The NusA:RNA polymerase ratio is increased at sites of rRNA synthesis in Bacillus subtilis
The NusA:RNA polymerase ratio is increased at sites of rRNA synthesis in Bacillus subtilis
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DOI：
10.1111/j.1365-2958.2005.04669.x
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发表时间：
2005-07-01
影响因子：
3.6
通讯作者：
Lewis, PJ
中科院分区：
文献类型：
--
作者：
Davies, KM;Dedman, AJ;Lewis, PJ
细菌RNA聚合酶（RNAP）能够使用体外测定在不存在额外因子的情况下产生全长转录物。然而，在体内RNAP可以成为停滞在转录的延伸阶段，由于各种序列基序的存在。随后，需要许多延伸因子来调节RNAP的活性。NusA是研究最深入的延伸因子，在增加RNAP暂停和终止中起作用。相反，它在rRNA的转录中也很重要，它作为抗终止因子发挥作用，有助于确保只产生全长转录本。在这里，我们表明，NusA是密切相关的RNAP内的细菌类核，它是优先招募到rRNA合成的网站。体内和体外分析表明，这导致在rRNA合成的亚细胞位点处NusA：RNAP的化学计量从1：1变化到约2：1。一个模型显示NusA：RNAP的比例如何影响延伸复合物的活性，使其在rRNA合成过程中起抗终止子复合物的作用。
Bacterial RNA polymerases (RNAPs) are capable of producing full-length transcripts in the absence of additional factors using in vitro assays. However, in vivo RNAP can become stalled during the elongation phase of transcription due to the presence of various sequence motifs. Subsequently, a host of elongation factors are required to modulate the activity of RNAP. NusA, the most intensively studied elongation factor, plays a role in increasing RNAP pausing and termination. Conversely, it is also important in transcription of rRNA where it functions as an anti-termination factor, helping to ensure only full-length transcripts are produced. Here we show that NusA is closely associated with RNAP within the bacterial nucleoid and that it is preferentially recruited to sites of rRNA synthesis. In vivo and in vitro analyses indicate this results in a change in stoichiometry of NusA:RNAP from 1:1 to approximately 2:1 at the subcellular sites of rRNA synthesis. A model is presented showing how the ratio of NusA:RNAP could affect the activity of the elongation complex so that it functions as an anti-terminator complex during rRNA synthesis.