Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| assembly of xcpr in the cytoplasmic membrane is required for extracellular protein secretion in pseudomonas aeruginosa. | a broad range of extracellular proteins secreted by pseudomonas aeruginosa use the type ii or general secretory pathway (gsp) to reach the medium. this pathway requires the expression of at least 12 xcp gene products. xcpr, a putative nucleotide-binding protein, is essential for the secretion process across the outer membrane even though the protein contains no hydrophobic sequence that could target or anchor it to the bacterial envelope. for a better understanding of the relationship between xc ... | 1999 | 9882649 |
| regulation of hexuronate utilization in bacillus subtilis. | we have identified a locus essential for galacturonate utilization in bacillus subtilis. genes homologous to escherichia coli and erwinia chrysanthemi glucuronate and galacturonate metabolic genes were found in a cluster consisting of 10 open reading frames (orfs) in the b. subtilis chromosome. a mutant of b. subtilis containing a replacement of the second and third orfs was unable to grow with galacturonate as its primary carbon source. galacturonate induced expression from a sigmaa-dependent p ... | 1999 | 9882655 |
| the lysr homolog lrha promotes rpos degradation by modulating activity of the response regulator spre. | synthesis of the ompf porin of escherichia coli is regulated in response to environmental and growth phase signals. in order to identify constituents of the various regulatory pathways involved in modulating ompf transcriptional expression, transposon insertion mutagenesis was performed and mutations that increased ompf'-lacz activity were identified as previously described. mutations mapping to a previously identified gene of unknown function, lrha, were obtained. we found that lrha, a lysr hom ... | 1999 | 9882671 |
| quorum sensing in burkholderia cepacia: identification of the luxri homologs cepri. | burkholderia cepacia has emerged as an important pathogen in patients with cystic fibrosis. many gram-negative pathogens regulate the production of extracellular virulence factors by a cell density-dependent mechanism termed quorum sensing, which involves production of diffusible n-acylated homoserine lactone signal molecules, called autoinducers. transposon insertion mutants of b. cepacia k56-2 which hyperproduced siderophores on chrome azurol s agar were identified. one mutant, k56-r2, contain ... | 1999 | 9922236 |
| thermoregulated expression and characterization of an nad(p)h-dependent 2-cyclohexen-1-one reductase in the plant pathogenic bacterium pseudomonas syringae pv. glycinea. | the phytopathogenic bacterium pseudomonas syringae pv. glycinea pg4180.n9 causes bacterial blight of soybeans and preferably infects its host plant during periods of cold, humid weather conditions. to identify proteins differentially expressed at low temperatures, total cellular protein fractions derived from pg4180.n9 grown at 18 and 28 degreesc were separated by two-dimensional gel electrophoresis. of several proteins which appeared to be preferentially present at 18 degreesc, a 40-kda protein ... | 1999 | 9922244 |
| the minimal gene set member msra, encoding peptide methionine sulfoxide reductase, is a virulence determinant of the plant pathogen erwinia chrysanthemi. | peptide methionine sulfoxide reductase (msra), which repairs oxidized proteins, is present in most living organisms, and the cognate structural gene belongs to the so-called minimum gene set [mushegian, a. r. & koonin, e. v., (1996) proc. natl. acad. sci. usa 93, 10268-10273]. in this work, we report that msra is required for full virulence of the plant pathogen erwinia chrysanthemi. the following differences were observed between the wild-type and a msra- mutant: (i) the msra- mutant was more s ... | 1999 | 9927663 |
| cell-specific production and antimicrobial activity of naphthoquinones in roots of lithospermum erythrorhizon | pigmented naphthoquinone derivatives of shikonin are produced at specific times and in specific cells of lithospermum erythrorhizon roots. normal pigment development is limited to root hairs and root border cells in hairy roots grown on "noninducing" medium, whereas induction of additional pigment production by abiotic (cuso4) or biotic (fungal elicitor) factors increases the amount of total pigment, changes the ratios of derivatives produced, and initiates production of pigment de novo in epide ... | 1999 | 9952436 |
| genetic and transcriptional analyses of the vibrio cholerae mannose-sensitive hemagglutinin type 4 pilus gene locus. | the mannose-sensitive hemagglutinin (msha) of the vibrio cholerae o1 el tor biotype is a member of the family of type 4 pili. type 4 pili are found on the surface of a variety of gram-negative bacteria and have demonstrated importance as host colonization factors, bacteriophage receptors, and mediators of dna transfer. the gene locus required for the assembly and secretion of the msha pilus has been localized to a 16.7-kb region of the v. cholerae chromosome. sixteen genes required for hemagglut ... | 1999 | 9973335 |
| characterization of insertions of is476 and two newly identified insertion sequences, is1478 and is1479, in xanthomonas campestris pv. campestris. | thirty-two plasmid insertion mutants were independently isolated from two strains of xanthomonas campestris pv. campestris in taiwan. of the 32 mutants, 14 (44%), 8 (25%), and 4 (12%) mutants resulted from separate insertions of an is3 family member, is476, and two new insertion sequences (is), is1478 and is1479. while is1478 does not have significant sequence homology with any is elements in the embl/genbank/ddbj database, is1479 demonstrated 73% sequence homology with is1051 in x. campestris p ... | 1999 | 9973349 |
| functional determinants of the escherichia coli fis promoter: roles of -35, -10, and transcription initiation regions in the response to stringent control and growth phase-dependent regulation. | escherichia coli fis is a small dna binding and bending protein that has been implicated in a variety of biological processes. a minimal promoter sequence consisting of 43 bp is sufficient to generate its characteristic growth phase-dependent expression pattern and is also subject to negative regulation by stringent control. however, information about the precise identification of nucleotides contributing to basal promoter activity and its regulation has been scant. in this work, 72 independent ... | 1999 | 9973355 |
| auxins upregulate expression of the indole-3-pyruvate decarboxylase gene in azospirillum brasilense. | transcription of the azospirillum brasilense ipdc gene, encoding an indole-3-pyruvate decarboxylase involved in the biosynthesis of indole-3-acetic acid (iaa), is induced by iaa as determined by ipdc-gusa expression studies and northern analysis. besides iaa, exogenously added synthetic auxins such as 1-naphthaleneacetic acid, 2,4-dichlorophenoxypropionic acid, and p-chlorophenoxyacetic acid were also found to upregulate ipdc expression. no upregulation was observed with tryptophan, acetic acid, ... | 1999 | 9973364 |
| characterization of the exopolygalacturonate lyase pelx of erwinia chrysanthemi 3937. | erwinia chrysanthemi 3937 secretes several pectinolytic enzymes, among which eight isoenzymes of pectate lyases with an endo-cleaving mode (pela, pelb, pelc, peld, pele, peli, pell, and pelz) have been identified. two exo-cleaving enzymes, the exopolygalacturonate lyase, pelx, and an exo-poly-alpha-d-galacturonosidase, pehx, have been previously identified in other e. chrysanthemi strains. using a genomic bank of a 3937 mutant with the major pel genes deleted, we cloned a pectinase gene identifi ... | 1999 | 10049400 |
