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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. • A crystal structure of exfoliative toxin D (ETD) was determined at 1.75 Å resolution. • A model of ETD in complex with part of human desmoglein-1 (hDsg1) was constructed. • Glu381 in hDsg1 interacted with six amino acid residues in ETD. • A space near subsite S1′ potentially binds to other parts of ETD. • The ETD loop D structure was different from those in the other exfoliative toxins. [ABSTRACT FROM AUTHOR]

[Display omitted] • Recombinant α-glucosidase rAsojAgdL is proteolytically processed in Pichia pastoris. • The structure of residues 457–560 is unique to rAsojAgdL. • Electron density for residues 496–515 is not seen in the structure of rAsojAgdL. • Residues 457–495 constitute the entrance of the catalytic pocket of rAsojAgdL. An α-glucosidase from Aspergillus sojae , AsojAgdL, exhibits strong transglucosylation activity to produce α-1,6-glucosidic linkages. The most remarkable structural feature of AsojAgdL is that residues 457–560 of AsojAgdL (designated the NC sequence) is not conserved in other glycoside hydrolase family 31 enzymes, and part of this NC sequence is proteolytically cleaved during its maturation. In this study, the enzyme was expressed in Pichia pastoris , and electrophoretic analysis indicated that the recombinant enzyme, rAsojAgdL, consisted of two polypeptide chains, as observed in the case of the enzyme produced in an Aspergillus strain. The crystal structure of rAsojAgdL was determined in complex with the substrate analog trehalose. Electron density corresponding to residues 496–515 of the NC sequence was not seen, and there were no α-helices or β-strands except for a short α-helix in the structures of residues 457–495 and residues 516–560, both of which belong to the NC sequence. The residues 457–495 and the residues 516–560 both formed extra components of the catalytic domain. The residues 457–495 constituted the entrance of the catalytic pocket of rAsojAgdL, and Gly467, Asp468, Pro469, and Pro470 in the NC sequence were located within 4 Å of Trp400, a key residue involved in binding of the substrate. The results suggest that the proteolytic processing of the NC sequence is related to the formation of the catalytic pocket of AsojAgdL. [ABSTRACT FROM AUTHOR]