Bifurcating electron-transfer pathways in DNA photolyases determine the repair quantum yield

• DOI: 10.1126/science.aah6071
• Publication Date: 2016-10-13T18:03:01Z
• Authors: Meng Zhang; Lijuan Wang; Shi Shu; Aziz Sancar; Dongping Zhong
• Keywords: Photolyase; Pyrimidine dimer; Quantum yield

Photolyase is a blue-light-activated enzyme that repairs ultraviolet-induced DNA damage occurs in the form of cyclobutane pyrimidine dimers (CPDs) and pyrimidine-pyrimidone (6-4) photoproducts. Previous studies on microbial photolyases have revealed an electron-tunneling pathway critical for repair mechanism. In this study, we used femtosecond spectroscopy to deconvolute seven electron-transfer reactions 10 elementary steps all classes CPD photolyases. We report unified through conserved structural configuration bifurcates favor direct tunneling prokaryotes two-step hopping mechanism eukaryotes. Both bifurcation routes are operative, but their relative contributions, dictated by reduction potentials flavin cofactor substrate, determine overall quantum yield repair.