ADP-RIBOSYLTRANSFERASE TYPE-A FROM TURKEY ERYTHROCYTES MODIFIES ACTIN AT ARG-95 AND ARG-372

Turkey erythrocyte ADP-ribosyltransferase A catalyzes the transfer of ADP-ribose from NAD to both monomeric and polymeric skeletal muscle alpha-actin with the incorporation of 2 mol of ADP-ribose per mol of actin. In contrast, Clostridium perfringens iota toxin ADP-ribosylates only G-actin, with modification at arginine-177 [Vandekerckhove, J., et al. (1987) FEES Lett. 255, 48-42]. Transferase A-catalyzed modifications are sensitive to 0.5 M neutral hydroxylamine, consistent with the arginine side chain modification. Radiolabeled peptides ADP-ribosylated by transferase A were generated by tryptic digestion and purified by reversed phase high performance Liquid chromatography. Amino acid sequence and molecular mass analysis identified the ADP-ribosylation sites as Arg-95 and Arg-372 of actin; both residues are located within subdomain-1 of the actin 3D structure [Kabsch, W., et al. (1990) Nature 347, 37-44]. ADP-ribosylation did not affect cytochalasin D-stimulated G-actin ATPase, the binding of actin to DNase I or to gelsolin, or the ability of actin to polymerize. Following ADP-ribosylation, however, a prolonged delay in polymerization was observed, consistent with a decreased rate of nucleation.