Stimulation of 3'-->5' exonuclease and 3'-phosphodiesterase activities of yeast apn2 by proliferating cell nuclear antigen

Mol Cell Biol. 2002 Sep;22(18):6480-6. doi: 10.1128/MCB.22.18.6480-6486.2002.


The Apn2 protein of Saccharomyces cerevisiae contains 3'-->5' exonuclease and 3'-phosphodiesterase activities, and these activities function in the repair of DNA strand breaks that have 3'-damaged termini and which are formed in DNA by the action of oxygen-free radicals. Apn2 also has an AP endonuclease activity and functions in the removal of abasic sites from DNA. Here, we provide evidence for the physical and functional interaction of Apn2 with proliferating cell nuclear antigen (PCNA). As indicated by gel filtration and two-hybrid studies, Apn2 interacts with PCNA both in vitro and in vivo and mutations in the consensus PCNA-binding motif of Apn2 abolish this interaction. Importantly, PCNA stimulates the 3'-->5' exonuclease and 3'-phosphodiesterase activities of Apn2. We have examined the involvement of the interdomain connector loop (IDCL) and of the carboxy-terminal domain of PCNA in Apn2 binding and found that Apn2 binds PCNA via distinct domains dependent upon whether the binding is in the absence or presence of DNA. In the absence of DNA, Apn2 binds PCNA through its IDCL domain, whereas in the presence of DNA, when PCNA has been loaded onto the template-primer junction by replication factor C, the C-terminal domain of PCNA mediates the binding.

Publication types

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

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Carbon-Oxygen Lyases / genetics
  • Carbon-Oxygen Lyases / physiology*
  • Chromatography, Gel
  • DNA / metabolism
  • DNA Damage
  • DNA Repair
  • DNA-(Apurinic or Apyrimidinic Site) Lyase
  • Dose-Response Relationship, Drug
  • Hydrolysis
  • Molecular Sequence Data
  • Mutation
  • Oxygen / metabolism
  • Plasmids / metabolism
  • Proliferating Cell Nuclear Antigen / genetics
  • Proliferating Cell Nuclear Antigen / metabolism*
  • Protein Binding
  • Protein Structure, Tertiary
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae Proteins*
  • Two-Hybrid System Techniques


  • Proliferating Cell Nuclear Antigen
  • Saccharomyces cerevisiae Proteins
  • DNA
  • Carbon-Oxygen Lyases
  • APN2 protein, S cerevisiae
  • DNA-(Apurinic or Apyrimidinic Site) Lyase
  • Oxygen