Publications

sequence analysis of the mobile genome island pklc102 of pseudomonas aeruginosa c.	the pseudomonas aeruginosa plasmid pklc102 coexists as a plasmid and a genome island in clone c strains. whereas the related plasmid pklk106 reversibly recombines with p. aeruginosa clone k chromosomes at one of the two trna(lys) genes, pklc102 is incorporated into the trna(lys) gene only close to the pila locus. targeting of the other trna(lys) copy in the chromosome is blocked by a 23,395-bp mosaic of truncated pao open reading frames, transposons, and pklc102 homologs. annotation and phylogen ...	2004	14702321
pseudomonas syringae type iii secretion system targeting signals and novel effectors studied with a cya translocation reporter.	pseudomonas syringae pv. tomato strain dc3000 is a pathogen of tomato and arabidopsis: the hrp-hrc-encoded type iii secretion system (ttss), which injects bacterial effector proteins (primarily called hop or avr proteins) into plant cells, is required for pathogenicity. in addition to being regulated by the hrpl alternative sigma factor, most avr or hop genes encode proteins with n termini that have several characteristic features, including (i) a high percentage of ser residues, (ii) an aliphat ...	2004	14702323
functional display of foreign protein on surface of escherichia coli using n-terminal domain of ice nucleation protein.	we investigated the ability of the n-terminal domain of inak, an ice nucleation protein from pseudomonas syringae kctc1832, to act as an anchoring motif for the display of foreign proteins on the escherichia coli cell surface. total expression level and surface display efficiency of green fluorescent protein (gfp) was compared following their fusion with either the n-terminal domain of inak (inak-n), or with the known truncated inak containing both n- and c-terminal domains (inak-nc). we report ...	2004	14705004
frequency, size, and localization of bacterial aggregates on bean leaf surfaces.	using epifluorescence microscopy and image analysis, we have quantitatively described the frequency, size, and spatial distribution of bacterial aggregates on leaf surfaces of greenhouse-grown bean plants inoculated with the plant-pathogenic bacterium pseudomonas syringae pv. syringae strain b728a. bacterial cells were not randomly distributed on the leaf surface but occurred in a wide range of cluster sizes, ranging from single cells to over 10(4) cells per aggregate. the average cluster size i ...	2004	14711662
growth of escherichia coli coexpressing phosphotriesterase and glycerophosphodiester phosphodiesterase, using paraoxon as the sole phosphorus source.	phosphotriesterases catalyze the hydrolytic detoxification of phosphotriester pesticides and chemical warfare nerve agents with various efficiencies. the directed evolution of phosphotriesterases to enhance the breakdown of poor substrates is desirable for the purposes of bioremediation. a limiting factor in the identification of phosphotriesterase mutants with increased activity is the ability to effectively screen large mutant libraries. to this end, we have investigated the possibility of cou ...	2004	14711669
rme1 is necessary for mi-1-mediated resistance and acts early in the resistance pathway.	the tomato gene mi-1 confers resistance to root-knot nematodes (meloidogyne spp.), potato aphid, and whitefly. using genetic screens, we have isolated a mutant, rme1 (resistance to meloidogyne spp.), compromised in resistance to m. javanica and potato aphid. here, we show that the rme1 mutant is also compromised in resistance to m. incognita, m. arenaria, and whitefly. in addition, using an agrobacterium-mediated transient assay in leaves to express constitutive gain-of-function mutant pto(l205d ...	2004	14714868
functional analysis of genes involved in the synthesis of syringolin a by pseudomonas syringae pv. syringae b301 d-r.	strains of the phytopathogenic bacterium pseudomonas syringae pv. syringae secrete a family of structurally closely related peptide derivatives dubbed syringolins, of which syringolin a is the major variant. the function of syringolins in the interaction of p. syringae pv. syringae with their host plants presently is unknown. it is hypothesized that they may constitute virulence factors. however, syringolins are determinants recognized and reacted to by nonhost plant species, and syringolin a ha ...	2004	14714872
pathogenicity islands in bacterial pathogenesis.	in this review, we focus on a group of mobile genetic elements designated pathogenicity islands (pai). these elements play a pivotal role in the virulence of bacterial pathogens of humans and are also essential for virulence in pathogens of animals and plants. characteristic molecular features of pai of important human pathogens and their role in pathogenesis are described. the availability of a large number of genome sequences of pathogenic bacteria and their benign relatives currently offers a ...	2004	14726454
the nifl-nifa system: a multidomain transcriptional regulatory complex that integrates environmental signals.		2004	14729684
direct glutaminyl-trna biosynthesis and indirect asparaginyl-trna biosynthesis in pseudomonas aeruginosa pao1.	the genomic sequence of pseudomonas aeruginosa pao1 was searched for the presence of open reading frames (orfs) encoding enzymes potentially involved in the formation of gln-trna and of asn-trna. we found orfs similar to known glutamyl-trna synthetases (glurs), glutaminyl-trna synthetases (glnrs), aspartyl-trna synthetases (asprs), and trimeric trna-dependent amidotransferases (adt) but none similar to known asparaginyl-trna synthetases (asnrs). the absence of asnrs was confirmed by biochemical ...	2004	14729703
the arabidopsis thaliana dihydroxyacetone phosphate reductase gene suppresssor of fatty acid desaturase deficiency1 is required for glycerolipid metabolism and for the activation of systemic acquired resistance.	systemic acquired resistance (sar) is a broad-spectrum resistance mechanism in plants that is activated in naive organs after exposure of another organ to a necrotizing pathogen. the organs manifesting sar exhibit an increase in levels of salicylic acid (sa) and expression of the pathogenesis-related1 (pr1) gene. sa signaling is required for the manifestation of sar. we demonstrate here that the arabidopsis thaliana suppressor of fatty acid desaturase deficiency1 (sfd1) mutation compromises the ...	2004	14729910
divergent roles in arabidopsis thaliana development and defense of two homologous genes, aberrant growth and death2 and agd2-like defense response protein1, encoding novel aminotransferases.	the disease-resistant arabidopsis thaliana aberrant growth and death2 (agd2-1) mutant has elevated levels of the defense signal salicylic acid (sa), altered leaf morphology, and mild dwarfism. agd2 and its close homolog ald1 (for agd2-like defense response protein1) encode aminotransferases that act on an overlapping set of amino acids in vitro. however, kinetic parameters indicate that agd2 and ald1 may drive the aminotransferase reaction in opposite directions. ald1-deficient mutants have the ...	2004	14729919
lempk3 is a mitogen-activated protein kinase with dual specificity induced during tomato defense and wounding responses.	mitogen-activated protein (map) kinase cascades are readily activated during the response of plants to avirulent pathogens or to pathogen-derived elicitors. here we show that the tomato map kinase lempk3 is specifically induced at the mrna level during elicitation of the hypersensitive response in resistant plants infected by avirulent strains of the phytopathogenic bacteria xanthomonas campestris pv. vesicatoria and pseudomonas syringae pv. tomato, as well as upon treatment with the fungal elic ...	2004	14742423
