Regulation of TAFI Activity by TAF7

TAF7 对 TAFI 活动的调节

• 批准号: 6948352
• 负责人: DINAH SINGER
• 金额: --
• 依托单位: DIVISION OF CLINICAL SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6948352
• 关键词: MHC class I antigen; acyltransferase; enzyme activity; enzyme induction /repression; genetic promoter element; genetic regulation; genetic transcription; intermolecular interaction; recombinant proteins; transcription factor; yeast two hybrid system

The general transcription factor, TFIID, consists of the TATA binding protein (TBP) associated with a series of TBP-associated factors (TAFs) that together participate in the assembly of the transcription preinitiation complex. One of the TAFs, has acetyl transferase (AT) activity that is necessary for transcription of MHC class I genes: inhibition of the AT activity represses transcription. To identify potential cellular factors that might regulate the AT activity of TAFI, a yeast two-hybrid library was screened with a TAFI segment (848-1279 aa) that spanned part of its AT domain and its RAP74 binding domain. The TFIID component, TAF7, was isolated and found to interact predominantly with the RAP74-binding domain. TAF7 binding to TAFI inhibits its AT activity. Importantly, addition of recombinant TAF7 to in vitro transcription assays inhibits TAFI-dependent MHC class I transcription. Thus, TAF7 is capable of regulating TAFI function by modulating its AT activity. To investigate the role in transcription of TAF7 repression of TAF1 AT activity, we have developed an in vitro preinitiation complex (PIC) assembly assay, using the MHC class I promoter as the template. In this assay, transcription from the PIC initiates at the sites observed in vivo, depends on all 4 dNTP's and is inhibited by inhibitors of transcription. Furthermore, we find that TAF7 assembles with the PIC. Currently under investigation is the mechanism by which TAF7-repression of the TAF1 AT activity is relieved, allowing transcription to proceed.

一般转录因子TFIID由TATA结合蛋白（TBP）和一系列TBP相关因子（TAF）组成，这些因子共同参与转录前起始复合物的组装。TAF之一具有乙酰转移酶（AT）活性，其是MHC I类基因转录所必需的：AT活性的抑制抑制转录。为了鉴定可能调节TAFI的AT活性的潜在细胞因子，用跨越其AT结构域和RAP 74结合结构域的一部分的TAFI区段（848-1279 aa）筛选酵母双杂交文库。TFIID成分TAF 7被分离出来，并发现主要与RAP 74结合结构域相互作用。TAF 7与TAFI结合抑制其AT活性。重要的是，将重组TAF 7添加到体外转录测定中抑制TAFI依赖性MHC I类转录。因此，TAF 7能够通过调节其AT活性来调节TAFI功能。为了研究TAF 7抑制TAF 1 AT活性在转录中的作用，我们开发了一种体外前起始复合物（PIC）组装试验，使用MHC I类启动子作为模板。在该试验中，PIC的转录起始于体内观察到的位点，依赖于所有4种dNTP，并被转录抑制剂抑制。此外，我们发现TAF 7与PIC组装。目前正在研究的是TAF 1 AT活性的TAF 7抑制被解除，从而允许转录进行的机制。