DNA repair and DNA triplet repeat expansion: the impact of abasic lesions on triplet repeat DNA energetics.

ABSTRACT: Enhanced levels of DNA triplet expansion are observed when base excision repair (BER) of oxidative DNA base damage (e.g., 8-oxo-dG) occurs at or near CAG repeat sequences. This observation suggests an interplay between processing mechanisms required for DNA repair and expansion pathways that yield genotypes associated with many neurological/developmental disorders. It has been proposed that DNA expansion involves the transient formation within the triplet repeat domains of non-native slipped DNA structures that are incorrectly processed by the BER machinery of repair during DNA synthesis. We show here that replacement within a triplet repeat bulge loop domain of a guanosine residue by an abasic site, the universal BER intermediate, increases the population of slipped/looped DNA structures

SUBMITTER: Volker J 

PROVIDER: S-EPMC2705181 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature