| rhizobium meliloti nodd genes mediate host-specific activation of nodabc. | to differentiate among the roles of the three nodd genes of rhizobium meliloti 1021, we studied the activation of a nodc-lacz fusion by each of the three nodd genes in response to root exudates from several r. meliloti host plants and in response to the flavone luteolin. we found (i) that the nodd1 and nodd2 products (nodd1 and nodd2) responded differently to root exudates from a variety of hosts, (ii) that nodd1 but not nodd2 responded to luteolin, (iii) that nodd2 functioned synergistically wi ... | 1990 | 2298703 |
| the rhizobium nodulation gene nodo encodes a ca2(+)-binding protein that is exported without n-terminal cleavage and is homologous to haemolysin and related proteins. | nodulation and host-specific recognition of legumes such as peas and vicia spp. are encoded by the nodulation (nod) genes of rhizobium leguminosarum biovar viciae. one of these genes, nodo, has been shown to encode an exported protein that contains a multiple tandem repeat of a nine amino acid domain. this domain was found to be homologous to repeated sequences in a group of bacterial exported proteins that includes haemolysin, cyclolysin, leukotoxin and two proteases. these proteins are secrete ... | 1990 | 2303029 |
| virg, an agrobacterium tumefaciens transcriptional activator, initiates translation at a uug codon and is a sequence-specific dna-binding protein. | the agrobacterium tumefaciens ti plasmid virg locus, in conjunction with vira and acetosyringone, activates transcription of the virulence (vir) genes. insertional and deoxyoligonucleotide-directed mutagenesis studies showed that both octopine and nopaline ti plasmid virg genes initiate translation at a uug codon. virg protein initiated at this uug codon was found to be 241 amino acid residues in length and had an apparent molecular mass of 27.1 kilodaltons. a salmonella typhimurium trp-virg tra ... | 1990 | 2307647 |
| symbiotic pseudorevertants of rhizobium meliloti ndv mutants. | nodule development (ndv) mutants of rhizobium meliloti cannot invade alfalfa to establish a nitrogen-fixing symbiosis and instead induce the formation of small, white, unoccupied nodules on alfalfa roots. such mutants also fail to produce the unusual cyclic oligosaccharide beta-(1----2)-glucan and show defects in several aspects of vegetative growth and function. here we show that ndv mutants are severely reduced, although not totally deficient, in the ability to attach to and initiate infection ... | 1990 | 2307652 |
| 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 |
| immunochemical analysis of lipopolysaccharides from free-living and endosymbiotic forms of rhizobium leguminosarum. | rhizobium leguminosarum b556 and 8002 differ only with respect to carrying symbiotic plasmids with specificity for pisum or phaseolus hosts, respectively. protease-treated samples derived from free-living cultures of both strains revealed a ladder of lipopolysaccharide (lps-1) bands after periodate-silver staining of sodium dodecyl sulfate-polyacrylamide gels. these bands were arranged as doublets. after western (immuno-) blotting, all lps-1 bands reacted with monoclonal antibody jim 21, whereas ... | 1990 | 2318803 |
| 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 |
| 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 |
| 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 |
| 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 |
| symbiotic host-specificity of rhizobium meliloti is determined by a sulphated and acylated glucosamine oligosaccharide signal. | rhizobia are symbiotic bacteria that elicit the formation on leguminous plants of specialized organs, root nodules, in which they fix nitrogen. in various rhizobium species, such as r. leguminosarum and r. meliloti, common and host-specific nodulation (nod) genes have been identified which determine infection and nodulation of specific hosts. common nodabc genes as well as host-specific nodh and nodq genes were shown recently, using bioassays, to be involved in the production of extracellular no ... | 1990 | 2330031 |
| 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 |
