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Staphylococcus haemolyticus prophage ΦSH2 endolysin relies on cysteine, histidine-dependent

Mathias Schmelcher1, Olga Korobova, Nina Schischkova

  • 1ANRI, Agricultural Research Service, US Department of Agriculture, 10300 Baltimore Avenue, Building 230, BARC-EAST, Beltsville, MD 20705, USA.

Journal of Biotechnology
|October 3, 2012
PubMed

Insights

Bacteriophage endolysins offer a novel antimicrobial approach against resistant Staphylococcus aureus. The ΦSH2 lysin, particularly its CHAP domain, shows significant lytic activity against MRSA and mastitis-causing strains.

Area of Science:

  • Microbiology
  • Biochemistry
  • Antimicrobial Research

Background:

  • Staphylococcus aureus, including methicillin-resistant (MRSA) strains, poses a significant threat in human and veterinary medicine.
  • Antibiotic resistance in S. aureus necessitates the development of alternative therapeutic strategies.
  • Bovine mastitis caused by S. aureus results in substantial economic losses for the dairy industry.

Purpose of the Study:

  • To characterize the lytic activity of Staphylococcus haemolyticus prophage ΦSH2 endolysin (ΦSH2 lysin).
  • To investigate the functional contribution of its catalytic (CHAP, amidase) and cell wall binding (SH3b) domains to bacterial lysis.
  • To evaluate the efficacy of ΦSH2 lysin against clinically relevant staphylococcal strains.

Main Methods:

  • Deletion constructs of ΦSH2 lysin were created to analyze domain contributions.
  • Zymogram assays and turbidity reduction assays were employed to assess lytic activity.
  • Activity was tested under various conditions, including different salt concentrations and in the presence of divalent ions.

Main Results:

  • The CHAP domain alone demonstrated three-fold higher lytic activity than the full-length ΦSH2 lysin.
  • Optimal activity for the CHAP domain was observed in physiological saline, further enhanced by calcium ions.
  • The SH3b domain was essential for the full lytic activity of the complete ΦSH2 lysin.
  • Both the full-length enzyme and the CHAP domain exhibited potent activity against diverse staphylococcal strains, including MRSA, mastitis isolates, and coagulase-negative staphylococci (CoNS).

Conclusions:

  • The CHAP domain is a potent lytic enzyme effective against various staphylococci.
  • ΦSH2 lysin represents a promising antimicrobial agent for combating resistant staphylococcal infections, including bovine mastitis.
  • Understanding domain contributions aids in the engineering of more effective phage-derived antimicrobials.

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