Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| the quorum sensing negative regulators esar and expr(ecc), homologues within the luxr family, retain the ability to function as activators of transcription. | most luxr homologues function as activators of transcription during the process of quorum sensing, but a few, including esar and expr(ecc), negatively impact gene expression. the luxr-activated luxi promoter and luxr binding site, the lux box, were used in artificial contexts to assess the potential for transcriptional activation and dna binding by esar and expr(ecc). although the acyl-homoserine lactone responsiveness of both proteins is the opposite of that shown by most luxr family members, e ... | 2003 | 14617666 |
| oxyr acts as a repressor of catalase expression in neisseria gonorrhoeae. | it has been reported that neisseria gonorrhoeae possesses a very high level of catalase activity, but the regulation of catalase expression has not been investigated extensively. in escherichia coli and salmonella enterica serovar typhimurium, it has been demonstrated that oxyr is a positive regulator of hydrogen peroxide-inducible genes, including the gene encoding catalase. the oxyr gene from n. gonorrhoeae was cloned and used to complement an e. coli oxyr mutant, confirming its identity and f ... | 2003 | 12496210 |
| nitric oxide contributes to induction of innate immune responses to gram-negative bacteria in drosophila. | studies in mammals uncovered important signaling roles of nitric oxide (no), and contributions to innate immunity. suggestions of conservation led us to explore the involvement of no in drosophila innate immunity. inhibition of nitric oxide synthase (nos) increased larval sensitivity to gram-negative bacterial infection, and abrogated induction of the antimicrobial peptide diptericin. nos was up-regulated after infection. antimicrobial peptide reporters revealed that no triggered an immune respo ... | 2003 | 12514104 |
| enhancement of population size of a biological control agent and efficacy in control of bacterial speck of tomato through salicylate and ammonium sulfate amendments. | sodium salicylate and ammonium sulfate were applied to leaf surfaces along with suspensions of the biological control agents pseudomonas syringae cit7(pnah7), which catabolizes salicylate, and cit7, which does not catabolize salicylate, to determine whether enhanced biological control of bacterial speck of tomato could be achieved. foliar amendment with salicylate alone significantly enhanced the population size and the efficacy of cit7(pnah7), but not of cit7, on tomato leaves. application of a ... | 2003 | 12571060 |
| gaca regulates symbiotic colonization traits of vibrio fischeri and facilitates a beneficial association with an animal host. | the gacs/gaca two-component system regulates the expression of bacterial traits during host association. although the importance of gacs/gaca as a regulator of virulence is well established, its role in benign associations is not clear, as mutations in either the gacs or gaca gene have little impact on the success of colonization in nonpathogenic associations studied thus far. using as a model the symbiotic association of the bioluminescent marine bacterium vibrio fischeri with its animal host, ... | 2003 | 14645281 |
| pathways leading from bara/sira to motility and virulence gene expression in salmonella. | the bara and sira genes of salmonella enterica serovar typhimurium encode a two-component sensor kinase and a response regulator, respectively. this system increases the expression of virulence genes and decreases the expression of motility genes. in this study, we examined the pathways by which sira affects these genes. we found that the master regulator of flagellar genes, flhdc, had a positive regulatory effect on the primary regulator of intestinal virulence determinants, hila, but that hila ... | 2003 | 14645287 |
| vibrio harveyi quorum sensing: a coincidence detector for two autoinducers controls gene expression. | in a process called quorum sensing, bacteria communicate with one another by exchanging chemical signals called autoinducers. in the bioluminescent marine bacterium vibrio harveyi, two different auto inducers (ai-1 and ai-2) regulate light emission. detection of and response to the v.harveyi autoinducers are accomplished through two two-component sensory relay systems: ai-1 is detected by the sensor luxn and ai-2 by luxpq. here we further define the v.harveyi quorum-sensing regulon by identifyin ... | 2003 | 12574123 |
| quorum sensing in nitrogen-fixing rhizobia. | members of the rhizobia are distinguished for their ability to establish a nitrogen-fixing symbiosis with leguminous plants. while many details of this relationship remain a mystery, much effort has gone into elucidating the mechanisms governing bacterium-host recognition and the events leading to symbiosis. several signal molecules, including plant-produced flavonoids and bacterially produced nodulation factors and exopolysaccharides, are known to function in the molecular conversation between ... | 2003 | 14665677 |
| a single gene that promotes interaction of a phytopathogenic bacterium with its insect vector, drosophila melanogaster. | insects are major vectors of plant and animal disease, and bacterial phytopathogens are often disseminated by flies. we have previously reported that some isolates of the phytopathogenic bacterial species erwinia carotovora infect drosophila and activate an immune response. using a genetic screen, we have now identified two genes that are required by e. carotovora to infect drosophila. one of these genes has a regulatory role whereas the other, evf, confers an infectious phenotype: its transfer ... | 2003 | 12612613 |
| regulation of the vitamin b12 metabolism and transport in bacteria by a conserved rna structural element. | cobalamin in the form of adenosylcobalamin (ado-cbl) is known to repress expression of genes for vitamin b(12) biosynthesis and be transported by a posttranscriptional regulatory mechanism, which involves direct binding of ado-cbl to 5'untranslated gene regions (5'utr). using comparative analysis of genes and regulatory regions, we identified a highly conserved rna structure, the b12-element, which is widely distributed in 5'utrs of vitamin b(12)-related genes in eubacteria. multiple alignment o ... | 2003 | 12923257 |
| insertion sequence isecp1b is involved in expression and mobilization of a bla(ctx-m) beta-lactamase gene. | the genetic structures (ca. 10-kb dna fragment) surrounding the plasmid-borne extended-spectrum beta-lactamase bla(ctx-m-19) gene in a klebsiella pneumoniae clinical isolate were determined. this beta-lactamase gene was part of a 4,797-bp transposon inserted inside orf1 of tn1721. inside this transposon, bla(ctx-m-19) was bracketed upstream and downstream by insertion sequences ise cp1b and is903d, respectively, and further downstream by a truncated gene encoding an outer membrane protein for ir ... | 2003 | 12936998 |
| [the bactericidal activity of lectins from nitrogen-fixing bacilli]. | lectins i and ii isolated from the nitrogen-fixing soil bacterium paenibacillus polymyxa 1460 were found to be able to suppress the growth of rhizobium leguminosarum 252 and bacillus subtilis 36 at nearly all the concentrations tested (from 1 to 10 micrograms/ml). lectin i was also inhibitory to azospirillum brasilense 245 and erwinia carotovora subsp. citrulis 603, while lectin ii exerted bactericidal activity against xanthomonas campestris b-610 and b-611 and a. brasilense 245. the bacillar le ... | 2003 | 12901008 |
