Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| eds1, an essential component of r gene-mediated disease resistance in arabidopsis has homology to eukaryotic lipases. | a major class of plant disease resistance (r) genes encodes leucine-rich-repeat proteins that possess a nucleotide binding site and amino-terminal similarity to the cytoplasmic domains of the drosophila toll and human il-1 receptors. in arabidopsis thaliana, eds1 is indispensable for the function of these r genes. the eds1 gene was cloned by targeted transposon tagging and found to encode a protein that has similarity in its amino-terminal portion to the catalytic site of eukaryotic lipases. thu ... | 1999 | 10077677 |
| the mxi-spa type iii secretory pathway of shigella flexneri requires an outer membrane lipoprotein, mxim, for invasin translocation. | invasion of epithelial cells by shigella flexneri is mediated by a set of translocated bacterial invasins, the ipa proteins, and its dedicated type iii secretion system, called mxi-spa. we show here that mxim, part of the mxi-spa locus in the s. flexneri virulence plasmid, encodes an indispensable type iii secretion apparatus component, required for both ipa translocation and tissue culture cell invasion. we demonstrated that mature mxim, first identified as a putative lipoprotein, is lipidated ... | 1999 | 10085046 |
| degradation of 1,2-dibromoethane by mycobacterium sp. strain gp1. | the newly isolated bacterial strain gp1 can utilize 1, 2-dibromoethane as the sole carbon and energy source. on the basis of 16s rrna gene sequence analysis, the organism was identified as a member of the subgroup which contains the fast-growing mycobacteria. the first step in 1,2-dibromoethane metabolism is catalyzed by a hydrolytic haloalkane dehalogenase. the resulting 2-bromoethanol is rapidly converted to ethylene oxide by a haloalcohol dehalogenase, in this way preventing the accumulation ... | 1999 | 10094681 |
| characterization of the pyoluteorin biosynthetic gene cluster of pseudomonas fluorescens pf-5. | ten genes (plt) required for the biosynthesis of pyoluteorin, an antifungal compound composed of a bichlorinated pyrrole linked to a resorcinol moiety, were identified within a 24-kb genomic region of pseudomonas fluorescens pf-5. the deduced amino acid sequences of eight plt genes were similar to the amino acid sequences of genes with known biosynthetic functions, including type i polyketide synthases (pltb, pltc), an acyl coenzyme a (acyl-coa) dehydrogenase (plte), an acyl-coa synthetase (pltf ... | 1999 | 10094695 |
| cellular locations of pseudomonas syringae pv. syringae hrcc and hrcj proteins, required for harpin secretion via the type iii pathway. | the complete hrp-hrc-hrma cluster of pseudomonas syringae pv. syringae 61 encodes 28 polypeptides. a saprophytic bacterium carrying this cluster is capable of secreting hrpz-a harpin encoded by hrpz-in an hrp-dependent manner, which suggests that this cluster contains sufficient components to assemble functional type iii secretion machinery. sequence data show that hrcj and hrcc are putative outer membrane proteins, and nonpolar mutagenesis demonstrates they are all required for hrpz secretion. ... | 1999 | 10094714 |
| location and survival of leaf-associated bacteria in relation to pathogenicity and potential for growth within the leaf | the growth and survival of pathogenic and nonpathogenic pseudomonas syringae strains and of the nonpathogenic species pantoea agglomerans, stenotrophomonas maltophilia, and methylobacterium organophilum were compared in the phyllosphere of bean. in general, the plant pathogens survived better than the nonpathogens on leaves under environmental stress. the sizes of the total leaf-associated populations of the pathogenic p. syringae strains were greater than the sizes of the total leaf-associated ... | 1999 | 10103233 |
| cuma, a gene encoding a multicopper oxidase, is involved in mn2+ oxidation in pseudomonas putida gb-1. | pseudomonas putida gb-1-002 catalyzes the oxidation of mn2+. nucleotide sequence analysis of the transposon insertion site of a nonoxidizing mutant revealed a gene (designated cuma) encoding a protein homologous to multicopper oxidases. addition of cu2+ increased the mn2+-oxidizing activity of the p. putida wild type by a factor of approximately 5. the growth rates of the wild type and the mutant were not affected by added cu2+. a second open reading frame (designated cumb) is located downstream ... | 1999 | 10103278 |
| genetic analysis of biodegradation of tetralin by a sphingomonas strain. | a strain designated tfa which very efficiently utilizes tetralin has been isolated from the rhine river. the strain has been identified as sphingomonas macrogoltabidus, based on 16s rdna sequence similarity. genetic analysis of tetralin biodegradation has been performed by insertion mutagenesis and by physical analysis and analysis of complementation between the mutants. the genes involved in tetralin utilization are clustered in a region of 9 kb, comprising at least five genes grouped in two di ... | 1999 | 10103288 |
| identification of a novel ice-nucleating bacterium of antarctic origin and its ice nucleation properties. | a novel ice-nucleating bacterium (inb) was isolated from ross island, antarctica. inbs could be isolated more frequently than was generally thought. inb strain in-74 was found in the white colony group. strain in-74 was identified from its taxonomic characteristics as a novel inb, pseudomonas antarctica in-74. when strain in-74 was cultured aerobically in a medium consisting of the ice-nucleating broth (ph 7.0) for 6 days at 4 degrees c, the ice-nucleating activity of strain in-74 cells was obta ... | 1999 | 10191036 |
| transcriptional organization of the czc heavy-metal homeostasis determinant from alcaligenes eutrophus. | the czc system of alcaligenes eutrophus mediates resistance to cobalt, zinc, and cadmium through ion efflux catalyzed by the czccb2a cation-proton antiporter. dna sequencing of the region upstream of the czcnicbadrs determinant located on megaplasmid pmol30 revealed the 5' end of czcn and a gene for a mgtc-like protein which is transcribed in the orientation opposite that of czc. additional open reading frames upstream of czc had no homologs in the current databases. using oligonucleotide-probed ... | 1999 | 10198000 |
| azospirillum irakense produces a novel type of pectate lyase. | the pela gene from the n2-fixing plant-associated bacterium azospirillum irakense, encoding a pectate lyase, was isolated by heterologous expression in escherichia coli. nucleotide sequence analysis of the region containing pela indicated an open reading frame of 1,296 bp, coding for a preprotein of 432 amino acids with a typical amino-terminal signal peptide of 24 amino acids. n-terminal amino acid sequencing confirmed the processing of the protein in e. coli at the signal peptidase cleavage si ... | 1999 | 10198006 |
| characterization of two novel type i ribosome-inactivating proteins from the storage roots of the andean crop mirabilis expansa. | two novel type i ribosome-inactivating proteins (rips) were found in the storage roots of mirabilis expansa, an underutilized andean root crop. the two rips, named me1 and me2, were purified to homogeneity by ammonium sulfate precipitation, cation-exchange perfusion chromatography, and c4 reverse-phase chromatography. the two proteins were found to be similar in size (27 and 27.5 kd) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their isoelectric points were determined to be ... | 1999 | 10198104 |
| slow and prolonged activation of the p47 protein kinase during hypersensitive cell death in a culture of tobacco cells | to investigate the involvement of protein kinases in the signaling cascade that leads to hypersensitive cell death, we used a previously established system in which a fungal elicitor, xylanase from trichoderma viride (tvx), induces a hypersensitive reaction in tobacco (nicotiana tabacum) cells in culture (line xd6s). the elicitor induced the slow and prolonged activation of a p47 protein kinase, which has the characteristics of a family member of the mitogen-activated protein kinases. an inhibit ... | 1999 | 10198106 |
