• Synthesis of trypsin-resistant variants of the Listeria-active bacteriocin salivaricin P

      O'Shea, Eileen F.; O'Connor, Paula M.; Cotter, Paul D.; Ross, R Paul; Hill, Colin; Department of Agriculture, Food and the Marine, Ireland; Science Foundation Ireland; Teagasc Walsh Fellowship Programme (American Society for Microbiology, 25/06/2010)
      Two-component Salivaricin P-like bacteriocins have demonstrated potential as antimicrobials capable of controlling infections in the gastrointestinal tract (GIT). The anti-Listeria activity of salivaricin P is optimal when the individual peptides, Sln1 and Sln2, are added in succession in a 1:1 ratio. However, as degradation by digestive proteases may compromise the functionality of these peptides within the GIT we investigated the potential to create salivaricin variants with enhanced resistance to the intestinal protease, trypsin. A total of 11 variants of the salivaricin P components were generated in which conservative modifications at the trypsin-specific cleavage sites were explored in order to protect the peptides from trypsin degradation while maintaining their potent antimicrobial activity. Analysis of these variants revealed that eight were resistant to trypsin digestion while retaining antimicrobial activity. Combining the complementary trypsin resistant variants Sln1-5 and Sln2-3 resulted in a MIC50 of 300 nM against Listeria monocytogenes, a 3.75-fold reduction in activity compared to wild-type salivaricin P. This study demonstrates the potential of engineering bacteriocins variants which are resistant to specific protease action but which retain significant antimicrobial activity.