| genomic structure and phylogeny of the plant pathogen ralstonia solanacearum inferred from gene distribution analysis. | in the present study, we investigated the gene distribution among strains of the highly polymorphic plant pathogenic beta-proteobacterium ralstonia solanacearum, paying particular attention to the status of known or candidate pathogenicity genes. based on the use of comparative genomic hybridization on a pangenomic microarray for the gmi1000 reference strain, we have defined the conditions that allowed comparison of the repertoires of genes among a collection of 18 strains that are representativ ... | 2007 | 17085551 |
| genomic structure and phylogeny of the plant pathogen ralstonia solanacearum inferred from gene distribution analysis. | in the present study, we investigated the gene distribution among strains of the highly polymorphic plant pathogenic beta-proteobacterium ralstonia solanacearum, paying particular attention to the status of known or candidate pathogenicity genes. based on the use of comparative genomic hybridization on a pangenomic microarray for the gmi1000 reference strain, we have defined the conditions that allowed comparison of the repertoires of genes among a collection of 18 strains that are representativ ... | 2007 | 17085551 |
| synthesis of n-acyl homoserine lactone analogues reveals strong activators of sdia, the salmonella enterica serovar typhimurium luxr homologue. | n-acyl homoserine lactones (ahls) are molecules that are synthesized and detected by many gram-negative bacteria to monitor the population density, a phenomenon known as quorum sensing. salmonella enterica serovar typhimurium is an exceptional species since it does not synthesize its own ahls, while it does encode a luxr homologue, sdia, which enables this bacterium to detect ahls that are produced by other species. to obtain more information about the specificity of the ligand binding by sdia, ... | 2007 | 17085703 |
| synthesis of n-acyl homoserine lactone analogues reveals strong activators of sdia, the salmonella enterica serovar typhimurium luxr homologue. | n-acyl homoserine lactones (ahls) are molecules that are synthesized and detected by many gram-negative bacteria to monitor the population density, a phenomenon known as quorum sensing. salmonella enterica serovar typhimurium is an exceptional species since it does not synthesize its own ahls, while it does encode a luxr homologue, sdia, which enables this bacterium to detect ahls that are produced by other species. to obtain more information about the specificity of the ligand binding by sdia, ... | 2007 | 17085703 |
| autoinducer-2 of the fire blight pathogen erwinia amylovora and other plant-associated bacteria. | autoinducers are important for cellular communication of bacteria. the luxs gene has a central role in the synthesis of autoinducer-2 (ai-2). the gene was identified in a shotgun library of erwinia amylovora and primers designed for pcr amplification from bacterial dna. supernatants of several erwinia amylovora strains were assayed for ai-2 activity with a vibrio harveyi mutant and were positive. many other plant-associated bacteria also showed ai-2 activity such as erwinia pyrifoliae and erwini ... | 2007 | 17092294 |
| the thiol:disulfide oxidoreductase dsbb mediates the oxidizing effects of the toxic metalloid tellurite (teo32-) on the plasma membrane redox system of the facultative phototroph rhodobacter capsulatus. | the highly toxic oxyanion tellurite (teo3(2-)) is a well known pro-oxidant in mammalian and bacterial cells. this work examines the effects of tellurite on the redox state of the electron transport chain of the facultative phototroph rhodobacter capsulatus, in relation to the role of the thiol:disulfide oxidoreductase dsbb. under steady-state respiration, the addition of tellurite (2.5 mm) to membrane fragments generated an extrareduction of the cytochrome pool (c- and b-type hemes); further, in ... | 2007 | 17098900 |
| the thiol:disulfide oxidoreductase dsbb mediates the oxidizing effects of the toxic metalloid tellurite (teo32-) on the plasma membrane redox system of the facultative phototroph rhodobacter capsulatus. | the highly toxic oxyanion tellurite (teo3(2-)) is a well known pro-oxidant in mammalian and bacterial cells. this work examines the effects of tellurite on the redox state of the electron transport chain of the facultative phototroph rhodobacter capsulatus, in relation to the role of the thiol:disulfide oxidoreductase dsbb. under steady-state respiration, the addition of tellurite (2.5 mm) to membrane fragments generated an extrareduction of the cytochrome pool (c- and b-type hemes); further, in ... | 2007 | 17098900 |
| [introduction of transpozon tn9 to endogenic plasmids of erwinia carotovora during lysogenization of cells by coliphage p1]. | it has been shown that phage p1 of escherichia coli is able not only to lysogenize the cells of erwinia carotovora but also to be a source of transpozon tn9 for mutagenesis of cryptic plasmids of this important phytopathogen. since the amount of the introduction in one of plasmids pca25::tn9 is 3.8 kb, at an average, it is supposed that tn9 is inherited as a double tandem structure. a convenient method is offered for selecting bacterial clones carrying the plasmid pca25::tn9 which is based on co ... | 2006 | 17100326 |
| detection and characterization of bacteria from the potato rhizosphere degrading n-acyl-homoserine lactone. | quorum sensing plays a role in the regulation of soft rot diseases caused by the plant pathogenic bacterium pectobacterium carotovorum subsp. carotovorum. the signal molecules involved in quorum sensing in p. carotovorum subsp. carotovorum belong to the group of n-acyl homoserine lactones (ahls). in our study, we screened bacteria isolated from the potato rhizosphere for the ability to degrade ahls produced by p. carotovorum subsp. carotovorum. six isolates able to degrade ahls were selected for ... | 2006 | 17110970 |
| novel type iv secretion system involved in propagation of genomic islands. | type iv secretion systems (t4sss) mediate horizontal gene transfer, thus contributing to genome plasticity, evolution of infectious pathogens, and dissemination of antibiotic resistance and other virulence traits. a gene cluster of the haemophilus influenzae genomic island icehin1056 has been identified as a t4ss involved in the propagation of genomic islands. this t4ss is novel and evolutionarily distant from the previously described systems. mutation analysis showed that inactivation of key ge ... | 2007 | 17122343 |
| novel type iv secretion system involved in propagation of genomic islands. | type iv secretion systems (t4sss) mediate horizontal gene transfer, thus contributing to genome plasticity, evolution of infectious pathogens, and dissemination of antibiotic resistance and other virulence traits. a gene cluster of the haemophilus influenzae genomic island icehin1056 has been identified as a t4ss involved in the propagation of genomic islands. this t4ss is novel and evolutionarily distant from the previously described systems. mutation analysis showed that inactivation of key ge ... | 2007 | 17122343 |
| the presence of n-terminal secretion signal sequences leads to strong stimulation of the total expression levels of three tested medically important proteins during high-cell-density cultivations of escherichia coli. | genetic optimizations to achieve high-level production of three different proteins of medical importance for humans, granulocyte-macrophage colony-stimulating factor (gm-csf), interferon alpha 2b (ifn-alpha2b), and single-chain antibody variable fragment (scfv-phox), were investigated during high-cell-density cultivations of escherichia coli. all three proteins were poorly expressed when put under control of the strong pm/xyls promoter/regulator system, but high volumetric yields of gm-csf and s ... | 2007 | 17142370 |
