Apurinic endonuclease activity of yeast Apn2 protein

J Biol Chem. 2000 Jul 21;275(29):22427-34. doi: 10.1074/jbc.M002845200.


Abasic (apurinic/apyrimidinic; AP) sites are generated in vivo through spontaneous base loss and by enzymatic removal of bases damaged by alkylating agents and reactive oxygen species. In Saccharomyces cerevisiae, the APN1 and APN2 genes function in alternate pathways of AP site removal. Apn2-like proteins have been identified in other eukaryotes including humans, and these proteins form a distinct subfamily within the exonuclease III (ExoIII)/Ape1/Apn2 family of proteins. Apn2 and other members of this subfamily contain a carboxyl-terminal extension not present in the ExoIII/Ape1-like proteins. Here, we purify the Apn2 protein from yeast and show that it is a class II AP endonuclease. Deletion of the carboxyl terminus does not affect the AP endonuclease activity of the protein, but this protein is defective in the removal of AP sites in vivo. The carboxyl terminus may enable Apn2 to complex with other proteins, and such a multiprotein assembly may be necessary for the efficient recognition and cleavage of AP sites in vivo.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Carbon-Oxygen Lyases / genetics
  • Carbon-Oxygen Lyases / metabolism*
  • DNA-(Apurinic or Apyrimidinic Site) Lyase
  • Deoxyribonuclease IV (Phage T4-Induced)
  • Enzyme Activation
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism
  • Molecular Sequence Data
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Sequence Alignment
  • Sequence Deletion


  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • Deoxyribonuclease IV (Phage T4-Induced)
  • Carbon-Oxygen Lyases
  • APN2 protein, S cerevisiae
  • DNA-(Apurinic or Apyrimidinic Site) Lyase