Structural analyses reveal the mechanism of inhibition of influenza virus NS1 by two antiviral compounds

J Biol Chem. 2018 Sep 21;293(38):14659-14668. doi: 10.1074/jbc.RA118.004012. Epub 2018 Aug 3.

Abstract

The influenza virus is a significant public health concern causing 250,000-500,000 deaths worldwide each year. Its ability to change quickly results in the potential for rapid generation of pandemic strains for which most individuals would have no antibody protection. This pandemic potential highlights the need for the continuous development of new drugs against influenza virus. As an essential component and well established virulence determinant, NS1 (nonstructural protein 1) of influenza virus is a highly prioritized target for the development of anti-influenza compounds. Here, we used NMR to determine that the NS1 effector domain (NS1ED) derived from the A/Brevig Mission/1/1918 (H1N1) strain of influenza (1918H1N1) binds to two previously described anti-influenza compounds A9 (JJ3297) and A22. We then used X-ray crystallography to determine the three-dimensional structure of the 1918H1N1 NS1ED Furthermore, we mapped the A9/A22-binding site onto our 1918H1N1 NS1ED structure and determined that A9 and A22 interact with the NS1ED in the hydrophobic pocket known to facilitate binding to the 30-kDa subunit of the cleavage and polyadenylation specificity factor (CPSF30), suggesting that the two compounds likely attenuate influenza replication by inhibiting the NS1ED-CPSF30 interaction. Finally, our structure revealed that NS1ED could dimerize via an interface that we termed the α3-α3 dimer. Taken together, the findings presented here provide strong evidence for the mechanism of action of two anti-influenza compounds that target NS1 and contribute significant structural insights into NS1 that we hope will promote and inform the development and optimization of influenza therapies based on A9/A22.

Keywords: 1918 H1N1; 2013 H7N9; CPSF30; NS1; antiviral agent; influenza; influenza virus; nonstructural protein 1; nuclear magnetic resonance (NMR); protein structure; viral protein; viral replication.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antiviral Agents / pharmacology*
  • Binding Sites
  • Cleavage And Polyadenylation Specificity Factor / metabolism
  • Crystallography, X-Ray
  • Dimerization
  • Drug Development
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Influenza A Virus, H1N1 Subtype / metabolism*
  • Influenza A Virus, H1N1 Subtype / physiology
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Conformation
  • Proteolysis
  • Viral Nonstructural Proteins / antagonists & inhibitors*
  • Viral Nonstructural Proteins / chemistry*
  • Viral Nonstructural Proteins / metabolism
  • Virus Replication / drug effects

Substances

  • Antiviral Agents
  • CPSF4 protein, human
  • Cleavage And Polyadenylation Specificity Factor
  • INS1 protein, influenza virus
  • Viral Nonstructural Proteins

Associated data

  • PDB/2RHK
  • PDB/3RVC
  • PDB/6DGK
  • PDB/3EE9
  • PDB/2GX9