| the presence of n-terminal secretion signal sequences leads to strong stimulation of the total expression levels of three tested medically important proteins during high-cell-density cultivations of escherichia coli. | genetic optimizations to achieve high-level production of three different proteins of medical importance for humans, granulocyte-macrophage colony-stimulating factor (gm-csf), interferon alpha 2b (ifn-alpha2b), and single-chain antibody variable fragment (scfv-phox), were investigated during high-cell-density cultivations of escherichia coli. all three proteins were poorly expressed when put under control of the strong pm/xyls promoter/regulator system, but high volumetric yields of gm-csf and s ... | 2007 | 17142370 |
| atptr3, a wound-induced peptide transporter needed for defence against virulent bacterial pathogens in arabidopsis. | mutation in the wound-induced peptide transporter gene atptr3 (at5g46050) of arabidopsis thaliana has been shown to affect germination on media containing a high salt concentration. the heterologous expression in yeast was utilized to verify that the atptr3 protein transports di-and tripeptides. the t-dna insert in the atptr3-1 mutant in the arabidopsis ecotype c24 revealed two t-dna copies, the whole vector sequence, and the gus marker gene inserted in the second intron of the atptr3 gene. an a ... | 2007 | 17143616 |
| substrate recognition by the hetero-octameric atp phosphoribosyltransferase from lactococcus lactis. | two families of atp phosphoribosyl transferases (atp-prt) join atp and 5-phosphoribosyl-1 pyrophosphate (prpp) in the first reaction of histidine biosynthesis. these consist of a homohexameric form found in all three kingdoms and a hetero-octameric form largely restricted to bacteria. hetero-octameric atp-prts consist of four hisgs catalytic subunits related to periplasmic binding proteins and four hisz regulatory subunits that resemble histidyl-trna synthetases. to clarify the relationship betw ... | 2006 | 17154531 |
| hpar, a putative marr family transcriptional regulator, is positively controlled by hrpg and hrpx and involved in the pathogenesis, hypersensitive response, and extracellular protease production of xanthomonas campestris pathovar campestris. | the marr family of transcriptional regulators of bacteria are involved in the regulation of many cellular processes, including pathogenesis. in this work, we have demonstrated genetically that hpar (hpa, hrp associated), which encodes a putative marr family regulator, is involved in the hypersensitive response (hr), pathogenicity, and extracellular protease production of the phytopathogenic bacterium xanthomonas campestris pathovar campestris. a mutation in hpar resulted in complete loss of viru ... | 2007 | 17158655 |
| hpar, a putative marr family transcriptional regulator, is positively controlled by hrpg and hrpx and involved in the pathogenesis, hypersensitive response, and extracellular protease production of xanthomonas campestris pathovar campestris. | the marr family of transcriptional regulators of bacteria are involved in the regulation of many cellular processes, including pathogenesis. in this work, we have demonstrated genetically that hpar (hpa, hrp associated), which encodes a putative marr family regulator, is involved in the hypersensitive response (hr), pathogenicity, and extracellular protease production of the phytopathogenic bacterium xanthomonas campestris pathovar campestris. a mutation in hpar resulted in complete loss of viru ... | 2007 | 17158655 |
| characterization of the thermotoga maritima chemotaxis methylation system that lacks pentapeptide-dependent methyltransferase cher:mcp tethering. | sensory adaptation in bacterial chemotaxis is mediated by covalent modifications of specific glutamate and glutamine residues within the cytoplasmic domains of methyl-accepting chemotaxis proteins (mcps). in escherichia coli and salmonella enterica, efficient methylation of mcps depends on the localization of methyltransferase cher to mcp clusters through an interaction between the cher beta-subdomain and a pentapeptide sequence (nwetf or nwesf) at the c-terminus of the mcp. in vitro methylation ... | 2007 | 17163981 |
| characterization of the thermotoga maritima chemotaxis methylation system that lacks pentapeptide-dependent methyltransferase cher:mcp tethering. | sensory adaptation in bacterial chemotaxis is mediated by covalent modifications of specific glutamate and glutamine residues within the cytoplasmic domains of methyl-accepting chemotaxis proteins (mcps). in escherichia coli and salmonella enterica, efficient methylation of mcps depends on the localization of methyltransferase cher to mcp clusters through an interaction between the cher beta-subdomain and a pentapeptide sequence (nwetf or nwesf) at the c-terminus of the mcp. in vitro methylation ... | 2007 | 17163981 |
| high precision multi-genome scale reannotation of enzyme function by eficaz. | the functional annotation of most genes in newly sequenced genomes is inferred from similarity to previously characterized sequences, an annotation strategy that often leads to erroneous assignments. we have performed a reannotation of 245 genomes using an updated version of eficaz, a highly precise method for enzyme function prediction. | 2006 | 17166279 |
| the complete genome sequence and comparative genome analysis of the high pathogenicity yersinia enterocolitica strain 8081. | the human enteropathogen, yersinia enterocolitica, is a significant link in the range of yersinia pathologies extending from mild gastroenteritis to bubonic plague. comparison at the genomic level is a key step in our understanding of the genetic basis for this pathogenicity spectrum. here we report the genome of y. enterocolitica strain 8081 (serotype 0:8; biotype 1b) and extensive microarray data relating to the genetic diversity of the y. enterocolitica species. our analysis reveals that the ... | 2006 | 17173484 |
| global effect of indole-3-acetic acid biosynthesis on multiple virulence factors of erwinia chrysanthemi 3937. | production of the plant hormone indole-3-acetic acid (iaa) is widespread among plant-associated microorganisms. the non-gall-forming phytopathogen erwinia chrysanthemi 3937 (strain ech3937) possesses iaam (asap16562) and iaah (asap16563) gene homologues. in this work, the null knockout iaam mutant strain ech138 was constructed. the iaa production by ech138 was reduced in m9 minimal medium supplemented with l-tryptophan. compared with wild-type ech3937, ech138 exhibited reduced ability to produce ... | 2007 | 17189441 |
| global effect of indole-3-acetic acid biosynthesis on multiple virulence factors of erwinia chrysanthemi 3937. | production of the plant hormone indole-3-acetic acid (iaa) is widespread among plant-associated microorganisms. the non-gall-forming phytopathogen erwinia chrysanthemi 3937 (strain ech3937) possesses iaam (asap16562) and iaah (asap16563) gene homologues. in this work, the null knockout iaam mutant strain ech138 was constructed. the iaa production by ech138 was reduced in m9 minimal medium supplemented with l-tryptophan. compared with wild-type ech3937, ech138 exhibited reduced ability to produce ... | 2007 | 17189441 |
| low-abundance kutznerides from kutzneria sp. 744. | five new (5-9) and four known (1-4) kutznerides were isolated from the actinomycete kutzneria sp. 744. compounds 1-9 all consisted of a cyclohexadepsipeptide core with the general structure 2-(1-methylcyclopropyl)-d-glycine-(2s,3ar,8as)-6,7-dichloro-3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid-3-hydroxy-d-glutamic acid-o-methyl-l-serine-l-piperazic acid-(s)-2-hydroxy-3,3-dimethylbutyric acid. compounds 5, 6, and 8 contained erythro-3-hydroxy-d-glutamic acid, whereas 7 ... | 2006 | 17190458 |
