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

ABSTRACT: The eukaryotic leading-strand DNA polymerase ε (Polε) is a dual-function enzyme with a proofreading 3'-5' exonuclease (exo) site located 40 Å from the DNA synthesizing pol site. Errors in Polε proofreading can cause various mutations, including C-to-G transversions, the most prevalent mutation in cancers and genetic diseases. Polε interacts with all three subunits of the PCNA ring to assemble a functional holoenzyme. Despite previous studies on proofreading of several Pol's, how Polε-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 preexisting mismatch cannot enter the exo site of Polε-PCNA holoenzyme, but a mismatch generated in situ in the pol</

SUBMITTER: Wang F 

PROVIDER: S-EPMC12146725 | biostudies-literature | 2025 Jun

REPOSITORIES: biostudies-literature