抄録
Ionizing radiation and reactive oxygen species produce various types of DNA damage in living cells. Most of oxidative DNA damage are primarily repaired by base excision repair (BER) system. DNA glycosylases excise damaged bases, releasing AP sites in the DNA. Then AP endonucleases or AP lyases cleave DNA at the AP site, followed by repair synthesis and rejoining by DNA polymerases and DNA ligase. Most of all species so far examined have BER system. Therefore, BER plays an important role in maintenance of genome integrity. Endonuclease III (Nth) is a bifunctional glycosylase which excises oxidized pirimidines such as thymine glycol, and incises the DNA at the resulting AP site. DNA glycosylases are conserved in many organisms, indicating that this enzyme plays a critical role in removing oxidative damage from DNA. In this study, we sub-cloned C. elegans nth homolog gene. Neither OGG1 nor Nei homolog has been identified in C. elegans for oxdative base damage. It is likely that Nth homolog is a major glycosylase for 8-oxoguanine as well as thymine glycol in C. elegans.
