biostudies-literatureZhou ZMinistry of Science and Technology of the People's Republic of China (MOST)MOST | National Natural Science Foundation of China (NSFC)e2416284121https://www.ebi.ac.uk/biostudies/studies/S-EPMC11725880biostudies-literatureUnknown122(1)Class II photolyases (PLs) are a distant subclade in the photolyase/cryptochrome superfamily, displaying a unique Trp-Tyr tetrad for photoreduction and exhibiting a lower quantum yield (QY) of DNA repair (49%) than class I photolyases (82%) [M. Zhang, L. Wang, S. Shu, A. Sancar, D. Zhong, <i>Science</i> <b>354</b>, 209-213 (2016)]. Using layer-by-layer mutant design and femtosecond spectroscopy, we have successfully determined the rates of electron transfer and proton transfer, driving force, and reorganization energy for nine elementary steps involved in the initial photoreduction of class II <i>Arabidopsis thaliana</i> photolyase (AtPL), thereby constructing the photoreduction network specific to class II PLs. Several dynamic features have been revealed including a slow-rise (172 ps) andProceedings of the National Academy of Sciences of the United States of AmericaElucidation of a distinct photoreduction pathway in class II &lt;i&gt;Arabidopsis thaliana&lt;/i&gt; photolyase.PMC117258803197123312004246224330032020YFA0509700Ding BChen ZWang BKang XWZhong DTang SZou SZhou YZhou ZfalseElucidation of a distinct photoreduction pathway in class II &lt;i&gt;Arabidopsis thaliana&lt;/i&gt; photolyase.Class II photolyases (PLs) are a distant subclade in the photolyase/cryptochrome superfamily, displaying a unique Trp-Tyr tetrad for photoreduction and exhibiting a lower quantum yield (QY) of DNA repair (49%) than class I photolyases (82%) [M. Zhang, L. Wang, S. Shu, A. Sancar, D. Zhong, <i>Science</i> <b>354</b>, 209-213 (2016)]. Using layer-by-layer mutant design and femtosecond spectroscopy, we have successfully determined the rates of electron transfer and proton transfer, driving force, and reorganization energy for nine elementary steps involved in the initial photoreduction of class II <i>Arabidopsis thaliana</i> photolyase (AtPL), thereby constructing the photoreduction network specific to class II PLs. Several dynamic features have been revealed including a slow-rise (172 ps) and2025-01-01T00:00:00Z2025 Jan2026-06-01T15:39:32.795Z2026-04-08T13:39:19.97ZS-EPMC117258803973980310.1073/pnas.2416284121