molecular characterization of a glucose-inhibited division gene, gida, that regulates cytotoxic enterotoxin of aeromonas hydrophila.	by using a mini-transposon, we obtained two mutated strains of a diarrheal isolate, ssu, of aeromonas hydrophila that exhibited a 50 to 53% reduction in the hemolytic activity and 83 to 87% less cytotoxic activity associated with the cytotoxic enterotoxin (act). act is a potent virulence factor of a. hydrophila and has been shown to contribute significantly to the development of both diarrhea and septicemia in animal models. subsequent cloning and dna sequence analysis revealed that transposon i ...	2004	14742556
identification of five outer membrane-associated proteins among cross-protective factor proteins of pasteurella multocida.	fowl cholera is caused by pasteurella multocida serovars a:1, a:3, and a:4. the 39-kda cross-protective factor protein and four other membrane proteins of the membrane proteome of p. multocida were identified. we determined that the 39-kda cross-protective protein was pasteurella lipoprotein b, or plpb.	2004	14742575
convergent evolution of disease resistance gene specificity in two flowering plant families.	plant disease resistance (r) genes that mediate recognition of the same pathogen determinant sometimes can be found in distantly related plant families. this observation implies that some r gene alleles may have been conserved throughout the diversification of land plants. to address this question, we have compared r genes from glycine max (soybean), rpg1-b, and arabidopsis thaliana, rpm1, that mediate recognition of the same type iii effector protein from pseudomonas syringae, avrb. rpm1 has be ...	2004	14742871
cassette-like variation of restriction enzyme genes in escherichia coli c and relatives.	a surprising result of comparative bacterial genomics has been the large amount of dna found to be present in one strain but not in another of the same species. we examine in detail one location where gene content varies extensively, the restriction cluster in escherichia coli. this region is designated the immigration control region (icr) for the density and variability of restriction functions found there. to better define the boundaries of this variable locus, we determined the sequence of th ...	2004	14744977
functional reclassification of the putative cinnamyl alcohol dehydrogenase multigene family in arabidopsis.	of 17 genes annotated in the arabidopsis genome database as cinnamyl alcohol dehydrogenase (cad) homologues, an in silico analysis revealed that 8 genes were misannotated. of the remaining nine, six were catalytically competent for nadph-dependent reduction of p-coumaryl, caffeyl, coniferyl, 5-hydroxyconiferyl, and sinapyl aldehydes, whereas three displayed very low activity and only at very high substrate concentrations. of the nine putative cads, two (atcad5 and atcad4) had the highest activit ...	2004	14745009
evolutionary potential of an rna virus.	rna viruses are remarkably adaptable to changing environments. this is medically important because it enables pathogenic viruses to escape the immune response and chemotherapy and is of considerable theoretical interest since it allows the investigation of evolutionary processes within convenient time scales. a number of earlier studies have addressed the dynamics of adapting rna virus populations. however, it has been difficult to monitor the trajectory of molecular changes in rna genomes in re ...	2004	14747576
influence of growth temperature on lipid and phosphate contents of surface polysaccharides from the antarctic bacterium pseudoalteromonas haloplanktis tac 125.	the chemical structural variations induced by different growth temperatures in the lipooligosaccharide and exopolysaccharide components extracted from the antarctic bacterium pseudoalteromonas haloplanktis tac 125 are described. the increase in phosphorylation with the increase in growth temperature seems to be general, because it happens not only for the lipooligosaccharide but also for the exopolysaccharide. structural variations in the lipid components of lipid a also occur. in addition, free ...	2004	14679221
characterization of cmaa, an adenylation-thiolation didomain enzyme involved in the biosynthesis of coronatine.	several pathovars of pseudomonas syringae produce the phytotoxin coronatine (cor), which contains an unusual amino acid, the 1-amino-2-ethylcyclopropane carboxylic acid called coronamic acid (cma), which is covalently linked to a polyketide-derived carboxylic acid, coronafacic acid, by an amide bond. the region of the cor biosynthetic gene cluster proposed to be responsible for cma biosynthesis was resequenced, and errors in previously deposited cmaa sequences were corrected. these efforts allow ...	2004	14679222
rtsa coordinately regulates dsba and the salmonella pathogenicity island 1 type iii secretion system.	salmonella serovars cause a wide variety of diseases ranging from mild gastroenteritis to life-threatening systemic infections. an important step in salmonella enterica serovar typhimurium infection is the invasion of nonphagocytic epithelial cells, mediated by a type iii secretion system (ttss) encoded on salmonella pathogenicity island 1 (spi1). the spi1 ttss forms a needle complex through which effector proteins are injected into the cytosol of host cells, where they promote actin rearrangeme ...	2004	14679226
in pseudomonas syringae pv. phaseolicola, expression of the argk gene, encoding the phaseolotoxin-resistant ornithine carbamoyltransferase, is regulated indirectly by temperature and directly by a precursor resembling carbamoylphosphate.	pseudomonas syringae pv. phaseolicola synthesizes a non-host-specific toxin, phaseolotoxin, and also synthesizes a phaseolotoxin-resistant ornithine carbamoyltransferase (roct) to protect itself from its own toxin. roct is encoded by argk, which is expressed coordinately with phaseolotoxin synthesis at 18 degrees c. to investigate the regulatory mechanisms of this system, null mutants were constructed for argk, argf (encoding the phaseolotoxin-sensitive octase [soct]), and amta (encoding an amid ...	2004	14679234
the pseudomonas syringae type iii effector avrrpt2 functions downstream or independently of sa to promote virulence on arabidopsis thaliana.	avrrpt2, a pseudomonas syringae type iii effector protein, functions from inside plant cells to promote the virulence of p. syringae pv. tomato strain dc3000 (pstdc3000) on arabidopsis thaliana plants lacking a functional copy of the corresponding rps2 resistance gene. in this study, we extended our understanding of avrrpt2 virulence activity by exploring the hypothesis that avrrpt2 promotes pstdc3000 virulence by suppressing plant defenses. when delivered by pstdc3000, avrrpt2 suppresses pathog ...	2004	14756766
identification of pseudomonas syringae type iii effectors that can suppress programmed cell death in plants and yeast.	the pseudomonas syringae pv. tomato dc3000 type iii secretion system (ttss) is required for bacterial pathogenicity on plants and elicitation of the hypersensitive response (hr), a programmed cell death (pcd) that occurs on resistant plants. cosmid phir11 enables non-pathogens to elicit an hr dependent upon the ttss and the effector hoppsya. we used phir11 to determine that effectors hopptoe, avirulence avrpphepto, avrppib1pto, avrptob, and hopptof could suppress a hoppsya-dependent hr on tobacc ...	2004	14756767
