Structural Evidence for the Evolution of Pyrogenic Toxin Superantigens

J Mol Evol. 2000 Dec;51(6):520-31. doi: 10.1007/s002390010116.


Pathogenic bacteria have evolved a wide variety of toxins to invade and attack host organisms. In particular, strains of the bacteria Staphylococcus aureus and Streptococcus pyogenes produce a family of pyrogenic toxin superantigens (PTSAgs) that can cause illness, e.g., toxic shock syndrome, or synergize with a number of other immune system disorders. The PTSAgs are all similar in size and have a conserved two-domain tertiary fold despite minimal amino acid sequence identity. The tertiary structure of PTSAg domain 1 is similar to the immunoglobulin binding motif of streptococcal proteins G and L. PTSAg domain 2 resembles members of the oligosaccharide/oligonucleotide binding fold family that includes the B subunits of the AB(5) heat-labile enterotoxins, cholera toxin, pertussis toxin, and verotoxin. The strong structural homology between the pyrogenic toxins and other bacterial proteins suggests that the PTSAgs evolved through the recombination of two smaller beta-strand motifs.

Publication types

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

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Bacterial Toxins / chemistry
  • Bacterial Toxins / genetics*
  • Enterotoxins / chemistry
  • Enterotoxins / genetics
  • Evolution, Molecular*
  • Molecular Sequence Data
  • Protein Conformation
  • Sequence Homology, Amino Acid
  • Staphylococcus aureus / genetics*
  • Staphylococcus aureus / immunology
  • Streptococcus pyogenes / genetics*
  • Streptococcus pyogenes / immunology
  • Superantigens / chemistry
  • Superantigens / genetics*


  • Bacterial Toxins
  • Enterotoxins
  • Superantigens
  • enterotoxin F, Staphylococcal