Impact of NRT2.1 posttranslational regulatory mechanisms on nitrate uptake and sensing

硝酸盐是植物生长所必需的常量营养素。此外，它还具有信号功能，触发新陈代谢和根发育的特定适应。在拟南芥中，已知转运蛋白NRT2.1在根硝酸盐吸收中起核心作用，也可能在根发育对硝酸盐的响应信号中发挥作用。之前由两个合作伙伴发起的工作开始为NRT2.1翻译后调控绘制了一幅复杂的图景，涉及总共五个不同位点的N-末端和C-末端的磷酸化，与伙伴蛋白的相互作用，以及C-末端部分的切割。该项目现在的目标是建立在德国和法国合作伙伴之间技能的强大互补性基础上，并将蛋白质组学方法与生物化学、遗传和植物生理学相结合，以破译这些复杂的调控机制。具体地说，该项目的目的是(I)了解NRT2.1的蛋白质-蛋白质相互作用的动力学取决于其修饰状态，(Ii)识别作用于NRT2.1的其他调节蛋白(激酶、磷酸酶)，(Iii)破译NRT2.1的C-末端蛋白分解作为额外调节机制的机制。该项目将为根硝酸盐吸收和/或硝酸盐传感的调控提供新的和有价值的见解，这对提高植物的氮素利用效率具有战略意义。

Nitrate is an essential macronutrient for plant growth. In addition it has signaling functions triggering specific adaptations in metabolism and root development. In A. thaliana, the transporter NRT2.1 is known to have a central role for root nitrate uptake and it could also play a role in signaling for root development in response to nitrate. Previous work initiated by both partners started to draw a complex picture for NRT2.1 post-translational regulations involving phosphorylation of N- and C-terminus at a total of five different sites, interaction with partner proteins, and cleavage of the C-terminal part. The goal of this project is now to build on the strong complementarity of skills between the German and the French partners and combined proteomics approaches with biochemistry, genetic and plant physiology to decipher these complex regulatory mechanisms. Specifically, the project aims at (i) understanding the dynamics of protein-protein interactions of NRT2.1 depending on its modification status, (ii) identification of further regulatory proteins (kinases, phosphatases) acting on NRT2.1, (iii) deciphering the mechanisms of NRT2.1 C-terminal proteolysis as an additional regulatory mechanism. The project will provide novel and valuable insights into the regulation of root nitrate uptake and/or nitrate sensing, which has a strategic importance to improve plants nitrogen use efficiency.