Poster abstracts

Poster number 54 submitted by Austin Raper

Dynamic damage searching and substrate processing by hOGG1 and its coordination with APE1 during base excision repair

Austin T. Raper (Ohio State Biochemistry Program, Department of Chemistry and Biochemistry, The Ohio State University), Brian A. Maxwell (Ohio State Biophysics Graduate Program), Zucai Suo (Ohio State Biochemistry Program, Ohio State Biophysics Graduate Program, Department of Chemistry and Biochemistry, The Ohio State University)

Abstract:
Base excision repair (BER) is the primary pathway by which our cells resolve single base damage. One particularly common example of single base damage is 8-oxo-7,8-dihydro-2ʹ-deoxoguanine (8-oxo-dG). The ability of 8-oxo-dG to trigger mutation and its high frequency of occurrence warrant its rapid and efficient repair. While the elegant coordination of BER enzymes is implicated in the repair of base lesions, it remains unclear how this coordination is executed in resolving 8-oxo-dG damage. In addition, the mechanism by which our cells limit cytotoxic BER intermediates from eliciting further DNA damage is unclear. Our single-molecule Förster Resonance Energy Transfer (smFRET) technique has provided a means to characterize the enzymes important in the repair of 8-oxo-dG and the potential coordination between them. We specifically explore the interaction of two enzymes involved in consecutive steps in the pathway, human 8-oxoguanine glycosylase (hOGG1) and human AP endonuclease (APE1). In addition to providing valuable insight into the mechanism of hOGG1, our work strongly supports the existence of a ternary complex between hOGG1, APE1, and the DNA substrate. As such, our results imply a mechanism in which APE1 actively displaces hOGG1 from its abasic site product. Furthermore, this work supports the idea that APE1 serves as the connection between the damage specific and general stages of BER by utilizing specific protein-protein interactions with the glycosylase.

Keywords: Single-molecule Frster Resonance Energy Transfer, Base Excision Repair, oxidative damage