Oligomerization of Clostridium perfringens epsilon toxin is dependent upon caveolins 1 and 2.
Evidence from multiple studies suggests that Clostridium perfringens ε-toxin is a pore-forming toxin, assembling into oligomeric complexes in the plasma membrane of sensitive cells. In a previous study, we used gene-trap mutagenesis to identify mammalian factors contributing to toxin activity, including caveolin-2 (CAV2). In this study, we demonstrate the importance of caveolin-2 and its interaction partner, caveolin-1 (CAV1), in ε-toxin-induced cytotoxicity. Using CAV2-specific shRNA in a toxin-sensitive human kidney cell line, ACHN, we confirmed that cells deficient in CAV2 exhibit increased resistance to ε-toxin. Similarly, using CAV1-specific shRNA, we demonstrate that cells deficient in CAV1 also exhibit increased resistance to the toxin. Immunoprecipitation of CAV1 and CAV2 from ε-toxin-treated ACHN cells demonstrated interaction of both CAV1 and -2 with the toxin. Furthermore, blue-native PAGE indicated that the toxin and caveolins were components of a 670 kDa protein complex. Although ε-toxin binding was only slightly perturbed in caveolin-deficient cells, oligomerization of the toxin was dramatically reduced in both CAV1- and CAV2-deficient cells. These results indicate that CAV1 and -2 potentiate ε-toxin induced cytotoxicity by promoting toxin oligomerization - an event which is requisite for pore formation and, by extension, cell death.
Division of Infectious Disease, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America.
Christine M
CM
Fennessey
Jinsong
J
Sheng
Donald H
DH
Rubin
Mark S
MS
McClain
D000818:Animals; D001427:Bacterial Toxins / Q000737:chemistry* / Q000633:toxicity; D051242:Caveolin 1 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051243:Caveolin 2 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D004285:Dogs; D055785:Gene Knockdown Techniques; D006801:Humans; D061985:Madin Darby Canine Kidney Cells; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D034741:RNA, Small Interfering / Q000235:genetics
D001427:Bacterial Toxins; D051242:Caveolin 1; D051243:Caveolin 2; C039811:Clostridium perfringens epsilon-toxin; D034741:RNA, Small Interfering