Sequence determination of the Sendai virus fusion protein gene

From a genomic DNA library of Sendai virus, we have identified and sequenced clones corresponding to the F glycoprotein gene. The limits of the F gene region were defined by mapping the 5' and 3' ends of the mRNA with S1 nuclease. The Sendai virus F gene is 1821 nucleotides long. The predicted primary translation product of the single long open reading frame would code for a protein of 565 amino acids, containing a putative signal peptide, three carbohydrate addition sites, a hydrophobic region corresponding to the known cleavage/activation site of FO, and a long, very hydrophobic region near the C-terminus which probably represents the transmembrane region of the protein. The signal peptide cleavage site of the mature protein was determined by mass spectrometry. Interestingly, the amino acid sequence surrounding the cleavage/activation site of the Sendai virus F protein shows significant homology to the same region of the influenza B and C virus HA proteins, suggesting that these genes may have evolved from a common ancestor. The ability of the Sendai virus F protein to fuse membranes relative to its primary structure is discussed.