title: Phosphorylation of the enteropathogenic E. coli receptor by the Src-family kinase c-Fyn triggers actin pedestal formation.
abstract: Enteropathogenic Escherichia coli (EPEC) causes diarrhoeal disease worldwide. Pathogen adherence to host cells induces reorganization of the actin cytoskeleton into 'pedestal-like' pseudopods beneath the extracellular bacteria. This requires two bacterial virulence factors that mimic a ligand-receptor interaction. EPEC delivers its own receptor, the translocated intimin receptor (Tir), into the target cell plasma membrane, which is phosphorylated on interaction with the bacterial surface protein intimin. Tir phosphorylated on Tyr 474 (ref. 4) binds the cellular adaptor Nck, triggering actin polymerization. Nevertheless, despite its critical role, the mechanism of Tir Tyr 474 phosphorylation remains unknown. Here, by artificially uncoupling Tir delivery and activity, we show that Tir phosphorylation and Nck-dependent pedestal formation require the Src-family kinase (SFK) c-Fyn. SFK inhibitors prevent Tyr 474 phosphorylation, and cells lacking c-fyn are resistant to pedestal formation. c-Fyn exclusively phosphorylates clustered Tir in vitro, and kinase knockdown suppresses Tir phosphorylation and pedestal formation in cultured cells. These results identify the transient interaction with host c-Fyn as a pivotal link between bacterial Tir and the cellular Nck-WASP-Arp2/3 cascade, illuminating a tractable experimental system in which to dissect tyrosine kinase signalling.
authors.affiliation: University of Cambridge, Department of Pathology, Tennis Court Road, Cambridge CB2 1QP, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: Phillips
authors.forename: Richard D
authors.initials: RD
authors.lastname: Hayward
authors.forename: Vassilis
authors.initials: V
authors.lastname: Koronakis
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D018829:Adhesins, Bacterial / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D022081:Cell Surface Extensions / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004926:Escherichia coli / Q000378:metabolism*; D004927:Escherichia coli Infections / Q000378:metabolism / Q000503:physiopathology; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism / Q000382:microbiology; D051379:Mice; D041681:NIH 3T3 Cells; D015513:Oncogene Proteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D034622:RNA Interference / Q000502:physiology; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018829:Adhesins, Bacterial; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D029968:Escherichia coli Proteins; C078332:Nck protein; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; C109287:Tir protein, E coli; C073819:eaeA protein, E coli; D020794:Receptor Protein-Tyrosine Kinases; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn