title: Economic photoprotection in photosystem II that retains a complete light-harvesting system with slow energy traps.
abstract: The light-harvesting antenna of higher plant photosystem II has an intrinsic capability for self-defence against intense sunlight. The thermal dissipation of excess energy can be measured as the non-photochemical quenching of chlorophyll fluorescence. It has recently been proposed that the transition between the light-harvesting and self-defensive modes is associated with a reorganization of light-harvesting complexes. Here we show that despite structural changes, the photosystem II cross-section does not decrease. Our study reveals that the efficiency of energy trapping by the non-photochemical quencher(s) is lower than the efficiency of energy capture by the reaction centres. Consequently, the photoprotective mechanism works effectively for closed rather than open centres. This type of defence preserves the exceptional efficiency of electron transport in a broad range of light intensities, simultaneously ensuring high photosynthetic productivity and, under hazardous light conditions, sufficient photoprotection for both the reaction centre and the light-harvesting pigments of the antenna.
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, Fogg Building, London E1 4NS, UK.
authors.forename: Erica
authors.initials: E
authors.lastname: Belgio
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, Fogg Building, London E1 4NS, UK.
authors.forename: Ekaterina
authors.initials: E
authors.lastname: Kapitonova
authors.affiliation: 1] Department of Theoretical Physics, Faculty of Physics, Vilnius University, Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania [2] Institute of Physics, Center for Physical Sciences and Technology, A. Gostauto 11, LT-01108 Vilnius, Lithuania.
authors.forename: Jevgenij
authors.initials: J
authors.lastname: Chmeliov
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, Fogg Building, London E1 4NS, UK.
authors.forename: Christopher D P
authors.initials: CD
authors.lastname: Duffy
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, Fogg Building, London E1 4NS, UK.
authors.forename: Petra
authors.initials: P
authors.lastname: Ungerer
authors.affiliation: 1] Department of Theoretical Physics, Faculty of Physics, Vilnius University, Saulėtekio Avenue 9, LT-10222 Vilnius, Lithuania [2] Institute of Physics, Center for Physical Sciences and Technology, A. Gostauto 11, LT-01108 Vilnius, Lithuania.
authors.forename: Leonas
authors.initials: L
authors.lastname: Valkunas
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, Fogg Building, London E1 4NS, UK.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Ruban
mesh_terms: D017360:Arabidopsis / Q000502:physiology*; D045342:Light-Harvesting Protein Complexes / Q000502:physiology*; D008954:Models, Biological; D010788:Photosynthesis / Q000502:physiology; D045332:Photosystem II Protein Complex / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology; D012993:Solar Energy
chemical_list: D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex