Open Access3′-Phosphodiesterase and 3′→5′ Exonuclease Activities of Yeast Apn2 Protein and Requirement of These Activities for Repair of Oxidative DNA Damage
Author(s) -
Ildikó Unk,
Lajos Haracska,
Satya Prakash,
Louise Prakash
Publication year - 2001
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.21.5.1656-1661.2001
Subject(s) - biology , exonuclease , ap site , dna repair , dna damage , biochemistry , dna , dna polymerase , saccharomyces cerevisiae , ap endonuclease , microbiology and biotechnology , exonuclease iii , yeast , gene , escherichia coli
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.