Imura, TomokiTomokiImuraHosokawa, YuheiYuheiHosokawaYang, Kai-ChunKai-ChunYangBan, YukiYukiBanShih, Hsuan-YuHsuan-YuShihYamamoto, JunpeiJunpeiYamamotoMaestre-Reyna, ManuelManuelMaestre-Reyna2025-10-272025-10-272025-07-14https://scholars.lib.ntu.edu.tw/handle/123456789/733057Co-crystal structures of a base-excision DNA-repair enzyme (human 8-oxo-guanine DNA glycosylase; hOgg1) in complex with a photocaged 8-oxoguanine DNA lesion were determined before and after uncaging via illumination at 2.81 and 2.48 Å resolution, respectively. The structures were carefully reassessed to rapidly expand the target repertoire of light-triggered time-resolved macromolecular crystallography. Late-intermediate cryo-trapping after uncaging revealed the partial accommodation of 8-oxoguanine in the active site with 68% occupancy, which did not induce full active-site adaptation to the catalytic state. Crystal illumination led to a light-dependent loss of diffraction power, likely due to crystal-packing collapse during the very late reaction stages. This work therefore not only demonstrates that hOgg1 is well suited for time-resolved crystallography, but also that such analysis is necessary to determine further steps in its reaction.enDNA repairhOgg1intermediate trappingphotocaged substrate analogs[SDGs]SDG3journal article10.1107/S2052252525006062