Regulatory dynamics of the higher-plant PSI-LHCI supercomplex during state transitions  

作　　者：Jianghao Wu Shuaijiabin Chen Chao Wang Weijun Lin Chao Huang Chengxu Fan Dexian Han Dandan Lu Xiumei Xu SenFang Sui Lixin Zhang 

机构地区：[1]State Key Laboratory of Crop Stress Adaptation and Improvement,School of Life Sciences,Henan University,Jinming Avenue,Kaifeng 475004,China [2]School of Life Science,Southern University of Science and Technology,Shenzhen 518055,China [3]State Key Laboratory of Membrane Biology,Beijing Advanced Innovation Center for Structural Biology,Beijing Frontier Research Center for Biological Structure,School of Life Sciences,Tsinghua University,Beijing 100084,China [4]Cryo-EM Center,Southern University of Science and Technology,Shenzhen 518055,China [5]Photosynthesis Research Center,Key Laboratory of Photobiology,Insttute of Botany,Chinese Academy of Sciences,Bejing 100093,China

出　　处：《Molecular Plant》2023年第12期1937-1950,共14页分子植物（英文版）

基　　金：the National Key Research and Development Program of China(2020YFA0907600 to L.Z.);the National Natural Science Foundation of China(National Science Foundation of China)(32241030 to S.S.).

摘　　要：State transition is a fundamental light acclimation mechanism of photosynthetic organisms in response to the environmental light conditions.This process rebalances the excitation energy between photosystemI(PSl)and photosystem Il through regulated reversible binding of the light-harvesting complex Il(LHCll)to PSl.However,the structural reorganization of PSI-LHCI,the dynamic binding of LHCll,and the regulatory mechanisms underlying state transitions are less understood in higher plants.In this study,using cryoelectron microscopy we resolved the structures of PSI-LHCI in both state 1(PSI-LHCI-ST1)and state 2(PSILHCI-LHCll-ST2)from Arabidopsis thaliana.Combined genetic and functional analyses revealed novel contacts between Lhcb1 and PsaK that further enhanced the binding of the LHCll trimer to the PSI core with the known interactions between phosphorylated Lhcb2 and the PsaL/PsaH/PsaO subunits.Specifically,PsaO was absent in the PSI-LHCI-ST1 supercomplex but present in the PSI-LHCI-LHCIl-ST2 supercomplex,in which the PsaL/PsaK/PsaA subunits undergo several conformational changes to strengthen the binding of PsaO in ST2.Furthermore,the PSI-LHCI module adopts a more compact configuration with shorter Mg-to-Mg distances between the chlorophylls,which may enhance the energy transfer efficiency from the peripheral antenna to the PSl core in ST2.Collectively,our work provides novel structural and functional insights into the mechanisms of light acclimation during state transitions in higher plants.

关 键 词：state transitions dynamic conformation photosystem l regulatory mechanism Arabidopsis thaliana 

分 类 号：Q94[生物学—植物学]