| inhibition of vibrio anguillarum by pseudomonas fluorescens ah2, a possible probiotic treatment of fish. | to study the possible use of probiotics in fish farming, we evaluated the in vitro and in vivo antagonism of antibacterial strain pseudomonas fluorescens strain ah2 against the fish-pathogenic bacterium vibrio anguillarum. as iron is important in virulence and bacterial interactions, the effect of p. fluorescens ah2 was studied under iron-rich and iron-limited conditions. sterile-filtered culture supernatants from iron-limited p. fluorescens ah2 inhibited the growth of v. anguillarum, whereas st ... | 1999 | 10049849 |
| polynucleotide probes that target a hypervariable region of 16s rrna genes to identify bacterial isolates corresponding to bands of community fingerprints. | temperature gradient gel electrophoresis (tgge) is well suited for fingerprinting bacterial communities by separating pcr-amplified fragments of 16s rrna genes (16s ribosomal dna [rdna]). a strategy was developed and was generally applicable for linking 16s rdna from community fingerprints to pure culture isolates from the same habitat. for this, digoxigenin-labeled polynucleotide probes were generated by pcr, using bands excised from tgge community fingerprints as a template, and applied in hyb ... | 1999 | 10049861 |
| enhanced resistance to bacterial diseases of transgenic tobacco plants overexpressing sarcotoxin ia, a bactericidal peptide of insect. | sarcotoxin ia is a bactericidal peptide of 39 amino acids found in the common flesh fly, sarcophaga peregrina. many agronomically important bacteria in japan are killed by this peptide at sub-micro molar levels, and the growth of tobacco and rice suspension cultured cells is not inhibited with less than 25 microm. transgenic tobacco plants which overexpress the peptide, i.e. over 250 pmol per gram of fresh leaf, under the control of a high expression constitutive promoter showed enhanced resista ... | 1999 | 10050028 |
| surface motility of serratia liquefaciens mg1. | 1999 | 10074060 | |
| identification and cloning of an erwinia carotovora subsp. carotovora bacteriocin regulator gene by insertional mutagenesis. | avirulent erwinia carotovora subsp. carotovora cge234-m403 produces two types of bacteriocin. for the purpose of cloning the bacteriocin genes of strain cge234m403, a spontaneous rifampin-resistant mutant of this strain, m-rif-11-2, was isolated. by tn5 insertional mutagenesis using m-rif-11-2, a mutant, tm01a01, which produces the high-molecular-weight bacteriocin but not the low-molecular-weight bacteriocin was obtained. by thermal asymmetric interlaced pcr, the dna sequence from the tn5 inser ... | 1999 | 10074096 |
| crystallization and preliminary crystallographic analysis of the endo-polygalacturonase from erwinia carotovora ssp. carotovora. | crystals of endo-polygalacturonase from erwinia carotovora ssp. carotovora have been grown from polyethylene glycol 6000 by the hanging-drop method. polygalacturonase is important in the virulence of this plant pathogen. the protein crystallizes in space group c2 with unit-cell parameters a = 81.3, b = 53.0, c = 103.1 a, beta = 112.6 degrees and with a single molecule in the asymmetric unit. the crystals diffract to 1.9 a. | 1999 | 10089438 |
| the major phase-variable outer membrane protein of escherichia coli structurally resembles the immunoglobulin a1 protease class of exported protein and is regulated by a novel mechanism involving dam and oxyr. | here we report the characterization of an escherichia coli gene (agn43) which encodes the principal phase-variable outer membrane protein termed antigen 43 (ag43). the agn43 gene encodes a precursor protein of 107 kda containing a 52-amino-acid signal sequence. posttranslational processing generates an alpha43 subunit (predicted mr of 49,789) and a c-terminal domain (beta43) with features typical of a bacterial integral outer membrane protein (predicted mr of 51, 642). secondary structure analys ... | 1999 | 10094691 |
| rsal, a novel repressor of virulence gene expression in pseudomonas aeruginosa. | as components of a pseudomonas aeruginosa quorum-sensing system, lasr and pai-1 globally regulate expression of multiple virulence determinants, as well as the second p. aeruginosa quorum-sensing system. to date, no information exists on negative regulation of the quorum-sensing cascade in p. aeruginosa. here we describe a novel gene, rsal, which is located downstream from lasr and transcribed antisense relative to lasr. in p. aeruginosa, overexpression of rsal results in reduced lasb expression ... | 1999 | 10094696 |
| kdgrecc negatively regulates genes for pectinases, cellulase, protease, harpinecc, and a global rna regulator in erwinia carotovora subsp. carotovora. | erwinia carotovora subsp. carotovora produces extracellular pectate lyase (pel), polygalacturonase (peh), cellulase (cel), and protease (prt). the concerted actions of these enzymes largely determine the virulence of this plant-pathogenic bacterium. e. carotovora subsp. carotovora also produces harpinecc, the elicitor of the hypersensitive reaction. we document here that kdgrecc (kdg, 2-keto-3-deoxygluconate; kdgr, general repressor of genes involved in pectin and galacturonate catabolism), a ho ... | 1999 | 10198003 |
| azospirillum irakense produces a novel type of pectate lyase. | the pela gene from the n2-fixing plant-associated bacterium azospirillum irakense, encoding a pectate lyase, was isolated by heterologous expression in escherichia coli. nucleotide sequence analysis of the region containing pela indicated an open reading frame of 1,296 bp, coding for a preprotein of 432 amino acids with a typical amino-terminal signal peptide of 24 amino acids. n-terminal amino acid sequencing confirmed the processing of the protein in e. coli at the signal peptidase cleavage si ... | 1999 | 10198006 |
| hypersensitive cell death and papilla formation in barley attacked by the powdery mildew fungus are associated with hydrogen peroxide but not with salicylic acid accumulation | we analyzed the pathogenesis-related generation of h2o2 using the microscopic detection of 3,3-diaminobenzidine polymerization in near-isogenic barley (hordeum vulgare l.) lines carrying different powdery mildew (blumeria graminis f.sp. hordei) resistance genes, and in a line expressing chemically activated resistance after treatment with 2,6-dichloroisonicotinic acid (dcina). hypersensitive cell death in mla12 and mlg genotypes or after chemical activation by dcina was associated with h2o2 accu ... | 1999 | 10198083 |
| characterization of two novel type i ribosome-inactivating proteins from the storage roots of the andean crop mirabilis expansa. | two novel type i ribosome-inactivating proteins (rips) were found in the storage roots of mirabilis expansa, an underutilized andean root crop. the two rips, named me1 and me2, were purified to homogeneity by ammonium sulfate precipitation, cation-exchange perfusion chromatography, and c4 reverse-phase chromatography. the two proteins were found to be similar in size (27 and 27.5 kd) by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and their isoelectric points were determined to be ... | 1999 | 10198104 |
| sequence analysis of the gyra and parc homologues of a wild-type strain of vibrio parahaemolyticus and its fluoroquinolone-resistant mutants. | vibrio parahaemolyticus causes seafood-borne gastroenteritis in humans. it is particularly important in japan, where raw seafood is frequently consumed. fluoroquinolone is one of the current drugs of choice for treating patients infected by v. parahaemolyticus because resistant strains are rarely found. to study a possible fluoroquinolone resistance mechanism in this organism, nucleotide sequences that are homologous to known gyra and parc genes have been cloned from v. parahaemolyticus aq3815 a ... | 1999 | 10223929 |
| direct interaction of the epsl and epsm proteins of the general secretion apparatus in vibrio cholerae. | the general secretion pathway of gram-negative bacteria is responsible for extracellular secretion of a number of different proteins, including proteases and toxins. this pathway supports secretion of proteins across the cell envelope in two distinct steps, in which the second step, involving translocation through the outer membrane, is assisted by at least 13 different gene products. two of these components, the cytoplasmic membrane proteins epsl and epsm of vibrio cholerae, have been purified ... | 1999 | 10322014 |
