National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, P.R. China.
University of Chinese Academy of Sciences, Beijing 100049, P.R. China.
Science. 2018 Jun 8;360(6393):1109-1113. doi: 10.1126/science.aat1156.
Plants regulate photosynthetic light harvesting to maintain balanced energy flux into photosystems I and II (PSI and PSII). Under light conditions favoring PSII excitation, the PSII antenna, light-harvesting complex II (LHCII), is phosphorylated and forms a supercomplex with PSI core and the PSI antenna, light-harvesting complex I (LHCI). Both LHCI and LHCII then transfer excitation energy to the PSI core. We report the structure of maize PSI-LHCI-LHCII solved by cryo-electron microscopy, revealing the recognition site between LHCII and PSI. The PSI subunits PsaN and PsaO are observed at the PSI-LHCI interface and the PSI-LHCII interface, respectively. Each subunit relays excitation to PSI core through a pair of chlorophyll molecules, thus revealing previously unseen paths for energy transfer between the antennas and the PSI core.
植物调节光合作用光捕获以维持进入光系统 I 和 II（PSI 和 PSII）的平衡能量流。在有利于 PSII 激发的光照条件下，PSII 天线、光捕获复合物 II（LHCII）被磷酸化，并与 PSI 核心和 PSI 天线、光捕获复合物 I（LHCI）形成超复合物。然后，LHCI 和 LHCII 将激发能量转移到 PSI 核心。我们通过冷冻电子显微镜报告了玉米 PSI-LHCI-LHCII 的结构，揭示了 LHCII 和 PSI 之间的识别位点。PSI 亚基 PsaN 和 PsaO 分别在 PSI-LHCI 界面和 PSI-LHCII 界面被观察到。每个亚基通过一对叶绿素分子将激发传递给 PSI 核心，从而揭示了天线和 PSI 核心之间能量转移的以前看不见的途径。
