| is1491 from pseudomonas alcaligenes ncib 9867: characterization and distribution among pseudomonas species. | a new insertion sequence, is1491, has been cloned and sequenced. the 2489-bp is1491 was isolated from a pseudomonas alcaligenes ncib 9867 (strain p25x) 4.8-kb psti chromosomal fragment. is1491 is flanked by an imperfect inverted repeat of 23 bp and carries two overlapping open reading frames, orf1 and orf2. both orf1 and orf2 displayed homology to the ista-like and istb-like transposases encoded by the is21 family of insertion sequences, which include two is elements previously isolated from p. ... | 1998 | 9571135 |
| isolation and characterization of is1416 from pseudomonas glumae, a new member of the is3 family. | isolation and characterization of four different insertion sequence (is) elements from pseudomonas glumae maff 302744 through transposition into the entrapment vector pshi1063 are described. one of the elements, is1416, was further characterized. is1416 is 1322 bp long and carries 29-bp terminal inverted repeats flanked by a 3-bp direct duplication. is1416 contains three open reading frames (orfs), which are designated orfa1, orfa2, and orfb, on one strand. both dna sequence of is1416 and the de ... | 1998 | 9571136 |
| ptn5cat: a tn5-derived genetic element to facilitate insertion mutagenesis, promoter probing, physical mapping, cloning, and marker exchange in phytopathogenic and other gram-negative bacteria. | a tn5-derived mobile element has been constructed to identify genes and promoters related to pathogenesis and virulence in pseudomonas syringae pv. phaseolicola. to enhance the rate of mutation this tn5 derivative was constructed carrying a mutant transposase which was placed in cis to the transposable element, but just outside the inverted repeats, therefore eliminating secondary transposition and increasing the stability of the insertion. the new element also contains a promoterless cat (chlor ... | 1998 | 9571137 |
| antibiotic production by erwinia herbicola eh1087: its role in inhibition of erwinia amylovora and partial characterization of antibiotic biosynthesis genes. | mutants of erwinia herbicola eh1087 (ant-), which did not produce antibiotic activity against erwinia amylovora, the fire blight pathogen, were selected after tnphoa mutagenesis. in immature pear fruit ant- mutants grew at the same rate as wild-type strain eh1087 but did not suppress development of the disease caused by e. amylovora. these results indicated that antibiosis plays an important role in the suppression of disease by strain eh1087. all of the ant- mutations obtained were located in a ... | 1998 | 9572960 |
| ecophysiological and phylogenetic studies of nevskia ramosa in pure culture. | during the last 100 years, the neuston bacterium nevskia ramosa has been described several times. this bacterium forms conspicuous rosette-like microcolonies at the air-water interface. in this study, pure cultures of nevskia ramosa were obtained for the first time, from a bog lake (strain soe1, dsmz 11499t) and a freshwater ditch (strain ol1, dsmz 11500). the isolates showed special adaptations to life in the epineuston. they formed hydrophobic surface films with a dull appearance. n. ramosa is ... | 1998 | 9572968 |
| effect of bacterial distribution and activity on conjugal gene transfer on the phylloplane of the bush bean (phaseolus vulgaris). | conjugal plasmid transfer was examined on the phylloplane of bean (phaseolus vulgaris) and related to the spatial distribution pattern and metabolic activity of the bacteria. the donor (pseudomonas putida kt2442) harbored a derivative of the tol plasmid, which conferred kanamycin resistance and had the gfp gene inserted downstream of a lac promoter. a chromosomal insertion of laciq prevented expression of the gfp gene. the recipient (p. putida kt2440) had a chromosomal tetracycline resistance ma ... | 1998 | 9572970 |
| structures of homologous composite transposons carrying cbaabc genes from europe and north america. | is1071 is a class ii transposable element carrying a tnpa gene related to the transposase genes of the tn3 family. copies of is1071 that are conserved with more than 99% nucleotide sequence identity have been found as direct repeats flanking a remarkable variety of catabolic gene sequences worldwide. the sequences of chlorobenzoate catabolic transposons found on pbrc60 (tn5271) in niagara falls, n.y., and on pcpe3 in bologna, italy, show that these transposons were formed from highly homologous ... | 1998 | 9572977 |
| burkholderia cepacia produces a hemolysin that is capable of inducing apoptosis and degranulation of mammalian phagocytes. | burkholderia cepacia is an opportunistic pathogen that has become a major threat to individuals with cystic fibrosis (cf). in approximately 20% of patients, pulmonary colonization with b. cepacia leads to cepacia syndrome, a fatal fulminating pneumonia sometimes associated with septicemia. it has been reported that culture filtrates of clinically derived strains of b. cepacia are hemolytic. in this study, we have characterized a factor which contributes to this hemolytic activity and is secreted ... | 1998 | 9573086 |
| (methyl)ammonium transport in the nitrogen-fixing bacterium azospirillum brasilense. | an ammonium transporter of azospirillum brasilense was characterized. in contrast to most previously reported putative prokaryotic nh4+ transporter genes, a. brasilense amtb is not part of an operon with glnb or glnz which, in a. brasilense, encode nitrogen regulatory proteins pii and pz, respectively. sequence analysis predicts the presence of 12 transmembrane domains in the deduced amtb protein and classifies amtb as an integral membrane protein. nitrogen regulates the transcription of the amt ... | 1998 | 9573149 |
| processed virb2 is the major subunit of the promiscuous pilus of agrobacterium tumefaciens. | previous studies have implicated the obligatory requirement for the vir regulon (or "virulon") of the ti plasmid for the transfer of oncogenes from agrobacterium tumefaciens to plant cells. the machinery used in this horizontal gene transfer has been long thought to be a transformation or conjugative delivery system. based on recent protein sequence comparisons, the proteins encoded by the virb operon are strikingly similar to proteins involved in the synthesis and assembly of conjugative pili s ... | 1998 | 9573157 |
| nucleotide sequence and spatiotemporal expression of the vibrio cholerae viesab genes during infection. | the ivivii gene of vibrio cholerae was previously identified by a screen for genes induced during intestinal infection. in the present study, nucleotide sequence analysis revealed that ivivii is a 1,659-bp open reading frame, herein designated vieb, that is predicted to be last in a tricistronic operon (viesab). the deduced amino acid sequence of vies exhibited similarity to the sensor kinase component, and those of viea and vieb were similar to the response regulator components, respectively, o ... | 1998 | 9573178 |
| a race-specific insertion of transposable element is801 in pseudomonas syringae pv. phaseolicola. | the isolation and cloning of a random amplified polymorphic dna-polymerase chain reaction (rapd-pcr) band specific for pseudomonas syringae pv. phaseolicola race 1 allowed us to design a pair of primers that amplify 1.2-kb race 1-specific and 2.7-kb race 2-specific fragments, providing a rapid method for the identification of races by standard pcr methods. restriction analysis revealed identical endonuclease sites in both fragments but the race 2 fragment contains a 1.5-kb insertion, identified ... | 1998 | 9574509 |
