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toxic effects of linear alkylbenzene sulfonate on metabolic activity, growth rate, and microcolony formation of nitrosomonas and nitrosospira strains.strong inhibitory effects of the anionic surfactant linear alkylbenzene sulfonate (las) on four strains of autotrophic ammonia-oxidizing bacteria (aob) are reported. two nitrosospira strains were considerably more sensitive to las than two nitrosomonas strains were. interestingly, the two nitrosospira strains showed a weak capacity to remove las from the medium. this could not be attributed to adsorption or any other known physical or chemical process, suggesting that biodegradation of las took ...200111375155
involvement of nitrate reductase and pyoverdine in competitiveness of pseudomonas fluorescens strain c7r12 in soil.involvement of nitrate reductase and pyoverdine in the competitiveness of the biocontrol strain pseudomonas fluorescens c7r12 was determined, under gnotobiotic conditions, in two soil compartments (bulk and rhizosphere soil), with the soil being kept at two different values of matric potential (-1 and -10 kpa). three mutants affected in the synthesis of either the nitrate reductase (nar(-)), the pyoverdine (pvd(-)), or both (nar(-) pvd(-)) were used. the nar(-) and nar(-) pvd(-) mutants were obt ...200111375173
comparison of endotoxin exposure assessment by bioaerosol impinger and filter-sampling methods.environmental assessment data collected in two prior occupational hygiene studies of swine barns and sawmills allowed the comparison of concurrent, triplicate, side-by-side endotoxin measurements using air sampling filters and bioaerosol impingers. endotoxin concentrations in impinger solutions and filter eluates were assayed using the limulus amebocyte lysate assay. in sawmills, impinger sampling yielded significantly higher endotoxin concentration measurements and lower variances than filter s ...200111375194
survival of escherichia coli o157:h7 atcc 43895 in a model apple juice medium with different concentrations of proline and caffeic acid.the effects of proline and caffeic acid on the survival of shiga toxin-producing escherichia coli (stec) o157:h7 strain atcc 43895 in a model apple juice medium were studied. it is hypothesized that the inhibitory effect of caffeic acid may explain why almost all outbreaks of stec o157:h7 infections linked to apple juice or cider have occurred in october or november.200111375209
[processes of plant colonization by methylobacterium strains and some bacterial properties ].the pink-pigmented facultative methylotrophic bacteria (ppfmb) of the genus methylobacterium are indespensible inhabitants of the plant phyllosphere. using maize zea mays as a model, the ways of plant colonization by ppfmb and some properties of the latter that might be beneficial to plants were studied. a marked strain, methylobacterium mesophilicum apr-8 (pulb113), was generated to facilitate the detection of the methylotrophic bacteria inoculated into the soil or applied to the maize leaves. ...200111386061
identification and expression of the pseudomonas syringae pv. aptata hrpz(psa) gene which encodes an harpin elicitor.a sequence homologous to an internal fragment 0.75 kb bstxi of the pseudomonas syringae pv. syringae hrpz gene was identified in pseudomonas syringae pv. aptata ncppb 2664, the causal agent of bacterial blight in sugar beet, lettuce and other plants. and in e. coli dh10b (pccp1069) containing the p. syringae pv. aptata hrp gene cluster. pcr with oligonucleotides, based on the hrpz(pss) gene and used as primers with the total genomic dna of p. syringae pv. aptata, amplified a 1 kb fragment that h ...200111392485
the agrobacterium tumefaciens rnd homolog is required for trar-mediated quorum-dependent activation of ti plasmid tra gene expression.conjugal transfer of agrobacterium tumefaciens ti plasmids is regulated by quorum sensing via trar and its cognate autoinducer, n-(3-oxo-octanoyl)-l-homoserine lactone. we isolated four tn5-induced mutants of a. tumefaciens c58 deficient in trar-mediated activation of tra genes on ptic58deltaaccr. these mutations also affected the growth of the bacterium but had no detectable influence on the expression of two tester gene systems that are not regulated by quorum sensing. in all four mutants tn5 ...200111395455
visualization of secreted hrp and avr proteins along the hrp pilus during type iii secretion in erwinia amylovora and pseudomonas syringae.pili are required for protein and/or dna transfer from bacteria to recipient plant or bacterial cells, based on genetic evidence. however, it has never been shown directly that the effector proteins or dna are localized along or inside the pili in situ. failure to visualize an association of effector proteins/dna with pili is the central issue in the debate regarding the exact function of pili in protein and dna transfer. in this study, a newly developed in situ immunogold labelling procedure en ...200111401717
complete dna sequence of yersinia enterocolitica serotype 0:8 low-calcium-response plasmid reveals a new virulence plasmid-associated replicon.the complete nucleotide sequence and organization of the yersinia enterocolitica serotype 0:8 low-calcium-response (lcr) plasmid, pyve8081, were determined. the 67,720-bp plasmid encoded all the genes known to be part of the lcr stimulon except for ylpa. eight of 13 intact open reading frames of unknown function identified in pyve8081 had homologues in yersinia pestis plasmid pcd1 or in y. enterocolitica serotype 0:9 plasmid pyve227. a region of approximately 17 kbp showed no dna identity to pcd ...200111402007
beta-aminobutyric acid-induced protection of arabidopsis against the necrotrophic fungus botrytis cinerea.the non-protein amino acid beta-aminobutyric acid (baba) protects numerous plants against various pathogens. protection of arabidopsis plants against virulent pathogens involves the potentiation of pathogen-specific defense responses. to extend the analysis of the mode of action of baba to necrotrophs we evaluated the effect of this chemical on arabidopsis plants infected with the gray mold fungus botrytis cinerea. baba-treated arabidopsis were found to be less sensitive to two different strains ...200111402183
jasmonate-dependent induction of indole glucosinolates in arabidopsis by culture filtrates of the nonspecific pathogen erwinia carotovora.elicitors from the plant pathogen erwinia carotovora trigger coordinate induction of the tryptophan (trp) biosynthesis pathway and trp oxidizing genes in arabidopsis. to elucidate the biological role of such pathogen-induced activation we characterized the production of secondary defense metabolites such as camalexin and indole glucosinolates derived from precursors of this pathway. elicitor induction was followed by a specific increase in 3-indolylmethylglucosinolate (igs) content, but only a b ...200111402212
characterization of the lipopolysaccharide and structure of the o-specific polysaccharide of the bacterium pseudomonas syringae pv. atrofaciens imv 948.lipopolysaccharide (lps) was isolated from the phytopathogenic bacterium pseudomonas syringae pv. atrofaciens imv 948 by mild extraction of the microbial cells with saline, and the properties, composition, and structure of the lps were studied. the lps showed low toxicity in d- galactosamine-sensitized mice and low biological activity in plants. structural components of lps--lipid a, core oligosaccharide, and o-specific polysaccharide (ops)--were obtained by mild acid degradation and characteriz ...200111403642
