PARALLEL PATHWAYS OF GENE REGULATION

这个项目的目标是确定 分离转录调控途径，使用单细胞 真核生物酿酒酵母。我们已经确定了两条途径 转录调控显示出许多相似之处。HO和CTS1 基因表现出相同的细胞周期调节模式，表达 在细胞周期的G1期晚期。这些基因受 含有转录因子SWI5和ACE2的锌指。这两个 转录因子表现出相同的细胞周期调控模式 转录和细胞周期调控核定位。 此外，SWI5和ACE2的DNA结合域是相同的，以及 它们在体外都与HO启动子结合。然而，尽管有这么多 相似之处，SWI5和ACE2在体内调节不同的基因。SWI5 激活HO的转录，但不激活CTS1，而ACE2激活CTS1 但不是何。 我们建议研究分离SWI5/HO和 ACE2/CTS1通路。我们有数据支持两种不同的模型 监管，这两种模式并不是相互排斥的。第一 模型提出不同的负性调控因子与HO和CTS1结合 而且，SWI5和ACE2克服这些缺陷的能力不同。 这些启动子特异的负调控因子的抑制作用。在……里面 对启动子结构的活体分析为这一模型提供了支持。这个 第二个模型提出，需要额外的因素才能 启动子识别的特异性，以及合作相互作用 因子之间的相互作用有助于启动子的结合和途径的分离。 为了支持这一模型，我们确定了一个因素，它约束着 与SWI5一起协同作用于HO启动子。我们假设 是否存在特定启动子所需的相似因子 ACE2对CTS1启动子的识别。建议进行实验，以 分析这些因素与DNA上的位点以及与每个位点的相互作用 其他，并测试监管控制的模型。 纯化了与SWI5协同结合DNA的因子。这个 编码该因子的基因已经被克隆，我们知道该因子是一种 同源结构域蛋白。尚未观察到合作互动 在锌指蛋白和同源结构域蛋白之间，我们 建议对他们的互动进行描述。建议进行实验，以 确定合作作用所需的这些蛋白质的区域。

The goal of this project is to determine the molecular mechanisms which isolate pathways of transcriptional regulation, using the unicellular eukaryote Saccharomyces cerevisiae. We have identified two pathways of transcriptional regulation which show many parallels. The HO and CTS1 genes show identical patterns of cell cycle regulation, with expression in late G1 phase of the cell cycle. These genes are regulated by zinc-finger containing transcription factors, SWI5 and ACE2. These two transcription factors show identical patterns of cell cycle regulated transcription and cell cycle regulated nuclear localization. Furthermore, the DNA binding domains of SWI5 and ACE2 are identical, and they both bind to the HO promoter in vitro. However, despite these many similarities, SWI5 and ACE2 regulate different genes in vivo. SWI5 activates transcription of HO but not of CTS1, and ACE2 activates CTS1 but not HO. We propose to investigate the mechanisms which isolate the SWI5/HO and ACE2/CTS1 pathways. We have data supporting two distinct models for regulation, and these two models are not mutually exclusive. The first model proposes that different negative regulators bind to the HO and CTS1 promoters, and that SWI5 and ACE2 differ in their ability to overcome the repressive effects of these promoter specific negative regulators. In vivo analysis of promoter constructs provides support for this model. The second model proposes that additional factors are required for specificity in promoter recognition, and that cooperative interactions between factors contributes to promoter binding and pathway isolation. In support of this model we have identified a factor which binds cooperatively, along with SWI5, to the HO promoter. We postulate the existence of an analogous factor which is needed for specific promoter recognition of the CTS1 promoter by ACE2. Experiments are proposed to analyze the interactions of these factors with sites on DNA and with each other, and to test models of regulatory control. The factor that binds DNA cooperatively with SWI5 has been purified. The gene encoding this factor has been cloned, and we know this factor is a homeodomain protein. Cooperative interactions have not been observed before between a zinc finger protein and a homeodomain protein, and we propose to characterize their interaction. Experiments are proposed to identify regions of these proteins required for cooperative interactions.