activation of a coi1-dependent pathway in arabidopsis by pseudomonas syringae type iii effectors and coronatine.	gram-negative bacteria use a variety of virulence factors including phytotoxins, exopolysaccharides, effectors secreted by the type iii secretion system, and cell-wall-degrading enzymes to promote parasitism in plants. however, little is known about how these virulence factors alter plant cellular responses to promote disease. in this study, we show that virulent pseudomonas syringae strains activate the transcription of an arabidopsis ethylene response factor (erf) gene, rap2.6, in a coronatine ...	2004	14756769
coordinated regulation of genes for secretion in tobacco at late developmental stages: association with resistance against oomycetes.	besides the systemic acquired resistance (sar) induced in response to microbial stimulation, host plants may also acquire resistance to pathogens in response to endogenous stimuli associated with their own development. in tobacco (nicotiana tabacum), the vegetative-to-flowering transition comes along with a susceptibility-to-resistance transition to the causal agent of black shank disease, the oomycete phytophthora parasitica. this resistance affects infection effectiveness and hyphal expansion ...	2004	14764907
an extracellular aspartic protease functions in arabidopsis disease resistance signaling.	we have used activation tagging with t-dna carrying cauliflower mosaic virus 35s enhancers to investigate the complex signaling networks underlying disease resistance in arabidopsis. from a screen of approximately 5000 lines, we identified constitutive disease resistance (cdr1) encoding an apoplastic aspartic protease, the overexpression of which causes dwarfing and resistance to virulent pseudomonas syringae. these phenotypes reflect salicylic-acid-dependent activation of micro-oxidative bursts ...	2004	14765119
pseudomonas syringae pv. phaseolicola can be separated into two genetic lineages distinguished by the possession of the phaseolotoxin biosynthetic cluster.	the bean (phaseolus spp.) plant pathogen pseudomonas syringae pv. phaseolicola is characterized by the ability to produce phaseolotoxin (tox(+)). we recently reported that the majority of the spanish p. syringae pv. phaseolicola population is unable to synthesize this toxin (tox(-)). these tox(-) isolates appear to lack the entire dna region for the biosynthesis of phaseolotoxin (argk-tox gene cluster), as shown by pcr amplification and dna hybridization using dna sequences specific for separate ...	2004	14766926
harpin inactivates mitochondria in arabidopsis suspension cells.	harpin is a well-known proteinaceous bacterial elicitor that can induce an oxidative burst and programmed cell death in various host plants. given the demonstrated roles of mitochondria in animal apoptosis, we investigated the effect of harpin from pseudomonas syringae on mitochondrial functions in arabidopsis suspension cells in detail. fluorescence microscopy in conjunction with double-staining for reactive oxygen species (ros) and mitochondria suggested co-localization of mitochondria and ros ...	2004	14964527
importance of opghxcv of xanthomonas campestris pv. vesicatoria in host-parasite interactions.	tn5 insertion mutants of xanthomonas campestris pv. vesicatoria were inoculated into tomato and screened for reduced virulence. one mutant exhibited reduced aggressiveness and attenuated growth in planta. southern blot analyses indicated that the mutant carried a single tn5 insertion not associated with previously cloned pathogenicity-related genes of x. campestris pv. vesicatoria. the wild-type phenotype of this mutant was restored by one recombinant plasmid (popg361) selected from a genomic li ...	2004	14964529
identification and characterization of a well-defined series of coronatine biosynthetic mutants of pseudomonas syringae pv. tomato dc3000.	to identify pseudomonas syringae pv. tomato genes involved in pathogenesis, we carried out a screen for tn5 mutants of p. syringae pv. tomato dc3000 with reduced virulence on arabidopsis thaliana. several mutants defining both known and novel virulence loci were identified. six mutants contained insertions in biosynthetic genes for the phytotoxin coronatine (cor). the p. syringae pv. tomato dc3000 cor genes are chromosomally encoded and are arranged in two separate clusters, which encode enzymes ...	2004	14964530
nopl, an effector protein of rhizobium sp. ngr234, thwarts activation of plant defense reactions.	bacterial effector proteins delivered into eukaryotic cells via bacterial type iii secretion systems are important virulence factors in plant-pathogen interactions. type iii secretion systems have been found in rhizobium species that form symbiotic, nitrogen-fixing associations with legumes. one such bacterium, rhizobium sp. ngr234, secretes a number of type iii effectors, including nodulation outer protein l (nopl, formerly y4xl). here, we show that expression of nopl in tobacco (nicotiana taba ...	2004	14966249
genomic and genetic analysis of bordetella bacteriophages encoding reverse transcriptase-mediated tropism-switching cassettes.	liu et al. recently described a group of related temperate bacteriophages that infect bordetella subspecies and undergo a unique template-dependent, reverse transcriptase-mediated tropism switching phenomenon (liu et al., science 295: 2091-2094, 2002). tropism switching results from the introduction of single nucleotide substitutions at defined locations in the vr1 (variable region 1) segment of the mtd (major tropism determinant) gene, which determines specificity for receptors on host bacteria ...	2004	14973019
evidence for a symbiosis island involved in horizontal acquisition of pederin biosynthetic capabilities by the bacterial symbiont of paederus fuscipes beetles.	pederin belongs to a group of antitumor compounds found in terrestrial beetles and marine sponges. it is used by apparently all members of the rove beetle genera paederus and paederidus as a chemical defense against predators. however, a recent analysis of the putative pederin biosynthesis (ped) gene cluster strongly suggests that pederin is produced by bacterial symbionts. we have sequenced an extended region of the symbiont genome to gain further insight into the biology of this as-yet-uncultu ...	2004	14973122
the melampsora lini avrl567 avirulence genes are expressed in haustoria and their products are recognized inside plant cells.	the linum usitatissimum (flax) l gene alleles, which encode nucleotide binding site-leu rich repeat class intracellular receptor proteins, confer resistance against the melampsora lini (flax rust) fungus. at least 11 different l resistance specificities are known, and the corresponding avirulence genes in m. lini map to eight independent loci, some of which are complex and encode multiple specificities. we identified an m. lini cdna marker that cosegregates in an f2 rust family with a complex lo ...	2004	14973158
the arabidopsis cytosolic thioredoxin h5 gene induction by oxidative stress and its w-box-mediated response to pathogen elicitor.	the attrxh5 protein belongs to the cytosolic thioredoxins h family that, in arabidopsis, contains eight members showing very distinct patterns and levels of expression. here, we show that the attrxh5 gene is up-regulated during wounding, abscission, and senescence, as well as during incompatible interactions with the bacterial pathogen pseudomonas syringae. by electrophoretic mobility shift assays, a binding activity on a w-box in the attrxh5 promoter region was found induced by treatments with ...	2004	14976236