analysis of the enzymatic domains in the modular portion of the coronafacic acid polyketide synthase.coronafacic acid (cfa) is the polyketide component of coronatine (cor), a phytotoxin produced by the plant pathogen pseudomonas syringae. the cfa polyketide synthase (pks) consists of two open reading frames (orfs) that encode type i multifunctional proteins and several orfs that encode monofunctional proteins. sequence comparisons of the modular portions of the cfa pks with other prokaryotic, modular pkss elucidated the boundaries of the domains that are involved in the individual stages of pol ...200111404016
broad-spectrum antimicrobial activity in vitro of the synthetic peptide d4e1.broad-spectrum antimicrobial activity of a synthetic peptide, d4e1, is documented in this paper. d4e1 inhibited the growth of several fungal phytopathogens belonging to four classes-ascomycetes, basidiomycetes, deuteromycetes, and oomycetes, and two bacterial pathogens, pseudomonas syringae pv. tabaci and xanthomonas campestris pv. malvacearum race 18. the minimum inhibitory concentration (mic) of d4e1 required to completely inhibit the growth of all fungi studied ranged from 4.67 to 25 microm. ...200111409968
the alkane hydroxylase gene of burkholderia cepacia rr10 is under catabolite repression control.in many microorganisms the first step for alkane degradation is the terminal oxidation of the molecule by an alkane hydroxylase. we report the characterization of a gene coding for an alkane hydroxylase in a burkholderia cepacia strain isolated from an oil-contaminated site. the protein encoded showed similarity to other known or predicted bacterial alkane hydroxylases, although it clustered on a separate branch together with the predicted alkane hydroxylase of a mycobacterium tuberculosis strai ...200111418560
trans-3-chloroacrylic acid dehalogenase from pseudomonas pavonaceae 170 shares structural and mechanistic similarities with 4-oxalocrotonate tautomerase.the genes (caad1 and caad2) encoding the trans-3-chloroacrylic acid dehalogenase (caad) of the 1,3-dichloropropene-utilizing bacterium pseudomonas pavonaceae 170 were cloned and heterologously expressed in escherichia coli and pseudomonas sp. strain gj1. caad is a protein of 50 kda that is composed of alpha-subunits of 75 amino acid residues and beta-subunits of 70 residues. it catalyzes the hydrolytic cleavage of the beta-vinylic carbon-chlorine bond in trans-3-chloroacrylic acid with a turnove ...200111418568
constitutive salicylic acid-dependent signaling in cpr1 and cpr6 mutants requires pad4.salicylic acid (sa)-dependent signaling controls activation of a set of plant defense mechanisms that are important for resistance to a variety of microbial pathogens. many arabidopsis mutants that display altered sa-dependent signaling have been isolated. we used double mutant analysis to determine the relative positions of the pad4, cpr1, cpr5, cpr6, dnd1 and dnd2 mutations in the signal transduction network leading to sa-dependent activation of defense gene expression and disease resistance. ...200111439127
resistance to pseudomonas syringae conferred by an arabidopsis thaliana coronatine-insensitive (coi1) mutation occurs through two distinct mechanisms.a new allele of the coronatine-insensitive locus (coi1) was isolated in a screen for arabidopsis thaliana mutants with enhanced resistance to the bacterial pathogen pseudomonas syringae. this mutant, designated coi1-20, exhibits robust resistance to several p. syringae isolates but remains susceptible to the virulent pathogens erisyphe and cauliflower mosaic virus. resistance to p. syringae strain pstdc3000 in coi1-20 plants is correlated with hyperactivation of pr-1 expression and accumulation ...200111439137
potential virulence role of the legionella pneumophila ptsp ortholog.we previously identified the legionella pneumophila ptsp (phosphoenolpyruvate phosphotransferase) ortholog gene as a putative virulence factor in a study of signature-tagged mutagenesis using a guinea pig pneumonia model. in this study, we further defined the phenotypic properties of l. pneumophila ptsp and its complete sequence. the l. pneumophila ptsp was 2,295 bases in length. its deduced amino acid sequence had high similarity with ptsp orthologs of pseudomonas aeruginosa, azotobacter vinela ...200111447151
evolutionary relationships among virulence-associated histidine kinases.a strong relationship between virulence-associated sensor histidine kinases of fungi and those in streptomyces coelicolor was observed, and phylogenetic analysis suggested that bacterium-to-eukaryote horizontal gene transfer had occurred between ancestors of these organisms. phylogenetic analysis also identified a group of histidine kinases orthologous to the streptomyces proteins that includes pseudomonas aeruginosa gacs. we provide evidence that gacs is important for swarming motility, lipase ...200111447209
persistence and translocation of a benzothiadiazole derivative in tomato plants in relation to systemic acquired resistance against pseudomonas syringae pv tomato.a reproducible and accurate procedure, based on hplc analysis, has been developed to determine simultaneously acibenzolar-s-methyl (cga 245 704) and its acid derivative (cga 210 007) in tomato leaves. the limit of detection and quantification of the method are 0.015 and 0.15 mg litre-1 for cga 245 704 and 0.030 and 0.30 mg litre-1 for cga 210 007. in tomato plants treated with 250 microm cga 245 704, it was found that the inducer rapidly translocates from treated leaves (cotyledons, 1st and 2nd) ...200111455656
the ice nucleation temperature determines the primary drying rate of lyophilization for samples frozen on a temperature-controlled shelf.the objective of this study was to determine the influence of ice nucleation temperature on the primary drying rate during lyophilization for samples in vials that were frozen on a lyophilizer shelf. aqueous solutions of 10% (w/v) hydroxyethyl starch were frozen in vials with externally mounted thermocouples and then partially lyophilized to determine the primary drying rate. low- and high-particulate-containing samples, ice-nucleating additives silver iodide and pseudomonas syringae, and other ...200111458335
oxidation of phenolate siderophores by the multicopper oxidase encoded by the escherichia coli yack gene.a gene (yack) encoding a putative multicopper oxidase (mco) was cloned from escherichia coli, and the expressed enzyme was demonstrated to exhibit phenoloxidase and ferroxidase activities. the purified protein contained six copper atoms per polypeptide chain and displayed optical and electron paramagnetic resonance (epr) spectra consistent with the presence of type 1, type 2, and type 3 copper centers. the strong optical a(610) (e(610) = 10,890 m(-1) cm(-1)) and copper stoichiometry were taken a ...200111466290
crystallization and preliminary x-ray analysis of clade i catalases from pseudomonas syringae and listeria seeligeri.haem-containing catalases are homotetrameric molecules that degrade hydrogen peroxide. phylogenetically, the haem-containing catalases can be grouped into three main lines or clades. the crystal structures of seven catalases have been determined, all from clades ii and iii. in order to obtain a structure of an enzyme from clade i, which includes all plant, algae and some bacterial enzymes, two bacterial catalases, catf from pseudomonas syringae and kat from listeria seeligeri, have been crystall ...200111468413
quantitative analysis of bacterial gene expression by using the gusa reporter gene system.an azospirillum brasilense sp7 strain containing a plasmid-borne translational cytn-gusa fusion was grown in a continuous culture to quantitatively evaluate the influence of extracellular signals (such as o(2)) on expression of the cytnoqp operon. the dissolved oxygen concentration was shifted at regular time intervals before the steady state was reached. the measured beta-glucuronidase activity was used to monitor cytn gene expression. however, as the beta-glucuronidase activity in the experime ...200111472903
