| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| isolation and identification of antimicrobial furocoumarins from parsley. | photoactive furocoumarins extracted from four varieties of fresh and freeze-dried parsley leaves inhibited a dna repair-deficient escherichia coli in a photobiological assay. using media-modified assays, the human pathogens e. coli o157:h7 and listeria monocytogenes, the spoilage microorganism erwinia carotovora, and listeria innocua were also inhibited. pseudomonas fragi was not inhibited. minimum concentrations of forest green parsley powder in agar which showed inhibition ranged from 0.12% to ... | 1997 | 10465045 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| an evolutionarily conserved rna stem-loop functions as a sensor that directs feedback regulation of rnase e gene expression. | rnase e is a key regulatory enzyme that controls the principal pathway for mrna degradation in escherichia coli. the cellular concentration of this endonuclease is governed by a feedback mechanism in which rnase e tightly regulates its own synthesis. autoregulation is mediated in cis by the 361-nucleotide 5' untranslated region (utr) of rne (rnase e) mrna. here we report the determination of the secondary structure of the rne 5' utr by phylogenetic comparison and chemical alkylation, together wi ... | 2000 | 10817759 |
| detection of pseudomonas savastanoi pv. savastanoi in olive plants by enrichment and pcr. | the sequence of the gene iaal of pseudomonas savastanoi ew2009 was used to design primers for pcr amplification. the iaal-derived primers directed the amplification of a 454-bp fragment from genomic dna isolated from 70 strains of p. savastanoi, whereas genomic dna from 93 non-p. savastanoi isolates did not yield this amplified product. a previous bacterial enrichment in the semiselective liquid medium pvf-1 improved the pcr sensitivity level, allowing detection of 10 to 100 cfu/ml of plant extr ... | 2000 | 10831456 |
| 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 |
| distribution of aldoxime dehydratase in microorganisms. | the distribution of phenylacetaldoxime-degrading and pyridine-3-aldoxime-degrading ability was examined with intact cells of 975 microorganisms, including 45 genera of bacteria, 11 genera of actinomyces, 22 genera of yeasts, and 37 genera of fungi, by monitoring the decrease of the aldoximes by high-pressure liquid chromatography. the abilities were found to be widely distributed in bacteria, actinomyces, fungi, and some yeasts: 98 and 107 strains degraded phenylacetaldoxime and pyridine-3-aldox ... | 2000 | 10831401 |
| prey range characterization, ribotyping, and diversity of soil and rhizosphere bdellovibrio spp. isolated on phytopathogenic bacteria. | thirty new bdellovibrio strains were isolated from an agricultural soil and from the rhizosphere of plants grown in that soil. using a combined molecular and culture-based approach, we found that the soil bdellovibrios included subpopulations of organisms that differed from rhizosphere bdellovibrios. thirteen soil and seven common bean rhizosphere bdellovibrio strains were isolated when pseudomonas corrugata was used as prey; seven and two soil strains were isolated when erwinia carotovora subsp ... | 2000 | 10831412 |
| biosynthesis of carbapenem antibiotic and prodigiosin pigment in serratia is under quorum sensing control. | serratia sp. atcc 39006 produces the carbapenem antibiotic, carbapen-2-em-3-carboxylic acid and the red pigment, prodigiosin. we have previously reported the characterization of a gene, carr, controlling production of carbapenem in this strain. we now describe further characterization of the carr locus to locate the genes encoding carbapenem biosynthetic and resistance functions. a novel family of diverse proteins showing sequence similarity to the c-terminal domain of carf (required for carbape ... | 2000 | 10844645 |
| vibrio fischeri lux genes play an important role in colonization and development of the host light organ. | the bioluminescent bacterium vibrio fischeri and juveniles of the squid euprymna scolopes specifically recognize and respond to one another during the formation of a persistent colonization within the host's nascent light-emitting organ. the resulting fully developed light organ contains brightly luminescing bacteria and has undergone a bacterium-induced program of tissue differentiation, one component of which is a swelling of the epithelial cells that line the symbiont-containing crypts. while ... | 2000 | 10913092 |
