期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 117, 期 11, 页码 5801-5809出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1920747117
关键词
transcription initiation; initial transcription; promoter escape; sigma factor; initiation factor
资金
- Chinese Academy of Sciences (CAS) Strategic Priority Research Program [XDB29020000]
- National Natural Science Foundation of China [31670067, 31822001]
- CAS Leading Science Key Research Program [QYZDB-SSWSMC005]
- NIH [GM041376]
All organisms-bacteria, archaea, and eukaryotes-have a transcription initiation factor that contains a structural module that binds within the RNA polymerase (RNAP) active-center cleft and interacts with template-strand single-stranded DNA (ssDNA) in the immediate vicinity of the RNAP active center. This transcription initiation-factor structural module preorganizes template-strand ssDNA to engage the RNAP active center, thereby facilitating binding of initiating nucleotides and enabling transcription initiation from initiating mononucleotides. However, this transcription initiation-factor structural module occupies the path of nascent RNA and thus presumably must be displaced before or during initial transcription. Here, we report four sets of crystal structures of bacterial initially transcribing complexes that demonstrate and define details of stepwise, RNA-extension-driven displacement of the s-finger of the bacterial transcription initiation factor sigma. The structures reveal that-for both the primary sigma-factor and extracytoplasmic (ECF) sigma-factors, and for both 5'-triphosphate RNA and 5'-hydroxy RNA-the sigma-finger is displaced in stepwise fashion, progressively folding back upon itself, driven by collision with the RNA 5'-end, upon extension of nascent RNA from similar to 5 nt to similar to 10 nt.
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