| a dispensable region of the chromosome which is associated with an avirulence gene in pseudomonas syringae pv. pisi. | pseudomonas syringae pv. pisi comprises a number of races which fall into two phylogenetically distinct groups (designated i and ii). races are based on cultivar specificity in the host plant, pea (pisum sativum), and are specified by the presence of avirulence genes. the avirulence gene avrppia1 is present on the chromosome of all strains examined in race 2, which belongs to phylogenetic group ii. a race 4b strain, from phylogenetic group i, lacks this avirulence gene and a comparative study wa ... | 1999 | 10206691 |
| biological and molecular detection of toxic lipodepsipeptide-producing pseudomonas syringae strains and pcr identification in plants | toxin-based identification procedures are useful for differentiating pseudomonas syringae pathovars. a biological test on peptone-glucose-nacl agar in which the yeast rhodotorula pilimanae was used proved to be more reliable for detecting lipodepsipeptide-producing strains of p. syringae than the more usual test on potato dextrose agar in which geotrichum candidum is used. a pcr test performed with primers designed to amplify a 1, 040-bp fragment in the coding sequence of the syrd gene, which wa ... | 1999 | 10223977 |
| genetic diversity of african and worldwide strains of ralstonia solanacearum as determined by pcr-restriction fragment length polymorphism analysis of the hrp gene region | the genetic diversity among a worldwide collection of 120 strains of ralstonia solanacearum was assessed by restriction fragment length polymorphism (rflp) analysis of amplified fragments from the hrp gene region. five amplified fragments appeared to be specific to r. solanacearum. fifteen different profiles were identified among the 120 bacterial strains, and a hierarchical cluster analysis distributed them into eight clusters. each cluster included strains belonging to a single biovar, except ... | 1999 | 10224018 |
| analysis of 16s-23s rrna intergenic spacer regions of vibrio cholerae and vibrio mimicus. | vibrio cholerae identification based on molecular sequence data has been hampered by a lack of sequence variation from the closely related vibrio mimicus. the two species share many genes coding for proteins, such as ctxab, and show almost identical 16s dna coding for rrna (rdna) sequences. primers targeting conserved sequences flanking the 3' end of the 16s and the 5' end of the 23s rdnas were used to amplify the 16s-23s rrna intergenic spacer regions of v. cholerae and v. mimicus. two major (c ... | 1999 | 10224020 |
| identification of three putative signal transduction genes involved in r gene-specified disease resistance in arabidopsis. | the rps5 disease resistance gene of arabidopsis mediates recognition of pseudomonas syringae strains that possess the avirulence gene avrpphb. by screening for loss of rps5-specified resistance, we identified five pbs (avrpphb susceptible) mutants that represent three different genes. mutations in pbs1 completely blocked rps5-mediated resistance, but had little to no effect on resistance specified by other disease resistance genes, suggesting that pbs1 facilitates recognition of the avrpphb prot ... | 1999 | 10224270 |
| molecular characterization of a flagellar export locus of helicobacter pylori. | motility of helicobacter species has been shown to be essential for successful colonization of the host. we have investigated the organization of a flagellar export locus in helicobacter pylori. a 7-kb fragment of the h. pylori ccug 17874 genome was cloned and sequenced, revealing an operon comprising an open reading frame of unknown function (orf03), essential housekeeping genes (iles and murb), flagellar export genes (flii and fliq), and a homolog to a gene implicated in virulence factor trans ... | 1999 | 10225855 |
| the interaction of lipodepsipeptide toxins from pseudomonas syringae pv. syringae with biological and model membranes: a comparison of syringotoxin, syringomycin, and two syringopeptins. | pseudomonas syringae pv. syringae produces two groups of cyclic lipodepsipeptides (ldps): the nona-peptides syringomycins, syringostatins, and syringotoxin (st), and the more complex syringopeptins composed of either 22 or 25 amino acid residues (sp22 and sp25). both classes of peptides significantly contribute to bacterial pathogenesis and their primary target of action seems to be the plasma membrane. we studied and compared the activity of some members of these two classes of ldps on red bloo ... | 1999 | 10226372 |
| conductive properties and gating of channels formed by syringopeptin 25a, a bioactive lipodepsipeptide from pseudomonas syringae pv. syringae, in planar lipid membranes. | syringopeptin 25a, a pseudomonad lipodepsipeptide, can form ion channels in planar lipid membranes. pore conductance is around 40 ps in 0.1 m nacl. channel opening is strongly voltage dependent and requires a negative potential on the same side of the membrane where the toxin was added. these pores open and close with a lifetime of several seconds. at negative voltages, an additional pore state of around 10 ps and a lifetime of around 30 ms is also present. the voltage dependence of the rates of ... | 1999 | 10226373 |
| studies on the cytoplasmic protein tyrosine kinase activity of the antarctic psychrotrophic bacterium pseudomonas syringae. | the antarctic psychrotrophic bacterium pseudomonas syringae contains a 66-kda cytoplasmic protein which was found to by phosphorylated on a tyrosine residue [ray, m.k. et al. (1994) fems microbiol. lett. 122, pp. 49-54]. to investigate the nature of the cytoplasmic protein tyrosine kinase and its role in the bacterial physiology, we carried out some biochemical studies of the enzyme in vitro in the presence of exogenous peptide substrates and expression studies in vivo at low and high temperatur ... | 1999 | 10227168 |
| dna relatedness among the pathovars of pseudomonas syringae and description of pseudomonas tremae sp. nov. and pseudomonas cannabina sp. nov. (ex sutic and dowson 1959). | a total of 48 pathovars of pseudomonas syringae and eight related species were studied by dna-dna hybridization (s1 nuclease method) and ribotyping. the existence of nine discrete genomospecies was indicated. genomospecies 1 corresponded to p. syringae sensu stricto and included p. syringae pathovars syringae, aptata, lapsa, papulans, pisi, atrofaciens, aceris, panici, dysoxyli and japonica. genomospecies 2 included p. syringae pathovars phaseolicola, ulmi, mori, lachrymans, sesami, tabaci, mors ... | 1999 | 10319466 |
| growth of azospirillum irakense kbc1 on the aryl beta-glucoside salicin requires either sala or salb. | the rhizosphere nitrogen-fixing bacterium azospirillum irakense kbc1 is able to grow on pectin and beta-glucosides such as cellobiose, arbutin, and salicin. two adjacent genes, sala and salb, conferring beta-glucosidase activity to escherichia coli, have been identified in a cosmid library of a. irakense dna. the sala and salb enzymes preferentially hydrolyzed aryl beta-glucosides. a delta(sala-salb) a. irakense mutant was not able to grow on salicin but could still utilize arbutin, cellobiose, ... | 1999 | 10321999 |
| identification and characterization of a gene cluster for synthesis of the polyketide antibiotic 2,4-diacetylphloroglucinol from pseudomonas fluorescens q2-87. | the polyketide metabolite 2,4-diacetylphloroglucinol (2,4-dapg) is produced by many strains of fluorescent pseudomonas spp. with biocontrol activity against soilborne fungal plant pathogens. genes required for 2,4-dapg synthesis by p. fluorescens q2-87 are encoded by a 6.5-kb fragment of genomic dna that can transfer production of 2,4-dapg to 2,4-dapg-nonproducing recipient pseudomonas strains. in this study the nucleotide sequence was determined for the 6.5-kb fragment and flanking regions of g ... | 1999 | 10322017 |