| saccharomyces cerevisiae cells harboring the gene encoding sarcotoxin ia secrete a peptide that is toxic to plant pathogenic bacteria. | sarcotoxin ia is a cecropin-type antibacterial protein produced by the flesh fly, sarcophaga peregrina. similar to other bactericidal small proteins produced by insects, sarcotoxin ia is released into the hemolymph of larvae and nymphs upon mechanical injury or bacterial infection. the gene (sarco) that encodes this toxin was introduced into saccharomyces cerevisiae yeast cells and was expressed under a constitutive yeast promoter. the transformed yeast cells were grown in a liquid medium, and a ... | 1999 | 10336869 |
| enhancement of expression and apparent secretion of erwinia chrysanthemi endoglucanase (encoded by celz) in escherichia coli b. | escherichia coli b has been engineered as a biocatalyst for the conversion of lignocellulose into ethanol. previous research has demonstrated that derivatives of e. coli b can produce high levels of erwinia chrysanthemi endoglucanase (encoded by celz) as a periplasmic product and that this enzyme can function with commercial fungal cellulase to increase ethanol production. in this study, we have demonstrated two methods that improve celz expression in e. coli b. initially, with a low-copy-number ... | 1999 | 10347024 |
| a pyruvated mannose-specific xanthan lyase involved in xanthan degradation by paenibacillus alginolyticus xl-1. | the xanthan-degrading bacterium paenibacillus alginolyticus xl-1, isolated from soil, degrades approximately 28% of the xanthan molecule and appears to leave the backbone intact. several xanthan-degrading enzymes were excreted during growth on xanthan, including xanthan lyase. xanthan lyase production was induced by xanthan and inhibited by glucose and low-molecular-weight enzymatic degradation products from xanthan. a xanthan lyase with a molecular mass of 85 kda and a pi of 7.9 was purified an ... | 1999 | 10347025 |
| characterization and nucleotide sequence of a klebsiella oxytoca cryptic plasmid encoding a cmy-type beta-lactamase: confirmation that the plasmid-mediated cephamycinase originated from the citrobacter freundii ampc beta-lactamase. | plasmid ptkh11, originally obtained by electroporation of a klebsiella oxytoca plasmid preparation into escherichia coli xac, expressed a high level of an ampc-like beta-lactamase. the enzyme, designated cmy-5, conferred resistance to extended-spectrum beta-lactams in e. coli; nevertheless, the phenotype was cryptic in the k. oxytoca donor. determination of the complete nucleotide sequence of ptkh11 revealed that the 8,193-bp plasmid encoded seven open reading frames, including that for the cmy- ... | 1999 | 10348751 |
| mutation in a gene required for lipopolysaccharide and enterobacterial common antigen biosynthesis affects virulence in the plant pathogen erwinia carotovora subsp. atroseptica. | spontaneous bacteriophage-resistant mutants of the phytopathogen erwinia carotovora subsp. atroseptica (eca) scri1043 were isolated and, out of 40, two were found to exhibit reduced virulence in planta. one of these mutants, a5/22, showed multiple cell surface defects including alterations in synthesis of outer membrane proteins, lipopolysaccharide (lps), enterobacterial common antigen (eca), and flagella. mutant a5/22 also showed reduced synthesis of the exoenzymes pectate lyase (pel) and cellu ... | 1999 | 10356801 |
| analysis of quorum-sensing-dependent control of rhizosphere-expressed (rhi) genes in rhizobium leguminosarum bv. viciae. | the rhi genes of rhizobium leguminosarum biovar viciae are expressed in the rhizosphere and play a role in the interaction with legumes, such as the pea. previously (k. m. gray, j. p. pearson, j. a. downie, b. e. a. boboye, and e. p. greenberg, j. bacteriol. 178:372-376, 1996) the rhiabc operon had been shown to be regulated by rhir and to be induced by added n-(3-hydroxy-7-cis-tetradecenoyl)-l-homoserine lactone (3oh, c14:1-hsl). mutagenesis of a cosmid carrying the rhiabc and rhir gene region ... | 1999 | 10368158 |
| the exopolygalacturonate lyase pelw and the oligogalacturonate lyase ogl, two cytoplasmic enzymes of pectin catabolism in erwinia chrysanthemi 3937. | erwinia chrysanthemi 3937 secretes into the external medium several pectinolytic enzymes, among which are eight isoenzymes of the endo-cleaving pectate lyases: pela, pelb, pelc, peld, and pele (family 1); peli (family 4); pell (family 3); and pelz (family 5). in addition, one exo-cleaving pectate lyase, pelx (family 3), has been found in the periplasm of e. chrysanthemi. the e. chrysanthemi 3937 gene kdgc has been shown to exhibit a high degree of similarity to the genes pely of yersinia pseudot ... | 1999 | 10383957 |
| membrane association and multimerization of secreton component pulc. | the pulc component of the klebsiella oxytoca pullulanase secretion machinery (the secreton) was found by subcellular fractionation to be associated with both the cytoplasmic (inner) and outer membranes. association with the outer membrane was independent of other secreton components, including the outer membrane protein puld (secretin). the association of pulc with the inner membrane is mediated by the signal anchor sequence located close to its n terminus. these results suggest that pulc forms ... | 1999 | 10383968 |
| structure-function analysis of xcpp, a component involved in general secretory pathway-dependent protein secretion in pseudomonas aeruginosa. | the general secretory pathway of pseudomonas aeruginosa is required for the transport of signal peptide-containing exoproteins across the cell envelope. after completion of the sec-dependent translocation of exoproteins across the inner membrane and cleavage of the signal peptide, the xcp machinery mediates translocation across the outer membrane. this machinery consists of 12 components, of which xcpq (gspd) is the sole outer membrane protein. xcpq forms a multimeric ring-shaped structure, with ... | 1999 | 10383969 |
| swarming by pseudomonas syringae b728a requires gacs (lema) and gaca but not the acyl-homoserine lactone biosynthetic gene ahli. | pseudomonas syringae pv. syringae b728a, a causal agent of bacterial brown spot on snap beans, swarms with a characteristic dendritic pattern on semisolid (0.4%) agar plates. filamentation of swarming cells of b728a was not observed. mutations in either the gacs (formerly lema) or gaca gene of b728a eliminate the ability of this p. syringae isolate to swarm without obvious effects on bacterial motility. three field isolates showed a similar dependence on gacs for swarming. since gacs and gaca mu ... | 1999 | 10383988 |
| purification and characterization of an alpha-glucosidase from rhizobium sp. (robinia pseudoacacia l.) strain usda 4280. | a novel alpha-glucosidase with an apparent subunit mass of 59 +/- 0. 5 kda was purified from protein extracts of rhizobium sp. strain usda 4280, a nodulating strain of black locust (robinia pseudoacacia l), and characterized. after purification to homogeneity (475-fold; yield, 18%) by ammonium sulfate precipitation, cation-exchange chromatography, hydrophobic chromatography, dye chromatography, and gel filtration, this enzyme had a pi of 4.75 +/- 0.05. the enzyme activity was optimal at ph 6.0 t ... | 1999 | 10388682 |
| the genes ruba and rubb for alkane degradation in acinetobacter sp. strain adp1 are in an operon with estb, encoding an esterase, and oxyr. | alkanes are oxidized in acinetobacter sp. strain adp1 by a three-component alkane monooxygenase, composed of alkane hydroxylase, rubredoxin, and rubredoxin reductase. ruba and rubb encode rubredoxin and a nad(p)h-dependent rubredoxin reductase. we demonstrate here that single base pair substitutions in ruba or rubb lead to defects in alkane degradation, showing that both genes are essential for alkane utilization. differences in the degradation capacity for hexadecane and dodecane in these mutan ... | 1999 | 10400587 |
