CHARACTERIZATION OF THE S POMBE CAMP SIGNAL PATHWAY

响应环境信号的转录调控涉及 细胞用来控制细胞过程的重要机制 生长、分化和发育。 在单细胞生物中， 碳源的变化可以引发巨大的变化 参与碳源利用的基因转录， 异源发生 例如，葡萄糖会抑制 利用其他碳所需基因的转录 源 这种现象被称为葡萄糖抑制或 分解代谢物阻遏 我的工作主要集中在葡萄糖阻遏fbp 1 （编码果糖-1，6二磷酸酶）在酵母中的转录 裂殖酵母S.粟酒裂殖酵母是一种基因柔韧的有机体 在许多方面类似于高等真核细胞。 虽然这 生物已被广泛和非常成功地利用在该地区 细胞周期控制，很少有研究已经在该领域进行， 转录调控 我已经识别出一组基因， git基因（git =葡萄糖不敏感转录），葡萄糖所需 抑制fbp1转录，包括腺苷酸环化酶基因 （git2）. 携带突变的菌株中的转录缺陷， git 2或任何六个另外的git基因被外源cAMP抑制。 这种抑制，沿着其他遗传和生化观察， 表明这些基因的功能是刺激腺苷酸环化酶， 对葡萄糖的反应。 因此，我建议测量野生动物中的cAMP水平， 型细胞暴露于葡萄糖，并分析进一步的git2突变体 对葡萄糖的反应有缺陷我亦建议 对这些git基因和nft基因（nft）进行分子分析 突变体在抑制fbp1转录方面有缺陷; nft = 非去阻遏的FBP1转录）。 我会克隆野生型的 确定它们的DNA序列，构建无效等位基因， 并检查关于cAMP水平和fbp1的无效表型 转录。 我也会描述自发的git和nft突变体 通过cAMP测定、遗传分析和fbp1转录测定， 鉴定S.粟酒

Transcriptional regulation in response to environmental signals involves important mechanisms employed by cells to control the processes of cell growth, differentiation and development. In unicellular organisms, changes in the carbon source available can trigger dramatic alterations in transcription of genes involved in carbon source utilization and gluconeogenesis. For example, glucose causes the repression of transcription of genes required for the utilization of other carbon sources. This phenomenon has been termed glucose repression or catabolite repression. My work focuses on glucose repression of fbp1 (encoding fructose-1,6bisphosphatase) transcription in the yeast Schizosaccharomyces pombe. S. pombe is a genetically pliable organism that resembles higher eukaryotic cells in many respects. While this organism has been widely and very successfuly exploited in the area of cell cycle control, few studies have been carried out in the area of transcriptional regulation. I have identified aset of genes, designated git genes (git=glucose insensitive transcription), required for glucose repression of fbp1 transcription, including the adenylate cyclase gene (git2). The trasncriptional defect in strains carrying a mutation in git2 or any six additional git genes is suppressed by exogenous cAMP. This suppression, along with other genetic and biochemical observations, suggests that these genes function to stimulate adenylate cyclase in response to glucose. I therefore propose to measure cAMP levels in wild type cells upon exposure to glucose, and to analyze further git2 mutants that appear to be defective in response to glucose. I also propose to carry out molecular analyses of these git genes and of nft genes (nft mutants are defective in depression of fbp1 transcription; nft= nonderepressible fbp1 transcription). I will clone the wild type copies of these genes, determine their DNA sequences, construct null alleles, and examine the null phenotypes with regard to cAMP levels and fbp1 transcription. I will also characterize spontaneous git and nft mutants by cAMP assays, genetic analyses and fbp1 transcriptional assays to identify the pathway for activation of adenylate cyclase in S. pombe.