Dynamical and allosteric regulation of photoprotection in light harvesting complex Ⅱ  

作　　者：Hao Li Yingjie Wang Manping Ye Shanshan Li Deyong Li Haisheng Ren Mohan Wang Luchao Du Heng Li Gianluigi Veglia Jiali Gao Yuxiang Weng 

机构地区：[1]Laboratory of Soft Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Shenzhen Bay Laboratory,Shenzhen 518055,China [4]Department of Chemistry and Supercomputing Institute,University of Minnesota,Minneapolis,MN 55455,USA [5]Department of Biochemistry,Molecular Biology and Biophysics,University of Minnesota,Minneapolis,MN 55455,USA [6]Laboratory of Computational Chemistry and Drug Design,State Key Laboratory of Chemical Oncogenomics,Peking University Shenzhen Graduate School,Shenzhen 518055,China

出　　处：《Science China Chemistry》2020年第8期1121-1133,共13页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China(21433014,11721404,21533003);the Ministry of Science and Technology(2017YFB0203400);Chinese Academy of Sciences Innovation Program(KJCX2-YW-W25);the National Institutes of Health(GM46736,GM64742)。

摘　　要：Major light-harvesting complex of photosystemⅡ(LHCⅡ)plays a dual role in light-harvesting and excited energy dissipation to protect photodamage from excess energy.The regulatory switch is induced by increased acidity,temperature or both.However,the molecular origin of the protein dynamics at the atomic level is still unknown.We carried out temperature-jump time-resolved infrared spectroscopy and molecular dynamics simulations to determine the energy quenching dynamics and conformational changes of LHCⅡtrimers.We found that the spontaneous formation of a pair of localα-helices from the 310-helix E/loop and the C-terminal coil of the neighboring monomer,in response to the increased environmental temperature and/or acidity,induces a scissoring motion of transmembrane helices A and B,shifting the conformational equilibrium to a more open state,with an increased angle between the associated carotenoids.The dynamical and allosteric conformation change leads to close contacts between carotenoid lutein 1 and chlorophyll pigment 612,facilitating the fluorescence quenching.Based on these results,we suggest a unified mechanism by which the LHCⅡtrimer controls the dissipation of excess excited energy in response to increased temperature and acidity,as an intrinsic result of intense sun light in plant photosynthesis.

关 键 词：LHCⅡphotoprotection conformational dynamics and allostery protein switch T-jump FTIR fluorescence quenching excited energy transfer 

分 类 号：Q945.11[生物学—植物学]