RNA polymerase switches between inactivated and activated states by translocating back and forth along the DNA and the RNA
RNA polymerase switches between inactivated and activated states by translocating back and forth along the DNA and the RNA
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DOI：
10.1074/jbc.272.24.15329
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发表时间：
1997-06-13
影响因子：
4.8
通讯作者：
Kashlev, M
中科院分区：
文献类型：
--
作者：
Komissarova, N;Kashlev, M
目前，原核和真核转录中的重要调控事件都是用伸长的插入蠕虫模型来解释的，在这个模型中，RNA的延伸是由一个移动的催化中心进行的，该中心在某些DNA位点上推进固定的RNA聚合酶。这个想法是从观察到个体延长复合体的足迹产生的，在体外停止在连续的DNA位置，可以保持固定在模板上进行几个连续的核苷酸加成。在这里，我们详细地研究了酶在观察到RNA聚合酶不连续推进的位点停止后立即发生的结构转变，我们证明，在这样的特殊位点停止并不能使RNA聚合酶在一个位置“冻结”，而是诱导它离开其初始位置，并沿着DNA和RNA向后滑动，而不会降低转录本的质量。RNA聚合酶被认为是一个在催化活性和非活性状态之间切换的振荡对象，因此]RNA聚合酶被认为是一个振荡的对象。退缩的异构体构成了因子诱导的核内溶解RNA裂解的主要中间体。RNA聚合酶的这些振荡可以解释其明显的不连续推进，这被解释为表明酶内的灵活性。
Important regulatory events in both prokaryotic and eukaryotic transcription are currently explained in terms of an inchworming model of elongation, In this model, RNA extension is carried out by a mobile catalytic center that, at certain DNA sites, advances within stationary RNA polymerase. This idea emerged from the observation that footprints of individual elongation complexes, halted in vitro at consecutive DNA positions, can remain fixed on the template for several contiguous nucleotide additions. Here, we examine in detail the structural transitions that occur immediately after the enzyme stops at sites where discontinuous advancement of RNA polymerase is observed, We demonstrate that halting at such special sites does not ''freeze'' RNA polymerase at one location but induces it to leave its initial position and to slide backward along the DNA and the RNA without degrading the transcript. The resulting loss of contact between the RNA S'-hydroxyl and the enzyme's catalytic center leads to temporary loss of the catalytic activity, This process is equilibrated with enzyme return to the original location, so that]RNA polymerase is envisaged as an oscillating object switching between catalytically active and inactive states. The retreated isoform constitutes a principal intermediate in factor-induced endonucleolytic RNA cleavage. These oscillations of RNA polymerase can explain its apparent discontinuous advancement, which had been interpreted as indicating flexibility within the enzyme.