Structure of a green algal photosystem I in complex with a large number of light-harvesting complex I subunits

Xiaochun Qin, Xiong Pi, Wenda Wang, Guangye Han, Lixia Zhu, Mingmei Liu, Linpeng Cheng, Jian-Ren Shen, Tingyun Kuang, Sen Fang Sui

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Photosystem I (PSI) is a highly efficient natural light-energy converter, and has diverse light-harvesting antennas associated with its core in different photosynthetic organisms. In green algae, an extremely large light-harvesting complex I (LHCI) captures and transfers energy to the PSI core. Here, we report the structure of PSI–LHCI from a green alga Bryopsis corticulans at 3.49 Å resolution, obtained by single-particle cryo-electron microscopy, which revealed 13 core subunits including subunits characteristic of both prokaryotes and eukaryotes, and 10 light-harvesting complex a (Lhca) antennas that form a double semi-ring and an additional Lhca dimer, including a novel four-transmembrane-helix Lhca. In total, 244 chlorophylls were identified, some of which were located at key positions for the fast energy transfer. These results provide a firm structural basis for unravelling the mechanisms of light-energy harvesting, transfer and quenching in the green algal PSI–LHCI, and important clues as to how PSI–LHCI has changed during evolution.

Original languageEnglish
Pages (from-to)263-272
Number of pages10
JournalNature Plants
Issue number3
Publication statusPublished - Mar 1 2019


ASJC Scopus subject areas

  • Plant Science

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