Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Republic of Korea.
Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, 1230 York Avenue, New York, NY, USA.
Nat Commun. 2022 Aug 15;13(1):4668. doi: 10.1038/s41467-022-32315-y.
Transcription, in which RNA polymerases (RNAPs) produce RNA from DNA, is the first step of gene expression. As such, it is highly regulated either by trans-elements like protein factors and/or by cis-elements like specific sequences on the DNA. Lambdoid phage HK022 contains a cis-element, put, which suppresses pausing and termination during transcription of the early phage genes. The putRNA transcript solely performs the anti-pausing/termination activities by interacting directly with the E.coli RNAP elongation complex (EC) by an unknown structural mechanism. In this study, we reconstituted putRNA-associated ECs and determined the structures using cryo-electron microscopy. The determined structures of putRNA-associated EC, putRNA-absent EC, and σ-bound EC suggest that the putRNA interaction with the EC counteracts swiveling, a conformational change previously identified to promote pausing and σ might modulate putRNA folding via σ-dependent pausing during elongation.
转录是指 RNA 聚合酶（RNAPs）从 DNA 生成 RNA，是基因表达的第一步。因此，它受到转录因子（如蛋白质因子）等转位元件和 DNA 上特定序列等顺式元件的高度调控。λ噬菌体 HK022 含有一个顺式元件 put，它在早期噬菌体基因转录过程中抑制暂停和终止。putRNA 转录本通过未知的结构机制直接与大肠杆菌 RNAP 延伸复合物（EC）相互作用，仅通过相互作用就能发挥抗暂停/终止活性。在这项研究中，我们重建了与 putRNA 相关的 EC，并使用冷冻电镜确定了其结构。与 putRNA 相关的 EC、没有 putRNA 的 EC 和 σ 结合的 EC 的结构表明，putRNA 与 EC 的相互作用阻止了旋转，这是先前确定的促进暂停的构象变化，而 σ 可能通过在延伸过程中依赖 σ 的暂停来调节 putRNA 折叠。
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