| detection and isolation of novel rhizopine-catabolizing bacteria from the environment | microbial rhizopine-catabolizing (moc) activity was detected in serial dilutions of soil and rhizosphere washes. the activity observed generally ranged between 10(6) and 10(7) catabolic units per g, and the numbers of nonspecific culture-forming units were found to be approximately 10 times higher. a diverse set of 37 isolates was obtained by enrichment on scyllo-inosamine-containing media. however, none of the bacteria that were isolated were found to contain dna sequences homologous to the kno ... | 1998 | 9835587 |
| differential expression of a senescence-enhanced metallothionein gene in arabidopsis in response to isolates of peronospora parasitica and pseudomonas syringae. | the metallothionein gene, lsc54, shows increased expression during leaf senescence in brassica napus and arabidopsis thaliana. a number of abiotic and biotic stresses have been shown to induce senescence-like symptoms in plants and, to investigate this further, the promoter of the lsc54 gene was cloned and fused to the gus gene and transformed into arabidopsis. the promoter was highly induced during leaf senescence and also in response to wounding; histochemical analysis indicated that this indu ... | 1998 | 9839466 |
| inorganic cation transport and energy transduction in enterococcus hirae and other streptococci. | energy metabolism by bacteria is well understood from the chemiosmotic viewpoint. we know that bacteria extrude protons across the plasma membrane, establishing an electrochemical potential that provides the driving force for various kinds of physiological work. among these are the uptake of sugars, amino acids, and other nutrients with the aid of secondary porters and the regulation of the cytoplasmic ph and of the cytoplasmic concentration of potassium and other ions. bacteria live in diverse ... | 1998 | 9841664 |
| the virulence plasmid of yersinia, an antihost genome. | the 70-kb virulence plasmid enables yersinia spp. (yersinia pestis, y. pseudotuberculosis, and y. enterocolitica) to survive and multiply in the lymphoid tissues of their host. it encodes the yop virulon, an integrated system allowing extracellular bacteria to disarm the cells involved in the immune response, to disrupt their communications, or even to induce their apoptosis by the injection of bacterial effector proteins. this system consists of the yop proteins and their dedicated type iii sec ... | 1998 | 9841674 |
| potentiation of the oxidative burst and isoflavonoid phytoalexin accumulation by serine protease inhibitors | treatment of soybean (glycine max l. cv williams 82) cell-suspension cultures with pseudomonas syringae pv glycinea (psg) harboring an avirulence gene (avra) or with yeast elicitor resulted in an oxidative burst characterized by the accumulation of h2o2. this burst, and the resultant induction of glutathione s-transferase transcripts, occurred more rapidly and was more prolonged if cells were simultaneously treated with serine protease inhibitors such as phenylmethylsulfonyl fluoride (pmsf) or d ... | 1998 | 9847125 |
| the two-component regulators gacs and gaca influence accumulation of the stationary-phase sigma factor sigmas and the stress response in pseudomonas fluorescens pf-5. | three global regulators are known to control antibiotic production by pseudomonas fluorescens. a two-component regulatory system comprised of the sensor kinase gacs (previously called apda or lema) and gaca, a member of the fixj family of response regulators, is required for antibiotic production. a mutation in rpos, which encodes the stationary-phase sigma factor sigmas, differentially affects antibiotic production and reduces the capacity of stationary-phase cells of p. fluorescens to survive ... | 1998 | 9852008 |
| biosynthesis of the pseudomonas polyketide coronafacic acid requires monofunctional and multifunctional polyketide synthase proteins. | coronafacic acid (cfa) is the polyketide component of the phytotoxin coronatine, a virulence factor of the plant pathogen pseudomonas syringae. our current knowledge of polyketide biosynthesis largely is based on the analysis of polyketide synthases (pkss) in actinomycetes and other gram-positive bacteria. consequently, the cloning and characterization of the cfa biosynthetic gene cluster will contribute significantly to our knowledge of polyketide synthesis in pseudomonas. in this report, we de ... | 1998 | 9860992 |
