title: A secreted protein tyrosine phosphatase with modular effector domains in the bacterial pathogen Salmonella typhimurium.
abstract: 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 exoenzyme 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.
authors.affiliation: Department of Molecular Genetics and Microbiology, School of Medicine, State University of New York at Stony Brook 11794-5222, USA.
authors.forename: K
authors.initials: K
authors.lastname: Kaniga
authors.forename: J
authors.initials: J
authors.lastname: Uralil
authors.forename: J B
authors.initials: JB
authors.lastname: Bliska
authors.forename: J E
authors.initials: JE
authors.lastname: Galán
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002460:Cell Line; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial; D004195:Disease Models, Animal; D004847:Epithelial Cells; D005260:Female; D006801:Humans; D008264:Macrophages / Q000166:cytology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D017027:Protein Tyrosine Phosphatases / Q000235:genetics* / Q000378:metabolism; D012480:Salmonella Infections / Q000382:microbiology; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D017386:Sequence Homology, Amino Acid; D014774:Virulence
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D017027:Protein Tyrosine Phosphatases; C439890:sptP protein, Salmonella typhimurium