Antenna arrangement and energy-transfer pathways of PSI-LHCI from the moss Physcomitrella patens.
Antenna arrangement and energy-transfer pathways of PSI-LHCI from the moss Physcomitrella patens.
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立碗藓 (Physcomitrella patens) 的 PSI-LHCI 的天线排列和能量转移途径
DOI：
10.1038/s41421-021-00242-9
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发表时间：
2021-02-16
期刊：
影响因子：
33.5
通讯作者：
Shen JR
中科院分区：
文献类型：
--
作者：
Yan Q;Zhao L;Wang W;Pi X;Han G;Wang J;Cheng L;He YK;Kuang T;Qin X;Sui SF;Shen JR
植物分别通过围绕光系统I和II（PSI和PSII）的捕光复合物I和II（LHCI和LHCII）来捕获用于光合作用的光能。在绿色植物进化过程中，苔藓处于水生光合生物向陆生植物进化的中间位置，是最早登陆的光合生物。在这里，我们报告的结构PSI-LHCI超复杂的苔藓立碗藓（Pp）在3.23纳米分辨率解决了冷冻电子显微镜。我们的结构显示，四个Lhca亚基与PSI核心相关，顺序为Lhca 1-Lhca 5-Lhca 2-Lhca 3。在大多数绿色藻类PSI-LHCI中，亚基的数目从8个减少到10个，但与陆生植物的亚基数目相同。虽然Pp PSI-LHCI具有与陆生植物PSI-LHCI相似的结构，但它在Lhca的第二位具有Lhca 5而不是Lhca 4，并且发现绿色藻类、苔藓和陆生植物PSI-LHCI之间的叶绿素排列存在一些差异。在苔藓PSI-LHCI中发现的一种叶绿素PsaF-Chl 305位于两个中间Lhca亚基与PSI核心之间的差距区域，因此可能使LHCI向PSI核心的激发能转移比陆地植物更有效。另一方面，两侧Lhca亚基的能量传递路径相对保守。这些结果为揭示苔藓PSI-LHCI的光能收集和传递机制提供了结构基础，也为研究登陆后PSI-LHCI的变化提供了重要线索。
Plants harvest light energy utilized for photosynthesis by light-harvesting complex I and II (LHCI and LHCII) surrounding photosystem I and II (PSI and PSII), respectively. During the evolution of green plants, moss is at an evolutionarily intermediate position from aquatic photosynthetic organisms to land plants, being the first photosynthetic organisms that landed. Here, we report the structure of the PSI–LHCI supercomplex from the moss Physcomitrella patens (Pp) at 3.23 Å resolution solved by cryo-electron microscopy. Our structure revealed that four Lhca subunits are associated with the PSI core in an order of Lhca1–Lhca5–Lhca2–Lhca3. This number is much decreased from 8 to 10, the number of subunits in most green algal PSI–LHCI, but the same as those of land plants. Although Pp PSI–LHCI has a similar structure as PSI–LHCI of land plants, it has Lhca5, instead of Lhca4, in the second position of Lhca, and several differences were found in the arrangement of chlorophylls among green algal, moss, and land plant PSI–LHCI. One chlorophyll, PsaF–Chl 305, which is found in the moss PSI–LHCI, is located at the gap region between the two middle Lhca subunits and the PSI core, and therefore may make the excitation energy transfer from LHCI to the core more efficient than that of land plants. On the other hand, energy-transfer paths at the two side Lhca subunits are relatively conserved. These results provide a structural basis for unravelling the mechanisms of light-energy harvesting and transfer in the moss PSI–LHCI, as well as important clues on the changes of PSI–LHCI after landing.
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