Mechanisms of amino-acid sensing by the GATOR complex

卡珀B。罗加拉|NIGMS R35 MIRA-ESI（PAR-20-117）|项目摘要|2022年10月3日 本项目的重点是大分子的信号转导机制， 称为GATOR的超复合物，它由三个具有不同作用的独立子复合物组成：GATOR 1， GATOR 2和KICSTOR。GATOR超复合体先前被证明负责接收 然后将这些信息传递给一个大的蛋白激酶 称为mTORC 1，其作用是调节细胞代谢以响应环境。之一 必须传递给mTORC 1的关键信号是细胞中营养素的可用性-氨基酸和糖。 监测细胞中每种营养物质的含量对于合理地确定细胞的生长至关重要。 这些决定将决定细胞未来的活动--它是否应该在营养物质充足的情况下生长。 可用，或备用，并保持自己的营养供应不足时。 该项目将特别关注氨基酸作为信号分子。我们的目标是破译 伴随三种关键氨基酸-亮氨酸， 精氨酸和甲硫氨酸。事实上，在20种不同的氨基酸类型中，只有3种是直接 通过mTORC 1途径监测，以告知细胞生长决策。这些氨基酸中的每一种 似乎通过三种不同的机制向GATOR复合体发出信号。然而，尽管广泛的研究， 在这一领域，我们仍然对这些机制如何传播氨基酸可用性信号知之甚少， 激活或失活mTORC 1。亮氨酸、精氨酸和蛋氨酸的存在是否同样重要， 或者一种氨基酸支配着其他氨基酸是否有任何大的构象变化伴随着 氨基酸传感器与GATOR蛋白的结合？GATOR的组成和本地化 补充或停用氨基酸后超复杂的变化？ 我们围绕三个主题建立了这个研究项目，这些主题将开始回答这些（以及更多！） 有趣的问题在主题#1中，我们将专注于GATOR复合体本身-以其apo形式。主题#2 将探讨亮氨酸和精氨酸信号转导至GATOR 2的机制。在主题#3中，我们将 试图破译对GATOR 1的神秘的甲硫氨酸可用性影响。我们的目标是激发更深层次的 以蛋白质机制为中心的思想。通过提供新的方案，蛋白质复合物结构， 以及一系列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，同时也有助于发展治疗对毁灭性疾病的增长， 例如癌症。

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.