Quantitative and functional posttranslational modification proteomics reveals that TREPH1 plays a role in plant touch-delayed bolting

First author: Kai Wang; Affiliations: The Hong Kong University of Science and Technology (香港科技大学): Hong Kong, China

Corresponding author: Ning Li

Environmental mechanical forces (机械外力), such as wind and touch, trigger gene-expression regulation and developmental changes, called “thigmomorphogenesis,” (接触形态建成) in plants, demonstrating the ability of plants to perceive such stimuli. In Arabidopsis, a major thigmomorphogenetic response is delayed bolting (延迟抽薹), i.e., emergence of the flowering stem. The signaling components responsible for mechanotransduction (机械转导) of the touch response are largely unknown. Here, we performed a high-throughput SILIA (stable isotope labeling 稳定同位素标记 in Arabidopsis)-based quantitative phosphoproteomics analysis (磷酸化蛋白质组定量鉴定) to profile changes in protein phosphorylation resulting from 40 seconds of force stimulation in Arabidopsis thaliana. Of the 24 touch-responsive phosphopeptides (磷酸肽) identified, many were derived from kinases (激酶), phosphatases (磷酸酶), cytoskeleton proteins (细胞骨架蛋白), membrane proteins, and ion transporters. In addition, the previously uncharacterized protein TOUCH-REGULATED PHOSPHOPROTEIN1 (TREPH1) became rapidly phosphorylated in touch-stimulated plants, as confirmed by immunoblots (免疫印迹). TREPH1 fractionates (分级) as a soluble protein and is shown to be required for the touch-induced delay of bolting and gene-expression changes. Furthermore, a nonphosphorylatable site-specific isoform of TREPH1 (S625A) failed to restore touch-induced flowering delay of treph1-1, indicating the necessity of S625 for TREPH1 function and providing evidence consistent with the possible functional relevance of the touch-regulated TREPH1 phosphorylation. Taken together, these findings identify a phosphoprotein player in Arabidopsis thigmomorphogenesis regulation and provide evidence that TREPH1 and its touch-induced phosphorylation may play a role in touch-induced bolting delay, a major component of thigmomorphogenesis.

诸如风、触碰等环境的机械外力会引起植物基因表达调控和发育的改变，这叫做“接触形态建成”，说明了植物能够感知外界刺激的能力。在拟南芥中，接触形态建成最主要的响应就是延迟抽薹，也就是花茎的形成被延迟。触碰响应下游在植物中的机械传导还有很多需要深入研究的地方。本文基于拟南芥稳定同位素标记的高通量磷酸化蛋白质组定量鉴定来绘制拟南芥中40秒的触碰处理所导致的蛋白磷酸化改变。在鉴定到的24个触碰响应磷酸化蛋白，大部分来自于激酶、磷酸酶、细胞骨架蛋白、膜蛋白及离子转运蛋白。另外，先前未被报道的触碰相关磷酸化蛋白TREPH1在受触碰刺激的植株中快速积累，免疫印迹试验验证了这一点。TREPH1作为可溶性蛋白，对于由触碰引起的抽薹延迟和基因表达改变是必须的。此外，不能被磷酸化的TREPH1 S625A异构体不能拯救treph1-1突变体触碰诱导的开花延迟表型，说明了S625对于TREPH1发挥功能是必要的，同时也说明了受触碰调控的TREPH1磷酸化的功能相关性。综上，本文的研究鉴定了一个调控拟南芥接触形态建成的磷酸化蛋白，同时也表明了TREPH1及其触碰诱导的磷酸化在拟南芥接触形态建成的重要响应，即延迟抽薹中发挥着非常重要的作用。

通讯：Ning Li（https://life-sci.ust.hk/faculty/Prof.N.Li/index.html）

研究方向：细胞信号转导和细胞周期中的翻译后修饰；翻译后修饰定量蛋白组、互作组及分子系统生物学。

doi: https://doi.org/10.1073/pnas.1814006115

Journal: PNAS

First Published: 05 October, 2018

（P.S. 原文下载：链接:https://pan.baidu.com/s/1qFiSsqwlF_7JjmGMbedfhQ  密码:dmu6）