Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks

Silva, Tânia; Claro, Bárbara; Silva, Bruno F. B.; Vale, Nuno; Gomes, Paula; Gomes, Maria Salomé; Funari, Sérgio S.; Teixeira, J.; Uhrı́ková, Daniela; Bastos, Margarida

doi:10.1021/acs.langmuir.7b03639

Cited by 36 publications

(34 citation statements)

References 69 publications

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“…The information on PxB behaviour documented in the literature together with results reported above demonstrate that the mechanism explaining the antimicrobial activity in our systems is not disintegration of the membrane due to pore formation. On the contrary, our findings are in favour of a mechanism of membrane condensation forming multilamellar lipid stacks, as shown recently in a model of a bacterial membrane and antimicrobial peptide of a cecropin A–melittin hybrid [ 56 ].…”

Section: Discussionsupporting

confidence: 65%

The Perturbation of Pulmonary Surfactant by Bacterial Lipopolysaccharide and Its Reversal by Polymyxin B: Function and Structure

Liskayová

Kanjaková

et al. 2018

IJMS

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After inhalation, lipopolysaccharide (LPS) molecules interfere with a pulmonary surfactant, a unique mixture of phospholipids (PLs) and specific proteins that decreases surface tension at the air–liquid interphase. We evaluated the behaviour of a clinically used modified porcine pulmonary surfactant (PSUR) in the presence of LPS in a dynamic system mimicking the respiratory cycle. Polymyxin B (PxB), a cyclic amphipathic antibiotic, is able to bind to LPS and to PSUR membranes. We investigated the effect of PxB on the surface properties of the PSUR/LPS system. Particular attention was paid to mechanisms underlying the structural changes in surface-reducing features. The function and structure of the porcine surfactant mixed with LPS and PxB were tested with a pulsating bubble surfactometer, optical microscopy, and small- and wide-angle X-ray scattering (SAXS/WAXS). Only 1% LPS (w/w to surfactant PLs) prevented the PSUR from reaching the necessary low surface tension during area compression. LPS bound to the lipid bilayer of PSUR and disturbed its lamellar structure by swelling. The structural changes were attributed to the surface charge unbalance of the lipid bilayers due to LPS insertion. PxB acts as an inhibitor of structural disarrangement induced by LPS and restores original lamellar packing, as detected by polarised light microscopy and SAXS.

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Section: Discussionsupporting

confidence: 65%

The Perturbation of Pulmonary Surfactant by Bacterial Lipopolysaccharide and Its Reversal by Polymyxin B: Function and Structure

Liskayová

Kanjaková

et al. 2018

IJMS

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“… 48 − 50 A similar scattering pattern was recently also reported for mixed phospholipid vesicles in the presence of peptides. 51 The formation mechanism of such an original lamellar structure likely originates from protein/lamellae interactions, for instance, through anchoring or bridging. Different lipid chain arrangements have been proposed for the observed double lamellar phases, but we have no experimental evidence to select one over the others.…”

Section: Resultsmentioning

confidence: 99%

The Impact of Nonequilibrium Conditions in Lung Surfactant: Structure and Composition Gradients in Multilamellar Films

et al. 2018

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The lipid–protein mixture that covers the lung alveoli, lung surfactant, ensures mechanical robustness and controls gas transport during breathing. Lung surfactant is located at an interface between water-rich tissue and humid, but not fully saturated, air. The resulting humidity difference places the lung surfactant film out of thermodynamic equilibrium, which triggers the buildup of a water gradient. Here, we present a millifluidic method to assemble multilamellar interfacial films from vesicular dispersions of a clinical lung surfactant extract used in replacement therapy. Using small-angle X-ray scattering, infrared, Raman, and optical microscopies, we show that the interfacial film consists of several coexisting lamellar phases displaying a substantial variation in water swelling. This complex phase behavior contrasts to observations made under equilibrium conditions. We demonstrate that this disparity stems from additional lipid and protein gradients originating from differences in their transport properties. Supplementing the extract with cholesterol, to levels similar to the endogenous lung surfactant, dispels this complexity. We observed a homogeneous multilayer structure consisting of a single lamellar phase exhibiting negligible variations in swelling in the water gradient. Our results demonstrate the necessity of considering nonequilibrium thermodynamic conditions to study the structure of lung surfactant multilayer films, which is not accessible in bulk or monolayer studies. Our reconstitution methodology also opens avenues for lung surfactant pharmaceuticals and the understanding of composition, structure, and property relationships at biological air–liquid interfaces.

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“…Previously, Silva et al reported a LUV ! collapsed MLV transition for the same lipid mixture in the presence of cecropin A (39). However, no coexisting sponge phase or other curvature-related structures were observed.…”

Section: Discussionmentioning

confidence: 88%

Magainin 2 and PGLa in Bacterial Membrane Mimics II: Membrane Fusion and Sponge Phase Formation

Kabelka

Pachler

Prévost

et al. 2019

Preprint

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We studied the synergistic mechanism of equimolar mixtures of magainin 2 (MG2a) and PGLa in phosphatidylethanolamine/phosphatidylglycerol mimics of Gram-negative cytoplasmic membranes. In a preceding paper [Pachler et al., Biophys. J. 2019 xxx], we reported on the early onset of parallel heterodimer formation of the two antimicrobial peptides already at low concentrations and the resulting defect formation in membranes. Here, we focus on the structures of the peptide/lipid aggregates occurring in the synergistic regime at elevated peptide concentrations. Using a combination of calorimetric, scattering, electron microscopic and in silico techniques, we demonstrate that the two peptides, even if applied individually, transform originally large unilamellar vesicles into multilamellar vesicles, with a collapsed interbilayer spacing resulting from peptide induced adhesion. Interestingly, the adhesion does not lead to a peptide induced lipid separation of charged and charge neutral species. In addition to this behavior, equimolar mixtures of MG2a and PGLa formed surface-aligned fibril-like structures, which induced adhesion zones between the membranes and the formation of transient fusion stalks in molecular dynamics simulations and a coexisting sponge phase observed by small-angle X-ray scattering. The previously reported increased leakage of lipid vesicles of identical composition in the presence of MG2a/PGLa mixtures is therefore related to a peptide-induced cross-linking of bilayers. STATEMENT OF SIGNIFICANCEWe demonstrate that the synergistic activity of the antimicrobial peptides MG2a and PGLa correlates to the formation of surface-aligned fibril-like peptide aggregates, which cause membrane adhesion, fusion and finally the formation of a sponge phase.

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Unravelling a Mechanism of Action for a Cecropin A-Melittin Hybrid Antimicrobial Peptide: The Induced Formation of Multilamellar Lipid Stacks

Cited by 36 publications

References 69 publications

The Perturbation of Pulmonary Surfactant by Bacterial Lipopolysaccharide and Its Reversal by Polymyxin B: Function and Structure

The Perturbation of Pulmonary Surfactant by Bacterial Lipopolysaccharide and Its Reversal by Polymyxin B: Function and Structure

The Impact of Nonequilibrium Conditions in Lung Surfactant: Structure and Composition Gradients in Multilamellar Films

Magainin 2 and PGLa in Bacterial Membrane Mimics II: Membrane Fusion and Sponge Phase Formation

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