19F NMR Reveals Multiple Conformations at the Dimer Interface of the Nonstructural Protein 1 Effector Domain from Influenza A Virus
Publication date: Available online 27 February 2014
Source:Structure
Author(s): James*M. Aramini , Keith Hamilton , Li-Chung Ma , G.V.T. Swapna , Paul*G. Leonard , John*E. Ladbury , Robert*M. Krug , Gaetano*T. Montelione
Nonstructural protein 1 of influenza A virus (NS1A) is a*conserved virulence factor comprised of an N-terminal double-stranded RNA (dsRNA)-binding domain and a multifunctional C-terminal effector domain (ED), each of which can independently form symmetric homodimers. Here we apply 19F NMR to NS1A from influenza A/Udorn/307/1972 virus (H3N2) labeled with 5-fluorotryptophan, and we demonstrate that the*19F signal of Trp187 is a sensitive, direct monitor of the ED helix:helix dimer interface. 19F relaxation dispersion data reveal the presence of conformational dynamics within this functionally important protein:protein interface, whose rate is more than three orders of magnitude faster than the kinetics of ED dimerization. 19F NMR also affords direct spectroscopic evidence that Trp187, which mediates intermolecular ED:ED interactions required for cooperative dsRNA binding, is solvent exposed in full-length NS1A at concentrations below aggregation. These results have important implications for the diverse roles of this NS1A epitope during influenza virus infection.
Graphical abstract
Teaser
19F NMR is a potentially powerful approach for directly probing dynamics at protein interaction surfaces. Aramini et*al. apply 19F NMR to 5-F-Trp-labeled influenza A NS1 protein and its isolated effector domain (ED) and reveal dynamic interconversion between multiple conformations at the ED dimer interface.
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