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Query: UNIPROT:P06889 (Mol)
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A mode of feces sample preparation was developed for polymerase chain reaction (PCR) assay. It was based on alkaline treatment of the material. This treatment killed the most part of indigenous microflora, whereas Yersinia survived, because it was relatively resistant to alkaline. The mode was tested using human feces artificially contaminated with Yersinia pseudotuberculosis. Positive responses in samples containing 10(3)-10(8) microbial cells per ml were obtained by PCR assay with Yersi and Yers2, Invl and Inv2, YP3 and YP4 primers. Diagnostic efficiency of PCR for patients, small mammals, and washings from environmental objects was 4.75, 1.66, and 2.12 times higher than diagnostic efficiency of bacteriological analysis of these samples, respectively. Positive results in PCR were obtained at the day of the material collection and treatment, whereas Y. pseudotuberculosis was isolated only after 8-20 days. Positive samples in PCR and in bacteriological analysis were found to coincide. A brief scheme of the Y. pseudotuberculosis laboratory diagnosis is suggested. According to this scheme, target-oriented bacteriological assay is performed only in those samples, in which preliminary PCR assay after 1-3 days of incubation gave positive results of Y. pseudotuberculosis DNA detection.
Mol Gen Mikrobiol Virusol 2002
PMID:[Mode of sample preparation for pseudotuberculosis laboratory diagnosis by polymer chain reaction method]. 1253 70

Type III secretion systems are used by several pathogens to translocate effector proteins into host cells. Yersinia pseudotuberculosis delivers several Yop effectors (e.g. YopH, YopE and YopJ) to counteract signalling responses during infection. YopB, YopD and LcrV are components of the translocation machinery. Here, we demonstrate that a type III translocation protein stimulates proinflammatory signalling in host cells, and that multiple effector Yops counteract this response. To examine proinflammatory signalling by the type III translocation machinery, HeLa cells infected with wild-type or Yop-Y. pseudotuberculosis strains were assayed for interleukin (IL)-8 production. HeLa cells infected with a YopEHJ- triple mutant released significantly more IL-8 than HeLa cells infected with isogenic wild-type, YopE-, YopH- or YopJ- bacteria. Complementation analysis demonstrated that YopE, YopH or YopJ are sufficient to counteract IL-8 production. IL-8 production required YopB, but did not require YopD, pore formation or invasin-mediated adhesion. In addition, YopB was required for activation of nuclear factor kappa B, the mitogen-activated protein kinases ERK and JNK and the small GTPase Ras in HeLa cells infected with the YopEHJ- mutant. We conclude that interaction of the Yersinia type III translocator factor YopB with the host cell triggers a proinflammatory signalling response that is counteracted by multiple effectors in host cells.
Mol Microbiol 2003 Mar
PMID:Proinflammatory signalling stimulated by the type III translocation factor YopB is counteracted by multiple effectors in epithelial cells infected with Yersinia pseudotuberculosis. 1260 36

The obligate intracellular bacterium Chlamydia trachomatis occupies a parasitophorous vacuole termed an inclusion. During its intracellular developmental cycle, C. trachomatis maintains this intracellular niche, presumably by expressing a type III secretion system, which deploys a set of host cell-interactive proteins including inclusion membrane-localized proteins termed Incs. Some Incs are expressed and secreted by 2 h (early cycle) after infection, whereas the expression of type III-specific genes is not detectable until 6-12 h (mid-cycle). To resolve this paradox, we investigated the presence of a type III apparatus on elementary bodies (EBs) that might function early in infection. We demonstrate the existence of the type III secretory apparatus by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) and immunoblot analyses of purified EB extracts. Immunoblots using polyclonal antibodies specific for the core apparatus component CdsJ identified this protein in both EB and reticulate body (RB) extracts. Furthermore, CdsJ-specific signals were detected by immunoblot of whole infected-culture extracts and by indirect immunofluorescence of infected monolayers at times before the detection of cdsJ-specific message. Finally, expression of IncC, expressed by 2 h after infection during C. trachomatis infections, in Yersinia pseudotuberculosis resulted in its secretion via the Yersinia type III apparatus. Based on these data, we propose a model in which type III secretion pores are present on EBs and mediate secretion of early Incs and possible additional effectors. Mid-cycle expression of type III genes would then replenish secretion apparatus on vegetative RBs and serve as a source of secretion pores for subsequently formed EBs.
Mol Microbiol 2003 May
PMID:Chlamydia trachomatis type III secretion: evidence for a functional apparatus during early-cycle development. 1269 13

