6K33

Structure of PSI-isiA supercomplex from Thermosynechococcus vulcanus

This is a non-PDB format compatible entry.

Summary for 6K33

• Entry DOI: 10.2210/pdb6k33/pdb
• EMDB information: 9908
• Descriptor: Photosystem I P700 chlorophyll a apoprotein A1, Photosystem I reaction center subunit XI, Photosystem I reaction center subunit XII, ... (22 entities in total)
• Functional Keywords: electron transport, photosynthesis
• Biological source: Thermosynechococcus vulcanus; More
• Total number of polymer chains: 54
• Total formula weight: 2096200.88

Authors

Akita, F.,Nagao, R.,Kato, K.,Shen, J.R.,Miyazaki, N. (deposition date: 2019-05-16, release date: 2020-05-20, Last modification date: 2024-10-16)

Primary citation

Akita, F.,Nagao, R.,Kato, K.,Nakajima, Y.,Yokono, M.,Ueno, Y.,Suzuki, T.,Dohmae, N.,Shen, J.R.,Akimoto, S.,Miyazaki, N.
Structure of a cyanobacterial photosystem I surrounded by octadecameric IsiA antenna proteins.
Commun Biol, 3:232-232, 2020

PubMed Abstract: Iron-stress induced protein A (IsiA) is a chlorophyll-binding membrane-spanning protein in photosynthetic prokaryote cyanobacteria, and is associated with photosystem I (PSI) trimer cores, but its structural and functional significance in light harvesting remains unclear. Here we report a 2.7-Å resolution cryo-electron microscopic structure of a supercomplex between PSI core trimer and IsiA from a thermophilic cyanobacterium Thermosynechococcus vulcanus. The structure showed that 18 IsiA subunits form a closed ring surrounding a PSI trimer core. Detailed arrangement of pigments within the supercomplex, as well as molecular interactions between PSI and IsiA and among IsiAs, were resolved. Time-resolved fluorescence spectra of the PSI-IsiA supercomplex showed clear excitation-energy transfer from IsiA to PSI, strongly indicating that IsiA functions as an energy donor, but not an energy quencher, in the supercomplex. These structural and spectroscopic findings provide important insights into the excitation-energy-transfer and subunit assembly mechanisms in the PSI-IsiA supercomplex.

PubMed: 32393811
DOI: 10.1038/s42003-020-0949-6

Experimental method

ELECTRON MICROSCOPY (2.74 Å)