Homology between Enterotoxin Protein and Spore Structural Protein in <i>Clostridium perfringens</i> Type A

Abstract

Clean, intact spores from three enterotoxin positive (ent + ) and three enterotoxin‐negative (ent − ) strains of Clostridium perfringens type A were treated with urea/mercaptoethanol, alkaline mercaptoethanol, or alkaline dithiothreitol, reagents known to solubilize spore coat proteins. A protein fraction comprising approximately 15 to 30% of the total spore protein was extracted. Protein solubilized by each method contained a fraction that was precipitated by anti‐enterotoxin serum and that had enterotoxin‐like biological activity neutralizable with anti‐enterotoxin serum but not commercial C. perfringens type A antitoxin. Highly purified C. perfringens type A enterotoxin was precipitated by antiserum prepared against the solubilized spore protein from an ent + and an ent − strain. These antisera also neutralized the biological activity of C. perfringens type A enterotoxin. Examination of “core” and “coat” fractions prepared from intact spores revealed that the extractable enterotoxin‐like protein was associated with the spore coat fraction. It is concluded that the enterotoxin of C. perfringens type A is a structural component of the spore coat.