| defense activation and enhanced pathogen tolerance induced by h2o2 in transgenic tobacco. | transgenic tobacco deficient in the h2o2-removing enzyme catalase (cat1as) was used as an inducible and noninvasive system to study the role of h2o2 as an activator of pathogenesis-related (pr) proteins in plants. excess h2o2 in cat1as plants was generated by simply increasing light intensities. sustained exposure of cat1as plants to excess h2o2 provoked tissue damage, stimulated salicylic acid and ethylene production, and induced the expression of acidic and basic pr proteins with a timing and ... | 1998 | 9576968 |
| biosynthesis and regulation of coronatine, a non-host-specific phytotoxin produced by pseudomonas syringae. | many p. syringae pathovars are known to produce low-molecular-weight, diffusible toxins in infected host plants. these phytotoxins reproduce some of the symptoms of the relevant bacterial disease and are effective at very low concentrations. phytotoxins generally enhance the virulence of the p. syringae pathovar which produces them, but are not required for pathogenesis. genes encoding phytotoxin production have been identified and cloned from several p. syringae pathovars. with the exception of ... | 1998 | 9594652 |
| generation of broad-spectrum disease resistance by overexpression of an essential regulatory gene in systemic acquired resistance. | the recently cloned npr1 gene of arabidopsis thaliana is a key regulator of acquired resistance responses. upon induction, npr1 expression is elevated and the npr1 protein is activated, in turn inducing expression of a battery of downstream pathogenesis-related genes. in this study, we found that npr1 confers resistance to the pathogens pseudomonas syringae and peronospora parasitica in a dosage-dependent fashion. overexpression of npr1 leads to enhanced resistance with no obvious detrimental ef ... | 1998 | 9601001 |
| expression of the transposase gene tnpa of tn4652 is positively affected by integration host factor. | tn4652 is a derivative of the toluene degradation transposon tn4651 that belongs to the tn3 family of transposons (m. tsuda and t. iino, mol. gen. genet. 210:270-276, 1987). we have sequenced the transposase gene tnpa of transposon tn4652 and mapped its promoter to the right end of the element. the deduced amino acid sequence of tnpa revealed 96.2% identity with the putative transposase of tn5041. homology with other tn3 family transposases was only moderate (about 20 to 24% identity), suggestin ... | 1998 | 9603867 |
| [physico-chemical properties of there phages of pseudomonas syringae]. | the properties of dna for 9b, 123, 788/8 phages lysing phytopathogenic pseudomonas syringae bacteria have been analysed with results presented. it was ascertained that their genomes consist of gc-type two-chain dna molecules having molecular weight 14-15 mda. it was shown that sedimentation coefficient for all three phage dna is identical and equals 26s. gc-base percentage was calculated for the phage genomes. its value, according to results of sedimentation analysis and melting temperature, was ... | 1997 | 9606835 |
| isolation of new arabidopsis mutants with enhanced disease susceptibility to pseudomonas syringae by direct screening. | to identify plant defense components that are important in restricting the growth of virulent pathogens, we screened for arabidopsis mutants in the accession columbia (carrying the transgene bgl2-gus) that display enhanced disease susceptibility to the virulent bacterial pathogen pseudomonas syringae pv. maculicola (psm) es4326. among six (out of a total of 11 isolated) enhanced disease susceptibility (eds) mutants that were studied in detail, we identified one allele of the previously described ... | 1998 | 9611172 |
| the hrpc and hrpn operons of erwinia chrysanthemi ec16 are flanked by plca and homologs of hemolysin/adhesin genes and accompanying activator/transporter genes. | the hrpc operon of erwinia chrysanthemi ec16 encodes five genes conserved in erwinia amylovora and pseudomonas syringae. mutagenesis indicated that hrcc is required for elicitation of the hypersensitive reaction in tobacco leaves. the unexpected presence of plca and homologs of hemolysin/activator genes in the regions flanking the hrcc and hrpn operons is reported. | 1998 | 9612954 |
| the myristylation motif of pto is not required for disease resistance. | the tomato pto kinase confers resistance to bacterial speck disease caused by strains of pseudomonas syringae pv. tomato that express the avirulence gene avrpto. pto contains a putative myristylation site at its amino terminus that was hypothesized to play a role in localizing pto in the plant cell. site-directed mutagenesis was used to change the invariant glycine residue in the myristylation motif to an alanine. transgenes encoding the mutant pto(g2a) and wild-type pto were placed behind the c ... | 1998 | 9612955 |
| type iii protein secretion systems in bacterial pathogens of animals and plants. | various gram-negative animal and plant pathogens use a novel, sec-independent protein secretion system as a basic virulence mechanism. it is becoming increasingly clear that these so-called type iii secretion systems inject (translocate) proteins into the cytosol of eukaryotic cells, where the translocated proteins facilitate bacterial pathogenesis by specifically interfering with host cell signal transduction and other cellular processes. accordingly, some type iii secretion systems are activat ... | 1998 | 9618447 |
| surface display of zymomonas mobilis levansucrase by using the ice-nucleation protein of pseudomonas syringae. | the ice-nucleation protein (inp) is a glycosyl phosphatidylinositol-anchored outer membrane protein found in some gram-negative bacteria. using pseudomonas syringae inp as an anchoring motif, we investigated the functional display of a foreign protein, zymomonas mobilis levansucrase (levu), on the surface of escherichia coli. the cells expressing inp-levu were found to retain both the ice-nucleation and whole-cell levansucrase enzyme activities, indicating the functional expression of inp-levu h ... | 1998 | 9624691 |
| identification of the gene encoding the tryptophan synthase beta-subunit from chlamydomonas reinhardtii. | we report the isolation of a chlamydomonas reinhardtii cdna that encodes the beta-subunit of tryptophan synthase (tsb). this cdna was cloned by functional complementation of a trp-operon-deleted strain of escherichia coli. hybridization analysis indicated that the gene exists in a single copy. the predicted amino acid sequence showed the greatest identity to tsb polypeptides from other photosynthetic organisms. with the goal of identifying mutations in the gene encoding this enzyme, we isolated ... | 1998 | 9625698 |
| use of a new tetrazolium-based assay to study the production of superoxide radicals by tobacco cell cultures challenged with avirulent zoospores of phytophthora parasitica var nicotianae | the relationship between the production of reactive oxygen species and the hypersensitive response (hr) of tobacco (nicotiana tabacum l. ) toward an incompatible race of the oomycete phytophthora parasitica var nicotianae has been investigated. a new assay for superoxide radical (o2-) production based on reduction of the tetrazolium dye sodium,3'-(1-[phenylamino-carbonyl]-3, 4-tetrazolium)-bis(4-methoxy-6-nitro) benzene-sulfonic acid hydrate (xtt) has enabled the quantitative estimation of perhy ... | 1998 | 9625702 |
| correlation between binding affinity and necrosis-inducing activity of mutant avr9 peptide elicitors. | the race-specific peptide elicitor avr9 of the fungus cladosporium fulvum induces a hypersensitive response only in tomato (lycopersicon esculentum) plants carrying the complementary resistance gene cf-9 (moneymaker-cf9). a binding site for avr9 is present on the plasma membranes of both resistant and susceptible tomato genotypes. we used mutant avr9 peptides to determine the relationship between elicitor activity of these peptides and their affinity to the binding site in the membranes of tomat ... | 1998 | 9625714 |
