Self-cutting to kill: new insights into the processing of Clostridium difficile toxins.

Clostridium difficile toxins A and B are the major cause of antibiotic-associated diarrhea and pseudomembranous colitis. The toxins are one of the biggest protein toxins known, but only the N-terminal catalytic domains of the large proteins enter the cytosol. Now, a new study shows that the toxins are processed by autocatalytic cleavage, which depends on the presence of inositol hexaphosphate.