| a carboxy-terminal 16-amino-acid region of sigma(38) of escherichia coli is important for transcription under high-salt conditions and sigma activities in vivo. | sigma(38) (or sigma(s), the rpos gene product) is a sigma subunit of rna polymerase in escherichia coli and directs transcription from a number of stationary-phase promoters as well as osmotically inducible promoters. in this study, we analyzed the function of the carboxy-terminal 16-amino-acid region of sigma(38) (residues 315 to 330), which is well conserved among the rpos gene products of enteric bacterial species. truncation of this region was shown to result in the loss of sigma activity in ... | 2000 | 10913098 |
| influence of deletions within domain ii of exotoxin a on its extracellular secretion from pseudomonas aeruginosa. | pseudomonas aeruginosa is a gram-negative bacterium that secretes many proteins into the extracellular medium via the xcp machinery. this pathway, conserved in gram-negative bacteria, is called the type ii pathway. the exoproteins contain information in their amino acid sequence to allow targeting to their secretion machinery. this information may be present within a conformational motif. the nature of this signal has been examined for p. aeruginosa exotoxin a (pe). previous studies failed to id ... | 2000 | 10869085 |
| identification and cell cycle control of a novel pilus system in caulobacter crescentus. | pilus assembly in caulobacter: crescentus occurs during a short period of the cell cycle and pili are only present at the flagellar pole of the swarmer cell. here we report a novel assay to visualize pili by light microscopy that led to the purification of caulobacter: pili and the isolation of a cluster of seven genes, including the major pilin subunit gene pila. this gene cluster encodes a novel group of pilus assembly proteins. we have shown that the pila promoter is activated late in the cel ... | 2000 | 10880436 |
| a regulatory rna (prrb rna) modulates expression of secondary metabolite genes in pseudomonas fluorescens f113. | the gacs-gaca two-component signal transduction system, which is highly conserved in gram-negative bacteria, is required for the production of exoenzymes and secondary metabolites in pseudomonas spp. screening of a pseudomonas fluorescens f113 gene bank led to the isolation of a previously undefined locus which could restore secondary metabolite production to both gacs and gaca mutants of f113. sequence analysis of this locus demonstrated that it did not contain any obvious pseudomonas protein-c ... | 2000 | 10869066 |
| controlling instability in gacs-gaca regulatory genes during inoculant production of pseudomonas fluorescens biocontrol strains. | secondary metabolism in fluorescent pseudomonads is globally regulated by gacs, which encodes a membrane-bound sensor kinase, and gaca, which encodes a transcriptional response regulator. spontaneous mutation in either gene blocked biosynthesis of the antimicrobial compounds hydrogen cyanide, 2,4-diacetylphloroglucinol, pyoluteorin, and pyrrolnitrin by the model biocontrol strain pseudomonas fluorescens cha0. spontaneous mutants also had altered abilities to utilize several carbon sources and to ... | 2000 | 10919762 |
| a genomic sample sequence of the entomopathogenic bacterium photorhabdus luminescens w14: potential implications for virulence. | photorhabdus luminescens is a pathogenic bacterium that lives in the guts of insect-pathogenic nematodes. after invasion of an insect host by a nematode, bacteria are released from the nematode gut and help kill the insect, in which both the bacteria and the nematodes subsequently replicate. however, the bacterial virulence factors associated with this "symbiosis of pathogens" remain largely obscure. in order to identify genes encoding potential virulence factors, we performed approximately 2,00 ... | 2000 | 10919786 |
| structure and function of pectic enzymes: virulence factors of plant pathogens. | the structure and function of erwinia chrysanthemi pectate lysase c, a plant virulence factor, is reviewed to illustrate one mechanism of pathogenesis at the molecular level. current investigative topics are discussed in this paper. | 2000 | 10922032 |
