title: Structure-based identification of an inducer of the low-pH conformational change in the influenza virus hemagglutinin: irreversible inhibition of infectivity.
abstract: Past efforts to employ a structure-based approach to design an inhibitor of the fusion-inducing conformational change in the influenza virus hemagglutinin (HA) yielded a family of small benzoquinones and hydroquinones. The most potent of these, tert-butyl hydroquinone (TBHQ), inhibits both the conformational change in HA from strain X:31 influenza virus and viral infectivity in tissue culture cells with 50% inhibitory concentrations in the micromolar range (D. L. Bodian, R. B. Yamasaki, R. L. Buswell, J. F. Stearns, J. M. White, and I. D. Kuntz, Biochemistry 32:2967-2978, 1993). A new structure-based inhibitor design search was begun which involved (i) the recently refined crystal structure (2.1-A resolution) of the HA ectodomain, (ii) new insights into the conformational change, and (iii) improvements in the molecular docking program, DOCK. As a result, we identified new inhibitors of HA-mediated membrane fusion. Like TBHQ, most of these molecules inhibit the conformational change. One of the new compounds, however, facilitates rather than inhibits the HA conformational change. Nonetheless, the facilitator, diiodofluorescein, inhibits HA-mediated membrane fusion and, irreversibly, infectivity. We further characterized the effects of inhibitors from both searches on the conformational change and membrane fusion activity of HA as well as on viral infectivity. We also isolated and characterized several mutants resistant to each class of inhibitor. The implications of our results for HA-mediated membrane fusion, anti-influenza virus therapy, and structure-based inhibitor design are discussed.
authors.affiliation: Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448, USA.
authors.forename: L R
authors.initials: LR
authors.lastname: Hoffman
authors.forename: I D
authors.initials: ID
authors.lastname: Kuntz
authors.forename: J M
authors.initials: JM
authors.lastname: White
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology*; D001665:Binding Sites; D001963:Bromelains; D002460:Cell Line; D015195:Drug Design; D005452:Fluoresceins / Q000494:pharmacology*; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000648:ultrastructure*; D006461:Hemolysis / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D006873:Hydroquinones / Q000494:pharmacology; D008024:Ligands; D008561:Membrane Fusion; D008958:Models, Molecular; D009975:Orthomyxoviridae / Q000254:growth & development / Q000648:ultrastructure*; D010446:Peptide Fragments; D011487:Protein Conformation / Q000187:drug effects*; D013329:Structure-Activity Relationship
chemical_list: C108722:2-(3-hydroxy-4,5-diiodo-6H-6-oxoxanthen-9-yl)benzoic acid; D000998:Antiviral Agents; D005452:Fluoresceins; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D006873:Hydroquinones; D008024:Ligands; D010446:Peptide Fragments; D001963:Bromelains; C018855:2-tert-butylhydroquinone