Reaction mechanisms of DNA photolyase.
DNA photolyase uses visible light and a fully reduced flavin cofactor FADH(-) to repair major UV-induced lesions in DNA, the cyclobutane pyrimidine dimers (CPDs). Electron transfer from photoexcited FADH(-) to CPD, splitting of the two intradimer bonds, and back electron transfer to the transiently formed flavin radical FADH° occur in overall 1ns. Whereas the kinetics of FADH° was resolved, the DNA-based intermediates escaped unambiguous detection yet. Another light reaction, named photoactivation, reduces catalytically inactive FADH° to FADH(-) without implication of DNA. It involves electron hopping along a chain of three tryptophan residues in 30ps, as elucidated in detail by transient absorption spectroscopy. The same triple tryptophan chain is found in cryptochrome blue-light photoreceptors and may be involved in their primary photoreaction.
Brettel
Klaus
K
CEA, IBITECS, Laboratoire de Photocatalyse et Biohydrogène, 91191 Gif-sur-Yvette, France. klaus.brettel@cea.fr
Byrdin
Martin
M
D000818:Animals; D055162:Biocatalysis; D004260:DNA Repair; D004255:Deoxyribodipyrimidine Photo-Lyase / Q000737:chemistry / Q000378:metabolism*; D004579:Electron Transport; D005415:Flavins / Q000378:metabolism; D006801:Humans; D055668:Photochemical Processes; D011740:Pyrimidine Dimers / Q000378:metabolism
D005415:Flavins; D011740:Pyrimidine Dimers; D004255:Deoxyribodipyrimidine Photo-Lyase