carbon limitation induces sigma(s)-dependent gene expression in pseudomonas fluorescens in soil.recent studies employing reporter gene technology indicate that the availabilities of the major nutrients nitrogen, phosphate, and iron to pseudomonas are not severely limited in bulk soil. indirect evidence has pointed to carbon limitation as a severe nutritional stress in this environment. we show that a plasmid (pgm115)-borne transcriptional fusion between the sigma(s)-dependent escherichia coli promoter p(fic) and lacz functions as a reliable reporter for carbon availability in pseudomonas f ...200111472905
assessment of the genetic diversity among strains of xanthomonas cynarae by randomly amplified polymorphic dna analysis and development of specific characterized amplified regions for the rapid identification of x. cynarae.the randomly amplified polymorphic dna (rapd) method was used to investigate the genetic diversity in xanthomonas cynarae, which causes bacterial bract spot disease of artichoke. this rapd analysis was also intended to identify molecular markers characteristic of this species, in order to develop pcr-based markers which can be used to detect this pathogenic bacterium in artichoke fields. among the 340 rapd primers tested, 40 were selected on their ability to produce reproducible and reliable fin ...200111472907
use of an intergenic region in pseudomonas syringae pv. syringae b728a for site-directed genomic marking of bacterial strains for field experiments.to construct differentially-marked derivatives of our model wild-type strain, pseudomonas syringae pv. syringae b728a (a causal agent of bacterial brown spot disease in snap bean plants), for field experiments, we selected a site in the gacs-cysm intergenic region for site-directed insertion of antibiotic resistance marker cassettes. in each of three field experiments, population sizes of the site-directed chromosomally marked b728a derivatives in association with snap bean plants were not signi ...200111472957
isolation and in vivo and in vitro antifungal activity of phenylacetic acid and sodium phenylacetate from streptomyces humidus.the antifungal substances sh-1 and sh-2 were isolated from streptomyces humidus strain s5-55 cultures by various purification procedures and identified as phenylacetic acid and sodium phenylacetate, respectively, based on the nuclear magnetic resonance, electron ionization mass spectral, and inductively coupled plasma mass spectral data. sh-1 and sh-2 completely inhibited the growth of pythium ultimum, phytophthora capsici, rhizoctonia solani, saccharomyces cerevisiae, and pseudomonas syringae p ...200111472958
activation of salicylic acid-induced protein kinase, a mitogen-activated protein kinase, induces multiple defense responses in tobacco.the activation of mitogen-activated protein kinases (mapks) is one of the earliest responses in plants challenged by avirulent pathogens or cells treated with pathogen-derived elicitors. expression of a constitutively active mapk kinase, ntmek2(dd), in tobacco induces the expression of defense genes and hypersensitive response-like cell death, which are preceded by the activation of two endogenous mapks, salicylic acid-induced protein kinase (sipk) and wounding-induced protein kinase (wipk). how ...200111487699
hsr203 antisense suppression in tobacco accelerates development of hypersensitive cell death.activation of the tobacco gene hsr203 is rapid, highly localized, specific for incompatible plant-pathogen interactions, and strongly correlated with programmed cell death occurring in response to diverse pathogens. functional characterization of hsr203 gene product has shown that hsr203 is a serine hydrolase that displays esterase activity. we show here that transgenic tobacco plants deficient in hsr203 protein exhibit an accelerated hypersensitive response when inoculated with an avirulent str ...200111489189
halohydrin dehalogenases are structurally and mechanistically related to short-chain dehydrogenases/reductases.halohydrin dehalogenases, also known as haloalcohol dehalogenases or halohydrin hydrogen-halide lyases, catalyze the nucleophilic displacement of a halogen by a vicinal hydroxyl function in halohydrins to yield epoxides. three novel bacterial genes encoding halohydrin dehalogenases were cloned and expressed in escherichia coli, and the enzymes were shown to display remarkable differences in substrate specificity. the halohydrin dehalogenase of agrobacterium radiobacter strain ad1, designated hhe ...200111489858
absence of all components of the flagellar export and synthesis machinery differentially alters virulence of salmonella enterica serovar typhimurium in models of typhoid fever, survival in macrophages, tissue culture invasiveness, and calf enterocolitis.in this study, we constructed an flhd (the master flagellar regulator gene) mutant of salmonella enterica serovar typhimurium and compared the virulence of the strain to that of the wild-type strain in a series of assays that included the mouse model of typhoid fever, the mouse macrophage survival assay, an intestinal epithelial cell adherence and invasion assay, and the calf model of enterocolitis. we found that the flhd mutant was more virulent than its parent in the mouse and displayed slight ...200111500437
harpin induces activation of the arabidopsis mitogen-activated protein kinases atmpk4 and atmpk6.mitogen-activated protein kinases (mapks) are key enzymes that mediate adaptive responses to various abiotic and biotic stresses, including pathogen challenge. the proteinaceous bacterial elicitor harpin (secreted by pseudomonas syringae pv syringae) activates two mapks in suspension cultures of arabidopsis var. landsberg erecta. in this study, we show that harpin and exogenous hydrogen peroxide (h(2)o(2)) activate myelin basic protein kinases in arabidopsis leaves. using anti-atmpk4 and anti-at ...200111500556
expression of 35s::pto globally activates defense-related genes in tomato plants.the tomato (lycopersicon esculentum) resistance gene pto confers resistance to the bacterial pathogen pseudomonas syringae pv tomato carrying the avirulent gene avrpto. overexpressing pto under the control of the cauliflower mosaic virus 35s promoter constitutively activates defense responses in the absence of pathogen infection and nonspecifically enhances disease resistance. to elucidate the mechanisms underlying this resistance, we isolated cdnas corresponding to transcripts that accumulated ...200111500562
n-terminal fatty acid substitution increases the leishmanicidal activity of ca(1-7)m(2-9), a cecropin-melittin hybrid peptide.in order to improve the leishmanicidal activity of the synthetic cecropin a-melittin hybrid peptide ca(1-7)m(2-9) (kwklfkkigavlkvl-nh(2)), a systematic study of its acylation with saturated linear fatty acids was carried out. acylation of the n(epsilon)-7 lysine residue led to a drastic decrease in leishmanicidal activity, whereas acylation at lysine 1, in either the alpha or the epsilon nh(2) group, increased up to 3 times the activity of the peptide against promastigotes and increased up to 15 ...200111502512
hypervalent iodine compounds as potent antibacterial agents against ice nucleation active (ina) pseudomonas syringae.twenty-three hypervalent iodine compounds belonging to aryliodonium salts, 1, aryliodonium ylides, 2, and (diacyloxyiodo)arenes, 3, were tested for their antibacterial activities against ice nucleation active (ina) pseudomonas syringae, and the mic and ec(50) values were determined. all of the compounds examined caused a dose-dependent decrease in bacterial growth rates. aryliodonium salts, especially those with electron-withdrawing groups, exhibit higher antibacterial activities with mic = 8-16 ...200111513659