| a novel campylobacter jejuni two-component regulatory system important for temperature-dependent growth and colonization. | campylobacter jejuni colonizes the intestines of domestic and wild animals and is a common cause of human diarrheal disease. we identified a two-component regulatory system, designated the racr-racs (reduced ability to colonize) system, that is involved in a temperature-dependent signalling pathway. a mutation of the response regulator gene racr reduced the organism's ability to colonize the chicken intestinal tract and resulted in temperature-dependent changes in its protein profile and growth ... | 1999 | 10322038 |
| amplified-fragment length polymorphism analysis versus macro-restriction fragment analysis for molecular typing of streptococcus pneumoniae isolates. | forty-eight pneumococci were genotyped by on-line laser fluorescence amplified-fragment length polymorphism (aflp) and pulsed-field gel electrophoresis (pfge) analysis of chromosomal restriction fragments. overall, the data generated by the two methods corresponded well. however, with aflp, clusters were delineated at a higher similarity level, and isolate differentiation was more pronounced. aflp and pfge were equally efficient for assessing intraserotype diversity. we conclude that aflp is a u ... | 1999 | 10325379 |
| saccharomyces cerevisiae cells harboring the gene encoding sarcotoxin ia secrete a peptide that is toxic to plant pathogenic bacteria. | sarcotoxin ia is a cecropin-type antibacterial protein produced by the flesh fly, sarcophaga peregrina. similar to other bactericidal small proteins produced by insects, sarcotoxin ia is released into the hemolymph of larvae and nymphs upon mechanical injury or bacterial infection. the gene (sarco) that encodes this toxin was introduced into saccharomyces cerevisiae yeast cells and was expressed under a constitutive yeast promoter. the transformed yeast cells were grown in a liquid medium, and a ... | 1999 | 10336869 |
| identification and molecular analysis of rough-colony-specific outer membrane proteins of actinobacillus actinomycetemcomitans. | actinobacillus actinomycetemcomitans, a gram-negative bacterium isolated from the human mouth, has been implicated in the pathogenesis of early-onset periodontitis. primary isolates cultured from subgingival plaque exhibit an adherent, rough colony phenotype which spontaneously converts to a nonadherent, smooth phenotype upon in vitro subculture. the rough colony variant produces abundant fimbriae and autoaggregates, while the smooth colony variant is planktonic and produces scant fimbriae. to b ... | 1999 | 10338497 |
| interaction of npr1 with basic leucine zipper protein transcription factors that bind sequences required for salicylic acid induction of the pr-1 gene. | the arabidopsis thaliana npr1 has been shown to be a key regulator of gene expression during the onset of a plant disease-resistance response known as systemic acquired resistance. the npr1 mutant plants fail to respond to systemic acquired resistance-inducing signals such as salicylic acid (sa), or express sa-induced pathogenesis-related (pr) genes. using npr1 as bait in a yeast two-hybrid screen, we identified a subclass of transcription factors in the basic leucine zipper protein family (ahbp ... | 1999 | 10339621 |
| two-component transcriptional regulation of n-acyl-homoserine lactone production in pseudomonas aureofaciens. | production of phenazine antibiotics by the biological control bacterium pseudomonas aureofaciens 30-84 is regulated in part by the phzi/phzr n-acyl-homoserine lactone (ahl) response system (l. s. pierson iii, v. d. keppenne, and d. w. wood, j. bacteriol. 176:3966-3974, 1994; d. w. wood and l. s. pierson iii, gene 168:49-53, 1996). two mutants, 30-84w and 30-84.a2, were isolated and were found to be deficient in the production of phenazine, protease, hydrogen cyanide (hcn), and the ahl signal n-h ... | 1999 | 10347004 |
| quantitative immunofluorescence of regulated eps gene expression in single cells of ralstonia solanacearum. | ralstonia solanacearum, a phytopathogenic bacterium, uses an environmentally sensitive and complex regulatory network to control expression of multiple virulence genes. part of this network is an unusual autoregulatory system that produces and senses 3-hydroxypalmitic acid methyl ester. in culture, this autoregulatory system ensures that expression of virulence genes, such as those of the eps operon encoding biosynthesis of the acidic extracellular polysaccharide, occurs only at high cell densit ... | 1999 | 10347013 |
| mapping of sugar and amino acid availability in soil around roots with bacterial sensors of sucrose and tryptophan | we developed a technique to map the availability of sugars and amino acids along live roots in an intact soil-root matrix with native microbial soil flora and fauna present. it will allow us to study interactions between root exudates and soil microorganisms at the fine spatial scale necessary to evaluate mechanisms of nitrogen cycling in the rhizosphere. erwinia herbicola 299r harboring a promoterless ice nucleation reporter gene, driven by either of two nutrient-responsive promoters, was used ... | 1999 | 10347061 |
| characterization of plasmids that encode streptomycin-resistance in bacterial epiphytes of apple. | streptomycin resistance in strains of pseudomonas syringae pv. papulans, pantoea agglomerans and a yellow-pigmented, non-fluorescent pseudomonas sp. (py), isolated from apple orchards in new york and washington states, is predominantly associated with stra-strb genes carried on conjugal plasmids (r plasmids). none of 128 resistant erwinia amylovora strains from the eastern and western usa hybridized with a stra-strb probe, smp3. resistant py strains transfered r plasmids to ps. syringae pv. papu ... | 1999 | 10347868 |
| regulation of alginate biosynthesis in pseudomonas syringae pv. syringae. | both pseudomonas aeruginosa and the phytopathogen p. syringae produce the exopolysaccharide alginate. however, the environmental signals that trigger alginate gene expression in p. syringae are different from those in p. aeruginosa with copper being a major signal in p. syringae. in p. aeruginosa, the alternate sigma factor encoded by algt (sigma22) and the response regulator algr1 are required for transcription of algd, a gene which encodes a key enzyme in the alginate biosynthetic pathway. in ... | 1999 | 10348861 |
| cloning of the glutamyl-trna synthetase (gltx) gene from pseudomonas aeruginosa. | the glutamyl-trna synthetase (gltx) gene from pseudomonas aeruginosa was identified. a plasmid containing a 2.3-kb insert complemented the temperature-sensitive gltx mutation of escherichia coli jp1449, and gltx activity was demonstrated. the inferred amino acid sequence of this gene showed 50.6% identity with gltx from rhizobium meliloti. | 1999 | 10348873 |
| pseudomonas syringae phytotoxins: mode of action, regulation, and biosynthesis by peptide and polyketide synthetases. | coronatine, syringomycin, syringopeptin, tabtoxin, and phaseolotoxin are the most intensively studied phytotoxins of pseudomonas syringae, and each contributes significantly to bacterial virulence in plants. coronatine functions partly as a mimic of methyl jasmonate, a hormone synthesized by plants undergoing biological stress. syringomycin and syringopeptin form pores in plasma membranes, a process that leads to electrolyte leakage. tabtoxin and phaseolotoxin are strongly antimicrobial and func ... | 1999 | 10357851 |
| a bacteriophage encoding a pathogenicity island, a type-iv pilus and a phage receptor in cholera bacteria. | the virulence properties of many pathogenic bacteria are due to proteins encoded by large gene clusters called pathogenicity islands, which are found in a variety of human pathogens including escherichia coli, salmonella, shigella, yersinia, helicobacter pylori, vibrio cholerae, and animal and plant pathogens such as dichelobacter nodosus and pseudomonas syringae. although the presence of pathogenicity islands is a prerequisite for many bacterial diseases, little is known about their origins or ... | 1999 | 10360577 |