We have studied the role of acidic pH as a barrier for the colonization of the plant apoplast by Erwinia chrysanthemi. A minitransposon containing a promoterless reporter gene, gus, was used for random mutagenesis of the bacterial genome. An acid-sensitive mutant, named BT119, was isolated and had the following differential features with respect to the wild-type strain: (i) inability to grow at pH </= 5.5; (ii) decreased survival at acid pH and in plant tissues; (iii) increased susceptibility to antimicrobial peptides; (iv) decreased virulence in chicory leaves and pear fruits; (v) reduced polygalacturonase production; and (vi) reduced ability to alkalinize chicory tissues after infection. The sequence of the interrupted gene was highly similar to the phoQ gene, which is involved in environmental sensing in several bacteria, such as Yersinia pseudotuberculosis, Erwinia carotovora, Salmonella typhimurium and Escherichia coli and thus, this designation was used for the E. chrysanthemi system. This gene was induced at low Mg(2+) concentrations and in planta. These results suggest that E. chrysanthemi PhoP-PhoQ system plays an important role in bacterial survival in plant tissues during the initial infection stages.
Mol Microbiol 2003 Jul
PMID:The Erwinia chrysanthemi phoP-phoQ operon plays an important role in growth at low pH, virulence and bacterial survival in plant tissue. 1282 34

Proteins with bacterial immunoglobulin-like (Big) domains, such as the Yersinia pseudotuberculosis invasin and Escherichia coli intimin, are surface-expressed proteins that mediate host mammalian cell invasion or attachment. Here, we report the identification and characterization of a new family of Big domain proteins, referred to as Lig (leptospiral Ig-like) proteins, in pathogenic Leptospira. Screening of L. interrogans and L. kirschneri expression libraries with sera from leptospirosis patients identified 13 lambda phage clones that encode tandem repeats of the 90 amino acid Big domain. Two lig genes, designated ligA and ligB, and one pseudogene, ligC, were identified. The ligA and ligB genes encode amino-terminal lipoprotein signal peptides followed by 10 or 11 Big domain repeats and, in the case of ligB, a unique carboxy-terminal non-repeat domain. The organization of ligC is similar to that of ligB but contains mutations that disrupt the reading frame. The lig sequences are present in pathogenic but not saprophytic Leptospira species. LigA and LigB are expressed by a variety of virulent leptospiral strains. Loss of Lig protein and RNA transcript expression is correlated with the observed loss of virulence during culture attenuation of pathogenic strains. High-pressure freeze substitution followed by immunocytochemical electron microscopy confirmed that the Lig proteins were localized to the bacterial surface. Immunoblot studies with patient sera found that the Lig proteins are a major antigen recognized during the acute host infection. These observations demonstrate that the Lig proteins are a newly identified surface protein of pathogenic Leptospira, which by analogy to other bacterial immunoglobulin superfamily virulence factors, may play a role in host cell attachment and invasion during leptospiral pathogenesis.
Mol Microbiol 2003 Aug
PMID:Pathogenic Leptospira species express surface-exposed proteins belonging to the bacterial immunoglobulin superfamily. 1289 19

The O-antigen of lipopolysaccharide (LPS) is a virulence factor in enterobacterial infections, and the advantage of its genetic loss in the lethal pathogen Yersinia pestis has remained unresolved. Y. pestis and Salmonella enterica express beta-barrel surface proteases of the omptin family that activate human plasminogen. Plasminogen activation is central in pathogenesis of plague but has not, however, been found to be important in diarrhoeal disease. We observed that the presence of O-antigen repeats on wild-type or recombinant S. enterica, Yersinia pseudotuberculosis or Escherichia coli prevents plasminogen activation by PgtE of S. enterica and Pla of Y. pestis; the O-antigen did not affect incorporation of the omptins into the bacterial outer membrane. Purified His6-Pla was successfully reconstituted with rough LPS but remained inactive after reconstitution with smooth LPS. Expression of smooth LPS prevented Pla-mediated adhesion of recombinant E. coli to basement membrane as well as invasion into human endothelial cells. Similarly, the presence of an O-antigen prevented PgtE-mediated bacterial adhesion to basement membrane. Substitution of Arg-138 and Arg-171 of the motif for protein binding to lipid A 4'-phosphate abolished proteolytic activity but not membrane translocation of PgtE, indicating dependence of omptin activity on a specific interaction with lipid A. The results suggest that Pla and PgtE require LPS for activity and that the O-antigen sterically prevents recognition of large-molecular-weight substrates. Loss of O-antigen facilitates Pla functions and invasiveness of Y. pestis; on the other hand, smooth LPS renders plasminogen activator cryptic in S. enterica.
Mol Microbiol 2004 Jan
PMID:Lack of O-antigen is essential for plasminogen activation by Yersinia pestis and Salmonella enterica. 1465 23

Diversification of bacterial species and pathotypes is largely caused by horizontal transfer of diverse DNA elements such as plasmids, phages and genomic islands (e.g. pathogenicity islands, PAIs). A PAI called high-pathogenicity island (HPI) carrying genes involved in siderophore-mediated iron acquisition (yersiniabactin system) has previously been identified in Yersinia pestis, Y. pseudotuberculosis and Y. enterocolitica IB strains, and has been characterized as an essential virulence factor in these species. Strikingly, an orthologous HPI is a widely distributed virulence determinant among Escherichia coli and other Enterobacteriaceae which cause extraintestinal infections. Here we report on the HPI of E. coli strain ECOR31 which is distinct from all other HPIs described to date because the ECOR31 HPI comprises an additional 35 kb fragment at the right border compared to the HPI of other E. coli and Yersinia species. This part encodes for both a functional mating pair formation system and a DNA-processing region related to plasmid CloDF13 of Enterobacter cloacae. Upon induction of the P4-like integrase, the entire HPI of ECOR31 is precisely excised and circularised. The HPI of ECOR31 presented here resembles integrative and conjugative elements termed ICE. It may represent the progenitor of the HPI found in Y. pestis and E. coli, revealing a missing link in the horizontal transfer of an element that contributes to microbial pathogenicity upon acquisition.
Mol Microbiol 2004 Feb
PMID:A novel integrative and conjugative element (ICE) of Escherichia coli: the putative progenitor of the Yersinia high-pathogenicity island. 1473 Dec 83