| influence of soft rot bacteria on growth of listeria monocytogenes on potato tuber slices. | growth of listeria monocytogenes on potato tuber slices and its interaction with four representative species of soft rot bacteria (pseudomonas fluorescens, p. viridiflava, erwinia carotovora subsp. carotovora, and xanthomonas campestris) were investigated. when potato tuber slices were inoculated with one of two l. monocytogenes strains (scott a and atcc 15313), an increase in numbers of 3 to 4 logs per gram of tissue was observed with samples that were stored at 20 degrees c for 6 days. however ... | 1999 | 10419206 |
| purification of catechol siderophores by boronate affinity chromatography: identification of chrysobactin from erwinia carotovora subsp. carotovora. | catechols are co-planar cis-diols known to form stable, isolable complexes with borate under weakly basic conditions. we exploited this chemistry and developed a boronate affinity chromatography for isolating catechol siderophores. the method was applied to the isolation of chrysobactin, enterobactin, and an unknown catechol siderophore produce by erwinia carotovora subsp. carotovora w3c105. yields of chrysobactin and enterobactin purified by boronate affinity chromatography were at least two-fo ... | 1999 | 10420578 |
| molecular genetics of carbapenem antibiotic biosynthesis. | carbapenems are potent beta-lactam antibiotics with a broad spectrum of activity against both gram positive and gram negative bacteria. as naturally produced metabolites, they have been isolated from species of streptomyces, erwinia and serratia. the latter two members of the enterobacteriaceae have proved to be genetically amenable and a growing body of research on these organisms now exists concerning the genes responsible for carbapenem biosynthesis and the regulatory mechanisms controlling t ... | 1999 | 10422586 |
| erwinia carotovora has two kdgr-like proteins belonging to the icir family of transcriptional regulators: identification and characterization of the rexz activator and the kdgr repressor of pathogenesis. | a novel erwinia carotovora subsp. carotovora mutant designated rexz, (regulator of exoenzymes) showed reduced production of the degradative exoenzymes. the rexz gene product shows similarity of the kdgr regulatory protein from erwinia chrysanthemi, described as the major repressor of the pectin catabolism pathway genes in the latter species. in vitro dna-protein interaction experiments demonstrated that the synthesis of the rexz protein is controlled by the camp-crp (camp-receptor protein) compl ... | 1999 | 10439393 |
| leucine aminopeptidase rnas, proteins, and activities increase in response to water deficit, salinity, and the wound signals systemin, methyl jasmonate, and abscisic acid | lapa rnas, proteins, and activities increased in response to systemin, methyl jasmonate, abscisic acid (aba), ethylene, water deficit, and salinity in tomato (lycopersicon esculentum). salicylic acid inhibited wound-induced increases of lapa rnas. experiments using the aba-deficient flacca mutant indicated that aba was essential for wound and systemin induction of lapa, and aba and systemin acted synergistically to induce lapa gene expression. in contrast, pin2 (proteinase inhibitor 2) was not d ... | 1999 | 10444081 |
| erwinia carotovora dsba mutants: evidence for a periplasmic-stress signal transduction system affecting transcription of genes encoding secreted proteins. | the dsba genes, which encode major periplasmic disulfide-bond-forming proteins, were isolated from erwinia carotovora subsp. carotovora (ecc) and erwinia carotovora subsp. atroseptica (eca), and the dsbc gene, encoding another periplasmic disulfide oxidoreductase was isolated from ecc. all three genes were sequenced and mutants deficient in these genes were created by marker exchange mutagenesis. the ecc mutants were severely affected in activity and secretion of pectate lyase, probably due to t ... | 1999 | 10463161 |
| isolation of an extracellular protease gene of erwinia carotovora subsp. carotovora strain scc3193 by transposon mutagenesis and the role of protease in phytopathogenicity. | using mini-tn5cmr::gusa, a transposon that allows transcriptional fusions to a promoterless beta-glucuronidase gene, a mutant of erwinia carotovora subsp. carotovora scc3193 deficient in extracellular protease production and soft-rot pathogenicity in plants was isolated. the mutant, designated scc6004, produced normal levels of pectate lyase, polygalacturonase and cellulase. the region of the transposon insertion was partially sequenced to permit the design of specific oligonucleotide primers to ... | 1999 | 10463162 |
| a simplified subtractive hybridization protocol used to isolate dna sequences specific to xylella fastidiosa. | a simplified protocol of subtractive hybridization based on the technique of l. m. kunkel, a. p. monaco, w. middlesworth, h. d. ochs & s. a. latt (1985, proc natl acad sci usa, 82, 4778-4782) was used to obtain dna sequences specific to xylella fastidiosa isolated from diseased citrus plants. as a driver, dna extracted from bacteria showing different degrees of relatedness was used: xy. fastidiosa 788 isolated from another host (plum), xanthomonas campestris pv. campestris and burkholderia gladi ... | 1999 | 10463163 |
| development and application of pathovar-specific monoclonal antibodies that recognize the lipopolysaccharide o antigen and the type iv fimbriae of xanthomonas hyacinthi. | the objective of this study was to develop a specific immunological diagnostic assay for yellow disease in hyacinths, using monoclonal antibodies (mabs). mice were immunized with a crude cell wall preparation (shear fraction) from xanthomonas hyacinthi and with purified type iv fimbriae. hybridomas were screened for a positive reaction with x. hyacinthi cells or fimbriae and for a negative reaction with x. translucens pv. graminis or erwinia carotovora subsp. carotovora. nine mabs recognized fim ... | 1999 | 10473431 |
| efficacy of electrolyzed oxidizing water for inactivating escherichia coli o157:h7, salmonella enteritidis, and listeria monocytogenes. | the efficacy of electrolyzed oxidizing water for inactivating escherichia coli o157:h7, salmonella enteritidis, and listeria monocytogenes was evaluated. a five-strain mixture of e. coli o157:h7, s. enteritidis, or l. monocytogenes of approximately 10(8) cfu/ml was inoculated in 9 ml of electrolyzed oxidizing water (treatment) or 9 ml of sterile, deionized water (control) and incubated at 4 or 23 degrees c for 0, 5, 10, and 15 min; at 35 degrees c for 0, 2, 4, and 6 min; or at 45 degrees c for 0 ... | 1999 | 10473453 |
| the response regulator expm is essential for the virulence of erwinia carotovora subsp. carotovora and acts negatively on the sigma factor rpos (sigma s). | the main virulence factors of erwinia carotovora subsp. carotovora, the secreted, extracellular cell-wall-degrading enzymes, are controlled by several regulatory mechanisms. we have isolated transposon mutants with reduced virulence on tobacco. one of these mutants, with a mutation in a gene designated expm, was characterized in this study. this mutant produces slightly reduced amounts of extracellular enzymes in vitro and the secretion of the enzymes is also affected. the expm wild-type allele ... | 1999 | 10478478 |
| oligogalacturonide-mediated induction of a gene involved in jasmonic acid synthesis in response to the cell-wall-degrading enzymes of the plant pathogen erwinia carotovora. | identification of arabidopsis thaliana genes responsive to plant cell-wall-degrading enzymes of erwinia carotovora subsp. carotovora led to the isolation of a cdna clone with high sequence homology to the gene for allene oxide synthase, an enzyme involved in the biosynthesis of jasmonates. expression of the corresponding gene was induced by the extracellular enzymes from this pathogen as well as by treatment with methyl jasmonate and short oligogalacturonides (ogas). this suggests that ogas are ... | 1999 | 10478482 |
