RNA Polymerase II C-terminal Heptarepeat Domain Ser-7 Phosphorylation Is Established in a Mediator-dependent Fashion
RNA Polymerase II C-terminal Heptarepeat Domain Ser-7 Phosphorylation Is Established in a Mediator-dependent Fashion
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DOI：
10.1074/jbc.m109.046565
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发表时间：
2010-01-01
影响因子：
4.8
通讯作者：
Meisterernst, Michael
中科院分区：
文献类型：
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作者：
Boeing, Stefan;Rigault, Caroline;Meisterernst, Michael
RNA聚合酶II (RNAPII) c端七萜结构域（CTD）的最大亚基在RNA聚合酶II的转录起始和延伸过程中被磷酸化。在这里，我们研究了导致人类酶中Ser-7磷酸化的分子机制。Ser-7在启动子区域转录开始前被磷酸化。我们确定周期蛋白依赖性激酶7 （CDK7）是一个负责任的激酶。Ser-5和Ser-7的磷酸化完全依赖于辅助因子复合物Mediator。与活性RNAPII相关的Mediator亚型对起始前复合物的形成和CTD磷酸化至关重要。介导体- rnapii复合体独立地将TFIIB和CDK7招募到核心启动子区域。CDK7在完整起始前复合物的情况下选择性地磷酸化Ser-7。CDK7不是唯一可以修饰CTD的Ser-7的激酶。化学抑制剂的ChIP实验提供了证据，证明其他尚未鉴定的激酶进一步磷酸化编码区Ser-7。
The largest subunit of RNA polymerase II (RNAPII) C-terminal heptarepeat domain (CTD) is subject to phosphorylation during initiation and elongation of transcription by RNA polymerase II. Here we study the molecular mechanisms leading to phosphorylation of Ser-7 in the human enzyme. Ser-7 becomes phosphorylated before initiation of transcription at promoter regions. We identify cyclin-dependent kinase 7 (CDK7) as one responsible kinase. Phosphorylation of both Ser-5 and Ser-7 is fully dependent on the cofactor complex Mediator. A subform of Mediator associated with an active RNAPII is critical for preinitiation complex formation and CTD phosphorylation. The Mediator-RNAPII complex independently recruits TFIIB and CDK7 to core promoter regions. CDK7 phosphorylates Ser-7 selectively in the context of an intact preinitiation complex. CDK7 is not the only kinase that can modify Ser-7 of the CTD. ChIP experiments with chemical inhibitors provide evidence that other yet to be identified kinases further phosphorylate Ser-7 in coding regions.