Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
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| cloning of chlorophyllase, the key enzyme in chlorophyll degradation: finding of a lipase motif and the induction by methyl jasmonate. | chlorophyllase (chlase) is the first enzyme involved in chlorophyll (chl) degradation and catalyzes the hydrolysis of ester bond to yield chlorophyllide and phytol. in the present study, we isolated the chlase cdna. we synthesized degenerate oligo dna probes based on the internal amino acid sequences of purified chlase from chenopodium album, screened the c. album cdna library, and cloned a cdna (caclh, c. album chlorophyll-chlorophyllido hydrolase). the deduced amino acid sequence (347 aa resid ... | 1999 | 10611389 |
| the virr response regulator from clostridium perfringens binds independently to two imperfect direct repeats located upstream of the pfoa promoter. | regulation of toxin production in the gram-positive anaerobe clostridium perfringens occurs at the level of transcription and involves a two-component signal transduction system. the sensor histidine kinase is encoded by the virs gene, while its cognate response regulator is encoded by the virr gene. we have constructed a virr expression plasmid in escherichia coli and purified the resultant his-tagged virr protein. gel mobility shift assays demonstrated that virr binds to the region upstream of ... | 2000 | 10613863 |
| production and comparison of peptide siderophores from strains of distantly related pathovars of pseudomonas syringae and pseudomonas viridiflava lmg 2352. | the production of peptide siderophores and the variation in siderophore production among strains of pseudomonas syringae and pseudomonas viridiflava were investigated. an antibiose test was used to select a free amino acid-containing agar medium favorable for production of fluorescent siderophores by two p. syringae strains. a culture technique in which both liquid and solid asparagine-containing culture media were used proved to be reproducible and highly effective for inducing production of si ... | 2000 | 10618243 |
| role of leaf surface sugars in colonization of plants by bacterial epiphytes. | the relationship between nutrients leached onto the leaf surface and the colonization of plants by bacteria was studied by measuring both the abundance of simple sugars and the growth of pseudomonas fluorescens on individual bean leaves. data obtained in this study indicate that the population size of epiphytic bacteria on plants under environmentally favorable conditions is limited by the abundance of carbon sources on the leaf surface. sugars were depleted during the course of bacterial coloni ... | 2000 | 10618250 |
| the pspa protein of escherichia coli is a negative regulator of sigma(54)-dependent transcription. | in eubacteria, expression of genes transcribed by an rna polymerase holoenzyme containing the alternate sigma factor sigma(54) is positively regulated by proteins belonging to the family of enhancer-binding proteins (ebps). these proteins bind to upstream activation sequences and are required for the initiation of transcription at the sigma(54)-dependent promoters. they are typically inactive until modified in their n-terminal regulatory domain either by specific phosphorylation or by the bindin ... | 2000 | 10629175 |
| characterization of p69e and p69f, two differentially regulated genes encoding new members of the subtilisin-like proteinase family from tomato plants. | subtilisin-like proteins represent an ancient family of serine proteases that are extremely widespread in living organisms. we report here the structure and genomic organization of two new transcriptionally active genes encoding proteins that belong to the p69 family of subtilisin-like proteases from tomato (lycopersicon esculentum) plants. the two new members, p69e and p69f, are organized in a cluster and arranged in a tandem form. mrna expression analysis and studies of transgenic arabidopsis ... | 2000 | 10631250 |
| helicobacter pylori uptake and efflux: basis for intrinsic susceptibility to antibiotics in vitro. | we previously demonstrated (m. m. exner, p. doig, t. j. trust, and r. e. w. hancock, infect. immun. 63:1567-1572, 1995) that helicobacter pylori has at least one nonspecific porin, hope, which has a low abundance in the outer membrane but forms large channels. h. pylori is relatively susceptible to most antimicrobial agents but less susceptible to the polycationic antibiotic polymyxin b. we demonstrate here that h. pylori is able to take up higher basal levels of the hydrophobic fluorescent prob ... | 2000 | 10639345 |
| isolation of neisseria gonorrhoeae mutants that show enhanced trafficking across polarized t84 epithelial monolayers. | initiation of a gonococcal infection involves attachment of neisseria gonorrhoeae to the plasma membrane of an epithelial cell in the mucosal epithelium and its internalization, transepithelial trafficking, and exocytosis from the basal membrane. piliation and expression of certain opa proteins and the immunoglobulin a1 protease influence the transcytosis process. we are interested in identifying other genetic determinants of n. gonorrhoeae that play a role in transcellular trafficking. using po ... | 2000 | 10639460 |
| crc is involved in catabolite repression control of the bkd operons of pseudomonas putida and pseudomonas aeruginosa. | crc (catabolite repression control) protein of pseudomonas aeruginosa has shown to be involved in carbon regulation of several pathways. in this study, the role of crc in catabolite repression control has been studied in pseudomonas putida. the bkd operons of p. putida and p. aeruginosa encode the inducible multienzyme complex branched-chain keto acid dehydrogenase, which is regulated in both species by catabolite repression. we report here that this effect is mediated in both species by crc. a ... | 2000 | 10648542 |
| bacterial cell surface display of an enzyme library for selective screening of improved cellulase variants. | the bacterial surface display method was used to selectively screen for improved variants of carboxymethyl cellulase (cmcase). a library of mutated cmcase genes generated by dna shuffling was fused to the ice nucleation protein (inp) gene so that the resulting fusion proteins would be displayed on the bacterial cell surface. some cells displaying mutant proteins grew more rapidly on carboxymethyl cellulose plates than controls, forming heterogeneous colonies. in contrast, cells displaying the no ... | 2000 | 10653752 |
| pathovars of pseudomonas syringae causing bacterial brown spot and halo blight in phaseolus vulgaris l. are distinguishable by ribotyping. | ribotyping was evaluated as a method to differentiate between pseudomonas syringae pv. phaseolicola and pv. syringae strains causing bacterial brown spot and halo blight diseases in phaseolus vulgaris l. ribotyping, with restriction enzymes bgli and sali and using the escherichia coli rrnb operon as the probe, differentiated 11 and 14 ribotypes, respectively, and a combination of data from both procedures yielded 19 combined ribotypes. cluster analysis of the combined ribotypes differentiated th ... | 2000 | 10653764 |
| cloning and expression in escherichia coli of 2-hydroxypropylphosphonic acid epoxidase from the fosfomycin-producing organism, pseudomonas syringae pb-5123. | the fosfomycin resistance gene, fosc, has been cloned from the fosfomycin-producing organism, pseudomonas syringae pb-5123. sequence analysis upstream of this gene found a new orf showing significant homology to 2-hydroxypropylphosphonic acid epoxidase from fosfomycin-producing streptomyces wedmorensis. the purified recombinant protein of this orf converted 2-hydroxypropylphosphonic acid to fosfomycin. this result clearly showed the orf to encode 2-hydroxypropylphosphonic acid epoxidase in pb-51 ... | 1999 | 10664856 |