| pseudomonas aeruginosa quorum-sensing signal molecule n-(3-oxododecanoyl)-l-homoserine lactone inhibits expression of p2y receptors in cystic fibrosis tracheal gland cells. | atp and utp have been proposed for use as therapeutic treatment of the abnormal ion transport in the airway epithelium in cystic fibrosis (cf), the most characteristic feature of which is permanent infection by pseudomonas aeruginosa. as for diverse gram-negative bacteria, this pathogenic bacterium accumulates diffusible n-acylhomoserine lactone (ahl) signal molecules, and when a threshold concentration is reached, virulence factor genes are activated. human submucosal tracheal gland serous (htg ... | 1999 | 10496880 |
| quorum sensing-dependent regulation and blockade of exoprotease production in aeromonas hydrophila. | in aeromonas hydrophila, the ahyi gene encodes a protein responsible for the synthesis of the quorum sensing signal n-butanoyl-l-homoserine lactone (c4-hsl). inactivation of the ahyi gene on the a. hydrophila chromosome abolishes c4-hsl production. the exoprotease activity of a. hydrophila consists of both serine protease and metalloprotease activities; in the ahyi-negative strain, both are substantially reduced but can be restored by the addition of exogenous c4-hsl. in contrast, mutation of th ... | 1999 | 10496895 |
| rsmc of the soft-rotting bacterium erwinia carotovora subsp. carotovora negatively controls extracellular enzyme and harpin(ecc) production and virulence by modulating levels of regulatory rna (rsmb) and rna-binding protein (rsma). | previous studies have shown that the production of extracellular enzymes (pectate lyase [pel], polygalacturonase [peh], cellulase [cel], and protease [prt]) and harpin(ecc) (the elicitor of hypersensitive reaction) in erwinia carotovora subsp. carotovora is regulated by rsma, an rna-binding protein, and rsmb, a regulatory rna (rsm stands for regulator of secondary metabolites) (y. liu et al., mol. microbiol. 29:219-234, 1998). we have cloned and characterized a novel regulatory gene, rsmc, that ... | 1999 | 10498717 |
| a simple purification method and morphology and component analyses for carotovoricin er, a phage-tail-like bacteriocin from the plant pathogen erwinia carotovora er. | carotovoricin er has been isolated as a phage-tail-like bacteriocin from the plant pathogen erwinia carotovora er [kamimiya, s. et al., (1977), agric. biol. chem. 41, 911-912]. however, the fine morphology and structural composition of carotovoricin er remained to be studied because a large amount of contracted carotovoricin er were present in the bacteriocin preparations so far obtained. to obtain intact carotovoricin er and its major parts, we developed simple and efficient purification method ... | 1999 | 10500998 |
| plants genetically modified to produce n-acylhomoserine lactones communicate with bacteria. | n-acylhomoserine lactones (ahls) play a critical role in plant/microbe interactions. the ahl, n-(3-oxohexanoyl)-l-homoserine lactone (ohhl), induces exoenzymes that degrade the plant cell wall by the pathogenic bacterium erwinia carotovora. conversely, the antifungal activity of the biocontrol bacterium pseudomonas aureofaciens 30-84 is due (at least in part) to phenazine antibiotics whose synthesis is regulated by n-hexanoylhomoserine lactone (hhl). targeting the product of an ahl synthase gene ... | 1999 | 10504705 |
| identification and characterization of come and comf, two novel pilin-like competence factors involved in natural transformation of acinetobacter sp. strain bd413. | although the high level of competence for natural transformation of acinetobacter sp. strain bd413 has been the subject of numerous studies, only two competence genes, comc and comp, have been identified to date. by chromosomal walking analysis we found two overlapping open reading frames, designated come and comf, starting 61 bp downstream of comc. come and comf are expressed as stable proteins in escherichia coli, thus proving that they are indeed coding regions, but expression was successful ... | 1999 | 10508090 |
| genotypic and phenotypic relationships between clinical and environmental isolates of stenotrophomonas maltophilia. | while the gram-negative bacterium stenotrophomonas maltophilia is used in biotechnology (e.g., for biological control of plant pathogens and for bioremediation), the number of s. maltophilia diseases in humans has dramatically increased in recent years. a total of 40 s. maltophilia isolates from clinical and environmental sources (plant associated and water) was investigated to determine the intraspecies diversity of the group and to determine whether or not the strains could be grouped based on ... | 1999 | 10523559 |
| the site-specific integration of genetic elements may modulate thermostable protease production, a virulence factor in dichelobacter nodosus, the causative agent of ovine footrot. | the gram-negative anaerobe dichelobacter nodosus is the causative agent of footrot in sheep. the authors have previously characterized two genetic elements, the inta (vap) and intb elements, which integrate into the genome of d. nodosus. in the virulent strain a198 there are two copies of the inta element. one copy is integrated into the 3' end of the trna-sergcu gene, close to the aspartokinase (aska) gene, and the second copy is integrated into the 3' end of the trna-sergga gene, next to the p ... | 1999 | 10537206 |
| a novel cellulosomal scaffoldin from acetivibrio cellulolyticus that contains a family 9 glycosyl hydrolase. | a novel cellulosomal scaffoldin gene, termed cipv, was identified and sequenced from the mesophilic cellulolytic anaerobe acetivibrio cellulolyticus. initial identification of the protein was based on a combination of properties, including its high molecular weight, cellulose-binding activity, glycoprotein nature, and immuno-cross-reactivity with the cellulosomal scaffoldin of clostridium thermocellum. the cipv gene is 5,748 bp in length and encodes a 1,915-residue polypeptide with a calculated ... | 1999 | 10542174 |
| the plant-growth-promoting rhizobacterium paenibacillus polymyxa induces changes in arabidopsis thaliana gene expression: a possible connection between biotic and abiotic stress responses. | this paper addresses changes in plant gene expression induced by inoculation with plant-growth-promoting rhizobacteria (pgpr). a gnotobiotic system was established with arabidopsis thaliana as model plant, and isolates of paenibacillus polymyxa as pgpr. subsequent challenge by either the pathogen erwinia carotovora (biotic stress) or induction of drought (abiotic stress) indicated that inoculated plants were more resistant than control plants. with rna differential display on parallel rna prepar ... | 1999 | 10550893 |
| the pseudomonas aeruginosa quorum-sensing signal molecule, n-(3-oxododecanoyl)-l-homoserine lactone, inhibits porcine arterial smooth muscle contraction. | the pseudomonas aeruginosa quorum sensing molecule n-(3-oxododecanoyl)-l-homoserine lactone (oddhl) has been shown to suppress cytokine production in macrophages. we have examined the effect of oddhl and related compounds on constrictor tone of porcine blood vessels. oddhl (1-30 microm) caused a concentration-dependent inhibition of u46619-induced contractions of the coronary artery through a largely endothelium-independent mechanism, but was markedly less effective in the pulmonary artery. quan ... | 1999 | 10556916 |
| global gaca-steered control of cyanide and exoprotease production in pseudomonas fluorescens involves specific ribosome binding sites. | the conserved two-component regulatory system gacs/gaca determines the expression of extracellular products and virulence factors in a variety of gram-negative bacteria. in the biocontrol strain cha0 of pseudomonas fluorescens, the response regulator gaca is essential for the synthesis of extracellular protease (apra) and secondary metabolites including hydrogen cyanide. gaca was found to exert its control on the hydrogen cyanide biosynthetic genes (hcnabc) and on the apra gene indirectly via a ... | 1999 | 10570200 |
