| effect of nh4+ on nitrogenase activity in nodule breis and bacteroides from pisum sativum l. | nodule breis and bacteroid preparations were made from pisum sativum l. (cv. trapper) inoculated with a single strain of rhizobium leguminosarum. the detached nodules were triturated under helium flow. the resultant breis could support c2h2 reduction in n-tris[hydroxymethyl]methyl-2-aminoethane-sulfonic acid buffer (tes) without any additions for over an hour. nh4+ was found to inhibit c2h2 reduction and h2 evolution. the inhibition was not dependent on the counterion and was evident immediately ... | 1981 | 6938248 |
| use of plasmid r68.45 for constructing a circular linkage map of the rhizobium trifolii chromosome. | plasmid r68.45 was used to promote conjugal transfer of chromosomal markers in rhizobium trifolii rs55. analysis of two-factor and three-factor crosses among r. trifolii strains enabled construction of a circular linkage map of the r. trifolii chromosome, containing 17 nutritional and resistance markers. | 1982 | 6947977 |
| expression of large plasmids in the endosymbiotic form of rhizobium leguminosarum. | isolated plasmid dna from rhizobium leguminosarum was hybridised with cellular rna from broth-cultured bacteria and endosymbiotic bacteroids. from these hybridisation, experiments it is concluded that plasmid genes are strongly expressed in bacteroids and only weakly or not at all in bacteria. from the hybridisation of plasmid dna with the cloned structural nif genes of klebsiella pneumoniae it is shown that at least part of the nif genes are located on a plasmid. | 1980 | 7001365 |
| large plasmids of fast-growing rhizobia: homology studies and location of structural nitrogen fixation (nif) genes. | a single large plasmid was isolated from multiplasmid-harboring strains rhizobium leguminosarum 1001 and r. trifolii 5. these single plasmids, as well as the largest plasmid detectable in r. phaseoli 3622, hybridized with part of the nif structural genes of klebsiella pneumoniae. in contrast, the plasmids of r. meliloti strains v7 and l5-30 did not show hybridization with the nif genes of k. pneumoniae, indicating that these genes might be located either on the chromosome or on a much larger pla ... | 1981 | 7009569 |
| uptake hydrogenase activity and atp formation in rhizobium leguminosarum bacteroids. | the role of uptake hydrogenase was studied in rhizobium leguminosarum bacteroids from the nodules of pisum sativum l. cv. homesteader. uptake hydrogenase activity, measured by the 3h2 uptake method, was dependent on o-consumption and was similar to h2 uptake measured by gas chromatography. km for o2 of 0.0007 atm (0.0709 kpa) and a km for h2 of 0.0074 atm (0.7498, kpa) were determined. h2 increased the rate of endogenous respiration by isolates with uptake hydrogenase (hup+) but had no effect on ... | 1982 | 7047503 |
| regulation of tryptophan genes in rhizobium leguminosarum. | twelve tryptophan auxotrophs of rhizobium leguminosarum were characterized biochemically. they were grown in complex and minimal media with several carbon sources, in both limiting and excess tryptophan. missing enzyme activities allowed assignment of all mutant to the trpe, trpd, trpb, or trpa gene, confirming earlier results with the same mutants (johnston et al., mol. gen. genet. 165:323-330, 1978). in regulatory experiments, only the first enzyme of the pathway, anthranilate synthase, respon ... | 1982 | 7061383 |
| mechanism of regulation of glucose transport in rhizobium leguminosarum. | multiple glucose transport systems were distinguished in rhizobium leguminosarum. we found nonlinear lineweaver-burk plots for the uptake of glucose, 2-deoxy-d-glucose, and alpha-methyl-d-glucoside, and this implied the existence of at least two uptake mechanisms. different patterns of inhibition of 2-deoxy-d-glucose uptake and alpha-methyl-d-glucoside uptake at 0.1 mm by various carbohydrates revealed differences in the stereospecificities of the transport systems. osmotic shock treatment aboli ... | 1982 | 7061388 |
| genetic transformation of rhizobium leguminosarum by plasmid dna. | we demonstrated the genetic transformation of rhizobium leguminosarum by r68.45 plasmid dna by freezing and thawing cell suspensions in the presence of r68.45 plasmid dna and 20 mm mgcl2. clones resistant to kanamycin and tetracycline were recovered at a frequency of 10(-8) per recipient cell. no colonies that were doubly drug resistant were recovered in parallel control experiments. | 1982 | 7061403 |
| molecular mechanism for loss of nodulation properties of rhizobium trifolii. | of 18 rhizobium trifolii strains tested, 12 showed a high frequency of loss of nodulation ability after incubation in cultures at elevated temperatures. a correlation between loss of nodulation ability and loss of a large plasmid was demonstrated for r. trifolii. in some nonnodulating (nod-) mutants, deletions occurred instead of total elimination of the plasmid molecule. the maximum curing effect was observed in bacteria incubated at 35 degrees c. after 4 or more days of incubation at this temp ... | 1982 | 7076625 |
| identification and mobilization by cointegrate formation of a nodulation plasmid in rhizobium trifolii. | a nodulation plasmid, prtr-514a, of molecular size 180 megadaltons (mdal) was identified in rhizobium trifolii strain nzp514. this plasmid was absent in both spontaneous and heat-cured nod- derivatives of nzp514, and these strains were unable to induce root hair curling. the ability to nodulate clover was transferred from the wild-type strain to a nod- derivatives, pn104, with the broad-host-range plasmid r68.45 (39 megadaltons) at a cotransfer frequency of about 4 x 10(-3). most of the nod+ tra ... | 1982 | 7085562 |
| plasmids and stability of symbiotic properties of rhizobium trifolii. | a conjugal plasmid which encodes both peak nodulation genes and nitrogenase genes, and which is labeled with the transposon tn5, was transferred to a wild-type rhizobium trifolii strain to examine the stability and expression of the host range and fixation (fix+) phenotypes. transconjugates were isolated which were shown to initially form nitrogen-fixing nodules (nod+ fix+) on both clovers and peas. these hybrid strains were then repeatedly passaged through either pea or clover nodules or onto a ... | 1982 | 7096265 |
| properties of rhizobium leguminosarum isolated from various regions of morocco. | twenty-eight isolates of rhizobium leguminosarum capable of nodulating broad-bean (vicia faba l. var. major) were collected throughout morocco and characterized by using morphological, physiological, biochemical and serological tests. the properties of isolates from within a given climatic zone varied as much as the properties of isolates from different zones. the isolates were adapted to desiccation, but were not adapted to temperatures higher than 37 degrees c. a high degree of heterogeneity w ... | 1982 | 7103311 |
| identification of the sym plasmid of rhizobium leguminosarum strain 1001 and its transfer to and expression in other rhizobia and agrobacterium tumefaciens. | | 1982 | 7146147 |
| [bacterial population dynamics in a soil--plant system]. | the dynamics of rhizobium leguminosarum and arthrobacter crystallopoietes populations introduced into soil at different levels of density was studied in a zone near barley roots. microbial life with a high rate of growth was found only at the root surface. for a. crystallopoietes, the ultimate bacterial incidence at the root surface was found to depend on the original level of population density. for rh. leguminosarum, the ultimate incidence was shown to reach an identical level irrespective of ... | 1981 | 7219211 |
