An irradiation density dependent energy relaxation in plant photosystem II antenna assembly
Autor: | Mingdong Yao, Yang Zheng, Wenming Tian, Rongrong Cui, Liezheng Deng, Jun Chen, Heping Yang, Guohe Sha |
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Rok vydání: | 2015 |
Předmět: |
Chlorophyll
LHCII Photosynthetic reaction centre Light Photosystem II Light-Harvesting Protein Complexes Biophysics macromolecular substances Photochemistry Biochemistry Irradiation Chlorophyll fluorescence Photoprotection Chemistry Photosystem II Protein Complex food and beverages Cell Biology Plants Fluorescence Photoexcitation Spectrometry Fluorescence Energy relaxation Non-photochemical quenching Relaxation (physics) |
Zdroj: | Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1847:286-293 |
ISSN: | 0005-2728 |
Popis: | Plant photosystem II (PSII) is a multicomponent pigment-protein complex that harvests sunlight via pigments photoexcitation, and converts light energy into chemical energy. Against high light induced photodamage, excess light absorption of antenna pigments triggers the operation of photoprotection mechanism in plant PSII. Non-photochemical energy relaxation as a major photoprotection way is essentially correlated to the excess light absorption. Here we investigate the energy relaxation of plant PSII complexes with varying incident light density, by performing steady-state and transient chlorophyll fluorescence measurements of the grana membranes (called as BBY), functional moiety PSII reaction center and isolated light-harvesting complex LHCII under excess light irradiation. Based on the chlorophyll fluorescence decays of these samples, it is found that an irradiation density dependent energy relaxation occurs in the LHCII assemblies, especially in the antenna assembly of PSII supercomplexes in grana membrane, when irradiation increases to somewhat higher density levels. Correspondingly, the average chlorophyll fluorescence lifetime of the highly isolated BBY fragments gradually decreases from ~ 1680 to ~ 1360 ps with increasing the irradiation density from 6.1 × 109 to 5.5 × 1010 photon cm− 2 pulse− 1. Analysis of the relation of fluorescence decay change to the aggregation extent of LHCIIs suggests that a dense arrangement of trimeric LHCIIs is likely the structural base for the occurrence of this irradiation density dependent energy relaxation. Once altering the irradiation density, this energy relaxation is quickly reversible, implying that it may play an important role in photoprotection of plant PSII. |
Databáze: | OpenAIRE |
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