| providencia stuartii genes activated by cell-to-cell signaling and identification of a gene required for production or activity of an extracellular factor. | by utilizing reporter transposons, five providencia stuartii genes that are activated by the accumulation of self-produced extracellular signals have been identified. these genes have been designated cma for conditioned medium activated. the presence of conditioned medium from stationary-phase cultures grown in rich media resulted in the premature activation of each gene in cells at early log phase, with activation values ranging from 6- to 26-fold. preparation of conditioned medium from an m9 s ... | 1999 | 10572119 |
| genetic dissection of the outer membrane secretin puld: are there distinct domains for multimerization and secretion specificity? | linker and deletion mutagenesis and gene fusions were used to probe the possible domain structure of the dodecameric outer membrane secretin puld from the pullulanase secretion pathway of klebsiella oxytoca. insertions of 24 amino acids close to or within strongly predicted and highly conserved amphipathic beta strands in the c-terminal half of the polypeptide (the beta domain) abolished sodium dodecyl sulfate (sds)-resistant multimer formation that is characteristic of this protein, whereas ins ... | 1999 | 10572123 |
| evaluation of phenotypic and molecular typing techniques for determining diversity in erwinia carotovora subspp. atroseptica. | a number of phenotypic and molecular fingerprinting techniques, including physiological profiling (biolog), restriction fragment length polymorphism (rflp), enterobacterial repetitive intergenic consensus (eric) and a phage typing system, were evaluated for their ability to differentiate between 60 strains of erwinia carotovora ssp. atroseptica (eca) from eight west european countries. these techniques were compared with other fingerprinting techniques, random amplified polymorphic dna (rapd) an ... | 1999 | 10594720 |
| role of rpos in virulence and stress tolerance of the plant pathogen erwinia carotovora subsp. carotovora. | the plant-pathogenic bacterium erwinia carotovora subsp. carotovora causes plant disease mainly through a number of extracellular plant-cell-wall-degrading enzymes. in this study, the ability of an rpos mutant of the er. carotovora subsp. carotovora strain scc3193 to infect plants and withstand environmental stress was characterized. this mutant was found to be sensitive to osmotic and oxidative stresses in vitro and to be deficient in glycogen accumulation. the production of extracellular enzym ... | 1999 | 10627052 |
| the hexy genes of erwinia carotovora ssp. carotovora and ssp. atroseptica encode novel proteins that regulate virulence and motility co-ordinately. | mutations located in a new gene, hexy, in erwinia carotovora ssp. carotovora (ecc) and ssp. atroseptica (eca) cause strong upregulation of production of exoenzyme virulence factors and motility. the hexy gene encodes a novel 14.4 kda protein with no known homologues. the hexy mrna transcript has an unusually long (525bp) 5' untranslated region, which may be important for post-transcriptional regulation. an elevated level of transcription of two exoenzyme genes, pelcand celv, was observed in the ... | 1999 | 11207775 |
| carbonic anhydrase is an ancient enzyme widespread in prokaryotes. | carbonic anhydrases catalyze the reversible hydration of co(2) and are ubiquitous in highly evolved eukaryotes. the recent identification of a third class of carbonic anhydrase (gamma class) in a methanoarchaeon and our present finding that the beta class also extends into thermophilic species from the archaea domain led us to initiate a systematic search for these enzymes in metabolically and phylogenetically diverse prokaryotes. here we show that carbonic anhydrase is widespread in the archaea ... | 1999 | 10611359 |
| production of acylated homoserine lactones by psychrotrophic members of the enterobacteriaceae isolated from foods. | bacteria are able to communicate and gene regulation can be mediated through the production of acylated homoserine lactone (ahl) signal molecules. these signals play important roles in several pathogenic and symbiotic bacteria. the following study was undertaken to investigate whether ahls are produced by bacteria found in food at temperatures and nacl conditions commercially used for food preservation and storage. a minimum of 116 of 154 psychrotrophic enterobacteriaceae strains isolated from c ... | 1999 | 10427034 |
| bacterial quorum sensing in pathogenic relationships. | 2000 | 10948095 | |
| bacterial growth stimulation with exogenous siderophore and synthetic n-acyl homoserine lactone autoinducers under iron-limited and low-nutrient conditions. | the growth of marine bacteria under iron-limited conditions was investigated. neither siderophore production nor bacterial growth was detected for pelagiobacter sp. strain v0110 when fe(iii) was present in the culture medium at a concentration of <1.0 microm. however, the growth of v0110 was strongly stimulated by the presence of trace amounts of exogenous siderophore from an alpha proteobacterium, v0902, and 1 nm n-acyl-octanoylhomoserine lactone (c(8)-hsl), which is known as a quorum-sensing c ... | 2000 | 10877770 |
| how novel methods can help discover more information about foodborne pathogens. | considerable emphasis is being placed on quantitative risk assessment modelling as a basis for regulation of trade in food products. however, for models to be accurate, information about the behaviour of potential pathogens in foods needs to be available. the question is how to obtain this knowledge in a simple and cost effective way. one technique that has great potential is the use of reporter bacteria which have been genetically modified to express a phenotype that can be easily monitored, su ... | 2000 | 18159282 |
| the drosophila caspase dredd is required to resist gram-negative bacterial infection. | the drosophila innate immune system discriminates between pathogens and responds by inducing the expression of specific antimicrobial peptide-encoding genes through distinct signaling cascades. fungal infection activates nf-kappab-like transcription factors via the toll pathway, which also regulates innate immune responses in mammals. the pathways that mediate antibacterial defenses, however, are less defined. we have isolated loss-of-function mutations in the caspase encoding gene dredd, which ... | 2000 | 11269502 |
| [characteristics of bacterial lipopolysaccharides depending on extraction method]. | carbohydrate-containing biopolymers have been isolated from erwinia carotovora subsp. atroseptica 549 by two methods--the aqueous-phenol and with using physiological solution--with addition and without addition of ethylenediaminetetraacetate (edta). the biopolymers yield from the cells of bacteria are shown to depend on the extraction method. lipopolysaccharide-protein complex have been isolated by the sparing method. the purest lipopolysaccharide have been isolated by the aqueousphenol method. ... | 2000 | 11392785 |
| hexa of erwinia carotovora ssp. carotovora strain ecc71 negatively regulates production of rpos and rsmb rna, a global regulator of extracellular proteins, plant virulence and the quorum-sensing signal, n-(3-oxohexanoyl)-l-homoserine lactone. | the soft-rotting bacterium, erwinia carotovora ssp. carotovora (e. c. carotovora), produces an array of extracellular enzymes (= exoenzymes), including pectate lyase (pel), polygalacturonase (peh), cellulase (cel) and protease (prt), as well as harpinecc, the elicitor of hypersensitive reaction (hr). the production of these exoenzymes and harpinecc responds to plant products and the quorum-sensing signal [n-(3-oxohexanoyl)-l-homoserine lactone; ohl] and is subject to both transcriptional and pos ... | 2000 | 11220306 |
