| functional analysis of the lactococcus lactis galu and gale genes and their impact on sugar nucleotide and exopolysaccharide biosynthesis. | we studied the udp-glucose pyrophosphorylase (galu) and udp-galactose epimerase (gale) genes of lactococcus lactis mg1363 to investigate their involvement in biosynthesis of udp-glucose and udp-galactose, which are precursors of glucose- and galactose-containing exopolysaccharides (eps) in l. lactis. the lactococcal galu gene was identified by a pcr approach using degenerate primers and was found by northern blot analysis to be transcribed in a monocistronic rna. the l. lactis galu gene could co ... | 2001 | 11425718 |
| effects of rice seed surface sterilization with hypochlorite on inoculated burkholderia vietnamiensis. | when a combination of hydrogen peroxide and hypochlorite was used to surface sterilize rice seeds, a 10(2)- to 10(4)-fold decrease in cfu was observed during the first 15 h after inoculation of the rice rhizosphere organism burkholderia vietnamiensis tvv75. this artifact could not be eliminated simply by rinsing the seeds, even thoroughly, with sterile distilled water. when growth resumed, a significant increase in the frequency of rifampin- and nalidixic acid-resistant mutants in the population ... | 2001 | 11425720 |
| nitrogen-fixing nodules with ensifer adhaerens harboring rhizobium tropici symbiotic plasmids. | ensifer adhaerens is a soil bacterium that attaches to other bacteria and may cause lysis of these other bacteria. based on the sequence of its small-subunit rrna gene, e. adhaerens is related to sinorhizobium spp. e. adhaerens atcc 33499 did not nodulate phaseolus vulgaris (bean) or leucaena leucocephala, but with symbiotic plasmids from rhizobium tropici cfn299 it formed nitrogen-fixing nodules on both hosts. the nodule isolates were identified as e. adhaerens isolates by growth on selective m ... | 2001 | 11425750 |
| ribosomal protein gene cluster analysis in eubacterium genomics: homology between sinorhizobium meliloti strain 1021 and bacillus subtilis. | the first whole genome sequence of a symbiotic soil bacterium, sinorhizobium meliloti (formely named rhizobium meliloti) strain 1021, is due in 2001. as an active participant in the european and north american consortium that has completed this work, our group has sequenced a region on the chromosome containing clusters rpobc, str, s10, spc and alpha corresponding to 30 protein genes. the structural organization and function of these genes were compared with those of orthologs in another 15 comp ... | 2001 | 11433019 |
| phenotype microarrays for high-throughput phenotypic testing and assay of gene function. | the bacterium escherichia coli is used as a model cellular system to test and validate a new technology called phenotype microarrays (pms). pm technology is a high-throughput technology for simultaneous testing of a large number of cellular phenotypes. it consists of preconfigured well arrays in which each well tests a different cellular phenotype and an automated instrument that continuously monitors and records the response of the cells in all wells of the arrays. for example, nearly 700 pheno ... | 2001 | 11435407 |
| [genetic diversity of a natural population of sinorhizobium meliloti, detected during analysis of a cryptic plasmid and isrm2011-2 fingerprints]. | fifty-six natural strains of alfalfa nodule bacteria were isolated from samples of the soil under wild legume and alfalfa in two different field sites of irkutsk oblast. based on the results of analysis of plasmid profile, 11 different types of strains were detected, and 43 types were identified based on the results of hybridization with the insertion sequence element isrm2011-2. significant differences were found in the plasmid profile and is fingerprints between strains isolated from the soil ... | 2001 | 11436551 |
| mutation in the ntrr gene, a member of the vap gene family, increases the symbiotic efficiency of sinorhizobium meliloti. | in specific plant organs, namely the root nodules of alfalfa, fixed nitrogen (ammonia) produced by the symbiotic partner sinorhizobium meliloti supports the growth of the host plant in nitrogen-depleted environment. here, we report that a derivative of s. meliloti carrying a mutation in the chromosomal ntrr gene induced nodules with enhanced nitrogen fixation capacity, resulting in an increased dry weight and nitrogen content of alfalfa. the efficient nitrogen fixation is a result of the higher ... | 2001 | 11437262 |
| methionine regeneration and aspartate aminotransferase in parasitic protozoa. | aspartate aminotransferases have been cloned and expressed from crithidia fasciculata, trypanosoma brucei brucei, giardia intestinalis, and plasmodium falciparum and have been found to play a role in the final step of methionine regeneration from methylthioadenosine. all five enzymes contain sequence motifs consistent with membership in the ia subfamily of aminotransferases; the crithidial and giardial enzymes and one trypanosomal enzyme were identified as cytoplasmic aspartate aminotransferases ... | 2001 | 11443076 |
| isolation and characterization of a soluble nadph-dependent fe(iii) reductase from geobacter sulfurreducens. | nadph is an intermediate in the oxidation of organic compounds coupled to fe(iii) reduction in geobacter species, but fe(iii) reduction with nadph as the electron donor has not been studied in these organisms. crude extracts of geobacter sulfurreducens catalyzed the nadph-dependent reduction of fe(iii)-nitrilotriacetic acid (nta). the responsible enzyme, which was recovered in the soluble protein fraction, was purified to apparent homogeneity in a four-step procedure. its specific activity for f ... | 2001 | 11443080 |
| competence repression under oxygen limitation through the two-component micab signal-transducing system in streptococcus pneumoniae and involvement of the pas domain of micb. | in streptococcus pneumoniae, a fermentative aerotolerant and catalase-deficient human pathogen, oxidases with molecular oxygen as substrate are important for virulence and for competence. the signal-transducing two-component systems ciarh and comde mediate the response to oxygen, culminating in competence. in this work we show that the two-component micab system, whose micb kinase carries a pas domain, is also involved in competence repression under oxygen limitation. autophosphorylation of reco ... | 2001 | 11443095 |
| compatibility of a wild type and its genetically modified sinorhizobium strain with two mycorrhizal fungi on medicago species as affected by drought stress. | the effect of double inoculation with two strains of sinorhizobium meliloti [the wild type (wt) strain gr4 and its genetically modified (gm) derivative gr4(pck3)], and two species of arbuscular mycorrhizal (am) fungi (glomus deserticola and glomus intraradices) was examined in a microcosm system on three species of medicago (m. nolana, m. rigidula, m. rotata). two water regimes (80 and 100% water holding capacity, whc) were assayed. the efficiency of each am fungus increasing plant growth, nutri ... | 2001 | 11448765 |
| binding site for chitin oligosaccharides in the soybean plasma membrane. | affinity cross-linking of the plasma membrane fraction to an (125)i-labeled chitin oligosaccharide led to the identification and characterization of an 85-kd, chitin binding protein in plasma membrane-enriched fractions from both suspension-cultured soybean cells and root tissue. inhibition analysis indicated a binding preference for larger (i.e. degrees of polymerization = 8) n-acetylated chitin molecules with a 50% inhibition of initial activity value of approximately 50 nm. n-acetyl-glucosami ... | 2001 | 11457966 |
| more than one way to sense chemicals. | | 2001 | 11466269 |
