Publications

attachment of escherichia coli o157:h7 to the surfaces and internal structures of apples as detected by confocal scanning laser microscopy.	confocal scanning laser microscopy (cslm) was used to demonstrate the attachment of escherichia coli o157:h7 transformed with a plasmid encoding for green fluorescent protein (gfp) to the surface and within the internal structures of nonwaxed red delicious cv. apples. apples at 2 or 25 degrees c were inoculated with an e. coli o157:h7 cell suspension at 2 or 25 degrees c. the effect of a negative temperature differential (cold inoculum, warm apple), a positive differential (warm inoculum, cold a ...	2000	11055910
identification of ciprofloxacin-resistant campylobacter jejuni by use of a fluorogenic pcr assay.	fluoroquinolones are one class of antimicrobial agents commonly used to treat severe campylobacter jejuni infection. c. jejuni strains resistant to high levels of the fluoroquinolone ciprofloxacin (mic >/=16 microg/ml) have been predominantly characterized with a c-->t transition in codon 86 of gyra. the gyra gene encodes one subunit of dna gyrase, which is a primary target for fluoroquinolone antibiotics. this study establishes a rapid pcr-based taqman method for identifying ciprofloxacin-resis ...	2000	11060054
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
inhibition of fungal and bacterial plant pathogens by synthetic peptides: in vitro growth inhibition, interaction between peptides and inhibition of disease progression.	four synthetic cationic peptides, pep6, pep7, pep11 and pep20, were tested alone and in combinations for their antimicrobial activities against economically important plant pathogenic fungi (phytophthora infestans and alternaria solani) and bacteria (erwinia carotovora subsp. carotovora and e. carotovora subsp. atroseptica). in in vitro studies, p. infestans and a. solani were inhibited by all four peptides, while e. carotovora subsp. carotovora and e. carotovora subsp. atroseptica were inhibite ...	2000	10939256
a competitive pcr-based method for the detection and quantification of erwinia carotovora subsp. atroseptica on potato tubers.	a pcr-based method was developed for the simultaneous detection and quantification of the potato pathogen erwinia carotovora subsp. atroseptica (eca) on potato tubers. the method incorporates a competitor pcr template cloned into escherichia coli in vector pgem-t (e. coli 4r l/l). predetermined numbers of e. coli 4r were added to potato peel extract, either pre-inoculated with eca or from naturally contaminated tubers, and eca numbers estimated by comparing the ratio of products generated from e ...	2000	10792657
an evolutionarily conserved rna stem-loop functions as a sensor that directs feedback regulation of rnase e gene expression.	rnase e is a key regulatory enzyme that controls the principal pathway for mrna degradation in escherichia coli. the cellular concentration of this endonuclease is governed by a feedback mechanism in which rnase e tightly regulates its own synthesis. autoregulation is mediated in cis by the 361-nucleotide 5' untranslated region (utr) of rne (rnase e) mrna. here we report the determination of the secondary structure of the rne 5' utr by phylogenetic comparison and chemical alkylation, together wi ...	2000	10817759
distribution of aldoxime dehydratase in microorganisms.	the distribution of phenylacetaldoxime-degrading and pyridine-3-aldoxime-degrading ability was examined with intact cells of 975 microorganisms, including 45 genera of bacteria, 11 genera of actinomyces, 22 genera of yeasts, and 37 genera of fungi, by monitoring the decrease of the aldoximes by high-pressure liquid chromatography. the abilities were found to be widely distributed in bacteria, actinomyces, fungi, and some yeasts: 98 and 107 strains degraded phenylacetaldoxime and pyridine-3-aldox ...	2000	10831401
quorum-sensing signal binding results in dimerization of trar and its release from membranes into the cytoplasm.	promoter binding by trar and luxr, the activators of two bacterial quorum-sensing systems, requires their cognate acyl-homoserine lactone (acyl-hsl) signals, but the role the signal plays in activating these transcription factors is not known. soluble active trar, when purified from cells grown with the acyl-hsl, contained bound signal and was solely in dimer form. however, genetic and cross-linking studies showed that trar is almost exclusively in monomer form in cells grown without signal. add ...	2000	11013223
new virulence-activated and virulence-repressed genes identified by systematic gene inactivation and generation of transcriptional fusions in bordetella pertussis.	an in silico scan of the partially completed genome sequence of bordetella pertussis and analyses of transcriptional fusions generated with a new integrational vector were used to identify new potential virulence genes. the genes encoding a putative siderophore receptor, adhesins, and an autotransporter protein appeared to be regulated in a manner similar to bordetella virulence genes by the global virulence regulator bvgas. in contrast, the gene encoding a putative intimin-like protein appeared ...	2000	11004193
acyl-homoserine lactone quorum sensing in gram-negative bacteria: a signaling mechanism involved in associations with higher organisms.	recent advances in studies of bacterial gene expression have brought the realization that cell-to-cell communication and community behavior are critical for successful interactions with higher organisms. species-specific cell-to-cell communication is involved in successful pathogenic or symbiotic interactions of a variety of bacteria with plant and animal hosts. one type of cell-cell signaling is acyl-homoserine lactone quorum sensing in gram-negative bacteria. this type of quorum sensing repres ...	2000	10922036
an escherichia coli reference collection group b2- and uropathogen-associated polymorphism in the rpos-muts region of the e. coli chromosome.	chromosomal dnas of enterohemorrhagic, uropathogenic, and laboratory attenuated escherichia coli strains differ in the rpos-muts region. many uropathogens lack a deletion and an insertion characteristic of enterohemorrhagic strains. at the same chromosomal position, they harbor a 2.1-kb insertion of unknown origin with a base composition suggestive of horizontal gene transfer. unlike virulence determinants associated with urinary tract infection and/or neonatal meningitis (pap or prs, sfa, kps, ...	2000	11029456
