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Free keywords:
DEPENDENT TRANSCRIPTION TERMINATION; ESCHERICHIA-COLI NUSA;
RNA-POLYMERASE; IN-VIVO; ALPHA-SUBUNIT; PHAGE-LAMBDA; N-PROTEIN;
ANTITERMINATION; ELONGATION; DOMAINS
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 coil NusG, suggesting that the NTD-CTD interaction of TmNusG represents an autoinhibited state.
