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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

lamB gene segments were obtained from Yersinia enterocolitica and Vibrio parahaemolyticus by the PCR and the DNA sequence determined. The deduced polypeptide sequences showed high similarity to six other LamB-related proteins and all contained typical signature sequences present in all members of the family but not other proteins. The aligned amino acid sequences permitted derivation of a model of LamB folding across the bacterial outer membrane using an approach successfully applied in the identification of structural features in other porins (Ferenci,T. (1994) Mol. Microbiol. 14:188-189). The alignment-based model differs from previous LamB structure predictions and is also more complex than that found for OmpF-related porins; more than 16 conserved stretches of amino acid sequence potentially corresponded to membrane-spanning segments.
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PMID:Sequence alignment and structural modelling of the LamB glycoporin family. 770 22

The chromosome of Yersinia enterocolitica encodes an enterotoxin called Yst. We analysed transcription of chromosomal yst'--luxAB and plasmid-borne yst'--lacZ operon fusions and we observed that regulation of yst expression occurs at transcriptional level. In a wild-type strain, yst was transcribed from at least two major promoters. yst transcription reached a maximum at the entry to the stationary phase and significantly varied in different Y. enterocolitica strains. In some strains, it gradually decreased during the course of our work, suggesting the existence of a mechanism switching the expression of yst to a silent state. Changes in the status of bacterial host factors rather than modifications in the yst gene are responsible for this silencing. Negative regulator YmoA participates in yst silencing and temperature regulation of yst. YmoA was also required for proper growth-phase regulation of yst, although it is not the only factor involved in this regulation. Physico-chemical parameters of the environment play an important role in yst transcription. In usual culture media (e.g. tryptic soy broth), the enterotoxin gene was transcribed only at temperatures below 30 degrees C, which argued against the role of Yst in a prolonged diarrhoea at body temperatures. However, yst transcription could be induced at 37 degrees C by increasing osmolarity and pH to the values normally present in the ileum lumen. This finding reconciles the observations concerning yst expression in a host environment and in bacterial cultures, thus supporting the idea that enterotoxin Yst is a virulence factor of Y. enterocolitica.
Mol Microbiol 1994 Dec
PMID:Regulation of the Yersinia enterocolitica enterotoxin Yst gene. Influence of growth phase, temperature, osmolarity, pH and bacterial host factors. 771 52

Pathogenic bacteria of the genus Yersinia release in vitro a set of antihost proteins called Yops. Upon infection of cultured epithelial cells, extracellular Yersinia pseudotuberculosis transfers YopE across the host cell plasma membrane. To facilitate the study of this translocation process, we constructed a recombinant Yersinia enterocolitica strain producing YopE fused to a reporter enzyme. As a reporter, we selected the calmodulin-dependent adenylate cyclase of Bordetella pertussis and we monitored the accumulation of cyclic AMP (cAMP). Since bacteria do not produce calmodulin, cyclase activity marks the presence of hybrid enzyme in the cytoplasmic compartment of the eukaryotic cell. Infection of a monolayer of HeLa cells by the recombinant Y. enterocolitica strain led to a significant increase of cAMP. This phenomenon was dependent not only on the integrity of the Yop secretion pathway but also on the presence of YopB and/or YopD. It also required the presence of the adhesin YadA at the bacterial surface. In contrast, the phenomenon was not affected by cytochalasin D, indicating that internalization of the bacteria themselves was not required for the translocation process. Our results demonstrate that Y. enterocolitica is able to transfer hybrid proteins into eukaryotic cells. This system can be used not only to study the mechanism of YopE translocation but also the fate of the other Yops or even of proteins secreted by other bacterial pathogens.
Mol Microbiol 1994 Nov
PMID:Translocation of a hybrid YopE-adenylate cyclase from Yersinia enterocolitica into HeLa cells. 788 36

