Ring B Z, Yarnell W S, Roberts J W
Section of Biochemistry, Molecular and Cell Biology Cornell University Ithaca, New York 14853, USA.
Cell. 1996 Aug 9;86(3):485-93. doi: 10.1016/s0092-8674(00)80121-x.
The sigma factor sigma 70 of E. coli RNA polymerase acts not only in initiation, but also at an early stage of elongation to induce a transcription pause, and simultaneously to allow the phage lambda gene Q transcription antiterminator to act. We identify the signal in DNA that induces early pausing to be a version of the sigma 70 -10 promoter consensus, and we show that sigma 70 is both necessary for pausing and present in the paused transcription complex. Regions 2 and 3 of sigma 70 suffice to induce pausing. Since pausing is induced by the nontemplate DNA strand of the open transcription bubble, we conclude that RNA polymerase containing sigma 70 carries out base-specific recognition of the nontemplate strand as single stranded DNA. We suggest that sigma 70 remains bound to core RNA polymerase when the -10 promoter contacts are broken, and then moves to the pause-inducing sequence.
大肠杆菌RNA聚合酶的σ因子σ70不仅在起始阶段发挥作用，还在延伸的早期阶段诱导转录暂停，同时允许噬菌体λ基因Q转录抗终止子发挥作用。我们确定诱导早期暂停的DNA信号是σ70 -10启动子共有序列的一个变体，并且我们表明σ70对于暂停是必需的，并且存在于暂停的转录复合物中。σ70的区域2和区域3足以诱导暂停。由于暂停是由开放转录泡的非模板DNA链诱导的，我们得出结论，含有σ70的RNA聚合酶对作为单链DNA的非模板链进行碱基特异性识别。我们认为，当-10启动子接触断开时，σ70仍与核心RNA聚合酶结合，然后移动到诱导暂停的序列。