antimicrobial effect of rosemary extracts.	a rosemary extract commercially exploited (oxy'less) as an antioxidant of lipids in foods was dissolved in ethanol (100 mg/ml), and the solution was tested against foodborne microorganisms. for gram-positive bacteria, the mic of the ethanolic solution was 1% for leuconostoc mesenteroides, 0.5% for listeria monocytogenes, 0.5% for staphylococcus aureus, 0.13% for streptococcus mutans, and 0.06% for bacillus cereus. it slowed the growth of penicillium roquefortii and botrytis cinerea. up to 1% of ...	2000	11041135
induced expression of sarcotoxin ia enhanced host resistance against both bacterial and fungal pathogens in transgenic tobacco.	we demonstrate here that induced expression of sarcotoxin ia, a bactericidal peptide from sarcophaga peregrina, enhanced the resistance of transgenic tobacco plants to both bacterial and fungal pathogens. the peptide was produced with a modified pr1a promoter, which is further activated by salicylic acid treatment and necrotic lesion formation by pathogen infection. host resistance to infection of bacteria erwinia carotovora subsp. carotovora and pseudomonas syringae pv. tabaci was shown to be d ...	2000	10939257
bacteria in the leaf ecosystem with emphasis on pseudomonas syringae-a pathogen, ice nucleus, and epiphyte.	the extremely large number of leaves produced by terrestrial and aquatic plants provide habitats for colonization by a diversity of microorganisms. this review focuses on the bacterial component of leaf microbial communities, with emphasis on pseudomonas syringae-a species that participates in leaf ecosystems as a pathogen, ice nucleus, and epiphyte. among the diversity of bacteria that colonize leaves, none has received wider attention than p. syringae, as it gained notoriety for being the firs ...	2000	10974129
keys to symbiotic harmony.		2000	11004160
a potato gene encoding a wrky-like transcription factor is induced in interactions with erwinia carotovora subsp. atroseptica and phytophthora infestans and is coregulated with class i endochitinase expression.	a potato gene encoding a putative wrky protein was isolated from a cdna library enriched by suppression subtractive hybridization for sequences upregulated 1 h postinoculation with erwinia carotovora subsp. atroseptica. the cdna encodes a putative polypeptide of 172 amino acids, containing a single wrky domain with a zinc finger motif and preceded by a potential nuclear localization site. st-wrky1 was strongly upregulated in compatible, but only weakly in incompatible, interactions with phytopht ...	2000	11043470
the pseudomonas aeruginosa lectins pa-il and pa-iil are controlled by quorum sensing and by rpos.	in pseudomonas aeruginosa, many exoproduct virulence determinants are regulated via a hierarchical quorum-sensing cascade involving the transcriptional regulators lasr and rhlr and their cognate activators, n-(3-oxododecanoyl)-l-homoserine lactone (3o-c12-hsl) and n-butanoyl-l-homoserine lactone (c4-hsl). in this paper, we demonstrate that the cytotoxic lectins pa-il and pa-iil are regulated via quorum sensing. using immunoblot analysis, the production of both lectins was found to be directly de ...	2000	11053384
analysis of the role of reca in phenotypic switching of pseudomonas tolaasii.	switching between the pathogenic smooth (1116s) and nonpathogenic rough (1116r) forms of pseudomonas tolaasii occurs due to the reversible duplication of a 661-bp element within the phen locus. disruption of the chromosomal reca locus of 1116s and 1116r produced strains 1116sreca and 1116rreca, respectively, which showed typical loss of uv resistance. switching from the smooth to the rough form was virtually eliminated in the 1116sreca strain, whereas the extent of switching from the rough to th ...	2000	11053404
identification and characterization of yersinia enterocolitica genes induced during systemic infection.	yersinia enterocolitica is one of three pathogenic yersinia species that share a tropism for lymphoid tissues. however, infection of an immunocompromised host is likely to result in a systemic infection, which is often fatal. little is known about the bacterial proteins needed to establish such an infection. the genes that encode these virulence factors are likely to be active only during systemic infection. a library of random cat fusions was used to inoculate balb/c mice. fusions expressed dur ...	2000	11083775
increased killing of bacillus subtilis on the hair roots of transgenic t4 lysozyme-producing potatoes.	transgenic potato plants expressing the phage t4 lysozyme gene which are resistant to the plant-pathogenic enterobacterium erwinia carotovora subsp. carotovora have been constructed. the agricultural growth of these potatoes might have harmful effects on soil microbiota as a result of t4 lysozyme release into the rhizosphere. to assess the bactericidal effect of roots, we have developed a novel method to associate the cells of bacillus subtilis with hair roots of plants and to quantify the survi ...	2000	10788351
aiia, an enzyme that inactivates the acylhomoserine lactone quorum-sensing signal and attenuates the virulence of erwinia carotovora.	n-acylhomoserine lactones, known as autoinducers (ais), are widely conserved signal molecules present in quorum-sensing systems of many gram-negative bacteria. ais are involved in the regulation of diverse biological functions, including expression of pathogenic genes in the plant pathogens pseudomonas solanacearum, several erwinia species, and the human pathogen pseudomonas aeruginosa. a bacterial isolate, bacillus sp. 240b1, is capable of enzymatic inactivation of ais. the gene (aiia) for ai i ...	2000	10716724
mutations in the extracellular protein secretion pathway genes (eps) interfere with rugose polysaccharide production in and motility of vibrio cholerae.	vibrio cholerae is the causal organism of the diarrheal disease cholera. the rugose variant of v. cholerae is associated with the secretion of an exopolysaccharide. the rugose polysaccharide has been shown to confer increased resistance to a variety of agents, such as chlorine, bioacids, and oxidative and osmotic stresses. it also promotes biofilm formation, thereby increasing the survival of the bacteria in the aquatic environments. here we show that the extracellular protein secretion system ( ...	2000	10722590
