Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| multicomponent transcriptional regulation at the complex promoter of the exopolysaccharide i biosynthetic operon of ralstonia solanacearum. | high-level transcription of eps, an operon encoding biosynthesis of an exopolysaccharide virulence factor of the phytopathogen ralstonia (pseudomonas) solanacearum, requires the products of at least seven regulatory genes (phca, phcb, xpsr, vsra-vsrd, and vsrb-vsrc), which are organized in three converging signal transduction cascades. because xpsr and the vsrb-vsrc two-component system are the most downstream cascade components required for activation of eps, we explored how these components co ... | 2000 | 11073909 |
| novel role for an hpt domain in stabilizing the phosphorylated state of a response regulator domain. | two-component regulatory systems that utilize a multistep phosphorelay mechanism often involve a histidine-containing phosphotransfer (hpt) domain. these hpt domains serve an essential role as histidine-phosphorylated protein intermediates during phosphoryl transfer from one response regulator domain to another. in saccharomyces cerevisiae, the ypd1 protein facilitates phosphoryl transfer from a hybrid sensor kinase, sln1, to two distinct response regulator proteins, ssk1 and skn7. because the p ... | 2000 | 11073911 |
| genetic analysis of calcium spiking responses in nodulation mutants of medicago truncatula. | the symbiotic interaction between medicago truncatula and sinorhizobium meliloti results in the formation of nitrogen-fixing nodules on the roots of the host plant. the early stages of nodule formation are induced by bacteria via lipochitooligosaccharide signals known as nod factors (nfs). these nfs are structurally specific for bacterium-host pairs and are sufficient to cause a range of early responses involved in the host developmental program. early events in the signal transduction of nfs ar ... | 2000 | 11078514 |
| dissection of nodulation signaling using pea mutants defective for calcium spiking induced by nod factors and chitin oligomers. | changes in intracellular calcium in pea root hairs responding to rhizobium leguminosarum bv. viciae nodulation (nod) factors were analyzed by using a microinjected calcium-sensitive fluorescent dye (dextran-linked oregon green). within 1-2 min after nod-factor addition, there was usually an increase in fluorescence, followed about 10 min later by spikes in fluorescence occurring at a rate of about one spike per minute. these spikes, corresponding to an increase in calcium of approximately 200 nm ... | 2000 | 11078515 |
| structure and sequence analysis of yersinia yada and moraxella uspas reveal a novel class of adhesins. | the non-fimbrial adhesins, yada of enteropathogenic yersinia species, and uspa1 and uspa2 of moraxella catarrhalis, are established pathogenicity factors. in electron micrographs, both surface proteins appear as distinct 'lollipop'-shaped structures forming a novel type of surface projection on the outer membranes. these structures, amino acid sequence analysis of these molecules and yada gene manipulation suggest a tripartite organization: an n-terminal oval head domain is followed by a putativ ... | 2000 | 11080146 |
| the acidic pin of ruva modulates holliday junction binding and processing by the ruvabc resolvasome. | holliday junctions are four-way branched dna structures formed during recombination, replication and repair. they are processed in escherichia coli by the ruva, ruvb and ruvc proteins. ruva targets the junction and facilitates loading of ruvb helicase and ruvc endonuclease to form complexes that catalyse junction branch migration (ruvab) and resolution (ruvabc). we investigated the role of ruva in these reactions and in particular the part played by the acidic pin located on its dna-binding surf ... | 2000 | 11080172 |
| cell surface expansion in polarly growing root hairs of medicago truncatula. | fluorescent microspheres were used as material markers to investigate the relative rates of cell surface expansion at the growing tips of medicago truncatula root hairs. from the analysis of tip shape and microsphere movements, we propose three characteristic zones of expansion in growing root hairs. the center of the apical dome is an area of 1- to 2- microm diameter with relatively constant curvature and high growth rate. distal to the apex is a more rapidly expanding region 1 to 2 microm in w ... | 2000 | 11080274 |
| localization of a nod factor-binding protein in legume roots and factors influencing its distribution and expression. | the roots of the legume dolichos biflorus contain a lectin/nucleotide phosphohydrolase (db-lnp) that binds to the nod factor signals produced by rhizobia that nodulate this plant. in this study we show that db-lnp is differentially distributed along the surface of the root axis in a pattern that correlates with the zone of nodulation of the root. db-lnp is present on the surface of young and emerging root hairs and redistributes to the tips of the root hairs in response to treatment of the roots ... | 2000 | 11080281 |
| oxygen regulation of a nodule-located carbonic anhydrase in alfalfa. | control of the permeability to oxygen is critical for the function of symbiotic nitrogen fixation in legume nodules. the inner cortex (ic) seems to be a primary site for this regulation. in alfalfa (medicago sativa) nodules, expression of the msca1 gene encoding a carbonic anhydrase (ca) was previously found to be restricted to the ic. we have now raised antibodies against recombinant msca1 protein and used them, together with antibodies raised against potato leaf ca, to demonstrate the presence ... | 2000 | 11080283 |
| how alfalfa root hairs discriminate between nod factors and oligochitin elicitors. | using ion-selective microelectrodes, the problem of how signals coming from symbiotic partners or from potential microbial intruders are distinguished was investigated on root hairs of alfalfa (medicago sativa). the nod factor, nodrm-iv(c16:2,s), was used to trigger the symbiotic signal and (glcnac)(8) was selected from (glcnac)(4-8), to elicit defense-related reactions. to both compounds, root hairs responded with initial transient depolarizations and alkalinizations, which were followed by a h ... | 2000 | 11080312 |
| molecular characterization of the sinorhizobium meliloti nlpd gene. | the sinorhizobium meliloti nlpd gene consists of 1,539 nucleotides and codes for 512 amino acids. expression of the nlpd gene as a histidine-tagged protein in escherichia coli resulted in the production of a 57-kda protein. the deduced polypeptide sequence of nlpd contains one unusual hexamer repeat (kvqrgq), one tetramer (tvtv) and two direct and inverted trimer repeats (kaa, aak). the n-terminal amino acid residues displayed similarity with signal peptides of secreted bacterial lipoproteins. m ... | 2000 | 11081798 |
| hemin-binding surface protein from bartonella quintana. | bartonella quintana, the agent of trench fever and a cause of endocarditis and bacillary angiomatosis in humans, has the highest reported in vitro hemin requirement for any bacterium. we determined that eight membrane-associated proteins from b. quintana bind hemin and that a approximately 25-kda protein (hbpa) was the dominant hemin-binding protein. like many outer membrane proteins, hbpa partitions to the detergent phase of a triton x-114 extract of the cell and is heat modifiable, displaying ... | 2000 | 11083791 |
| sequencing the sinorhizobium meliloti genome. | the sinorhizobium meliloti genome consists of three replicons. this bacterium forms an intricate symbiotic relationship with the roots of certain legumes and is considered as an agriculturally important nitrogen-fixer. a consortium of 6 european laboratories was organized to sequence its single chromosome (3.7 mb), whereas the other two elements (psyma 1.4 mb and psymb 1.7 mb) will be sequenced by other groups. | 2000 | 11092731 |
