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.
Bibliographical noteFunding Information:
We thank Prof. Yigong Shi (Tsinghua University) for generously providing the UVR8 plasmid. This work was supported in part by the National Institute of Health (Grant GM144047 to D.Z. for experiments and GM46736 to J.G. for computation) and the National Natural Science Foundation of China (for support of collaboration efforts through a visit of XL and summer stays of D.Z. in Shanghai Jiao Tong University and Grant No. 21533003 to J.G. for support of H.R. to complete computational work).
© 2022, The Author(s).
PubMed: MeSH publication types
- Journal Article
- Research Support, N.I.H., Extramural
- Research Support, Non-U.S. Gov't