Botulinum C2 toxin treatment increases the G-actin pool in intact chicken cells: a model for the cytopathic action of actin-ADP-ribosylating toxins.

Botulinum C2 toxin ADP-ribosylates actin in intact chicken embryo cells in a concentration-dependent manner. This effect correlates with an enhancement in the inhibitory potency of the respective cell lysates on DNAse I activity, indicating an increase in the cellular G-actin content of toxin-treated cells. The data support our view, that ADP-ribosylation of cellular actin with subsequent depolymerization of cytoskeleton-associated F-actin to monomeric G-actin is involved in the cytotoxic effects of botulinum C2 toxin. A model of the cytopathic action of actin-ADP-ribosylating toxins is presented.