title: Structural and biochemical analysis of human pathogenic astrovirus serine protease at 2.0 A resolution.
abstract: Astroviruses are single-stranded RNA viruses with a replication strategy based on the proteolytic processing of a polyprotein precursor and subsequent release of the viral enzymes of replication. So far, the catalytic properties of the astrovirus protease as well as its structure have remained uncharacterized. In this study, the three-dimensional crystal structure of the predicted protease of human pathogenic astrovirus has been solved to 2.0 A resolution. The protein displays the typical properties of trypsin-like enzymes but also several characteristic features: (i) a catalytic Asp-His-Ser triad in which the aspartate side chain is oriented away from the histidine, being replaced by a water molecule; (ii) a non-common conformation and composition of the S1 pocket; and (iii) the lack of the typical surface beta-ribbons together with a "featureless" shape of the substrate-binding site. Hydrolytic activity assays indicate that the S1 pocket recognises Glu and Asp side chains specifically, which, therefore, are predicted to occupy the P1 position on the substrate cleavage site. The positive electrostatic potential featured by the S1 region underlies this specificity. The comparative structural analysis highlights the peculiarity of the astrovirus protease, and differentiates it from the human and viral serine proteases.
authors.affiliation: Department of Genetics and Microbiology, University of Pavia, via Ferrata 1, Pavia, 27100 Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Speroni
authors.forename: Jacques
authors.initials: J
authors.lastname: Rohayem
authors.forename: Simone
authors.initials: S
authors.lastname: Nenci
authors.forename: Daniele
authors.initials: D
authors.lastname: Bonivento
authors.forename: Ivonne
authors.initials: I
authors.lastname: Robel
authors.forename: Julia
authors.initials: J
authors.lastname: Barthel
authors.forename: Victor B
authors.initials: VB
authors.lastname: Luzhkov
authors.forename: Bruno
authors.initials: B
authors.lastname: Coutard
authors.forename: Bruno
authors.initials: B
authors.lastname: Canard
authors.forename: Andrea
authors.initials: A
authors.lastname: Mattevi
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D017931:DNA Primers / Q000235:genetics; D006801:Humans; D001257:Mamastrovirus / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D055672:Static Electricity
chemical_list: D017931:DNA Primers; D011994:Recombinant Proteins; D012697:Serine Endopeptidases