| structure and activity of persicomycins, toxins produced by a pseudomonas syringae pv. persicae/prunus persica isolate. | a toxigenic property has been demonstrated in a pseudomonas syringae pv. persicae/prunus persica isolate. several substances, which are named persicomycins, have been purified in variable quantities from cultures. the structures of four of them were established by nmr and chemical ionization mass spectrometry. these compounds are 3-(3'-hydroxy)hydroxy fatty acids and thus represent a new family among the phytobacterial toxins. other minor substances have also been isolated and have been shown to ... | 1996 | 8774716 |
| systemic resistance in arabidopsis induced by biocontrol bacteria is independent of salicylic acid accumulation and pathogenesis-related gene expression. | systemic acquired resistance is a pathogen-inducible defense mechanism in plants. the resistant state is dependent on endogenous accumulation of salicylic acid (sa) and is characterized by the activation of genes encoding pathogenesis-related (pr) proteins. recently, selected nonpathogenic, root-colonizing biocontrol bacteria have been shown to trigger a systemic resistance response as well. to study the molecular basis underlying this type of systemic resistance, we developed an arabidopsis-bas ... | 1996 | 8776893 |
| distribution of pseudomonas syringae pathovars into twenty-three o serogroups. | serological reactions of pseudomonas syringae and pseudomonas viridiflava were studied by ouchterlony double diffusion. a total of 55 polyclonal antisera, containing anti-lipopolysaccharide (anti-lps) precipitating antibodies, were cross-tested against antigenic suspensions of 51 strains. twenty-three o serogroups were defined, primarily on the reaction of the type strains. two families of o serogroups showed antigenic crossreactivities (pha, mop1, mop2, mop3, hel1, hel2, and syr1; persavtom1, p ... | 1996 | 8779574 |
| two cold-inducible genes encoding lipid transfer protein ltp4 from barley show differential responses to bacterial pathogens. | the barley genes hvltp4.2 and hvltp4.3 both encode the lipid transfer protein ltp4 and are less than 1 kb apart in tail-to-tail orientation. they differ in their non-coding regions from each other and from the gene corresponding to a previously reported ltp4 cdna (now ltp4.1). southern blot analysis indicated the existence of three or more ltp4 genes per haploid genome and showed considerable polymorphism among barley cultivars. we have investigated the transient expression of genes hvltp4.2 and ... | 1996 | 8804389 |
| the rsma- mutants of erwinia carotovora subsp. carotovora strain ecc71 overexpress hrpnecc and elicit a hypersensitive reaction-like response in tobacco leaves. | erwinia carotovora subsp. carotovora wild-type strain ecc71 does not elicit the hypersensitive reaction (hr) in tobacco leaves. by mini-tn5-km and chemical mutagenesis we have isolated rsma- mutants of ecc71 that produce high basal levels of pectate lyases, polygalacturonase, cellulase, and protease; they also are hypervirulent. the rsma- mutants, but not their parent strains, elicit an hr-like response in tobacco leaves. this reaction is characterized by the rapid appearance of water soaking fo ... | 1996 | 8810071 |
| use of translational fusions to the maltose-binding protein to produce and purify proteins in pseudomonas syringae and assess their activity in vivo. | a simple approach is described for the production and purification of proteins in pseudomonas syringae. the strategy involves the use of the tac promoter, the maltose-binding protein, and the broad-host-range vector, prk415. this approach was used to partially purify two proteins involved in coronatine biosynthesis from p. syringae. the activity of the fusions was demonstrated in vivo in complementation experiments using the appropriate mutants. | 1996 | 8810079 |
| analysis of the role of the pseudomonas syringae pv. syringae hrpz harpin in elicitation of the hypersensitive response in tobacco using functionally non-polar hrpz deletion mutations, truncated hrpz fragments, and hrma mutations. | pseudomonas syringae pv. syringae, like many plant pathogenic bacteria, secretes a 'harpin' protein that can elicit the hypersensitive response (hr), a defensive cellular suicide, in non-host plants. the harpin-encoding hrpz gene is located in an operon that also encodes hrp secretion pathway components and is part of the functional cluster of hrp genes carried on cosmid phir11 that enables saprophytic bacteria like escherichia coli and pseudomonas fluorescens to elicit the hr in tobacco leaves. ... | 1996 | 8820642 |
| syr2, a gene necessary for syringomycin growth inhibition of saccharomyces cerevisiae. | the pseudomonas syringae cyclic lipodepsipeptide syringomycin inhibits the growth of saccharomyces cerevisiae. a novel yeast gene, syr2, was found to complement two syringomycin-resistant s. cerevisiae mutants. syr2 was cloned, sequenced, and shown to encode a 349 amino acid protein located in the endoplasmic reticulum. syr2 was identical to sur2, which is involved in survival during nutritional starvation. gene disruption or overexpression of syr2 did not affect cell viability or ergosterol lev ... | 1996 | 8868422 |
| defense reaction in medicago sativa: a gene encoding a class 10 pr protein is expressed in vascular bundles. | infiltration of medicago sativa leaves with a suspension of pseudomonas syringae pv. pisi elicits the accumulation of several mrna classes. a clone, designated as mspr10-1, encoding a polypeptide exhibiting strong similarity to the class 10 pr protein was isolated and characterized from a cdna library prepared from leaf mrna. the corresponding gene was shown to be developmentally regulated: except in roots, its expression was not detectable in other analyzed organs of healthy plants (hypocotyls, ... | 1996 | 8870270 |
| mode of action of the arabidopsis thaliana phytoalexin camalexin and its role in arabidopsis-pathogen interactions. | the virulent arabidopsis thaliana pathogen pseudomonas syringae pv. maculicola strain es4326 (psm es4326) and other gram-negative bacteria are sensitive to camalexin (3-thiazol-2'-yl-indole), the arabidopsis phytoalexin. furthermore, psm es4326 is unable to degrade camalexin or to become tolerant to it. apparently, psm es4326 is a successful pathogen even though it elicits synthesis of a host phytoalexin to which it is sensitive. assays of membrane integrity revealed that, like other phytoalexin ... | 1996 | 8870273 |
| the pseudomonas syringae hrp regulation and secretion system controls the production and secretion of multiple extracellular proteins. | pseudomonas syringae pv. tomato dc3000 produces seven to eight major extracellular proteins (exps) in a minimal medium inducing hrp genes. using a polyclonal antibody against dc3000 exps, we have determined that the production and secretion of five exps (exp-60, exp-45, exp-43, exp-22, and exp-10) are under the control of the hrp regulation and secretion system. | 1996 | 8892851 |
| hrp gene-dependent induction of hin1: a plant gene activated rapidly by both harpins and the avrpto gene-mediated signal. | two classes of bacterial genes are involved in the elicitation of the plant hypersensitive response (hr) in resistant plants: hrp genes and avr genes. hrp genes have been shown to be involved in the production and secretion of a new class of bacterial virulence/avirulence proteins, including harpin of erwinia amylovora and harpinpss of pseudomonas syringae. the ability of avr genes in the elicitation of the hr/resistance is dependent on functional hrp genes. the relationships between harpins and ... | 1996 | 8893538 |
| resistance to ultraviolet light in pseudomonas syringae: sequence and functional analysis of the plasmid-encoded rulab genes. | the indigenous plasmids, ppsr1 and ppsr5, were each shown to confer resistance to ultraviolet light (uv) in pseudomonas syringae (ps) pv. syringae ff5. the uv-resistance (uvr) determinant was subcloned from a cosmid library of ppsr1, and sequence analysis revealed the presence of two orfs, designated rulab which are homologous to the escherichia coli umudc mutagenic dna repair systems and other plasmid-encoded uvr operons. amino acid (aa) alignments indicated that rulab are most closely related ... | 1996 | 8921848 |
