title: Structural evidence for a second sialic acid binding site in avian influenza virus neuraminidases.
abstract: The x-ray structure of a complex of sialic acid (Neu5Ac) with neuraminidase N9 subtype from A/tern/Australia/G70C/75 influenza virus at 4 degrees C has revealed the location of a second Neu5Ac binding site on the surface of the enzyme. At 18 degrees C, only the enzyme active site contains bound Neu5Ac. Neu5Ac binds in the second site in the chair conformation in a similar way to which it binds to hemagglutinin. The residues that interact with Neu5Ac at this second site are mostly conserved in avian strains, but not in human and swine strains, indicating that it has some as-yet-unknown biological function in birds.
authors.affiliation: Biomolecular Research Institute, 343 Royal Parade, Parkville, 3052 Australia. jose.varghese@bioresi.com.au
authors.forename: J N
authors.initials: JN
authors.lastname: Varghese
authors.forename: P M
authors.initials: PM
authors.lastname: Colman
authors.forename: A
authors.initials: A
authors.lastname: van Donkelaar
authors.forename: T J
authors.initials: TJ
authors.lastname: Blick
authors.forename: A
authors.initials: A
authors.lastname: Sahasrabudhe
authors.forename: J L
authors.initials: JL
authors.lastname: McKimm-Breschkin
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D009980:Influenza A virus / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000378:metabolism*; D009439:Neuraminidase / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013499:Surface Properties; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism
chemical_list: D014764:Viral Proteins; D009439:Neuraminidase; D019158:N-Acetylneuraminic Acid