Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
Department of Molecular Structural Biology, Max Planck Institute for Biochemistry, Martinsried, Germany.
Nat Struct Mol Biol. 2017 Oct;24(10):809-815. doi: 10.1038/nsmb.3465. Epub 2017 Sep 11.
During transcription, RNA polymerase II (Pol II) associates with the conserved elongation factor DSIF. DSIF renders the elongation complex stable and functions during Pol II pausing and RNA processing. We combined cryo-EM and X-ray crystallography to determine the structure of the mammalian Pol II-DSIF elongation complex at a nominal resolution of 3.4 Å. Human DSIF has a modular structure with two domains forming a DNA clamp, two domains forming an RNA clamp, and one domain buttressing the RNA clamp. The clamps maintain the transcription bubble, position upstream DNA, and retain the RNA transcript in the exit tunnel. The mobile C-terminal region of DSIF is located near exiting RNA, where it can recruit factors for RNA processing. The structure provides insight into the roles of DSIF during mRNA synthesis.
在转录过程中，RNA 聚合酶 II（Pol II）与保守的延伸因子 DSIF 结合。DSIF 使延伸复合物稳定，并在 Pol II 暂停和 RNA 加工过程中发挥作用。我们结合冷冻电镜和 X 射线晶体学，以 3.4Å 的名义分辨率确定了哺乳动物 Pol II-DSIF 延伸复合物的结构。人类 DSIF 具有模块化结构，由两个形成 DNA 夹的结构域、两个形成 RNA 夹的结构域和一个支撑 RNA 夹的结构域组成。夹保持转录泡，定位上游 DNA，并将 RNA 转录本保留在出口隧道中。DSIF 的可移动 C 端区域位于即将离开的 RNA 附近，在此可以募集用于 RNA 加工的因子。该结构为 DSIF 在 mRNA 合成过程中的作用提供了深入了解。
