Anionic Membranes Research Articles

Do interactions between protein and phospholipids influence the release behavior from lipid-based exenatide depot systems?

The release mechanism for proteins and peptides from vesicular phospholipid gels (VPGs) is very complex. Drug release proceeds via a combination of erosion of the gel and diffusion of the drug out of it. This diffusion can be retarded by a slow permeation of the drug across the lipid bilayers in the gel as well as by its direct binding or adsorption to the lipid bilayers. Finally, the viscosity and homogeneity of the formulation may affect the release behavior. So far a direct correlation between one of these parameters and the release kinetics is not possible.In the present study, we aimed to investigate the contribution of drug-membrane interactions to the release kinetics of exenatide from differently composed VPGs (POPC, POPG and mixtures of both). To this end, in vitro release of exenatide as well as in vitro release of the phospholipids was monitored. Binding affinities were determined by microscale thermophoresis (MST).The sustained release behavior of exenatide could not simply be correlated to high viscosity of the VPG formulation. Release of exenatide from VPGs of anionic membranes containing POPG proceeded with a half-life of the order of 5 days and it seems to be controlled by the erosion of the gel. Its rate is unaffected by the initial pH inside the gel, independently of the strong impact of pH on exenatide binding to the membrane. At pH 4.5, exenatide is cationic and binds to membranes containing anionic POPG with a high affinity (Kd ≈ 10–30 µM).No high affinity membrane binding of exenatide is detected in this at pH 7.4, where exenatide is anionic, and to zwitterionic membranes composed of POPC. Exenatide release from the latter has a significantly longer half-life of 30 to 55 days. That means, these VPGs are much more resistant to erosion and show a very slow diffusional release. In this case, diffusion should be slowed down by the barrier function of the membranes rather than membrane affinity.In conclusion, erosion of the VPG matrix and membrane permeability of the drug are the major parameters influencing the release of exenatide from VPGs of POPC-POPG, whereas drug binding to the membranes had a minor effect only.

Orientational transition and complexation of DNA with anionic membranes: Weak and intermediate electrostatic coupling.

We characterize the role of charge correlations in the adsorption of a short, rodlike anionic polyelectrolyte onto a similarly charged membrane. Our theory reveals two different mechanisms driving the like-charge polyelectrolyte-membrane complexation: In weakly charged membranes, repulsive polyelectrolyte-membrane interactions lead to the interfacial depletion and a parallel orientation of the polyelectrolyte with respect to the membrane; while in the intermediate membrane charge regime, the interfacial counterion excess gives rise to an attractive "salt-induced" image force. This furthermore results in an orientational transition from a parallel to a perpendicular configuration and a subsequent short-ranged like-charge adsorption of the polyelectrolyte to the substrate. A further increase of the membrane charge engenders a charge inversion, originating from surface-induced ionic correlations, that act as a separate mechanism capable of triggering the like-charge polyelectrolyte-membrane complexation over an extended distance interval from the membrane surface. The emerging picture of this complexation phenomenon identifies the interfacial "salt-induced" image forces as a powerful control mechanism in polyelectrolyte-membrane complexation.

Design, Synthesis, Antibacterial Potential, and Structural Characterization of N-Acylated Derivatives of the Human Autophagy 16 Polypeptide.

A synthetic antimicrobial peptide library based on the human autophagy 16 polypeptide has been developed. Designed acetylated peptides bearing lipids of different chain lengths resulted in peptides with enhanced potency compared to the parent Atg16. A 21-residue fragment of Atg16 conjugated to 4-methylhexanoic acid (K30) emerged as the most potent antibacterial, with negligible hemolysis. Several studies, including microscopy, dye leakage, and ITC, were conducted to gain insight into the antibacterial mechanism of action of the peptide. Visual inspection using both SEM and TEM revealed the membranolytic effect of the peptide on bacterial cells. The selectivity of the peptide against bacterial cell membranes was also proven using dye leakage assays. ITC analysis revealed the exothermic nature of the binding interaction of the peptide to D8PG micelles. The three-dimensional solution NMR structure of K30 in complex with dioctanoylphosphatidylglycerol (D8PG) micelles revealed that the peptide adopts a helix-loop-helix structure in the presence of anionic membrane lipids mimicking bacterial membranes. Intermolecular NOEs between the peptide and lipid deciphered the location of the peptide in the bound state, which was subsequently supported by the paramagnetic relaxation enhancement (PRE) NMR experiment. Collectively, these results describe the structure-function relationship of the peptide in the bacterial membrane.

