Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Department of Biochemistry and Molecular Biology, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel
Biochem Soc Trans. 2018 Apr 17;46(2):285-294. doi: 10.1042/BST20170299. Epub 2018 Feb 27.
Plant photosystem I (PSI) is one of the most intricate membrane complexes in nature. It comprises two complexes, a reaction center and light-harvesting complex (LHC), which together form the PSI-LHC supercomplex. The crystal structure of plant PSI was solved with two distinct crystal forms. The first, crystallized at pH 6.5, exhibited 21 symmetry; the second, crystallized at pH 8.5, exhibited 212121 symmetry. The surfaces involved in binding plastocyanin and ferredoxin are identical in both forms. The crystal structure at 2.6 Å resolution revealed 16 subunits, 45 transmembrane helices, and 232 prosthetic groups, including 143 chlorophyll , 13 chlorophyll , 27 β-carotene, 7 lutein, 2 xanthophyll, 1 zeaxanthin, 20 monogalactosyl diglyceride, 7 phosphatidyl diglyceride, 5 digalactosyl diglyceride, 2 calcium ions, 2 phylloquinone, and 3 iron sulfur clusters. The model reveals detailed interactions, providing mechanisms for excitation energy transfer and its modulation in one of nature's most efficient photochemical machine.
植物光系统 I（PSI）是自然界中最复杂的膜复合物之一。它由两个复合物组成，一个反应中心和一个光捕获复合物（LHC），它们共同形成 PSI-LHC 超复合物。植物 PSI 的晶体结构是用两种不同的晶体形式解决的。第一种，在 pH 值为 6.5 时结晶，表现出 21 对称；第二种，在 pH 值为 8.5 时结晶，表现出 212121 对称。与质体蓝素和铁氧还蛋白结合的表面在两种形式中是相同的。分辨率为 2.6 Å 的晶体结构揭示了 16 个亚基、45 个跨膜螺旋和 232 个辅基，包括 143 个叶绿素、13 个叶绿素、27 个β-胡萝卜素、7 个叶黄素、2 个叶黄素、1 个玉米黄质、20 个单半乳糖基二甘油酯、7 个磷脂二甘油酯、5 个二半乳糖基二甘油酯、2 个钙离子、2 个叶绿醌和 3 个铁硫簇。该模型揭示了详细的相互作用，为激发能量转移及其在自然界最有效的光化学机器之一中的调节提供了机制。
