The 15 amino acid residues preceding the amino terminus of the envelope protein in the yellow fever virus polyprotein precursor act as a signal peptide

Abstract

The 15 amino acids which precede the sequence of the envelope (E) protein in the yellow fever virus (YFV) polyprotein precursor have been proposed to function as a signal peptide for the E protein (P. Desprès, A. Cahour, C. Wychowski, M. Girard and M. Bouloy; Ann. Inst. Pasteur/Virol., 139, 59–67, 1988). To confirm this hypothesis, recombinant SV40 genomes were constructed in which the sequence of the E protein, or that of the poliovirus VPO capsid polypeptide were placed immediately downstream of and in frame with the sequence of the putative signal peptide, under the control of the late SV40 promoter. The E protein expressed by the hybrid virus SV-E was recognized by two neutralizing monoclonal antibodies directed against the YFV envelope protein. In this construct, the E protein was deleted of its C-terminal transmembrane zone. Therefore, as expected, the protein appeared to be efficiently transported along the exocytic pathway and excreted into the cell culture medium. In addition, when the putative signal peptide was fused in frame with poliovirus polypeptide VPO, the expressed chimeric polypeptide was targeted to the endoplasmic reticulum where it underwent glycosylation.