Studies on the ATP-binding Site of Actin Using Site-directed Mutagenesis
Hydrolysis of the actin-bound AT? is linked to actin filament turnover. However, neither the role nor the mechanism of the actin ATPase are well established. A novel role for the actin ATPase in muscle contraction has been proposed, making actin the principal force generator (1). The crystal structures of α- (2,3) and β-actin (4) suggest involvement of serine 14 (S14) and aspartic acid 157 (D157) in ATP hydrolysis (2,5). Myslik (5) suggested that the serine hydroxyl, polarized by the aspartic carboxyl, might be transiently phosphorylated under the hydrolysis reaction. According to his analysis (5) of the β-actin structure (4), the geometry of the ATP-site would favor an in-line attack on the ATPγP by the serine hydroxyl. This model was also inspired by the geometric homology of actin to the ATPase domain of Hsc70, which places alcoholic and acidic side chains at similar positions (6).
KeywordsATPase Activity Actin Filament Motility Assay Myosin Binding Heat Shock Cognate Protein
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- 5.Myslik, J.C. (1992), The structure of actin in the crystalline profiling:actin complex. Thesis, Princeton UniversityGoogle Scholar