cdna-aflp analysis of differential gene expression in the prokaryotic plant pathogen erwinia carotovora.	for studies of differential gene expression in prokaryotes, methods for synthesizing representative cdna populations are required. here, a technique is described for the synthesis of cdna from the potato pathogens erwinia carotovora subsp. atroseptica (eca) and erwinia carotovora subsp. carotovora (ecc) using a combination of short oligonucleotide (11-mer) primers that were known to anneal to conserved sequences in the 3' regions of enterobacterial genes. specific pcr amplifications with primers ...	2000	10658663
characterization of sota and sotb, two erwinia chrysanthemi proteins which modify isopropyl-beta-d-thiogalactopyranoside and lactose induction of the escherichia coli lac promoter.	the expression, in escherichia coli, of variants of the erwinia chrysanthemi secretion genes outb and outs under the ptac promoter is toxic to the cells. during attempts to clone e. chrysanthemi genes able to suppress this toxicity, i identified two genes, sota and sotb, whose products are able to reduce the isopropyl-beta-d-thiogalactopyranoside (iptg) induction of the e. coli lac promoter. sota and sotb belong to two different families of the major facilitator superfamily. sota is a member of ...	2000	10671456
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
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
n-acyl homoserine lactone binding to the carr receptor determines quorum-sensing specificity in erwinia.	quorum sensing via an n-acyl homoserine lactone (hsl) pheromone controls the biosynthesis of a carbapenem antibiotic in erwinia carotovora. transcription of the carbapenem biosynthetic genes is dependent on the luxr-type activator protein, carr. equilibrium binding of a range of hsl molecules, which are thought to activate carr to bind to its dna target sequence, was examined using fluorescence quenching, dna bandshift analysis, limited proteolysis and reporter gene assays. carr bound the most p ...	2000	10675332
the phytopathogenic bacteria erwinia carotovora infects drosophila and activates an immune response.	although drosophila possesses potent immune responses, little is known about the microbial pathogens that infect drosophila. we have identified members of the bacterial genus erwinia that induce the systemic expression of genes encoding antimicrobial peptides in drosophila larvae after ingestion. these erwinia strains are phytopathogens and use flies as vectors; our data suggest that these strains have also evolved mechanisms for exploiting their insect vectors as hosts. erwinia infections induc ...	2000	10725405
autoinduction of 2,4-diacetylphloroglucinol biosynthesis in the biocontrol agent pseudomonas fluorescens cha0 and repression by the bacterial metabolites salicylate and pyoluteorin.	the antimicrobial metabolite 2,4-diacetylphloroglucinol (2,4-dapg) contributes to the capacity of pseudomonas fluorescens strain cha0 to control plant diseases caused by soilborne pathogens. a 2, 4-dapg-negative tn5 insertion mutant of strain cha0 was isolated, and the nucleotide sequence of the 4-kb genomic dna region adjacent to the tn5 insertion site was determined. four open reading frames were identified, two of which were homologous to phla, the first gene of the 2,4-dapg biosynthetic oper ...	2000	10671440
association of the cytoplasmic membrane protein xpsn with the outer membrane protein xpsd in the type ii protein secretion apparatus of xanthomonas campestris pv. campestris.	an xps gene cluster composed of 11 open reading frames is required for the type ii protein secretion in xanthomonas campestris pv. campestris. immediately upstream of the xpsd gene, which encodes an outer membrane protein that serves as the secretion channel by forming multimers, there exists an open reading frame (previously designated orf2) that could encode a protein of 261 amino acid residues. its n-terminal hydrophobic region is a likely membrane-anchoring sequence. antibody raised against ...	2000	10692359
ssra (tmrna) plays a role in salmonella enterica serovar typhimurium pathogenesis.	escherichia coli ssra encodes a small stable rna molecule, tmrna, that has many diverse functions, including tagging abnormal proteins for degradation, supporting phage growth, and modulating the activity of dna binding proteins. here we show that ssra plays a role in salmonella enterica serovar typhimurium pathogenesis and in the expression of several genes known to be induced during infection. moreover, the phage-like attachment site, attl, encoded within ssra, serves as the site of integratio ...	2000	10692360
quorum sensing in the plant pathogen erwinia carotovora subsp. carotovora: the role of expr(ecc).	the production of the main virulence determinants of the plant pathogen erwinia carotovora subsp. carotovora, the extracellular cell wall-degrading enzymes, is partly controlled by the diffusible signal molecule n-(3-oxohexanoyl)-l-homoserine lactone (ohhl). ohhl is synthesized by the product of the expi/cari gene. linked to expi we found a gene encoding a putative transcriptional regulator of the luxr-family. this gene, expr(ecc), is transcribed convergently to the expi gene and the two open re ...	2000	10755301
interacting signal pathways control defense gene expression in arabidopsis in response to cell wall-degrading enzymes from erwinia carotovora.	we have characterized the role of salicylic acid (sa)-independent defense signaling in arabidopsis thaliana in response to the plant pathogen erwinia carotovora subsp. carotovora. use of pathway-specific target genes as well as signal mutants allowed us to elucidate the role and interactions of ethylene, jasmonic acid (ja), and sa signal pathways in this response. gene expression studies suggest a central role for both ethylene and ja pathways in the regulation of defense gene expression trigger ...	2000	10755306