| the ti plasmid of agrobacterium tumefaciens harbors an attm-paralogous gene, aiib, also encoding n-acyl homoserine lactonase activity. | the agrobacterium tumefaciens c58 genome contains three putative n-acyl homoserine lactone (acyl-hsl) hydrolases, which are closely related to the lactonase aiia of bacillus. when expressed in escherichia coli, two of the putative acyl-hsl hydrolases, attm and aiib, conferred the ability to degrade acyl-hsls on the host. in erwinia strain 6276, the lactonases reduced the endogenous acyl-hsl level and the bacterial virulence in planta. | 2003 | 12902298 |
| novel bacteria degrading n-acylhomoserine lactones and their use as quenchers of quorum-sensing-regulated functions of plant-pathogenic bacteria. | bacteria degrading the quorum-sensing (qs) signal molecule n-hexanoylhomoserine lactone were isolated from a tobacco rhizosphere. twenty-five isolates degrading this homoserine lactone fell into six groups according to their genomic rep-pcr and rrs pcr-rflp profiles. representative strains from each group were identified as members of the genera pseudomonas, comamonas, variovorax and rhodococcus: all these isolates degraded n-acylhomoserine lactones other than the hexanoic acid derivative, albei ... | 2003 | 12904538 |
| the drosophila forkhead transcription factor foxo mediates the reduction in cell number associated with reduced insulin signaling. | forkhead transcription factors belonging to the foxo subfamily are negatively regulated by protein kinase b (pkb) in response to signaling by insulin and insulin-like growth factor in caenorhabditis elegans and mammals. in drosophila, the insulin-signaling pathway regulates the size of cells, organs, and the entire body in response to nutrient availability, by controlling both cell size and cell number. in this study, we present a genetic characterization of dfoxo, the only drosophila foxo ortho ... | 2003 | 12908874 |
| structure of the o-polysaccharide of erwinia carotovora ssp. carotovora gspb 436. | the o-polysaccharide of a phytopathogenic bacterium, erwinia carotovora ssp. carotovora gspb 436, was studied by sugar and methylation analysis, along with 1h and 13c nmr spectroscopy. the following structure of the branched tetrasaccharide repeating unit of the o-polysaccharide was established: [carbohydrate structure in text] the o-polysaccharide contains a minor proportion of 4-o-methylrhamnose, which is suggested to terminate the polymer main chain. | 2003 | 14499581 |
| the erwinia chrysanthemi phop-phoq operon plays an important role in growth at low ph, virulence and bacterial survival in plant tissue. | we have studied the role of acidic ph as a barrier for the colonization of the plant apoplast by erwinia chrysanthemi. a minitransposon containing a promoterless reporter gene, gus, was used for random mutagenesis of the bacterial genome. an acid-sensitive mutant, named bt119, was isolated and had the following differential features with respect to the wild-type strain: (i) inability to grow at ph </= 5.5; (ii) decreased survival at acid ph and in plant tissues; (iii) increased susceptibility to ... | 2003 | 12828634 |
| identification of a new ribosomal protection type of tetracycline resistance gene, tet(36), from swine manure pits. | previously, only one ribosome protection type of a tetracycline resistance gene, tetq, had been identified in bacteroides spp. during an investigation of anaerobic bacteria present in swine feces and manure storage pits, a tetracycline-resistant bacteroides strain was isolated. subsequent analysis showed that this new bacteroides strain, bacteroides sp. strain 139, did not contain tetq but contained a previously unidentified tetracycline resistance gene. sequence analysis showed that the tetracy ... | 2003 | 12839793 |
| detection and diversity assessment of xylella fastidiosa in field-collected plant and insect samples by using 16s rrna and gyrb sequences. | the causal agent of diseases in many economically important plants is attributed to the xylem-limited bacterium xylella fastidiosa. the detection of this plant pathogen has been hampered due to its difficult isolation and slow growth on plates. nearly complete nucleotide sequences of the 16s rrna gene and partial sequences of the gyrb gene were determined for 18 strains of x. fastidiosa isolated from different plant hosts. a phylogenetic analysis, based on gyrb, grouped strains in three clusters ... | 2003 | 12839807 |
| sequence of the escherichia coli o121 o-antigen gene cluster and detection of enterohemorrhagic e. coli o121 by pcr amplification of the wzx and wzy genes. | the dna sequence of the 15,155-bp o-antigen gene cluster of escherichia coli o121 was determined, and 14 open reading frames were identified (all had the same transcriptional direction). analyses of results indicated that the wzx (o-antigen flippase) and wzy (o-antigen polymerase) genes were e. coli o121 specific, so regions in these two genes were chosen for development of pcr assays. the pcr assays using dna from 99 e. coli o121 strains, strains representative of non-o121 e. coli serogroups, a ... | 2003 | 12843098 |
| peh production, flagellum synthesis, and virulence reduced in erwinia carotovora subsp. carotovora by mutation in a homologue of cytr. | erwinia carotovora subsp. carotovora is a causal agent of soft-rot diseases in a wide variety of plants. here, we have isolated a new regulatory factor involved in the virulence of e. carotovora subsp. carotovora by in vivo insertional mutagenesis using a transposon tn5. the gene was homologous to cytr encoding a transcriptional repressor of nucleoside uptake and catabolism genes in escherichia coli, salmonella typhimurium, and vibrio cholerae. phenotypic characterization of a nonpolar deletion ... | 2003 | 12744509 |
| [the study of erwinia carotovora bacteriocins in the nalidixic acid resistant erwinia carotovora]. | a novel approach is proposed for the study of the macromolecular bacteriocins of erwinia carotovora (mctvs). the approach lies in that the bacteriocinogeny of pectolytic erwinia is studied using a lawn of a bacterial mutant resistant to nalidixic acid, an inducer of mctvs. the high efficiency of this approach was demonstrated by studying carotovoricins in 104 different e. carotovora strains, 88% of which bear mctvs, distinguished by the morphology of zones of induced lysis on a lawn of susceptib ... | 2003 | 12751244 |
| mutation of luxs of streptococcus pneumoniae affects virulence in a mouse model. | the luxs protein is required for the biosynthesis of the type 2 autoinducer (ai-2), which is involved in quorum sensing in a wide range of bacterial species. we have determined the effects of a defined luxs mutation on the virulence of streptococcus pneumoniae. although the luxs mutant displayed reduced virulence relative to its wild-type parent, the type 2 strain d39, it was by no means avirulent in a mouse model. after intranasal administration, the luxs mutant was able to colonize the nasopha ... | 2003 | 12761100 |
| ahld, an n-acylhomoserine lactonase in arthrobacter sp., and predicted homologues in other bacteria. | quorum sensing is a signalling mechanism that controls diverse biological functions, including virulence, via n-acylhomoserine lactone (ahl) signal molecules in gram-negative bacteria. with the aim of isolating strains or enzymes capable of blocking quorum sensing by inactivating ahl, bacteria were screened for ahl degradation by their ability to utilize n-3-oxohexanoyl-l-homoserine lactone (ohhl) as the sole carbon source. among four isolates, strain ibn110, identified as arthrobacter sp., was ... | 2003 | 12777494 |