rapid identification and differentiation of the soft rot erwinias by 16s-23s intergenic transcribed spacer-pcr and restriction fragment length polymorphism analyses.current identification methods for the soft rot erwinias are both imprecise and time-consuming. we have used the 16s-23s rrna intergenic transcribed spacer (its) to aid in their identification. analysis by its-pcr and its-restriction fragment length polymorphism was found to be a simple, precise, and rapid method compared to current molecular and phenotypic techniques. the its was amplified from erwinia and other genera using universal pcr primers. after pcr, the banding patterns generated allow ...200111526007
gly gene cloning and expression and purification of glycinecin a, a bacteriocin produced by xanthomonas campestris pv. glycines 8ra.glycinecin a, a bacteriocin produced by xanthomonas campestris pv. glycines, inhibits the growth of x. campestris pv. vesicatoria. we have cloned and expressed the genes encoding glycinecin a in escherichia coli. recombinant glycinecin a was purified from cell extracts by ammonium sulfate precipitation followed by chromatography on q-sepharose, mono q (ion exchange), and size exclusion columns. purified glycinecin a is composed of two polypeptides, is active over a wide ph range (6 to 9), and is ...200111526012
a second quorum-sensing system regulates cell surface properties but not phenazine antibiotic production in pseudomonas aureofaciens.the root-associated biological control bacterium pseudomonas aureofaciens 30-84 produces a range of exoproducts, including protease and phenazines. phenazine antibiotic biosynthesis by phzxyfabcd is regulated in part by the phzr-phzi quorum-sensing system. mutants defective in phzr or phzi produce very low levels of phenazines but wild-type levels of exoprotease. in the present study, a second genomic region of strain 30-84 was identified that, when present in trans, increased beta-galactosidase ...200111526037
characterization by 16s rrna sequence analysis of pseudomonads causing blotch disease of cultivated agaricus bisporus.bacterial blotch of agaricus bisporus has typically been identified as being caused by either pseudomonas tolaasii (brown blotch) or pseudomonas gingeri (ginger blotch). to address the relatedness of pseudomonads able to induce blotch, a pilot study was initiated in which pseudomonads were selectively isolated from mushroom farms throughout new zealand. thirty-three pseudomonad isolates were identified as being capable of causing different degrees of discoloration (separable into nine categories ...200111526038
the arabidopsis aberrant growth and death2 mutant shows resistance to pseudomonas syringae and reveals a role for npr1 in suppressing hypersensitive cell death.a novel arabidopsis mutant has been identified with constitutive expression of gst1-gus using plants with a pathogen-responsive reporter transgene containing the beta-glucuronidase (gus) coding region driven by the gst1 promoter. the recessive mutant, called agd2 (aberrant growth and death2), has salicylic acid (sa)-dependent increased resistance to virulent and avirulent strains of the bacterial pathogen pseudomonas syringae, elevated sa levels, a low level of spontaneous cell death, callose de ...200111532166
enhancer-binding proteins hrpr and hrps interact to regulate hrp-encoded type iii protein secretion in pseudomonas syringae strains.in pseudomonas syringae strains, the hrp-hrc pathogenicity island consists of an hrpl-dependent regulon that encodes a type iii protein translocation complex and translocated effector proteins required for pathogenesis. hrpr and hrps function as positive regulatory factors for the hrpl promoter, but their mechanism of action has not been established. both hrpr and hrps are structurally related to enhancer-binding proteins, but they lack receiver domains and do not appear to require a cognate pro ...200111544221
complete nucleotide sequence and organization of the atrazine catabolic plasmid padp-1 from pseudomonas sp. strain adp.the complete 108,845-nucleotide sequence of catabolic plasmid padp-1 from pseudomonas sp. strain adp was determined. plasmid padp-1 was previously shown to encode atza, atzb, and atzc, which catalyze the sequential hydrolytic removal of s-triazine ring substituents from the herbicide atrazine to yield cyanuric acid. computational analyses indicated that padp-1 encodes 104 putative open reading frames (orfs), which are predicted to function in catabolism, transposition, and plasmid maintenance, t ...200111544232
epidemic population structure of pseudomonas aeruginosa: evidence for a clone that is pathogenic to the eye and that has a distinct combination of virulence factors.the genetic structure of a population of pseudomonas aeruginosa, isolated from patients with keratitis, endophthalmitis, and contact lens-associated red eye, contact lens storage cases, urine, ear, blood, lungs, wounds, feces, and the environment was determined by multilocus enzyme electrophoresis. the presence and characteristics of virulence factors were determined by restriction fragment length polymorphism analysis with dna probes for lasa, lasb, apra, exos, exot, exou, and ctx and by zymogr ...200111553572
salicylic acid and ethylene pathways are differentially activated in melon cotyledons by active or heat-denatured cellulase from trichoderma longibrachiatum.infiltration of cellulase (ec 3.2.1.4) from trichoderma longibrachiatum into melon (cucumis melo) cotyledons induced several key defense mechanisms and hypersensitive reaction-like symptoms. an oxidative burst was observed 3 hours after treatment and was followed by activation of ethylene and salicylic acid (sa) signaling pathways leading to marked induction of peroxidase and chitinase activities. the treatment of cotyledons by heat-denatured cellulase also led to some induction of peroxidase an ...200111553761
type iii secretion in plant growth-promoting pseudomonas fluorescens sbw25.in vivo expression technology (ivet) analysis of rhizosphere-induced genes in the plant growth-promoting rhizobacterium (pgpr) pseudomonas fluorescens sbw25 identified a homologue of the type iii secretion system (ttss) gene hrcc. the hrcc homologue resides within a 20-kb gene cluster that resembles the type iii (hrp) gene cluster of pseudomonas syringae. the type iii (rsp) gene cluster in p. fluorescens sbw25 is flanked by a homologue of the p. syringae ttss-secreted protein avre. p. fluorescen ...200111555282
genetic characterization of pseudomonas 'nzi7'--a novel pathogen that results in a brown blotch disease of agaricus bisporus.to characterize a novel pseudomonad isolate capable of causing brown blotch disease of agaricus bisporus.200111556905
[comparative characteristics of lipopolysaccharides of various pseudomonas fluorescens strains (biovar i)].from the biomass of five pseudomonas fluorescens biovar i strains, including the p. fluorescens type strain imv 4125 (atcc 13525), lipopolysaccharides (lps) were isolated (by extraction with a phenol-water mixture followed by repeated ultracentrifugation), as well as individual structural components of the lps macromolecule: lipid a, the core oligosaccharide, and o-specific polysaccharide (o-ps). 3-hydroxydecanoic, 2-hydroxydodecanoic, 3-hydroxydodecanoic, dodecanoic, hexadecanoic, octadecanoic, ...200111558277
lignification induced by pseudomonads harboring avirulent genes on arabidopsis.the responses of arabidopsis thaliana ecotypes to the bacterial pathogen pseudomonas syringae pv. maculicola 4326 (psm4326) harboring cloned avirulence genes avrb and avrrpt2 from p. syringae pv. glycinea were examined. psm4326 containing avirulent genes, avrb and avrrpt2 induced lignification and peroxidase activities in the bacteria infiltrated leaves of col-o only and not in mt-o, bla-2 and po-1. however, arabidopsis ecotypes infiltrated with psm4326 harboring with and without avirulent genes ...200111561727