| acyl-homoserine lactone quorum sensing in gram-negative bacteria: a signaling mechanism involved in associations with higher organisms. | recent advances in studies of bacterial gene expression have brought the realization that cell-to-cell communication and community behavior are critical for successful interactions with higher organisms. species-specific cell-to-cell communication is involved in successful pathogenic or symbiotic interactions of a variety of bacteria with plant and animal hosts. one type of cell-cell signaling is acyl-homoserine lactone quorum sensing in gram-negative bacteria. this type of quorum sensing repres ... | 2000 | 10922036 |
| establishment of introduced antagonistic bacteria in the rhizosphere of transgenic potatoes and their effect on the bacterial community. | in a field release experiment, rifampicin resistant mutants of two antagonistic plant-associated bacteria were used for seed tuber inoculation of transgenic t4 lysozyme expressing potatoes, transgenic control potatoes and non-transgenic parental potatoes. the t4 lysozyme tolerant pseudomonas putida qc14-3-8 was originally isolated from the tuber surface (geocaulosphere) of t4 lysozyme producing plants and showed in vitro antibacterial activity to the bacterial pathogen erwinia carotovora ssp. at ... | 2000 | 10922502 |
| inhibition of fungal and bacterial plant pathogens by synthetic peptides: in vitro growth inhibition, interaction between peptides and inhibition of disease progression. | four synthetic cationic peptides, pep6, pep7, pep11 and pep20, were tested alone and in combinations for their antimicrobial activities against economically important plant pathogenic fungi (phytophthora infestans and alternaria solani) and bacteria (erwinia carotovora subsp. carotovora and e. carotovora subsp. atroseptica). in in vitro studies, p. infestans and a. solani were inhibited by all four peptides, while e. carotovora subsp. carotovora and e. carotovora subsp. atroseptica were inhibite ... | 2000 | 10939256 |
| induced expression of sarcotoxin ia enhanced host resistance against both bacterial and fungal pathogens in transgenic tobacco. | we demonstrate here that induced expression of sarcotoxin ia, a bactericidal peptide from sarcophaga peregrina, enhanced the resistance of transgenic tobacco plants to both bacterial and fungal pathogens. the peptide was produced with a modified pr1a promoter, which is further activated by salicylic acid treatment and necrotic lesion formation by pathogen infection. host resistance to infection of bacteria erwinia carotovora subsp. carotovora and pseudomonas syringae pv. tabaci was shown to be d ... | 2000 | 10939257 |
| identification of brucella abortus oxyr and its role in control of catalase expression. | we report the cloning and sequencing of the brucella abortus oxyr homolog and provide evidence that the transcription product of this gene binds to the b. abortus catalase promoter region. a gene replacement/deletion brucella oxyr mutant exhibits increased sensitivity to prolonged exposure to h(2)o(2) and is unable to adapt to h(2)o(2) in the environment. | 2000 | 10986275 |
| 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 |
| keys to symbiotic harmony. | | 2000 | 11004160 |
| new virulence-activated and virulence-repressed genes identified by systematic gene inactivation and generation of transcriptional fusions in bordetella pertussis. | an in silico scan of the partially completed genome sequence of bordetella pertussis and analyses of transcriptional fusions generated with a new integrational vector were used to identify new potential virulence genes. the genes encoding a putative siderophore receptor, adhesins, and an autotransporter protein appeared to be regulated in a manner similar to bordetella virulence genes by the global virulence regulator bvgas. in contrast, the gene encoding a putative intimin-like protein appeared ... | 2000 | 11004193 |
| quorum-sensing signal binding results in dimerization of trar and its release from membranes into the cytoplasm. | promoter binding by trar and luxr, the activators of two bacterial quorum-sensing systems, requires their cognate acyl-homoserine lactone (acyl-hsl) signals, but the role the signal plays in activating these transcription factors is not known. soluble active trar, when purified from cells grown with the acyl-hsl, contained bound signal and was solely in dimer form. however, genetic and cross-linking studies showed that trar is almost exclusively in monomer form in cells grown without signal. add ... | 2000 | 11013223 |
