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Updated: Nov 16, 2025
Measuring Peptide Translocation into Large Unilamellar Vesicles
Published on: January 27, 2012
Tylopeptin B peptide antibiotic in lipid membranes at low concentrations: Self-assembling, mutual repulsion and
Victoria N Syryamina1, Natalia E Sannikova2, Marta De Zotti3
1Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation.
Abstract:
The medium-length peptide Tylopeptin B possesses activity against Gram-positive bacteria. It binds to bacterial membranes altering their mechanical properties and increasing their permeability. This action is commonly related with peptide self-assembling, resulting in the formation of membrane channels. Here, pulsed double electron-electron resonance (DEER) data for spin-labeled Tylopeptin B in palmitoyl-oleoyl-glycero-phosphocholine (POPC) model membrane reveal that peptide self-assembling starts at concentration as low as 0.1 mol%; above 0.2 mol% it attains a saturation-like dependence with a mean number of peptides in the cluster
Insights
Tylopeptin B peptide aggregates in bacterial membranes at low concentrations, altering membrane properties to exert antimicrobial activity. This peptide self-assembly and membrane destabilization mechanism is crucial for its effectiveness against Gram-positive bacteria.
Area of Science:
- Biophysics
- Membrane Biophysics
- Antimicrobial Peptides
Background:
- Tylopeptin B is a medium-length peptide with demonstrated activity against Gram-positive bacteria.
- Its mechanism involves binding to bacterial membranes, altering mechanical properties and increasing permeability, often through self-assembly into membrane channels.
Purpose of the Study:
- To investigate the self-assembly behavior and membrane interaction of Tylopeptin B using biophysical techniques.
- To elucidate the relationship between peptide concentration, aggregation, and antimicrobial activity.
Main Methods:
- Pulsed double electron-electron resonance (DEER) on spin-labeled Tylopeptin B in palmitoyl-oleoyl-glycero-phosphocholine (POPC) model membranes.
- Electron spin echo envelope modulation (ESEEM) technique.
- Utilized spin-labeled stearic acids to model free fatty acid (FFA) behavior.
Main Results:
- Peptide self-assembly initiates at 0.1 mol% Tylopeptin B, reaching saturation around 0.2 mol% with an average cluster size of 3.3 peptides.
- Tylopeptin B molecules adopt a planar orientation within the membrane.
- At 0.1-0.2 mol%, peptide clusters exhibit mutual repulsion (20 nm exclusion radius), potentially destabilizing the membrane.
- The peptide promotes lipid-mediated FFA clusters at 0.1-0.2 mol%, which dissipate at higher peptide concentrations.
Conclusions:
- Tylopeptin B self-assembles in model membranes, with aggregation dynamics dependent on concentration.
- The planar orientation and repulsive interactions between peptide clusters contribute to membrane destabilization and antimicrobial action.
- The peptide modulates free fatty acid clustering within the membrane, a process linked to its overall mechanism of action.