| characterization of the xanthomonas axonopodis pv. glycines hrp pathogenicity island. | we sequenced an approximately 29-kb region from xanthomonas axonopodis pv. glycines that contained the hrp type iii secretion system, and we characterized the genes in this region by tn3-gus mutagenesis and gene expression analyses. from the region, hrp (hypersensitive response and pathogenicity) and hrc (hrp and conserved) genes, which encode type iii secretion systems, and hpa (hrp-associated) genes were identified. the characteristics of the region, such as the presence of many virulence gene ... | 2003 | 12730176 |
| novel virulence-associated type ii secretion system unique to high-pathogenicity yersinia enterocolitica. | yersinia enterocolitica strains comprise an important group of bacterial enteropathogens that cause a broad range of gastrointestinal syndromes. three groups are distinguishable within this bacterial species, namely, the nonpathogenic group (biotype 1a strains), the low-pathogenicity, non-mouse-lethal group (biotypes 2 to 5), and the high-pathogenicity, mouse-lethal group (biotype 1b). to date, the presence of the high-pathogenicity island (hpi), a chromosomal locus that encodes the yersiniabact ... | 2003 | 12654803 |
| isolation and antifungal and antioomycete activities of aerugine produced by pseudomonas fluorescens strain mm-b16. | the bacterial strain mm-b16, which showed strong antifungal and antioomycete activity against some plant pathogens, was isolated from a mountain forest soil in korea. based on the physiological and biochemical characteristics and 16s ribosomal dna sequence analysis, the bacterial strain mm-b16 was identical to pseudomonas fluorescens. an antibiotic active against colletotrichum orbiculare and phytophthora capsici in vitro and in vivo was isolated from the culture filtrates of p. fluorescens stra ... | 2003 | 12676678 |
| elevation of three subspecies of pectobacterium carotovorum to species level: pectobacterium atrosepticum sp. nov., pectobacterium betavasculorum sp. nov. and pectobacterium wasabiae sp. nov. | a collection of 42 strains belonging to the five subspecies of pectobacterium carotovorum (subspecies atrosepticum, betavasculorum, carotovorum, odoriferum and wasabiae) and 11 reference and type strains of biovars of pectobacterium chrysanthemi, pectobacterium cacticidum and brenneria paradisiaca were studied by dna-dna hybridization, numerical taxonomy of 120 phenotypic characteristics, serology and new phylogenetic analysis of previously reported sequences from a database of aligned 16s rdna ... | 2003 | 12710602 |
| mutational analysis of the residue at position 48 in the salmonella enterica serovar typhimurium phoq sensor kinase. | the phop/phoq two-component regulatory system of salmonella enterica serovar typhimurium plays an essential role in controlling virulence by mediating the adaptation to mg(2+) depletion. the pho-24 allele of phoq harbors a single amino acid substitution (t48i) in the periplasmic domain of the phoq histidine kinase sensor. this mutation has been shown to increase net phosphorylation of the phop response regulator. we analyzed the effect on signaling by phop/phoq of various amino acid substitution ... | 2003 | 12618457 |
| quorum-sensing system and stationary-phase sigma factor (rpos) of the onion pathogen burkholderia cepacia genomovar i type strain, atcc 25416. | bacterial strains belonging to burkholderia cepacia can be human opportunistic pathogens, plant pathogens, and plant growth promoting and have remarkable catabolic activity. b. cepacia consists of several genomovars comprising what is now known as the b. cepacia complex. here we report the quorum-sensing system of a genomovar i onion rot type strain atcc 25416. quorum sensing is a cell-density-dependent regulatory response which involves the production of n-acyl homoserine lactone (hsl) signal m ... | 2003 | 12620866 |
| two families of mechanosensitive channel proteins. | mechanosensitive (ms) channels that provide protection against hypoosmotic shock are found in the membranes of organisms from the three domains of life: bacteria, archaea, and eucarya. two families of ubiquitous ms channels are recognized, and these have been designated the mscl and mscs families. a high-resolution x-ray crystallographic structure is available for a member of the mscl family, and extensive molecular genetic, biophysical, and biochemical studies conducted in many laboratories hav ... | 2003 | 12626684 |
| rhamnogalacturonate lyase rhie is secreted by the out system in erwinia chrysanthemi. | supernatants of rhamnose-induced erwinia chrysanthemi strain 3937 cultures contain a principal secreted protein named rhie. a rhie mutant has been found among a set of rhamnose-induced mudi1681 lacz fusions. rhie is a 62-kda protein that has rhamnogalacturonate lyase activity on rhamnogalacturonan i (rg-i). it does not require a divalent cation for its activity and has an optimal ph of 6.0. rhie expression is strongly induced in the presence of rhamnose but is also regulated by pect and crp, two ... | 2003 | 12591882 |
| role of rsma in the regulation of swarming motility and virulence factor expression in proteus mirabilis. | swarming by proteus mirabilis involves differentiation of typical short vegetative rods into filamentous hyper-flagellated swarm cells that undergo cycles of rapid and co-ordinated population migration across surfaces and exhibit high levels of virulence gene expression. rsma (repressor of secondary metabolites) and csra, its homologue in escherichia coli, control many phenotypic traits, such as motility and pathogenesis in erwinia species, glycogen biosynthesis, cell size and biofilm formation ... | 2003 | 12488561 |
| celi, a noncellulosomal family 9 enzyme from clostridium thermocellum, is a processive endoglucanase that degrades crystalline cellulose. | the family 9 cellulase gene celi of clostridium thermocellum, was previously cloned, expressed, and characterized (g. p. hazlewood, k. davidson, j. i. laurie, n. s. huskisson, and h. j. gilbert, j. gen. microbiol. 139:307-316, 1993). we have recloned and sequenced the entire celi gene and found that the published sequence contained a 53-bp deletion that generated a frameshift mutation, resulting in a truncated and modified c-terminal segment of the protein. the enzymatic properties of the wild-t ... | 2003 | 12511483 |
| functional and mutational analysis of conjugative transfer region 2 (tra2) from the inchi1 plasmid r27. | the transfer 2 region (tra2) of the conjugative plasmid drr27 (derepressed r27) was analyzed by psi-blast, insertional mutagenesis, genetic complementation, and an h-pilus assay. tra2 contains 11 mating-pair formation (mpf) genes that are essential for conjugative transfer, 9 of which are essential for h-pilus production (trha, -l, -e, -k, -b, -v, -c, -p, and -w). trhk has similarity to secretin proteins, suggesting a mechanism by which dna could traverse the outer membrane of donors. the remain ... | 2003 | 12511505 |
| a colonization factor (production of lateral flagella) of mesophilic aeromonas spp. is inactive in aeromonas salmonicida strains. | the nine laf (lateral flagellum) genes of mesophilic aeromonads are in the aeromonas salmonicida genome. the laf genes are functional, except for lafa (flagellin gene), which was inactivated by transposase 8 (is3 family). a pathogenic characteristic of mesophilic aeromonads (lateral flagella) is abolished in this specialized pathogen with a narrow host range. | 2003 | 12514057 |
| sm-like proteins in eubacteria: the crystal structure of the hfq protein from escherichia coli. | the hfq protein was discovered in escherichia coli in the early seventies as a host factor for the qbeta phage rna replication. during the last decade, it was shown to be involved in many rna processing events and remote sequence homology indicated a link to spliceosomal sm proteins. we report the crystal structure of the e.coli hfq protein showing that its monomer displays a characteristic sm-fold and forms a homo-hexamer, in agreement with former biochemical data. overall, the structure of the ... | 2003 | 12853626 |
