Redox-State-Dependent Structural Changes within a Prokaryotic 6-4 Photolyase.
Wang, P.H., Hosokawa, Y., C Soares, J., Emmerich, H.J., Fuchs, V., Caramello, N., Engilberge, S., Bologna, A., Rosner, C.J., Nakamura, M., Watad, M., Luo, F., Owada, S., Tosha, T., Kang, J., Tono, K., Bessho, Y., Nango, E., Pierik, A.J., Royant, A., Tsai, M.D., Yamamoto, J., Maestre-Reyna, M., Essen, L.O.(2025) J Am Chem Soc 
- PubMed: 40298610 
- DOI: https://doi.org/10.1021/jacs.4c18116
- Primary Citation of Related Structures:  
9HNK, 9HNL, 9HNM, 9HNN, 9HNO, 9Q8F - PubMed Abstract: 
Photolyases 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.
Organizational Affiliation: 
Department of Chemistry, Philipps University Marburg, Hans-Meerwein Strasse 4, Marburg 35032, Germany.