PSM-Mec-A Virulence Determinant that Connects Transcriptional Regulation, Virulence, and Antibiotic Resistance in Staphylococci

Front Microbiol. 2016 Aug 22:7:1293. doi: 10.3389/fmicb.2016.01293. eCollection 2016.

Abstract

PSM-mec is a secreted virulence factor that belongs to the phenol-soluble modulin (PSM) family of amphipathic, alpha-helical peptide toxins produced by Staphylococcus species. All known PSMs are core genome-encoded with the exception of PSM-mec, whose gene is found in specific sub-types of SCCmec methicillin resistance mobile genetic elements present in methicillin-resistant Staphylococcus aureus and coagulase-negative staphylococci. In addition to the cytolytic translational product, PSM-mec, the psm-mec locus encodes a regulatory RNA. In S. aureus, the psm-mec locus influences cytolytic capacity, methicillin resistance, biofilm formation, cell spreading, and the expression of other virulence factors, such as other PSMs, which results in a significant impact on immune evasion and disease. However, these effects are highly strain-dependent, which is possibly due to differences in PSM-mec peptide vs. psm-mec RNA-controlled effects. Here, we summarize the functional properties of PSM-mec and the psm-mec RNA molecule and their roles in staphylococcal pathogenesis and physiology.

Keywords: PSM-mec; SCCmec; Staphylococcus aureus; Staphylococcus epidermidis; phenol-soluble modulin; regulatory RNA; virulence.

Publication types

  • Review