| molecular evolution of virulence in natural field strains of xanthomonas campestris pv. vesicatoria. | the avrbs2 avirulence gene of the bacterial plant pathogen xanthomonas campestris pv. vesicatoria triggers disease resistance in pepper plants containing the bs2 resistance gene and contributes to bacterial virulence on susceptible host plants. we studied the effects of the pepper bs2 gene on the evolution of avrbs2 by characterizing the molecular basis for virulence of 20 x. campestris pv. vesicatoria field strains that were isolated from disease spots on previously resistant bs2 pepper plants. ... | 2000 | 11092868 |
| characterization of a major cluster of nif, fix, and associated genes in a sugarcane endophyte, acetobacter diazotrophicus. | a major 30.5-kb cluster of nif and associated genes of acetobacter diazotrophicus (syn. gluconacetobacter diazotrophicus), a nitrogen-fixing endophyte of sugarcane, was sequenced and analyzed. this cluster represents the largest assembly of contiguous nif-fix and associated genes so far characterized in any diazotrophic bacterial species. northern blots and promoter sequence analysis indicated that the genes are organized into eight transcriptional units. the overall arrangement of genes is most ... | 2000 | 11092875 |
| coliform bacteria and nitrogen fixation in pulp and paper mill effluent treatment systems. | the majority of pulp and paper mills now biotreat their combined effluents using activated sludge. on the assumption that their wood-based effluents have negligible fixed n, and that activated-sludge microorganisms will not fix significant n, these mills routinely spend large amounts adding ammonia or urea to their aeration tanks (bioreactors) to permit normal biomass growth. n(2) fixation in seven eastern canadian pulp and paper mill effluent treatment systems was analyzed using acetylene reduc ... | 2000 | 11097883 |
| behavioral responses of rhodobacter sphaeroides to linear gradients of the nutrients succinate and acetate. | rhodobacter sphaeroides cells were tethered by their flagella and subjected to increasing and decreasing nutrient gradients. using motion analysis, changes in flagellar motor rotation were measured and the responses of the cells to the chemotactic gradients were determined. the steepness and concentration ranges of increasing and decreasing gradients were varied, and the bacterial responses were measured. this allowed the limits of gradients that would invoke changes in flagellar behavior to be ... | 2000 | 11097888 |
| control of expression of divergent pseudomonas putida put promoters for proline catabolism. | pseudomonas putida kt2440 uses proline as the sole c and n source. utilization of this amino acid involves its uptake, which is mediated by the putp protein, and its conversion into glutamate, mediated by the puta protein. sequence analysis revealed that the puta and putp genes are transcribed divergently. expression from the putp and puta genes was analyzed at the mrna level in different host backgrounds in the absence and presence of proline. expression from the put promoters was induced by pr ... | 2000 | 11097893 |
| fatty acid competition as a mechanism by which enterobacter cloacae suppresses pythium ultimum sporangium germination and damping-off. | interactions between plant-associated microorganisms play important roles in suppressing plant diseases and enhancing plant growth and development. while competition between plant-associated bacteria and plant pathogens has long been thought to be an important means of suppressing plant diseases microbiologically, unequivocal evidence supporting such a mechanism has been lacking. we present evidence here that competition for plant-derived unsaturated long-chain fatty acids between the biological ... | 2000 | 11097912 |
| a homologue of the tryptophan-rich sensory protein tspo and fixl regulate a novel nutrient deprivation-induced sinorhizobium meliloti locus. | a nutrient deprivation-induced locus in sinorhizobium meliloti strain 1021 was identified by use of a tn5-luxab reporter gene transposon. the tagged locus is comprised of two open reading frames (orfs) designated ndia and ndib for nutrient deprivation-induced genes a and b. comparison of the deduced amino acid sequences of both ndia and ndib to the protein databases failed to reveal similarity to any known genes. the expression of the ndi locus was found to be induced by carbon and nitrogen depr ... | 2000 | 11097914 |
| detection on surfaces and in caco-2 cells of campylobacter jejuni cells transformed with new gfp, yfp, and cfp marker plasmids. | we have developed two sets of campylobacter shuttle vectors containing either the gfp (green fluorescent protein), yfp (yellow fluorescent protein), or cfp (cyan fluorescent protein) reporter gene. in one set, the reporter gene is fused to a consensus campylobacter promoter sequence (p(c)). the other set contains a puc18 multicloning site upstream of the reporter gene, allowing the construction of transcriptional fusions using known promoters or random genomic fragments. c. jejuni cells transfor ... | 2000 | 11097924 |
| photosynthetic bradyrhizobia are natural endophytes of the african wild rice oryza breviligulata. | we investigated the presence of endophytic rhizobia within the roots of the wetland wild rice oryza breviligulata, which is the ancestor of the african cultivated rice oryza glaberrima. this primitive rice species grows in the same wetland sites as aeschynomene sensitiva, an aquatic stem-nodulated legume associated with photosynthetic strains of bradyrhizobium. twenty endophytic and aquatic isolates were obtained at three different sites in west africa (senegal and guinea) from nodal roots of o. ... | 2000 | 11097925 |
| biogeography and degree of endemicity of fluorescent pseudomonas strains in soil. | fluorescent pseudomonas strains were isolated from 38 undisturbed pristine soil samples from 10 sites on four continents. a total of 248 isolates were confirmed as pseudomonas sensu stricto by fluorescent pigment production and group-specific 16s ribosomal dna (rdna) primers. these isolates were analyzed by three molecular typing methods with different levels of resolution: 16s rdna restriction analysis (ardra), 16s-23s rdna intergenic spacer-restriction fragment length polymorphism (its-rflp) a ... | 2000 | 11097926 |
| the bradyrhizobium japonicum proline biosynthesis gene proc is essential for symbiosis. | plant host-derived proline is proposed to serve as an energy source for rhizobia in the rhizosphere and in symbiotic root nodules. the bradyrhizobium japonicum proc gene was isolated, and a proc mutant strain that behaved as a strict proline auxotroph in culture was constructed. the proc strain elicited undeveloped nodules on soybeans that lacked nitrogen fixation activity and plant hemoglobin. we conclude that the proc gene is essential for symbiosis and suggest that the mutant does not obtain ... | 2000 | 11097929 |
| translational and structural requirements of the early nodulin gene enod40, a short-open reading frame-containing rna, for elicitation of a cell-specific growth response in the alfalfa root cortex. | a diversity of mrnas containing only short open reading frames (sorf-rnas; encoding less than 30 amino acids) have been shown to be induced in growth and differentiation processes. the early nodulin gene enod40, coding for a 0.7-kb sorf-rna, is expressed in the nodule primordium developing in the root cortex of leguminous plants after infection by symbiotic bacteria. ballistic microtargeting of this gene into medicago roots induced division of cortical cells. translation of two sorfs (i and ii, ... | 2001 | 11113209 |
