Collective dynamics in lipid membranes containing transmembrane peptides
Elizabeth G Kelley1, Paul D Butler2, Michihiro Nagao3
1NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, USA. egk@nist.gov.
Soft Matter
|May 4, 2021
Summary
Antimicrobial peptides significantly alter lipid membrane dynamics, affecting bending and thickness fluctuations. Gramicidin stiffens membranes, while alamethicin softens them, revealing peptide-specific effects on bilayer properties.
Area of Science:
- Biophysics
- Membrane Biophysics
- Soft Matter Physics
Background:
- Biological membranes comprise lipids and proteins influencing function.
- Channel-forming proteins' activity depends on lipid bilayer properties.
- Less is known about how channels impact lipid bilayer dynamics.
Purpose of the Study:
- Investigate how membrane-spanning channels affect lipid bilayer fluctuation dynamics.
- Quantify changes in collective bending and thickness fluctuations induced by peptides.
- Understand the interplay between antimicrobial peptides and lipid bilayer properties.
Main Methods:
- Neutron spin echo spectroscopy (NSE) used to measure dynamics.
- Studied dimyristoylphosphatidylcholine (DMPC) lipid membranes.
- Incorporated alamethicin (Ala) and gramicidin (gD) antimicrobial peptides.
Main Results:
- Peptides altered collective membrane dynamics without changing average bilayer structure.
- Gramicidin (gD) addition stiffened the membrane, while alamethicin (Ala) softened it.
- Low gD enhanced thickness fluctuations; higher gD and all Ala dampened them.
Conclusions:
- Lipid and protein synergy dictates collective membrane dynamics.
- Antimicrobial peptides have distinct, non-universal effects on lipid bilayer fluctuations.
- Peptides should not be treated as rigid bodies when assessing bilayer dynamics.
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