Sphingomyelin Functions as a Novel Receptor for Helicobacter pylori VacA

PLoS Pathogens

Joseph Eichberg¹  Sean S. Kostolansky¹  Steven R. Blanke¹  Hetal K. Patel²  Roberto A. Ballivian²  Vijay R. Gupta² 

[1] Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America;Department of Microbiology, Institute for Genomic Biology, University of Illinois, Urbana, Illinois, United States of America

关键词: Cell membranes;    Lipids;    Cell binding;    Toxins;    HeLa cells;    Membrane proteins;    Cholesterol;    Flow cytometry;   

DOI  :  10.1371/journal.ppat.1000073

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The vacuolating cytotoxin (VacA) of the gastric pathogen Helicobacter pylori binds and enters epithelial cells, ultimately resulting in cellular vacuolation. Several host factors have been reported to be important for VacA function, but none of these have been demonstrated to be essential for toxin binding to the plasma membrane. Thus, the identity of cell surface receptors critical for both toxin binding and function has remained elusive. Here, we identify VacA as the first bacterial virulence factor that exploits the important plasma membrane sphingolipid, sphingomyelin (SM), as a cellular receptor. Depletion of plasma membrane SM with sphingomyelinase inhibited VacA-mediated vacuolation and significantly reduced the sensitivity of HeLa cells, as well as several other cell lines, to VacA. Further analysis revealed that SM is critical for VacA interactions with the plasma membrane. Restoring plasma membrane SM in cells previously depleted of SM was sufficient to rescue both toxin vacuolation activity and plasma membrane binding. VacA association with detergent-resistant membranes was inhibited in cells pretreated with SMase C, indicating the importance of SM for VacA association with lipid raft microdomains. Finally, VacA bound to SM in an in vitro ELISA assay in a manner competitively inhibited by lysenin, a known SM-binding protein. Our results suggest a model where VacA may exploit the capacity of SM to preferentially partition into lipid rafts in order to access the raft-associated cellular machinery previously shown to be required for toxin entry into host cells.

【 授权许可】

CC BY