A new technique is elaborated for quantitative evaluation of the polymerase chain reaction (PCR) results based on a system for yopA gene identification in Yersinia pseudotuberculosis fragment located on p45 plasmid. The analysis schedule includes amplification of the studied DNA sequence under the conditions when the reverse primer carries chemically bound biotin label on the 5'-end, hybridization of the labelled amplified fragment with the probe immobilized on the microplate surface, the probe being complementary to the inner portion of specific DNA, visualization of the label, and calculation of bound labelled DNA quantity. The lower threshold of analysis sensitivity is some picograms. It makes possible the analysis and detection of PCR product in the period of exponential increase of its content, i.e. in the initial period of reaction when the quantity of amplified DNA in the reaction mixture is not enough for reliable identification by ethidium bromide staining.
Mol Gen Mikrobiol Virusol
PMID:[Quantitative PCR-analysis: development of a system for determining the level of an amplified DNA fragment]. 789 29

The authors analyze current data on genetic control of the principal factors of pathogenicity of Shigella, Salmonella, Yersinia, Listeria and Proteus. They review the phases in the development of an infectious process and discuss problems in interaction of chromosomal and plasmid genes determining the pathogenicity of the said bacteria.
Mol Gen Mikrobiol Virusol
PMID:[The role of the chromosome and its interaction with extrachromosomal determinants during the process of genetic control of bacterial pathogenicity]. 789 31

The YadA surface protein of enteropathogenic Yersinia species contains two highly hydrophobic regions: one close to the amino terminal, and the other at the carboxy-terminal end of the YadA polypeptide. To study the role of these hydrophobic regions, we constructed 66 bp deletion mutants of the yadA genes of Yersinia enterocolitica serotype O:3 strain 6471/76 (YeO3) and of O:8 strain 8081 (YeO8). The mutant proteins, YadAYeO3-delta 83-104 and YadAYeO8-delta 8O-101, lacked 22 amino acids from the amino-terminal hydrophobic region, formed fibrillae and were expressed on the cell surface. Bacteria expressing the mutated protein lost their auto-agglutination potential as well as their collagen-binding property. Binding to fibronectin and laminin was affected differently in the YeO3 and the YeO8 constructs. The deletion did not influence YadA-mediated complement inhibition. Loss of the collagen-binding property was associated with loss of virulence in mice. We also constructed a number of YadAYeO3 deletion mutants lacking the hydrophobic carboxy-terminal end of the protein. Deletions ranging from 19 to 79 amino acids from the carboxy terminus affected polymerization of the YadA subunits, and also resulted in the loss of the YadA expression on the cell surface. This suggests that the carboxy terminus of YadA is involved in transport of the protein to the bacterial outer surface.
Mol Microbiol 1993 Dec
PMID:Hydrophobic domains affect the collagen-binding specificity and surface polymerization as well as the virulence potential of the YadA protein of Yersinia enterocolitica. 793 75

The hha gene of Escherichia coli was identified as modulating the expression of the haemolysin (hly) genes encoded by the recombinant plasmid pANN202-312. hha mutants harbouring plasmid pANN202-312 showed increased haemolysin production. The product of the hha gene, the Hha protein, shows strong homology to the YmoA protein of Yersinia enterocolitica, which plays a role in the thermoregulation of various Y. enterocolitica virulence genes. We show in this study that the Hha protein modulates the expression of haemolysin at the transcriptional level in cells harbouring plasmid pANN202-312. In addition, hha mutants show alterations in the level of plasmid DNA supercoiling. This suggests that the hha mutation increases haemolysin expression through changes in the DNA topology. This hypothesis is supported by our finding that gyr mutations, inhibitors of DNA gyrase such as novobiocin, or growth in conditions reported to reduce levels of negative supercoiling, such as low osmolarity medium, increase haemolysin production.
Mol Microbiol 1993 Sep
PMID:Escherichia coli hha mutants, DNA supercoiling and expression of the haemolysin genes from the recombinant plasmid pANN202-312. 793 7

