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Updated: Jun 18, 2026

Hybrid Ensemble and Single-molecule Assay to Image the Motion of Fully Reconstituted CMG
Published on: July 26, 2024
Structural determinant for switching between the polymerase and exonuclease modes in the PCNA-replicative DNA
Hirokazu Nishida1, Kouta Mayanagi, Shinichi Kiyonari
1Central Research Laboratory, Hitachi Ltd., 1-280 Higashi-koigakubo, Kokubunji, Tokyo 185-8601, Japan.
Abstract:
Proliferating cell nuclear antigen (PCNA) is responsible for the processivity of DNA polymerase. We determined the crystal structure of Pyrococcus furiosus DNA polymerase (PfuPol) complexed with the cognate monomeric PCNA, which allowed us to construct a convincing model of the polymerase-PCNA ring interaction, with unprecedented configurations of the two molecules. Electron microscopic analyses indicated that this complex structure exists in solution. Our structural study revealed that an interaction occurs between a stretched loop of PCNA and the PfuPol Thumb domain, in addition to the authentic PCNA-polymerase recognition site (PIP box). Comparisons of the present structure with the previously reported structures of polymerases complexed with DNA, suggested that the second interaction plays a crucial role in switching between the polymerase and exonuclease modes, by inducing a PCNA-polymerase complex configuration that favors synthesis over editing. This putative mechanism for fidelity control of replicative DNA polymerases is supported by experiments, in which mutations at the second interaction site caused enhancements in the exonuclease activity in the presence of PCNA.
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