| cell surface display of hepatitis b virus surface antigen by using pseudomonas syringae ice nucleation protein. | a new system designed for cell surface display of recombinant proteins on escherichia coli was evaluated for expression of eukaryotic viral antigens. the major surface antigen of hepatitis b virus (hbsag) was fused to the ice nucleation protein (inp), an outer membrane protein of pseudomonas syringae. western blotting, immunofluorescence microscopy, whole-cell elisa, and ice nucleation activity assay confirmed expression of recombinant proteins on the surface of escherichia coli. this study indi ... | 1999 | 10664968 |
| effects of calcium and calcium chelators on growth and morphology of escherichia coli l-form nc-7. | growth of a wall-less, l-form of escherichia coli specifically requires calcium, and in its absence, cells ceased dividing, became spherical, swelled, developed large vacuoles, and eventually lysed. the key cell division protein, ftsz, was present in the l-form at a concentration five times less than that in the parental strain. one interpretation of these results is that the l-form possesses an enzoskeleton partly regulated by calcium. | 2000 | 10671467 |
| expression and localization of nitrilase during symptom development of the clubroot disease in arabidopsis. | the expression of nitrilase in arabidopsis during the development of the clubroot disease caused by the obligate biotroph plasmodiophora brassicae was investigated. a time course study showed that only during the exponential growth phase of the clubs was nitrilase prominently enhanced in infected roots compared with controls. nit1 and nit2 are the nitrilase isoforms predominantly expressed in clubroot tissue, as shown by investigating promoter-beta-glucuronidase fusions of each. two peaks of bet ... | 2000 | 10677430 |
| isolation and characterization of powdery mildew-resistant arabidopsis mutants. | a compatible interaction between a plant and a pathogen is the result of a complex interplay between many factors of both plant and pathogen origin. our objective was to identify host factors involved in this interaction. these factors may include susceptibility factors required for pathogen growth, factors manipulated by the pathogen to inactivate or avoid host defenses, or negative regulators of defense responses. to this end, we identified 20 recessive arabidopsis mutants that do not support ... | 2000 | 10677553 |
| characterization of the foma and fomb gene products from streptomyces wedmorensis, which confer fosfomycin resistance on escherichia coli. | together, the foma and fomb genes in the fosfomycin biosynthetic gene cluster of streptomyces wedmorensis confer high-level fosfomycin resistance on escherichia coli. to elucidate their functions, the foma and fomb genes were overexpressed in e. coli and the gene products were characterized. the recombinant foma protein converted fosfomycin to fosfomycin monophosphate, which was inactive on e. coli, in the presence of a magnesium ion and atp. on the other hand, the recombinant fomb protein did n ... | 2000 | 10681332 |
| arabidopsis cytochrome p450s that catalyze the first step of tryptophan-dependent indole-3-acetic acid biosynthesis. | plants synthesize numerous secondary metabolites that are used as developmental signals or as defense against pathogens. tryptophan (trp)-derived secondary metabolites include camalexin, indole glucosinolates, and indole-3-acetic acid (iaa); however, the steps in their synthesis from trp or its precursors remain unclear. we have identified two arabidopsis cytochrome p450s (cyp79b2 and cyp79b3) that can convert trp to indole-3-acetaldoxime (iaox), a precursor to iaa and indole glucosinolates. | 2000 | 10681464 |
| the gene coding for the hrp pilus structural protein is required for type iii secretion of hrp and avr proteins in pseudomonas syringae pv. tomato. | bacterial surface appendages called pili often are associated with dna and/or protein transfer between cells. the exact function of pili in the transfer process is not understood and is a matter of considerable debate. the hrp pilus is assembled by the hrp type iii protein secretion system of pseudomonas syringae pv. tomato (pst) strain dc3000. in this study, we show that the hrpa gene, which encodes the major subunit of the hrp pilus, is required for secretion of putative virulence proteins, su ... | 2000 | 10681465 |
| molecular cloning of a defense-response-related cytochrome p450 gene from tobacco. | plant defenses against pathogen attack involve a series of inducible responses that contribute to resistance. tobacco leaves injected with hwc (hyphal wall components prepared from phytophthora infestans) elicitor showed typical defense responses, including the induction of localized necrosis and the accumulation of pathogenesis-related proteins. in order to elucidate the molecular mechanisms by which plant defense systems are activated, we screened tobacco plants for genes differentially expres ... | 1999 | 10682345 |
| functional analysis of pvds, an iron starvation sigma factor of pseudomonas aeruginosa. | in pseudomonas aeruginosa, iron modulates gene expression through a cascade of negative and positive regulatory proteins. the master regulator fur is involved in iron-dependent repression of several genes. one of these genes, pvds, was predicted to encode a putative sigma factor responsible for the transcription of a subset of genes of the fur regulon. pvds appears to belong to a structurally and functionally distinct subgroup of the extracytoplasmic function family of alternative sigma factors. ... | 2000 | 10692351 |
| identification of genes in the rosr regulon of rhizobium etli. | rosr is a determinant of nodulation competitiveness and cell surface characteristics of rhizobium etli and has sequence similarity to a family of transcriptional repressors. to understand how rosr affects these phenotypes, we mutagenized a rosr mutant derivative of r. etli strain ce3 with a mini-tn5 that contains a promoterless gusa gene at one end, which acts as a transcriptional reporter. using a mass-mating technique, we introduced rosr into each mutant in trans and screened for mutants that ... | 2000 | 10692377 |
| the right end of the vir region of an octopine-type ti plasmid contains four new members of the vir regulon that are not essential for pathogenesis. | we sequenced the vird-vire, vire-virf, and virf-t-dna intergenic regions of an octopine ti plasmid. four newly described genes were induced by the vir gene inducer acetosyringone, two of which are conserved in the nopaline-type ti plasmid ptic58. one gene resembles a family of phosphatase genes. each of these genes is dispensable for tumorigenesis. | 2000 | 10692388 |
| frequency and biodiversity of 2,4-diacetylphloroglucinol-producing bacteria isolated from the maize rhizosphere at different stages of plant growth. | a pseudomonas 2,4-diacetylphloroglucinol (dapg)-producing population that occurred naturally on the roots, in rhizosphere soil of zea mays and in the nonrhizosphere soil was investigated in order to assess the microbial diversity at five stages of plant growth. a total of 1,716 isolates were obtained, and 188 of these isolates were able to produce dapg. dapg producers were isolated at each stage of plant growth, indicating that the maize rhizosphere is colonized by natural dapg producers through ... | 2000 | 10698757 |
| characterization and determination of origin of lactic acid bacteria from a sorghum-based fermented weaning food by analysis of soluble proteins and amplified fragment length polymorphism fingerprinting. | the group that includes the lactic acid bacteria is one of the most diverse groups of bacteria known, and these organisms have been characterized extensively by using different techniques. in this study, 180 lactic acid bacterial strains isolated from sorghum powder (44 strains) and from corresponding fermented (93 strains) and cooked fermented (43 strains) porridge samples that were prepared in 15 households were characterized by using biochemical and physiological methods, as well as by analyz ... | 2000 | 10698775 |