| sweet pepper ferredoxin-like protein ( pflp) gene as a novel selection marker for orchid transformation. | a novel method for selection of transgenic plants utilizing the sweet pepper ( capsicum annuum l.) ferredoxin-like protein ( pflp) gene as selection marker and erwinia carotovora as the selection agent has been developed. an expression vector containing a pflp cdna driven by a cauliflower mosaic virus 35s promoter was successfully transformed into protocorm-like bodies of oncidium orchid by agrobacterium tumefaciens and particle bombardment, respectively. erwinia carotovora was used as a selecti ... | 2003 | 12721849 |
| characterization of the hrp pathogenicity cluster of erwinia carotovora subsp. carotovora: high basal level expression in a mutant is associated with reduced virulence. | extracellularly targeted proteins are crucial for virulence of gram-negative phytopathogenic bacteria. erwinia carotovora subsp. carotovora employs the so-called type ii (gsp) pathway to secrete a number of pectinases and cellulases, which cause the typical tissue maceration symptoms of soft-rot disease. the type iii (hrp) pathway is the major virulence determinant in the genera pseudomonas, ralstonia and xanthomonas, and in non-macerating species of erwinia. the hrp cluster was recently partial ... | 2003 | 14576934 |
| the pmra-pmrb two-component system responding to acidic ph and iron controls virulence in the plant pathogen erwinia carotovora ssp. carotovora. | efficient response to environmental cues is crucial to successful infection by plant-pathogenic bacteria such as erwinia carotovora ssp. carotovora. the expression of the main virulence genes of this pathogen, encoding extracellular enzymes that degrade the plant-cell wall, is subject to complex regulatory machinery where two-component systems play an important role. in this paper, we describe for the first time the involvement of the pmra-pmrb two-component system in regulation of virulence in ... | 2003 | 14617142 |
| isolation of enterobacter sakazakii from midgut of stomoxys calcitrans. | 2003 | 14626227 | |
| regulation of lysine biosynthesis and transport genes in bacteria: yet another rna riboswitch? | comparative analysis of genes, operons and regulatory elements was applied to the lysine biosynthetic pathway in available bacterial genomes. we report identification of a lysine-specific rna element, named the lys element, in the regulatory regions of bacterial genes involved in biosynthesis and transport of lysine. similarly to the previously described rna regulatory elements for three vitamins (riboflavin, thiamin and cobalamin), purine and methionine regulons, this regulatory rna structure i ... | 2003 | 14627808 |
| functional domains of the rhlr transcriptional regulator of pseudomonas aeruginosa. | the rhlr transcriptional regulator of pseudomonas aeruginosa, along with its cognate autoinducer, n-butyryl homoserine lactone (c(4)-hsl), regulates gene expression in response to cell density. with an escherichia coli lexa-based protein interaction system, we demonstrated that rhlr multimerized and that the degree of multimerization was dependent on the c(4)-hsl concentration. studies with an e. coli lasb::lacz lysogen demonstrated that rhlr multimerization was necessary for it to function as a ... | 2003 | 14645272 |
| oxidative burst elicited by bacillus mycoides isolate bac j, a biological control agent, occurs independently of hypersensitive cell death in sugar beet. | response of sugar beet cultivars c40 and ush11 to syringe infiltration of live and dead bacillus mycoides isolate bac j, a biological control agent, and virulent and avirulent isolates of erwinia carotovora pv. betavasculorum was measured by monitoring systemic acquired resistance control of cercospora beticola, specific activity of chitinase and beta-glucanase, the oxidative burst, and hypersensitive cell death at the infiltration site. priming sugar beet with b. mycoides bac j (1 x 10(8) cells ... | 2003 | 14651348 |
| proteomic analysis of wild-type sinorhizobium meliloti responses to n-acyl homoserine lactone quorum-sensing signals and the transition to stationary phase. | proteome analysis revealed that two long-chain n-acyl homoserine lactones (ahls) produced by sinorhizobium meliloti 1021 induced significant differences in the accumulation of more than 100 polypeptides in early-log-phase cultures of the wild type. fifty-six of the corresponding proteins have been identified by peptide mass fingerprinting. the proteins affected by addition of these two ahls had diverse functions in carbon and nitrogen metabolism, energy cycles, metabolite transport, dna synthesi ... | 2003 | 12923075 |
| the sweet pepper ferredoxin-like protein (pflp) conferred resistance against soft rot disease in oncidium orchid. | genetic engineering to date has not been used to introduce disease resistance genes into the orchid gene pool. the ferredoxin-like protein gene originally isolated from sweet pepper is thought to function as a natural defense against infection due to its antimicrobial properties. hence it was reasoned that introduction of this gene might produce oncidium plants resistant to erwinia carotovora, the causal agent for the soft rot disease. an expression vector containing sweet pepper ferredoxin-like ... | 2003 | 12779121 |
| inhibition and alternate substrate studies on the mechanism of carbapenam synthetase from erwinia carotovora. | the erwinia carotorova cara, carb, and carc gene products are essential for the biosynthesis of (5r)-carbapen-2-em-3-carboxylic acid, the simplest carbapenem beta-lactam antibiotic. cara (hereafter named carbapenam synthetase) has been proposed to catalyze formation of (3s,5s)-carbapenam-3-carboxylic acid from (2s,5s)-5-carboxymethyl proline based on characterization of the products of fermentation experiments in escherichia coli cells transformed with pet24a/carb and pet24a/carab, and on sequen ... | 2003 | 12820893 |
| a novel potato defence-related alcohol:nadp+ oxidoreductase induced in response to erwinia carotovora. | identification of solanum tuberosum genes responsive to culture filtrates (cf) from erwinia carotovora subsp. carotovora led to the isolation of a full-length cdna with high sequence similarity to several alcohol dehydrogenases. accumulation of transcripts corresponding to this defence-related alcohol dehydrogenase (drd-1) was rapidly induced in cf-treated and wounded plants. the gene was also responsive to molecules involved in defence signalling such as salicylic acid, methyl jasmonate and eth ... | 2003 | 12825698 |
| erwinia carotovora subsp. carotovora and erwinia-derived elicitors hrpn and peha trigger distinct but interacting defense responses and cell death in arabidopsis. | we have used an hrp-positive strain of the soft rot pathogen erwinia carotovora subsp. carotovora to elucidate plant responses to this bacterial necrotroph. purified virulence determinants, harpin (hrpn) and polygalacturonase (peha), were used as tools to facilitate this analysis. we show that hrpn elicits lesion formation in arabidopsis and tobacco and triggers systemic resistance in arabidopsis. establishment of resistance is accompanied by the expression of salicylic acid (sa)-dependent, but ... | 2003 | 12650449 |
