| 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 |
| 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 |
| 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 |
| identification of methyl halide-utilizing genes in the methyl bromide-utilizing bacterial strain imb-1 suggests a high degree of conservation of methyl halide-specific genes in gram-negative bacteria. | strain imb-1, an aerobic methylotrophic member of the alpha subgroup of the proteobacteria, can grow with methyl bromide as a sole carbon and energy source. a single cmu gene cluster was identified in imb-1 that contained six open reading frames: cmuc, cmua, orf146, paae, huti, and partial metf. cmua from imb-1 has high sequence homology to the methyltransferase cmua from methylobacterium chloromethanicum and hyphomicrobium chloromethanicum and contains a c-terminal corrinoid-binding motif and a ... | 2001 | 11282657 |
| the hcl gene of medicago truncatula controls rhizobium-induced root hair curling. | the symbiotic infection of the model legume medicago truncatula by sinorhizobium meliloti involves marked root hair curling, a stage where entrapment of the microsymbiont occurs in a chamber from which infection thread formation is initiated within the root hair. we have genetically dissected these early symbiotic interactions using both plant and rhizobial mutants and have identified a m. truncatula gene, hcl, which controls root hair curling. s. meliloti nod factors, which are required for the ... | 2001 | 11290290 |
| complete dna sequence and analysis of the large virulence plasmid of shigella flexneri. | the complete sequence analysis of the 210-kb shigella flexneri 5a virulence plasmid was determined. shigella spp. cause dysentery and diarrhea by invasion and spread through the colonic mucosa. most of the known shigella virulence determinants are encoded on a large plasmid that is unique to virulent strains of shigella and enteroinvasive escherichia coli; these known genes account for approximately 30 to 35% of the virulence plasmid. in the complete sequence of the virulence plasmid, 286 open r ... | 2001 | 11292750 |
| preparation, immunogenicity, and protective efficacy, in a murine model, of a conjugate vaccine composed of the polysaccharide moiety of the lipopolysaccharide of vibrio cholerae o139 bound to tetanus toxoid. | the epidemic and pandemic potential of vibrio cholerae o139 is such that a vaccine against this newly emerged serogroup of v. cholerae is required. a conjugate made of the polysaccharide moiety (o-specific polysaccharide plus core) of the lipopolysaccharide (lps) of v. cholerae o139 (pmlps) was prepared by derivatization of the pmlps with adipic acid dihydrazide and coupling to tetanus toxoid (tt) by carbodiimide-mediated condensation. the immunologic properties of the conjugate were tested usin ... | 2001 | 11292781 |
| characterization of the d-xylulose 5-phosphate/d-fructose 6-phosphate phosphoketolase gene (xfp) from bifidobacterium lactis. | a d-xylulose 5-phosphate/d-fructose 6-phosphate phosphoketolase (xfp) from the probiotic bifidobacterium lactis was purified to homogeneity. the specific activity of the purified enzyme with d-fructose 6-phosphate as a substrate is 4.28 units per mg of enzyme. k(m) values for d-xylulose 5-phosphate and d-fructose 6-phosphate are 45 and 10 mm, respectively. the native enzyme has a molecular mass of 550,000 da. the subunit size upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (90,000 ... | 2001 | 11292814 |
| differential regulation of a family of apyrase genes from medicago truncatula. | four putative apyrase genes were identified from the model legume medicago truncatula. two of the genes identified from m. truncatula (mtapy1 and mtapy4) are expressed in roots and are inducible within 3 h after inoculation with sinorhizobium meliloti. the level of mrna expression of the other two putative apyrases, mtapy2 and mtapy3, was unaffected by rhizobial inoculation. screening of a bacterial artificial chromosome library of m. truncatula genomic dna showed that mtapy1, mtapy3, and mtapy4 ... | 2001 | 11299390 |
