Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Baddiley-Clark Building, Richardson Road, Newcastle upon Tyne NE2 4AX, UK.
Nucleic Acids Res. 2011 May;39(10):4352-9. doi: 10.1093/nar/gkq1359. Epub 2011 Jan 25.
The highly processive transcription by multi-subunit RNA polymerases (RNAP) can be interrupted by misincorporation or backtracking events that may stall transcription or lead to erroneous transcripts. Backtracked/misincorporated complexes can be resolved via hydrolysis of the transcript. Here, we show that, in response to misincorporation and/or backtracking, the catalytic domain of RNAP active centre, the trigger loop (TL), is substituted by transcription factor Gre. This substitution turns off the intrinsic TL-dependent hydrolytic activity of RNAP active centre, and exchanges it to a far more efficient Gre-dependent mechanism of RNA hydrolysis. Replacement of the TL by Gre factor occurs only in backtracked/misincorporated complexes, and not in correctly elongating complexes. This controlled switching of RNAP activities allows the processivity of elongation to be unaffected by the hydrolytic activity of Gre, while ensuring efficient proofreading of transcription and resolution of backtracked complexes.
多亚基 RNA 聚合酶（RNAP）的高度连续转录可能会被错误掺入或回溯事件中断，这些事件可能会使转录停滞或导致错误的转录本。回溯/错误掺入的复合物可以通过转录物的水解来解决。在这里，我们表明，在响应错误掺入和/或回溯时，RNAP 活性中心的催化结构域、触发环（TL）被转录因子 Gre 取代。这种取代关闭了 RNAP 活性中心内在的 TL 依赖性水解活性，并将其交换为一种更有效的 Gre 依赖性 RNA 水解机制。只有在回溯/错误掺入的复合物中，TL 才会被 Gre 因子取代，而在正确延伸的复合物中则不会。这种 RNAP 活性的受控切换允许延伸的连续性不受 Gre 水解活性的影响，同时确保转录的有效校对和回溯复合物的解决。
