Nucleotide sequence of the staphylococcal enterotoxin C3 gene: sequence comparison of all three type C staphylococcal enterotoxins.
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.
Hovde
C J
CJ
Department of Bacteriology and Biochemistry, University of Idaho, Moscow 83843.
Hackett
S P
SP
Bohach
G A
GA
D000595:Amino Acid Sequence; D001483:Base Sequence; D004768:Enterotoxins / Q000235:genetics*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011498:Protein Precursors / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D013211:Staphylococcus aureus / Q000235:genetics*
D004768:Enterotoxins; D011498:Protein Precursors; C034959:enterotoxin C, staphylococcal