| enhanced resistance to phytophthora infestans and alternaria solani in leaves and tubers, respectively, of potato plants with decreased activity of the plastidic atp/adp transporter. | recently, it has been reported that tubers of transgenic potato ( solanum tuberosum l.) plants with decreased activity of the plastidic atp/adp transporter (aatp1) contain less starch, despite having an increased glucose level [p. geigenberger et al. (2001) plant physiol 125:1667-1678]. the metabolic alterations correlated with enhanced resistance to the bacterium erwinia carotovora. here it is shown that transgenic potato tubers, possessing less starch yet increased glucose levels due to the ex ... | 2003 | 12721851 |
| paex, a second pectin acetylesterase of erwinia chrysanthemi 3937. | erwinia chrysanthemi causes soft-rot diseases of various plants by enzymatic degradation of the pectin in plant cell walls. pectin is a complex polysaccharide. the main chain is constituted of galacturonate residues, and some of them are modified by methyl and/or acetyl esterification. esterases are necessary to remove these modifications and, thus, to facilitate the further degradation of the polysaccharidic chain. in addition to paey, the first pectin acetylesterase identified in the e. chrysa ... | 2003 | 12730169 |
| directed expression of the hiv-1 accessory protein vpu in drosophila fat-body cells inhibits toll-dependent immune responses. | human immunodeficiency virus 1 (hiv-1) expresses several accessory proteins that manipulate various host-cell processes to achieve optimum replicative efficiency. one of them, viral protein u (vpu), has been shown to interfere with the cellular degradation machinery through interaction with scf(beta-trcp) complexes. to learn more about vpu function in vivo, we used the genetically tractable fruit fly, drosophila melanogaster. our results show that the directed expression of vpu, but not the non- ... | 2003 | 12973300 |
| mechanism of pseudomonas aeruginosa rhlr transcriptional regulation of the rhlab promoter. | pseudomonas aeruginosa contains two transcription regulators (lasr and rhlr) that, when complexed with their specific autoinducers (3-oxo-dodecanoyl-homoserine lactone and butanoyl-homoserine lactone, respectively) activate transcription of different virulence-associated traits. we studied the rhlr-dependent transcriptional regulation of the rhlab operon encoding rhamnosyltransferase 1, an enzyme involved in the synthesis of the surfactant monorhamnolipid, and showed that rhlr binds to a specifi ... | 2003 | 14526008 |
| host specificity of mollicutes oric plasmids: functional analysis of replication origin. | recently, artificial oric plasmids containing the chromosomal dnaa gene and surrounding dnaa box sequences were obtained for the mollicutes spiroplasma citri and mycoplasma pulmonis. in order to study the specificity of these plasmids among mollicutes, a set of similar oric plasmids was developed for three mycoplasmas belonging to the mycoides cluster, mycoplasma mycoides subsp. mycoides lc (mmmlc), m.mycoides subsp. mycoides sc (mmmsc) and mycoplasma capricolum subsp. capricolum. mycoplasmas fr ... | 2003 | 14602921 |
| comparative study of regulatory mechanisms for pectinase production by erwinia carotovora subsp. carotovora and erwinia chrysanthemi. | the production of pectinase, the major virulence determinant of soft-rot erwinia species, is controlled by many regulatory factors. we focused on the major regulatory proteins, kdgr, crp, pir, and pecs, characterized mainly in e. chrysanthemi, and tested for their presence and function in the control of pectate lyase (pel) and polygalacturonase (peh) production in e. carotovora subsp. carotovora. homologues of kdgr and crp but not of pir and pecs were detected by southern blot analyses in e. car ... | 2003 | 12650454 |
| [expression of gene aiia carrying the promoter of gene cry3aa in bacillus thuringiensis]. | n-acyl-homoserine lactones (ahls), are widely conserved signal molecules present in quorum-sensing systems of many gram-negative bacteria. ahls molecules mediate the expression of virulence genes of a range of bacterial pathogens. recently, it has been reported that aiia protein, which widely exists in bacillus species, can inactivate the ahls by hydrolyzing the lactone bond of ahls, thus attenuate the diseases caused by the expression of virulence genes of bacterial pathogens. bacillus thuringi ... | 2003 | 15969053 |
| polygalacturonase from sitophilus oryzae: possible horizontal transfer of a pectinase gene from fungi to weevils. | endo-polygalacturonase, one of the group of enzymes known collectively as pectinases, is widely distributed in bacteria, plants and fungi. the enzyme has also been found in several weevil species and a few other insects, such as aphids, but not in drosophila melanogaster, anopheles gambiae, or caenorhabditis elegans or, as far as is known, in any more primitive animal species. what, then, is the genetic origin of the polygalacturonases in weevils? since some weevil species harbor symbiotic micro ... | 2003 | 15841240 |
| [purification and properties of recombinant erwinia carotovora l-asparaginase expressed in e.coli cells]. | the method of purification erwinia carotovora recombinant l-asparaginase, expressed in e.coli, including ultrasonic disintegration of biomass, fractionation ammonium sulfate and column chromatography on cm- or sp-sepharose has been developed. according to sds-paage the enzyme preparation was homogeneous, its specific activity and yield consist respectively about 620 iu/mg of protein and 75%. physical-chemical and structural properties of recombinant erwinia carotovora l-asparaginase are similar ... | 2003 | 16119104 |
| ethylene-insensitive tobacco shows differentially altered susceptibility to different pathogens. | abstract transgenic tobacco plants (tetr) expressing the mutant etr1-1 gene from arabidopsis thaliana are insensitive to ethylene and develop symptoms of wilting and stem rot when grown in nonautoclaved soil. several isolates of fusarium, thielaviopsis, and pythium were recovered from stems of diseased tetr plants. inoculation with each of these isolates of 6-week-old plants growing in autoclaved soil caused disease in tetr plants but not in nontransformed plants. also, when 2-week-old seedlings ... | 2003 | 18943162 |
| an oligonucleotide array for the identification and differentiation of bacteria pathogenic on potato. | abstract oligonucleotides, 16 to 24 bases long, were selected from the 3' end of the 16s gene and the 16s-23s intergenic spacer regions of bacteria pathogenic on potato, including clavibacter michiganensis subsp. sepedonicus, ralstonia solanacearum, and the pectolytic erwinias, including erwinia carotovora subsp. atroseptica and carotovora and e. chrysanthemi. oligonucleotides were designed and formatted into an array by pin spotting on nylon membranes. genomic dna from bacterial cultures was am ... | 2003 | 18944335 |
| salt stress activation of wound-related genes in tomato plants. | plants respond to various stresses by expressing distinct sets of genes. the effects of multiple stresses on plants and their interactions are not well understood. we have discovered that salt stress causes the accumulation of proteinase inhibitors and the activation of other wound-related genes in tomato (lycopersicon esculentum) plants. salt stress was also found to enhance the plant's response to wounding locally and systemically. the tomato mutant (def-1), which has an impairment in the octa ... | 2003 | 12913164 |
| modulation of cyp79 genes and glucosinolate profiles in arabidopsis by defense signaling pathways. | glucosinolates are natural plant products that function in the defense toward herbivores and pathogens. plant defense is regulated by multiple signal transduction pathways in which salicylic acid (sa), jasmonic acid, and ethylene function as signaling molecules. glucosinolate content was analyzed in arabidopsis wild-type plants in response to single or combinatorial treatments with methyljasmonate (meja), 2,6-dichloro-isonicotinic acid, ethylene, and 2,4-dichloro-phenoxyacetic acid, or by woundi ... | 2003 | 12529537 |