| fructose uptake in sinorhizobium meliloti is mediated by a high-affinity atp-binding cassette transport system. | by transposon mutagenesis, we have isolated a mutant of sinorhizobium meliloti which is totally unable to grow on fructose as sole carbon source as a consequence of its inability to transport this sugar. the cloning and sequencing analysis of the chromosomal dna region flanking the tnphoa insertion revealed the presence of six open reading frames (orfs) organized in two loci, frcrs and frcbcak, transcribed divergently. the frcbca genes encode the characteristic components of an atp-binding casse ... | 2001 | 11466273 |
| genetic studies of mrp, a locus essential for cellular aggregation and sporulation of myxococcus xanthus. | under starvation conditions, myxococcus xanthus undergoes a complex developmental process which includes cellular aggregation and sporulation. a transposon insertion mutant (the tn5-omega280 mutant) with defects in both aggregation and sporulation was analyzed in this study. the tn5-omega280 mutant was found to have a disrupted ntrc-like response regulator designated myxococcus regulatory protein b (mrpb). further sequencing analyses revealed a histidine kinase homolog (mrpa) immediately upstrea ... | 2001 | 11466282 |
| acid and alkaline treatments for enhancing the growth of rhizobia in sludge. | wastewater sludges have been proposed as an effective media for the production of rhizobia. the effect of total suspended solid (tss) concentrations and pretreatments of sludge on the growth of sinorhizobium meliloti were investigated. acid (ph 2.0-6.0 obtained with h2so4) and alkaline (50-200 mequiv.wt./l of naoh) treatments were applied to enhance the biodegradability of primary (0.325%-3.2% tss obtained by dilution of original sample) and secondary (0.2%-0.4% tss obtained by concentration of ... | 2001 | 11467722 |
| temporal effects on the composition of a population of sinorhizobium meliloti associated with medicago sativa and melilotus alba. | an assessment was made of the impact of temporal separation on the composition of a population of sinorhizobium meliloti associated with medicago sativa (alfalfa) and melilotus alba (sweet clover) grown at a single site that had no known history of alfalfa cultivation. root nodules were sampled on six occasions over two seasons, and a total of 1620 isolates of s. meliloti were characterized on the basis of phage sensitivity using 16 typing phages. plant infection tests indicated that symbiotic s ... | 2001 | 11467732 |
| [irepeat sequences of genomes of rhizobium and sinorhizobium meliloti: a comparative analysis]. | amongst prokaryotic genomes, those of nitrogen-fixing members of the rhizobiaceae family are relatively large (6-9 mb), often include mega-plasmids of 1.5-2 mb, and contain numerous families of repeated dna sequences. although most essential nodulation and nitrogen fixation genes are well characterized, these represent only a small fraction of the dna content. little is known about the detailed structure of rhizobial genomes. with the development of sequencing techniques and new bio-informatic t ... | 2001 | 11469253 |
| a conserved rna structure (thi box) is involved in regulation of thiamin biosynthetic gene expression in bacteria. | the thicoge genes of rhizobium etli code for enzymes involved in thiamin biosynthesis. these genes are transcribed with a 211-base untranslated leader that contains the thi box, a 38-base sequence highly conserved in the 5' regions of thiamin biosynthetic and transport genes of gram-positive and gram-negative organisms. a deletion analysis of thic-lacz fusions revealed an unexpected relationship between the degree of repression shown by the deleted derivatives and the length of the thic sequence ... | 2001 | 11470904 |
| direct amplification of nodd from community dna reveals the genetic diversity of rhizobium leguminosarum in soil. | sequences of nodd, a gene found only in rhizobia, were amplified from total community dna isolated from a pasture soil. the polymerase chain reaction (pcr) primers used, y5 and y6, match nodd from rhizobium leguminosarum biovar trifolii, r. leguminosarum biovar viciae and sinorhizobium meliloti. the pcr product was cloned and yielded 68 clones that were identified by restriction pattern as derived from biovar trifolii [11 restriction fragment length polymorphism (rflp) types] and 15 clones ident ... | 2001 | 11472501 |
| brown pigments produced by yarrowia lipolytica result from extracellular accumulation of homogentisic acid. | yarrowia lipolytica produces brown extracellular pigments that correlate with tyrosine catabolism. during tyrosine depletion, the yeast accumulated homogentisic acid, p-hydroxyphenylethanol, and p-hydroxyphenylacetic acid in the medium. homogentisic acid accumulated under all aeration conditions tested, but its concentration decreased as aeration decreased. with moderate aeration, equimolar concentrations of alcohol and p-hydroxyphenylacetic acid (1:1) were detected, but with lower aeration the ... | 2001 | 11472920 |
| effect of primers hybridizing to different evolutionarily conserved regions of the small-subunit rrna gene in pcr-based microbial community analyses and genetic profiling. | genetic profiling techniques of microbial communities based on pcr-amplified signature genes, such as denaturing gradient gel electrophoresis or single-strand-conformation polymorphism (sscp) analysis, are normally done with pcr products of less than 500-bp. the most common target for diversity analysis, the small-subunit rrna genes, however, are larger, and thus, only partial sequences can be analyzed. here, we compared the results obtained by pcr targeting different variable (v) regions (v2 an ... | 2001 | 11472932 |
| specific detection of bradyrhizobium and rhizobium strains colonizing rice (oryza sativa) roots by 16s-23s ribosomal dna intergenic spacer-targeted pcr. | in addition to forming symbiotic nodules on legumes, rhizobial strains are members of soil or rhizosphere communities or occur as endophytes, e.g., in rice. two rhizobial strains which have been isolated from root nodules of the aquatic legumes aeschynomene fluminensis (irbg271) and sesbania aculeata (irbg74) were previously found to promote rice growth. in addition to analyzing their phylogenetic positions, we assessed the suitability of the 16s-23s ribosomal dna (rdna) intergenic spacer (igs) ... | 2001 | 11472944 |
| isolation and regulation of sinorhizobium meliloti 1021 loci induced by oxygen limitation. | eleven sinorhizobium meliloti 1021 loci whose expression was induced under low oxygen concentrations were identified in a collection of 5,000 strains carrying tn5-1063 (luxab) transcriptional reporter gene fusions. the 11 tn5-1063-tagged loci were cloned and characterized. the dependence of the expression of the tagged loci on the fixl/fixj oxygen-sensing two-component regulatory system was examined. three of the loci were found to be dependent upon fixl and fixj for their expression, while one ... | 2001 | 11472955 |
| sinorhizobium meliloti cells require biotin and either cobalt or methionine for growth. | sinorhizobium meliloti is usually cultured in rich media containing yeast extract. it has been suggested that some components of yeast extract are also required for growth in minimal medium. we tested 27 strains of this bacterium and found that none were able to grow in minimal medium when methods to limit carryover of yeast extract were used during inoculation. by fractionation of yeast extract, two required growth factors were identified. biotin was found to be absolutely required for growth, ... | 2001 | 11472965 |
