Igo M M, Losick R
J Mol Biol. 1986 Oct 20;191(4):615-24. doi: 10.1016/0022-2836(86)90449-3.
The ctc gene of Bacillus subtilis is transcribed in vitro by the minor RNA polymerase holoenzyme forms, E sigma 37 and E sigma 32. To study the expression and regulation of ctc in vivo, we constructed operon and translational fusions of the ctc promoter region to the lacZ gene of Escherichia coli. Our results indicate that ctc is regulated at the transcriptional level, and that this RNA synthesis is maximally induced at the end of the exponential phase of growth under nutritional conditions which inhibit the activity of the tricarboxylic acid cycle. Analysis of in vitro-constructed deletion mutations extending into the ctc promoter region demonstrated that the region required for this regulation is no greater than 53 base-pairs in length. We also compared the expression of ctc to that of another B. subtilis gene, which is transcribed by E sigma 37 and E sigma 32 in vitro, the sporulation gene spoVG. Although the ctc and spoVG promoter regions are recognized by the same forms of RNA polymerase in vitro, our results show that they differ strikingly in the nutritional and genetic requirements for their expression in vivo.
枯草芽孢杆菌的ctc基因在体外由次要的RNA聚合酶全酶形式E σ37和E σ32转录。为了研究ctc在体内的表达和调控，我们构建了ctc启动子区域与大肠杆菌lacZ基因的操纵子融合和翻译融合。我们的结果表明，ctc在转录水平受到调控，并且在抑制三羧酸循环活性的营养条件下，这种RNA合成在生长指数期结束时被最大程度地诱导。对延伸到ctc启动子区域的体外构建缺失突变的分析表明，这种调控所需的区域长度不超过53个碱基对。我们还比较了ctc与另一个枯草芽孢杆菌基因的表达，该基因在体外由E σ37和E σ32转录，即芽孢形成基因spoVG。尽管ctc和spoVG启动子区域在体外被相同形式的RNA聚合酶识别，但我们的结果表明，它们在体内表达的营养和遗传需求方面存在显著差异。