| a purine-related metabolite negatively regulates fixnoqp expression in sinorhizobium meliloti by modulation of fixk expression. | 5-aminoimidazole-4-carboxamide nucleotide (aicar) is a negative effector of cytochrome terminal oxidase cbb3 production in rhizobium etli. in this work, the effect of aicariboside (aicar), the precursor of aicar on the expression of the sinorhizobium meliloti fixnoqp operon encoding the symbiotic terminal oxidase cbb3, was analyzed. aicar reduced the microaerobic induction levels of fixn-lacz and fixt-lacz gene fusions 18- and seven-fold respectively, and both genes were activated by the transcr ... | 2001 | 11310745 |
| isolation and symbiotic characterization of aromatic amino acid auxotrophs of sinorhizobium meliloti. | ten aromatic amino acid auxotrophs of sinorhizobium meliloti (previously called rhizobium meliloti) rmd201 were generated by random mutagenesis with transposon tn5 and their symbiotic properties were studied. normal symbiotic activity, as indicated by morphological features, was observed in the tryptophan synthase mutants and the lone tyrosine mutant. the trpe and aro mutants fixed trace amounts of nitrogen whereas the phe mutant was completely ineffective in nitrogen fixation. histology of the ... | 2000 | 11324158 |
| the ccrm dna methyltransferase of agrobacterium tumefaciens is essential, and its activity is cell cycle regulated. | dna methylation is now recognized as a regulator of multiple bacterial cellular processes. ccrm is a dna adenine methyltransferase found in the alpha subdivision of the proteobacteria. like the dam enzyme, which is found primarily in escherichia coli and other gamma proteobacteria, it does not appear to be part of a dna restriction-modification system. the ccrm homolog of agrobacterium tumefaciens was found to be essential for viability. overexpression of ccrm is associated with significant abno ... | 2001 | 11325934 |
| osmoregulated periplasmic glucans of erwinia chrysanthemi. | we report the initial characterization of the osmoregulated periplasmic glucans (opgs) of erwinia chrysanthemi. opgs are intrinsic components of the bacterial envelope necessary to the pathogenicity of this phytopathogenic enterobacterium (f. page, s. altabe, n. hugouvieux-cotte-pattat, j.-m. lacroix, j. robert-baudouy and j.-p. bohin, j. bacteriol. 183:0000-0000, 2001 [companion in this issue]). opgs were isolated by trichloracetic acid treatment and gel permeation chromatography. the synthesis ... | 2001 | 11325941 |
| a homolog of the ctra cell cycle regulator is present and essential in sinorhizobium meliloti. | during development of the symbiotic soil bacterium sinorhizobium meliloti into nitrogen-fixing bacteroids, dna replication and cell division cease and the cells undergo profound metabolic and morphological changes. regulatory genes controlling the early stages of this process have not been identified. as a first step in the search for regulators of these events, we report the isolation and characterization of a ctra gene from s. meliloti. we show that the s. meliloti ctra belongs to the ctra-lik ... | 2001 | 11325950 |
| effects of mutations in the pseudomonas putida miaa gene: regulation of the trpe and trpgdc operons in p. putida by attenuation. | tn5 insertion mutants defective in regulation of the pseudomonas putida trpe and trpgdc operons by tryptophan were found to contain insertions in the p. putida miaa gene, whose product (in escherichia coli) modifies trna(trp) and is required for attenuation. nucleotide sequences upstream of trpe and trpg encode putative leader peptides similar in sequence to leader peptides found in other bacterial species, and the phenotypes of the mutants strongly suggest that transcription of these operons is ... | 2001 | 11325956 |
| complexation precedes phosphorylation for two-component regulatory system fixl/fixj of sinorhizobium meliloti. | the fixl/fixj two-component regulatory system of sinorhizobium meliloti controls the expression of nitrogen fixation genes in response to o2. when phosphorylated, the transcription factor fixj binds to the nifa and fixk promoters in s. meliloti and induces expression of the corresponding genes, both of which encode key transcription activators. phosphorylation of fixj has been proposed to occur via the following cascade. the sensor kinase fixl reacts with atp independently of fixj, transferring ... | 2001 | 11327779 |