| the composite genome of the legume symbiont sinorhizobium meliloti. | the scarcity of usable nitrogen frequently limits plant growth. a tight metabolic association with rhizobial bacteria allows legumes to obtain nitrogen compounds by bacterial reduction of dinitrogen (n2) to ammonium (nh4+). we present here the annotated dna sequence of the alpha-proteobacterium sinorhizobium meliloti, the symbiont of alfalfa. the tripartite 6.7-megabase (mb) genome comprises a 3.65-mb chromosome, and 1.35-mb psyma and 1.68-mb psymb megaplasmids. genome sequence analysis indicate ... | 2001 | 11474104 |
| analysis of the chromosome sequence of the legume symbiont sinorhizobium meliloti strain 1021. | sinorhizobium meliloti is an alpha-proteobacterium that forms agronomically important n(2)-fixing root nodules in legumes. we report here the complete sequence of the largest constituent of its genome, a 62.7% gc-rich 3,654,135-bp circular chromosome. annotation allowed assignment of a function to 59% of the 3,341 predicted protein-coding orfs, the rest exhibiting partial, weak, or no similarity with any known sequence. unexpectedly, the level of reiteration within this replicon is low, with onl ... | 2001 | 11481430 |
| the complete sequence of the 1,683-kb psymb megaplasmid from the n2-fixing endosymbiont sinorhizobium meliloti. | analysis of the 1,683,333-nt sequence of the psymb megaplasmid from the symbiotic n(2)-fixing bacterium sinorhizobium meliloti revealed that the replicon has a high gene density with a total of 1,570 protein-coding regions, with few insertion elements and regions duplicated elsewhere in the genome. the only copies of an essential arg-trna gene and the mincde genes are located on psymb. almost 20% of the psymb sequence carries genes encoding solute uptake systems, most of which were of the atp-bi ... | 2001 | 11481431 |
| nucleotide sequence and predicted functions of the entire sinorhizobium meliloti psyma megaplasmid. | the symbiotic nitrogen-fixing soil bacterium sinorhizobium meliloti contains three replicons: psyma, psymb, and the chromosome. we report here the complete 1,354,226-nt sequence of psyma. in addition to a large fraction of the genes known to be specifically involved in symbiosis, psyma contains genes likely to be involved in nitrogen and carbon metabolism, transport, stress, and resistance responses, and other functions that give s. meliloti an advantage in its specialized niche. | 2001 | 11481432 |
| non-canonical mechanism for translational control in bacteria: synthesis of ribosomal protein s1. | translation initiation region (tir) of the rpsa mrna encoding ribosomal protein s1 is one of the most efficient in escherichia coli despite the absence of a canonical shine-dalgarno-element. its high efficiency is under strong negative autogenous control, a puzzling phenomenon as s1 has no strict sequence specificity. to define sequence and structural elements responsible for translational efficiency and autoregulation of the rpsa mrna, a series of rpsa'-'lacz chromosomal fusions bearing various ... | 2001 | 11483525 |
| ethylene inhibits the nod factor signal transduction pathway of medicago truncatula. | legumes form a mutualistic symbiosis with bacteria collectively referred to as rhizobia. the bacteria induce the formation of nodules on the roots of the appropriate host plant, and this process requires the bacterial signaling molecule nod factor. although the interaction is beneficial to the plant, the number of nodules is tightly regulated. the gaseous plant hormone ethylene has been shown to be involved in the regulation of nodule number. the mechanism of the ethylene inhibition on nodulatio ... | 2001 | 11487696 |
| cellobiose uptake in the hyperthermophilic archaeon pyrococcus furiosus is mediated by an inducible, high-affinity abc transporter. | the hyperthermophilic archaeon pyrococcus furiosus can utilize different beta-glucosides, like cellobiose and laminarin. cellobiose uptake occurs with high affinity (k(m) = 175 nm) and involves an inducible binding protein-dependent transport system. the cellobiose binding protein (cbta) was purified from p. furiosus membranes to homogeneity as a 70-kda glycoprotein. cbta not only binds cellobiose but also cellotriose, cellotetraose, cellopentaose, laminaribiose, laminaritriose, and sophorose. t ... | 2001 | 11489849 |
| proteolysis of the caulobacter mcpa chemoreceptor is cell cycle regulated by a clpx-dependent pathway. | proteolysis is involved in cell differentiation and the progression through the cell cycle in caulobacter crescentus. we have constitutively expressed the transmembrane chemoreceptor mcpa from a multicopy plasmid to demonstrate that mcpa degradation is modulated during the cell cycle. the level of mcpa protein starts to decrease only when the swarmer cells differentiate into stalked cells. the reduction in mcpa protein levels is maintained until the stalked cells develop into predivisional cells ... | 2001 | 11489852 |
| characterization of pita and pitb from escherichia coli. | escherichia coli contains two major systems for transporting inorganic phosphate (p(i)). the low-affinity p(i) transporter (pita) is expressed constitutively and is dependent on the proton motive force, while the high-affinity pst system (pstscab) is induced at low external p(i) concentrations by the pho regulon and is an abc transporter. we isolated a third putative p(i) transport gene, pitb, from e. coli k-12 and present evidence that pitb encodes a functional p(i) transporter that may be repr ... | 2001 | 11489853 |
| the molecular weight distribution of succinoglycan produced by sinorhizobium meliloti is influenced by specific tyrosine phosphorylation and atpase activity of the cytoplasmic domain of the exop protein. | it is thought that in the gram-negative soil bacterium sinorhizobium meliloti the protein exop is involved in biosynthesis of the acidic exopolysaccharide succinoglycan (eps i). the amounts and compositions of eps i produced by mutants expressing exop proteins characterized by specific amino acid substitutions in the c-terminal cytoplasmic domain were analyzed. the cytoplasmic domain of the exop protein was shown to have atpase activity. mutations in the highly conserved walker a atp-binding mot ... | 2001 | 11489870 |
| methanococcus jannaschii generates l-proline by cyclization of l-ornithine. | cell extracts of methanococcus jannaschii have been shown to readily convert l-ornithine to l-proline. this cyclization reaction proceeds with the loss of only the c-2 nitrogen, as has been documented for ornithine cyclodeaminase (ec 4.3.1.12). since no gene homologous to that coding for ornithine cyclodeaminase is present in the genome of m. jannaschii, these results indicate that proline biosynthesis in m. jannaschii is accomplished by a previously unrecognized enzyme. | 2001 | 11489875 |
| ultrastructural studies on nodules induced by pyrimidine auxotrophs of sinorhizobium meliloti. | twenty three pyrimidine auxotrophs of sinorhizobium meliloti rmd201 were generated by random mutagenesis with transposon tn5. on the basis of biochemical characters these auxotrophic mutants were classified into car, pyrc and pyre/pyrf categories. all auxotrophs induced white nodules which were ineffective in nitrogen fixation. light and electron microscopic studies revealed that the nodules induced by pyrc mutants were more developed than the nodules of car mutants. similarly the nodules induce ... | 2001 | 11491584 |
| the dictyostelium homologue of mammalian soluble adenylyl cyclase encodes a guanylyl cyclase. | a new dictyostelium discoideum cyclase gene was identified that encodes a protein (sgc) with 35% similarity to mammalian soluble adenylyl cyclase (sac). gene disruption of sgc has no effect on adenylyl cyclase activity and results in a >10-fold reduction in guanylyl cyclase activity. the scg- null mutants show reduced chemotactic sensitivity and aggregate poorly under stringent conditions. with mn(2+)/gtp as substrate, most of the sgc activity is soluble, but with the more physiological mg(2+)/g ... | 2001 | 11500361 |
