Szentirmay M N, Sawadogo M
Department of Molecular Genetics, University of Texas, M. D. Anderson Cancer Center, Houston 77030.
Proc Natl Acad Sci U S A. 1991 Dec 1;88(23):10691-5. doi: 10.1073/pnas.88.23.10691.
We have investigated conditions that allow multiple rounds of transcription initiation from the adenovirus major late promoter in an in vitro system derived from HeLa cell nuclear extracts. Templates containing guanine-free cassettes provided a direct assay for discriminating between reinitiated transcripts and transcripts generated by a first-round of transcription initiations. When reactions were reconstituted with the previously characterized class II transcription factors (TFIIA, TFIIB, TFIID, TFIIE/F), transcription by human RNA polymerase II from the adenovirus major late promoter was essentially restricted to a single round of initiations. Reinitiations at previously transcribed major late templates required an additional activity, designated reinitiation transcription factor (RTF). The RTF activity could be separated from the required transcription initiation factors. Semipurified human RTF also promoted transcription reinitiations at minimal promoters derived from the human c-myc, histone H4, and heat shock 70-kDa protein genes, indicating that the same reinitiation factor may be utilized by many, if not all, genes. The possible role of RTF in regulating the transcription rate of various class II genes is discussed.
我们研究了在源自HeLa细胞核提取物的体外系统中，允许从腺病毒主要晚期启动子进行多轮转录起始的条件。含有无鸟嘌呤盒的模板为区分重新起始的转录本和第一轮转录起始产生的转录本提供了直接检测方法。当用先前鉴定的II类转录因子（TFIIA、TFIIB、TFIID、TFIIE/F）重建反应时，人RNA聚合酶II从腺病毒主要晚期启动子的转录基本上仅限于单轮起始。在先前转录的主要晚期模板上重新起始需要一种额外的活性，称为重新起始转录因子（RTF）。RTF活性可以与所需的转录起始因子分离。半纯化的人RTF也促进了源自人c-myc、组蛋白H4和热休克70 kDa蛋白基因的最小启动子处的转录重新起始，表明许多（如果不是全部）基因可能利用相同的重新起始因子。讨论了RTF在调节各种II类基因转录速率中的可能作用。
