Study on the mechanism of transcriptional regulation by the general transcription factor TFIID (The Role of WD

由TBP结合蛋白（TBP）和TBP相关因子（TAF5）组成的通用转录因子TFIID在真核生物RNA聚合酶II的转录起始中起核心作用。本研究以裂糖酵母（Schizosaccharomyces pombe）的WD重复序列TAF72和TAF73为研究对象，了解TFIID的转录调控机制。以TAF72为诱饵进行双杂交筛选，鉴定其相互作用蛋白。筛选得到一个h4样TAF，计算分子量为50 kDa，命名为TAF50。共免疫沉淀实验表明，TAF50和TAF72是S. pombe TFIID复合物的一个组成部分。这两种TAFs也存在于SAGA复合体中，这是一种不同于TFIID的组蛋白乙酰转移酶复合体。为了在S. pombe中鉴定更多的TAFs，进行了数据库搜索，发现S. pombe基因组包含一组与其他生物中鉴定的TAFs同源。此外，我们还分离了温度敏感突变体TAF72和TAF73，以阐明这些TAFs的体内功能。这些结果揭示了TAF72的WD-repeat区域的功能，即介导TAFs之间的相互作用，并为S. pombe的基础转录机制提供了信息。此外，本研究分离到的温度敏感突变体TAF72和TAF73可作为后续工作的材料。

The general transcription factor TFIID, which consists of TATA-binding protein (TBP) and TBP-associated factors (TAF5), plays a central role in transcription initiation by RNA polymerase II in eukaryotes. This study was carried out to understand the mechanism of transcriptional regulation by TFIID, focusing on the WD repeat-containing TAFs, TAF72 and TAF73, of the fission yeast Schizosaccharomyces pombe.TAF72 was used as bait in a two-hybrid screen to identify its interacting proteins. The screen yielded hitone H4-like TAF with a calculated molecular mass of 50 kDa, which was named TAF50. Coimmunoprecipitation experiments demonstrated that TAF50, as well as TAF72, is a component of the S. pombe TFIID complex. Both TAFs were also present in the SAGA complex, a histone acetyltransferase complex distinct from TFIID.To identify additional TAFs in S. pombe, database searches were performed, revealing that the S. pombe genome contains a set of TAFs homologous to those identified in other organisms.In addition, temperature-sensitive mutants of TAF72 and TAF73 were isolated to elucidate the in vivo function of these TAFs.These results uncover a function of the WD-repeat region of TAF72, that is, mediating interaction between TAFs, and also provide information about the basal transcription machinery of S. pombe. Furthermore, the temperature-sensitive mutants of TAF72 and TAF73 isolated in this study would serve as materials for future work.