| a bypass of sucrose synthase leads to low internal oxygen and impaired metabolic performance in growing potato tubers. | plants possess two alternative biochemical pathways for sucrose (suc) degradation. one involves hydrolysis by invertase followed by phosphorylation via hexokinase and fructokinase, and the other route-which is unique to plants-involves a udp-dependent cleavage of suc that is catalyzed by suc synthase (susy). in the present work, we tested directly whether a bypass of the endogenous susy route by ectopic overexpression of invertase or suc phosphorylase affects internal oxygen levels in growing tu ... | 2003 | 12913161 |
| ethylene response factor1 integrates signals from ethylene and jasmonate pathways in plant defense. | cross-talk between ethylene and jasmonate signaling pathways determines the activation of a set of defense responses against pathogens and herbivores. however, the molecular mechanisms that underlie this cross-talk are poorly understood. here, we show that ethylene and jasmonate pathways converge in the transcriptional activation of ethylene response factor1 (erf1), which encodes a transcription factor that regulates the expression of pathogen response genes that prevent disease progression. the ... | 2003 | 12509529 |
| chemical communication among bacteria. | cell-cell communication in bacteria is accomplished through the exchange of chemical signal molecules called autoinducers. this process, called quorum sensing, allows bacteria to monitor their environment for the presence of other bacteria and to respond to fluctuations in the number and/or species present by altering particular behaviors. most quorum-sensing systems are species- or group-specific, which presumably prevents confusion in mixed-species environments. however, some quorum-sensing ci ... | 2003 | 12949263 |
| tmrdb (tmrna database). | maintained at the university of texas health science center at tyler, texas, the tmrna database (tmrdb) is accessible at the url http://psyche.uthct.edu/dbs/tmrdb/tmrdb.html with mirror sites located at auburn university, auburn, alabama (http://www.ag.auburn.edu/mirror/tmrdb/) and the bioinformatics research center, aarhus, denmark (http://www.bioinf.au.dk/tmrdb/). the tmrdb collects and distributes information relevant to the study of tmrna. in trans-translation, this molecule combines propert ... | 2003 | 12520048 |
| molecular basis of bacterial outer membrane permeability revisited. | gram-negative bacteria characteristically are surrounded by an additional membrane layer, the outer membrane. although outer membrane components often play important roles in the interaction of symbiotic or pathogenic bacteria with their host organisms, the major role of this membrane must usually be to serve as a permeability barrier to prevent the entry of noxious compounds and at the same time to allow the influx of nutrient molecules. this review summarizes the development in the field since ... | 2003 | 14665678 |
| interspecies communication in bacteria. | until recently, bacteria were considered to live rather asocial, reclusive lives. new research shows that, in fact, bacteria have elaborate chemical signaling systems that enable them to communicate within and between species. one signal, termed ai-2, appears to be universal and facilitates interspecies communication. many processes, including virulence factor production, biofilm formation, and motility, are controlled by ai-2. strategies that interfere with communication in bacteria are being e ... | 2003 | 14597753 |
| pharmacological inhibition of quorum sensing for the treatment of chronic bacterial infections. | traditional treatment of infectious diseases is based on compounds that aim to kill or inhibit bacterial growth. a major concern with this approach is the frequently observed development of resistance to antimicrobial compounds. the discovery of bacterial-communication systems (quorum-sensing systems), which orchestrate important temporal events during the infection process, has afforded a novel opportunity to ameliorate bacterial infection by means other than growth inhibition. compounds able t ... | 2003 | 14597754 |
| a new evaluation of our life-support system. | 2003 | 12949578 | |
| degradation of pathogen quorum-sensing molecules by soil bacteria: a preventive and curative biological control mechanism. | abstract the plasmid pme6863, carrying the aiia gene from the soil bacterium bacillus sp. a24 that encodes a lactonase enzyme able to degrade n-acyl-homoserine lactones (ahls), was introduced into the rhizosphere isolate pseudomonas fluorescens p3. this strain is not an effective biological control agent against plant pathogens. the transformant p. fluorescens p3/pme6863 acquired the ability to degrade ahls. in planta, p. fluorescens p3/pme6863 significantly reduced potato soft rot caused by erw ... | 2003 | 19719608 |
| soft rot erwiniae: from genes to genomes. | summary the soft rot erwiniae, erwinia carotovora ssp. atroseptica (eca), e. carotovora ssp. carotovora (ecc) and e. chrysanthemi (ech) are major bacterial pathogens of potato and other crops world-wide. we currently understand much about how these bacteria attack plants and protect themselves against plant defences. however, the processes underlying the establishment of infection, differences in host range and their ability to survive when not causing disease, largely remain a mystery. this rev ... | 2003 | 20569359 |
| down-regulation of photosystem i by erwinia carotovora-derived elicitors correlates with h(2)o(2) accumulation in chloroplasts of potato. | summary identification of solanum tuberosum genes responsive to culture filtrates (cf) from erwinia carotovora ssp. carotovora resulted in isolation of psad, a nuclear gene encoding the psi-d subunit of photosystem i (psi). this gene was rapidly and markedly down-regulated in cf-treated or wounded plants. down-regulation of psad transcripts was also triggered by signal molecules involved in plant defence such as methyl jasmonate. the cf-induced down-regulation of psad transcripts was correlated ... | 2004 | 20565588 |
| inter-genomic displacement via lateral gene transfer of bacterial trp operons in an overall context of vertical genealogy. | the growing conviction that lateral gene transfer plays a significant role in prokaryote genealogy opens up a need for comprehensive evaluations of gene-enzyme systems on a case-by-case basis. genes of tryptophan biosynthesis are frequently organized as whole-pathway operons, an attribute that is expected to facilitate multi-gene transfer in a single step. we have asked whether events of lateral gene transfer are sufficient to have obscured our ability to track the vertical genealogy that underp ... | 2004 | 15214963 |
| the homeobox gene caudal regulates constitutive local expression of antimicrobial peptide genes in drosophila epithelia. | in drosophila melanogaster, although the nf-kappab transcription factors play a pivotal role in the inducible expression of innate immune genes, such as antimicrobial peptide genes, the exact regulatory mechanism of the tissue-specific constitutive expression of these genes in barrier epithelia is largely unknown. here, we show that the drosophila homeobox gene product caudal functions as the innate immune transcription modulator that is responsible for the constitutive local expression of antim ... | 2004 | 14673153 |
