Mechanism of NusG-stimulated pausing, hairpin-dependent pause site selection and intrinsic termination at overlapping pause and termination sites in the Bacillus subtilis trp leader.
Mechanism of NusG-stimulated pausing, hairpin-dependent pause site selection and intrinsic termination at overlapping pause and termination sites in the Bacillus subtilis trp leader.
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NusG 刺激的暂停机制、发夹依赖性暂停位点选择以及枯草芽孢杆菌 trp 前导序列中重叠暂停和终止位点的内在终止。
DOI：
10.1111/j.1365-2958.2010.07126.x
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发表时间：
2010
影响因子：
3.6
通讯作者：
Babitzke,Paul
中科院分区：
文献类型：
--
作者：
Yakhnin,AlexanderV;Babitzke,Paul
枯草芽孢杆菌trpEDCFBA操纵子受TRAP依赖性转录衰减和翻译抑制机制调节。先前的结果表明，NusA和NusG协同刺激RNA聚合酶在pleader中的U107和U144处暂停，并且在体内需要NusG才能在U144处暂停。在U107和U144处的暂停通过为TRAP结合提供额外的时间而分别参与衰减和翻译抑制机制。intrinsictrpleader终止子与发夹依赖性U144暂停位点重叠。在这里，我们进行了系统的突变分析的终止子/暂停区。删除发夹减少停顿，但不影响停顿位点的选择。因此，对于这个暂停位点，发夹刺激暂停是比发夹依赖暂停更合适的术语。相比之下，发夹结构的微小变化废除了终止。发夹后富含U/T的序列对终止和暂停的影响不同。发夹和RNA 3′端之间的距离决定了终止的位置，而发夹下游的序列负责暂停位点的选择。发现NusA通过降低转录速率来增加暂停和终止。我们还发现，NusG刺激的停顿是序列特异性的，NusG不影响终止。
TheBacillus subtilis trpEDCFBAoperon is regulated by TRAP‐dependent transcription attenuation and translation repression mechanisms. Previous results showed that NusA and NusG cooperatively stimulate RNA polymerase pausing at U107 and U144 in thetrpleader, and that NusG is required for pausing at U144in vivo. Pausing at U107 and U144 participate in the attenuation and translation repression mechanisms, respectively, by providing additional time for TRAP binding. The intrinsictrpleader terminator overlaps the hairpin‐dependent U144 pause site. Here, we conducted a systematic mutational analysis of the terminator/pause region. Deletion of the hairpin reduced pausing but did not affect pause site selection. Thus, hairpin‐stimulated pausing is a more appropriate term than hairpin‐dependent pausing for this pause site. In contrast, minor changes to the hairpin abolished termination. Sequences in the U‐rich/T‐rich tract following the hairpin affected termination and pausing differentially. The distance between the hairpin and the 3′ end of the RNA dictates the position of termination, whereas the sequence downstream from the hairpin is responsible for pause site selection. NusA was found to increase both pausing and termination by reducing the rate of transcription. We also found that NusG‐stimulated pausing is sequence specific and that NusG does not affect termination.