TY - JOUR
T1 - Investigating the lytic activity and structural properties of Staphylococcus aureus phenol soluble modulin (PSM) peptide toxins
AU - Laabei, Maisem
AU - Jamieson, W. David
AU - Yang, Yi
AU - Van Den Elsen, Jean
AU - Jenkins, A. Toby A.
PY - 2014/12/1
Y1 - 2014/12/1
N2 - The ubiquitous bacterial pathogen, Staphylococcus aureus, expresses a large arsenal of virulence factors essential for pathogenesis. The phenol-soluble modulins (PSMs) are a family of cytolytic peptide toxins which have multiple roles in staphylococcal virulence. To gain an insight into which specific factors are important in PSM-mediated cell membrane disruption, the lytic activity of individual PSM peptides against phospholipid vesicles and T cells was investigated. Vesicles were most susceptible to lysis by the PSMα subclass of peptides (α1–3 in particular), when containing between 10 and 30 mol% cholesterol, which for these vesicles is the mixed solid ordered (so)–liquid ordered (lo) phase. Our results show that the PSMβ class of peptides has little effect on vesicles at concentrations comparable to that of the PSMα class and exhibited no cytotoxicity. Furthermore, within the PSMα class, differences emerged with PSMα4 showing decreased vesicle and cytotoxic activity in comparison to its counterparts, in contrast to previous studies. In order to understand this, peptides were studied using helical wheel projections and circular dichroism measurements. The degree of amphipathicity, alpha-helicity and properties such as charge and hydrophobicity were calculated, allowing a structure–function relationship to be inferred. The degree of alpha-helicity of the peptides was the single most important property of the seven peptides studied in predicting their lytic activity. These results help to redefine this class of peptide toxins and also highlight certain membrane parameters required for efficient lysis.
AB - The ubiquitous bacterial pathogen, Staphylococcus aureus, expresses a large arsenal of virulence factors essential for pathogenesis. The phenol-soluble modulins (PSMs) are a family of cytolytic peptide toxins which have multiple roles in staphylococcal virulence. To gain an insight into which specific factors are important in PSM-mediated cell membrane disruption, the lytic activity of individual PSM peptides against phospholipid vesicles and T cells was investigated. Vesicles were most susceptible to lysis by the PSMα subclass of peptides (α1–3 in particular), when containing between 10 and 30 mol% cholesterol, which for these vesicles is the mixed solid ordered (so)–liquid ordered (lo) phase. Our results show that the PSMβ class of peptides has little effect on vesicles at concentrations comparable to that of the PSMα class and exhibited no cytotoxicity. Furthermore, within the PSMα class, differences emerged with PSMα4 showing decreased vesicle and cytotoxic activity in comparison to its counterparts, in contrast to previous studies. In order to understand this, peptides were studied using helical wheel projections and circular dichroism measurements. The degree of amphipathicity, alpha-helicity and properties such as charge and hydrophobicity were calculated, allowing a structure–function relationship to be inferred. The degree of alpha-helicity of the peptides was the single most important property of the seven peptides studied in predicting their lytic activity. These results help to redefine this class of peptide toxins and also highlight certain membrane parameters required for efficient lysis.
U2 - 10.1016/j.bbamem.2014.08.026
DO - 10.1016/j.bbamem.2014.08.026
M3 - Article
SN - 0005-2736
VL - 1838
SP - 3153
EP - 3161
JO - Biochimica Et Biophysica Acta-Biomembranes
JF - Biochimica Et Biophysica Acta-Biomembranes
IS - 12
ER -