8IWZ

Cryo-EM structure of unprotonated LHCII in detergent solution at low pH value

Summary for 8IWZ

• Entry DOI: 10.2210/pdb8iwz/pdb
• EMDB information: 35784
• Descriptor: Chlorophyll a-b binding protein, chloroplastic, CHLOROPHYLL B, CHLOROPHYLL A, ... (7 entities in total)
• Functional Keywords: lhcii, light-harvesting complex, photosystem ii, plant protein
• Biological source: Spinacia oleracea (spinach)
• Total number of polymer chains: 3
• Total formula weight: 117458.24

Authors

Ruan, M.X.,Ding, W. (deposition date: 2023-03-31, release date: 2023-09-06, Last modification date: 2023-10-04)

Primary citation

Ruan, M.,Li, H.,Zhang, Y.,Zhao, R.,Zhang, J.,Wang, Y.,Gao, J.,Wang, Z.,Wang, Y.,Sun, D.,Ding, W.,Weng, Y.
Cryo-EM structures of LHCII in photo-active and photo-protecting states reveal allosteric regulation of light harvesting and excess energy dissipation.
Nat.Plants, 9:1547-1557, 2023

PubMed Abstract: The major light-harvesting complex of photosystem II (LHCII) has a dual regulatory function in a process called non-photochemical quenching to avoid the formation of reactive oxygen. LHCII undergoes reversible conformation transitions to switch between a light-harvesting state for excited-state energy transfer and an energy-quenching state for dissipating excess energy under full sunshine. Here we report cryo-electron microscopy structures of LHCII in membrane nanodiscs, which mimic in vivo LHCII, and in detergent solution at pH 7.8 and 5.4, respectively. We found that, under low pH conditions, the salt bridges at the lumenal side of LHCII are broken, accompanied by the formation of two local α-helices on the lumen side. The formation of α-helices in turn triggers allosterically global protein conformational change, resulting in a smaller crossing angle between transmembrane helices. The fluorescence decay rates corresponding to different conformational states follow the Dexter energy transfer mechanism with a characteristic transition distance of 5.6 Å between Lut1 and Chl612. The experimental observations are consistent with the computed electronic coupling strengths using multistate density function theory.

PubMed: 37653340
DOI: 10.1038/s41477-023-01500-2

Experimental method

ELECTRON MICROSCOPY (2.52 Å)