| phytotoxicity and innate immune responses induced by nep1-like proteins. | we show that oomycete-derived nep1 (for necrosis and ethylene-inducing peptide1)-like proteins (nlps) trigger a comprehensive immune response in arabidopsis thaliana, comprising posttranslational activation of mitogen-activated protein kinase activity, deposition of callose, production of nitric oxide, reactive oxygen intermediates, ethylene, and the phytoalexin camalexin, as well as cell death. transcript profiling experiments revealed that nlps trigger extensive reprogramming of the arabidopsi ... | 2006 | 17194768 |
| diversity of the abundant pklc102/pagi-2 family of genomic islands in pseudomonas aeruginosa. | the known genomic islands of pseudomonas aeruginosa clone c strains are integrated into trna(lys) (pklc102) or trna(gly) (pagi-2 and pagi-3) genes and differ from their core genomes by distinctive tetranucleotide usage patterns. pklc102 and the related island papi-1 from p. aeruginosa pa14 were spontaneously mobilized from their host chromosomes at frequencies of 10% and 0.3%, making pklc102 the most mobile genomic island known with a copy number of 30 episomal circular pklc102 molecules per cel ... | 2007 | 17194795 |
| diversity of the abundant pklc102/pagi-2 family of genomic islands in pseudomonas aeruginosa. | the known genomic islands of pseudomonas aeruginosa clone c strains are integrated into trna(lys) (pklc102) or trna(gly) (pagi-2 and pagi-3) genes and differ from their core genomes by distinctive tetranucleotide usage patterns. pklc102 and the related island papi-1 from p. aeruginosa pa14 were spontaneously mobilized from their host chromosomes at frequencies of 10% and 0.3%, making pklc102 the most mobile genomic island known with a copy number of 30 episomal circular pklc102 molecules per cel ... | 2007 | 17194795 |
| functional analysis of arabidopsis wrky25 transcription factor in plant defense against pseudomonas syringae. | a common feature of plant defense responses is the transcriptional regulation of a large number of genes upon pathogen infection or treatment with pathogen elicitors. a large body of evidence suggests that plant wrky transcription factors are involved in plant defense including transcriptional regulation of plant host genes in response to pathogen infection. however, there is only limited information about the roles of specific wrky dna-binding transcription factors in plant defense. | 2007 | 17214894 |
| fusion of the genes for ahl-lactonase and s-layer protein in bacillus thuringiensis increases its ability to inhibit soft rot caused by erwinia carotovora. | two genes, ctc and ctc2, responsible for surface layer (s-layer) protein synthesis in bacillus thuringiensis ctc, were mutated and resulted in b. thuringiensis tr5. to synthesize and express the n-acyl-homoserine lactonase (ahl-lactonase) in the extracellular space of b. thuringiensis, the aiia ( 4q7 ) gene (an ahl-lactonase gene from b. thuringiensis 4q7), which confers the ability to inhibit plant soft rot disease in b. thuringiensis 4q7, was fused with the upstream sequence of the ctc gene, w ... | 2007 | 17216466 |
| acid ph activation of the pmra/pmrb two-component regulatory system of salmonella enterica. | acid ph often triggers changes in gene expression. however, little is known about the identity of the gene products that sense fluctuations in extracytoplasmic ph. the gram-negative pathogen salmonella enterica serovar typhimurium experiences a number of acidic environments both inside and outside animal hosts. growth in mild acid (ph 5.8) promotes transcription of genes activated by the response regulator pmra, but the signalling pathway(s) that mediates this response has thus far remained unex ... | 2007 | 17229213 |
| [phage system for studying the restriction-modification of erwinia carotovora]. | a model for revealing and type identifying the systems of restriction-modification of phytopathogenic bacterium ewinia carotovora with the help of two virulent polyvalent phages-fe 44 and t7 is proposed in the work. the joint use of the phages permits to identify both the limitations of phages development on the part of rm-systems of three major types, and on the part of the competing episomes. the proposed system also allows to reveal other kinds of limitations, in particular those connected wi ... | 2006 | 17243364 |
| [intragenome heterogeneity of the temperate bacteriophage zf40 erwinia carotovora]. | it has been shown that the temperate bacteriophage zf40 erwinia carotovora combines in it two kinds of intragenome heterogeneity--cyclic permutation and cohesive end structures. the latter reassociate more quickly than analogous cos-sites of the phage lambda escherichia coli. a series of clear-mutants was found after the temperature inactivation of the phage particles; they are the components of the complementation group being involved in the repressor gene. one of the mutants, zf40c(5/5), was i ... | 2006 | 17243365 |
| salmonella typhimurium flhe, a conserved flagellar regulon gene required for swarming. | the salmonella typhimurium gene flhe is located at the end of a large flagellar locus in at least 10 peritrichously flagellated gram-negative bacterial genera, but it shares no significant similarity with other genes. this study shows that flhe is transcribed as part of an flhbae flagellar operon, under the control of the flagellar master regulator flhd(2)c(2). deletion of the chromosomal flhe gene did not affect swimming motility, but it abolished swarming motility across solid agar. swarming w ... | 2007 | 17259626 |
| characterization of the signaling domain of the no-responsive regulator norr from ralstonia eutropha h16 by site-directed mutagenesis. | in ralstonia eutropha h16, the nitric oxide (no)-responsive transcriptional activator norr controls the expression of a dicistronic operon that encodes a membrane-bound no reductase, norb, and a protein of unknown function, nora. the n-terminal domain (ntd) of norr is responsible for perception of the signal molecule, nitric oxide. thirteen out of 29 conserved residues of the ntd were exchanged by site-directed mutagenesis. replacement of r63, r72, d93, d96, c112, d130, or f137 strongly decrease ... | 2007 | 17277050 |
| species-specific functioning of the pseudomonas xcpq secretin: role for the c-terminal homology domain and lipopolysaccharide. | secretins are oligomeric proteins that mediate the export of macromolecules across the bacterial outer membrane. the members of the secretin superfamily possess a c-terminal homology domain that is important for oligomerization and channel formation, while their n-terminal halves are thought to be involved in system-specific interactions. the xcpq secretin of pseudomonas spp. is a component of the type ii secretion pathway. xcpq from pseudomonas alcaligenes is not able to functionally replace th ... | 2007 | 17277064 |
| interplay between crp-camp and pii-ntr systems forms novel regulatory network between carbon metabolism and nitrogen assimilation in escherichia coli. | in escherichia coli, utilization of carbon sources is regulated by the phosphoenolpyruvate-dependent phosphotransferase system (pts), which modulates the intracellular levels of camp. the camp receptor protein (crp) controls the transcription of many catabolic genes. the availability of nitrogen is sensed by the pii protein at the level of intracellular glutamine. glutamine is transported mainly by glnhpq, and synthesized by glutamine synthetase (gs) encoded by glna. previous studies suggest tha ... | 2007 | 17284458 |