| independent deletions of a pathogen-resistance gene in brassica and arabidopsis. | plant disease resistance (r) genes confer race-specific resistance to pathogens and are genetically defined on the basis of intra-specific functional polymorphism. little is known about the evolutionary mechanisms that generate this polymorphism. most r loci examined to date contain alternate alleles and/or linked homologs even in disease-susceptible plant genotypes. in contrast, the resistance to pseudomonas syringae pathovar maculicola (rpm1) bacterial resistance gene is completely absent (rpm ... | 1998 | 9861058 |
| the arabidopsis thaliana rpm1 disease resistance gene product is a peripheral plasma membrane protein that is degraded coincident with the hypersensitive response. | disease resistance in plants is often controlled by a gene-for-gene mechanism in which avirulence (avr) gene products encoded by pathogens are specifically recognized, either directly or indirectly, by plant disease resistance (r) gene products. members of the nbs-lrr class of r genes encode proteins containing a putative nucleotide binding site (nbs) and carboxyl-terminal leucine-rich repeats (lrrs). generally, nbs-lrr proteins do not contain predicted transmembrane segments or signal peptides, ... | 1998 | 9861059 |
| identification of an escherichia coli pepa homolog and its involvement in suppression of the algb phenotype in mucoid pseudomonas aeruginosa. | strains of pseudomonas aeruginosa isolated from the respiratory tracts of patients with cystic fibrosis often display a mucoid morphology due to high levels of expression of the exopolysaccharide alginate. the response regulator algb is required for full transcription of the alginate biosynthetic operon. repeated attempts to demonstrate a direct interaction between algb and the promoter region of algd, the first gene in the alginate operon, have thus far been unsuccessful. the possibility that a ... | 1999 | 9864319 |
| adaptation of mycobacterium smegmatis to stationary phase. | mycobacterium tuberculosis can persist for many years within host lung tissue without causing clinical disease. little is known about the state in which the bacilli survive, although it is frequently referred to as dormancy. some evidence suggests that cells survive in nutrient-deprived stationary phase. therefore, we are studying stationary-phase survival of mycobacterium smegmatis as a model for mycobacterial persistence. m. smegmatis cultures could survive 650 days of either carbon, nitrogen, ... | 1999 | 9864340 |
| cloning of genes by mrna differential display induced during the hypersensitive reaction of soybean after inoculation with pseudomonas syringae pv. glycinea. | soybean (glycine max [l.] merr.) cell suspension cultures (cv. williams 82) inoculated with the pathogenic bacteria pseudomonas syringae pv. glycinea respond with a hypersensitive reaction (hr) when the bacteria express the avirulence gene avra. a mrna differential display was established for this system to allow the identification of genes induced during the hr. six pcr-fragments (dd1-dd6) from the differential display analysis were identified, which are induced during the hr. database searches ... | 1998 | 9869427 |
| insertion specificity and trans-activation of is801. | the transposable element is801, isolated from plasmid pmmc7105 of pseudomonas syringae pv. phaseolicola, transposes in escherichia coli to plasmid targets, expressing a relatively relaxed target specificity. the target sequences are tetramers with homology with the left terminus (gaac) of the transposing unit, the alternative targets being gaac, ggac, caag, and cgac. in the areas flanking is801 in 13 different locations, no similarities other than the target tetramer were observed. the transposa ... | 1998 | 9870703 |
| 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 |
| structure of the o polysaccharide and immunochemical relationships between the lipopolysaccharides of pseudomonas syringae pathovar tomato and pathovar maculicola. | o polysaccharides (ops) of the lipopolysaccharides (lps) of pseudomonas syringae pathovar tomato gspb 483 and pathovar maculicola imv 381 were studied by 1h-nmr and 13c-nmr spectroscopy, including two-dimensional cosy, rotating-frame noe spectroscopy (roesy), and h-detected 1h,13c heteronuclear multiple-quantum coherence (hmqc) experiments. the ops from both strains were shown to be chemically identical. two structurally different types of repeating units (o repeats 1 and 2) were elucidated in e ... | 1998 | 9874231 |
