Unified Mechanism of Light-State BLUF Domain Photocycles by Capturing Proton Relay Intermediates  

作　　者：Yalin Zhou Xiu-Wen Kang Zhongneng Zhou Zijing Chen Shuhua Zou Siwei Tang Bingyao Wang Kailin Wang Dongping Zhong Bei Ding 

机构地区：[1]Center for Ultrafast Science and Technology,School of Chemistry and Chemical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China

出　　处：《Ultrafast Science》2024年第5期44-54,共11页超快科学(英文)

基　　金：supported by the National Key Research and Development Program of China(grant 2020YFA0509700);National Natural Science Foundation of China(grant 31971233).

摘　　要：The blue light using flavin(BLUF)domain is one of nature’s smallest photoswitching protein domains,yet a cross-species photoactivation mechanism is lacking.Its photoactivation involves an intricate bidirectional proton-coupled electron transfer(PCET)reaction;however,the key reverse PCET route remains largely elusive,with its elementary steps undissected.Here,we resolved the light-state photoreaction cycles of the BLUF domains in 3 species,i.e.,AppA from Rhodobacter sphaeroides,OaPAC from Oscillatoria acuminata,and SyPixD from Synechocystis sp.PCC6803,with a unified kinetic model.Using mutant design and femtosecond spectroscopy,we captured the spectroscopic snapshots of a key proton-relay intermediate in all species,revealing that the light-state photoreaction cycle consists of 4 elementary steps including a forward concerted electron-proton transfer(CEPT),a 2-step proton rocking,and a reverse CEPT.We emphasize that the last reverse CEPT step(1.5 to 3.7 ps)is shared by both the light-state and dark-state photocycles and is essential to the photoswitching functionality.

关 键 词：oscillatoria acuminat rhodobacter sphaeroidesoapac bluf domains photocycles proton relay INTERMEDIATES 

分 类 号：Q945[生物学—植物学]