Elucidating the Lipid Binding Properties of Membrane-Active Peptides Using Cyclised Nanodiscs.

The lipid composition of the cellular membrane plays an important role in a number of biological processes including the binding of membrane-active peptides. Characterization of membrane binding remains challenging, due to the technical limitations associated with the use of standard biophysical techniques and available membrane models. Here, we investigate the lipid binding properties of two membrane-active peptides, VSTx1, a well characterized ion-channel inhibitor, identified from spider venom, that preferentially binds to anionic lipid mixtures, and AA139 an antimicrobial β-hairpin peptide with uncharacterised lipid binding properties, currently in pre-clinical development. The lipid binding properties of these peptides are elucidated using nanodiscs formed by both linear and circularized (sortase-mediated) forms of a membrane scaffold protein (MSP1D1ΔH5). We find that nanodiscs formed by circularized MSPs—in contrast to those formed by linear MSPs—are sufficiently stable under sample conditions typically used for biophysical measurements (including lipid composition, a range of buffers, temperatures and concentrations). Using these circularized nanodiscs, we are able to extract detailed thermodynamic data using isothermal titration calorimetry (ITC) as well as atomic resolution mapping of the lipid binding interfaces of our isotope labeled peptides using solution-state, heteronuclear, nuclear magnetic resonance (NMR) spectroscopy. This represents a novel and general approach for elucidating the thermodynamics and molecular interface of membrane-active peptides toward flat lipid bilayers of variable composition. Our approach is validated by first determining the thermodynamic parameters and binding interface of VSTx1 toward the lipid bilayer, which shows good agreement with previous studies using lipid micelles and liposomes. The method is then applied to AA139, where the membrane binding properties are unknown. This characterization, involved solving the high-resolution structure of AA139 in solution using NMR spectroscopy and the development of a suitable expression system for isotope labeling. AA139 was found to bind exclusively to anionic membranes with moderate affinity (Kd~low μM), and was found to have a lipid binding interface involving the termini of the β-hairpin structure. The preference of AA139 for anionic lipids supports a role for membrane binding in the mode-of-action of this peptide, which is also consistent with its higher inhibitory activity against bacterial cells compared to mammalian cells. The described approach is a powerful method for investigation of the membrane binding properties of this important class of molecules.

A sustainable self-reproducing liposome consisting of a synthetic phospholipid.

A novel phosphoric membrane lipid (phospholipid) bearing an oleyl group as one of the hydrophobic chains formed a liposome with a thin lamella in water. Since the anionic membrane of pre-existing liposomes acted as a catalytic surface in phosphate buffer, membrane lipids could be generated from their precursor in an autocatalytic manner without the inclusion of catalytic amphiphiles in the liposome. The morphological changes of this anionic liposome were monitored both by flow cytometry and optical microscopy, and it was found that the liposomes deformed into a budding shape, followed by division, after the addition of a membrane precursor. Hence, this anionic monocomponent liposome could be regarded as a sustainable self-reproducing system. This liposome was also able to provide a reaction cavity for enzymatic reactions, such as DNA amplification by a polymerase chain reaction.

Membrane Sphingolipids Regulate the Fitness and Antifungal Protein Susceptibility of Neurospora crassa.

The membrane sphingolipid glucosylceramide (GlcCer) plays an important role in fungal fitness and adaptation to most diverse environments. Moreover, reported differences in the structure of GlcCer between fungi, plants and animals render this pathway a promising target for new generation therapeutics. Our knowledge about the GlcCer biosynthesis in fungi is mainly based on investigations of yeasts, whereas this pathway is less well characterized in molds. We therefore performed a detailed lipidomic profiling of GlcCer species present in Neurospora crassa and comprehensively show that the deletion of genes encoding enzymes involved in GlcCer biosynthesis affects growth, conidiation and stress response in this model fungus. Importantly, our study evidences that differences in the pathway intermediates and their functional role exist between N. crassa and other fungal species. We further investigated the role of GlcCer in the susceptibility of N. crassa toward two small cysteine-rich and cationic antimicrobial proteins (AMPs), PAF and PAFB, which originate from the filamentous ascomycete Penicillium chrysogenum. The interaction of these AMPs with the fungal plasma membrane is crucial for their antifungal toxicity. We found that GlcCer determines the susceptibility of N. crassa toward PAF, but not PAFB. A higher electrostatic affinity of PAFB than PAF to anionic membrane surfaces might explain the difference in their antifungal mode of action.