| sequential assignment and secondary structure of the 14 kda chemotactic protein chey2 from sinorhizobium meliloti. | | 2001 | 11330820 |
| two enzymes of diacylglyceryl-o-4'-(n,n,n,-trimethyl)homoserine biosynthesis are encoded by btaa and btab in the purple bacterium rhodobacter sphaeroides. | betaine lipids are ether-linked, nonphosphorous glycerolipids that resemble the more commonly known phosphatidylcholine in overall structure. betaine lipids are abundant in many eukaryotes such as nonseed plants, algae, fungi, and amoeba. some of these organisms are entirely devoid of phosphatidylcholine and, instead, contain a betaine lipid such as diacylglyceryl-o-4'-(n,n,n,-trimethyl)homoserine. recently, this lipid also was discovered in the photosynthetic purple bacterium rhodobacter sphaer ... | 2001 | 11331765 |
| functional analysis of the galactosyltransferases required for biosynthesis of d-galactan i, a component of the lipopolysaccharide o1 antigen of klebsiella pneumoniae. | d-galactan i is an o-antigenic polymer with the repeat unit structure [-->3)-beta-d-galf-(1-->3)-alpha-d-galp-(1-->], that is found in the lipopolysaccharide of klebsiella pneumoniae o1 and other gram-negative bacteria. a genetic locus containing six genes is responsible for the synthesis and assembly of d-galactan i via an atp-binding cassette (abc) transporter-dependent pathway. the galactosyltransferase activities that are required for the processive polymerization of d-galactan i were identi ... | 2001 | 11344139 |
| isolation of pdx2, a second novel gene in the pyridoxine biosynthesis pathway of eukaryotes, archaebacteria, and a subset of eubacteria. | in this paper we describe the isolation of a second gene in the newly identified pyridoxine biosynthesis pathway of archaebacteria, some eubacteria, fungi, and plants. although pyridoxine biosynthesis has been thoroughly examined in escherichia coli, recent characterization of the cercospora nicotianae biosynthesis gene pdx1 led to the discovery that most organisms contain a pyridoxine synthesis gene not found in e. coli. pdx2 was isolated by a degenerate primer strategy based on conserved seque ... | 2001 | 11344146 |
| rhizobial nodl o-acetyl transferase and nods n-methyl transferase functionally interfere in production of modified nod factors. | the products of the rhizobial nodulation genes are involved in the biosynthesis of lipochitin oligosaccharides (lcos), which are host-specific signal molecules required for nodule formation. the presence of an o-acetyl group on c-6 of the nonreducing n-acetylglucosamine residue of lcos is due to the enzymatic activity of nodl. here we show that transfer of the nodl gene into four rhizobial species that all normally produce lcos that are not modified on c-6 of the nonreducing terminal residue res ... | 2001 | 11344149 |
| intracellular survival of brucella spp. in human monocytes involves conventional uptake but special phagosomes. | brucella spp. are facultative intracellular parasites of various mammals, including humans, typically infecting lymphoid as well as reproductive organs. we have investigated how b. suis and b. melitensis enter human monocytes and in which compartment they survive. peripheral blood monocytes readily internalized nonopsonized brucellae and killed most of them within 12 to 18 h. the presence of brucella-specific antibodies (but not complement) increased the uptake of bacteria without increasing the ... | 2001 | 11349069 |
| sugar-binding activity of pea lectin enhances heterologous infection of transgenic alfalfa plants by rhizobium leguminosarum biovar viciae. | transgenic alfalfa (medicago sativa l. cv regen) roots carrying genes encoding soybean lectin or pea (pisum sativum) seed lectin (psl) were inoculated with bradyrhizobium japonicum or rhizobium leguminosarum bv viciae, respectively, and their responses were compared with those of comparably inoculated control plants. we found that nodule-like structures formed on alfalfa roots only when the rhizobial strains produced nod factor from the alfalfa-nodulating strain, sinorhizobium meliloti. uninfect ... | 2001 | 11351077 |