| succinate transport in rhizobium leguminosarum. | the transport of succinate was studied in an effective streptomycin-resistant strain of rhizobium leguminosarum. high levels of succinate transport occurred when cells were grown on succinate, fumarate, or malate, whereas low activity was found when cells were grown on glucose, sucrose, arabinose, or pyruvate as the sole carbon source. because of the rapid metabolism of succinate after transport into the cells, a succinate dehydrogenase-deficient mutant was isolated in which intracellular succin ... | 1981 | 7287623 |
| infection and nodulation of clover by nonmotile rhizobium trifolii. | nonmotile mutants of rhizobium trifolii were isolated to determine whether bacterial motility is required for the infection and nodulation of clover. the nonmotile mutants were screened for their ability to infect and nodulate clover seedlings in fahraeus glass slide assemblies, plastic growth pouches, and vermiculite-sand-filled clay pots. in each system, the nonmotile mutants were able to infect and nodulate clover. | 1980 | 7364722 |
| rhizobium leguminosarum mutants incapable of normal extracellular polysaccharide production. | mutants of rhizobium leguminosarum which are deficient in normal polysaccharide production have been isolated and characterized. a correlation between diminished production of extracellular polysaccharide and reduced infection and nodulation efficiency has been observed. | 1980 | 7364730 |
| dynamics of rhizobium competition for nodulation of pisum sativum cv. afghanistan. | nodulation of pisum sativum cv. afghanistan by rhizobium leguminosarum strain tom can be blocked by the nonnodulating r. leguminosarum strain pf2. this system was used to study the dynamics of rhizobial binding to seedling root surfaces. appreciable numbers of 35s-labeled rhizobia bound to the root surface within 2h after inoculation. pf2 colonized the root surfaces earlier and in greater numbers that did tom. radioactive extracellular polysaccharides and lipopolysaccharides from either organism ... | 1980 | 7378950 |
| the bacterial 'enigma': cracking the code of cell-cell communication. | in recent years it has become clear that the production of n-acyl homoserine lactones (n-ahls) is widespread in gram-negative bacteria. these molecules act as diffusible chemical communication signals (bacterial pheromones) which regulate diverse physiological processes including bioluminescence, antibiotic production, plasmid conjugal transfer and synthesis of exoenzyme virulence factors in plant and animal pathogens. the paradigm for n-ahl production is in the bioluminescence (lux) phenotype o ... | 1995 | 7476157 |
| lipopolysaccharide epitope expression of rhizobium bacteroids as revealed by in situ immunolabelling of pea root nodule sections. | to investigate the in situ expression of lipopolysaccharide (lps) epitopes on nodule bacteria of rhizobium leguminosarum, monoclonal antibodies recognizing lps macromolecules were used for immunocytochemical staining of pea nodule tissue. many lps epitopes were constitutively expressed, and the corresponding antibodies reacted in nodule sections with bacteria at all stages of tissue infection and cell invasion. some antibodies, however, recognized epitopes that were only expressed in particular ... | 1994 | 7511581 |
| the psi operon of rhizobium leguminosarum biovar phaseoli: identification of two genes whose products are located at the bacterial cell surface. | we have delineated three short open reading frames, psia, orf-p and psib within the psi operon of rhizobium leguminosarum biovar phaseoli. psia, in a multi-copy plasmid, causes inhibition of exopolysaccharide synthesis in r. leguminosarum. in addition, the suppression of exopolysaccharide synthesis due to the multi-copy psia caused r. leguminosarum strains to stain with the dye calcofluor, a response that does not occur with wild-type strains of this species. insertions of a defective phoa gene ... | 1994 | 7517767 |
| the nodulation-signaling protein nodo from rhizobium leguminosarum biovar viciae forms ion channels in membranes. | the secreted nodulation-signaling protein nodo was purified from the supernatant of cultures of rhizobium leguminosarum biovar viciae. the native protein has a m(r) of approximately 67,000, suggesting that it exists as a dimer since the dna sequence predicts a m(r) of 30,002. pure nodo protein had no protease, pectinase, or cellulase activity, and no binding was observed to lipooligosaccharide nodulation factors. although nodo is relatively hydrophilic, it appeared to insert into liposomes and w ... | 1994 | 7524090 |
| isolation and characterization of ropa homologous genes from rhizobium leguminosarum biovars viciae and trifolii. | ropa encodes a 36-kda outer membrane protein of rhizobium leguminosarum bv. viciae strain 248 which constitutes the low-m(r) part of antigen group iii (r.a. de maagd, i.h.m. mulders, h.c.j. canter cremers, b.j.j. lugtenberg, j. bacteriol. 174:214-221, 1992). we observed that genes homologous to ropa are present in strain 248 as well as in other r. leguminosarum strains, and we describe the cloning and characterization of two of these genes. sequencing of a 2.2-kb bg/ii fragment from r. leguminos ... | 1995 | 7545151 |
| substrate specificity and kinetic studies of nodulation protein nodl of rhizobium leguminosarum. | all lipo-chitin oligosaccharides identified from rhizobium leguminosarum carry an o-acetyl moiety on c6 of the nonreducing terminal n-acetylglucosamine residue. previously, we have shown that purified nodl protein, using acetyl-coa as acetyl donor, in vitro acetylates n-acetylglucosamine, chitin oligosaccharides, and lipo-chitin oligosaccharides. in this paper, the enzymatic properties and substrate specificity of nodl protein were analyzed, using a spectrophotometric assay to quantify nodl tran ... | 1995 | 7548024 |
| the ntrbc genes of azospirillum brasilense are part of a nifr3-like-ntrb-ntrc operon and are negatively regulated. | a cosmid able to complement the nif- and nitrate-dependent growth phenotypes of the azospirillum brasilense mutant fp9 was isolated from a genomic library of the wild-type strain fp2. a 6-kb dna region was sequenced and showed two open reading frames (orfs) identified as the ntrb and ntrc genes. an orf1 located upstream from the ntrb gene and coding for a 36-kda polypeptide showed similarity to the nifr3 gene of rhodobacter capsulatus and the orf1 of rhizobium leguminosarum, both located upstrea ... | 1995 | 7553451 |
| identification of rhizobium-specific intergenic mosaic elements within an essential two-component regulatory system of rhizobium species. | analysis of the dna regions upstream of the phosphoenolpyruvate carboxykinase gene (pcka) in rhizobium meliloti and rhizobium sp. strain ngr234 identified an open reading frame which was highly homologous to the agrobacterium tumefaciens chromosomal virulence gene product chvi. a second gene product, 500 bp downstream of the chvi-like gene in r. meliloti, was homologous to the a. tumefaciens chvg protein. the homology between the r. meliloti and a. tumefaciens genes was confirmed, because the r. ... | 1995 | 7559334 |
| the hypbfcde operon from rhizobium leguminosarum biovar viciae is expressed from an fnr-type promoter that escapes mutagenesis of the fnrn gene. | pea (pisum sativum l.) bacteroids produced by rhizobium leguminosarum bv. viciae upm791 synthesize a membrane-bound (nife) hydrogenase which oxidizes h2 arising from the nitrogen fixation process in root nodules. synthesis of the active enzyme requires the products of the structural genes hupsl and an array of accessory proteins from at least 15 additional genes, including the gene cluster hypabfcde, likely involved in nickel metabolism. unlike the hupsl genes, which are expressed only in symbio ... | 1995 | 7559356 |
