Protein-DNA interactions that govern AAA+ activator-dependent bacterial transcription initiation
Protein-DNA interactions that govern AAA+ activator-dependent bacterial transcription initiation
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DOI：
10.1016/j.jmb.2007.10.045
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发表时间：
2008-01-04
影响因子：
5.6
通讯作者：
Buck, Martin
中科院分区：
文献类型：
--
作者：
Burrows, Patricia C.;Wigneshweraraj, Siva R.;Buck, Martin
在启动子解链步骤的转录控制尚未得到很好的理解。在这项研究中，一个定点的光交联方法被用来系统地分析组件蛋白质-DNA的相互作用，管理启动子熔化的增强子依赖性大肠杆菌RNA聚合酶（RNAP）含有sigma（54）启动子特异性因子（E sigma（54））在一个单一的碱基对分辨率在三个功能状态。sigma（54）因子通过在启动子解链成核处产生调节开关（类似于转录起始位点上游12 bp），对RNAP施加严格控制。通过E sigma（54）的启动子解链仅在ATP水解反应中通过专门的激活蛋白重塑该调节开关时触发。我们证明，在DNA解链之前，只有sigma（54）-因子直接与启动子相互作用，在初始封闭的E sigma（54）-启动子复合物和一个中间E sigma（54）-启动子复合物内的调节开关。我们确定，激活剂诱导的构象重排的调节开关是一个先决条件，让启动子进入RNAP的催化裂缝，从而建立转录能力开放的复合物，在那里发生完全启动子熔化。这些结果大大推进了我们目前对细菌启动子处发生的结构转变的理解，其中调控发生在DNA解链步骤。(c)2007爱思唯尔有限公司版权所有。
Transcriptional control at the promoter melting step is not yet well understood. In this study, a site-directed photo-cross-linking method was used to systematically analyse component protein-DNA interactions that govern promoter melting by the enhancer-dependent Escherichia coli RNA polymerase (RNAP) containing the sigma(54) promoter specificity factor (E sigma(54)) at a single base pair resolution in three functional states. The sigma(54)- factor imposes tight control upon the RNAP by creating a regulatory switch where promoter melting nucleates, similar to 12 bp upstream of the transcription start site. Promoter melting by E sigma(54) is only triggered upon remodelling of this regulatory switch by a specialised activator protein in an ATP-hydrolysing reaction. We demonstrate that prior to DNA melting, only the sigma(54)-factor directly interacts with the promoter in the regulatory switch within the initial closed E sigma(54)-promoter complex and one intermediate E sigma(54)-promoter complex. We establish that activator-induced conformational rearrangements in the regulatory switch are a prerequisite to allow the promoter to enter the catalytic cleft of the RNAP and hence establish the transcriptionally competent open complex, where full promoter melting occurs. These results significantly advance our current understanding of the structural transitions occurring at bacterial promoters, where regulation occurs at the DNA melting step. (c) 2007 Elsevier Ltd. All rights reserved.