The proofreading mechanism of the human leading strand DNA polymerase ε holoenzyme.

ABSTRACT: The eukaryotic leading strand DNA polymerase epsilon is a dual function enzyme with a proofreading exonuclease site located 40 angstroms from the DNA synthesizing polymerase site. Errors in Pol epsilon proofreading can cause various mutations, including C to G transversions, the most prevalent mutation in cancers and genetic diseases. Pol epsilon interacts with all three subunits of the PCNA ring to assemble a functional holoenzyme. Despite previous studies on proofreading of several polymerases, how Pol epsilon, or any Pol complexed with its sliding clamp proofreads a mismatch generated in situ has been unknown. We show here by cryo-EM that a template/primer DNA substrate with a pre-existing mismatch cannot enter the exo site of Pol epsilon/PCNA holoenzyme, but a mismatch generated in the

SUBMITTER: Wang F 

PROVIDER: S-EPMC12027367 | biostudies-literature | 2025 Apr

REPOSITORIES: biostudies-literature