| glucocorticoid-inducible expression of a bacterial avirulence gene in transgenic arabidopsis induces hypersensitive cell death. | pathogenic strains of pseudomonas syringae pv. tomato carrying the avrrpt2 avirulence gene specifically induce a hypersensitive cell death response in arabidopsis plants that contain the complementary rps2 disease resistance gene. transient expression of avrrpt2 in arabidopsis plants having the rps2 gene has been shown to induce hypersensitive cell death. in order to analyze the effects of conditional expression of avrrpt2 in arabidopsis plants, transgenic lines were constructed that contained t ... | 1998 | 9628020 |
| cloning and characterization of an outer membrane protein of vibrio vulnificus required for heme utilization: regulation of expression and determination of the gene sequence. | vibrio vulnificus is a halophilic, marine pathogen that has been associated with septicemia and serious wound infections in patients with iron overload and preexisting liver disease. for v. vulnificus, the ability to acquire iron from the host has been shown to correlate with virulence. v. vulnificus is able to use host iron sources such as hemoglobin and heme. we previously constructed a fur mutant of v. vulnificus which constitutively expresses at least two iron-regulated outer membrane protei ... | 1998 | 9632577 |
| pad4 functions upstream from salicylic acid to control defense responses in arabidopsis. | the arabidopsis pad4 gene was previously shown to be required for synthesis of camalexin in response to infection by the virulent bacterial pathogen pseudomonas syringae pv maculicola es4326 but not in response to challenge by the non-host fungal pathogen cochliobolus carbonum. in this study, we show that pad4 mutants exhibit defects in defense responses, including camalexin synthesis and pathogenesis-related pr-1 gene expression, when infected by p. s. maculicola es4 326. no such defects were o ... | 1998 | 9634589 |
| resistance gene n-mediated de novo synthesis and activation of a tobacco mitogen-activated protein kinase by tobacco mosaic virus infection. | salicylic acid-induced protein kinase (sipk) and wounding-induced protein kinase (wipk), two distinct members of the mitogen-activated protein (map) kinase family, are activated in tobacco resisting infection by tobacco mosaic virus (tmv). wipk activation by tmv depends on the disease-resistance gene n because infection of susceptible tobacco not carrying the n gene failed to activate wipk. activation of wipk required not only posttranslational phosphorylation but also a preceding rise in its mr ... | 1998 | 9636167 |
| gene-for-gene disease resistance without the hypersensitive response in arabidopsis dnd1 mutant. | the cell death response known as the hypersensitive response (hr) is a central feature of gene-for-gene plant disease resistance. a mutant line of arabidopsis thaliana was identified in which effective gene-for-gene resistance occurs despite the virtual absence of hr cell death. plants mutated at the dnd1 locus are defective in hr cell death but retain characteristic responses to avirulent pseudomonas syringae such as induction of pathogenesis-related gene expression and strong restriction of pa ... | 1998 | 9636234 |
| toxin production by pathovars of pseudomonas syringae and their antagonistic activities against epiphytic microorganisms. | 75 strains of 21 various pseudomonas syringae (p.) pathovars were investigated in different tests for their toxin production. data from literature about the production of the known phytotoxins phaseolotoxin (pv. phaseolicola), tabtoxin (pv. coronafaciens, pv. tabaci), coronatine (pv. atropurpurea, pv. glycinea, pv. maculicola, pv. morsprunorum, pv. tomato), and toxins of the lipodepsipeptide group (pv. aptata, pv. atrofaciens, pv. syringae) could be confirmed. besides, a production of the phytoh ... | 1998 | 9637014 |
| analysis of genes involved in biosynthesis of coronafacic acid, the polyketide component of the phytotoxin coronatine. | coronafacic acid (cfa) is the polyketide component of coronatine (cor), a phytotoxin produced by the plant-pathogenic bacterium pseudomonas syringae. the genes involved in cfa biosynthesis are encoded by a single transcript which encompasses 19 kb of the cor gene cluster. in the present study, the nucleotide sequence was determined for a 4-kb region located at the 3' end of the cfa biosynthetic gene cluster. three open reading frames were identified and designated cfa8, cfa9, and tnp1; the predi ... | 1998 | 9642184 |
| a highly selective pcr protocol for detecting 16s rrna genes of the genus pseudomonas (sensu stricto) in environmental samples. | pseudomonas species are plant, animal, and human pathogens; exhibit plant pathogen-suppressing properties useful in biological control; or express metabolic versatilities valued in biotechnology and bioremediation. specific detection of pseudomonas species in the environment may help us gain a more complete understanding of the ecological significance of these microorganisms. the objective of this study was to develop a pcr protocol for selective detection of pseudomonas (sensu stricto) in envir ... | 1998 | 9647828 |
| development of a lipase fermentation process that uses a recombinant pseudomonas alcaligenes strain. | pseudomonas alcaligenes m-1 secretes an alkaline lipase, which has excellent characteristics for the removal of fatty stains under modern washing conditions. a fed-batch fermentation process based on the secretion of the alkaline lipase from p. alcaligenes was developed. due to the inability of p. alcaligenes to grow on glucose, citric acid and soybean oil were applied as substrates in the batch phase and feed phase, respectively. the gene encoding the high-alkaline lipase from p. alcaligenes wa ... | 1998 | 9647843 |
| the defense-related rice gene pir7b encodes an alpha/beta hydrolase fold protein exhibiting esterase activity towards naphthol as-esters. | acquired resistance of rice to pyricularia oryzae, the causing agent of rice blast, can be induced by inoculation with the non-host pathogen pseudomonas syringae pv. syringae. we have previously cloned a cdna and a corresponding gene (pir7b) whose transcripts accumulate upon infiltration with the resistance-inducing bacteria. the putative encoded product pir7b exhibits significant sequence similarity to two recently cloned hydroxynitrile lyases from manihot esculenta (cassava) and hevea brasisli ... | 1998 | 9652390 |
| copper-binding compounds from methylosinus trichosporium ob3b. | two copper-binding compounds/cofactors (cbcs) were isolated from the spent media of both the wild type and a constitutive soluble methane monooxygenase (smmoc) mutant, pp319 (p. a. phelps et al., appl. environ. microbiol. 58:3701-3708, 1992), of methylosinus trichosporium ob3b. both cbcs are small polypeptides with molecular masses of 1,218 and 779 da for cbc-l1 and cbc-l2, respectively. the amino acid sequence of cbc-l1 is s?mypgs?m, and that of cbc-l2 is spmp?s. copper-free cbcs showed absorpt ... | 1998 | 9658004 |
| differential regulation of rhizobium etli rpon2 gene expression during symbiosis and free-living growth. | the rhizobium etli rpon1 gene, encoding the alternative sigma factor sigma54 (rpon), was recently characterized and shown to be involved in the assimilation of several nitrogen and carbon sources during free-living aerobic growth (j. michiels, t. van soom, i. d'hooghe, b. dombrecht, t. benhassine, p. de wilde, and j. vanderleyden, j. bacteriol. 180:1729-1740, 1998). we identified a second rpon gene copy in r. etli, rpon2, encoding a 54.0-kda protein which displays 59% amino acid identity with th ... | 1998 | 9658006 |
