Enterohemorrhagic E. coli Requires N-WASP for Efficient Type III Translocation but Not for EspFU-Mediated Actin Pedestal Formation

PLoS Pathogens

Archana Kapoor¹  Scott B. Snapper¹  Kenneth G. Campellone²  Didier Vingadassalom²  Michael J. Brady²  John M. Leong²  Brian Skehan²  Douglas Robbins²  Gail Hecht³  Scott E. Battle³ 

[1] Department of Medicine and Immunology, Massachusetts General Hospital, Boston, Massachusetts, United States of America;Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America;Section of Digestive Diseases and Nutrition, University of Illinois at Chicago, Chicago, Illinois, United States of America

关键词: Actins;    Cell fusion;    Enterohaemorrhagic Escherichia coli;    Actin polymerization;    Cell membranes;    Cell staining;    DAPI staining;    Membrane proteins;   

DOI  :  10.1371/journal.ppat.1001056

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Upon infection of mammalian cells, enterohemorrhagic E. coli (EHEC) O157:H7 utilizes a type III secretion system to translocate the effectors Tir and EspFU (aka TccP) that trigger the formation of F-actin-rich ‘pedestals’ beneath bound bacteria. EspFU is localized to the plasma membrane by Tir and binds the nucleation-promoting factor N-WASP, which in turn activates the Arp2/3 actin assembly complex. Although N-WASP has been shown to be required for EHEC pedestal formation, the precise steps in the process that it influences have not been determined. We found that N-WASP and actin assembly promote EHEC-mediated translocation of Tir and EspFU into mammalian host cells. When we utilized the related pathogen enteropathogenic E. coli to enhance type III translocation of EHEC Tir and EspFU, we found surprisingly that actin pedestals were generated on N-WASP-deficient cells. Similar to pedestal formation on wild type cells, Tir and EspFU were the only bacterial effectors required for pedestal formation, and the EspFU sequences required to interact with N-WASP were found to also be essential to stimulate this alternate actin assembly pathway. In the absence of N-WASP, the Arp2/3 complex was both recruited to sites of bacterial attachment and required for actin assembly. Our results indicate that actin assembly facilitates type III translocation, and reveal that EspFU, presumably by recruiting an alternate host factor that can signal to the Arp2/3 complex, exhibits remarkable versatility in its strategies for stimulating actin polymerization.

【 授权许可】

CC BY