(19)F NMR reveals multiple conformations at the dimer interface of the nonstructural protein 1 effector domain from influenza A virus

Structure. 2014 Apr 8;22(4):515-525. doi: 10.1016/j.str.2014.01.010. Epub 2014 Feb 27.


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 (19)F NMR to NS1A from influenza A/Udorn/307/1972 virus (H3N2) labeled with 5-fluorotryptophan, and we demonstrate that the (19)F signal of Trp187 is a sensitive, direct monitor of the ED helix:helix dimer interface. (19)F 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. (19)F 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.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Fluorine-19 Magnetic Resonance Imaging
  • Gene Expression
  • Influenza A Virus, H3N2 Subtype / chemistry*
  • Molecular Dynamics Simulation*
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Binding
  • Protein Multimerization
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • RNA, Double-Stranded / chemistry*
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / genetics
  • Tryptophan / analogs & derivatives*
  • Tryptophan / chemistry
  • Viral Nonstructural Proteins / chemistry*
  • Viral Nonstructural Proteins / genetics


  • RNA, Double-Stranded
  • Recombinant Proteins
  • Viral Nonstructural Proteins
  • 5-fluorotryptophan
  • Tryptophan