| brucella abortus htra functions as an authentic stress response protease but is not required for wild-type virulence in balb/c mice. | a second mutation has recently been identified in the previously described brucella abortus htra mutant phe1. as a result of this finding, a new b. abortus htra mutant, designated rwp11, was constructed to evaluate the biological function of the brucella htra protease. rwp11 is more sensitive to oxidative killing in vitro and less resistant to killing by cultured murine neutrophils and macrophages than the virulent parental strain 2308 but is not attenuated in balb/c mice through 4 weeks postinf ... | 2001 | 11500472 |
| a medicago truncatula homoglutathione synthetase is derived from glutathione synthetase by gene duplication. | glutathione (gsh) and homo-gsh (hgsh) are the major low-molecular weight thiols synthesized in medicago truncatula. two m. truncatula cdnas (gshs1 and gshs2) corresponding to a putative gsh synthetase (gshs) and a putative hgsh synthetase (hgshs) were characterized. heterologous expression of gshs1 and gshs2 cdnas in an escherichia coli strain deficient in gshs activity showed that gshs1 and gshs2 are a gshs and an hgshs, respectively. leucine-534 and proline-535 present in hgshs were substitute ... | 2001 | 11500568 |
| mutational analysis of the rhizobium lupini h13-3 and sinorhizobium meliloti flagellin genes: importance of flagellin a for flagellar filament structure and transcriptional regulation. | complex flagellar filaments are unusual in their fine structure composed of flagellin dimers, in their right-handed helicity, and in their rigidity, which prevents a switch of handedness. the complex filaments of rhizobium lupini h13-3 and those of sinorhizobium meliloti are composed of three and four flagellin (fla) subunits, respectively. the fla-encoding genes, named flaa through flad, are separately transcribed from sigma(28)-specific promoters. mutational analysis of the fla genes revealed ... | 2001 | 11514517 |
| single and double overexpression of c(4)-cycle genes had differential effects on the pattern of endogenous enzymes, attenuation of photorespiration and on contents of uv protectants in transgenic potato and tobacco plants. | to improve the efficiency of co(2) fixation in c(3) photosynthesis, c(4)-cycle genes were overexpressed in potato and tobacco plants either individually or in combination. overexpression of the phosphoenolpyruvate carboxylase (pepc) gene (ppc) from corynebacterium glutamicum (cppc) or from potato (stppc, deprived of the phosphorylation site) in potato resulted in a 3-6-fold induction of endogenous cytosolic nadp malic enzyme (me) and an increase in the activities of nad-me (3-fold), nadp isocitr ... | 2001 | 11520867 |
| control of bacterial motility by environmental factors in polarly flagellated and peritrichous bacteria isolated from lake baikal. | despite numerous studies on bacterial motility, little is known about the regulation of this process by environmental factors in natural isolates. in this study we investigated the control of bacterial motility in response to environmental parameters in two strains isolated from the natural habitat of lake baikal. morphological characterization, carbon source utilization, fermentation analysis, and sequence comparison of 16s rrna genes showed that these strains belong to two distinct genera, i.e ... | 2001 | 11525977 |
| construction and environmental release of a sinorhizobium meliloti strain genetically modified to be more competitive for alfalfa nodulation. | highly efficient nitrogen-fixing strains selected in the laboratory often fail to increase legume production in agricultural soils containing indigenous rhizobial populations because they cannot compete against these populations for nodule formation. we have previously demonstrated, with a sinorhizobium meliloti puta- mutant strain, that proline dehydrogenase activity is required for colonization and therefore for the nodulation efficiency and competitiveness of s. meliloti on alfalfa roots (j. ... | 2001 | 11525978 |
| the viable but nonculturable state of ralstonia solanacearum may be involved in long-term survival and plant infection. | the role of the dormant-like viable but nonculturable (vbnc) condition in the etiology of bacterial infection was examined using a plant system. the plant-pathogenic bacterium ralstonia solanacearum was first shown to enter into the vbnc state both in response to cupric sulfate when in a saline solution and when placed in autoclaved soil. to determine if the vbnc condition is related to pathogenesis, the physiological status of bacteria recovered from different regions of inoculated tomato plant ... | 2001 | 11525979 |
| antimicrobial properties of pyridine-2,6-dithiocarboxylic acid, a metal chelator produced by pseudomonas spp. | pyridine-2,6-dithiocarboxylic acid (pdtc) is a metal chelator produced by pseudomonas spp. it has been shown to be involved in the biodegradation of carbon tetrachloride; however, little is known about its biological function. in this study, we examined the antimicrobial properties of pdtc and the mechanism of its antibiotic activity. the growth of pseudomonas stutzeri strain kc, a pdtc-producing strain, was significantly enhanced by 32 microm pdtc. all nonpseudomonads and two strains of p. stut ... | 2001 | 11525988 |
| characterization of the single superoxide dismutase of staphylococcus xylosus. | staphylococcus xylosus is a facultative anaerobic bacterium used as a starter culture for fermented meat products. in an attempt to analyze the antioxidant capacities of this organism, the superoxide dismutase (sod) was characterized. s. xylosus contains a single cytoplasmic sod, which was not inhibited by h2o2. the sod activity in crude extracts was completely lost upon metal depletion, but it could be recovered by manganese and very weakly by iron. it is therefore suggested that the s. xylosus ... | 2001 | 11526011 |
| characterization by 16s rrna sequence analysis of pseudomonads causing blotch disease of cultivated agaricus bisporus. | bacterial blotch of agaricus bisporus has typically been identified as being caused by either pseudomonas tolaasii (brown blotch) or pseudomonas gingeri (ginger blotch). to address the relatedness of pseudomonads able to induce blotch, a pilot study was initiated in which pseudomonads were selectively isolated from mushroom farms throughout new zealand. thirty-three pseudomonad isolates were identified as being capable of causing different degrees of discoloration (separable into nine categories ... | 2001 | 11526038 |
| ectopic transposition of a group ii intron in natural bacterial populations. | self-splicing group ii introns are thought to be the evolutionary progenitors of eukaryotic spliceosomal introns. the invasion of novel (ectopic) sites by group ii introns is considered to be a key mechanism by which spliceosomal introns may have become widely dispersed. however, the dynamics of these events in populations are unknown. in bacteria, only two group ii introns have been shown to splice and to be mobile in vivo. one of these introns, rmint1 from sinorhizobium meliloti, which encodes ... | 2001 | 11532132 |
| the emerging periplasm-localized subclass of aroq chorismate mutases, exemplified by those from salmonella typhimurium and pseudomonas aeruginosa. | chorismate mutases of the aroq homology class are widespread in the bacteria and the archaea. many of these exist as domains that are fused with other aromatic-pathway catalytic domains. among the monofunctional aroq proteins, that from erwinia herbicola was previously shown to have a cleavable signal peptide and located in the periplasmic compartment. whether or not this might be unique to e. herbicola was unknown. | 2001 | 11532214 |
