Architecture of Fis-activated transcription complexes at the Escherichia coli rrnB P1 and rrnE P1 promoters
Architecture of Fis-activated transcription complexes at the Escherichia coli rrnB P1 and rrnE P1 promoters
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DOI：
10.1006/jmbi.2001.5390
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发表时间：
2002-02-22
影响因子：
5.6
通讯作者：
Gourse, RL
中科院分区：
文献类型：
--
作者：
Aiyar, SE;McLeod, SM;Gourse, RL
转录因子Fis通过分别结合到以-71和-72为中心的位点并与RNA聚合酶α亚基（RNAP alphaCTD）的C-末端结构域相互作用来激活大肠杆菌rRNA启动子rrnB P1和rrnE P1。为了理解Fis在这些启动子处激活的机制，我们使用定向的α-异源二聚体RNAP和Fis的异源二聚体来确定α和Fis的一个或两个亚基是否参与α CTD-Fis相互作用。我们的研究结果表明，只有一个alphaCTD的α二聚体和只有一个激活熟练的亚基的Fis二聚体所需的激活Fis。使用α中丙氨酸取代的文库来鉴定在rrnB P1和rrnE P1处的Fis依赖性转录所需的alphaCTD决定簇。我们提出，启动子近端亚基的Fis二聚体的转录激活区域与包括一个alphaCTD的E273的决定簇相互作用以激活转录。我们进一步表明，Fis与alphaCTD的接触导致alphaCTD与DNA的相互作用，这与在不存在Fis的情况下在UP元件处发生的相互作用有些不同。随附的论文显示，α CTD上的273决定簇也被Fis靶向proP P2启动子，其中激活剂与-35六聚体重叠结合。因此，当激活剂结合在DNA上非常不同的位置时，类似的Fis-alphaCTD相互作用用于激活转录。(C)2002 Elsevier Science Ltd.
The transcription factor Fis activates the Escherichia coli rRNA promoters rrnB P1 and rrnE PI by binding to sites centered at -71 and -72, respectively, and interacting with the C-terminal domain of the a subunit of RNA polymerase (RNAP alphaCTD). To understand the mechanism of activation by Fis at these promoters, we used oriented alpha-heterodimeric RNAPs and heterodimers of Fis to determine whether one or both subunits of alpha and Fis participate in the alphaCTD-Fis interaction. Our results imply that only one alphaCTD in the a dimer and only one activation-proficient subunit in the Fis dimer are required for activation by Fis. A library of alanine substitutions in alpha was used to identify the alphaCTD determinants required for Fis-dependent transcription at rrnB PI and rrnE P1. We propose that the transcriptional activation region of the promoter-proximal subunit of the Fis dimer interacts with a determinant that includes E273 of one alphaCTD to activate transcription. We further suggest that the Fis contact to alphaCTD results in alphaCTD interactions with DNA that differ somewhat from those that occur at UP elements in the absence of Fis. The accompanying paper shows that the 273 determinant on alphaCTD is also targeted by Fis at the proP P2 promoter where the activator binds overlapping the -35 hexamer. Thus, similar Fis-alphaCTD interactions are used for activation of transcription when the activator is bound at very different positions on the DNA. (C) 2002 Elsevier Science Ltd.