| structural heterogeneity in the o polysaccharide of pseudomonas syringae pv. coriandricola gspb 2028 (ncppb 3780, w-43). | the o polysaccharide (ops) of the lipopolysaccharide of pseudomonas syringae pv. coriandricola gspb 2028 (ncppb 3780, w-43) was studied by smith degradation and 1h-nmr and 13c-nmr spectroscopy, including two-dimensional cosy, tocsy, noesy, and h-detected 1h,13c heteronuclear multiple-quantum coherence (hmqc) experiments. the ops was shown to consist of pentasaccharide o repeats of two types both containing four l-rhamnose and one 3-acetamido-3,6-dideoxy-d-galactose (d-fuc3nac) residue. structure ... | 1998 | 9874239 |
| diversity and molecular evolution of the rps2 resistance gene in arabidopsis thaliana. | the rps2 gene in arabidopsis thaliana governs resistance to strains of the bacterial pathogen, pseudomonas syringae pv. tomato, that express the avrrpt2 gene. the two loci are involved in a gene-for-gene interaction. seventeen accessions of a. thaliana were sequenced to explore the diversity present in the coding region of the rps2 locus. an unusually high level of nucleotide polymorphisms was found (1.26%), with nearly half of the observed polymorphisms resulting in amino acid changes in the rp ... | 1999 | 9874813 |
| overexpression of pto activates defense responses and confers broad resistance. | the tomato disease resistance (r) gene pto specifies race-specific resistance to the bacterial pathogen pseudomonas syringae pv tomato carrying the avrpto gene. pto encodes a serine/threonine protein kinase that is postulated to be activated by a physical interaction with the avrpto protein. here, we report that overexpression of pto in tomato activates defense responses in the absence of the pto-avrpto interaction. leaves of three transgenic tomato lines carrying the cauliflower mosaic virus 35 ... | 1999 | 9878629 |
| correlation of defense gene induction defects with powdery mildew susceptibility in arabidopsis enhanced disease susceptibility mutants. | we investigated the relative importance of specific arabidopsis thaliana genes in conferring resistance to bacterial versus fungal pathogens. we first developed a pathosystem involving the infection of arabidopsis accession columbia with a virulent isolate of the obligate biotrophic fungal pathogen erysiphe orontii. e. orontii elicited the accumulation of mrnas corresponding to the defense-related genes pr1, bgl2 (pr2), pr5 and gst1, but did not elicit production of the phytoalexin camalexin or ... | 1998 | 9881167 |
| cloning and characterization of a tetracycline resistance determinant present in agrobacterium tumefaciens c58. | agrobacterium tumefaciens c58 and its derivatives give rise to spontaneous mutants resistant to tetracycline at a high frequency. we observed that a mutation affecting a trna processing function significantly affected the emergence of such mutants, suggesting that c58 contained a positively acting gene conferring resistance to tetracycline. a cosmid clone conferring resistance to tetracycline in escherichia coli and agrobacterium was isolated from a genomic bank of one such mutant. subcloning, t ... | 1999 | 9882678 |
| control of herbaspirillum seropedicae nifa activity by ammonium ions and oxygen. | the activity of a truncated form of herbaspirillum seropedicae nifa in different genetic backgrounds showed that its regulatory domain is involved in nitrogen control but not in o2 sensitivity or fe dependence. the model for nitrogen control involving pii could thus apply to the proteobacteria at large. nifa may have a role in controlling adp-ribosylation of nitrogenase in azospirillum brasilense. | 1999 | 9882688 |
| camalexin accumulation in arabis lyrata. | inoculation of leaves of arabis lyrata with either a bacterial pathogen pseudomonas syringae pv. maculicola strain es4326 or cochliobolus carbonum, a fungal nonpathogen of a. lyrata, resulted in the accumulation of a compound with similar chromatographic and fluorescent properties to that of camalexin (i), a phytoalexin produced by arabidopsis thaliana. a. lyrata is closely related to a. thaliana. high resolution electron impact mass spectroscopic and proton nmr analysis confirmed that the compo ... | 1998 | 9887527 |