escherichia coli fadr positively regulates transcription of the fabb fatty acid biosynthetic gene.in escherichia coli expression of the genes of fatty acid degradation (fad) is negatively regulated at the transcriptional level by fadr protein. in contrast the unsaturated fatty acid biosynthetic gene, faba, is positively regulated by fadr. we report that fabb, a second unsaturated fatty acid biosynthetic gene, is also positively regulated by fadr. genomic array studies that compared global transcriptional differences between wild-type and fadr-null mutant strains, as well as in cultures of ea ...200111566998
ssebcd proteins are secreted by the type iii secretion system of salmonella pathogenicity island 2 and function as a translocon.the type iii secretion system encoded by salmonella pathogenicity island 2 (spi2) is required for systemic infections and intracellular accumulation of salmonella enterica. this system is induced by intracellular salmonella and subsequently transfers effector proteins into the host cell. growth conditions either inducing expression of the type iii secretion system or the secretion of substrate proteins were defined. here we report the identification of a set of substrate proteins consisting of s ...200111567004
direct interaction between the arabidopsis disease resistance signaling proteins, eds1 and pad4.the arabidopsis eds1 and pad4 genes encode lipase-like proteins that function in resistance (r) gene-mediated and basal plant disease resistance. phenotypic analysis of eds1 and pad4 null mutants shows that eds1 and pad4 are required for resistance conditioned by the same spectrum of r genes but fulfil distinct roles within the defence pathway. eds1 is essential for elaboration of the plant hypersensitive response, whereas eds1 and pad4 are both required for accumulation of the plant defence-pot ...200111574472
cdna-aflp analysis unravels a genome-wide hrpg-regulon in the plant pathogen xanthomonas campestris pv. vesicatoria.the hrp type iii protein secretion system is essential for pathogenicity of the gram-negative plant pathogen xanthomonas campestris pv. vesicatoria. expression of the hrp gene cluster is controlled by hrpg, a two-component response regulator, and hrpx, an arac-type transcriptional activator. using the cdna-aflp technique, 30 hrpg-induced (hgi) and five hrpg-repressed (hgr) cdna fragments were identified, defining a large hrpg-regulon in x. campestris pv. vesicatoria. expression of most genes in ...200111580833
pseudomonas aeruginosa pao1 kills caenorhabditis elegans by cyanide poisoning.in this report we describe experiments to investigate a simple virulence model in which pseudomonas aeruginosa pao1 rapidly paralyzes and kills the nematode caenorhabditis elegans. our results imply that hydrogen cyanide is the sole or primary toxic factor produced by p. aeruginosa that is responsible for killing of the nematode. four lines of evidence support this conclusion. first, a transposon insertion mutation in a gene encoding a subunit of hydrogen cyanide synthase (hcnc) eliminated nemat ...200111591663
bacterial two-hybrid analysis of interactions between region 4 of the sigma(70) subunit of rna polymerase and the transcriptional regulators rsd from escherichia coli and algq from pseudomonas aeruginosa.a number of transcriptional regulators mediate their effects through direct contact with the sigma(70) subunit of escherichia coli rna polymerase (rnap). in particular, several regulators have been shown to contact a c-terminal portion of sigma(70) that harbors conserved region 4. this region of sigma contains a putative helix-turn-helix dna-binding motif that contacts the -35 element of sigma(70)-dependent promoters directly. here we report the use of a recently developed bacterial two-hybrid s ...200111591686
mammalian bax-induced plant cell death can be down-regulated by overexpression of arabidopsis bax inhibitor-1 (atbi-1).we recently isolated the atbi-1 (arabidopsis bax inhibitor-1) gene, the expression of which suppressed bax-induced cell death in yeast. to determine whether the same is true in the plant system, transgenic arabidopsis plants overexpressing bax protein under a dexamethasone (dex)-inducible promoter were generated. on dex treatment, such transgenic plants exhibited marked cell death at the whole-plant level, cell shrinkage, membranous destruction, and other apoptotic phenotypes. transgenic bax pla ...200111593047
a humidity-sensitive arabidopsis copine mutant exhibits precocious cell death and increased disease resistance.the copines are a newly identified class of calcium-dependent, phospholipid binding proteins that are present in a wide range of organisms, including paramecium, plants, caenorhabditis elegans, mouse, and human. however, the biological functions of the copines are unknown. here, we describe a humidity-sensitive copine mutant in arabidopsis. under nonpermissive, low-humidity conditions, the cpn1-1 mutant displayed aberrant regulation of cell death that included a lesion mimic phenotype and an acc ...200111595798
the esat-6 gene cluster of mycobacterium tuberculosis and other high g+c gram-positive bacteria.the genome of mycobacterium tuberculosis h37rv has five copies of a cluster of genes known as the esat-6 loci. these clusters contain members of the cfp-10 (lhp) and esat-6 (esat-6) gene families (encoding secreted t-cell antigens that lack detectable secretion signals) as well as genes encoding secreted, cell-wall-associated subtilisin-like serine proteases, putative abc transporters, atp-binding proteins and other membrane-associated proteins. these membrane-associated and energy-providing pro ...200111597336
families of restriction enzymes: an analysis prompted by molecular and genetic data for type id restriction and modification systems.current genetic and molecular evidence places all the known type i restriction and modification systems of escherichia coli and salmonella enterica into one of four discrete families: type ia, ib, ic or id. stysbli is the founder member of the id family. similarities of coding sequences have identified restriction systems in e.coli and klebsiella pneumoniae as probable members of the type id family. we present complementation tests that confirm the allocation of ecor9i and kpnai to the id family ...200111600708
activation of an eds1-mediated r-gene pathway in the snc1 mutant leads to constitutive, npr1-independent pathogen resistance.the arabidopsis npr1 protein is an essential regulatory component of systemic acquired resistance (sar). mutations in the npr1 gene completely block the induction of sar by signals such as salicylic acid (sa). an arabidopsis mutant, snc1 (suppressor of npr1-1, constitutive 1), was isolated in a screen for suppressors of npr1-1. in the npr1-1 background, the snc1 mutation resulted in constitutive resistance to pseudomonas syringae maculicola es4326 and peronospora parasitica noco2. high levels of ...200111605952
genetic organization of the pantoea stewartii subsp. stewartii hrp gene cluster and sequence analysis of the hrpa, hrpc, hrpn, and wtse operons.the hrp/wts gene cluster of pantoea stewartii subsp. stewartii is required for pathogenicity on sweet corn and the ability to elicit a hypersensitive response (hr) in tobacco. site-directed transposon mutagenesis and nucleotide sequencing were used to identify hrp/wts genes within the left 20 kb of this cluster. seventeen open reading frames (orfs) comprise seven genetic complementation groups. these orfs share homology with hrp and dsp genes from erwinia amylovora, erwinia chrysanthemi, and pse ...200111605961