| characterization of the pseudomonas syringae pv. tomato avrrpt2 protein: demonstration of secretion and processing during bacterial pathogenesis. | pseudomonas syringae pv. tomato strain dc3000 (pst dc3000) expressing avrrpt2 is specifically recognized by plant cells expressing rps2 activity, resulting in localized cell death and plant resistance. furthermore, transient expression of this bacterial avrrpt2 gene in plant cells results in rps2-dependent cell death. this indicates that the avrrpt2 protein is recognized inside rps2 plant cells and is sufficient for the activation of disease resistance-mediated cell death in planta. we explored ... | 1999 | 10361296 |
| enhanced expression and activation of the alternative oxidase during infection of arabidopsis with pseudomonas syringae pv tomato. | cyanide-resistant ("alternative") respiration was studied in arabidopsis during incompatible and compatible infection with pseudomonas syringae pv tomato dc3000. total leaf respiration increased as the leaves became necrotic, as did the cyanide-resistant component that was sensitive to salicylhydroxamic acid. infiltration of leaves with an avirulent strain rapidly induced alternative oxidase (aox) mrna, whereas the increase was delayed in the compatible combination. the increase in mrna correlat ... | 1999 | 10364404 |
| the mdoc gene of escherichia coli encodes a membrane protein that is required for succinylation of osmoregulated periplasmic glucans. | osmoregulated periplasmic glucans (opgs) of escherichia coli are anionic oligosaccharides that accumulate in the periplasmic space in response to low osmolarity of the medium. their anionic character is provided by the substitution of the glucosidic backbone by phosphoglycerol originating from the membrane phospholipids and by succinyl residues from unknown origin. a phosphoglycerol-transferase-deficient mdob mutant was subjected to tn5 transposon mutagenesis, and putative mutant clones were scr ... | 1999 | 10368134 |
| bacterioferritin a modulates catalase a (kata) activity and resistance to hydrogen peroxide in pseudomonas aeruginosa. | we have cloned a 3.6-kb genomic dna fragment from pseudomonas aeruginosa harboring the rpoa, rplq, kata, and bfra genes. these loci are predicted to encode, respectively, (i) the alpha subunit of rna polymerase; (ii) the l17 ribosomal protein; (iii) the major catalase, kata; and (iv) one of two iron storage proteins called bacterioferritin a (bfra; cytochrome b1 or b557). our goal was to determine the contributions of kata and bfra to the resistance of p. aeruginosa to hydrogen peroxide (h2o2). ... | 1999 | 10368148 |
| constitutively active pto induces a prf-dependent hypersensitive response in the absence of avrpto. | resistance in tomato to pseudomonas syringae pv tomato (avrpto) is conferred by the gene pto in a gene-for-gene relationship. a hypersensitive disease resistance response (hr) is elicited when pto and avrpto are expressed experimentally within the same plant cell. the kinase capability of pto was required for avrpto-dependent hr induction. systematic mutagenesis of the activation segment of pto kinase confirmed the homologous p+1 loop as an avrpto-binding determinant. specific amino acid substit ... | 1999 | 10369664 |
| characterization of an arabidopsis thaliana receptor-like protein kinase gene activated by oxidative stress and pathogen attack. | an arabidopsis thaliana cdna clone that encodes a putative receptor-like protein kinase gene (at-rlk3) was characterized. the deduced 667-amino acid protein consists of an amino-terminal signal sequence, an extracellular domain, a single transmembrane domain, and a cytoplasmic domain with characteristics of serine/threonine protein kinase. because of the original features of its extracellular domain, the at-rlk3 protein is a member of a new class of receptor-like protein kinases. the at-rlk3 gen ... | 1999 | 10377997 |
| swarming by pseudomonas syringae b728a requires gacs (lema) and gaca but not the acyl-homoserine lactone biosynthetic gene ahli. | pseudomonas syringae pv. syringae b728a, a causal agent of bacterial brown spot on snap beans, swarms with a characteristic dendritic pattern on semisolid (0.4%) agar plates. filamentation of swarming cells of b728a was not observed. mutations in either the gacs (formerly lema) or gaca gene of b728a eliminate the ability of this p. syringae isolate to swarm without obvious effects on bacterial motility. three field isolates showed a similar dependence on gacs for swarming. since gacs and gaca mu ... | 1999 | 10383988 |
| ultraviolet radiation (uvr) sensitivity analysis and uvr survival strategies of a bacterial community from the phyllosphere of field-grown peanut (arachis hypogeae l.). | > abstract the short-term population dynamics of the culturable bacterial community from field-grown peanut (arachis hypogeae l.) was analyzed over three 2-day periods. as in other phyllosphere studies, significant numbers of pigmented organisms were detected, suggesting the importance of pigmentation in the colonization of this habitat. isolates were grouped according to pigmentation (orange, pink, yellow, nonpigmented), and the sensitivity of each isolate in the collection (n = 617) to ultravi ... | 1999 | 10384007 |
| phylogenetic analysis of particle-attached and free-living bacterial communities in the columbia river, its estuary, and the adjacent coastal ocean. | the columbia river estuary is a dynamic system in which estuarine turbidity maxima trap and extend the residence time of particles and particle-attached bacteria over those of the water and free-living bacteria. particle-attached bacteria dominate bacterial activity in the estuary and are an important part of the estuarine food web. pcr-amplified 16s rrna genes from particle-attached and free-living bacteria in the columbia river, its estuary, and the adjacent coastal ocean were cloned, and 239 ... | 1999 | 10388721 |
| cell surface display of human immunodeficiency virus type 1 gp120 on escherichia coli by using ice nucleation protein. | a new system designed for cell surface display of recombinant proteins on escherichia coli has been evaluated for expression of eukaryotic viral proteins. human immunodeficiency virus type 1 (hiv-1) gp120 was fused to the c terminus of ice nucleation protein (inp), an outer membrane protein of pseudomonas syringae. western blotting, immunofluorescence microscopy, fluorescence-activated cell-sorting analysis, whole-cell enzyme-linked immunosorbent assay, and ice nucleation activity assay confirme ... | 1999 | 10391850 |
| high gene density is conserved at syntenic loci of small and large grass genomes. | comparative genomic analysis at the genetic-map level has shown extensive conservation of the gene order between the different grass genomes in many chromosomal regions. however, little is known about the gene organization in grass genomes at the microlevel. comparison of gene-coding regions between maize, rice, and sorghum showed that the distance between the genes is correlated with the genome size. we have investigated the microcolinearity at lrk gene loci in the genomes of four grass species ... | 1999 | 10393983 |
| molecular basis of the interaction of salmonella with the intestinal mucosa. | salmonella is one of the most extensively characterized bacterial pathogens and is a leading cause of bacterial gastroenteritis. despite this, we are only just beginning to understand at a molecular level how salmonella interacts with its mammalian hosts to cause disease. studies during the past decade on the genetic basis of virulence of salmonella have significantly advanced our understanding of the molecular basis of the host-pathogen interaction, yet many questions remain. in this review, we ... | 1999 | 10398673 |
| a vibrio cholerae lysr homolog, aphb, cooperates with apha at the tcpph promoter to activate expression of the toxr virulence cascade. | we describe here a new member of the lysr family of transcriptional regulators, aphb, which is required for activation of the vibrio cholerae toxr virulence cascade. aphb activates the transcription of the tcpph operon in response to environmental stimuli, and this process requires cooperation with a second protein, apha. the expression of neither apha or aphb is strongly regulated by environmental stimuli, raising the possibility that the activities of the proteins themselves may be influenced ... | 1999 | 10400582 |