| purification of l-asparaginase from a bacteria erwinia carotovora and effect of a dihydropyrimidine derivative on some of its kinetic parameters. | l-asparaginase shows antileukemic activity and is generally administered in the body in combination with other anticancer drugs like pyrimidine derivatives. in the present study, l-asparaginase was purified from a bacteria erwinia carotovora and the effect of a dihydropyrimidine derivative (1-amino-6-methyl-4-phenyl-2-thioxo, 1,2,3,4-tetrahydropyrimidine-5-carboxylic acid methyl ester) was studied on the kinetic parameters km and vmax of the enzyme using l-asparagine as substrate. the enzyme had ... | 2006 | 17285805 |
| cross talk between type iii secretion and flagellar assembly systems in pseudomonas aeruginosa. | pseudomonas aeruginosa cytotoxicity is linked to a type iii secretion system (t3ss) that delivers effectors into the host cell. we show here that a negative cross-control exists between t3ss and flagellar assembly. we observed that, in a strain lacking flagella, t3ss gene expression, effector secretion, and cytotoxicity were increased. conversely, we revealed that flagellar-gene expression and motility were decreased in a strain overproducing exsa, the t3ss master regulator. interestingly, a non ... | 2007 | 17307856 |
| plant carbohydrate scavenging through tonb-dependent receptors: a feature shared by phytopathogenic and aquatic bacteria. | tonb-dependent receptors (tbdrs) are outer membrane proteins mainly known for the active transport of iron siderophore complexes in gram-negative bacteria. analysis of the genome of the phytopathogenic bacterium xanthomonas campestris pv. campestris (xcc), predicts 72 tbdrs. such an overrepresentation is common in xanthomonas species but is limited to only a small number of bacteria. here, we show that one xcc tbdr transports sucrose with a very high affinity, suggesting that it might be a sucro ... | 2007 | 17311090 |
| tailoring structure-function properties of l-asparaginase: engineering resistance to trypsin cleavage. | bacterial l-asnases (l-asparaginases) catalyse the conversion of l-asparagine into l-aspartate and ammonia, and are widely used for the treatment of all (acute lymphoblastic leukaemia). in the present paper, we describe an efficient approach, based on protein chemistry and protein engineering studies, for the construction of trypsin-resistant pegylated l-asnase from erwinia carotovora (ecal-asnase). limited proteolysis of ecal-asnase with trypsin was found to be associated with a first cleavage ... | 2007 | 17313368 |
| comparative genomic analysis of regulation of anaerobic respiration in ten genomes from three families of gamma-proteobacteria (enterobacteriaceae, pasteurellaceae, vibrionaceae). | gamma-proteobacteria, such as escherichia coli, can use a variety of respiratory substrates employing numerous aerobic and anaerobic respiratory systems controlled by multiple transcription regulators. thus, in e. coli, global control of respiration is mediated by four transcription factors, fnr, arca, narl and narp. however, in other gamma-proteobacteria the composition of global respiration regulators may be different. | 2007 | 17313674 |
| a pair of highly conserved two-component systems participates in the regulation of the hypervariable fir proteins in different legionella species. | legionella pneumophila and other pathogenic legionella species multiply inside protozoa and human macrophages by using the icm/dot type iv secretion system. the icmq protein, which possesses pore-forming activity, and icmr, which functions as its chaperone, are two essential components of this system. it was previously shown that in 29 legionella species, a large hypervariable-gene family (fir genes) is located upstream from a conserved icmq gene, but although nonhomologous, the fir proteins wer ... | 2007 | 17337587 |
| cross-kingdom signalling: exploitation of bacterial quorum sensing molecules by the green seaweed ulva. | the green seaweed ulva has been shown to detect signal molecules produced by bacteria. biofilms that release n-acylhomoserine lactones (ahls) attract zoospores--the motile reproductive stages of ulva. the evidence for ahl involvement is based on several independent lines of evidence, including the observation that zoospores are attracted to wild-type bacteria that produce ahls but are not attracted to mutants that do not produce signal molecules. synthetic ahl also attracts zoospores and the att ... | 2007 | 17360272 |
| quorum-quenching microbial infections: mechanisms and implications. | | 2007 | 17360274 |
| quorum sensing, virulence and secondary metabolite production in plant soft-rotting bacteria. | quorum sensing describes the ability of bacteria to sense their population density and respond by modulating gene expression. in the plant soft-rotting bacteria, such as erwinia, an arsenal of plant cell wall-degrading enzymes is produced in a cell density-dependent manner, which causes maceration of plant tissue. however, quorum sensing is central not only to controlling the production of such destructive enzymes, but also to the control of a number of other virulence determinants and secondary ... | 2007 | 17360277 |
| quorum-sensing regulation in rhizobia and its role in symbiotic interactions with legumes. | legume-nodulating bacteria (rhizobia) usually produce n-acyl homoserine lactones, which regulate the induction of gene expression in a quorum-sensing (or population-density)-dependent manner. there is significant diversity in the types of quorum-sensing regulatory systems that are present in different rhizobia and no two independent isolates worked on in detail have the same complement of quorum-sensing genes. the genes regulated by quorum sensing appear to be rather diverse and many are associa ... | 2007 | 17360278 |
| burkholderia hep_hag autotransporter (buha) proteins elicit a strong antibody response during experimental glanders but not human melioidosis. | the bacterial biothreat agents burkholderia mallei and burkholderia pseudomallei are the cause of glanders and melioidosis, respectively. genomic and epidemiological studies have shown that b. mallei is a recently emerged, host restricted clone of b. pseudomallei. | 2007 | 17362501 |
| using aqueous chlorine dioxide to prevent contamination of tomatoes with salmonella enterica and erwinia carotovora during fruit washing. | chlorine dioxide (clo2) is an antimicrobial agent recognized for its disinfectant properties. in this study, the sanitizing effects of clo2 solutions against salmonella enterica and erwinia carotovora in water, on tomato surfaces, and between loads of tomatoes were evaluated. in water, clo2 at 5, 10, and 20 ppm caused a > or = 5-log reduction of s. enterica within 6, 4, and 2 s, respectively. higher lethality was observed with e. carotovora; a 5-log reduction was achieved after only 2 s with 10 ... | 2007 | 17388051 |
| sigmae-dependent small rnas of salmonella respond to membrane stress by accelerating global omp mrna decay. | the bacterial envelope stress response (esr) is triggered by the accumulation of misfolded outer membrane proteins (omps) upon envelope damage or excessive omp synthesis, and is mediated by the alternative sigma factor, sigmae. activation of the ge pathway causes a rapid downregulation of major omp mrnas, which prevents further build-up of unassembled omps and liberates the translocation and folding apparatus under conditions that require envelope remodelling. the factors that facilitate the rap ... | 2006 | 17427289 |
