Department of Physics, Department of Chemistry and Biochemistry, Programs of Biophysics, Chemical Physics and Biochemistry, The Ohio State University, Columbus, OH, 43210, USA.
Center for Ultrafast Science and Technology, School of Physics and Astronomy, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
Nat Commun. 2022 Jan 10;13(1):93. doi: 10.1038/s41467-021-27756-w.
Photoreceptors are a class of light-sensing proteins with critical biological functions. UVR8 is the only identified UV photoreceptor in plants and its dimer dissociation upon UV sensing activates UV-protective processes. However, the dissociation mechanism is still poorly understood. Here, by integrating extensive mutations, ultrafast spectroscopy, and computational calculations, we find that the funneled excitation energy in the interfacial tryptophan (Trp) pyramid center drives a directional Trp-Trp charge separation in 80 ps and produces a critical transient Trp anion, enabling its ultrafast charge neutralization with a nearby positive arginine residue in 17 ps to destroy a key salt bridge. A domino effect is then triggered to unzip the strong interfacial interactions, which is facilitated through flooding the interface by channel and interfacial water molecules. These detailed dynamics reveal a unique molecular mechanism of UV-induced dimer monomerization.
光感受器是一类具有重要生物学功能的感光蛋白。UVR8 是植物中唯一被鉴定的 UV 光感受器，其在 UV 感应时的二聚体解离会激活 UV 保护过程。然而，其解离机制仍不清楚。在这里，我们通过整合广泛的突变、超快光谱和计算计算，发现界面色氨酸（Trp）金字塔中心的漏斗式激发能量驱动了一个定向的 Trp-Trp 电荷分离，在 80 ps 内产生了一个关键的瞬态 Trp 阴离子，使其能够在 17 ps 内与附近的正精氨酸残基快速电荷中和，破坏一个关键的盐桥。随后，触发了一个级联效应，通过通道和界面水分子淹没界面来解开强界面相互作用。这些详细的动力学揭示了 UV 诱导二聚体单体化的独特分子机制。
