title: Phosphorylation of the vacuolar anion exchanger AtCLCa is required for the stomatal response to abscisic acid.
abstract: Eukaryotic anion/proton exchangers of the CLC (chloride channel) family mediate anion fluxes across intracellular membranes. The Arabidopsis thaliana anion/proton exchanger AtCLCa is involved in vacuolar accumulation of nitrate. We investigated the role of AtCLCa in leaf guard cells, a specialized plant epidermal cell that controls gas exchange and water loss through pores called stomata. We showed that AtCLCa not only fulfilled the expected role of accumulating anions in the vacuole during stomatal opening but also mediated anion release during stomatal closure in response to the stress hormone abscisic acid (ABA). We found that this dual role resulted from a phosphorylation-dependent change in the activity of AtCLCa. The protein kinase OST1 (also known as SnRK2.6) is a key signaling player and central regulator in guard cells in response to ABA. Phosphorylation of Thr(38) in the amino-terminal cytoplasmic domain of AtCLCa by OST1 increased the outward anion fluxes across the vacuolar membrane, which are essential for stomatal closure. We provide evidence that bidirectional activities of an intracellular CLC exchanger are physiologically relevant and that phosphorylation regulates the transport mode of this exchanger.
authors.affiliation: CNRS-UPR 2355, Institut des Sciences du Végétal, Saclay Plant Sciences Labex, Bât. 22, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Wege
authors.affiliation: CNRS-UPR 2355, Institut des Sciences du Végétal, Saclay Plant Sciences Labex, Bât. 22, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France. Istituto di Biofisica, C.N.R., Via De Marini 6, 16149 Genova, Italy. Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
authors.forename: Alexis
authors.initials: A
authors.lastname: De Angeli
authors.affiliation: CNRS-UPR 2355, Institut des Sciences du Végétal, Saclay Plant Sciences Labex, Bât. 22, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
authors.forename: Marie-Jo
authors.initials: MJ
authors.lastname: Droillard
authors.affiliation: Laboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265, Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bât. 156, 13108 St Paul-lez-Durance, France.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Kroniewicz
authors.affiliation: CNRS-UPR 2355, Institut des Sciences du Végétal, Saclay Plant Sciences Labex, Bât. 22, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Merlot
authors.affiliation: CNRS-FRC5115, Centre de Recherche de Gif, Imagif, Bât. 21, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
authors.forename: David
authors.initials: D
authors.lastname: Cornu
authors.affiliation: Istituto di Biofisica, C.N.R., Via De Marini 6, 16149 Genova, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Gambale
authors.affiliation: Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
authors.forename: Enrico
authors.initials: E
authors.lastname: Martinoia
authors.affiliation: CNRS-UPR 2355, Institut des Sciences du Végétal, Saclay Plant Sciences Labex, Bât. 22, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Barbier-Brygoo
authors.affiliation: CNRS-UPR 2355, Institut des Sciences du Végétal, Saclay Plant Sciences Labex, Bât. 22, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Thomine
authors.affiliation: Laboratoire de Biologie du Développement des Plantes, Unité Mixte de Recherche 7265, Centre National de la Recherche Scientifique-Commissariat à l'Energie Atomique-Université Aix-Marseille II, Commissariat à l'Energie Atomique Cadarache Bât. 156, 13108 St Paul-lez-Durance, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Leonhardt
authors.affiliation: CNRS-UPR 2355, Institut des Sciences du Végétal, Saclay Plant Sciences Labex, Bât. 22, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France. Université Paris 7 Denis Diderot, U.F.R. Sciences du Vivant, 35 rue Hélène Brion, 75205 Paris Cedex 13, France. sophie.filleur@isv.cnrs-gif.fr.
authors.forename: Sophie
authors.initials: S
authors.lastname: Filleur
mesh_terms: D000040:Abscisic Acid / Q000378:metabolism / Q000494:pharmacology*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018118:Chloride Channels / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology*; D054046:Plant Stomata / Q000235:genetics / Q000378:metabolism*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology
chemical_list: C407524:ATCLC-A protein, Arabidopsis; D029681:Arabidopsis Proteins; D018118:Chloride Channels; D010937:Plant Growth Regulators; D000040:Abscisic Acid; D011494:Protein Kinases; C472139:OST1 protein, Arabidopsis