IDENTIFICATION OF AN ATPASE ACTIVITY ASSOCIATED WITH A 71-KILODALTON POLYPEPTIDE ENCODED IN GENE-1 OF THE HUMAN CORONAVIRUS 229E

Human coronavirus 229E gene expression involves proteolytic processing of the gene I-encoded polyproteins pp1a and pp1ab. In this study, we have detected a 71-kDa polypeptide in virus-infected cells that is rel eased from pp1ab by the virus-encoded 3C-like proteinase and that has been predicted to contain both metal-binding and helicase domains. The polypeptide encompasses amino acids Ala-4996 to Gln-5592 of pp1ab and exhibits nucleic acid-stimulated ATPase activity when expressed as a fusion protein with the Escherichia coli maltose-binding protein. Thes e data provide the first identification of a coronavirus open reading frame 1b-encoded enzymatic activity.