人类转录媒介复合体的结构基础,其可分离的激酶模块调节了该复合体
bioRxiv : the preprint server for biology
|July 15, 2024
概括
CDK8激酶模块 (CKM) 通过阻断RNA聚合酶II (Pol II) 与中介体复合体结合来抑制转录. 结构洞察力揭示了CKM如何阻碍转录启动并影响启动后的基因表达.
科学领域:
- 分子生物学分子生物学
- 结构生物学 结构生物学
- 基因规则 基因规则
背景情况:
- 由核 (cMED) 和可解离的CDK8激酶模块 (CKM) 组成的真核介质复合体,对于调节RNA聚合酶II (Pol II) 依存转录至关重要.
- 众所周知,CKM抑制了cMED招募Pol II和形成预启动复合体 (PIC) 的能力,并且还参与了启动后的基因表达控制.
研究的目的:
- 阐明CKM介导的cMED激活转录的抑制的结构基础.
- 了解CKM调节转录启动和启动后事件的分子机制.
主要方法:
- 使用冷电子显微镜 (cryo-EM) 确定了完整的人类调解器复合体及其CKM的结构.
- 进行了结构分析,以确定相互作用接口和硬质障碍机制.
主要成果:
- 通过MED13的内在无序区域 (IDR) 和MED12的HEAT重复,CKM与cMED结合.
- 在cMED上,MED13 IDR物理阻断了Pol II和MED26的结合部位,从而抑制了PIC的形成.
- 与TFIIH和+1核细胞体的固体阻碍进一步阻碍了转录启动.
- 绑定cMED的MED12 将CDK8定位在转录开始地点的下游,这表明它在启动后调节中发挥了作用.
结论:
- 该研究提供了高分辨率结构,解释了CKM在转录启动中的抑制作用.
- 这些发现揭示了CKM绑定如何阻碍Pol II招募和PIC组装.
- CDK8通过MED12的定位为其在启动后转录控制中的功能提供了新的见解.
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