| the chvh locus of agrobacterium encodes a homologue of an elongation factor involved in protein synthesis. | the virulence of agrobacterium tumefaciens depends on both chromosome- and ti plasmid-encoded gene products. in this study, we characterize a chromosomal locus, chvh, previously identified by tnphoa mutagenesis and shown to be required for tumor formation. through dna sequencing and comparison of the sequence with identified sequences in the database, we show that this locus encodes a protein similar in sequence to elongation factor p, a protein thought to be involved in peptide bond synthesis i ... | 2001 | 11114898 |
| identification of residues involved in catalytic activity of the inverting glycosyl transferase wbbe from salmonella enterica serovar borreze. | synthesis of the o:54 o antigen of salmonella enterica is initiated by the nonprocessive glycosyl transferase wbbe, assigned to family 2 of the glycosyl transferase enzymes (gt2). gt2 enzymes possess a characteristic n-terminal domain, domain a. based on structural data from the gt2 representative spsa (s. j. charnock and g. j. davies, biochemistry 38:6380-6385, 1999), this domain is responsible for nucleotide binding. it possesses two invariant asp residues, the first forming a hydrogen bond to ... | 2001 | 11114903 |
| rubrerythrin and rubredoxin oxidoreductase in desulfovibrio vulgaris: a novel oxidative stress protection system. | evidence is presented for an alternative to the superoxide dismutase (sod)-catalase oxidative stress defense system in desulfovibrio vulgaris (strain hildenborough). this alternative system consists of the nonheme iron proteins, rubrerythrin (rbr) and rubredoxin oxidoreductase (rbo), the product of the rbo gene (also called desulfoferrodoxin). a deltarbo strain of d. vulgaris was found to be more sensitive to internal superoxide exposure than was the wild type. unlike rbo, expression of plasmid- ... | 2001 | 11114906 |
| methylotrophic methylobacterium bacteria nodulate and fix nitrogen in symbiosis with legumes. | rhizobia described so far belong to three distinct phylogenetic branches within the alpha-2 subclass of proteobacteria. here we report the discovery of a fourth rhizobial branch involving bacteria of the methylobacterium genus. rhizobia isolated from crotalaria legumes were assigned to a new species, "methylobacterium nodulans," within the methylobacterium genus on the basis of 16s ribosomal dna analyses. we demonstrated that these rhizobia facultatively grow on methanol, which is a characterist ... | 2001 | 11114919 |
| critical protective role of bacterial superoxide dismutase in rhizobium-legume symbiosis. | in nitrogen-poor soils, rhizobia elicit nodule formation on legume roots, within which they differentiate into bacteroids that fix atmospheric nitrogen. protection against reactive oxygen species (ros) was anticipated to play an important role in rhizobium-legume symbiosis because nitrogenase is extremely oxygen sensitive. we deleted the soda gene encoding the sole cytoplasmic superoxide dismutase (sod) of sinorhizobium meliloti. the resulting mutant, deficient in superoxide dismutase, grew almo ... | 2000 | 11115110 |
| tmrdb (tmrna database). | the tmrna database (tmrdb) is maintained at the university of texas health science center at tyler, texas, and accessible on the world wide web at the url http://psyche.uthct.edu/dbs/tmrdb/tmrdb.++ +html. mirror sites are located at auburn university, auburn, alabama (http://www.ag.auburn.edu/mirror/tmrdb/) and the institute of biological sciences, aarhus, denmark (http://www.bioinf.au. dk/tmrdb/). the tmrdb provides information and citation links about tmrna, a molecule that combines functions ... | 2001 | 11125081 |
| evidence for a functional similarity between the two-component regulatory systems regsr, actsr, and regba (prrba) in alpha-proteobacteria. | the symbiotic bacteria bradyrhizobium japonicum and sinorhizobium meliloti, and the purple photosynthetic bacteria rhodobacter capsulatus, rhodovulum sulfidophilum, roseobacter denitrificans and rhodobacter sphaeroides possess homologous two-component regulatory systems, namely regsr, actsr, regba and prrba. the respective response regulators of these bacteria control expression of different regulons that are involved in n2 fixation, co2 fixation, photosynthesis or acid tolerance. we therefore a ... | 2000 | 11131020 |
| novel tellurite-amended media and specific chromosomal and ti plasmid probes for direct analysis of soil populations of agrobacterium biovars 1 and 2. | ecology and biodiversity studies of agrobacterium spp. require tools such as selective media and dna probes. tellurite was tested as a selective agent and a supplement of previously described media for agrobacteria. the known biodiversity within the genus was taken into account when the selectivity of k(2)teo(3) was analyzed and its potential for isolating agrobacterium spp. directly from soil was evaluated. a k(2)teo(3) concentration of 60 ppm was found to favor the growth of agrobacteria and r ... | 2001 | 11133429 |
| direct cloning from enrichment cultures, a reliable strategy for isolation of complete operons and genes from microbial consortia. | enrichment cultures of microbial consortia enable the diverse metabolic and catabolic activities of these populations to be studied on a molecular level and to be explored as potential sources for biotechnology processes. we have used a combined approach of enrichment culture and direct cloning to construct cosmid libraries with large (>30-kb) inserts from microbial consortia. enrichment cultures were inoculated with samples from five environments, and high amounts of avidin were added to the cu ... | 2001 | 11133432 |
| non-growth-associated demethylation of dimethylsulfoniopropionate by (homo)acetogenic bacteria. | the demethylation of the algal osmolyte dimethylsulfoniopropionate (dmsp) to methylthiopropionate (mtpa) by (homo)acetogenic bacteria was studied. five eubacterium limosum strains (including the type strain), sporomusa ovata dsm 2662(t), sporomusa sphaeroides dsm 2875(t), and acetobacterium woodii dsm 1030(t) were shown to demethylate dmsp stoichiometrically to mtpa. the (homo)acetogenic fermentation based on this demethylation did not result in any significant increase in biomass. the analogous ... | 2001 | 11133459 |
| small-subunit rrna genotyping of rhizobia nodulating australian acacia spp. | the structure of rhizobial communities nodulating acacia in southeastern australia from south queensland to tasmania was investigated by a molecular approach. a total of 118 isolates from nodule samples from 13 different acacia species collected at 44 sites were characterized by small-subunit (ssu) ribosomal dna (rdna) pcr-restriction fragment length polymorphism analysis. nine rhizobial genomospecies were identified, and these taxa corresponded to previously described genomospecies (b. lafay an ... | 2001 | 11133471 |
| identification of the nik gene cluster of brucella suis: regulation and contribution to urease activity. | analysis of a brucella suis 1330 gene fused to a gfp reporter, and identified as being induced in j774 murine macrophage-like cells, allowed the isolation of a gene homologous to nika, the first gene of the escherichia coli operon encoding the specific transport system for nickel. dna sequence analysis of the corresponding b. suis nik locus showed that it was highly similar to that of e. coli except for localization of the nikr regulatory gene, which lies upstream from the structural nikabcde ge ... | 2001 | 11133934 |