| identification of the heat-shock sigma factor rpoh and a second rpoh-like protein in sinorhizobium meliloti. | hybridization to a pcr product derived from conserved sigma-factor sequences led to the identification of two sinorhizobium meliloti dna segments that display significant sequence similarity to the family of rpoh genes encoding the sigma(32) (rpoh) heat-shock transcription factors. the first gene, rpoh1, complements an escherichia coli rpoh mutation. cells containing an rpoh1 mutation are impaired in growth at 37 degrees c under free-living conditions and are defective in nitrogen fixation durin ... | 2001 | 11535780 |
| plant gene expression response to agrobacterium tumefaciens. | to elucidate the nature of plant response to infection and transformation by agrobacterium tumefaciens, we compared the cdna-amplified fragment length polymorphism (aflp) pattern of agrobacterium- and mock-inoculated ageratum conyzoides plant cell cultures. from 16,000 cdna fragments analyzed, 251 (1.6%) were differentially regulated (0.5% down-regulated) 48 h after cocultivation with agrobacterium. from 75 strongly regulated fragments, 56 were already regulated 24 h after cocultivation. sequenc ... | 2001 | 11535836 |
| binding of transcriptional activators to sigma 54 in the presence of the transition state analog adp-aluminum fluoride: insights into activator mechanochemical action. | conformational changes in sigma 54 (sigma(54)) and sigma(54)-holoenzyme depend on nucleotide hydrolysis by an activator. we now show that sigma(54) and its holoenzyme bind to the central atp-hydrolyzing domains of the transcriptional activators pspf and nifa in the presence of adp-aluminum fluoride, an analog of atp in the transition state for hydrolysis. direct binding of sigma(54) region i to activator in the presence of adp-aluminum fluoride was shown and inferred from in vivo suppression gen ... | 2001 | 11544185 |
| enhancer-binding proteins hrpr and hrps interact to regulate hrp-encoded type iii protein secretion in pseudomonas syringae strains. | in pseudomonas syringae strains, the hrp-hrc pathogenicity island consists of an hrpl-dependent regulon that encodes a type iii protein translocation complex and translocated effector proteins required for pathogenesis. hrpr and hrps function as positive regulatory factors for the hrpl promoter, but their mechanism of action has not been established. both hrpr and hrps are structurally related to enhancer-binding proteins, but they lack receiver domains and do not appear to require a cognate pro ... | 2001 | 11544221 |
| mtnk, methylthioribose kinase, is a starvation-induced protein in bacillus subtilis. | methylthioadenosine, the main by-product of spermidine synthesis, is degraded in bacillus subtilis as adenine and methylthioribose. the latter is an excellent sulfur source and the precursor of quorum-sensing signalling molecules. nothing was known about methylthioribose recycling in this organism. | 2001 | 11545674 |
| molecular cloning of a bacteroides caccae tonb-linked outer membrane protein identified by an inflammatory bowel disease marker antibody. | commensal enteric bacteria are a required pathogenic factor in inflammatory bowel disease (ibd), but the identity of the pertinent bacterial species is unresolved. using an ibd-associated panca monoclonal antibody, a 100-kda protein was recently characterized from an ibd clinical isolate of bacteroides caccae (p2lc3). in this study, consensus oligonucleotides were designed from 100-kda peptides and used to identify a single-copy gene from the p2lc3 genome. sequence analysis of the genomic clone ... | 2001 | 11553542 |
| identification of a new iron-regulated virulence gene, irea, in an extraintestinal pathogenic isolate of escherichia coli. | our laboratory is studying an extraintestinal pathogenic isolate of escherichia coli (cp9) as a model pathogen. we have been using human urine, ascites, and blood ex vivo to identify genes with increased expression in these media relative to expression in luria-bertani (lb) broth. such genes may represent new or unrecognized virulence traits. in this study, we report the identification of a new gene, irea (iron-responsive element). this gene has an open reading frame of 2,049 nucleotides, and it ... | 2001 | 11553562 |
| ferrochelatase is present in brucella abortus and is critical for its intracellular survival and virulence. | brucella spp. are pathogenic bacteria that cause brucellosis, an animal disease which can also affect humans. although understanding the pathogenesis is important for the health of animals and humans, little is known about virulence factors associated with it. in order for chronic disease to be established, brucella spp. have developed the ability to survive inside phagocytes by evading cell defenses. it hides inside vacuoles, where it then replicates, indicating that it has an active metabolism ... | 2001 | 11553564 |
| srchi24, a chitinase homolog lacking an essential glutamic acid residue for hydrolytic activity, is induced during nodule development on sesbania rostrata. | the interaction between the tropical legume sesbania rostrata and the bacterium azorhizobium caulinodans results in the formation of nodules on both stem and roots. stem nodulation was used as a model system to isolate early markers by differential display. one of them, srchi24 is a novel early nodulin whose transcript level increased already 4 h after inoculation. this enhancement depended on nod factor-producing bacteria. srchi24 transcript levels were induced also by exogenous cytokinins. in ... | 2001 | 11553736 |
| novel pathway for phosphatidylcholine biosynthesis in bacteria associated with eukaryotes. | phosphatidylcholine (pc) is the major membrane-forming phospholipid in eukaryotes and can be synthesised by either of two pathways, the cdp-choline pathway or the methylation pathway. many prokaryotes lack pc, but it can be found in significant amounts in membranes of distantly related bacteria such as rhizobacteria and spirochetes. enzymatic methylation of phosphatidylethanolamine via the methylation pathway was thought to be the only biosynthetic pathway to yield pc in bacteria. however, a nov ... | 2001 | 11566392 |
| genetic locus required for antigenic maturation of rhizobium etli ce3 lipopolysaccharide. | rhizobium etli modifies lipopolysaccharide (lps) structure in response to environmental signals, such as low ph and anthocyanins. these lps modifications result in the loss of reactivity with certain monoclonal antibodies. the same antibodies fail to recognize previously isolated r. etli mutant strain ce367, even in the absence of such environmental cues. chemical analysis of the lps in strain ce367 demonstrated that it lacked the terminal sugar of the wild-type o antigen, 2,3,4-tri-o-methylfuco ... | 2001 | 11567006 |
| group-specific monitoring of phenol hydroxylase genes for a functional assessment of phenol-stimulated trichloroethylene bioremediation. | the sequences of the largest subunit of bacterial multicomponent phenol hydroxylases (lmphs) were compared. it was found that lmphs formed three phylogenetic groups, i, ii, and iii, corresponding to three previously reported kinetic groups, low-k(s) (the half-saturation constant in haldane's equation for trichloroethylene [tce]), moderate-k(s), and high-k(s) groups. consensus sequences and specific amino acid residues for each group of lmph were found, which facilitated the design of universal a ... | 2001 | 11571171 |