| effects of alfalfa nod gene-inducing flavonoids on nodabc transcription in rhizobium meliloti strains containing different nodd genes. | transcription of the nodulation genes nodabc in rhizobium meliloti requires a plant flavonoid signal and nodd, a family of bacterial regulatory genes (nodd1, nodd2, and nodd3). results from this study show that all previously identified nod gene inducers released by alfalfa seeds and roots induced nodabc-lacz transcription in r. meliloti containing extra copies of nodd1, but only 4,4'-dihydroxy-2'-methoxychalcone gave high levels of induction with extra copies of nodd2. while mixtures of the met ... | 1990 | 2332406 |
| molecular characterization of the nodulation gene, nodt, from two biovars of rhizobium leguminosarum. | dna sequencing of the nodij region from rhizobium leguminosarum biovar trifolii revealed the nodt gene immediately downstream of nodj. dna hybridizations using a nodt-specific probe showed that nodt is present in several r. leguminosarum strains. interestingly, a flavonoid-inducible nodt gene homologue in r. leguminosarum bv. viciae is not in the nodabcij operon but is located downstream of nodmn. the sequence of the nodt gene from bv. viciae was determined and a comparison of the predicted amin ... | 1990 | 2338917 |
| 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 |
| nodule formation in soybeans by exopolysaccharide mutants of rhizobium fredii usda 191. | production of exopolysaccharides by rhizobium has been linked with efficient invasion and nodulation of leguminous plant roots by the bacteria. exopolysaccharide-deficient (exo) mutants of rhizobium fredii usda 191 were isolated following tn5-insertion mutagenesis. five phenotypically unique exo mutants were investigated for exopolysaccharide synthesis and their ability to nodulate soybeans. the exopolysaccharides produced by these mutants were analysed for polysaccharide composition by column c ... | 1990 | 2351951 |
| uptake of glycine betaine and its analogues by bacteroids of rhizobium meliloti. | bacteroids isolated from alfalfa nodules induced by rhizobium meliloti 102f34 transported glycine betaine at a constant rate for up to 30 min. addition of sodium salts greatly increased the uptake activity, whereas other salts or non-electrolytes had less effect. the apparent km for glycine betaine uptake was 8.3 microm and v was about 0.84 nmol min-1 (mg protein)-1 in the presence of 200 mm-nacl which gave maximum stimulation of the transport. supplementing bacteroid suspensions with various en ... | 1990 | 2351954 |
| a model of nitrogen flow by malonamate in rhizobium japonicum-soybean symbiosis. | two types of novel malonamidases were found in soybean nodules. one (e1) catalyzes the formation of malonamate from malonate and its hydrolysis to ammonia, whereas the other (e2) acts mainly on the hydrolysis of malonamate. e1 and e2 were found in bacteroids, but only e2 was found in the plant cytosol of the nodule. the substrate requirements of e1 and e2 were highly specific for malonate and malonamate, respectively. from these and other results reported previously, we propose that malonamate p ... | 1990 | 2357226 |
| dna sequence and translational product of a new nodulation-regulatory locus: syrm has sequence similarity to nodd proteins. | rhizobium meliloti nodulation (nod) genes are expressed when activated by trans-acting proteins in the nodd family. the nodd1 and nodd2 gene products activate nod promoters when cells are exposed to plant-synthesized signal molecules. alternatively, the same nod promoters are activated by the nodd3 gene when nodd3 is carried in trans along with a closely linked global regulatory locus, syrm (symbiotic regulator) (j. t. mulligan and s. r. long, genetics 122:7-18, 1989). in this article we report ... | 1990 | 2361944 |
| 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 |
| correlation between ultrastructural differentiation of bacteroids and nitrogen fixation in alfalfa nodules. | bacteroid differentiation was examined in developing and mature alfalfa nodules elicited by wild-type or fix- mutant strains of rhizobium meliloti. ultrastructural studies of wild-type nodules distinguished five steps in bacteroid differentiation (types 1 to 5), each being restricted to a well-defined histological region of the nodule. correlative studies between nodule development, bacteroid differentiation, and acetylene reduction showed that nitrogenase activity was always associated with the ... | 1990 | 2376562 |
| 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 |
