ACS Chem Biol. 2019 Feb 15;14(2):288-295. doi: 10.1021/acschembio.8b01013. Epub 2019 Jan 29.
Aminoacyl-tRNA synthetases (AARSs) charge their cognate tRNAs with corresponding amino acids, playing key roles in ribosomal protein synthesis. A series of proteomic studies have demonstrated that AARSs have levels of lysine acetylation much higher than those of other proteins in Escherichia coli. To study AARS acetylation, 25 site-specifically acetylated variants of four AARSs were generated by the genetic code expansion strategy. Kinetic analyses were performed to biochemically characterize the impact of site-specific acetylation on AARS functions, including amino acid activation, tRNA aminoacylation, and editing activities. The results showed that impacts of acetylation were different between class I and class II AARSs and also varied among the same class of AARSs. The results also showed that acetylation of threonyl-tRNA synthetase (ThrRS) could affect its editing function. Both in vivo and in vitro studies were further performed to explore the acetylation and deacetylation processes of ThrRS. Although nonenzymatic acetylation and CobB-dependent deacetylation were concluded, the results also indicated the existence of additional modifying enzymes or mechanisms for ThrRS acetylation and deacetylation.
氨酰-tRNA 合成酶（AARSs）将其对应的氨基酸加载到相应的 tRNA 上，在核糖体蛋白合成中发挥关键作用。一系列蛋白质组学研究表明，AARSs 的赖氨酸乙酰化水平远高于大肠杆菌中其他蛋白质的水平。为了研究 AARSs 的乙酰化，通过遗传密码扩展策略生成了四个 AARSs 的 25 种特异性乙酰化变体。进行了动力学分析，以生化方式表征特异性乙酰化对 AARSs 功能的影响，包括氨基酸激活、tRNA 氨酰化和编辑活性。结果表明，乙酰化的影响在 I 类和 II 类 AARSs 之间不同，并且在同一类 AARSs 之间也有所不同。结果还表明，苏氨酰-tRNA 合成酶（ThrRS）的乙酰化可能会影响其编辑功能。进一步进行了体内和体外研究，以探索 ThrRS 的乙酰化和去乙酰化过程。尽管得出了非酶促乙酰化和 CobB 依赖性去乙酰化的结论，但结果还表明存在用于 ThrRS 乙酰化和去乙酰化的其他修饰酶或机制。
