title: Salt-induced subcellular kinase relocation and seedling susceptibility caused by overexpression of Medicago SIMKK in Arabidopsis.
abstract: Dual-specificity mitogen-activated protein kinases kinases (MAPKKs) are the immediate upstream activators of MAPKs. They simultaneously phosphorylate the TXY motif within the activation loop of MAPKs, allowing them to interact with and regulate multiple substrates. Often, the activation of MAPKs triggers their nuclear translocation. However, the spatiotemporal dynamics and the physiological consequences of the activation of MAPKs, particularly in plants, are still poorly understood. Here, we studied the activation and localization of the Medicago sativa stress-induced MAPKK (SIMKK)-SIMK module after salt stress. In the inactive state, SIMKK and SIMK co-localized in the cytoplasm and in the nucleus. Upon salt stress, however, a substantial part of the nuclear pool of both SIMKK and SIMK relocated to cytoplasmic compartments. The course of nucleocytoplasmic shuttling of SIMK correlated temporally with the dual phosphorylation of the pTEpY motif. SIMKK function was further studied in Arabidopsis plants overexpressing SIMKK-yellow fluorescent protein (YFP) fusions. SIMKK-YFP plants showed enhanced activation of Arabidopsis MPK3 and MPK6 kinases upon salt treatment and exhibited high sensitivity against salt stress at the seedling stage, although they were salt insensitive during seed germination. Proteomic analysis of SIMKK-YFP overexpressors indicated the differential regulation of proteins directly or indirectly involved in salt stress responses. These proteins included catalase, peroxiredoxin, glutathione S-transferase, nucleoside diphosphate kinase 1, endoplasmic reticulum luminal-binding protein 2, and finally plasma membrane aquaporins. In conclusion, Arabidopsis seedlings overexpressing SIMKK-YFP exhibited higher salt sensitivity consistent with their proteome composition and with the presumptive MPK3/MPK6 hijacking of the salt response pathway.
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Ovečka
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Takáč
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: George
authors.initials: G
authors.lastname: Komis
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Pavol
authors.initials: P
authors.lastname: Vadovič
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Slávka
authors.initials: S
authors.lastname: Bekešová
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Anna
authors.initials: A
authors.lastname: Doskočilová
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Veronika
authors.initials: V
authors.lastname: Šamajová
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Ivan
authors.initials: I
authors.lastname: Luptovčiak
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Olga
authors.initials: O
authors.lastname: Samajová
authors.affiliation: Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria.
authors.forename: Alois
authors.initials: A
authors.lastname: Schweighofer
authors.affiliation: Max F. Perutz Laboratories, Vienna Biocenter, University of Vienna, Dr Bohr-Gasse 9, A-1030 Vienna, Austria.
authors.forename: Irute
authors.initials: I
authors.lastname: Meskiene
authors.affiliation: Gregor Mendel Institute of Molecular Plant Biology GmbH, Dr Bohr-Gasse 3, A-1030 Vienna, Austria.
authors.forename: Claudia
authors.initials: C
authors.lastname: Jonak
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic.
authors.forename: Pavel
authors.initials: P
authors.lastname: Křenek
authors.affiliation: Institution of Cell Imaging and Ultrastructure Research, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Irene
authors.initials: I
authors.lastname: Lichtscheidl
authors.affiliation: Department of Rickettsiology, Institute of Virology, Slovak Academy of Sciences, Dubravska cesta 9, Bratislava, 845 05, Slovakia.
authors.forename: L'udovít
authors.initials: L
authors.lastname: Škultéty
authors.affiliation: Unité de Recherche en Genomique Végétale, Université d'Evry-Val-d'essone, 2, rue Gaston Crémieux, F-91057 Evry, France.
authors.forename: Heribert
authors.initials: H
authors.lastname: Hirt
authors.affiliation: Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University, Šlechtitelů 11, 783 71 Olomouc, Czech Republic jozef.samaj@upol.cz.
authors.forename: Jozef
authors.initials: J
authors.lastname: Šamaj
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D004789:Enzyme Activation; D015870:Gene Expression; D000455:Medicago sativa / Q000201:enzymology* / Q000235:genetics; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D021381:Protein Transport; D012492:Salts / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D012492:Salts; D020929:Mitogen-Activated Protein Kinase Kinases
keywords: Arabidopsis; MAPK; Medicago; SIMK; SIMKK; proteomics; salt stress; subcellular relocation.