| cloning of nod gene regions from mesquite rhizobia and bradyrhizobia and nucleotide sequence of the nodd gene from mesquite rhizobia. | nitrogen-fixing symbiosis between bacteria and the tree legume mesquite (prosopis glandulosa) is important for the maintenance of many desert ecosystems. genes essential for nodulation and for extending the host range to mesquite were isolated from cosmid libraries of rhizobium (mesquite) sp. strain hw17b and bradyrhizobium (mesquite) sp. strain hw10h and were shown to be closely linked. all of the cosmid clones of rhizobia that extended the host range of rhizobium (parasponia) sp. strain ngr234 ... | 1995 | 7574650 |
| rhizobium nodi and nodj proteins play a role in the efficiency of secretion of lipochitin oligosaccharides. | thin-layer chromatographic analysis of extracts of d-[1-14c]glucosamine-labelled rhizobia was used to analyze the effects of nodi, nodj, and nodt on secretion of lipochitin oligosaccharide (lco) signal molecules. secretion was analyzed by comparing quantities of radiolabelled lcos present in the cellular and spent growth medium fractions. a second rapid and sensitive method was introduced to estimate the secreted lco fractions by using d-[1-14c]glucosamine-labelled cells grown in medium suppleme ... | 1995 | 7592394 |
| fragmentations of the large-subunit rrna in the family rhizobiaceae. | a 130-nucleotide-long rrna species corresponding to the 5' end of the 23s rrna gene was found in 96 strains belonging to different rhizobium, bradyrhizobium, and agrobacterium species. additional fragmentation in the central region of the large-subunit rrna occurred in all agrobacteria, except agrobacterium vitis, and in most rhizobium leguminosarum and rhizobium etli strains but did not occur in any of the other rhizobia and bradyrhizobia studied. | 1995 | 7592497 |
| supraoperonic clustering of pca genes for catabolism of the phenolic compound protocatechuate in agrobacterium tumefaciens. | the protocatechuate branch of the beta-ketoadipate pathway comprises the last six enzymatic steps in the catabolism of diverse phenolic compounds to citric acid cycle intermediates. in this paper, the regulation and tight supraoperonic clustering of the protocatechuate (pca) genes from agrobacterium tumefaciens a348 are elucidated. a previous study found that the pcad gene is controlled by an adjacent regulatory gene, pcaq, which encodes an activator. the activator responded to beta-carboxy-cis, ... | 1995 | 7601847 |
| lipid a biosynthesis in rhizobium leguminosarum: role of a 2-keto-3-deoxyoctulosonate-activated 4' phosphatase. | lipid a from several strains of the n2-fixing bacterium rhizobium leguminosarum displays significant structural differences from escherichia coli lipid a, one of which is the complete absence of phosphate groups. however, the first seven enzymes of e. coli lipid a biosynthesis, leading from udp-glcnac to the phosphorylated intermediate, 2-keto-3-deoxyoctulosonate (kdo2)-lipid iva, are present in r. leguminosarum. we now describe a membrane-bound phosphatase in r. leguminosarum extracts that remo ... | 1995 | 7638195 |
| bacterial and plant glycoconjugates at the rhizobium-legume interface. | many classes of bacterial and plant glycoconjugate have been shown to be involved in establishing the rhizobium root nodule symbiosis with peas (pisum sativum). it was demonstrated, using techniques of molecular genetics, that a group of rhizobium nodulation genes (nod genes) co-operate to synthesize a lipo-oligosaccharide signal molecule that specifically initiates nodule development on legume hosts. an additional gene function, encoded by nodx, has been found to extend the host range of rhizob ... | 1994 | 7639793 |
| rhizobium leguminosarum nodt is related to a family of outer-membrane transport proteins that includes tolc, prtf, cyae and aprf. | cells containing a protein fusion consisting of the rhizobium leguminosarum bv. viciae nodulation protein, nodt, fused to phoa, produced alkaline phosphatase activity, indicating that the n terminus of nodt could translocate phoa across the inner membrane. cellular fractionation suggested that the nodt::phoa fusion is targetted to the outer membrane. nodt resembles a family of bacterial outer membrane proteins including tolc, prtf, cyae and aprf, which are involved in secretion. by analogy, nodt ... | 1995 | 7642132 |
| identification and characterization of a rhizobium leguminosarum bv. phaseoli gene that is important for nodulation competitiveness and shows structural homology to a rhizobium fredii host-inducible gene. | dna sequence analysis of a 1.4-kb sali-hindiii segment located approximately 2 kb upstream of the rhizobium leguminosarum bv. phaseoli syrm gene revealed the presence of an open reading frame (orf3) encoding a putative 295-amino acid polypeptide with a molecular mass of 33,401 da. orf3 is homologous to a r. fredii host-inducible gene. the proteins encoded by r. l. bv. phaseoli orf3 and by the r. fredii host-inducible gene share 37% sequence identity. in contrast to the r. fredii host-inducible g ... | 1995 | 7655066 |
| early nodulin gene expression during nod factor-induced processes in vicia sativa. | rhizobium leguminosarum bv. viciae-secreted nod factors are able to induce root hair deformation, the formation of nodule primordia and the expression of early nodulin genes in vicia sativa (vetch). to obtain more insight into the mode of action of nod factors the expression of early nodulin genes was followed during nod factor-induced root hair deformation and nodule primordium formation. the results of these studies suggested that the expression of vsenod5 and vsenod12 is not required for root ... | 1995 | 7655502 |
| characterization of the cychjkl genes involved in cytochrome c biogenesis and symbiotic nitrogen fixation in rhizobium leguminosarum. | mutants of rhizobium leguminosarum bv. viciae unable to respire via the cytochrome aa3 pathway were identified by the inability to oxidize n,n'-dimethyl-p-phenylenediamine. two mutants which were complemented by cosmid pij1942 from an r. leguminosarum clone bank were identified. although pea nodules induced by these mutants contained many bacteroids, no symbiotic nitrogen fixation was detected. heme staining of cellular proteins revealed that all cytochrome c-type heme proteins were absent. thes ... | 1995 | 7665469 |
| mutation or increased copy number of node has no effect on the spectrum of chitolipooligosaccharide nod factors made by rhizobium leguminosarum bv. trifolii. | the bacterial gene node is the key determinant of host specificity in the rhizobium leguminosarum-legume symbiosis and has been proposed to determined unique polyunsaturated fatty acyl moieties in chitolipooligosaccharides (clos) made by the bacterial symbiont. we evaluated node function by examining clos structures made by wild-type r. leguminosarum bv. trifolii anu843, an isogenic node::tn5 mutant, and a recombinant strain containing multiple copies of the psym nod region of anu843. 1h-nmr, el ... | 1995 | 7673121 |
| surface polysaccharide mutants of rhizobium sp. (acacia) strain grh2: major requirement of lipopolysaccharide for successful invasion of acacia nodules and host range determination. | two transposon tn5-induced mutants of wild-type broad-host-range rhizobium sp. grh2 were isolated and found to harbour different alterations in surface polysaccharides. these mutants, designated grh2-14 and grh2-50, induced a few, empty nodules on acacia and lost the ability to nodulate most host herbaceous legumes. whereas mutant grh2-14 produces an acidic exopolysaccharide (eps) similar to the wild-type, the acidic eps of mutant grh2-50 lacks galactose and the pyruvyl and 3-hydroxybutyryl subs ... | 1995 | 7711895 |
