Cryo-EM structure of a plant photosystem II supercomplex with light-harvesting protein Lhcb8 and α-tocopherol

0575717 - ÚEB 2024 RIV GB eng J - Journal Article
Opatíková, M. - Semchonok, D. A. - Kopečný, D. - Ilík, P. - Pospíšil, P. - Ilíková, Iva - Roudnický, P. - Zeljković, S. Ć. - Tarkowski, P. - Kyrilis, F. L. - Hamdi, F. - Kastritis, P. L. - Kouřil, R.
Cryo-EM structure of a plant photosystem II supercomplex with light-harvesting protein Lhcb8 and α-tocopherol.
Nature Plants. Roč. 9, č. 8 (2023), s. 1359-1369. ISSN 2055-026X. E-ISSN 2055-0278
R&D Projects: GA ČR(CZ) GA21-05497S; GA MŠMT(CZ) EF16_019/0000827
Institutional support: RVO:61389030
Keywords : ALPHA-TOCOPHEROL QUINONE * COMPLEX * LHCII
OECD category: Biochemistry and molecular biology
Impact factor: 18, year: 2022
Method of publishing: Open access
https://doi.org/10.1038/s41477-023-01483-0

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.
Permanent Link: https://hdl.handle.net/11104/0345462