| induction of defense-related responses in cf9 tomato cells by the avr9 elicitor peptide of cladosporium fulvum is developmentally regulated | the avr9 elicitor from the fungal pathogen cladosporium fulvum induces defense-related responses, including cell death, specifically in tomato (lycopersicon esculentum mill.) plants that carry the cf-9 resistance gene. to study biochemical mechanisms of resistance in detail, suspension cultures of tomato cells that carry the cf-9 resistance gene were initiated. treatment of cells with various elicitors, except avr9, induced an oxidative burst, ion fluxes, and expression of defense-related genes. ... | 1998 | 9662523 |
| pathogen-induced changes in the antioxidant status of the apoplast in barley leaves | leaves of two barley (hordeum vulgare l.) isolines, alg-r, which has the dominant mla1 allele conferring hypersensitive race-specific resistance to avirulent races of blumeria graminis, and alg-s, which has the recessive mla1 allele for susceptibility to attack, were inoculated with b. graminis f. sp. hordei. total leaf and apoplastic antioxidants were measured 24 h after inoculation when maximum numbers of attacked cells showed hypersensitive death in alg-r. cytoplasmic contamination of the apo ... | 1998 | 9662553 |
| a newly identified regulator is required for virulence and toxin production in pseudomonas syringae. | the genes lema (which we here redesignate gacs) and gaca encode members of a widely conserved two-component regulatory system. in pseudomonas syringae strain b728a, gacs and gaca are required for lesion formation on bean, as well as for the production of protease and the toxin syringomycin. a gene, designated sala, was discovered that restored syringomycin production to a gacs mutant when present on a multiple-copy plasmid. disruption of chromosomal sala resulted in loss of syringomycin producti ... | 1998 | 9663679 |
| successful search for a resistance gene in tomato targeted against a virulence factor of a fungal pathogen. | the interaction between tomato and its fungal pathogen cladosporium fulvum complies with the gene-for-gene system, in which specific recognition of fungal proteins by plant genotypes with matching resistance genes results in host resistance. two proteins, ecp1 and ecp2, secreted by c. fulvum during infection, are required for full virulence of the fungus on tomato. we chose the most important virulence factor, ecp2, for a targeted search for hypersensitive response (hr)-based resistance among a ... | 1998 | 9671796 |
| the separation of alginate biosynthesis and acetylation in pseudomonas syringae. | seaweed alginate was acetylated by resting cells of pseudomonas syringae subsp. phaseolicola atcc 19304. physiological studies on this strain and its uv-induced mutants showed no correlation between bacterial alginate biosynthesis and acetylation. specific yields of alginate and degree of acetylation in these polymers varied with strain and culture medium. this was indirect evidence that alginate biosynthesis is separate from polysaccharide acetylation. it indicated that the enzyme system involv ... | 1998 | 9674113 |
| the extracytoplasmic function sigma factors: role and regulation. | alternative sigma factors provide a means of regulating gene expression in response to various extracellular changes. one such class of sigma factors appears to control a variety of functions, including expression of heat-shock genes in escherichia coli, biosynthesis of alginates and carotenoids in pseudomonas aeruginosa and myxococcus xanthus, respectively, iron uptake in e. coli and pseudomonas spp., nickel and cobalt efflux in alcaligenes europhus, plant pathogenicity in pseudomonas syringae ... | 1998 | 9680198 |
| molecular characterization of oxa-20, a novel class d beta-lactamase, and its integron from pseudomonas aeruginosa. | the pseudomonas aeruginosa mus clinical isolate produces oxa-18, a pi 5.5 class d extended-spectrum beta-lactamase totally inhibited by clavulanic acid (l. n. philippon, t. naas, a.-t. bouthors, v. barakett, and p. nordmann, antimicrob. agents chemother. 41:2188-2195, 1997). a second beta-lactamase was cloned, and the recombinant escherichia coli clone ppl10 expressed a pi 7.4 beta-lactamase which conferred high levels of amoxicillin and ticarcillin resistance and which was partially inhibited b ... | 1998 | 9687410 |
| phospholipid analysis and fractional reconstitution of the ice nucleation protein activity purified from escherichia coli overexpressing the inaz gene of pseudomonas syringae. | ice nucleation protein was partially purified from the membrane fraction of e. coli carrying inaz from pseudomonas syringae. the ice nucleation protein was totally localized in the bacterial envelope and was extracted by either salt (0.25 m nh4cl) or the nonionic detergent tween 20. the extracted protein was partially purified by sequential passage through deae-52 cellulose and sephacryl-s400 columns. the activity of the purified protein was lost after treatment with phospholipase c, and its act ... | 1998 | 9698431 |
| molecular characterization of an arabidopsis gene encoding hydroperoxide lyase, a cytochrome p-450 that is wound inducible. | hydroperoxide lyase (hpl) cleaves lipid hydroperoxides to produce volatile flavor molecules and also potential signal molecules. we have characterized a gene from arabidopsis that is homologous to a recently cloned hpl from green pepper (capsicum annuum). the deduced protein sequence indicates that this gene encodes a cytochrome p-450 with a structure similar to that of allene oxide synthase. the gene was cloned into an expression vector and expressed in escherichia coli to demonstrate hpl activ ... | 1998 | 9701595 |
| sequence variations in alleles of the avirulence gene avrpphe.r2 from pseudomonas syringae pv. phaseolicola lead to loss of recognition of the avrpphe protein within bean cells and a gain in cultivar-specific virulence. | the bean halo blight pathogen, pseudomonas syringae pv. phaseolicola (psph), is differentiated into nine races based on the presence or absence of five avirulence (avr) genes in the bacterium, which interact with corresponding resistance genes. r1-r5, in phaseolus vulgaris. the resistance gene r2 is matched by avrpphe, which is located adjacent to the cluster of hrp genes that are required for pathogenicity of psph. although only races 2, 4, 5 and 7 are avirulent on cultivars with r2 (inducing t ... | 1998 | 9701811 |
| nitric oxide functions as a signal in plant disease resistance. | recognition of an avirulent pathogen triggers the rapid production of the reactive oxygen intermediates superoxide (o2-) and hydrogen peroxide (h2o2). this oxidative burst drives crosslinking of the cell wall, induces several plant genes involved in cellular protection and defence, and is necessary for the initiation of host cell death in the hypersensitive disease-resistance response. however, this burst is not enough to support a strong disease-resistance response. here we show that nitric oxi ... | 1998 | 9707120 |
| the root knot nematode resistance gene mi from tomato is a member of the leucine zipper, nucleotide binding, leucine-rich repeat family of plant genes. | the mi locus of tomato confers resistance to root knot nematodes. tomato dna spanning the locus was isolated as bacterial artificial chromosome clones, and 52 kb of contiguous dna was sequenced. three open reading frames were identified with similarity to cloned plant disease resistance genes. two of them, mi-1.1 and mi-1.2, appear to be intact genes; the third is a pseudogene. a 4-kb mrna hybridizing with these genes is present in tomato roots. complementation studies using cloned copies of mi- ... | 1998 | 9707531 |
| a cloned erwinia chrysanthemi hrp (type iii protein secretion) system functions in escherichia coli to deliver pseudomonas syringae avr signals to plant cells and to secrete avr proteins in culture. | the hrp (type iii protein secretion) system is essential for the plant parasitic ability of pseudomonas syringae and most gram-negative bacterial plant pathogens. avrb and avrpto are two p. syringae proteins that have biological activity when produced via heterologous gene expression inside plant cells or when produced by hrp+ bacteria. avr-like proteins, presumably injected by the hrp system on bacterial contact with plant cells, appear to underlie pathogenic interactions, but none has been obs ... | 1998 | 9707625 |