| the effect of l-tryptophane on yield of field bean and activity of soil microorganisms. | the pot trial was performed to study the effect of l-tryptophane (as an auxin precursor) applied in the amount 0.3 and 3.0 mg per 1 kg of the soil on yield and the chemical composition of field bean. the effects of this compound on dehydrogenases activity in the cells rhizobium leguminosarum isolated from root nodules, soil dehydrogenases activity and number of microorganisms from different systematic or physiological groups were also studied. the effects of l-tryptophane were compared to indole ... | 1994 | 7740988 |
| a homolog of the rhizobium meliloti nitrogen fixation gene fixn is involved in the production of a microaerobically induced oxidase activity in the phytopathogenic bacterium agrobacterium tumefaciens. | hybridization analysis using the rhizobium meliloti nitrogen fixation gene fixn as a probe revealed the presence of a homologous dna region in the phytopathogenic bacterium agrobacterium tumefaciens. hybridization signals were also detected with total dnas of rhizobium leguminosarum bv. phaseoli, rhodobacter capsulatus and escherichia coli, but not those of xanthomonas campestris pv. campestris and pseudomonas putida. the hybridizing fragment from a. tumefaciens was cloned and sequenced. the pre ... | 1995 | 7753030 |
| long-term effects of metals in sewage sludge on soils, microorganisms and plants. | this paper reviews the evidence for impacts of metals on the growth of selected plants and on the effects of metals on soil microbial activity and soil fertility in the long-term. less is known about adverse long-term effects of metals on soil microorganisms than on crop yields and metal uptake. this is not surprising, since the effects of metals added to soils in sewage sludge are difficult to assess, and few long-term experiments exist. controlled field experiments with sewage sludges exist in ... | 1995 | 7766215 |
| characterization of the structural elements in lipid a required for binding of a recombinant fragment of bactericidal/permeability-increasing protein rbpi23. | both human bactericidal/permeability-increasing protein (bpi) and a recombinant amino-terminal fragment of bpi (rbpi23) have been shown to bind with high affinity to the lipid a region of lipopolysaccharide (lps) (h. gazzano-santoro, j. b. parent, l. grinna, a. horwitz, t. parsons, g. theofan, p. elsbach, j. weiss, and p. j. conlon, infect. immun. 60:4754-4761, 1992). in the present study, lipid a preparations derived from bacterial lps as well as synthetic lipid a's and various lipid a analogs ... | 1995 | 7768599 |
| is292: a novel insertion element from agrobacterium. | a new insertion sequence, is292, located in the 6b gene of a nopaline-type agrobacterium strain (x88-292) isolated from poplar was identified and sequenced. is292 is 2494 bp long, has 21 bp inverted terminal repeats with two mismatches, and generates 10 bp direct repeats upon integration. no sequence similarity was found between is292 and other insertion elements associated with agrobacterium, but it shows strong similarity with isr/1 from rhizobium leguminosarum bv. viciae. the occurrence of is ... | 1995 | 7773388 |
| construction and characterization of a rhizobium leguminosarum biovar viciae strain designed to assess horizontal gene transfer in the environment. | an integration vector was developed which inserts cloned dna in a non-essential site of the rhizobium leguminosarum biovar viciae chromosome. the expression of integrated genes is under the control of the constitutive neomycin phosphotransferase ii (nptii) promoter of transposon tn5. the design of the vector ensures that loss of vector sequences can be detected, enabling selection of progeny containing only the requisite dna. the newly constructed vector was employed to insert the escherichia co ... | 1995 | 7781972 |
| structure of the unusual trisaccharide lipopolysaccharide component produced by a symbiotically defective mutant of rhizobium leguminosarum biovar viciae. | the structure of an unusual trisaccharide component isolated from the lipopolysaccharide (lps) of a tn5 mutant of rhizobium leguminosarum biovar viciae vf39 which is defective in infection of its host plant has been elucidated. this mutant also appears to be defective in the synthesis of a tetrasaccharide component normally synthesized by the wild-type organism. the three glycosyl components are galactose, mannose, and 3-deoxy-d-manno-2-octulosonic acid (kdo). mannose is linked to the 5-position ... | 1994 | 7805065 |
| structural identification of metabolites produced by the nodb and nodc proteins of rhizobium leguminosarum. | the rhizobium nodulation genes nodabc are involved in the synthesis of lipo-chitin oligosaccharides. we have analysed the metabolites which are produced in vivo and in vitro by rhizobium strains which express the single noda, nodb and nodc genes or combinations of the three. in vivo radioactive labelling experiments, in which d-[1-14c]-glucosamine was used as a precursor, followed by mass spectrometric analysis of the purified radiolabelled metabolic products, showed that rhizobium strains that ... | 1994 | 7815941 |
| oxygen sensitivity and metal ion-dependent transcriptional activation by nifa protein from rhizobium leguminosarum biovar trifolii. | the nifa protein from rhizobium leguminosarum biovar trifolii (r. trifolii) strain anu843 lacks an n-terminal domain present in homologous nifa proteins from other diazotrophs. the r. trifolii nifa gene product is unstable when expressed in escherichia coli under both aerobic and microaerobic conditions. stability is increased by fusion of additional amino acids to the n-terminus of the protein or by expression of nifa in sno mutant (presumed protease deficient) strains of e. coli. transcription ... | 1994 | 7816041 |
| differentiation of brucella abortus bv. 1, 2, and 4, brucella melitensis, brucella ovis, and brucella suis bv. 1 by pcr. | several pcr assays which identify the genus brucella but do not discriminate among species have been reported. we describe a pcr assay that comprises five oligonucleotide primers which can identify selected biovars of four species of brucella. individual biovars within a species are not differentiated. the assay can identify three biovars (1, 2, and 4) of b. abortus, all three biovars of b. melitensis, biovar 1 of b. suis, and all b. ovis biovars. these biovars include all of the brucella specie ... | 1994 | 7852552 |
| structurally diverse chitolipooligosaccharide nod factors accumulate primarily in membranes of wild type rhizobium leguminosarum biovar trifolii. | the general view on rhizobium chitolipooligosaccharides (clos) is that they are made in very low levels as diffusible molecules and are primarily secreted by the bacteria into the extracellular milieu where they interact with the host. however, the structural and predicted physicochemical properties of these amphiphilic molecules led us to postulate that they should normally be targeted to bacterial membranes after synthesis. thus, we analyzed membrane lipid extracts of rhizobium leguminosarum b ... | 1995 | 7893680 |
| rhizobium leguminosarum nodulation gene (nod) expression is lowered by an allele-specific mutation in the dicarboxylate transport gene dctb. | to identify host genes that might influence nod (nodulation) gene expression in rhizobium leguminosarum, a nodc-phoa reporter plasmid (carrying nodd) was introduced into a chemically mutagenized population of a r. leguminosarum strain lacking a symbiotic plasmid. the transconjugants were screened for expression of alkaline phosphatase (phoa) on plates containing hesperetin, an inducer of nod genes, and a mutant with reduced expression was identified. when the nodc-phoa plasmid was cured from the ... | 1995 | 7894701 |
