title: Phospholipid dependent mechanism of smp24, an α-helical antimicrobial peptide from scorpion venom.
abstract: Determining the mechanism of action of antimicrobial peptides (AMPs) is critical if they are to be developed into the clinical setting. In recent years high resolution techniques such as atomic force microscopy (AFM) have increasingly been utilised to determine AMP mechanism of action on planar lipid bilayers and live bacteria. Here we present the biophysical characterisation of a prototypical AMP from the venom of the North African scorpion Scorpio maurus palmatus termed Smp24. Smp24 is an amphipathic helical peptide containing 24 residues with a charge of +3 and exhibits both antimicrobial and cytotoxic activity and we aim to elucidate the mechanism of action of this peptide on both membrane systems. Using AFM, quartz crystal microbalance-dissipation (QCM-D) and liposomal leakage assays the effect of Smp24 on prototypical synthetic prokaryotic (DOPG:DOPC) and eukaryotic (DOPE:DOPC) membranes has been determined. Our data points to a toroidal pore mechanism against the prokaryotic like membrane whilst the formation of hexagonal phase non-lamellar phase structures is seen in eukaryotic like membrane. Also, phase segregation is observed against the eukaryotic membrane and this study provides direct evidence of the same peptide having multiple mechanisms of action depending on the membrane lipid composition.
authors.affiliation: Biomolecular Research Centre, Sheffield Hallam University, Sheffield, UK.
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Harrison
authors.affiliation: Department of Physics and Astronomy, Leeds University, Leeds, UK.
authors.forename: George R
authors.initials: GR
authors.lastname: Heath
authors.affiliation: Department of Physics and Astronomy, Leeds University, Leeds, UK.
authors.forename: Benjamin R G
authors.initials: BRG
authors.lastname: Johnson
authors.affiliation: Biomolecular Research Centre, Sheffield Hallam University, Sheffield, UK; Zoology Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Abdel-Rahman
authors.affiliation: Biomolecular Research Centre, Sheffield Hallam University, Sheffield, UK.
authors.forename: Peter N
authors.initials: PN
authors.lastname: Strong
authors.affiliation: Department of Physics and Astronomy, Leeds University, Leeds, UK.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Evans
authors.affiliation: Biomolecular Research Centre, Sheffield Hallam University, Sheffield, UK. Electronic address: K.miller@shu.ac.uk.
authors.forename: Keith
authors.initials: K
authors.lastname: Miller
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000494:pharmacology*; D008051:Lipid Bilayers / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D018716:Molecular Mimicry; D010713:Phosphatidylcholines / Q000737:chemistry; D010714:Phosphatidylethanolamines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D000072756:Protein Conformation, alpha-Helical; D012604:Scorpion Venoms / Q000138:chemical synthesis / Q000494:pharmacology*; D012605:Scorpions / Q000737:chemistry; D055672:Static Electricity
chemical_list: D023181:Antimicrobial Cationic Peptides; D008051:Lipid Bilayers; D008081:Liposomes; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D012604:Scorpion Venoms; C094877:dioleoyl phosphatidylethanolamine; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; C017251:1,2-oleoylphosphatidylcholine
keywords: Antimicrobial peptides; Atomic force microscopy; Membrane damage; Quartz crystal microbalance-dissipation