| the gdhb gene of pseudomonas aeruginosa encodes an arginine-inducible nad(+)-dependent glutamate dehydrogenase which is subject to allosteric regulation. | the nad(+)-dependent glutamate dehydrogenase (nad-gdh) from pseudomonas aeruginosa pao1 was purified, and its amino-terminal amino acid sequence was determined. this sequence information was used in identifying and cloning the encoding gdhb gene and its flanking regions. the molecular mass predicted from the derived sequence for the encoded nad-gdh was 182.6 kda, in close agreement with that determined from sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme (180 kda ... | 2001 | 11133942 |
| genetic and biochemical analyses of bvga interaction with the secondary binding region of the fha promoter of bordetella pertussis. | the bvga-bvgs two-component signal transduction system regulates expression of virulence factors in bordetella pertussis. the bvga response regulator activates transcription by binding to target promoters, which include those for the genes encoding filamentous hemagglutinin (fha) and pertussis toxin (ptx). we have previously shown that at both promoters the phosphorylated form of bvga binds multiple high- and low-affinity sites. specifically, at the fha promoter, we proposed that there may be hi ... | 2001 | 11133947 |
| ihfa gene of the bacterium myxococcus xanthus and its role in activation of carotenoid genes by blue light. | myxococcus xanthus responds to blue light by producing carotenoids. several regulatory genes are known that participate in the light action mechanism, which leads to the transcriptional activation of the carotenoid genes. we had already reported the isolation of a carotenoid-less, tn5-induced strain (mr508), whose mutant site was unlinked to the indicated regulatory genes. here, we show that omegamr508::tn5 affects all known light-inducible promoters in different ways. it blocks the activation o ... | 2001 | 11133949 |
| nag genes of ralstonia (formerly pseudomonas) sp. strain u2 encoding enzymes for gentisate catabolism. | ralstonia sp. strain u2 metabolizes naphthalene via gentisate to central metabolites. we have cloned and sequenced a 21.6-kb region spanning the nag genes. upstream of the pathway genes are nagy, homologous to chemotaxis proteins, and nagr, a regulatory gene of the lysr family. divergently transcribed from nagr are the genes for conversion of naphthalene to gentisate (nagaaghabacadbfcqed) (s. l. fuenmayor, m. wild, a. l. boyes, and p. a. williams, j. bacteriol. 180:2522-2530, 1998), which except ... | 2001 | 11133965 |
| temporal regulation of genes encoding the flagellar proximal rod in caulobacter crescentus. | the gram-negative bacterium caulobacter crescentus has a life cycle that includes two distinct and separable developmental stages, a motile swarmer phase and a sessile stalked phase. the cell cycle-controlled biogenesis of the single polar flagellum of the swarmer cell is the best-studied aspect of this developmental program. the flagellar regulon is arranged into a rigid trans-acting hierarchy of gene expression in which successful expression of early genes is required for the expression of gen ... | 2001 | 11133968 |
| vertical transmission of biosynthetic plasmids in aphid endosymbionts (buchnera). | this study tested for horizontal transfer of plasmids among buchnera aphidicola strains associated with ecologically and phylogenetically related aphid hosts (uroleucon species). phylogenetic congruence of buchnera plasmid (trpeg and leuabc) and chromosomal (dnan and trpb) genes supports strictly vertical long-term transmission of plasmids, which persist due to their contributions to host nutrition rather than capacity for infectious transfer. synonymous divergences indicate elevated mutation on ... | 2001 | 11133977 |
| limited genetic diversity of brucella spp. | multilocus enzyme electrophoresis (mlee) of 99 brucella isolates, including the type strains from all recognized species, revealed a very limited genetic diversity and supports the proposal of a monospecific genus. in mlee-derived dendrograms, brucella abortus and a marine brucella sp. grouped into a single electrophoretic type related to brucella neotomae and brucella ovis. brucella suis and brucella canis formed another cluster linked to brucella melitensis and related to rhizobium tropici. th ... | 2001 | 11136777 |
| purification, stability, and mineralization of 3-hydroxy-2- formylbenzothiophene, a metabolite of dibenzothiophene. | 3-hydroxy-2-formylbenzothiophene (hfbt) is a metabolite found in many bacterial cultures that degrade dibenzothiophene (dbt) via the kodama pathway. the fate of hfbt in cultures and in the environment is unknown. in this study, hfbt was produced by a dbt-degrading bacterium and purified by sublimation. when stored in organic solvent or as a crystal, the hfbt slowly decomposed, yielding colored products. two of these were identified as thioindigo and cis-thioindigo. the supernatant of the dbt-deg ... | 2001 | 11157249 |
| characterization of acetic acid bacteria in traditional acetic acid fermentation of rice vinegar (komesu) and unpolished rice vinegar (kurosu) produced in japan. | bacterial strains were isolated from samples of japanese rice vinegar (komesu) and unpolished rice vinegar (kurosu) fermented by the traditional static method. fermentations have never been inoculated with a pure culture since they were started in 1907. a total of 178 isolates were divided into groups a and b on the basis of enterobacterial repetitive intergenic consensus-pcr and random amplified polymorphic dna fingerprinting analyses. the 16s ribosomal dna sequences of strains belonging to eac ... | 2001 | 11157275 |
| synthesis of a low-molecular-weight form of exopolysaccharide by bradyrhizobium japonicum usda 110. | a novel extracellular low-molecular-weight polysaccharide was detected as a contaminant within extracellular cyclic beta-1,6-beta-1,3-glucan preparations from bradyrhizobium japonicum usda 110 cultures. compositional analysis, methylation analysis, and nuclear magnetic resonance analysis revealed that this low-molecular-weight polysaccharide was composed of the same pentasaccharide repeating unit previously described for the high-molecular-weight form of the exopolysaccharide (eps) synthesized b ... | 2001 | 11157281 |
| genetic characterization of a sinorhizobium meliloti chromosomal region in lipopolysaccharide biosynthesis. | the genetic characterization of a 5.5-kb chromosomal region of sinorhizobium meliloti 2011 that contains lpsb, a gene required for the normal development of symbiosis with medicago spp., is presented. the nucleotide sequence of this dna fragment revealed the presence of six genes: grea and lpsb, transcribed in the forward direction; and lpse, lpsd, lpsc, and lrp, transcribed in the reverse direction. except for lpsb, none of the lps genes were relevant for nodulation and nitrogen fixation. analy ... | 2001 | 11157937 |
| cloning of the soda gene from corynebacterium melassecola and role of superoxide dismutase in cellular viability. | the soda gene encoding the corynebacterium melassecola manganese-cofactored superoxide dismutase (sod) has been cloned in escherichia coli and sequenced. the gene is transcribed monocistronically; the predicted polypeptide is 200 amino acids long and associates in a homotetrameric, manganese-dependent form, able to complement an sod-deficient e. coli mutant. a second open reading frame, coding for a putative 217-amino-acid protein with high homology to peptide methionine sulfoxide reductases fro ... | 2001 | 11157941 |
