title: Ion antiport accelerates photosynthetic acclimation in fluctuating light environments.
abstract: Many photosynthetic organisms globally, including crops, forests and algae, must grow in environments where the availability of light energy fluctuates dramatically. How photosynthesis maintains high efficiency despite such fluctuations in its energy source remains poorly understood. Here we show that Arabidopsis thaliana K(+) efflux antiporter (KEA3) is critical for high photosynthetic efficiency under fluctuating light. On a shift from dark to low light, or high to low light, kea3 mutants show prolonged dissipation of absorbed light energy as heat. KEA3 localizes to the thylakoid membrane, and allows proton efflux from the thylakoid lumen by proton/potassium antiport. KEA3's activity accelerates the downregulation of pH-dependent energy dissipation after transitions to low light, leading to faster recovery of high photosystem II quantum efficiency and increased CO2 assimilation. Our results reveal a mechanism that increases the efficiency of photosynthesis under fluctuating light.
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, California 94305, USA.
authors.forename: Ute
authors.initials: U
authors.lastname: Armbruster
authors.affiliation: Plant Research Laboratory, Michigan State University, R106 Plant Biology Building, East Lansing, Michigan 48824-1312, USA.
authors.forename: L Ruby
authors.initials: LR
authors.lastname: Carrillo
authors.affiliation: Dpto de Bioquímica, Biología Celular y Molecular de Plantas, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, c/. Profesor Albareda 1, 18008 Granada, Spain.
authors.forename: Kees
authors.initials: K
authors.lastname: Venema
authors.affiliation: Biochemie der Pflanzen, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany.
authors.forename: Lazar
authors.initials: L
authors.lastname: Pavlovic
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, California 94305, USA.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Schmidtmann
authors.affiliation: Department of Global Ecology, Carnegie Institution for Science, 260 Panama Street, Stanford, California 94305, USA.
authors.forename: Ari
authors.initials: A
authors.lastname: Kornfeld
authors.affiliation: Biochemie der Pflanzen, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Jahns
authors.affiliation: Department of Global Ecology, Carnegie Institution for Science, 260 Panama Street, Stanford, California 94305, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Berry
authors.affiliation: Plant Research Laboratory, Michigan State University, R106 Plant Biology Building, East Lansing, Michigan 48824-1312, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Kramer
authors.affiliation: Department of Plant Biology, Carnegie Institution for Science, 260 Panama Street, Stanford, California 94305, USA.
authors.forename: Martin C
authors.initials: MC
authors.lastname: Jonikas
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000378:metabolism*; D001833:Body Temperature Regulation; D015536:Down-Regulation; D004777:Environment; D008027:Light; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D027961:Potassium-Hydrogen Antiporters / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C000589494:KEA3 protein, Arabidopsis; D045332:Photosystem II Protein Complex; D027961:Potassium-Hydrogen Antiporters