Structure of spinach photosystem II-LHCII supercomplex at 3.2 Å resolution
Structure of spinach photosystem II-LHCII supercomplex at 3.2 Å resolution
复制标题
3.2 埃分辨率下菠菜光系统 II-LHCII 超复合体的结构
DOI：
10.1038/nature18020
复制
发表时间：
2016-06-02
期刊：
影响因子：
64.8
通讯作者：
Liu, Zhenfeng
中科院分区：
文献类型：
--
作者：
Wei, Xuepeng;Su, Xiaodong;Liu, Zhenfeng
在光合作用期间，植物光系统 II 核心复合体从外围光捕获复合体 II (LHCII) 接收激发能量。它们之间激发能量转移的途径及其组装机制仍有待通过高分辨率结构研究来破译。在这里，我们报告了通过单粒子冷冻电子显微镜以 3.2 埃分辨率解析的 1.1 兆道尔顿菠菜光系统 II-LHCII 超复合体的结构。该结构揭示了同二聚超分子系统，其中每个单体包含 25 个蛋白质亚基、105 个叶绿素、28 个类胡萝卜素和其他辅助因子。三个外在亚基（PsbO、PsbP 和 PsbQ）对于光系统 II 的最佳放氧活性至关重要，它们形成一个三角冠，保护 CP43 和 D1 的 Mn4CaO5 结合域。一个主要的三聚体和两个次要的单体 LHCII 与每个核心复合物单体结合，并且天线-核心相互作用通过三个小的内在亚基（PsbW、PsbH 和 PsbZ）得到加强。通过分析紧密相连的界面叶绿素，我们对天线和核心复合体之间的能量传递路径有了详细的了解。
During photosynthesis, the plant photosystem II core complex receives excitation energy from the peripheral light-harvesting complex II (LHCII). The pathways along which excitation energy is transferred between them, and their assembly mechanisms, remain to be deciphered through high-resolution structural studies. Here we report the structure of a 1.1-megadalton spinach photosystem II-LHCII supercomplex solved at 3.2 angstrom resolution through single-particle cryo-electron microscopy. The structure reveals a homodimeric supramolecular system in which each monomer contains 25 protein subunits, 105 chlorophylls, 28 carotenoids and other cofactors. Three extrinsic subunits (PsbO, PsbP and PsbQ), which are essential for optimal oxygen-evolving activity of photosystem II, form a triangular crown that shields the Mn4CaO5-binding domains of CP43 and D1. One major trimeric and two minor monomeric LHCIIs associate with each core-complex monomer, and the antenna-core interactions are reinforced by three small intrinsic subunits (PsbW, PsbH and PsbZ). By analysing the closely connected interfacial chlorophylls, we have obtained detailed insights into the energy-transfer pathways between the antenna and core complexes.