Structural basis for-10 promoter element melting by environmentally induced sigma factors
Structural basis for-10 promoter element melting by environmentally induced sigma factors
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DOI：
10.1038/nsmb.2777
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发表时间：
2014-03-01
影响因子：
16.8
通讯作者：
Allain, Frederic H-T
中科院分区：
文献类型：
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作者：
Campagne, Sebastien;Marsh, May E.;Allain, Frederic H-T
细菌的转录由σ因子控制，σ因子是作为起始因子的RNA聚合酶亚基。虽然单个管家σ因子能够从数千个启动子转录，但环境诱导的σ因子将基因表达重定向到小的调节子以进行集中的应答。利用结构和功能分析，我们确定了大肠杆菌sigma（E）识别-10启动子元件的分子基础，这揭示了实现启动子解链的前所未有的方式。第IV组σ因子通过从非模板链DNA碱基堆叠中翻转出单个核苷酸来诱导-10元件处的链分离。这个关键碱基的非耐药性选择是由动态蛋白质环驱动的，该蛋白质环可以被取代以改变启动子识别的特异性。启动子熔化的这种机制解释了环境诱导的σ因子的启动子选择严格性增加。
Bacterial transcription is controlled by sigma factors, the RNA polymerase subunits that act as initiation factors. Although a single housekeeping sigma factor enables transcription from thousands of promoters, environmentally induced sigma factors redirect gene expression toward small regulons to carry out focused responses. Using structural and functional analyses, we determined the molecular basis of -10 promoter element recognition by Escherichia coli sigma(E), which revealed an unprecedented way to achieve promoter melting. Group IV sigma factors induced strand separation at the -10 element by flipping out a single nucleotide from the nontemplate-strand DNA base stack. Unambiguous selection of this critical base was driven by a dynamic protein loop, which can be substituted to modify specificity of promoter recognition. This mechanism of promoter melting explains the increased promoter-selection stringency of environmentally induced sigma factors.