Del Peso Santos Teresa, Shingler Victoria
Department of Molecular Biology, Umeå University, Umeå SE 90187, Sweden.
Department of Molecular Biology, Umeå University, Umeå SE 90187, Sweden
Nucleic Acids Res. 2016 Nov 16;44(20):9638-9649. doi: 10.1093/nar/gkw639. Epub 2016 Jul 15.
Divergent transcription from within bacterial intergenic regions frequently involves promoters dependent on alternative σ-factors. This is the case for the non-overlapping σ- and σ-dependent promoters that control production of the substrate-responsive regulator and enzymes for (methyl)phenol catabolism. Here, using an array of in vivo and in vitro assays, we identify transcription-driven supercoiling arising from the σ-promoter as the mechanism underlying inter-promoter communication that results in stimulation of the activity of the σ-promoter. The non-overlapping 'back-to-back' configuration of a powerful σ-promoter and weak σ-promoter within this system offers a previously unknown means of inter-sigmulon communication that renders the σ-promoter subservient to signals that elicit σ-dependent transcription without it possessing a cognate binding site for the σ-RNA polymerase holoenzyme. This mode of control has the potential to be a prevalent, but hitherto unappreciated, mechanism by which bacteria adjust promoter activity to gain appropriate transcriptional control.
细菌基因间区域内的分歧转录通常涉及依赖于替代σ因子的启动子。控制底物响应调节因子和（甲基）苯酚分解代谢酶产生的非重叠σ和σ依赖性启动子就是这种情况。在这里，我们使用一系列体内和体外试验，确定了由σ启动子产生的转录驱动超螺旋是启动子间通信的基础机制，这种通信导致σ启动子活性的刺激。该系统中强大的σ启动子和弱σ启动子的非重叠“背对背”配置提供了一种以前未知的西格玛操纵子间通信方式，使σ启动子服从于引发σ依赖性转录的信号，而无需其拥有σ-RNA聚合酶全酶的同源结合位点。这种控制模式有可能是一种普遍但迄今未被认识到的机制，细菌通过该机制调整启动子活性以获得适当的转录控制。
