7YCA

Cryo-EM structure of the PSI-LHCI-Lhcp supercomplex from Ostreococcus tauri

Summary for 7YCA

• Entry DOI: 10.2210/pdb7yca/pdb
• EMDB information: 33737
• Descriptor: Lhca1, Photosystem I reaction center subunit II, chloroplastic, Photosystem I reaction centre subunit IV, ... (39 entities in total)
• Functional Keywords: complex, electron transport, photosynthesis
• Biological source: Ostreococcus tauri; More
• Total number of polymer chains: 30
• Total formula weight: 1076390.18

Authors

Shan, J.,Sheng, X.,Ishii, A.,Watanabe, A.,Song, C.,Murata, K.,Minagawa, J.,Liu, Z. (deposition date: 2022-07-01, release date: 2023-04-26, Last modification date: 2024-10-23)

Primary citation

Ishii, A.,Shan, J.,Sheng, X.,Kim, E.,Watanabe, A.,Yokono, M.,Noda, C.,Song, C.,Murata, K.,Liu, Z.,Minagawa, J.
The photosystem I supercomplex from a primordial green alga Ostreococcus tauri harbors three light-harvesting complex trimers.
Elife, 12:-, 2023

PubMed Abstract: As a ubiquitous picophytoplankton in the ocean and an early-branching green alga, is a model prasinophyte species for studying the functional evolution of the light-harvesting systems in photosynthesis. Here, we report the structure and function of the photosystem I (PSI) supercomplex in low light conditions, where it expands its photon-absorbing capacity by assembling with the light-harvesting complexes I (LHCI) and a prasinophyte-specific light-harvesting complex (Lhcp). The architecture of the supercomplex exhibits hybrid features of the plant-type and the green algal-type PSI supercomplexes, consisting of a PSI core, an Lhca1-Lhca4-Lhca2-Lhca3 belt attached on one side and an Lhca5-Lhca6 heterodimer associated on the other side between PsaG and PsaH. Interestingly, nine Lhcp subunits, including one Lhcp1 monomer with a phosphorylated amino-terminal threonine and eight Lhcp2 monomers, oligomerize into three trimers and associate with PSI on the third side between Lhca6 and PsaK. The Lhcp1 phosphorylation and the light-harvesting capacity of PSI were subjected to reversible photoacclimation, suggesting that the formation of PSI-LHCI-Lhcp supercomplex is likely due to a phosphorylation-dependent mechanism induced by changes in light intensity. Notably, this supercomplex did not exhibit far-red peaks in the 77 K fluorescence spectra, which is possibly due to the weak coupling of the chlorophyll 603-609 pair in Lhca1-4.

PubMed: 36951548
DOI: 10.7554/eLife.84488

Experimental method

ELECTRON MICROSCOPY (2.94 Å)