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Impact of Antimicrobial Peptides on E.coli-mimicking Lipid Model Membranes: correlating structural and dynamic effects using scattering methods

Abstract

The mechanism of action of antimicrobial peptides (AMPs) has been debated over many years, and various models have been proposed. In this work we combine small angle X-ray/neutron scattering (SAXS/SANS) techniques to systematically study the effect of AMPs on the cytoplasmic membrane of Escherichia coli (E. coli) bacteria using a simplified model system of 4:1 DMPE:DMPG ([1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine]:[1,2-dimyristoyl-sn-glycero-3-phospho-(10-rac-glycerol)]) phopholipid unilamellar vesicles. The studied antimicrobial peptides aurein 1.2, indolicidin, LL-37, lacticin Q and colistin vary in size, charge, degree of helicity and origin. The peptides insert into the bilayer to various degrees, and are found to accelerate the dynamics of phospholipids significantly as seen by time resolved SANS (TR-SANS) measurements, with the exception of colistin that is suggested to rather interact with lipopolysaccharid (LPS) on the outer membrane of E. coli. We compare these results with earlier published data on model systems based on PC-lipids (phosphatidylcholines), showing comparable effect with regards to peptide insertion and effect on dynamis. However, model systems based on PE-lipids (phosphatidylethanolamine) are more prone to destabilisation upon addition of peptides, with formation of multilamellar structures and morphological changes. These properties of PE-vesicles lead to less conclusive results regarding peptide effect on structure and dynamics of the membrane.

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Supplementary files

Article information


Submitted
27 Apr 2020
Accepted
11 Sep 2020
First published
21 Sep 2020

Faraday Discuss., 2020, Accepted Manuscript
Article type
Paper

Impact of Antimicrobial Peptides on E.coli-mimicking Lipid Model Membranes: correlating structural and dynamic effects using scattering methods

J. E. Nielsen, S. Prevost, J. havard and R. Lund, Faraday Discuss., 2020, Accepted Manuscript , DOI: 10.1039/D0FD00046A

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