| transmembrane topology of pit-2, a phosphate transporter-retrovirus receptor. | pit-1 and pit-2 are related multiple transmembrane proteins which function as sodium-dependent phosphate transporters and as the cell receptors of several oncoretroviruses. two copies of a homology domain that is found in distantly related species assign these proteins to a large family of phosphate transporters. a current membrane topology model of pit-1 and pit-2 predicts 10 transmembrane domains. however, the validity of this model has not been addressed experimentally. we addressed this issu ... | 2001 | 11356966 |
| ralstonia solanacearum needs motility for invasive virulence on tomato. | ralstonia solanacearum, a widely distributed and economically important plant pathogen, invades the roots of diverse plant hosts from the soil and aggressively colonizes the xylem vessels, causing a lethal wilting known as bacterial wilt disease. by examining bacteria from the xylem vessels of infected plants, we found that r. solanacearum is essentially nonmotile in planta, although it can be highly motile in culture. to determine the role of pathogen motility in this disease, we cloned, charac ... | 2001 | 11371523 |
| regulation of rpos gene expression in pseudomonas: involvement of a tetr family regulator. | the rpos gene encodes the sigma factor which was identified in several gram-negative bacteria as a central regulator during stationary phase. rpos gene regulation is known to respond to cell density, showing higher expression in stationary phase. for pseudomonas aeruginosa, it has been demonstrated that the cell-density-dependent regulation response known as quorum sensing interacts with this regulatory response. using the rpos promoter of p. putida, we identified a genomic tn5 insertion mutant ... | 2001 | 11371535 |
| unusual methyl-branched alpha,beta-unsaturated acyl chain substitutions in the nod factors of an arctic rhizobium, mesorhizobium sp. strain n33 (oxytropis arctobia). | mesorhizobium sp. strain n33 (oxytropis arctobia), a rhizobial strain isolated in arctic canada, is able to fix nitrogen at very low temperatures in association with a few arctic legume species belonging to the genera astragalus, onobrychis, and oxytropis. using mass spectrometry and nuclear magnetic resonance spectroscopy, we have determined the structure of n33 nod factors, which are major determinants of nodulation. they are pentameric lipochito-oligosaccharides 6-o sulfated at the reducing e ... | 2001 | 11371536 |
| role of a ferredoxin gene cotranscribed with the nifhdk operon in n(2) fixation and nitrogenase "switch-off" of azoarcus sp. strain bh72. | the endophytic diazotroph azoarcus sp. strain bh72 is capable of infecting rice roots and of expressing the nitrogenase (nif) genes there. in order to study the genetic background for nitrogen fixation in strain bh72, the structural genes of nitrogenase (nifhdk) were cloned and sequenced. the sequence analysis revealed an unusual gene organization: downstream of nifhdk, a ferredoxin gene (fdxn; 59% amino acid sequence identity to r. capsulatus fdxn) and open reading frames showing 52 and 36% ami ... | 2001 | 11371540 |
| identification and structure of the rhizobium galegae common nodulation genes: evidence for horizontal gene transfer. | rhizobia are soil bacteria able to fix atmospheric nitrogen in symbiosis with leguminous plants. in response to a signal cascade coded by genes of both symbiotic partners, a specific plant organ, the nodule, is formed. rhizobial nodulation (nod) genes trigger nodule formation through the synthesis of nod factors, a family of chitolipooligosaccharides that are specifically recognized by the host plant at the first stages of the nodulation process. here, we present the organization and sequence of ... | 2001 | 11371578 |
| the sinorhizobium meliloti nutrient-deprivation-induced tyrosine degradation gene hmga is controlled by a novel member of the arsr family of regulatory genes. | the regulation of the nutrient-deprivation-induced sinorhizobium meliloti homogentisate dioxygenase (hmga) gene, involved in tyrosine degradation, was examined. hmga expression was found to be independent of the canonical nitrogen regulation (ntr) system. to identify regulators of hmga, secondary mutagenesis of an s. meliloti strain harboring a hmga-luxab reporter gene fusion (n4) was carried out using transposon tn1721. two independent tn1721 insertions were found to be located in a positive re ... | 2001 | 11375175 |
