Structural highlights
FunctionPublication Abstract from PubMedPhotolyases repair UV damage to DNA by using absorbed blue light. Within the photolyase/cryptochrome superfamily (PCSf), a major subgroup consists of prokaryotic (6-4) photolyases. These enzymes rely on flavin adenine dinucleotide (FAD) as a catalytic cofactor, besides an ancillary antenna chromophore, and a [4Fe-4S] cluster with yet unknown function. For the prokaryotic 6-4 photolyase of Caulobacter crescentus, we investigated structural changes associated with its different redox states by damage-free crystallography using X-ray free-electron lasers. EPR and optical spectroscopy confirmed redox-dependent structural transitions, including the formation of an oxidized [4Fe-4S](3+) cluster with the dynamic cleavage of a single iron-sulfur bond. Photoreduction to the catalytic FADH(-) state alters the flavin binding site at the proximal aromatic pair Y390/F394 that is part of the electron transport pathway. Upon oxidation, the observable structural transitions of the protein matrix around the [4Fe-4S] cluster may affect DNA binding and are consistent with the much-debated role of the iron-sulfur cluster in DNA-binding proteins for quenching electron holes. Redox-State-Dependent Structural Changes within a Prokaryotic 6-4 Photolyase.,Wang PH, Hosokawa Y, C Soares J, Emmerich HJ, Fuchs V, Caramello N, Engilberge S, Bologna A, Rosner CJ, Nakamura M, Watad M, Luo F, Owada S, Tosha T, Kang J, Tono K, Bessho Y, Nango E, Pierik AJ, Royant A, Tsai MD, Yamamoto J, Maestre-Reyna M, Essen LO J Am Chem Soc. 2025 Apr 29. doi: 10.1021/jacs.4c18116. PMID:40298610[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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