Cryo-EM structure of photosystem II supercomplex from a green microalga with extreme phototolerance
Year: 2026
Type: article
Abstract: Photosystem II (PSII) is essential for energy conversion during oxygenic photosynthesis in plants and algae. Chlorella ohadii, one of the fastest multiplying green algae, thrives under the harsh desert sun but lacks the standard PSII photoprotective mechanisms involving LhcSR/PsbS proteins or protein phosphorylation. Here, we present the cryo-EM structure of the PSII supercomplex from C. ohadii at 2.9 Å resolution, which is used to determine whether the exceptional resistance to desert conditions has a structural basis in PSII. The structure reveals a distinct PsbO isoform and additional subunits, PsbR and PsbY, which enhance core complex stability through extensive interactions. Furthermore, the trimeric light-harvesting complexes (LHCII) are bound to the PSII core by specific light-harvesting proteins whose down-regulation in response to high-light conditions implies a reduction in the number of bound LHCII trimers. These structural modifications, together with the high accumulation of specific polyamines in the thylakoid membrane, play a key role in maintaining PSII stability and photoprotection, allowing C. ohadii to survive in extreme conditions.
Source: Nature Communications
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $6,990
Funders: European Commission, Deutsche Forschungsgemeinschaft, Ministerstvo Školství, Mládeže a Tělovýchovy, Grantová Agentura České Republiky, Bundesministerium für Bildung und Forschung, Central European Institute of Technology, HORIZON EUROPE Framework Programme, European Regional Development Fund
Awards: Zentrum für Innovationskompetenz HALOmem, Nachwuchsgruppe: Kryo-Elektronenmikroskopie von membrangebundenen Protein-Nanomaschinen, G1761812275, G208869049, G2384880475, G238684906, G2478170884, G2509988855, G3491845953, G3503563290, ERA Chair Holder to establish the electron cryo-microscopy analysis of cellular and artificial nanomachines, G4490333144, G5330073736, Zentrum für Innovationskompetenz - HALOmem - Strategische Investitionen für die Weiterentwicklung 'Struktur und Dynamik von Membranproteinen', G6165425573, G6807155651, National Institute of Virology and Bacteriology, G7534432959, G7662032182, CORONA - CORONAmem - Molekulare Determinaten der differentiellen Wirtsanfälligkeit gegenüber SARS-CoV-2 am Eintrittspunkt, GRK 2467: Intrinsisch ungeordnete Proteine – Molekulare Prinzipien, zelluläre Funktionen und Krankheiten, G7931965296, G8138094502, Identification and characterization of structural entities associated with different lipid phases of plant thylakoid membranes, G8213085267, G8227998441, Czech Infrastructure for Integrative Structural Biology, G941802975
OpenAlex ID: W7119531271