title: Contribution of the twin arginine translocation system to the virulence of enterohemorrhagic Escherichia coli O157:H7.
abstract: Shiga toxin-producing Escherichia coli O157:H7 is a major food-borne infectious pathogen. In order to analyze the contribution of the twin arginine translocation (TAT) system to the virulence of E. coli O157:H7, we deleted the tatABC genes of the O157:H7 EDL933 reference strain. The mutant displayed attenuated toxicity on Vero cells and completely lost motility on soft agar plates. Further analyses revealed that the Delta tatABC mutation impaired the secretion of the Shiga toxin 1 (Stx1) and abolished the synthesis of H7 flagellin, which are two major known virulence factors of enterohemorrhagic E. coli O157:H7. Expression of the EDL933 stxAB(1) genes in E. coli K-12 conferred verotoxicity on this nonpathogenic strain. Remarkably, cytotoxicity assay and immunoblot analysis showed, for the first time, an accumulation of the holotoxin complex in the periplasm of the wild-type strain and that a much smaller amount of StxA(1) and reduced verotoxicity were detected in the Delta tatC mutant cells. Together, these results establish that the TAT system of E. coli O157:H7 is an important virulence determinant of this enterohemorrhagic pathogen.
authors.affiliation: Laboratoire de Chimie Bactérienne, UPR9043, IBSM, CNRS, F-13402 Marseille Cedex 20, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Pradel
authors.forename: Changyun
authors.initials: C
authors.lastname: Ye
authors.forename: Valérie
authors.initials: V
authors.lastname: Livrelli
authors.forename: Jianguo
authors.initials: J
authors.lastname: Xu
authors.forename: Bernard
authors.initials: B
authors.lastname: Joly
authors.forename: Long-Fei
authors.initials: LF
authors.lastname: Wu
mesh_terms: D000818:Animals; D001483:Base Sequence; D002522:Chlorocebus aethiops; D004269:DNA, Bacterial / Q000235:genetics; D019453:Escherichia coli O157 / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000235:genetics / Q000502:physiology*; D005408:Flagellin / Q000096:biosynthesis; D017353:Gene Deletion; D005798:Genes, Bacterial; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D021381:Protein Transport; D022622:Shiga Toxin 1 / Q000378:metabolism; D014709:Vero Cells; D014774:Virulence / Q000235:genetics / Q000502:physiology
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D022622:Shiga Toxin 1; C408585:twin-arginine translocase complex, E coli; D005408:Flagellin