| immunochemical characterization of o polysaccharides composing the alpha-d-rhamnose backbone of lipopolysaccharide of pseudomonas syringae and classification of bacteria into serogroups o1 and o2 with monoclonal antibodies. | murine monoclonal antibodies (mabs) reacting with pseudomonas syringae lipopolysaccharide (lps) o polysaccharides (ops) composed of tetra- and tri-alpha-d-rhamnose repeats in the backbone [3)d-rha(alpha1-3)d-rha(alpha1-2)d-rha(alpha1-2)d-rha(alpha1] and [3)d-rha(alpha1-3)d-rha(alpha1-2)d-rha(alpha1] were generated and used for immunochemical analysis and for serological classification of the bacteria. a total of 195 of 358 p. syringae strains tested representing 21 pathovars were shown to share ... | 1996 | 8932301 |
| the azotobacter vinelandii gene algj encodes an outer-membrane protein presumably involved in export of alginate. | the algj gene from azotobacter vinelandii was cloned using a labelled rna probe representing the coding region of the alge gene from pseudomonas aeruginosa. dna sequencing revealed an orf of 1452 bp encoding a protein of 484 amino acid residues with a calculated molecular mass of 54611 da. an rna probe corresponding to alge was also used for southern hybridization of chromosomal dna, which showed that alge-related dna sequences are also present in the alginate-producing phytopathogen species pse ... | 1996 | 8936313 |
| molecular basis of gene-for-gene specificity in bacterial speck disease of tomato | transient expression of the pseudomonas syringae avirulence gene avrpto in plant cells resulted in a pto-dependent necrosis. the avrpto avirulence protein was observed to interact directly with the pto resistance protein in the yeast two-hybrid system. mutations in the pto and avrpto genes which reduce in vivo activity had parallel effects on association in the two-hybrid assay. these data suggest that during infection the pathogen delivers avrpto into the plant host cell and that resistance is ... | 1996 | 8953034 |
| characterization of eds1, a mutation in arabidopsis suppressing resistance to peronospora parasitica specified by several different rpp genes. | the interaction between arabidopsis and the biotrophic oomycete peronospora parasitica (downy mildew) provides an attractive model pathosystem to identify molecular components of the host that are required for genotype-specific recognition of the parasite. these components are the so-called rpp genes (for resistance to p. parasitica). mutational analysis of the ecotype wassilewskija (ws-0) revealed an rpp-nonspecific locus called eds1 (for enhanced disease susceptibility) that is required for th ... | 1996 | 8953768 |
| characterization of two epiphytic bacteria from soybean leaves with antagonistic activities against pseudomonas syringae pv. glycinea. | the strains 48b/90 and 22d/93 are naturally occurring ephiphytes which were isolated from soybean leaves. on the basis of pheno- and genotypic characteristics 48b/90 was identified as erwinia herbicola and 22d/93 as pseudomonas syringae. these two isolates produced biological active substances against different indicator organisms. the e. herbicola strain showed clear antagonistic properties against escherichia coli and pseudomonas syringae pv. glycinea, but not against geotrichum candidum. 22d/ ... | 1996 | 8956493 |
| isolation and characterization of a tobacco mosaic virus-inducible myb oncogene homolog from tobacco. | salicylic acid (sa) plays an important role in signaling the activation of plant defense responses against pathogen attack including induction of pathogenesis-related (pr) proteins. to gain further insight into the sa-mediated signal transduction pathway, we have isolated and characterized a tobacco mosaic virus (tmv)-inducible myb oncogene homolog (myb1) from tobacco. the myb1 gene was induced upon tmv infection during both the hypersensitive response and development of systemic acquired resist ... | 1996 | 8962166 |
| comparative analysis of pseudomonas syringae pv. actinidiae and pv. phaseolicola based on phaseolotoxin-resistant ornithine carbamoyltransferase gene (argk) and 16s-23s rrna intergenic spacer sequences. | pseudomonas syringae pv. phaseolicola, which causes halo blight on various legumes, and pv. actinidiae, responsible for canker or leaf spot on actinidia plants, are known as phaseolotoxin producers, and the former possesses phaseolotoxin-resistant ornithine carbamoyltransferase (roct) which confers resistance to the toxin. we confirmed that the latter is also resistant to phaseolotoxin and possesses roct, and we compared the two pathovars by using sequence data of the roct gene and the intergeni ... | 1997 | 8979356 |
| molecular recognition of pathogen attack occurs inside of plant cells in plant disease resistance specified by the arabidopsis genes rps2 and rpm1. | the arabidopsis thaliana disease resistance genes rps2 and rpm1 belong to a class of plant disease resistance genes that encode proteins that contain an n-terminal tripartite nucleotide binding site (nbs) and a c-terminal tandem array of leucine-rich repeats. rps2 and rpm1 confer resistance to strains of the bacterial phytopathogen pseudomonas syringae carrying the avirulence genes avrrpt2 and avrb, respectively. in these gene-for-gene relationships, it has been proposed that pathogen avirulence ... | 1996 | 8986840 |
| the sink-specific and stress-regulated arabidopsis stp4 gene: enhanced expression of a gene encoding a monosaccharide transporter by wounding, elicitors, and pathogen challenge. | a cdna for the arabidopsis stp4 gene (for sugar transport protein 4) was isolated, and the properties of the encoded protein were studied in schizosaccharomyces pombe. the stp4 monosaccharide h+ symporter is composed of 514 amino acids and has a calculated molecular mass of 57.1 kd. rna gel blot analyses revealed that stp4 is expressed primarily in roots and flowers of arabidopsis. this was shown in more detail with stp4 promoter-beta-glucuronidase (gus) plants yielding strong stp4-driven gus ac ... | 1996 | 8989877 |
| characterization of dapb, a gene required by pseudomonas syringae pv. tabaci br2.024 for lysine and tabtoxinine-beta-lactam biosynthesis. | the dapb gene, which encodes l-2,3-dihydrodipicolinate reductase, the second enzyme of the lysine branch of the aspartic amino acid family, was cloned and sequenced from a tabtoxin-producing bacterium, pseudomonas syringae pv. tabaci br2.024. the deduced amino acid sequence shared 60 to 90% identity to known dapb gene products from gram-negative bacteria and 19 to 21% identity to the dapb products from gram-positive bacteria. the consensus sequence for the nad(p)h binding site [(v/i)(a/g)(v/i)xg ... | 1997 | 8990304 |
| characterisation 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 pathogen, pseudomonas syringae. in the present study we have determined the nucleotide sequence of a 3.92-kb dna fragment involved in cfa biosynthesis. analysis of the sequence revealed four complete open reading frames (orfs) designated cfa1 to cfa4 and one incomplete orf (cfa5), all transcribed in the same direction. the predicted translation products of cfa1, cfa2 and cfa3 showed related ... | 1996 | 8996103 |
| relative expression and stability of a chromosomally integrated and plasmid-borne marker gene fusion in environmentally competent bacteria. | a xyle-icec transcriptional fusion was created by ligatinga dna fragment harboring the cloned xyle structural gene from the tol plasmid of pseudomonas putida mt-2 into the cloned icec gene of pseudomonas syringae cit7. this fusion construct was integrated into the chromosome of pseudomonas syringae cit7 by homologous recombination. both cis-merodiploid strain cit7m17 and marker exchange strain cit7h69 produced the xyle gene product, catechol2,3-dioxygenase. strain cit7m17, in which xyle was infl ... | 1997 | 9003582 |
