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Updated: May 10, 2026

Isolation of Ribosome Bound Nascent Polypeptides in vitro to Identify Translational Pause Sites Along mRNA
Published on: July 6, 2012
Structural basis of transcriptional pausing in bacteria
Albert Weixlbaumer1, Katherine Leon, Robert Landick
1The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
Abstract:
Transcriptional pausing by multisubunit RNA polymerases (RNAPs) is a key mechanism for regulating gene expression in both prokaryotes and eukaryotes and is a prerequisite for transcription termination. Pausing and termination states are thought to arise through a common, elemental pause state that is inhibitory for nucleotide addition. We report three crystal structures of Thermus RNAP elemental paused elongation complexes (ePECs). The structures reveal the same relaxed, open-clamp RNAP conformation in the ePEC that may arise by failure to re-establish DNA contacts during translocation. A kinked bridge-helix sterically blocks the RNAP active site, explaining how this conformation inhibits RNAP catalytic activity. Our results provide a framework for understanding how RNA hairpin formation stabilizes the paused state and how the ePEC intermediate facilitates termination.
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