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-Structure paper
Title | Structure of eukaryotic DNA polymerase δ bound to the PCNA clamp while encircling DNA. |
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Journal, issue, pages | Proc Natl Acad Sci U S A, Vol. 117, Issue 48, Page 30344-30353, Year 2020 |
Publish date | Dec 1, 2020 |
Authors | Fengwei Zheng / Roxana E Georgescu / Huilin Li / Michael E O'Donnell / |
PubMed Abstract | The DNA polymerase (Pol) δ of (S.c.) is composed of the catalytic subunit Pol3 along with two regulatory subunits, Pol31 and Pol32. Pol δ binds to proliferating cell nuclear antigen (PCNA) and ...The DNA polymerase (Pol) δ of (S.c.) is composed of the catalytic subunit Pol3 along with two regulatory subunits, Pol31 and Pol32. Pol δ binds to proliferating cell nuclear antigen (PCNA) and functions in genome replication, repair, and recombination. Unique among DNA polymerases, the Pol3 catalytic subunit contains a 4Fe-4S cluster that may sense the cellular redox state. Here we report the 3.2-Å cryo-EM structure of S.c. Pol δ in complex with primed DNA, an incoming ddTTP, and the PCNA clamp. Unexpectedly, Pol δ binds only one subunit of the PCNA trimer. This singular yet extensive interaction holds DNA such that the 2-nm-wide DNA threads through the center of the 3-nm interior channel of the clamp without directly contacting the protein. Thus, a water-mediated clamp and DNA interface enables the PCNA clamp to "waterskate" along the duplex with minimum drag. Pol31 and Pol32 are positioned off to the side of the catalytic Pol3-PCNA-DNA axis. We show here that Pol31-Pol32 binds single-stranded DNA that we propose underlies polymerase recycling during lagging strand synthesis, in analogy to replicase. Interestingly, the 4Fe-4S cluster in the C-terminal CysB domain of Pol3 forms the central interface to Pol31-Pol32, and this strategic location may explain the regulation of the oxidation state on Pol δ activity, possibly useful during cellular oxidative stress. Importantly, human cancer and other disease mutations map to nearly every domain of Pol3, suggesting that all aspects of Pol δ replication are important to human health and disease. |
External links | Proc Natl Acad Sci U S A / PubMed:33203675 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.2 Å |
Structure data | EMDB-22803: Cryo-EM 3D map of the Saccharomyces cerevisiae replicative polymerase delta in complex with a primer/template and the PCNA clamp |
Chemicals | ChemComp-MG: ChemComp-SF4: ChemComp-D3T: ChemComp-ZN: |
Source |
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Keywords | REPLICATION / Polymerase delta / PCNA / primed DNA / complex |