5'-Deoxyribose Phosphate Lyase Activity of Human DNA Polymerase &igr; in Vitro

DNA polymerase iota (pol ι) is one of several recently discovered DNA polymerases in mammalian cells whose function is unknown. We report here that human pol ι has an intrinsic 5′-deoxyribose phosphate (dRP) lyase activity. In reactions reconstituted with uracil-DNA glycosylase (UDG), apurinic/apyrimidinic (AP) endonuclease and DNA ligase I, pol ι can use its dRP lyase and polymerase activities to repair G•U and A•U pairs in DNA. These data and three distinct catalytic properties of pol ι implicate it in specialized forms of base excision repair (BER).