Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
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| methods for detecting acylated homoserine lactones produced by gram-negative bacteria and their application in studies of ahl-production kinetics. | in the process of evaluating the role of acylated homoserine lactones (ahls) in food-spoiling gram-negative bacteria, we have combined a range of bacterial ahl monitor systems to determine the ahl-profile and the kinetics of ahl-production. ahl production from 148 strains of enterobacteriaceae isolated from foods was tested using escherichia coli psb403 (luxr), agrobacterium tumefaciens a136 (trar) and both induction and inhibition of chromobacterium violaceum cv026 (cvir). all strains except on ... | 2001 | 11240047 |
| sira orthologs affect both motility and virulence. | the sira gene of salmonella enterica serovar typhimurium encodes a two-component response regulator of the fixj family that has a positive regulatory influence on the expression of type iii secretion genes involved with epithelial cell invasion and the elicitation of bovine gastroenteritis. sira orthologs in pseudomonas, vibrio, and erwinia control the expression of distinct virulence genes in these genera, but an evolutionarily conserved target of sira regulation has never been identified. in t ... | 2001 | 11244064 |
| an inner membrane platform in the type ii secretion machinery of gram-negative bacteria. | the type ii secretion machinery allows most gram-negative bacteria to deliver virulence factors into their surroundings. we report that in erwinia chrysanthemi, gspe (the putative ntpase), gspf, gspl and gspm constitute a complex in the inner membrane that is presumably used as a platform for assembling other parts of the secretion machinery. the gspe-gspf-gspl-gspm complex was demonstrated by two methods: (i) co-immunoprecipitation of gspe-gspf-gspl with antibodies raised against either gspe or ... | 2001 | 11266368 |
| the effect of polysialylation on the immunogenicity and antigenicity of asparaginase: implication in its pharmacokinetics. | erwinia carotovora l-asparaginase was conjugated via the epsilon-amino groups of its lysine residues with colominic acid (ca) (polysialic acid) of average molecular mass of 10 kda by reductive amination in the presence of nacnbh3. polysialylation using 50-, 100- and 250-fold molar excess ca relative to the enzyme led to an increasing proportion of the enzyme's in-amino groups (5.8, 7.6 and 11.3%, respectively) being conjugated to ca. polysialylated and native (intact) asparaginase were used to i ... | 2001 | 11292557 |
| mapping stress-induced changes in autoinducer ai-2 production in chemostat-cultivated escherichia coli k-12. | numerous gram-negative bacteria employ a cell-to-cell signaling mechanism, termed quorum sensing, for controlling gene expression in response to population density. recently, this phenomenon has been discovered in escherichia coli, and while pathogenic e. coli utilize quorum sensing to regulate pathogenesis (i.e., expression of virulence genes), the role of quorum sensing in nonpathogenic e. coli is less clear, and in particular, there is no information regarding the role of quorum sensing durin ... | 2001 | 11292813 |
| study of the role of antimicrobial glucosinolate-derived isothiocyanates in resistance of arabidopsis to microbial pathogens. | crude aqueous extracts from arabidopsis leaves were subjected to chromatographic separations, after which the different fractions were monitored for antimicrobial activity using the fungus neurospora crassa as a test organism. two major fractions were obtained that appeared to have the same abundance in leaves from untreated plants versus leaves from plants challenge inoculated with the fungus alternaria brassicicola. one of both major antimicrobial fractions was purified to homogeneity and iden ... | 2001 | 11299350 |
| effects of the two-component system comprising gaca and gacs of erwinia carotovora subsp. carotovora on the production of global regulatory rsmb rna, extracellular enzymes, and harpinecc. | posttranscriptional regulation mediated by the regulator of secondary metabolites (rsm) rsma-rsmb pair is the most important factor in the expression of genes for extracellular enzymes and harpinecc in erwinia carotovora subsp. carotovora. rsma is a small rna-binding protein, which acts by lowering the half-life of a mrna species. rsmb specifies an untranslated regulatory rna and neutralizes the rsma effect. it has been speculated that gaca-gacs, members of a two-component system, may affect gen ... | 2001 | 11310739 |
| optimization of fermentation conditions for preparation of polygalacturonic acid transeliminase by erwinia carotovora ifo3830. | this paper is concerned with optimization of the fermentation conditions for preparation of alkaline pectin lyase (poly-galacturonic acid trans-eliminase, pate) by erwinia carotovora ifo3830 (e.c.ifo3830). the orthogonal matrix method was adopted as the experimental design method for media. the effects of media composition on the growth rate of e.c.ifo3830 are in the order of pectin > kh(2)po(4)/na(2)hpo(4) > mgso(4) > (nh(4))(2)so(4) > glucose > l-glutamate sodium, and those on pate activity ar ... | 2001 | 11312709 |
| molecular characterization of an endopolygalacturonase from fusarium oxysporum expressed during early stages of infection. | the tomato vascular wilt pathogen fusarium oxysporum f. sp. lycopersici produces an array of pectinolytic enzymes that may contribute to penetration and colonization of the host plant. here we report the isolation of pg5, encoding a novel extracellular endopolygalacturonase (endopg) that is highly conserved among different formae speciales of f. oxysporum. the putative mature pg5 product has a calculated molecular mass of 35 kda and a pi of 8.3 and is more closely related to endopgs from other f ... | 2001 | 11319099 |
| osmoregulated periplasmic glucan synthesis is required for erwinia chrysanthemi pathogenicity. | erwinia chrysanthemi is a phytopathogenic enterobacterium causing soft rot disease in a wide range of plants. osmoregulated periplasmic glucans (opgs) are intrinsic components of the gram-negative bacterial envelope. we cloned the opggh operon of e. chrysanthemi, encoding proteins involved in the glucose backbone synthesis of opgs, by complementation of the homologous locus mdogh of escherichia coli. opgg and opgh show a high level of similarity with mdog and mdoh, respectively, and mutations in ... | 2001 | 11325942 |
| the pdz domain of outc and the n-terminal region of outd determine the secretion specificity of the type ii out pathway of erwinia chrysanthemi. | the plant pathogens erwinia chrysanthemi and erwinia carotovora secrete multiple exoproteins by a type ii pathway, the out system. secretion in erwinia is species-specific: exoproteins of one species cannot be secreted by the other. we analysed the role of two components of the out system, the bitopic inner membrane protein outc and the secretin outd, in the specific recognition of secreted proteins. we demonstrated that the pdz domain of outc determines its secretion specificity towards certain ... | 2001 | 11327762 |
| physico-chemical analysis of lipid a fractions of lipopolysaccharide from erwinia carotovora in relation to bioactivity. | highly purified bisphosphoryl, monophosphoryl and dephosphoryl lipids a from erwinia carotovora with different acylation patterns were characterized physico-chemically. applying matrix assisted laser desorption/ionization mass spectrometry, the purity of the lipid a fractions was determined, and from monolayer measurements the molecular space requirement was estimated. fourier transform infrared spectroscopy allowed the elucidation of the gel to liquid crystalline phase transition of the acyl ch ... | 2001 | 11342157 |