| control of directionality in integrase-mediated recombination: examination of recombination directionality factors (rdfs) including xis and cox proteins. | similarity between the dna substrates and products of integrase-mediated site-specific recombination reactions results in a single recombinase enzyme being able to catalyze both the integration and excision reactions. the control of directionality in these reactions is achieved through a class of small accessory factors that favor one reaction while interfering with the other. these proteins, which we will refer to collectively as recombination directionality factors (rdfs), play architectural r ... | 2001 | 11376138 |
| agrobacterium rhizogenes-transformed roots of medicago truncatula for the study of nitrogen-fixing and endomycorrhizal symbiotic associations. | medicago truncatula, a diploid autogamous legume, is currently being developed as a model plant for the study of root endosymbiotic associations, including nodulation and mycorrhizal colonization. an important requirement for such a plant is the possibility of rapidly introducing and analyzing chimeric gene constructs in root tissues. for this reason, we developed and optimized a convenient protocol for agrobacterium rhizogenes-mediated transformation of m. truncatula. this unusual protocol, whi ... | 2001 | 11386364 |
| the disruption of a gene encoding a putative arylesterase impairs pyruvate dehydrogenase complex activity and nitrogen fixation in sinorhizobium meliloti. | nitrogen-fixing sinorhizobium meliloti cells depend upon dicarboxylic acids as carbon and energy sources. the metabolism of these intermediate compounds of the trichloroacetic acid cycle is dependent upon the availability of acetyl-coenzyme a (coa). in bacteroids, the combined activities of malic enzymes and pyruvate dehydrogenase (pdh) have been proposed to be responsible for the anaplerotic synthesis of acetyl-coa. we obtained a s. meliloti mutant strain, pd3, in which a tn5 insertion led to a ... | 2001 | 11386377 |
| characterization, cloning and sequence analysis of the inducible ochrobactrum anthropi ampc beta-lactamase. | ochrobactrum anthropi is resistant to most cephalosporins and penicillins due, at least in part, to the inducible expression of a single beta-lactamase. the beta-lactamase gene has been cloned and sequenced. it encodes an ampc-type class 1 serine active-site enzyme that hydrolyses mainly cephalosporins and is resistant to inhibition by clavulanic acid. expression of the ampc gene is inducible via a typical ampr regulator, which is encoded upstream of ampc. inducible expression is retained follow ... | 2001 | 11389106 |
| a glutamine-amidotransferase-like protein modulates fixt anti-kinase activity in sinorhizobium meliloti. | nitrogen fixation gene expression in sinorhizobium meliloti, the alfalfa symbiont, depends on a cascade of regulation that involves both positive and negative control. on top of the cascade, the two-component regulatory system fixlj is activated under the microoxic conditions of the nodule. in addition, activity of the fixlj system is inhibited by a specific anti-kinase protein, fixt. the physiological significance of this negative regulation by fixt was so far unknown. | 2001 | 11389771 |
| changes in fatty acid composition and degree of unsaturation of (brady)rhizobia as a response to phases of growth, reduced water activities and mild desiccation. | the effects of growth phase, reductions in the water activity (a(w)) of the growth medium and mild desiccation on the composition and the degree of unsaturation of cellular fatty acids (cfa) of sinorhizobium meliloti, bradyrhizobium elkanii and bradyrhizobium japonicum were studied. during the course of growth, an interchange of cis-vaccenic with lactobacillic acid and a slight increase in palmitic acid were observed while other fatty acids remained constant. the degree of unsaturation was signi ... | 2001 | 11392487 |
