Presidential Faculty Fellow

总统教员研究员

• 批准号: 9553140
• 负责人: Erin O'Shea
• 金额: $ 50万
• 依托单位: University of California-San Francisco
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-01-01 至 2000-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9553140&HistoricalAwards=false
• 关键词: Presidential; Faculty; Fellow

9553140 O'Shea Yeast growth is sustained by the availability of nutrients. Phosphate is a required nutrient. When phosphate is limiting transcription of an acid phosphatase occurs. This enzyme which is secreted hydrolyzes phosphoryl groups of organic molecules to yield phosphate ion. The PHO5 gene encodes the phosphatase; transcription is tightly repressed when yeast are grown in medium containing Pi. Three positive regulators and two negative regulators of the gene have been identified. Two of the positive regulators have been shown to be transcriptional regulators that bind to the promoter. Both of the negative regulators are essential; deletion of either results in high levels of gene expression. One of these, PHO80, is homologous to a yeast cyclin (which regulates cell division). The other negative regulator, PHO85, is a CDC related protein kinase. The complex of negative regulators phosphorylates transcription factor PHO4 only when yeast are grown in high phosphate. This phosphorylation is correlated with gene repression. Growth in low Pi results in one of the positive regulators, PHO81, inhibiting the kinase complex. The reduced activity of the kinase is correlated with derepression of the gene; this is assisted by the action of PHO4 whose biochemical activity is not characterized. %%% Yeast require phosphate to grow and multiply. When phosphate amounts are low the yeast secrete a special enzyme that breaks down organic compounds that contain phosphate to renew the supplies. The investigator has found that the same molecules that regulate the production of the special enzyme also regulate cell division. This is a remarkable example of adaptation to the environment. The use of the same or similar molecules that control phosphate use which is necessary for growth and division also direct the cell to reproduce itself. ***

9553140 O'Shea 酵母的生长是通过营养物质的可用性来维持的。 磷酸盐是必需的营养素。 当磷酸盐限制酸性磷酸酶的转录时发生。 这种分泌的酶水解有机分子的磷酰基，产生磷酸根离子。 PHO5基因编码磷酸酶；当酵母在含有 Pi 的培养基中生长时，转录受到严格抑制。 已鉴定出该基因的三个正调节因子和两个负调节因子。 其中两个正调节因子已被证明是与启动子结合的转录调节因子。 两个负调节因子都是必不可少的；任何一个的缺失都会导致高水平的基因表达。 其中之一 PHO80 与酵母细胞周期蛋白（调节细胞分裂）同源。 另一个负调节因子 PHO85 是 CDC 相关蛋白激酶。 仅当酵母在高磷酸盐中生长时，负调节因子复合物才会磷酸化转录因子 PHO4。 这种磷酸化与基因抑制相关。 低 Pi 条件下的生长会导致正调节因子之一 PHO81 抑制激酶复合物。 激酶活性的降低与基因的去抑制相关；这是由 PHO4 的作用辅助的，PHO4 的生化活性尚未确定。 %%% 酵母需要磷酸盐才能生长和繁殖。 当磷酸盐含量较低时，酵母会分泌一种特殊的酶，可以分解含有磷酸盐的有机化合物来更新供应。 研究人员发现，调节特殊酶产生的相同分子也调节细胞分裂。 这是适应环境的一个显着例子。 使用相同或相似的分子来控制生长和分裂所必需的磷酸盐的使用，也可以指导细胞自我繁殖。 ***