STRUCTURAL CHARACTERIZATION OF THE TAF1-TAF7 TFIID SUBCOMPLEX

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其它NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， 而不是由NCRR赠款提供给子项目或子项目工作人员的直接资金。 转录因子TFIID由TATA盒结合蛋白（TBP）和14个TBP相关因子（TAFs）组成，在RNA聚合酶II调控基因表达中起关键作用。TFIID作为核心启动子识别因子，在真核生物蛋白质编码基因的起始位点开始组装转录装置的过程中起着关键作用。TFIID复合物的各种生物化学研究表明，复合物的最大亚基TAF 1具有组蛋白乙酰转移酶和激酶活性，可能在TFIID依赖性启动子的基因表达调控中发挥关键作用。虽然这些活动已被假定，TAF 1结构域不具有任何已知的激酶或乙酰转移酶家族成员的序列同源性。虽然一些TAF 1结构域和功能已被表征，但被鉴定为可能的酶结构域的TAF 1分子的最大C-末端区域在结构上仍然未知。因此，我们有兴趣获得TFIID的TAF 1亚基的结构信息。我们以前已经确定了一个稳定的TFIID亚复合物，它由TAF 1亚基的推定催化区和TAF 7的调节区组成，并确定了从大肠杆菌中表达和纯化该复合物的条件。杆菌我们希望通过晶体学方法确定TFIID的TAF 1-TAF 7亚复合物的结构，并相信这将为preinitiation复合物的组织和组装提供第一个结构一瞥。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. The transcription factor TFIID, composed of the TATA box binding protein (TBP) and 14 TBP associated factors (TAFs), plays a key role in regulation of gene expression by RNA Polymerase II. TFIID plays a critical role as a core promoter recognition factor that begins the process of assembling the transcriptional apparatus at the start site of protein coding genes in eukaryotes. A variety of biochemical studies of TFIID complexes have suggested that the largest subunit of the complex, TAF1, possesses histone acetyl-transferase and kinase activities that may play critical roles in the regulation of gene expression from TFIID dependent promoters. While these activities have been postulated, TAF1 domains possess no sequence homology with any known kinase or acetyl-transferase family members. Although some TAF1 domains and functions have been characterized, the largest C-terminal region of the TAF1 molecule identified as the likely enzymatic domain remains structurally unknown. Consequently we are interested in obtaining structural information for the TAF1 subunit of TFIID. We have previously identified a stable subcomplex of TFIID that consists of the putative catalytic region of the TAF1 subunit and the regulatory region of TAF7 and have determined conditions for the expression and purification of this complex from E. coli. We hope to determine the structure of the TAF1-TAF7 subcomplex of TFIID crystallographically and believe this will provide the first structural glimpse into the organization and assembly of the preinitiation complex.