| transformation of pbr322-derived plasmids in phytopathogenicpseudomonas avenae and enhanced transformation in itsproline-auxotrophic mutant | efficient transformation of pbr322 and its derivedplasmids, which have been widely used as cloning vectors in escherichiacoli, was observed in pseudomonas avenae (k1), the pathogen ofleaf blight disease in cereals. moreover, there was a 10- to 50-foldtransformation efficiency (1.3-3.0 x 10(6)/&mgr;g dna) in theproline-auxotrophic mutant (pr47), whose virulence to rice seedlingsdecreased. similar enhancement of the frequency of transfer by mobilizationof rsf1010, a broad host range plasmid, was o ... | 1997 | 9009065 |
| alleles of pto and fen occur in bacterial speck-susceptible and fenthion-insensitive tomato cultivars and encode active protein kinases. | the pto gene was derived originally from the wild tomato species lycopersicon pimpinellifolium and confers resistance to pseudomonas syringae pv tomato strains expressing the avirulence gene avrpto. the fen gene is also derived from l. pimpinellifolium and confers sensitivity to the insecticide fenthion. we have now isolated and characterized the alleles of pto and fen from cultivated tomato, l. esculentum, and designated them pto and fen. high conservation of genome organization between the two ... | 1997 | 9014365 |
| assessment of genetic diversity among strains of pseudomonas syringae by pcr-restriction fragment length polymorphism analysis of rrna operons with special emphasis on p. syringae pv. tomato. | phylogenetic relationships among 77 bacterial strains belonging to pseudomonas syringae and pseudomonas viridiflava species were assessed by analysis of the pcr-restriction fragment length polymorphism (rflp) patterns of three dna fragments corresponding to rrs and rrl genes and the internal transcribed spacer, its1. no difference among all strains in rrs and rrl genes was observed with 14 restriction enzymes, which confirms the close relationships existing between these two species. the nucleot ... | 1997 | 9023928 |
| the hrpa and hrpc operons of erwinia amylovora encode components of a type iii pathway that secretes harpin. | a 6.2-kb region of dna corresponding to complementation groups ii and iii of the erwinia amylovora hrp gene cluster was analyzed. transposon mutagenesis indicated that the two complementation groups are required for secretion of harpin, an elicitor of the hypersensitive reaction. the sequence of the region revealed 10 open reading frames in two putative transcription units: hrpa, hrpb, hrcj, hrpd, and hrpe in the hrpa operon (group iii) and hrpf, hrpg, hrcc, hrpt, and hrpv in the hrpc operon (gr ... | 1997 | 9045830 |
| rapid stimulation of a soybean protein-serine kinase that phosphorylates a novel bzip dna-binding protein, g/hbf-1, during the induction of early transcription-dependent defenses. | the g-box (cacgtg) and h-box (cctacc) cis elements function in the activation of phenylpropanoid biosynthetic genes involved in the elaboration of lignin precursors, phytoalexins and the secondary signal salicylic acid as early responses to pathogen attack. we have isolated a soybean cdna encoding a novel bzip protein, g/hbf-1, which binds to both the g-box and adjacent h-box in the proximal region of the chalcone synthase chs15 promoter. while g/hbf-1 transcript and protein levels do not increa ... | 1997 | 9049302 |
| expression of avrpphb, an avirulence gene from pseudomonas syringae pv. phaseolicola, and the delivery of signals causing the hypersensitive reaction in bean. | protein production encoded by the avirulence gene avrpphb from pseudomonas syringae pv. phaseolicola was examined. incorporation of [35s]-labeled methionine into the avrpphb protein indicated processing of the full-length peptide in escherichia coli to give a major 28-kda product. the 28-kda native peptide was isolated from e. coli following over-expression of avrpphb and found not to elicit the hypersensitive response (hr) after infiltration into bean leaves. antiserum raised to the 28-kda pept ... | 1997 | 9057331 |
| localization of hydrogen peroxide accumulation during the hypersensitive reaction of lettuce cells to pseudomonas syringae pv phaseolicola. | the active oxygen species hydrogen peroxide (h2o2) was detected cytochemically by its reaction with cerium chloride to produce electron-dense deposits of cerium perhydroxides. in uninoculated lettuce leaves, h2o2 was typically present within the secondary thickened walls of xylem vessels. inoculation with wild-type cells of pseudomonas syringae pv phaseolicola caused a rapid hypersensitive reaction (hr) during which highly localized accumulation of h2o2 was found in plant cell walls adjacent to ... | 1997 | 9061952 |
| salicylic acid potentiates an agonist-dependent gain control that amplifies pathogen signals in the activation of defense mechanisms. | the phenylpropanoid-derived natural product salicylic acid (sa) plays a key role in disease resistance. however, sa administered in the absence of a pathogen is a paradoxically weak inductive signal, often requiring concentrations of 0.5 to 5 mm to induce acquired resistance or related defense mechanisms or to precondition signal systems. in contrast, endogenous sa accumulates to concentrations of < 70 microm at the site of attempted infection. here, we show that although 10 to 100 microm sa had ... | 1997 | 9061956 |
| multiple loci of pseudomonas syringae pv. syringae are involved in pathogenicity on bean: restoration of one lesion-deficient mutant requires two trna genes. | a mutational analysis of lesion-forming ability was undertaken in pseudomonas syringae pv. syringae b728a, causal agent of bacterial brown spot disease of bean. following a screen of 6,401 tn5-containing derivatives of b728a on bean pods, 26 strains that did not form disease lesions were identified. nine of the mutant strains were defective in the ability to elicit the hypersensitive reaction (hr) and were shown to contain tn5 insertions within the p. syringae pv. syringae hrp region. ten hr+ mu ... | 1997 | 9079910 |
| conservation of the multidrug resistance efflux gene oprm in pseudomonas aeruginosa. | an intragenic probe derived from the multidrug resistance gene oprm hybridized with genomic dna from all 20 serotypes of pseudomonas aeruginosa and from all 34 environmental and clinical isolates tested, indicating that the mexa-mexb-oprm multidrug efflux system is highly conserved in this organism. the oprm probe also hybridized with genomic dna from pseudomonas aureofaciens, pseudomonas chlororaphis, pseudomonas syringae, burkholderia pseudomallei, and pseudomonas putida, suggesting that efflu ... | 1997 | 9087505 |
| arabidopsis enhanced disease susceptibility mutants exhibit enhanced susceptibility to several bacterial pathogens and alterations in pr-1 gene expression. | to identify plant defense responses that limit pathogen attack, arabidopsis eds mutants that exhibit enhanced disease susceptibility to the virulent bacterial pathogen pseudomonas syringae pv maculicola es4326 were previously identified. in this study, we show that each of four eds mutants (eds5-1, eds6-1, eds7-1, and eds9-1) has a distinguishable phenotype with respect to the degree of susceptibility to a panel of bacterial phytopathogens and the ability to activate pathogenesis-related pr-1 ge ... | 1997 | 9090877 |
| hrp pilus: an hrp-dependent bacterial surface appendage produced by pseudomonas syringae pv. tomato dc3000. | hypersensitive response and pathogenicity (hrp) genes control the ability of major groups of plant pathogenic bacteria to elicit the hypersensitive response (hr) in resistant plants and to cause disease in susceptible plants. a number of hrp proteins share significant similarities with components of the type iii secretion apparatus and flagellar assembly apparatus in animal pathogenic bacteria. here we report that pseudomonas syringae pv. tomato strain dc3000 (race 0) produces a filamentous surf ... | 1997 | 9096416 |
