Nucleotide-induced conformational changes in an isolated Escherichia coli DNA polymerase III clamp loader subunit.
Sliding clamps are loaded onto DNA by ATP-driven clamp loader complexes. The structure of the E. coli clamp loader in a nucleotide-free state has been determined previously. We now report crystal structures of a truncated form of the isolated gamma-ATPase subunit, gamma(1-243), of the E. coli clamp loader, in nucleotide-free and bound forms. The gamma subunit adopts a defined conformation when empty, in which the nucleotide binding site is blocked. The binding of either ATPgammaS or ADP, which are shown to bind with equal affinity to gamma(1-243), induces a change in the relative orientation of the two domains such that nucleotides can be accommodated. This change would break one of the gamma:gamma interfaces seen in the empty clamp loader complex, and may represent one step in the activation process.
Podobnik
Marjetka
M
Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
Weitze
Tanya F
TF
O'Donnell
Mike
M
Kuriyan
John
J
D000251:Adenosine Triphosphatases / Q000378:metabolism; D004247:DNA / Q000378:metabolism*; D004258:DNA Polymerase III / Q000378:metabolism*; D004926:Escherichia coli / Q000201:enzymology*; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D020027:Pyrococcus furiosus / Q000201:enzymology
D004247:DNA; D004258:DNA Polymerase III; D000251:Adenosine Triphosphatases