Cationic antimicrobial peptides disrupt the Streptococcus pyogenes ExPortal
Article first published online: 26 JUL 2012
© 2012 Blackwell Publishing Ltd
Volume 85, Issue 6, pages 1119–1132, September 2012
How to Cite
Vega, L. A. and Caparon, M. G. (2012), Cationic antimicrobial peptides disrupt the Streptococcus pyogenes ExPortal. Molecular Microbiology, 85: 1119–1132. doi: 10.1111/j.1365-2958.2012.08163.x
- Issue published online: 10 SEP 2012
- Article first published online: 26 JUL 2012
- Accepted manuscript online: 11 JUL 2012 04:56AM EST
- Accepted 30 June, 2012.
Although they possess a well-characterized ability to porate the bacterial membrane, emerging research suggests that cationic antimicrobial peptides (CAPs) can influence pathogen behaviour at levels that are sublethal. In this study, we investigated the interaction of polymyxin B and human neutrophil peptide (HNP-1) with the human pathogen Streptococcus pyogenes. At sublethal concentrations, these CAPs preferentially targeted the ExPortal, a unique microdomain of the S. pyogenes membrane, specialized for protein secretion and processing. A consequence of this interaction was the disruption of ExPortal organization and a redistribution of ExPortal components into the peripheral membrane. Redistribution was associated with inhibition of secretion of certain toxins, including the SpeB cysteine protease and the streptolysin O (SLO) cytolysin, but not SIC, a protein that protects S. pyogenes from CAPs. These data suggest a novel function for CAPs in targeting the ExPortal and interfering with secretion of factors required for infection and survival. This mechanism may prove valuable for the design of new types of antimicrobial agents to combat the emergence of antibiotic-resistant pathogens.