| an escherichia coli reference collection group b2- and uropathogen-associated polymorphism in the rpos-muts region of the e. coli chromosome. | chromosomal dnas of enterohemorrhagic, uropathogenic, and laboratory attenuated escherichia coli strains differ in the rpos-muts region. many uropathogens lack a deletion and an insertion characteristic of enterohemorrhagic strains. at the same chromosomal position, they harbor a 2.1-kb insertion of unknown origin with a base composition suggestive of horizontal gene transfer. unlike virulence determinants associated with urinary tract infection and/or neonatal meningitis (pap or prs, sfa, kps, ... | 2000 | 11029456 |
| pseudobactin biogenesis in the plant growth-promoting rhizobacterium pseudomonas strain b10: identification and functional analysis of the l-ornithine n(5)-oxygenase (psba) gene. | pseudobactin(b10), the fluorescent siderophore produced by the rhizobacterium pseudomonas strain b10, contains the hydroxamate ligand d-n(5)-hydroxyornithine (d-n(5)-oh-orn). we cloned the l-orn n(5)-oxygenase (psba) gene from a genomic library of pseudomonas strain b10 and demonstrated that psba is involved in the conversion of l-orn to its n(5)-oh derivative. psba shows significant similarity to microbial omega-amino acid hydroxylases containing flavin adenine dinucleotide and nadp cofactor-bi ... | 2000 | 11029447 |
| antimicrobial effect of rosemary extracts. | a rosemary extract commercially exploited (oxy'less) as an antioxidant of lipids in foods was dissolved in ethanol (100 mg/ml), and the solution was tested against foodborne microorganisms. for gram-positive bacteria, the mic of the ethanolic solution was 1% for leuconostoc mesenteroides, 0.5% for listeria monocytogenes, 0.5% for staphylococcus aureus, 0.13% for streptococcus mutans, and 0.06% for bacillus cereus. it slowed the growth of penicillium roquefortii and botrytis cinerea. up to 1% of ... | 2000 | 11041135 |
| a potato gene encoding a wrky-like transcription factor is induced in interactions with erwinia carotovora subsp. atroseptica and phytophthora infestans and is coregulated with class i endochitinase expression. | a potato gene encoding a putative wrky protein was isolated from a cdna library enriched by suppression subtractive hybridization for sequences upregulated 1 h postinoculation with erwinia carotovora subsp. atroseptica. the cdna encodes a putative polypeptide of 172 amino acids, containing a single wrky domain with a zinc finger motif and preceded by a potential nuclear localization site. st-wrky1 was strongly upregulated in compatible, but only weakly in incompatible, interactions with phytopht ... | 2000 | 11043470 |
| the pseudomonas aeruginosa lectins pa-il and pa-iil are controlled by quorum sensing and by rpos. | in pseudomonas aeruginosa, many exoproduct virulence determinants are regulated via a hierarchical quorum-sensing cascade involving the transcriptional regulators lasr and rhlr and their cognate activators, n-(3-oxododecanoyl)-l-homoserine lactone (3o-c12-hsl) and n-butanoyl-l-homoserine lactone (c4-hsl). in this paper, we demonstrate that the cytotoxic lectins pa-il and pa-iil are regulated via quorum sensing. using immunoblot analysis, the production of both lectins was found to be directly de ... | 2000 | 11053384 |
| analysis of the role of reca in phenotypic switching of pseudomonas tolaasii. | switching between the pathogenic smooth (1116s) and nonpathogenic rough (1116r) forms of pseudomonas tolaasii occurs due to the reversible duplication of a 661-bp element within the phen locus. disruption of the chromosomal reca locus of 1116s and 1116r produced strains 1116sreca and 1116rreca, respectively, which showed typical loss of uv resistance. switching from the smooth to the rough form was virtually eliminated in the 1116sreca strain, whereas the extent of switching from the rough to th ... | 2000 | 11053404 |
| 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 |
