title: Site of fluorescent label modifies interaction of melittin with live cells and model membranes.
abstract: The mechanism of membrane disruption by melittin (MLT) of giant unilamellar vesicles (GUVs) and live cells was studied using fluorescence microscopy and two fluorescent synthetic analogues of MLT. The N-terminus of one of these was acylated with thiopropionic acid to enable labeling with maleimido-AlexaFluor 430 to study the interaction of MLT with live cells. It was compared with a second analogue labeled at P14C. The results indicated that the fluorescent peptides adhered to the membrane bilayer of phosphatidylcholine GUVs and inserted into the plasma membrane of HeLa cells. Fluorescence and light microscopy revealed changes in cell morphology after exposure to MLT peptides and showed bleb formation in the plasma membrane of HeLa cells. However, the membrane disruptive effect was dependent upon the location of the fluorescent label on the peptide and was greater when MLT was labeled at the N-terminus. Proline at position 14 appeared to be important for antimicrobial activity, hemolysis and cytotoxicity, but not essential for cell membrane disruption.
authors.affiliation: School of Chemistry, Bio21 Institute, The University of Melbourne, VIC 3010, Australia.
authors.forename: Elaheh
authors.initials: E
authors.lastname: Jamasbi
authors.affiliation: Department of Pathology, The University of Melbourne, VIC 3010, Australia.
authors.forename: Giuseppe D
authors.initials: GD
authors.lastname: Ciccotosto
authors.affiliation: The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, VIC 3010, Australia.
authors.forename: Julien
authors.initials: J
authors.lastname: Tailhades
authors.affiliation: Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, VIC 3010, Australia; Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, VIC 3052, Australia.
authors.forename: Roy M
authors.initials: RM
authors.lastname: Robins-Browne
authors.affiliation: Department of Biochemistry & Molecular Biology, Bio21 Institute, The University of Melbourne, VIC 3010, Australia.
authors.forename: Cathryn L
authors.initials: CL
authors.lastname: Ugalde
authors.affiliation: Department of Biochemistry & Molecular Biology, Bio21 Institute, The University of Melbourne, VIC 3010, Australia.
authors.forename: Robyn A
authors.initials: RA
authors.lastname: Sharples
authors.affiliation: School of Chemistry, Bio21 Institute, The University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, VIC 3010, Australia.
authors.forename: Nitin
authors.initials: N
authors.lastname: Patil
authors.affiliation: School of Chemistry, Bio21 Institute, The University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, VIC 3010, Australia.
authors.forename: John D
authors.initials: JD
authors.lastname: Wade
authors.affiliation: School of Chemistry, Bio21 Institute, The University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, The University of Melbourne, VIC 3010, Australia.
authors.forename: Mohammed Akhter
authors.initials: MA
authors.lastname: Hossain
authors.affiliation: School of Chemistry, Bio21 Institute, The University of Melbourne, VIC 3010, Australia.
authors.forename: Frances
authors.initials: F
authors.lastname: Separovic
mesh_terms: D005456:Fluorescent Dyes / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008051:Lipid Bilayers / Q000737:chemistry*; D008555:Melitten / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008555:Melitten
keywords: Cell membranes; Cytotoxicity; Fluorescence; Hemolysis; Melittin; Microscopy