| genetically engineered broad-spectrum disease resistance in tomato. | resistance in tomato to the bacterial pathogen pseudomonas syringae pathovar tomato requires pto and prf. mutations that eliminate prf show a loss of both pto resistance and sensitivity to the organophosphate insecticide fenthion, suggesting that prf controls both phenotypes. herein, we report that the overexpression of prf leads to enhanced resistance to a number of normally virulent bacterial and viral pathogens and leads to increased sensitivity to fenthion. these plants express levels of sal ... | 1998 | 9707642 |
| different requirements for eds1 and ndr1 by disease resistance genes define at least two r gene-mediated signaling pathways in arabidopsis. | the arabidopsis genes eds1 and ndr1 were shown previously by mutational analysis to encode essential components of race-specific disease resistance. here, we examined the relative requirements for eds1 and ndr1 by a broad spectrum of resistance (r) genes present in three arabidopsis accessions (columbia, landsberg-erecta, and wassilewskija). we show that there is a strong requirement for eds1 by a subset of r loci (rpp2, rpp4, rpp5, rpp21, and rps4), conferring resistance to the biotrophic oomyc ... | 1998 | 9707643 |
| evidence for growth of strains of the plant epiphytic bacterium erwinia herbicola and transconjugation among the bacterial strains in guts of the silkworm bombyx mori. | growth of plant epiphytic bacteria erwinia herbicola and pseudomonas syringae in guts of the silkworm, bombyx mori, was studied. fifth instar silkworm larvae were fed artificial diets supplemented with these bacteria for 6 to 12 h followed by uncontaminated diets. at 1, 3, and 6 days after feeding, bacteria were isolated from insect guts and feces. a much larger population of e. herbicola was detected in the samples collected 3 and 6 days after the inoculation than in samples collected after 1 d ... | 1998 | 9709009 |
| pas, a novel protein required for protein secretion and attaching and effacing activities of enterohemorrhagic escherichia coli. | enterohemorrhagic escherichia coli (ehec) exhibits a pattern of localized adherence to host cells, with the formation of microcolonies, and induces a specific histopathological phenotype collectively known as the attaching and effacing lesion. the genes encoding the products responsible for this phenotype are located on a 35-kb pathogenicity island designated the locus of enterocyte effacement, which is also shared by enteropathogenic e. coli. we have identified an open reading frame (orf) which ... | 1998 | 9721271 |
| chitinolytic activity in chromobacterium violaceum: substrate analysis and regulation by quorum sensing. | quorum sensing control mediated by n-acyl homoserine lactone (ahl) signaling molecules has been established as a key feature of the regulation of exoenzyme production in many gram-negative bacteria. in chromobacterium violaceum atcc 31532 a number of phenotypic characteristics, including production of the purple pigment violacein, hydrogen cyanide, antibiotics, and exoproteases are known to be regulated by the endogenous ahl n-hexanoyl-l-homoserine lactone (hhl). in this study we show that c. vi ... | 1998 | 9721280 |
| molecular characterization and sequence of a methionine biosynthetic locus from pseudomonas syringae. | two methionine biosynthetic genes in pseudomonas syringae pv. syringae, metx and metw, were isolated, sequenced, and evaluated for their roles in methionine biosynthesis and bacterial fitness on leaf surfaces. the metxw locus was isolated on a 1.8-kb dna fragment that was required for both methionine prototrophy and wild-type epiphytic fitness. sequence analysis identified two consecutive open reading frames (orfs), and in vitro transcription-translation experiments provided strong evidence that ... | 1998 | 9721288 |
| characterization of the hrpc and hrprs operons of pseudomonas syringae pathovars syringae, tomato, and glycinea and analysis of the ability of hrpf, hrpg, hrcc, hrpt, and hrpv mutants to elicit the hypersensitive response and disease in plants. | the species pseudomonas syringae encompasses plant pathogens with differing host specificities and corresponding pathovar designations. p. syringae requires the hrp (type iii protein secretion) system, encoded by a 25-kb cluster of hrp and hrc genes, in order to elicit the hypersensitive response (hr) in nonhosts or to be pathogenic in hosts. dna sequence analysis of the hrpc and hrprs operons of p. syringae pv. syringae 61 (brown spot of beans), p. syringae pv. glycinea u1 (bacterial blight of ... | 1998 | 9721291 |
| negative regulation of hrp genes in pseudomonas syringae by hrpv. | mutations in the five hrp and hrc genes in the hrpc operon of the phytopathogen pseudomonas syringae pv. syringae 61 have different effects on bacterial interactions with host and nonhost plants. the hrcc gene within the hrpc operon encodes an outer membrane component of the hrp secretion system that is conserved in all type iii protein secretion systems and is required for most pathogenic phenotypes and for secretion of the hrpz harpin to the bacterial milieu. the other four genes (in order), h ... | 1998 | 9721292 |
| novel escherichia coli umud' mutants: structure-function insights into sos mutagenesis. | although it has been 10 years since the discovery that the escherichia coli umud protein undergoes a reca-mediated cleavage reaction to generate mutagenically active umud', the function of umud' has yet to be determined. in an attempt to elucidate the role of umud' in sos mutagenesis, we have utilized a colorimetric papillation assay to screen for mutants of a hydroxylamine-treated, low-copy-number umud' plasmid that are unable to promote sos-dependent spontaneous mutagenesis. using such an appr ... | 1998 | 9721309 |
| a response regulator of cyanobacteria integrates diverse environmental signals and is critical for survival under extreme conditions. | microorganisms must sense their environment and rapidly tune their metabolism to ambient conditions to efficiently use available resources. we have identified a gene encoding a response regulator, nblr, that complements a cyanobacterial mutant unable to degrade its light-harvesting complex (phycobilisome), in response to nutrient deprivation. cells of the nblr mutant (i) have more phycobilisomes than wild-type cells during nutrient-replete growth, (ii) do not degrade phycobilisomes during sulfur ... | 1998 | 9724820 |
| cloning, nucleotide sequence, and expression in escherichia coli of levansucrase genes from the plant pathogens pseudomonas syringae pv. glycinea and p. syringae pv. phaseolicola. | plant-pathogenic bacteria produce various extracellular polysaccharides (epss) which may function as virulence factors in diseases caused by these bacteria. the eps levan is synthesized by the extracellular enzyme levansucrase in pseudomonas syringae, erwinia amylovora, and other bacterial species. the lsc genes encoding levansucrase from p. syringae pv. glycinea pg4180 and p. syringae pv. phaseolicola ncppb 1321 were cloned, and their nucleotide sequences were determined. heterologous expressio ... | 1998 | 9726857 |
| contribution of indole-3-acetic acid production to the epiphytic fitness of erwinia herbicola | erwinia herbicola 299r produces large quantities of indole-3-acetic acid (iaa) in culture media supplemented with l-tryptophan. to assess the contribution of iaa production to epiphytic fitness, the population dynamics of the wild-type strain and an iaa-deficient mutant of this strain on leaves were studied. strain 299xyle, an isogenic iaa-deficient mutant of strain 299r, was constructed by insertional interruption of the indolepyruvate decarboxylase gene of strain 299r with the xyle gene, which ... | 1998 | 9726868 |
