A structural and functional comparison of staphylococcal enterotoxins A and C2 reveals remarkable similarity and dissimilarity.
Staphylococcal enterotoxins and toxic shock syndrome toxin-1 are known as superantigens due to their ability to activate a large number of T-cells by crosslinking the major histocompatibility complex class II molecules with the T-cell receptor. Although superantigens seem to act by a common mechanism, they vary in many of their specific interactions and biological properties. A structural comparison of staphylococcal enterotoxins A and C2, members of the staphylococcal superantigens, has shown large conformational differences at the putative TcR interaction site (loops between alphaN-alpha2, alpha4-beta9 and beta10-alpha5 in staphylococcal enterotoxin A) that could explain the variability in their T-cell receptor specificity. A common Zn2(+)-binding site was identified in both staphylococcal enterotoxin A and C2 that is superimposable but differs somewhat in its coordination geometry between the two molecules.
Schad
E M
EM
Department of Molecular Biophysics, Center for Chemistry and Chemical Engineering, Lund University, Sweden.
Papageorgiou
A C
AC
Svensson
L A
LA
Acharya
K R
KR
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000737:chemistry*; D001665:Binding Sites; D004768:Enterotoxins / Q000737:chemistry* / Q000276:immunology; D015798:HLA-DR1 Antigen / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D016415:Sequence Alignment / Q000379:methods; D017386:Sequence Homology, Amino Acid; D018089:Superantigens / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
D000942:Antigens, Bacterial; D004768:Enterotoxins; D015798:HLA-DR1 Antigen; D011948:Receptors, Antigen, T-Cell; D018089:Superantigens; C026066:enterotoxin A, Staphylococcal; C034959:enterotoxin C, staphylococcal; D015032:Zinc