evidence for a hybrid genomic island in verocytotoxin-producing escherichia coli cl3 (serotype o113:h21) containing segments of edl933 (serotype o157:h7) o islands 122 and 48.	genomic o island 122 (oi-122) of the verocytotoxin-producing escherichia coli (vtec) strain edl933 contains four putative virulence genes, z4321, z4326, z4332, and z4333. however, strain cl3 (serotype o113:h21) contains only z4321, not the other three genes. to determine whether z4321 is part of a different genomic island in cl3, a region of 27,293 bp up- and downstream of z4321 was sequenced and found to contain elements of two different edl933 genomic islands (oi-48 and oi-122) and a yersinia ...	2004	14977955
pseudomonas syringae pv. tomato cells encounter inhibitory levels of water stress during the hypersensitive response of arabidopsis thaliana.	during plant defense against bacterial pathogens, the hypersensitive response (hr) functions to restrict pathogen growth and spread. the mechanisms driving this growth restriction are poorly understood. we used a water stress-responsive transcriptional fusion to quantify the water potential sensed by individual pseudomonas syringae pv. tomato dc3000 cells during infection of arabidopsis thaliana leaves. a nonpathogenic dc3000 hrcc mutant defective in type iii secretion, as well as the saprophyte ...	2004	14981249
the broad host range pathogen pseudomonas aeruginosa strain pa14 carries two pathogenicity islands harboring plant and animal virulence genes.	the ubiquitous bacterium pseudomonas aeruginosa is the quintessential opportunistic pathogen. certain isolates infect a broad range of host organisms, from plants to humans. the pathogenic promiscuity of particular variants may reflect an increased virulence gene repertoire beyond the core p. aeruginosa genome. we have identified and characterized two p. aeruginosa pathogenicity islands (papi-1 and papi-2) in the genome of pa14, a highly virulent clinical isolate. the 108-kb papi-1 and 11-kb pap ...	2004	14983043
dissecting virulence: systematic and functional analyses of a pathogenicity island.	bacterial pathogenicity islands (pai) often encode both effector molecules responsible for disease and secretion systems that deliver these effectors to host cells. human enterohemorrhagic escherichia coli (ehec), enteropathogenic e. coli, and the mouse pathogen citrobacter rodentium (cr) possess the locus of enterocyte effacement (lee) pai. we systematically mutagenized all 41 cr lee genes and functionally characterized these mutants in vitro and in a murine infection model. we identified 33 vi ...	2004	14988506
phosphatidylethanolamine is not essential for growth of sinorhizobium meliloti on complex culture media.	in addition to phosphatidylglycerol (pg), cardiolipin (cl), and phosphatidylethanolamine (pe), sinorhizobium meliloti also possesses phosphatidylcholine (pc) as a major membrane lipid. the biosynthesis of pc in s. meliloti can occur via two different routes, either via the phospholipid n-methylation pathway, in which pe is methylated three times in order to obtain pc, or via the phosphatidylcholine synthase (pcs) pathway, in which choline is condensed with cdp-diacylglycerol to obtain pc directl ...	2004	14996797
identification of a novel pseudomonas syringae psy61 effector with virulence and avirulence functions by a hrpl-dependent promoter-trap assay.	the hrp pathogenicity island of pseudomonas syringae encodes a type iii secretion system (ttss) that translocates effectors into plant cells. most genes encoding effectors are dispersed in the p. syringae genome. regardless of location, all are regulated coordinately by the alternative sigma factor hrpl. an hrpl-dependent promoter-trap assay was developed to screen genomic libraries of p. syringae strains for promoters whose activity in escherichia coli is dependent on an inducible hrpl construc ...	2004	15000392
mutations in the pseudomonas syringae avrrpt2 gene that dissociate its virulence and avirulence activities lead to decreased efficiency in avrrpt2-induced disappearance of rin4.	the avrrpt2 gene from pseudomonas syringae pv. tomato exhibits avirulence activity on arabidopsis expressing the resistance gene rps2 but promotes bacterial virulence on susceptible rps2 arabidopsis. to understand the functional relationship between the avirulence and virulence activities of avrrpt2, we analyzed a series of six avrrpt2 mutants deficient in eliciting the rps2-dependent hypersensitive response. we show that the mutants are also severely impaired in triggering rsp2-dependent resist ...	2004	15000398
pathogens: the plight of plants.		2004	15003115
myrbase: analysis of genome-wide glycine myristoylation enlarges the functional spectrum of eukaryotic myristoylated proteins.	we evaluated the evolutionary conservation of glycine myristoylation within eukaryotic sequences. our large-scale cross-genome analyses, available as myrbase, show that the functional spectrum of myristoylated proteins is currently largely underestimated. we give experimental evidence for in vitro myristoylation of selected predictions. furthermore, we classify five membrane-attachment factors that occur most frequently in combination with, or even replacing, myristoyl anchors, as some protein f ...	2004	15003124
molecular evidence for the evolution of metal homeostasis genes by lateral gene transfer in bacteria from the deep terrestrial subsurface.	lateral gene transfer (lgt) plays a vital role in increasing the genetic diversity of microorganisms and promoting the spread of fitness-enhancing phenotypes throughout microbial communities. to date, lgt has been investigated in surface soils, natural waters, and biofilm communities but not in the deep terrestrial subsurface. here we used a combination of molecular analyses to investigate the role of lgt in the evolution of metal homeostasis in lead-resistant subsurface bacteria. a nested pcr a ...	2004	15006795
the o-polysaccharide of pseudomonas syringae pv. mori ncppb 1656 is a beta-(1-->2)-linked homopolymer of l-rhamnose.	the o-polysaccharide from the lipopolysaccharide of the phytopathogenic bacterium pseudomonas syringae pv. mori ncppb 1656 was studied by sugar analysis along with 1h and 13c nmr spectroscopy and found to be a new beta-(1-->2)-linked homopolymer of l-rhamnose.	2004	15013414
fusicoccin activates pathogen-responsive gene expression independently of common resistance signalling pathways, but increases disease symptoms in pseudomonas syringae-infected tomato plants.	fusicoccin (fc), an activator of the plant plasma membrane h+-atpase, induces several components of plant pathogen resistance responses, including defence hormone biosynthesis and pathogenesis-related (pr) gene expression. the mechanism by which these responses occur, and the effect they have on plant-pathogen interactions is unknown. here, we show that pr gene expression in response to fc in tomato (lycopersicon esculentum mill.) plants does not strictly require the common defence hormones, sal ...	2004	15014997
crystal structure of the type iii effector avrb from pseudomonas syringae.	avrb is a pseudomonas syringae type iii effector protein that is translocated into host plant cells during attempted pathogenesis. arabidopsis harboring the corresponding resistance protein rpm1 can detect avrb and mount a rapid host defense response, thus avoiding active infection. in the plant cell, avrb induces phosphorylation of rin4, a key component in avrb/rpm1 recognition. although the avrb/rpm1 system is among the best characterized of the numerous bacterial effector/plant resistance pro ...	2004	15016364