novel tellurite-amended media and specific chromosomal and ti plasmid probes for direct analysis of soil populations of agrobacterium biovars 1 and 2.ecology and biodiversity studies of agrobacterium spp. require tools such as selective media and dna probes. tellurite was tested as a selective agent and a supplement of previously described media for agrobacteria. the known biodiversity within the genus was taken into account when the selectivity of k(2)teo(3) was analyzed and its potential for isolating agrobacterium spp. directly from soil was evaluated. a k(2)teo(3) concentration of 60 ppm was found to favor the growth of agrobacteria and r ...200111133429
direct cloning from enrichment cultures, a reliable strategy for isolation of complete operons and genes from microbial consortia.enrichment cultures of microbial consortia enable the diverse metabolic and catabolic activities of these populations to be studied on a molecular level and to be explored as potential sources for biotechnology processes. we have used a combined approach of enrichment culture and direct cloning to construct cosmid libraries with large (>30-kb) inserts from microbial consortia. enrichment cultures were inoculated with samples from five environments, and high amounts of avidin were added to the cu ...200111133432
pantoea agglomerans strain eh318 produces two antibiotics that inhibit erwinia amylovora in vitro.pantoea agglomerans (synonym: erwinia herbicola) strain eh318 produces through antibiosis a complex zone of inhibited growth in an overlay seeded with erwinia amylovora, the causal agent of fire blight. this zone is caused by two antibiotics, named pantocin a and b. using a genomic library of eh318, two cosmids, pcpp702 and pcpp704, were identified that conferred on escherichia coli the ability to inhibit growth of e. amylovora. the two cosmids conferred different antibiotic activities on e. col ...200111133457
gene cloning and functional characterization by heterologous expression of the fructosyltransferase of aspergillus sydowi iam 2544.we have purified a fructosyltransferase from conidia of the inulin-producing fungus aspergillus sydowi iam 2544 and obtained peptide sequences from proteolytic fragments of the protein. with degenerated primers, we amplified a pcr fragment that was used to screen a cdna library. the fructosyltransferase gene from aspergillus sydowi (embl accession no. aj289046) is expressed in conidia, while no expression could be detected in mycelia by northern blot analysis of mycelial rna. the gene encodes a ...200111133467
genetic and molecular organization of the alkylbenzene catabolism operon in the psychrotrophic strain pseudomonas putida 01g3.the 11-kb sequence encompassing the alkylbenzene upper pathway in pseudomonas putida 01g3, a psychrotrophic strain able to degrade alkylbenzenes at low temperatures, was characterized. together with a potential regulator (ebdr), six putative enzymes (ebdaaabacadbc) were identified, and they exhibited highly significant similarities with enzymes implicated in the equivalent pathway in p. putida re204. ebd genes appeared to be preferentially induced by ethylbenzene. multiple-alignment data and gro ...200111133479
hrpz(psph) from the plant pathogen pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro.the hrp gene clusters of plant pathogenic bacteria control pathogenicity on their host plants and ability to elicit the hypersensitive reaction in resistant plants. some hrp gene products constitute elements of the type iii secretion system, by which effector proteins are exported and delivered into plant cells. here, we show that the hrpz gene product from the bean halo-blight pathogen, pseudomonas syringae pv. phaseolicola (hrpz(psph)), is secreted in an hrp-dependent manner in p. syringae pv. ...200111134504
hrpz(psph) from the plant pathogen pseudomonas syringae pv. phaseolicola binds to lipid bilayers and forms an ion-conducting pore in vitro.the hrp gene clusters of plant pathogenic bacteria control pathogenicity on their host plants and ability to elicit the hypersensitive reaction in resistant plants. some hrp gene products constitute elements of the type iii secretion system, by which effector proteins are exported and delivered into plant cells. here, we show that the hrpz gene product from the bean halo-blight pathogen, pseudomonas syringae pv. phaseolicola (hrpz(psph)), is secreted in an hrp-dependent manner in p. syringae pv. ...200111134504
the release of alginate lyase from growing pseudomonas syringae pathovar phaseolicola.pseudomonas syringae pathovar phaseolicola, which produces alginate during stationary growth phase, displayed elevated extracellular alginate lyase activity during both mid-exponential and late-stationary growth phases of batch growth. intracellular activity remained below 22% of the total activity during exponential growth, suggesting that alginate lyase has an extracellular function for this organism. extracellular enzyme activity in continuous cultures, grown in either nutrient broth or gluco ...200111136126
accumulation of soluble and wall-bound indolic metabolites in arabidopsis thaliana leaves infected with virulent or avirulent pseudomonas syringae pathovar tomato strains.the chemical structures and accumulation kinetics of several major soluble as well as wall-bound, alkali-hydrolyzable compounds induced upon infection of arabidopsis thaliana leaves with pseudomonas syringae pathovar tomato were established. all identified accumulating products were structurally related to tryptophan. most prominent among the soluble substances were tryptophan, beta-d-glucopyranosyl indole-3-carboxylic acid, 6-hydroxyindole-3-carboxylic acid 6-o-beta-d-glucopyranoside, and the i ...200111136235
analysis of the type iv fimbrial-subunit gene fima of xanthomonas hyacinthi: application in pcr-mediated detection of yellow disease in hyacinths.a sensitive and specific detection method was developed for xanthomonas hyacinthi; this method was based on amplification of a subsequence of the type iv fimbrial-subunit gene fima from strain s148. the fima gene was amplified by pcr with degenerate dna primers designed by using the n-terminal and c-terminal amino acid sequences of trypsin fragments of fima. the nucleotide sequence of fima was determined and compared with the nucleotide sequences coding for the fimbrial subunits in other type iv ...200111157222
iron-binding compounds from agrobacterium spp.: biological control strain agrobacterium rhizogenes k84 produces a hydroxamate siderophore.iron-binding compounds were produced in various amounts in response to iron starvation by a collection of agrobacterium strains belonging to the species a. tumefaciens, a. rhizogenes, and a. vitis. the crown gall biocontrol agent a. rhizogenes strain k84 produced a hydroxamate iron chelator in large amounts. production of this compound, and also of a previously described antibiotic-like substance called als84, occurred only in cultures of strain k84 grown in iron-deficient medium. similarly, sen ...200111157228
the adna transcriptional factor affects persistence and spread of pseudomonas fluorescens under natural field conditions.a soil plot was inoculated with a mixture of pseudomonas fluorescens pf0-2, the wild type, and pf0-5a, a tn5 insertion mutant in adna, at 7.84 log cfu/g of soil. over a period of 231 days, culturable populations of both strains were measured at selected times below and away from the point of inoculation. pf0-5a did not spread as fast and attained significantly lower populations than pf0-2. at sample depths below the inoculation site, the adna mutant showed a significant decrease in cfu/g of soil ...200111157254
