3'-phosphodiesterase and 3'-->5' exonuclease activities of yeast Apn2 protein and requirement of these activities for repair of oxidative DNA damage

Mol Cell Biol. 2001 Mar;21(5):1656-61. doi: 10.1128/MCB.21.5.1656-1661.2001.


In Saccharomyces cerevisiae, the AP endonucleases encoded by the APN1 and APN2 genes provide alternate pathways for the removal of abasic sites. Oxidative DNA-damaging agents, such as H(2)O(2), produce DNA strand breaks which contain 3'-phosphate or 3'-phosphoglycolate termini. Such 3' termini are inhibitory to synthesis by DNA polymerases. Here, we show that purified yeast Apn2 protein contains 3'-phosphodiesterase and 3'-->5' exonuclease activities, and mutation of the active-site residue Glu59 to Ala in Apn2 inactivates both these activities. Consistent with these biochemical observations, genetic studies indicate the involvement of APN2 in the repair of H(2)O(2)-induced DNA damage in a pathway alternate to APN1, and the Ala59 mutation inactivates this function of Apn2. From these results, we conclude that the ability of Apn2 to remove 3'-end groups from DNA is paramount for the repair of strand breaks arising from the reaction of DNA with reactive oxygen species.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alanine / chemistry
  • Base Sequence
  • Binding Sites
  • Carbon-Oxygen Lyases / chemistry
  • Carbon-Oxygen Lyases / physiology*
  • DNA Damage*
  • DNA Repair*
  • DNA-(Apurinic or Apyrimidinic Site) Lyase
  • Deoxyribonuclease IV (Phage T4-Induced)
  • Dose-Response Relationship, Drug
  • Exodeoxyribonuclease V
  • Exodeoxyribonucleases / metabolism*
  • Glutamic Acid / chemistry
  • Glutathione Transferase / metabolism
  • Hydrogen Peroxide / pharmacology
  • Hydrogen-Ion Concentration
  • Molecular Sequence Data
  • Mutation
  • Nucleotidases / metabolism*
  • Oxygen / metabolism*
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae Proteins*
  • Substrate Specificity
  • Time Factors


  • Saccharomyces cerevisiae Proteins
  • Glutamic Acid
  • Hydrogen Peroxide
  • Glutathione Transferase
  • Exodeoxyribonucleases
  • Exodeoxyribonuclease V
  • Deoxyribonuclease IV (Phage T4-Induced)
  • Nucleotidases
  • 3'-nucleotidase
  • Carbon-Oxygen Lyases
  • APN2 protein, S cerevisiae
  • DNA-(Apurinic or Apyrimidinic Site) Lyase
  • Alanine
  • Oxygen