| a rna polymerase with transcriptional activity at 0 degrees c from the antarctic bacterium pseudomonas syringae. | a dna-dependent rna polymerase was purified from the antarctic psychrotrophic bacterium pseudomonas syringae. the rna polymerase showed a typical eubacterial subunit composition with beta, beta', alpha2 and sigma subunits. the subunits cross-reacted with antibodies raised against holoenzyme and the individual subunits of the rna polymerase of escherichia coli. however, the enzyme was considered unique, since unlike the rna polymerase of mesophilic e. coli it exhibited significant and consistent ... | 1999 | 10405167 |
| gut colonization by an ice nucleation active bacterium, erwinia (pantoea) ananas reduces the cold hardiness of mulberry pyralid larvae. | to evaluate the suitability of using ice nucleation active (ina) bacteria for the biological control of insect pests, the supercooling point (scp) of larvae of mulberry pyralid, glyphodes duplicalis, and silkworm, bombyx mori, ingesting ina strains of erwinia (pantoea) ananas and pseudomonas syringae was determined. mean scp of the guts of silkworm larvae ingesting ina strains of e. ananas ranged from -2.5 to -2.8 degrees c, being 5 degrees c higher than that in control treatments. similarly, me ... | 1999 | 10413571 |
| isolation of additional bacteriophages with genomes of segmented double-stranded rna. | eight different bacteriophages were isolated from leaves of pisum sativum, phaseolus vulgaris, lycopersicon esculentum, daucus carota sativum, raphanus sativum, and ocimum basilicum. all contain three segments of double-stranded rna and have genomic-segment sizes that are similar but not identical to those of previously described bacteriophage phi6. all appear to have lipid-containing membranes. the base sequences of some of the viruses are very similar but not identical to those of phi6. three ... | 1999 | 10419946 |
| structure of the o-polysaccharide of the lipopolysaccharide of pseudomonas syringae pv. garcae icmp 8047. | the composition and structure of the o-polysaccharide of the lipopolysaccharide of pseudomonas syringae pathovar garcae icmp 8047 were studied using methylation analyses, smith degradation, and 1h- and 13c-nmr spectroscopy, including two-dimensional correlation spectroscopy (cosy), total correlation spectroscopy (tocsy), nuclear overhauser effect spectroscopy (noesy), and h-detected 1h,13c heteronuclear multiple-quantum coherence (hmqc) experiments. the polysaccharide was found to contain l-rham ... | 1999 | 10424899 |
| genetic structure of natural populations of escherichia coli in wild hosts on different continents. | current knowledge of genotypic and phenotypic diversity in the species escherichia coli is based almost entirely on strains recovered from humans or zoo animals. in this study, we analyzed a collection of 202 strains obtained from 81 mammalian species representing 39 families and 14 orders in australia and the americas, as well as several reference strains; we also included a strain from a reptile and 10 from different families of birds collected in mexico. the strains were characterized genotyp ... | 1999 | 10427022 |
| the xanthomonas hrp type iii system secretes proteins from plant and mammalian bacterial pathogens. | studies of essential pathogenicity determinants in gram-negative bacteria have revealed the conservation of type iii protein secretion systems that allow delivery of virulence factors into host cells from plant and animal pathogens. ten of 21 hrp proteins of the plant pathogen xanthomonas campestris pv. vesicatoria have been suggested to be part of a type iii machinery. here, we report the hrp-dependent secretion of two avirulence proteins, avrbs3 and avrrxv, by x. campestris pv. vesicatoria str ... | 1999 | 10430949 |
| a bean cdna expressed during a hypersensitive reaction encodes a putative calcium-binding protein. | the hypersensitive reaction (hr) is an inducible plant response that is associated with disease resistance. it is characterized by rapid, localized cell death at the site of infection and is believed to inhibit the spread of invading pathogens. we have isolated a cdna clone, designated hra32 (for hypersensitive reaction associated), corresponding to an rna transcript that accumulates in bean during an hr. the predicted protein product of the hra32 cdna is an approximately 17 kda protein of 161 a ... | 1999 | 10432637 |
| rapid transcript accumulation of pathogenesis-related genes during an incompatible interaction in bacterial speck disease-resistant tomato plants. | in the yeast two-hybrid system, the pto kinase interacts with three putative transcription factors pti4, pti5 and pti6. the pti4/5/6 proteins contain a dna binding domain that recognizes and binds a dna sequence (5'-agccgcc3'; the 'pr box') present in the promoter region of a large number of genes encoding 'pathogenesis-related' (pr) proteins. we have now investigated the pathogen-induced expression of pr box-containing genes in tomato. we isolated a tomato osmotin gene that contains two pr boxe ... | 1999 | 10437829 |
| influence of a putative ecf sigma factor on expression of the major outer membrane protein, oprf, in pseudomonas aeruginosa and pseudomonas fluorescens. | the gene encoding oprf, a major outer membrane protein in pseudomonas species (formerly known as type 1 pseudomonads), was thought to be constitutively transcribed from a single sigma 70 promoter immediately upstream of the gene. we now report the identification of a novel putative ecf (extracytoplasmic function) sigma factor gene, sigx, located immediately upstream of oprf in both pseudomonas aeruginosa pao1 and pseudomonas fluorescens oe 28.3 and show that disruption of this gene significantly ... | 1999 | 10438740 |
| the avr (effector) proteins hrma (hoppsya) and avrpto are secreted in culture from pseudomonas syringae pathovars via the hrp (type iii) protein secretion system in a temperature- and ph-sensitive manner. | we present here data showing that the avr proteins hrma and avrpto are secreted in culture via the native hrp pathways from pseudomonas syringae pathovars that produce these proteins. moreover, their secretion is strongly affected by the temperature and ph of the culture medium. both hrma and avrpto were secreted at their highest amounts when the temperature was between 18 and 22 degrees c and when the culture medium was ph 6.0. in contrast, temperature did not affect the secretion of hrpz. ph d ... | 1999 | 10438746 |
| disruption of narg, the gene encoding the catalytic subunit of respiratory nitrate reductase, also affects nitrite respiration in pseudomonas fluorescens yt101. | the pseudomonas fluorescens yt101 gene narg, which encodes the catalytic alpha subunit of the respiratory nitrate reductase, was disrupted by insertion of a gentamicin resistance cassette. in the nar(-) mutants, nitrate reductase activity was not detectable under all the conditions tested, suggesting that p. fluorescens yt101 contains only one membrane-bound nitrate reductase and no periplasmic nitrate reductase. whereas n(2)o respiration was not affected, anaerobic growth with no(2) as the sole ... | 1999 | 10438786 |
| leucine aminopeptidase rnas, proteins, and activities increase in response to water deficit, salinity, and the wound signals systemin, methyl jasmonate, and abscisic acid | lapa rnas, proteins, and activities increased in response to systemin, methyl jasmonate, abscisic acid (aba), ethylene, water deficit, and salinity in tomato (lycopersicon esculentum). salicylic acid inhibited wound-induced increases of lapa rnas. experiments using the aba-deficient flacca mutant indicated that aba was essential for wound and systemin induction of lapa, and aba and systemin acted synergistically to induce lapa gene expression. in contrast, pin2 (proteinase inhibitor 2) was not d ... | 1999 | 10444081 |