potential symbiosis-specific genes uncovered by sequencing a 410-kilobase dna region of the bradyrhizobium japonicum chromosome.the physical and genetic map of the bradyrhizobium japonicum chromosome revealed that nitrogen fixation and nodulation genes are clustered. because of the complex interactions between the bacterium and the plant, we expected this chromosomal sector to contain additional genes that are involved in the maintenance of an efficient symbiosis. therefore, we determined the nucleotide sequence of a 410-kb region. the overall g+c nucleotide content was 59.1%. using a minimum gene length of 150 nucleotid ...200111157954
syringolin reprograms wheat to undergo hypersensitive cell death in a compatible interaction with powdery mildew.we had previously isolated and characterized syringolin a, one of the molecular determinants secreted by pseudomonas syringae pv syringae that is perceived by nonhost plant species such as rice. here, we show that syringolin a is recognized by wheat and that it induces the accumulation of gene transcripts and increases protection against powdery mildew when applied before inoculation. moreover, syringolin a essentially eradicates powdery mildew from infected wheat if applied after inoculation. t ...200111158536
the arabidopsis isr1 locus controlling rhizobacteria-mediated induced systemic resistance is involved in ethylene signaling.in arabidopsis, the rhizobacterial strain pseudomonas fluorescens wcs417r triggers an induced systemic resistance (isr) response that is effective against different types of pathogens. the isr signaling pathway functions independent of salicylic acid, but requires responsiveness to jasmonate (ja) and ethylene. using the genetic variability of isr inducibility between arabidopsis accessions, we recently identified a locus (isr1) on chromosome iii that is involved in isr signaling. accessions rld ...200111161023
the use of 16s and 16s-23s rdna to easily detect and differentiate common gram-negative orchard epiphytes.the identification of gram-negative pathogenic and non-pathogenic bacteria commonly isolated from an orchard phylloplane may result in a time consuming and tedious process for the plant pathologist. the paper provides a simple "one-step" protocol that uses the polymerase chain reaction (pcr) to amplify intergenic spacer regions between 16s and 23s genes and a portion of 16s gene in the prokaryotic rrna genetic loci. amplified 16s rdna, and restriction fragment length polymorphisms (rflp) followi ...200111166101
cell surface display of salmobin, a thrombin-like enzyme from agkistrodon halys venom on escherichia coli using ice nucleation protein.cell surface display on escherichia coli using ice nucleation protein was performed in order to develop a new expression system for recombinant eukaryotic proteins. salmobin, the thrombin-like enzyme obtained from korean snake (agkistrodon halys) venom was displayed on the surface of escherichia coli fused to the c-terminus of the ice nucleation protein (inp), an outer membrane protein of pseudomonas syringae. the thrombin cleavage site was inserted between salmobin and inp. the presence of salm ...200111166806
probenazole induces systemic acquired resistance in arabidopsis with a novel type of action.probenazole (pbz; 3-allyloxy-1,2-benzisothiazole-1,1-dioxide), which is the active ingredient in oryzemate, has been used widely in asia to protect rice plants against the rice blast fungus magnaporthe grisea. to study pbz's mode of action, we analyzed its ability, as well as that of its active metabolite 1, 2-benzisothiazol-3 (2h)-one 1,1-dioxide (bit) to induce defense gene expression and resistance in arabidopsis mutants that are defective in various defense signaling pathways. wild-type arab ...200111169191
the insect endosymbiont sodalis glossinidius utilizes a type iii secretion system for cell invasion.sodalis glossinidius is a maternally transmitted secondary endosymbiont residing intracellularly in tissues of the tsetse flies, glossina spp. in this study, we have used tn5 mutagenesis and a negative selection procedure to derive a s. glossinidius mutant that is incapable of invading insect cells in vitro and is aposymbiotic when microinjected into tsetse. this mutant strain harbors tn5 integrated into a chromosomal gene sharing high sequence identity with a type iii secretion system invasion ...200111172045
ancient origin of pathogen recognition specificity conferred by the tomato disease resistance gene pto.we have investigated the origin of the pto disease resistance (r) gene that was previously identified in the wild tomato species lycopersicon pimpinellifolium and isolated by map-based cloning. pto encodes a serine-threonine protein kinase that specifically recognizes strains of pseudomonas syringae pv. tomato (pst) that express the avirulence gene avrpto. we examined an accession of the distantly related wild species lycopersicon hirsutum var. glabratum that exhibits avrpto-specific resistance ...200111172075
an active role for a structured b-linker in effector control of the sigma54-dependent regulator dmpr.the activities of many prokaryotic sigma54-dependent transcriptional activators are controlled by the n-terminal a-domain of the protein, which is linked to the central transcriptional activation domain via a short b-linker. it used to be thought that these b-linkers simply serve as flexible tethers. here we show that the b-linker of the aromatic-responsive regulator dmpr and many other regulators of the family contain signature heptad repeats with regularly spaced hydrophobic amino acids. mutan ...200111179226
cloning and characterization of a bean udp-glucosyltransferase cdna expressed during plant-bacterial interactions.a cdna clone, which corresponds to an rna transcript that accumulates in bean during the hypersensitive reaction, was isolated and designated hra25 (for hypersensitive reaction associated). hra25 is predicted to encode a udp-glucosyltransferase. northern analysis was used to study hra25 transcript accumulation in bean in response to incompatible and compatible strains of pseudomonas syringae, an hrp- mutant, and wounding. our data suggest that the hra25 transcript is activated in response to spe ...200111194877
functional analysis of the type iii effectors avrrpt2 and avrrpm1 of pseudomonas syringae with the use of a single-copy genomic integration system.gram-negative phytopathogenic bacteria require a type iii secretion apparatus for pathogenesis, presumably to deliver avr effector proteins directly into plant cells. to extend previous studies of avr effectors that employed plasmids encoding avr proteins, we developed a system that permits the integration of any gene into the pseudomonas syringae genome in single copy. with this system, we confirmed earlier findings showing that p. syringae pv. maculicola strain psmes4326 expressing the avrrpt2 ...200111204777
the induction of tomato leucine aminopeptidase genes (lapa) after pseudomonas syringae pv. tomato infection is primarily a wound response triggered by coronatine.tomato plants constitutively express a neutral leucine aminopeptidase (lap-n) and an acidic lap (lap-a) during floral development and in leaves in response to insect infestation, wounding, and pseudomonas syringae pv. tomato infection. to assess the physiological roles of lap-a, a lapa-antisense construct (35s:aslapa1) was introduced into tomato. the 35s:aslapa1 plants had greatly reduced or showed undetectable levels of lap-a and lap-n proteins in healthy and wounded leaves and during floral de ...200111204785
immunogold labeling of hrp pili of pseudomonas syringae pv. tomato assembled in minimal medium and in planta.hypersensitive reaction and pathogenicity (hrp) genes are required for pseudomonas syringae pv. tomato (pst) dc3000 to cause disease in susceptible tomato and arabidopsis thaliana plants and to elicit the hypersensitive response in resistant plants. the hrp genes encode a type iii protein secretion system known as the hrp system, which in pst dc3000 secretes hrpa, hrpz, hrpw, and avrpto and assembles a surface appendage, named the hrp pilus, in hrp-gene-inducing minimal medium. hrpa has been sug ...200111204787
