Phosphorylation of the enteropathogenic E. coli receptor by the Src-family kinase c-Fyn triggers actin pedestal formation

      Nat Cell Biol. 6: 618-625, 2004

Speaker： 鄭智仁                               Time: 11/17/2004, 13:10-14:00

Commentator： 何漣漪 老師                      Place: Room 601

Abstract：

Enteropathogenic Escherichia coli (EPEC) is the archetype of bacterial pathogens that cause diarrhea worldwide. In this report, EPECs were shown to deliver their receptor, the translocated intimin receptor (Tir), into the plasma membrane of target cells, and then interacts with the bacterial surface protein intimin. When Tir binds to intimin, Tir was phosphorylated on tyrosine 474, resulting in adaptor Nck recruitment and the actin polymerization. Moreover, the authors revealed that both Tir phosphorylation and Nck-dependent pedestal formation require Src-family kinase (SFK) c-Fyn by means of artificially uncoupling of the Tir delivery and activity. Given that the context of Tir Tyr 474 is similar to c-Src tyrosine kinase target motif, the Tyr 474 motif was suggested as the target motif of Src-family kinase. This hypothesis was verified by the impact of tyrosine kinase inhibitors on Tyr 474 phosphorylation and the pedestal formation. Furthermore, cells lacking specific Src-family kinases were utilized to determine the significance of c-Fyn for Tyr 474 phosphorylation and pedestal formation. Moreover, RNA interference was employed to investigate the effect of reducing endogenous c-Fyn on pedestal formation. On the basis of these experiments, the authors indicate that c-Fyn is the kinase that links between Tir phosphorylation and Nck-WASP-Arp2/3 cascade, resulting in pedestal formation.

References：

1.      Campellone, K. G., Giese, A., Tipper, D. J. & Leong, J. M. A tyrosine-phosphorylated 12-amino-acid sequence of enteropathogenic Escherichia coli Tir binds the host adaptor protein Nck and is required for Nck localisation to actin pedestals. Mol.1Microbiol. 43, 1227–1241 (2002).

2.      Touzé, T., Hayward, R. D., Eswaran, J., Leong, J. M. & Koronakis, V. Self-association of EPEC intimin mediated by the β-barrel-containing anchor domain: a role in clustering of the Tir receptor. Mol. Microbiol. 51, 73–87 (2004).

3.  Phillips, N., Hayward, R. D. & Koronakis, V. Phosphorylation of the enteropathogenic E. coli receptor by the Src-family kinase c-Fyn triggers actin pedestal formation. Nature Cell Biol. 6, 618–625 (2004).