| structural studies of a novel exopolysaccharide produced by a mutant of rhizobium meliloti strain rm1021. | the structure of a novel expolysaccharide obtained from a mutant of rhizobium meliloti strain rm1021 was elucidated by a combination of enzymic, chemical, and spectroscopic methods. the polysaccharide is composed of a disaccharide repeating-unit, beta-d-glcp-(1----3)-alpha-d-galp-(1----3), having a 6-o-acetyl group attached to most d-glucose residues and a 4,6-o-(1-carboxyethylidene) group attached to every d-galactose residue. | 1990 | 2379191 |
| dicarboxylic acid transport and regulation of nitrogen fixation in rhizobium meliloti. | | 1990 | 2379758 |
| 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 |
| defective viral dna ameliorates symptoms of geminivirus infection in transgenic plants. | nicotiana benthamiana was transformed with a single copy of a tandem repeat of subgenomic dna b isolated from plants infected with a kenyan isolate of the bipartite geminivirus african cassava mosaic virus. symptoms in transformed plants were less severe than in nontransformed controls when challenged with virus or cloned dna of kenyan or nigerian isolates. symptom amelioration was associated with the mobilization and amplification of the subgenomic dna, producing a comparable reduction in the a ... | 1990 | 2385593 |
| 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 |
| a biovar-specific signal of rhizobium leguminosarum bv. viciae induces increased nodulation gene-inducing activity in root exudate of vicia sativa subsp. nigra. | flavonoids in root exudate of leguminous plants activate the transcription of rhizobium genes involved in the formation of root nodules (nod genes). we report that inoculation with the homologous symbiont r. leguminosarum bv. viciae results in an increased nod gene-inducing activity (ini) in root exudate of v. sativa subsp. nigra, whereas inoculation with heterologous rhizobium strains results in exudates with nod gene-inducing activity comparable to that of uninfected plants. ini can be demonst ... | 1990 | 2394688 |
| dna sequence encoding the two structural genes for the uptake hydrogenase of rhizobium leguminosarum bv. viciae b10. | | 1990 | 2402452 |
| 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 |
| a rhizobium leguminosarum mutant defective in symbiotic iron acquisition. | iron acquisition by symbiotic rhizobium spp. is essential for nitrogen fixation in the legume root nodule symbiosis. rhizobium leguminosarum 116, an ineffective mutant strain with a defect in iron acquisition, was isolated after nitrosoguanidine mutagenesis of the effective strain 1062. the pop-1 mutation in strain 116 imparted to it a complex phenotype, characteristic of iron deficiency: the accumulation of porphyrins (precursors of hemes) so that colonies emitted a characteristic pinkish-red f ... | 1990 | 2404949 |
| use of saturation mutagenesis to localize probable functional domains in the nahr protein, a lysr-type transcription activator. | the nahr protein of the pseudomonas naphthalene degradation plasmid nah7 encodes a 300-residue transcription activator which is very similar to the nodd transcription activator of rhizobium and other proteins in the lysr activator family. nahr binds to conserved sequences upstream (nucleotides -80 to -47) of the nah and sal promoters and activates transcription of genes for naphthalene catabolism in response to the inducer salicylate. transformation of an escherichia coli gal deletion strain (co ... | 1990 | 2406264 |
| determination of viability within serotypes of a soil population of rhizobium leguminosarum bv. trifolii. | concern has been raised about the percentage of viable cells within soil rhizobia populations measured by the immunofluorescence direct count method. the purpose of this study was to evaluate a direct viable count technique which is based on the fact that viable bacteria in natural populations undergo cell elongation when they are exposed to a combination of substrate and the inhibitor of dna gyrase, nalidixic acid. a soil extraction procedure was developed to recover a high proportion of soil b ... | 1990 | 2407187 |
| genetic organization of the hydrogen uptake (hup) cluster from rhizobium leguminosarum. | in symbiosis with peas, rhizobium leguminosarum upm791 induces the synthesis of a hydrogen uptake (hup) system that recycles hydrogen generated in nodules by nitrogenase. a cosmid (pal618) containing hup genes from this strain on a 20-kilobase-pair (kb) dna insert has previously been isolated in our laboratory (a. leyva, j. m. palacios, t. mozo, and t.ruiz-argüeso, j. bacteriol. 169:4929-4934, 1987). here we show that cosmid pal618 contains all of the genetic information required to confer high ... | 1990 | 2407728 |
