Visualization of diffusion limited antimicrobial peptide attack on supported lipid membranes

Abstract

Understanding the mechanism of action of antimicrobial peptides (AMP) is fundamental to the development and design of peptide based antimicrobials. Utilizing fast-scan atomic force microscopy (AFM) we detail the attack of an AMP on both prototypical prokaryotic (DOPC:DOPG) and eukaryotic (DOPC:DOPE) model lipid membranes on the nanoscale and in real time. Previously shown to have a favourable therapeutic index, we study Smp43, an AMP with a helical-hinge-helical topology isolated from the venom of the North African scorpion Scorpio maurus palmatus. We observe the dynamic formation of highly branched defects being supported by 2D diffusion models and further experimental data from liposome leakage assays and quartz crystal microbalance-dissipation (QCM-D) analysis, we propose that Smp43 disrupts these membranes via a common mechanism, which we have termed 'diffusion limited disruption' that encompasses elements of both the carpet model and the expanding pore mechanism.

Flowering Poration—A Synergistic Multi-Mode Antibacterial Mechanism by a Bacteriocin Fold

“…This scenario resembles mechanisms proposed for four- and five-helix protein toxins that insert into the upper leaflet of the bilayer where they arrange into pores ( González et al., 2000 ; Michalek et al., 2013 ). Similarly, antimicrobial peptides accumulate in the upper leaflet causing the thinning of phospholipid bilayers ( Heath et al., 2018 ). These studies indicate that as more peptide binds to the bilayers thinning areas grow in size but not in depth, as also observed for NI01 ( Figure 3 E) ( Mecke et al., 2005 ).…”

Cytotoxic Effects of Smp24 and Smp43 Scorpion Venom Antimicrobial Peptides on Tumour and Non-tumour Cell Lines

“…A threshold concentration is (often) then required before membrane disruption occurs. A multitude of models and mechanisms have been proposed to account for this subsequent disruption (Teixeira et al 2012;Heath et al 2018). One key challenge to developing AMPs as therapeutic agents is to minimize and hopefully eliminate any cytolytic effects on eukaryotes.…”

“…The mechanism of membrane disruption caused by Smp24 depended on phospholipid composition; the peptide formed toroidal pores in prokaryotic-like membranes but hexagonal phase non-lamellar phase structures were seen in eukaryotic-like membranes (Harrison et al 2016b). In comparison, Smp43 disrupted both types of membranes by a common mechanism that involves elements of both the carpet model and the expanding pore mechanism, that we have termed "diffusion-limited disruption" (Heath et al 2018). Here in more detail, we have set out to study the cytotoxic effects of Smp24 and Smp43 on non-tumour (hematopoietic stem cells, primary renal cells and immortalised keratinocytes) and tumour (myeloid and lymphoid leukaemia) eukaryotic cells lines.…”

GM1 Ganglioside role in the interaction of Alpha-synuclein with lipid membranes: Morphology and structure

“…Since the thickness of fully-hydrated DOPC bilayer is around 5.0 nm [56], we assumed that monomeric AS is able to remodel the bilayer morphology intercalating in the upper lipid monolayer and leading to a thinning and lateral expansion of the lipid molecules. This mechanism has been speculated in other experimental studies on the interaction of AS monomer, as well as of antimicrobial peptides [54][55][56], with both planar and vesicular model lipid membranes of different lipid composition [57][58][59][60]. Moreover, membrane thinning processes have been associated with biological processes mediated by AS, such as in vivo synaptic vesicle formation [4] and, in general, endocytosis [64], [65].…”