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Updated: Sep 9, 2025

Investigation of Protein Recruitment to DNA Lesions Using 405 Nm Laser Micro-irradiation
Published on: March 20, 2018
Infrared and ultraviolet spectroscopic characterization of a key intermediate during DNA repair by (6-4) photolyase
Daichi Yamada1, Ai Kadono1, Tatsumi Maeno1
1Department of Life Science, Graduate School of Science, University of Hyogo, Ako, Hyogo, Japan.
Abstract:
Ultraviolet (UV) irradiation of DNA causes genotoxic photolesions, such as carcinogenic pyrimidine(6-4)pyrimidone photoproducts ((6-4)PPs). In many organisms, (6-4)PPs are repaired by (6-4) photolyases, which contain a flavin chromophore and use blue light energy to initiate the catalytic reaction. Although (6-4)PP repair has been shown to require the input of two successive photons, details of the mechanism remain elusive. Here, we applied recently developed time-resolved UV and infrared (IR) spectroscopic techniques to capture a key intermediate that awaits the second photon in the repair reaction of Xenopus laevis (6-4) photolyase. The results indicate that the intermediate is formed within 500 μs following the initial absorption of a photon and contains a four-membered oxetane ring that bridges two adjacent pyrimidine bases. These findings shed light on the molecular basis of DNA repair involving two-photon activation.
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