Structural visualization of transcription initiation in action

• 成果类型: Article
• 署名作者: Chen, Xizi; Liu, Weida; Wang, Qianmin; Wang, Xinxin; Ren, Yulei; Qu, Xuechun; Li, Wanjun; Xu, Yanhui
• 署名单位: Fudan University; Fudan University; Fudan University
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-9003
• DOI: 10.1126/science.adi5120
• 发表日期: 2023-12-22
• 页码: 1377-+
• 关键词: rna-polymerase-ii; promoter escape; in-vitro; abortive initiation; preinitiation complex; trigger loop; human tfiib; dna; mechanism; distinct

摘要

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.