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CELL BIOLOGY AND SIGNAL TRANSDUCTION

Protein Tyrosine Kinases and Protein Tyrosine Phosphatases Are Involved in Abscisic Acid-Dependent Processes in Arabidopsis Seeds and Suspension Cells¹

UPMC Université Paris 06, UMR 7180 (T.G., E.M., E.J.), and CNRS, UMR 7180 (Y.H., B.S.), Laboratoire de Physiologie Cellulaire et Moléculaire des Plantes, 94200 Ivry sur Seine, France; UPMC Université Paris 06, IFR 83, Plate-Forme de Spectrométrie de Masse et Protéomique, 75005 Paris, France (G.B., G.C.); and CNRS, UMR 7613, Laboratoire de Structure et Fonction de Molécules Bioactives, 75005 Paris, France (G.B.)

Protein tyrosine (Tyr) phosphorylation plays a central role in many signaling pathways leading to cell growth and differentiation in animals. Tyr phosphorylated proteins have been detected in higher plants, and the roles of protein Tyr phosphatases and protein Tyr kinases in some physiological responses have been shown. We investigated the involvement of Tyr phosphorylation events in abscisic acid (ABA) signaling using a pharmacological approach. Phenylarsine oxide, a specific inhibitor of protein Tyr phosphatase activity, abolished the ABA-dependent accumulation of RAB18 (responsive to ABA 18) transcripts. Protein Tyr kinase inhibitors like genistein, tyrphostin A23, and erbstatin blocked the RAB18 expression induced by ABA in Arabidopsis (Arabidopsis thaliana). Stomatal closure induced by ABA was also inhibited by phenylarsine oxide and genistein. We studied the changes in the Tyr phosphorylation levels of proteins in Arabidopsis seeds after ABA treatment. Proteins were separated by two-dimensional gel electrophoresis, and those phosphorylated on Tyr residues were detected using an anti-phosphotyrosine antibody by western blot. Changes were detected in the Tyr phosphorylation levels of 19 proteins after ABA treatment. Genistein inhibited the ABA-dependent Tyr phosphorylation of proteins. The 19 proteins were analyzed by matrix-assisted laser-desorption ionization time-of-flight/time-of-flight mass spectrometry. Among the proteins identified were storage proteins like cruciferins, enzymes involved in the mobilization of lipid reserves like aconitase, enolase, aldolase, and a lipoprotein, and enzymes necessary for seedling development like the large subunit of Rubisco. Additionally, the identification of three putative signaling proteins, a peptidyl-prolyl isomerase, an RNA-binding protein, and a small ubiquitin-like modifier-conjugating enzyme, enlightens how Tyr phosphorylation might regulate ABA transduction pathways in plants.

The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Thanos Ghelis (thanos.ghelis{at}upmc.fr).

www.plantphysiol.org/cgi/doi/10.1104/pp.108.124594

^* Corresponding author; e-mail thanos.ghelis{at}upmc.fr.

Received June 11, 2008; accepted August 26, 2008; published September 3, 2008.