BOVINE CORONAVIRUS-I PROTEIN-SYNTHESIS FOLLOWS RIBOSOMAL SCANNING ON THE BICISTRONIC-N MESSENGER-RNA

The mRNA encoding the 49-kDa nucleocapsid protein (N) of the bovine co ronavirus is bicistronic. A 23-kDa protein, termed the I protein for t he 'internal' open reading frame (ORF), is also synthesized but in the fl reading frame beginning 61 nt downstream of the N start codon. Seq uences flanking the N and I start codons suggest that the I ORF might be accessed by scanning ribosomes passing over the N start codon. Here we test this idea and demonstrate with translation studies both in vi tro and in vivo that the I protein is synthesized according to the lea ky scanning model for initiation of translation on the subgenomic N mR NA molecule. (C) 1997 Elsevier Science B.V.