Characterisation of cell membrane interaction mechanisms of antimicrobial peptides by electrical bilayer recording
Diana Priyadarshini1, Josip Ivica1, Frances Separovic2
1Electronics and Computer Science, Faculty of Physical & Applied Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Abstract:
Many antimicrobial peptides (AMPs) are cationic host defence peptides (HDPs) that interact with microbial membranes. This ability may lead to implementation of AMPs as therapeutics to overcome the wide-spread antibiotic resistance problem as the affected bacteria may not be able to recover from membrane lysis types of attack. AMP interactions with lipid bilayer membranes are typically explained through three mechanisms, i.e., barrel-stave pore, toroidal pore and carpet models. Electrical bilayer recording is a relatively simple and sensitive technique that is able to capture the nanoscale perturbations caused by the AMPs in the bilayer membranes. Molecular-level understanding of the behaviour of AMPs in relation to lipid bilayers mimicking bacterial and human cell membranes is essential for their development as novel therapeutic agents that are capable of targeted action against disease causing micro-organisms. The effects of four AMPs (aurein 1.2, caerin 1.1, citropin 1.1 and maculatin 1.1 from the skin secretions of Australian tree frogs) and the toxin melittin (found in the venom of honeybees) on two different phospholipid membranes were studied using the electrical bilayer recording technique. Bilayers composed of zwitterionic (DPhPC) and anionic (DPhPC/POPG) lipids were used to mimic the charge of eukaryotic and prokaryotic cell membranes, respectively, so as to determine the corresponding interaction mechanisms for different concentrations of the peptide. Analysis of the dataset corresponding to the four frog AMPs, as well as the resulting dataset corresponding to the bee toxin, confirms the proposed peptide-bilayer interaction models in existing publications and demonstrates the importance of using appropriate bilayer compositions and peptide concentrations for AMP studies.
Insights
Antimicrobial peptides (AMPs) from Australian tree frogs and bee venom were studied for their membrane interactions. Electrical bilayer recording confirmed known peptide-membrane interaction models, highlighting the importance of lipid composition and peptide concentration.
Area of Science:
- Biochemistry and Biophysics
- Antimicrobial Peptide Research
- Membrane Biophysics
Background:
- Antimicrobial peptides (AMPs), also known as cationic host defence peptides (HDPs), are crucial in combating antibiotic resistance due to their membrane-disrupting capabilities.
- Understanding AMP-lipid bilayer interactions is vital for developing targeted antimicrobial therapeutics.
- Existing models (barrel-stave, toroidal, carpet) explain AMP-membrane interactions, but require validation with diverse peptide and membrane systems.
Purpose of the Study:
- To investigate the interaction mechanisms of four Australian tree frog AMPs and the bee toxin melittin with model cell membranes.
- To validate proposed peptide-bilayer interaction models using electrical bilayer recording.
- To assess the influence of membrane charge (mimicked by zwitterionic vs. anionic lipids) and peptide concentration on AMP activity.
Main Methods:
- Utilized the electrical bilayer recording technique to monitor nanoscale perturbations in lipid bilayers.
- Employed two distinct phospholipid bilayers: zwitterionic (DPhPC) to mimic eukaryotic membranes and anionic (DPhPC/POPG) to mimic prokaryotic membranes.
- Studied the effects of varying concentrations of four frog AMPs (aurein 1.2, caerin 1.1, citropin 1.1, maculatin 1.1) and melittin.
Main Results:
- The study confirmed established peptide-bilayer interaction models for the investigated frog AMPs and melittin.
- Data analysis demonstrated that both bilayer composition (lipid charge) and peptide concentration significantly influence AMP-membrane interactions.
- Electrical bilayer recording proved effective in capturing and analyzing the nanoscale membrane perturbations induced by these peptides.
Conclusions:
- The findings validate existing models of antimicrobial peptide and lipid bilayer interactions.
- This research underscores the critical need to select appropriate lipid compositions and peptide concentrations when studying AMPs.
- The results support the potential of AMPs as therapeutic agents against antibiotic-resistant bacteria, emphasizing the importance of understanding their membrane interaction mechanisms.
Related Concept Videos
01:18Patch Clamp
In this method, a glass micropipette containing electrolyte solution is tightly sealed against a small portion of the cell membrane. As a result, a patch of the cell...
01:15Potentiometry: Membrane Electrodes
01:35Asymmetric Lipid Bilayer