Interaction of the antibiotic peptide nisin with anionic membranes in different phase-states: a vibrational study.

Interactions between the antibiotic peptide nisin and multilamellar vesicles of phosphoglycerol lipids in different phase-states were studied using vibrational spectroscopy. The infrared amide I' band of nisin, both in solution and in the membrane-bound state, was analyzed in the temperature range comprised between 20 and 60 °C in order to study its conformational behavior. Nisin presented mainly unordered and β-turns conformations. Their relative populations varied according to the environment and as the temperature increased: β turns were more favored in the membrane-bound state than in solution, but at higher temperatures the disordered conformation was dominant in both states. Spectral changes of specific infrared bands belonging to the hydrocarbon and polar moieties of lipids were also analyzed to evaluate the perturbation of the lipid membrane order. Nisin interactions with the membrane polar region induced a high restriction to water incorporation, promoting a small increase in the temperature of the lipid phase transition. Raman spectra of nisin/phosphoglycerol systems at ambient temperature were also analyzed. They revealed that the peptide incorporation to a membrane in the fluid phase caused drastic structural modifications in the hydrophobic region of the bilayer. Although nisin may be able to disrupt the hydrophobic portion of the bilayer in the gel phase, the most of the peptide molecule remained at the membrane surface interacting with the polar headgroups. This work provides evidence of a differential effect of nisin on anionic membranes, depending on the phase-state of the lipid.

Mechanistic predictions of the influence of collagen-binding domain sequences on human LL37 interactions with model lipids using quartz crystal microbalance with dissipation.

Modifications of human-derived antimicrobial peptide LL37 with collagen binding domains (CBD-LL37) hold promise as alternatives to antibiotics due to their wider therapeutic ratio than unmodified LL37 when interacting with collagen substrates such as commercial wound dressings. However, CBD-LL37 lipid membrane interaction mechanisms (against both mammalian and bacterial lipids) are not well understood. Our goal was to develop a mechanistic explanation of how CBDs modulate peptide-lipid interactions leading to their observed bioactivities, in order to better understand their potential for clinical applications. The authors studied time- and concentration-dependent interactions of CBD-LL37 modified with collagenase (cCBD) and fibronectin (fCBD) CBDs, with zwitterionic and anionic supported lipid bilayers, in order to model mammalian erythrocytes and bacterial cells, respectively. Quartz crystal microbalance with dissipation monitoring (QCM-D) was used to characterize peptide-lipid interactions at concentrations in the immunomodulatory (0.5-1.0 μM), antimicrobial (1.0-5.0 μM), and cytotoxic (5.0-10.0 μM) ranges. Their prior work with zwitterionic membranes demonstrated that cCBD-LL37 formed transmembrane pores while fCBD-LL37 underwent surface adsorption. Our goal in this study is to better interpret these results, by investigating the data at a wider concentration range and for two types of lipids, and by applying the Voigt-Kelvin viscoelastic model to calculate thickness and density changes of the peptide-lipid films as a function of time and concentration, thus providing information to help build detailed mechanisms of peptide/bilayer interactions. For pore-forming cCBD-LL37 and unmodified LL37, they found that there was a relationship between layer thicknesses and pore formation, which was attributed to different peptide orientation changes influenced by bilayer charge prior to pore formation. Specifically, cCBD-LL37 at 0.5 and 1.0 μM demonstrated higher thicknesses on zwitterionic than anionic membranes, indicating that prior to insertion into zwitterionic membranes, it orients perpendicular to the surface, which was also consistent with the higher dissipation changes observed on zwitterionic membranes. fCBD-LL37 demonstrated a bilayer adsorption mechanism with a preference toward anionic lipids. Adsorption of fCBD-LL37 onto anionic lipids demonstrated a rapid first adsorption step that transitioned depending on the number of fCBD-LL37 molecules on the bilayer. For this peptide at higher concentrations, greater dissipation changes were observed than for fCBD-LL37 physically adsorbed onto surfaces without bilayers. This suggests that peptide-peptide interactions promoted by the fCBD domain dominated after saturation. The development of a structure-function relationship for cCBD-LL37 and fCBD-LL37 demonstrates promise for using QCM-D predictions to inform the rational design of novel, antimicrobial, and noncytotoxic CBD-LL37 for clinical applications.

