Different forms of Streptolysin O produced by Streptococcus pyogenes and by Escherichia coli expressing recombinant toxin: Cleavage by streptococcal cysteine protease

Academic Article


  • To resolve apparent discrepancies in the literature, N-terminal sequences of the active high- and low-molecular-weight (high- and low-M(r)) forms of native streptolysin O (nSLO) purified from Streptococcus pyogenes culture supernatants and of the similar-size high- and low-M(r) forms of recombinant SLO (rSLO) found in the periplasm of Escherichia coli expressing a cloned slo gene were determined. The high-M(r) forms of nSLO and rSLO are identical, reflecting removal of a 31-residue signal peptide, but the similar-size low- M(r) forms are very different. Removal of C-terminal sequences by proteases in the E. coli periplasm produces an inactive low-M(r) form of rSLO. In contrast, an active low-M(r) form of nSLO is produced by proteolytic cleavage between the N-terminal residues Lys-77 and Leu-78, which was shown to correspond to an extremely sensitive cleavage site for the pyrogenic exotoxin B-derived streptococcal cysteine protease.
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    Author List

  • Pinkney M; Kapur V; Smith J; Weller U; Palmer M; Glanville M; Messner M; Musser JM; Bhakdi S; Kehoe MA
  • Start Page

  • 2776
  • End Page

  • 2779
  • Volume

  • 63
  • Issue

  • 7