The refined crystal structure of toxic shock syndrome toxin-1 at 2.07 angstrom resolution

The pyrogenic toxin toxic shock syndrome toxin-1 from Staphylococcus aureus is a causative agent of the toxic shock syndrome disease. It belongs to a family of proteins known as superantigens that cross-link major histocompatibility class II molecules and T-cell receptors leading to the activation of a substantial number of T cells. The crystal structure of this protein has been refined to 2.07 Angstrom with an R(cryst) value of 20.4% for 51,240 reflections. The final model contains three molecules in the asymmetric unit with good stereochemistry and a root-mean-square deviation of 0.009 Angstrom and 1.63 degrees from ideality for bond lengths and bond angles, respectively. The overall fold is considerably similar to that of other known microbial superantigens (staphylococcal enterotoxins). However, a detailed structural analysis shows that toxic shock syndrome toxin-1 lacks several structural features that affect its specificity for V beta elements of the T-cell receptor and also its recognition by major histocompatibility class II molecules. (C) 1996 Academic Press Limited