universally occurring phenylpropanoid and species-specific indolic metabolites in infected and uninfected arabidopsis thaliana roots and leaves.	a total of eleven alkali-released, aromatic compounds were identified by hplc, ms and nmr analyses in cell wall extracts from arabidopsis thaliana roots. nine of them together constituted the three complete series of 4-hydroxy-, 4-hydroxy-3-methoxy, and 4-hydroxy-3,5-dimethoxy-substituted benzaldehydes, benzoic acids and cinnamic acids. the other two were indolic metabolites: indole-3-carboxylic acid and indole-3-carbaldehyde. qualitatively similar, but quantitatively distinct profiles were obta ...	2004	15016565
bacterial biota in the human distal esophagus.	the esophagus, like other luminal organs of the digestive system, provides a potential environment for bacterial colonization, but little is known about the presence of a bacterial biota or its nature. by using broad-range 16s rdna pcr, biopsies were examined from the normal esophagus of four human adults. the 900 pcr products cloned represented 833 unique sequences belonging to 41 genera, or 95 species-level operational taxonomic units (slotu); 59 slotu were homologous with culture-defined bact ...	2004	15016918
silencing of the mitogen-activated protein kinase mpk6 compromises disease resistance in arabidopsis.	here, we use a loss-of-function approach to demonstrate that the arabidopsis (arabidopsis thaliana) mitogen-activated protein kinase (mapk) mpk6 plays a role in resistance to certain pathogens. mpk6-silenced arabidopsis showed no apparent morphological phenotype or reduced fertility, indicating mpk6 is not required for development. however, resistances to an avirulent strain of peronospora parasitica and avirulent and virulent strains of pseudomonas syringae were compromised, suggesting that mpk ...	2004	15020743
identification of a novel steroid inducible gene associated with the beta hsd locus of comamonas testosteroni.	comamonas testosteroni is a soil bacterium, which can use a variety of steroids as carbon and energy source. even if it can be estimated that the complete degradation of the steroid nucleus requires more than 20 enzymatic reactions, the complete molecular characterization of the genes encoding these steroid degradative enzymes as well as the genetic organization of them remain to be elucidated. we have previously reported the cloning and nucleotide sequence of two steroid-inducible genes, beta h ...	2004	15026087
hetr homodimer is a dna-binding protein required for heterocyst differentiation, and the dna-binding activity is inhibited by pats.	hetr plays a key role in regulation of heterocyst differentiation. when the cys-48 residue of the hetr from anabaena sp. pcc 7120 was replaced with an ala residue, the mutant hetr (hetr(c48a)) could not dimerize, indicating that hetr forms a homodimer through a disulfide bond. the anabaena strain c48, containing the hetrc48a gene, could not produce hetr homodimer and failed to form heterocyst. we show that hetr is a dna-binding protein and that its homodimerization is required for the dna bindin ...	2004	15051891
mutagenic dna repair potential in pseudomonas spp., and characterization of the rulabpc operon from the highly mutable strain pseudomonas cichorii 302959.	we assessed the tolerance to ultraviolet b (uvb; 290-320 nm) radiation and uvb-induced mutability in 28 pseudomonas spp. and four burkholderia cepacia strains. the uvb survival of 23 (72%) of the strains was elevated (>46% survival following irradiation with a 2250 j m-2 dose), and 17 (53%) strains were defined as mutable by uvb. a mutagenic dna repair determinant was cloned and characterized from the highly mutable strain p. cichorii 302959 and shown by sequence analysis to be an allele of rula ...	2004	15052319
a dynamic mathematical model to clarify signaling circuitry underlying programmed cell death control in arabidopsis disease resistance.	plant cells undergo programmed cell death in response to invading pathogens. this cell death limits the spread of the infection and triggers whole plant antimicrobial and immune responses. the signaling network connecting molecular recognition of pathogens to these responses is a prime target for manipulation in genetic engineering strategies designed to improve crop plant disease resistance. moreover, as alterations to metabolism can be misinterpreted as pathogen infection, successful plant met ...	2004	15058987
comparative genomics of gene-family size in closely related bacteria.	the wealth of genomic data in bacteria is helping microbiologists understand the factors involved in gene innovation. among these, the expansion and reduction of gene families appears to have a fundamental role in this, but the factors influencing gene family size are unclear.	2004	15059260
gldi is a lipoprotein that is required for flavobacterium johnsoniae gliding motility and chitin utilization.	cells of flavobacterium johnsoniae glide rapidly over surfaces by an unknown mechanism. seven genes (glda, gldb, gldd, gldf, gldg, gldh, and ftsx) that are required for gliding motility have been described. complementation of the nonmotile mutants uw102-41, uw102-85, and uw102-92 identified another gene, gldi, that is required for gliding motility. gldi mutants formed nonspreading colonies, and individual cells were completely nonmotile. they were also resistant to bacteriophages that infect wil ...	2004	15060031
characterization of the cis-acting regulatory element controlling hrpb-mediated activation of the type iii secretion system and effector genes in ralstonia solanacearum.	the ability of ralstonia solanacearum to cause disease on plants depends on its type iii secretion system (ttss) encoded by hrp genes. the expression of hrp genes and known ttss substrates is coordinately regulated by hrpb, a member of the arac family of transcriptional regulators. two hrpb-regulated promoters (hrpy and popabc) were characterized by deletion analysis, and the hrpb-dependent activation of these promoters was found to be conferred by a 25-nucleotide dna element, the hrp(ii) box (t ...	2004	15060033
genetic analysis of the salmonella enterica type iii secretion-associated atpase invc defines discrete functional domains.	an essential component of all type iii secretion systems is a highly conserved atpase that shares significant amino acid sequence similarity to the beta subunit of the f(0)f(1) atpases and is thought to provide the energy for the secretion process. we have performed a genetic and functional analysis of invc, the atpase associated with the salmonella enterica type iii secretion system encoded within its pathogenicity island 1. through a mutagenesis analysis, we have identified amino acid residues ...	2004	15060043
characterization of cfa1, a monofunctional acyl carrier protein involved in the biosynthesis of the phytotoxin coronatine.	cfa1 was overproduced in escherichia coli and pseudomonas syringae, and the degree of 4'-phosphopantetheinylation was determined. the malonyl-coenzyme a:acyl carrier protein transacylase (fabd) of p. syringae was overproduced and shown to catalyze malonylation of cfa1, suggesting that fabd plays a role in coronatine biosynthesis. highly purified cfa1 did not exhibit self-malonylation activity.	2004	15060056
the timing of senescence and response to pathogens is altered in the ascorbate-deficient arabidopsis mutant vitamin c-1.	the ozone-sensitive arabidopsis mutant vitamin c-1 (vtc1) is deficient in l-ascorbic acid (asa) due to a mutation in gdp-man pyrophosphorylase (conklin et al., 1999), an enzyme involved in the asa biosynthetic pathway (smirnoff et al., 2001). in this study, the physiology of this asa deficiency was initially investigated in response to biotic (virulent pathogens) stress and subsequently with regards to the onset of senescence. infection with either virulent pseudomonas syringae or peronospora pa ...	2004	15064386
