgenic tobacco plants confers resistance to the herbicide 2,4-dichlorophenoxyacetic acid. | plants resistant to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-d) were produced through the genetic engineering of a novel detoxification pathway into the cells of a species normally sensitive to 2,4-d. we cloned the gene for 2,4-d monooxygenase, the first enzyme in the plasmid-encoded 2,4-d degradative pathway of the bacterium alcaligenes eutrophus, into a cauliflower mosaic virus 35s promoter expression vector and introduced it into tobacco plants by agrobacterium-mediated transformatio ... | 1989 | 2491671 |
| nucleotide sequence and genetic organization of the bacillus subtilis comg operon. | a series of tn917lac insertions define the comg region of the bacillus subtilis chromosome. comg mutants are deficient in competence and specifically in the binding of exogenous dna. the genes included in the comg region are first expressed during the transition from the exponential to the stationary growth phase. from nucleotide sequence information, it was concluded that the comg locus contains seven open reading frames (orfs), several of which overlap at their termini. high-resolution s1 nucl ... | 1989 | 2507524 |
| chva locus may be involved in export of neutral cyclic beta-1,2-linked d-glucan from agrobacterium tumefaciens. | extracellular and intracellular neutral beta-1,2-linked d-glucan content was determined in a virulent, attachment-deficient mutants of agrobacterium tumefaciens that map in the chva locus. chva mutants contained approximately the same amount of intracellular glucan as cells of the virulent control strain a759, but released into the culture medium only 2% of the glucan released by strain a759. introduction of a cosmid carrying the wild-type chv region restored attachment and virulence and restore ... | 1989 | 2520158 |
| expression of agrobacterium nopaline-specific vird1, vird2, and virc1 proteins and their requirement for t-strand production in e. coli. | induction of ti plasmid virulence (vir) genes during early stages of the genetic transformation of plant cells by agrobacterium tumefaciens results in several molecular events that are involved in generating a transferable t-dna copy. these events include site-specific nicking at the t-dna borders and synthesis of free, unipolar, linear, single-stranded copies of the t-dna (t-strands). here e. coli was used as a heterologous cell to assay the requirements for t-strand synthesis. cells of e. coli ... | 1989 | 2520160 |
| the relationship between nodulin gene expression and the rhizobium nod genes in vicia sativa root nodule development. | the role of the rhizobium nod genes in the induction of nodulin gene expression was examined by analyzing nodules formed on vetch roots by bacterial strains containing only the nod region. introduction of an 11-kb cloned nod region of the r. leguminosarum sym plasmid prl1ji into sym plasmid-cured rhizobia conferred on the recipient strains the ability to induce nodules in which all nodulin genes were expressed. this proves that from the sym plasmid only the nod region is involved in the inductio ... | 1989 | 2520161 |
| plant viruses: a tool-box for genetic engineering and crop protection. | traditionally, plant viruses are viewed as harmful, undesirable pathogens. however, their genomes can provide several useful 'designer functions' or 'sequence modules' with which to tailor future gene vectors for plant or general biotechnology. the majority (77%) of known plant viruses have single-stranded rna of the messenger (protein coding) sense as their genetic material. over the past 4 years, improved in vitro transcription systems and the construction of partial or full-length dna copies ... | 1989 | 2662963 |
| identification, cloning, and sequence analysis of the nitrogen regulation gene ntrc of agrobacterium tumefaciens c58. | we describe the cloning of an ntrc gene of agrobacterium tumefaciens c58 by interspecific complementation of an escherichia coli ntrc mutant. restriction mapping and southern blot analysis of the complementing clone identified a 1.7-kb ecori-pvuii dna fragment whose sequence was determined. analysis of this sequence revealed coding regions corresponding to a complete ntrc gene and the c-terminal region of an ntrb gene. amino acid sequence comparisons of a. tumefaciens ntrc protein with ntrc sequ ... | 1989 | 2520824 |
