title: A chloroplast "wake up" mechanism: Illumination with weak light activates the photosynthetic antenna function in dark-adapted plants.
abstract: The efficient and fluent operation of photosynthesis in plants relies on activity of pigment-protein complexes called antenna, absorbing light and transferring excitations toward the reaction centers. Here we show, based on the results of the fluorescence lifetime imaging analyses of single chloroplasts, that pigment-protein complexes, in dark-adapted plants, are not able to act effectively as photosynthetic antennas, due to pronounced, adverse excitation quenching. It appeared that the antenna function could be activated by a short (on a minute timescale) illumination with light of relatively low intensity, substantially below the photosynthesis saturation threshold. The low-light-induced activation of the antenna function was attributed to phosphorylation of the major accessory light-harvesting complex LHCII, based on the fact that such a mechanism was not observed in the stn7 Arabidopsis thaliana mutant, with impaired LHCII phosphorylation. It is proposed that the protein phosphorylation-controlled change in the LHCII clustering ability provides mechanistic background for this regulatory process.
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland; Department of Cell Biology, Institute of Biology, Maria Curie-Sklodowska University, 20-031 Lublin, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Janik
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland.
authors.forename: Joanna
authors.initials: J
authors.lastname: Bednarska
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland; Institute of Agrophysics, Polish Academy of Sciences, Doswiadczalna 4, 20-290 Lublin, Poland.
authors.forename: Monika
authors.initials: M
authors.lastname: Zubik
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland.
authors.forename: Rafal
authors.initials: R
authors.lastname: Luchowski
authors.affiliation: Department of Metabolic Regulation, Institute of Biochemistry, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland.
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Mazur
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland; Faculty of Pharmacy, Medical University, 20-093 Lublin, Poland.
authors.forename: Karol
authors.initials: K
authors.lastname: Sowinski
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland.
authors.forename: Wojciech
authors.initials: W
authors.lastname: Grudzinski
authors.affiliation: Department of Metabolic Regulation, Institute of Biochemistry, Faculty of Biology, University of Warsaw, 02-096 Warsaw, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Garstka
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland. Electronic address: wieslaw.gruszecki@umcs.pl.
authors.forename: Wieslaw I
authors.initials: WI
authors.lastname: Gruszecki
mesh_terms: D017360:Arabidopsis / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D008027:Light; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010788:Photosynthesis
chemical_list: D045342:Light-Harvesting Protein Complexes
keywords: Chloroplast imaging; Light-harvesting complexes; Phosphorylation; Photosynthesis