SpeB is a bacterial determinant for cleavage of desmogleins. (A) Culture supernatant from S. pyogenes strain 591 was pretreated with various types of protease inhibitors at room temperature for 30 min, then incubated with <t>Dsg1</t> or Dsg3 recombinant protein at 37°C for 3 h. (B) Recombinant desmogleins were separately treated with culture supernatants from S. pyogenes strains at 37°C for 3 h. An in-frame speB deletion mutant and its revertant strain with a background of NIH35 or 591 were employed for analysis. (C) Dsg1 and Dsg3 recombinant proteins were separately incubated with various concentrations of recombinant SpeB at 37°C for 3 h, then cleavage of desmogleins was detected by western blot analysis. White and black arrowheads indicate the full-length band and cleavage fragment, respectively.
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