| identification of ciprofloxacin-resistant campylobacter jejuni by use of a fluorogenic pcr assay. | fluoroquinolones are one class of antimicrobial agents commonly used to treat severe campylobacter jejuni infection. c. jejuni strains resistant to high levels of the fluoroquinolone ciprofloxacin (mic >/=16 microg/ml) have been predominantly characterized with a c-->t transition in codon 86 of gyra. the gyra gene encodes one subunit of dna gyrase, which is a primary target for fluoroquinolone antibiotics. this study establishes a rapid pcr-based taqman method for identifying ciprofloxacin-resis ... | 2000 | 11060054 |
| linear beta-1,3 glucans are elicitors of defense responses in tobacco. | laminarin, a linear beta-1,3 glucan (mean degree of polymerization of 33) was extracted and purified from the brown alga laminaria digitata. its elicitor activity on tobacco (nicotiana tabacum) was compared to that of oligogalacturonides with a mean degree of polymerization of 10. the two oligosaccharides were perceived by suspension-cultured cells as distinct chemical stimuli but triggered a similar and broad spectrum of defense responses. a dose of 200 microg ml(-1) laminarin or oligogalacturo ... | 2000 | 11080280 |
| identification and characterization of yersinia enterocolitica genes induced during systemic infection. | yersinia enterocolitica is one of three pathogenic yersinia species that share a tropism for lymphoid tissues. however, infection of an immunocompromised host is likely to result in a systemic infection, which is often fatal. little is known about the bacterial proteins needed to establish such an infection. the genes that encode these virulence factors are likely to be active only during systemic infection. a library of random cat fusions was used to inoculate balb/c mice. fusions expressed dur ... | 2000 | 11083775 |
| regulation of salmonella enterica serovar typhimurium invasion genes by csra. | penetration of intestinal epithelial cells by salmonella enterica serovar typhimurium requires the expression of invasion genes, found in salmonella pathogenicity island 1 (spi1), that encode components of a type iii secretion apparatus. these genes are controlled in a complex manner by regulators within spi1, including hila and invf, and those outside spi1, such as the two-component regulators phop/phoq and bara/sira. we report here that epithelial cell invasion requires the serovar typhimurium ... | 2000 | 11083797 |
| metabolism of acyl-homoserine lactone quorum-sensing signals by variovorax paradoxus. | acyl-homoserine lactones (acyl-hsls) serve as dedicated cell-to-cell signaling molecules in many species of the class proteobacteria. we have addressed the question of whether these compounds can be degraded biologically. a motile, rod-shaped bacterium was isolated from soil based upon its ability to utilize n-(3-oxohexanoyl)-l-homoserine lactone as the sole source of energy and nitrogen. the bacterium was classified as a strain of variovorax paradoxus. the v. paradoxus isolate was capable of gr ... | 2000 | 11092851 |
| improved barley broiler feed with transgenic malt containing heat-stable (1,3-1,4)-beta-glucanase. | the low nutritional value of barley for poultry is because of the absence of an intestinal enzyme for efficient depolymerization of (1, 3-1,4)-beta-glucan, the major polysaccharide of the endosperm cell walls. this leads to high viscosity in the intestine, limited nutrient uptake, decreased growth rate, and unhygienic sticky droppings adhering to chickens and floors of the production cages. consequently, the 7.5 billion broiler chickens produced annually in the united states are primarily raised ... | 2000 | 11106393 |
| 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 ... | 2001 | 11133457 |
| a competitive pcr-based method for the detection and quantification of erwinia carotovora subsp. atroseptica on potato tubers. | a pcr-based method was developed for the simultaneous detection and quantification of the potato pathogen erwinia carotovora subsp. atroseptica (eca) on potato tubers. the method incorporates a competitor pcr template cloned into escherichia coli in vector pgem-t (e. coli 4r l/l). predetermined numbers of e. coli 4r were added to potato peel extract, either pre-inoculated with eca or from naturally contaminated tubers, and eca numbers estimated by comparing the ratio of products generated from e ... | 2000 | 10792657 |
