An Autoinhibited State in the Structure of Thermotoga maritima NusG

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Drögemüller, Johanna ; Stegmann, Christian M. ; Mandal, Angshuman ; Steiner, Thomas ; Burmann, Björn M. ; Gottesman, Max E. ; Wöhrl, Birgitta M. ; Rösch, Paul ; Wahl, Markus C. ; Schweimer, Kristian:
An Autoinhibited State in the Structure of Thermotoga maritima NusG.
In: Structure. Bd. 21 (2013) Heft 3 . - S. 365-375.
ISSN 0969-2126
DOI: https://doi.org/10.1016/j.str.2012.12.015

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Abstract

NusG is a conserved regulatory protein interacting with RNA polymerase (RNAP) and other proteins to form multicomponent complexes that modulate transcription. The crystal structure of Thermotoga maritima NusG (TmNusG) shows a three-domain architecture, comprising well-conserved amino-terminal (NTD) and carboxy-terminal (CTD) domains with an additional, species-specific domain inserted into the NTD. NTD and CTD directly contact each other, occluding a surface of the NTD for binding to RNAP and a surface on the CTD interacting either with transcription termination factor Rho or transcription antitermination factor NusE. NMR spectroscopy confirmed the intramolecular NTD-CTD interaction up to the optimal growth temperature of Thermotoga maritima. The domain interaction involves a dynamic equilibrium between open and closed states and contributes significantly to the overall fold stability of the protein. Wild-type TmNusG and deletion variants could not replace endogenous Escherichia coli NusG, suggesting that the NTD-CTD interaction of TmNusG represents an autoinhibited state.