Performance of a greywater cathode in a microbial fuel cell with three ion exchange membranes

AbstractBACKGROUNDGreywater and blackwater treatment is necessary to make sanitation and water reuse possible, and microbial fuel cells (MFCs) have emerged as a promising technology for achieving this objective. Ion exchange membranes play a key role in double chamber microbial fuel cell performance, but there are differences of opinion as to which membrane type is better.RESULTSThis project was set up to study the effect of three ion exchange membranes (Nafion® 117, Ultrex™ CMI‐7000 and Ultrex™ AMI‐7001) in MFCs using greywater as catholyte in stacks of three microbial fuel cells each. The results demonstrate that the stacks with cationic membranes (Nafion® 117 and Ultrex™ CMI‐7000) generated higher power (201.50 ± 21.62 and 178.74 ± 56.89 mW m−3, respectively) than those with the anionic membrane stack Ultrex™ AMI‐7001 (71.57 ± 3.46 mW m−3). For the greywater catholyte, a 31% of chemical oxygen demand removal was achieved and proved to be an option as a catholyte in microbial fuel cells for countries that carry out wastewater separation.CONCLUSIONSThe results obtained in this study demonstrated that an anion exchange membrane is not a better option for double chamber MFCs. © 2019 Society of Chemical Industry

Crown ether modified peptide interactions with model membranes‡

ABSTRACTA simple model of an uncharged antimicrobial peptide, carrying four crown ether side chains, is modified further by the selective incorporation of arginine side chains to control its secondary structure and its interaction with model membranes and living cells. Conformational studies show that shifting the position of a cationic residue in the peptide sequence allows to control its secondary structure and supramolecular self-assembly in solution. Results also demonstrate that the secondary structure influences the interaction with model membranes and cells. An α-helical peptide with greater amphiphilicity forms assemblies that interact with both prokaryotic and eukaryotic model membranes and cells. However, a β-stranded peptide with evenly distributed charges generates assemblies that interact more selectively with prokaryotic model membranes and cells. In addition, we observed differences in peptide orientation between uncharged and cationic α-helical peptides with different phospholipid bilayers. In general, the studied peptides have a higher affinity for thinner membranes, and cationic peptides interacted better with anionic membranes.

Antibiotic resistance and host immune evasion in Staphylococcus aureus mediated by a metabolic adaptation

Staphylococcus aureus is a notorious human bacterial pathogen with considerable capacity to develop antibiotic resistance. We have observed that human infections caused by highly drug-resistant S. aureus are more prolonged, complicated, and difficult to eradicate. Here we describe a metabolic adaptation strategy used by clinical S. aureus strains that leads to resistance to the last-line antibiotic, daptomycin, and simultaneously affects host innate immunity. This response was characterized by a change in anionic membrane phospholipid composition induced by point mutations in the phospholipid biosynthesis gene, cls2, encoding cardiolipin synthase. Single cls2 point mutations were sufficient for daptomycin resistance, antibiotic treatment failure, and persistent infection. These phenotypes were mediated by enhanced cardiolipin biosynthesis, leading to increased bacterial membrane cardiolipin and reduced phosphatidylglycerol. The changes in membrane phospholipid profile led to modifications in membrane structure that impaired daptomycin penetration and membrane disruption. The cls2 point mutations also allowed S. aureus to evade neutrophil chemotaxis, mediated by the reduction in bacterial membrane phosphatidylglycerol, a previously undescribed bacterial-driven chemoattractant. Together, these data illustrate a metabolic strategy used by S. aureus to circumvent antibiotic and immune attack and provide crucial insights into membrane-based therapeutic targeting of this troublesome pathogen.

The Effect of Ions on Membrane Elasticity - Implications for Vesicle Fusion

Ions and charged peptides can have dramatic effects on the properties of membranes. A case in point is calcium and its crucial role in vesicle fusion.[1] Using all-atom molecular dynamics, we simulated calcium mediated vesicle fusion.[2] Aided by a new, local approach to determining membrane elastic properties,[3] we are able to quantify the effect of ions on lipid spontaneous curvature, bending rigidity, and tilt. We probe the effect of ions on membranes of different composition. Our simulations indicate that calcium specifically induces negative spontaneous curvature in those anionic lipid membranes which are susceptible to calcium mediated fusion, concomitantly strongly affecting the Gaussian bending modulus. We further determine the mechanism of membrane curvature induction through ion-headgroup interactions, giving special attention to lipid clustering. In addition to membrane elasticity, we discuss electrostatic effects on osmotic pressures and the hydration force. This systematic approach allows us to fill crucial gaps in our understanding of the mechanism of membrane fusion. Finally, we point out possible implications for synaptic vesicle fusion and endocytosis. [1] E. Neher, R. Schneggenburger, Nature 406, 889-893 (2000) [2] C. Allolio, A. Magarkar, P. Jurkiewicz, K. Baxova, M. Javanainen, R. Šachl, M. Hof, D. Horinek, V. Heinz, R. Rachel, C. Ziegler, M. Cebecauer, A. Schrofel, P. Jungwirth, resubmitted to PNAS (2018) [3] C. Allolio, A. Haluts, D. Harries,Chem. Phys, in press (2018)

