title: Structure of arterivirus nsp4. The smallest chymotrypsin-like proteinase with an alpha/beta C-terminal extension and alternate conformations of the oxyanion hole.
abstract: Arteriviruses are enveloped, positive-stranded RNA viruses and include pathogens of major economic concern to the swine- and horse-breeding industries. The arterivirus replicase gene encodes two large precursor polyproteins that are processed by the viral main proteinase nonstructural protein 4 (nsp4). The three-dimensional structure of the 21-kDa nsp4 from the arterivirus prototype equine arteritis virus has been determined to 2.0 A resolution. Nsp4 adopts the smallest known chymotrypsin-like fold with a canonical catalytic triad of Ser-120, His-39, and Asp-65, as well as a novel alpha/beta C-terminal extension domain that may play a role in mediating protein-protein interactions. In different copies of nsp4 in the asymmetric unit, the oxyanion hole adopts either a collapsed inactive conformation or the standard active conformation, which may be a novel way of regulating proteolytic activity.
authors.affiliation: Canadian Institutes for Health Research Group in Protein Structure and Function, Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
authors.forename: Isabelle H
authors.initials: IH
authors.lastname: Barrette-Ng
authors.forename: Kenneth K-S
authors.initials: KK
authors.lastname: Ng
authors.forename: Brian L
authors.initials: BL
authors.lastname: Mark
authors.forename: Danny
authors.initials: D
authors.lastname: Van Aken
authors.forename: Maia M
authors.initials: MM
authors.lastname: Cherney
authors.forename: Craig
authors.initials: C
authors.lastname: Garen
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Kolodenko
authors.forename: Alexander E
authors.initials: AE
authors.lastname: Gorbalenya
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Snijder
authors.forename: Michael N G
authors.initials: MN
authors.lastname: James
mesh_terms: D000595:Amino Acid Sequence; D000838:Anions; D018018:Arterivirus / Q000201:enzymology*; D001224:Aspartic Acid / Q000737:chemistry; D001665:Binding Sites; D020134:Catalytic Domain; D002918:Chymotrypsin / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006639:Histidine / Q000737:chemistry; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry; D012697:Serine Endopeptidases / Q000737:chemistry*
chemical_list: D000838:Anions; D001224:Aspartic Acid; D012694:Serine; D006639:Histidine; D012697:Serine Endopeptidases; D002918:Chymotrypsin