title: Interactions of an anionic antimicrobial peptide with Staphylococcus aureus membranes.
abstract: The antimicrobial activity of the anionic peptide, AP1 (GEQGALAQFGEWL), was investigated. AP1 was found to kill Staphylococcus aureus with an MLC of 3mM and to induce maximal surface pressure changes of 3.8 mN m(-1) over 1200s in monolayers formed from lipid extract of S. aureus membranes. FTIR spectroscopy showed the peptide to be alpha-helical (100%) in the presence of vesicles formed from this lipid extract and to induce increases in their fluidity (Deltanu circa 0.5 cm(-1)). These combined data show that AP1 is able to function as an alpha-helical antimicrobial peptide against Gram-positive bacteria and suggest that the killing mechanism used by the peptide involves interactions with the membrane lipid headgroup region. Moreover, this killing mechanism differs strongly from that previously reported for AP1 against Gram-negative bacteria, indicating the importance of considering the effects of membrane lipid composition when investigating the structure/function relationships of antimicrobial peptides.
authors.affiliation: Faculty of Science, University of Central Lancashire, Preston PR1 2HE, UK.
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Dennison
authors.forename: Jörg
authors.initials: J
authors.lastname: Howe
authors.forename: Leslie H G
authors.initials: LH
authors.lastname: Morton
authors.forename: Klaus
authors.initials: K
authors.lastname: Brandenburg
authors.forename: Frederick
authors.initials: F
authors.lastname: Harris
authors.forename: David A
authors.initials: DA
authors.lastname: Phoenix
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000737:chemistry / Q000187:drug effects*; D008081:Liposomes; D008563:Membrane Lipids / Q000737:chemistry*; D010455:Peptides / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared; D013211:Staphylococcus aureus / Q000187:drug effects*
chemical_list: C513345:AP1 peptide; D000900:Anti-Bacterial Agents; D008081:Liposomes; D008563:Membrane Lipids; D010455:Peptides