NusG inhibits RNA polymerase backtracking by stabilizing the minimal transcription bubble
Abstract
Universally conserved factors from NusG family bind at the upstream fork junction of transcription elongation complexes and modulate RNA synthesis in response to translation, processing, and folding of the nascent RNA. Escherichia coli NusG enhances transcription elongation in vitro by a poorly understood mechanism. Here we report that E. coli NusG slows Gre factor-stimulated cleavage of the nascent RNA, but does not measurably change the rates of single nucleotide addition and translocation by a non-paused RNA polymerase. We demonstrate that NusG slows RNA cleavage by inhibiting backtracking. This activity is abolished by mismatches in the upstream DNA and is independent of the gate and rudder loops, but is partially dependent on the lid loop. Our comprehensive mapping of the upstream fork junction by base analogue fluorescence and nucleic acids crosslinking suggests that NusG inhibits backtracking by stabilizing the minimal transcription bubble.
Article and author information
Author details
Funding
Suomen Akatemia (grant #286205)
- Matti Turtola
- Georgiy A Belogurov
Turun Yliopisto (Graduate Student Fellowship)
- Matti Turtola
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Robert Landick, University of Wisconsin-madison, United States
Version history
- Received: May 23, 2016
- Accepted: October 3, 2016
- Accepted Manuscript published: October 4, 2016 (version 1)
- Version of Record published: November 8, 2016 (version 2)
Copyright
© 2016, Turtola & Belogurov
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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