| the wrky70 transcription factor: a node of convergence for jasmonate-mediated and salicylate-mediated signals in plant defense. | cross talk between salicylic acid (sa)- and jasmonic acid (ja)-dependent defense signaling has been well documented in plants, but how this cross talk is executed and the components involved remain to be elucidated. we demonstrate that the plant-specific transcription factor wrky70 is a common component in sa- and ja-mediated signal pathways. expression of wrky70 is activated by sa and repressed by ja. the early induction of wrky70 by sa is npr1-independent, but functional npr1 is required for f ... | 2004 | 14742872 |
| [genetic regulation of pathogenicity and virulence factors in bacteria erwinia carotovora subsp. atroseptica: phenotypic characteristic of bacteria with the mutant kdud gene]. | in contrast to the closely related bacteria erwinia chrysanthemi, bacteria erwinia carotovora subsp. atroseptica produce lower levels of main pathogenicity and virulence factors (pectate lyases, cellulases, and proteases) in the presence of pectins. this effect was shown to be connected with the accumulation of the intermediate product of intracellular degradation of these substances, 2,5-diketo-3-deoxygluconate (dk2). the presence of dk2 in the culture broth of mutant bacteria, connected to its ... | 2004 | 15559146 |
| potential ecotoxicological implication of methyl tert-butyl ether (mtbe) spills in the environment. | streptomyceticidal activity of methyl tert-butyl ether (mtbe) elucidated for the first time. adverse effect of mtbe, the gasoline additive, against 11 soil inhabitant streptomyces spp. isolates was investigated. mtbe, an octane enhancer is added to gasoline to reduce atmospheric concentrations of carbon monoxide and ozone. it contaminates soil and groundwater by fuel leaks and spills. streptomyces spp. are of the major contributors to the biological buffering of soils by exerting beneficial and ... | 2004 | 15673212 |
| sensitive and specific detection of xanthomonas campestris pv campestris by pcr using species-specific primers based on hrpf gene sequences. | a sensitive and specific assay was developed to detect bacterial black rot of crucifers caused by xanthomonas campestris pv. campestris (x. c. pv. campestris), in cabbage seed and plant. primers xcf and xcr from hrpf homologous to nolx, host recognition protein, were used to amplify a 525 bp dna fragment. pcr technique was applied to detect the pathogen in naturally infected seed and plant of cabbage. the pcr product was only produced from x. c. pv. campestris among 40 isolates of xanthomonas st ... | 2004 | 15646387 |
| structural and biochemical analysis of the asc operon encoding 6-phospho-beta-glucosidase in pectobacterium carotovorum subsp. carotovorum ly34. | an asc operon of pectobacterium carotovorum subsp. carotovorum ly34 (pcc ly34) was isolated from a genomic library in a screen for beta-glucosidase activities. sequence analysis of the 5618-bp cloned dna fragment (accession number ay622309) showed three open reading frames (ascg, ascf, and ascb) that are predicted to encode 375, 486, and 476 amino acid proteins, respectively. the ascg orf shared a high similarity with the escherichia coli ascg repressor. the ascf orf shared 81% identity with the ... | 2004 | 15748978 |
| peptidoglycan recognition protein (pgrp)-le and pgrp-lc act synergistically in drosophila immunity. | in innate immunity, pattern recognition molecules recognize cell wall components of microorganisms and activate subsequent immune responses, such as the induction of antimicrobial peptides and melanization in drosophila. the diaminopimelic acid (dap)-type peptidoglycan potently activates imd-dependent induction of antibacterial peptides. peptidoglycan recognition protein (pgrp) family members act as pattern recognition molecules. pgrp-lc loss-of-function mutations affect the imd-dependent induct ... | 2004 | 15538387 |
| the n terminus of bacterial elongation factor tu elicits innate immunity in arabidopsis plants. | innate immunity is based on the recognition of pathogen-associated molecular patterns (pamps). here, we show that elongation factor tu (ef-tu), the most abundant bacterial protein, acts as a pamp in arabidopsis thaliana and other brassicaceae. ef-tu is highly conserved in all bacteria and is known to be n-acetylated in escherichia coli. arabidopsis plants specifically recognize the n terminus of the protein, and an n-acetylated peptide comprising the first 18 amino acids, termed elf18, is fully ... | 2004 | 15548740 |
| plant defense gene promoter enhances the reliability of shiva-1 gene-induced resistance to soft rot disease in potato. | pal5, a tomato (lycopersicon esculentum mill.) plant defense gene that encodes phenylalanine ammonia-lyase, is known to respond to a variety of environmental stresses including pathogen infection and wounding. a shiva-1 gene recombinant that encodes a small synthetic antibacterial peptide under the pal5 gene promoter was transformed into potato (solanum tuberosum l.) and its ability to induce resistance to erwinia carotovora was compared with a construct under the control of the constitutive and ... | 2004 | 15309537 |
| involvement of n-acylhomoserine lactones throughout plant infection by erwinia carotovora subsp. atroseptica (pectobacterium atrosepticum). | erwinia carotovora subsp. atroseptica is responsible for potato blackleg disease in the field and tuber soft rot during crop storage. the process leading to the disease occurs in two phases: a primary invasion step followed by a maceration step. bacteria-to-bacteria communication is associated with a quorum-sensing (qs) process based on the production of n-acylhomoserine lactones (hsl). the role of hsl throughout plant infection was analyzed. to this purpose, hsl produced by a specific e. caroto ... | 2004 | 15553252 |
| analysis of bgl operon structure and characterization of beta-glucosidase from pectobacterium carotovorum subsp. carotovorum ly34. | a putative bgl operon of pectobacterium carotovorum subsp. carotovorum ly34 (pcc ly34) was isolated. sequence analysis of the 5,557 bp cloned dna fragment (accession no. ay542524) showed three open reading frames (bglt, bglp, and bglb) predicted to encode 287, 633, and 468 amino acid proteins respectively. bglt and bglp orfs show high similarity to that of the pectobacterium chrysanthemi arbg antiterminator and arbf permease respectively. also, the latter contains most residues important for pho ... | 2004 | 15564664 |
| identification and characterization of nip, necrosis-inducing virulence protein of erwinia carotovora subsp. carotovora. | erwinia carotovora subsp. carotovora is a gram-negative bacterium that causes soft rot disease of many cultivated crops. when a collection of e. carotovora subsp. carotovora isolates was analyzed on a southern blot using the harpin-encoding gene hrpn as probe, several harpinless isolates were found. regulation of virulence determinants in one of these, strain scc3193, has been characterized extensively. it is fully virulent on potato and in arabidopsis thaliana. an rpos (sigmas) mutant of scc319 ... | 2004 | 15597742 |
| chlorophyllase 1, a damage control enzyme, affects the balance between defense pathways in plants. | accumulation of reactive oxygen species (ros) is central to plant response to several pathogens. one of the sources of ros is the chloroplast because of the photoactive nature of the chlorophylls. chlorophyllase 1 (encoded by atclh1) of arabidopsis thaliana is quickly induced after tissue damage (e.g., caused by the bacterial necrotroph erwinia carotovora or the necrotrophic fungus alternaria brassicicola). rna interference silencing of atclh1 resulted in failure to degrade free chlorophyll afte ... | 2004 | 15598807 |