| 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 |
| transcriptional activity at supraoptimal temperature of growth in the antarctic psychrotrophic bacterium pseudomonas syringae. | transcriptional activity was monitored in cells of the antarctic psychrotrophic bacterium pseudomonas syringae (lz4w), which does not grow above 30 degrees c. it was observed that the bacterium was capable of synthesising rna at a temperature range of 0-37 degrees c, both in vitro and in vivo. the net incorporation of the radioactive precursor, [3h]uridine, into rna was found to be affected at 37 degrees c. a pulse-chase experiment following a 32p labeling of rna in vivo indicated that the ribos ... | 1999 | 9922464 |
| fungal lethality, binding, and cytotoxicity of syringomycin-e. | syringomycin-e (se) was significantly lethal to aspergillus and fusarium species at between 1.9 and 7.8 micrograms/ml. se complexed with the following fungal wall constituents (in order of binding): beta-1,3-glucan > chitin > mannan > ergosterol = cholesterol. cytotoxicity in hela cells was proportional to the se concentration, while the amount required for cytotoxicity was 3 to 20 times that needed to kill 95% of the fungi tested. | 1999 | 9925536 |
| the arabidopsis ssi1 mutation restores pathogenesis-related gene expression in npr1 plants and renders defensin gene expression salicylic acid dependent. | the arabidopsis npr1 gene was previously shown to be required for the salicylic acid (sa)- and benzothiadiazole (bth)-induced expression of pathogenesis-related (pr) genes and systemic acquired resistance. the dominant ssi1 (for suppressor of sa insensitivity) mutation characterized in this study defines a new component of the sa signal transduction pathway that bypasses the requirement of npr1 for expression of the pr genes and disease resistance. the ssi1 mutation caused pr (pr-1, bgl2 [pr-2], ... | 1999 | 9927638 |
| cell-specific production and antimicrobial activity of naphthoquinones in roots of lithospermum erythrorhizon | pigmented naphthoquinone derivatives of shikonin are produced at specific times and in specific cells of lithospermum erythrorhizon roots. normal pigment development is limited to root hairs and root border cells in hairy roots grown on "noninducing" medium, whereas induction of additional pigment production by abiotic (cuso4) or biotic (fungal elicitor) factors increases the amount of total pigment, changes the ratios of derivatives produced, and initiates production of pigment de novo in epide ... | 1999 | 9952436 |
| hybrid frequencies confirm limit to coinfection in the rna bacteriophage phi6. | coinfection of the same host cell by multiple viruses may lead to increased competition for limited cellular resources, thus reducing the fitness of an individual virus. selection should favor viruses that can limit or prevent coinfection, and it is not surprising that many viruses have evolved mechanisms to do so. here we explore whether coinfection is limited in the rna bacteriophage phi6 that infects pseudomonas phaseolicola. we estimated the limit to coinfection in phi6 by comparing the freq ... | 1999 | 9971826 |
| characterization of insertions of is476 and two newly identified insertion sequences, is1478 and is1479, in xanthomonas campestris pv. campestris. | thirty-two plasmid insertion mutants were independently isolated from two strains of xanthomonas campestris pv. campestris in taiwan. of the 32 mutants, 14 (44%), 8 (25%), and 4 (12%) mutants resulted from separate insertions of an is3 family member, is476, and two new insertion sequences (is), is1478 and is1479. while is1478 does not have significant sequence homology with any is elements in the embl/genbank/ddbj database, is1479 demonstrated 73% sequence homology with is1051 in x. campestris p ... | 1999 | 9973349 |
| auxins upregulate expression of the indole-3-pyruvate decarboxylase gene in azospirillum brasilense. | transcription of the azospirillum brasilense ipdc gene, encoding an indole-3-pyruvate decarboxylase involved in the biosynthesis of indole-3-acetic acid (iaa), is induced by iaa as determined by ipdc-gusa expression studies and northern analysis. besides iaa, exogenously added synthetic auxins such as 1-naphthaleneacetic acid, 2,4-dichlorophenoxypropionic acid, and p-chlorophenoxyacetic acid were also found to upregulate ipdc expression. no upregulation was observed with tryptophan, acetic acid, ... | 1999 | 9973364 |