| rhizobium leguminosarum contains multiple chaperonin (cpn60) genes. | we have examined the heat shock response of rhizobium leguminosarum. after normal growth at 28 degrees c, a 10 min heat shock at 37 degrees c induced the synthesis of proteins with approximate m(r) values of 90,000, 70,000, 60,000, 58,000, 19,000, 17,000 and 13,000. a monoclonal antibody raised against the e. coli cpn60 cross-reacted with proteins of m(r) 60,000 and 58,000 in r. leguminosarum, suggesting that both were cpn60 homologues. hybridization of an e. coli cpn60 probe to total dna from r ... | 1994 | 7909257 |
| regulation of nitrogen metabolism is altered in a glnb mutant strain of rhizobium leguminosarum. | we isolated a rhizobium leguminosarum mutant strain altered in the glnb gene. this event, which has never been described in the rhizobiaceae, is rare in comparison to mutants isolated in the contiguous gene, glna. the glnb mutation removes the glnba promoter but in vivo does not prevent glna expression from its own promoter, which is not nitrogen regulated. the glnb mutant strain does not grow on nitrate as a sole nitrogen source and it is nod+, fix+. two -24/-12 promoters, for the glnii and gln ... | 1994 | 7910937 |
| purification of rhizobium leguminosarum hypb, a nickel-binding protein required for hydrogenase synthesis. | the products of the rhizobium leguminosarum hyp gene cluster are necessary for synthesis of a functional uptake [nife] hydrogenase system in symbiosis with pea plants, and at least for hypb and hypf, a role in hydrogenase-specific nickel metabolism has been postulated (l. rey, j. murillo, y. hernando, e. hidalgo, e. cabrera, j. imperial, and t. ruiz-argüeso, mol. microbiol. 8:471-481, 1993). the r. leguminosarum hypb gene product has been overexpressed in escherichia coli and purified by immobil ... | 1994 | 7928968 |
| resistance to nodulation of cv. afghanistan peas is overcome by nodx, which mediates an o-acetylation of the rhizobium leguminosarum lipo-oligosaccharide nodulation factor. | only some strains of rhizobium leguminosarum biovar viciae can efficiently nodulate varieties of peas such as cv. afghanistan, which carry a recessive allele that blocks efficient nodulation by most western isolates of r.i. viciae. one strain (tom) which can nodulate cv. afghanistan peas has a gene (nodx) that is required to overcome the nodulation resistance. strain tom makes significantly lower amounts of lipo-oligosaccharide nodulation factors than other strains of r.i. viciae and this effect ... | 1993 | 7934826 |
| a rhizobium tropici dna region carrying the amino-terminal half of a nodd gene and a nod-box-like sequence confers host-range extension. | rhizobium tropici ciat899 is a broad-host-range strain that, in addition to phaseolus, nodulates other plant legumes such as leucaena and macroptilium. the narrow-host-range of rhizobium leguminosarum biovars phaseoli (strain ce3) and trifolii (strain rs1051) can be extended to leucaena esculenta and phaseolus vulgaris plants, respectively, by the introduction of a dna fragment 521 bp long, which carries 128 amino acids of the amino-terminal region of a nodd gene from r. tropici, as well as a pu ... | 1993 | 7934929 |
| hupk, a hydrogenase-ancillary protein from rhizobium leguminosarum, shares structural motifs with the large subunit of nife hydrogenases and could be a scaffolding protein for hydrogenase metal cofactor assembly. | | 1993 | 7934943 |
| cell wall degradation during infection thread formation by the root nodule bacterium rhizobium leguminosarum is a two-step process. | in the nitrogen-fixing root-nodule symbiosis of rhizobium leguminosarum biovar viciae and its host plants pea and vetch, the bacteria enter one root cortical cell after another via a tip-growing structure, the infection thread. rhizobial nod (nodulation) factors induce the formation of preinfection thread structures (van brussel, a.a.n., r. bakhuizen, p.c. van spronsen, h.p. spaink, t. tak, b.j.j. lugtenberg, j.w. kijne, science 257, 70-72 (1992)), but formation of infection threads requires the ... | 1994 | 7957317 |
| the pss4 gene from rhizobium leguminosarum by viciae vf39: cloning, sequence and the possible role in polysaccharide production and nodule formation. | the tn5 insertion into the genome of rhizobium leguminosarum bv viciae vf39, resulting in non-mucoid growth and formation of non-n2-fixing nodule-like structures on vicia faba plants, was mapped within a 1.4-kb ecorv-saci fragment. nucleotide sequence analysis revealed an orf (pss4) of 263 amino acids (aa). three transcription start points (tsp) were determined. two of them were localized upstream from the first gtg codon; the third tsp was mapped in front of the second putative start codon (gtg ... | 1994 | 7959035 |
| sequences, organization and analysis of the hupzmnoqrtv genes from the azotobacter chroococcum hydrogenase gene cluster. | hydrogen-uptake (hup) activity in azotobacter chroococcum depends upon a cluster of genes spread over 13,687 bp of the chromosome. six accessory genes of the cluster, hupabycde, begin 4.8 kb downstream of the structural genes, hupsl, and are required for the formation of a functional [nife] hydrogenase. the sequencing of the intervening 4.8 kb of hup-specific dna has now been completed. this revealed eight additional closely linked orfs, which we designated hupz, hupm, hupn, hupo, hupq, hupr, hu ... | 1994 | 7966281 |
| cloning and sequencing show that 4-hydroxybenzoate hydroxylase (poba) is required for uptake of 4-hydroxybenzoate in rhizobium leguminosarum. | mutants of rhizobium leguminosarum bv. viciae mnf300 and r. leguminosarum bv. trifolii wu95 unable to accumulate 4-hydroxybenzoate lack 4-hydroxybenzoate hydroxylase. the capacity of these mutants to take up and grow on 4-hydroxybenzoate was restored by a 2.0 kb ecori-psti dna fragment. this contained only one orf which had over 60% dna sequence similarity with the structural gene for 4-hydroxybenzoate hydroxylase (poba) from pseudomonas spp. and acinetobacter. reported effects of metabolic inhi ... | 1994 | 8000543 |
| identification of chromosomal genes located downstream of dctd that affect the requirement for calcium and the lipopolysaccharide layer of rhizobium leguminosarum. | in rhizobium leguminosarum both the c4-dicarboxylate transport system and wild-type lipopolysaccharide layer (lps) are essential for nitrogen fixation. a tn5 mutant (ru301) of r. leguminosarum bv. viciae 3841, was isolated that is only able to synthesize lps ii, which lacks the o-antigen. strain ru301 exhibits a rough colony morphology, flocculates in culture and is unable to swarm in ty agar. it also fails to grow on organic acids, sugars or ty unless the concentration of calcium or magnesium i ... | 1994 | 8000544 |
| expression of the symbiotic plasmid from rhizobium leguminosarum biovar trifolii in sphingobacterium multivorum. | an inoculant strain of rhizobium leguminosarum biovar trifolii containing a tn5 marked symbiotic plasmid transferred this plasmid by conjugation to sphingobacterium multivorum, an organism that can be found in soil. the transconjugant bacteria nodulated the roots of white clover (trifolium repens) seedlings but did not fix atmospheric nitrogen. microscopic examination revealed abnormal nodule structures. bacteria isolated from the nodules were shown to be closely related to the recipient s. mult ... | 1994 | 8000966 |
| serine residue 45 of nodulation protein nodf from rhizobium leguminosarum bv. viciae is essential for its biological function. | a system for testing the role of the rhizobium nodf gene in the production of host-specific lipochitin oligosaccharides and in nodulation was developed. we show that a mutant nodf gene, in which the codon for serine residue 45 was changed to that for threonine, still expresses nodf, which, however, is no longer functional. | 1994 | 8002602 |