Phosphatidylserine (PS) Externalization Facilitates Membrane Vesiculation through Decreasing Membrane Stiffness

Extracellular vesicles (EVs) including exosomes and microvesicles play critical roles in intercellular communication by exchanging proteins, lipids, and genetic materials between cells. However, the origin and biogenesis of these vesicles remain unclear. It has been noted that almost all EVs present the anionic membrane lipid phosphatidylserine (PS) on their outer leaflet, in opposition to their cells of origin, which almost exclusively retain PS in the cytoplasmic leaflet. The "scrambling” of PS from the inner to the outer leaflet of the bilayer is facilitated by the lipid channel Ano6. This process of lipid scrambling has been implicated in a variety of physiological contexts, including apoptotic cell removal, bone mineralization, viral infection and blood coagulation. However, the biophysical role of PS externalization in the formation of extracellular vesicles is still a mystery. Using micrometer-sized giant plasma membrane vesicles (GPMVs) that are produced by membrane blebbing from mouse B-cells (BaF3), we studied the role of PS externalization in membrane vesiculation. We first found that a scramblase (i.e. Ano6) knockout BaF3 cell line was deficient in producing large vesicles compared with the wild type cell line, indicating that PS externalization is necessary for membrane budding. Importantly, through fluorescence lifetime imaging microscopy (FLIM) using a reporter of lipid packing (Di4), we found that PS exposure lead to a decrease of plasma membrane packing, potentially make the membrane softer for bending and thus facilitating membrane budding. To confirm this assumption, we artificially decreased the lipid order on the plasma membrane by increasing the incubation temperature or treating the cells with methyl-β-cyclodextrin (MβCD). Under all conditions which reduced membrane stiffness, large vesicles were efficiently produced from the PS externalization-deficient Ano6 knockout cell line, confirming the crucial role of membrane stiffness in cell vesiculation.

Characterization of encapsulated cells within hyaluronic acid and alginate microcapsules produced via horseradish peroxidase-catalyzed crosslinking

Hydrogel microcapsules having the ability to promote cell adhesion and proliferation are a useful tool for fabricating tissue in vitro. The present study explored the effects of two anionic polysaccharide hydrogel membranes which have an impact on the adhesiveness, morphology and growth of cells. Microcapsules were made by coating a cell-laden gelatin microparticle with a hydrogel membrane produced from modified hyaluronic acid or alginate possessing phenolic hydroxyl moieties (HA-Ph or Alg-Ph respectively) via a horseradish peroxidase-catalyzed crosslinking reaction. Some gelatin was retained within the microcapsules to support the attachment and growth of encapsulated cells. The morphological and functional characteristics of encapsulated HeLa and 10T1/2 cells were evaluated. The HA-Ph hydrogel, which exhibited greater retention of gelatin, showed a higher degree of cytocompatibility with respect to cell adhesion, spreading and proliferation compared with the Alg-Ph hydrogel membrane. These findings indicate that HA-Ph microcapsules synthesized around a temporary gelatin microparticles are a promising cell vehicle for tissue engineering applications.

Liquid crystalline microspheres of azobenzene amphiphiles formed by thermally induced pH changes in binary water-hydrolytic ionic liquid media.

Anionic azobenzene-containing bilayered membranes dispersed in binary water-ionic liquid (IL) media undergo proton-responsive transformation into liquid crystalline microspheres (LCMs). This transformation was induced by protons released by the heat-induced hydrolysis of tetrafluoroborate ions in the ILs. This work demonstrates the first beneficial use of hydrolysis-susceptible ILs in chemistry.

Anionic nanoparticle-lipid membrane interactions: the protonation of anionic ligands at the membrane surface reduces membrane disruption.

