GLUCOSE SENSING AND SIGNALLING IN YEAST

描述（由申请人提供）：葡萄糖燃料寿命。大多数细胞喜欢它作为它们的碳源和能量来源，并且必须快速准确地感知它。因为它使用葡萄糖的方式不寻常。酵母细胞必须检测葡萄糖供应的波动，并迅速调整其代谢，以最大限度地利用可用的葡萄糖。酵母菌控制葡萄糖利用的第一个限速步骤--转运到细胞中.我们发现了两种新的葡萄糖传感器，启动信号转导途径，调节编码葡萄糖转运蛋白的HXT基因的表达。这些葡萄糖传感器是一类与营养转运蛋白相关的新型营养受体的创始成员;我们想知道它们的工作原理。由葡萄糖传感器启动的信号转导途径现在是焦点;我相信我们准备将其提升到与其他信号转导途径同等的理解水平。这种葡萄糖传感途径始于细胞膜上的Snf 3和Rgt 2葡萄糖传感器，它们与Yck 1蛋白激酶偶联。葡萄糖信号被转导至Rgt 1转录因子，其抑制HXT基因，并被Mth 1和Std 1抑制。葡萄糖与传感器的结合导致Yck 1磷酸化Mth 1和Std 1，从而靶向它们进行泛素化和降解。我们想知道葡萄糖信号是如何由传感器产生的，信号如何激活Yck 1对Mth 1和Std 1的磷酸化，Mth 1和Std 1如何调节Rgt 1功能，以及信号通路如何与代谢网络相结合。我们未来四年的具体目标是：目标1：了解葡萄糖信号是如何在通路的顶部产生和转导的。目标1A：葡萄糖传感器是葡萄糖受体吗？目标1B：传感器和传输器之间功能差异的基础是什么？Aim 1C：Yck 1在信号通路中的作用是什么？Aim 1D：我们是否遗漏了SRR途径的任何组成部分？目的2：了解葡萄糖信号如何调节Rgt 1阻遏物。Aim 2A：Rgt 1的抗阻遏物区域如何发挥其功能？Aim 2B：Rgt 1磷酸化残基的作用是什么？Aim 2C：Mth 1和Std 1如何抑制Rgt 1的抗阻遏物区域？目标3：了解葡萄糖信号通路如何与代谢网络整合。目的3A：Mth 1在腺嘌呤生物合成和一碳代谢中的作用是什么？目标3B：信号通路在其他酵母中是如何部署的？它是如何演变的？公共卫生相关性：葡萄糖是生命的燃料。大多数细胞喜欢葡萄糖作为食物来源，有些细胞需要葡萄糖，细胞已经进化出许多复杂的机制来感知葡萄糖并做出适当的反应。这在面包酵母中尤其明显（S.酿酒酵母），其具有几种高度进化的调节机制，用于感测和利用其在其寿命期间遇到的广泛变化量的葡萄糖。这些调节机制决定了酵母独特的代谢，这是它与许多种肿瘤细胞共享的生活方式。我们的长期目标是了解酵母细胞如何感知和响应葡萄糖。我们正在研究一种葡萄糖传感系统，其关键成分是位于细胞膜上并检测葡萄糖的新型葡萄糖受体，向细胞发送影响基因表达和影响代谢的信号。我们的目标是了解这些新受体是如何工作的。

DESCRIPTION (provided by applicant): Glucose fuels life. Most cells prefer it as their carbon and energy source, and must rapidly and accurately sense it. This is particularly apparent for yeast (S. cerevisiae) because of the unusual way it uses glucose. Yeast cells must detect fluctuations in the glucose supply and rapidly adjust their metabolism to make maximum use of what is available. Yeasts control glucose utilization at its first, rate- limiting step - transport into the cell. We discovered two novel glucose sensors that initiate a signal transduction pathway that regulates expression of HXT genes encoding glucose transporters. These glucose sensors are the founding members of a novel class of nutrient receptor related to nutrient transporters; we would like to know they work. The signal transduction pathway initiated by the glucose sensors is now in focus; I believe we are poised to elevate it to a level of understanding on par with other signal transduction pathways. This glucose sensing pathway begins at the cell membrane with the Snf3 and Rgt2 glucose sensors, which are coupled to the Yck1 protein kinase. The glucose signal is transduced to the Rgt1 transcription factor, which represses HXT genes, and is inhibited by Mth1 and Std1. Glucose binding to the sensors causes Yck1 to phosphorylate Mth1 and Std1, thereby targeting them for ubiquitination and degradation. We want to know how the glucose signal is generated by the sensors, how the signal activates phosphorylation of Mth1 and Std1 by Yck1, how Mth1 and Std1 regulate Rgt1 function, and how the signaling pathway meshes with the metabolic network. Our Specific Aims for the next four years are: Aim 1: Learn how the glucose signal is generated and transduced at the top of the pathway. Aim1A: Are the glucose sensors glucose receptors? Aim1B: What is the basis for functional differences between sensors and transporters? Aim1C: What is the role of Yck1 in the signaling pathway? Aim1D: Are we missing any components of the SRR pathway? Aim 2: Learn how the glucose signal regulates the Rgt1 repressor. Aim2A: How does the antirepressor region of Rgt1 inhibt its function?. Aim2B: What is the role of phosphorylated residues of Rgt1? Aim2C: How do Mth1 and Std1 inhibit the antirepressor region of Rgt1? Aim 3: Learn how the glucose signaling pathway is integrated with the metabolic network. Aim 3A: What is the role of Mth1 in adenine biosynthesis and one-carbon metabolism? Aim 3B: How is the signaling pathway deployed in other yeasts? How did it evolve? PUBLIC HEALTH RELEVANCE: Glucose fuels life. Most cells prefer it as their food source; some cells require it. Cells have evolved numerous and sophisticated mechanisms for sensing glucose and responding to it appropriately. This is especially apparent in Bakers' yeast (S. cerevisiae), which has several highly evolved regulatory mechanisms for sensing and utilizing the widely varying amounts of glucose it encounters during its lifetime. These regulatory mechanisms determine the distinctive metabolism of yeast, a lifestyle it shares with many kinds of tumor cells. Our long-term goal is to understand how yeast cells sense and respond to glucose. We are studying a glucose sensing system whose key components are novel glucose receptors that sit in the cell membrane and detect glucose, sending a signal into the cell that affects gene expression and influences metabolism. We aim to learn how these novel receptors work.