N-terminal amino acid sequences of vaccinia virus structural proteins

The N-terminal amino acid sequences of vaccinia virus structural proteins were determined by direct sequencing following separation of the proteins of purified intracellular mature virus by SDS-polyacrylamide gels. By comparing the sequences obtained with the published vaccinia virus DNA sequences, specific open reading frames (ORFs) were identified. The structural proteins were encoded by the ORFs of HindIII, A3L (VP57K, 32K), A10L (VP62K, VP28K, VP22K), A12L (VP10K, VP4K), A13L (VP14K), A14L (VP17-25K), A17L (VP23-29K), A27L (VP13.8K), D8L (VP32K), H3L (VP34-37K), L4R (VP27K), G7L (VP16K), and 15L (VP13K). Four virus membrane proteins contained transmembrane signals. The N-termini of proteins indicated four types of cleavages. Ala-Gly-specific cleavage associated with products of six ORFs. Phe-specific cleavage was found in two, Met-specific in three, and Arg-specific in the product of one ORF. Ala-Gly-specific cleavage processes seven core proteins encoded by five ORFs and one membrane protein. The Met- and Arg-specific cleavages are suggested to be nonessential for virus assembly because the major portions of the target membrane proteins remain unaffected.