Transcription Initiation in a Single-Subunit RNA Polymerase Proceeds through DNA Scrunching and Rotation of the N-Terminal Subdomains

Guo Qing Tang, Rahul Roy, Taekjip Ha, Smita S. Patel

Research output: Contribution to journalArticle

Abstract

Elucidating the mechanism of transcription initiation by RNA polymerases (RNAP) is essential for understanding gene transcription and regulation. Although several models, such as DNA scrunching, RNAP translation, and RNAP rotation, have been proposed, the mechanism of initiation by T7 RNAP has remained unclear. Using ensemble and single-molecule Förster resonance energy transfer (FRET) studies, we provide evidence for concerted DNA scrunching and rotation during initiation by T7 RNAP. A constant spatial distance between the upstream and downstream edges of initiation complexes making 4-7 nt RNA supports the DNA scrunching model, but not the RNAP translation or the pure rotation model. DNA scrunching is accompanied by moderate hinging motion (18° ± 4°) of the promoter toward the downstream DNA. The observed stepwise conformational changes provide a basis to understand abortive RNA synthesis during early stages of initiation and promoter escape during the later stages that allows transition to processive elongation.

Original languageEnglish (US)
Pages (from-to)567-577
Number of pages11
JournalMolecular cell
Volume30
Issue number5
DOIs
StatePublished - Jun 5 2008
Externally publishedYes

Keywords

  • DNA
  • PROTEINS

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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