Structure of a C2S2M2N2-type PSII–LHCII supercomplex from the green alga Chlamydomonas reinhardtii

Liangliang Shen, Zihui Huang, Shenghai Chang, Wenda Wang, Jingfen Wang, Tingyun Kuang, Guangye Han, Jian Ren Shen, Xing Zhang

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Photosystem II (PSII) in the thylakoid membranes of plants, algae, and cyanobacteria catalyzes light-induced oxidation of water by which light energy is converted to chemical energy and molecular oxygen is produced. In higher plants and most eukaryotic algae, the PSII core is surrounded by variable numbers of light-harvesting antenna complex II (LHCII), forming a PSII–LHCII supercomplex. In order to harvest energy efficiently at low–light-intensity conditions under water, a complete PSII–LHCII supercomplex (C2S2M2N2) of the green alga Chlamydomonas reinhardtii (Cr) contains more antenna subunits and pigments than the dominant PSII–LHCII supercomplex (C2S2M2) of plants. The detailed structure and energy transfer pathway of the Cr-PSII–LHCII remain unknown. Here we report a cryoelectron microscopy structure of a complete, C2S2M2N2-type PSII–LHCII supercomplex from C. reinhardtii at 3.37-Å resolution. The results show that the Cr-C2S2M2N2 supercomplex is organized as a dimer, with 3 LHCII trimers, 1 CP26, and 1 CP29 peripheral antenna subunits surrounding each PSII core. The N-LHCII trimer partially occupies the position of CP24, which is present in the higher-plant PSII–LHCII but absent in the green alga. The M trimer is rotated relative to the corresponding M trimer in plant PSII–LHCII. In addition, some unique features were found in the green algal PSII core. The arrangement of a huge number of pigments allowed us to deduce possible energy transfer pathways from the peripheral antennae to the PSII core.

Original languageEnglish
Pages (from-to)21246-21255
Number of pages10
JournalProceedings of the National Academy of Sciences of the United States of America
Volume116
Issue number42
DOIs
Publication statusPublished - Oct 15 2019

Keywords

  • Cryoelectron microscopy
  • Light-harvesting complex
  • Photosynthesis
  • Photosystem II
  • Structural analysis

ASJC Scopus subject areas

  • General

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