| survival and epiphytic fitness of a nonpathogenic mutant of xanthomonas campestris pv. glycines. | xanthomonas campestris pv. glycines is the causal agent of bacterial pustule disease of soybeans. the objective of this work was to construct a nonpathogenic mutant derived from the pathogenic wild-type strain yr32 and to evaluate its effectiveness in preventing growth of its parent on the soybean phyllosphere. a mini-tn5-derived transposon was used to generate nonpathogenic mutants. southern hybridization and pulsed-field gel electrophoresis confirmed the presence of a single transposon in each ... | 2000 | 10698789 |
| identification of arabidopsis mutants exhibiting an altered hypersensitive response in gene-for-gene disease resistance. | a mutational study was carried out to isolate arabidopsis thaliana plants that exhibit full or partial disruption of the rps2-mediated hypersensitive response (hr) to pseudomonas syringae that express avrrpt2. five classes of mutants were identified including mutations at rps2, dnd mutations causing a "defense, no death" loss-of-hr phenotype, a lesion-mimic mutant that also exhibited an hr- phenotype, and a number of intermediate or partial-loss-of-hr mutants. surprisingly, many of these mutants ... | 2000 | 10707353 |
| syringolin-mediated activation of the pir7b esterase gene in rice cells is suppressed by phosphatase inhibitors. | inoculation of rice plants (oryza sativa) with the nonhost pathogen pseudomonas syringae pv. syringae leads to the activation of defense-related genes and ultimately to induced resistance against the rice blast fungus pyricularia oryzae. one of the molecular determinants of p. syringae pv. syringae that is recognized by the plant cells and evokes these defense responses is syringolin a, an elicitor that is secreted by the bacteria under appropriate conditions. in order to investigate signal tran ... | 2000 | 10707360 |
| salicylic acid mediated by the oxidative burst is a key molecule in local and systemic responses of cotton challenged by an avirulent race of xanthomonas campestris pv malvacearum. | we analyzed the production of reactive oxygen species, the accumulation of salicylic acid (sa), and peroxidase activity during the incompatible interaction between cotyledons of the cotton (gossypium hirsutum) cv reba b50/xanthomonas campestris pv malvacearum (xcm) race 18. sa was detected in petioles of cotyledons 6 h after infection and 24 h post inoculation in cotyledons and untreated leaves. the first peak of sa occurred 3 h after generation of superoxide (o(2)(.-)), and was inhibited by inf ... | 2000 | 10712539 |
| identification of two novel hrp-associated genes in the hrp gene cluster of xanthomonas oryzae pv. oryzae. | we have cloned a hrp gene cluster from xanthomonas oryzae pv. oryzae. bacteria with mutations in the hrp region have reduced growth in rice leaves and lose the ability to elicit a hypersensitive response (hr) on the appropriate resistant cultivars of rice and the nonhost plant tomato. a 12,165-bp portion of nucleotide sequence from the presumed left end and extending through the hrpb operon was determined. the region was most similar to hrp genes from xanthomonas campestris pv. vesicatoria and r ... | 2000 | 10714988 |
| purification and characterization of a catalase from the facultatively psychrophilic bacterium vibrio rumoiensis s-1(t) exhibiting high catalase activity. | catalase from the facultatively psychrophilic bacterium vibrio rumoiensis s-1(t), which was isolated from an environment exposed to h(2)o(2) and exhibited high catalase activity, was purified and characterized, and its localization in the cell was determined. its molecular mass was 230 kda, and the molecule consisted of four identical subunits. the enzyme, which was not apparently reduced by dithionite, showed a soret peak at 406 nm in a resting state. the catalytic activity was 527,500 u. mg of ... | 2000 | 10714995 |
| characterization of the gene cluster involved in isoprene metabolism in rhodococcus sp. strain ad45. | the genes involved in isoprene (2-methyl-1,3-butadiene) utilization in rhodococcus sp. strain ad45 were cloned and characterized. sequence analysis of an 8.5-kb dna fragment showed the presence of 10 genes of which 2 encoded enzymes which were previously found to be involved in isoprene degradation: a glutathione s-transferase with activity towards 1,2-epoxy-2-methyl-3-butene (isoi) and a 1-hydroxy-2-glutathionyl-2-methyl-3-butene dehydrogenase (isoh). furthermore, a gene encoding a second gluta ... | 2000 | 10715003 |
| reply. establishing a paradigm for the generation of new s alleles | 2000 | 10715318 | |
| molecular and biological analysis of eight genetic islands that distinguish neisseria meningitidis from the closely related pathogen neisseria gonorrhoeae. | the pathogenic species neisseria meningitidis and neisseria gonorrhoeae cause dramatically different diseases despite strong relatedness at the genetic and biochemical levels. n. meningitidis can cross the blood-brain barrier to cause meningitis and has a propensity for toxic septicemia unlike n. gonorrhoeae. we previously used subtractive hybridization to identify dna sequences which might encode functions specific to bacteremia and invasion of the meninges because they are specific to n. menin ... | 2000 | 10722605 |
| arabidopsis rela/spot homologs implicate (p)ppgpp in plant signaling. | arabidopsis rpp5 is a member of a large class of pathogen resistance genes encoding nucleotide-binding sites and leucine-rich repeat domains. yeast two-hybrid analysis showed that rpp5 specifically interacts with at-rsh1, an arabidopsis rela/spot homolog. in escherichia coli, rela and spot determine the level of guanosine tetraphosphate (ppgpp) and guanosine pentaphosphate (pppgpp), which are the effector nucleotides of the bacterial stringent response. functional analysis in e. coli and in stre ... | 2000 | 10725385 |
| molecular cloning of a soybean class iii beta-1,3-glucanase gene that is regulated both developmentally and in response to pathogen infection. | we isolated and characterized a soybean gene (sgn1) encoding a basic beta-1,3-glucanase that is a plant class iii isoform of beta-1,3-glucanase. the deduced amino acid sequence of the sgn1 gene is similar to that of the pr-q'b gene, the basic class iii beta-1,3-glucanase of tomato. based on rna blot hybridization, sgn1 gene expression was detected in all tissues of 4-day old seedlings, but it was present only in root tissue of 30-day old plants. gus expression analysis carried out in transgenic ... | 2000 | 10725560 |
| a novel phenanthrene dioxygenase from nocardioides sp. strain kp7: expression in escherichia coli. | nocardioides sp. strain kp7 grows on phenanthrene but not on naphthalene. this organism degrades phenanthrene via 1-hydroxy-2-naphthoate, o-phthalate, and protocatechuate. the genes responsible for the degradation of phenanthrene to o-phthalate (phd) were found by southern hybridization to reside on the chromosome. a 10.6-kb dna fragment containing eight phd genes was cloned and sequenced. the phda, phdb, phdc, and phdd genes, which encode the alpha and beta subunits of the oxygenase component, ... | 2000 | 10735855 |
| roles of horizontal gene transfer and gene integration in evolution of 1,3-dichloropropene- and 1,2-dibromoethane-degradative pathways. | the haloalkane-degrading bacteria rhodococcus rhodochrous ncimb13064, pseudomonas pavonaceae 170, and mycobacterium sp. strain gp1 share a highly conserved haloalkane dehalogenase gene (dhaa). here, we describe the extent of the conserved dhaa segments in these three phylogenetically distinct bacteria and an analysis of their flanking sequences. the dhaa gene of the 1-chlorobutane-degrading strain ncimb13064 was found to reside within a 1-chlorobutane catabolic gene cluster, which also encodes a ... | 2000 | 10735862 |
