1njf: Difference between revisions

[[Image:1njf.gif|left|200px]]

'''Nucleotide bound form of an isolated E. coli clamp loader gamma 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.

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 02:36:21 2008''