| the adaptive acid tolerance response in root nodule bacteria and escherichia coli. | root nodule bacteria and escherichia coli show an adaptive acid tolerance response when grown under mildly acidic conditions. this is defined in terms of the rate of cell death upon exposure to acid shock at ph 3.0 and expressed in terms of a decimal reduction time, d. the d values varied with the strain and the ph of the culture medium. early exponential phase cells of three strains of rhizobium leguminosarum (wu95, 3001 and wsm710) had d values of 1, 6 and 5 min respectively when grown at ph 7 ... | 1994 | 8002711 |
| sequence and regulation of psra, a gene on the sym plasmid of rhizobium leguminosarum biover phaseoli which inhibits transcription of the psi genes. | the psr region of rhizobium leguminosarum biovar phaseoli had originally been recognized on the basis of its ability to repress the transcription of the psi genes, one of which, psia, inhibits exopolysaccharide synthesis when cloned in multi-copy plasmids. both psr and psi are located on the symbiotic plasmid prp2ji. the psra gene was localized and sequenced. the deduced amino acid sequence of psra was shown to have similarity to the dna-binding region of a family of other transcriptional regula ... | 1994 | 8012570 |
| genetic characterization of rhizobium sp. strain tal1145 that nodulates tree legumes. | rhizobium sp. strain tal1145 nodulates leucaena leucocephala and phaseolus vulgaris, in addition to a wide range of tropical tree legumes. six overlapping clones that complemented nodulation defects in leucaena and bean rhizobia were isolated and a 40-kb map of the symbiosis region was constructed. the common nod and nifa genes were situated approximately 17 kb apart, with the nodij genes in between. these clones enabled a derivative of tal1145 carrying a partially deleted psym to form ineffecti ... | 1994 | 8012908 |
| chromosomal location of lectin genes indicates they are not the basis of rhizobium strain specificity mutations identified in pea (pisum sativum l.). | a lectin gene family is located on linkage group 7 in pea. the lectin genes are arranged as a cluster, with no recombination observed within the multigene family. a lectin-like cdna clone, pea207, and eight dna fragments generated by random priming also were mapped in the region of the lectin genes. none of the known pea mutants altering rhizobium leguminosarum strain specificity map to this region of the genome, and therefore their altered specificities appear not to be directly produced by mut ... | 1994 | 8014459 |
| identification of a gene encoding a thioredoxin-like product necessary for cytochrome c biosynthesis and symbiotic nitrogen fixation in rhizobium leguminosarum. | a tn5-induced mutant of rhizobium leguminosarum bv. viciae could not form nitrogen-fixing nodules on pea or vetch because of a lesion in electron transport to oxygen. the mutant lacked spectroscopically detectable cytochromes c and aa3. no proteins containing c-type cytochrome could be identified in the mutant by heme staining of proteins fractionated on polyacrylamide gels, indicating that the mutant was defective in maturation of all c-type cytochromes. the tn5 mutation was determined to be lo ... | 1994 | 8021193 |
| flavone-enhanced accumulation and symbiosis-related biological activity of a diglycosyl diacylglycerol membrane glycolipid from rhizobium leguminosarum biovar trifolii. | rhizobium leguminosarum bv. trifolii is the bacterial symbiont which induces nitrogen-fixing root nodules on the leguminous host, white clover (trifolium repens l.). in this plant-microbe interaction, the host plant excretes a flavone, 4',7-dihydroxyflavone (dhf), which activates expression of modulation genes, enabling the bacterial symbiont to elicit various symbiosis-related morphological changes in its roots. we have investigated the accumulation of a diglycosyl diacylglycerol (bf-7) in wild ... | 1994 | 8021221 |
| construction of multipurpose gene cartridges based on a novel synthetic promoter for high-level gene expression in gram-negative bacteria. | a series of gene cartridges containing a novel synthetic promoter (psyn) was constructed. the psyn sequence is based on the consensus of a number of naturally occurring promoters and displays strong activity in escherichia coli and rhizobium leguminosarum. in a direct comparison, psyn proved to be about twice as strong as the tac promoter in e. coli, while the difference in rhizobium was about tenfold. a small psyn cartridge was constructed by adding a shine-dalgarno sequence, an atg codon, and ... | 1994 | 8026755 |
| identification of a rhizobium leguminosarum gene homologous to nodt but located outside the symbiotic plasmid. | an open reading frame (orf471), homologous to nodt from rhizobium leguminosarum, has been found outside the symbiotic plasmid. the deduced amino-acid sequence indicates that the gene product is an outer membrane lipoprotein similar to the nodt proteins. this orf seems to be widespread among r. leguminosarum bv. viciae strains and its presence in the genetic background of different strains may explain the lack of a nodulation-deficient phenotype found in such strains carrying a nod mutation. | 1994 | 8026763 |
| specific, high affinity binding of chitin fragments to tomato cells and membranes. competitive inhibition of binding by derivatives of chitooligosaccharides and a nod factor of rhizobium. | suspension-cultured tomato cells have a sensitive perception system for chitin fragments with a degree of polymerization (dp) > or = 4 and react to these compounds with a transient alkalinization of their culture medium (felix, g., regenass, m., and boller, t. (1993) plant. j. 4, 307-316). a chitin fragment with dp 5 was aminated at the reducing end and coupled to t-butoxycarbonyl-l-[35s]methionine via an amidoglycine spacer. the radiolabeled chitin fragment (approximately 1000 ci/mmol) exhibite ... | 1994 | 8027050 |
| characterization of the rhizobium leguminosarum biovar phaseoli nifa gene, a positive regulator of nif gene expression. | we report the isolation, mutational analysis and the nucleotide sequence of the rhizobium leguminosarum bv. phaseoli nifa gene. comparison of the deduced amino acid sequence with other nifa sequences indicated the presence of the conserved central activator and the c-terminal dna-binding domains. nodules elicited by a r. leguminosarum bv. phaseoli nifa mutant were symbiotically ineffective. the expression of a nifa-gusa fusion was shown to be independent on the oxygen status of the cell. we clon ... | 1994 | 8042903 |
| two inverted repeats in the nodd promoter region are involved in nodd regulation in rhizobium leguminosarum. | in rhizobium leguminosarum (r.l.) biovar viciae, the nodulation gene nodd encodes a transcriptional activator (nodd) which binds to highly conserved dna sequences (nod-boxes) in the promoters of other nod operons. in addition, nodd represses nodd transcription and this occurs at the divergent and overlapping noda-nodd promoters. we mutagenised this region with hydroxylamine, and by cloning the mutagenised dna into a vector carrying the lacz reporter gene downstream from the cloning site identifi ... | 1994 | 8045429 |
| biosynthesis of a structurally novel lipid a in rhizobium leguminosarum: identification and characterization of six metabolic steps leading from udp-glcnac to 3-deoxy-d-manno-2-octulosonic acid2-lipid iva. | lipopolysaccharides (lpss) are prominent structural components of the outer membranes of gram-negative bacteria. in rhizobium spp. lps functions as a determinant of the nitrogen-fixing symbiosis with legumes. lps is anchored to the outer surface of the outer membrane by the lipid a moiety, the principal lipid component of the outer bacterial surface. several notable structural differences exist between the lipid a of escherichia coli and that of rhizobium leguminosarum, suggesting that diverse b ... | 1994 | 8045896 |
