Related Experiment Videos
Tryptophan-rich antimicrobial peptides: comparative properties and membrane interactions
David J Schibli1, Raquel F Epand, Hans J Vogel
1Department of Biological Sciences, University of Calgary, AB, Canada.
Biochemistry and Cell Biology = Biochimie Et Biologie Cellulaire
|November 21, 2002
Summary
Cationic antimicrobial peptides rich in tryptophan (Trp) interact with cell membranes. These peptides insert into the membrane interface, with greater burial in anionic lipid bilayers, causing membrane disruption and leakage.
Area of Science:
- Biochemistry
- Biophysics
- Molecular Biology
Background:
- Cationic antimicrobial peptides (CAPs) are crucial in innate immunity.
- Tryptophan (Trp)-rich CAPs are a significant subclass with potent membrane-disrupting activities.
- Understanding their membrane interaction mechanisms is key to developing new antimicrobial strategies.
Purpose of the Study:
- To investigate the membrane interaction of Trp-rich CAPs, including tritrpticin, indolicidin, lactoferricin B (Lfcin B), and LfcinB4-9.
- To determine the location and environment of Trp residues within model membranes.
- To correlate peptide-membrane interactions with membrane disruption and leakage.
Main Methods:
- Fluorescence spectroscopy (emission wavelength, red edge effect) to probe Trp residue environment.
- Fluorescence quenching assays using acrylamide and spin-labeled phospholipids to assess peptide insertion.
- Chemical modification of Trp residues with N-bromosuccinimide.
- Liposome leakage assay using the ANTS/DPX method.
Main Results:
- Trp residues were primarily located at the membrane-water interface.
- Increased Trp burial was observed in vesicles containing anionic phosphatidylglycerol headgroups.
- Tritrpticin, showing the largest red edge shift, caused the most significant liposome leakage.
- Peptide insertion into the interfacial region correlated with membrane disruption.
Conclusions:
- Cationic Trp-rich antimicrobial peptides preferentially interact with and disrupt anionic lipid bilayers.
- The membrane interfacial region is a key site for CAP interaction.
- Peptide-induced membrane leakage is linked to their insertion depth and interaction with anionic lipids.