Pore formation and translocation of melittin.
Melittin, a bee venom, is a basic amphiphilic peptide, which mainly acts on the lipid matrix of membranes, lysing various cells. To elucidate the molecular mechanism, we investigated its interactions with phospholipid vesicles. The peptide formed a pore with a short lifetime in the membrane, as revealed by the release of an anionic fluorescent dye, calcein, from the liposomes. Our new double-labeling method clarified that the pore size increased with the peptide-to-lipid ratio. Upon the disintegration of the pore, a fraction of the peptides translocated across the bilayer. The pore formation was coupled with the translocation, which was proved by three fluorescence experiments recently developed by our laboratory. A novel model for the melittin pore formation was discussed in comparison with other pore-forming peptides.
Matsuzaki
K
K
Faculty of Pharmaceutical Sciences, Kyoto University, Japan. katsumim@pharm.kyoto-u.ac.jp
Yoneyama
S
S
Miyajima
K
K
D003911:Dextrans; D004227:Dithionite; D004735:Energy Transfer; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives; D005452:Fluoresceins; D005456:Fluorescent Dyes; D007700:Kinetics; D008051:Lipid Bilayers; D008081:Liposomes; D008555:Melitten / Q000737:chemistry*; D008962:Models, Theoretical; D013050:Spectrometry, Fluorescence; D013329:Structure-Activity Relationship
D003911:Dextrans; D005452:Fluoresceins; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008081:Liposomes; C015219:fluorescein isothiocyanate dextran; D004227:Dithionite; D008555:Melitten; D016650:Fluorescein-5-isothiocyanate; C007740:fluorexon