evolution of the core genome of pseudomonas syringae, a highly clonal, endemic plant pathogen.	pseudomonas syringae is a common foliar bacterium responsible for many important plant diseases. we studied the population structure and dynamics of the core genome of p. syringae via multilocus sequencing typing (mlst) of 60 strains, representing 21 pathovars and 2 nonpathogens, isolated from a variety of plant hosts. seven housekeeping genes, dispersed around the p. syringae genome, were sequenced to obtain 400 to 500 nucleotides per gene. forty unique sequence types were identified, with most ...	2004	15066790
identification of the bacterial community of maple sap by using amplified ribosomal dna (rdna) restriction analysis and rdna sequencing.	the bacterial community of maple sap was characterized by analysis of samples obtained at the taphole of maple trees for the 2001 and 2002 seasons. among the 190 bacterial isolates, 32 groups were formed according to the similarity of the banding patterns obtained by amplified ribosomal dna restriction analysis (ardra). a subset of representative isolates for each ardra group was identified by 16s rrna gene fragment sequencing. results showed a wide variety of organisms, with 22 different genera ...	2004	15066796
urease-encoding genes in ammonia-oxidizing bacteria.	many but not all ammonia-oxidizing bacteria (aob) produce urease (urea amidohydrolase, ec 3.5.1.5) and are capable of using urea for chemolithotrophic growth. we sequenced the urease operons from two aob, the beta-proteobacterium nitrosospira sp. strain npav and the gamma-proteobacterium nitrosococcus oceani. in both organisms, all seven urease genes were contiguous: the three structural urease genes ureabc were preceded and succeeded by the accessory genes ured and ureefg, respectively. green f ...	2004	15066830
proline accumulation and atp5cs2 gene activation are induced by plant-pathogen incompatible interactions in arabidopsis.	accumulation of free l-proline (pro) is a typical stress response incited by osmotic injuries in plants and microorganisms. although the protective role of pro in osmotic stress is not well understood, it is thought to function as compatible osmolyte or as a scavenger of reactive oxygen species (ros). here we show that, in arabidopsis thaliana, pro biosynthesis can be activated by incompatible plant-pathogen interactions triggering a hypersensitive response (hr). pro accumulates in leaf tissues ...	2004	15077666
feedback control of the arabidopsis hypersensitive response.	the plant hypersensitive response (hr) to avirulent bacterial pathogens results from programmed cell death of plant cells in the infected region. ion leakage and changes in signaling components associated with hr progression were measured. these studies compared arabidopsis mutants affecting feedback loops with wild-type plants, with timepoints taken hourly. in response to pseudomonas syringae pv. tomato dc3000 x avrb, npr1-2 mutant plants showed increased ion leakage relative to wild-type plant ...	2004	15077668
bacterial disease resistance in arabidopsis through flagellin perception.	plants and animals recognize microbial invaders by detecting pathogen-associated molecular patterns (pamps) such as flagellin. however, the importance of flagellin perception for disease resistance has, until now, not been demonstrated. here we show that treatment of plants with flg22, a peptide representing the elicitor-active epitope of flagellin, induces the expression of numerous defence-related genes and triggers resistance to pathogenic bacteria in wild-type plants, but not in plants carry ...	2004	15085136
structural and genetic characterization of glycosylation of type a flagellin in pseudomonas aeruginosa.	type a flagellins from two strains of pseudomonas aeruginosa, strains pak and jj692, were found to be glycosylated with unique glycan structures. in both cases, two sites of o-linked glycosylation were identified on each monomer, and these sites were localized to the central, surface-exposed domain of the monomer in the assembled filament. the pak flagellin was modified with a heterogeneous glycan comprising up to 11 monosaccharide units that were o linked through a rhamnose residue to the prote ...	2004	15090491
enzymatic characterization of a prokaryotic urea carboxylase.	we identified the first prokaryotic urea carboxylase (uca) from a member of the alpha subclass of the class proteobacteria, oleomonas sagaranensis. this enzyme (o. sagaranensis uca) was composed of 1,171 amino acids, and its n-terminal region resembled the biotin carboxylase domains of various biotin-dependent carboxylases. the c-terminal region of the enzyme harbored the met-lys-met motif found in biotin carboxyl carrier proteins. the primary structure of the enzyme was 45% identical to that of ...	2004	15090492
divergence and redundancy of 16s rrna sequences in genomes with multiple rrn operons.	the level of sequence heterogeneity among rrn operons within genomes determines the accuracy of diversity estimation by 16s rrna-based methods. furthermore, the occurrence of widespread horizontal gene transfer (hgt) between distantly related rrn operons casts doubt on reconstructions of phylogenetic relationships. for this study, patterns of distribution of rrn copy numbers, interoperonic divergence, and redundancy of 16s rrna sequences were evaluated. bacterial genomes display up to 15 operons ...	2004	15090503
origin and diversity of alginate lyases of families pl-5 and -7 in sphingomonas sp. strain a1.	sphingomonas sp. strain a1 has three endotype alginate lyases (a1-i, a1-ii [family pl-7], and a1-iii [family pl-5]), each of which is encoded by a single gene. in addition to those of these lyases, a gene (the a1-ii' gene) showing significant identity with the a1-ii gene was present in the bacterial genome and coded for an alginate lyase with broad substrate specificity. since no expression of a1-ii' was observed even in bacterial cells grown on alginate, the a1-ii' gene was thought to be a sile ...	2004	15090531
segmentally variable genes: a new perspective on adaptation.	genomic sequence variation is the hallmark of life and is key to understanding diversity and adaptation among the numerous microorganisms on earth. analysis of the sequenced microbial genomes suggests that genes are evolving at many different rates. we have attempted to derive a new classification of genes into three broad categories: lineage-specific genes that evolve rapidly and appear unique to individual species or strains; highly conserved genes that frequently perform housekeeping function ...	2004	15094797
light conditions influence specific defence responses in incompatible plant-pathogen interactions: uncoupling systemic resistance from salicylic acid and pr-1 accumulation.	in incompatible plant-pathogen interactions, disease resistance is generated by rapid activation of a multitude of plant defence reactions. little is known about the dependency of these resistance responses on external factors. the plasticity of plant defence mechanisms in terms of light conditions is studied here. interaction of arabidopsis thaliana (l.) heynh. with an avirulent strain of pseudomonas syringae pv. maculicola in the dark resulted in increased apoplastic bacterial growth and there ...	2004	15098125