| lipopeptide phytotoxins produced by pseudomonas syringae pv. syringae: comparison of the biosurfactant and ion channel-forming activities of syringopeptin and syringomycin. | the phytopathogenic bacterium pseudomonas syringae pv. syringae produces two classes of necrosis-inducing lipodepsipeptide toxins commonly referred to as the syringomycins and syringopeptins. members of the syringomycins class are pore-forming cytotoxins that act by promoting passive transmembrane ion flux. in this study, we test the hypothesis that syringopeptin forms sp22a and sp22b likewise function as pore-forming cytotoxins and are similar in activity to syringomycin in artificial and plant ... | 1997 | 9100379 |
| molecular cloning, characterization, and mutagenesis of a pel gene from pseudomonas syringae pv. lachyrmans encoding a member of the erwinia chrysanthemi pelade family of pectate lyases. | the pels gene from pseudomonas syringae pv. lachrymans 859 was cloned by heterologous expression in nonpectolytic p. syringae pv. syringae buvs1, using genomic dna libraries constructed with two novel broad-host-range cosmid vectors, pcpp34 and pcpp47. screening of p. syringae pv. syringae transconjugants for the ability to pit pectate media at ph 6.0 and 8.5 yielded several overlapping clones of the same dna region. ultrathin-layer isoelectric focusing gels, activity-stained with diagnostically ... | 1997 | 9100381 |
| comparison of avrd alleles from pseudomonas syringae pv. glycinea. | avirulence gene d alleles resided on indigenous plasmids in races 0, 2, 3, 4, 5, and 6 of pseudomonas syringae pv. glycinea (psg), but the allele in race 1 appeared to be chromosomal. these were all nonfunctional avirulence genes because they neither induced the avirulence phenotype on rpg4 soybean cultivars nor directed the production of syringolide elicitors when expressed in escherichia coli cells. the predicted proteins encoded by the seven psg avrd genes were very similar to that of a funct ... | 1997 | 9100386 |
| characterization of o-antigens from different strains of pseudomonas syringae pv. tabaci. | o-antigens (lipopolysaccharides, lps) were isolated by nacl extraction from microbial biomass of pseudomonas syringae pv. tabaci and purified by ultracentrifugation. individual structural components of the lps macromolecule (o-specific polysaccharide (o-ps), core oligosaccharide, and lipid a) were obtained and characterized. fatty acids 3-oh-c10:0, c12:0, 2-oh-c12:0, 3-oh-c12:0, c16:1, c16:0, c18:1, and c18:0 were identified in the lipid a composition. glucosamine, ethanolamine, and phosphoethan ... | 1997 | 9113726 |
| in vitro antifungal and fungicidal activities and erythrocyte toxicities of cyclic lipodepsinonapeptides produced by pseudomonas syringae pv. syringae. | recent increases in fungal infections, the few available antifungal drugs, and increasing fungal resistance to the available antifungal drugs have resulted in a broadening of the search for new antifungal agents. strains of pseudomonas syringae pv. syringae produce cyclic lipodepsinonapeptides with antifungal activity. the in vitro antifungal and fungicidal activities of three cyclic lipodepsinonapeptides (syringomycin e, syringotoxin b, and syringostatin a) against medically important isolates ... | 1996 | 9124827 |
| phytoalexin-deficient mutants of arabidopsis reveal that pad4 encodes a regulatory factor and that four pad genes contribute to downy mildew resistance. | we are working to determine the role of the arabidopsis phytoalexin, camalexin, in protecting the plant from pathogen attack by isolating phytoalexin-deficient (pad) mutants in the accession columbia (col-0) and examining their response to pathogens. mutations in pad1, pad2, and pad4 caused enhanced susceptibility to the bacterial pathogen pseudomonas syringae pv. maculicola strain es4326 (psmes4326), while mutations in pad3 or pad5 did not. camalexin was not detected in any of the double mutant ... | 1997 | 9136026 |
| characterization of is1474, an insertion sequence of the is21 family isolated from pseudomonas alcaligenes ncib 9867. | a new insertion sequence (is) designated is1474 was isolated from pseudomonas alcaligenes ncib 9867 (p25x). is1474 is a 2632 bp element which showed a characteristic is structure with 12 bp inverted repeats (irs) flanking a 2608 bp central region. is1474 contained four open reading frames (orf1-orf4), two in each orientation. similarities were detected between orf1 and orf2 and the putative transposases of the is21 family. sequences upstream from is1474 were found to display up to 89% homology w ... | 1997 | 9141667 |
| pilp, a pilus biogenesis lipoprotein in neisseria gonorrhoeae, affects expression of pilq as a high-molecular-mass multimer. | studies of gonococcal pilus biogenesis are fundamental to understanding organelle structure/function relationships and identifying new approaches to controlling disease. this area of research is also relevant to elucidating the basic mechanisms of outer membrane translocation of macromolecules, which requires components highly related to those involved in type iv pilus expression. previous studies have shown that products of several ancillary pil genes are required for organelle biogenesis but o ... | 1997 | 9157238 |
| detecting and characterizing n-acyl-homoserine lactone signal molecules by thin-layer chromatography. | many gram-negative bacteria regulate gene expression in response to their population size by sensing the level of acyl-homoserine lactone signal molecules which they produce and liberate to the environment. we have developed an assay for these signals that couples separation by thin-layer chromatography with detection using agrobacterium tumefaciens harboring lacz fused to a gene that is regulated by autoinduction. with the exception of n-butanoyl-l-homoserine lactone, the reporter detected acyl ... | 1997 | 9177164 |
| altered localization of hrpz in pseudomonas syringae pv. syringae hrp mutants suggests that different components of the type iii secretion pathway control protein translocation across the inner and outer membranes of gram-negative bacteria. | pseudomonas syringae pv. syringae 61 (pss61) secretes the hrpz harpin by a type iii protein secretion pathway encoded by a cluster of hrp (hypersensitive response and pathogenicity) and hrc genes. the nine hrc genes represent a subset of hrp genes that are also conserved in the type iii virulence protein secretion systems of animal pathogenic yersinia, shigella, and salmonella spp. the hrpj and hrpu operons contain seven hrc genes (counting hrcq(a) and hrcq(b) as one gene), all with additional h ... | 1997 | 9190801 |
| characterization of the cryptic plasmids of the pseudomonas alcaligenes type strain. | the species type strain of pseudomonas alcaligenes contains three small cryptic plasmids (designated pecb1, 2, and 3) of 7740, 4480, and 2700 bp, respectively. partial restriction enzyme maps have been constructed for pecb1 and 2 which on this basis do not appear to be related. pecb3 proved refractile to cutting with commonly used restriction enzymes, though it was completely rendered by those enzymes which recognize 4-bp sequences containing only g + c. this suggested that pecb3 is especially r ... | 1997 | 9200222 |
| a hairpin-loop conformation in tandem repeat sequence of the ice nucleation protein revealed by nmr spectroscopy. | the 1h-nmr spectrum of a synthetic 24-residue peptide (a1-g-v-d-s-s-l-i-a-g-y-g-s-t-q-t-s-g-s-d-s-a-l-t24; inp24), comprising three repeats of the 8-residue consensus sequence of pseudomonas syringae ice nucleation protein, was fully assigned using 2-dimensional (2d) nmr spectroscopy at 4 degrees c and 30 degrees c. close proximity of the aliphatic protons between leu7, ile8, ala9, and the ring-protons of tyr11 was indicated from the observation of the inter-molecular nuclear overhauser enhancem ... | 1997 | 9202151 |
