Apn1 Background Information
DNA nucleases catalyze the cleavage of phosphodiester bonds. These enzymes play crucial roles in various DNA repair processes, which involve DNA replication, base excision repair, nucleotide excision repair, mismatch repair, and double strand break repair (1). In Saccharomyces cerevisiae, Apn1 functions as the major apurinic/apyrimidinic endonuclease and 3’-repair DNA diesterase to repair DNA damaged by oxygen radicals and alkylating agents (2-4). Specifically, Apn1 removes abasic sites, which are inhibitory to synthesis by DNA polymerases (2-4). Apn1, the yeast homolog of Escherichia coli endonuclease IV, shows overlapping function with the yeast Apn2, Rad1/Rad10 and Mus81/Mms4 proteins (2,5,6). Apn1 mutants display hypersensitivity to both oxidative and alkylating agents, and accumulate unrepaired damages in chromosomal DNA (2). The yeast Apn1 gene maps to chromosome XI, and expresses a protein that localizes to both the nucleus and mitochondria, where it may participate in repair of mitochondrial DNA (7-9).
