精氨酸甲基化调控ABA受体R10蛋白稳定性的分子机制

The shortage of agricultural resources and the frequent occurrence of natural disasters are the great challenges for China's agricultural production. Abscisic acid (ABA) plays an important role in plant resistance to drought, salinity and extreme temperature. Since ABA receptor is the key regulator of ABA signaling, and the stability of the receptor protein is closely related to plant stress resistance, we focus on studying the regulating mechanism of ABA receptor stability. We found that the ubiquitination of ABA receptor R10 was regulated by APC/C complex. TE is a subunit of APC/C complex responsible for substrate recognition. Results showed that te mutant is sensitive to ABA, and is much resistant to drought treatment (Nature communication, 2015, 14, 6:7981). In this work, we found that ABA receptor R10 was also modified by arginine methylation, and arginine methylation was directly related to the stability of ABA receptor. On the basis of this project, we will analyze the molecular mechanism of arginine methylation in the regulation of R10 stability, and explore the application value of R10 arginine methylation mutation in improving crop stress resistance. These work will lay the foundation for the improvement of crop resistance to abiotic stress by molecular assisted breeding.

农业资源紧缺、自然灾害频发是我国农业生产面临的巨大挑战。脱落酸（ABA）在植物抵御干旱、盐害、极端温度等逆境胁迫中发挥重要作用。 ABA受体是ABA信号的核心调控因子，解析ABA受体的转录及翻译后调控机制对认识和有效利用ABA信号具有重要意义。.在蛋白翻译后修饰研究中我们发现，水稻ABA受体R10泛素化降解受APC/CTE复合体调控。TE蛋白是APC/CTE复合体中负责识别底物的亚基，te突变体中ABA受体积累，植株抗旱性比野生型明显增强（Nature communication, 2015, 14, 6:7981）。后续研究发现，ABA受体R10还受到精氨酸甲基化修饰，并且精氨酸甲基化与ABA受体稳定性直接相关。本项目将在此基础上，系统解析精氨酸甲基化调控R10稳定性的分子机制，探索R10精氨酸甲基化突变在提高水稻抗逆性方面的应用价值，为利用ABA信号增强作物抗逆性奠定基础。

蛋白质精氨酸甲基转移酶（PRMT）广泛分布于动物、酵母和植物中。PRMT在动物和酵母中的作用已被广泛研究，但对PRMT在植物中的作用仍知之甚少。在这里，我们发现水稻OsPRMT6b在精氨酸残基48（R48）、精氨酸残基79（R79）和精氨酸残基113（R113）的位置上特异性地甲基化ABA受体OsPYL/RCAR10（R10）。OsPRMT6b在转录和翻译水平均由ABA诱导，prmt6b突变体表现出ABA敏感表型，类似于甲基化缺失模拟OE（R10/3RK）株系。转录数据还表明，OsPRMT6b对ABA反应基因的表达具有负调控作用。进一步研究表明，精氨酸甲基化模拟突变增加了R10的泛素化水平，并促进其降解。我们的结果发现，OsPRMT6b是决定水稻ABA受体稳定性的关键调节因子。ABA信号是植物参与逆境响应的最重要激素之一，这项工作为通过基因工程调控水稻抗逆性提供了新的靶点。