title: Two Distinctive Binding Modes of Endonuclease Inhibitors to the N-Terminal Region of Influenza Virus Polymerase Acidic Subunit.
abstract: Influenza viruses are global threat to humans, and the development of new antiviral agents are still demanded to prepare for pandemics and to overcome the emerging resistance to the current drugs. Influenza polymerase acidic protein N-terminal domain (PAN) has endonuclease activity and is one of the appropriate targets for novel antiviral agents. First, we performed X-ray cocrystal analysis on the complex structures of PAN with two endonuclease inhibitors. The protein crystallization and the inhibitor soaking were done at pH 5.8. The binding modes of the two inhibitors were different from a common binding mode previously reported for the other influenza virus endonuclease inhibitors. We additionally clarified the complex structures of PAN with the same two endonuclease inhibitors at pH 7.0. In one of the crystal structures, an additional inhibitor molecule, which chelated to the two metal ions in the active site, was observed. On the basis of the crystal structures at pH 7.0, we carried out 100 ns molecular dynamics (MD) simulations for both of the complexes. The analysis of simulation results suggested that the binding mode of each inhibitor to PAN was stable in spite of the partial deviation of the simulation structure from the crystal one. Furthermore, crystal structure analysis and MD simulation were performed for PAN in complex with an inhibitor, which was already reported to have a high compound potency for comparison. The findings on the presence of multiple binding sites at around the PAN substrate-binding pocket will provide a hint for enhancing the binding affinity of inhibitors.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University , 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fudo
authors.affiliation: Graduate School of Medicine, Juntendo University , 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.|Influenza Virus Research Center, National Institute of Infectious Diseases , 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
authors.forename: Norio
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Faculty of Pharmaceutical Sciences, Josai International University , 1 Gumyo, Togane-shi Chiba 283-8555, Japan.
authors.forename: Michiyoshi
authors.initials: M
authors.lastname: Nukaga
authors.affiliation: Influenza Virus Research Center, National Institute of Infectious Diseases , 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
authors.forename: Takato
authors.initials: T
authors.lastname: Odagiri
authors.affiliation: Influenza Virus Research Center, National Institute of Infectious Diseases , 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Tashiro
authors.affiliation: Graduate School of Pharmaceutical Sciences, Chiba University , 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan.
authors.forename: Tyuji
authors.initials: T
authors.lastname: Hoshino
mesh_terms: D000998:Antiviral Agents / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry*; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics*; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D000072417:Protein Domains; D014764:Viral Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry*
chemical_list: D000998:Antiviral Agents; D004791:Enzyme Inhibitors; D014764:Viral Proteins