Nanomechanical Characterization of the Synergism of Antimicrobial Peptides PGLa and Mag2 for Lipid Membrane Disruption

Antimicrobial peptides are an attractive alternative to traditional antibiotics, due to their physicochemical properties, activity toward a broad spectrum of bacteria, and mode-of-actions distinct from those used by current antibiotics. In general, antimicrobial peptides kill bacteria by either disrupting their membrane, or by entering inside bacterial cells to interact with intracellular components. Characterization of their mode-of-action is essential to improve their activity, avoid resistance in bacterial pathogens, and accelerate their use as therapeutics. Here we review experimental biophysical tools that can be employed with model membranes and bacterial cells to characterize the mode-of-action of antimicrobial peptides.

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Characterization of dual effects induced by antimicrobial peptides: Regulated cell death or membrane disruption

Biochimica et Biophysica Acta (BBA) - General Subjects ◽

10.1016/j.bbagen.2012.02.015 ◽

2012 ◽

Vol 1820 (7) ◽

pp. 1062-1072 ◽

Cited By ~ 63

Author(s):

Edgar J. Paredes-Gamero ◽

Marta N.C. Martins ◽

Fábio A.M. Cappabianco ◽

Jaime S. Ide ◽

Antonio Miranda

Keyword(s):

Cell Death ◽

Antimicrobial Peptides ◽

Membrane Disruption ◽

Regulated Cell Death

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Electrophysiological Characterization of Transport Across Outer Membrane Channels from Gram-Negative Bacteria in Their Native Environment

10.26434/chemrxiv.8282204.v1 ◽

2019 ◽

Author(s):

Jiajun Wang ◽

Rémi Terrasse ◽

Jayesh Arun Bafna ◽

Lorraine Benier ◽

Mathias Winterhalter

Keyword(s):

Outer Membrane ◽

Lipid Membrane ◽

Membrane Vesicles ◽

Outer Membrane Vesicles ◽

Multi Drug Resistance ◽

Gram Negative Bacteria ◽

Membrane Channels ◽

Gram Negative ◽

Electrophysiological Characterization

Multi-drug resistance in Gram-negative bacteria is often associated with low permeability of the outer membrane. To investigate the role of membrane channels in the uptake of antibiotics, we extract, purify and reconstitute them into artificial planar membranes. To avoid this time-consuming procedure, here we show a robust approach using fusion of native outer membrane vesicles (OMV) into planar lipid bilayer which moreover allows also to some extend the characterization of membrane protein channels in their native environment. Two major membrane channels from Escherichia coli, OmpF and OmpC, were overexpressed from the host and the corresponding OMVs were collected. Each OMV fusion revealed surprisingly single or only few channel activities. The asymmetry of the OMV´s translates after fusion into the lipid membrane with the LPS dominantly present at the side of OMV addition. Compared to conventional reconstitution methods, the channels fused from OMVs containing LPS have similar conductance but a much broader distribution. The addition of Enrofloxacin on the LPS side yields somewhat higher association (kon) and lower dissociation (koff) rates compared to LPS-free reconstitution. We conclude that using outer membrane vesicles is a fast and easy approach for functional and structural studies of membrane channels in the native membrane.

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Dimerization of the Antimicrobial Peptide Polyphemusin I into One Polypeptide Chain: Theoretical and Practical Consequences

Biotekhnologiya ◽

10.21519/0234-2758-2019-35-5-36-41 ◽

2019 ◽

Vol 35 (5) ◽

pp. 36-41

Author(s):

V.A. Zenin ◽

E.G. Sadykhov ◽

A.N. Fedorov

Keyword(s):

Antimicrobial Peptides ◽

Pore Formation ◽

Lipid Membrane ◽

Polypeptide Chain ◽

Unique Identifier ◽

Bacterial Cultures ◽

In Series ◽

The Russian Federation ◽

Peptide Dimerization ◽

Putative Mechanism

A strategy of sequential dimerization of monomers of antimicrobial peptides (AMPs) into one polypeptide chain has been implemented on the example of a beta-structural AMP polyphemusin I which is one of the most effective candidate for use as an antibiotic. The possible polyphemusin I monomer and dimer structures in lipid membrane were studied in this work via molecular modeling. To this end, these molecules were chemically synthesized so that the dimer represented two monomers connected in series into one polypeptide chain with a flexible linker. The antimicrobial effects of monomer and dimer were then tested on various bacterial cultures, and their similarity was shown. Therefore, we can conclude that the pore formation is not a putative mechanism of the polyphemusin I action. antimicrobial peptides, peptide dimerization, mechanism of antimicrobial action, polyphemusin The work was supported by the Ministry of Science and Higher Education of the Russian Federation (Project Unique Identifier RFMEFI57517X0151).

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Electrochemical Properties of Lipid Membranes Self-Assembled from Bicelles

Membranes ◽

10.3390/membranes11010011 ◽

2020 ◽

Vol 11 (1) ◽

pp. 11

Author(s):

Damian Dziubak ◽

Kamil Strzelak ◽

Slawomir Sek

Keyword(s):

Electrochemical Properties ◽

Self Assembly ◽

Lipid Membranes ◽

Lipid Membrane ◽

Membrane Resistance ◽

Electrochemical Characteristics ◽

Freeze Thaw ◽

Lipid Films ◽

Supported Lipid Membranes

Supported lipid membranes are widely used platforms which serve as simplified models of cell membranes. Among numerous methods used for preparation of planar lipid films, self-assembly of bicelles appears to be promising strategy. Therefore, in this paper we have examined the mechanism of formation and the electrochemical properties of lipid films deposited onto thioglucose-modified gold electrodes from bicellar mixtures. It was found that adsorption of the bicelles occurs by replacement of interfacial water and it leads to formation of a double bilayer structure on the electrode surface. The resulting lipid assembly contains numerous defects and pinholes which affect the permeability of the membrane for ions and water. Significant improvement in morphology and electrochemical characteristics is achieved upon freeze–thaw treatment of the deposited membrane. The lipid assembly is rearranged to single bilayer configuration with locally occurring patches of the second bilayer, and the number of pinholes is substantially decreased. Electrochemical characterization of the lipid membrane after freeze–thaw treatment demonstrated that its permeability for ions and water is significantly reduced, which was manifested by the relatively high value of the membrane resistance.

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