Structural basis for energy transfer in a huge diatom PSI-FCPI supercomplex

Caizhe Xu, Xiong Pi, Yawen Huang, Guangye Han, Xiaobo Chen, Xiaochun Qin, Guoqiang Huang, Songhao Zhao, Yanyan Yang, Tingyun Kuang, Wenda Wang, Sen Fang Sui, Jian Ren Shen

Research output: Contribution to journalArticlepeer-review

Abstract

Diatom is an important group of marine algae and contributes to around 20% of the global photosynthetic carbon fixation. Photosystem I (PSI) of diatoms is associated with a large number of fucoxanthin-chlorophyll a/c proteins (FCPIs). We report the structure of PSI-FCPI from a diatom Chaetoceros gracilis at 2.38 Å resolution by single-particle cryo-electron microscopy. PSI-FCPI is a monomeric supercomplex consisting of 12 core and 24 antenna subunits (FCPIs), and 326 chlorophylls a, 34 chlorophylls c, 102 fucoxanthins, 35 diadinoxanthins, 18 β-carotenes and some electron transfer cofactors. Two subunits designated PsaR and PsaS were found in the core, whereas several subunits were lost. The large number of pigments constitute a unique and huge network ensuring efficient energy harvesting, transfer and dissipation. These results provide a firm structural basis for unraveling the mechanisms of light-energy harvesting, transfer and quenching in the diatom PSI-FCPI, and also important clues to evolutionary changes of PSI-LHCI.

Original languageEnglish
Article number5081
JournalNature communications
Volume11
Issue number1
DOIs
Publication statusPublished - Dec 1 2020

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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