| mycobacterium bovis bcg reca deletion mutant shows increased susceptibility to dna-damaging agents but wild-type survival in a mouse infection model. | pathogenic microorganisms possess antioxidant defense mechanisms for protection from reactive oxygen metabolites which are generated during the respiratory burst of phagocytic cells. these defense mechanisms include enzymes such as catalase, which detoxifies reactive oxygen species, and dna repair systems, which repair damage resulting from oxidative stress. to (i) determine the relative importance of the dna repair system when oxidative stress is encountered by the mycobacterium tuberculosis co ... | 2001 | 11349014 |
| quorum sensing controls the synthesis of virulence factors by modulating rsma gene expression in erwinia carotovora subsp. carotovora. | the plant-pathogenic bacterium erwinia carotovora subsp. carotovora (ecc) causes disease mainly by means of a number of extracellular plant cell wall-degrading enzymes (pcwdes), also referred to as virulence factors. the production of pcwdes is coordinately activated by the diffusible signal molecule n-acyl-homoserine lactone (hsl) in a population density-dependent manner ("quorum sensing"). expi is the enzyme responsible for the synthesis of hsl. the rsm system negatively regulates the producti ... | 2001 | 11361339 |
| the luxm homologue vanm from vibrio anguillarum directs the synthesis of n-(3-hydroxyhexanoyl)homoserine lactone and n-hexanoylhomoserine lactone. | vibrio anguillarum, which causes terminal hemorrhagic septicemia in fish, was previously shown to possess a luxri-type quorum-sensing system (vanri) and to produce n-(3-oxodecanoyl)homoserine lactone (3-oxo-c10-hsl). however, a vani null mutant still activated n-acylhomoserine lactone (ahl) biosensors, indicating the presence of an additional quorum-sensing circuit in v. anguillarum. in this study, we have characterized this second system. using high-pressure liquid chromatography in conjunction ... | 2001 | 11371516 |
| [processes of plant colonization by methylobacterium strains and some bacterial properties ]. | the pink-pigmented facultative methylotrophic bacteria (ppfmb) of the genus methylobacterium are indespensible inhabitants of the plant phyllosphere. using maize zea mays as a model, the ways of plant colonization by ppfmb and some properties of the latter that might be beneficial to plants were studied. a marked strain, methylobacterium mesophilicum apr-8 (pulb113), was generated to facilitate the detection of the methylotrophic bacteria inoculated into the soil or applied to the maize leaves. ... | 2001 | 11386061 |
| [adsorbed receptors for erwinia carotovor subsp. carotovora macromolecular bacteriocins]. | study of nature of receptors for macromolecular bacteriocins erwinia carotovora subsp. carotovora has shown that lipopolysaccharide (lps) of cell membrane is an attaching structure for them. it has been established that enzymic treatment of lps preparation with its further deproteinization by phenol is necessary for isolation of biologically active lipopolysaccharide. the process of absorption by lps has been studied quantitatively and it has been shown that it is a low-efficient receptor as com ... | 2001 | 11392768 |
| exchange of xcp (gsp) secretion machineries between pseudomonas aeruginosa and pseudomonas alcaligenes: species specificity unrelated to substrate recognition. | pseudomonas aeruginosa and pseudomonas alcaligenes are gram-negative bacteria that secrete proteins using the type ii or general secretory pathway, which requires at least 12 xcp gene products (xcpa and xcpp to -z). despite strong conservation of this secretion pathway, gram-negative bacteria usually cannot secrete exoproteins from other species. based on results obtained with erwinia, it has been proposed that the xcpp and/or xcpq homologs determine this secretion specificity (m. linderberg, g. ... | 2001 | 11208795 |
| betawrap: successful prediction of parallel beta -helices from primary sequence reveals an association with many microbial pathogens. | the amino acid sequence rules that specify beta-sheet structure in proteins remain obscure. a subclass of beta-sheet proteins, parallel beta-helices, represent a processive folding of the chain into an elongated topologically simpler fold than globular beta-sheets. in this paper, we present a computational approach that predicts the right-handed parallel beta-helix supersecondary structural motif in primary amino acid sequences by using beta-strand interactions learned from non-beta-helix struct ... | 2001 | 11752429 |
| homology of escherichia coli r773 arsa, arsb, and arsc genes in arsenic-resistant bacteria isolated from raw sewage and arsenic-enriched creek waters. | the occurrence and diversity of the escherichia coli r773 ars operon were investigated among arsenic-resistant enteric and nonenteric bacteria isolated from raw sewage and arsenic-enriched creek waters. selected isolates from each creek location were screened for ars genes by colony hybridization and pcr. the occurrence of arsa, arsb, and arsc determined by low-stringency colony hybridization (31 to 53% estimated mismatch) was 81, 87, and 86%, respectively, for 84 bacteria isolated on arsenate- ... | 2002 | 11772637 |
| [in vitro self assembly of supermolecular structures after spontaneous disassembly of carotovoricins]. | the self-assembly of supramolecular structures (empty sheaths and polysheaths of the macromolecular erwinia carotovora bacteriocins) was studied by electron microscopy in the course of 1- to 2-year incubation of phage particles at 4 degrees c. this study showed that the empty sheaths and polysheaths of the bacteriocins of eight e. carotovora strains spontaneously assemble at the self-assembly centers (or crystallization centers), which have a diameter of 26-65 nm and contain a dense proteinaceou ... | 2002 | 12244715 |
| heca, a member of a class of adhesins produced by diverse pathogenic bacteria, contributes to the attachment, aggregation, epidermal cell killing, and virulence phenotypes of erwinia chrysanthemi ec16 on nicotiana clevelandii seedlings. | erwinia chrysanthemi is representative of a broad class of bacterial pathogens that are capable of inducing necrosis in plants. the e. chrysanthemi ec16 heca gene predicts a 3,850-aa member of the bordetella pertussis filamentous hemagglutinin family of adhesins. a hecatn7 mutant was reduced in virulence on nicotiana clevelandii seedlings after inoculation without wounding. epifluorescence and confocal laser-scanning microscopy observations of heca and wild-type cells expressing the green fluore ... | 2002 | 12271135 |
| inhibition of hydrolytic enzyme activities and plant pathogen growth by invertase inhibitors. | the invertase inhibitory protein isolated from cyphomandra betacea sendt and solanum tuberosum inhibited the invertase activity from different species, genera and even plant family. furthermore, proteinaceous inhibitors are not invertase specific; fungal, bacterial and higher plant enzymes including polygalacturonase, pectinase, pectin lyase, alpha-l-arabinofuranosidase and beta-glucosidase are also shown to be inhibited. both inhibitors exhibited an in vitro antibacterial action against phytopa ... | 2002 | 12365459 |
| in vitro efficacy of plant volatiles for inhibiting the growth of fruit and vegetable decay microorganisms. | the effects of acetaldehyde, benzaldehyde, cinnamaldehyde, ethanol, benzyl alcohol, nerolidol, 2-nonanone, beta-ionone, and ethyl formate vapors on the growth of rhizopus stolonifer, penicillium digitatum, colletotrichum musae, erwinia carotovora, and pseudomonas aeruginosa on agar medium were evaluated. the aldehydes were found to be the strongest growth inhibitors and the most lethal to the fungal spores and mycelia and bacterial cells. the average minimum inhibitory concentrations (mics) of a ... | 2002 | 12381119 |