| the virulence plasmid-encoded impcab operon enhances survival and induced mutagenesis in shigella flexneri after exposure to uv radiation. | upon exposure to uv radiation, shigella flexneri sa100 displayed survival and mutation frequencies comparable to those of escherichia coli ab1157, which contains a functional umudc error-prone dna repair system. survival of sa100 after uv irradiation was associated with the presence of the 220-kb virulence plasmid, pvp. this plasmid encodes homologues of impa and impb, which comprise an error-prone dna repair system encoded on plasmid tp110 that was initially identified in salmonella typhimurium ... | 1999 | 10024589 |
| the synthesis of tabtoxin peptide bond in pseudomonas syringae pv. tabaci. | | 1998 | 10047897 |
| components of the salmonella flagellar export apparatus and classification of export substrates. | until now, identification of components of the flagellar protein export apparatus has been indirect. we have now identified these components directly by establishing whether mutants defective in putative export components could translocate export substrates across the cytoplasmic membrane into the periplasmic space. hook-type proteins could be exported to the periplasm of rod mutants, indicating that rod protein export does not have to precede hook-type protein export and therefore that both typ ... | 1999 | 10049367 |
| secretion, localization, and antibacterial activity of tasa, a bacillus subtilis spore-associated protein. | the synthesis and subcellular localization of the proteins that comprise the bacillus subtilis spore are under a variety of complex controls. to better understand these controls, we have identified and characterized a 31-kda sporulation protein, called tasa, which is secreted into the culture medium early in sporulation and is also incorporated into the spore. tasa synthesis begins approximately 30 min after the onset of sporulation and requires the sporulation transcription factor genes spo0h a ... | 1999 | 10049401 |
| suppression of bacterial blight by a bacterial community isolated from the guttation fluids of anthuriums | growth and survival of xanthomonas campestris pv. dieffenbachiae in guttation fluids (xylem sap exuded from leaf margins) of anthuriums were suppressed by several bacterial strains indigenous to leaves of various anthurium cultivars. inhibition of growth was not observed in filter-sterilized guttation fluids and was restored to original levels only by reintroducing specific mixtures of bacteria into filter-sterilized guttation fluids. the inhibitory effect was related to the species in the bacte ... | 1999 | 10049858 |
| polynucleotide probes that target a hypervariable region of 16s rrna genes to identify bacterial isolates corresponding to bands of community fingerprints. | temperature gradient gel electrophoresis (tgge) is well suited for fingerprinting bacterial communities by separating pcr-amplified fragments of 16s rrna genes (16s ribosomal dna [rdna]). a strategy was developed and was generally applicable for linking 16s rdna from community fingerprints to pure culture isolates from the same habitat. for this, digoxigenin-labeled polynucleotide probes were generated by pcr, using bands excised from tgge community fingerprints as a template, and applied in hyb ... | 1999 | 10049861 |
| enhanced resistance to bacterial diseases of transgenic tobacco plants overexpressing sarcotoxin ia, a bactericidal peptide of insect. | sarcotoxin ia is a bactericidal peptide of 39 amino acids found in the common flesh fly, sarcophaga peregrina. many agronomically important bacteria in japan are killed by this peptide at sub-micro molar levels, and the growth of tobacco and rice suspension cultured cells is not inhibited with less than 25 microm. transgenic tobacco plants which overexpress the peptide, i.e. over 250 pmol per gram of fresh leaf, under the control of a high expression constitutive promoter showed enhanced resista ... | 1999 | 10050028 |