| evidence that the pseudomonas syringae pv. syringae hrp-linked hrma gene encodes an avr-like protein that acts in an hrp-dependent manner within tobacco cells. | a 25-kb dna region, previously cloned from pseudomonas syringae pv. syringae 61 in cosmid phir11, enables nonpathogenic bacteria such as pseudomonas fluorescens and escherichia coli to elicit the hypersensitive response (hr) in tobacco (nicotiana tabacum). hrma is located within this region, adjacent to a conserved cluster of hrp genes, and is essential for nonpathogens to elicit the hr. dna sequence analysis suggested that hrma was the second of two genes in an operon and was preceded by an ope ... | 1997 | 9204563 |
| the presence of hrp genes on the pathogenicity-associated plasmid of the tumorigenic bacterium erwinia herbicola pv. gypsophilae. | the pathogenicity-associated plasmid (ppath) of erwinia herbicola pv. gypsophilae (ehg), which is present only in pathogenic strains, contains a gene cluster encoding indole-3-acetic acid and cytokinin biosynthesis. the transposon-reporter tn3-spice was used to generate nonpathogenic mutants on two overlapping cosmids, pla150 and pla352, of the ppath. a cluster of such mutations, which spanned 16 kb, mapped approximately 15 kb from the gene cluster involved in phytohormone biosynthesis. non-path ... | 1997 | 9204571 |
| hctr1: a human gene for copper uptake identified by complementation in yeast. | the molecular mechanisms responsible for the cellular uptake of copper in mammalian cells are unknown. we describe isolation of a human gene involved in this process by complementation of the yeast high-affinity copper uptake mutant, ctr1. besides complementing ctr1 growth defect on nonfermentable media, the human gene also rescues iron transport and sod1 defects in ctr1 yeast. overexpression of the gene in yeast leads to vulnerability to the toxicity of copper overload. in addition, its express ... | 1997 | 9207117 |
| analysis of the syrp gene, which regulates syringomycin synthesis by pseudomonas syringae pv. syringae. | syringomycin is a lipodepsinonapeptide phytotoxin synthesized by pseudomonas syringae pv. syringae on multienzymatic peptide synthetases. sequence analysis of the interval between the syrb and syrd genes of p. syringae pv. syringae strain b301d revealed a 1,059-bp open reading frame (orf), designated syrp. the predicted product of this orf was a 39.6-kda protein consisting of 353 amino acid residues. searches of protein sequence databases demonstrated that syrp was most similar to histidine kina ... | 1997 | 9212424 |
| the pto kinase conferring resistance to tomato bacterial speck disease interacts with proteins that bind a cis-element of pathogenesis-related genes. | in tomato, the pto kinase confers resistance to bacterial speck disease by recognizing the expression of a corresponding avirulence gene, avrpto, in the pathogen pseudomonas syringae pv. tomato. using the yeast two-hybrid system, we have identified three genes, pti4, pti5 and pti6, that encode proteins that physically interact with the pto kinase. pti4/5/6 each encode a protein with characteristics that are typical of transcription factors and are similar to the tobacco ethylene-responsive eleme ... | 1997 | 9214637 |
| characterization of the alginate biosynthetic gene cluster in pseudomonas syringae pv. syringae. | alginate, a copolymer of d-mannuronic acid and l-guluronic acid, is produced by a variety of pseudomonads, including pseudomonas syringae. alginate biosynthesis has been most extensively studied in p. aeruginosa, and a number of structural and regulatory genes from this species have been cloned and characterized. in the present study, an alginate-defective (alg-) mutant of p. syringae pv. syringae ff5 was shown to contain a tn5 insertion in algl, a gene encoding alginate lyase. a cosmid clone de ... | 1997 | 9226254 |
| use of tn5-gusa5 to investigate environmental and nutritional effects on gene expression in the coronatine biosynthetic gene cluster of pseudomonas syringae pv. glycinea. | pseudomonas syringae pv. glycinea pg4180 produces coronatine (cor), a chlorosis-inducing phytotoxin that consists of the polyketide coronafacic acid (cfa) coupled via an amide bond to the ethylcyclopropyl amino acid coronamic acid (cma). both cfa and cma function as intermediates in the pathway to coronatine, and genes encoding their synthesis have been localized: however, the precise factors that regulate the production of cor and its precursors remain unclear. in the present study, a lambda de ... | 1997 | 9226871 |
| antagonistic activities of epiphytic bacteria from soybean leaves against pseudomonas syringae pv. glycinea in vitro and in planta | | 1997 | 9230099 |
| biological activities of pseudomycin a, a lipodepsinonapeptide from pseudomonas syringae msu 16h. | similarly to other pseudomonas lipodepsinonapeptides, pseudomycin a inhibits proton extrusion from maize roots, promotes closure of stomata in vicia faba, necrosis of tobacco leaves, haemolysis of human erythrocytes, affects h(+)-atpase activity and proton translocation in plasma membrane vesicles, and stimulates succinate respiration in pea mitochondria. in general, the biological activities of pseudomycin a are lower than those of syringomycin-e, the prototype member of this family of bacteria ... | 1997 | 9237401 |
| differential induction of systemic resistance in arabidopsis by biocontrol bacteria. | selected nonpathogenic, root-colonizing bacteria are able to elicit induced systemic resistance (isr) in plants. to elucidate the molecular mechanisms underlying this type of systemic resistance, an arabidopsis-based model system was developed in which pseudomonas syringae pv. tomato and fusarium oxysporum f. sp. raphani were used as challenging pathogens. in arabidopsis thaliana ecotypes columbia and landsberg erecta, colonization of the rhizosphere by p. fluorescens strain wcs417r induced syst ... | 1997 | 9245833 |
| structure of l-a virus: a specialized compartment for the transcription and replication of double-stranded rna. | the genomes of double-stranded (ds)rna viruses are never exposed to the cytoplasm but are confined to and replicated from a specialized protein-bound compartment-the viral capsid. we have used cryoelectron microscopy and three-dimensional image reconstruction to study this compartment in the case of l-a, a yeast virus whose capsid consists of 60 asymmetric dimers of gag protein (76 kd). at 16-a resolution, we distinguish multiple domains in the elongated gag subunits, whose nonequivalent packing ... | 1997 | 9281577 |
| a possible role for acetylated intermediates in diaminopimelate and tabtoxinine-beta-lactam biosynthesis in pseudomonas syringae pv. tabaci br2.024. | the deduced product of an open reading frame (orf3) located in the tabtoxinine-beta-lactam (t beta l) biosynthetic region of pseudomonas syringae pv. tabaci br2.024 (br2.024) has significant sequence homology to the dapd products of other bacteria. dapd encodes l-2,3,4,5-tetrahydrodipicolinate succinyl coenzyme a succinyltransferase (thdpa-st), an enzyme in the diaminopimelate (dap) and lysine biosynthetic pathway. complementation studies, in vitro transcription-translation experiments, and enzy ... | 1997 | 9294453 |
| identification of a promoter region on the halomonas elongata cryptic plasmid phe1 employing the inaz reporter gene of pseudomonas syringae. | a native promoter located on the cryptic plasmid phe1 from the moderate halophile halomonas elongata was identified employing a promoterless ice nucleation gene inaz of pseudomonas syringae by direct subcloning and assaying for ice nucleation activity. the presence of the promoter was verified by inserting the corresponding intact or deleted phe1 fragment in the promoter analysis vector pkk232-8 upstream of the promoterless cat or inaz gene. only constructs carrying the intact phe1 fragment gave ... | 1997 | 9297819 |
