PMID:20188667
| Citation |
Downey, CD and McHenry, CS (2010) Chaperoning of a replicative polymerase onto a newly assembled DNA-bound sliding clamp by the clamp loader. Mol. Cell 37:481-91 |
|---|---|
| Abstract |
Cellular replicases contain multiprotein ATPases that load sliding clamp processivity factors onto DNA. We reveal an additional role for the DnaX clamp loader: chaperoning of the replicative polymerase onto a clamp newly bound to DNA. We show that chaperoning confers distinct advantages, including marked acceleration of initiation complex formation. We reveal a requirement for the tau form of DnaX complex to relieve inhibition by single-stranded DNA binding protein during initiation complex formation. We propose that, after loading beta(2), DnaX complex preserves an SSB-free segment of DNA immediately downstream of the primer terminus and chaperones Pol III into that position, preventing competition by SSB. The C-terminal tail of SSB stimulates reactions catalyzed by tau-containing DnaX complexes through a contact distinct from the contact involving the chi subunit. Chaperoning of Pol III by the DnaX complex provides a molecular explanation for how initiation complexes form when supported by the nonhydrolyzed analog ATPgammaS. |
| Links |
PubMed PMC2830912 Online version:10.1016/j.molcel.2010.01.013 |
| Keywords |
Adenosine Triphosphate/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; DNA/genetics; DNA/metabolism; DNA Polymerase III/genetics; DNA Polymerase III/metabolism; DNA Replication; DNA-Binding Proteins/metabolism; Escherichia coli/enzymology; Molecular Chaperones/metabolism; Protein Binding; Protein Subunits/genetics; Protein Subunits/metabolism |
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