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

We characterized a bacterium-host cell interaction that is mediated by the Yersinia adhesin YadA. Derivatives of the virulence plasmid pIB1 harboring mutations in yadA, yopE, or yopH or in a low-calcium-response regulatory locus were introduced into a Yersinia pseudotuberculosis YPIII strain defective for Inv. The mutant strains were tested for the capacity to attach to and enter HEp-2 cells and express the cytotoxic activities of YopE and YopH. As previously shown, expression of YadA was necessary for bacterial attachment and Yop activity in the absence of Inv (R. Rosqvist, A. Forsberg, M. Rimpilainen, T. Bergman, and H. Wolf-Watz, Mol. Microbiol. 4:657-667, 1990). In addition, bacterial entry into HEp-2 cells occurred efficiently when YadA was expressed in the absence of YopE and YopH. These results demonstrated that YadA mediates intimate attachment of Y. pseudotuberculosis to HEp-2 cells and that phagocytic uptake of bacteria by this pathway is inhibited by the synergistic activities of YopH and YopE. A role for beta 1 integrins as host cell receptors for this bacterial attachment and entry mechanism was supported by HEp-2 cell adhesion and monoclonal antibody neutralization studies.
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PMID:The Yersinia pseudotuberculosis adhesin YadA mediates intimate bacterial attachment to and entry into HEp-2 cells. 768 42

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 chromosomal gene encoding the phospholipase D from Corynebacterium pseudotuberculosis (biovar ovis) isolate Whetten 1 was replaced with an allele containing a nonsense mutation. The virulence of the mutant strain (W1.31r1) and the isogenic parental strain were then compared by inoculation of goats. The wild-type strain caused abscessation at the site of infection, which then spread to the regional lymph node, while W1.31r1 had a reduced ability to establish a primary infection and was incapable of dissemination. Our results confirm that phospholipase D is a virulence determinant of C. pseudotuberculosis that increases the persistence and spread of the bacteria within the host.
Mol Microbiol 1994 Jun
PMID:Targeted mutagenesis of the phospholipase D gene results in decreased virulence of Corynebacterium pseudotuberculosis. 793 99

The recombinant plasmid pKC47M has been constructed on the base of a mini-Mu-phage and the replicon of plasmid pBR328. The plasmid was constructed for in vivo insertional mutagenesis in bacteria. Use of the plasmid in vivo alleviates the possibility of secondary transposition of the inserted sequences and enrichment of multiple-site mutations. Efficient mutagenesis caused by plasmid pKC47M was tested by induction auxotrophic mutations in Escherichia coli, Yersinia enterocolitica, Yersinia pseudotuberculosis.
Mol Gen Mikrobiol Virusol
PMID:[Design of recombinant DNA intended for insertional mutagenesis of bacteria]. 828 40

Iron-repressible outer membrane proteins (Irp) and siderophore production of Yersinia enterocolitica, serotype 08, were subjected to analysis. Here four Irps of apparent molecular weights of 62,000, 65,000, 74,000 and 75,000 could be identified which were expressed constitutively by a fur mutant. Production of a novel catechol-containing siderophore (denoted yersiniabactin) was detected by siderophore-indicator agar (chrome azurol S) and feeding experiments. Growth support by yersiniabactin under iron-restricted conditions was TonB- and Irp65-dependent and correlated with pesticin-sensitivity of Yersinia enterocolitica and Escherichia coli O. From these results we conclude that Irp65 of Y. enterocolitica functions as yersiniabactin receptor (FyuA) and as pesticin receptor. By immunoblotting using rabbit antibodies against Irp65 and chrome azurol S-agar, we were able to demonstrate that all tested mouse-lethal Y. enterocolitica and Yersinia pseudotuberculosis strains of different serotypes express siderophores and Irp65. Moreover, the anti-Irp65 rabbit serum did not cross-react with the known iron-repressible high-molecular-weight proteins (HMWPs). Evidently, the mouse lethality trait in enteropathogenic Yersinia spp. is closely associated with a novel iron-uptake system, comprising the production of a siderophore and a siderophore receptor of apparent molecular mass 65,000 Da.
Mol Microbiol 1993 Apr
PMID:Virulence of Yersinia enterocolitica is closely associated with siderophore production, expression of an iron-repressible outer membrane polypeptide of 65,000 Da and pesticin sensitivity. 831 88