| gfp-based n-acyl homoserine-lactone sensor systems for detection of bacterial communication. | in order to perform single-cell analysis and online studies of n-acyl homoserine lactone (ahl)-mediated communication among bacteria, components of the vibrio fischeri quorum sensor encoded by luxr-p(luxi) have been fused to modified versions of gfpmut3* genes encoding unstable green fluorescent proteins. bacterial strains harboring this green fluorescent sensor detected a broad spectrum of ahl molecules and were capable of sensing the presence of 5 nm n-3-oxohexanoyl-l-homoserine lactone in the ... | 2001 | 11157219 |
| 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 ... | 2001 | 11157222 |
| disulfide bond formation in secreton component pulk provides a possible explanation for the role of dsba in pullulanase secretion. | when expressed in escherichia coli, the 15 klebsiella oxytoca pul genes that encode the so-called pul secreton or type ii secretion machinery promote pullulanase secretion and the assembly of one of the secreton components, pulg, into pili. besides these pul genes, efficient pullulanase secretion also requires the host dsba gene, encoding a periplasmic disulfide oxidoreductase, independently of disulfide bond formation in pullulanase itself. two secreton components, the secretin pilot protein pu ... | 2001 | 11157944 |
| subset of hybrid eukaryotic proteins is exported by the type i secretion system of erwinia chrysanthemi. | erwinia chrysanthemi exports degradative enzymes by using a type i protein secretion system. the proteases secreted by this system lack an n-terminal signal peptide but contain a c-terminal secretion signal. to explore the substrate specificity of this system, we have expressed the e. chrysanthemi transporter system (prtdef genes) in escherichia coli and tested the ability of this abc transporter to export hybrid proteins carrying c-terminal fragments of e. chrysanthemi protease b. the c terminu ... | 2001 | 11157948 |
| 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 ... | 2001 | 11157954 |
| 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 ... | 2001 | 11161023 |
| bacteria in the leaf ecosystem with emphasis on pseudomonas syringae-a pathogen, ice nucleus, and epiphyte. | the extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. this review focuses on the bacterial component of leaf microbial communities, with emphasis on pseudomonas syringae-a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. among the diversity of bacteria that colonize leaves, none has received wider attention than p. syringae, as it gained notoriety for being the firs ... | 2000 | 10974129 |
| 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. ... | 2001 | 11208795 |
| 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 |
| the pleiotropic two-component regulatory system phop-phoq. | | 2001 | 11222580 |
| molecular characterization of global regulatory rna species that control pathogenicity factors in erwinia amylovora and erwinia herbicola pv. gypsophilae. | rsmb(ecc) specifies a nontranslatable rna regulator that controls exoprotein production and pathogenicity in soft rot-causing erwinia carotovora subsp. carotovora. this effect of rsmb(ecc) rna is mediated mostly by neutralizing the function of rsma(ecc), an rna-binding protein of e. carotovora subsp. carotovora, which acts as a global negative regulator. to determine the occurrence of functional homologs of rsmb(ecc) in non-soft-rot-causing erwinia species, we cloned the rsmb genes of e. amylovo ... | 2001 | 11222584 |
| phylogeny of genes for secretion ntpases: identification of the widespread tada subfamily and development of a diagnostic key for gene classification. | macromolecular transport systems in bacteria currently are classified by function and sequence comparisons into five basic types. in this classification system, type ii and type iv secretion systems both possess members of a superfamily of genes for putative ntp hydrolase (ntpase) proteins that are strikingly similar in structure, function, and sequence. these include virb11, trbb, trag, gspe, pilb, pilt, and comg1. the predicted protein product of tada, a recently discovered gene required for t ... | 2001 | 11226268 |
| 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 ... | 2001 | 11229911 |