A tRNA synthetase is an amino acid sensor for TOR in plants

项目总结 雷帕霉素靶标(TOR)是一种高度保守的蛋白激酶，调节真核生物 新陈代谢。ToR感知和整合上游信号，特别是营养供应，以协调 只有在条件有利的情况下，才能促进新陈代谢和生长。ToR失调导致或 导致广泛的人类疾病，包括癌症、与年龄相关的健康障碍，以及 代谢紊乱，这是美国发病率和死亡率的主要原因。 因此，生物医学研究的一个主要目标是开发特定的治疗方法 TOR信号网络的目标组件，而不广泛干扰新陈代谢和 依赖TOR的健康细胞的动态平衡。最近，在这方面取得了重大进展 目标是发现几种推定的TOR氨基酸传感器。关于这一事件的报道相互矛盾 这些传感器的相对贡献、重要性和分子机制阻碍了这些 然而，这是进步。该项目使用一种创新的方法来为这些问题带来新的视角 通过将焦点转移到另一个主要的真核生物谱系--植物，目前正在进行的辩论。 在我的实验室正在进行的阐明植物中TOR信号网络的工作中，我发现了一种新的氨基 TOR的酸传感器，一种氨基酰tRNA合成酶(AARS)。此AARS是维持TOR所必需的 活性，并足以刺激植物细胞中的TOR。使用生化，分子， 遗传和系统水平的方法，我建议准确地定义AARs如何在 植物细胞通过三个独立的目标。在目标1中，我建议突变关键的酶残基和 AARs的结构特征来确定激活TOR所需的分子特征。在AIM 2、我建议使用Robust来定位介导Aars-TOR激活的信号转导通路 正交切间入路。然后将验证可能的信号转导组件 使用互惠分析和功能遗传学全面定义AARS-TOR相互作用 为TOR监管做出贡献。在目标3中，我建议建立TOR对特定目标的选择性敏感性 并确定AARS是否是TOR的真正的氨基酸传感器。 综合起来，这三个目标将定义潜在的氨基的分子机制。 ACID-AARS-TOR信号轴及其代谢调控研究新方向 真核生物。此外，这一途径将成为理解tRNA合成酶如何 已经在信号转导途径中进化出了超越翻译的功能，并说明了 复杂的TOR信号网络进化为整合了人类不同的生理线索。从长远来看， 我们的发现将对当代生物医学研究的一个主要目标做出重大贡献： 微调TOR信号网络，以改善和延长健康的人类寿命。

PROJECT SUMMARY TARGET OF RAPAMYCIN (TOR) is a deeply conserved protein kinase that regulates eukaryotic metabolism. TOR senses and integrates upstream signals, especially nutrient availability, to coordinate metabolism and promote growth only when conditions are favorable. TOR dysregulation causes or contributes to a broad range of human diseases, including cancers, age-related health disorders, and metabolic disorders, which are the major causes of morbidity and mortality in the United States. Therefore, a major goal for biomedical research is to develop therapeutic treatments that specifically target components of the TOR signaling network without broadly disrupting metabolism and homeostasis in healthy cells that rely on TOR. Recently, there have been significant advances to that goal with the discovery of several putative amino acid sensors for TOR. Conflicting reports about the relative contributions, importance, and molecular mechanisms of these sensors have stymied these advances, however. This project uses an innovative approach to bring fresh perspective to these ongoing debates by shifting focus to the other major eukaryotic lineage, plants. In my lab’s ongoing work to elucidate the TOR signaling network in plants, I discovered a novel amino acid sensor for TOR, an aminoacyl tRNA synthetase (aaRS). This aaRS is necessary to maintain TOR activity and sufficient to stimulate TOR in plant cells. Using a combination of biochemical, molecular, genetic, and systems-level approaches, I propose to precisely define how the aaRS activates TOR in plant cells through three independent aims. In Aim 1, I propose to mutate key enzymatic residues and structural features of the aaRS to determine the molecular features it requires to activate TOR. In Aim 2, I propose to map the signal transduction pathway mediating aaRS-TOR activation using robust orthogonal interactomic approaches. Putative signal transduction components will then be validated using reciprocal assays and functional genetics to comprehensively define how aaRS-TOR interactors contribute to TOR regulation. In Aim 3, I propose to establish the selective sensitivity of TOR for specific amino acids and determine whether the aaRS is a bona fide amino acid sensor for TOR. Taken together, these three aims will define the molecular mechanisms underlying the putative amino acid-aaRS-TOR signaling axis and open new directions for future research on metabolic regulation in eukaryotes. Moreover, this pathway will serve as a model for understanding how tRNA synthetases have evolved functions beyond translation in signal transduction pathways and illuminate how the complex TOR signaling network evolved to integrate diverse physiological cues in humans. Long-term, our findings will make significant contributions to a major goal of contemporary biomedical research: fine-tuning TOR signaling networks to improve and lengthen healthy human lifespans.