Structure of oligomeric photosystem I is first revealed in a photosynthetic eukaryote

March 31, 2022

A key to understand the evolution from prokaryotes to eukaryotes

A research group of Okayama University together with Kobe University and the RIKEN CSRS succeeded in 3D structural analysis of tetrameric photosystem I (PSI) of glaucophyte alga using cryo-electron microscopy. A PSI tetramer was composed of two PSI dimers bound together. This analysis suggests that PSI tetramers form due to the structures of specific subunits constituting PSI monomers different from those in the other photosynthetic organisms. This is the first report of the PSI oligomer in the photosynthetic eukaryote because all the previously known photosynthetic eukaryotes have PSI monomers. Since PSIs of photosynthetic prokaryotes form trimers or tetramers, the PSI conformation of the glaucophyte suggests that this alga is eukaryotic somewhere in between photosynthetic prokaryotes and eukaryotes.

Original article
Nature Communications doi:10.1038/s41467-022-29303-7
K. Kato, R. Nagao, Y. Ueno, M. Yokono, T. Suzuki, T.-Y. Jiang, N. Dohmae, F. Akita, S. Akimoto, N. Miyazaki, J.-R. Shen,
"Structure of a tetrameric photosystem I from a glaucophyte alga Cyanophora paradoxa".
Naoshi Dohmae
Unit Leader
Biomolecular Characterization Unit