| binary vectors which allow the exchange of plant selectable markers and reporter genes. | | 1990 | 2408008 |
| use of intrinsic antibiotic resistance for characterisation and identification of rhizobia from nodules of vigna unguiculata (l) walp. and phaseolus vulgaris (l). | intrinsic resistance to low concentrations of antibiotics was used to characterise 83 isolates from nodules of cowpea (vigna unguiculata) and field bean (phaseolus vulgaris). characterisation and differentiation of isolates from cowpea was made difficult by associated fast-growing bacteria inside the nodule tissue. thus, reliable pure culture was difficult to secure without repeated isolation and even via nodulation of the appropriate homologous host. although the technique may be satisfactory f ... | 1985 | 2412407 |
| 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 |
| transcription patterns of rhizobium meliloti symbiotic plasmid psym: identification of nifa-independent fix genes. | we performed a systematic survey of transcription of a large region of the rhizobium meliloti symbiotic plasmid psym. this led to the discovery of two new sequences induced during symbiosis. the first sequence was linked to the known nitrogen fixation (nif-fix) gene cluster, and its expression depended on the nifa gene product. the second sequence was a novel fix locus (m.-h. renalier, j. batut, j. ghai, b. terzaghi, m. gherardi, m. david, a.-m. garnerone, j. vasse, g. truchet, t. huguet, and p. ... | 1987 | 2437100 |
| the nifa gene of rhizobium meliloti is oxygen regulated. | experiments using plasmid-borne gene fusions and direct rna measurements have revealed that expression from the nifa gene is induced in rhizobium meliloti when the external oxygen concentration is reduced to microaerobic levels. induction occurs in the absence of alfalfa and in the presence of fixed nitrogen and does not require ntrc. the production of functional nifa gene product (nifa) can be demonstrated by its ability to activate the nitrogenase promoter p1. aerobic induction of nifa can als ... | 1987 | 2439489 |
| use of tannic acid for the ultrastructural visualization of periplasm in gram-negative bacteria. | tannic acid mordanting reveals the periplasm, the area between the outer membrane and the inner membrane of gram-negative bacteria, rhizobium sp., escherichia coli and enterobacter aerogenes, as an electron-dense layer continuous with the inner leaflet of the outer membrane. the method involves 18 hr of tannic acid treatment after fixation in aldehyde prior to osmium tetroxide postfixation, followed by conventional electron microscopy. | 1987 | 2440153 |
| nucleotide sequence of a trna(leu)cag gene from rhizobium meliloti. | the nucleotide sequence of a trna(leu)cag gene from rhizobium meliloti has been determined. its organization includes a short transcript with a promoter-like structure and two rho-independent terminators about 10 bp downstream from the cloverleaf structure. the putative promoter shows good homology with the -45 and -35 region of the consensus (sigma 70) promoter sequence of escherichia coli, but less with the -10 region. a discriminator-like sequence is present between the start of the transcrip ... | 1987 | 2442068 |
| 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 |
| 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 |
| 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 |
| functioning haemoglobin genes in non-nodulating plants. | haemoglobin has previously been recorded in plants only in the nitrogen-fixing nodules formed by symbiotic association between rhizobium or frankia and legume or non-legume hosts. structural similarities amongst these and animal haemoglobins at the protein and gene level suggested a common evolutionary origin. this suggests that haemoglobin genes, inherited from an ancestor common to plants and animals, might be present in all plants. we report here the isolation of a haemoglobin gene from trema ... | 1988 | 2448639 |
| rhizobium fix genes mediate at least two communication steps in symbiotic nodule development. | to identify bacterial genes involved in symbiotic nodule development, ineffective nodules of alfalfa (medicago sativa) induced by 64 different fix-mutants of rhizobium meliloti were characterized by assaying for symbiotic gene expression and by morphological studies. the expression of leghemoglobin and nodulin-25 genes from alfalfa and of the nifhd genes from r. meliloti were monitored by hybridizing the appropriate dna probes to rna samples prepared from nodules. the mutants were accordingly di ... | 1988 | 2450096 |
