Crystal Structure of a Conserved Phosphatase Domain of Non-structural Protein-3 (nsp3) from the SARS Coronavirus

Severe Acute Respiratory Syndrome (SARS) is a debilitating pneumonia-like disease of the upper pulmonary tract in humans whose causative organism is a group II coronavirus (SARS-CoV). An early event in infected cells is the transcription of its genomic RNA into a large (~7000 residues) replicase polyprotein, which is then cleaved into 16 mature proteins known as non-structural proteins or nsps. Several groups have begun to characterize these proteins that form integral components of the SARS replicase/transcriptase complex. The third of these nsps, (nsp3) is a large 213kDa multidomain protein that arises due to cleavage of the polyprotein by the virally encoded papain-like protease or PLpro. It has at least six structural domains apart from a transmembrane domain.