Mode of action of parasporin-4, a cytocidal protein from Bacillus thuringiensis

► Parasporin-4 (PS4) is a cytotoxic protein produced by Bacillus thuringiensis strain. ► PS4 exhibits specific cytotoxicity against human cancer cell lines, but not against normal tissue cells. ► PS4 induces plasma membrane damage to the PS4-susceptible cells. ► PS4 aggregates into oligomers only on the plasma membrane of PS4-susceptible cells. ► PS4 is a unique β-pore-forming toxin with a cholesterol-independent activity.