Structure of a cyanobacterial photosystem I tetramer revealed by cryo-electron microscopy

Koji Kato; Ryo Nagao; Tian Yi Jiang; Yoshifumi Ueno; Makio Yokono; Siu Kit Chan; Mai Watanabe; Masahiko Ikeuchi; Jian Ren Shen; Seiji Akimoto; Naoyuki Miyazaki; Fusamichi Akita

doi:10.1038/s41467-019-12942-8

Structure of a cyanobacterial photosystem I tetramer revealed by cryo-electron microscopy

Koji Kato, Ryo Nagao, Tian Yi Jiang, Yoshifumi Ueno, Makio Yokono, Siu Kit Chan, Mai Watanabe, Masahiko Ikeuchi, Jian Ren Shen, Seiji Akimoto, Naoyuki Miyazaki, Fusamichi Akita

Research Institute for Interdisciplinary Science

Research output: Contribution to journal › Article › peer-review

39 Citations (Scopus)

Abstract

Photosystem I (PSI) functions to harvest light energy for conversion into chemical energy. The organisation of PSI is variable depending on the species of organism. Here we report the structure of a tetrameric PSI core isolated from a cyanobacterium, Anabaena sp. PCC 7120, analysed by single-particle cryo-electron microscopy (cryo-EM) at 3.3 Å resolution. The PSI tetramer has a C2 symmetry and is organised in a dimer of dimers form. The structure reveals interactions at the dimer-dimer interface and the existence of characteristic pigment orientations and inter-pigment distances within the dimer units that are important for unique excitation energy transfer. In particular, characteristic residues of PsaL are identified to be responsible for the formation of the tetramer. Time-resolved fluorescence analyses showed that the PSI tetramer has an enhanced excitation-energy quenching. These structural and spectroscopic findings provide insights into the physiological significance of the PSI tetramer and evolutionary changes of the PSI organisations.

Original language	English
Article number	4929
Journal	Nature communications
Volume	10
Issue number	1
DOIs	https://doi.org/10.1038/s41467-019-12942-8
Publication status	Published - Dec 1 2019

ASJC Scopus subject areas

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

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title = "Structure of a cyanobacterial photosystem I tetramer revealed by cryo-electron microscopy",

abstract = "Photosystem I (PSI) functions to harvest light energy for conversion into chemical energy. The organisation of PSI is variable depending on the species of organism. Here we report the structure of a tetrameric PSI core isolated from a cyanobacterium, Anabaena sp. PCC 7120, analysed by single-particle cryo-electron microscopy (cryo-EM) at 3.3 {\AA} resolution. The PSI tetramer has a C2 symmetry and is organised in a dimer of dimers form. The structure reveals interactions at the dimer-dimer interface and the existence of characteristic pigment orientations and inter-pigment distances within the dimer units that are important for unique excitation energy transfer. In particular, characteristic residues of PsaL are identified to be responsible for the formation of the tetramer. Time-resolved fluorescence analyses showed that the PSI tetramer has an enhanced excitation-energy quenching. These structural and spectroscopic findings provide insights into the physiological significance of the PSI tetramer and evolutionary changes of the PSI organisations.",

author = "Koji Kato and Ryo Nagao and Jiang, {Tian Yi} and Yoshifumi Ueno and Makio Yokono and Chan, {Siu Kit} and Mai Watanabe and Masahiko Ikeuchi and Shen, {Jian Ren} and Seiji Akimoto and Naoyuki Miyazaki and Fusamichi Akita",

note = "Funding Information: This work was supported by the Platform Project for Supporting Drug Discovery and Life Science Research (Basis for Supporting Innovative Drug Discovery and Life Science Research (BINDS) from AMED under Grant Number JP18am0101072j002 (to N.M.), and JSPS KAKENHI Nos. JP19H04726 (to R.N.), JP17H0643410 (to J.-R.S.) and JP16H06553 (to S.A.). Publisher Copyright: {\textcopyright} 2019, The Author(s).",

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doi = "10.1038/s41467-019-12942-8",

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AU - Kato, Koji

AU - Nagao, Ryo

AU - Jiang, Tian Yi

AU - Ueno, Yoshifumi

AU - Yokono, Makio

AU - Chan, Siu Kit

AU - Watanabe, Mai

AU - Ikeuchi, Masahiko

AU - Shen, Jian Ren

AU - Akimoto, Seiji

AU - Miyazaki, Naoyuki

AU - Akita, Fusamichi

N1 - Funding Information: This work was supported by the Platform Project for Supporting Drug Discovery and Life Science Research (Basis for Supporting Innovative Drug Discovery and Life Science Research (BINDS) from AMED under Grant Number JP18am0101072j002 (to N.M.), and JSPS KAKENHI Nos. JP19H04726 (to R.N.), JP17H0643410 (to J.-R.S.) and JP16H06553 (to S.A.). Publisher Copyright: © 2019, The Author(s).

PY - 2019/12/1

Y1 - 2019/12/1

N2 - Photosystem I (PSI) functions to harvest light energy for conversion into chemical energy. The organisation of PSI is variable depending on the species of organism. Here we report the structure of a tetrameric PSI core isolated from a cyanobacterium, Anabaena sp. PCC 7120, analysed by single-particle cryo-electron microscopy (cryo-EM) at 3.3 Å resolution. The PSI tetramer has a C2 symmetry and is organised in a dimer of dimers form. The structure reveals interactions at the dimer-dimer interface and the existence of characteristic pigment orientations and inter-pigment distances within the dimer units that are important for unique excitation energy transfer. In particular, characteristic residues of PsaL are identified to be responsible for the formation of the tetramer. Time-resolved fluorescence analyses showed that the PSI tetramer has an enhanced excitation-energy quenching. These structural and spectroscopic findings provide insights into the physiological significance of the PSI tetramer and evolutionary changes of the PSI organisations.

AB - Photosystem I (PSI) functions to harvest light energy for conversion into chemical energy. The organisation of PSI is variable depending on the species of organism. Here we report the structure of a tetrameric PSI core isolated from a cyanobacterium, Anabaena sp. PCC 7120, analysed by single-particle cryo-electron microscopy (cryo-EM) at 3.3 Å resolution. The PSI tetramer has a C2 symmetry and is organised in a dimer of dimers form. The structure reveals interactions at the dimer-dimer interface and the existence of characteristic pigment orientations and inter-pigment distances within the dimer units that are important for unique excitation energy transfer. In particular, characteristic residues of PsaL are identified to be responsible for the formation of the tetramer. Time-resolved fluorescence analyses showed that the PSI tetramer has an enhanced excitation-energy quenching. These structural and spectroscopic findings provide insights into the physiological significance of the PSI tetramer and evolutionary changes of the PSI organisations.

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Structure of a cyanobacterial photosystem I tetramer revealed by cryo-electron microscopy

Abstract

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