Post-translationale Regulation pflanzlicher schwach gleichrichtender K+ Kanäle

弱整流性钾通道是植物钾通道中所特有的。这些电压门控的K+通道具有特殊的门控特性，这些特性受到复杂的翻译后修饰谱的强烈调节。这些通道可以在两种不同的模式下工作。在模式1中，它们表现为内向整流钾通道，仅介导K+的吸收。然而，在模式2中，它们被锁定打开，因此可以在质膜上双向运输K+。在最近的一项研究中，PI组可以阐明这一调节的生理意义。Kware通道的翻译后修饰利用了一种“钾电池”，从而有效地辅助质膜H+-ATPase为韧皮部组织的跨膜运输过程提供能量。遗憾的是，到目前为止，关于调节Kware通道活动和运行模式的信号级联的知识仍然非常有限。该项目旨在通过从模式植物拟南芥中识别与Kware通道AKT2相互作用的蛋白质，并调节其活性，来研究这些信号级联反应中的进一步步骤。相互作用的蛋白质将使用酵母-双杂交系统和分裂-泛素系统的改进版本，通过直接蛋白质组学方法和电子计算机方法进行鉴定。新发现的蛋白质的调节功能将直接在共表达实验和AKT2活性分析中进行测试。新收集的信息将为建立一个弱监管网络提供基础。该网络的动力学将在计算模拟中进行研究。在拟南芥中发现的AKT2-通道调节的有益方面也将在杨树上进行测试。

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.