| [modification of recombinant asparaginase from erwinia carotovora with polyethylene glycol 5000]. | a method for polyethylene conjugation with recombinant asparaginase has been developed to improve therapeutically important properties of this enzyme. methoxy-nitrophenyl carbamate of polyethylene glycol with molecular weight 5000 was employed as the modification reagent. optimization of pegylation procedure allowed achieving high level of the enzyme modification. under 4.5 molar excess of modification reagent more than 10 molecules of methoxy-polyethylene bound per one asparaginase molecular. t ... | 2007 | 17436691 |
| crystal structure and allosteric regulation of the cytoplasmic escherichia coli l-asparaginase i. | ansa is the cytoplasmic asparaginase from escherichia coli involved in intracellular asparagine utilization. analytical ultracentifugation and x-ray crystallography reveal that ansa forms a tetrameric structure as a dimer of two intimate dimers. kinetic analysis of the enzyme reveals that ansa is positively cooperative, displaying a sigmoidal substrate dependence curve with an [s](0.5) of 1 mm l-asparagine and a hill coefficient (n(h)) of 2.6. binding of l-asparagine to an allosteric site was ob ... | 2007 | 17451745 |
| solution structure of domains iva and v of the tau subunit of escherichia coli dna polymerase iii and interaction with the alpha subunit. | the solution structure of the c-terminal domain v of the tau subunit of e. coli dna polymerase iii was determined by nuclear magnetic resonance (nmr) spectroscopy. the fold is unique to tau subunits. amino acid sequence conservation is pronounced for hydrophobic residues that form the structural core of the protein, indicating that the fold is representative for tau subunits from a wide range of different bacteria. the interaction between the polymerase subunits tau and alpha was studied by nmr ... | 2007 | 17452361 |
| thermoregulation of n-acyl homoserine lactone-based quorum sensing in the soft rot bacterium pectobacterium atrosepticum. | the psychrotolerant bacterium pectobacterium atrosepticum produces four n-acyl homoserine lactones under a wide range of temperatures. their thermoregulation differs from that of the exoenzyme production, described as being under quorum-sensing control. a mechanism involved in this thermoregulation consists of controlling n-acyl homoserine lactones synthase production at a transcriptional level. | 2007 | 17468275 |
| directed evolution for increased chitinase activity. | directed evolution through dna shuffling and screening was used to enhance the catalytic ability of a fungal, beauveria bassiana, chitinase, bbchit1. the bbchit gene was first linked to various prokaryotic signal sequences and expressed in escherichia coli. the signal peptide, pelb, from erwinia carotovora resulted in greatest chitinase secretion into broth. the nucleotide sequence expressing pelb signal peptide was then incorporated into an e. coli vector to express bbchit1 variants generated b ... | 2007 | 17468866 |
| characterization of the zinc-containing metalloprotease encoded by zpx and development of a species-specific detection method for enterobacter sakazakii. | enterobacter sakazakii causes a severe form of neonatal meningitis that occurs as sporadic cases as well as outbreaks. the disease has been epidemiologically associated with consumption of reconstituted, dried infant formulas. very little information is available regarding pathogenicity of the organism and production of virulence factors. clinical and environmental strains were screened for production of factors which have activity against chinese hamster ovary (cho) cells in tissue culture. pol ... | 2007 | 17483271 |
| two-dimensional fluorescence difference gel electrophoresis for comparative proteomics profiling. | quantitative proteomics is the workhorse of the modern proteomics initiative. the gel-based and mudpit approaches have facilitated vital advances in the measurement of protein expression alterations in normal and disease phenotypic states. the methodological advance in two-dimensional gel electrophoresis (2dge) has been the multiplexing fluorescent two-dimensional fluorescence difference gel electrophoresis (2d-dige). 2d-dige is based on direct labeling of lysine groups on proteins with cyanine ... | 2006 | 17487156 |
| [physico-chemical properties of temperate bacteriophage zf40 of erwinia carotovora]. | a method of efficient purification of the extremely instable virions of the temperate bacteriophage zf40 of erwinia carotovora was proposed in the work. the stage-by-stage centrifugation in mentrizamide and caesium chloride gradients permitted to obtain highly purified phage preparations which were used for studying the protein composition of the studied erwiniophage. it was established that the buoyant density of the phage zf40 was 1.23 g/cm3, 1.49 g/cm3 and 1.27 g/cm3 in the gradients of metri ... | 2007 | 17494330 |
| [nature of the cryptic plasmid pca25 of erwinia carotovora subsp. carotovora 48a]. | high specificity of tn9 transposition into the cryptic plasmid pca25 of erwinia carotovora subsp. carotovora 48a was established on the basis of the comparative restriction analysis of dna by endonucleases ecorv and psti. under the extremal conditions of growth (1% sds) the plasmid pca25:: tn9 loses about 50 % of transpozone sequence, however the cells are not healed of extrachromosomal dna. the inheritance stability, side by side with site-specific transposition and deleting of tn9, confirms a ... | 2007 | 17494331 |
| crystal structure of rseb and a model of its binding mode to rsea. | the bacterial envelope stress response senses stress signals in the extracytoplasmic compartment, and activates sigma(e)-dependent transcription by degrading its antisigma factor rsea. rseb, a binding partner of rsea, plays a pivotal role in regulating this response, but its molecular mechanism is not understood. we therefore determined the crystal structure of escherichia coli rseb at a resolution of 2.4 a. rseb is composed of two domains linked by a flexible linker and forms a loosely packed d ... | 2007 | 17496148 |
| the map kinase kinase mkk2 affects disease resistance in arabidopsis. | the arabidopsis mitogen-activated protein kinase (mapk) kinase 2 (mkk2) was shown to mediate cold and salt stress responses through activation of the two map kinases mpk4 and mpk6. transcriptome analysis of plants expressing constitutively active mkk2 (mkk2-ee plants) showed altered expression of genes induced by abiotic stresses but also a significant number of genes involved in defense responses. both mpk4 and mpk6 became rapidly activated upon pseudomonas syringae pv. tomato dc3000 infection ... | 2007 | 17506336 |
| indole is an inter-species biofilm signal mediated by sdia. | as a stationary phase signal, indole is secreted in large quantities into rich medium by escherichia coli and has been shown to control several genes (e.g., astd, tnab, gabt), multi-drug exporters, and the pathogenicity island of e. coli; however, its impact on biofilm formation has not been well-studied. | 2007 | 17511876 |
| the crystal structure of the pentahaem c-type cytochrome nrfb and characterization of its solution-state interaction with the pentahaem nitrite reductase nrfa. | nrfb is a small pentahaem electron-transfer protein widely involved in the respiratory reduction of nitrite or nitric oxide to ammonia, processes that provide energy for anaerobic metabolism in many enteric bacteria and also serve to detoxify these reactive nitrogen species. the x-ray crystal structure of escherichia coli nrfb is presented at 1.74 a (1 a=0.1 nm) resolution. the architecture of the protein is that of a 40 a 'nanowire' in which the five haems are positioned within 6 a of each othe ... | 2007 | 17521287 |
