State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, 320 Yue Yang Road, Shanghai 200031, China.
State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
Nucleic Acids Res. 2019 Sep 19;47(16):8662-8674. doi: 10.1093/nar/gkz588.
A typical feature of eukaryotic aminoacyl-tRNA synthetases (aaRSs) is the evolutionary gain of domains at either the N- or C-terminus, which frequently mediating protein-protein interaction. TARSL2 (mouse Tarsl2), encoding a threonyl-tRNA synthetase-like protein (ThrRS-L), is a recently identified aaRS-duplicated gene in higher eukaryotes, with canonical functions in vitro, which exhibits a different N-terminal extension (N-extension) from TARS (encoding ThrRS). We found the first half of the N-extension of human ThrRS-L (hThrRS-L) is homologous to that of human arginyl-tRNA synthetase. Using the N-extension as a probe in a yeast two-hybrid screening, AIMP1/p43 was identified as an interactor with hThrRS-L. We showed that ThrRS-L is a novel component of the mammalian multiple tRNA synthetase complex (MSC), and is reliant on two leucine zippers in the N-extension for MSC-incorporation in humans, and mouse cell lines and muscle tissue. The N-extension was sufficient to target a foreign protein into the MSC. The results from a Tarsl2-deleted cell line showed that it does not mediate MSC integrity. The effect of phosphorylation at various sites of hThrRS-L on its MSC-targeting is also explored. In summary, we revealed that ThrRS-L is a bona fide component of the MSC, which is mediated by a newly evolved N-extension domain.
真核生物氨酰-tRNA 合成酶（aaRSs）的一个典型特征是在 N 端或 C 端获得进化获得的结构域，这些结构域通常介导蛋白质-蛋白质相互作用。TARSL2（小鼠 Tarsl2）编码一种苏氨酰-tRNA 合成酶样蛋白（ThrRS-L），是高等真核生物中最近鉴定的 aaRS 重复基因，具有体外的典型功能，其 N 端延伸（N-延伸）与 TARS（编码 ThrRS）不同。我们发现人 ThrRS-L（hThrRS-L）的 N-延伸的前半部分与人精氨酰-tRNA 合成酶同源。使用 N-延伸作为酵母双杂交筛选的探针，鉴定到 AIMP1/p43 与人 hThrRS-L 相互作用。我们表明 ThrRS-L 是哺乳动物多 tRNA 合成酶复合物（MSC）的一个新成分，并且依赖于 N-延伸中的两个亮氨酸拉链来将人 MSC 纳入，以及小鼠细胞系和肌肉组织。N-延伸足以将外来蛋白靶向 MSC。来自 Tarsl2 缺失细胞系的结果表明，它不介导 MSC 完整性。还探索了 hThrRS-L 上各种位点的磷酸化对其 MSC 靶向的影响。总之，我们揭示了 ThrRS-L 是 MSC 的一个真正组成部分，它是由新进化的 N-延伸结构域介导的。
