Ordered ATP Hydrolysis in the γ Complex Clamp Loader AAA+ Machine

摘要: The gamma complex couples ATP hydrolysis to the loading of beta sliding clamps onto DNA for processive replication. structure shows that clamp loader subunits are arranged as a circular heteropentamer. three motor bind ATP, delta wrench opens ring, and delta' stator modulates delta-beta interaction. Neither nor ATP. This report demonstrates contributes catalytic arginine bound adjacent gamma(1) subunit. Thus, function trimer. Mutation 169 gamma, which removes arginines from only gamma(2) gamma(3) sites, abolishes ATPase activity even though site 1 is intact all sites filled. result implies molecules occurs in particular order, reverse binding, where not hydrolyzed until 2 and/or 3 hydrolyzed. Implications these results loaders other systems discussed.