Post-translationale Regulation pflanzlicher schwach gleichrichtender K+ Kanäle

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Weakly rectifying K+ (Kweak) channels are unique among potassium channels in plants. These voltage-gated K+ channel have exceptional gating properties that are strongly regulated by a complex spectrum of posttranslational modifications. These channels can act in two different modes. In modus 1 they behave as inward-rectifying potassium channels mediating K+ uptake only. In modus 2, however, they are locked open and can therefore transport K+ in both directions over the plasmamembrane. In a recent study, the group of the PI could clarify the physiological significance of this regulation. Post-translational modification of Kweak channels taps a ‘potassium battery’ that then efficiently assists the plasma membrane H+-ATPase in energizing transmembrane transport processes in phloem tissues. Unfortunately, up to now, knowledge on the signaling cascades that regulate activity and operation mode of Kweak channels is still very limited. The project proposed here aims at investigating further steps in these signaling cascades by identifying proteins that interact with the Kweak channel AKT2 from the model plant Arabidopsis thaliana and regulate its activity. Interacting proteins will be identified using improved versions of the yeast-two hybrid system and the split-ubiquitin system, in direct proteomic approaches as well as by in silico methods. The regulatory function of the newly identified proteins will be tested directly in co-expression experiments and analyses of AKT2 activity. The newly gathered information will provide the basis for developing a Kweak-regulatory network. The dynamics of this network will be investigated in computational simulations. Beneficial aspects of AKT2-channel regulation that were uncovered in Arabidopsis will be tested also in poplar.