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'Detergent-like' permeabilization of anionic lipid vesicles by melittin

A S Ladokhin1, S H White

  • 1Department of Physiology and Biophysics, University of California, 364-D Medical Sciences 1, Irvine, CA 92697-4560, USA. ladokhin@uci.edu

Biochimica Et Biophysica Acta
|September 15, 2001
PubMed

Insights

Melittin (MLT) permeabilizes membranes differently based on lipid type. Anionic lipids inhibit MLT

Area of Science:

  • Biochemistry and Biophysics
  • Membrane Biology
  • Peptide-lipid interactions

Background:

  • Melittin (MLT), a peptide from honeybees, is a model for studying membrane permeabilization.
  • MLT's ability to permeabilize membranes is significantly reduced by anionic lipids.
  • Understanding MLT's interaction with different lipid types is crucial for host-defense peptide research.

Purpose of the Study:

  • To investigate the mechanism of melittin-induced membrane permeabilization in anionic vesicles.
  • To compare MLT's interaction with anionic (POPG) and zwitterionic (POPC) lipid bilayers.
  • To determine the structural basis for MLT's altered membrane activity in the presence of anionic lipids.

Main Methods:

  • Assessed MLT-induced release of fluorescent dextran markers (4 and 50 kDa) from POPG vesicles.
  • Compared release profiles from POPG vesicles with previously established data from POPC vesicles.
  • Utilized oriented circular dichroism to study MLT's secondary structure and orientation within POPG and POPC multilayers.

Main Results:

  • MLT-induced release from POPG vesicles was non-selective ('detergent-like'), unlike the selective release from POPC vesicles.
  • Alpha-helical MLT adopted a transbilayer orientation in POPC multilayers but not in POPG multilayers.
  • Anionic lipids appear to suppress MLT's ability to translocate across the membrane bilayer.

Conclusions:

  • The mechanism of melittin permeabilization differs significantly between zwitterionic and anionic lipid membranes.
  • Anionic lipids inhibit MLT permeabilization by preventing its translocation through the membrane.
  • Findings provide insight into the role of lipid charge in modulating antimicrobial peptide membrane interactions.

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