The Yersinia high-pathogenicity island (HPI) encodes the siderophore yersiniabactin-mediated iron uptake system. The HPI of Yersinia pseudotuberculosis I has previously been shown to be able to excise precisely from the bacterial chromosome by recombination between the attB-R and attB-L sites flanking the island. However, the nature of the Y. pseudotuberculosis HPI excision machinery remained unknown. We show here that, upon excision, the HPI forms an episomal circular molecule. The island thus has the ability to excise from the chromosome, circularize and reintegrate itself, either in the same location or in another asn tRNA copy. We also demonstrate that the HPI-encoded bacteriophage P4-like integrase (Int) plays a critical role in HPI excision and that, like phage integrases, it acts as a site-specific recombinase that catalyses both excision and integration reactions. However, Int alone cannot efficiently promote recombination between the attB-R and attB-L sites, and we demonstrate that a newly identified HPI-borne factor, designated Hef (for HPI excision factor) is also required for this activity. Hef belongs to a family of recombination directionality factors. Like the other members of this family, Hef probably plays an architectural rather than a catalytic role and promotes HPI excision from the chromosome by driving the function of Int towards an excisionase activity. The fact that the HPI, and probably several other pathogenicity islands, carry a machinery of integration/excision highly similar to those of bacteriophages argues for a phage-mediated acquisition and transfer of these elements.
Mol Microbiol 2004 Jun
PMID:Excision of the high-pathogenicity island of Yersinia pseudotuberculosis requires the combined actions of its cognate integrase and Hef, a new recombination directionality factor. 1516 37

Important pathogens in the genus Yersinia include the plague bacillus Yersinia pestis and two enteropathogenic species, Yersinia pseudotuberculosis and Yersinia enterocolitica. A shift in growth temperature induced changes in the number and type of acyl groups on the lipid A of all three species. After growth at 37 degrees C, Y. pestis lipopolysaccharide (LPS) contained the tetra-acylated lipid IV(A) and smaller amounts of lipid IV(A) modified with C10 or C12 acyl groups, Y. pseudotuberculosis contained the same forms as part of a more heterogeneous population in which lipid IV(A) modified with C16:0 predominated, and Y. enterocolitica produced a unique tetra-acylated lipid A. When grown at 21 degrees C, however, the three yersiniae synthesized LPS containing predominantly hexa-acylated lipid A. This more complex lipid A stimulated human monocytes to secrete tumour necrosis factor-alpha, whereas the lipid A synthesized by the three species at 37 degrees C did not. The Y. pestis phoP gene was required for aminoarabinose modification of lipid A, but not for the temperature-dependent acylation changes. The results suggest that the production of a less immunostimulatory form of LPS upon entry into the mammalian host is a conserved pathogenesis mechanism in the genus Yersinia, and that species-specific lipid A forms may be important for life cycle and pathogenicity differences.
Mol Microbiol 2004 Jun
PMID:Variation in lipid A structure in the pathogenic yersiniae. 1516 39

The transcriptional activator RovA of Yersinia pseudotuberculosis, a member of the SlyA/Hor family, activates its own expression and that of the virulence factor invasin in response to moderate growth temperature, but not at 37 degrees C. In this work, we analysed the mechanism of RovA-dependent transcription of the rovA and inv genes. We found that rovA is transcribed by two different promoters. Sequences located upstream and downstream of the promoters were involved in rovA autoregulation and interacted specifically with the RovA protein. To define the nucleotides recognized by the RovA protein, we determined the RovA binding sites in the rovA and the inv regulatory region and revealed related AT-rich sequence motifs at diverse positions relative to the transcriptional start sites. We also showed that rovA and the RovA-dependent inv gene were both subject to silencing by the nucleoid-associated H-NS protein of Y. pseudotuberculosis. The binding sites of the H-NS and RovA proteins in the rovA and inv regulatory sequences were superimposed, and the presence of the RovA protein alleviated H-NS-mediated repression of the rovA and inv promoter. Moreover, loss of H-NS function led to a significant increase in rovA and inv transcription nearly independently of RovA, indicating that RovA acts mainly as an antirepressor. We therefore hypothesize that the transcription level of RovA-dependent genes reflects the outcome of the RovA/H-NS competition and the rovA autoregulatory mechanism.
Mol Microbiol 2004 Aug
PMID:RovA is autoregulated and antagonizes H-NS-mediated silencing of invasin and rovA expression in Yersinia pseudotuberculosis. 1525 99


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