| mechanism of inactivation of ornithine transcarbamoylase by ndelta -(n'-sulfodiaminophosphinyl)-l-ornithine, a true transition state analogue? crystal structure and implications for catalytic mechanism. | the crystal structure is reported at 1.8 a resolution of escherichia coli ornithine transcarbamoylase in complex with the active derivative of phaseolotoxin from pseudomonas syringae pv. phaseolicola, n(delta)-(n'-sulfodiaminophosphinyl)-l-ornithine. electron density reveals that the complex is not a covalent adduct as previously thought. kinetic data confirm that n(delta)-(n'-sulfodiaminophosphinyl)-l-ornithine exhibits reversible inhibition with a half-life in the order of approximately 22 h a ... | 2000 | 10747936 |
| inorganic polyphosphate is needed for swimming, swarming, and twitching motilities of pseudomonas aeruginosa. | polyphosphate kinase (ppk), encoded by the ppk gene, is the principal enzyme in many bacteria for the synthesis of inorganic polyphosphate (poly p) from atp. a knockout mutant in the ppk gene of pseudomonas aeruginosa pao1 is impaired in flagellar swimming motility on semisolid agar plates. the mutant is deficient in type iv pili-mediated twitching motility and in a "swarming motility" previously unobserved in p. aeruginosa. in swarming cultures, the polar monotrichous bacteria have differentiat ... | 2000 | 10758151 |
| atbi-1, a plant homologue of bax inhibitor-1, suppresses bax-induced cell death in yeast and is rapidly upregulated during wounding and pathogen challenge. | extensive searches have so far failed to identify functional plant homologues of the mammalian apoptotic machinery. here we report the isolation and characterisation of an arabidopsis thaliana homologue of human bax inhibitor-1, atbi-1, isolated during a differential screen of plants challenged with the phytopathogen pseudomonas syringae. atbi is a member of a small gene family in arabidopsis, members of which display extensive amino acid identity to human bi-1. atbi-1 is also functionally simil ... | 2000 | 10758491 |
| genotypic characterization of xanthomonad strains isolated from passion fruit plants (passiflora spp.) and their relatedness to different xanthomonas species. | the genetic diversity of 55 xanthomonad strains isolated from passion fruit plants (passiflora spp.) and identified as xanthomonas campestris pv. passiflorae was initially assessed by randomly amplified polymorphic dna (rapd) analysis. the strains showed a high level of polymorphism with almost unique fingerprints. fifteen clusters with a similarity of approximately 70% were identified, three of which were prevalent. there was a correlation between the clusters and the geographic origin of the s ... | 2000 | 10758892 |
| genome organization in dicots: genome duplication in arabidopsis and synteny between soybean and arabidopsis. | synteny between soybean and arabidopsis was studied by using conceptual translations of dna sequences from loci that map to soybean linkage groups a2, j, and l. synteny was found between these linkage groups and all four of the arabidopsis chromosomes, where genbank contained enough sequence for synteny to be identified confidently. soybean linkage group a2 (soya2) and arabidopsis chromosome i showed significant synteny over almost their entire lengths, with only 2-3 chromosomal rearrangements r ... | 2000 | 10759555 |
| structure of the o polysaccharide and serological classification of pseudomonas syringae pv. ribicola ncppb 1010. | the o polysaccharide (ops) moiety of the lipopolysaccharide (lps) of a phytopathogenic bacterium pseudomonas syringae pv. ribicola ncppb 1010 was studied by sugar and methylation analyses, smith degradation, and 1h- and 13c-nmr spectroscopy, including 2d cosy, tocsy, noesy and h-detected 1h,13c hmqc experiments. the ops structure was elucidated, and shown to be composed of branched pentasaccharide repeating units (o repeats) of two types, major (1) and minor (2), differing in the position of sub ... | 2000 | 10759863 |
| the gacs sensor kinase regulates alginate and poly-beta-hydroxybutyrate production in azotobacter vinelandii. | azotobacter vinelandii produces two polymers: the extracellular polysaccharide alginate and the intracellular polyester poly-beta-hydroxybutyrate (phb). a cosmid clone (psmu588) from an a. vinelandii gene library diminished alginate production by a. vinelandii mucoid strain atcc 9046. the nucleotide sequence and predicted amino acid sequence of the locus responsible for the mucoidy suppression revealed 65% identity to pseudomonas gacs, a transmembrane sensor kinase of the two-component regulator ... | 2000 | 10762268 |
| rpma is required for nonopsonic phagocytosis of pseudomonas aeruginosa. | pseudomonas aeruginosa causes severe respiratory tract infections in patients with cystic fibrosis (cf). we have been examining nonopsonic phagocytosis of p. aeruginosa by macrophages. to study the p. aeruginosa-macrophage interaction at the molecular level, we have constructed a transposon tn5g bank in a clinical isolate of p. aeruginosa (strain 4020) and identified mutants resistant to nonopsonic phagocytosis. phagocytosis-resistant mutants were enriched by passaging the transposon bank over 1 ... | 2000 | 10768936 |
| syringomycin e inhibition of saccharomyces cerevisiae: requirement for biosynthesis of sphingolipids with very-long-chain fatty acids and mannose- and phosphoinositol-containing head groups. | syringomycin e is an antifungal cyclic lipodepsinonapeptide that inhibits the growth of saccharomyces cerevisiae by interaction with the plasma membrane. a screen conducted to find the yeast genes necessary for its fungicidal action identified two novel syringomycin e response genes, syr3 and syr4. a syr3 mutant allele was complemented by elo2 and elo3. these genes encode enzymes that catalyze the elongation of sphingolipid very long chain fatty acids. tetrad analysis showed that syr3 was elo2. ... | 2000 | 10770748 |
| the pseudomonas syringae hrp pathogenicity island has a tripartite mosaic structure composed of a cluster of type iii secretion genes bounded by exchangeable effector and conserved effector loci that contribute to parasitic fitness and pathogenicity in plants. | the plant pathogenic bacterium pseudomonas syringae is divided into pathovars differing in host specificity, with p. syringae pv. syringae (psy) and p. syringae pv. tomato (pto) representing particularly divergent pathovars. p. syringae hrp/hrc genes encode a type iii protein secretion system that appears to translocate avr and hop effector proteins into plant cells. dna sequence analysis of the hrp/hrc regions in psy 61, psy b728a, and pto dc3000 has revealed a hrp pathogenicity island (pai) wi ... | 2000 | 10781092 |
| haloalkane-utilizing rhodococcus strains isolated from geographically distinct locations possess a highly conserved gene cluster encoding haloalkane catabolism. | the sequences of the 16s rrna and haloalkane dehalogenase (dhaa) genes of five gram-positive haloalkane-utilizing bacteria isolated from contaminated sites in europe, japan, and the united states and of the archetypal haloalkane-degrading bacterium rhodococcus sp. strain ncimb13064 were compared. the 16s rrna gene sequences showed less than 1% sequence divergence, and all haloalkane degraders clearly belonged to the genus rhodococcus. all strains shared a completely conserved dhaa gene, suggesti ... | 2000 | 10781539 |
| the arcb sensor kinase of escherichia coli: genetic exploration of the transmembrane region. | the arc two-component signal transduction system of escherichia coli regulates the expression of numerous operons in response to respiratory growth conditions. cellular redox state or proton motive force (delta(h(+))) has been proposed to be the signal for the membrane-associated arcb sensor kinase. this study provided evidence for a short arcb periplasmic bridge that contains a his47. the dispensability of this amino acid, the only amino acid with a pk in the physiological range, renders the de ... | 2000 | 10781568 |
