Journal Article

The pigment-protein network of a diatom photosystem II–light-harvesting antenna supercomplex

Zhao, Songhao, Xu, Caizhe, Wang, Wenda, Liu, Desheng, Shen, Jian-Ren, Kuang, Tingyun, Sui, Sen-Fang, Pi, Xiong, Han, Guangye

2019

Overview

Photosynthetic organisms use huge arrays of pigments to draw light energy into the core of photosystem II. The arrangement of these pigments influences how much energy reaches the reaction center. Pi et al. determined the structure of photosystem II from a diatom in complex with an antenna of fucoxanthin–chlorophyll a/c binding proteins (FCPs) (see the Perspective by Büchel). The specialized pigments in this complex allow microalgae to harvest light within a wide range of the visible spectrum. The FCPs are arranged in a pattern analogous to light-harvesting complexes in plants. Science , this issue p. eaax4406 ; see also p. 447 The cryo-EM structure of a diatom photosystem II complex suggests energy transfer and dissipation pathways. Diatoms play important roles in global primary productivity and biogeochemical cycling of carbon, in part owing to the ability of their photosynthetic apparatus to adapt to rapidly changing light intensity. We report a cryo–electron microscopy structure of the photosystem II (PSII)–fucoxanthin (Fx) chlorophyll (Chl) a/c binding protein (FCPII) supercomplex from the centric diatom Chaetoceros gracilis . The supercomplex comprises two protomers, each with two tetrameric and three monomeric FCPIIs around a PSII core that contains five extrinsic oxygen-evolving proteins at the lumenal surface. The structure reveals the arrangement of a huge pigment network that contributes to efficient light energy harvesting, transfer, and dissipation processes in the diatoms.

• Publisher: American Association for the Advancement of Science,The American Association for the Advancement of Science
• Subject: Algae / Antenna arrays / Antennas / Aquatic microorganisms / Bacillariophyceae / Biogeochemical cycles / Carbon cycle / Carotenoids / Chaetoceros gracilis / Chemical energy / Chlorophyll / Chlorophyll Binding Proteins - chemistry / Cryoelectron Microscopy / Cyanobacteria / Diatoms - enzymology / Electron microscopy / Energy / Energy harvesting / Energy transfer / Evolution / Fucoxanthin / Light / Light intensity / Luminous intensity / Microscopy / Molecular weight / Monomers / Organic chemistry / Organisms / Oxygen / Photosynthesis / Photosynthetic apparatus / Photosystem II / Photosystem II Protein Complex - chemistry / Pigments / Protein Multimerization / Proteins / Reaction centers / RESEARCH ARTICLE SUMMARY / Trimers / Visible spectrum / Water splitting