Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, UK.
EMBO J. 2011 Jul 26;30(18):3766-75. doi: 10.1038/emboj.2011.252.
Bacterial promoters are recognized by RNA polymerase (RNAP) σ subunit, which specifically interacts with the -10 and -35 promoter elements. Here, we provide evidence that the β' zipper, an evolutionarily conserved loop of the largest subunit of RNAP core, interacts with promoter spacer, a DNA segment that separates the -10 and -35 promoter elements, and facilitates the formation of stable closed promoter complex. Depending on the spacer sequence, the proposed interaction of the β' zipper with the spacer can also facilitate open promoter complex formation and even substitute for interactions of the σ subunit with the -35 element. These results suggest that there exists a novel class of promoters that rely on interaction of the β' zipper with promoter spacer, along with or instead of interactions of σ subunit with the -35 element, for their activity. Finally, our data suggest that sequence-dependent interactions of the β' zipper with DNA can contribute to promoter-proximal σ-dependent RNAP pausing, a recently recognized important step of transcription control.
细菌启动子被 RNA 聚合酶 (RNAP) σ 亚基识别，后者特异性地与 -10 和 -35 启动子元件相互作用。在这里，我们提供的证据表明，β'拉链，RNAP 核心大亚基的一个进化保守环，与启动子间隔区相互作用，后者是分隔 -10 和 -35 启动子元件的 DNA 片段，并促进稳定的封闭启动子复合物的形成。根据间隔序列，β'拉链与间隔区的提议相互作用还可以促进开放启动子复合物的形成，甚至可以替代 σ 亚基与 -35 元件的相互作用。这些结果表明，存在一类新的启动子，它们依赖于 β'拉链与启动子间隔区的相互作用，以及或代替 σ 亚基与 -35 元件的相互作用，来发挥其活性。最后，我们的数据表明，β'拉链与 DNA 的序列依赖性相互作用可以促进启动子近端 σ 依赖性 RNA 聚合酶暂停，这是最近发现的转录调控的一个重要步骤。
