Identification of a Mammalian 5-Formyluracil-DNA Glycosylase and its Substrate Recognition Mechanism

Abstract

Oxidative DNA base lesions produced by reactive oxygen species exert genotoxic and cytotoxic effects on living organisms. 5-Formyluracil (fU) is a major oxidative thymine lesion and induces transition mutations if not repaired. In the previous study, we partially purified and characterized rat fU-DNA glycosylase (FDG). The analysis of the FDG activity to various base lesions suggested that FDG was a rat homologue of SMUG1. In this study, we have performed immunological analysis of FDG using hSMUG1 antibodies. The FDG fraction from rat liver exhibited a positive Western band with a molecular mass of 30 kDa. The fU-releasing activity in rat and human cell free extracts were effectively neutralized by the antibodies. Futhermore the antibodies also neutralized the activities for 5-hydroxyuracil and 5-hydroxymethyluracil but not for thymine glycol in the cell free extracts. These data confirm that mammalian FDG is SMUG1. We are currently studying the substrate recognition mechanism of hSMUG1. [J Radiat Res 44:408 (2003)]