exchange of xcp (gsp) secretion machineries between pseudomonas aeruginosa and pseudomonas alcaligenes: species specificity unrelated to substrate recognition.pseudomonas aeruginosa and pseudomonas alcaligenes are gram-negative bacteria that secrete proteins using the type ii or general secretory pathway, which requires at least 12 xcp gene products (xcpa and xcpp to -z). despite strong conservation of this secretion pathway, gram-negative bacteria usually cannot secrete exoproteins from other species. based on results obtained with erwinia, it has been proposed that the xcpp and/or xcpq homologs determine this secretion specificity (m. linderberg, g. ...200111208795
activation of a mitogen-activated protein kinase pathway is involved in disease resistance in tobacco.hypersensitive response (hr), a form of programmed cell death, is frequently associated with plant disease resistance. it has been proposed that mitogen-activated protein kinase (mapk) cascades regulate hr cell death based on pharmacological studies by using kinase inhibitors. however, direct evidence is lacking. here, we demonstrate that ntmek2, a mapk kinase, is upstream of salicylic acid-induced protein kinase (sipk) and wounding-induced protein kinase (wipk), two tobacco mapks that are activ ...200111209069
structural determination of the phytotoxic mannan exopolysaccharide from pseudomonas syringae pv. ciccaronei.the structural determination was performed of a mannan exopolysaccharide from the gram negative bacterium pseudomonas syringae pv. ciccaronei, which is the pathogenic agent responsible for the leaf spots of carob plants. the structure, obtained by chemical, enzymatic and spectroscopic methods, consisted of a backbone of alpha-(1-->6)-linked mannopyranose units with 80% substituted at c-2 by mono-, di- and trisaccharide side chains. in addition, terminal glucose units and phosphate groups were fo ...200111217981
modeling pseudomonas syringae ice-nucleation protein as a beta-helical protein.antifreeze proteins (afps) inhibit the growth of ice, whereas ice-nucleation proteins (inps) promote its formation. although the structures of several afps are known, the structure of inp has been modeled thus far because of the difficulty in determining membrane protein structures. here, we present a novel model of an inp structure from pseudomonas syringae based on comparison with two newly determined insect afp structures. the results suggest that both this class of afps and inps may have a s ...200111222281
phase-variable expression of an operon encoding extracellular alkaline protease, a serine protease homolog, and lipase in pseudomonas brassicacearum.the rhizobacterium pseudomonas brassicacearum forms phenotypic variants which do not show extracellular protease and lipase activity. the operon encoding these enzymes, a serine protease homolog, and a type i secretion machinery was characterized. transcriptional lacz gene fusions revealed that the expression of the operon is under the control of phase variation.200111222613
genes involved in copper homeostasis in escherichia coli.recently, genes for two copper-responsive regulatory systems were identified in the escherichia coli chromosome. in this report, data are presented that support a hypothesis that the putative multicopper oxidase cueo and the transenvelope transporter cuscfba are involved in copper tolerance in e. coli.200111222619
arabidopsis nho1 is required for general resistance against pseudomonas bacteria.nonhost interactions are prevalent between plants and specialized phytopathogens. although it has great potential for providing crop plants with durable resistance, nonhost resistance is poorly understood. here, we show that nonhost resistance is controlled, at least in part, by general resistance. arabidopsis plants are resistant to the nonhost pathogen pseudomonas syringae pv phaseolicola nps3121 and completely arrest bacterial multiplication in the plant. ten arabidopsis mutants were isolated ...200111226196
acyl-homoserine lactone production is more common among plant-associated pseudomonas spp. than among soilborne pseudomonas spp.a total of 137 soilborne and plant-associated bacterial strains belonging to different pseudomonas species were tested for their ability to synthesize n-acyl-homoserine lactones (nahl). fifty-four strains synthesized nahl. interestingly, nahl production appears to be more common among plant-associated than among soilborne pseudomonas spp. indeed, 40% of the analyzed pseudomonas syringae strains produced nahl which were identified most often as the short-chain nahl, n-hexanoyl-l-homoserine lacton ...200111229911
biological sensor for sucrose availability: relative sensitivities of various reporter genes.a set of three sucrose-regulated transcriptional fusions was constructed. fusions p61rytir, p61rylac, and p61ryice contain the scrr sucrose repressor gene and the promoterless gfp, lacz, and inaz reporter genes, respectively, fused to the scry promoter from salmonella enterica serovar typhimurium. cells of erwinia herbicola containing these fusions are induced only in media amended with sucrose, fructose, or sorbose. while a large variation in sucrose-dependent reporter gene activity was observe ...200111229926
genetic evidence that loss of virulence associated with gacs or gaca mutations in pseudomonas syringae b728a does not result from effects on alginate production.mutations in the global regulatory genes gacs and gaca render pseudomonas syringae pv. syringae strain b728a completely nonpathogenic in foliar infiltration assays on bean plants. it had been previously demonstrated that gac genes regulate alginate production in pseudomonas species, while other published work indicated that alginate is involved in the pathogenic interaction of p. syringae on bean plants. together, these results suggested that the effects of gacs and gaca mutations on virulence i ...200111229941
negative regulation of defense responses in plants by a conserved mapkk kinase.the enhanced disease resistance 1 (edr1) mutation of arabidopsis confers resistance to powdery mildew disease caused by the fungus erysiphe cichoracearum. resistance mediated by the edr1 mutation is correlated with induction of several defense responses, including host cell death. double mutant analysis revealed that all edr1-associated phenotypes are suppressed by mutations that block salicylic acid (sa) perception (nim1) or reduce sa production (pad4 and eds1). the nahg transgene, which lowers ...200111114160
negative regulation of defense responses in plants by a conserved mapkk kinase.the enhanced disease resistance 1 (edr1) mutation of arabidopsis confers resistance to powdery mildew disease caused by the fungus erysiphe cichoracearum. resistance mediated by the edr1 mutation is correlated with induction of several defense responses, including host cell death. double mutant analysis revealed that all edr1-associated phenotypes are suppressed by mutations that block salicylic acid (sa) perception (nim1) or reduce sa production (pad4 and eds1). the nahg transgene, which lowers ...200111114160
phzo, a gene for biosynthesis of 2-hydroxylated phenazine compounds in pseudomonas aureofaciens 30-84.certain strains of root-colonizing fluorescent pseudomonas spp. produce phenazines, a class of antifungal metabolites that can provide protection against various soilborne root pathogens. despite the fact that the phenazine biosynthetic locus is highly conserved among fluorescent pseudomonas spp., individual strains differ in the range of phenazine compounds they produce. this study focuses on the ability of pseudomonas aureofaciens 30-84 to produce 2-hydroxyphenazine-1-carboxylic acid (2-oh-pca ...200111114932
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