Basic Forestry and Proteomics Research Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, P. R. China.
Basic Forestry and Proteomics Research Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian Province 350002, P. R. China.
Dev Cell. 2021 May 3;56(9):1283-1295.e5. doi: 10.1016/j.devcel.2021.03.022. Epub 2021 Apr 7.
The evolutionarily conserved target-of-rapamycin (TOR) kinase coordinates cellular and organismal growth in all eukaryotes. Amino acids (AAs) are key upstream signals for mammalian TOR activation, but how nitrogen-related nutrients regulate TOR signaling in plants is poorly understood. Here, we discovered that, independent of nitrogen assimilation, nitrate and ammonium function as primary nitrogen signals to activate TOR in the Arabidopsis leaf primordium. We further identified that a total of 15 proteinogenic AAs are also able to activate TOR, and the first AAs generated from plant specific nitrogen assimilation (glutamine), sulfur assimilation (cysteine), and glycolate cycle (glycine), exhibit the highest potency. Interestingly, nitrate, ammonium, and glutamine all activate the small GTPase Rho-related protein from plants 2 (ROP2), and constitutively active ROP2 restores TOR activation under nitrogen-starvation conditions. Our findings suggest that specific evolutionary adaptations of the nitrogen-TOR signaling pathway occurred in plant lineages, and ROP2 can integrate diverse nitrogen and hormone signals for plant TOR activation.
进化保守的雷帕霉素靶蛋白（TOR）激酶在所有真核生物中协调细胞和生物体的生长。氨基酸（AAs）是哺乳动物 TOR 激活的关键上游信号，但氮相关营养素如何调节植物中的 TOR 信号尚不清楚。在这里，我们发现，硝酸盐和铵盐独立于氮同化，作为初级氮信号在拟南芥叶原基中激活 TOR。我们进一步确定，总共 15 种蛋白质氨基酸也能够激活 TOR，并且植物特有的氮同化（谷氨酰胺）、硫同化（半胱氨酸）和乙醛酸循环（甘氨酸）产生的第一个氨基酸具有最高的活性。有趣的是，硝酸盐、铵盐和谷氨酰胺都能激活植物中的 Rho 相关蛋白 2（ROP2），而组成型激活的 ROP2 可以在氮饥饿条件下恢复 TOR 的激活。我们的研究结果表明，氮-TOR 信号通路的特定进化适应性发生在植物谱系中，ROP2 可以整合不同的氮和激素信号以激活植物 TOR。
