Crystal structure of exfoliative toxin D from Staphylococcus aureus.

Staphylococcus aureus exfoliative toxins (ETs) are serine proteases responsible for staphylococcal scalded skin syndrome. Four ETs, ETA, ETB, ETD, and ETE, have been identified, all of which cleave desmoglein-1. This study presents the crystal structure of ETD at 1.75 Å resolution. The protein exhibits a structure composed of two β-barrels and two α-helices as described in previous studies of ETs. A predicted model of ETD in complex with Ile380-Glu381-Gly382-Pro383 (IEGP), a segment of human desmoglein-1 (hDsg1), was constructed. Glu381 of hDsg1 was predicted to interact with as many as six amino acid residues in ETD, whereas two amino acid residues in ETD primarily constituted subsite S1', and a space near subsite S1' was noted. It is likely that polypeptide chains located near the IEGP segment in the predicted structure of hDsg1 bind to this space. The structure of loop D, which was predicted to participate in subsite S2', in ETD was markedly different from those in other ETs.