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Nat Plants. 2019 Mar;5(3):263-272. doi: 10.1038/s41477-019-0379-y. Epub 2019 Mar 8.

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

Author information

1
School of Biological Science and Technology, University of Jinan, Jinan, China.
2
Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
3
State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
4
Institute for Interdisciplinary Science, Okayama University, Okayama, Japan.
5
Photosynthesis Research Center, Key Laboratory of Photobiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China. kuangty@ibcas.ac.cn.
6
State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China. suisf@mail.tsinghua.edu.cn.

Abstract

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.

PMID:
30850820
DOI:
10.1038/s41477-019-0379-y

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