Genetic Regulation of Alcohol Metabolism in Yeast

描述(申请人提供)：转录调节在细胞内稳态中起重要作用，调节细胞的内部节律及其对外部环境的反应。细胞对营养缺乏的反应需要基因表达的协调，以确保合成适当的酶和辅因子来满足有机体的新陈代谢需求。糖尿病和代谢综合征是两种人类疾病的例子，当对热量摄入的代谢反应在多个水平上没有得到适当的调节时，包括转录水平。虽然严格地说，衰老不是一种疾病，但它是另一种疾病，其发病年龄和严重程度受到营养应激或热量限制的影响，部分是通过影响染色质组织的转录途径发挥作用。营养剥夺带来的压力在萌芽酵母酿酒酵母中已经得到了特别好的研究。正如在多细胞真核生物中一样，酵母中的代谢应激是通过包括复杂的蛋白激酶AMP激活的蛋白激酶(AMPK)的一系列酶来感知和传递的。蛋白磷酸酶复合体调节着该蛋白激酶级联的活性。激酶和磷酸酶复合体的靶标包括转录因子和染色质成分，以及在碳源利用中催化关键代谢反应的酶。一种重要的营养压力是葡萄糖缺乏。在酵母中，就像在其他生物体中一样，葡萄糖饥饿要求有机体利用其他不太容易获得的碳源。当葡萄糖可用时，这些替代能源通过不被利用的途径代谢，这一过程被称为碳分解代谢抑制或简称葡萄糖抑制。当没有葡萄糖时，AMPK被激活，它的活性作为开关来启动许多基因，这些基因的活性是处理较差的碳底物(如乙醇、甘油和乳酸)所必需的，或者是分解储备的碳水化合物和脂肪，或者是利用替代的可发酵碳源。在我们以前的工作中，我们鉴定了两个重要的转录因子，Adr1和Cat8，它们是由AMPK激活的。在目前的建议中，我们集中在一个明显参与基因抑制的新的蛋白磷酸酶复合体的特征，影响Adr1结合的染色质变化，以及调节Adr1结合和活性的上游通路的鉴定和特征。

DESCRIPTION (provided by applicant): Transcriptional regulation plays an important role in cellular homeostasis, regulating internal rhythms of the cell and its response to the external milieu. The cellular response to nutrient deprivation requires coordination of gene expression to insure that appropriate enzymes and cofactors are synthesized to meet the metabolic needs of the organism. Diabetes and metabolic syndrome are examples of two human diseases that arise when the metabolic response to caloric intake is not appropriately regulated at multiple levels, include transcriptional ones. Although not a disease strictly speaking, aging is another condition whose age of onset and severity is affected by nutrient stress, or caloric restriction, acting in part through transcriptional pathways affecting chromatin organization. The stress imposed by nutrient deprivation has been particularly well-studied in the budding yeast Saccharomyces cerevisiae. As in multicellular eukaryotes, metabolic stress in yeast is sensed and transmitted through an enzyme cascade that includes a complex protein kinase, the AMP-activated protein kinase (AMPK). The activity of the kinase cascade is modulated by a protein phosphatase complex. The targets of the kinase and phosphatase complexes include transcription factors and chromatin components as well as enzymes catalyzing key metabolic reactions in carbon source utilization. One important nutrient stress is glucose deprivation. In yeast as in other organisms, glucose starvation requires the organism to utilize other less readily available sources of carbon. These alternative energy sources are metabolized by pathways that are not utilized when glucose is available, a process called carbon catabolite repression or simply glucose repression. AMPK is activated when glucose is not available, and its activity serves as a switch to turn on numerous genes whose activity is necessary to process poorer carbon substrates such as ethanol, glycerol, and lactate, or to breakdown reserve carbohydrates and lipids, or to utilize alternative fermentable carbon sources. In our previous work we characterized two important transcription factors, Adr1 and Cat8, which are activated by AMPK. In the present proposal we focus on the characterization of an apparently novel protein phosphatase complex involved in gene repression, the chromatin changes that influence Adr1 binding, and the identification and characterization of upstream pathways that regulate the binding and activity of Adr1.