| leucine aminopeptidases: the ubiquity of lap-n and the specificity of lap-a. | the wound-induced leucine aminopeptidase (ec 3.4.11.1) genes, lapa1 and lapa2, from tomato (lycopersicon esculentum mill.) were isolated and characterized. the genes were organized in a tandem array with approximately 6 kb separating their coding regions. quantitation of lapa mrna levels in conjunction with nuclear run-on experiments indicated that lapa genes were primarily under transcriptional control after wounding and infection with pseudomonas syringae pv. tomato. in contrast, actin genes w ... | 2000 | 10787049 |
| development of a highly sensitive nested-pcr procedure using a single closed tube for detection of erwinia amylovora in asymptomatic plant material. | a novel method, which involves a nested pcr in a single closed tube, was developed for the sensitive detection of erwinia amylovora in plant material. the external and internal primer pairs used had different annealing temperatures and directed the amplification of a specific dna fragment from plasmid pea29. the procedure involved two consecutive pcrs, the first of which was performed at a higher annealing temperature that allowed amplification only by the external primer pair. using pure cultur ... | 2000 | 10788384 |
| identification of the pgmg gene, encoding a bifunctional protein with phosphoglucomutase and phosphomannomutase activities, in the gellan gum-producing strain sphingomonas paucimobilis atcc 31461. | the pgmg gene of sphingomonas paucimobilis atcc 31461, the industrial gellan gum-producing strain, was cloned and sequenced. it encodes a 50,059-da polypeptide that has phosphoglucomutase (pgm) and phosphomannomutase (pmm) activities and is 37 to 59% identical to other bifunctional proteins with pgm and pmm activities from gram-negative species, including pseudomonas aeruginosa algc. purified pgmg protein showed a marked preference for glucose-1-phosphate (g1p); the catalytic efficiency was abou ... | 2000 | 10788412 |
| plant species and plant incubation conditions influence variability in epiphytic bacterial population size. | the influences of plant species and plant incubation conditions on the variability in bacterial population sizes among leaves were investigated in field and growth chamber studies. pseudomonas syringae strains tlp2 and cit7 were inoculated onto plants and population sizes were measured at intervals after inoculation. total bacterial population sizes were also assessed in field studies. levels of leaf-to-leaf variability in both p. syringae population size and bacterial community size differed si ... | 2000 | 10790512 |
| serological and molecular size characterization of flagellins of pseudomonas syringae pathovars and related bacteria | flagella from a total of 118 strains representing mostly pathovars of the phytopathogenic group pseudomonas syringae, but also p. chlororaphis, p. cichorii, p. corrugata, p. fluorescens, p. fuscovaginae, p. stutzeri, p. viridiflava, as well as related phytopathogenic genera (burkholderia cepacia and ralstonia solanacearum) were characterized by immuno-fluorescent staining, sds-page, and immunoblotting. eighty-six strains of the p. syringae group pathovars, p. cichorii and p. viridiflava were sho ... | 1999 | 10794141 |
| arabidopsis thaliana eds4 contributes to salicylic acid (sa)-dependent expression of defense responses: evidence for inhibition of jasmonic acid signaling by sa. | the arabidopsis enhanced disease susceptibility 4 (eds4) mutation causes enhanced susceptibility to infection by the bacterial pathogen pseudomonas syringae pv. maculicola es4326 (psm es4326). gene-for-gene resistance to bacteria carrying the avirulence gene avrrpt2 is not significantly affected by eds4. plants homozygous for eds4 exhibit reduced expression of the pathogenesis-related gene pr-1 after infection by psm es4326, weakened responses to treatment with the signal molecule salicylic acid ... | 2000 | 10796016 |
| decreased inositol 1,4,5-trisphosphate content in pathogen-challenged soybean cells. | phosphoinositide-specific phospholipase c (pi-plc) has been shown to be transiently activated when plant cells were treated with elicitors. we thus investigated the activity of pi-plc when soybean cells were infected with the bacterial pathogen pseudomonas syringae pv. glycinea, by measuring cellular cytosolic inositol 1,4,5-trisphosphate (ip3) levels. we observed that ip3 content decreased in both compatible and incompatible interactions. in vitro phosphatase activities were similar in both wat ... | 2000 | 10796022 |
| avrpto enhances growth and necrosis caused by pseudomonas syringae pv.tomato in tomato lines lacking either pto or prf. | avrpto was introduced into three tomato genotypes with two biotic agents to study its role in compatible interactions. avrpto enhanced the capacity of the pseudomonas syringae pv. tomato strain t1 to induce necrotic symptoms on tomato plants that lacked either pto or prf genes. the enhanced necrosis correlated with a small increase in bacterial growth. in planta expression of avrpto in isolation did not elicit necrosis in the absence of a functional prf gene. | 2000 | 10796023 |
| ethylene formation and phenotypic analysis of transgenic tobacco plants expressing a bacterial ethylene-forming enzyme. | a bacterial ethylene-forming enzyme (efe) catalyzes oxygenation of 2-oxoglutarate to produce ethylene and carbon dioxide in contrast to a plant enzyme which uses 1-aminocyclopropane-1-carboxylic acid as a substrate. we constructed several lines of transgenic tobacco plants which expressed an efe from pseudomonas syringae pv. phaseolicola pk2. the gene encoding a chimeric protein consisting of efe and beta-glucuronidase (gus) was introduced into the tobacco genome using a binary vector which dire ... | 2000 | 10805596 |
| response to xanthomonas campestris pv. vesicatoria in tomato involves regulation of ethylene receptor gene expression. | although ethylene regulates a wide range of defense-related genes, its role in plant defense varies greatly among different plant-microbe interactions. we compared ethylene's role in plant response to virulent and avirulent strains of xanthomonas campestris pv. vesicatoria in tomato (lycopersicon esculentum mill.). the ethylene-insensitive never ripe (nr) mutant displays increased tolerance to the virulent strain, while maintaining resistance to the avirulent strain. expression of the ethylene r ... | 2000 | 10806227 |
| octadecanoid-derived alteration of gene expression and the "oxylipin signature" in stressed barley leaves. implications for different signaling pathways. | stress-induced gene expression in barley (hordeum vulgare cv salome) leaves has been correlated with temporally changing levels of octadecanoids and jasmonates, quantified by means of gas chromatography/mass spectrometry-single ion monitoring. application of sorbitol-induced stress led to a low and transient rise of jasmonic acid (ja), its precursor 12-oxophytodienoic acid (opda), and the methyl esters jame and opdame, respectively, followed by a large increase in their levels. ja and jame peake ... | 2000 | 10806235 |
| differential regulation of plastidial and cytosolic isoforms of peptide methionine sulfoxide reductase in arabidopsis. | we report the characterization of two members of a gene family from arabidopsis that encode, respectively, cytosolic (cpmsr) and plastid-targeted (ppmsr) isoforms of the oxidative-stress-repair enzyme peptide methionine sulfoxide reductase. overexpression of these proteins in escherichia coli confirmed that each had pmsr enzyme activity with a synthetic substrate, n-acetyl-[(3)h]-methionine sulfoxide, or a biological substrate, alpha-1 proteinase inhibitor. the ppmsr was imported into intact chl ... | 2000 | 10806242 |
