Contribution of Histidine Residues to Oligomerization of θ-Toxin (Perfringolysin O), a Cholesterol-Binding Cytolysin

Abstract

  θ-Toxin (perfringolysin O) modified by diethyl pyrocarbonate, a histidine-specific reagent, lost its hemolytic activity. The modified toxin retains the activities of binding to and insertion into cholesterol-containing membranes but lacks the ability to form oligomers. These results suggest that histidine residues of θ-toxin contribute their share to cytolysis, especially the oligomerization process.