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Membrane interactions of proline-rich antimicrobial peptide, Chex1-Arg20, multimers

Wenyi Li¹, Marc-Antoine Sani², Elaheh Jamasbi²

¹School of Chemistry, Bio21 Institute, University of Melbourne, VIC 3010, Australia; The Florey Institute of Neuroscience and Mental Health, University of Melbourne, VIC 3010, Australia.

Biochimica Et Biophysica Acta

|March 2, 2016

Abstract:

The increasing prevalence of antibiotic-resistant pathogens requires the development of new antibiotics. Proline-rich antimicrobial peptides (PrAMPs), including native apidaecins, Bac7, and oncocins or designed A3APO, show multi-modal actions against pathogens together with immunostimulatory activities. The interactions of the designed PrAMP, Chex1-Arg20, and its dimeric and tetrameric oligomers with different model membranes were investigated by circular dichroism spectroscopy, dynamic light scattering, zeta potential, differential scanning calorimetry, and dye leakage. Chex1-Arg20 oligomers showed stronger affinity and preferential binding to negatively charged phospholipid bilayers and led to lipid aggregation and neutralization. Fluorescence microscopy of negatively charged giant unilamellar vesicles with AlexFluor-647-labeled Chex1-Arg20 dimers and tetramers displayed aggregation at a peptide/lipid low ratio of 1:200 and at higher peptide concentrations (1:100/1:50) for Chex1-Arg20 monomer. Such interactions, aggregation, and neutralization of PrAMP oligomers additionally showed the importance of interactions of PrAMPs with negatively charged membranes.

Insights

New proline-rich antimicrobial peptides (PrAMPs) show potent activity against antibiotic-resistant pathogens. Oligomers of Chex1-Arg20 bind strongly to negatively charged membranes, disrupting them and enhancing antimicrobial action.

Area of Science:

Biochemistry
Microbiology
Materials Science

Background:

Antibiotic resistance necessitates novel therapeutic strategies.
Proline-rich antimicrobial peptides (PrAMPs) exhibit broad-spectrum antimicrobial and immunostimulatory effects.
Designed PrAMPs offer potential for enhanced therapeutic applications.

Purpose of the Study:

To investigate the membrane interaction mechanisms of a designed PrAMP, Chex1-Arg20, and its oligomers.
To determine the influence of oligomerization on PrAMP binding affinity and membrane disruption.
To elucidate the role of membrane charge in PrAMP-membrane interactions.

Main Methods:

Circular dichroism spectroscopy
Dynamic light scattering
Zeta potential measurements
Differential scanning calorimetry
Dye leakage assays
Fluorescence microscopy

Main Results:

Chex1-Arg20 oligomers demonstrated enhanced binding and preferential interaction with negatively charged phospholipid bilayers.
PrAMP oligomers induced lipid aggregation and membrane neutralization.
Fluorescence microscopy confirmed aggregation of labeled Chex1-Arg20 dimers and tetramers on negatively charged vesicles at low peptide/lipid ratios.
Monomeric Chex1-Arg20 required higher concentrations for similar aggregation effects.

Conclusions:

Oligomerization significantly enhances the interaction of Chex1-Arg20 with negatively charged membranes.
The preferential binding and disruptive effects on anionic membranes are crucial for PrAMP antimicrobial activity.
Understanding these interactions is vital for designing effective PrAMP-based therapeutics against resistant pathogens.

Read full analysis

Keywords:

Chex1-Arg20 multimers Lipid–peptide interactions Liposomes Phospholipid bilayers Proline-rich antimicrobial peptides

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