FERONIA receptor kinase as a cell surface-located regulator for RAC/ROP GTPase-mediated auxin signaling

植物激素生长素控制细胞生长和细胞分裂，并且在决定整体形态方面也具有关键作用。生长素信号感知的分子水平细节已经研究了几十年。生长素受体复合物位于细胞核内，与生长素调控的许多过程有关。 然而，目前还不清楚这种复合物能否解释生长素调节的所有现象，特别是那些发生在细胞膜沿着的现象。因此，对细胞表面生长素信号传导机制的研究仍在继续。这个项目将扩展以前的工作，表明生长素激活主要的信号介质，功能沿着内表面的细胞膜称为RAC/ROP GTP酶。 这些重要的蛋白质可能作为介质激活表面定位的反应。目前的项目将测试跨膜蛋白FERONIA是否可能是连接细胞外生长素信号到该系统的缺失环节。具体而言，该项目将确定FERONIA的胞外结构域是否单独或以复合物形式与称为LORELEI样葡萄糖基磷脂酰肌醇锚定蛋白1的低分子量胞外基质蛋白直接相互作用。生物化学方法，如蛋白质共免疫沉淀，下拉测定和细胞生物学方法将用于测试这些相互作用在植物细胞中，并确定生长素如何影响它们。直接生长素结合研究将用于测试生长素和FERONIA或FERONIA复合物之间的受体-配体相互作用。 这些测试FERONIA作为细胞表面生长素信号装置的潜力的关键实验将为一名研究生和一名博士后提供培训。

The plant hormone auxin controls both cell growth and cell division and also has a crucial role in determining overall morphology. The molecular-level details of auxin signal perception have been studied for decades. An auxin receptor complex located in the nucleus has been associated with many auxin-regulated processes. It is not clear, however, that this complex can explain the full range of auxin-regulated phenomena, especially those occurring along the cell membrane. Thus, the search for a cell surface-located auxin signaling mechanism continues. This project will extend previous work showing that auxin activates major signal mediators that function along the inner surface of the cell membrane called RAC/ROP GTPases. These important proteins may act as mediators activating surface-located responses. The current project will test whether the transmembrane protein FERONIA could be the missing link connecting extracellular auxin signals to this system. Specifically, this project will determine whether the extracellular domain of FERONIA directly interacts, alone or in a complex, with a low molecular weight extracellular matrix protein called LORELEI-like glucosylphosphatidylinositol-anchored protein1. Biochemical methods such as protein co-immunoprecipitation, pull-down assays and cell biological methods will be used to test for these interactions in plant cells and determine how auxin affects them. Direct auxin-binding studies will be used to test for receptor-ligand interactions between auxin and FERONIA or FERONIA complexes. These crucial experiments testing the potential of FERONIA as a cell surface auxin signaling apparatus will provide training for one graduate student and one postdoctoral fellow.