Complete amino acid sequence of staphylococcal enterotoxin A

Abstract

The amino acid sequence of staphylococcal enterotoxin A is presented. Staphylococcal enterotoxin A is a single-chain polypeptide which consists of 233 amino acid residues with a molecular weight of 27,078 and has the amino acid composition Cys2, Asp17, Asn19, Thr16, Ser13, Glu15, Gln12, Pro4, Gly15, Ala7, Val13, Met2, Ile10, Leu23, Tyr18, Phe8, His6, Lys24, Arg7, Trp2, with serine as both amino- and carboxyl-terminal amino acids. Automated sequence analysis of intact enterotoxin A, as well as characterization of the peptides obtained from cyanogen bromide treatment and trypsin and chymotrypsin digestion, led to the elucidation of the complete primary structure of this protein. Less structural homology is observed among staphylococcal enterotoxins A, B (Huang, I-Y., and Bergdoll, M. S. (1970) J. Biol. Chem. 245, 3518-3525), and C1 (Schmidt, J. J., and Spero, L. (1983) J. Biol. Chem. 258, 6300-6306) than that seen between enterotoxins B and C1.