| expression and analysis of coronafacate ligase, a thermoregulated gene required for production of the phytotoxin coronatine in pseudomonas syringae. | coronafacic acid, the polyketide component of the phytotoxin coronatine, is activated and coupled to coronamic acid via amide bond formation, a biosynthetic step presumably catalyzed by the coronafacate ligase (cfl) gene product. in the present study, cfl was fused to the carboxy terminus of male, which encodes the maltose-binding protein (mbp), and overexpressed in escherichia coli. immunoblot analysis indicated that cfl contained an atp-binding region, a motif conserved in enzymes which activa ... | 1997 | 9297822 |
| molecular organisation of the ice nucleation protein inav from pseudomonas syringae. | a new ice nucleation gene from pseudomonas syringae was isolated and overexpressed as a fully active protein in escherichia coli in order to gain experimental data about the structure of ice nucleation proteins. no evidence of a signal sequence or secondary glycosylation was found. differences in the extent of aggregation were shown to modulate the ice nucleation activity. the circular dichroism spectrum of the purified protein indicated the presence of beta-sheet structure. this finding support ... | 1997 | 9323042 |
| avirulence gene d of pseudomonas syringae pv. tomato may have undergone horizontal gene transfer. | avirulence gene d (avrd) is carried on the b-plasmid of the plant pathogen pseudomonas syringae pv. tomato with plasmid-borne avrd homologs widely distributed among the pseudomonads. we now report sequences in the soft rot pathogen erwinia carotovora that cross-hybridize to avrd suggesting a conserved function beyond avirulence. alternatively, avrd may have been transferred horizontally among species: (i) dna linked to avrd shows evidence of class ii transpositions and contains a novel is3-relat ... | 1997 | 9326365 |
| the cpr5 mutant of arabidopsis expresses both npr1-dependent and npr1-independent resistance. | the cpr5 mutant was identified from a screen for constitutive expression of systemic acquired resistance (sar). this single recessive mutation also leads to spontaneous expression of chlorotic lesions and reduced trichome development. the cpr5 plants were found to be constitutively resistant to two virulent pathogens, pseudomonas syringae pv maculicola es4326 and peronospora parasitica noco2; to have endogenous expression of the pathogenesis-related gene 1 (pr-1); and to have an elevated level o ... | 1997 | 9338960 |
| enhanced tolerance to bacterial pathogens caused by the transgenic expression of barley lipid transfer protein ltp2. | purified lipid transfer protein ltp2 from barley applied on tobacco leaves eliminated symptoms caused by infiltration of pseudomonas syringae pv. tabaci 153. growth of the pathogen in leaves of transgenic tobacco plants was retarded when compared with non-transformed controls. the percentage of inoculation points that showed necrotic lesions was greatly reduced in transgenic tobacco (17-38% versus 78%) and the average size of these lesions was 61-81% that of control. the average total lesion are ... | 1997 | 9351251 |
| sequencing of regions downstream of adda (98 degrees) and citg (289 degrees) in bacillus subtilis. | the nucleotide sequence of 17.3 kbp downstream of adda (98 degrees) on the bacillus subtilis chromosome was determined. twenty putative orfs were identified. three of them coincided with known b. subtilis genes, adda, sbcd and wpra. the product of four other orfs showed similarity to sbcc of clostridium perfringens, coth of b. subtilis, 2-hydroxyhepta-2,4-diene-1,7-diodate isomerase of methanococcus jannaschi and a putative orf of pseudomonas syringae. in addition, a sequence of 7.6 kbp downstre ... | 1997 | 9353931 |
| the phte locus in the phaseolotoxin gene cluster has orfs with homologies to genes encoding amino acid transferases, the arac family of transcriptional factors, and fatty acid desaturases. | a cluster of genes involved in the production of phaseolotoxin, a phytotoxin produced by pseudomonas syringae pv. phaseolicola, contains eight (phta through phth) complementation groups (y. x. zhang, k. b. rowley, and s. s. patil, j. bacteriol., 175:6451-6458, 1993). in this study, sequencing of the region encompassing the phte locus revealed six putative open reading frames (orfs), each preceded by a putative ribosomal binding site, and all oriented in the same direction. reverse transcription- ... | 1997 | 9353942 |
| yersinia enterocolitica induces apoptosis in macrophages by a process requiring functional type iii secretion and translocation mechanisms and involving yopp, presumably acting as an effector protein. | yersiniae, causative agents of plague and gastrointestinal diseases, secrete and translocate yop effector proteins into the cytosol of macrophages, leading to disruption of host defense mechanisms. it is shown in this report that yersinia enterocolitica induces apoptosis in macrophages and that this effect depends on yopp. functional secretion and translocation mechanisms are required for yopp to act, strongly suggesting that this protein exerts its effect intracellularly, after translocation in ... | 1997 | 9356502 |
| use of model plant hosts to identify pseudomonas aeruginosa virulence factors. | we used plants as an in vivo pathogenesis model for the identification of virulence factors of the human opportunistic pathogen pseudomonas aeruginosa. nine of nine tnphoa mutant derivatives of p. aeruginosa strain ucbpp-pa14 that were identified in a plant leaf assay for less pathogenic mutants also exhibited significantly reduced pathogenicity in a burned mouse pathogenicity model, suggesting that p. aeruginosa utilizes common strategies to infect both hosts. seven of these nine mutants contai ... | 1997 | 9371831 |
| purified hrpa of pseudomonas syringae pv. tomato dc3000 reassembles into pili. | pseudomonas syringae pv. tomato dc3000 produces hrp pili under inducing in vitro conditions. a preparation of partially purified extracellular filaments contains hrpa, flagellin and some minor contaminants. hrpa was separated from the major contaminant, the flagellin, by gel filtration to a fraction containing hrpa as well as its three n-terminally truncated forms. these were further separated by two steps of reversed phase chromatography. hrpa and its degradation products were each shown to rea ... | 1997 | 9395289 |
| genetic engineering of parthenocarpic plants. | transgenic tobacco and eggplants expressing the coding region of the iaam gene from pseudomonas syringae pv. savastanoi, under the control of the regulatory sequences of the ovule-specific defh9 gene from antirrhinum majus, showed parthenocarpic fruit development. expression of the defh9-iaam chimeric transgene occurs during flower development in both tobacco and eggplant. seedless fruits were produced by emasculated flowers. when pollinated, the parthenocarpic plants produced fruits containing ... | 1997 | 9415894 |
| dspa, an essential pathogenicity factor of erwinia amylovora showing homology with avre of pseudomonas syringae, is secreted via the hrp secretion pathway in a dspb-dependent way. | in erwinia amylovora, the dsp region, required for pathogenicity on the host plant but not for hypersensitive elicitation on tobacco, is separated from the hrp region by 4 kb. the genetic analysis reported in this paper showed that this 4kb region is not required for pathogenicity on pear seedlings. the environmental conditions allowing expression of a dsp::lacz fusion were examined: expression was barely detected in rich medium at 30 degrees c, and the highest expression was observed in m9 gala ... | 1997 | 9426142 |
| biodegradation of phosphonomycin by rhizobium huakuii pmy1. | the biodegradation by rhizobium huakuii pmy1 of up to 10 mm phosphonomycin as a carbon, energy, and phosphorus source with accompanying p(i) release is described. this biodegradation represents a further mechanism of resistance to this antibiotic and a novel, phosphate-deregulated route for organophosphonate metabolism by rhizobium spp. | 1998 | 9435089 |