Monolayer-protected gold nanoparticles (Au NPs) are promising biomedical tools with applications in diagnosis and therapy, thanks to their biocompatibility and versatility. Here we show how the NP surface functionalization can drive the mechanism of interaction with lipid membranes. In particular, we show that the spontaneous protonation of anionic carboxylic groups on the NP surface can make the NP-membrane interaction faster and less disruptive.

Synthetic cell-like membrane interfaces for probing dynamic protein-lipid interactions.

The ability to rapidly screen interactions between proteins and membrane-like interfaces would aid in establishing the structure-function of protein-lipid interactions, provide a platform for engineering lipid-interacting protein tools, and potentially inform the signaling mechanisms and dynamics of membrane-associated proteins. Here, we describe the preparation and application of water-in-oil (w/o) emulsions with lipid-stabilized droplet interfaces that emulate the plasma membrane inner leaflet with tunable composition. Fluorescently labeled proteins are easily visualized in these synthetic cell-like droplets on an automated inverted fluorescence microscope, thus allowing for both rapid screening of relative binding and spatiotemporally resolved analyses of for example, protein-interface association and dissociation dynamics and competitive interactions, using commonplace instrumentation. We provide protocols for droplet formation, automated imaging assays and analysis, and the production of the positive control protein BcLOV4, a natural photoreceptor with a directly light-regulated interaction with anionic membrane phospholipids that is useful for optogenetic membrane recruitment.

Cd(II)- and Pb(II)-Induced Self-Assembly of Peripheral Membrane Domains from Protein Kinase C.

Cd2+ and Pb2+ are xenobiotic heavy metal ions that use ionic mimicry to interfere with the cellular function of biomacromolecules. Using a combination of SAXS, electron microscopy, FRET, and solution NMR spectroscopy, we demonstrate that treatment with Cd2+ and Pb2+ causes self-assembly of protein kinase C regulatory domains that peripherally associate with membranes. The self-assembly process successfully competes with ionic mimicry and is mediated by conserved protein regions that are distinct from the canonical Ca2+-binding motifs of protein kinase C. The ability of protein oligomers to interact with anionic membranes is enhanced compared to the monomeric species. Our findings suggest that metal-ion-dependent peripheral membrane domains can be utilized for generating protein-metal-ion nanoclusters and serve as biotemplates for the design of sequestration agents.

Dynamics of Membrane-Bound G12V-KRAS from Simulations and Single-Molecule FRET in Native Nanodiscs

Recent studies have shown that the small GTPase KRAS adopts multiple orientations with respect to the plane of anionic model membranes, whereby either the three C-terminal helices or the three N-terminal β-strands of the catalytic domain face the membrane. This has functional implications because, in the latter, the membrane occludes the effector-interacting surface. However, it remained unclear how membrane reorientation occurs and, critically, whether it occurs in the cell in which KRAS operates as a molecular switch in signaling pathways. Herein, using data from a 20 μs-long atomistic molecular dynamics simulation of the oncogenic G12V-KRAS mutant in a phosphatidylcholine/phosphatidylserine bilayer, we first show that internal conformational fluctuations of flexible regions in KRAS result in three distinct membrane orientations. We then show, using single-molecule fluorescence resonance energy transfer measurements in native lipid nanodiscs derived from baby hamster kidney cells, that G12V-KRAS samples three conformational states that correspond to the predicted orientations. The combined results suggest that relatively small energy barriers separate orientation states and that signaling-competent conformations dominate the overall population.

Could Cardiolipin Protect Membranes against the Action of Certain Antimicrobial Peptides? Aurein 1.2, a Case Study.

The activity of a host of antimicrobial peptides has been examined against a range of lipid bilayers mimicking bacterial and eukaryotic membranes. Despite this, the molecular mechanisms and the nature of the physicochemical properties underlying the peptide–lipid interactions that lead to membrane disruption are yet to be fully elucidated. In this study, the interaction of the short antimicrobial peptide aurein 1.2 was examined in the presence of an anionic cardiolipin-containing lipid bilayer using molecular dynamics simulations. Aurein 1.2 is known to interact strongly with anionic lipid membranes. In the simulations, the binding of aurein 1.2 was associated with buckling of the lipid bilayer, the degree of which varied with the peptide concentration. The simulations suggest that the intrinsic properties of cardiolipin, especially the fact that it promotes negative membrane curvature, may help protect membranes against the action of peptides such as aurein 1.2 by counteracting the tendency of the peptide to induce positive curvature in target membranes.