Structural visualization of transcription initiation in action
Structural visualization of transcription initiation in action
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DOI：
10.1126/science.adi5120
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发表时间：
2023-12-22
期刊：
影响因子：
56.9
通讯作者：
Xu，Yanhui
中科院分区：
文献类型：
--
作者：
Chen，Xizi;Liu，Weida;Xu，Yanhui
转录起始是一个复杂的过程，其机制尚不完全清楚。我们分别测定了新生RNA长度达到2到17个核苷酸时，在无g启动子上停止RNA聚合酶II的新生转录复合物TC2到TC17的结构。将这些结构连接起来，生成了一个电影和一个工作模型。当最初合成的RNA生长时，一般转录因子（GTFs）仍然与启动子结合，转录泡扩大。三磷酸核苷（NTP）驱动的RNA-DNA易位和模板链在一个近乎封闭的通道中积累可能促进从初始转录复合物（ITCs） （TC2到TC9）到早期延伸复合物（EECs） （TC10到TC17）的转变。我们的研究揭示了转录起始的动态过程，并揭示了为什么ITCs需要GTF和泡膨胀来进行初始RNA合成，而EECs需要GTF与启动子分离和泡破裂来进行启动子逃逸。
Transcription initiation is a complex process, and its mechanism is incompletely understood. We determined the structures of de novo transcribing complexes TC2 to TC17 with RNA polymerase II halted on G-less promoters when nascent RNAs reach 2 to 17 nucleotides in length, respectively. Connecting these structures generated a movie and a working model. As initially synthesized RNA grows, general transcription factors (GTFs) remain bound to the promoter and the transcription bubble expands. Nucleoside triphosphate (NTP)–driven RNA-DNA translocation and template-strand accumulation in a nearly sealed channel may promote the transition from initially transcribing complexes (ITCs) (TC2 to TC9) to early elongation complexes (EECs) (TC10 to TC17). Our study shows dynamic processes of transcription initiation and reveals why ITCs require GTFs and bubble expansion for initial RNA synthesis, whereas EECs need GTF dissociation from the promoter and bubble collapse for promoter escape.