title: A zinc binding site in viral serine proteinases.
abstract: The NS3 protein of hepatitis C virus contains a chymotrypsin-like serine proteinase domain. We built a homology model of this domain which predicts the presence of a tetradentate metal binding site formed by three cysteines and one histidine. These residues are strictly conserved in all known hepatitis C viral genotypes as well as in other recently discovered related hepatitis viruses. We show that the hepatitis C virus enzyme does indeed contain a Zn2+ ion with S3N ligation and that the metal is required for structural integrity and activity of the enzyme. Strikingly, the residues forming the metal binding site are also conserved in the chymotrypsin-like 2A cysteine proteinases of picornaviruses. Remarkably, in these highly variable viral genomes the metal binding site is more conserved than the catalytic residues and thus allows us to define a novel class of zinc binding chymotrypsin-like proteinases and to identify a new attractive target for antiviral therapy.
authors.affiliation: Istitituto di Ricerche di Biologia Molecolare (IRBM) P. Angeletti, Pomezia (Rome), Italy.
authors.forename: R
authors.initials: R
authors.lastname: De Francesco
authors.forename: A
authors.initials: A
authors.lastname: Urbani
authors.forename: M C
authors.initials: MC
authors.lastname: Nardi
authors.forename: L
authors.initials: L
authors.lastname: Tomei
authors.forename: C
authors.initials: C
authors.lastname: Steinkühler
authors.forename: A
authors.initials: A
authors.lastname: Tramontano
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics; D016174:Hepacivirus / Q000201:enzymology* / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000378:metabolism*; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases
chemical_list: D011994:Recombinant Proteins; D012697:Serine Endopeptidases; D017361:Viral Nonstructural Proteins; D015032:Zinc; C084422:NS3 protein, hepatitis C virus; D043583:Nucleoside-Triphosphatase; D053487:DEAD-box RNA Helicases; D000085242:Viral Proteases