title: Host protein interactions with enteropathogenic Escherichia coli (EPEC): 14-3-3tau binds Tir and has a role in EPEC-induced actin polymerization.
abstract: Enteropathogenic Escherichia coli (EPEC) cause infantile diarrhoea and are characterized by their ability to produce attaching and effacing lesions on the surface of intestinal epithelial cells. EPEC employ a filamentous type III secretion system to deliver effector molecules that subvert mammalian cell function to generate actin- and cytokeratin-rich pedestals beneath adherent bacteria. Tir is a major effector protein that is delivered to the plasma membrane of the eukaryotic cell where it acts as the receptor for the bacterial adhesin intimin. Host cell proteins that are recruited to the site of intimate attachment include focal adhesion and cytoskeletal proteins that contribute to pedestal formation. We have used Tir as bait in a yeast two-hybrid screen to identify the protein 14-3-3tau as a binding partner. 14-3-3 proteins are a family of adaptor proteins that modulate protein function in all eukaryotic cells. Here we demonstrate that the tau isoform (also known as theta) of 14-3-3 can bind specifically to Tir in a phosphorylation-independent manner, and that the interaction occurs during the infection process by co-immunoprecipitation of the partners from infected HeLa cell extracts. 14-3-3tau is recruited to the site of the pedestal (3 h after infection) and can decorate attached EPEC in the later stages of the infection process (5-7 h). Pedestal formation can be impaired by depletion of cellular 14-3-3tau using small interfering RNAs. This study indicates a direct functional role for the 14-3-3tau:Tir interaction and is the first to demonstrate the association of a host protein with the surface of EPEC.
authors.affiliation: Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, Leics LE12 5RD, UK.
authors.forename: Amit
authors.initials: A
authors.lastname: Patel
authors.forename: Nicola
authors.initials: N
authors.lastname: Cummings
authors.forename: Miranda
authors.initials: M
authors.lastname: Batchelor
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Hill
authors.forename: Thierry
authors.initials: T
authors.lastname: Dubois
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Mellits
authors.forename: Gad
authors.initials: G
authors.lastname: Frankel
authors.forename: Ian
authors.initials: I
authors.lastname: Connerton
mesh_terms: D048948:14-3-3 Proteins / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D001422:Bacterial Adhesion; D001704:Biopolymers; D002457:Cell Extracts; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D010766:Phosphorylation; D011485:Protein Binding; D021381:Protein Transport; D034741:RNA, Small Interfering / Q000235:genetics; D011956:Receptors, Cell Surface / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D048948:14-3-3 Proteins; D000199:Actins; D001704:Biopolymers; D002457:Cell Extracts; D029968:Escherichia coli Proteins; D034741:RNA, Small Interfering; D011956:Receptors, Cell Surface; C109287:Tir protein, E coli