Characterization of UV-Damage and Repair with Cry-Dash in DNA Using AFM and SPR

Wednesday, November 10, 2010
Hall 1 (Salt Palace Convention Center)
Enis Demir1, H. Enis Karahan2, Hande Asimgil2, A. Levent Demirel3, Halil Kavakli1 and Seda Kizilel1, (1)Chemical and Biological Engineering, Koç University, Istanbul, Turkey, (2)Materials Science and Engineering, Koç University, Istanbul, Turkey, (3)Chemistry Department, Koç University, Istanbul, Turkey

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.

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