| nucleotide sequence and genetic analysis of the nifb-nifq region from azotobacter vinelandii. | a 3.8-kilobase-pair ecori fragment which corrects the mutations carried by the nifb- azotobacter vinelandii strains ca30 and uw45 was cloned, and its nucleotide sequence was determined. four complete open reading frames (orfs) and two partial orfs were found. the translation product of the first partial orf is the carboxy-terminal end of a protein homologous to the nifa gene product from klebsiella pneumoniae. a 285-base-pair sequence containing a potential nif promoter and nif regulatory sites ... | 1988 | 2450865 |
| agrobacterium tumefaciens vire operon encodes a single-stranded dna-binding protein. | the virulence (vir) genes of agrobacterium tumefaciens ti plasmid are essential for transformation of plant cells. overproduction of a vire-encoded gene product in escherichia coli was achieved by construction of an operon fusion with the e. coli tryptophan (trp) operon. the vire2 gene product in e. coli partitioned into the insoluble membrane fraction. the protein was solubilized by treatment with 4 m urea at 0 degree c. dna-protein binding experiments showed that a strong single-stranded (ss) ... | 1988 | 2452439 |
| 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 |
| [branching enzyme from rhizobium lupini bacteroids as a nucleoprotein: the role of rna in the complex with protein component and after its removal]. | | 1988 | 2454184 |
| ntr-like promoters and upstream regulatory sequence ftr are required for transcription of a developmentally regulated caulobacter crescentus flagellar gene. | the flbg (hook operon or transcription unit ii) and flan (transcription unit i) operons of caulobacter crescentus have a -12, -24 nucleotide sequence motif that is very similar to those of the nif and ntr promoters of enteric bacteria and rhizobium spp. and a conserved ftr (flagellar gene transcription regulation) sequence, previously designated ii-1 (d. a. mullin, s. a. minnich, l.-s. chen, and a. newton, j. mol. biol. 195:939-943, 1987) at approximately -100. we have used site-directed mutagen ... | 1989 | 2470725 |
| transient transfection of mammalian cells with dna of the plant-pathogenic ti-plasmid and expression of marker and resident sequences. | the large ti-plasmid from agrobacterium tumefaciens strain c58 has been used for transfection experiments with mammalian cells. in dna from tupaia baby fibroblasts ti-plasmid sequences could be identified by filter hybridization as long as four weeks after transfection including two cell passages. the hybridization signals decreased rapidly after addition of the ti-plasmid dna-coprecipitate to the cells. the signals were often not detected any more after the first day, but were visible one week ... | 1989 | 2471056 |
| oxyr, a positive regulator of hydrogen peroxide-inducible genes in escherichia coli and salmonella typhimurium, is homologous to a family of bacterial regulatory proteins. | the oxyr gene is required for the induction of a regulon of hydrogen peroxide-inducible genes in escherichia coli and salmonella typhimurium. the e. coli oxyr gene has been cloned and sequenced, revealing an open reading frame (305 amino acids) that encodes a 34.4-kda protein, which is produced in maxicells carrying the oxyr clone. the oxyr protein shows homology to a family of positive regulatory proteins including lysr in e. coli and nodd in rhizobium. like them, oxyr appears to be negatively ... | 1989 | 2471187 |
| 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 |
| differential regulation of soybean chalcone synthase genes in plant defence, symbiosis and upon environmental stimuli. | four independent recombinant lambda clones hybridizing to parsley chalcone synthase (chs) cdna were isolated from a soybean (glycine max) genomic library. restriction fragment length polymorphism (rflp) analysis indicated that the chs gene family comprises six members. the chs genes were found to be clustered with three genes on a 10 kb segment and pairs on others. dna sequences of the 5'-, the coding-, and the 3' untranslated regions were determined for three different genes. a consensus alignm ... | 1989 | 2476656 |