| one of two hemn genes in bradyrhizobium japonicum is functional during anaerobic growth and in symbiosis. | previously, we screened the symbiotic gene region of the bradyrhizobium japonicum chromosome for new nifa-dependent genes by competitive dna-rna hybridization (a. nienaber, a. huber, m. göttfert, h. hennecke, and h. m. fischer, j. bacteriol. 182:1472-1480, 2000). here we report more details on one of the genes identified, a hemn-like gene (now called hemn(1)) whose product exhibits significant similarity to oxygen-independent coproporphyrinogen iii dehydrogenases involved in heme biosynthesis in ... | 2001 | 11157943 |
| potential symbiosis-specific genes uncovered by sequencing a 410-kilobase dna region of the bradyrhizobium japonicum chromosome. | the physical and genetic map of the bradyrhizobium japonicum chromosome revealed that nitrogen fixation and nodulation genes are clustered. because of the complex interactions between the bacterium and the plant, we expected this chromosomal sector to contain additional genes that are involved in the maintenance of an efficient symbiosis. therefore, we determined the nucleotide sequence of a 410-kb region. the overall g+c nucleotide content was 59.1%. using a minimum gene length of 150 nucleotid ... | 2001 | 11157954 |
| influence of the nucleoid on placement of ftsz and mine rings in escherichia coli. | we previously presented evidence that replicating but unsegregated nucleoids, along with the min system, act as topological inhibitors to restrict assembly of the ftsz ring (z ring) to discrete sites in the cell. to test if nonreplicating nucleoids have similar exclusion effects, we examined z rings in dnaa (temperature sensitive) mutants. z rings were excluded from centrally localized nucleoids and were often observed at nucleoid edges. cells with nonreplicating nucleoids formed filaments, some ... | 2001 | 11157955 |
| gene discovery through genomic sequencing of brucella abortus. | brucella abortus is the etiological agent of brucellosis, a disease that affects bovines and human. we generated dna random sequences from the genome of b. abortus strain 2308 in order to characterize molecular targets that might be useful for developing immunological or chemotherapeutic strategies against this pathogen. the partial sequencing of 1,899 clones allowed the identification of 1,199 genomic sequence surveys (gsss) with high homology (blast expect value < 10(-5)) to sequences deposite ... | 2001 | 11159979 |
| identification of legionella pneumophila genes important for infection of amoebas by signature-tagged mutagenesis. | legionella pneumophila is a facultative intracellular gram-negative rod that causes pneumonia in humans. free-living amoebas are thought to serve as a reservoir for legionella infections. signature-tagged mutagenesis was employed to identify legionella pneumophila genes necessary for survival in the amoeba acanthamoeba castellanii. six mutant strains were defective in assays of invasion and intracellular growth. four mutants also exhibited invasion and replication defects in hartmannella vermifo ... | 2001 | 11159993 |
| control of hema expression in rhodobacter sphaeroides 2.4.1: effect of a transposon insertion in the hbda gene. | the common precursor to all tetrapyrroles is 5-aminolevulinic acid (ala), and in rhodobacter sphaeroides its formation occurs via the shemin pathway. ala synthase activity is encoded by two differentially regulated genes in r. sphaeroides 2.4.1: hema and hemt. in our investigations of hema regulation, we applied transposon mutagenesis under aerobic conditions, followed by a selection that identified transposon insertion mutants in which hema expression is elevated. one of these mutants has been ... | 2001 | 11160087 |
| the hook gene (flge) is expressed from the flgbcdef operon in rhodobacter sphaeroides: study of an flge mutant. | in this work we identified the flge gene encoding the flagellar hook protein from rhodobacter sphaeroides. our results show that this gene is part of a flagellar cluster that includes the genes flgb, flgc, flgd, flge, and flgf. two different types of mutants in the flge gene were isolated, and both showed a fla(-) phenotype, indicating the functionality of this sequence. complementation studies of these mutant strains suggest that flge is included in a single transcriptional unit that starts in ... | 2001 | 11160099 |
| vpsr, a member of the response regulators of the two-component regulatory systems, is required for expression of vps biosynthesis genes and eps(etr)-associated phenotypes in vibrio cholerae o1 el tor. | the rugose colonial variant of vibrio cholerae o1 el tor produces an exopolysaccharide (eps(etr)) that enables the organism to form a biofilm and to resist oxidative stress and the bactericidal action of chlorine. transposon mutagenesis of the rugose variant led to the identification of vpsr, which codes for a homologue of the ntrc subclass of response regulators. targeted disruption of vpsr in the rugose colony genetic background yielded a nonreverting smooth-colony morphotype that produced no ... | 2001 | 11160103 |
| characterization of the catalytic activities of the phoq histidine protein kinase of salmonella enterica serovar typhimurium. | studies of escherichia coli membranes that were highly enriched in the salmonella enterica serovar typhimurium phoq protein showed that the presence of atp and divalent cations such as mg2+, mn2+, ca2+, or ba2+ resulted in phoq autophosphorylation. however, when mg2) or mn2+ was present at concentrations higher than 0.1 mm, the kinetics of phoq autophosphorylation were strongly biphasic, with a rapid autophosphorylation phase followed by a slower dephosphorylation phase. a fusion protein lacking ... | 2001 | 11160113 |
| conserved gene cluster at replication origins of the alpha-proteobacteria caulobacter crescentus and rickettsia prowazekii. | a 30-kb region surrounding the replication origin in caulobacter crescentus was analyzed. comparison to the genome sequence of another alpha-proteobacterium, rickettsia prowazekii, revealed a conserved cluster of genes (rp001, heme, hemh, and rp883) that overlaps the established origin of replication in c. crescentus and the putative origin of replication in r. prowazekii. the genes flanking this cluster differ between these two organisms. we therefore propose that this conserved gene cluster ca ... | 2001 | 11160121 |
| genetic snapshots of the rhizobium species ngr234 genome. | in nitrate-poor soils, many leguminous plants form nitrogen-fixing symbioses with members of the bacterial family rhizobiaceae. we selected rhizobium sp. ngr234 for its exceptionally broad host range, which includes more than i 12 genera of legumes. unlike the genome of bradyrhizobium japonicum, which is composed of a single 8.7 mb chromosome, that of ngr234 is partitioned into three replicons: a chromosome of about 3.5 mb, a megaplasmid of more than 2 mb (pngr234b) and pngr234a, a 536,165 bp pl ... | 2000 | 11178268 |
| an active role for a structured b-linker in effector control of the sigma54-dependent regulator dmpr. | the activities of many prokaryotic sigma54-dependent transcriptional activators are controlled by the n-terminal a-domain of the protein, which is linked to the central transcriptional activation domain via a short b-linker. it used to be thought that these b-linkers simply serve as flexible tethers. here we show that the b-linker of the aromatic-responsive regulator dmpr and many other regulators of the family contain signature heptad repeats with regularly spaced hydrophobic amino acids. mutan ... | 2001 | 11179226 |
| peroxide sensors for the fission yeast stress-activated mitogen-activated protein kinase pathway. | the schizosaccharomyces pombe stress-activated sty1p/spc1p mitogen-activated protein (map) kinase regulates gene expression through the atf1p and pap1p transcription factors, homologs of human atf2 and c-jun, respectively. mcs4p, a response regulator protein, acts upstream of sty1p by binding the wak1p/wis4p map kinase kinase kinase. we show that phosphorylation of mcs4p on a conserved aspartic acid residue is required for activation of sty1p only in response to peroxide stress. mcs4p acts in a ... | 2001 | 11179424 |