inhibition of luminescence and virulence in the black tiger prawn (penaeus monodon) pathogen vibrio harveyi by intercellular signal antagonists.	expression of luminescence in the penaeus monodon pathogen vibrio harveyi is regulated by an intercellular quorum sensing mechanism involving the synthesis and detection of two signaling molecules, one of which is n-hydroxy butanoyl-l-homoserine lactone and the other of which is uncharacterized. indirect evidence has suggested that virulence, associated with a toxic extracellular protein, and luminescence in v. harveyi are coregulated. in this study the effects of an acylated homoserine lactone ...	2000	10788385
two regions of epsl involved in species-specific protein-protein interactions with epse and epsm of the general secretion pathway in vibrio cholerae.	extracellular secretion of proteins via the type ii or general secretion pathway in gram-negative bacteria requires the assistance of at least 12 gene products that are thought to form a complex apparatus through which secreted proteins are translocated. although this apparatus is specifically required only for the outer membrane translocation step during transport across the bacterial cell envelope, it is believed to span both membranes. the epse, epsl, and epsm proteins of the type ii apparatu ...	2000	10633109
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
phylogeny of genes for secretion ntpases: identification of the widespread tada subfamily and development of a diagnostic key for gene classification.	macromolecular transport systems in bacteria currently are classified by function and sequence comparisons into five basic types. in this classification system, type ii and type iv secretion systems both possess members of a superfamily of genes for putative ntp hydrolase (ntpase) proteins that are strikingly similar in structure, function, and sequence. these include virb11, trbb, trag, gspe, pilb, pilt, and comg1. the predicted protein product of tada, a recently discovered gene required for t ...	2001	11226268
acyl-homoserine lactone production is more common among plant-associated pseudomonas spp. than among soilborne pseudomonas spp.	a total of 137 soilborne and plant-associated bacterial strains belonging to different pseudomonas species were tested for their ability to synthesize n-acyl-homoserine lactones (nahl). fifty-four strains synthesized nahl. interestingly, nahl production appears to be more common among plant-associated than among soilborne pseudomonas spp. indeed, 40% of the analyzed pseudomonas syringae strains produced nahl which were identified most often as the short-chain nahl, n-hexanoyl-l-homoserine lacton ...	2001	11229911
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
the rssb response regulator directly targets sigma(s) for degradation by clpxp.	the sigma(s) subunit of escherichia coli rna polymerase regulates the expression of stationary phase and stress response genes. control over sigma(s) activity is exercised in part by regulated degradation of sigma(s). in vivo, degradation requires the clpxp protease together with rssb, a protein homologous to response regulator proteins. using purified components, we reconstructed the degradation of sigma(s) in vitro and demonstrate a direct role for rssb in delivering sigma(s) to clpxp. rssb gr ...	2001	11238382
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
pantoea agglomerans strain eh318 produces two antibiotics that inhibit erwinia amylovora in vitro.	pantoea agglomerans (synonym: erwinia herbicola) strain eh318 produces through antibiosis a complex zone of inhibited growth in an overlay seeded with erwinia amylovora, the causal agent of fire blight. this zone is caused by two antibiotics, named pantocin a and b. using a genomic library of eh318, two cosmids, pcpp702 and pcpp704, were identified that conferred on escherichia coli the ability to inhibit growth of e. amylovora. the two cosmids conferred different antibiotic activities on e. col ...	2001	11133457
disulfide bond in pseudomonas aeruginosa lipase stabilizes the structure but is not required for interaction with its foldase.	pseudomonas aeruginosa secretes a 29-kda lipase which is dependent for folding on the presence of the lipase-specific foldase lif. the lipase contains two cysteine residues which form an intramolecular disulfide bond. variant lipases with either one or both cysteines replaced by serines showed severely reduced levels of extracellular lipase activity, indicating the importance of the disulfide bond for secretion of lipase through the outer membrane. wild-type and variant lipase genes fused to the ...	2001	11133953
gfp-based n-acyl homoserine-lactone sensor systems for detection of bacterial communication.	in order to perform single-cell analysis and online studies of n-acyl homoserine lactone (ahl)-mediated communication among bacteria, components of the vibrio fischeri quorum sensor encoded by luxr-p(luxi) have been fused to modified versions of gfpmut3* genes encoding unstable green fluorescent proteins. bacterial strains harboring this green fluorescent sensor detected a broad spectrum of ahl molecules and were capable of sensing the presence of 5 nm n-3-oxohexanoyl-l-homoserine lactone in the ...	2001	11157219
quenching quorum-sensing-dependent bacterial infection by an n-acyl homoserine lactonase.	bacterial cells sense their population density through a sophisticated cell-cell communication system and trigger expression of particular genes when the density reaches a threshold. this type of gene regulation, which controls diverse biological functions including virulence, is known as quorum sensing. quorum-sensing signals, such as acyl-homoserine lactones (ahls), are the essential components of the communication system. ahls regulate virulence gene expression in a range of plant and animal ...	2001	11459062
transgenic plants producing the bacterial pheromone n-acyl-homoserine lactone exhibit enhanced resistance to the bacterial phytopathogen erwinia carotovora.	bacterial pheromones, mainly different homoserine lactones, are central to a number of bacterial signaling processes, including those involved in plant pathogenicity. we previously demonstrated that n-oxoacyl-homoserine lactone (ohl) is essential for quorum sensing in the soft-rot phytopathogen erwinia carotovora. in this pathogen, ohl controls the coordinate activation of genes encoding the main virulence determinants, extracellular plant cell wall degrading enzymes (pcwdes), in a cell density- ...	2001	11551068