| attachment of escherichia coli o157:h7 to the surfaces and internal structures of apples as detected by confocal scanning laser microscopy. | confocal scanning laser microscopy (cslm) was used to demonstrate the attachment of escherichia coli o157:h7 transformed with a plasmid encoding for green fluorescent protein (gfp) to the surface and within the internal structures of nonwaxed red delicious cv. apples. apples at 2 or 25 degrees c were inoculated with an e. coli o157:h7 cell suspension at 2 or 25 degrees c. the effect of a negative temperature differential (cold inoculum, warm apple), a positive differential (warm inoculum, cold a ... | 2000 | 11055910 |
| two regions of epsl involved in species-specific protein-protein interactions with epse and epsm of the general secretion pathway in vibrio cholerae. | extracellular secretion of proteins via the type ii or general secretion pathway in gram-negative bacteria requires the assistance of at least 12 gene products that are thought to form a complex apparatus through which secreted proteins are translocated. although this apparatus is specifically required only for the outer membrane translocation step during transport across the bacterial cell envelope, it is believed to span both membranes. the epse, epsl, and epsm proteins of the type ii apparatu ... | 2000 | 10633109 |
| an unusual pectate lyase from a bacillus sp. with high activity on pectin: cloning and characterization. | the gene pela encoding a pectate lyase from the strain bacillus sp. bp-23 was cloned and expressed in escherichia coli. the nucleotide sequence of a 1214 bp dna fragment containing pela gene was determined, revealing an orf of 666 nucleotides that encoded a protein of 23233 da. the deduced amino acid sequence of the encoded enzyme showed homology to pectate lyases a, b, c and d from fusarium solani, pel-3 and pelb from erwinia carotovora and pell from erwinia chrysanthemi. homology was also foun ... | 2000 | 10658655 |
| cdna-aflp analysis of differential gene expression in the prokaryotic plant pathogen erwinia carotovora. | for studies of differential gene expression in prokaryotes, methods for synthesizing representative cdna populations are required. here, a technique is described for the synthesis of cdna from the potato pathogens erwinia carotovora subsp. atroseptica (eca) and erwinia carotovora subsp. carotovora (ecc) using a combination of short oligonucleotide (11-mer) primers that were known to anneal to conserved sequences in the 3' regions of enterobacterial genes. specific pcr amplifications with primers ... | 2000 | 10658663 |
| autoinduction of 2,4-diacetylphloroglucinol biosynthesis in the biocontrol agent pseudomonas fluorescens cha0 and repression by the bacterial metabolites salicylate and pyoluteorin. | the antimicrobial metabolite 2,4-diacetylphloroglucinol (2,4-dapg) contributes to the capacity of pseudomonas fluorescens strain cha0 to control plant diseases caused by soilborne pathogens. a 2, 4-dapg-negative tn5 insertion mutant of strain cha0 was isolated, and the nucleotide sequence of the 4-kb genomic dna region adjacent to the tn5 insertion site was determined. four open reading frames were identified, two of which were homologous to phla, the first gene of the 2,4-dapg biosynthetic oper ... | 2000 | 10671440 |
| characterization of sota and sotb, two erwinia chrysanthemi proteins which modify isopropyl-beta-d-thiogalactopyranoside and lactose induction of the escherichia coli lac promoter. | the expression, in escherichia coli, of variants of the erwinia chrysanthemi secretion genes outb and outs under the ptac promoter is toxic to the cells. during attempts to clone e. chrysanthemi genes able to suppress this toxicity, i identified two genes, sota and sotb, whose products are able to reduce the isopropyl-beta-d-thiogalactopyranoside (iptg) induction of the e. coli lac promoter. sota and sotb belong to two different families of the major facilitator superfamily. sota is a member of ... | 2000 | 10671456 |
| n-acyl homoserine lactone binding to the carr receptor determines quorum-sensing specificity in erwinia. | quorum sensing via an n-acyl homoserine lactone (hsl) pheromone controls the biosynthesis of a carbapenem antibiotic in erwinia carotovora. transcription of the carbapenem biosynthetic genes is dependent on the luxr-type activator protein, carr. equilibrium binding of a range of hsl molecules, which are thought to activate carr to bind to its dna target sequence, was examined using fluorescence quenching, dna bandshift analysis, limited proteolysis and reporter gene assays. carr bound the most p ... | 2000 | 10675332 |
| association of the cytoplasmic membrane protein xpsn with the outer membrane protein xpsd in the type ii protein secretion apparatus of xanthomonas campestris pv. campestris. | an xps gene cluster composed of 11 open reading frames is required for the type ii protein secretion in xanthomonas campestris pv. campestris. immediately upstream of the xpsd gene, which encodes an outer membrane protein that serves as the secretion channel by forming multimers, there exists an open reading frame (previously designated orf2) that could encode a protein of 261 amino acid residues. its n-terminal hydrophobic region is a likely membrane-anchoring sequence. antibody raised against ... | 2000 | 10692359 |
| ssra (tmrna) plays a role in salmonella enterica serovar typhimurium pathogenesis. | escherichia coli ssra encodes a small stable rna molecule, tmrna, that has many diverse functions, including tagging abnormal proteins for degradation, supporting phage growth, and modulating the activity of dna binding proteins. here we show that ssra plays a role in salmonella enterica serovar typhimurium pathogenesis and in the expression of several genes known to be induced during infection. moreover, the phage-like attachment site, attl, encoded within ssra, serves as the site of integratio ... | 2000 | 10692360 |
| evolution of arginine biosynthesis in the bacterial domain: novel gene-enzyme relationships from psychrophilic moritella strains (vibrionaceae) and evolutionary significance of n-alpha-acetyl ornithinase. | in the arginine biosynthetic pathway of the vast majority of prokaryotes, the formation of ornithine is catalyzed by an enzyme transferring the acetyl group of n-alpha-acetylornithine to glutamate (ornithine acetyltransferase [oatase]) (argj encoded). only two exceptions had been reported-the enterobacteriaceae and myxococcus xanthus (members of the gamma and delta groups of the class proteobacteria, respectively)-in which ornithine is produced from n-alpha-acetylornithine by a deacylase, acetyl ... | 2000 | 10692366 |
| aiia, an enzyme that inactivates the acylhomoserine lactone quorum-sensing signal and attenuates the virulence of erwinia carotovora. | n-acylhomoserine lactones, known as autoinducers (ais), are widely conserved signal molecules present in quorum-sensing systems of many gram-negative bacteria. ais are involved in the regulation of diverse biological functions, including expression of pathogenic genes in the plant pathogens pseudomonas solanacearum, several erwinia species, and the human pathogen pseudomonas aeruginosa. a bacterial isolate, bacillus sp. 240b1, is capable of enzymatic inactivation of ais. the gene (aiia) for ai i ... | 2000 | 10716724 |
| mutations in the extracellular protein secretion pathway genes (eps) interfere with rugose polysaccharide production in and motility of vibrio cholerae. | vibrio cholerae is the causal organism of the diarrheal disease cholera. the rugose variant of v. cholerae is associated with the secretion of an exopolysaccharide. the rugose polysaccharide has been shown to confer increased resistance to a variety of agents, such as chlorine, bioacids, and oxidative and osmotic stresses. it also promotes biofilm formation, thereby increasing the survival of the bacteria in the aquatic environments. here we show that the extracellular protein secretion system ( ... | 2000 | 10722590 |
| the phytopathogenic bacteria erwinia carotovora infects drosophila and activates an immune response. | although drosophila possesses potent immune responses, little is known about the microbial pathogens that infect drosophila. we have identified members of the bacterial genus erwinia that induce the systemic expression of genes encoding antimicrobial peptides in drosophila larvae after ingestion. these erwinia strains are phytopathogens and use flies as vectors; our data suggest that these strains have also evolved mechanisms for exploiting their insect vectors as hosts. erwinia infections induc ... | 2000 | 10725405 |