| early symbiotic responses induced by sinorhizobium meliloti iivc mutants in alfalfa. | a mutation in the ilvc gene of sinorhizobium meliloti 1021 determines a symbiotically defective phenotype. ilvc mutants obtained from different s. meliloti wild-type strains are able to induce root hair deformation on alfalfa roots and show variable activation of the common nodulation genes nodabc. all of these mutants are noninfective. the presence of extra copies of nodd3-syrm in an ilvc- background does not promote nod expression but allows the detection of low levels of nod factor production ... | 2001 | 11194871 |
| oxidative burst in alfalfa-sinorhizobium meliloti symbiotic interaction. | reactive oxygen species are produced as an early event in plant defense response against avirulent pathogens. we show here that alfalfa responds to infection with sinorhizobium meliloti by production of superoxide and hydrogen peroxide. this similarity in the early response to infection by pathogenic and symbiotic bacteria addresses the question of which mechanism rhizobia use to counteract the plant defense response. | 2001 | 11194876 |
| two-component sensor required for normal symbiotic colonization of euprymna scolopes by vibrio fischeri. | the light organ of the squid euprymna scolopes is specifically colonized to a high density by the marine bacterium vibrio fischeri. to date, only a few factors contributing to the specificity of this symbiosis have been identified. using a genetic screen for random transposon mutants defective in initiating the symbiotic association or in colonizing the light organ to high density, we identified a mutant of v. fischeri that exhibited an apparent defect in symbiosis initiation. this mutant was no ... | 2001 | 11208780 |
| enhanced symbiotic performance by rhizobium tropici glycogen synthase mutants. | we isolated a tn5-induced rhizobium tropici mutant that has enhanced capacity to oxidize n,n-dimethyl-p-phenylendiamine (dmpd) and therefore has enhanced respiration via cytochrome oxidase. the mutant had increased levels of the cytochromes c(1) and cycm and a small increase in the amount of cytochrome aa(3). in plant tests, the mutant increased the dry weight of phaseolus vulgaris plants by 20 to 38% compared with the control strain, thus showing significantly enhanced symbiotic performance. th ... | 2001 | 11208782 |
| effects exerted by transcriptional regulator pcau from acinetobacter sp. strain adp1. | protocatechuate degradation is accomplished in a multistep inducible catabolic pathway in acinetobacter sp. strain adp1. the induction is brought about by the transcriptional regulator pcau in concert with the inducer protocatechuate. pcau, a member of the new iclr family of transcriptional regulators, was shown to play a role in the activation of transcription at the promoter for the structural pca genes, leaving open the participation of additional activators. in this work we show that there i ... | 2001 | 11208784 |
| evidence of multiple regulatory functions for the ptsn (iia(ntr)) protein of pseudomonas putida. | the ptsn gene of pseudomonas putida encodes iia(ntr), a protein of the phosphoenol pyruvate:sugar phosphotransferase (pts) system which is required for the c source inhibition of the sigma(54)-dependent promoter pu of the tol (toluate degradation) plasmid pww0. using two-dimensional gel electrophoresis, we have examined the effect of ptsn disruption on the general expression pattern of p. putida. to this end, cells were grown in the presence or absence of glucose, and a 1,117-spot subset of the ... | 2001 | 11208802 |
| connection between poly-beta-hydroxybutyrate biosynthesis and growth on c(1) and c(2) compounds in the methylotroph methylobacterium extorquens am1. | several dna regions containing genes involved in poly-beta-hydroxybutyrate (phb) biosynthesis and degradation and also in fatty acid degradation were identified from genomic sequence data and have been characterized in the serine cycle facultative methylotroph methylobacterium extorquens am1. genes involved in phb biosynthesis include those encoding beta-ketothiolase (phaa), nadph-linked acetoacetyl coenzyme a (acetyl-coa) reductase (phab), and phb synthase (phac). phaa and phab are closely link ... | 2001 | 11208803 |
| analysis of the pmsceab gene cluster involved in biosynthesis of salicylic acid and the siderophore pseudomonine in the biocontrol strain pseudomonas fluorescens wcs374. | mutants of pseudomonas fluorescens wcs374 defective in biosynthesis of the fluorescent siderophore pseudobactin still display siderophore activity, indicating the production of a second siderophore. a recombinant cosmid clone (pmb374-07) of a wcs374 gene library harboring loci necessary for the biosynthesis of salicylic acid (sa) and this second siderophore pseudomonine was isolated. the salicylate biosynthesis region of wcs374 was localized in a 5-kb ecori fragment of pmb374-07. the sa and pseu ... | 2001 | 11222588 |
| involvement of rese phosphatase activity in down-regulation of resd-controlled genes in bacillus subtilis during aerobic growth. | the resd-rese signal transduction system is required for aerobic and anaerobic respiration in bacillus subtilis. the histidine sensor kinase rese, by functioning as a kinase and a phosphatase for the cognate response regulator resd, controls the level of phosphorylated resd. a high level of phosphorylated resd is postulated to cause a dramatic increase in transcription of resde-controlled genes under anaerobic conditions. a mutant rese, which retains autophosphorylation and resd phosphorylation ... | 2001 | 11222591 |
| symbiotic plasmid rearrangement in rhizobium leguminosarum bv. viciae vf39sm. | a rearrangement between the symbiotic plasmid (prlevf39d) and a nonsymbiotic plasmid (prlevf39b) in rhizobium leguminosarum bv. viciae vf39 was observed. the rearranged derivative showed the same plasmid profile as its parent strain, but hybridization to nod, fix, and nif genes indicated that most of the symbiotic genes were now present on a plasmid corresponding in size to prlevf39b instead of prlevf39d. on the other hand, some dna fragments originating from prlevf39b now hybridized to the plas ... | 2001 | 11222618 |
| in vitro roles of invariant helix-turn-helix motif residue r383 in sigma(54) (sigma(n)). | in vitro dna-binding and transcription properties of sigma(54) proteins with the invariant arg383 in the putative helix-turn-helix motif of the dna-binding domain substituted by lysine or alanine are described. we show that r383 contributes to maintaining stable holoenzyme-promoter complexes in which limited dna opening downstream of the -12 gc element has occurred. unlike wild-type sigma(54), holoenzymes assembled with the r383a or r383k mutants could not form activator-independent, heparin-sta ... | 2001 | 11222766 |
| phylogenetic relationships among group ii intron orfs. | group ii introns are widely believed to have been ancestors of spliceosomal introns, yet little is known about their own evolutionary history. in order to address the evolution of mobile group ii introns, we have compiled 71 open reading frames (orfs) related to group ii intron reverse transcriptases and subjected their derived amino acid sequences to phylogenetic analysis. the phylogenetic tree was rooted with reverse transcriptases (rts) of non-long terminal repeat retroelements, and the infer ... | 2001 | 11222775 |