| the agrobacterium tumefaciens rnd homolog is required for trar-mediated quorum-dependent activation of ti plasmid tra gene expression. | conjugal transfer of agrobacterium tumefaciens ti plasmids is regulated by quorum sensing via trar and its cognate autoinducer, n-(3-oxo-octanoyl)-l-homoserine lactone. we isolated four tn5-induced mutants of a. tumefaciens c58 deficient in trar-mediated activation of tra genes on ptic58deltaaccr. these mutations also affected the growth of the bacterium but had no detectable influence on the expression of two tester gene systems that are not regulated by quorum sensing. in all four mutants tn5 ... | 2001 | 11395455 |
| global versus local regulatory roles for lrp-related proteins: haemophilus influenzae as a case study. | lrp (leucine-responsive regulatory protein) plays a global regulatory role in escherichia coli, affecting expression of dozens of operons. numerous lrp-related genes have been identified in different bacteria and archaea, including asnc, an e. coli gene that was the first reported member of this family. pairwise comparisons of amino acid sequences of the corresponding proteins shows an average sequence identity of only 29% for the vast majority of comparisons. by contrast, lrp-related proteins f ... | 2001 | 11395465 |
| microbial origin of plant-type 2-keto-3-deoxy-d-arabino-heptulosonate 7-phosphate synthases, exemplified by the chorismate- and tryptophan-regulated enzyme from xanthomonas campestris. | enzymes performing the initial reaction of aromatic amino acid biosynthesis, 2-keto-3-deoxy-d-arabino-heptulosonate 7-phosphate (dahp) synthases, exist as two distinct homology classes. the three classic escherichia coli paralogs are aroa(i) proteins, but many members of the bacteria possess the aroa(ii) class of enzyme, sometimes in combination with aroa(i) proteins. aroa(ii) dahp synthases until now have been shown to be specifically dedicated to secondary metabolism (e.g., formation of ansamy ... | 2001 | 11395471 |
| efficient vir gene induction in agrobacterium tumefaciens requires vira, virg, and vir box from the same ti plasmid. | the vir genes of octopine, nopaline, and l,l-succinamopine ti plasmids exhibit structural and functional similarities. however, we observed differences in the interactions between octopine and nopaline vir components. the induction of an octopine vire(a6)::lacz fusion (psm358cd) was 2.3-fold higher in an octopine strain (a348) than in a nopaline strain (c58). supplementation of the octopine virg(a6) in a nopaline strain with psm358 did not completely restore vire(a6) induction. however, addition ... | 2001 | 11395473 |
| periplasmic pqq-dependent glucose oxidation in free-living and symbiotic rhizobia. | the expression of the pyrroloquinoline quinone (pqq)-dependent glucose dehydrogenase (gdh) of rhizobium tropici ciat899 and sinorhizobium meliloti rcr2011 was investigated under different nutrient-limiting conditions in continuous cultures, under different conditions of phosphate availability, and in s. meliloti bacteroids. the presence of free pqq in alfalfa root exudates has also been assayed. it was shown that apo-gdh or holoenzyme was actively synthesized by these rhizobia, with the concomit ... | 2001 | 11400050 |
| motility and the polar flagellum are required for aeromonas caviae adherence to hep-2 cells. | aeromonas caviae is increasingly being recognized as a cause of gastroenteritis, especially among the young. the adherence of aeromonads to human epithelial cells in vitro has been correlated with enteropathogenicity, but the mechanism is far from well understood. initial investigations demonstrated that adherence of a. caviae to hep-2 cells was significantly reduced by either pretreating bacterial cells with an antipolar flagellin antibody or by pretreating hep-2 cells with partially purified f ... | 2001 | 11401962 |
