Dynamical and allosteric regulation of photoprotection in light harvesting complex II

Major light-harvesting complex of photosystem II (LHCII) plays a dual role in light-harvesting and excited energy dissipation to protect photodamage from excess energy. The regulatory switch is induced by increased acidity, temperature or both. However, the molecular origin of the protein dynamics a...

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Bibliographic Details
Published in:Science China. Chemistry 2020-08, Vol.63 (8), p.1121-1133
Main Authors: Li, Hao, Wang, Yingjie, Ye, Manping, Li, Shanshan, Li, Deyong, Ren, Haisheng, Wang, Mohan, Du, Luchao, Li, Heng, Veglia, Gianluigi, Gao, Jiali, Weng, Yuxiang
Format: Article
Language:English
Subjects:
Carotenoids
Chemistry
Chemistry and Materials Science
Chemistry/Food Science
Chlorophyll
Crystal structure
Energy dissipation
Energy harvesting
Helices
Light
Molecular dynamics
NMR
Nuclear magnetic resonance
Photosynthesis
Proteins
Quenching
Temperature
Trimers
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Summary:Major light-harvesting complex of photosystem II (LHCII) plays a dual role in light-harvesting and excited energy dissipation to protect photodamage from excess energy. The regulatory switch is induced by increased acidity, temperature or both. However, the molecular origin of the protein dynamics at the atomic level is still unknown. We carried out temperature-jump time-resolved infrared spectroscopy and molecular dynamics simulations to determine the energy quenching dynamics and conformational changes of LHCII trimers. We found that the spontaneous formation of a pair of local α-helices from the 3 10 -helix E/loop and the C-terminal coil of the neighboring monomer, in response to the increased environmental temperature and/or acidity, induces a scissoring motion of transmembrane helices A and B, shifting the conformational equilibrium to a more open state, with an increased angle between the associated carotenoids. The dynamical and allosteric conformation change leads to close contacts between carotenoid lutein 1 and chlorophyll pigment 612, facilitating the fluorescence quenching. Based on these results, we suggest a unified mechanism by which the LHCII trimer controls the dissipation of excess excited energy in response to increased temperature and acidity, as an intrinsic result of intense sun light in plant photosynthesis.
ISSN:1674-7291
1869-1870
DOI:10.1007/s11426-020-9771-2