| characterization of a broad range antibacterial substance from a new bacillus species isolated from amazon basin. | a bacillus sp. strain producing a bacteriocin-like substance was characterized by biochemical profiling and 16s rdna sequencing. the phylogenetic analysis indicated that this strain has low sequence similarity with most bacillus spp., suggesting a new species was isolated. the antimicrobial activity was detected starting at the exponential growth phase, and maximum activity was observed at stationary phase. the substance was inhibitory to a broad range of indicator strains, including pathogenic ... | 2007 | 17534601 |
| genetic flux over time in the salmonella lineage. | dna sequences that are shared between closely related organisms while being absent from their common ancestor and from sister lineages of that ancestor are likely to have been acquired by horizontal gene transfer. over time, the composition of those sequences tends to become more similar to the compositional signature of their host (amelioration). | 2007 | 17547764 |
| [study of hrpn(csds001) and the gene expression profile of arabidopsis thaliana induced by harpin(csds001)]. | erwinia carotovora subsp. carotovora csds001 elicits hypersensitive reaction (hr) in tobacco. from the genomic libraries of erwinia carotovora subsp. carotovora csds001, the hrpncsds001 gene (genbank number ay939927), was isolated. the hrpncsds001 fusion protein was produced in escherichia coli, and was used to induce hr by injecting into tobacco. we further examined the global regulation of arabidopsis thaliana genes in response to harpincsds001 at a concentration of 30 miccrog/ml. we indicated ... | 2007 | 17548335 |
| [isolation and identification of rhodosporidium toruloides r1 degrading n-acyl homoserine lactone]. | in the present study, a ahl-utilizing strain ri was isolated and identified as the genus rhodosporidium toruloides r1 by physi-biochemical approaches and 18s rdna sequence analysis, and this strain was designated as r. toruloides r1. results showed that r. toruloides r1 exhibited the ability to utilize and degrade the all n-acyl homoserine lactones tested in this study. coculture of r. toruloides r1 with erwinia carotovora subsp. carotovora effectively inhibit the soft rot disease of patato caus ... | 2007 | 17552249 |
| involvement of a quorum-sensing-regulated lipase secreted by a clinical isolate of burkholderia glumae in severe disease symptoms in rice. | burkholderia glumae is an emerging rice pathogen in several areas around the world. closely related burkholderia species are important opportunistic human pathogens for specific groups of patients, such as patients with cystic fibrosis and patients with chronic granulomatous disease. here we report that the first clinical isolate of b. glumae, strain au6208, has retained its capability to be very pathogenic to rice. as previously reported for rice isolate b. glumae bgr1 (and also for the clinica ... | 2007 | 17557855 |
| the rcs phosphorelay modulates the expression of plant cell wall degrading enzymes and virulence in pectobacterium carotovorum ssp. carotovorum. | production of plant cell wall degrading enzymes, the major virulence factors of soft-rot pectobacterium species, is controlled by many regulatory factors. pectobacterium carotovorum ssp. carotovorum scc3193 encodes an rcs phosphorelay system that involves two sensor kinases, rcsc(pcc) and rcsd(pcc), and a response regulator rcsb(pcc) as key components of this system, and an additional small lipoprotein rcsf(pcc). this study indicates that inactivation of rcsc(pcc), rcsd(pcc) and rcsb(pcc) enhanc ... | 2007 | 17561945 |
| the identification of antibacterial compounds for the development of enhanced media for the detection of foodborne fungi. | in an effort to identify a more suitable antibiotic for utilization in mycological media, 12 food borne fungal species from various genera including alternaria alternata, aspergillus flavus, a. niger, eurotium chevalieri, fusarium moniliforme, penicillium sp., rhizopus stolonifer, saccharomyces cerevisiae, candida tropicalis, geotrichum candidum, rhodotorula glutinis and kluyveromyces thermotolerans along with 21 chloramphenicol-resistant bacterial isolates from fresh produce and atcc cultures o ... | 2007 | 17574697 |
| mptpb, a virulence factor from mycobacterium tuberculosis, exhibits triple-specificity phosphatase activity. | bacterial pathogens have developed sophisticated mechanisms of evading the immune system to survive in infected host cells. central to the pathogenesis of mycobacterium tuberculosis is the arrest of phagosome maturation, partly through interference with ptdins signalling. the protein phosphatase mptpb is an essential secreted virulence factor in m. tuberculosis. a combination of bioinformatics analysis, enzyme kinetics and substrate-specificity characterization revealed that mptpb exhibits both ... | 2007 | 17584180 |
| two-component response regulators of vibrio fischeri: identification, mutagenesis, and characterization. | two-component signal transduction systems are utilized by prokaryotic and eukaryotic cells to sense and respond to environmental stimuli, both to maintain homeostasis and to rapidly adapt to changing conditions. studies have begun to emerge that utilize a large-scale mutagenesis approach to analyzing these systems in prokaryotic organisms. due to the recent availability of its genome sequence, such a global approach is now possible for the marine bioluminescent bacterium vibrio fischeri, which e ... | 2007 | 17586650 |
| detecting laterally transferred genes: use of entropic clustering methods and genome position. | most parametric methods for detecting foreign genes in bacterial genomes use a scoring function that measures the atypicality of a gene with respect to the bulk of the genome. genes whose features are sufficiently atypical-lying beyond a threshold value-are deemed foreign. yet these methods fail when the range of features of donor genomes overlaps with that of the recipient genome, leading to misclassification of foreign and native genes; existing parametric methods choose threshold parameters t ... | 2007 | 17591616 |
| inhibition of quorum sensing-regulated behaviors by scorzonera sandrasica. | many gram-negative bacteria use n-acyl homoserine lactone signal molecules to monitor their own population density and coordinate gene regulation in a process called quorum sensing (qs). increasing evidence implies that certain eukaryotes produce qs-inhibitory compounds. in this work, we tested 46 terrestrial plants materials for their ability to inhibit qs-regulated behaviors in different bacterial species. plant materials were dried and extracted using different solvents. the chloroform-solubl ... | 2007 | 17597339 |
| conservation of transcriptional sensing systems in prokaryotes: a perspective from escherichia coli. | the activity of transcription factors is usually governed by allosteric physicochemical signals or metabolites, which are in turn produced in the cell or obtained from the environment by the activity of the products of effector genes. previously, we identified a collection of more than 110 transcription factors and their corresponding effector genes in escherichia coli k-12. here, we introduce the notion of "triferog", which relates to the identification of orthologous transcription factors and ... | 2007 | 17617412 |
| study of the mode of action of a polygalacturonase from the phytopathogen burkholderia cepacia. | we have recently isolated and heterologously expressed bcpeh28a, an endopolygalacturonase from the phytopathogenic gram-negative bacterium burkholderia cepacia. endopolygalacturonases belong to glycoside hydrolase family 28 and are responsible for the hydrolysis of the non-esterified regions of pectins. the mode of action of bcpeh28a on different substrates has been investigated and its enzymatic mechanism elucidated. the hydrolysis of polygalacturonate indicates that bcpeh28a is a non-processiv ... | 2007 | 17627609 |