| characterization of serracin p, a phage-tail-like bacteriocin, and its activity against erwinia amylovora, the fire blight pathogen. | serratia plymithicum j7 culture supernatant displayed activity against many pathogenic strains of erwinia amylovora, the causal agent of the most serious bacterial disease of apple and pear trees, fire blight, and against klebsiella pneumoniae, serratia liquefaciens, serratia marcescens, and pseudomonas fluorescens. this activity increased significantly upon induction with mitomycin c. a phage-tail-like bacteriocin, named serracin p, was purified from an induced culture supernatant of s. plymith ... | 2002 | 12406768 |
| the regulation of virulence in phytopathogenic erwinia species: quorum sensing, antibiotics and ecological considerations. | erwinia carotovora is a gram-negative bacterial phytopathogen that causes soft-rot disease and potato blackleg. the organism is environmentally widespread and exhibits an opportunistic plant pathogenesis. the ability to secrete multiple plant cell wall-degrading enzymes is a key virulence trait and exoenzyme production is responsive to multiple environmental and physiological cues. one important cue is the cell population density of the pathogen. cell density is monitored via an acylated homoser ... | 2002 | 12448721 |
| relatedness of chromosomal and plasmid dnas of erwinia pyrifoliae and erwinia amylovora. | the plant pathogen erwinia pyrifoliae has been classified as a separate species from erwinia amylovora based in part on differences in molecular properties. in this study, these and other molecular properties were examined for e. pyrifoliae and for additional strains of e. amylovora, including strains from brambles (rubus spp.). the nucleotide composition of the internal transcribed spacer (its) region was determined for six of the seven 16s-23s rrna operons detected in these species with a 16s ... | 2002 | 12450843 |
| coexistence of multiple proteobacterial endosymbionts in the gills of the wood-boring bivalve lyrodus pedicellatus (bivalvia: teredinidae). | wood-boring bivalves of the family teredinidae (commonly called shipworms) are known to harbor dense populations of gram-negative bacteria within specialized cells (bacteriocytes) in their gills. these symbionts are thought to provide enzymes, e.g., cellulase and dinitrogenase, which assist the host in utilizing wood as a primary food source. a cellulolytic, dinitrogen-fixing bacterium, teredinibacter turnerae, has been isolated from the gill tissues of numerous teredinid bivalves and has been p ... | 2002 | 12450854 |
| spatio-temporal expression of patatin-like lipid acyl hydrolases and accumulation of jasmonates in elicitor-treated tobacco leaves are not affected by endogenous levels of salicylic acid. | we have previously isolated three tobacco genes (ntpat) encoding patatin-like proteins, getting rapidly induced during the hypersensitive response (hr) to tobacco mosaic virus, in advance to jasmonate accumulation. ntpat enzymes are lipid acyl hydrolases that display high phospholipase a2 (pla2) activity and may mobilize fatty acid precursors of oxylipins. here, we performed a detailed study of ntpat gene regulation under various biotic and abiotic stresses. pla2 activity was poorly induced in r ... | 2002 | 12472690 |
| [type iii secretion system in se9r can recognize and secret harpin in erwinia amylovora]. | bacterial pathogens of both animals and plants use type iii secretion machines to secret virulence proteins. the signal that leads to tye type iii secretion is encoded as stem loop structure in the messenger rna. harpin, produced by erwinia anylovora is secreted via type iii secretion. erwinia carotovora se9r and erwinia amylovora belong to the same genus and they use type iii secretion machines to secret virulence proteins. we used pcr to amplify hrpn from pcpp430 which harbors hrpn gene cluste ... | 2002 | 12557554 |
| regulatory rna as mediator in gaca/rsma-dependent global control of exoproduct formation in pseudomonas fluorescens cha0. | in pseudomonas fluorescens cha0, an antagonist of root-pathogenic fungi, the gacs/gaca two-component system tightly controls the expression of antifungal secondary metabolites and exoenzymes at a posttranscriptional level, involving the rna-binding protein and global regulator of secondary metabolism rsma. this protein was purified from p. fluorescens, and rna bound to it was converted to cdna, which served as a probe to isolate the corresponding chromosomal locus, rsmz. this gene encoded a regu ... | 2002 | 11807065 |
| nonenzymatic turnover of an erwinia carotovora quorum-sensing signaling molecule. | the production of virulence factors and carbapenem antibiotic in the phytopathogen erwinia carotovora is under the control of quorum sensing. the quorum-sensing signaling molecule, n-(3-oxohexanoyl)-l-homoserine lactone (ohhl), accumulates in log-phase culture supernatants of e. carotovora but diminishes in concentration during the stationary phase. in this study, we show that the diminution in ohhl was not due to sequestration of the ligand by the cells, although some partitioning did occur. ra ... | 2002 | 11807077 |
| quorum-sensing signals and quorum-sensing genes in burkholderia vietnamiensis. | acyl-homoserine lactone (acyl-hsl) quorum sensing is common to many proteobacteria including a clinical isolate of burkholderia cepacia. the b. cepacia isolate produces low levels of octanoyl-hsl. we have examined an environmental isolate of burkholderia vietnamiensis. this isolate produced several acyl-hsls. the most abundant species was decanoyl-hsl. decanoyl-hsl in b. vietnamiensis cultures reached concentrations in excess of 20 microm. we isolated a b. vietnamiensis dna fragment containing a ... | 2002 | 11807080 |
| efficient insertion mutagenesis strategy for bacterial genomes involving electroporation of in vitro-assembled dna transposition complexes of bacteriophage mu. | an efficient insertion mutagenesis strategy for bacterial genomes based on the phage mu dna transposition reaction was developed. incubation of mua transposase protein with artificial mini-mu transposon dna in the absence of divalent cations in vitro resulted in stable but inactive mu dna transposition complexes, or transpososomes. following delivery into bacterial cells by electroporation, the complexes were activated for dna transposition chemistry after encountering divalent metal ions within ... | 2002 | 11823210 |
| genotyping of bacteria belonging to the former erwinia genus by pcr-rflp analysis of a reca gene fragment. | genotypic characterization, based on the analysis of restriction fragment length polymorphism of the reca gene fragment pcr product (reca pcr-rflp), was performed on members of the former erwinia genus. pcr primers deduced from published reca gene sequences of erwinia carotovora allowed the amplification of an approximately 730 bp dna fragment from each of the 19 erwinia species tested. amplified reca fragments were compared using rflp analysis with four endonucleases (alui, hinfi, tasi and tru1 ... | 2002 | 11832521 |
| manipulation of strawberry fruit softening by antisense expression of a pectate lyase gene. | strawberry (fragaria x ananassa, duch., cv chandler) is a soft fruit with a short postharvest life, mainly due to a rapid lost of firm texture. to control the strawberry fruit softening, we obtained transgenic plants that incorporate an antisense sequence of a strawberry pectate lyase gene under the control of the 35s promoter. forty-one independent transgenic lines (apel lines) were obtained, propagated in the greenhouse for agronomical analysis, and compared with control plants, non-transforme ... | 2002 | 11842178 |
