ADP-RIBOSYLATION OF ARG28 AND ARG206 ON THE ACTIN MOLECULE BY CHICKENARGININE-SPECIFIC ADP-RIBOSYLTRANSFERASE

We reported previously on ADP-ribosylation of actins by chicken argini ne-specific ADP-ribosyltransferase in vitro and in situ and the inhibi tion of actin polymerization by this modification [Terashima, M., Mish ima, K., Yamada, K., Tsuchiya, M., Wakutani, T. & Shimoyama, M. (1992) Eur. J. Biochem, 204, 305-311]. In the present study, we determined a mino acid residues of ADP-robosylation site(s) in globular (G-) and fi lamentous (F-) actins and examined the molecular basis of the modifica tion of actin. Arginine-specific ADP-ribosylation occurred at Arg28 an d Arg206 in G-actin, but only at Arg28 in F-actin. ADP-ribosylation of Arg206, located on the pointed end of the actin molecule, significant ly blocked the interaction with deoxyribonuclease I. These results ind icate that Arg206 in G-actin may be involved in actin polymerization. ADP-ribosylation of Arg28, located on the outer surface of actin molec ule, did not affect the binding activity with myosin subfragment-1, th at is thought to interact through the N-terminal amino acid residues o f G-actin. ADP-ribosylation at both Arg28 and Arg206 of G-actin had no apparent effect on the intrinsic ATPase activity. We concluded from t his study that ADP-ribosylation of Arg206 in G-actin causes the inhibi tion of actin polymerization, and that ADP-ribosylation of Arg28 occur s in F-actin.