title: Nucleotide-induced conformational changes in an isolated Escherichia coli DNA polymerase III clamp loader subunit.
abstract: 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.
authors.affiliation: Department of Molecular and Cell Biology, Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
authors.forename: Marjetka
authors.initials: M
authors.lastname: Podobnik
authors.forename: Tanya F
authors.initials: TF
authors.lastname: Weitze
authors.forename: Mike
authors.initials: M
authors.lastname: O'Donnell
authors.forename: John
authors.initials: J
authors.lastname: Kuriyan
mesh_terms: 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
chemical_list: D004247:DNA; D004258:DNA Polymerase III; D000251:Adenosine Triphosphatases