| linkage map of escherichia coli k-12, edition 10: the traditional map. | this map is an update of the edition 9 map by berlyn et al. (m. k. b. berlyn, k. b. low, and k. e. rudd, p. 1715-1902, in f. c. neidhardt et al., ed., escherichia coli and salmonella: cellular and molecular biology, 2nd ed., vol. 2, 1996). it uses coordinates established by the completed sequence, expressed as 100 minutes for the entire circular map, and adds new genes discovered and established since 1996 and eliminates those shown to correspond to other known genes. the latter are included as ... | 1998 | 9729611 |
| yscb of yersinia pestis functions as a specific chaperone for yopn. | following contact with a eucaryotic cell, yersinia species pathogenic for humans (y. pestis, y. pseudotuberculosis, and y. enterocolitica) export and translocate a distinct set of virulence proteins (yope, yoph, yopj, yopm, and ypka) from the bacterium into the eucaryotic cell. during in vitro growth at 37 degrees c in the presence of calcium, yop secretion is blocked; however, in the absence of calcium, yop secretion is triggered. yop secretion occurs via a plasmid-encoded type iii, or "contact ... | 1998 | 9733695 |
| the o7 antigen of stenotrophomonas maltophilia is a linear d-rhamnan with a trisaccharide repeating unit that is also present in polymers for some pseudomonas and burkholderia species. | the o antigen polymer recovered from the reference strain for stenotrophomonas (xanthomonas or pseudomonas) maltophilia serogroup o7, after mild acid hydrolysis of the lipopolysaccharide, was constructed from d-rhamnose. by means of chemical degradations and nmr studies, the repeating unit of the polymer was shown to be a linear trisaccharide with the structure -->2)-alpha-d-rhap-(1-->3)-alpha-d-rhap-(1-->3)-alpha-d-r hap-(1-->. the same repeating unit is present in the common antigen of pseudom ... | 1998 | 9741084 |
| dna sequencing and analysis of the low-ca2+-response plasmid pcd1 of yersinia pestis kim5. | the low-ca2+-response (lcr) plasmid pcd1 of the plague agent yersinia pestis kim5 was sequenced and analyzed for its genetic structure. pcd1 (70,509 bp) has an incfiia-like replicon and a sopabc-like partition region. we have assigned 60 apparently intact open reading frames (orfs) that are not contained within transposable elements. of these, 47 are proven or possible members of the lcr, a major virulence property of human-pathogenic yersinia spp., that had been identified previously in one or ... | 1998 | 9746557 |
| characterization of the rice pathogen-related protein rir1a and regulation of the corresponding gene. | in rice (oryza sativa l.), local acquired resistance against pyricularia oryzae (cav.), the causal agent of rice blast, can be induced by a preinoculation with the non-host pathogen pseudomonas syringae pv. syringae. we have cloned a cdna (rir1a) and a closely related gene (rir1b) corresponding to transcripts that accumulate in leaf tissue upon inoculation with p. syringae pv. syringae. the cdna encodes a putative 107 amino acid protein, rir1a, that exhibits a putative signal peptide cleavage si ... | 1998 | 9747803 |
| a new class of caulobacter crescentus flagellar genes. | eight caulobacter crescentus flagellar genes, flma, flmb, flmc, flmd, flme, flmf, flmg, and flmh, have been cloned and characterized. these eight genes are clustered in pairs (flmab, flmcd, flmef, and flmgh) that appear to be structurally organized as operons. homology comparisons suggest that the proteins encoded by the flm genes may be involved in posttranslational modification of flagellins or proteins that interact with flagellin monomers prior to their assembly into a flagellar filament. ex ... | 1998 | 9748431 |
| hrpw of erwinia amylovora, a new harpin that contains a domain homologous to pectate lyases of a distinct class. | harpins, such as hrpn of erwinia amylovora, are extracellular glycine-rich proteins that elicit the hypersensitive reaction (hr). we identified hrpw of e. amylovora, which encodes a protein similar to known harpins in that it is acidic, rich in glycine and serine, and lacks cysteine. a putative hrpl-dependent promoter was identified upstream of hrpw, and western blot analysis of hrpl mutants indicated that the production of hrpw is regulated by hrpl. hrpw is secreted via the hrp (type iii) pathw ... | 1998 | 9748455 |
| the pseudomonas syringae pv. tomato hrpw protein has domains similar to harpins and pectate lyases and can elicit the plant hypersensitive response and bind to pectate. | the host-specific plant pathogen pseudomonas syringae elicits the hypersensitive response (hr) in nonhost plants and secretes the hrpz harpin in culture via the hrp (type iii) secretion system. previous genetic evidence suggested the existence of another harpin gene in the p. syringae genome. hrpw was found in a region adjacent to the hrp cluster in p. syringae pv. tomato dc3000. hrpw encodes a 42. 9-kda protein with domains resembling harpins and pectate lyases (pels), respectively. hrpw has ke ... | 1998 | 9748456 |
| the cytochrome c maturation operon is involved in manganese oxidation in pseudomonas putida gb-1. | a pseudomonas putida strain, strain gb-1, oxidizes mn2+ to mn oxide in the early stationary growth phase. it also secretes a siderophore (identified as pyoverdine) when it is subjected to iron limitation. after transposon (tn5) mutagenesis several classes of mutants with differences in mn2+ oxidation and/or secretion of the mn2+-oxidizing activity were identified. preliminary analysis of the tn5 insertion site in one of the nonoxidizing mutants suggested that a multicopper oxidase-related enzyme ... | 1998 | 9758767 |
| distribution and life strategies of two bacterial populations in a eutrophic lake | monoclonal antibodies and epifluorescence microscopy were used to determine the depth distribution of two indigenous bacterial populations in the stratified lake plusssee and characterize their life strategies. populations of comamonas acidovorans px54 showed a depth distribution with maximum abundances in the oxic epilimnion, whereas aeromonas hydrophila pu7718 showed a depth distribution with maximum abundances in the anoxic thermocline layer (metalimnion), i. e., in the water layer with the h ... | 1998 | 9758799 |
| genetic characterization of pseudomonas syringae pv. syringae strains from stone fruits in california | strains of pseudomonas syringae pv. syringae were isolated from healthy and diseased stone fruit tissues sampled from 43 orchard sites in california in 1995 and 1996. these strains, together with p. syringae strains from other hosts and pathovars, were tested for pathogenicity and the presence of the syrb and syrc genes and were genetically characterized by using enterobacterial repetitive intergenic consensus (eric) primers and pcr. all 89 strains of p. syringae pv. syringae tested were moderat ... | 1998 | 9758805 |
| characterization of genes involved in biosynthesis of a novel antibiotic from burkholderia cepacia bc11 and their role in biological control of rhizoctonia solani. | genetic manipulation of fluorescent pseudomonads has provided major insight into their production of antifungal molecules and their role in biological control of plant disease. burkholderia cepacia also produces antifungal activities, but its biological control activity is much less well characterized, in part due to difficulties in applying genetic tools. here we report genetic and biochemical characterization of a soil isolate of b. cepacia relating to its production of an unusual antibiotic t ... | 1998 | 9758823 |
