Staphylolysin

This chapter describes the structural chemistry and the biological aspects of staphylolysin. Staphylolysin cleaves peptide bonds within the pentaglycine cross-linking peptides of S. aureus peptidoglycan and leads to cell lysis. It also lyses cell walls of Micrococcus radiodurans and Gaffkia tetragena, which contain di- and triglycine sequences in their interpeptides, respectively. Synthetic penta- and hexaglycine are cleaved into di- and tri- or triglycine, respectively. Oligopeptides containing internal Gly-Gly or Gly-Gly-Gly sequences are also cleaved, but the cleavage sites in these substrates are not defined. Staphylolysin has been purified from culture filtrates of several P. aeruginosa strains with purification factors ranging from 140 to 520. Purified staphylolysin preparations often contain another protease(s) that is undetectable in SDS gels, but its presence is responsible for a β-casein hydrolytic activity. Biologically and clinically relevant substrates of staphylolysin include S. aureus cells and elastin. The enzyme also enhances syndecan-1 shedding from epithelial cell surfaces. A lasA deletion derivative of P. aeruginosa shows no detectable staphylolytic activity under standard assay conditions.