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  • 1
    Electronic Resource
    Electronic Resource
    CROSS-TALK BETWEEN BACTERIAL PATHOGENS AND THEIR HOST CELLS (1996)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 12 (1996), S. 221-255 
    Details
    ISSN: 1081-0706
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract A taxonomically diverse group of bacterial pathogens have evolved a variety of strategies to subvert host-cellular functions to their advantage. This often involves two-way biochemical interactions leading to responses in both the pathogen and host cell. Central to this interaction is the function of a specialized protein secretion system that directs the export and/or translocation into the host cells of a number of bacterial proteins that can induce or interfere with host-cell signal transduction pathways. The understanding of these bacterial/host-cell interactions will not only lead to novel therapeutic approaches but will also result in a better understanding of a variety of basic aspects of cell physiology and immunology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.cellbio.12.1.221
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  • 2
    Electronic Resource
    Electronic Resource
    YERSINIA OUTER PROTEINS: Role in Modulation of Host Cell Signaling Responses and Pathogenesis (2005)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Microbiology 59 (2005), S. 69-89 
    Details
    ISSN: 0066-4227
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Notes: A type III secretion system (TTSS) is encoded on a virulence plasmid that is common to three pathogenic Yersinia species: Y. enterocolitica, Y. pseudotuberculosis, and Y. pestis. Pathogenic Yersinia species require this TTSS to survive and replicate within lymphoid tissues of their animal or human hosts. A set of pathogenicity factors, including those known as Yersinia outer proteins (Yops), is exported by this system upon bacterial infection of host cells. Two translocator Yops (YopB and YopD) insert into the host plasma membrane and function to transport six effector Yops (YopO, YopH, YopM, YopT, YopJ, and YopE) into the cytosol of the host cell. Effector Yops function to counteract multiple signaling responses in the infected host cell. The signaling responses counteracted by Yops are initiated by phagocytic receptors, Toll-like receptors, translocator Yops, and additional mechanisms. Innate and adaptive immune responses are thwarted as a consequence of Yop activities. A biochemical function for each effector Yop has been established, and the importance of these proteins for the pathogenesis process is being elucidated. This review focuses on the biochemical functions of Yops, the signaling pathways they modulate, and the role of these proteins in Yersinia virulence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.micro.59.030804.121320
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  • 3
    Electronic Resource
    Electronic Resource
    The RhoGAP activity of the Yersinia pseudotuberculosis cytotoxin YopE is required for antiphagocytic function and virulence (2001)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 39 (2001), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2001.02270.x
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  • 4
    Electronic Resource
    Electronic Resource
    The RhoGAP activity of the Yersinia pseudotuberculosis cytotoxin YopE is required for antiphagocytic function and virulence (2000)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 37 (2000), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A variety of pathogenic bacteria use type III secretion pathways to translocate virulence proteins into host eukaryotic cells. YopE is an important virulence factor that is translocated into mammalian cells via a plasmid-encoded type III system in Yersinia spp. YopE action in mammalian cells promotes the disruption of actin filaments, cell rounding and blockage of phagocytosis. It was reported recently that two proteins with sequence similarity to YopE, SptP of Salmonella typhimurium and ExoS of Pseudomonas aeruginosa, function as GTPase-activating proteins (GAPs) for Rho GTPases. YopE contains an ‘arginine finger’ motif that is present in SptP, ExoS and other Rho GAPs and is essential for catalysis by this class of proteins. We show here that a GST–YopE fusion protein stimulated in vitro GTP hydrolysis by the Rho family members Cdc42, RhoA and Rac1, but not by Ras. Conversion of the essential arginine in the arginine finger motif to alanine (R144A) eliminated the in vitro GAP activity of GST–YopE. Infection assays carried out with a Yersinia pseudotuberculosis strain producing YopER144A demonstrated that GAP function was essential for the disruption of actin filaments, cell rounding and inhibition of phagocytosis by YopE in HeLa cells. Furthermore, the GAP function of YopE was important for Y. pseudotuberculosis pathogenesis in a mouse infection assay. Transfection of HeLa cells with a vector that produces a constitutively active form of RhoA (RhoA-V14) prevented the disruption of actin filaments and cell rounding by YopE. Production of an activated form of Rac1 (Rac1-V12), but not RhoA-V14, in HeLa cells interfered with YopE antiphagocytic activity. These results demonstrate that YopE functions as a RhoGAP to downregulate multiple Rho GTPases, leading to the disruption of actin filaments and inhibition of bacterial uptake into host cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2000.02021.x
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  • 5
    Electronic Resource
    Electronic Resource
    YopJ of Yersinia pseudotuberculosis is required for the inhibition of macrophage TNF-α production and downregulation of the MAP kinases p38 and JNK (1998)
    Oxford BSL : Blackwell Science Ltd, UK
    Molecular microbiology 27 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Exposure of macrophages to lipopolysaccharide (LPS) leads to production of the pro-inflammatory cytokine, tumour necrosis factor alpha (TNF-α). Previous studies have suggested that pathogenic Yersinia spp. inhibit LPS-mediated production of TNF-α in macrophages, and that one of the Yop proteins secreted by the plasmid-encoded type III pathway is required for this activity. We found that TNF-α production was inhibited when J774A.1 murine macrophages were infected with wild-type Y. pseudotuberculosis but not with an isogenic ysc mutant defective for Yop secretion. We inactivated multiple yop genes to identify which of these factors are required for the inhibition of TNF-α production. A mutant unable to express yopJ was defective for the inhibition of TNF-α production. Production of TNF-α is regulated at the transcriptional and translational levels by several mitogen-activated protein (MAP) kinases. The MAP kinases p38 and JNK underwent sustained activation in macrophages infected with the yopJ mutant. Conversely, p38 and JNK were downregulated in macrophages infected with the wild-type strain. The ability of the yopJ mutant to downregulate p38 and JNK and to inhibit production of TNF-α was restored by the expression of yopJ+in trans. Therefore, YopJ is required for Y. pseudotuberculosis to downregulate MAP kinases and inhibit the production of TNF-α in macrophages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.00740.x
