Enhancement of human DNA polymerase η activity and fidelity is dependent upon a bipartite interaction with the Werner syndrome protein

J Biol Chem. 2012 Dec 7;287(50):42312-23. doi: 10.1074/jbc.M112.410332. Epub 2012 Oct 8.


We have investigated the interaction between human DNA polymerase η (hpol η) and the Werner syndrome protein (WRN). Functional assays revealed that the WRN exonuclease and RecQ C-terminal (RQC) domains are necessary for full stimulation of hpol η-catalyzed formation of correct base pairs. We find that WRN does not stimulate hpol η-catalyzed formation of mispairs. Moreover, the exonuclease activity of WRN prevents stable mispair formation by hpol η. These results are consistent with a proofreading activity for WRN during single-nucleotide additions. ATP hydrolysis by WRN appears to attenuate stimulation of hpol η. Pre-steady-state kinetic results show that k(pol) is increased 4-fold by WRN. Finally, pulldown assays reveal a bipartite physical interaction between hpol η and WRN that is mediated by the exonuclease and RQC domains. Taken together, these results are consistent with alteration of the rate-limiting step in polymerase catalysis by direct protein-protein interactions between WRN and hpol η. In summary, WRN improves the efficiency and fidelity of hpol η to promote more effective replication of DNA.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adenosine Triphosphate / chemistry*
  • Adenosine Triphosphate / genetics
  • Adenosine Triphosphate / metabolism
  • Catalysis
  • DNA / biosynthesis*
  • DNA / chemistry
  • DNA / genetics
  • DNA Replication / physiology*
  • DNA-Directed DNA Polymerase / chemistry*
  • DNA-Directed DNA Polymerase / genetics
  • DNA-Directed DNA Polymerase / metabolism
  • Exodeoxyribonucleases / chemistry*
  • Exodeoxyribonucleases / genetics
  • Exodeoxyribonucleases / metabolism
  • RecQ Helicases / chemistry*
  • RecQ Helicases / genetics
  • RecQ Helicases / metabolism
  • Werner Syndrome Helicase


  • Adenosine Triphosphate
  • DNA
  • DNA-Directed DNA Polymerase
  • POLN protein, human
  • Exodeoxyribonucleases
  • RecQ Helicases
  • WRN protein, human
  • Werner Syndrome Helicase