Organization of an activator-bound RNA polymerase holoenzyme.
Organization of an activator-bound RNA polymerase holoenzyme.
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DOI：
10.1016/j.molcel.2008.09.015
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发表时间：
2008-11-07
期刊：
影响因子：
16
通讯作者：
Zhang, Xiaodong
中科院分区：
文献类型：
--
作者：
Bose, Daniel;Pape, Tillmann;Burrows, Patricia C.;Rappas, Mathieu;Wigneshweraraj, Siva R.;Buck, Martin;Zhang, Xiaodong
转录起始涉及从封闭的启动子复合体(包括RNA聚合酶(RNAP)和双链启动子DNA)到开放复合体的转换，在开放复合体中，酶能够以单链的形式访问DNA模板。细菌RNAP与其主要变异型Sigma因子σ54之间的复合体一直是封闭的复合体，直到激活蛋白发生依赖于ATP水解的重塑。这种重塑促进了DNA的融化，并允许向开放复合体的过渡。在这里，我们提出了细菌的RNAP与σ54单独的复合体和RNAP-σ54与AAA+激活剂的冷冻电子显微镜重建。结合光交联数据确定启动子在复合体中的位置，我们解释了为什么RNAP-σ54闭合复合体不能获得DNA模板，并提出了由激活剂结合引起的结构变化如何引发构象变化，最终导致开放复合体的形成。
Transcription initiation involves the conversion from closed promoter complexes, comprising RNA polymerase (RNAP) and double-stranded promoter DNA, to open complexes, in which the enzyme is able to access the DNA template in a single-stranded form. The complex between bacterial RNAP and its major variant sigma factor σ54 remains as a closed complex until ATP hydrolysis-dependent remodeling by activator proteins occurs. This remodeling facilitates DNA melting and allows the transition to the open complex. Here we present cryoelectron microscopy reconstructions of bacterial RNAP in complex with σ54 alone, and of RNAP-σ54 with an AAA+ activator. Together with photo-crosslinking data that establish the location of promoter DNA within the complexes, we explain why the RNAP-σ54 closed complex is unable to access the DNA template and propose how the structural changes induced by activator binding can initiate conformational changes that ultimately result in formation of the open complex.
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