| antagonistic interaction between abscisic acid and jasmonate-ethylene signaling pathways modulates defense gene expression and disease resistance in arabidopsis. | the plant hormones abscisic acid (aba), jasmonic acid (ja), and ethylene are involved in diverse plant processes, including the regulation of gene expression during adaptive responses to abiotic and biotic stresses. previously, aba has been implicated in enhancing disease susceptibility in various plant species, but currently very little is known about the molecular mechanisms underlying this phenomenon. in this study, we obtained evidence that a complex interplay between aba and ja-ethylene sig ... | 2004 | 15548743 |
| [genetic regulation of pathogenicity and virulence factors in bacteria erwinia carotovora subsp. atroseptica: identification of kdud gene]. | a mutant that cannot utilize pectin substances of plant cell walls was obtained via insertion of mini-mini-tn5xyle transposon into the chromosome of phytopathogenic bacteria erwinia carotovora subsp. atroseptica. the inability of mutant cells to utilize these substrates was caused by a failure to accomplish the catabolism of unsaturated digalacturonic acid (uda). study of enzymatic activities has established that mutant bacteria lost the ability to produce 2,5-diketo-3-deoxygluconate dehydrogena ... | 2004 | 15559145 |
| identification of quorum-sensing signal molecules and the luxri homologs in fish pathogen edwardsiella tarda. | edwardsiella tarda is a gram-negative bacterium that causes septicaemia in fish and serious damage to the aquaculture industry. the virulence factors of this pathogen and control mechanisms of the expression of virulence genes have not yet been clearly elucidated. a number of gram-negative pathogenic bacteria have a quorum-sensing system. these bacteria produce n-acyl-l-homoserine lactone (ahl) that they use them as a quorum-sensing signal molecule. in this study, we found that e. tarda isolated ... | 2004 | 16233705 |
| integration of environmental and host-derived signals with quorum sensing during plant-microbe interactions. | many plant-associated microbes use secreted autoinducer molecules, including n-acylhomoserine lactones (ahls), to regulate diverse behaviours in association with their population density (quorum sensing). often, these responses are affected by environmental conditions, including the presence of other ahl-producing bacterial species. in addition, plant-derived metabolites, including products that arise as a direct result of the bacterial infection, may profoundly influence ahl-regulated behaviour ... | 2004 | 14764105 |
| evaluation of colilert-18 for detection of coliforms and eschericha coli in subtropical freshwater. | the accuracy of colilert-18 as a test for coliforms and escherichia coli in subtropical freshwater was evaluated by using api 20e strips and fatty acid methyl ester analysis. the false-positive and -negative rates of detection were 7.4 and 3.5%, respectively, for e. coli and 9.6 and 6.3%, respectively, for coliforms. | 2004 | 14766614 |
| quorum quenching: enzymatic disruption of n-acylhomoserine lactone-mediated bacterial communication in burkholderia thailandensis. | many species of gram-negative bacteria communicate by synthesizing, secreting, and responding to n-acylhomoserine lactones (ahls), a mechanism termed quorum sensing. several investigations have characterized numerous ahl-degrading enzymes (aiia lactonases) encoded by environmental isolates of bacillus spp. the burkholderia thailandensis quorum system is comprised of at least three ahl synthases (ahss) and five transcriptional regulators belonging to the luxir class of proteins. expression of the ... | 2004 | 15466564 |
| characterization of atypical erwinia carotovora strains causing blackleg of potato in brazil. | to determine the characteristics of bacteria associated with the blackleg disease of potato in brazil and compare them with species and subspecies of pectolytic erwinia. | 2004 | 14962133 |
| innate immunity in arabidopsis thaliana: lipopolysaccharides activate nitric oxide synthase (nos) and induce defense genes. | lipopolysaccharides (lps) are cell-surface components of gram-negative bacteria and are microbe-/pathogen-associated molecular patterns in animal pathosystems. as for plants, the molecular mechanisms of signal transduction in response to lps are not known. here, we show that arabidopsis thaliana reacts to lps with a rapid burst of no, a hallmark of innate immunity in animals. fifteen lps preparations (among them burkholderia cepacia, pseudomonas aeruginosa, and erwinia carotovora) as well as lip ... | 2004 | 15498873 |
| a drosophila p38 orthologue is required for environmental stress responses. | the p38 mitogen-activated protein kinase (mapk) cascade is an evolutionarily conserved signalling mechanism involved in processes as diverse as apoptosis, cell fate determination, immune function and stress response. aberrant p38 signalling has been implicated in many human diseases, including heart disease, cancer, arthritis and neurodegenerative diseases. to further understand the role of p38 in these processes, we generated a drosophila strain that is null for the d-p38a gene. mutants are hom ... | 2004 | 15514678 |
| in vivo production of active nickel superoxide dismutase from prochlorococcus marinus mit9313 is dependent on its cognate peptidase. | metal-dependent superoxide dismutases (sods) with a specific requirement for a manganese or iron ion for catalytic activity and copper- and zinc-dependent enzymes are essential for detoxification of superoxide anion radicals. genome sequence analyses predict the existence of a nickel-dependent enzyme (nisod) as the unique sod in oxygen-evolving marine cyanobacteria. nisod activity was observed in escherichia coli when sodn and sodx (encoding a putative peptidase) from prochlorococcus marinus mit ... | 2004 | 15516600 |
| antifungal activity of beta-asarone from rhizomes of acorus gramineus. | an antifungal substance was isolated from the extract of acorus gramineus using various chromatographic procedures. the antibiotic was identified as beta-asarone, cis-2,4,5-trimethoxy-1-propenylbenzene, on the basis of the high-resolution ei-mass, nmr, and uv spectral data. beta-asarone completely inhibited mycelial growth of some plant pathogenic fungi, cladosporium cucumerinum,colletotrichum orbiculare, magnaporthe grisea, and pythium ultimum, in a range of 0.5-30 microg/ml. the growth of baci ... | 2004 | 14969530 |
| inactivation of a pseudomonas aeruginosa quorum-sensing signal by human airway epithelia. | mammalian airways protect themselves from bacterial infection by using multiple defense mechanisms including antimicrobial peptides, mucociliary clearance, and phagocytic cells. we asked whether airways might also target a key bacterial cell-cell communication system, quorum-sensing. the opportunistic pathogen pseudomonas aeruginosa uses two quorum-sensing molecules, n-(3-oxododecanoyl)-l-homoserine lactone (3oc12-hsl) and n-butanoyl-l-homoserine lactone (c4-hsl), to control production of extrac ... | 2004 | 14970327 |
| ralstonia solanacearum iron scavenging by the siderophore staphyloferrin b is controlled by phca, the global virulence regulator. | phca is a transcriptional regulator that activates expression of multiple virulence genes in the plant pathogen ralstonia solanacearum. relative to their wild-type parents, phca mutants overproduced iron-scavenging activity detected with chrome azurol s siderophore detection medium. transposon mutagenesis of strain aw1-pc (phca1) generated strain gb6, which was siderophore negative but retained weak iron-scavenging activity. the ssd gene inactivated in gb6 encodes a protein similar to group iv a ... | 2004 | 15547261 |