Moreno Rosamaria Y, Juetten Kyle J, Panina Svetlana B, Butalewicz Jamie P, Floyd Brendan M, Venkat Ramani Mukesh Kumar, Marcotte Edward M, Brodbelt Jennifer S, Zhang Y Jessie
Department of Molecular Biosciences, University of Texas, Austin, TX, USA.
Department of Chemistry, University of Texas, Austin, TX, USA.
iScience. 2023 Aug 9;26(9):107581. doi: 10.1016/j.isci.2023.107581. eCollection 2023 Sep 15.
During eukaryotic transcription, RNA polymerase II undergoes dynamic post-translational modifications on the C-terminal domain (CTD) of the largest subunit, generating an information-rich PTM landscape that transcriptional regulators bind. The phosphorylation of Ser5 and Ser2 of CTD heptad occurs spatiotemporally with the transcriptional stages, recruiting different transcriptional regulators to Pol II. To delineate the protein interactomes at different transcriptional stages, we reconstructed phosphorylation patterns of the CTD at Ser5 and Ser2 . Our results showed that distinct protein interactomes are recruited to RNA polymerase II at different stages of transcription by the phosphorylation of Ser2 and Ser5 of the CTD heptads. In particular, we characterized calcium homeostasis endoplasmic reticulum protein (CHERP) as a regulator bound by phospho-Ser2 heptad. Pol II association with CHERP recruits an accessory splicing complex whose loss results in broad changes in alternative splicing events. Our results shed light on the PTM-coded recruitment process that coordinates transcription.
在真核生物转录过程中，RNA聚合酶II在最大亚基的C末端结构域（CTD）上经历动态的翻译后修饰，形成一个富含信息的翻译后修饰景观，转录调节因子可与之结合。CTD七肽的Ser5和Ser2的磷酸化与转录阶段在时空上同步发生，将不同的转录调节因子招募到Pol II。为了描绘不同转录阶段的蛋白质相互作用组，我们重建了CTD在Ser5和Ser2处的磷酸化模式。我们的结果表明，通过CTD七肽的Ser2和Ser5的磷酸化，在转录的不同阶段将不同的蛋白质相互作用组招募到RNA聚合酶II。特别是，我们将钙稳态内质网蛋白（CHERP）鉴定为一种与磷酸化Ser2七肽结合的调节因子。Pol II与CHERP的结合招募了一个辅助剪接复合体，其缺失会导致可变剪接事件发生广泛变化。我们的结果揭示了协调转录的翻译后修饰编码招募过程。