| protection against tobacco mosaic virus in transgenic plants that express tobacco mosaic virus antisense rna. | transgenic tobacco plants that express rna sequences complementary to the tobacco mosaic virus (tmv) coat protein (cp) coding sequence with or without the trna-like structure at the 3' end of the tmv rna were produced. progeny of self-pollinated plants were challenged with tmv to determine their resistance to infection. plants that expressed rna sequences complementary to the cp coding region and the 3' untranslated region, including the trna-like sequences, were protected from infection by tmv ... | 1989 | 2476807 |
| altered imino diacid synthesis and transcription in crown gall tumors with transposon tn5 insertions in the 3' end of the octopine synthase gene. | octopine synthase encoded by the t-dna (transferred dna) locus ocs synthesizes n2-(d-1-carboxyethyl)-l-amino acids in octopine-type crown gall tumors. so far, derivatives of only basic amino acids have been isolated. we have detected a glutamine derivative and called it heliopine. tumors induced by several ti plasmids with transposon tn5 insertions in the 3' end of ocs still synthesized small quantities of n2-(1-carboxyethyl)-arginine and n2-(1-carboxyethyl)-glutamine. in addition, n2-(1,3-dicar ... | 1989 | 2478521 |
| 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 |
| signal structure for transcriptional activation in the upstream regions of virulence genes on the hairy-root-inducing plasmid a4. | the inducibility of the vir genes (vira, -b, -c, -d, -e, and -g) on pria4 was examined at the transcriptional level, and the rna-starting sites were determined by s1-nuclease mapping and primer-extension experiments. all of these genes were inducible, while vira, -e, and -g were transcribed even under noninducing conditions. each transcription of virb, -c, -d, and -e was initiated at one particular site, but that of vira and -g occurred at two and three sites, respectively, depending on the cond ... | 1989 | 2479910 |
| [ribosomal rna sequencing with reverse transcriptase: its application to the phylogenetic study of cells]. | | 1989 | 2480986 |
| 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 |
| anaerobic processes in yellow lupin (lupinus luteus l.) root nodules. | the lupin root nodule homogenate was separated by centrifugation in the percoll density gradient into the rhizobium bacteroid fraction and plant subcellular components. high activities of alcohol dehydrogenase and lactate dehydrogenase in the soluble fraction of host plant, and high capability of the isolated bacteroids to oxidize ethanol, malate, lactate and acetaldehyde evidence functional interrelationship between the plant and bacteroids. | 1989 | 2486002 |
| nodule-specific repression of yellow lupin protein r18. | it was found, using immunochemical techniques, that protein r18 presumably specifically repressed during development of lupin root nodules (sikorski et al., 1989, acta biochim. polon., 36, 63-72) is present in various tissues of this plant. protein r18 was also detected in roots of four other legumes but was absent from the bacteroid-containing cells of root nodules. the data support our earlier view (sikorski et al., op. cit.) that expression of protein r18 is regulated by the coupled mechanism ... | 1989 | 2486003 |
| 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 |
| expression of bradyrhizobium japonicum nodulation gene in rhizobium fredii nod mutants. | the b. japonicum usda 110 plafr1 gene library was transferred to tn5-induced rhizobium fredii usda 191-4 nod- mutants with helper plasmid prk2013. smr tcr transconjugants occurred with a frequency of 5 x 10(-4). the transconjugants were purified and used to inoculate germinated soybean seeds. seven nodules were obtained in the nodulation experiment. the fast-growing nod+ smr tcr rhizobium fredii strain was isolated from all nodules. each isolate had acquired a new plasmid with a molecular mass o ... | 1989 | 2491321 |
| 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 |
| transformation of plant cells via agrobacterium. | | 1989 | 2491660 |
| 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 |
| 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 |
| 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 |
| sequence of the pseudomonas aeruginosa trpi activator gene and relatedness of trpi to other procaryotic regulatory genes. | in pseudomonas aeruginosa, the trpi gene product regulates the expression of the trpba gene pair encoding tryptophan synthase. trpi and trpba are transcribed divergently. the trpi dna sequence and deduced amino acid sequence were determined. the trpi start codon was found to be 103 base pairs from that of trpb. trpi encodes a 293-residue protein and the size of the trpi gene product, measured on sodium dodecyl sulfatepolyacrylamide gels, was close to that calculated from the amino acid sequence. ... | 1989 | 2492495 |
