Molecular Characterization of Rotavirus Porcine OSU Carbohydrate- Binding Domain VP8*

Characterized by susceptibility of rotavirus infectivity to sialidase treatment on host cells, the currently accepted classification scheme divides rotaviruses into two groups: 'sialidase-sensitive' and 'sialidase-insensitive'. However, the significance of sialic acids at early stage of rotavirus cell entry still remains in debate. To better understand the mechanisms mediating rotavirus cell entry and characterize the biological influence of conserved amino acids involved in rotavirus cell recognition, we have undertaken a site-directed mutagenesis study on amino acid residue 100 (Asp to Asn) of the carbohydratebinding domain VP8* of sialidase-sensitive porcine rotavirus OSU. Diffraction data of this VP8* mutant was collected to 2.35 Å and its crystallographic structure was determined by molecular replacement. Though showing a loss in the binding level compared to the wild type OSU VP8*, this Asp100Asn mutant maintains its capability of recognizing sialic acids, which implicates that this single point mutation is unable to alter the recognition phenotype of sialic acids by OSU VP8* directly.