ADP-ribosylation of Arg28 and Arg206 on the actin molecule by chicken arginine-specific ADP-ribosyltransferase.

We reported previously on ADP-ribosylation of actins by chicken arginine-specific ADP-ribosyltransferase in vitro and in situ and the inhibition of actin polymerization by this modification [Terashima, M., Mishima, K., Yamada, K., Tsuchiya, M., Wakutani, T. & Shimoyama, M. (1992) Eur. J. Biochem. 204, 305-311]. In the present study, we determined amino acid residues of ADP-ribosylation site(s) in globular (G-) and filamentous (F-) actins and examined the molecular basis of the modification of actin. Arginine-specific ADP-ribosylation occurred at Arg28 and Arg206 in G-actin, but only at Arg28 in F-actin. ADP-ribosylation of Arg206, located on the pointed end of the actin molecule, significantly blocked the interaction with deoxyribonuclease I. These results indicate that Arg206 in G-actin may be involved in actin polymerization. ADP-ribosylation of Arg28, located on the outer surface of actin molecule, did not affect the binding activity with myosin subfragment-1, that is thought to interact through the N-terminal amino acid residues of G-actin. ADP-ribosylation at both Arg28 and Arg206 of G-actin had no apparent effect on the intrinsic ATPase activity. We concluded from this study that ADP-ribosylation of Arg206 in G-actin causes the inhibition of actin polymerization, and that ADP-ribosylation of Arg28 occurs in F-actin.