| effects of t4 lysozyme release from transgenic potato roots on bacterial rhizosphere communities are negligible relative to natural factors. | rhizosphere bacterial communities of two transgenic potato lines which produce t4 lysozyme for protection against bacterial infections were analyzed in comparison to communities of wild-type plants and transgenic controls not harboring the lysozyme gene. rhizosphere samples were taken from young, flowering, and senescent plants at two field sites in three consecutive years. the communities were characterized in a polyphasic approach. cultivation-dependent methods included heterotrophic plate cou ... | 2002 | 11872484 |
| regulation of the expression of prtw::gusa fusions in erwinia carotovora subsp. carotovora. | erwinia carotovora subsp. carotovora, a gram-negative phytopathogenic bacterium, secretes an extracellular metalloprotease, prtw. previous results demonstrated that protease activity is necessary for the normal progression of disease symptoms caused by this bacterium. the present study revealed that the prtw gene constitutes an independent transcriptional unit. it is demonstrated that introduction of the prtw(+) plasmid in trans into the prtw(-) mutant restores the protease activity in this stra ... | 2002 | 11882719 |
| altered lignin structure and resistance to pathogens in spi 2-expressing tobacco plants. | the physiological role of the norway spruce [ picea abies (l.) karst.] spi 2 gene, encoding a defense-related cationic peroxidase was examined in transgenic tobacco (nicotiana tabacum l.). expression of spi 2, under control of the 35s promoter, in tobacco plants resulted in higher total peroxidase activities. the phenotype of the spi 2-transformed lines was normal. the spi 2-transformed lines displayed lignin levels similar to levels in the control line, but with some alteration in lignin histoc ... | 2002 | 11882939 |
| [temperate bacteriophage zf40 of erwinia carotovora: phage particle structure and dna restriction analysis]. | structural organization of the temperate bacteriophage zf40 of erwinia carotovora was studied. phage zf40 proved to be a typical member of the myoviridae family (morphotype a1). phage particles consist of an isometric head 58.3 nm in diameter and a contractile 86.3-nm-long tail with a complex basal plate and short tail fibers (31.5 nm). phage tail sheath, a truncated cone in shape, is characterized by specific packaging of structural subunits. the zf40 phage genome is 45.8 kb in size, as determi ... | 2002 | 11910811 |
| [study of erwinia carotovora phage resistance with the use of temperate bacteriophage zf40]. | the causes of the unique phage resistance of the pectinolytic phytopathogenic strains of erwinia carotovora were studied with the use of temperate bacteriophage zf40. it was shown that, in these bacteria, the bacteriophage-cell interaction can be substantially blocked at the adsorption level. an adequate indicator for studying the temperate bacteriophages of erwinias was developed on the basis of mutants resistant to macromolecular bacteriocins. various restriction-modification systems, which in ... | 2002 | 11910812 |
| the extracellular transport signal of the vibrio cholerae endochitinase (chia) is a structural motif located between amino acids 75 and 555. | chia, an 88-kda endochitinase encoded by the chia gene of the gram-negative enteropathogen vibrio cholerae, is secreted via the eps-encoded main terminal branch of the general secretory pathway (gsp), a mechanism which also transports cholera toxin. to localize the extracellular transport signal of chia that initiates transport of the protein through the gsp, a chimera comprised of chia fused at the n terminus with the maltose-binding protein (male) of escherichia coli and fused at the c terminu ... | 2002 | 11914354 |
| application of amplified fragment length polymorphism fingerprinting for taxonomy and identification of the soft rot bacteria erwinia carotovora and erwinia chrysanthemi. | the soft rot bacteria erwinia carotovora and erwinia chrysanthemi are important pathogens of potato and other crops. however, the taxonomy of these pathogens, particularly at subspecies level, is unclear. an investigation using amplified fragment length polymorphism (aflp) fingerprinting was undertaken to determine the taxonomic relationships within this group based on their genetic relatedness. following cluster analysis on the similarity matrices derived from the aflp gels, four clusters (clus ... | 2002 | 11916661 |
| the ybit gene of erwinia chrysanthemi codes for a putative abc transporter and is involved in competitiveness against endophytic bacteria during infection. | we investigated the role in bacterial infection of a putative abc transporter, designated ybit, of erwinia chrysanthemi ac4150. the deduced sequence of this gene showed amino acid sequence similarity with other putative abc transporters of gram-negative bacteria, such as escherichia coli and pseudomonas aeruginosa, as well as structural similarity with proteins of streptomyces spp. involved in resistance to macrolide antibiotics. the gene contiguous to ybit, designated as pab (putative antibioti ... | 2002 | 11916677 |
| identification of quorum-quenching n-acyl homoserine lactonases from bacillus species. | a range of gram-negative bacterial species use n-acyl homoserine lactone (ahl) molecules as quorum-sensing signals to regulate different biological functions, including production of virulence factors. ahl is also known as an autoinducer. an autoinducer inactivation gene, aiia, coding for an ahl lactonase, was cloned from a bacterial isolate, bacillus sp. strain 240b1. here we report identification of more than 20 bacterial isolates capable of enzymatic inactivation of ahls from different source ... | 2002 | 11916693 |
| a putative three-dimensional targeting motif of polygalacturonase (peha), a protein secreted through the type ii (gsp) pathway in erwinia carotovora. | intramolecular information specifying protein secretion through the type ii (gsp) pathway of gram-negative bacteria was investigated. two regions of the polygalacturonase (peha) of erwinia carotovora containing residues proposed to be included in a targeting motif were located, one close to the c-terminus between residues 342 and 369 and another between residues 84 and 135 in the large central loops. the regions were required together to promote secretion. further residues in the middle of the p ... | 2002 | 11929517 |
| genetic control of quorum-sensing signal turnover in agrobacterium tumefaciens. | a signal turnover system is an essential component of many genetic regulatory mechanisms. the best-known example is the ubiquitin-dependent protein degradation system that exists in many organisms. we found that agrobacterium tumefaciens adopts a unique signal turnover system to control exiting from a quorum-sensing mode. a. tumefaciens regulates ti plasmid conjugal transfer by a quorum-sensing signal, n-3-oxo-octanoyl homoserine lactone (3oc8hsl), also known as agrobacterium autoinducer. by usi ... | 2002 | 11930013 |
| [study of population dissociation of collection strains of erwinia carotovora]. | unusual dissociants of erwinia carotovora subsp. atroseptica (eat) population that emerge with high frequency (18-94%) during long-term storage of cultures were found. the dissociants (poe-phenotype) differ from parental forms by slow growth and long development of the colour of colonies on emb agar though they are not lac-mutants. more than 60% of poe-mutants of strain eat 39a are characterized by 8- and 150-fold decrease of stability to erythromycin and oleandomicin, correspondingly. they are ... | 2002 | 11944340 |
| rhodospirillum centenum utilizes separate motor and switch components to control lateral and polar flagellum rotation. | rhodospirillum centenum is a purple photosynthetic bacterium that is capable of differentiating from vibrioid swimming cells that contain a single polar flagellum into rod-shaped swarming cells that have a polar flagellum plus numerous lateral flagella. microscopic studies have demonstrated that the polar flagellum is constitutively present and that the lateral flagella are found only when the cells are grown on solidified or viscous medium. in this study, we demonstrated that r. centenum contai ... | 2002 | 11948156 |
