Genetic Regulation of Alcohol Metabolism in Yeast

描述（由申请人提供）：转录调节在细胞稳态中起重要作用，调节细胞的内部节律及其对外部环境的响应。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，以满足生物体的代谢需要。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没有在多个水平（包括转录水平）得到适当调节时，就会出现这种疾病。虽然不是一种疾病严格来说，老化是另一种条件，其发病年龄和严重程度受到营养压力或热量限制的影响，部分通过影响染色质组织的转录途径起作用。在芽殖酵母酿酒酵母（Saccharomyces cerevisiae）中，营养剥夺所造成的压力已得到特别充分的研究。与多细胞真核生物一样，酵母中的代谢应激通过包括复杂蛋白激酶（AMP活化蛋白激酶（AMPK））的酶级联反应来感知和传递。激酶级联的活性由蛋白磷酸酶复合物调节。激酶和磷酸酶复合物的靶标包括转录因子和染色质组分以及催化碳源利用中的关键代谢反应的酶。一个重要的营养压力是葡萄糖剥夺。在酵母和其他生物体中，葡萄糖饥饿需要生物体利用其他不易获得的碳源。这些替代能源是通过葡萄糖可用时不被利用的途径代谢的，这一过程称为碳分解代谢物抑制或简单的葡萄糖抑制。当葡萄糖不可用时，AMPK被激活，其活性作为开关打开许多基因，这些基因的活性对于处理较差的碳底物如乙醇、甘油和乳酸盐，或分解储备的碳水化合物和脂质，或利用替代的可发酵碳源是必需的。在我们以前的工作中，我们表征了两个重要的转录因子Adr 1和Cat8，它们被AMPK激活。在本提案中，我们专注于一个显然是新的蛋白磷酸酶复合物参与基因阻遏，染色质的变化，影响Adr 1的结合，和上游途径的识别和表征，调节Adr 1的结合和活性的表征。

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.