ADP-RIBOSYLATION OF ACTIN FROM THE GREEN-ALGA CHARA-CORALLINA BY CLOSTRIDIUM-BOTULINUM C2 TOXIN AND CLOSTRIDIUM-PERFRINGENS IOTA-TOXIN

The ability of two bacterial toxins to modify a plant actin by covalen t ADP-ribosylation was tested in the green alga Chara corallina. Using [P-32]NAD, both Clostridium botulinum C2 toxin and Clostridium perfri ngens iota toxin labelled a protein of M(r) 42 kDa which comigrated wi th actin and was immunoprecipitated by a monoclonal anti-actin antibod y. ADP-ribosylation of Chara actin was more efficient with iota toxin than with C2 toxin. The actin bundles in perfused Chara cells were not affected by toxin-containing media competent for ADP-ribosylation. Th e data indicate that monomeric plant actin is substrate for ADP-ribosy lation by the bacterial toxins.