functional transfer of salmonella pathogenicity island 2 to salmonella bongori and escherichia coli.	the type iii secretion system (t3ss) encoded by the salmonella pathogenicity island 2 (spi2) has a central role in systemic infections by salmonella enterica and for the intracellular phenotype. intracellular s. enterica uses the spi2-encoded t3ss to translocate a set of effector proteins into the host cell, which modify host cell functions, enabling intracellular survival and replication of the bacteria. we sought to determine whether specific functions of the spi2-encoded t3ss can be transferr ...	2004	15102800
the defh9-iaam auxin-synthesizing gene increases plant fecundity and fruit production in strawberry and raspberry.	the defh9-iaam gene fusion which is expressed specifically in placenta/ovules and promotes auxin-synthesis confers parthenocarpic fruit development to eggplant, tomato and tobacco. transgenic defh9-iaam eggplants and tomatoes show increased fruit production due mainly to an improved fruit set. however, the weight of the fruits is also frequently increased.	2004	15113427
analysis of nitric oxide signaling functions in tobacco cells challenged by the elicitor cryptogein.	nitric oxide (no) has recently emerged as an important cellular mediator in plant defense responses. however, elucidation of the biochemical mechanisms by which no participates in this signaling pathway is still in its infancy. we previously demonstrated that cryptogein, an elicitor of tobacco defense responses, triggers a no burst within minutes in epidermal sections from tobacco leaves (nicotiana tabacum cv xanthi). here, we investigate the signaling events that mediate no production, and anal ...	2004	15122020
a novel cost of r gene resistance in the presence of disease.	resistance responses can impose fitness costs when pests are absent. here, we test whether the induction of resistance can decrease fitness even in plants under attack; we call this potential outcome a net cost with attack. using lines in which genetic background was controlled, we investigated whether susceptible arabidopsis thaliana plants can outperform r gene resistant plants when infected with pathogens. for the r gene rps2, there was a fitness benefit of resistance in the presence of intra ...	2004	15122498
the pseudomonas syringae genome encodes a combined mannuronan c-5-epimerase and o-acetylhydrolase, which strongly enhances the predicted gel-forming properties of alginates.	alginates are industrially important, linear copolymers of beta-d-mannuronic acid (m) and its c-5-epimer alpha-l-guluronic acid (g). the g residues originate from a postpolymerization reaction catalyzed by mannuronan c-5-epimerases (mes), leading to extensive variability in m/g ratios and distribution patterns. alginates containing long continuous stretches of g residues (g blocks) can form strong gels, a polymer type not found in alginate-producing bacteria belonging to the genus pseudomonas. h ...	2004	15123694
silencing of subfamily i of protein phosphatase 2a catalytic subunits results in activation of plant defense responses and localized cell death.	the central importance of protein phosphorylation in plant defense responses has been demonstrated by the isolation of several disease-resistance genes that encode protein kinases. in addition, there are many reports of changes in protein phosphorylation accompanying plant responses to pathogens. in contrast, little is known about the role of protein dephosphorylation in regulating plant defenses. we report that expression of the lepp2ac1 gene, which encodes a catalytic subunit of the heterotrim ...	2004	15125764
negative cross-communication among wheat rhizosphere bacteria: effect on antibiotic production by the biological control bacterium pseudomonas aureofaciens 30-84.	phenazine antibiotic production in the biological control bacterium pseudomonas aureofaciens 30-84 is regulated in part via the phzr/phzi n-acyl homoserine lactone (ahl) system. previous work showed that a subpopulation of the wheat rhizosphere community positively affected phenazine gene expression in strain 30-84 via ahl signals (e. a. pierson, d. w. wood, j. a. cannon, f. m. blachere, and l. s. pierson iii, mol. plant-microbe interact. 11:1078-1084, 1998). in the present work, a second subpop ...	2004	15128573
citrx thioredoxin interacts with the tomato cf-9 resistance protein and negatively regulates defence.	to identify proteins involved in tomato cf-9 resistance protein function, a yeast two-hybrid screen was undertaken using the cytoplasmic c-terminus of cf-9 as bait. a thioredoxin-homologous clone, interacting specifically with cf-9, was identified and called citrx (cf-9-interacting thioredoxin). virus-induced gene silencing (vigs) of citrx resulted in an accelerated cf-9/avr9-triggered hypersensitive response in both tomato and nicotiana benthamiana, accompanied by enhanced accumulation of react ...	2004	15131698
the role of the jasmonate response in plant susceptibility to diverse pathogens with a range of lifestyles.	plants defend themselves against attack from insects and pathogens with various resistance strategies. the jasmonate and salicylate signaling pathways are two induced responses that protect plants against these attackers. knowledge of the range of organisms that are affected by each response is important for understanding how plants coordinate their defenses against multiple attackers and the generality of effect of different resistance mechanisms. the jasmonate response is known to protect plan ...	2004	15133157
proton-transfer-reaction mass spectrometry as a new tool for real time analysis of root-secreted volatile organic compounds in arabidopsis.	plant roots release about 5% to 20% of all photosynthetically-fixed carbon, and as a result create a carbon-rich environment for numerous rhizosphere organisms, including plant pathogens and symbiotic microbes. although some characterization of root exudates has been achieved, especially of secondary metabolites and proteins, much less is known about volatile organic compounds (vocs) released by roots. in this communication, we describe a novel approach to exploring these rhizosphere vocs and th ...	2004	15141066
the hopptof locus of pseudomonas syringae pv. tomato dc3000 encodes a type iii chaperone and a cognate effector.	type iii secretion systems are highly conserved among gram-negative plant and animal pathogenic bacteria. through the type iii secretion system, bacteria inject a number of virulence proteins into the host cells. analysis of the whole genome sequence of pseudomonas syringae pv. tomato dc3000 strain identified a locus, named hopptof, that is homologous to the avirulence gene locus avrpphf in p. syringae pv. phaseolicola. the hopptof locus harbors two genes, shcf(pto) and hopf(pto), that are prece ...	2004	15141948
arabidopsis dnd2, a second cyclic nucleotide-gated ion channel gene for which mutation causes the "defense, no death" phenotype.	a previous mutant screen identified arabidopsis dnd1 and dnd2 "defense, no death" mutants, which exhibit loss of hypersensitive response (hr) cell death without loss of gene-for-gene resistance. the dnd1 phenotype is caused by mutation of the gene encoding cyclic nucleotide-gated (cng) ion channel atcngc2. this study characterizes dnd2 plants. even in the presence of high titers of pseudomonas syringae expressing avrrpt2, most leaf mesophyll cells in the dnd2 mutant exhibited no hr. these plants ...	2004	15141955
regulation of ahl production and its contribution to epiphytic fitness in pseudomonas syringae.	pseudomonas syringae forms large cell aggregates that are more stress tolerant than solitary cells during epiphytic growth on plants. the differential survival of aggregates on leaves suggests that epiphytic fitness traits may be controlled in a density-dependent manner via cell-cell signaling. we investigated this hypothesis in p. syringae b728a. synthesis of n-acyl-homoserine lactone (ahl), 3-oxo-hexanoyl homoserine lactone, and the expression of the gene encoding ahl synthase ahli were maxima ...	2004	15141956
