ADP‐ribosylation of actin isoforms by Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin

Open Access
Publisher Website
Google Scholar
Abstract
The substrate specificities of the actin-ADP-ribosylating toxins, Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin were studied by using five different preparations of actin isoforms: α-skeletal muscle actin, α-cardiac muscle actin, gizzard γ-smooth muscle actin, spleen β- and γ-cytoplasmic actin, and aortic smooth muscle actin containing α- and γ-smooth muscle actin isoforms. C. perfringens iota toxin ADP-ribosylated all actin isoforms tested, whereas C. botulinum C2 toxin did not modify α-skeletal muscle actin or α-cardiac muscle actin. Spleen β/γ-cytoplasmic actin and gizzard γ-smooth muscle actin were substrates of C. botulinum C2 toxin. In the aortic smooth muscle actin preparation, γ-smooth muscle actin but not α-smooth muscle actin was ADP-ribosylated by C. botulinum C2 toxin. The data indicate that, in contrast to C. perfringens iota toxin, C. botulinum C2 toxin ADP-ribosylates only β/γ-cytoplasmic and γ-smooth muscle actin and suggest that the N-terminal region of actin isoforms define the substrate specificity for ADP-ribosylation by C. botulinum C2 toxin.