Nucleotide-Induced Conformational Changes in an Isolated Escherichia coli DNA Polymerase III Clamp Loader Subunit

摘要: Sliding clamps are loaded onto DNA by ATP-driven clamp loader complexes. The structure of the E. coli in a nucleotide-free state has been determined previously. We now report crystal structures truncated form isolated gamma-ATPase subunit, gamma(1-243), loader, and bound forms. gamma subunit adopts defined conformation when empty, which nucleotide binding site is blocked. either ATPgammaS or ADP, shown to bind with equal affinity induces change relative orientation two domains such that nucleotides can be accommodated. This would break one gamma:gamma interfaces seen empty complex, may represent step activation process.