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The difference between MelP5 and melittin membrane poration.

Bing Zan1,2,3, Martin B Ulmschneider4, Jakob P Ulmschneider5,6

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|March 3, 2025
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Melittin peptide mutant MelP5 forms large membrane pores more effectively than natural melittin. Cholesterol significantly enhances MelP5 pore formation and stability, revealing key mechanisms for membrane permeabilization.

Keywords:
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Area of Science:

  • Biophysics
  • Molecular Biology
  • Membrane Biophysics

Background:

  • Melittin, a bee venom peptide, induces cell membrane pores.
  • Artificial mutant MelP5 exhibits significantly enhanced pore-forming activity compared to melittin.
  • The precise mechanism behind MelP5's enhanced membrane permeabilization is not fully understood.

Purpose of the Study:

  • To elucidate the mechanism by which MelP5 forms stable, macro-molecular sized pores in cell membranes.
  • To investigate the role of cholesterol in MelP5-induced membrane permeabilization.
  • To understand how peptide mutations and lipid composition influence pore formation.

Main Methods:

  • All-atom molecular dynamics (MD) simulations were employed to model peptide-membrane interactions.
  • Simulations were conducted with varying concentrations of cholesterol in the lipid bilayer.
  • Analysis focused on peptide aggregation, pore stability, and interactions with lipid tails.

Main Results:

  • MelP5 forms stable, macro-molecular sized pores, distinct from melittin's activity.
  • Mutations in MelP5 reduce electrostatic repulsion and enhance hydrophobic interactions, stabilizing the pore.
  • Cholesterol significantly promotes MelP5 pore formation, increasing pore size, stability, and formation speed.
  • Cholesterol also promotes peptide oligomerization, further stabilizing the membrane pores.

Conclusions:

  • MelP5's enhanced pore-forming ability is attributed to reduced electrostatic repulsion and increased hydrophobic interactions.
  • Cholesterol is a critical factor in MelP5-mediated membrane permeabilization, enhancing pore formation and stability.
  • These findings provide novel insights into the mechanism of action for membrane-active peptides and the influence of cholesterol.