A pair of polymerase chain reaction (PCR) primers, YC1 and YC2, selected from the sequence of the invasin locus (inv) of Y. enterocolitica, has been evaluated for specific detection of pathogenic Y. enterocolitica by PCR. The primers were hybridized at high stringency conditions to DNA from 65 pathogenic Y. enterocolitica, 16 non-pathogenic Y. enterocolitica, 18 other Yersinia and 124 non-Yersinia strains. YC2 hybridized to the pathogenic Y. enterocolitica only, while YC1 hybridized weakly to nine non-Yersinia as well. In a PCR with annealing at 64 degrees C all Y. enterocolitica, pathogenic and non-pathogenic, were positive. However, DNA from 60 non-Y. enterocolitica was amplified. With annealing at 72 degrees C, 10 non-pathogenic Y. enterocolitica and 41 non-Y. enterocolitica were positive. When a two-step PCR assay with annealing at 72 degrees C, hot-start and 1% dimethylsulphoxide (DMSO) were used, only DNA from the pathogenic Y. enterocolitica were amplified. The limit of detection was shown for four different strains to be less than 10 cells per PCR tube.
Mol Cell Probes 1994 Apr
PMID:Specific detection of pathogenic Yersinia enterocolitica by two-step PCR using hot-start and DMSO. 793 18

The identification and differentiation of the two variants of the ail gene, ailA from the more virulent American serotypes (08, 013a, 13b, 018, 020, 021) and ailNA from the less virulent non-American serotypes (03, 04, 05, 06, 09, 027 and 07, 8) was studied in a panel of 32 Yersinia enterocolitica human pathogenic isolates. A 444 bp fragment corresponding to the ail gene was amplified using a PCR procedure in all tested strains. Subsequent digestion of the PCR product by Rsal and by HaeIII endonucleases, provide electrophoretic patterns that clearly discriminate ailA and ailNA variants. This non-radioactive and reliable procedure allows large clinical and epidemiological studies, and could be proposed to survey the spread of virulent clones.
Mol Cell Probes 1994 Jun
PMID:A simple procedure to differentiate ailA and ailNA gene variants among human pathogenic Yersinia enterocolitica strains. 796 90

The iron-repressible outer membrane protein FyuA of Yersinia enterocolitica operates as a receptor with dual function: (i) as a receptor for the Y. pestis bacteriocin pesticin, and (ii) as a receptor for yersiniabactin, a siderophore that is produced by mouse-virulent Y. enterocolitica strains of biogroup IB. Cloning of the FyuA-encoding gene was achieved by mobilization of a genomic cosmid library of the pesticin-sensitive and mouse-virulent Y. enterocolitica O:8 strain WA into the pesticin-resistant WA fyuA mutant and subsequent in vivo selection of transconjugants for the ability to survive and multiply in mice (phenotype mouse virulence). The reisolated transconjugants which survived in mice for 3 d harboured a unique cosmid and phenotypically were pesticin sensitive. From this cosmid a 2650 bp SalI-PstI fragment conferring pesticin sensitivity was subcloned. Sequencing of this DNA fragment revealed a single open reading frame of 2022 bp, which encodes a deduced polypeptide of 673 amino acids with a predicted molecular mass of 73,677 Da. Cleavage of a putative signal sequence composed of 22 amino acids should lead to a mature protein of 651 amino acids with a molecular mass of 71,368 Da. The open reading frame is preceded by a sequence which shares homology with the postulated consensus Fur iron-repressor protein-binding site. FyuA shows homology to other iron-regulated TonB-dependent outer membrane proteins with receptor functions (e.g. BtuB, CirA, FepA, IutA, FhuA, FoxA, FcuA). On the basis of multiple alignment of amino acid sequences of FyuA and other TonB-dependent receptors, a phylogenetic tree was constructed, demonstrating that FyuA probably belongs to the citrate subfamily or represents a new subfamily of TonB-dependent receptors. Moreover, by complementation of the WA fyuA mutant by the cloned fyuA gene, yersiniabactin uptake and mouse virulence were restored. These studies demonstrate that the cloned pesticin/yersiniabactin receptor FyuA of Y. enterocolitica has the typical features of iron-regulated TonB-dependent outer membrane receptors for siderophores and bacteriocins and is required for mouse virulence.
Mol Microbiol 1994 Jul
PMID:The pesticin receptor of Yersinia enterocolitica: a novel virulence factor with dual function. 798 5


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