J. David Gladstone Institutes, San Francisco, CA 94158, USA; Department of Medicine, University of California San Francisco, San Francisco, CA 94143, USA.
Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, CA 94143, USA.
Mol Cell. 2019 Jun 20;74(6):1164-1174.e4. doi: 10.1016/j.molcel.2019.04.008. Epub 2019 May 1.
Post-translational modifications of the RNA polymerase II C-terminal domain (CTD) coordinate the transcription cycle. Crosstalk between different modifications is poorly understood. Here, we show how acetylation of lysine residues at position 7 of characteristic heptad repeats (K7ac)-only found in higher eukaryotes-regulates phosphorylation of serines at position 5 (S5p), a conserved mark of polymerases initiating transcription. We identified the regulator of pre-mRNA-domain-containing (RPRD) proteins as reader proteins of K7ac. K7ac enhanced CTD peptide binding to the CTD-interacting domain (CID) of RPRD1A and RPRD1B proteins in isothermal calorimetry and molecular modeling experiments. Deacetylase inhibitors increased K7ac- and decreased S5-phosphorylated polymerases, consistent with acetylation-dependent S5 dephosphorylation by an RPRD-associated S5 phosphatase. Consistent with this model, RPRD1B knockdown increased S5p but enhanced K7ac, indicating that RPRD proteins recruit K7 deacetylases, including HDAC1. We also report autoregulatory crosstalk between K7ac and S5p via RPRD proteins and their interactions with acetyl- and phospho-eraser proteins.
RNA 聚合酶 II C 末端结构域（CTD）的翻译后修饰协调转录周期。不同修饰之间的串扰知之甚少。在这里，我们展示了仅在高等真核生物中发现的特征七肽重复序列（K7ac）上赖氨酸残基的乙酰化如何调节丝氨酸（S5p）的磷酸化，S5p 是启动转录的聚合酶的保守标记。我们确定了前体 RNA 结构域包含（RPRD）蛋白作为 K7ac 的读取蛋白。在等温量热法和分子建模实验中，K7ac 增强了 CTD 肽与 RPRD1A 和 RPRD1B 蛋白的 CTD 相互作用结构域（CID）的结合。去乙酰化酶抑制剂增加了 K7ac 和减少了 S5 磷酸化的聚合酶，与 RPRD 相关的 S5 磷酸酶依赖于乙酰化的 S5 去磷酸化一致。与该模型一致，RPRD1B 敲低增加了 S5p，但增强了 K7ac，表明 RPRD 蛋白募集了 K7 去乙酰化酶，包括 HDAC1。我们还报告了通过 RPRD 蛋白及其与乙酰化和磷酸化擦除蛋白的相互作用，K7ac 和 S5p 之间的自动调节串扰。