| characterization of the erwinia chrysanthemi gan locus, involved in galactan catabolism. | beta-1,4-galactan is a major component of the ramified regions of pectin. analysis of the genome of the plant pathogenic bacteria erwinia chrysanthemi revealed the presence of a cluster of eight genes encoding proteins potentially involved in galactan utilization. the predicted transport system would comprise a specific porin ganl and an abc transporter made of four proteins, ganfgk(2). degradation of galactans would be catalyzed by the periplasmic 1,4-beta-endogalactanase gana, which released o ... | 2007 | 17644603 |
| gliding arc discharge in the potato pathogen erwinia carotovora subsp. atroseptica: mechanism of lethal action and effect on membrane-associated molecules. | gliding arc (glidarc) discharge is a physicochemical technique for decontamination at atmospheric pressure and ambient temperature. it leads to the destruction of bacterial phytopathogens responsible for important losses in industrial agriculture, namely, erwinia spp., without the formation of resistant forms. we investigated the effect of a novel optimized prototype allowing bacterial killing without lag time. this prototype also decreases the required duration of treatment by 50%. the study of ... | 2007 | 17644644 |
| comparison of pathogen-induced expression and efficacy of two amphibian antimicrobial peptides, msra2 and temporin a, for engineering wide-spectrum disease resistance in tobacco. | the rapid accumulation of defensive transgene products in plants only on pathogen invasion has clear advantages over their constitutive synthesis. in this study, two antimicrobial peptides from the skin secretions of frogs, msra2 (n-methionine-dermaseptin b1) and temporin a, were evaluated for engineering pathogen-induced disease resistance in plants. both peptides inhibited plant-specific pathogens in vitro at micromolar concentrations that were not toxic to plant protoplasts. the plant-optimiz ... | 2007 | 17645440 |
| [preliminary characteristic of dna-containing virus-like particles of erwinia carotovora]. | dna-containing particles formed by the expression of the defect prophages of e. carotovora subsp. carotovora (ecc) have been revealed for the first time. two types of virus-like particles (vlp) occur in this phytopathogenic bacterium. capsides of the first type vlp are weakly identified at agarose electrophoretic separation while dna released from them are presented by distinct reflexes. mobility of the second type particles is close to that of separate capsids of the temperate phage zf40. dna p ... | 2007 | 17682527 |
| short-tailed stx phages exploit the conserved yaet protein to disseminate shiga toxin genes among enterobacteria. | infection of escherichia coli by shiga toxin-encoding bacteriophages (stx phages) was the pivotal event in the evolution of the deadly shiga toxin-encoding e. coli (stec), of which serotype o157:h7 is the most notorious. the number of different bacterial species and strains reported to produce shiga toxin is now more than 500, since the first reported stec infection outbreak in 1982. clearly, stx phages are spreading rapidly, but the underlying mechanism for this dissemination has not been expla ... | 2007 | 17693515 |
| one step engineering of t7-expression strains for protein production: increasing the host-range of the t7-expression system. | the t7-expression system has been very useful for protein expression in escherichia coli. however, it is often desirable to over-express proteins in species other than e. coli. here, we constructed an inducible broad-host-range t7-expression transposon, which allows simple one-step construction of t7-expression strains in various species, providing the option to over-express proteins of interest in a broader host-range. this transposon contains the t7 rna polymerase driven by the lacuv5 promoter ... | 2007 | 17716915 |
| asparaginase (native asnase or pegylated asnase) in the treatment of acute lymphoblastic leukemia. | the discovery of the tumor-inhibitory properties of asparaginase (asnase) began in the early 1950s with the observation that guinea pig serum-treated lymphoma-bearing mice underwent rapid and often complete regression. about 4000 cases of acute lymphoblastic leukemia (all) are diagnosed very year in the us and many more through out the world. the majority of these cases are in children and young adults, making all the most common form of malignancy in these age groups. the treatment protocols of ... | 2006 | 17717965 |
| activation of year-yoag operon transcription by the nitrate-responsive regulator narl is independent of oxygen- responsive regulator fnr in escherichia coli k-12. | the facultative aerobe escherichia coli k-12 can use respiratory nitrate ammonification to generate energy during anaerobic growth. the toxic compound nitric oxide is a by-product of this metabolism. previous transcript microarray studies identified the year-yoag operon, encoding proteins of unknown function, among genes whose transcription is induced in response to nitrate, nitrite, or nitric oxide. nitrate and nitrite regulate anaerobic respiratory gene expression through the narx-narl and nar ... | 2007 | 17720788 |
| mycobacterial cells have dual nickel-cobalt sensors: sequence relationships and metal sites of metal-responsive repressors are not congruent. | a novel arsr-smtb family transcriptional repressor, kmtr, has been characterized from mycobacteria. mutants of mycobacterium tuberculosis lacking kmtr show elevated expression of rv2025c encoding a deduced cdf-family metal exporter. kmtr-dependent repression of the cdf and kmtr operator-promoters was alleviated by nickel and cobalt in minimal medium. electrophoretic mobility shift assays and fluorescence anisotropy show binding of purified kmtr to nucleotide sequences containing a region of dyad ... | 2007 | 17726022 |
| structure and function of the escherichia coli protein ymgb: a protein critical for biofilm formation and acid-resistance. | the escherichia coli gene cluster ymgabc was identified in transcriptome studies to have a role in biofilm development and stability. in this study, we showed that ymgb represses biofilm formation in rich medium containing glucose, decreases cellular motility, and protects the cell from acid indicating that ymgb has a major role in acid-resistance in e. coli. our data show that these phenotypes are potentially mediated through interactions with the important cell signal indole. in addition, gel ... | 2007 | 17765265 |
| virulence and prodigiosin antibiotic biosynthesis in serratia are regulated pleiotropically by the ggdef/eal domain protein, pigx. | gram-negative bacteria of the genus serratia are opportunistic human, plant, and insect pathogens. serratia sp. strain atcc 39006 secretes pectinases and cellulases and produces the secondary metabolites carbapenem and prodigiosin. mutation of a gene (pigx) resulted in an extremely pleiotropic phenotype: prodigiosin antibiotic biosynthesis, plant virulence, and pectinase production were all elevated. pigx controlled secondary metabolism by repressing the transcription of the target prodigiosin b ... | 2007 | 17766413 |