| putative start codon ttg for the regulatory protein virg of the hairy-root-inducing plasmid pria4. | the nucleotide sequence of the virg gene for a transcriptional activator on the agropine-type hairy-root-inducing plasmid pria4 was determined. the sequence contained one possible open reading frame. the gene product with a molecular size of 26.5 kda was identified by an escherichia coli coupled-transcription-translation system using cloned virg plasmids as templates. however, neither an atg nor a gtg start codon which could give rise to such a protein was identified in the nucleotide sequence. ... | 1989 | 2670679 |
| efficient transformation of agrobacterium spp. by electroporation. | | 1989 | 2674902 |
| a gene required for transfer of t-dna to plants encodes an atpase with autophosphorylating activity. | the virb operon of the agrobacterium tume-faciens ptia6nc plasmid likely plays a role in directing t-dna transfer events at the bacterial membrane, as determined previously by mutagenesis and cellular fractionation studies and by dna sequence analysis of the approximately 12-kilobase-pair operon. the dna sequence analysis also revealed consensus mononucleotide binding domains in the deduced virb5 and virb11 gene products, suggesting that one or both of these proteins couple energy, by means of n ... | 1989 | 2532360 |
| firefly luciferase as a reporter enzyme for measuring gene expression in vegetative and symbiotic rhizobium meliloti and other gram-negative bacteria. | a dna segment carrying a cdna copy of the luciferase gene (luc) of the north american firefly photinus pyralis, fused to the lambda pr promoter and expressed in escherichia coli [de wet et al., proc. natl. acad. sci. usa 82 (1985) 7870-7873], was inserted into a broad-host-range plasmid vector and established in a variety of gram-negative bacteria. luciferase activity, expressed from the lambda pr promoter, was detected in both intact cells and extracts prepared from cells of strains of rhizobiu ... | 1989 | 2680767 |
| functional analysis of dna sequences responsible for ethylene regulation of a bean chitinase gene in transgenic tobacco. | expression of at least two genes from bean encoding the defense-related protein chitinase has been shown previously to be transcriptionally regulated by the phytohormone ethylene. we have determined the complete nucleotide sequence of one of these genes, the ch5b gene, which resides on a 4.7-kilobase fragment of bean genomic dna. the structural gene consists of a single open reading frame and encodes the 301 amino acids of the mature protein and a 26-amino acid signal peptide. the ch5b gene has ... | 1989 | 2535512 |
| efficient transformation of agrobacterium spp. by high voltage electroporation. | | 1989 | 2682529 |
| nucleotide sequence of the tzs gene from agrobacterium rhizogenes strain a4. | | 1989 | 2685753 |
| a family of genes encoding a cell-killing function may be conserved in all gram-negative bacteria. | the relf gene in escherichia coli is related to the hok gene on plasmid r1. both genes encode small proteins which, when overexpressed in e. coli lead to collapse of the membrane potential and cell death. a third gene, designated gef, which encodes a homologous cell-toxic protein, has been isolated from e. coli dna. both gef and relf are transcribed in e. coli and subject to post-transcriptional regulation which, in the case of gef, is coupled to translation of a leader sequence. the finding of ... | 1989 | 2693900 |
| level of expression of the tomato rbcs-3a gene is modulated by a far upstream promoter element in a developmentally regulated manner. | by agrobacterium-mediated transformation we have demonstrated that a 1.10-kilobase promoter sequence from the tomato rbcs-3a gene confers light-inducible and organ-specific expression upon fusion to the bacterial chloramphenicol acetyltransferase gene. a biphasic expression profile was obtained by 5' deletion analysis of this promoter, indicating the presence of both positive and negative regulatory elements. a severe reduction in the level of expression was observed when the 5'-terminal 90 base ... | 1989 | 2535544 |
| cloning and analysis of genes involved in coenzyme b12 biosynthesis in pseudomonas denitrificans. | cobalamin synthesis probably requires 20 to 30 different enzymatic steps. pseudomonas putida and agrobacterium tumefaciens mutants deficient in cobalamin synthesis (cob have been isolated. in p. putida, cob mutants were identified as being unable to use ethanolamine as a source of nitrogen in the absence of added cobalamin (deamination of ethanolamine requires coenzyme b12 as a cofactor). in a. tumefaciens, cob mutants were simply screened for their reduced cobalamin synthesis. a genomic library ... | 1989 | 2536665 |
