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首页> 外文期刊>Journal of Molecular Biology >Genetic evidence for a novel interaction between transcriptional activator soxs and region 4 of the sigma(70) subunit of RNA polymerase at class ii SoxS-dependent promoters in Escherichia coli.
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Genetic evidence for a novel interaction between transcriptional activator soxs and region 4 of the sigma(70) subunit of RNA polymerase at class ii SoxS-dependent promoters in Escherichia coli.

机译：转录激活因子soxs与RNA聚合酶的ii类SoxS依赖性启动子上的RNA聚合酶sigma（70）亚基的区域4之间的新型相互作用的遗传证据。

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Escherichia coli SoxS activates transcription of the genes of the soxRS regulon, which provide the cell's defense against oxidative stress. In response to this stress, SoxS is synthesized de novo. Because the DNA binding site of SoxS is highly degenerate, SoxS efficiently activates transcription by the mechanism of prerecruitment. In prerecruitment, newly synthesized SoxS first forms binary complexes with RNA polymerase. These complexes then scan the chromosome for class I and II SoxS-dependent promoters, using the specific DNA-recognition properties of SoxS and sigma(70) to distinguish SoxS-dependent promoters from the vast excess of sequence-equivalent soxboxes that do not reside in promoters. Previously, we determined that SoxS interacts with RNA polymerase in two ways: by making protein-protein interactions with the DNA-binding determinant of the alpha subunit and by interacting with sigma(70) region 4 (sigma(70) R4) both "on-DNA" and "off-DNA." Here, we address the question of how SoxS and sigma(70) R4 coexist at class II promoters, where the binding site for SoxS either partially or completely overlaps the -35 region of the promoter, which is usually bound by sigma(70) R4. To do so, we created a tri-alanine scanning library that covers all of sigma(70) R4. We determined that interactions between sigma(70) R4 and the DNA in the promoter's -35 region are required for activation of class I promoters, where the binding site lies upstream of the -35 hexamer, but they are not required at class II promoters. In contrast, specific three-amino-acid stretches are required for activation of class I (lac) and class II (galP1) cyclic AMP receptor protein-dependent promoters. We conclude from these data that SoxS and sigma(70) R4 interact with each other in a novel way at class II SoxS-dependent promoters such that the two proteins do not accommodate one another in the -35 region but instead SoxS binding there occludes the binding of sigma(70) R4.
机译：大肠杆菌SoxS激活soxRS regulon基因的转录，从而提供细胞抵御氧化应激的防御作用。为了应对这种压力，SoxS从头开始合成。由于SoxS的DNA结合位点高度简并，因此SoxS通过预招募机制有效激活了转录。在预招募中，新合成的SoxS首先与RNA聚合酶形成二元复合物。然后，这些复合物使用SoxS和sigma（70）的特定DNA识别特性，在染色体上扫描I和II类SoxS依赖的启动子，以将SoxS依赖的启动子与大量不存在于序列中的soxbox区分开来发起人。以前，我们确定SoxS通过两种方式与RNA聚合酶相互作用：通过使蛋白质与蛋白质与α亚基的DNA结合决定簇相互作用，以及与sigma（70）region 4（sigma（70）R4）相互作用-DNA”和“非DNA”。在这里，我们解决了SoxS和sigma（70）R4如何在II类启动子上共存的问题，其中SoxS的结合位点部分或完全重叠了启动子的-35区，通常与sigma（70）R4结合。为此，我们创建了一个涵盖所有sigma（70）R4的三丙氨酸扫描库。我们确定sigma（70）R4和启动子-35区域中的DNA之间的相互作用是激活I类启动子所必需的，其中结合位点位于-35六聚体的上游，但在II类启动子上则不需要。相反，激活I类（lac）和II类（galP1）环状AMP受体蛋白依赖性启动子需要特定的三个氨基酸序列。我们从这些数据得出结论，SoxS和sigma（70）R4在II类SoxS依赖性启动子上以新颖的方式相互作用，因此这两种蛋白在-35区互不容纳，而是在那里结合的SoxS封闭了σ（70）R4的绑定。

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