The receptor-like pseudokinase MRH1 interacts with the voltage-gated potassium channel AKT2

Kamil Sklodowski (1, 2, 3) , Janin Riedelsberger (4) , Natalia Raddatz , Gonzalo Riadi (4) , Julio Caballero (4) , Isabelle Chérel (5) , Waltraud Schulze (6) , Alexander Graf (2) , Ingo Dreyer (1, 7, 4)

1 Heisenberg Group of Biophysics and Molecular Plant Biology, Institute of Biochemistry and Biology, Molecular Biology
2 MPI-MP - Max Planck Institute of Molecular Plant Physiology
3 Department of Biology
4 Centro de Bioinformática y Simulación Molecular, Facultad de Ingeniería
5 BPMP - Biochimie et Physiologie Moléculaire des Plantes
6 Department of Plant Systems Biology
7 Plant Biophysics, Centro de Biotecnología y Genómica de Plantas - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)

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.

Domaines: Sciences du Vivant [q-bio]

Kamil Sklodowski, Janin Riedelsberger, Natalia Raddatz, Gonzalo Riadi, Julio Caballero, et al.. The receptor-like pseudokinase MRH1 interacts with the voltage-gated potassium channel AKT2. Scientific Reports, 2017, 7, pp.1-12. ⟨10.1038/srep44611⟩. ⟨hal-01605987⟩