Structure-function and pathogenesis studies of streptococcus pyogenes extracellular cysteine protease

Replacement of the single cysteine residue (C192) with serine in the Streptococcus pyogenes extracellular cysteine protease (SCP) prevented auto- catalytic processing of the 40-kDa zymogen to the 28-kDa mature form and eliminated proteolytic activity. SCP incubated with human endothelial cells induced a time- and concentration-dependent increase in a 66-kDa gelatinase/type IV collagenase in culture supernatants. Activation of this gelatinase/collagenase may contribute to endothelial cell damage, tissue destruction, and hemodynamic derangement observed in some patients with severe, invasive S. pyogenes infection.