| ocatin. a novel tuber storage protein from the andean tuber crop oca with antibacterial and antifungal activities. | the most abundant soluble tuber protein from the andean crop oca (oxalis tuberosa mol.), named ocatin, has been purified and characterized. ocatin accounts for 40% to 60% of the total soluble oca tuber proteins, has an apparent molecular mass of 18 kd and an isoelectric point of 4.8. this protein appears to be found only in tubers and is accumulated only within the cells of the pith and peridermis layers (peel) of the tuber as it develops. ocatin inhibits the growth of several phytopathogenic ba ... | 2002 | 11950978 |
| genomic analysis of the f3031 brazilian purpuric fever clone of haemophilus influenzae biogroup aegyptius by pcr-based subtractive hybridization. | pcr-based subtractive genome hybridization produced clones harboring inserts present in brazilian purpuric fever (bpf) prototype strain f3031 but absent in noninvasive haemophilus influenzae biogroup aegyptius isolate f1947. some of these inserts have no matches in the genbank database, while others are similar to genes encoding either known or hypothetical proteins. one insert represents a 2.3-kb locus with similarity to a thermotoga maritima hypothetical protein, while another is part of a 7.6 ... | 2002 | 11953414 |
| response of endophytic bacterial communities in potato plants to infection with erwinia carotovora subsp. atroseptica. | the term endophyte refers to interior colonization of plants by microorganisms that do not have pathogenic effects on their hosts, and various endophytes have been found to play important roles in plant vitality. in this study, cultivation-independent terminal restriction fragment length polymorphism analysis of 16s ribosomal dna directly amplified from plant tissue dna was used in combination with molecular characterization of isolates to examine the influence of plant stress, achieved by infec ... | 2002 | 11976096 |
| high-density microarray of small-subunit ribosomal dna probes. | ribosomal dna sequence analysis, originally conceived as a way to provide a universal phylogeny for life forms, has proven useful in many areas of biological research. some of the most promising applications of this approach are presently limited by the rate at which sequences can be analyzed. as a step toward overcoming this limitation, we have investigated the use of photolithography chip technology to perform sequence analyses on amplified small-subunit rrna genes. the genechip (affymetrix co ... | 2002 | 11976131 |
| advancing the quorum in pseudomonas aeruginosa: mvat and the regulation of n-acylhomoserine lactone production and virulence gene expression. | pseudomonas aeruginosa regulates the production of many exoproteins and secondary metabolites via a hierarchical quorum-sensing cascade through lasr and rhlr and their cognate signal molecules n-(3-oxododecanoyl)-l-homoserine lactone (3o-c12-hsl) and n-(butanoyl)-l-homoserine lactone (c4-hsl). in this study, we found that transcription of the quorum sensing-regulated genes leca (coding for pa-il lectin), lasb (coding for elastase), and rpos appeared to be growth phase dependent and their express ... | 2002 | 11976285 |
| pehn, a polygalacturonase homologue with a low hydrolase activity, is coregulated with the other erwinia chrysanthemi polygalacturonases. | erwinia chrysanthemi 3937 secretes an arsenal of pectinolytic enzymes, including at least eight endo-pectate lyases encoded by pel genes, which play a major role in the soft-rot disease caused by this bacterium on various plants. e. chrysanthemi also produces some hydrolases that cleave pectin. three adjacent hydrolase genes, pehv, pehw, and pehx, encoding exo-poly-alpha-d-galacturonosidases, have been characterized. these enzymes liberate digalacturonides from the nonreducing end of pectin. we ... | 2002 | 11976295 |
| sample sequencing of a selected region of the genome of erwinia carotovora subsp. atroseptica reveals candidate phytopathogenicity genes and allows comparison with escherichia coli. | genome sequencing is making a profound impact on microbiology. currently, however, only one plant pathogen genome sequence is publicly available and no genome-sequencing project has been initiated for any species of the genus erwinia, which includes several important plant pathogens. this paper describes a targeted sample sequencing approach to study the genome of erwinia carotovora subsp. atroseptica (eca), a major soft-rot pathogen of potato. a large insert dna (approx. 115 kb) library of eca ... | 2002 | 11988510 |
| temperature-dependent production of carotovoricin er and pectin lyase in phytopathogenic erwinia carotovora subsp. carotovora er. | the production of pectin lyase (pnl) and carotovoricin (ctv), as well as cell lysis in the plant-pathogenic bacterium erwinia carotovora subsp. carotovora er are induced by mitomycin c. here, pnl and ctv production and cell lysis were found to be temperature-dependent. the optimal temperature for pnl production was 30 degrees c. however, the optimal temperature for both ctv production and cell lysis was 23 degrees c, at which pnl production was reduced to 47% of the maximum. these data suggest t ... | 2002 | 11999425 |
| detection of bacterial infection of agave plants by laser-induced fluorescence. | greenhouse-grown plants of agave tequilana weber var. azul were inoculated with erwinia carotovora, the causal agent of stem soft rot. we investigated the laser-induced fluorescence (lif) of agave plants to determine whether lif can be used as a noninvasive sensing tool for pathological studies. the lif technique was also investigated as a means of detecting the effect of the polyamine biosynthesis inhibitor beta-hydroxyethylhydrazine as a bactericide against the pathogenic bacterium erwinia car ... | 2002 | 12009165 |
| identification of a quorum-sensing signal molecule in the facultative intracellular pathogen brucella melitensis. | brucella melitensis is a gram-negative alpha2-proteobacterium responsible for abortion in goats and for malta fever in humans. this facultative intracellular pathogen invades and survives within both professional and nonprofessional phagocytes. a dichloromethane extract of spent culture supernatant from b. melitensis induces bioluminescence in an escherichia coli acyl-homoserine lactone (acyl-hsl) biosensor strain based upon the activity of the lasr protein of pseudomonas aeruginosa. hplc fracti ... | 2002 | 12010991 |
| natural variability in the arabidopsis response to infection with erwinia carotovora subsp. carotovora. | the natural variation in the response of arabidopsis thaliana (l.) heynh. to erwinia carotovora subsp. carotovora has been studied in seven ecotypes and two mutants. the susceptibility of all the plant types was investigated by (i) macroscopic symptoms, (ii) fluorescence microscopy using green fluorescent protein (gfp) and (iii) bacterial growth in planta. although all the plants were susceptible to the bacterium, there was no correlation in the degree of infection as ascertained by the three me ... | 2002 | 12029469 |
| identification of two quorum-sensing systems in sinorhizobium meliloti. | sinorhizobium meliloti is a free-living soil bacterium which is capable of establishing a symbiotic relationship with the alfalfa plant (medicago sativa). this symbiosis involves a network of bacterium-host signaling, as well as the potential for bacterium-bacterium communication, such as quorum sensing. in this study, we characterized the production of n-acyl homoserine lactones (ahls) by two commonly used s. meliloti strains, ak631 and rm1021. we found that ak631 produces at least nine differe ... | 2002 | 12057940 |
