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PDBsum entry 1njg
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Contents |
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* Residue conservation analysis
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References listed in PDB file
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Key reference
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Title
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Nucleotide-Induced conformational changes in an isolated escherichia coli DNA polymerase III clamp loader subunit.
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Authors
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M.Podobnik,
T.F.Weitze,
M.O'Donnell,
J.Kuriyan.
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Ref.
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Structure, 2003,
11,
253-263.
[DOI no: ]
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PubMed id
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Abstract
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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.
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Figure 8.
Figure 8. Schematic Diagram of Potential Rearrangement in
the Clamp Loader Complex upon Nucleotide BindingThis represents
a hypothetical sequence of events based on structural and
biochemical evidence of conformational changes presented here
and in [9]. Only three subunits of the g complex are shown for
clarity. Green: d'; red: g1; blue: g2. S1: sensor 1/switch 2
helix a7, containing the SRC motif; P: P loop; S2: sensor 2
helix a10. Close contacts between the subunits are marked by
yellow circles. ATP is drawn bound to the g1 subunit (brown
circles are for the base and sugar, and white are for the
phosphate groups). Arginine from the conserved SRC motif is
indicated on the S1 (sensor 1) helices.
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The above figure is
reprinted
by permission from Cell Press:
Structure
(2003,
11,
253-263)
copyright 2003.
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