The RALF1–FERONIA complex phosphorylates eIF4E1 to promote protein synthesis and polar root hair growth

First author: Sirui Zhu; Affiliations: Hunan University (湖南大学): Changsha, China

Corresponding author: Feng Yu

The molecular links between extracellular signals and the regulation of localized protein synthesis in plant cells are poorly understood. Here, we show that in Arabidopsis thaliana, the extracellular peptide RALF1 and its receptor, the FERONIA receptor kinase, promote root hair (RH) tip growth by modulating protein synthesis. The underlying mechanism is that RALF1 promotes the FERONIA-mediated phosphorylation of eIF4E1, a component that plays a crucial role in the control of the mRNA translation rate. Phosphorylated eIF4E1 increases mRNA affinity and modulates mRNA translation and, thus, protein synthesis. The mRNAs targeted by the RALF1-FERONIA-eIF4E1 module include ROP2 and RSL4, which are important for RH cell polarity and growth. RALF1-FERONIA expressed in a polar manner in RHs facilitates eIF4E1 polar localization and may further control local ROP2 translation. Moreover, high levels of RSL4 exert a negative feedback on RALF1 expression via directly binding the RALF1 gene promoter, determining the final RH size. The link between RALF1–FERONIA signaling and protein synthesis constitutes a novel component regulating cell expansion in these growing polar cells.

在植物中，有关细胞间信号的分子联系以及局部的蛋白合成调控还不是很清楚。本文中，作者在拟南芥中的研究显示胞外多肽RALF1及其受体FERONIA受体激酶通过调控蛋白合成来促进根毛尖端生长。具体的分子机制是，RALF1会促进由FERONIA介导的对于eIF4E1的磷酸化，而eIF4E1蛋白在控制mRNA的翻译速率方面扮演着重要角色。磷酸化的eIF4E1能够增加mRNA的亲和力，同时调控mRNA翻译以及蛋白合成。由RALF1-FERONIA-eIF4E1靶向的mRNA包含两个在根毛细胞极性及生长方面发挥重要功能的蛋白，即ROP2和RSL4。RALF1-FERONIA在根毛中的表达具有极性，进而导致了eIF4E1的极性定位，这有可能促进了ROP2基因局部的翻译调控。此外，高水平的RSL4会通过直接靶向RALF1基因的启动子，从而对RALF1基因的表达存在负调控作用，最终决定了根毛的大小。综上，本文鉴定了一个根毛极性细胞中调控细胞扩张的新的分子模块，即RALF1–FERONIA信号转导与蛋白合成之间的潜在分子关联。

通讯：于 峰 (http://grjl.hnu.edu.cn/p/FFD7C7A9294091F134482129CFAD0763)

个人简介：2003-2007年，湖南师范大学，学士；2008-2013年，湖南师范大学，硕博；2017-2018年，加州大学伯克利分校，访问学者。

研究方向：1. 细胞活动与环境适应；2. 优良农作物性状挖掘及新品种培育；3. 生物信息学与大数据。

doi: https://doi.org/10.1016/j.molp.2019.12.014

Journal: Molecular Plant

Published date: January 03, 2019