| cloning and expression of ntnd, encoding a novel nad(p)(+)-independent 4-nitrobenzyl alcohol dehydrogenase from pseudomonas sp. strain tw3. | pseudomonas sp. strain tw3 is able to metabolize 4-nitrotoluene to 4-nitrobenzoate and toluene to benzoate aerobically via a route analogous to the upper pathway of the tol plasmids. we report the cloning and characterization of a benzyl alcohol dehydrogenase gene (ntnd) which encodes the enzyme for the catabolism of 4-nitrobenzyl alcohol and benzyl alcohol to 4-nitrobenzaldehyde and benzaldehyde, respectively. the gene is located downstream of the previously reported ntn gene cluster. ntnd bear ... | 2000 | 10809692 |
| members of the arabidopsis hrt/rpp8 family of resistance genes confer resistance to both viral and oomycete pathogens. | turnip crinkle virus (tcv) inoculation onto tcv-resistant arabidopsis leads to a hypersensitive response (hr) controlled by the dominant gene hrt. hrt is a member of the class of resistance (r) genes that contain a leucine zipper, a nucleotide binding site, and leucine-rich repeats. the chromosomal position of hrt and its homology to resistance gene rpp8 and two rpp8 homologs indicate that unequal crossing over and gene conversion may have contributed to hrt evolution. rpp8 confers resistance to ... | 2000 | 10810142 |
| pti4 is induced by ethylene and salicylic acid, and its product is phosphorylated by the pto kinase. | the tomato pti4 gene encodes a transcription factor that was identified on the basis of its specific interaction with the product of the pto disease resistance gene in a yeast two-hybrid system. we show here that the pti4 protein specifically binds the gcc-box cis element, which is present in the promoter region of many pathogenesis-related (pr) genes. expression of the pti4 gene in tomato leaves was rapidly induced by ethylene and by infection with pseudomonas syringae pv tomato, and this induc ... | 2000 | 10810149 |
| pilus formation and protein secretion by the same machinery in escherichia coli. | the secreton (type ii secretion) and type iv pilus biogenesis branches of the general secretory pathway in gram-negative bacteria share many features that suggest a common evolutionary origin. five components of the secreton, the pseudopilins, are similar to subunits of type iv pili. here, we report that when the 15 genes encoding the pullulanase secreton of klebsiella oxytoca were expressed on a high copy number plasmid in escherichia coli, one pseudopilin, pulg, was assembled into pilus-like b ... | 2000 | 10811613 |
| thr38 and ser198 are pto autophosphorylation sites required for the avrpto-pto-mediated hypersensitive response. | the tomato pto kinase confers resistance to pseudomonas syringae pv. tomato expressing the avrpto protein. to elucidate the role of pto autophosphorylation in disease resistance, eight sites autophosphorylated by pto in vitro were identified by a combination of hplc purification of tryptic phosphopeptides, maldi-tof/ms analysis and edman degradation. mutational analysis of the autophosphorylation sites revealed that pto residues thr38 and ser198 are required for avrpto-pto- mediated elicitation ... | 2000 | 10811617 |
| a bacterial sensor of plant cell contact controls the transcriptional induction of ralstonia solanacearum pathogenicity genes. | the hrp genes of the plant pathogen ralstonia solanacearum are key pathogenicity determinants; they encode a type iii protein secretion machinery involved in the secretion of mediators of the bacterium-plant interaction. these hrp genes are under the genetic control of the hrpb regulatory gene, expression of which is induced when bacteria are co-cultivated with plant cell suspensions. in this study, we used hrp-gfp transcriptional fusions to demonstrate that the expression of the hrpb and type i ... | 2000 | 10811621 |
| eukaryotic fatty acylation drives plasma membrane targeting and enhances function of several type iii effector proteins from pseudomonas syringae. | bacterial pathogens of plants and animals utilize conserved type iii delivery systems to traffic effector proteins into host cells. plant innate immune systems evolved disease resistance (r) genes to recognize some type iii effectors, termed avirulence (avr) proteins. on disease-susceptible (r) plants, avr proteins can contribute to pathogen virulence. we demonstrate that several type iii effectors from pseudomonas syringae are targeted to the host plasma membrane and that efficient membrane ass ... | 2000 | 10830163 |
| a cluster of mutations disrupt the avirulence but not the virulence function of avrpto. | avrpto in pseudomonas syringae pv. tomato encodes an avirulence protein that triggers race-specific resistance in tomato plants carrying pto. the avrpto protein is secreted from p. syringae pv. tomato to plant cells through the type iii secretion pathway and activates race-specific resistance by a direct interaction with the pto protein. here we report that avrpto enhances the virulence of p. syringae pv. tomato in a strain-dependent manner in tomato plants lacking pto. to determine whether the ... | 2000 | 10830258 |
| prey range characterization, ribotyping, and diversity of soil and rhizosphere bdellovibrio spp. isolated on phytopathogenic bacteria. | thirty new bdellovibrio strains were isolated from an agricultural soil and from the rhizosphere of plants grown in that soil. using a combined molecular and culture-based approach, we found that the soil bdellovibrios included subpopulations of organisms that differed from rhizosphere bdellovibrios. thirteen soil and seven common bean rhizosphere bdellovibrio strains were isolated when pseudomonas corrugata was used as prey; seven and two soil strains were isolated when erwinia carotovora subsp ... | 2000 | 10831412 |
| methods for intense aeration, growth, storage, and replication of bacterial strains in microtiter plates. | miniaturized growth systems for heterogeneous culture collections are not only attractive in reducing demands for incubation space and medium but also in making the parallel handling of large numbers of strains more practicable. we report here on the optimization of oxygen transfer rates in deep-well microtiter plates and the development of a replication system allowing the simultaneous and reproducible sampling of 96 frozen glycerol stock cultures while the remaining culture volume remains froz ... | 2000 | 10831450 |
| detection of pseudomonas savastanoi pv. savastanoi in olive plants by enrichment and pcr. | the sequence of the gene iaal of pseudomonas savastanoi ew2009 was used to design primers for pcr amplification. the iaal-derived primers directed the amplification of a 454-bp fragment from genomic dna isolated from 70 strains of p. savastanoi, whereas genomic dna from 93 non-p. savastanoi isolates did not yield this amplified product. a previous bacterial enrichment in the semiselective liquid medium pvf-1 improved the pcr sensitivity level, allowing detection of 10 to 100 cfu/ml of plant extr ... | 2000 | 10831456 |
| surface-displayed viral antigens on salmonella carrier vaccine. | we have developed a recombinant live oral vaccine using the ice-nucleation protein (inp) from pseudomonas syringae to display viral antigens on the surface of salmonella spp. fusion proteins containing viral antigens were expressed in the oral vaccine strain, salmonella typhi ty21a. surface localization was verified by immunoblotting and fluorescence-activated cell sorting. the immunogenicity of surface-displayed viral antigens on the recombinant live vaccine strain was assessed in mice inoculat ... | 2000 | 10835603 |
