Mechanisms of amino-acid sensing by the GATOR complex

Kacper B.Rogala|NIGMS R35 Mira-ESI(PAR-20-117)|项目摘要|2022年10月3日 本课题的重点是研究大分子的信号转导机制。 被称为GATOR的超复合体，由三个具有不同角色的单独的子复合体组成：GATOR1， GATOR2和KICSTOR。鳄鱼超复合体此前被证明负责接收 来自各种细胞传感器的信息，然后将这些信息传递给一个大的蛋白激酶 被称为mTORC1，其作用是调节细胞新陈代谢以应对环境。其中一个 必须传递给mTORC1的关键信号是细胞中营养物质的可用性--氨基酸和糖。 监测细胞可支配的每一种营养物质的量，对于合理地 将决定细胞未来活动的决定-当营养物质 当营养素供应不足时，可供使用，或备用并保持其自身。 这个项目将特别关注作为信号分子的氨基酸。我们的目标是破译分子 伴随着三种关键氨基酸-亮氨酸-细胞浓度变化而发生的一连串事件， 精氨酸和蛋氨酸。事实上，在二十种不同的氨基酸类型中，只有三种是直接的 由mTORC1途径监测，为细胞生长决策提供信息。这些氨基酸中的每一种也 似乎通过三种不同的机制向鳄鱼复合体发出信号。然而，尽管进行了广泛的研究 在这个领域，我们仍然对这些机制如何将氨基酸可获得性信号传播到 激活或停用mTORC1。亮氨酸、精氨酸和蛋氨酸的存在是否同样重要， 或者可能有一种氨基酸主宰了其余的氨基酸？有没有伴随而来的大的构象变化？ 氨基酸传感器与鳄鱼蛋白的结合？短吻鳄的组成和本地化 补充或停用氨基酸后的超复合体变化？ 我们围绕三个主题建立了这个研究项目，这三个主题将开始回答这些(以及更多！) 很有趣的问题。在主题#1中，我们将重点关注鳄鱼情结本身--以它的apo形式。主题#2 将探讨亮氨酸和精氨酸信号转导GATOR2的机制。在主题#3中，我们将 试图破译GATOR1上神秘的蛋氨酸可利用性影响。我们的雄心是激发更深层次的灵感 这一领域以蛋白质机制为中心的思维。并通过提供新的方案，蛋白质复杂结构， 和一组经过验证的结构导向突变体，我们将为新的研究奠定基础 方向，同时也有助于开发针对破坏性生长疾病的治疗方法， 比如癌症。

Kacper B. Rogala | NIGMS R35 MIRA-ESI (PAR-20-117) | Project Summary | October 3, 2022 The focus of this project is on the mechanisms of signal transduction by the large macromolecular supercomplex called GATOR, which is made of three individual sub-complexes with distinct roles: GATOR1, GATOR2, and KICSTOR. The GATOR supercomplex was previously shown to be responsible for receiving information from various cellular sensors, and then passing that information down to a large protein kinase called mTORC1, the role of which is to regulate cellular metabolism in response to the environment. One of the key signals that must be relayed to mTORC1 is availability of nutrients in the cell — amino acids and sugars. Monitoring how much of every individual nutrient the cell has at its disposal is critical for making rational decisions that will determine the future activities of the cell — whether it should grow when nutrients are available, or stand-by and maintain itself when nutrients are in short supply. This project will specifically focus on amino acids as signaling molecules. Our goal is to decipher the molecular chain of events that accompany changes in cellular concentration of three critical amino acids — leucine, arginine, and methionine. Indeed, out of twenty different amino acid types, only three of them are directly monitored by the mTORC1 pathway to inform cellular growth decisions. Each one of these amino acids also appears to signal to the GATOR complex — via three distinct mechanisms. Yet, despite extensive research in this field, we still know very little about how these mechanisms propagate amino-acid availability signals to either activate or deactivate mTORC1. Is the presence of leucine, arginine, and methionine equally important, or perhaps one amino acid dominates the rest? Are there any large conformational changes that accompany binding of amino-acid sensors to GATOR proteins? Does the composition and localization of the GATOR supercomplex change upon amino acid supplementation or withdrawal? We built this research project around three main themes that will begin answering these (and many more!) fascinating questions. In Theme #1, we will focus on the GATOR complex itself — in its apo form. Theme #2 will explore the mechanism of leucine and arginine signal transduction to GATOR2. And in Theme #3, we will attempt to decipher the enigmatic methionine-availability effects on GATOR1. Our ambition is to inspire deeper protein-mechanism-centered thinking in this field. And by providing novel protocols, protein complex structures, and a set of validated structure-guided mutants, we will lay the foundation that will enable new research directions, while also contributing to the development of therapeutics against devastating diseases of growth, such as cancer.