| product of the lactococcus lactis gene required for malolactic fermentation is homologous to a family of positive regulators. | malolactic fermentation is a secondary fermentation that many lactic acid bacteria can carry out when l-malate is present in the medium. the activation of the malolactic system in lactococcus lactis is mediated by a locus we call mler. induction of the genes necessary to perform malolactic fermentation occurs only in bacteria with a functional copy of mler. the mler gene consists of one open reading frame capable of coding for a protein with a calculated molecular mass of 33,813 daltons. the ami ... | 1989 | 2498286 |
| evidence for divalent cation (ca2+)-stabilized oligomeric proteins and covalently bound protein-peptidoglycan complexes in the outer membrane of rhizobium leguminosarum. | two unusual characteristics of some outer membrane proteins of rhizobium leguminosarum are described. first, most of the major outer membrane proteins could only be visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after lysozyme treatment of the isolated cell envelopes, suggesting a very strong, possibly covalent, interaction of these proteins with the peptidoglycan. these peptidoglycan-associated outer membrane proteins belonged to two distinct groups of immunologically r ... | 1989 | 2500420 |
| effect of carbofuran, carbaryl, and their metabolites on the growth of rhizobium sp. and azotobacter chroococcum. | | 1989 | 2500994 |
| two host-inducible genes of rhizobium fredii and characterization of the inducing compound. | random transcription fusions with mu d1(kan lac) generated three mutants in rhizobium fredii (strain usda 201) which showed induction of beta-galactosidase when grown in root exudate of the host plants glycine max, phaseolus vulgaris, and vigna ungliculata. two genes were isolated from a library of total plasmid dna of one of the mutants, 3f1. these genes, present in tandem on a 4.2-kilobase hindiii fragment, appear in one copy each on the symbiotic plasmid and do not hybridize to the rhizobium ... | 1988 | 2447061 |
| relationship between raman spectroscopic lines and growth of rhizobium japonicum. | the raman spectroscopic lines of liquid cultures of rhizobium japonicum have been compared with electron microscopic examinations and growth measurements of these cells. the results showed that the significant raman lines are related to the reproduction activities of the procaryotic cells. | 1987 | 2446767 |
| identification and characterization of the nifh and nifj promoter regions located on the nif-plasmid pea3 of enterobacter agglomerans 333. | small restriction fragments of the plasmid-borne enterobacter agglomerans 333 nif region were cloned into a promoter probe plasmid as transcriptional fusions with the lacz gene. identification of nifa-dependent promoters was accomplished by using a compatible plasmid which constitutively expresses the klebsiella pneumoniae nifa gene. beta-galactosidase assays showed strong activation of the cloned e. agglomerans promoters in escherichia coli by the heterologous k. pneumoniae nifa gene product. t ... | 1989 | 2504647 |
| construction of a lacz-kanamycin-resistance cassette, useful for site-directed mutagenesis and as a promoter probe. | a lacz gene without a promoter, but containing its ribosome-binding site, was cloned next to the kanamycin-resistance (kmr) gene of plasmid puc4k, yielding a lacz-kmr cassette. from the resulting plasmid, pkok5, the lacz-kmr cassette was recloned by means of bamhi into plasmid pkok4, a mobilizable derivative of pbr322 which mediates ampicillin, chloramphenicol and tetracycline resistance. the lacz-kmr cassette can be excised from pkok5 or pkok6 by digestion with bamhi, sali or psti. it can be us ... | 1989 | 2515118 |
| the -24/-12 promoter comes of age. | a new bacterial promoter type has been identified in the last few years. originally designated as nif (= nitrogen fixation) or ntr (= nitrogen regulation) consensus promoter, it is now evident that this promoter occurs in many different bacterial species and is used not only for genes involved in nitrogen assimilation but also for genes determining many other unrelated metabolic functions. the general features of this type of promoter are (i) the conserved -24(gg)/-12(gc) consensus sequence, (ii ... | 1989 | 2517036 |