| multiple interactions between pullulanase secreton components involved in stabilization and cytoplasmic membrane association of pule. | we report attempts to analyze interactions between components of the pullulanase (pul) secreton (type ii secretion machinery) from klebsiella oxytoca encoded by a multiple-copy-number plasmid in escherichia coli. three of the 15 pul proteins (b, h, and n) were found to be dispensable for pullulanase secretion. the following evidence leads us to propose that pule, pull, and pulm form a subcomplex with which pulc and pulg interact. the integral cytoplasmic membrane protein pull prevented proteolys ... | 2000 | 10735856 |
| degradation of pectins with different degrees of esterification by bacteroides thetaiotaomicron isolated from human gut flora. | a complete human fecal flora and cultures of defined species obtained from fecal flora were investigated in vitro to determine their ability to ferment the dietary fiber pectin. bacteroides thetaiotaomicron was tested as a pectin-degrading microorganism alone and in coculture with escherichia coli. macromolecular pectins with different degrees of esterification were used as substrates in microbial degradation studies. the levels of oligogalacturonic acids formed in batch cultures were estimated ... | 2000 | 10742206 |
| quorum sensing in the plant pathogen erwinia carotovora subsp. carotovora: the role of expr(ecc). | the production of the main virulence determinants of the plant pathogen erwinia carotovora subsp. carotovora, the extracellular cell wall-degrading enzymes, is partly controlled by the diffusible signal molecule n-(3-oxohexanoyl)-l-homoserine lactone (ohhl). ohhl is synthesized by the product of the expi/cari gene. linked to expi we found a gene encoding a putative transcriptional regulator of the luxr-family. this gene, expr(ecc), is transcribed convergently to the expi gene and the two open re ... | 2000 | 10755301 |
| interacting signal pathways control defense gene expression in arabidopsis in response to cell wall-degrading enzymes from erwinia carotovora. | we have characterized the role of salicylic acid (sa)-independent defense signaling in arabidopsis thaliana in response to the plant pathogen erwinia carotovora subsp. carotovora. use of pathway-specific target genes as well as signal mutants allowed us to elucidate the role and interactions of ethylene, jasmonic acid (ja), and sa signal pathways in this response. gene expression studies suggest a central role for both ethylene and ja pathways in the regulation of defense gene expression trigger ... | 2000 | 10755306 |
| a two-component regulatory system, pehr-pehs, controls endopolygalacturonase production and virulence in the plant pathogen erwinia carotovora subsp. carotovora. | genes coding for the main virulence determinants of the plant pathogen erwinia carotovora subsp. carotovora, the plant cell wall-degrading enzymes, are under the coordinate control of global regulator systems including both positive and negative factors. in addition to this global control, some virulence determinants are subject to specific regulation. we have previously shown that mutations in the pehr locus result in reduced virulence and impaired production of one of these enzymes, an endopol ... | 2000 | 10755308 |
| deduced amino-acid sequence and possible catalytic residues of a novel pectate lyase from an alkaliphilic strain of bacillus. | the nucleotide sequence of the gene for a highly alkaline, low-molecular-mass pectate lyase (pel-15) from an alkaliphilic bacillus isolate was determined. it harbored an open reading frame of 672 bp encoding the mature enzyme of 197 amino acids with a predicted molecular mass of 20 924 da. the deduced amino-acid sequence of the mature enzyme showed very low homology (< 20.4% identity) to those of known pectinolytic enzymes in the large pectate lyase superfamily (the polysaccharide lyase family 1 ... | 2000 | 10759850 |
| the gacs sensor kinase regulates alginate and poly-beta-hydroxybutyrate production in azotobacter vinelandii. | azotobacter vinelandii produces two polymers: the extracellular polysaccharide alginate and the intracellular polyester poly-beta-hydroxybutyrate (phb). a cosmid clone (psmu588) from an a. vinelandii gene library diminished alginate production by a. vinelandii mucoid strain atcc 9046. the nucleotide sequence and predicted amino acid sequence of the locus responsible for the mucoidy suppression revealed 65% identity to pseudomonas gacs, a transmembrane sensor kinase of the two-component regulator ... | 2000 | 10762268 |
| involvement of the respiratory chain of gram-negative bacteria in the reduction of tellurite. | the terminal oxidases of the respiratory chain of seven strains of gram-negative bacteria were shown to be involved in the reduction of tellurite. the rate of tellurite reduction correlated with the intensity of respiration. the inhibitors of terminal oxidases, carbon monoxide and cyanide, inhibited the reduction of tellurite. in pseudomonas aeruginosa pao ml4262 and p. aeruginosa pao ml4262 (pbs 10), the respiratory chain was found to contain three types of cytochrome c, one of which (the carbo ... | 2000 | 10763749 |
| [the effect of the substance exin on development of microbial infections and isolation of ethylene in plants]. | effects of exin on infection of tomato, potato, and cabbage plants with pseudomonas solanacearum and erwinia carotovora and a fungus sclerotium rolfsii were studied. the treatment of infected plants with exin caused no significant effect on the development of the disease. treatment with streptomycin as a standard for comparison completely inhibited the growth of these microorganisms. pretreatment with exin one to eight days before infecting inhibited the development of diseases. the numbers of t ... | 2000 | 10780015 |
| increased killing of bacillus subtilis on the hair roots of transgenic t4 lysozyme-producing potatoes. | transgenic potato plants expressing the phage t4 lysozyme gene which are resistant to the plant-pathogenic enterobacterium erwinia carotovora subsp. carotovora have been constructed. the agricultural growth of these potatoes might have harmful effects on soil microbiota as a result of t4 lysozyme release into the rhizosphere. to assess the bactericidal effect of roots, we have developed a novel method to associate the cells of bacillus subtilis with hair roots of plants and to quantify the survi ... | 2000 | 10788351 |
| development of a highly sensitive nested-pcr procedure using a single closed tube for detection of erwinia amylovora in asymptomatic plant material. | a novel method, which involves a nested pcr in a single closed tube, was developed for the sensitive detection of erwinia amylovora in plant material. the external and internal primer pairs used had different annealing temperatures and directed the amplification of a specific dna fragment from plasmid pea29. the procedure involved two consecutive pcrs, the first of which was performed at a higher annealing temperature that allowed amplification only by the external primer pair. using pure cultur ... | 2000 | 10788384 |
| inhibition of luminescence and virulence in the black tiger prawn (penaeus monodon) pathogen vibrio harveyi by intercellular signal antagonists. | expression of luminescence in the penaeus monodon pathogen vibrio harveyi is regulated by an intercellular quorum sensing mechanism involving the synthesis and detection of two signaling molecules, one of which is n-hydroxy butanoyl-l-homoserine lactone and the other of which is uncharacterized. indirect evidence has suggested that virulence, associated with a toxic extracellular protein, and luminescence in v. harveyi are coregulated. in this study the effects of an acylated homoserine lactone ... | 2000 | 10788385 |