| bulk and rhizosphere soil bacterial communities studied by denaturing gradient gel electrophoresis: plant-dependent enrichment and seasonal shifts revealed. | the bacterial rhizosphere communities of three host plants of the pathogenic fungus verticillium dahliae, field-grown strawberry (fragaria ananassa duch.), oilseed rape (brassica napus l.), and potato (solanum tuberosum l.), were analyzed. we aimed to determine the degree to which the rhizosphere effect is plant dependent and whether this effect would be increased by growing the same crops in two consecutive years. rhizosphere or soil samples were taken five times over the vegetation periods. to ... | 2001 | 11571180 |
| genome sequence of an industrial microorganism streptomyces avermitilis: deducing the ability of producing secondary metabolites. | streptomyces avermitilis is a soil bacterium that carries out not only a complex morphological differentiation but also the production of secondary metabolites, one of which, avermectin, is commercially important in human and veterinary medicine. the major interest in this genus streptomyces is the diversity of its production of secondary metabolites as an industrial microorganism. a major factor in its prominence as a producer of the variety of secondary metabolites is its possession of several ... | 2001 | 11572948 |
| on the species of origin: diagnosing the source of symbiotic transcripts. | most organisms have developed ways to recognize and interact with other species. symbiotic interactions range from pathogenic to mutualistic. some molecular mechanisms of interspecific interaction are well understood, but many remain to be discovered. expressed sequence tags (ests) from cultures of interacting symbionts can help identify transcripts that regulate symbiosis, but present a unique challenge for functional analysis. given a sequence expressed in an interaction between two symbionts, ... | 2001 | 11574056 |
| promoter-specific involvement of the fixj receiver domain in transcriptional activation. | the "two-component" fixlj system activates nitrogen fixation genes via nifa and fixk in sinorhizobium meliloti. like other response regulators, the fixj protein can be decomposed into an n-terminal phosphorylatable "receiver" domain fixjn and a c-terminal transcriptional activator domain fixjc. the fixjn receiver domain was known to regulate activity of fixjc negatively at the nifa promoter. here we show a different situation at the fixk promoter where fixjn also contributes positively to transc ... | 2001 | 11575915 |
| identification of the partitioning site within the repabc-type replicon of the composite paracoccus versutus plasmid ptav1. | the replicator region of composite plasmid ptav1 of paracoccus versutus (included in mini-replicon ptav320) belongs to the family of repabc replicons commonly found in plasmids harbored by agrobacterium and rhizobium spp. the repabc replicons encode three genes clustered in an operon, which are involved in partitioning (repa and repb) and replication (repc). in order to localize the partitioning site of ptav320, the two identified incompatibility determinants of this mini-replicon (inc1, located ... | 2001 | 11591666 |
| tspo as a modulator of the repressor/antirepressor (ppsr/appa) regulatory system in rhodobacter sphaeroides 2.4.1. | the tspo outer membrane protein of rhodobacter sphaeroides has been shown to be involved in controlling the transcription of a number of genes which encode enzymes involved in photopigment biosynthesis and the puc operon. the display of regulated genes appears identical to those genes encompassing the ppsr/appa repressor/antirepressor regulon, although the effect of tspo is modest relative to that of ppsr/appa. to directly address the hypothesis that tspo is effective through the ppsr/appa syste ... | 2001 | 11591680 |
| genetic analysis of the sinorhizobium meliloti baca protein: differential effects of mutations on phenotypes. | sinorhizobium meliloti strains lacking baca function are impaired in symbiosis with alfalfa host plants and display altered sensitivities to a number of compounds relative to wild-type strains. with the goal of finding clues to the currently unknown biological function(s) of baca, we carried out a genetic analysis to determine which amino acids are critical for protein function and to attempt to ascertain whether the multiple phenotypes that result from a baca-null allele were the result of a co ... | 2001 | 11591690 |
| the esat-6 gene cluster of mycobacterium tuberculosis and other high g+c gram-positive bacteria. | the genome of mycobacterium tuberculosis h37rv has five copies of a cluster of genes known as the esat-6 loci. these clusters contain members of the cfp-10 (lhp) and esat-6 (esat-6) gene families (encoding secreted t-cell antigens that lack detectable secretion signals) as well as genes encoding secreted, cell-wall-associated subtilisin-like serine proteases, putative abc transporters, atp-binding proteins and other membrane-associated proteins. these membrane-associated and energy-providing pro ... | 2001 | 11597336 |
| characterization of a brucella species 25-kilobase dna fragment deleted from brucella abortus reveals a large gene cluster related to the synthesis of a polysaccharide. | in the present study we completed the nucleotide sequence of a brucella melitensis 16m dna fragment deleted from b. abortus that accounts for 25,064 bp and show that the other brucella spp. contain the entire 25-kb dna fragment. two short direct repeats of four nucleotides, detected in the b. melitensis 16m dna flanking both sides of the fragment deleted from b. abortus, might have been involved in the deletion formation by a strand slippage mechanism during replication. in addition to omp31, co ... | 2001 | 11598046 |
| identification of a group 1-like capsular polysaccharide operon for vibrio vulnificus. | virulence of vibrio vulnificus correlates with changes in colony morphology that are indicative of a reversible phase variation for expression of capsular polysaccharide (cps). encapsulated variants are virulent with opaque colonies, whereas phase variants with reduced cps expression are attenuated and are translucent. using tnphoa mutagenesis, we identified a v. vulnificus cps locus, which included an upstream ops element, a wza gene (wza(vv)), and several open reading frames with homology to c ... | 2001 | 11598064 |
| overlapping plant signal transduction pathways induced by a parasitic nematode and a rhizobial endosymbiont. | root-knot nematodes and rhizobia establish interactions with roots characterized by the de novo induction of host structures, termed giant cells and nodules, respectively. two transcription regulators, phan and knox, required for the establishment of meristems were previously shown to be expressed in tomato giant cells. we isolated the orthologues of phan and knox (mt-phan and mt-knox-1) from the model legume medicago truncatula, and established the spatial distribution of their expression in si ... | 2001 | 11605956 |
| differential effects of replacing escherichia coli ribosomal protein l27 with its homologue from aquifex aeolicus. | the rpma gene, which encodes 50s ribosomal subunit protein l27, was cloned from the extreme thermophile aquifex aeolicus, and the protein was overexpressed and purified. comparison of the a. aeolicus protein with its homologue from escherichia coli by circular dichroism analysis and proton nuclear magnetic resonance spectroscopy showed that it readily adopts some structure in solution that is very stable, whereas the e. coli protein is unstructured under the same conditions. a mutant of e. coli ... | 2001 | 11673426 |
| presence of prokaryotic and eukaryotic species in all subgroups of the pp(i)-dependent group ii phosphofructokinase protein family. | inorganic pyrophosphate-dependent phosphofructokinase (pp(i)-pfk) of the amitochondriate eukaryote mastigamoeba balamuthi was sequenced and showed about 60% identity to pp(i)-pfks from two eubacteria, propionibacterium freudenreichii and sinorhizobium meliloti. these gene products represent a newly recognized lineage of pfks. all four lineages of group ii pfks, as defined by phylogenetic analysis, contained both prokaryotic and eukaryotic species, underlining the complex evolutionary history of ... | 2001 | 11673446 |
