Nucleotide sequence of the staphylococcal enterotoxin C3 gene: sequence comparison of all three type C staphylococcal enterotoxins

Mol Gen Genet. 1990 Jan;220(2):329-33. doi: 10.1007/BF00260504.


The structural gene entC3, which encodes staphylococcal enterotoxin C3 was cloned from the genome of Staphylococcus aureus FRI-913 and sequenced. The primary amino acid sequence of the toxin was deduced from the nucleotide sequence data. entC3 contains 801 bp and encodes a precursor protein of 266 amino acids. Glutamic acid was found to be the N-terminus of mature enterotoxin C3. Thus, the first 27 residues of the toxin precursor comprise the signal peptide, and the mature toxin contains 239 amino acids with a molecular weight of 27,563 daltons. Enterotoxin C3 differs from enterotoxin C2 by four amino acids and from enterotoxin C1 by nine residues. The 167 C-terminal residues of the three toxins are identical, except for one conservative amino acid substitution in enterotoxin C3. The degree of immunological relatedness among the three Type C enterotoxins is proportional to their molecular relatedness. This study also provides evidence that the N-termini of Type C enterotoxins determine subtype-specific antigenic epitopes, while more conserved C-terminal regions determine biological properties and cross-reactive antigenic epitopes shared with other pyrogenic toxins.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Enterotoxins / genetics*
  • Genes, Bacterial*
  • Molecular Sequence Data
  • Molecular Weight
  • Protein Precursors / genetics
  • Sequence Homology, Nucleic Acid
  • Staphylococcus aureus / genetics*


  • Enterotoxins
  • Protein Precursors
  • enterotoxin C, staphylococcal