title: The receptor-like pseudokinase MRH1 interacts with the voltage-gated potassium channel AKT2.
abstract: The potassium channel AKT2 plays important roles in phloem loading and unloading. It can operate as inward-rectifying channel that allows H+-ATPase-energized K+uptake. Moreover, through reversible post-translational modifications it can also function as an open, K+-selective channel, which taps a 'potassium battery', providing additional energy for transmembrane transport processes. Knowledge about proteins involved in the regulation of the operational mode of AKT2 is very limited. Here, we employed a large-scale yeast two-hybrid screen in combination with fluorescence tagging and null-allele mutant phenotype analysis and identified the plasma membrane localized receptor-like kinase MRH1/MDIS2 (AT4G18640) as interaction partner of AKT2. The phenotype of the mrh1-1 knockout plant mirrors that of akt2 knockout plants in energy limiting conditions. Electrophysiological analyses showed that MRH1/MDIS2 failed to exert any functional regulation on AKT2. Using structural protein modeling approaches, we instead gathered evidence that the putative kinase domain of MRH1/MDIS2 lacks essential sites that are indispensable for a functional kinase suggesting that MRH1/MDIS2 is a pseudokinase. We propose that MRH1/MDIS2 and AKT2 are likely parts of a bigger protein complex. MRH1 might help to recruit other, so far unknown partners, which post-translationally regulate AKT2. Additionally, MRH1 might be involved in the recognition of chemical signals.
authors.affiliation: Heisenberg Group of Biophysics and Molecular Plant Biology, Institute of Biochemistry and Biology, Molecular Biology, University of Potsdam, D-14476 Potsdam-Golm, Germany.|Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany.|ETH Zürich, Department of Biology, CH-8092 Zürich, Switzerland.
authors.forename: Kamil
authors.initials: K
authors.lastname: Sklodowski
authors.affiliation: Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile.
authors.forename: Janin
authors.initials: J
authors.lastname: Riedelsberger
authors.affiliation: Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), E-28223 Pozuelo de Alarcón (Madrid), Spain.|Instituto de Biología Vegetal y Fotosíntesis, Consejo Superior de Investigaciones Científicas, E-41092 Sevilla, Spain.
authors.forename: Natalia
authors.initials: N
authors.lastname: Raddatz
authors.affiliation: Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Riadi
authors.affiliation: Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile.
authors.forename: Julio
authors.initials: J
authors.lastname: Caballero
authors.affiliation: Biochimie et Physiologie Moléculaire des Plantes, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5004, Institut National de la Recherche Agronomique U386, Montpellier SupAgro, Université Montpellier II, F-34060 Montpellier cedex 2, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Chérel
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany.|Department of Plant Systems Biology, University of Hohenheim, D-70593 Stuttgart, Germany.
authors.forename: Waltraud
authors.initials: W
authors.lastname: Schulze
authors.affiliation: Max-Planck-Institute of Molecular Plant Physiology, D-14476 Potsdam-Golm, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Graf
authors.affiliation: Heisenberg Group of Biophysics and Molecular Plant Biology, Institute of Biochemistry and Biology, Molecular Biology, University of Potsdam, D-14476 Potsdam-Golm, Germany.|Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería, Universidad de Talca, Talca, Chile.|Plant Biophysics, Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), E-28223 Pozuelo de Alarcón (Madrid), Spain.
authors.forename: Ingo
authors.initials: I
authors.lastname: Dreyer
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055162:Biocatalysis; D031541:Fluorescence Resonance Energy Transfer; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D059828:Plant Cells / Q000378:metabolism; D015221:Potassium Channels / Q000378:metabolism*; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015203:Reproducibility of Results; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D014981:Xenopus
chemical_list: C097485:AKT2 protein, Arabidopsis; D029681:Arabidopsis Proteins; D015221:Potassium Channels; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D011494:Protein Kinases; C000606284:MDIS2 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases