Structural basis of actin recognition and arginine ADP-ribosylation by Clostridium perfringens iota-toxin.

The ADP-ribosylating toxins (ADPRTs) produced by pathogenic bacteria modify intracellular protein and affect eukaryotic cell function. Actin-specific ADPRTs (including Clostridium perfringens iota-toxin and Clostridium botulinum C2 toxin) ADP-ribosylate G-actin at Arg-177, leading to disorganization of the cytoskeleton and cell death. Although the structures of many actin-specific ADPRTs are available, the mechanisms underlying actin recognition and selective ADP-ribosylation of Arg-177 remain unknown.

Role of Ca2+-binding motif in cytotoxicity induced by Clostridium perfringens iota-toxin.

Clostridium perfringens iota-toxin is a binary toxin composed of an enzymatic component (Ia) and a binding component (Ib). We investigated the role of the conserved Ca(2+)-binding motif of Ib in the cytotoxicity of iota-toxin. The cytotoxicity of iota-toxin increased with an increase in the concentration of extracellular Ca(2+).