6JEO

Structure of PSI tetramer from Anabaena

This is a non-PDB format compatible entry.

Summary for 6JEO

• Entry DOI: 10.2210/pdb6jeo/pdb
• EMDB information: 9807
• Descriptor: Photosystem I P700 chlorophyll a apoprotein A1, Photosystem I reaction center subunit XI, Photosystem I reaction center subunit XII, ... (19 entities in total)
• Functional Keywords: photosystem, photosynthesis
• Biological source: Nostoc sp. (strain PCC 7120 / SAG 25.82 / UTEX 2576); More
• Total number of polymer chains: 48
• Total formula weight: 1459789.49

Authors

Kato, K.,Nagao, R.,Shen, J.R.,Miyazaki, N.,Akita, F. (deposition date: 2019-02-06, release date: 2019-11-13, Last modification date: 2025-04-09)

Primary citation

Kato, K.,Nagao, R.,Jiang, T.Y.,Ueno, Y.,Yokono, M.,Chan, S.K.,Watanabe, M.,Ikeuchi, M.,Shen, J.R.,Akimoto, S.,Miyazaki, N.,Akita, F.
Structure of a cyanobacterial photosystem I tetramer revealed by cryo-electron microscopy.
Nat Commun, 10:4929-4929, 2019

PubMed 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.

PubMed: 31666526
DOI: 10.1038/s41467-019-12942-8

Experimental method

ELECTRON MICROSCOPY (3.3 Å)