control of bacterial motility by environmental factors in polarly flagellated and peritrichous bacteria isolated from lake baikal.	despite numerous studies on bacterial motility, little is known about the regulation of this process by environmental factors in natural isolates. in this study we investigated the control of bacterial motility in response to environmental parameters in two strains isolated from the natural habitat of lake baikal. morphological characterization, carbon source utilization, fermentation analysis, and sequence comparison of 16s rrna genes showed that these strains belong to two distinct genera, i.e ...	2001	11525977
cosecretion of chaperones and low-molecular-size medium additives increases the yield of recombinant disulfide-bridged proteins.	attempts were made to engineer the periplasm of escherichia coli to an expression compartment of heterologous proteins in their native conformation. as a first approach the low-molecular-size additive l-arginine and the redox compound glutathione (gsh) were added to the culture medium. addition of 0.4 m l-arginine and 5 mm reduced gsh increased the yield of a native tissue-type plasminogen activator variant (rpa), consisting of the kringle-2 and the protease domain, and a single-chain antibody f ...	2001	11525996
gly gene cloning and expression and purification of glycinecin a, a bacteriocin produced by xanthomonas campestris pv. glycines 8ra.	glycinecin a, a bacteriocin produced by xanthomonas campestris pv. glycines, inhibits the growth of x. campestris pv. vesicatoria. we have cloned and expressed the genes encoding glycinecin a in escherichia coli. recombinant glycinecin a was purified from cell extracts by ammonium sulfate precipitation followed by chromatography on q-sepharose, mono q (ion exchange), and size exclusion columns. purified glycinecin a is composed of two polypeptides, is active over a wide ph range (6 to 9), and is ...	2001	11526012
[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
novel topology of bfpe, a cytoplasmic membrane protein required for type iv fimbrial biogenesis in enteropathogenic escherichia coli.	enteropathogenic escherichia coli (epec) produces the bundle-forming pilus (bfp), a type iv fimbria that has been implicated in virulence, autoaggregation, and localized adherence to epithelial cells. the bfpe gene is one of a cluster of bfp genes previously shown to encode functions that direct bfp biosynthesis. here, we show that an epec strain carrying a nonpolar mutation in bfpe fails to autoaggregate, adhere to hep-2 cells, or form bfp, thereby demonstrating that bfpe is required for bfp bi ...	2001	11443077
sdia of salmonella enterica is a luxr homolog that detects mixed microbial communities.	proteins of the luxr family detect the presence of n-acylhomoserine lactones (ahls) and regulate transcription accordingly. when ahls are synthesized by the same species that detects them, the system allows a bacterium to measure the population density of its own species, a phenomenon known as quorum sensing. the sdia genes of escherichia coli and salmonella enterica serovar typhimurium are predicted to encode luxr homologs. however, these species do not appear to synthesize ahls or any other mo ...	2001	11544237
nkbor, a mini-tn10-based transposon for random insertion in the chromosome of gram-negative bacteria and the rapid recovery of sequences flanking the insertion sites in escherichia coli.	we have constructed an r6k-based suicide vector that permits the random insertion of a mini-transposon named nkbor into the chromosome of gram-negative bacteria and the subsequent rapid cloning of sequences flanking the insertion site in escherichia coli. this mini-transposon contains a conditional r6k plasmid origin of replication, a kanamycin resistance gene and unique restriction sites between the is10 inverted repeats. nkbor can be propagated by replication in an e. coli strain containing th ...	2001	11446516
visualization of n-acylhomoserine lactone-mediated cell-cell communication between bacteria colonizing the tomato rhizosphere.	given that a large proportion of the bacteria colonizing the roots of plants is capable of producing n-acyl-l-homoserine lactone (ahl) molecules, it appears likely that these bacterial pheromones may serve as signals for communication between cells of different species. in this study, we have developed and characterized novel gfp-based monitor strains that allow in situ visualization of ahl-mediated communication between individual cells in the plant rhizosphere. for this purpose, three gfp-base ...	2001	11722933
assessment of the genetic diversity among strains of xanthomonas cynarae by randomly amplified polymorphic dna analysis and development of specific characterized amplified regions for the rapid identification of x. cynarae.	the randomly amplified polymorphic dna (rapd) method was used to investigate the genetic diversity in xanthomonas cynarae, which causes bacterial bract spot disease of artichoke. this rapd analysis was also intended to identify molecular markers characteristic of this species, in order to develop pcr-based markers which can be used to detect this pathogenic bacterium in artichoke fields. among the 340 rapd primers tested, 40 were selected on their ability to produce reproducible and reliable fin ...	2001	11472907
haemodynamic effects of the bacterial quorum sensing signal molecule, n-(3-oxododecanoyl)-l-homoserine lactone, in conscious, normal and endotoxaemic rats.	n-acylhomoserine lactones (ahls) are small, diffusible signalling molecules, employed by gram-negative bacteria to coordinate gene expression with cell population density. recent in vitro findings indicate that ahls may function as virulence determinants per se, through modification of cytokine production by eukaryotic cells, and by stimulating the relaxation of blood vessels. in the present study, we assessed the influence of ahls on cardiovascular function in conscious rats, and draw attention ...	2001	11487515