| early events in the signal pathway for the oxidative burst in soybean cells exposed to avirulent pseudomonas syringae pv glycinea | soybean (glycine max) cv williams 82 suspension cultures exhibit an oxidative burst approximately 3 h after challenge with pseudomonas syringae pv glycinea (psg) harboring the avra (avirulence) gene. pretreatment with the tyrosine (tyr) kinase inhibitor herbimycin a or the serine/threonine kinase inhibitor k252a abolished the burst and subsequent induction of glutathione s-transferase. however, imposition of a 45-min rest period between pathogen challenge and subsequent addition of the kinase in ... | 1999 | 10444097 |
| involvement of the exopolysaccharide alginate in the virulence and epiphytic fitness of pseudomonas syringae pv. syringae. | alginate, a co-polymer of o-acetylated beta-1,4-linked d-mannuronic acid and l-guluronic acid, has been reported to function in the virulence of pseudomonas syringae, although genetic studies to test this hypothesis have not been undertaken previously. in the present study, we used a genetic approach to evaluate the role of alginate in the pathogenicity of p. syringae pv. syringae 3525, which causes bacterial brown spot on beans. alginate biosynthesis in strain 3525 was disrupted by recombining ... | 1999 | 10447881 |
| salicylic acid induction-deficient mutants of arabidopsis express pr-2 and pr-5 and accumulate high levels of camalexin after pathogen inoculation. | in arabidopsis, systemic acquired resistance against pathogens has been associated with the accumulation of salicylic acid (sa) and the expression of the pathogenesis-related proteins pr-1, pr-2, and pr-5. we report here the isolation of two nonallelic mutants impaired in the pathway leading to sa biosynthesis. these sa induction-deficient (sid) mutants do not accumulate sa after pathogen inoculation and are more susceptible to both virulent and avirulent forms of pseudomonas syringae and perono ... | 1999 | 10449575 |
| role of the hrp type iii protein secretion system in growth of pseudomonas syringae pv. syringae b728a on host plants in the field. | hrp genes are reportedly required for pathogenicity in pseudomonas syringae pv. syringae (pss) and other phytopathogenic bacterial species. a subset of these genes encodes a type iii secretion system through which virulence factors are thought to be delivered to plant cells. in this study, we sought to better understand the role that hrp genes play in interactions of pss with its host as they occur naturally under field conditions. population sizes of hrp mutants with defects in genes that encod ... | 1999 | 10449783 |
| a simplified subtractive hybridization protocol used to isolate dna sequences specific to xylella fastidiosa. | a simplified protocol of subtractive hybridization based on the technique of l. m. kunkel, a. p. monaco, w. middlesworth, h. d. ochs & s. a. latt (1985, proc natl acad sci usa, 82, 4778-4782) was used to obtain dna sequences specific to xylella fastidiosa isolated from diseased citrus plants. as a driver, dna extracted from bacteria showing different degrees of relatedness was used: xy. fastidiosa 788 isolated from another host (plum), xanthomonas campestris pv. campestris and burkholderia gladi ... | 1999 | 10463163 |
| amplified fragment length polymorphism fingerprinting of pseudomonas strains from a poultry processing plant. | molecular typing has been used previously to identify and trace dissemination of pathogenic and spoilage bacteria associated with food processing. amplified fragment length polymorphism (aflp) is a novel dna fingerprinting technique which is considered highly reproducible and has high discriminatory power. this technique was used to fingerprint 88 pseudomonas fluorescens and pseudomonas putida strains that were previously isolated from plate counts of carcasses at six processing stages and vario ... | 1999 | 10473382 |
| microbial proline 4-hydroxylase screening and gene cloning. | microbial proline 4-hydroxylases, which hydroxylate free l-proline to trans-4-hydroxy-l-proline, were screened in order to establish an industrial system for biotransformation of l-proline to trans-4-hydroxy-l-proline. enzyme activities were detected in eight strains, including strains of dactylosporangium spp. and amycolatopsis spp. the dactylosporangium sp. strain rh1 enzyme was partially purified 3,300-fold and was estimated to be a monomer polypeptide with an apparent molecular mass of 31 kd ... | 1999 | 10473412 |
| identification of the pseudomonas stutzeri ox1 toluene-o-xylene monooxygenase regulatory gene (tour) and of its cognate promoter. | toluene-o-xylene monooxygenase is an enzymatic complex, encoded by the touabcdef genes, responsible for the early stages of toluene and o-xylene degradation in pseudomonas stutzeri ox1. in order to identify the loci involved in the transcriptional regulation of the tou gene cluster, deletion analysis and complementation studies were carried out with pseudomonas putida paw340 as a heterologous host harboring pfb1112, a plasmid that allowed regulated expression, inducible by toluene and o-xylene a ... | 1999 | 10473416 |
| development and application of pathovar-specific monoclonal antibodies that recognize the lipopolysaccharide o antigen and the type iv fimbriae of xanthomonas hyacinthi. | the objective of this study was to develop a specific immunological diagnostic assay for yellow disease in hyacinths, using monoclonal antibodies (mabs). mice were immunized with a crude cell wall preparation (shear fraction) from xanthomonas hyacinthi and with purified type iv fimbriae. hybridomas were screened for a positive reaction with x. hyacinthi cells or fimbriae and for a negative reaction with x. translucens pv. graminis or erwinia carotovora subsp. carotovora. nine mabs recognized fim ... | 1999 | 10473431 |
| systemic resistance in arabidopsis induced by rhizobacteria requires ethylene-dependent signaling at the site of application. | root colonization of arabidopsis thaliana by the nonpathogenic, rhizosphere-colonizing, biocontrol bacterium pseudomonas fluorescens wcs417r has been shown to elicit induced systemic resistance (isr) against pseudomonas syringae pv. tomato (pst). the isr response differs from the pathogen-inducible systemic acquired resistance (sar) response in that isr is independent of salicylic acid and not associated with pathogenesis-related proteins. several ethylene-response mutants were tested and showed ... | 1999 | 10475689 |
| deficiency in phytoalexin production causes enhanced susceptibility of arabidopsis thaliana to the fungus alternaria brassicicola. | the phytoalexin-deficient arabidopsis mutant pad3-1, which is affected in the production of the indole-type phytoalexin camalexin, has previously been shown not to display altered susceptibility to either the bacterium pseudomonas syringae (glazebrook & ausubel 1994; proc. natl. acad. sci. usa, 91: 8955-8959) or the biotrophic fungi peronospora parasitica (glazebrook et al. 1997; genetics, 146: 381-392) and erysiphe orontii (reuber et al. 1998; plant j. 16: 473-485). we now show that this mutant ... | 1999 | 10476063 |
| genetics of o-antigen biosynthesis in pseudomonas aeruginosa. | pathogenic bacteria produce an elaborate assortment of extracellular and cell-associated bacterial products that enable colonization and establishment of infection within a host. lipopolysaccharide (lps) molecules are cell surface factors that are typically known for their protective role against serum-mediated lysis and their endotoxic properties. the most heterogeneous portion of lps is the o antigen or o polysaccharide, and it is this region which confers serum resistance to the organism. pse ... | 1999 | 10477307 |
| dnak and the heat stress response of pseudomonas syringae pv. glycinea. | the dnak gene from pseudomonas syringae pv. glycinea pg4180 was cloned and sequenced. the dnak coding region was 1,917 bp and contained a putative sigma 32 heat shock promoter 86 bp upstream of the translational start site. grpe, another heat shock gene, was found immediately upstream of the putative dnak promoter. the predicted amino acid sequence of dnak showed relatedness to the atpase and substrate binding domains commonly found in heat shock proteins, as well as the highly conserved signatu ... | 1999 | 10478477 |
