Identification and characterization of novel enzymes involved in base excision repair for oxidative base damage in DNA

Abstract

Reactive oxygen species cause a wide variety of oxidative modifications to purines and pyrimidines in DNA. Bacteria and eukaryotes have evolved base excision repair mechanisms for oxidative base damage in DNA. E. coli has three kinds of DNA glycosylase, MutM,Nth and Nei, that recognize and remove oxidatively damaged bases from DNA. These DNA glycosylases are able to recognize and remove 5-formyluracil and 5-hydroxymethyluracil in DNA. However, several evidence showed that there are residual activities in crude extract from E. coli mutM nth nei triple mutant. In this study, we identified the abilities of novel enzyme(s) to recognize double-stranded oligonucleotides containing 5-foU. We are currently investigating the nature of the enzyme(s).