PMID: 23374340
Authors:
Weixlbaumer A, Leon K, Landick R, Darst SA
Title:
Structural basis of transcriptional pausing in bacteria.
Journal:
Cell. 2013 Jan 31;152(3):431-41. doi: 10.1016/j.cell.2012.12.020.
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.