| isolation of the gene for eilp, an elicitor-inducible lrr receptor-like protein, from tobacco by differential display. | we screened tobacco genes, which are differentially expressed in response to a fungal elicitor, and have isolated a gene which codes for a leucine-rich repeat (lrr) protein closely related to cf genes in tomato. the eilp (elicitor inducible lrr protein) gene encodes 95 kda protein, which consists of a putative membrane spanning region, 28 leucine-rich repeats and some n-linked glycosylation sites, and shows high homology to cf-2/cf-5 family genes. southern blot analysis revealed the presence of ... | 2000 | 10845459 |
| a resistance gene product of the nucleotide binding site -- leucine rich repeats class can form a complex with bacterial avirulence proteins in vivo. | resistance (r) genes in plants mediate gene-for-gene disease resistance. the ligand-receptor model, which explains the gene-for-gene specificity, predicts a physical interaction between an elicitor, which is directly or indirectly encoded by an avirulence (avr) gene in the pathogen, and the corresponding r gene product. the nucleotide binding site (nbs) - leucine rich repeats (lrr) class of r genes is the largest known class of r genes. here we report that an nbs-lrr r protein and its cognate av ... | 2000 | 10849351 |
| identification of sinorhizobium meliloti genes regulated during symbiosis. | rna fingerprinting by arbitrarily primed pcr was used to isolate sinorhizobium meliloti genes regulated during the symbiotic interaction with alfalfa (medicago sativa). sixteen partial cdnas were isolated whose corresponding genes were differentially expressed between symbiotic and free-living conditions. thirteen sequences corresponded to genes up-regulated during symbiosis, whereas three were instead repressed during establishment of the symbiotic interaction. seven cdnas corresponded to known ... | 2000 | 10850975 |
| characterization of the fructosyltransferase gene of actinomyces naeslundii wvu45. | oral actinomycetes produce fructosyltransferase (ftf) enzymes which convert sucrose into polymers of d-fructose, known as levans, and these polymers are thought to contribute to the persistence and virulence of the organisms. a gene encoding ftf was isolated from actinomyces naeslundii wvu45; the deduced amino acid sequence showed significant similarity to known levansucrases of gram-negative environmental isolates but was less similar to ftfs from gram-positive bacteria. a transcriptional start ... | 2000 | 10850978 |
| marinomonas mediterranea mmb-1 transposon mutagenesis: isolation of a multipotent polyphenol oxidase mutant. | marinomonas mediterranea is a melanogenic marine bacterium expressing a multifunctional polyphenol oxidase (ppo) able to oxidize substrates characteristic for laccases and tyrosinases, as well as produce a classical tyrosinase. a new and quick method has been developed for screening laccase activity in culture plates to detect mutants differentially affected in this ppo activity. transposon mutagenesis has been applied for the first time to m. mediterranea by using different minitransposons load ... | 2000 | 10850991 |
| phosphorelay as the sole physiological route of signal transmission by the arc two-component system of escherichia coli. | the arc two-component system, comprising a tripartite sensor kinase (arcb) and a response regulator (arca), modulates the expression of numerous genes involved in respiratory functions. in this study, the steps of phosphoryl group transfer from phosphorylated arcb to arca were examined in vivo by using single copies of wild-type and mutant arcb alleles. the results indicate that the signal transmission occurs solely by his-asp-his-asp phosphorelay. | 2000 | 10851007 |
| virulence of the phytopathogen pseudomonas syringae pv. maculicola is rpon dependent. | we cloned the rpon (ntra and glnf) gene encoding sigma(54) from the phytopathogen pseudomonas syringae pv. maculicola strain es4326. the p. syringae es4326 rpon gene complemented pseudomonas aeruginosa, escherichia coli, and klebsiella aerogenes rpon mutants for a variety of rpon mutant phenotypes, including the inability to utilize nitrate as sole nitrogen source. dna sequence analysis of the p. syringae es4326 rpon gene revealed that the deduced amino acid sequence was most similar (86% identi ... | 2000 | 10852883 |
| the alternative sigma factor rpon is required for hrp activity in pseudomonas syringae pv. maculicola and acts at the level of hrpl transcription. | beta-glucuronidase (uida) reporter gene fusions were constructed for the hrpz, hrpl, and hrps genes from the phytopathogen pseudomonas syringae pv. maculicola strain es4326. these reporters, as well as an avrrpt2-uida fusion, were used to measure transcriptional activity in es4326 and a es4326 rpon mutant. rpon was required for the expression of avrrpt2, hrpz, and hrpl in vitro in minimal media and in vivo when infiltrated into arabidopsis thaliana leaves. in contrast, the expression of hrps was ... | 2000 | 10852884 |
| cdna-aflp reveals a striking overlap in race-specific resistance and wound response gene expression profiles. | the tomato cf-9 gene confers resistance to races of the fungal pathogen cladosporium fulvum expressing the avr9 gene. cdna amplified fragment length polymorphism analysis was used to display transcripts whose expression is rapidly altered during the avr9- and cf-9-mediated defense response in tobacco cell cultures. diphenyleneiodonium was used to abolish the production of active oxygen species during gene induction. of 30,000 fragments inspected, 290 showed altered abundance, of which 263 were i ... | 2000 | 10852940 |
| regulation of brucella abortus catalase. | all aerobic organisms have mechanisms that protect against oxidative compounds. catalase, peroxidase, superoxide dismutase, glutathione, and thioredoxin are widely distributed in many taxa and constitute elements of a nearly ubiquitous antioxidant metabolic strategy. interestingly, the regulatory mechanisms that control these elements are rather different depending on the nature of the oxidative stress and the organism. catalase is well documented to play an important role in protecting cells fr ... | 2000 | 10858195 |
| relationship between the tsh autotransporter and pathogenicity of avian escherichia coli and localization and analysis of the tsh genetic region. | the temperature-sensitive hemagglutinin tsh is a member of the autotransporter group of proteins and was first identified in avian-pathogenic escherichia coli (apec) strain chi7122. the prevalence of tsh was investigated in 300 e. coli isolates of avian origin and characterized for virulence in a 1-day-old chick lethality test. results indicate that among the tsh-positive apec isolates, 90.6% belonged to the highest virulence class. experimental inoculation of chickens with chi7122 and an isogen ... | 2000 | 10858231 |
| ozone sensitivity in hybrid poplar correlates with insensitivity to both salicylic acid and jasmonic acid. the role of programmed cell death in lesion formation. | our earlier studies demonstrated that the ozone-sensitive hybrid poplar clone ne-388 displays an attenuated level of ozone-, wound-, and phytopathogen-induced defense gene expression. to determine if this reduced gene activation involves signal transduction pathways dependent on salicylic acid (sa) and/or jasmonic acid (ja), we compared the responses of ne-388 and an ozone-tolerant clone, ne-245, to these signal molecules. ja levels increased in both clones in response to ozone, but only minimal ... | 2000 | 10859179 |
| cytochrome p450-dependent metabolism of oxylipins in tomato. cloning and expression of allene oxide synthase and fatty acid hydroperoxide lyase. | allene oxide synthase (aos) and fatty acid hydroperoxide lyase (hpl) are plant-specific cytochrome p450s that commit fatty acid hydroperoxides to different branches of oxylipin metabolism. here we report the cloning and characterization of aos (leaos) and hpl (lehpl) cdnas from tomato (lycopersicon esculentum). functional expression of the cdnas in escherichia coli showed that leaos and lehpl encode enzymes that metabolize 13- but not 9-hydroperoxide derivatives of c(18) fatty acids. leaos was a ... | 2000 | 10859201 |
