TRANSCRIPTION FACTOR MUTANTS OF YEAST

我的长期研究目标是确定在体内RNA聚合酶II （Pol II）转录中起重要作用的因素，并确定这些因素的作用机制。提出的研究反映了我长期以来对基因调控的兴趣和对生物医学研究的承诺。实验将在一个高度互动和支持性的研究环境中进行，我的进步将大大得益于机构承诺减轻教学和委员会的责任。我的近期研究目标集中在转录起始和早期起始后事件。具体目标代表了我们之前对酿酒酵母TATA盒结合蛋白（TBP）研究的延伸。TBP直接与Pol II启动子上的TATA盒子结合，并引发一系列事件，最终形成RNA信息。因此，了解控制TBP的因素是理解真核生物基因表达调控的关键一步。特异性目的1是研究Rtf1的功能，Rtf1是一种对TBP的TATA位点选择和转录延伸都很重要的新蛋白。Rtf1和相关蛋白将被纯化，Rtf1调控基因将使用DNA微阵列进行鉴定，并进行遗传选择以鉴定Rtf1突变的抑制因子。此外，将分析不同突变株中与转录周期相关的Pol II的磷酸化状态。具体目的2是阐明TBP作为体内调节因子靶点的重要性。染色质免疫沉淀和体内足迹方法将用于确定基因特异性和全局作用的转录因子对TBP招募到高度调节的模型启动子的影响。具体目标3是分析两种不同类型的TBP突变体，并深入了解Pol II转录的两个基本方面：转录复合物的定向特异性组装和起始调控。在体内表现出反向DNA结合极性的TBP突变体将使用DNA切割和转录分析进行分析。TBP突变体在TBP的特定亚域发生改变，并表现出表明转录缺陷的表型，将被研究。这项工作的结果将为未来几年继续解剖转录起始和延伸提供坚实的基础。由于用于调节Pol II的蛋白质和机制是高度保守的，因此从酵母研究中获得的信息将大大提高我们对人类转录的理解，其中这一过程的改变导致了包括艾滋病在内的重要人类疾病。

My long-term research objectives are to identify factors that play important roles in transcription by RNA polymerase II (Pol II) in vivo and to determine the mechanisms by which these factors act. The proposed studies reflect my longstanding interests in gene regulation and commitment to biomedical research. The experiments will be performed in a highly interactive and supportive research environment, and my progress will be greatly aided by institutional commitments to alleviate teaching and committee responsibilities. My immediate research goals center on transcription initiation and early post- initiation events. The Specific Aims represent extensions of our previous studies on Saccharomyces cerevisiae TATA box-binding protein (TBP). TBP binds directly to the TATA box at Pol II promoters and initiates a cascade of events that culminate in an RNA message. Therefore, an understanding of the factors that control TBP is a critical step toward understanding the regulation of gene expression in eukaryotes. Specific Aim 1 is to investigate the function of Rtf1, a novel protein important both for TATA site selection by TBP and for transcript elongation. Rtf1 and associated proteins will be purified, Rtf1- regulated genes will be identified using DNA microarrays, and genetic selections will be performed to identify suppressors of rtf1 mutations. In addition, the phosphorylation state of Pol II, which correlates with the transcription cycle, will be analyzed in various mutant strains. Specific Aim 2 is to elucidate the importance of TBP as a target for regulatory factors in vivo. Chromatin immunoprecipitation and in vivo footprinting methods will be used to determine the effect of gene-specific and globally acting transcription factors on the recruitment of TBP to a highly regulated model promoter. Specific Aim 3 is to analyze two distinct classes of TBP mutants and gain insights into two fundamental aspects of Pol II transcription: orientation specific assembly of the transcription complex and regulation of initiation. TBP mutants that exhibit reversed DNA binding polarity in vivo will be analyzed using DNA cleavage and transcription assays. TBP mutants that are altered in a particular subdomain of TBP and exhibit phenotypes indicative of transcriptional defects will be studied. The results from this work will provide a solid foundation for the continued dissection of transcription initiation and elongation in future years. Since the proteins and mechanisms employed in the regulation of Pol II are highly conserved, the information that is learned from these studies in yeast will significantly advance our understanding of transcription in humans, where an alteration in this process leads to important human diseases including AIDS.