Major light-harvesting complex of photosystemⅡ(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 acidit...Major light-harvesting complex of photosystemⅡ(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 LHCⅡtrimers.We found that the spontaneous formation of a pair of localα-helices from the 310-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 LHCⅡtrimer 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.展开更多
Multistate density functional theory(MSDFT)employing a minimum active space(MAS)is presented to determine charge transfer(CT)and local excited states of bimolecular complexes.MSDFT is a hybrid wave function theory(WFT...Multistate density functional theory(MSDFT)employing a minimum active space(MAS)is presented to determine charge transfer(CT)and local excited states of bimolecular complexes.MSDFT is a hybrid wave function theory(WFT)and density functional theory,in which dynamic correlation is first incorporated in individual determinant configurations using a Kohn–Sham exchangecorrelation functional.Then,nonorthogonal configuration-state interaction is performed to treat static correlation.Because molecular orbitals are optimized separately for each determinant by including Kohn–Sham dynamic correlation,a minimal number of configurations in the active space,essential to representing low-lying excited and CT states of interest,is sufficient to yield the adiabatic states.We found that the present MAS-MSDFT method provides a good description of covalent and CT excited states in comparison with experiments and high-level computational results.Because of the simplicity and interpretive capability through diabatic configuration weights,the method may be useful in dynamic simulations of CT and nonadiabatic processes.展开更多
基金supported by the National Natural Science Foundation of China(21433014,11721404,21533003)the Ministry of Science and Technology(2017YFB0203400)+1 种基金Chinese Academy of Sciences Innovation Program(KJCX2-YW-W25)the National Institutes of Health(GM46736,GM64742)。
文摘Major light-harvesting complex of photosystemⅡ(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 LHCⅡtrimers.We found that the spontaneous formation of a pair of localα-helices from the 310-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 LHCⅡtrimer 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.
基金This work was partially supported by grants from the Shenzhen Municipal Science and Technology Innovation Commission(KQTD2017-0330155106581)the Key-area Research and Development Program of Guangdong Province(2020B0101350001)+1 种基金the National Natural Science Foundation of China(Grant No.21533003)The study was completed for the excimer complex relevant in photoreceptors at Minnesota,which was partially supported by the National Institutes of Health(Grant Number GM046736).The authors thank Dr.Peng Bao for discussion and assistance.Computing resources were provided by the computing facilities at Shenzhen Bay Laboratory,and part of the computations were performed in 2020 at the Minnesota Supercomputing Institute.
文摘Multistate density functional theory(MSDFT)employing a minimum active space(MAS)is presented to determine charge transfer(CT)and local excited states of bimolecular complexes.MSDFT is a hybrid wave function theory(WFT)and density functional theory,in which dynamic correlation is first incorporated in individual determinant configurations using a Kohn–Sham exchangecorrelation functional.Then,nonorthogonal configuration-state interaction is performed to treat static correlation.Because molecular orbitals are optimized separately for each determinant by including Kohn–Sham dynamic correlation,a minimal number of configurations in the active space,essential to representing low-lying excited and CT states of interest,is sufficient to yield the adiabatic states.We found that the present MAS-MSDFT method provides a good description of covalent and CT excited states in comparison with experiments and high-level computational results.Because of the simplicity and interpretive capability through diabatic configuration weights,the method may be useful in dynamic simulations of CT and nonadiabatic processes.
