Structural basis of LhcbM5-mediated state transitions in green algae
Structural basis of LhcbM5-mediated state transitions in green algae
复制标题
DOI：
10.1038/s41477-021-00960-8
复制
发表时间：
2021-07-08
期刊：
影响因子：
18
通讯作者：
Li, Mei
中科院分区：
文献类型：
--
作者：
Pan, Xiaowei;Tokutsu, Ryutaro;Li, Mei
莱茵衣藻PSI-LHCI-LHCII超复合物的高分辨结构揭示了PSI-LHCI复合物与两个磷酸化LHCII三聚体之间的组装机制。在绿色藻类和植物中，状态转换作为调节光系统I和II（分别为PSI和PSII）捕光能力的短期光适应过程。在此过程中，捕光复合物II（LHCII）的一部分被磷酸化，从PSII解离并与PSI结合以形成超复合物PSI-LHCI-LHCII。在这里，我们报告的高分辨率结构的PSI-LHCI-LHCII莱茵衣藻，揭示PSI-LHCI复合物和两个磷酸化的LHCII三聚体包含所有四种类型的LhcbM蛋白之间的装配机制。两种特异性LhcbM亚型，即LhcbM 1和LhcbM 5，通过其磷酸化氨基末端区域直接与PSI核心相互作用。此外，缺乏LhcbM 1或LhcbM 5的突变株的生化和功能研究表明，只有LhcbM 5是不可或缺的超复合物的形成。研究结果揭示了绿色藻PSI与两种磷酸化LHCII之间的特异性相互作用和潜在的激发能量传递途径。
High-resolution structures of the PSI-LHCI-LHCII supercomplex from Chlamydomonas reinhardtii reveal the mechanism of assembly between the PSI-LHCI complex and two phosphorylated LHCII trimers.In green algae and plants, state transitions serve as a short-term light-acclimation process in the regulation of the light-harvesting capacity of photosystems I and II (PSI and PSII, respectively). During the process, a portion of light-harvesting complex II (LHCII) is phosphorylated, dissociated from PSII and binds with PSI to form the supercomplex PSI-LHCI-LHCII. Here, we report high-resolution structures of PSI-LHCI-LHCII from Chlamydomonas reinhardtii, revealing the mechanism of assembly between the PSI-LHCI complex and two phosphorylated LHCII trimers containing all four types of LhcbM protein. Two specific LhcbM isoforms, namely LhcbM1 and LhcbM5, directly interact with the PSI core through their phosphorylated amino terminal regions. Furthermore, biochemical and functional studies on mutant strains lacking either LhcbM1 or LhcbM5 indicate that only LhcbM5 is indispensable in supercomplex formation. The results unravel the specific interactions and potential excitation energy transfer routes between green algal PSI and two phosphorylated LHCIIs.