| cooperative binding of agrobacterium tumefaciens vire2 protein to single-stranded dna. | the vire2 protein of agrobacterium tumefaciens ti plasmid ptia6 is a single-stranded-dna-binding protein. density gradient centrifugation studies showed that it exists as a tetramer in solution. monomeric vire2 active in dna binding could also be obtained by using a different protein isolation procedure. vire2 was found to be thermolabile; brief incubation at 37 degrees c abolished its dna-binding activity. it was insensitive to the sulfhydryl-specific reagent n-ethylmaleimide. removal of the ca ... | 1989 | 2708313 |
| biochemical characterization of avirulent agrobacterium tumefaciens chva mutants: synthesis and excretion of beta-(1-2)glucan. | the chva gene product of agrobacterium tumefaciens is required for virulence and attachment of bacteria to plant cells. three chva mutants were studied. in vivo, they were defective in the synthesis, accumulation, and secretion of beta-(1-2)glucan; however, the 235-kilodalton (kda) protein known to be involved in the synthesis of beta-(1-2)glucan (a. zorreguieta and r. ugalde, j. bacteriol. 167:947-951, 1986) was present and active in vitro. was present and active in vitro. two molecular forms o ... | 1989 | 2708321 |
| sequences responsible for the tissue specific promoter activity of a pea legumin gene in tobacco. | maturing pea cotyledons accumulate large quantities of storage proteins at a specific time in seed development. to examine the sequences responsible for this regulated expression, a series of deletion mutants of the lega major seed storage protein gene were made and transferred to tobacco using the bin19 disarmed agrobacterium vector system. a promoter sequence of 97 bp including the caat and tata boxes was insufficient for expression. expression was first detected in a construct with 549 bp of ... | 1989 | 2710102 |
| sequence determination and characterization of the replicator region in the tumor-inducing plasmid ptib6s3. | the replicator region of the 195-kilobase-pair (kb) tumor-inducing plasmid ptib6s3 was previously identified by isolation of a 6.8-kb miniplasmid (b.p. koekman, p.j.j. hooykaas, and r.a. schilperoort, plasmid 7:119-132, 1982). this miniplasmid was joined to cole1-based vectors and subjected to mutagenesis. the resulting mutant plasmids were examined for their ability to replicate autonomously in agrobacterium tumefaciens. it was found that a 4.2-kb region was sufficient for displaying replicatio ... | 1989 | 2537824 |
| recovery of agrobacterium tumefaciens t-dna molecules from whole plants early after transfer. | a system for the analysis of independent t-dna transfer events from agrobacterium to plants is described. the complete t-dna except for the 25 bp border sequences was replaced by one genome of a plant virus so that upon transfer to the plant, a viable replicon is produced by circularization. rescue of virus from such infected plants allowed analysis of dna sequences at or close to the ends of t-dna molecules. a rather conserved right border remnant of three nucleotides was found, whereas the seq ... | 1989 | 2720788 |
| saturation mutagenesis of the octopine synthase enhancer: correlation of mutant phenotypes with binding of a nuclear protein factor. | a 16-base-pair palindrome from the agrobacterium tumefaciens octopine synthase gene functions as a constitutive enhancer in plant protoplasts. degenerate oligonucleotide mutagenesis provided single base substitutions at every position in the element and a number of multiple base substitutions. the effects of these changes were determined in transient expression assays with tobacco and maize protoplasts. the majority of single and double base changes had little effect on the activity of the octop ... | 1989 | 2726750 |
| the vird operon of agrobacterium tumefaciens ti plasmid encodes a dna-relaxing enzyme. | the vird locus of agrobacterium tumefaciens ti plasmid encodes functions necessary for endonucleolytic cleavage of transferred dna (t-dna) prior to its transfer to plant cells. for the overproduction of the vird proteins in escherichia coli a tac-vird operon fusion was constructed. a significant increase in the accumulation of vird proteins was observed in a lon protease-deficient e. coli host. the presence of an overlapping open reading frame (orf) upstream of the vird1 coding sequence had a ne ... | 1989 | 2541431 |