| gene genealogies and population variation in plants. | early in the development of plant evolutionary biology, genetic drift, fluctuations in population size, and isolation were identified as critical processes that affect the course of evolution in plant species. attempts to assess these processes in natural populations became possible only with the development of neutral genetic markers in the 1960s. more recently, the application of historically ordered neutral molecular variation (within the conceptual framework of coalescent theory) has allowed ... | 2000 | 10860966 |
| a regulatory rna (prrb rna) modulates expression of secondary metabolite genes in pseudomonas fluorescens f113. | the gacs-gaca two-component signal transduction system, which is highly conserved in gram-negative bacteria, is required for the production of exoenzymes and secondary metabolites in pseudomonas spp. screening of a pseudomonas fluorescens f113 gene bank led to the isolation of a previously undefined locus which could restore secondary metabolite production to both gacs and gaca mutants of f113. sequence analysis of this locus demonstrated that it did not contain any obvious pseudomonas protein-c ... | 2000 | 10869066 |
| a new two-component regulatory system involved in adhesion, autolysis, and extracellular proteolytic activity of staphylococcus aureus. | a transposition mutant of staphylococcus aureus was selected from the parent strain mt23142, a derivative of strain 8325. the site of transposition was near the 5' terminus of the gene arls. arls exhibits strong similarities with histidine protein kinases. sequence analysis suggested that arls forms an operon with upstream gene arlr. the predicted product of arlr is a member of the ompr-phob family of response regulators. the arls mutant formed a biofilm on a polystyrene surface unlike the paren ... | 2000 | 10869073 |
| lon protease influences antibiotic production and uv tolerance of pseudomonas fluorescens pf-5. | pseudomonas fluorescens pf-5 is a soil bacterium that suppresses plant pathogens due in part to its production of the antibiotic pyoluteorin. previous characterization of pf-5 revealed three global regulators, including the stationary-phase sigma factor sigma(s) and the two-component regulators gaca and gacs, that influence both antibiotic production and stress response. in this report, we describe the serine protease lon as a fourth global regulator influencing these phenotypes in pf-5. lon mut ... | 2000 | 10877760 |
| genes expressed in pseudomonas putida during colonization of a plant-pathogenic fungus. | in vivo expression technology (ivet) was employed to study colonization of phytophthora parasitica by a biological control bacterium, pseudomonas putida 06909, based on a new selection marker. the pyrb gene, which encodes aspartate transcarbamoylase, an enzyme used for pyrimidine biosynthesis, was cloned from p. putida 06909. a pyrb-disrupted mutant did not grow in pyrimidine-deficient media unless it was complemented with pyrbc' behind an active promoter. thirty clones obtained from p. putida 0 ... | 2000 | 10877766 |
| characterization of an atrazine-degrading pseudaminobacter sp. isolated from canadian and french agricultural soils. | atrazine, a herbicide widely used in corn production, is a frequently detected groundwater contaminant. fourteen bacterial strains able to use this herbicide as a sole source of nitrogen were isolated from soils obtained from two farms in canada and two farms in france. these strains were indistinguishable from each other based on repetitive extragenic palindromic pcr genomic fingerprinting performed with primers eric1r, eric2, and boxa1r. based on 16s rrna sequence analysis of one representativ ... | 2000 | 10877767 |
| sequence analysis and initial characterization of two isozymes of hydroxylaminobenzene mutase from pseudomonas pseudoalcaligenes js45. | pseudomonas pseudoalcaligenes js45 grows on nitrobenzene by a partially reductive pathway in which the intermediate hydroxylaminobenzene is enzymatically rearranged to 2-aminophenol by hydroxylaminobenzene mutase (hab mutase). the properties of the enzyme, the reaction mechanism, and the evolutionary origin of the gene(s) encoding the enzyme are unknown. in this study, two open reading frames (haba and habb), each encoding an hab mutase enzyme, were cloned from a p. pseudoalcaligenes js45 genomi ... | 2000 | 10877793 |
| the common nodulation genes of astragalus sinicus rhizobia are conserved despite chromosomal diversity. | the nodulation genes of mesorhizobium sp. (astragalus sinicus) strain 7653r were cloned by functional complementation of sinorhizobium meliloti nod mutants. the common nod genes, nodd, noda, and nodbc, were identified by heterologous hybridization and sequence analysis. the noda gene was found to be separated from nodbc by approximately 22 kb and was divergently transcribed. the 2. 0-kb noddbc region was amplified by pcr from 24 rhizobial strains nodulating a. sinicus, which represented differen ... | 2000 | 10877796 |
| cultivar-specific avirulence and virulence functions assigned to avrpphf in pseudomonas syringae pv. phaseolicola, the cause of bean halo-blight disease. | the avrpphf gene was cloned from pseudomonas syringae pathovar phaseolicola (pph:) races 5 and 7, based on its ability to confer avirulence towards bean cultivars carrying the r1 gene for halo-blight resistance, such as red mexican. avrpphf comprised two open reading frames, which were both required for function, and was located on a 154 kb plasmid (pav511) in pph: strain rw60 of pph:, lacking pav511, displayed a loss in virulence to a range of previously susceptible cultivars such as tendergree ... | 2000 | 10880434 |
| applications of differential-display reverse transcription-pcr to molecular pathogenesis and medical mycology. | the host-fungus interaction is characterized by changes in gene expression in both host and pathogen. differential-display reverse transcription pcr (ddrt-pcr) is a pcr-based method that allows extensive analysis of gene expression among several cell populations. several limitations and drawbacks to this procedure have now been addressed, including the large number of false-positive results and the difficulty in confirming differential expression. modifications that simplify the reaction time, a ... | 2000 | 10885984 |
| female reproductive tissues are the primary target of agrobacterium-mediated transformation by the arabidopsis floral-dip method. | the floral-dip method for agrobacterium-mediated transformation of arabidopsis allows efficient plant transformation without need for tissue culture. to facilitate use with other plant species, we investigated the mechanisms that underlie this method. in manual outcrossing experiments, application of agrobacterium tumefaciens to pollen donor plants did not produce any transformed progeny, whereas application of agrobacterium to pollen recipient plants yielded transformants at a rate of 0.48%. ag ... | 2000 | 10889238 |
| enhancement of induced disease resistance by simultaneous activation of salicylate- and jasmonate-dependent defense pathways in arabidopsis thaliana. | the plant-signaling molecules salicylic acid (sa) and jasmonic acid (ja) play an important role in induced disease resistance pathways. cross-talk between sa- and ja-dependent pathways can result in inhibition of ja-mediated defense responses. we investigated possible antagonistic interactions between the sa-dependent systemic acquired resistance (sar) pathway, which is induced upon pathogen infection, and the ja-dependent induced systemic resistance (isr) pathway, which is triggered by nonpatho ... | 2000 | 10890883 |
| the bacterial enhancer-dependent sigma(54) (sigma(n)) transcription factor. | 2000 | 10894718 |