The lipid dependence of melittin action investigated by dual-color fluorescence burst analysis.
Dual-color fluorescence-burst analysis was used to study melittin-induced leakage of macromolecules from liposomes of various lipid compositions. To perform dual-color fluorescence-burst analysis, fluorescently labeled size-marker molecules were encapsulated into liposomes, labeled with a second lipid-attached fluorophore. By correlating the fluorescence bursts, resulting from the liposomes diffusing through the detection volume of a dual-color confocal microscope, the distribution of size-marker molecules over the liposomes was determined. It was found that melittin causes leakage via two different mechanisms: 1), For liposomes composed of neutral bilayer-forming lipids, low melittin concentrations induced pore formation with the pore size depending on the melittin concentration. 2), For liposomes containing anionic and/or nonbilayer forming lipids, melittin induced fusion or aggregation of liposomes accompanied by a-specific leakage. Experiments with liposomes prepared from Escherichia coli lipid extracts and intact cells of Lactococcus lactis indicate that both mechanisms are physiologically relevant.
van den Bogaart
Geert
G
Biochemistry Department, Groningen Biomolecular Science and Biotechnology Institute & Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands.
Mika
Jacek T
JT
Krasnikov
Victor
V
Poolman
Bert
B
D002462:Cell Membrane / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008555:Melitten / Q000737:chemistry*; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods; D008954:Models, Biological; D008956:Models, Chemical; D008958:Models, Molecular; D010743:Phospholipids / Q000737:chemistry*; D016062:Porosity
D008051:Lipid Bilayers; D010743:Phospholipids; D008555:Melitten