PROMOTER SPECIFICITY OF TRANSCRIPTION FACTORS

描述：相关的酵母转录激活因子SWI 5和ACE 2 具有相关的锌指/DNA结合结构域，并结合相同的序列。 然而，SWI 5激活HO（用于交配型转换的核酸内切酶）和ACE 2 激活CTS 1（几丁质酶）。 这两种激活剂都在细胞周期的G1期起作用。 其特异性的基础是什么？ 在此之前斯蒂尔曼医生 已经有了一些发现。 首先，CTS 1中ACE 2的结合位点 ACE 2和SWI 5与CTS 1和HO位点的结合 在体外进行比较。 由此得出结论，SWI 5和ACE 2结合于 具有相同亲和力的相同序列。 有趣的是，第三个基因SIC 1（cdk抑制剂）被鉴定出来， 由SWI 5和ACE 2激活。 第二，SWI 5与HOUAS结合， 与另一种激活剂PHO 2协同作用。 在体内，PHO 2不是 需要野生型HO的转录，但当SWI- HO中的结合位点因突变而被削弱。 PHO 2协同工作 使用不同的酵母激活剂来激活PHO 5和HIS 4等基因。 发挥 对CTS 1的表达无作用，不与ACE 2协同作用。 三是通过 制造SWI 5-ACE 2嵌合体，鉴定了这些蛋白质中的大区域 其不同于DNA结合结构域并决定靶基因 的特异性 第四，CTS 1启动子中的一个负元件大致上是 已定义，删除时允许激活SWI 5。 建议在 ACE 2的一种活性必须是对抗该元素。 该元素还 将抑制启动子融合体中的异源CYC 1激活剂。 可能 该元件的反式作用阻遏物通过以下突变鉴定： 这些基因（NCE）允许SWI 5激活CTS 1。 五号 两个PHO 2中的区域 确定了HO合作所需的SWI和SWI 5。 PHO 2突变 缺失，SWI 5突变包括单个氨基酸变化， 聚集在一个区域。 第六，两个远端SWI 5基因的突变 HO的结合位点用于暴露PHO 2需求，导致 图片显示SWI 5-PHO 2复合物介导了长程相互作用 在这两个网站之间。 在下一阶段，PI建议1。 进一步表征 PHO 2-SWI 5相互作用。 2. 描述CTS中的负调节1 启动子 3. 表征HO启动子中的负调控作用 的特异性 4. 表征ACE 2如何赋予启动子特异性 activation. 5. 表征受以下调节的其他基因的调节： SWI 5和ACE 2。

DESCRIPTION: The related yeast transcriptional activators SWI5 and ACE2 have related zinc finger/DNA-binding domains, and bind to the same sequence. Yet SWI5 activates HO (endonuclease for mating type switching) and ACE2 activates CTS1 (chitinase). Both activators work in G1 of the cell cycle. What is the basis of their specificity? In the prior period, Dr. Stillman has made several findings. First, binding sites for ACE2 in the CTS1 promoter were identified and binding of ACE2 and SWI5 to CTS1 and HO sites compared in vitro. This led to the conclusion that SWI5 and ACE2 bind to the same sequences with the same affinities. Interestingly, a third gene SIC1 (cdk inhibitor) was identified which is activated by both SWI5 and ACE2. Second, SWI5 binds to the HO UAS in concert with another activator, PHO2, in vitro. In vivo, PHO2 is not required for transcription of wild type HO, but is important when the SWI- binding sites in HO have been weakened by mutation. PHO2 works in concert with different yeast activators for genes such as PHO5 and HIS4. It plays no role in expression of CTS1 and does not cooperate with ACE2. Third, by making SWI5-ACE2 chimeras, large regions in these proteins were identified which are distinct from the DNA-binding domains and dictate target gene specificity. Fourth, a negative element in the CTS1 promoter was roughly defined which when removed allows SWI5 to activate. It is suggested that one activity of ACE2 must be to counteract this element. This element also will inhibit the heterologous CYC1 activators in promoter fusions. Possible trans-acting repressors for this element were identified by mutations in genes (NCE) that allow SWI5 to activate CTS1. Fifth. regions in both PHO2 and SWI5 required for cooperation at HO were identified. The PHO2 mutations were deletions and the SWI5 mutations included single amino acid changes, which clustered in one region. Sixth, mutations in the two distant SWI5 binding sites of HO were used to expose a PHO2 requirement, leading to a picture that a SWI5-PHO2 complex mediates the long range interactions between these two sites. In the next period, the PI proposes to 1. further characterize the PHO2-SWI5 interaction. 2. Characterize the negative regulation in the CTS1 promoter. 3. Characterize the role of negative regulation in HO promoter specificity. 4. Characterize how ACE2 confers promoter specific activation. 5. Characterize the regulation of other genes regulated by SWI5 and ACE2.