global regulators expa (gaca) and kdgr modulate extracellular enzyme gene expression through the rsma-rsmb system in erwinia carotovora subsp. carotovora.	the production of the main virulence determinants, the extracellular plant cell wall-degrading enzymes, and hence virulence of erwinia carotovora subsp. carotovora is controlled by a complex regulatory network. one of the global regulators, the response regulator expa, a gaca homolog, is required for transcriptional activation of the extracellular enzyme genes of this soft-rot pathogen. to elucidate the mechanism of expa control as well as interactions with other regulatory systems, we isolated ...	2001	11497464
type iii secretion contributes to the pathogenesis of the soft-rot pathogen erwinia carotovora: partial characterization of the hrp gene cluster.	the virulence of soft-rot erwinia species is dependent mainly upon secreted enzymes such as pectinases, pectin lyases, and proteases that cause maceration of plant tissue. some soft-rot erwinia spp. also harbor genes homologous to the hypersensitive reaction and pathogenesis (hrp) gene cluster, encoding components of the type iii secretion system. the hrp genes are essential virulence determinants for numerous nonmacerating gram-negative plant pathogens but their role in the virulence of soft-ro ...	2001	11497468
analysis of native microflora and selection of strains antagonistic to human pathogens on fresh produce.	the native microflora of three types of produce (green bell peppers, romaine lettuce, and prepeeled baby carrots) and two types of sprouting seeds (alfalfa and clover) were investigated. aerobic plate count (apc) for each produce or seed type as determined on pseudomonas agar f (paf) with incubation at 28 degrees c was in the range of 4 to 7 log cfu per g of tissue or seed. there was no significant difference (p > or = 0.05) in apc when the determinations were made with three agar media includin ...	2001	11510644
dna microarray-based identification of genes controlled by autoinducer 2-stimulated quorum sensing in escherichia coli.	bacterial cell-to-cell communication facilitates coordinated expression of specific genes in a growth rate-ii and cell density-dependent manner, a process known as quorum sensing. while the discovery of a diffusible escherichia coli signaling pheromone, termed autoinducer 2 (ai-2), has been made along with several quorum sensing genes, the overall number and coordination of genes controlled by quorum sensing through the ai-2 signal has not been studied systematically. we investigated global chan ...	2001	11514505
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
analysis of the type iv fimbrial-subunit gene fima of xanthomonas hyacinthi: application in pcr-mediated detection of yellow disease in hyacinths.	a sensitive and specific detection method was developed for xanthomonas hyacinthi; this method was based on amplification of a subsequence of the type iv fimbrial-subunit gene fima from strain s148. the fima gene was amplified by pcr with degenerate dna primers designed by using the n-terminal and c-terminal amino acid sequences of trypsin fragments of fima. the nucleotide sequence of fima was determined and compared with the nucleotide sequences coding for the fimbrial subunits in other type iv ...	2001	11157222
indole can act as an extracellular signal in escherichia coli.	previous work has shown that lacz fusions to the cysk, astd, tnab, and gabt genes in escherichia coli are activated by self-produced extracellular signals. using a combination of ethyl acetate extraction, reversed-phase c(18) chromatography, and thin-layer chromatography, we have purified an extracellular activating signal from e. coli supernatants. mass spectrometry revealed a molecule with an m/z peak of 117, consistent with indole. nuclear magnetic resonance analysis of the purified e. coli f ...	2001	11418561
exo-arabinanase of penicillium chrysogenum able to release arabinobiose from alpha-1,5-l-arabinan.	an exo-arabinanase, designated abnx, was purified from a culture filtrate of penicillium chrysogenum 31b by ammonium sulfate precipitation, anion-exchange chromatography, and hydrophobic chromatography. abnx had an apparent molecular mass of 47 kda. the enzyme released only arabinobiose from the nonreducing terminus of alpha-1,5-l-arabinan and showed no activity towards p-nitrophenyl-alpha-l-arabinofuranoside and alpha-1,5-l-arabinofuranobiose. abnx is the first enzyme with this mode of action.	2001	11425761
subset of hybrid eukaryotic proteins is exported by the type i secretion system of erwinia chrysanthemi.	erwinia chrysanthemi exports degradative enzymes by using a type i protein secretion system. the proteases secreted by this system lack an n-terminal signal peptide but contain a c-terminal secretion signal. to explore the substrate specificity of this system, we have expressed the e. chrysanthemi transporter system (prtdef genes) in escherichia coli and tested the ability of this abc transporter to export hybrid proteins carrying c-terminal fragments of e. chrysanthemi protease b. the c terminu ...	2001	11157948
potential symbiosis-specific genes uncovered by sequencing a 410-kilobase dna region of the bradyrhizobium japonicum chromosome.	the physical and genetic map of the bradyrhizobium japonicum chromosome revealed that nitrogen fixation and nodulation genes are clustered. because of the complex interactions between the bacterium and the plant, we expected this chromosomal sector to contain additional genes that are involved in the maintenance of an efficient symbiosis. therefore, we determined the nucleotide sequence of a 410-kb region. the overall g+c nucleotide content was 59.1%. using a minimum gene length of 150 nucleotid ...	2001	11157954
the arabidopsis isr1 locus controlling rhizobacteria-mediated induced systemic resistance is involved in ethylene signaling.	in arabidopsis, the rhizobacterial strain pseudomonas fluorescens wcs417r triggers an induced systemic resistance (isr) response that is effective against different types of pathogens. the isr signaling pathway functions independent of salicylic acid, but requires responsiveness to jasmonate (ja) and ethylene. using the genetic variability of isr inducibility between arabidopsis accessions, we recently identified a locus (isr1) on chromosome iii that is involved in isr signaling. accessions rld ...	2001	11161023
