Vos J C, Sasker M, Stunnenberg H G
European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany.
Cell. 1991 Apr 5;65(1):105-13. doi: 10.1016/0092-8674(91)90412-r.
Fractionation of an extract prepared from HeLa cells infected with vaccinia virus resulted in the separation of factors involved in vaccinia virus intermediate transcription. Two activities, VITF-A and VITF-B, in addition to the viral RNA polymerase are necessary and sufficient to direct intermediate transcription in vitro. VITF-B confers intermediate promoter specificity to an early-specific extract prepared from virus particles. A committed complex between VITF-B and the template can sequester VITF-A and RNA polymerase into a pre-initiation complex. VITF-B is further able to melt the promoter at the start site of transcription. Open complex formation is stimulated by ATP. In contrast to prokaryotic and eukaryotic pol III transcription, promoter melting is independent of the presence of RNA polymerase.
对感染痘苗病毒的HeLa细胞制备的提取物进行分级分离，导致参与痘苗病毒中间转录的因子得以分离。除病毒RNA聚合酶外，两种活性物质VITF - A和VITF - B对于体外指导中间转录是必需且足够的。VITF - B赋予从病毒颗粒制备的早期特异性提取物中间启动子特异性。VITF - B与模板之间形成的稳定复合物可将VITF - A和RNA聚合酶隔离到预起始复合物中。VITF - B还能够在转录起始位点使启动子解链。ATP可刺激开放复合物的形成。与原核生物和真核生物的pol III转录不同，启动子解链与RNA聚合酶的存在无关。
