Collart M A, Struhl K
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115.
EMBO J. 1993 Jan;12(1):177-86. doi: 10.1002/j.1460-2075.1993.tb05643.x.
The yeast HIS3 promoter region contains two functionally distinct TATA elements, TC and TR, that are responsible respectively for initiation from the +1 and +13 sites. Both TC and TR support basal HIS3 transcription and require the TATA binding protein TFIID, but only TR responds to transcriptional activation by GCN4 and GAL4. By selecting for yeast strains that increase transcription by a GCN4 derivative with a defective activation domain, we have isolated a temperature-sensitive mutation in CDC39, a previously defined gene implicated in cell-cycle control and the pheromone response. This cdc39-2 mutation causes increased basal transcription of many, but not all genes, as well as increased transcriptional activation by GCN4 and GAL4. Surprisingly, basal HIS3 transcription from the +1 initiation site is strongly increased, while initiation from the +13 site is barely affected. Thus, unlike acidic activator proteins that function through TR, CDC39 preferentially affects transcription mediated by TC. CDC39 is an essential gene that encodes a very large nuclear protein (2108 amino acids) containing two glutamine-rich regions. These observations suggest that CDC39 negatively regulates transcription either by affecting the general RNA polymerase II machinery or by altering chromatin structure.
酵母HIS3启动子区域包含两个功能不同的TATA元件，即TC和TR，它们分别负责从+1和+13位点起始转录。TC和TR都支持HIS3的基础转录，且都需要TATA结合蛋白TFIID，但只有TR对GCN4和GAL4介导的转录激活有反应。通过筛选能被具有缺陷激活结构域的GCN4衍生物增强转录的酵母菌株，我们在CDC39中分离到一个温度敏感型突变，CDC39是一个先前已确定与细胞周期调控和信息素反应有关的基因。这个cdc39-2突变导致许多（但不是所有）基因的基础转录增加，以及GCN4和GAL4介导的转录激活增加。令人惊讶的是，从+1起始位点的HIS3基础转录大幅增加，而从+13位点的起始转录几乎不受影响。因此，与通过TR起作用的酸性激活蛋白不同，CDC39优先影响由TC介导的转录。CDC39是一个必需基因，编码一个非常大的核蛋白（2108个氨基酸），含有两个富含谷氨酰胺的区域。这些观察结果表明，CDC39通过影响通用的RNA聚合酶II机制或改变染色质结构来负调控转录。
