Phosphorylation of the vacuolar anion exchanger AtCLCa is required for the stomatal response to abscisic acid

Sci. Signal., 8 July 2014
Vol. 7, Issue 333, p. ra65
DOI: 10.1126/scisignal.2005140

Phosphorylation of the vacuolar anion exchanger AtCLCa is required for the stomatal response to abscisic acid

  1. Stefanie Wege1,*,
  2. Alexis De Angeli1,2,3,
  3. Marie-Jo Droillard1,
  4. Laetitia Kroniewicz4,
  5. Sylvain Merlot1,
  6. David Cornu5,
  7. Franco Gambale2,
  8. Enrico Martinoia3,
  9. Hélène Barbier-Brygoo1,
  10. Sébastien Thomine1,
  11. Nathalie Leonhardt4, and
  12. Sophie Filleur1,6,
  1. 1CNRS-UPR 2355, Institut des Sciences du Végétal, Saclay Plant Sciences Labex, Bât. 22, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
  2. 2Istituto di Biofisica, C.N.R., Via De Marini 6, 16149 Genova, Italy.
  3. 3Institute of Plant Biology, University of Zurich, Zollikerstrasse 107, CH-8008 Zurich, Switzerland.
  4. 4Laboratoire 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.
  5. 5CNRS-FRC5115, Centre de Recherche de Gif, Imagif, Bât. 21, 1 Avenue de la Terrasse, 91198 Gif sur Yvette Cedex, France.
  6. 6Université Paris 7 Denis Diderot, U.F.R. Sciences du Vivant, 35 rue Hélène Brion, 75205 Paris Cedex 13, France.
  1. Corresponding author. E-mail: sophie.filleur{at}isv.cnrs-gif.fr
  • * Present address: Department of Plant Molecular Biology, University of Lausanne, CH-1015 Lausanne, Switzerland.

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 Thr38 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.

Citation:

S. Wege, A. De Angeli, M.-J. Droillard, L. Kroniewicz, S. Merlot, D. Cornu, F. Gambale, E. Martinoia, H. Barbier-Brygoo, S. Thomine, N. Leonhardt, and S. Filleur, Phosphorylation of the vacuolar anion exchanger AtCLCa is required for the stomatal response to abscisic acid. Sci. Signal. 7, ra65 (2014).

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Ann Bot 115, 419-431 (1 February 2015)

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