| differential regulation of multiple proteins of escherichia coli and salmonella enterica serovar typhimurium by the transcriptional regulator slya. | slya is a transcriptional regulator of escherichia coli, salmonella enterica, and other bacteria belonging to the enterobacteriaceae: the slya protein has been shown to be involved in the virulence of s. enterica serovar typhimurium, but its role in e. coli is unclear. in this study, we employed the proteome technology to analyze the slya regulons of enteroinvasive e. coli (eiec) and salmonella serovar typhimurium. in both cases, comparative analysis of the two-dimensional protein maps of a wild ... | 2002 | 12057949 |
| interaction of ozone and negative air ions to control micro-organisms. | the aims of this study were to investigate the effect of ozone and/or negative air ions (nai) on the viability of bacteria. | 2002 | 12067383 |
| potentiation of developmentally regulated plant defense response by atwrky18, a pathogen-induced arabidopsis transcription factor. | atwrky18 is a pathogen- and salicylic acid-induced arabidopsis transcription factor containing the plant-specific wrky zinc finger dna-binding motif. in the present study, we have transformed arabidopsis plants with atwrky18 under control of the cauliflower mosaic virus 35s promoter. surprisingly, transgenic plants expressing high levels of atwrky18 were stunted in growth. when expressed at moderate levels, atwrky18 potentiated developmentally regulated defense responses in transgenic plants wit ... | 2002 | 12068113 |
| [isolation and genetic study of erwinia mutants devoid of common components of the phosphoenolpyruvate-dependent phosphotransferase system]. | mutants of bacteria belonging the genus erwinia (erwinia chrysanthemi and erwinia carotovora) with pleiotropic disturbances in the utilization of many substrates were obtained through chemical and transposon mutagenesis. genetic studies revealed that these mutants had defective ptsi or ptsh genes responsible for the synthesis of common components of the phosphoenolpyruvate-dependent phosphotransferase system, enzyme i and the hpr protein, respectively. the ptsi+ allele in both erwinia species wa ... | 2002 | 12068545 |
| cloning and relational analysis of 15 novel fungal endoglucanases from family 12 glycosyl hydrolase. | cellulases belong to the large family of glycosyl hydrolases (ghs) and are produced by a variety of bacteria and fungi. these extracellular enzymes act as endoglucanases (egs), cellobiohydrolases or beta-glucosidases. in this paper, we describe molecular screening for egs from the gh family 12. using three homologous sequence boxes deduced from five previously known members of the family, we analysed 22 cellulase-producing fungal strains obtained from a diverse area of the fungal kingdom. polyme ... | 2002 | 12073090 |
| secondary (gamma-proteobacteria) endosymbionts infect the primary (beta-proteobacteria) endosymbionts of mealybugs multiple times and coevolve with their hosts. | mealybugs (hemiptera, coccoidea, pseudococcidae) are plant sap-sucking insects that have within their body cavities specialized cells containing prokaryotic primary endosymbionts (p-endosymbionts). the p-endosymbionts have the unusual property of containing within their cytoplasm prokaryotic secondary endosymbionts (s-endosymbionts) [c. d. von dohlen, s. kohler, s. t. alsop, and w. r. mcmanus, nature (london) 412:433-436, 2001]. four-kilobase fragments containing 16s-23s ribosomal dna (rdna) wer ... | 2002 | 12088994 |
| altering plant-microbe interaction through artificially manipulating bacterial quorum sensing. | many bacteria regulate diverse physiological processes in concert with their population size. bacterial cell-to-cell communication utilizes small diffusible signal molecules, which the bacteria both produce and perceive. the bacteria couple gene expression to cell density by eliciting a response only when the signalling molecules reach a critical threshold (a point at which the population is said to be 'quorate'). the population as a whole is thus able to modify its behaviour as a single unit. a ... | 2002 | 12096736 |
| rsma and the quorum-sensing signal, n-[3-oxohexanoyl]-l-homoserine lactone, control the levels of rsmb rna in erwinia carotovora subsp. carotovora by affecting its stability. | rsma (for regulator of secondary metabolism), rsmc, and rsmb rna, the components of a posttranscriptional regulatory system, control extracellular protein production and pathogenicity in erwinia carotovora subsp. carotovora. rsma, an rna binding protein, acts as a negative regulator by promoting message decay. rsmb rna, on the other hand, acts as a positive regulator by neutralizing the effect of rsma. rsmc modulates the levels of rsma and rsmb rna by positively regulating rsma and negatively co ... | 2002 | 12107125 |
| diverse bacteria are pathogens of caenorhabditis elegans. | practically and ethically attractive as model systems, invertebrate organisms are increasingly recognized as relevant for the study of bacterial pathogenesis. we show here that the nematode caenorhabditis elegans is susceptible to a surprisingly broad range of bacteria and may constitute a useful model for the study of both pathogens and symbionts. | 2002 | 12117988 |
| the crystal structure of anthranilate phosphoribosyltransferase from the enterobacterium pectobacterium carotovorum. | the structure of anthranilate phosphoribosyltransferase from the enterobacterium pectobacterium carotovorum has been solved at 2.4 a in complex with mn(2+)-pyrophosphate, and at 1.9 a without ligands. the enzyme structure has a novel phosphoribosyltransferase (prt) fold and displays close homology to the structures of pyrimidine nucleoside phosphorylases. the enzyme is a homodimer with a monomer of 345 residues. each monomer consists of two subdomains, alpha and alpha/beta, which form a cleft co ... | 2002 | 12123839 |
| [defective lysogeny in erwinia carotovora]. | the electron microscopic study of several erwinia carotovora strains showed that the sos-induced cells of this pectolytic phytopathogenic bacterium produce particular phage parts (tails, heads, and baseplates) but do not assemble them into fully functional phage particles. e. carotovora cells produced several times greater amounts of phage tails in response to induction by mitomycin c than in response to induction by nalidixic acid. the tails were 128-192 nm in length and 13-21 nm in diameter. p ... | 2002 | 12138758 |
| identification, characterization, and regulation of a cluster of genes involved in carbapenem biosynthesis in photorhabdus luminescens. | the luminescent entomopathogenic bacterium photorhabdus luminescens produces several yet-uncharacterized broad-spectrum antibiotics. we report the identification and characterization of a cluster of eight genes (named cpma to cpmh) responsible for the production of a carbapenem-like antibiotic in strain tt01 of p. luminescens. the cpm cluster differs in several crucial aspects from other car operons. the level of cpm mrna peaks during exponential phase and is regulated by a rap/hor homolog ident ... | 2002 | 12147472 |
| genes encoding the n-acyl homoserine lactone-degrading enzyme are widespread in many subspecies of bacillus thuringiensis. | gram-negative bacteria can communicate with each other by n-acyl homoserine lactones (ahls), which are quorum-sensing autoinducers. recently, the aiia gene (encoding an enzyme catalyzing the degradation of ahl) has been cloned from bacillus sp. strain 240b1. during investigations in the course of the ongoing bacillus thuringiensis subsp. morrisoni genome project, an aiia homologue gene in the genome sequence was found. these results led to consideration of the possibility of the widespread exist ... | 2002 | 12147491 |
