Regulating regulators to survive nutrient limitation: Lessons from yeast

调节监管机构以应对营养限制：酵母的教训

• 批准号: RGPIN-2019-04683
• 负责人: vanderMerwe, George
• 金额: $ 2.33万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=737785
• 关键词: Regulating; regulators; survive; nutrient; limitation

Saccharomyces cerevisiae serves our society as a pivotal model organism in resolving fundamental questions in eukaryotic biology, and in its capacity to convert fermentable sugars, such as glucose, into ethanol and CO2 in the baking, beverage and bio-ethanol industries. While yeast prefers this fermentative metabolism to generate energy, it can efficiently use non-fermentable carbon sources, like ethanol, when glucose is depleted. During commercially important alcoholic fermentations, yeast commonly experience glucose depletion and increasing levels of ethanol, which negatively impacts the yeast's physiology and metabolism, which in turn decreases fermentation efficiency. Our overarching research goal is to understand the mechanisms that govern the adaptation of yeast to fermentation stresses, and to ultimately use this information to develop technologies to increase capacity in the fermentation industry. When glucose is abundant, the genes needed for fermentative growth are actively expressed, while those needed to metabolize non-fermentable carbon sources, like ethanol, are inhibited. This transcriptional regulation reverses when glucose is depleted, and ethanol is the sole carbon source. Similarly, the abundance, activity and intracellular localization of proteins can also be regulated by the available carbon source. Despite the identification and characterization of several regulatory proteins and signaling mechanisms that govern the adaptation of yeast to glucose depletion, the detailed aspects of transcriptional adaptation and the turnover of target proteins remain unresolved. We recently showed the Vid30 protein complex (Vid30c), an E3 ubiquitin ligase that links ubiquitin to target proteins destined for destruction, impacts the signaling mechanisms that govern fermentative metabolism, affects the transcriptional regulation of glucose repressed genes, and enables the degradation of the hexose transporters in response to glucose depletion. The molecular mechanisms used by Vid30c to mediate these specific events are currently unknown. Thus, the objectives of the proposed research are to characterize the impact of Vid30c on glucose-regulated gene expression and to identify and characterize its direct regulation of specific target proteins in response to carbon availability. We will use a combination of yeast genetic, molecular and cellular biology approaches to achieve these goals. The role of Vid30c in the expression, abundance, posttranslational modification, and subcellular localization of transcription factors and signaling proteins will provide further fundamental insight into the regulatory mechanisms that govern regulators in response to carbon availability. This information will generate a better understanding of commercial fermentations and could lead to the development of strategies to increase the fermentation efficiency of this commercially important organism.

酿酒酵母作为解决真核生物基本问题的关键模式生物，在烘焙、饮料和生物乙醇工业中将葡萄糖等可发酵糖转化为乙醇和二氧化碳的能力，为我们的社会服务。虽然酵母更喜欢这种发酵代谢来产生能量，但当葡萄糖耗尽时，它可以有效地利用不可发酵的碳源，如乙醇。在商业上重要的酒精发酵过程中，酵母通常会经历葡萄糖消耗和乙醇水平的增加，这对酵母的生理和代谢产生负面影响，从而降低发酵效率。我们的总体研究目标是了解控制酵母对发酵压力的适应机制，并最终利用这些信息开发技术来提高发酵工业的能力。当葡萄糖丰富时，发酵生长所需的基因被积极表达，而代谢不可发酵碳源（如乙醇）所需的基因则被抑制。当葡萄糖耗尽时，这种转录调节会逆转，乙醇是唯一的碳源。同样，蛋白质的丰度、活性和细胞内定位也可以受到可利用碳源的调节。尽管已经鉴定和鉴定了几种调节蛋白和信号机制，这些调节蛋白和信号机制控制着酵母对葡萄糖消耗的适应，但转录适应和靶蛋白周转的详细方面仍未解决。我们最近发现了Vid30蛋白复合物（Vid30c），一种E3泛素连接酶，将泛素连接到预定被破坏的靶蛋白，影响控制发酵代谢的信号机制，影响葡萄糖抑制基因的转录调节，并使葡萄糖转运蛋白在葡萄糖消耗时降解。Vid30c介导这些特定事件的分子机制目前尚不清楚。因此，本研究的目的是表征Vid30c对葡萄糖调节基因表达的影响，并识别和表征其对碳可用性的特定靶蛋白的直接调控。我们将使用酵母遗传，分子和细胞生物学方法的组合来实现这些目标。Vid30c在转录因子和信号蛋白的表达、丰度、翻译后修饰和亚细胞定位中的作用将为进一步了解调控因子响应碳可用性的调控机制提供基础知识。这些信息将使人们更好地了解商业发酵，并可能导致开发提高这种重要商业生物发酵效率的策略。