| metabolic engineering of poly(3-hydroxyalkanoates): from dna to plastic. | poly(3-hydroxyalkanoates) (phas) are a class of microbially produced polyesters that have potential applications as conventional plastics, specifically thermoplastic elastomers. a wealth of biological diversity in pha formation exists, with at least 100 different pha constituents and at least five different dedicated pha biosynthetic pathways. this diversity, in combination with classical microbial physiology and modern molecular biology, has now opened up this area for genetic and metabolic eng ... | 1999 | 10066830 |
| precise packaging of the three genomic segments of the double-stranded-rna bacteriophage phi6. | bacteriophage phi6 has a genome of three segments of double-stranded rna. each virus particle contains one each of the three segments. packaging is effected by the acquisition, in a serially dependent manner, of the plus strands of the genomic segments into empty procapsids. the empty procapsids are compressed in shape and expand during packaging. the packaging program involves discrete steps that are determined by the amount of rna inside the procapsid. the steps involve the exposure and concea ... | 1999 | 10066834 |
| plants expressing the pto disease resistance gene confer resistance to recombinant pvx containing the avirulence gene avrpto. | elicitation of hypersensitive cell death and induction of plant disease resistance by pseudomonas syringae pv. tomato (pst) is dependent on activity of the pst hrp secretion system and the gene-for-gene interaction between the tomato resistance gene pto and the bacterial avirulence gene avrpto. avrpto was expressed transiently in resistant or susceptible plant lines via a potato virus x (pvx) vector. we found that while pvx is normally virulent on tomato, a pvx derivative expressing avrpto was o ... | 1999 | 10069066 |
| isolation of ethylene-insensitive soybean mutants that are altered in pathogen susceptibility and gene-for-gene disease resistance | plants commonly respond to pathogen infection by increasing ethylene production, but it is not clear if this ethylene does more to promote disease susceptibility or disease resistance. ethylene production and/or responsiveness can be altered by genetic manipulation. the present study used mutagenesis to identify soybean (glycine max l. merr.) lines with reduced sensitivity to ethylene. two new genetic loci were identified, etr1 and etr2. mutants were compared with isogenic wild-type parents for ... | 1999 | 10069832 |
| the involvement of cysteine proteases and protease inhibitor genes in the regulation of programmed cell death in plants. | programmed cell death (pcd) is a process by which cells in many organisms die. the basic morphological and biochemical features of pcd are conserved between the animal and plant kingdoms. cysteine proteases have emerged as key enzymes in the regulation of animal pcd. here, we show that in soybean cells, pcd-activating oxidative stress induced a set of cysteine proteases. the activation of one or more of the cysteine proteases was instrumental in the pcd of soybean cells. inhibition of the cystei ... | 1999 | 10072402 |
| functional identification of the product of the bacillus subtilis yval gene as a secg homologue. | protein export in escherichia coli is mediated by translocase, a multisubunit membrane protein complex with seca as the peripheral subunit and the secy, sece, and secg proteins as the integral membrane domain. in the gram-positive bacterium bacillus subtilis, seca, secy, and sece have been identified through genetic analysis. sequence comparison of the bacillus chromosome identified a potential homologue of secg, termed yval. a chromosomal disruption of the yval gene results in mild cold sensiti ... | 1999 | 10074070 |
| replication regions from plant-pathogenic pseudomonas syringae plasmids are similar to cole2-related replicons. | many strains of the phytopathogen pseudomonas syringae contain mutually compatible plasmids that share extensive regions of sequence homology and essential replication determinants. the replication regions of two compatible large plasmids involved in virulence or pathogenicity, ppt23a from p. syringae pv. tomato strain pt23 and pav505 from p. syringae pv. phaseolicola strain hri1302a, were isolated. dna sequencing of the origins of replication revealed homologous orfs, designated orf-pto and orf ... | 1999 | 10075415 |
| 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 |