title: The Arabidopsis TOR Kinase Specifically Regulates the Expression of Nuclear Genes Coding for Plastidic Ribosomal Proteins and the Phosphorylation of the Cytosolic Ribosomal Protein S6.
abstract: Protein translation is an energy consuming process that has to be fine-tuned at both the cell and organism levels to match the availability of resources. The target of rapamycin kinase (TOR) is a key regulator of a large range of biological processes in response to environmental cues. In this study, we have investigated the effects of TOR inactivation on the expression and regulation of Arabidopsis ribosomal proteins at different levels of analysis, namely from transcriptomic to phosphoproteomic. TOR inactivation resulted in a coordinated down-regulation of the transcription and translation of nuclear-encoded mRNAs coding for plastidic ribosomal proteins, which could explain the chlorotic phenotype of the TOR silenced plants. We have identified in the 5' untranslated regions (UTRs) of this set of genes a conserved sequence related to the 5' terminal oligopyrimidine motif, which is known to confer translational regulation by the TOR kinase in other eukaryotes. Furthermore, the phosphoproteomic analysis of the ribosomal fraction following TOR inactivation revealed a lower phosphorylation of the conserved Ser240 residue in the C-terminal region of the 40S ribosomal protein S6 (RPS6). These results were confirmed by Western blot analysis using an antibody that specifically recognizes phosphorylated Ser240 in RPS6. Finally, this antibody was used to follow TOR activity in plants. Our results thus uncover a multi-level regulation of plant ribosomal genes and proteins by the TOR kinase.
authors.affiliation: Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-SaclayVersailles, France; Université Paris-Sud-Université Paris-SaclayOrsay, France; Umeå Plant Science Center, Department of Plant Physiology, Umeå UniversityUmeå, Sweden.
authors.forename: Thomas
authors.initials: T
authors.lastname: Dobrenel
authors.affiliation: Institut de Biologie Moléculaire des Plantes, UPR 2357 CNRS, Université de Strasbourg Strasbourg, France.
authors.forename: Eder
authors.initials: E
authors.lastname: Mancera-Martínez
authors.affiliation: Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-Saclay Versailles, France.
authors.forename: Céline
authors.initials: C
authors.lastname: Forzani
authors.affiliation: Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-Saclay Versailles, France.
authors.forename: Marianne
authors.initials: M
authors.lastname: Azzopardi
authors.affiliation: Plateforme PAPPSO, UMR GQE-Le Moulon Gif sur Yvette, France.
authors.forename: Marlène
authors.initials: M
authors.lastname: Davanture
authors.affiliation: Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-SaclayVersailles, France; Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, DSV, IBEB, SBVME, CEA, CNRS, Aix-Marseille Université, Faculté des Sciences de LuminyMarseille, France.
authors.forename: Manon
authors.initials: M
authors.lastname: Moreau
authors.affiliation: Institut de Biologie Moléculaire des Plantes, UPR 2357 CNRS, Université de Strasbourg Strasbourg, France.
authors.forename: Mikhail
authors.initials: M
authors.lastname: Schepetilnikov
authors.affiliation: Plateforme Protéomique Strasbourg-Esplanade, CNRS FRC1589, Institut de Biologie Moléculaire et Cellulaire Strasbourg, France.
authors.forename: Johana
authors.initials: J
authors.lastname: Chicher
authors.affiliation: Plateforme PAPPSO, UMR GQE-Le Moulon Gif sur Yvette, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Langella
authors.affiliation: Plateforme PAPPSO, UMR GQE-Le Moulon Gif sur Yvette, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Zivy
authors.affiliation: Laboratoire de Génétique et Biophysique des Plantes, UMR 7265, DSV, IBEB, SBVME, CEA, CNRS, Aix-Marseille Université, Faculté des Sciences de Luminy Marseille, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Robaglia
authors.affiliation: Institut de Biologie Moléculaire des Plantes, UPR 2357 CNRS, Université de Strasbourg Strasbourg, France.
authors.forename: Lyubov A
authors.initials: LA
authors.lastname: Ryabova
authors.affiliation: Umeå Plant Science Center, Department of Plant Physiology, Umeå University Umeå, Sweden.
authors.forename: Johannes
authors.initials: J
authors.lastname: Hanson
authors.affiliation: Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique, AgroParisTech, Centre National de la Recherche Scientifique, Université Paris-Saclay Versailles, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Meyer
keywords: RPS6; TOR kinase; phosphorylation; plastid; proteomic; ribosome; transcriptomic; translatomic