Targeted deletion of mNth1 reveals a novel DNA repair enzyme activity.

DNA N-glycosylase/AP (apurinic/apyrimidinic) lyase enzymes of the endonuclease III family (nth in Escherichia coli and Nth1 in mammalian organisms) initiate DNA base excision repair of oxidized ring saturated pyrimidine residues. We generated a null mouse (mNth1(-/-)) by gene targeting. After almost 2 years, such mice exhibited no overt abnormalities.