Refined structures of three crystal forms of toxic shock syndrome toxin- 1 and of a tetramutant with reduced activity

Abstract

The structure of toxic shock syndrome toxin-1 (TSST-1), the causative agent in toxic shock syndrome, has been determined in three crystal forms. The three structural models have been refined to R-factors of 0.154, 0.150, and 0.198 at resolutions of 2.05 Å, 2.90 Å, and 2.75 Å, respectively. One crystal form of TSST-1 contains a zinc ion bound between two symmetry- related molecules. Although not required for biological activity, zinc dramatically potentiates the mitogenicity of TSST-1H at very low concentrations. In addition, the structure of the tetramutant TSST-1H [T69I, Y80W, E132K, 1140T], which is nonmitogenic and does not amplify endotoxin shock, has been determined and refined in a fourth crystal form (R-factor = 0.173 to 1.9 Å resolution).