In photosynthesis, light energy is captured by pigments bound to light‐harvesting antenna proteins (LHC) that then transfer the energy to the photosystem (PS) cores to initiate photochemical reactions. The LHC proteins surround the PS cores to form PS‐LHC supercomplexes. In order to adapt to a wide range of light environments, photosynthetic organisms have developed a large variety of pigments and antenna proteins to utilize the light energy efficiently under different environments. Diatoms are a group of important eukaryotic algae and possess fucoxanthin (Fx) chlorophyll a/c proteins (FCP) as antenna which have exceptional capabilities of harvesting blue‐green light under water and dissipate excess energy under strong light conditions. We have solved the structure of a PSII–FCPII supercomplex from a centric diatom Chaetoceros gracilis by cryo‐electron microscopy, and also the structure of an isolated FCP dimer from a pennate diatom Phaeodactylum tricornutum by X‐ray crystallography at a high resolution. These results revealed the oligomerization states of FCPs distinctly different from those of LHCII found in the green lineage organisms, the detailed binding patterns of Chl c and Fxs, a huge pigment network, and extensive protein–protein, pigment–protein, and pigment–pigment interactions within the PSII–FCPII supercomplex. These results therefore provide a solid structural basis for examining the detailed mechanisms of the highly efficient energy transfer and quenching processes in diatoms.

中文翻译：

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硅藻光系统II的结构特征-集光天线复合体。

在光合作用中，光能被与光捕获天线蛋白（LHC）结合的色素捕获，然后色素将能量转移至光系统（PS）核心以引发光化学反应。LHC蛋白围绕PS核形成PS‐LHC超复合物。为了适应广泛的光照环境，光合生物已开发出多种色素和触角蛋白，以在不同环境下有效利用光能。硅藻是一组重要的真核藻类，并具有岩藻黄质（Fx）叶绿素a / c蛋白质（FCP）作为天线，具有在水下收集蓝绿色光并在强光条件下消散多余能量的出色能力。我们已经通过冷冻电子显微镜解决了中心硅藻Chaetoceros gracilis的PSII-FCPII超复合物的结构，以及通过高分辨率X射线晶体学从三角硅藻Phaeodactylum tricornutum分离出的FCP二聚体的结构。这些结果表明，FCPs的低聚状态与在绿色谱系生物中发现的LHCII的低聚状态明显不同，Chl c的详细结合方式Fxs是一个巨大的色素网络，在PSII-FCPII超复合物中具有广泛的蛋白质-蛋白质，色素-蛋白质和色素-色素相互作用。因此，这些结果为检查硅藻中高效能量转移和淬灭过程的详细机理提供了坚实的结构基础。