| closely related plasmid replicons coexisting in the phytopathogen pseudomonas syringae show a mosaic organization of the replication region and altered incompatibility behavior | many pseudomonas syringae strains contain native plasmids that are important for host-pathogen interactions, and most of them contain several coexisting plasmids (ppt23a-like plasmids) that cross-hybridize to replication sequences from ppt23a, which also carries a gene cluster coding for the phytotoxin coronatine in p. syringae pv. tomato pt23. in this study, three functional ppt23a-like replicons were cloned from p. syringae pv. glycinea race 6, suggesting that the compatibility of highly relat ... | 1998 | 9758824 |
| pcr-based detection of the causal agent of watermark disease in willows (salix spp.) | the watermark disease, caused by brenneria salicis (formerly erwinia salicis), is of significant concern wherever tree-forming willows are grown or occur naturally. the movement of infected, asymptomatic cuttings is a major cause of pathogen dispersal. a reliable and sensitive diagnostic procedure is necessary for the safe movement of willow planting material. we derived primers from the nucleotide sequence of the 16s rrna gene of b. salicis for the development of a pcr to detect this pathogen. ... | 1998 | 9758827 |
| resistance to tellurite as a selection marker for genetic manipulations of pseudomonas strains. | resistance to the toxic compound potassium tellurite (telr) has been employed as a selection marker built into a set of transposon vectors and broad-host-range plasmids tailored for genetic manipulations of pseudomonas strains potentially destined for environmental release. in this study, the activated telr determinants encoded by the cryptic telab genes of plasmid rk2 were produced, along with the associated kila gene, as dna cassettes compatible with cognate vectors. in one case, the telr dete ... | 1998 | 9758838 |
| efficacy of syringomycin e in a murine model of vaginal candidiasis. | syringomycin e (sr-e), a new antifungal produced by the bacterium pseudomonas syringae pv. syringae, was evaluated in a murine vaginal candidiasis model. in one study, mice were treated intravaginally b.i.d. for 4 days with drug carrier, sr-e 2% in either peg-400 or peg-ointment, or 1% clotrimazole as a positive control. quantitative vaginal cultures were taken prior to treatment on day 1 and on days 5, 6, and 7. both formulations showed a reduction of yeast colonization in the vaginas on day 5 ... | 1998 | 9766466 |
| the espb protein of enteropathogenic escherichia coli is targeted to the cytoplasm of infected hela cells. | the espb protein of enteropathogenic escherichia coli (epec) is exported via a type iii secretion apparatus. espb is critical for signaling the host cell and for the development of the attaching and effacing lesion characteristic of epec infection. we used cellular fractionation and confocal laser scanning microscopy to determine the cellular location of espb during infection of hela cells. both methods indicated that espb is targeted to the cytoplasm of infected cells. using mutants, we found t ... | 1998 | 9784563 |
| characterization of the phytopathogen pseudomonas syringae pathovar ribicola ncppb 963. | in 1939, a bacterial spot caused severe defoliation of ribes aureum (golden currant) the causal agent is now recognized as pseudomonas syringae pathovar ribicola. this communication extends the phenotype of the only identified strain of p. syringae pv. ribicola, which is reminiscent of those of other pathovars, and provides a molecular biological characterization. a minimum size of 5.55 mb for the bacterial genome was obtained using pulsed-field electrophoresis. the sds-page outer-membrane profi ... | 1998 | 9785483 |
| initial binding of shiga toxin-producing escherichia coli to host cells and subsequent induction of actin rearrangements depend on filamentous espa-containing surface appendages. | shiga toxin-producing escherichia coli (stec) induce so-called attaching and effacing lesions that enable the tight adherence of these pathogens to the gut epithelium. all of the genes necessary for this process are present in the locus of enterocyte effacement, which encodes a type iii secretion system, the secreted esp proteins and the surface protein intimin. in this study we sequenced the espa gene of stec, generated and characterized a corresponding deletion mutant and raised espa-specific ... | 1998 | 9786192 |
| the yersinia deadly kiss. | | 1998 | 9791096 |
| molecular genetic analysis of phosphite and hypophosphite oxidation by pseudomonas stutzeri wm88. | the first molecular and genetic characterization of a biochemical pathway for oxidation of the reduced phosphorus (p) compounds phosphite and hypophosphite is reported. the pathway was identified in pseudomonas stutzeri wm88, which was chosen for detailed studies from a group of organisms isolated based on their ability to oxidize hypophosphite (+1 valence) and phosphite (+3 valence) to phosphate (+5 valence). the genes required for oxidation of both compounds by p. stutzeri wm88 were cloned on ... | 1998 | 9791102 |
| physiological diversity of the rhizosphere diazotroph assemblages of selected salt marsh grasses. | rhizosphere diazotroph assemblages of salt marsh grasses are thought to be influenced by host plant species and by a number of porewater geochemical parameters. several geochemical variables can adversely affect plant productivity and spatial distributions, resulting in strong zonation of plant species and growth forms. this geochemically induced stress may also influence the species compositions and distributions of rhizosphere diazotroph assemblages, but little is currently known about these o ... | 1998 | 9797277 |
| detection of ralstonia solanacearum, which causes brown rot of potato, by fluorescent in situ hybridization with 23s rrna-targeted probes. | during the past few years, ralstonia (pseudomonas) solanacearum race 3, biovar 2, was repeatedly found in potatoes in western europe. to detect this bacterium in potato tissue samples, we developed a method based on fluorescent in situ hybridization (fish). the nearly complete genes encoding 23s rrna of five r. solanacearum strains and one ralstonia pickettii strain were pcr amplified, sequenced, and analyzed by sequence alignment. this resulted in the construction of an unrooted tree and suppor ... | 1998 | 9797321 |
| characterization of type iv pilus genes in pseudomonas syringae pv. tomato dc3000. | many strains of pseudomonas syringae produce retractile pili that act as receptors for lytic bacteriophage phi 6. as these are also characteristics of type iv pili, it was postulated that p. syringae may possess genes for type iv pilus biogenesis. a cosmid clone bank of p. syringae pv. tomato dc3000 genomic dna was used to complement a mutant of pseudomonas aeruginosa defective in the pild (xcpa) prepilin peptidase gene by selection for restoration of extracellular protein secretion, a function ... | 1998 | 9805392 |
| a nitrilase-like protein interacts with gcc box dna-binding proteins involved in ethylene and defense responses. | ethylene-responsive element-binding proteins (erebps) of tobacco (nicotiana tabacum l.) bind to the gcc box of many pathogenesis-related (pr) gene promoters, including osmotin (pr-5). the two gcc boxes on the osmotin promoter are known to be required, but not sufficient, for maximal ethylene responsiveness. erebps participate in the signal transduction pathway leading from exogenous ethylene application and pathogen infection to pr gene induction. in this study erebp3 was used as bait in a yeast ... | 1998 | 9808731 |
| localized changes in peroxidase activity accompany hydrogen peroxide generation during the development of a nonhost hypersensitive reaction in lettuce | peroxidase activity was characterized in lettuce (lactuca sativa l.) leaf tissue. changes in the activity and distribution of the enzyme were examined during the development of a nonhost hypersensitive reaction (hr) induced by pseudomonas syringae (p. s.) pv phaseolicola and in response to an hrp mutant of the bacterium. assays of activity in tissue extracts revealed ph optima of 4.5, 6.0, 5.5 to 6.0, and 6.0 to 6.5 for the substrates tetramethylbenzidine, guaiacol, caffeic acid, and chlorogenic ... | 1998 | 9808752 |