| nickel availability to pea (pisum sativum l.) plants limits hydrogenase activity of rhizobium leguminosarum bv. viciae bacteroids by affecting the processing of the hydrogenase structural subunits. | rhizobium leguminosarum bv. viciae upm791 induces the synthesis of an [nife] hydrogenase in pea (pisum sativum l.) bacteroids which oxidizes the h2 generated by the nitrogenase complex inside the root nodules. the synthesis of this hydrogenase requires the genes for the small and large hydrogenase subunits (hups and hupl, respectively) and 15 accessory genes clustered in a complex locus in the symbiotic plasmid. we show here that the bacteroid hydrogenase activity is limited by the availability ... | 1994 | 8071205 |
| rhizobia catabolize nod gene-inducing flavonoids via c-ring fission mechanisms. | gas chromatographic and mass spectrometric analyses of derivatized culture medium extracts were used to identify the products of flavonoid metabolism by rhizobia. a number of rhizobium species and biovars degraded their nod gene-inducing flavonoids by mechanisms which originated in a cleavage of the c-ring of the molecule and which yielded conserved a- and b-ring products among the metabolites. in contrast, pseudomonas putida degraded quercetin via an initial fission in its a-ring, and agrobacte ... | 1994 | 8071218 |
| rhizobium inoculation and physical wounding result in the rapid induction of the same chalcone synthase copy in trifolium subterraneum. | the gene or genes encoding chalcone synthase (chs) in the legume trifolium subterraneum (subterranean clover) were induced within 6 hr after inoculation with rhizobium leguminosarum bv. trifolii strain anu843. no induction was found in uninoculated controls or plants inoculated with either the nodulation-deficient r. l. bv. trifolii strain anu845 (psym-) or r. meliloti strain 1021, which is capable of nodulating alfalfa but not clover. morphological examination of the interaction between the leg ... | 1994 | 8075422 |
| cytochrome aa3 gene regulation in members of the family rhizobiaceae: comparison of copper and oxygen effects in bradyrhizobium japonicum and rhizobium tropici. | dithionite-reduced minus ferricyanide-oxidized difference spectra on membranes from rhizobium tropici (formerly rhizobium leguminosarum bv. phaseoli) incubated at progressively lower o2 concentrations showed only a slight concomitant decrease in a603, the alpha-peak of cytochrome aa3. in contrast to previous results on bradyrhizobium japonicum, r. tropici showed no significant o2-mediated reduction in the level of either coxa transcription or cytochrome aa3 activity (as measured by ascorbate-n,n ... | 1994 | 8117073 |
| biological activity of rhizobium sp. ngr234 nod-factors on macroptilium atropurpureum. | the broad host range of rhizobium sp. ngr234 is based mainly on its ability to secrete a family of lipooligosaccharide nod factors. to monitor nod-factor purification, we used the small seeded legume macroptilium atropurpureum, which responds evenly and consistently to nod factors. at concentrations between approximately equal to 10(-11) m and 10(-9) m, this response takes the form of deformation of the root hairs. higher concentrations (approximately equal to 10(-9) to 10(-7) m), provoked profo ... | 1993 | 8118058 |
| the new class ii transposon tn163 is plasmid-borne in two unrelated rhizobium leguminosarum biovar viciae strains. | tn163 is a transposable element identified in rhizobium leguminosarum bv. viciae by its high insertion rate into positive selection vectors. the 4.6 kb element was found in only one further r. leguminosarum bv. viciae strain out of 70 strains investigated. both unrelated r. leguminosarum bv. viciae strains contained one copy of the transposable element, which was localized in plasmids native to these strains. dna sequence analysis revealed three large open reading frames (orfs) and 38 bp termina ... | 1994 | 8121409 |
| homology of genes for exopolysaccharide synthesis in rhizobium leguminosarum and effect of cloned exo genes on nodule formation. | a 5.4 kb bamhi fragment of r. leguminosarum bv. trifolii ta1 was found to carry genes involved in exopolysaccharide synthesis (exo genes). this fragment was strongly hybridized to the total dna from r. l. bv. viciae and bv. phaseoli digested with ecori. no homology was found with total dna of r. meliloti and rhizobium sp. ngr 234. the exo genes from r. l. bv. trifolii ta1 conjugally introduced into r. l. bv. viciae 1302 considerably affected the symbiosis: the nodules induced on vetch were abort ... | 1993 | 8140821 |
| isolation and characterization of a regulatory gene affecting rhamnolipid biosurfactant synthesis in pseudomonas aeruginosa. | a mutant strain (65e12) of pseudomonas aeruginosa that is unable to produce rhamnolipid biosurfactants and lacks rhamnosyltransferase activity was genetically complemented by using a p. aeruginosa pg201 wild-type gene library. a single complementing cosmid was isolated on the basis of surface tension measurements of subcultures of the transconjugants by using a sib selection strategy. the subcloning of the complementing cosmid clone yielded a 2-kb fragment capable of restoring rhamnolipid biosyn ... | 1994 | 8144472 |
| phospholipids of rhizobium contain node-determined highly unsaturated fatty acid moieties. | in rhizobium leguminosarum the nodabc and nod-fel operons are involved in the production of lipooligosaccharide signals, which mediate host specificity. a node-determined highly unsaturated c18:4 fatty acid (trans-2,trans-4,trans-6,cis-11-octadecatetraenoic acid) is essential for the ability of the signals to induce nodule primordia (spaink, h. p., sheeley, d. m., van brussel, a. a. n., glushka, j., york, w.s., tak, t., geiger, o., kennedy, e. p., reinhold, v. n., and lugtenberg, b. j. j. (1991) ... | 1994 | 8157634 |
| nodulating ability of rhizobium tropici is conditioned by a plasmid-encoded citrate synthase. | rhizobium species elicit the formation of nitrogen-fixing root nodules through a complex interaction between bacteria and plants. various bacterial genes involved in the nodulation and nitrogen-fixation processes have been described and most have been localized on the symbiotic plasmids (psym). we have found a gene encoding citrate synthase on the psym plasmid of rhizobium tropici, a species that forms nitrogen-fixing nodules on the roots of beans (phaseolus vulgaris) and trees (leucaena spp.). ... | 1994 | 8170393 |
| structure of lipid a component of rhizobium leguminosarum bv. phaseoli lipopolysaccharide. unique nonphosphorylated lipid a containing 2-amino-2-deoxygluconate, galacturonate, and glucosamine. | the structure of lipid a from the lipopolysaccharide of rhizobium leguminosarum bv. phaseoli (wild type strain ce3) was investigated by alkylation analysis, nuclear magnetic resonance spectroscopy, and electrospray and fast atom bombardment mass spectrometry of the de-o-acylated lipid a. the lipid a carbohydrate backbone was shown to be a trisaccharide containing galacturonic acid, glucosamine, and the unique sugar 2-amino-2-deoxygluconic acid, previously unreported in lipopolysaccharides. nucle ... | 1994 | 8182046 |
| isolation of a dna polymerase i (pola) mutant of rhizobium leguminosarum that has significantly reduced levels of an incq-group plasmid. | a population of tn5 mutagenized rhizobium leguminosarum cells was screened for mutants affected in protein secretion by introducing a plasmid carrying the erwinia chrysanthemi prtb gene and screening for mutants defective in secretion of the protease prtb. one such mutant (a301) also appeared to be defective in secretion of the r. leguminosarum nodulation protein nodo. genetic analysis showed that the defect in a301 was caused by the tn5 insertion. however the dna sequence adjacent to the site o ... | 1994 | 8190065 |
