National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences (CAS), Beijing 100101, P.R. China.
School of Life Science, University of Science and Technology of China, Hefei, Anhui 230026, P.R. China.
Science. 2017 Aug 25;357(6353):815-820. doi: 10.1126/science.aan0327.
In plants, the photosynthetic machinery photosystem II (PSII) consists of a core complex associated with variable numbers of light-harvesting complexes II (LHCIIs). The supercomplex, comprising a dimeric core and two strongly bound and two moderately bound LHCIIs (CSM), is the dominant form in plants acclimated to limited light. Here we report cryo-electron microscopy structures of two forms of CSM (termed stacked and unstacked) from at 2.7- and 3.2-angstrom resolution, respectively. In each CSM, the moderately bound LHCII assembles specifically with a peripheral antenna complex CP24-CP29 heterodimer and the strongly bound LHCII, to establish a pigment network that facilitates light harvesting at the periphery and energy transfer into the core. The high mobility of peripheral antennae, including the moderately bound LHCII and CP24, provides insights into functional regulation of plant PSII.
在植物中，光合作用机构光系统 II（PSII）由一个与可变数量的光捕获复合物 II（LHCIIs）相关联的核心复合物组成。超级复合物由一个二聚体核心和两个强结合和两个中等结合的 LHCII（CSM）组成，是在适应有限光照的植物中占主导地位的形式。在这里，我们报告了来自 的两种形式的 CSM（分别称为堆叠和未堆叠）的 cryo-electron microscopy 结构，分辨率分别为 2.7-和 3.2-埃。在每个 CSM 中，中等结合的 LHCII 与外周天线复合物 CP24-CP29 异二聚体特异性组装，与强结合的 LHCII 一起建立一个色素网络，促进外围的光捕获和能量转移到核心。外周天线，包括中等结合的 LHCII 和 CP24 的高迁移性，为植物 PSII 的功能调节提供了深入的了解。