| brucella abortus cyclic beta-1,2-glucan mutants have reduced virulence in mice and are defective in intracellular replication in hela cells. | null cyclic beta-1,2-glucan synthetase mutants (cgs mutants) were obtained from brucella abortus virulent strain 2308 and from b. abortus attenuated vaccinal strain s19. both mutants show greater sensitivity to surfactants like deoxycholic acid, sodium dodecyl sulfate, and zwittergent than the parental strains, suggesting cell surface alterations. although not to the same extent, both mutants display reduced virulence in mice and defective intracellular multiplication in hela cells. the b. abort ... | 2001 | 11401996 |
| complete dna sequence of yersinia enterocolitica serotype 0:8 low-calcium-response plasmid reveals a new virulence plasmid-associated replicon. | the complete nucleotide sequence and organization of the yersinia enterocolitica serotype 0:8 low-calcium-response (lcr) plasmid, pyve8081, were determined. the 67,720-bp plasmid encoded all the genes known to be part of the lcr stimulon except for ylpa. eight of 13 intact open reading frames of unknown function identified in pyve8081 had homologues in yersinia pestis plasmid pcd1 or in y. enterocolitica serotype 0:9 plasmid pyve227. a region of approximately 17 kbp showed no dna identity to pcd ... | 2001 | 11402007 |
| [bacterial contamination and presence of sinorhizobium meliloti in irrigation canal water from the neuquén river]. | a survey of the changes in populations of heterotrophic bacteria, coliform microorganisms and s. meliloti was conducted in samples taken from the water irrigation channels of the neuquén river (argentina). fifty-six water samples were collected during the spring-summer seasons of 1997-1999 years. both the heterotrophic plate count bacterial and the number of coliforms oscillated between 110-5050 cfu/ml and 8-1400 cfu/100 ml, respectively, during the period this study was carried out. fecal colif ... | 2001 | 11407015 |
| a deeper investigation on carbohydrate cycling in sinorhizobium meliloti. | recycling of triose-phosphate and pentose-phosphate was previously reported on glucose in sinorhizobium meliloti, a polysaccharide-synthesizing bacterium, but the metabolic basis of such processes remained unclear. in this work, we have used (13)c-labelling strategies to demonstrate that carbohydrate cycling in this organism is independent of the gluconate bypass, the alternative pathway for glucose assimilation involving its periplasmic oxidation into gluconate. furthermore, carbohydrate cyclin ... | 2001 | 11418109 |
| identification of a dna binding region in gere from bacillus subtilis. | proteins that have a structure similar to those of luxr and fixj comprise a large subfamily of transcriptional activator proteins. most members of the luxr-fixj family contain a similar amino-terminal receiver domain linked by a small region to a carboxy-terminal domain that contains an amino acid sequence similar to the helix-turn-helix (hth) motif found in other dna-binding proteins. gere from bacillus subtilis is the smallest member of the luxr-fixj family. its 74-amino-acid sequence is simil ... | 2001 | 11418558 |
| trans-3-chloroacrylic acid dehalogenase from pseudomonas pavonaceae 170 shares structural and mechanistic similarities with 4-oxalocrotonate tautomerase. | the genes (caad1 and caad2) encoding the trans-3-chloroacrylic acid dehalogenase (caad) of the 1,3-dichloropropene-utilizing bacterium pseudomonas pavonaceae 170 were cloned and heterologously expressed in escherichia coli and pseudomonas sp. strain gj1. caad is a protein of 50 kda that is composed of alpha-subunits of 75 amino acid residues and beta-subunits of 70 residues. it catalyzes the hydrolytic cleavage of the beta-vinylic carbon-chlorine bond in trans-3-chloroacrylic acid with a turnove ... | 2001 | 11418568 |
| structural and functional characterization of is679 and is66-family elements. | a new insertion sequence (is) element, is679 (2,704 bp in length), has been identified in plasmid pb171 of enteropathogenic escherichia coli b171. is679 has imperfect 25-bp terminal inverted repeats (irs) and three open reading frames (orfs) (here called tnpa, tnpb, and tnpc). a plasmid carrying a composite transposon (tn679) with the kanamycin resistance gene flanked by an intact is679 sequence and an is679 fragment with only irr (ir on the right) was constructed to clarify the transposition ac ... | 2001 | 11418571 |