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

ABSTRACT: Photolyase is a blue-light-activated enzyme that repairs ultraviolet-induced DNA damage that 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 that is critical for the repair mechanism. In this study, we used femtosecond spectroscopy to deconvolute seven electron-transfer reactions in 10 elementary steps in all classes of CPD photolyases. We report a unified electron-transfer pathway through a conserved structural configuration that bifurcates to favor direct tunneling in prokaryotes and a two-step hopping mechanism in eukaryotes. Both bifurcation routes are operative, but their relative contributions, dictated by the reduction potentials of the flavin cofactor and the substrate, determine the overall quantum yield of repair.

SUBMITTER: Zhang M

PROVIDER: S-EPMC7227132 | biostudies-literature | 2016 Oct

REPOSITORIES: biostudies-literature

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

Zhang Meng M Wang Lijuan L Shu Shi S Sancar Aziz A Zhong Dongping D

Science (New York, N.Y.) 20161001 6309

Photolyase is a blue-light-activated enzyme that repairs ultraviolet-induced DNA damage that 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 that is critical for the repair mechanism. In this study, we used femtosecond spectroscopy to deconvolute seven electron-transfer reactions in 10 elementary steps in all classes of CPD photolyases. We report a unifi ...[more]

PMID: 27738168

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Photoselected electron transfer pathways in DNA photolyase.

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