Related Experiment Video
Updated: Jun 20, 2026
Deciphering the Molecular Mechanism and Function of Pore-Forming Toxins Using Leishmania major
Published on: October 28, 2022
Cause and effect of melittin-induced pore formation: a computational approach
Moutusi Manna1, Chaitali Mukhopadhyay
1Department of Chemistry, University of Calcutta, 92, A. P. C. Road, Kolkata-700 009, India.
Abstract:
Melittin embedded in a palmitoyl oleyl phosphatidylcholine bilayer at a high peptide/lipid ratio (1:30) was simulated in the presence of explicit water and ions. The simulation results indicate the incipience of an ion-permeable water pore through collective membrane perturbation by bound peptides. The positively charged residues of melittin not only act as "anchors" but also disrupt the membrane, leading to cell lysis. A detailed analysis of the lipid tail order parameter profile depicts localized membrane perturbation. The lipids in the vicinity of the aqueous cavity adopt a tilted conformation, which allows local bilayer thinning. The prepore thus formed can be considered as the melittin-induced structural defects in the bilayer membrane. Because of the strong cationic nature, the melittin-induced prepore exhibits selectivity toward anions over cations. As Cl(-) ions entered into the prepore, they are electrostatically entrapped by positively charged residues located at its wall. The confined motion of the Cl(-) ions in the membrane interior is obvious from calculated diffusion coefficients. Moreover, reorientation of the local lipids occurs in such a way that few lipid heads along with peptide helices can line the surface of the penetrating aqueous phase. The flipping of lipids argued in favor of melittin-induced toroidal pore over a barrel-stave mechanism. Thus, our result provides atomistic level details of the mechanism of membrane disruption by antimicrobial peptide melittin.
Insights
Antimicrobial peptide melittin forms ion-permeable pores in lipid bilayers, disrupting membranes and causing cell lysis. This study reveals melittin
Area of Science:
- Biophysics
- Computational Biology
- Membrane Biophysics
Background:
- Antimicrobial peptides (AMPs) are crucial for innate immunity.
- Melittin, a primary component of bee venom, exhibits potent antimicrobial activity.
- Understanding melittin's membrane interaction mechanism is key to developing new antimicrobial strategies.
Purpose of the Study:
- To elucidate the atomistic mechanism of membrane disruption by melittin.
- To investigate the formation and properties of melittin-induced pores in lipid bilayers.
- To analyze the ion selectivity and transport within these pores.
Main Methods:
- Molecular dynamics simulations of melittin in a palmitoyl oleyl phosphatidylcholine bilayer.
- Analysis of peptide-lipid interactions, membrane perturbation, and pore formation.
- Calculation of lipid order parameters, diffusion coefficients, and ion-binding affinities.
Main Results:
- Melittin induces localized membrane perturbation, forming an ion-permeable water pore.
- The positively charged residues of melittin anchor the peptide and disrupt the bilayer, leading to cell lysis.
- The melittin-induced pore exhibits anion selectivity, trapping chloride ions.
- Lipid reorientation and flipping support a toroidal pore mechanism over a barrel-stave model.
Conclusions:
- Melittin disrupts lipid bilayers by forming toroidal pores through collective peptide action.
- The pore formation is driven by peptide anchoring, membrane perturbation, and electrostatic interactions.
- This study provides detailed atomistic insights into the membrane lytic mechanism of melittin.
Related Concept Videos
01:17Pore Transport and Ion-Pair Transport
Pore transport, also known as convective transport, is a process where small molecules like urea, water, and sugars rapidly cross cell membranes as though there were channels or pores in the membrane. Although direct microscopic evidence is limited but the concept of pores or channels is widely accepted based on physiological evidence. Despite the lack of direct microscopic...
01:21Structure of Porins