| sphingomonas alaskensis strain afo1, an abundant oligotrophic ultramicrobacterium from the north pacific. | numerous studies have established the importance of picoplankton (microorganisms of < or =2 microm in length) in energy flow and nutrient cycling in marine oligotrophic environments, and significant effort has been directed at identifying and isolating heterotrophic picoplankton from the world's oceans. using a method of diluting natural seawater to extinction followed by monthly subculturing for 12 months, a bacterium was isolated that was able to form colonies on solid medium. the strain was i ... | 2001 | 11679312 |
| dna sequence and mutational analysis of rhizobitoxine biosynthesis genes in bradyrhizobium elkanii. | we cloned and sequenced a cluster of genes involved in the biosynthesis of rhizobitoxine, a nodulation enhancer produced by bradyrhizobium elkanii. the nucleotide sequence of the cloned 28.4-kb dna region encompassing rtxa showed that several open reading frames (orfs) were located downstream of rtxa. a large-deletion mutant of b. elkanii, usda94 delta rtx::omega 1, which lacks rtxa, orf1 (rtxc), orf2, and orf3, did not produce rhizobitoxine, dihydrorhizobitoxine, or serinol. the broad-host-rang ... | 2001 | 11679318 |
| identification of disulfides from the biodegradation of dibenzothiophene. | several investigations have identified benzothiophene-2,3-dione in the organic solvent extracts of acidified cultures degrading dibenzothiophene via the kodama pathway. in solution at neutral ph, the 2,3-dione exists as 2-mercaptophenylglyoxylate, which cyclizes upon acidification and is extracted as the 2,3-dione. the fate of these compounds in microbial cultures has never been determined. this study investigated the abiotic reactions of 2-mercaptophenylglyoxylate incubated aerobically in miner ... | 2001 | 11679330 |
| purification and properties of a glucuronan lyase from sinorhizobium meliloti m5n1cs (ncimb 40472). | a glucuronan lyase extracted from sinorhizobium meliloti strain m5n1cs was purified to homogeneity by anion-exchange chromatography. the purified enzyme corresponds to a monomer with a molecular mass of 20 kda and a pi of 4.9. a specific activity was found only for polyglucuronates leading to the production of 4,5-unsaturated oligoglucuronates. the enzyme activity was optimal at ph 6.5 and 50 degrees c. zn(2+), cu(2+), and hg(2+) (1 mm) inhibited the enzyme activity. no homology of the enzyme n- ... | 2001 | 11679345 |
| an altered pseudomonas diversity is recovered from soil by using nutrient-poor pseudomonas-selective soil extract media. | we designed five pseudomonas-selective soil extract naa media containing the selective properties of trimethoprim and sodium lauroyl sarcosine and 0 to 100% of the amount of casamino acids used in the classical pseudomonas-selective gould's s1 medium. all of the isolates were confirmed to be pseudomonas by a pseudomonas-specific oprf antibody and a pseudomonas-specific pcr targeting 16s ribosomal dna. the pseudomonas isolates were characterized by classical physiological tests, repetitive extrag ... | 2001 | 11679350 |
| concentrations of copper thought to be toxic to escherichia coli can induce the viable but nonculturable condition. | we have determined that concentrations of copper considered to be toxic can induce a fraction of a population of escherichia coli to enter the viable but nonculturable (vbnc) condition. copper-induced vbnc cells could be resuscitated for up to 2 weeks after entering the vbnc state. | 2001 | 11679363 |
| cloning and characterization of a second acid phosphatase from sinorhizobium meliloti strain 104a14. | sinorhizobium meliloti has two nonspecific periplasmic acid phosphatases. the napd enzyme has been previously described, and a second acid phosphatase, nape, is described in this report. nape was partially purified from an s. meliloti napd mutant and characterized with respect to molecular mass and substrate range. as predicted from sds-page analysis, the subunit molecular mass of nape is approximately 35.8 kda and gel filtration experiments estimated the native molecular mass to be approximatel ... | 2001 | 11685369 |
| the plant oncogene rold encodes a functional ornithine cyclodeaminase. | the plant oncogene rold stimulates the reproductive phase transition in plants. we define here the function of its gene product. we show that the rold protein bears sequence homology with ornithine cyclodeaminase, an uncommon enzyme of specialized-niche eubacteria and archaea that catalyzes the unusual nad(+)-dependent conversion of ornithine to proline. to confirm the prediction of the bioinformatic analysis, the rold protein was expressed in escherichia coli and purified. an ornithine-dependen ... | 2001 | 11687622 |
| retrotransposition of a yeast group ii intron occurs by reverse splicing directly into ectopic dna sites. | group ii introns, the presumed ancestors of nuclear pre-mrna introns, are site-specific retroelements. in addition to "homing" to unoccupied sites in intronless alleles, group ii introns transpose at low frequency to ectopic sites that resemble the normal homing site. two general mechanisms have been proposed for group ii intron transposition, one involving reverse splicing of the intron rna directly into an ectopic dna site, and the other involving reverse splicing into a site in rna followed b ... | 2001 | 11687644 |
| predictive and interpretive simulation of green fluorescent protein expression in reporter bacteria. | we have formulated a numerical model that simulates the accumulation of green fluorescent protein (gfp) in bacterial cells from a generic promoter-gfp fusion. the model takes into account the activity of the promoter, the time it takes gfp to mature into its fluorescent form, the susceptibility of gfp to proteolytic degradation, and the growth rate of the bacteria. from the model, we derived a simple formula with which promoter activity can be inferred easily and quantitatively from actual measu ... | 2001 | 11698362 |
| cloning and characterization of the pyruvate carboxylase from sinorhizobium meliloti rm1021. | the gene encoding pyruvate carboxylase (pyc) was isolated from a sinorhizobium meliloti rm1021 cosmid bank by complementation of a rhizobium tropici pyc mutant. pyc-negative mutants of s. meliloti rm1021 were isolated by transposon mutagenesis and were unable to grow with glucose or pyruvate as sole carbon sources, but were symbiotically competent in combination with alfalfa plants. pyc activity assays, pyc::lacz gene fusion studies and an in vivo biotinylation assay showed that pyc activity in ... | 2001 | 11702077 |
| dna adenine methylase is essential for viability and plays a role in the pathogenesis of yersinia pseudotuberculosis and vibrio cholerae. | salmonella strains that lack or overproduce dna adenine methylase (dam) elicit a protective immune response to different salmonella species. to generate vaccines against other bacterial pathogens, the dam genes of yersinia pseudotuberculosis and vibrio cholerae were disrupted but found to be essential for viability. overproduction of dam significantly attenuated the virulence of these two pathogens, leading to, in yersinia, the ectopic secretion of virulence proteins (yersinia outer proteins) an ... | 2001 | 11705940 |
