TRANSLATIONAL PROPERTIES OF THE HUMAN PAPILLOMAVIRUS TYPE-6 L1-CODINGMESSENGER-RNA

A cDNA encoding a bicistronic mRNA, E1(AND)E4(AND)L1, which was genera ted by double-splicing of the E1, E4 and L1 genes, of the type-6 human papillomavirus (HPV-6), was cloned. The E1(AND)E4 and L1 open reading frames (ORFs) in this cDNA were expressed in COS-1 or CV-1 cells as f usion proteins with Escherichia coli beta-galactosidase (betaGal), and the products were analyzed by immunoprecipitation and enzyme assay. T he results showed that the translational efficiency of the L1 ORF was about 9-15-fold less efficient than that of the E1(AND)E4 ORF. Substit ution of the ATG of the E1(AND)E4 ORF with AAG increased translation o f the L1 ORF about 30-fold. Lengthening of the intercistronic sequence to 31 bp, equivalent in length to the bicistronic HPV-1 mRNA, showed little translational effect relative to the wild-type 12-bp intercistr onic sequence. (Carets [AND] represent splicing of RNA.)