Mechanism of Loading the Escherichia coli DNA Polymerase III Sliding Clamp II. UNCOUPLING THE β AND DNA BINDING ACTIVITIES OF THE γ COMPLEX

摘要: Abstract Sliding clamps tether DNA polymerases to increase the processivity of synthesis. The Escherichia coli γ complex loads β sliding clamp onto in an ATP-dependent reaction which ATP binding and hydrolysis modulate affinity for DNA. This is second two reports (Williams, C. R., Snyder, A. K., Kuzmic, P., O'Donnell, M., Bloom, L. B. (2004) J. Biol. Chem. 279, 4376–4385) addressing question how regulate specific interactions with β. Mutations were made Arg residue a conserved SRC motif δ′ subunits that interacts site neighboring subunit. Mutation subunit reduced activity, whereas mutation activity complex. containing gave pre-steady-state burst hydrolysis, but at rate amplitude relative wild-type A was not observed mutations, consistent this differential effects these mutations suggest γ1 may be coupled conformational changes largely β, γ2 and/or γ3 have major role Additionally, results show “arginine fingers” play structural facilitating formation conformation has high