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Published on: July 21, 2014
Structural basis for transcription activation by the nitrate-responsive regulator NarL
Dmytro Kompaniiets1, Lina He2,3, Dong Wang1
1Section of Transcription & Gene Regulation, The Hormel Institute, University of Minnesota, Austin, MN 55912, USA.
Escherichia coli NarL (a nitrate-responsive transcription factor) activates gene expression through a novel mechanism, interacting with RNA polymerase alpha CTD at the yeaR promoter. This cryo-EM structure reveals a unique transcription activation complex (TAC) assembly.
Area of Science:
- Molecular Biology
- Structural Biology
- Microbiology
Background:
- Transcription activation is vital for gene regulation in response to stimuli.
- Escherichia coli NarL is a global transcription factor controlling nearly 100 genes in response to nitrate.
- The precise molecular mechanism of NarL-mediated transcription activation remains unclear.
Purpose of the Study:
- To elucidate the structural mechanism of NarL-dependent transcription activation at the yeaR promoter.
- To provide a high-resolution structural basis for NarL's regulatory function.
Main Methods:
- Cryo-electron microscopy (cryo-EM) to determine the structure of the transcription activation complex (TAC).
- In vivo and in vitro transcription assays to validate functional roles.
Main Results:
- Determined the cryo-EM structure of the NarL-dependent TAC at 3.2 Å resolution.
- Revealed NarL dimer binding to the yeaR promoter DNA and interaction with RNA polymerase alpha CTD (αCTD).
- Demonstrated that NarL binds DNA differently than class II activators and does not interact with σ4.
Conclusions:
- The study provides a structural foundation for understanding NarL-dependent transcription activation at the yeaR promoter.
- A potentially novel mechanism of transcription activation involving NarL and RNAP αCTD is proposed.
- NarL's unique binding mode and interactions offer insights into bacterial gene regulation.
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