| determining chemotactic responses by two subsurface microaerophiles using a simplified capillary assay method. | a simplified capillary chemotaxis assay utilizing a hypodermic needle, syringe, and disposable pipette tip was developed to measure bacterial tactic responses. the method was applied to two strains of subsurface microaerophilic bacteria. this method was more convenient than the adler method and required less practice. isolate vt10 was a strain of pseudomonas syringae, which was isolated from the shallow subsurface. it was chemotactically attracted toward dextrose, glycerol, and phenol, which cou ... | 1999 | 10480269 |
| trac of incn plasmid pkm101 associates with membranes and extracellular high-molecular-weight structures in escherichia coli. | conjugative transfer of incn plasmid pkm101 is mediated by the trai-traii region-encoded transfer machinery components. similar to the case for the related agrobacterium tumefaciens t-complex transfer apparatus, this machinery is needed for assembly of pili to initiate cell-to-cell contact preceding dna transfer. biochemical and cell biological experiments presented here show extracellular localization of trac, as suggested by extracellular complementation of trac-deficient bacteria by helper ce ... | 1999 | 10482495 |
| pathways of assimilative sulfur metabolism in pseudomonas putida. | cysteine and methionine biosynthesis was studied in pseudomonas putida s-313 and pseudomonas aeruginosa pao1. both these organisms used direct sulfhydrylation of o-succinylhomoserine for the synthesis of methionine but also contained substantial levels of o-acetylserine sulfhydrylase (cysteine synthase) activity. the enzymes of the transsulfuration pathway (cystathionine gamma-synthase and cystathionine beta-lyase) were expressed at low levels in both pseudomonads but were strongly upregulated d ... | 1999 | 10482527 |
| hydrogen peroxide from the oxidative burst is neither necessary nor sufficient for hypersensitive cell death induction, phenylalanine ammonia lyase stimulation, salicylic acid accumulation, or scopoletin consumption in cultured tobacco cells treated with elicitin. | h(2)o(2) from the oxidative burst, cell death, and defense responses such as the production of phenylalanine ammonia lyase (pal), salicylic acid (sa), and scopoletin were analyzed in cultured tobacco (nicotiana tabacum) cells treated with three proteinaceous elicitors: two elicitins (alpha-megaspermin and beta-megaspermin) and one glycoprotein. these three proteins have been isolated from phytophthora megasperma h20 and have been previously shown to be equally efficient in inducing a hypersensit ... | 1999 | 10482671 |
| the generation of active oxygen species differs in tobacco and grapevine mesophyll protoplasts. | our previous results have shown that oxidative stress may reduce the regeneration potential of protoplasts, but only protoplasts that are able to supply extracellularly h(2)o(2) can actually divide (c.i. siminis, a.k. kanellis, k.a. roubelakis-angelakis [1993] physiol plant 87: 263-270; c.i. siminis, a.k. kanellis, k.a. roubelakis-angelakis [1994] plant physiol 1105: 1375-1383; a. de marco, k.a. roubelakis-angelakis [1996a] plant physiol 110: 137-145; a. de marco, k.a. roubelakis-angelakis [1996 ... | 1999 | 10482675 |
| identification of a pathogenicity island, which contains genes for virulence and avirulence, on a large native plasmid in the bean pathogen pseudomonas syringae pathovar phaseolicola. | the 154-kb plasmid was cured from race 7 strain 1449b of the phytopathogen pseudomonas syringae pv. phaseolicola (pph). cured strains lost virulence toward bean, causing the hypersensitive reaction in previously susceptible cultivars. restoration of virulence was achieved by complementation with cosmid clones spanning a 30-kb region of the plasmid that contained previously identified avirulence (avr) genes avrd, avrpphc, and avrpphf. single transposon insertions at multiple sites (including one ... | 1999 | 10485919 |
| the gain-of-function arabidopsis acd6 mutant reveals novel regulation and function of the salicylic acid signaling pathway in controlling cell death, defenses, and cell growth. | we isolated a dominant gain-of-function arabidopsis mutant, accelerated cell death 6 (acd6), with elevated defenses, patches of dead and enlarged cells, reduced stature, and increased resistance to pseudomonas syringae. the acd6-conferred phenotypes are suppressed by removing a key signaling molecule, salicylic acid (sa), by using the nahg transgene, which encodes sa hydroxylase. this suppression includes phenotypes that are not induced by application of sa to wild-type plants, indicating that s ... | 1999 | 10488236 |
| a new peroxidase cdna from white clover: its characterization and expression in root tissue challenged with homologous rhizobia, heterologous rhizobia, or pseudomonas syringae. | temporal reverse transcription-polymerase chain reaction (rt-pcr) expression analyses were performed on trprx2, a new white clover peroxidase, with roots challenged with homologous rhizobia, heterologous rhizobia, and a pathogen, pseudomonas syringae. low levels of trprx2 expression were evident in all rhizobial treatments but in p.syringae-treated clover background expression was dramatically reduced within 1 h and was undetectable in treatments inoculated for more than 3 h. spraying 4 mm salic ... | 1999 | 10494634 |
| genomic subtractive hybridization and selective capture of transcribed sequences identify a novel salmonella typhimurium fimbrial operon and putative transcriptional regulator that are absent from the salmonella typhi genome. | salmonella typhi, the etiologic agent of typhoid fever, is adapted to the human host and unable to infect nonprimate species. the genetic basis for host specificity in s. typhi is unknown. the avirulence of s. typhi in animal hosts may result from a lack of genes present in the broad-host-range pathogen salmonella typhimurium. genomic subtractive hybridization was successfully employed to isolate s. typhimurium genomic sequences which are absent from the s. typhi genome. these genomic subtracted ... | 1999 | 10496884 |
| differential transcription of the tcpph operon confers biotype-specific control of the vibrio cholerae toxr virulence regulon. | epidemic strains of vibrio cholerae o1 are divided into two biotypes, classical and el tor. in both biotypes, regulation of virulence gene expression depends on a cascade in which toxr activates expression of toxt, and toxt activates expression of cholera toxin and other virulence genes. in the classical biotype, maximal expression of this toxr regulon in vitro occurs at 30 degrees c at ph 6.5 (toxr-inducing conditions), whereas in the el tor biotype, production of these virulence genes only occ ... | 1999 | 10496885 |
| expression of the soxr gene of pseudomonas aeruginosa is inducible during infection of burn wounds in mice and is required to cause efficient bacteremia. | burn wounds are prone to infection by pseudomonas aeruginosa, which is an opportunistic pathogen causing various human diseases. during infection, the bacterium senses environmental changes and regulates the expression of genes appropriate for survival. a purine-auxotrophic mutant of p. aeruginosa was unable to replicate efficiently on burn wounds, suggesting that burn wounds are purine-deficient environments. an in vivo expression technology based on purek gene expression was applied to the bur ... | 1999 | 10496912 |
| antifungal activities of antineoplastic agents: saccharomyces cerevisiae as a model system to study drug action. | recent evolutionary studies reveal that microorganisms including yeasts and fungi are more closely related to mammals than was previously appreciated. possibly as a consequence, many natural-product toxins that have antimicrobial activity are also toxic to mammalian cells. while this makes it difficult to discover antifungal agents without toxic side effects, it also has enabled detailed studies of drug action in simple genetic model systems. we review here studies on the antifungal actions of a ... | 1999 | 10515904 |