The adsorption specificity of T4 is determined by the tip of the gene 37 tail fibers which bind to receptors on the bacterial surface. T4 infects only Escherichia coli and closely related Shigella species, but rare host range mutants can be isolated that infect Yersinia pseudotuberculosis I, an evolutionally distant bacterium. Some of these mutations result in amino acid residue substitutions in the C-terminal portion of gene 37, but others involve unequal exchanges between a series of sequence motifs (His boxes) in the same region. The duplication or mutational alteration of this segment apparently suffices for phage adsorption to a Yersinia receptor. It is suggested that recombination between the His box sequences can generate diversity in phage host range by shuffling receptor recognition domains.
J Mol Biol 1996 May 24
PMID:Bacteriophage T4 host range is expanded by duplications of a small domain of the tail fiber adhesin. 863 4

Multiple yop mutant strains of Yersinia pseudotuberculosis not expressing several virulence effector Yop proteins (YopH, M, E, K and YpkA) were engineered. When high-copy-number plasmids carrying the ypkA or the yopE gene with their endogenous promoters were introduced into the engineered strains, the corresponding Yop protein was secreted at high levels in vitro. These multiple yop mutant strains, when harbouring the yopE gene in trans, behaved as the wild-type strain with respect to YopB-dependent translocation of YopE through the HeLa cell plasma membrane. Using these multiple yop mutant strains, it was demonstrated that the YpkA Ser/Thr protein kinase mediates morphological alterations of infected cultured HeLa cells different from those mediated by YopE and YopH. Furthermore, YpkA is shown to be translocated by a YopB-dependent translocation mechanism from surface-located bacteria and subsequently targeted to the inner surface of the target-cell plasma membrane. The pattern of YpkA localization after infection suggests that this Yop effector is involved in interference with signal transduction.
Mol Microbiol 1996 May
PMID:The Yersinia YpkA Ser/Thr kinase is translocated and subsequently targeted to the inner surface of the HeLa cell plasma membrane. 873 38

Three isogenic Y. pseudotuberculosis strains were studied. One of them contained pVM82 plasmid which was found in foci of pseudotuberculosis outbreaks and increased Yersinia resistance to blood serum. Cells with pVM82 plasmid did not inhibit the activation of complement components C1, C2, C3, C4, and C5 in human serum and increased the consumption of these complement components in comparison with control strains. Y. pseudotuberculosis cells with pVM82 were better resistant to human neutrophil phagocytosis than bacterial cells without this plasmid. For the strain with pVM82 plasmid, a lower level of phagocytosis within the first 30 min of Y. pseudotuberculosis incubation with neutrophils and a reduced percentage of killed bacteria among all those phagocytosed over the entire period of incubation of bacteria with neutrophils were observed.
Mol Gen Mikrobiol Virusol
PMID:[Effect of Yersinia pseudotuberculosis pVM82 on the activity of components of complement and phagocytosis by human blood neutrophils]. 878 45

The PTPase YopH of Yersinia is essential to the ability of these bacteria to block phagocytosis. Wild-type Yersinia pseudotuberculosis, but not the yopH mutant strain, resisted phagocytosis by J774 cells. Ingestion of a yopH mutant was dependent on tyrosine kinase activity. Transcomplementation with wild-type yopH restored the anti-phagocytic effect, whereas introduction of the gene encoding the catalytically inactive yopHC403A was without effect. The PTPase inhibitor orthovanadate impaired the anti-phagocytic effect of the wild-type strain, further demonstrating the importance of bacteria-derived PTPase activity for this event. The ability to resist phagocytosis indicates that the effect of the bacterium is immediately exerted when it becomes associated with the phagocyte. Within 30 s after the onset of infection, wild-type Y. pseudotuberculosis caused a YopH-dependent dephosphorylation of phosphotyrosine proteins in J774 cells. Furthermore, interaction of the cells with phagocytosable strains led to a rapid and transient increase in tyrosine phosphorylation of paxillin and some other proteins, an event dependent on the presence of the bacterial surface-located protein invasin. Co-infection with the phagocytosable strain and the wild-type strain abolished the induction of tyrosine phosphorylation. Taken together, the present findings demonstrate an immediate YopH-mediated dephosphorylation of macrophage phosphotyrosine proteins, suggesting that this PTPase acts by preventing early phagocytosis-linked signalling in the phagocyte.
Mol Microbiol 1996 Jun
PMID:YopH of Yersinia pseudotuberculosis interrupts early phosphotyrosine signalling associated with phagocytosis. 880 58


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