Interaction of proliferating cell nuclear antigen with PMS2 is required for MutLα activation and function in mismatch repair

Proc Natl Acad Sci U S A. 2017 May 9;114(19):4930-4935. doi: 10.1073/pnas.1702561114. Epub 2017 Apr 24.


Eukaryotic MutLα (mammalian MLH1-PMS2 heterodimer; MLH1-PMS1 in yeast) functions in early steps of mismatch repair as a latent endonuclease that requires a mismatch, MutSα/β, and DNA-loaded proliferating cell nuclear antigen (PCNA) for activation. We show here that human PCNA and MutLα interact specifically but weakly in solution to form a complex of approximately 1:1 stoichiometry that depends on PCNA interaction with the C-terminal endonuclease domain of the MutLα PMS2 subunit. Amino acid substitution mutations within a PMS2 C-terminal 721QRLIAP motif attenuate or abolish human MutLα interaction with PCNA, as well as PCNA-dependent activation of MutLα endonuclease, PCNA- and DNA-dependent activation of MutLα ATPase, and MutLα function in in vitro mismatch repair. Amino acid substitution mutations within the corresponding yeast PMS1 motif (723QKLIIP) reduce or abolish mismatch repair in vivo. Coupling of a weak allele within this motif (723AKLIIP) with an exo1Δ null mutation, which individually confer only weak mutator phenotypes, inactivates mismatch repair in the yeast cell.

Keywords: DNA repair; MutLalpha; endonuclease; mismatch repair; proliferating cell nuclear antigen.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • DNA Mismatch Repair*
  • Humans
  • Mismatch Repair Endonuclease PMS2* / chemistry
  • Mismatch Repair Endonuclease PMS2* / genetics
  • Mismatch Repair Endonuclease PMS2* / metabolism
  • MutL Proteins* / chemistry
  • MutL Proteins* / genetics
  • MutL Proteins* / metabolism
  • Proliferating Cell Nuclear Antigen* / chemistry
  • Proliferating Cell Nuclear Antigen* / genetics
  • Proliferating Cell Nuclear Antigen* / metabolism
  • Saccharomyces cerevisiae Proteins* / chemistry
  • Saccharomyces cerevisiae Proteins* / genetics
  • Saccharomyces cerevisiae Proteins* / metabolism
  • Saccharomyces cerevisiae* / chemistry
  • Saccharomyces cerevisiae* / genetics
  • Saccharomyces cerevisiae* / metabolism


  • MutLalpha protein, human
  • Proliferating Cell Nuclear Antigen
  • Saccharomyces cerevisiae Proteins
  • PMS2 protein, human
  • Mismatch Repair Endonuclease PMS2
  • MutL Proteins