title: Interface dynamics explain assembly dependency of influenza neuraminidase catalytic activity.
abstract: Influenza virus neuraminidase (iNA) is a homotetrameric surface protein of the influenza virus and an established target for antiviral drugs. In contrast to neuraminidases (NAs) of other biological systems (non-iNAs), enzymatic activity of iNA is only observed in a quaternary assembly and iNA needs the tetramerization to mediate enzymatic activity. Obviously, differences on a molecular level between iNA and non-iNAs are responsible for this intriguing observation. Comparison between protein structures and multiple sequence alignment allow the identification of differences in amino acid composition in crucial regions of the enzyme, such as next to the conserved D151 and the 150-loop. These differences in amino acid sequence and protein tetramerization are likely to alter the dynamics of the system. Therefore, we performed molecular dynamics simulations to investigate differences in the molecular flexibility of monomers, dimers, and tetramers of iNAs of subtype N1 (avian 2004, pandemic 1918 and pandemic 2009 iNA) and as comparison the non-iNA monomer from Clostridium perfringens. We show that conformational transitions of iNA are crucially influenced by its assembly state. The protein-protein interface induces a complex hydrogen-bonding network between the 110-helix and the 150-loop, which consequently stabilizes the structural arrangement of the binding site. Therefore, we claim that these altered dynamics are responsible for the dependence of iNA's catalytic activity on the tetrameric assembly. Only the tetramerization-induced balance between stabilization and altered local flexibility in the binding site provides the appropriate arrangement of key residues for iNA's catalytic activity.
authors.affiliation: a Institute of General, Inorganic and Theoretical Chemistry and Center for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck , Innsbruck , Austria.
authors.forename: Susanne
authors.initials: S
authors.lastname: von Grafenstein
authors.forename: Hannes G
authors.initials: HG
authors.lastname: Wallnoefer
authors.forename: Johannes
authors.initials: J
authors.lastname: Kirchmair
authors.forename: Julian E
authors.initials: JE
authors.lastname: Fuchs
authors.forename: Roland G
authors.initials: RG
authors.lastname: Huber
authors.forename: Michaela
authors.initials: M
authors.lastname: Schmidtke
authors.forename: Andreas
authors.initials: A
authors.lastname: Sauerbrei
authors.forename: Judith M
authors.initials: JM
authors.lastname: Rollinger
authors.forename: Klaus R
authors.initials: KR
authors.lastname: Liedl
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D055162:Biocatalysis; D020134:Catalytic Domain; D006801:Humans; D006860:Hydrogen Bonding; D009980:Influenza A virus / Q000201:enzymology* / Q000235:genetics; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018583:Pliability; D011485:Protein Binding; D017510:Protein Folding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid; D014764:Viral Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D014764:Viral Proteins; D009439:Neuraminidase
keywords: influenza; molecular dynamics simulation; neuraminidase; oligomerization; protein assembly