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  • 6
    Electronic Resource
    Electronic Resource
    A secreted protein tyrosine phosphatase with modular effector domains in the bacterial pathogen Salmonella typhimurlum (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Molecular microbiology 21 (1996), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: A number of bacterial pathogens have evolved sophisticated strategies to subvert host-cell signal-transduction pathways for their own benefit. These bacteria produce and export proteins capable of specific interactions with key mammalian cell regulatory molecules in order to derail the normal functions of the cells. In this study, we describe the identification of a modular effector protein secreted by the bacterial pathogen Salmonella typhimurium that is required for its full display of virulence. Sequence analysis revealed that a carboxy-terminal region of this protein, which we have termed SptP, is homologous to the catalytic domains of protein tyrosine phosphatases. Purified SptP protein efficiently dephosphorylated peptide substrates phosphorylated on tyrosine. An engineered mutant of SptP in which a critical Cys residue in the catalytic domain was changed to Ser was devoid of phosphatase activity, indicating a catalytic mechanism similar to that of other tyrosine phosphatases. In addition, an amino-terminal region of SptP exhibited sequence similarity to the ribosyltransferase exo-enzyme S from Pseudomonas aeruginosa and the cytotoxin YopE from Yersinia spp. The modular nature of this effector protein may allow multiple interactions with host-cell signalling functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.1996.tb02571.x
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  • 7
    Electronic Resource
    Electronic Resource
    Identification of an amino-terminal substrate-binding domain in the Yersinia tyrosine phosphatase that is required for efficient recognition of focal adhesion targets (1998)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 29 (1998), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: YopH is a protein tyrosine phosphatase (PTP) that is delivered into host mammalian cells via a type III secretion pathway in pathogenic Yersinia species. Although YopH is a highly active PTP, it preferentially targets a subset of tyrosine-phosphorylated proteins in host cells, including p130Cas. Previous in vitro studies have indicated that the carboxy-terminal PTP domain contributes specificity to the interaction of YopH with substrates. However, it is not known if the PTP domain is sufficient for substrate recognition by YopH. Here, we have identified paxillin as an additional substrate of YopH in HeLa cells. In addition, we have identified a domain in the amino-terminal region of YopH that binds to both p130Cas and paxillin and is required for the efficient recognition of substrates by the wild-type enzyme. This ‘substrate-binding’ domain exhibits a ligand specificity that is similar to that of the Crk Src homology 2 (SH2) domain, and it binds substrates directly in a phosphotyrosine-dependent manner. The substrate-binding domain of YopH may represent a novel type of protein–protein interaction module, as it lacks significant sequence similarity with any known SH2 or phosphotyrosine-binding (PTB) domain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1998.01014.x
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  • 8
    Electronic Resource
    Electronic Resource
    Two substrate-targeting sites in the Yersinia protein tyrosine phosphatase co-operate to promote bacterial virulence (2005)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 55 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: YopH is a protein tyrosine phosphatase and an essential virulence determinant of the pathogenic bacterium Yersinia. Yersinia delivers YopH into infected host cells using a type III secretion mechanism. YopH dephosphorylates several focal adhesion proteins including p130Cas in human epithelial cells, resulting in disruption of focal adhesions and cell detachment from the extracellular matrix. How the C-terminal protein tyrosine phosphatase domain of YopH targets specific substrates such as p130Cas in the complex milieu of the host cell has not been fully elucidated. An N-terminal non-catalytic domain of YopH binds p130Cas in a phosphotyrosine-dependent manner and functions as a novel substrate-targeting site. The structure of the YopH protein tyrosine phosphatase domain bound to a model phosphopeptide substrate was solved and the resulting structure revealed a second substrate-targeting site (‘site 2’) within the catalytic domain. Site 2 binds to p130Cas in a phosphotyrosine-dependent manner, and co-operates with the N-terminal domain (‘site 1’) to promote efficient recognition of p130Cas by YopH in epithelial cells. The identification of two substrate-targeting sites in YopH that co-operate to promote epithelial cell detachment and bacterial virulence reinforces the importance of protein–protein interactions for determining protein tyrosine phosphatase specificity in vivo, and highlights the sophisticated nature of microbial pathogenicity factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04477.x
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  • 9
    Electronic Resource
    Electronic Resource
    Proinflammatory signalling stimulated by the type III translocation factor YopB is counteracted by multiple effectors in epithelial cells infected with Yersinia pseudotuberculosis (2003)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 47 (2003), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2003.03350.x
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  • 10
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    Yop effectors of Yersinia spp. and actin rearrangements (2000)
    Cell Press
    Details
    Publication Date: 2000-05-01
    Print ISSN: 0966-842X
    Electronic ISSN: 1878-4380
    Topics: Biology
    Published by Cell Press
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