| infection of soybean and pea nodules by rhizobium spp. purine auxotrophs in the presence of 5-aminoimidazole-4-carboxamide riboside. | purine auxotrophs of various rhizobium species are symbiotically defective, usually unable to initiate or complete the infection process. earlier studies demonstrated that, in the rhizobium etli-bean symbiosis, infection by purine auxotrophs is partially restored by supplementation of the plant medium with 5-amino-imidazole-4-carboxamide (aica) riboside, the unphosphorylated form of the purine biosynthetic intermediate aicar. the addition of purine to the root environment does not have this effe ... | 1994 | 8195084 |
| nodulation protein nodl of rhizobium leguminosarum o-acetylates lipo-oligosaccharides, chitin fragments and n-acetylglucosamine in vitro. | upon induction of their nodulation genes, the root nodule-inducing rhizobium bacteria produce lipo-oligosaccharide signal molecules. all lipo-oligosaccharides identified from rhizobium leguminosarum bv. viciae carry an o-acetyl group at the c-6 position of the non-reducing terminal sugar, the presence of which is important for biological activity and host specificity. previously we showed that a functional nodl gene product is required for the presence of this o-acetyl moiety. the production of ... | 1994 | 8196551 |
| nucleotide sequence analysis of four genes, hupc, hupd, hupf and hupg, downstream of the hydrogenase structural genes in bradyrhizobium japonicum. | the nucleotide sequence of a 2.2 kb region downstream of the hydrogenase structural genes in bradyrhizobium japonicum was determined. four genes encoding predicted polypeptides of 27.8 (hupc), 21.4 (hupd), 10.6 (hupf) and 15.8 (hupg) kda were identified, of which the first three probably belong to the same operon as the hup structural genes, hups and hupl. hupc is homologous to the hydrophobic polypeptides with four potential transmembrane regions that are encoded by open reading frames followin ... | 1993 | 8230232 |
| proposal for rejection of agrobacterium tumefaciens and revised descriptions for the genus agrobacterium and for agrobacterium radiobacter and agrobacterium rhizogenes. | the 16s rrna sequences of seven representative agrobacterium strains, eight representative rhizobium strains, and the type strains of azorhizobium caulinodans and bradyrhizobium japonicum were determined. these strains included the type strains of agrobacterium tumefaciens, agrobacterium rhizogenes, agrobacterium radiobacter, agrobacterium vitis, agrobacterium rubi, rhizobium fredii, rhizobium galegae, rhizobium huakuii, rhizobium leguminosarum, rhizobium loti, rhizobium meliloti, and rhizobium ... | 1993 | 8240952 |
| genomic heterogeneity among french rhizobium strains isolated from phaseolus vulgaris l. | levels of dna relatedness between strains isolated from root nodules of phaseolus vulgaris and reference strains of different rhizobium species were determined by performing dna-dna hybridization experiments (s1 nuclease method). the nine strains examined were members of three genomic groups previously delineated by a restriction fragment length polymorphism analysis among strains isolated from p. vulgaris at different sites in france. in agreement with the results of the restriction fragment le ... | 1993 | 8240956 |
| identification of the sata gene encoding a streptogramin a acetyltransferase in enterococcus faecium bm4145. | enterococcus faecium bm4145, a clinical isolate from urine, was resistant to streptogramin group a antibiotics by inactivation. the strain harbored a plasmid containing a gene, sata, responsible for this resistance; this gene was cloned and sequenced. it encoded sata, a protein deduced to be 23,634 da in mass and homologous with a new family of chloramphenicol acetyltransferases described in agrobacterium tumefaciens, escherichia coli, pseudomonas aeruginosa, and staphylococcus aureus. the simil ... | 1993 | 8257133 |
| influence of growth conditions on production of capsular and extracellular polysaccharides by rhizobium leguminosarum. | the influence of growth rate and medium composition on exopolymer production by rhizobium leguminosarum was studied. when grown in medium containing 10 g/l mannitol and 1 g/l glutamic acid, rhizobium leguminosarum biovar trifolii ta-1 synthesized up to 2.0 g/l of extracellular polysaccharide (eps), and up to 1.6 g/l of capsular polysaccharide (cps). under non-growing cell conditions in medium without glutamic acid, cps synthesis by strain ta-1 could proceed to 2.1 g/l, while eps-production remai ... | 1993 | 8273998 |
| phospholipid and fatty acid compositions of rhizobium leguminosarum biovar trifolii anu843 in relation to flavone-activated psym nod gene expression. | the phospholipid and associated fatty acid compositions of the bacterial symbiont of clover, rhizobium leguminosarum biovar trifolii wild-type anu843, was analyzed by two-dimensional silica thin-layer chromatography, fast atom bombardment-mass spectrometry, flame-ionization detection gas-liquid chromatography and combined gas-liquid chromatography/mass spectrometry. the phospholipid composition included phosphatidylethanolamine (15%), n-methylphosphatidylethanolamine (47%), n,n-dimethylphosphati ... | 1993 | 8277828 |
| the survival of bacteria exposed to desiccation on surfaces associated with farm buildings. | the survival of 11 species of gram-negative and gram-positive bacteria was examined on different surfaces exposed to desiccation. there were large variations between species; pseudomonas spp. and rhizobium leguminosarum biovars survived for less than 2 d, whilst enterococcus spp. survived for more than 11 weeks. the type of surface on to which the bacteria were deposited affected survival, but with different effects between species. in addition the survival of spontaneous nalidixic acid-resistan ... | 1993 | 8294304 |
| the nodl and nodj proteins from rhizobium and bradyrhizobium strains are similar to capsular polysaccharide secretion proteins from gram-negative bacteria. | the nodl and nodj nodulation proteins have been described in different rhizobium and bradyrhizobium species. the nodlj genes belong to the nod regulon. other genes from this regulon are involved in the biosynthesis and modification of lipo-oligosaccharide molecule(s) which are morphogenic signals when acting on legume roots. it has been proposed that the nodl and nodj proteins belong to a bacterial inner membrane transport system of small molecules. nucleotide sequencing of mudll pr13 insertions ... | 1993 | 8316086 |
| molecular analysis of a microaerobically induced operon required for hydrogenase synthesis in rhizobium leguminosarum biovar viciae. | the nucleotide sequence (6138 bp) of a microaerobically inducible region (hupv/vi) from the rhizobium leguminosarum bv. viciae hydrogenase gene cluster has been determined. six genes, arranged as a single operon, were identified, and designated hypa, b, f, c, d and e based on the sequence similarities of all of them, except hypf, to genes from the hydrogenase pleiotropic operon (hyp) from escherichia coli. the gene products from hypbfcde were identified by in vivo expression analysis in e. coli, ... | 1993 | 8326860 |
| methoxylated fatty acids reported in rhizobium isolates arise from chemical alterations of common fatty acids upon acid-catalyzed transesterification procedures. | we obtained from a phospholipid extract of wild-type rhizobium leguminosarum bv. trifolii anu843 methoxylated fatty acids that had been previously reported as constitutive unusual rhizobium fatty acids. the use of deuterated reagents and subsequent gas-liquid chromatography-mass spectrometry analyses showed that these methoxylated fatty acid derivatives are the products of chemical alterations of common cyclopropane-containing and unsaturated fatty acids occurring during various acid-catalyzed t ... | 1993 | 8335647 |