| lasr, a transcriptional activator of pseudomonas aeruginosa virulence genes, functions as a multimer. | the pseudomonas aeruginosa lasr protein functions in concert with n-3-oxo-dodecanoyl-l-homoserine lactone (3o-c(12)-hsl) to coordinate the expression of target genes, including many genes that encode virulence factors, with cell density. we used a lexa-based protein interaction assay to demonstrate that lasr forms multimers only when 3o-c(12)-hsl is present. a series of lasr molecules containing internal deletions or substitutions in single, conserved amino acid residues indicated that the n-ter ... | 2002 | 12169617 |
| inhibition of the plastidic atp/adp transporter protein primes potato tubers for augmented elicitation of defense responses and enhances their resistance against erwinia carotovora. | tubers of transgenic potato (solanum tuberosum) plants with decreased activity of the plastidic atp/adp transporter aatp1 display reduced levels of starch, modified tuber morphology, and altered concentrations of primary metabolites. here, we demonstrate that the spontaneous production of hydrogen peroxide, the endogenous content of salicylic acid, and the levels of mrnas of various defense-related genes are similar in tuber discs of wild-type and aatp1(st) antisense plants. however, upon challe ... | 2002 | 12177473 |
| constitutive expression of hrap gene in transgenic tobacco plant enhances resistance against virulent bacterial pathogens by induction of a hypersensitive response. | hypersensitive response-assisting protein (hrap) has been previously reported as an amphipathic plant protein isolated from sweet pepper that intensifies the harpin(pss)-mediated hypersensitive response (hr). the hrap gene has no appreciable similarity to any other known sequences, and its activity can be rapidly induced by incompatible pathogen infection. to assess the function of the hrap gene in plant disease resistance, the camv 35s promoter was used to express sweet pepper hrap in transgeni ... | 2002 | 12182333 |
| [method for studying horizontal transfer of plasmids in erwinia carotovora]. | a simple method to determine frequency characteristics of the horizontal transfer of antibiotic resistance by transconjugative plasmids of various incompatibility groups into erwinia carotovora strains has been developed. the proposed method for selection of e. carotovora transconjugates provides for the use of selective medium with pectin and corresponding antibiotic, which permits carrying out reliable counterselection of the donor (escherichia, salmonella). the proposed method helped to study ... | 2002 | 12190030 |
| regulatory circuitry of the csra/csrb and bara/uvry systems of escherichia coli. | the global regulator csra (carbon storage regulator) is an rna binding protein that coordinates central carbon metabolism, activates flagellum biosynthesis and motility, and represses biofilm formation in escherichia coli. csra activity is antagonized by the untranslated rna csrb, to which it binds and forms a globular ribonucleoprotein complex. csra indirectly activates csrb transcription, in an apparent autoregulatory mechanism. in the present study, we elucidate the intermediate regulatory ci ... | 2002 | 12193630 |
| the crystal structure of the quorum sensing protein trar bound to its autoinducer and target dna. | the quorum sensing system allows bacteria to sense their cell density and initiate an altered pattern of gene expression after a sufficient quorum of cells has accumulated. in agrobacterium tumefaciens, quorum sensing controls conjugal transfer of the tumour- inducing plasmid, responsible for plant crown gall disease. the core components of this system are the transcriptional regulator trar and its inducing ligand n-(3-oxo-octanoyl)-l-homoserine lactone. this complex binds dna and activates gene ... | 2002 | 12198141 |
| biodegradation of the polyketide toxin cercosporin. | cercosporin is a non-host-specific polyketide toxin produced by many species of plant pathogens belonging to the genus cercospora. this red-pigmented, light-activated toxin is an important pathogenicity determinant for cercospora species. in this study, we screened 244 bacterial isolates representing 12 different genera for the ability to degrade cercosporin. cercosporin degradation was determined by screening for the presence of cleared zones surrounding colonies on cercosporin-containing cultu ... | 2002 | 12200262 |
| the fibronectin type 3-like repeat from the clostridium thermocellum cellobiohydrolase cbha promotes hydrolysis of cellulose by modifying its surface. | fibronectin type 3 homology domains (fn3) as found in the cellobiohydrolase cbha of clostridium thermocellum are common among bacterial extracellular glycohydrolases. the function of these domains is not clear. cbha is modular and composed of an n-terminal family iv carbohydrate-binding domain (cbdiv), an immunoglobulin-like domain, a family 9 glycosyl hydrolase catalytic domain (gh9), two fn3-like domains (fn3(1,2)), a family iii carbohydrate-binding domain (cbdiii), and a dockerin domain. effi ... | 2002 | 12200278 |
| predicted structure and phyletic distribution of the rna-binding protein hfq. | hfq, a bacterial rna-binding protein, was recently shown to contain the sm1 motif, a characteristic of sm and lsm proteins that function in rna processing events in archaea and eukaryotes. in this report, comparative structural modeling was used to predict a three-dimensional structure of the hfq core sequence. the predicted structure aligns with most major features of the methanobacterium thermoautotrophicum lsm protein structure. conserved residues in hfq are positioned at the same structural ... | 2002 | 12202750 |
| whole-genome comparative analysis of three phytopathogenic xylella fastidiosa strains. | xylella fastidiosa (xf) causes wilt disease in plants and is responsible for major economic and crop losses globally. owing to the public importance of this phytopathogen we embarked on a comparative analysis of the complete genome of xf pv citrus and the partial genomes of two recently sequenced strains of this species: xf pv almond and xf pv oleander, which cause leaf scorch in almond and oleander plants, respectively. we report a reanalysis of the previously sequenced xf 9a5c (cvc, citrus) st ... | 2002 | 12205291 |
| signal transduction and regulatory mechanisms involved in control of the sigma(s) (rpos) subunit of rna polymerase. | the sigma(s) (rpos) subunit of rna polymerase is the master regulator of the general stress response in escherichia coli and related bacteria. while rapidly growing cells contain very little sigma(s), exposure to many different stress conditions results in rapid and strong sigma(s) induction. consequently, transcription of numerous sigma(s)-dependent genes is activated, many of which encode gene products with stress-protective functions. multiple signal integration in the control of the cellular ... | 2002 | 12208995 |
| n-acylhomoserine lactones undergo lactonolysis in a ph-, temperature-, and acyl chain length-dependent manner during growth of yersinia pseudotuberculosis and pseudomonas aeruginosa. | in gram-negative bacterial pathogens, such as pseudomonas aeruginosa and yersinia pseudotuberculosis, cell-to-cell communication via the n-acylhomoserine lactone (ahl) signal molecules is involved in the cell population density-dependent control of genes associated with virulence. this phenomenon, termed quorum sensing, relies upon the accumulation of ahls to a threshold concentration at which target structural genes are activated. by using biosensors capable of detecting a range of ahls we obse ... | 2002 | 12228292 |