| rela-dependent (p)ppgpp production controls exoenzyme synthesis in erwinia carotovora subsp. atroseptica. | in this report, we investigate the link between nutrient limitation, rela-mediated (p)ppgpp production, and virulence in the phytopathogen erwinia carotovora subsp. atroseptica. a rela null mutant (jwc7) was constructed by allelic exchange, and we confirmed that, unlike the wild-type progenitor, this mutant did not produce elevated levels of (p)ppgpp upon nutrient downshift. however, (p)ppgpp production could be restored in strain jwc7 during nutrient limitation by supplying rela in trans. durin ... | 2007 | 17766416 |
| a generalized transducing phage for the murine pathogen citrobacter rodentium. | a virulent phage (phicr1) capable of generalized transduction in citrobacter rodentium was isolated from the environment and characterized. c. rodentium is a natural pathogen of mice, causing transmissible murine colonic hyperplasia. sequencing of its genome has recently been completed and will soon be fully annotated and published. c. rodentium is an important model organism for infections caused by the human pathogens enteropathogenic and enterohaemorrhagic escherichia coli (epec and ehec). ph ... | 2007 | 17768241 |
| siderophore-based iron acquisition and pathogen control. | high-affinity iron acquisition is mediated by siderophore-dependent pathways in the majority of pathogenic and nonpathogenic bacteria and fungi. considerable progress has been made in characterizing and understanding mechanisms of siderophore synthesis, secretion, iron scavenging, and siderophore-delivered iron uptake and its release. the regulation of siderophore pathways reveals multilayer networks at the transcriptional and posttranscriptional levels. due to the key role of many siderophores ... | 2007 | 17804665 |
| the plant pathogen pantoea ananatis produces n-acylhomoserine lactone and causes center rot disease of onion by quorum sensing. | a number of gram-negative bacteria have a quorum-sensing system and produce n-acyl-l-homoserine lactone (ahl) that they use them as a quorum-sensing signal molecule. pantoea ananatis is reported as a common colonist of wheat heads at ripening and causes center rot of onion. in this study, we demonstrated that p. ananatis sk-1 produced two ahls, n-hexanoyl-l-homoserine lactone (c6-hsl) and n-(3-oxohexanoyl)-l-homoserine lactone (3-oxo-c6-hsl). we cloned the ahl-synthase gene (eani) and ahl-recept ... | 2007 | 17827290 |
| structural and kinetic characterization of quinolinate phosphoribosyltransferase (hqprtase) from homo sapiens. | human quinolinate phosphoribosyltransferase (ec 2.4.2.19) (hqprtase) is a member of the type ii phosphoribosyltransferase family involved in the catabolism of quinolinic acid (qa). it catalyses the formation of nicotinic acid mononucleotide from quinolinic acid, which involves a phosphoribosyl transfer reaction followed by decarboxylation. hqprtase has been implicated in a number of neurological conditions and in order to study it further, we have carried out structural and kinetic studies on re ... | 2007 | 17868694 |
| quorum sensing: fact, fiction, and everything in between. | | 2007 | 17869606 |
| evaluation of reference genes for real-time rt-pcr expression studies in the plant pathogen pectobacterium atrosepticum. | real-time rt-pcr has become a powerful technique to monitor low-abundance mrna expression and is a useful tool when examining bacterial gene expression inside infected host tissues. however, correct evaluation of data requires accurate and reliable normalisation against internal standards. thus, the identification of reference genes whose expression does not change during the course of the experiment is of paramount importance. here, we present a study where manipulation of cultural growth condi ... | 2007 | 17888160 |
| genome-wide screen of salmonella genes expressed during infection in pigs, using in vivo expression technology. | pigs are a food-producing species that readily carry salmonella but, in the great majority of cases, do not show clinical signs of disease. little is known about the functions required by salmonella to be maintained in pigs. we have devised a recombinase-based promoter-trapping strategy to identify genes with elevated expression during pig infection with salmonella enterica serovar typhimurium. a total of 55 clones with in vivo-induced promoters were selected from a genomic library of approximat ... | 2007 | 17921269 |
| distribution and replication of the pathogenicity plasmid ppath in diverse populations of the gall-forming bacterium pantoea agglomerans. | pantoea agglomerans has been transformed from a commensal bacterium into two related gall-forming pathovars by acquisition of ppath plasmids containing a pathogenicity island (pai). this pai harbors an hrp/hrc gene cluster, type iii effectors, and phytohormone biosynthetic genes. dna typing by pulsed-field gel electrophoresis revealed two major groups of p. agglomerans pv. gypsophilae and one group of p. agglomerans pv. betae. the ppath plasmids of the different groups had nearly identical repli ... | 2007 | 17921271 |
| erwinia carotovora elicitors and botrytis cinerea activate defense responses in physcomitrella patens. | vascular plants respond to pathogens by activating a diverse array of defense mechanisms. studies with these plants have provided a wealth of information on pathogen recognition, signal transduction and the activation of defense responses. however, very little is known about the infection and defense responses of the bryophyte, physcomitrella patens, to well-studied phytopathogens. the purpose of this study was to determine: i) whether two representative broad host range pathogens, erwinia carot ... | 2007 | 17922917 |
| comparative and functional genomics reveals genetic diversity and determinants of host specificity among reference strains and a large collection of chinese isolates of the phytopathogen xanthomonas campestris pv. campestris. | xanthomonas campestris pathovar campestris (xcc) is the causal agent of black rot disease of crucifers worldwide. the molecular genetic diversity and host specificity of xcc are poorly understood. | 2007 | 17927820 |
| hasb, the serratia marcescens tonb paralog, is specific to hasr. | serratia marcescens possesses two functional tonb paralogs, tonb(sm) and hasb, for energizing tonb-dependent transport receptors (tbdt). previous work had shown that hasb is specific to heme uptake in the natural host and in escherichia coli expressing the s. marcescens tbdt receptor hasr, whereas the s. marcescens tonb and e. coli tonb proteins function equally well with various tbdt receptors for heme and siderophores. this has raised the question of the target of this specificity. hasb could ... | 2008 | 17951376 |
| hasb, the serratia marcescens tonb paralog, is specific to hasr. | serratia marcescens possesses two functional tonb paralogs, tonb(sm) and hasb, for energizing tonb-dependent transport receptors (tbdt). previous work had shown that hasb is specific to heme uptake in the natural host and in escherichia coli expressing the s. marcescens tbdt receptor hasr, whereas the s. marcescens tonb and e. coli tonb proteins function equally well with various tbdt receptors for heme and siderophores. this has raised the question of the target of this specificity. hasb could ... | 2008 | 17951376 |
| mechanical stress induces biotic and abiotic stress responses via a novel cis-element. | plants are continuously exposed to a myriad of abiotic and biotic stresses. however, the molecular mechanisms by which these stress signals are perceived and transduced are poorly understood. to begin to identify primary stress signal transduction components, we have focused on genes that respond rapidly (within 5 min) to stress signals. because it has been hypothesized that detection of physical stress is a mechanism common to mounting a response against a broad range of environmental stresses, ... | 2007 | 17953483 |