Department of Biotechnology, College of Life Sciences and Biotechnology, Korea University, Seoul 02841, Republic of Korea.
Medicinal Bioconvergence Research Center, Institute for Artificial Intelligence and Biomedical Research, College of Pharmacy & College of Medicine, Gangnam Severance Hospital, Yonsei University, Incheon 21983, Republic of Korea.
Cell Rep. 2021 Apr 27;35(4):109031. doi: 10.1016/j.celrep.2021.109031.
Leucyl-tRNA synthetase 1 (LARS1) mediates activation of leucine-dependent mechanistic target of rapamycin complex 1 (mTORC1) as well as ligation of leucine to its cognate tRNAs, yet its mechanism of leucine sensing is poorly understood. Here we describe leucine binding-induced conformational changes of LARS1. We determine different crystal structures of LARS1 complexed with leucine, ATP, and a reaction intermediate analog, leucyl-sulfamoyl-adenylate (Leu-AMS), and find two distinct functional states of LARS1 for mTORC1 activation. Upon leucine binding to the synthetic site, H251 and R517 in the connective polypeptide and FPYPY in the catalytic domain change the hydrogen bond network, leading to conformational change in the C-terminal domain, correlating with RagD association. Leucine binding to LARS1 is increased in the presence of ATP, further augmenting leucine-dependent interaction of LARS1 and RagD. Thus, this work unveils the structural basis for leucine-dependent long-range communication between the catalytic and RagD-binding domains of LARS1 for mTORC1 activation.
亮氨酰-tRNA 合成酶 1（LARS1）介导亮氨酸依赖性雷帕霉素靶蛋白复合物 1（mTORC1）的激活以及亮氨酸与其对应的 tRNA 的连接，但亮氨酸感应的机制尚不清楚。在这里，我们描述了亮氨酸诱导的 LARS1 构象变化。我们确定了 LARS1 与亮氨酸、ATP 和反应中间体类似物亮氨酰-磺酰-腺苷酸（Leu-AMS）复合物的不同晶体结构，并发现了 LARS1 用于 mTORC1 激活的两种不同的功能状态。亮氨酸结合到合成位点后，连接多肽中的 H251 和 R517 以及催化结构域中的 FPYPY 改变氢键网络，导致 C 末端结构域发生构象变化，与 RagD 相关联。在存在 ATP 的情况下，LARS1 与亮氨酸的结合增加，进一步增强了 LARS1 和 RagD 之间亮氨酸依赖性相互作用。因此，这项工作揭示了 LARS1 催化结构域和 RagD 结合结构域之间亮氨酸依赖性长程通讯的结构基础，用于 mTORC1 的激活。
