Elsby Laura M, O'Donnell Amanda J M, Green Laura M, Sharrocks Andrew D, Roberts Stefan G E
Faculty of Life Sciences, The Michael Smith Building, University of Manchester, Oxford Road, Manchester M13 9PT, UK.
EMBO Rep. 2006 Sep;7(9):898-903. doi: 10.1038/sj.embor.7400767. Epub 2006 Jul 28.
The general transcription factor TFIIB has a central role in the assembly of the preinitiation complex at the promoter, providing a platform for the entry of RNA polymerase II/TFIIF. We used an RNA interference (RNAi)-based system in which TFIIB expression is ablated in vivo and replaced with a TFIIB derivative that contains a silent mutation and is refractory to the RNAi. Using this approach, we found that transcriptionally defective TFIIB amino-terminal mutants showed distinct effects on the basis of their ability to compete with wild-type TFIIB in vivo. Moreover, analysis of the TFIIB mutant derivatives by chromatin immunoprecipitation showed that promoter occupancy by TFIIB is dependent on the association with RNA polymerase II. Together, our results support a mode of preinitiation complex assembly in which TFIIB/RNA polymerase II recruitment to the promoter occurs in vivo.
通用转录因子TFIIB在启动子处的起始前复合物组装中起核心作用,为RNA聚合酶II/TFIIF的进入提供了一个平台。我们使用了一种基于RNA干扰(RNAi)的系统,其中TFIIB的表达在体内被消除,并用一种含有沉默突变且对RNAi有抗性的TFIIB衍生物取代。使用这种方法,我们发现转录缺陷的TFIIB氨基末端突变体根据其在体内与野生型TFIIB竞争的能力表现出不同的影响。此外,通过染色质免疫沉淀对TFIIB突变衍生物的分析表明,TFIIB在启动子上的占据取决于与RNA聚合酶II的结合。总之,我们的结果支持一种起始前复合物组装模式,即TFIIB/RNA聚合酶II在体内被招募到启动子上。