| homology and functional similarity of an hrp-linked pathogenicity locus, dspef, of erwinia amylovora and the avirulence locus avre of pseudomonas syringae pathovar tomato. | the "disease-specific" (dsp) region next to the hrp gene cluster of erwinia amylovora is required for pathogenicity but not for elicitation of the hypersensitive reaction. a 6.6-kb apparent operon, dspef, was found responsible for this phenotype. the operon contains genes dspe and dspf and is positively regulated by hrpl. a blast search revealed similarity in the dspe gene to a partial sequence of the avre locus of pseudomonas syringae pathovar tomato. the entire avre locus was sequenced. homolo ... | 1998 | 9448330 |
| accumulation of salicylic acid and 4-hydroxybenzoic acid in phloem fluids of cucumber during systemic acquired resistance is preceded by a transient increase in phenylalanine ammonia-lyase activity in petioles and stems. | cucumber (cucumis sativa) leaves infiltrated with pseudomonas syringae pv. syringae cells produced a mobile signal for systemic acquired resistance between 3 and 6 h after inoculation. the production of a mobile signal by inoculated leaves was followed by a transient increase in phenylalanine ammonia-lyase (pal) activity in the petioles of inoculated leaves and in stems above inoculated leaves; with peaks in activity at 9 and 12 h, respectively, after inoculation. in contrast, pal activity in in ... | 1998 | 9449843 |
| auxin production is a common feature of most pathovars of pseudomonas syringae. | we investigated indole-3-acetic acid (iaa) production by 57 pathovars of pseudomonas syringae and related species. most of those analyzed produced iaa, especially in the presence of tryptophan. eight strains produced high iaa concentrations in the absence of trp. the iaam and iaah genes of p. savastanoi pv. savastanoi were detected in a limited number of strains only, including the eight above-mentioned strains. thus, iaa synthesis in most assayed strains of p. syringae and related species does ... | 1998 | 9450337 |
| environmental regulation of salmonella typhi invasion-defective mutants. | salmonella typhi is the etiologic agent of human typhoid. during infection, s. typhi adheres to and invades epithelial and m cells that line the distal ileum. to survive in the human host, s. typhi must overcome numerous complex extracellular and intracellular environments. since relatively little is known about s. typhi pathogenesis, studies were initiated to identify s. typhi genes involved in the early steps of interaction with the host and to evaluate the environmental regulation of these ge ... | 1998 | 9453627 |
| curli fibers are highly conserved between salmonella typhimurium and escherichia coli with respect to operon structure and regulation. | mouse-virulent salmonella typhimurium strains sr-11 and atcc 14028-1s express curli fibers, thin aggregative fibers, at ambient temperature on plates as judged by western blot analysis and electron microscopy. concomitantly with curli expression, cells develop a rough and dry colony morphology and bind the dye congo red (called the rdar morphotype). cloning and characterization of the two divergently transcribed operons required for curli biogenesis, csgba(c) and csgdefg, from s. typhimurium sr- ... | 1998 | 9457880 |
| a cold-adapted lipase of an alaskan psychrotroph, pseudomonas sp. strain b11-1: gene cloning and enzyme purification and characterization. | a psychrotrophic bacterium producing a cold-adapted lipase upon growth at low temperatures was isolated from alaskan soil and identified as a pseudomonas strain. the lipase gene (lipp) was cloned from the strain and sequenced. the amino acid sequence deduced from the nucleotide sequence of the gene (924 bp) corresponded to a protein of 308 amino acid residues with a molecular weight of 33,714. lipp also has consensus motifs conserved in other cold-adapted lipases, i.e., lipase 2 from antarctic m ... | 1998 | 9464382 |
| identification of bacterial isolates obtained from intestinal contents associated with 12,000-year-old mastodon remains. | mastodon (mammut americanum) remains unearthed during excavation of ancient sediments usually consist only of skeletal material, due to postmortem decomposition of soft tissues by microorganisms. two recent excavations of skeletal remains in anoxic sediments in ohio and michigan, however, have uncovered organic masses which appear to be remnants of the small and large intestines, respectively. macrobotanical examinations of the composition of these masses revealed assemblages of plant material r ... | 1998 | 9464403 |
| ethylene-insensitive tobacco lacks nonhost resistance against soil-borne fungi. | enhanced ethylene production is an early response of plants to pathogen attack and has been associated with both resistance and susceptibility to disease. tobacco plants were transformed with the mutant etr1-1 gene from arabidopsis, conferring dominant ethylene insensitivity. besides lacking known ethylene responses, these transformants (tetr) did not slow growth when contacting neighboring plants, hardly expressed defense-related basic pathogenesis-related proteins, and developed spontaneous st ... | 1998 | 9465120 |
| a major outer membrane protein of rahnella aquatilis functions as a porin and root adhesin. | a 38-kda major outer membrane protein (omp) was isolated from the nitrogen-fixing enterobacterium rahnella aquatilis cf3. this protein exists as a stable trimer in the presence of 2% sodium dodecyl sulfate at temperatures below 60 degrees c. single channel experiments showed that this major omp of r. aquatilis cf3 is able to form pores in the planar lipid membrane. two oligonucleotides encoding the n-terminal portion of the 38-kda omp and c-terminal portion of ompc were used to amplify the 38-kd ... | 1998 | 9473046 |
| phosphorylation-independent activity of the response regulators algb and algr in promoting alginate biosynthesis in mucoid pseudomonas aeruginosa. | overproduction of the capsular polysaccharide alginate appears to confer a selective advantage for pseudomonas aeruginosa in the lungs of cystic fibrosis patients. the regulators algb and algr, which are both required as positive activators in alginate overproduction, have homology with the regulator class of two-component environmental responsive proteins which coordinate gene expression through signal transduction mechanisms. signal transduction in this class of proteins generally occurs via a ... | 1998 | 9473053 |
| [the properties of the proteins and nucleic acids of 3 pseudomonas syringae phages]. | the 9b, 123, 788/8 pseudomonas syringae phages were investigated. paag electrophoretic profiles of phage proteins were identical for all three phages except the minor polypeptide having molecular weight 35,000 da. the band corresponding to this protein was present only in 9b and 788/8 phage protein profiles. amino acid composition of phage proteins varied insignificantly showing prevalence of asp, glu, ala, leu. phage dna fragments electrophoresis, carried out after processing with specific endo ... | 1997 | 9480014 |
| salmonella typhimurium encodes an sdia homolog, a putative quorum sensor of the luxr family, that regulates genes on the virulence plasmid. | quorum sensing is a phenomenon in which bacteria sense and respond to their own population density by releasing and sensing pheromones. in gram-negative bacteria, quorum sensing is often performed by the luxr family of transcriptional regulators, which affect phenotypes as diverse as conjugation, bioluminescence, and virulence gene expression. the gene encoding one luxr family member, named sdia (suppressor of cell division inhibition), is present in the escherichia coli genome. in this report, ... | 1998 | 9495757 |
| ethylene regulates the susceptible response to pathogen infection in tomato. | ethylene evolution occurs concomitantly with the progression of disease symptoms in response to many virulent pathogen infections in plants. a tomato mutant impaired in ethylene perception-never ripe-exhibited a significant reduction in disease symptoms in comparison to the wild type after inoculations of both genotypes with virulent bacterial (xanthomonas campestris pv vesicatoria and pseudomonas syringae pv tomato) and fungal (fusarium oxysporum f sp lycopersici) pathogens. bacterial spot dise ... | 1998 | 9501111 |