carbon limitation induces sigma(s)-dependent gene expression in pseudomonas fluorescens in soil.	recent studies employing reporter gene technology indicate that the availabilities of the major nutrients nitrogen, phosphate, and iron to pseudomonas are not severely limited in bulk soil. indirect evidence has pointed to carbon limitation as a severe nutritional stress in this environment. we show that a plasmid (pgm115)-borne transcriptional fusion between the sigma(s)-dependent escherichia coli promoter p(fic) and lacz functions as a reliable reporter for carbon availability in pseudomonas f ...	2001	11472905
the pleiotropic two-component regulatory system phop-phoq.		2001	11222580
molecular characterization of global regulatory rna species that control pathogenicity factors in erwinia amylovora and erwinia herbicola pv. gypsophilae.	rsmb(ecc) specifies a nontranslatable rna regulator that controls exoprotein production and pathogenicity in soft rot-causing erwinia carotovora subsp. carotovora. this effect of rsmb(ecc) rna is mediated mostly by neutralizing the function of rsma(ecc), an rna-binding protein of e. carotovora subsp. carotovora, which acts as a global negative regulator. to determine the occurrence of functional homologs of rsmb(ecc) in non-soft-rot-causing erwinia species, we cloned the rsmb genes of e. amylovo ...	2001	11222584
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
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
enhanced disease resistance conferred by expression of an antimicrobial magainin analog in transgenic tobacco.	magainins are a group of short peptides originally isolated from frog skin and thought to function as a natural defense mechanism against infection due to their antimicrobial properties. the engineered magainin analog peptide myp30 was found to inhibit spore germination of the oomycete, peronospora tabacina (adam) in vitro, and the growth of a bacterial pathogen erwinia carotovora subsp. carotovora (jones). transgenic tobacco (nicotiana tabacum l.) plants expressing myp30 were evaluated for resi ...	2001	11525522
salicylic acid and ethylene pathways are differentially activated in melon cotyledons by active or heat-denatured cellulase from trichoderma longibrachiatum.	infiltration of cellulase (ec 3.2.1.4) from trichoderma longibrachiatum into melon (cucumis melo) cotyledons induced several key defense mechanisms and hypersensitive reaction-like symptoms. an oxidative burst was observed 3 hours after treatment and was followed by activation of ethylene and salicylic acid (sa) signaling pathways leading to marked induction of peroxidase and chitinase activities. the treatment of cotyledons by heat-denatured cellulase also led to some induction of peroxidase an ...	2001	11553761
rpos-dependent transcriptional control of spre: regulatory feedback loop.	the stationary-phase response exhibited by escherichia coli upon nutrient starvation is mainly induced by a decrease of the clpxp-dependent degradation of the alternate primary sigma factor rpos. although it is known that the specific regulation of this proteolysis is exercised by the orphan response regulator spre, it remains unclear how spre's activity is regulated in vivo. previous studies have demonstrated that the cellular content of spre itself is paradoxically increased in stationary-phas ...	2001	11566997
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
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
rapid identification and differentiation of the soft rot erwinias by 16s-23s intergenic transcribed spacer-pcr and restriction fragment length polymorphism analyses.	current identification methods for the soft rot erwinias are both imprecise and time-consuming. we have used the 16s-23s rrna intergenic transcribed spacer (its) to aid in their identification. analysis by its-pcr and its-restriction fragment length polymorphism was found to be a simple, precise, and rapid method compared to current molecular and phenotypic techniques. the its was amplified from erwinia and other genera using universal pcr primers. after pcr, the banding patterns generated allow ...	2001	11526007
disulfide bond formation in secreton component pulk provides a possible explanation for the role of dsba in pullulanase secretion.	when expressed in escherichia coli, the 15 klebsiella oxytoca pul genes that encode the so-called pul secreton or type ii secretion machinery promote pullulanase secretion and the assembly of one of the secreton components, pulg, into pili. besides these pul genes, efficient pullulanase secretion also requires the host dsba gene, encoding a periplasmic disulfide oxidoreductase, independently of disulfide bond formation in pullulanase itself. two secreton components, the secretin pilot protein pu ...	2001	11157944
detection of methanotroph diversity on roots of submerged rice plants by molecular retrieval of pmoa, mmox, mxaf, and 16s rrna and ribosomal dna, including pmoa-based terminal restriction fragment length polymorphism profiling.	the diversity of methanotrophic bacteria associated with roots of submerged rice plants was assessed using cultivation-independent techniques. the research focused mainly on the retrieval of pmoa, which encodes the alpha subunit of the particulate methane monooxygenase. a novel methanotroph-specific community-profiling method was established using the terminal restriction fragment length polymorphism (t-rflp) technique. the t-rflp profiles clearly revealed a more complex root-associated methanot ...	2001	11526021
the emerging periplasm-localized subclass of aroq chorismate mutases, exemplified by those from salmonella typhimurium and pseudomonas aeruginosa.	chorismate mutases of the aroq homology class are widespread in the bacteria and the archaea. many of these exist as domains that are fused with other aromatic-pathway catalytic domains. among the monofunctional aroq proteins, that from erwinia herbicola was previously shown to have a cleavable signal peptide and located in the periplasmic compartment. whether or not this might be unique to e. herbicola was unknown.	2001	11532214
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