| the effect of the agrobacterium tumefaciens attr mutation on attachment and root colonization differs between legumes and other dicots. | infections of wound sites on dicot plants by agrobacterium tumefaciens result in the formation of crown gall tumors. an early step in tumor formation is bacterial attachment to the plant cells. attr mutants failed to attach to wound sites of both legumes and nonlegumes and were avirulent on both groups of plants. attr mutants also failed to attach to the root epidermis and root hairs of nonlegumes and had a markedly reduced ability to colonize the roots of these plants. however, attr mutants wer ... | 2001 | 11229893 |
| acyl-homoserine lactone production is more common among plant-associated pseudomonas spp. than among soilborne pseudomonas spp. | a total of 137 soilborne and plant-associated bacterial strains belonging to different pseudomonas species were tested for their ability to synthesize n-acyl-homoserine lactones (nahl). fifty-four strains synthesized nahl. interestingly, nahl production appears to be more common among plant-associated than among soilborne pseudomonas spp. indeed, 40% of the analyzed pseudomonas syringae strains produced nahl which were identified most often as the short-chain nahl, n-hexanoyl-l-homoserine lacton ... | 2001 | 11229911 |
| recovery and analysis of formyltetrahydrofolate synthetase gene sequences from natural populations of acetogenic bacteria. | primers for pcr amplification of partial (1,102 of 1,680 bp) formyltetrahydrofolate synthetase (fthfs) gene sequences were developed and tested. partial fthfs sequences were successfully amplified from dna from pure cultures of known acetogens, from other fthfs-producing organisms, from the roots of the smooth cordgrass, spartina alterniflora, and from fresh horse manure. the amplimers recovered were cloned, their nucleotide sequences were determined, and their translated amino acid sequences we ... | 2001 | 11229939 |
| phylogenetic analyses of two "archaeal" genes in thermotoga maritima reveal multiple transfers between archaea and bacteria. | the genome sequence of thermotoga maritima revealed that 24% of its open reading frames (orfs) showed the highest similarity scores to archaeal genes in blast analyses. here we screened 16 strains from the genus thermotoga and other related thermotogales for the occurrence of two of these "archaeal" genes: the gene encoding the large subunit of glutamate synthase (gltb) and the myo-inositol 1p synthase gene (ino1). both genes were restricted to the thermotoga species within the thermotogales. th ... | 2001 | 11230537 |
| legume root nodule bacteria and acid ph. | in 1984 the australian wool research trust fund called for expressions of interest in projects directed at using the developing techniques of molecular biology for application to agricultural problems. with our interests in legume root nodule bacteria and their physiology, we felt that the problems for legume nodulation and n2 fixation posed by soils which were already acid, or which were rapidly acidifying, required just such attention. further, the finding body's request coincided with the hig ... | 2000 | 11233369 |
| p(ii) signal transduction proteins, pivotal players in microbial nitrogen control. | the p(ii) family of signal transduction proteins are among the most widely distributed signal proteins in the bacterial world. first identified in 1969 as a component of the glutamine synthetase regulatory apparatus, p(ii) proteins have since been recognized as playing a pivotal role in control of prokaryotic nitrogen metabolism. more recently, members of the family have been found in higher plants, where they also potentially play a role in nitrogen control. the p(ii) proteins can function in t ... | 2001 | 11238986 |
| determination of wolbachia genome size by pulsed-field gel electrophoresis. | genome sizes of six different wolbachia strains from insect and nematode hosts have been determined by pulsed-field gel electrophoresis of purified dna both before and after digestion with rare-cutting restriction endonucleases. enzymes smai, apai, asci, and fsei cleaved the studied wolbachia strains at a small number of sites and were used for the determination of the genome sizes of wmelpop, wmel, and wmelcs (each 1.36 mb), wri (1.66 mb), wbma (1.1 mb), and wdim (0.95 mb). the wolbachia genome ... | 2001 | 11244060 |
| glucan synthase complex of aspergillus fumigatus. | the glucan synthase complex of the human pathogenic mold aspergillus fumigatus has been investigated. the genes encoding the putative catalytic subunit fks1p and four rho proteins of a. fumigatus were cloned and sequenced. sequence analysis showed that affks1p was a transmembrane protein very similar to other fksp proteins in yeasts and in aspergillus nidulans. heterologous expression of the conserved internal hydrophilic domain of affks1p was achieved in escherichia coli. anti-fks1p antibodies ... | 2001 | 11244067 |
| agricultural microbes genome 2: first glimpses into the genomes of plant-associated microbes. | 2001 | 11251088 | |
| two rpoh homologs responsible for the expression of heat shock protein genes in sinorhizobium meliloti. | we identified two rpoh-related genes encoding sigma32-like proteins from sinorhizobium meliloti, a nitrogen-fixing root-nodule symbiont of alfalfa. the genes, rpoh1 and rpoh2, are functionally similar to rpoh of escherichia coli because they partially complemented an e. coli rpoh null mutant. we obtained evidence indicating that these genes are involved in the heat shock response in s. meliloti. following an increase in temperature, synthesis of several putative heat shock proteins (hsps) was in ... | 2001 | 11254138 |
| analysis of transcriptionally active gene clusters of major outer membrane protein multigene family in ehrlichia canis and e. chaffeensis. | ehrlichia canis and e. chaffeensis are tick-borne obligatory intramonocytic ehrlichiae that cause febrile systemic illness in humans and dogs, respectively. the current study analyzed the pleomorphic multigene family encoding approximately 30-kda major outer membrane proteins (omps) of e. canis and e. chaffeensis. upstream from seca and downstream of hypothetical transcriptional regulator, 22 paralogs of the omp gene family were found to be tandemly arranged except for one or two genes with oppo ... | 2001 | 11254561 |
| immunochemical and biological characterization of three capsular polysaccharides from a single bacteroides fragilis strain. | although bacteroides fragilis accounts for only 0.5% of the normal human colonic flora, it is the anaerobic species most frequently isolated from intra-abdominal and other infections with an intestinal source. the capsular polysaccharides of b. fragilis are part of a complex of surface polysaccharides and are the organism's most important virulence factors in the formation of intra-abdominal abscesses. two capsular polysaccharides from strain nctc 9343, ps a1 and ps b1, have been characterized s ... | 2001 | 11254591 |
| complete genome sequence of caulobacter crescentus. | the complete genome sequence of caulobacter crescentus was determined to be 4,016,942 base pairs in a single circular chromosome encoding 3,767 genes. this organism, which grows in a dilute aquatic environment, coordinates the cell division cycle and multiple cell differentiation events. with the annotated genome sequence, a full description of the genetic network that controls bacterial differentiation, cell growth, and cell cycle progression is within reach. two-component signal transduction p ... | 2001 | 11259647 |
| genetic diversity of sinorhizobium populations recovered from different medicago varieties cultivated in tunisian soils. | a collection of 468 rhizobial isolates was obtained from different ecological areas of tunisia by trapping them on medicago sativa cv. gabes, medicago scutelleta cv. kelson, medicago truncatula, and medicago ciliaris. a subsample of 134 rhizobia was chosen to determine their plasmid profile, and 89 isolates were subjected to multilocus enzyme electrophoresis (mlee) and pcr/rflp analysis using 16s, igs (inter genic spacer), and nifkd probes. twenty-five representatives from these isolates were ev ... | 2001 | 11261493 |
