Abstract:
DNA photolyases, members of the photolyase-cryptochrome family, are light-driven enzymes containing a flavin-adenine dinucleotide (FAD) cofactor. DNA photolyases undergo photoactivation and catalyze DNA repair reactions. In the photoactivation process, two light-triggered single-electron photoreduction steps convert the oxidized chromophore (FAD
ox), via the radical semiquinone state, to the reduced (hydroquinone) state. The photoactivated, FADH
- state of DNA photolyase becomes catalytically competent and promotes blue light-driven DNA repair of UV photo lesions, such as cyclobutane pyrimidine dimers (CPD). The kinetic mechanisms of DNA photolyases have been extensively studied by ultrafast spectroscopy. However, crystal structures have not been obtainable due to light-sensitivity of the enzyme and short lifetime of its reaction intermediates. The recent development of X-ray free electron laser (XFEL) facilities, in combination with serial femtosecond crystallography (SFX) techniques, has allowed for damage-free data collection of biological macromolecular structures. In addition, it is possible to perform time-resolved experiments (TR-SFX) at ultrashort intervals upon light activation. In this lecture I will present the progress of TR-SFX studies of the structural mechanisms of the photoactivation and DNA repair of a photolyase, at picoseconds to milliseconds, by an international team, with experiments performed in both SACLA, Japan and SwissFEL, Switzerland.
Reference:
“Serial crystallography captures dynamic control of sequential electron and proton transfer events in a flavoenzyme”, Manuel Maestre-Reyna, (36 others), Lars-Oliver Essen*, Yoshitaka Bessho*, Ming-Daw Tsai*, Nature Chemistry, 2022. DOI: 10.1038/s41557-022-00922-3. URL: https://www.nature.com/articles/s41557-022-00922-3