Role of polymerase β in complementing aprataxin deficiency during abasic-site base excision repair

DNA polymerase β (pol β) lyase removal of 5'-deoxyribose phosphate (5'-dRP) from base excision repair (BER) intermediates is critical in mammalian BER involving the abasic site. We found that pol β also removes 5'-adenylated dRP from BER intermediates after abortive ligation. The crystal structure of a human pol β-DNA complex showed the 5'-AMP-dRP group positioned in the lyase active site. Pol β expression rescued methyl methanesulfonate sensitivity in aprataxin (hnt3)- and FEN1 (rad27)-deficient yeast.