Ray C, Tatti K M, Jones C H, Moran C P
J Bacteriol. 1987 May;169(5):1807-11. doi: 10.1128/jb.169.5.1807-1811.1987.
The discovery of secondary sigma factors in Bacillus subtilis that enable RNA polymerase to transcribe cloned sporulation genes in vitro has led to the proposal that the appearance of new sigma factors during sporulation directs RNA polymerase to the different temporal classes of sporulation genes. One sigma factor, which appears 2 h after the initiation of sporulation, is sigma E (formerly sigma 29). Mutations that inactivate the structural gene for sigma E prevent transcription from promoter G4. To determine whether sigma E-RNA polymerase interacts with the G4 promoter in vivo, we examined the effects of six single-base-pair substitutions in the G4 promoter on its utilization in vivo and in vitro by sigma E-RNA polymerase. The mutations in the G4 promoter affected utilization of the promoter in vivo in the same way that they affected its utilization in vitro by purified sigma E-RNA polymerase; therefore, we conclude that this polymerase interacts directly with the G4 promoter in vivo. The effects of these mutations also support the model in which sigma E-RNA polymerase utilizes promoters by interacting with two distinct sets of nucleotides located 10 and 35 base pairs upstream from the start point of transcription.
在枯草芽孢杆菌中发现的二级σ因子能够使RNA聚合酶在体外转录克隆的芽孢形成基因，这引发了一种观点，即芽孢形成过程中新σ因子的出现会引导RNA聚合酶转录不同时间类别的芽孢形成基因。其中一种在芽孢形成开始2小时后出现的σ因子是σE（以前称为σ29）。使σE的结构基因失活的突变会阻止从启动子G4进行转录。为了确定σE-RNA聚合酶在体内是否与G4启动子相互作用，我们检测了G4启动子中六个单碱基对替换对其在体内和体外被σE-RNA聚合酶利用的影响。G4启动子中的突变对其在体内的利用的影响方式与它们对纯化的σE-RNA聚合酶在体外利用的影响方式相同；因此，我们得出结论，这种聚合酶在体内直接与G4启动子相互作用。这些突变的影响也支持了这样一种模型，即σE-RNA聚合酶通过与位于转录起始点上游10和35个碱基对处的两组不同核苷酸相互作用来利用启动子。