a conserved genetic module that encodes the major virion components in both the coliphage t4 and the marine cyanophage s-pm2.	sequence analysis of a 10-kb region of the genome of the marine cyanomyovirus s-pm2 reveals a homology to coliphage t4 that extends as a contiguous block from gene (g)18 to g23. the order of the s-pm2 genes in this region is similar to that of t4, but there are insertions and deletions of small orfs of unknown function. in t4, g18 codes for the tail sheath, g19, the tail tube, g20, the head portal protein, g21, the prohead core protein, g22, a scaffolding protein, and g23, the major capsid prote ...	2001	11553768
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
[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
jasmonate-dependent induction of indole glucosinolates in arabidopsis by culture filtrates of the nonspecific pathogen erwinia carotovora.	elicitors from the plant pathogen erwinia carotovora trigger coordinate induction of the tryptophan (trp) biosynthesis pathway and trp oxidizing genes in arabidopsis. to elucidate the biological role of such pathogen-induced activation we characterized the production of secondary defense metabolites such as camalexin and indole glucosinolates derived from precursors of this pathway. elicitor induction was followed by a specific increase in 3-indolylmethylglucosinolate (igs) content, but only a b ...	2001	11402212
diversity of polyamine patterns in soft rot pathogens and other plant-associated members of the enterobacteriaceae.	polyamine profiles of 91 pectolytic and other plant-associated strains from 30 taxa of the enterobacteriaceae were obtained by gradient high performance liquid chromatography (hplc). pectobacterium carotovorum, basonym erwinia carotovora, contained a high amount of putrescine and less diaminopropane. diaminopropane was absent in pectobacterium chrysanthemi, basonym e. chrysanthemi, whereas cadaverine was present in addition to the major compound putrescine. this chemotaxonomic difference reflect ...	2001	11403399
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
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
dna inversion in the tail fiber gene alters the host range specificity of carotovoricin er, a phage-tail-like bacteriocin of phytopathogenic erwinia carotovora subsp. carotovora er.	carotovoricin er is a phage-tail-like bacteriocin produced by erwinia carotovora subsp. carotovora strain er, a causative agent for soft rot disease in plants. here we studied binding and killing spectra of carotovoricin er preparations for various strains of the bacterium (strains 645ar, ec-2, n786, and p7) and found that the preparations contain two types of carotovoricin er with different host specificities; carotovoricin era possessing a tail fiber protein of 68 kda killed strains 645ar and ...	2001	11591670
isolation and characterisation of the major outer membrane protein of erwinia carotovora.	the purified major outer membrane protein (37275 da) from the psychrotrophic phytopathogen erwinia carotovora mfcl0 was structurally characterised by maldi-tof mass spectrometry, n-terminal microsequencing and dna sequence determinations, and secondary structure prediction analyses. the deduced amino acid sequence showed 76% and 72% of similarities with the serratia marcescens and escherichia coli ompa proteins respectively. dendrogram analysis allowed to point out that e. carotovora is close to ...	2001	11597348
structural requirements of endopolygalacturonase for the interaction with pgip (polygalacturonase-inhibiting protein).	to invade a plant tissue, phytopathogenic fungi produce several cell wall-degrading enzymes; among them, endopolygalacturonase (pg) catalyzes the fragmentation and solubilization of homogalacturonan. polygalacturonase-inhibiting proteins (pgips), found in the cell wall of many plants, counteract fungal pgs by forming specific complexes with them. we report the crystal structure at 1.73 a resolution of pg from the phytopathogenic fungus fusarium moniliforme (fmpg). the structure of fmpg was usefu ...	2001	11687632
regulatory interactions of csr components: the rna binding protein csra activates csrb transcription in escherichia coli.	the global regulator csra (carbon storage regulator) of escherichia coli is a small rna binding protein that represses various metabolic pathways and processes that are induced in the stationary phase of growth, while it activates certain exponential phase functions. both repression and activation by csra involve posttranscriptional mechanisms, in which csra binding to mrna leads to decreased or increased transcript stability, respectively. csra also binds to a small untranslated rna, csrb, form ...	2001	11567002
bulk and rhizosphere soil bacterial communities studied by denaturing gradient gel electrophoresis: plant-dependent enrichment and seasonal shifts revealed.	the bacterial rhizosphere communities of three host plants of the pathogenic fungus verticillium dahliae, field-grown strawberry (fragaria ananassa duch.), oilseed rape (brassica napus l.), and potato (solanum tuberosum l.), were analyzed. we aimed to determine the degree to which the rhizosphere effect is plant dependent and whether this effect would be increased by growing the same crops in two consecutive years. rhizosphere or soil samples were taken five times over the vegetation periods. to ...	2001	11571180
the global regulators gaca and sigma(s) form part of a cascade that controls alginate production in azotobacter vinelandii.	transcription of the azotobacter vinelandii algd gene, which encodes gdp-mannose dehydrogenase (the rate-limiting enzyme of alginate synthesis), starts from three sites: p1, p2, and p3. the sensor kinase gacs, a member of the two-component regulatory system, is required for transcription of algd from its three sites during the stationary phase. here we show that algd is expressed constitutively throughout the growth cycle from the p2 and p3 sites and that transcription from p1 started at the tra ...	2001	11698366
organization of genes controlling disease resistance in the potato genome.	nineteen single dominant genes (r genes) for resistance to viruses, nematodes, and fungi have been positioned on the molecular map of potato using dna markers. fourteen of those genes are located in five "hotspots" for resistance in the potato genome. quantitative trait loci (qtl) for resistance to late blight caused by the oomycete phytophthora infestans, to tuber rot caused by the bacterium erwinia carotovora ssp. atroseptica, and to root cyst nematodes have been identified on all 12 potato ch ...	2001	11701860