Max Planck Institute for Biophysical Chemistry, Department of Molecular Biology, Göttingen, Germany.
Max Planck Institute for Biophysical Chemistry, Bioanalytical Mass Spectrometry, Göttingen, Germany.
Nature. 2018 Aug;560(7720):601-606. doi: 10.1038/s41586-018-0442-2. Epub 2018 Aug 22.
Metazoan gene regulation often involves the pausing of RNA polymerase II (Pol II) in the promoter-proximal region. Paused Pol II is stabilized by the protein complexes DRB sensitivity-inducing factor (DSIF) and negative elongation factor (NELF). Here we report the cryo-electron microscopy structure of a paused transcription elongation complex containing Sus scrofa Pol II and Homo sapiens DSIF and NELF at 3.2 Å resolution. The structure reveals a tilted DNA-RNA hybrid that impairs binding of the nucleoside triphosphate substrate. NELF binds the polymerase funnel, bridges two mobile polymerase modules, and contacts the trigger loop, thereby restraining Pol II mobility that is required for pause release. NELF prevents binding of the anti-pausing transcription elongation factor IIS (TFIIS). Additionally, NELF possesses two flexible 'tentacles' that can contact DSIF and exiting RNA. These results define the paused state of Pol II and provide the molecular basis for understanding the function of NELF during promoter-proximal gene regulation.
真核生物基因调控通常涉及 RNA 聚合酶 II（Pol II）在启动子近端区域的暂停。暂停的 Pol II 由蛋白复合物 DRB 敏感性诱导因子（DSIF）和负延伸因子（NELF）稳定。在这里，我们报告了一个暂停转录延伸复合物的冷冻电镜结构，该复合物含有 Sus scrofa Pol II 和 Homo sapiens DSIF 和 NELF，分辨率为 3.2Å。该结构揭示了一个倾斜的 DNA-RNA 杂交体，该杂交体阻碍了核苷三磷酸底物的结合。NELF 结合聚合酶漏斗，桥接两个移动的聚合酶模块，并与触发环接触，从而限制了 Pol II 释放暂停所需的移动性。NELF 阻止抗暂停转录延伸因子 IIS（TFIIS）的结合。此外，NELF 具有两个灵活的“触手”，可以与 DSIF 和正在退出的 RNA 接触。这些结果定义了 Pol II 的暂停状态，并为理解 NELF 在启动子近端基因调控过程中的功能提供了分子基础。