| cloning and sequence analysis of two pseudomonas flavoprotein xenobiotic reductases. | the genes encoding flavin mononucleotide-containing oxidoreductases, designated xenobiotic reductases, from pseudomonas putida ii-b and p. fluorescens i-c that removed nitrite from nitroglycerin (ng) by cleavage of the nitroester bond were cloned, sequenced, and characterized. the p. putida gene, xena, encodes a 39,702-da monomeric, nad(p)h-dependent flavoprotein that removes either the terminal or central nitro groups from ng and that reduces 2-cyclohexen-1-one but did not readily reduce 2,4,6- ... | 1999 | 10515912 |
| identification of a locus in arabidopsis controlling both the expression of rhizobacteria-mediated induced systemic resistance (isr) and basal resistance against pseudomonas syringae pv. tomato. | selected nonpathogenic rhizobacteria with biological disease control activity are able to elicit an induced systemic resistance (isr) response that is phenotypically similar to pathogen-induced systemic acquired resistance (sar). ten ecotypes of arabidopsis thaliana were screened for their potential to express rhizobacteria-mediated isr and pathogen-induced sar against the leaf pathogen pseudomonas syringae pv. tomato dc3000 (pst). all ecotypes expressed sar. however, of the 10 ecotypes tested, ... | 1999 | 10517031 |
| the transcriptional activator corr is involved in biosynthesis of the phytotoxin coronatine and binds to the cmaabt promoter region in a temperature-dependent manner. | a modified two-component regulatory system consisting of the histidine protein kinase cors and two highly homologous response regulators, corr and corp, controls biosynthesis of the polyketide phytotoxin coronatine (cor) by pseudomonas syringae pv. glycinea pg4180 in a temperature-dependent manner. cor synthesis is maximal at 18 degrees c but does not occur at 28 degrees c. fusions of corr and corp to the maltose-binding protein (mbp) were overproduced in escherichia coli and p. syringae pg4180, ... | 1999 | 10517320 |
| fate of escherichia coli o157:h7 on fresh-cut apple tissue and its potential for transmission by fruit flies. | pathogenic escherichia coli o157:h7, as well as nonpathogenic strains atcc 11775 and atcc 23716, grew exponentially in wounds on golden delicious apple fruit. the exponential growth occurred over a longer time period on fruit inoculated with a lower concentration of the bacterium than on fruit inoculated with a higher concentration. the bacterium reached the maximum population supported in the wounds regardless of the initial inoculum concentrations. populations of e. coli o157:h7 in various con ... | 1999 | 9872751 |
| characterization of a facultatively psychrophilic bacterium, vibrio rumoiensis sp. nov., that exhibits high catalase activity | a novel facultatively psychrophilic bacterium, strain s-1, which exhibits extraordinarily high catalase activity was isolated from the drain pool of a fish product processing plant that uses h2o2 as a bleaching and microbicidal agent. the catalase activity of the isolate was 1 or 2 orders of magnitude higher than those of corynebacterium glutamicum, staphylococcus aureus, pseudomonas fluorescens, and five other species tested in this study. the strain seemed to possess only one kind of catalase, ... | 1999 | 9872761 |
| suppressors of the arabidopsis lsd5 cell death mutation identify genes involved in regulating disease resistance responses. | cell death is associated with the development of the plant disease resistance hypersensitive reaction (hr). arabidopsis lsd mutants that spontaneously exhibit cell death reminiscent of the hr were identified previously. to study further the regulatory context in which cell death acts during disease resistance, one of these mutants, lsd5, was used to isolate new mutations that suppress its cell death phenotype. using a simple lethal screen, nine lsd5 cell death suppressors, designated phx (for th ... | 1999 | 9872969 |
| a genomic cluster containing four differentially regulated subtilisin-like processing protease genes is in tomato plants. | screening of a genomic library from tomato plants (lycopersicon esculentum) with a cdna probe encoding a subtilisin-like protease (pr-p69) that is induced at the transcriptional level following pathogen attack (tornero, p., conejero, v., and vera, p. (1996) proc. natl. acad. sci. u. s. a. 93, 6332-6337) resulted in the isolation of a cluster of genomic clones that comprise a tandem of four different subtilisin-like protease genes (p69a, p69b, p69c, and p69d). sequence analyses and comparison of ... | 1999 | 9891003 |
| killing of caenorhabditis elegans by pseudomonas aeruginosa used to model mammalian bacterial pathogenesis. | we show that a single clinical isolate of the human opportunistic pathogen pseudomonas aeruginosa (strain pa14), which previously was shown to be pathogenic in mice and plants, also kills caenorhabditis elegans. the rate of pa14-mediated killing of c. elegans depends on the composition of the agar medium on which pa14 is grown. when pa14 is grown on minimal medium, killing occurs over the course of several days and is referred to as "slow" killing. when pa14 is grown on high-osmolarity medium, k ... | 1999 | 9892699 |
| involvement of specific calmodulin isoforms in salicylic acid-independent activation of plant disease resistance responses. | the ca2+ signal is essential for the activation of plant defense responses, but downstream components of the signaling pathway are still poorly defined. here we demonstrate that specific calmodulin (cam) isoforms are activated by infection or pathogen-derived elicitors and participate in ca2+-mediated induction of plant disease resistance responses. soybean cam (scam)-4 and scam-5 genes, which encode for divergent cam isoforms, were induced within 30 min by a fungal elicitor or pathogen, whereas ... | 1999 | 9892708 |
| thermoregulated expression and characterization of an nad(p)h-dependent 2-cyclohexen-1-one reductase in the plant pathogenic bacterium pseudomonas syringae pv. glycinea. | the phytopathogenic bacterium pseudomonas syringae pv. glycinea pg4180.n9 causes bacterial blight of soybeans and preferably infects its host plant during periods of cold, humid weather conditions. to identify proteins differentially expressed at low temperatures, total cellular protein fractions derived from pg4180.n9 grown at 18 and 28 degreesc were separated by two-dimensional gel electrophoresis. of several proteins which appeared to be preferentially present at 18 degreesc, a 40-kda protein ... | 1999 | 9922244 |
| sequence and function of luxu: a two-component phosphorelay protein that regulates quorum sensing in vibrio harveyi. | vibrio harveyi regulates the expression of bioluminescence (lux) in response to cell density, a phenomenon known as quorum sensing. in v. harveyi, two independent quorum-sensing systems exist, and each produces, detects, and responds to a specific cell density-dependent autoinducer signal. the autoinducers are recognized by two-component hybrid sensor kinases called luxn and luxq, and sensory information from both systems is transduced by a phosphorelay mechanism to the response regulator protei ... | 1999 | 9922254 |
| characterization of is1547, a new member of the is900 family in the mycobacterium tuberculosis complex, and its association with is6110. | unlike classically defined insertion sequence (is) elements, which are delimited by their inverted terminal repeats, some is elements do not have inverted terminal repeats. among this group of atypical is elements, is116, is900, is901, and is1110 have been proposed as members of the is900 family of elements, not only because they do not have inverted terminal repeats but also because they share other features such as homologous transposases and particular insertion sites. in this study, we repor ... | 1999 | 9922269 |