| analysis of the major inducers of the rhizobium noda promoter from vicia sativa root exudate and their activity with different nodd genes. | root exudate of vicia sativa contains 7 inducers for the noda promoter of rhizobium leguminosarum biovar viciae. six of these inducers are flavanones. one inducer was identified as 3,5,7,3'-tetrahydroxy-4'-methoxyflavanone, and a second inducer most likely is 7,3'-dihydroxy-4'-methoxyflavanone. the inducing activity of these compounds and the other inducers depends on the nodd gene present in the test strains, which originated either from r. leguminosarum biovars viciae or trifolii, or from r. m ... | 1989 | 2519112 |
| 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 |
| nucleotide sequence and protein products of two new nodulation genes of rhizobium meliloti, nodp and nodq. | previous studies had suggested the existence of nodulation (nod) genes downstream of nodg in rhizobium meliloti strain 1021. we have established the dna sequence and analyzed the translation products of the genes located in this position. computer analysis of the dna sequence revealed a number of overlapping putative open-reading frames (orfs), so we constructed several clones that contained either full-length or truncated orfs. the protein products of these clones were expressed in both r. meli ... | 1989 | 2520820 |
| extension of host range of rhizobium leguminosarum bv. trifolii caused by point mutations in nodd that result in alterations in regulatory function and recognition of inducer molecules. | the positive activation of several nodulation genes in strain anu843 of rhizobium leguminosarum biovar trifolii is mediated by the product of the nodd gene and by the interaction of nodd with plant-secreted inducer and anti-inducer compounds. we have mutagenized the nodd gene of strain anu843 with nitrosoguanidine and have found that the ability of the mutated nodd products to interact with inducer and anti-inducer compounds is affected by the amino acid sequence in at least two key regions, inc ... | 1989 | 2520822 |
| isolation and characterization of a rhizobium loti gene required for effective nodulation of lotus pedunculatus. | a rhizobium loti gene required for effective invasion of the host lotus pedunculatus has been identified by transposon tn5 mutagenesis. cosmids that complemented a previously isolated mutation (239) at this invasion (inv) locus were identified by in planta complementation and used to construct a physical map of the gene region. the insertion site of tn5 in pn239 was mapped to a 7.5-kb ecori fragment, which complemented the mutation when subcloned into plafr1. further tn5 mutagenesis of the 7.5-k ... | 1989 | 2520823 |
| 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 |
| 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 |
| a non-nodulating alfalfa mutant displays neither root hair curling nor early cell division in response to rhizobium meliloti. | the early events in the alfalfa-rhizobium meliloti symbiosis include deformation of epidermal root hairs and the approximately concurrent stimulation of cell dedifferentiation and cell division in the root inner cortex. these early steps have been studied previously by analysis of r. meliloti mutants. bacterial strains mutated in nodabc, for example, fail to stimulate either root hair curling or cell division events in the plant host, whereas exopolysaccharide (exo) mutants of r. meliloti stimul ... | 1989 | 2535468 |
| 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 |
| 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 |
| isolation and characterization of mutants of rhizobium leguminosarum bv. viciae 248 with altered lipopolysaccharides: possible role of surface charge or hydrophobicity in bacterial release from the infection thread. | effects of alterations in lipopolysaccharide (lps) structure of rhizobium leguminosarum bv. viciae on effective symbiosis and on a number of cell surface characteristics were studied. tn5 mutants with altered lpss were screened for their inability to bind monoclonal antibody 3, one of three monoclonal antibodies to the tentative o-antigenic part of the wild-type lps of strain 248. ten class i lps mutants completely lacked the o-antigen-containing lps species. the class ii lps mutant had a severe ... | 1989 | 2536673 |