phenylpropanoids, phenylalanine ammonia lyase and peroxidases in elicitor-challenged cassava (manihot esculenta) suspension cells and leaves.	control of diseases in the key tropical staple, cassava, is dependent on resistant genotypes, but the innate mechanisms are unknown. the aim was to study phenylpropanoids and associated enzymes as possible defence components.	2004	15145789
suppression of pathogen-inducible no synthase (inos) activity in tomato increases susceptibility to pseudomonas syringae.	inducible no synthase (inos) activity is induced upon pathogen inoculation in resistant, but not susceptible, tobacco and arabidopsis plants. it was shown recently that a variant form of the arabidopsis p protein (atvarp) has inos activity. p protein is part of the glycine decarboxylase complex (gdc). it is unclear whether p protein also has inos activity and, if so, whether atvarp, p, or both, play a role in plant defense. here, we show that inos activity is induced in both resistant and suscep ...	2004	15146069
the pseudomonas syringae hopptov protein is secreted in culture and translocated into plant cells via the type iii protein secretion system in a manner dependent on the shcv type iii chaperone.	the bacterial plant pathogen pseudomonas syringae depends on a type iii protein secretion system and the effector proteins that it translocates into plant cells to cause disease and to elicit the defense-associated hypersensitive response on resistant plants. the availability of the p. syringae pv. tomato dc3000 genome sequence has resulted in the identification of many novel effectors. we identified the hopptov effector gene on the basis of its location next to a candidate type iii chaperone (t ...	2004	15150250
the global arginine regulator argr controls expression of argf in pseudomonas syringae pv. phaseolicola but is not required for the synthesis of phaseolotoxin or for the regulated expression of argk.	in pseudomonas syringae pv. phaseolicola the enzyme ornithine carbamoyltransferase (octase), encoded by argf, is negatively regulated by argr, similar to what has been reported for pseudomonas aeruginosa. however, production of the phaseolotoxin-resistant octase encoded by argk, synthesis of phaseolotoxin, and infectivity for bean pods occur independently of the argr protein.	2004	15150254
comparison of atpase-encoding type iii secretion system hrcn genes in biocontrol fluorescent pseudomonads and in phytopathogenic proteobacteria.	type iii protein secretion systems play a key role in the virulence of many pathogenic proteobacteria, but they also occur in nonpathogenic, plant-associated bacteria. certain type iii protein secretion genes (e.g., hrcc) have been found in pseudomonas sp. strain sbw25 (and other biocontrol pseudomonads), but other type iii protein secretion genes, such as the atpase-encoding gene hrcn, have not been found. using both colony hybridization and a pcr approach, we show here that hrcn is nevertheles ...	2004	15345390
regulation of the n-acyl homoserine lactone-dependent quorum-sensing system in rhizosphere pseudomonas putida wcs358 and cross-talk with the stationary-phase rpos sigma factor and the global regulator gaca.	quorum sensing is a cell population-density dependent regulatory system which in gram-negative bacteria often involves the production and detection of n-acyl homoserine lactones (ahls). some pseudomonas putida strains have been reported to produce ahls, and one quorum-sensing locus has been identified. however, it appears that the majority of strains do not produce ahls. in this study we report the identification and regulation of the ahl-dependent system of rhizosphere p. putida wcs358. this sy ...	2004	15345437
the pepper transcription factor capf1 confers pathogen and freezing tolerance in arabidopsis.	an erf/ap2-type transcription factor (capf1) was isolated by differential-display reverse transcription-pcr, following inoculation of the soybean pustule pathogen xanthomonas axonopodis pv glycines 8ra, which induces hypersensitive response in pepper (capsicum annuum) leaves. capf1 mrna was induced under conditions of biotic and abiotic stress. higher levels of capf1 transcripts were observed in disease-resistant tissue compared with susceptible tissue. capf1 expression was additionally induced ...	2004	15347795
genetic elucidation of nitric oxide signaling in incompatible plant-pathogen interactions.	recent experiments indicate that nitric oxide (no) plays a pivotal role in disease resistance and several other physiological processes in plants. however, most of the current information about the function of no in plants is based on pharmacological studies, and additional approaches are therefore required to ascertain the role of no as an important signaling molecule in plants. we have expressed a bacterial nitric oxide dioxygenase (nod) in arabidopsis plants and/or avirulent pseudomonas syrin ...	2004	15347797
modulation of the biological activity of a tobacco ltp1 by lipid complexation.	plant lipid transfer proteins (ltps) are small, cysteine-rich proteins secreted into the extracellular space. they belong to the pathogenesis-related proteins (pr-14) family and are believed to be involved in several physiological processes including plant disease resistance, although their precise biological function is still unknown. here, we show that a recombinant tobacco ltp1 is able to load fatty acids and jasmonic acid. this ltp1 binds to specific plasma membrane sites, previously charact ...	2004	15356262
arabidopsis rin4 negatively regulates disease resistance mediated by rps2 and rpm1 downstream or independent of the ndr1 signal modulator and is not required for the virulence functions of bacterial type iii effectors avrrpt2 or avrrpm1.	bacterial pathogens deliver type iii effector proteins into the plant cell during infection. on susceptible (r) hosts, type iii effectors can contribute to virulence. some trigger the action of specific disease resistance (r) gene products. the activation of r proteins can occur indirectly via modification of a host target. thus, at least some type iii effectors are recognized at site(s) where they may act as virulence factors. these data indicate that a type iii effector's host target might be ...	2004	15361584
arabidopsis nonsymbiotic hemoglobin ahb1 modulates nitric oxide bioactivity.	nitric oxide (no) is a widespread signaling molecule, and numerous targets of its action exist in plants. whereas the activity of no in erythrocytes, microorganisms, and invertebrates has been shown to be regulated by several hemoglobins, the function of plant hemoglobins in no detoxification has not yet been elucidated. here, we show that arabidopsis thaliana nonsymbiotic hemoglobin ahb1 scavenges no through production of s-nitrosohemoglobin and reduces no emission under hypoxic stress, indicat ...	2004	15367716
a patch of surface-exposed residues mediates negative regulation of immune signaling by tomato pto kinase.	tomato (lycopersicon esculentum) pto kinase specifically recognizes the pseudomonas effector proteins avrpto and avrptob, leading to induction of defense responses and hypersensitive cell death. structural modeling of pto combined with site-directed mutagenesis identified a patch of surface-exposed residues required for native regulation of signaling. mutations in this area resulted in constitutive gain-of-function (cgf) forms of pto that activated avrpto-independent cell death via the cognate s ...	2004	15367718