Oligomerization is essential for apoptotic activity of Vibrio vulnificus hemolysin

Abstract

Vibrio vulnificus hemolysin (VVH), a pore forming toxin, is thought to be a virulence factor of this bacterium. It is well known that VVH induces apoptosis as well as cell lysis in susceptible target cells. Although pore formation is an essential step in cell lysis, it is unknown whether this step is necessary for VVH-induced apoptosis. In this study, Chinese hamster ovary (CHO) cells were exposed to non-oligomerized mutant F334I, in which phenylalanine 334 was replaced by isoleucine. The rate of apoptosis caused by the wild type VVH (VVH wt) was 41.5 ± 6.4%, whereas that caused by F334I was 0.4 ± 0.8% at the same concentration. Our results clearly showed that oligomerization is essential for the cell lytic activity as well as apoptotic activity of this toxin.