| role of ergosterol in growth inhibition of saccharomyces cerevisiae by syringomycin e. | the antifungal activity of the lipodepsipeptide syringomycin e from pseudomonas syringae pv. syringae is modulated by sterols. to study the requirement of the predominant fungal sterol, ergosterol, in syringomycin e action, the sterol composition of saccharomyces cerevisiae sterol auxotroph strain fy-14 was modified and sensitivity to syringomycin e examined. cells containing solely ergosterol, cholesterol, beta-sitosterol or stigmasterol were sensitive to syringomycin e with the latter two bein ... | 1998 | 9809422 |
| mutational analysis of the role of nucleoside triphosphatase p4 in the assembly of the rna polymerase complex of bacteriophage phi6. | bacteriophage phi6 is a complex enveloped double-stranded rna virus with a segmented genome and replication strategy quite similar to that of the reoviridae. an in vitro packaging and replication system using purified components is available. the positive-polarity genomic segments are translocated into a preformed polymerase complex (procapsid) particle. this particle is composed of four proteins: the shell-forming protein p1, the rna polymerase p2, and two proteins active in packaging. protein ... | 1998 | 9811745 |
| solution conformation of the pseudomonas syringae msu 16h phytotoxic lipodepsipeptide pseudomycin a determined by computer simulations using distance geometry and molecular dynamics from nmr data. | pseudomycin a is a cyclic lipodepsinonapeptide phytotoxin produced by a strain of the plant pathogenic bacterium pseudomonas syringae. like other members of this family of bacterial metabolites, it is characterised by a fatty acylated cyclic peptide with mixed chirality and lactonic closure. several biological activities of pseudomycin a are lower than those found for some of its congeners, a difference which might depend on the diverse number and distribution of charged residues in the peptide ... | 1998 | 9826192 |
| the type iv leader peptidase/n-methyltransferase of vibrio vulnificus controls factors required for adherence to hep-2 cells and virulence in iron-overloaded mice. | vibrio vulnificus expresses a number of potential virulence determinants that may contribute to its ability to cause a severe and rapidly disseminating septicemia in susceptible hosts. we have cloned and characterized two genes encoding products related to components of the type iv pilus biogenesis and general secretory (type ii) pathways by complementation of a type iv peptidase/n-methyltransferase (pild) mutant of pseudomonas aeruginosa with a v. vulnificus genomic library. one of the genes (v ... | 1998 | 9826339 |
| complete dna sequence and detailed analysis of the yersinia pestis kim5 plasmid encoding murine toxin and capsular antigen. | yersinia pestis, the causative agent of plague, harbors at least three plasmids necessary for full virulence of the organism, two of which are species specific. one of the y. pestis-specific plasmids, pmt1, is thought to promote deep tissue invasion, resulting in more acute onset of symptoms and death. we determined the entire nucleotide sequence of y. pestis kim5 pmt1 and identified potential open reading frames (orfs) encoded by the 100,990-bp molecule. based on codon usage for known yersinial ... | 1998 | 9826348 |
| modulation of expression of the toxr regulon in vibrio cholerae by a member of the two-component family of response regulators. | the toxrs system in vibrio cholerae plays a central role in the modulation of virulence gene expression in response to environmental stimuli. an integration of multiple signalling inputs mediated by toxr, -s, and -t controls virulence gene expression leading to cholera toxin (ct) production. recently, we identified a new virulence locus, vara (virulence associated regulator), in classical v. cholerae o1 that positively controls transcription of tcpa, the major subunit of the toxin-coregulated pi ... | 1998 | 9826365 |
| cyp76c2, an arabidopsis thaliana cytochrome p450 gene expressed during hypersensitive and developmental cell death. | the characterisation of an arabidopsis thaliana cytochrome p450-encoding cdna clone, b72, preferentially expressed during the hypersensitive response (hr) provoked by the bacterial pathogen pseudomonas syringae pathovar maculicola, is reported. the b72 cdna clone corresponded to the cyp76c2 gene, which belongs to a small multigene family comprising four genes. hr-triggering bacteria harbouring different avirulence genes induced the accumulation of transcripts of this p450 gene. cyp76c2 gene expr ... | 1998 | 9827554 |
| characterization of corr, a transcriptional activator which is required for biosynthesis of the phytotoxin coronatine. | coronatine (cor) is a plasmid-encoded phytotoxin synthesized by several pathovars of phytopathogenic pseudomonas syringae. the cor biosynthetic gene cluster in p. syringae pv. glycinea pg4180 is encoded by a 32-kb region which contains both the structural and regulatory genes needed for cor synthesis. the regulatory region contains three genes: corp, cors, and corr. cors is thought to function as a histidine protein kinase, whereas corp and corr show relatedness to response regulators of the two ... | 1998 | 9829934 |
| combined physical and genetic map of the pseudomonas putida kt2440 chromosome. | a combined physical and genetic map of the pseudomonas putida kt2440 genome was constructed from data obtained by pulsed-field gel electrophoresis techniques (pfge) and southern hybridization. circular genome size was estimated at 6.0 mb by adding the sizes of 19 swai, 9 pmei, 6 paci, and 6 i-ceui fragments. a complete physical map was achieved by combining the results of (i) analysis of pfge of the dna fragments resulting from digestion of the whole genome with pmei, swai, i-ceui, and paci as w ... | 1998 | 9829947 |
| expression of the pseudomonas aeruginosa gentamicin resistance gene aacc3 in escherichia coli. | the pseudomonas aeruginosa aacc3 gene was expressed in escherichia coli after cloning of the single gene behind the strong tac promoter. in the original pseudomonas strain, aacc3 is preceded by cysc; together they form a single transcription unit. the ribosome-binding site and start codon of aacc3 are involved in a putative intercistronic hairpin, the stability of which interfered with the aminoglycoside resistance level. in northern blots, full-length transcripts comprising both cysc and aacc3 ... | 1998 | 9835511 |
| psychrotolerant bacteria isolated from arctic soil that degrade polychlorinated biphenyls at low temperatures | psychrotolerant polychlorinated biphenyl (pcb)-degrading bacteria were isolated at 7 degreesc from pcb-contaminated arctic soil by using biphenyl as the sole organic carbon source. these isolates were distinguished from each other by differences in substrates that supported growth and substrates that were oxidized. 16s ribosomal dna sequences suggest that these isolates are most closely related to the genus pseudomonas. total removal of aroclor 1242, and rates of removal of selected pcb congener ... | 1998 | 9835569 |
| ralstonia solanacearum pectin methylesterase is required for growth on methylated pectin but not for bacterial wilt virulence | ralstonia (pseudomonas) solanacearum causes bacterial wilt, a serious disease of many crop plants. the pathogen produces several extracellular plant cell wall-degrading enzymes, including polygalacturonases (pgs) and pectin methylesterase (pme). pme removes methyl groups from pectin, thereby facilitating subsequent breakdown of this cell wall component by pgs, which are known bacterial wilt virulence factors. r. solanacearum pgs could not degrade 93% methylated pectin unless the substrate was fi ... | 1998 | 9835583 |