A blue-light photoreceptor mediates the feedback regulation of photosynthesis.
In plants and algae, light serves both as the energy source for photosynthesis and a biological signal that triggers cellular responses via specific sensory photoreceptors. Red light is perceived by bilin-containing phytochromes and blue light by the flavin-containing cryptochromes and/or phototropins (PHOTs), the latter containing two photosensory light, oxygen, or voltage (LOV) domains. Photoperception spans several orders of light intensity, ranging from far below the threshold for photosynthesis to values beyond the capacity of photosynthetic CO2assimilation. Excess light may cause oxidative damage and cell death, processes prevented by enhanced thermal dissipation via high-energy quenching (qE), a key photoprotective response. Here we show the existence of a molecular link between photoreception, photosynthesis, and photoprotection in the green alga Chlamydomonas reinhardtii. We show that PHOT controls qE by inducing the expression of the qE effector protein LHCSR3 (light-harvesting complex stress-related protein 3) in high light intensities. This control requires blue-light perception by LOV domains on PHOT, LHCSR3 induction through PHOT kinase, and light dissipation in photosystem II via LHCSR3. Mutants deficient in the PHOT gene display severely reduced fitness under excessive light conditions, indicating that the sensing, utilization, and dissipation of light is a concerted process that plays a vital role in microalgal acclimation to environments of variable light intensities.
Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Université Grenoble Alpes, Institut National Recherche Agronomique, Institut de Biosciences et Biotechnologies de Grenoble, (BIG), CEA Grenoble, F-38054 Grenoble CEDEX 9, France.
Dimitris
D
Petroutsos
Division of Environmental Photobiology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan.|Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan.|Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan.
Ryutaro
R
Tokutsu
Department of Environmental Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8578, Japan.
Shinichiro
S
Maruyama
Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Université Grenoble Alpes, Institut National Recherche Agronomique, Institut de Biosciences et Biotechnologies de Grenoble, (BIG), CEA Grenoble, F-38054 Grenoble CEDEX 9, France.
Serena
S
Flori
Humboldt University of Berlin, Institute of Biology, Experimental Biophysics, Invalidenstraße 42, D-10115 Berlin, Germany.
Andre
A
Greiner
Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Université Grenoble Alpes, Institut National Recherche Agronomique, Institut de Biosciences et Biotechnologies de Grenoble, (BIG), CEA Grenoble, F-38054 Grenoble CEDEX 9, France.|Institute of Plant Biology and Biotechnology, University of Münster, Münster 48143, Germany.
Leonardo
L
Magneschi
Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Université Grenoble Alpes, Institut National Recherche Agronomique, Institut de Biosciences et Biotechnologies de Grenoble, (BIG), CEA Grenoble, F-38054 Grenoble CEDEX 9, France.
Loic
L
Cusant
Physical and Biophysical Chemistry, Bielefeld University, 33615 Bielefeld, Germany.
Tilman
T
Kottke
Institute of General Botany and Plant Physiology, Friedrich Schiller University, 07743 Jena, Germany.
Maria
M
Mittag
Humboldt University of Berlin, Institute of Biology, Experimental Biophysics, Invalidenstraße 42, D-10115 Berlin, Germany.
Peter
P
Hegemann
Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique, Commissariat à l'Energie Atomique et aux Energies Alternatives, Université Grenoble Alpes, Institut National Recherche Agronomique, Institut de Biosciences et Biotechnologies de Grenoble, (BIG), CEA Grenoble, F-38054 Grenoble CEDEX 9, France.
Giovanni
G
Finazzi
Division of Environmental Photobiology, National Institute for Basic Biology, Nishigonaka 38, Myodaiji, Okazaki 444-8585, Japan.|Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies, Okazaki 444-8585, Japan.|Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan.
Jun
J
Minagawa
D000064:Acclimatization / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects*; D003116:Color; D025461:Feedback, Physiological / Q000528:radiation effects*; D008027:Light; D055537:Light Signal Transduction / Q000528:radiation effects*; D045342:Light-Harvesting Protein Complexes / Q000096:biosynthesis / Q000378:metabolism; D010788:Photosynthesis / Q000528:radiation effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D056949:Phototropins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000737:chemistry / Q000378:metabolism
D045342:Light-Harvesting Protein Complexes; D045332:Photosystem II Protein Complex; D056949:Phototropins; D011494:Protein Kinases