The nature of self-regulation in photosynthetic light-harvesting antenna
| Autor: | Ramūnas Augulis, Alexander V. Ruban, Leonas Valkunas, Egidijus Songaila, Jevgenij Chmeliov, Christopher D. P. Duffy, Andrius Gelzinis |
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| Rok vydání: | 2016 |
| Předmět: |
0301 basic medicine
Quenching Materials science Light-Harvesting Protein Complexes Plant Science Atmospheric temperature range 010402 general chemistry Photosynthesis 01 natural sciences Fluorescence 0104 chemical sciences Plant Leaves 03 medical and health sciences 030104 developmental biology Chemical physics Spinacia oleracea Photoprotection Excited state Botany Antenna (radio) Excitation |
| Zdroj: | Nature plants. 2(5) |
| ISSN: | 2055-0278 |
| Popis: | The photosynthetic apparatus of green plants is well known for its extremely high efficiency that allows them to operate under dim light conditions. On the other hand, intense sunlight may result in overexcitation of the light-harvesting antenna and the formation of reactive compounds capable of ‘burning out’ the whole photosynthetic unit. Non-photochemical quenching is a self-regulatory mechanism utilized by green plants on a molecular level that allows them to safely dissipate the detrimental excess excitation energy as heat. Although it is believed to take place in the plant's major light-harvesting complexes (LHC) II, there is still no consensus regarding its molecular nature. To get more insight into its physical origin, we performed high-resolution time-resolved fluorescence measurements of LHCII trimers and their aggregates across a wide temperature range. Based on simulations of the excitation energy transfer in the LHCII aggregate, we associate the red-emitting state, having fluorescence maximum at ∼700 nm, with the partial mixing of excitonic and chlorophyll–chlorophyll charge transfer states. On the other hand, the quenched state has a totally different nature and is related to the incoherent excitation transfer to the short-lived carotenoid excited states. Our results also show that the required level of photoprotection in vivo can be achieved by a very subtle change in the number of LHCIIs switched to the quenched state. Non-photochemical quenching protects the photosynthetic apparatus of plants from damage in high light conditions. High-resolution time-resolved fluorescence measurements now show that the level of this photoprotection is regulated by subtle changes in the number of LHCIIs in a quenched state. |
| Databáze: | OpenAIRE |
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