Serial crystallography captures dynamic control of sequential electron and proton transfer events in a flavoenzyme
Serial crystallography captures dynamic control of sequential electron and proton transfer events in a flavoenzyme
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连续晶体学捕获了黄酶中连续电子和质子转移事件的动态控制
DOI：
10.1038/s41557-022-00922-3
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发表时间：
2022-04-07
期刊：
影响因子：
21.8
通讯作者：
Tsai, Ming-Daw
中科院分区：
文献类型：
--
作者：
Maestre-Reyna, Manuel;Yang, Cheng-Han;Tsai, Ming-Daw
黄素辅酶广泛存在于生物氧化还原反应中。DNA光解酶及其黄素发色团(FAD)利用蓝光进行DNA修复和光还原。后一过程包括两个单电子转移到FAD和间歇性质子化步骤，以启动对DNA修复活性的酶。在这里，我们使用时间分辨的连续飞秒X射线结晶学来描述光驱动的电子转移如何触发FAD与其ASN/Arg-Asp氧化还原传感器三联体之间随后的纳秒到微秒的纠缠。我们发现，光解酶-隐花色素家族中的这一关键功能调节FAD的重新杂交和质子化。在第一次电子转移后，当精氨酸靠近时，FAD(中心点)异四氢呋喃环强烈扭曲，以稳定负电荷。随后精氨酸-天冬氨酸盐桥的断裂允许质子从精氨酸转移到FAD(中心点-)。我们的分子视频展示了氧化还原辅因子的蛋白质环境如何以有序的方式组织多个电子/质子转移事件，这可能适用于其他氧化还原系统，如光合作用。
Flavin coenzymes are universally found in biological redox reactions. DNA photolyases, with their flavin chromophore (FAD), utilize blue light for DNA repair and photoreduction. The latter process involves two single-electron transfers to FAD with an intermittent protonation step to prime the enzyme active for DNA repair. Here we use time-resolved serial femtosecond X-ray crystallography to describe how light-driven electron transfers trigger subsequent nanosecond-to-microsecond entanglement between FAD and its Asn/Arg-Asp redox sensor triad. We found that this key feature within the photolyase-cryptochrome family regulates FAD re-hybridization and protonation. After first electron transfer, the FAD(center dot-) isoalloxazine ring twists strongly when the arginine closes in to stabilize the negative charge. Subsequent breakage of the arginine-aspartate salt bridge allows proton transfer from arginine to FAD(center dot-). Our molecular videos demonstrate how the protein environment of redox cofactors organizes multiple electron/proton transfer events in an ordered fashion, which could be applicable to other redox systems such as photosynthesis.