Homeostasis of branched-chain amino acids is critical for the activity of TOR signaling in Arabidopsis
Homeostasis of branched-chain amino acids is critical for the activity of TOR signaling in Arabidopsis
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DOI：
10.7554/elife.50747
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发表时间：
2019-12-06
期刊：
影响因子：
7.7
通讯作者：
Brandizzi, Federica
中科院分区：
文献类型：
--
作者：
Cao, Pengfei;Kim, Sang-Jin;Brandizzi, Federica
雷帕霉素（TOR）激酶的靶点是一个进化上保守的营养感知和代谢信号中枢。在植物中，TOR激活与葡萄糖可用性的功能联系已被证实，但尚不清楚支链氨基酸（BCAAs）是否像在酵母和哺乳动物细胞中一样是TOR信号的主要输入。在这里，我们报道了一个过量积累BCAAs的拟南芥突变体的特征。通过针对TOR的化学干预以及检测BCAA生物合成和TOR信号的突变体，我们发现BCAA过度积累导致TOR活性上调，从而导致肌动蛋白细胞骨架和肌动蛋白相关内膜的重组。最后，我们发现TOR的激活伴随着细胞扩增、增殖和特化代谢的改变，从而对植物的生长发育产生多效性影响。这些结果表明，BCAAs有助于植物TOR的激活，并揭示了以前未知的TOR信号传导的下游亚细胞过程。
The target of rapamycin (TOR) kinase is an evolutionarily conserved hub of nutrient sensing and metabolic signaling. In plants, a functional connection of TOR activation with glucose availability was demonstrated, while it is yet unclear whether branched-chain amino acids (BCAAs) are a primary input of TOR signaling as they are in yeast and mammalian cells. Here, we report on the characterization of an Arabidopsis mutant over-accumulating BCAAs. Through chemical interventions targeting TOR and by examining mutants of BCAA biosynthesis and TOR signaling, we found that BCAA over-accumulation leads to up-regulation of TOR activity, which causes reorganization of the actin cytoskeleton and actin-associated endomembranes. Finally, we show that activation of TOR is concomitant with alteration of cell expansion, proliferation and specialized metabolism, leading to pleiotropic effects on plant growth and development. These results demonstrate that BCAAs contribute to plant TOR activation and reveal previously uncharted downstream subcellular processes of TOR signaling.