| exopolysaccharide ii production is regulated by salt in the halotolerant strain rhizobium meliloti efb1. | the halotolerant strain rhizobium meliloti efb1 modifies the production of extracellular polysaccharides in response to salt. efb1 colonies grown in the presence of 0.3 m nacl show a decrease in mucoidy, and in salt-supplemented liquid medium this organism produces 40% less exopolysaccharides. we isolated transposon-induced mutant that, when grown in the absence of salt, had a colony morphology (nonmucoid) similar to the colony morphology of the wild type grown in the presence of salt. calcofluo ... | 1998 | 9501442 |
| growth phase and temperature influence promoter activity, transcript abundance, and protein stability during biosynthesis of the pseudomonas syringae phytotoxin coronatine. | the plant-pathogenic bacterium pseudomonas syringae pv. glycinea pg4180.n9 synthesizes high levels of the polyketide phytotoxin coronatine (cor) at 18 degrees c, whereas no detectable toxin is produced at 28 degrees c. previously, we reported that the temperature-sensitive activation of three promoters within the cor biosynthetic gene cluster might explain thermoregulation of cor biosynthesis. the present study was aimed at furthering our understanding of the transcriptional as well as the postt ... | 1998 | 9515901 |
| reactive oxygen intermediates mediate a systemic signal network in the establishment of plant immunity. | recognition of an avirulent pathogen stimulates an oxidative burst generating o2- and h2o2, and these reactive oxygen intermediates (rois) cue the induction of defense genes and cell death in the development of a restricted lesion. this localized hypersensitive response (hr) is accompanied by the development of systemic acquired resistance to virulent pathogens. here we show that inoculation of arabidopsis leaves with avirulent pseudomonas syringae induces secondary oxidative bursts in discrete ... | 1998 | 9529253 |
| comparative biochemistry of the oxidative burst produced by rose and french bean cells reveals two distinct mechanisms | cultured cells of rose (rosa damascena) treated with an elicitor derived from phytophthora spp. and suspension-cultured cells of french bean (phaseolus vulgaris) treated with an elicitor derived from the cell walls of colletotrichum lindemuthianum both produced h2o2. it has been hypothesized that in rose cells h2o2 is produced by a plasma membrane nad(p)h oxidase (superoxide synthase), whereas in bean cells h2o2 is derived directly from cell wall peroxidases following extracellular alkalinizatio ... | 1998 | 9536055 |
| identification of a novel salmonella invasion locus homologous to shigella ipgde. | genes essential for salmonella typhimurium invasion have been localized to salmonella pathogenicity island 1 (spi1) on the chromosome. however, it is clear that other genes are required for the invasion process. mutations that abolish the spi1 invasion type iii secretion system do not significantly reduce invasion into chinese hamster ovary tissue culture cells. two invasion defective mutants were isolated by screening 2,500 tn10dtc insertion mutants of s. typhimurium in the tissue culture invas ... | 1998 | 9537377 |
| occurrence of thermoregulation of genes involved in coronatine biosynthesis among various pseudomonas syringae strains. | several pathovars of pseudomonas syringae produce the polyketide phytotoxin coronatine (cor). in the bacterial blight pathogen of soybean, p. syringae pv. glycinea pg4180, cor is produced at high levels at 18 degrees c whereas no toxin is synthesized at 28 degrees c. previously, activation of three promoters inside the cor biosynthetic gene cluster by a modified two-component regulatory system was shown to influence thermoregulation of cor biosynthesis. using phenotypic determination of cor synt ... | 1998 | 9542107 |
| characterization of the dominant and rare members of a young hawaiian soil bacterial community with small-subunit ribosomal dna amplified from dna fractionated on the basis of its guanine and cytosine composition. | the small-subunit ribosomal dna (rdna) diversity was found to be very high in a hawaiian soil community that might be expected to have lower diversity than the communities in continental soils because the hawaiian soil is geographically isolated and only 200 years old, is subjected to a constant climate, and harbors low plant diversity. since an underlying community structure could not be revealed by analyzing the total eubacterial rdna, we first fractionated the dna on the basis of guanine-plus ... | 1998 | 9546163 |
| uncoupling pr gene expression from npr1 and bacterial resistance: characterization of the dominant arabidopsis cpr6-1 mutant. | in arabidopsis, npr1 mediates the salicylic acid (sa)-induced expression of pathogenesis-related (pr) genes and systemic acquired resistance (sar). here, we report the identification of another component, cpr 6, that may function with npr1 in regulating pr gene expression. the dominant cpr 6-1 mutant expresses the sa/npr1-regulated pr genes (pr-1, bgl 2, and pr-5) and displays enhanced resistance to pseudomonas syringae pv maculicola es4326 and peronospora parasitica noco2 in the absence of sar ... | 1998 | 9548982 |
| expression of carboxymethylcellulase on the surface of escherichia coli using pseudomonas syringae ice nucleation protein. | ice-nucleation protein (inp), an outer membrane protein from pseudomonas syringae, is able to catalyze the ice crystal formation of supercooled water. it was exploited for anchoring of bacillus subtilis carboxymethylcellulase (cmcase) on the surface of escherichia coli. a surface anchoring vector, pginp21m, was created that contains the multicloning sites including bamhi, smai and ecori at the end of the 3' flanking region encoding the c-terminus of inp instead of the stop codon for subcloning t ... | 1998 | 9549104 |
| erwinia amylovora secretes dspe, a pathogenicity factor and functional avre homolog, through the hrp (type iii secretion) pathway. | erwinia amylovora was shown to secrete dspe, a pathogenicity factor of 198 kda and a functional homolog of avre of pseudomonas syringae pv. tomato. dspe was identified among the supernatant proteins isolated from cultures grown in an hrp gene-inducing minimal medium by immunodetection with a dspe-specific antiserum. secretion required an intact hrp pathway. | 1998 | 9555912 |
| histidine utilisation operon (hut) is upregulated at low temperature in the antarctic psychrotrophic bacterium pseudomonas syringae. | the antarctic psychrotrophic bacterium pseudomonas syringae was mutagenised using a transposon tn5-ot182 which facilitates identification of promoter fusions expressing the reporter gene (lacz) for beta-galactosidase. most mutants expressed beta-galactosidase both at optimal growth temperature (20-22 degrees c) and at low temperature (4 degrees c). but a small percentage of the mutants (approximately 5%) were unique in that they expressed beta-galactosidase activity predominantly at low temperat ... | 1998 | 9561727 |
| a tellurite-resistance genetic determinant from phytopathogenic pseudomonads encodes a thiopurine methyltransferase: evidence of a widely-conserved family of methyltransferases. | a tellurite-resistance genetic determinant was isolated from the pea blight pathogen pseudomonas syringae pathovar pisi by a shotgun strategy involving a tellurite-selective screening in escherichia coli. a 1.65 kb tellurite resistance insert was obtained and analysed. it harbours a single complete and functional orf encoding a deduced protein of 24, 445 da. the deduced aa sequence shows significant similarities with the complete human thiopurine methyltransferase enzyme, a methyltransferase fro ... | 1998 | 9565678 |