title: Blue-light-controlled photoprotection in plants at the level of the photosynthetic antenna complex LHCII.
abstract: Plants have developed several adaptive regulatory mechanisms, operating at all the organization levels, to optimize utilization of light energy and to protect themselves against over-excitation-related damage. We report activity of a previously unknown possible regulatory mechanism that operates at the molecular level of the major photosynthetic pigment-protein complexes of plants, LHCII. This mechanism is driven exclusively by blue light, operates in the trimeric but not in the monomeric complex, and results in singlet excitation quenching leading to thermal energy dissipation. The conclusions are based on single molecule fluorescence lifetime analysis, direct measurements of thermal energy dissipation by photo-thermal spectroscopy, and on fluorescence spectroscopy. Possible molecular mechanisms involved in the blue-light-induced photoprotective effect are discussed, including xanthophyll photo-isomerization and the thermo-optic effect.
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20 031 Lublin, Poland. wieslaw.gruszecki@umcs.pl
authors.forename: Wieslaw I
authors.initials: WI
authors.lastname: Gruszecki
authors.forename: Rafal
authors.initials: R
authors.lastname: Luchowski
authors.forename: Monika
authors.initials: M
authors.lastname: Zubik
authors.forename: Wojciech
authors.initials: W
authors.lastname: Grudzinski
authors.forename: Ewa
authors.initials: E
authors.lastname: Janik
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Gospodarek
authors.forename: Jacek
authors.initials: J
authors.lastname: Goc
authors.forename: Zygmunt
authors.initials: Z
authors.lastname: Gryczynski
authors.forename: Ignacy
authors.initials: I
authors.lastname: Gryczynski
mesh_terms: D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010788:Photosynthesis / Q000528:radiation effects*; D055503:Protein Multimerization; D018724:Spinacia oleracea / Q000378:metabolism* / Q000528:radiation effects*; D013997:Time Factors
chemical_list: D045342:Light-Harvesting Protein Complexes; D002734:Chlorophyll; D000077194:Chlorophyll A