(568p) Characterization of UV-Damage and Repair with Cry-Dash in DNA Using AFM and SPR

The cyclobutaneprimidine dimer (CPD) and 6-4 lesion formations in DNA structure along with the specific breaks on strands are the most common type of DNA damage caused by UV irradiation. Specific to UV-damaged DNA, CPD photolyase I and II construct 2 subfamilies of flavoproteins, and have recognition and repair abilities of CPD sites on both single stranded (ssDNA) and double stranded (dsDNA) DNA using blue light energy. It has been recently found that a specific type of cryptochrome, CRY-DASH, has photorepair activity on ssDNA. In this study, we exploit AFM imaging of individual ssDNA molecules alone and in complex with DNA repair enzyme CRY-dASH for the first time, to quantify DNA damage and repair at a single-molecule level. SPR is used to determine the binding kinetics of CRY-DASH onto ssDNA. SPR confirms the interaction of CRY-DASH with the surface bound and UV treated or untreated ssDNA. This study may be significant for the characterization of ssDNA damage and repair of lesions in the DNA structure using AFM and SPR.