Physical and Biophysical Chemistry, Bielefeld University, 33615 Bielefeld, Germany.
Matthias Schleiden Institute of Genetics, Bioinformatics and Molecular Botany, Friedrich Schiller University, 07743 Jena, Germany.
J Phys Chem Lett. 2021 Jun 17;12(23):5558-5563. doi: 10.1021/acs.jpclett.1c00844. Epub 2021 Jun 8.
Plant cryptochromes are central blue light receptors in land plants and algae. Photoreduction of the flavin bound to the photolyase homology region (PHR) causes a dissociation of the C-terminal extension (CCT) as effector via an unclear pathway. We applied the recently developed in-cell infrared difference (ICIRD) spectroscopy to study the response of the full-length pCRY from in living bacterial cells, because the receptor degraded upon isolation. We demonstrate a stabilization of the flavin neutral radical as photoproduct and of the resulting β-sheet reorganization by binding of cellular ATP. Comparison between light-induced structural responses of full-length pCRY and PHR reveals a downshift in frequency of the β-sheet signal, implying an association of the CCT close to the only β-sheet of the PHR in the dark. We provide a missing link in activation of plant cryptochromes after flavin photoreduction by indicating that β-sheet reorganization causes the CCT release and restructuring.
植物隐花色素是陆生植物和藻类中重要的蓝光受体。与光解酶同源区（PHR）结合的黄素发生光还原作用，导致 C 端延伸（CCT）通过一条不明确的途径作为效应物解离。我们应用最近开发的细胞内红外差（ICIRD）光谱法来研究全长 pCRY 来自 的反应，因为受体在分离时会降解。我们证明了黄素中性自由基作为光产物的稳定，以及通过与细胞 ATP 结合导致的 β-折叠重组。全长 pCRY 和 PHR 的光诱导结构响应之间的比较表明，β-折叠信号的频率下移，这意味着在黑暗中 CCT 与 PHR 中的唯一 β-折叠接近。我们通过指出β-折叠重组导致 CCT 释放和重构，为黄素光还原后植物隐花色素的激活提供了一个缺失的环节。
