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Title | Cryo-EM structure of a plant photosystem II supercomplex with light-harvesting protein Lhcb8 and α-tocopherol. |
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Journal, issue, pages | Nat Plants, Vol. 9, Issue 8, Page 1359-1369, Year 2023 |
Publish date | Aug 7, 2023 |
Authors | Monika Opatíková / Dmitry A Semchonok / David Kopečný / Petr Ilík / Pavel Pospíšil / Iva Ilíková / Pavel Roudnický / Sanja Ćavar Zeljković / Petr Tarkowski / Fotis L Kyrilis / Farzad Hamdi / Panagiotis L Kastritis / Roman Kouřil / |
PubMed Abstract | The heart of oxygenic photosynthesis is the water-splitting photosystem II (PSII), which forms supercomplexes with a variable amount of peripheral trimeric light-harvesting complexes (LHCII). Our ...The heart of oxygenic photosynthesis is the water-splitting photosystem II (PSII), which forms supercomplexes with a variable amount of peripheral trimeric light-harvesting complexes (LHCII). Our knowledge of the structure of green plant PSII supercomplex is based on findings obtained from several representatives of green algae and flowering plants; however, data from a non-flowering plant are currently missing. Here we report a cryo-electron microscopy structure of PSII supercomplex from spruce, a representative of non-flowering land plants, at 2.8 Å resolution. Compared with flowering plants, PSII supercomplex in spruce contains an additional Ycf12 subunit, Lhcb4 protein is replaced by Lhcb8, and trimeric LHCII is present as a homotrimer of Lhcb1. Unexpectedly, we have found α-tocopherol (α-Toc)/α-tocopherolquinone (α-TQ) at the boundary between the LHCII trimer and the inner antenna CP43. The molecule of α-Toc/α-TQ is located close to chlorophyll a614 of one of the Lhcb1 proteins and its chromanol/quinone head is exposed to the thylakoid lumen. The position of α-Toc in PSII supercomplex makes it an ideal candidate for the sensor of excessive light, as α-Toc can be oxidized to α-TQ by high-light-induced singlet oxygen at low lumenal pH. The molecule of α-TQ appears to shift slightly into the PSII supercomplex, which could trigger important structure-functional modifications in PSII supercomplex. Inspection of the previously reported cryo-electron microscopy maps of PSII supercomplexes indicates that α-Toc/α-TQ can be present at the same site also in PSII supercomplexes from flowering plants, but its identification in the previous studies has been hindered by insufficient resolution. |
External links | Nat Plants / PubMed:37550369 |
Methods | EM (single particle) |
Resolution | 2.785 Å |
Structure data | EMDB-16389: Cryo-EM structure of photosystem II C2S2 supercomplex from Norway spruce (Picea babies) at 2.8 Angstrom resolution |
Chemicals | ChemComp-FE2: ChemComp-CLA: ChemComp-PHO: ChemComp-BCR: ChemComp-SQD: ChemComp-LMG: ChemComp-3PH: ChemComp-PL9: ChemComp-LHG: ChemComp-LNL: ChemComp-PAM: ChemComp-DGD: ChemComp-MG: ChemComp-VIV: ChemComp-BCT: ChemComp-DGA: ChemComp-HEM: ChemComp-CHL: ChemComp-LUT: ChemComp-NEX: ChemComp-XAT: ChemComp-HOH: |
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Keywords | MEMBRANE PROTEIN / Membrane protein complex / Photosynthesis / Photosystem / Gymnosperm |