A possible molecular basis for photoprotection in the minor antenna proteins of plants |
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Authors: | Kieran F. Fox Caner Ünlü Vytautas Balevičius Baboo Narottamsing Ramdour Carina Kern Xiaowei Pan Mei Li Herbert van Amerongen Christopher D.P. Duffy |
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Affiliation: | 1. School of Biological and Chemical Sciences, Queen Mary University of London, Mile End, London E1 4NS, United Kingdom;2. Laboratory of Biophysics, Wageningen University & Research, P.O. Box 8128, 6708WE Wageningen, The Netherlands;3. National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15th Datun Road, Chaoyang District, Beijing 100101, China;4. MicroSpectroscopy Research Facility, Wageningen University & Research, P.O. Box 8128, 6708WE Wageningen, The Netherlands |
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Abstract: | The bioenergetics of light-harvesting by photosynthetic antenna proteins in higher plants is well understood. However, investigation into the regulatory non-photochemical quenching (NPQ) mechanism, which dissipates excess energy in high light, has led to several conflicting models. It is generally accepted that the major photosystem II antenna protein, LHCII, is the site of NPQ, although the minor antenna complexes (CP24/26/29) are also proposed as alternative/additional NPQ sites. LHCII crystals were shown to exhibit the short excitation lifetime and several spectral signatures of the quenched state. Subsequent structure-based models showed that this quenching could be explained by slow energy trapping by the carotenoids, in line with one of the proposed models. Using Fluorescence Lifetime Imaging Microscopy (FLIM) we show that the crystal structure of CP29 corresponds to a strongly quenched conformation. Using a structure-based theoretical model we show that this quenching may be explained by the same slow, carotenoid-mediated quenching mechanism present in LHCII crystals. |
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Keywords: | Non-photochemical quenching Light-harvesting Carotenoids Photosystem II Minor antenna Photoprotection |
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