Characterization of the mutations responsible for the electrophoretic mobility differences in the NS proteins of...

Temperature-sensitive (ts) mutants of vesicular stomatitis virus, New Jersey serotype, classified in complementation group E contain lesions in the NS gene, which manifest as marked electrophoretic mobility differences of the mutant NS proteins in SDS-polyacrylamide gels. We have cloned full-length cDNA copies of the mutant NS mRNAs, and have determined their nucleotide sequences. tsE1 and tsE3 had single nucleotide changes, and tsE2 had two nucleotide changes, compared to the wild-type NS gene. Three of the mutations were clustered in a region of 18 nucleotides. All the nucleotide differences resulted in amino acid substitutions, which in each case changed the charge of the amino acid concerned. Analysis of the wild-type and mutant NS protein sequences by the method of Chou & Fasman indicated that single amino acid substitutions can radically alter the predicted secondary structure, and these data are discussed in relation to the observed electrophoretic mobility differences.