| early production of rhizopine in nodules induced by sinorhizobium meliloti strain l5-30. | the rhizopine l-3-o-methyl-scyllo-inosamine (3-o-msi) is metabolized by approximately 10% of the strains of rhizobium leguminosarum by. viciae and sinorhizobium meliloti. rhizopine strains enjoy a substantial competitive advantage in nodulation, which is manifest before 14 days post-inoculation, implying that rhizopine is produced before this time. we were able to detect this compound in the roots of alfalfa (medicago sativum l. cv. hunter river) four days after germination (six days post-infect ... | 2001 | 11261497 |
| dna methyltransferases of the cyanobacterium anabaena pcc 7120. | from the characterization of enzyme activities and the analysis of genomic sequences, the complement of dna methyltransferases (mtases) possessed by the cyanobacterium anabaena pcc 7120 has been deduced. anabaena has nine dna mtases. four are associated with type ii restriction enzymes (avai, avaii, avaiii and the newly recognized inactive avaiv), and five are not. of the latter, four may be classified as solitary mtases, those whose function lies outside of a restriction/modification system. th ... | 2001 | 11266551 |
| identification of nolr-regulated proteins in sinorhizobium meliloti using proteome analysis. | extractable proteins from sinorhizobium meliloti strains ak631 and ek698 (a tn5-induced noir-deficient mutant of ak631), grown in tryptone agar (ta) medium with or without the addition of the plant signal luteolin, were separated by two-dimensional gel electrophoresis and compared. analysis of silver-stained gels showed that the noir mutant had 189 proteins that were significantly altered in their levels (101 protein spots up- and 88 downregulated). coomassie-stained preparative two-dimensional ... | 2000 | 11271500 |
| proteome analysis demonstrates complex replicon and luteolin interactions in psyma-cured derivatives of sinorhizobium meliloti strain 2011. | sinorhizobium meliloti was studied by proteomic analysis to investigate the contribution made by plasmid-encoded functions on the intracellular regulation of this bacterium. protein profiles of strain 2011 were compared with those from its mutant strains which were either cured of their prme2011a (also called psyma) plasmid (strain 818), or contained an extensive deletion of this plasmid (strain sma146). plasmid psyma contains the nodulation and nitrogen fixation genes and is 1.4 mbp with an est ... | 2000 | 11271501 |
| cloning and characterization of the gene cluster for palatinose metabolism from the phytopathogenic bacterium erwinia rhapontici. | erwinia rhapontici is able to convert sucrose into isomaltulose (palatinose, 6-o-alpha-d-glucopyranosyl-d-fructose) and trehalulose (1-o-alpha-d-glucopyranosyl-d-fructose) by the activity of a sucrose isomerase. these sucrose isomers cannot be metabolized by plant cells and most other organisms and therefore are possibly advantageous for the pathogen. this view is supported by the observation that in vitro yeast invertase activity can be inhibited by palatinose, thus preventing sucrose consumpti ... | 2001 | 11274100 |
| mutually exclusive distribution of is1548 and gbsi1, an active group ii intron identified in human isolates of group b streptococci. | the present study shows that active, self-splicing group ii intron gbsi1 is located downstream of the c5a-peptidase gene, scpb, in some group b streptococcus (gbs) isolates that lack insertion sequence is1548. is1548 was previously reported to be often present at the scpb locus in gbs isolated in association with endocarditis. since none of 67 gbs isolates examined, 40 of which were of serotype iii, harbored both is1548 and gbsi1, these two elements are suggested to be markers for different gene ... | 2001 | 11274116 |
| genetic organization of the region encoding regulation, biosynthesis, and transport of rhizobactin 1021, a siderophore produced by sinorhizobium meliloti. | eight genes have been identified that function in the regulation, biosynthesis, and transport of rhizobactin 1021, a hydroxamate siderophore produced under iron stress by sinorhizobium meliloti. the genes were sequenced, and transposon insertion mutants were constructed for phenotypic analysis. six of the genes, named rhbabcdef, function in the biosynthesis of the siderophore and were shown to constitute an operon that is repressed under iron-replete conditions. another gene in the cluster, name ... | 2001 | 11274118 |
| a functional myo-inositol dehydrogenase gene is required for efficient nitrogen fixation and competitiveness of sinorhizobium fredii usda191 to nodulate soybean (glycine max [l.] merr.). | inositol derivative compounds provide a nutrient source for soil bacteria that possess the ability to degrade such compounds. rhizobium strains that are capable of utilizing certain inositol derivatives are better colonizers of their host plants. we have cloned and determined the nucleotide sequence of the myo-inositol dehydrogenase gene (idha) of sinorhizobium fredii usda191, the first enzyme responsible for inositol catabolism. the deduced idha protein has a molecular mass of 34,648 da and sho ... | 2001 | 11274120 |
| glnd and mvin are genes of an essential operon in sinorhizobium meliloti. | to evaluate the role of uridylyl-transferase, the sinorhizobium meliloti glnd gene was isolated by heterologous complementation in azotobacter vinelandii. the glnd gene is cotranscribed with a gene homologous to salmonella mvin. glnd1::omega or mvin1::omega mutants could not be isolated by a powerful sucrose counterselection procedure unless a complementing cosmid was provided, indicating that glnd and mvin are members of an indispensable operon in s. meliloti. | 2001 | 11274131 |
| sinorhizobium meliloti plasmid prm1132f replicates by a rolling-circle mechanism. | prm1132f isolated from sinorhizobium meliloti is a group iii rolling-circle-replicating (rcr) plasmid. at least seven of eight open reading frames in the nucleotide sequence represented coding regions. the minimal replicon contained a rep gene and single- and double-stranded origins of replication. detection of single-stranded plasmid dna confirmed that prm1132f replicated via an rcr mechanism. | 2001 | 11274136 |
| galactosides in the rhizosphere: utilization by sinorhizobium meliloti and development of a biosensor. | identifying the types and distributions of organic substrates that support microbial activities around plant roots is essential for a full understanding of plant-microbe interactions and rhizosphere ecology. we have constructed a strain of the soil bacterium sinorhizobium meliloti containing a gfp gene fused to the mela promoter which is induced on exposure to galactose and galactosides. we used the fusion strain as a biosensor to determine that galactosides are released from the seeds of severa ... | 2001 | 11274355 |
| the nodulation protein nodg shows the enzymatic activity of an 3-oxoacyl-acyl carrier protein reductase. | the acyl carrier protein nodf is required for the synthesis of unusual polyunsaturated fatty acids that confer specificity to lipochitin oligosaccharide nodulation (nod) factors of rhizobium leguminosarum. in this study, homogeneous nodf protein was used as a ligand to identify proteins of r. leguminosarum that specifically interact with nodf and presumably are involved in the biosynthesis or transfer of the unusual fatty acids. the n-terminal amino acid sequence of a 29-kda protein that interac ... | 2001 | 11277432 |