Insights into the Replisome from the Structure of a Ternary Complex of the DNA Polymerase III [alpha]-Subunit
- Yale
The crystal structure of the catalytic {alpha}-subunit of the DNA polymerase III (PolIII{alpha}) holoenzyme bound to primer-template DNA and an incoming deoxy-nucleoside 5{prime}-triphosphate has been determined at 4.6-{angstrom} resolution. The polymerase interacts with the sugar-phosphate backbone of the DNA across its minor groove, which is made possible by significant movements of the thumb, finger, and {beta}-binding domains relative to their orientations in the unliganded polymerase structure. Additionally, the DNA and incoming nucleotide are bound to the active site of PolIII{alpha} nearly identically as they are in their complex with DNA polymerase {beta}, thereby proving that the eubacterial replicating polymerase, but not the eukaryotic replicating polymerase, is homologous to DNA polymerase {beta}. Finally, superimposing a recent structure of the clamp bound to DNA on this PolIII{alpha} complex with DNA places a loop of the {beta}-binding domain into the appropriate clamp cleft and supports a mechanism of polymerase switching.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1007074
- Journal Information:
- J. Mol. Biol., Vol. 382, Issue (4) ; 10, 2008; ISSN 0022-2836
- Country of Publication:
- United States
- Language:
- ENGLISH
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