Zhang Hong, Wu Jiang, Lyu Zhihui, Ling Jiqiang
Department of Cell Biology and Molecular Genetics, The University of Maryland, College Park, MD 20742, USA.
Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center, Houston, TX 77030, USA.
Nucleic Acids Res. 2021 Sep 27;49(17):9953-9964. doi: 10.1093/nar/gkab766.
Aminoacyl-tRNA synthetases (aaRSs) are essential enzymes that provide the ribosome with aminoacyl-tRNA substrates for protein synthesis. Mutations in aaRSs lead to various neurological disorders in humans. Many aaRSs utilize editing to prevent error propagation during translation. Editing defects in alanyl-tRNA synthetase (AlaRS) cause neurodegeneration and cardioproteinopathy in mice and are associated with microcephaly in human patients. The cellular impact of AlaRS editing deficiency in eukaryotes remains unclear. Here we use yeast as a model organism to systematically investigate the physiological role of AlaRS editing. Our RNA sequencing and quantitative proteomics results reveal that AlaRS editing defects surprisingly activate the general amino acid control pathway and attenuate the heatshock response. We have confirmed these results with reporter and growth assays. In addition, AlaRS editing defects downregulate carbon metabolism and attenuate protein synthesis. Supplying yeast cells with extra carbon source partially rescues the heat sensitivity caused by AlaRS editing deficiency. These findings are in stark contrast with the cellular effects caused by editing deficiency in other aaRSs. Our study therefore highlights the idiosyncratic role of AlaRS editing compared with other aaRSs and provides a model for the physiological impact caused by the lack of AlaRS editing.
氨酰-tRNA合成酶（aaRSs）是一类至关重要的酶，它们为核糖体提供用于蛋白质合成的氨酰-tRNA底物。aaRSs的突变会导致人类出现各种神经紊乱疾病。许多aaRSs利用编辑功能来防止翻译过程中的错误传播。丙氨酰-tRNA合成酶（AlaRS）的编辑缺陷会在小鼠中引发神经退行性变和心脏蛋白病，并且与人类患者的小头畸形有关。真核生物中AlaRS编辑缺陷对细胞的影响仍不清楚。在此，我们以酵母作为模式生物，系统地研究AlaRS编辑的生理作用。我们的RNA测序和定量蛋白质组学结果显示，AlaRS编辑缺陷出人意料地激活了一般氨基酸控制途径，并减弱了热休克反应。我们通过报告基因和生长试验证实了这些结果。此外，AlaRS编辑缺陷会下调碳代谢并减弱蛋白质合成。为酵母细胞提供额外的碳源可部分挽救由AlaRS编辑缺陷导致的热敏感性。这些发现与其他aaRSs编辑缺陷所造成的细胞效应形成了鲜明对比。因此，我们的研究突出了AlaRS编辑与其他aaRSs相比所具有的独特作用，并为缺乏AlaRS编辑所造成的生理影响提供了一个模型。