| brucella abortus genes identified following constitutive growth and macrophage infection. | the chronicity of brucella abortus infection in humans and animals depends on the organism's ability to escape host defenses by gaining entry and surviving inside the macrophage. although no human vaccine exists for brucella, vaccine development in other bacteria has been based on deletions of selective nutritional as well as regulatory systems. our goal is to develop a vaccine for brucella. to further this aim, we have used a green fluorescent protein (gfp) reporter system to identify constitut ... | 2001 | 11705955 |
| application of high-density array-based signature-tagged mutagenesis to discover novel yersinia virulence-associated genes. | yersinia pestis, the causative agent of plague, and the enteropathogen yersinia pseudotuberculosis have nearly identical nucleotide similarity yet cause markedly different diseases. to investigate this conundrum and to study yersinia pathogenicity, we developed a high-density oligonucleotide array-based modification of signature-tagged mutagenesis (stm). y. pseudotuberculosis ypiii mutants constructed with the tagged transposons were evaluated in the murine yersiniosis infection model. the dna t ... | 2001 | 11705963 |
| salmonella dna adenine methylase mutants elicit protective immune responses to homologous and heterologous serovars in chickens. | salmonella dna adenine methylase (dam) mutants that lack or overproduce dam are highly attenuated for virulence in mice and confer protection against murine typhoid fever. to determine whether vaccines based on dam are efficacious in poultry, a salmonella dam(-) vaccine was evaluated in the protection of chicken broilers against oral challenge with homologous and heterologous salmonella serovars. a salmonella enterica serovar typhimurium dam(-) vaccine strain was attenuated for virulence in day- ... | 2001 | 11705984 |
| the role of ndr1 in avirulence gene-directed signaling and control of programmed cell death in arabidopsis. | arabidopsis plants containing the ndr1-1 mutation are incapable of mounting a hypersensitive response to bacteria carrying avrrpt2, but show an exaggerated cell death response to bacteria carrying avrb (century et al., 1995). we show here that ndr1-1 plants are severely impaired in induction of systemic acquired resistance and pr1-driven transcription of a reporter gene in response to pseudomonas syringae strains carrying avrrpt2 but not in response to p. syringae carrying avrb. the ndr1-1 mutat ... | 2001 | 11706189 |
| structure of thermotoga maritima stationary phase survival protein sure: a novel acid phosphatase. | the rpos, nlpd, pcm, and sure genes are among many whose expression is induced during the stationary phase of bacterial growth. rpos codes for the stationary-phase rna polymerase sigma subunit, and nlpd codes for a lipoprotein. the pcm gene product repairs damaged proteins by converting the atypical isoaspartyl residues back to l-aspartyls. the physiological and biochemical functions of sure are unknown, but its importance in stress is supported by the duplication of the sure gene in e. coli sub ... | 2001 | 11709173 |
| gene yerp, involved in surfactin self-resistance in bacillus subtilis. | surfactin is a cyclic lipopeptide biosurfactant. transposon mutagenesis was performed in bacillus subtilis strain 168, and a surfactin-susceptible mutant, strain 801, was isolated. analysis of the region of insertion revealed that yerp was the determinant of surfactin self-resistance. yerp had homology with the resistance, nodulation, and cell division (rnd) family proton motive force-dependent efflux pumps only characterized in gram-negative strains. the yerp-deficient strain 802, in which the ... | 2001 | 11709341 |
| regulation of gene expression in response to oxygen in rhizobium etli: role of fnrn in fixnoqp expression and in symbiotic nitrogen fixation. | previously, we reported finding duplicated fixnoqp operons in rhizobium etli cfn42. one of these duplicated operons is located in the symbiotic plasmid (fixnoqpd), while the other is located in a cryptic plasmid (fixnoqpf). although a novel fixl-fixkf regulatory cascade participates in microaerobic expression of both fixnoqp duplicated operons, we found that a mutation in fixl eliminates fixnoqpf expression but has only a moderate effect on expression of fixnoqpd. this suggests that there are di ... | 2001 | 11717256 |
| identification of essential amino acids in the azorhizobium caulinodans fucosyltransferase nodz. | the nodz gene, which is present in various rhizobial species, is involved in the addition of a fucose residue in an alpha 1-6 linkage to the reducing n-acetylglucosamine residue of lipo-chitin oligosaccharide signal molecules, the so-called nod factors. fucosylation of nod factors is known to affect nodulation efficiency and host specificity. despite a lack of overall sequence identity, nodz proteins share conserved peptide motifs with mammalian and plant fucosyltransferases that participate in ... | 2001 | 11717264 |
| cher- and cheb-dependent chemosensory adaptation system of rhodobacter sphaeroides. | rhodobacter sphaeroides has multiple homologues of most of the escherichia coli chemotaxis genes, organized in three major operons and other, unlinked, loci. these include chea(1) and cher(1) (che op(1)) and chea(2), cher(2), and cheb(1) (che op(2)). in-frame deletions of these cher and cheb homologues were constructed and the chemosensory behaviour of the resultant mutants examined on swarm plates and in tethered cell assays. under the conditions tested, cher(2) and cheb(1) were essential for n ... | 2001 | 11717272 |
| redox signal transduction by the arcb sensor kinase of haemophilus influenzae lacking the pas domain. | the arc (anoxic redox control) two-component signal transduction system of escherichia coli, which comprises the tripartite arcb sensor kinase and the arca response regulator, modulates the expression of numerous operons in response to redox conditions of growth. we demonstrate that the arca and arcb genes of haemophilus influenzae specify a two-component system. the arc proteins of the two bacterial species sufficiently resemble each other that they can participate in heterologous transphosphor ... | 2001 | 11717280 |
| improved soybean root association of n-starved bradyrhizobium japonicum. | in this study, we addressed the effects of n limitation in bradyrhizobium japonicum for its association with soybean roots. the wild-type strain lp 3001 grew for six generations with a growth rate of 1.2 day(-1) in a minimal medium with 28 mm mannitol as the carbon source and with the n source [(nh(4))(2)so(4)] limited to only 20 microm. under these conditions, the glutamine synthetase (gs) activity was five to six times higher than in similar cultures grown with 1 or 0.1 mm (nh(4))(2)so(4). the ... | 2001 | 11717284 |
| evidence for structurally specific negative feedback in the nod factor signal transduction pathway. | nod factor is a critical signalling molecule in the establishment of the legume/rhizobial symbiosis. the nod factor of sinorhizobium meliloti carries o-sulphate, o-acetate and c16:2 n-acyl attachments that define its activity and host specificity. here we assess the relative importance of these modifications for the induction of calcium spiking in medicago truncatula. we find that nod factor structures lacking the o-sulphate, structures lacking the o-acetate and n-acyl groups, and structures lac ... | 2001 | 11722762 |
| proteins induced during adaptation of acetobacter aceti to high acetate concentrations. | as a typical product of microbial metabolism, the weak acid acetate is well known for its cytotoxic effects. in contrast to most other microbes, the so-called acetic acid bacteria can acquire significant resistance to high acetate concentrations when properly adapted to such hostile conditions. to characterize the molecular events that are associated with this adaptation, we analyzed global protein expression levels during adaptation of acetobacter aceti by two-dimensional gel electrophoresis. a ... | 2001 | 11722895 |