| multidrug pump inhibitors uncover remarkable activity of plant antimicrobials. | plant antimicrobials are not used as systemic antibiotics at present. the main reason for this is their low level of activity, especially against gram-negative bacteria. the reported mic is often in the range of 100 to 1,000 micro g/ml, orders of magnitude higher than those of common broad-spectrum antibiotics from bacteria or fungi. major plant pathogens belong to the gram-negative bacteria, which makes the low level of activity of plant antimicrobials against this group of microorganisms puzzl ... | 2002 | 12234835 |
| regulation of erwinia carotovora hrpl(ecc) (sigma-l(ecc)), which encodes an extracytoplasmic function subfamily of sigma factor required for expression of the hrp regulon. | in erwinia carotovora subsp. carotovora (ecc) strain 71 (ecc71), hrpl(ecc), an alternate sigma factor of the extracytoplasmic function subfamily, plays a central role in the expression of the hrp (hypersensitive reaction and pathogenicity) regulon. we document here that sigma-54 (rpon) is required for full expression of hrpl(ecc) and that hrps, in conjunction with sigma-54, activates hrpl(ecc) transcription. we also made the novel observation that integration host factor is required for the acti ... | 2002 | 12236604 |
| dissimilatory fe(iii) and mn(iv) reduction by shewanella putrefaciens requires fere, a homolog of the pule (gspe) type ii protein secretion gene. | shewanella putrefaciens strain 200 respires anaerobically on a wide range of compounds as the sole terminal electron acceptor, including ferric iron [fe(iii)] and manganese oxide [mn(iv)]. previous studies demonstrated that a 23.3-kb s. putrefaciens wild-type dna fragment conferred metal reduction capability to a set of respiratory mutants with impaired fe(iii) and mn(iv) reduction activities (t. dichristina and e. delong, j. bacteriol. 176:1468-1474, 1994). in the present study, the smallest co ... | 2002 | 11741854 |
| microbial biodiversity: approaches to experimental design and hypothesis testing in primary scientific literature from 1975 to 1999. | research interest in microbial biodiversity over the past 25 years has increased markedly as microbiologists have become interested in the significance of biodiversity for ecological processes and as the industrial, medical, and agricultural applications of this diversity have evolved. one major challenge for studies of microbial habitats is how to account for the diversity of extremely large and heterogeneous populations with samples that represent only a very small fraction of these population ... | 2002 | 12456784 |
| identification of regulators of hrp/hop genes of erwinia carotovora ssp. carotovora and characterization of hrpl(ecc) (sigmal(eccm)), an alternative sigma factor. | summary erwinia carotovora ssp. carotovora (ecc) possesses hrpn(ecc)[hrp = gene for hypersensitive reaction (hr) and pathogenicity], the structural gene for harpin(ecc), the inducer of the hr-like response and genes for the type iii secretion system. in ecc, rsma, an rna-binding protein responsible for the accelerated decay of rna species, tightly controls the expression of the hrp regulon. we document here that ecc strain 71 possesses several presumed hrp regulators: hrpx(ecc), hrpy(ecc), hrps( ... | 2002 | 20569343 |
| bacterial autoinduction: looking outside the cell for new metabolic engineering targets. | recent evidence has demonstrated that cell-to-cell signaling is a fundamental activity carried out by numerous microorganisms. a number of specialized processes are reported to be regulated by density-dependent signaling molecules including antibiotic production, bioluminescence, biofilm formation, genetic competence, sporulation, swarming motility and virulence. however, a more centralized role for quorum sensing is emerging where quorum signaling pathways overlap with stress and starvation cir ... | 2002 | 12537600 |
| mob psychology. | 2002 | 11807045 | |
| constitutive expression of a single antimicrobial peptide can restore wild-type resistance to infection in immunodeficient drosophila mutants. | one of the characteristics of the host defense of insects is the rapid synthesis of a variety of potent antibacterial and antifungal peptides. to date, seven types of inducible antimicrobial peptides (amps) have been characterized in drosophila. the importance of these peptides in host defense is supported by the observation that flies deficient for the toll or immune deficiency (imd) pathway, which affects amp gene expression, are extremely susceptible to microbial infection. here we have devel ... | 2002 | 11854512 |
| a bypass of sucrose synthase leads to low internal oxygen and impaired metabolic performance in growing potato tubers. | plants possess two alternative biochemical pathways for sucrose (suc) degradation. one involves hydrolysis by invertase followed by phosphorylation via hexokinase and fructokinase, and the other route-which is unique to plants-involves a udp-dependent cleavage of suc that is catalyzed by suc synthase (susy). in the present work, we tested directly whether a bypass of the endogenous susy route by ectopic overexpression of invertase or suc phosphorylase affects internal oxygen levels in growing tu ... | 2003 | 12913161 |
| ethylene response factor1 integrates signals from ethylene and jasmonate pathways in plant defense. | cross-talk between ethylene and jasmonate signaling pathways determines the activation of a set of defense responses against pathogens and herbivores. however, the molecular mechanisms that underlie this cross-talk are poorly understood. here, we show that ethylene and jasmonate pathways converge in the transcriptional activation of ethylene response factor1 (erf1), which encodes a transcription factor that regulates the expression of pathogen response genes that prevent disease progression. the ... | 2003 | 12509529 |
| chemical communication among bacteria. | cell-cell communication in bacteria is accomplished through the exchange of chemical signal molecules called autoinducers. this process, called quorum sensing, allows bacteria to monitor their environment for the presence of other bacteria and to respond to fluctuations in the number and/or species present by altering particular behaviors. most quorum-sensing systems are species- or group-specific, which presumably prevents confusion in mixed-species environments. however, some quorum-sensing ci ... | 2003 | 12949263 |
| tmrdb (tmrna database). | maintained at the university of texas health science center at tyler, texas, the tmrna database (tmrdb) is accessible at the url http://psyche.uthct.edu/dbs/tmrdb/tmrdb.html with mirror sites located at auburn university, auburn, alabama (http://www.ag.auburn.edu/mirror/tmrdb/) and the bioinformatics research center, aarhus, denmark (http://www.bioinf.au.dk/tmrdb/). the tmrdb collects and distributes information relevant to the study of tmrna. in trans-translation, this molecule combines propert ... | 2003 | 12520048 |
| molecular basis of bacterial outer membrane permeability revisited. | gram-negative bacteria characteristically are surrounded by an additional membrane layer, the outer membrane. although outer membrane components often play important roles in the interaction of symbiotic or pathogenic bacteria with their host organisms, the major role of this membrane must usually be to serve as a permeability barrier to prevent the entry of noxious compounds and at the same time to allow the influx of nutrient molecules. this review summarizes the development in the field since ... | 2003 | 14665678 |
| interspecies communication in bacteria. | until recently, bacteria were considered to live rather asocial, reclusive lives. new research shows that, in fact, bacteria have elaborate chemical signaling systems that enable them to communicate within and between species. one signal, termed ai-2, appears to be universal and facilitates interspecies communication. many processes, including virulence factor production, biofilm formation, and motility, are controlled by ai-2. strategies that interfere with communication in bacteria are being e ... | 2003 | 14597753 |