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首页> 外文期刊>Journal of Molecular Biology >Novel protein-protein interaction between Escherichia coli SoxS and the DNA binding determinant of the RNA polymerase alpha subunit: SoxS functions as a co-sigma factor and redeploys RNA polymerase from UP-element-containing promoters to SoxS-depende
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Novel protein-protein interaction between Escherichia coli SoxS and the DNA binding determinant of the RNA polymerase alpha subunit: SoxS functions as a co-sigma factor and redeploys RNA polymerase from UP-element-containing promoters to SoxS-depende

机译：大肠杆菌SoxS与RNA聚合酶α亚基的DNA结合决定子之间的新型蛋白质相互作用：SoxS充当共和因子，并将RNA聚合酶从含UP元素的启动子重新部署到SoxS依赖性

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SoxS is the transcription activator of the SoxRS regulon. Despite being synthesized de novo in response to oxidative stress and despite the large disparity between the number of SoxS binding sites and the number of SoxS molecules per cell, SoxS-dependent promoters are rapidly activated after the onset of the stress. With the usual recruitment/post-recruitment mechanisms being unsuitable for activating gene expression under these wconditions, we previously proposed that SoxS functions by "pre-recruitment". In pre-recruitment, SoxS forms SoxS-RNA polymerase binary complexes, which use the DNA binding properties of SoxS and sigma(70) to distinguish SoxS-dependent promoters from housekeeping promoters and from the large number of sequence equivalent but functionally irrelevant SoxS binding sites. With previous work in Escherichia coli having indicated that the most likely target on RNA polymerase for interaction with SoxS is the C-terminal domain of alpha, we investigated the interaction directly with the yeast two-hybrid system. We found that SoxS interacts with the alphaCTD and that SoxS positive control mutations disrupt the interaction. Moreover, single alanine substitutions of the alphaCTD that reduce or enhance SoxS activation in E. coli reduce or enhance the interaction between SoxS and the alphaCTD in yeast. Significantly, the critical amino acid residues lie in and around the DNA binding determinant of the alphaCTD, the first example of an activator contacting this determinant. These interactions were confirmed with an affinity immobilization assay. Lastly, we found that SoxS induction interferes with utilization of the UP element of an rRNA promoter. Thus, by functioning as a co-sigma factor that interacts with the DNA binding determinant of the alphaCTD, SoxS diverts RNA polymerase from UP-containing promoters to SoxS-activatable promoters. (C) 2004 Elsevier Ltd. All rights reserved.
机译：SoxS是SoxRS调节子的转录激活因子。尽管是响应氧化应激从头合成的，并且尽管SoxS结合位点的数量与每个细胞的SoxS分子的数量之间存在巨大差异，但是在应激开始后，依赖于SoxS的启动子仍被迅速激活。由于通常的募集/募集后机制不适合在这些条件下激活基因表达，因此我们先前提出SoxS通过“预募集”发挥功能。在招募前，SoxS形成了SoxS-RNA聚合酶二元复合物，该复合物利用SoxS和sigma（70）的DNA结合特性将SoxS依赖性启动子与管家启动子以及大量序列等同但功能上无关的SoxS结合位点区分开。先前在大肠杆菌中的工作表明与SoxS相互作用的RNA聚合酶最可能的靶标是α的C末端结构域，我们直接研究了与酵母双杂交系统的相互作用。我们发现SoxS与alphaCTD相互作用，并且SoxS阳性对照突变破坏了相互作用。而且，减少或增强大肠杆菌中SoxS活化的αCTD的单个丙氨酸取代减少或增强了酵母中SoxS与αCTD之间的相互作用。重要的是，关键氨基酸残基位于alphaCTD的DNA结合决定簇内和周围，这是激活剂与该决定簇接触的第一个例子。这些相互作用用亲和力固定测定法确认。最后，我们发现SoxS诱导干扰rRNA启动子的UP元件的利用。因此，SoxS通过充当与αCTD的DNA结合决定簇相互作用的co-σ因子，将RNA聚合酶从含UP的启动子转移到可激活SoxS的启动子。 （C）2004 Elsevier Ltd.保留所有权利。

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