Dongping Zhong, the Robert Smith Associate Professor of Physics and associate professor in the departments of chemistry and biochemistry, has witnessed how the enzyme, called photolyase, works at the atomic level to repair sun-damaged DNA.

Ultraviolet (UV) light damages skin by causing chemical bonds to form in the wrong places along the DNA molecules in our cells. Scientists have linked chronic sun damage to DNA mutations that lead to diseases such as skin cancer.Exactly how the photolyase enzymes repairs chronic sun damage has remained a mystery until now.

Professor Zhong and his colleagues synthesized DNA in a lab and exposed it to ultraviolet light, producing damage similar to that of sunburn, then added photolyase enzymes. Using ultrafast light pulses, they took a series of “snapshots” to reveal how the enzyme repaired the DNA at the atomic level. Their study has revealed that photolyase breaks up those errant bonds in just the right spots to cause the atoms in the DNA to move back into their original positions. The bonds are then arranged in such a way that the electron and proton are automatically ejected out of the DNA helix and back into the photolyase, presumably so it could start the cycle over again and go on to heal other sites.

Normal sunscreen lotions convert UV light to heat, or reflect it away from our skin. A sunscreen containing photolyase could potentially heal some of the damage from UV rays that get through. Now that researchers know the mechanism by which photolyase works, the discovery holds promise for future sunburn remedies and skin cancer prevention.

Zhong’s coauthors on the paper include postdoctoral researchers Jiang Li, Xunmin Guo, and Lijuan Wang, and doctoral students Zheyun Liu and Chuang Tan, all of Ohio State; and Aziz Sancar, MD, of the University of North Carolina, Chapel Hill School of Medicine.