Computational and experimental investigation of DNA repair protein photolyase interactions with low molecular weight drugs.

This paper reports the previously unknown interactions between eight low molecular weight commercially available drugs (130-800 Da) and DNA repair protein photolyase using computational docking simulations and surface plasmon resonance (SPR) experiments. Theoretical dissociation constants, K(d), obtained from molecular docking simulations were compared with the values found from SPR experiments. Among the eight drugs analyzed, computational and experimental values showed similar binding affinities between selected drug and protein pairs. We found no significant differences in binding interactions between pure and commercial forms of the drug lornoxicam and DNA photolyase. Among the eight drugs studied, prednisone, desloratadine, and azelastine exhibited the highest binding affinity (K(d) = 1.65, 2.05, and 8.47 µM, respectively) toward DNA photolyase. Results obtained in this study are promising for use in the prediction of unknown interactions of common drugs with specific proteins such as human clock protein cryptochrome.

Investigation of real-time photorepair activity on DNA via surface plasmon resonance.

The cyclobutane pyrimidine dimer (CPD) and 6-4 lesion formations along with the specific breaks on strands are the most common type of DNA damage caused by Ultraviolet light (UV) irradiation. CPD photolyase I and II construct two subfamilies of flavoproteins, which have recognition and repair capabilities of CPD sites on both single stranded (ssDNA) and double stranded DNA (dsDNA) with the aid of blue light energy. The other types of flavoprotein family consist of cryptochromes (CRY) that act as photoreceptors in plants, or circadian rhythm regulators in animals. Recent findings showed that a specific type of Cryptochrome-Drosophila, Arabidopsis, Synechocystis, Human (CRY-DASH) has photorepair activity on ssDNA. In this work, real-time interactions between CRY-DASH and ss/dsDNA as well as the interactions between Vibrio cholerae photolyase (VcPHR) and ss/dsDNA were investigated using Surface Plasmon Resonance (SPR). The interactions were then characterized and compared in order to investigate the effect of different types of flavoprotein on UV damaged ss/dsDNA. SPR results confirm the specific binding of VcPHR and CRY-DASH with UV treated DNA. This study is the first instance to quantify the interactions of UV treated and untreated DNA with flavoproteins.