1
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Pabst G, Keller S. Exploring membrane asymmetry and its effects on membrane proteins. Trends Biochem Sci 2024; 49:333-345. [PMID: 38355393 DOI: 10.1016/j.tibs.2024.01.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/08/2024] [Accepted: 01/19/2024] [Indexed: 02/16/2024]
Abstract
Plasma membranes utilize free energy to maintain highly asymmetric, non-equilibrium distributions of lipids and proteins between their two leaflets. In this review we discuss recent progress in quantitative research enabled by using compositionally controlled asymmetric model membranes. Both experimental and computational studies have shed light on the nuanced mechanisms that govern the structural and dynamic coupling between compositionally distinct bilayer leaflets. This coupling can increase the membrane bending rigidity and induce order - or lipid domains - across the membrane. Furthermore, emerging evidence indicates that integral membrane proteins not only respond to asymmetric lipid distributions but also exhibit intriguing asymmetric properties themselves. We propose strategies to advance experimental research, aiming for a deeper, quantitative understanding of membrane asymmetry, which carries profound implications for cellular physiology.
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Affiliation(s)
- Georg Pabst
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz 8010, Austria; BioTechMed-Graz, Graz, Austria; Field of Excellence BioHealth, University of Graz, Graz, Austria.
| | - Sandro Keller
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz 8010, Austria; BioTechMed-Graz, Graz, Austria; Field of Excellence BioHealth, University of Graz, Graz, Austria
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2
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Eckhardt D, Semeraro EF, Steigenberger J, Schnur J, Kalie L, Massing U, Pabst G, Heerklotz H. Eutectic Resolves Lysolipid Paradox in Thermoresponsive Liposomes. Mol Pharm 2024; 21:1768-1776. [PMID: 38381374 DOI: 10.1021/acs.molpharmaceut.3c01094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
A better molecular understanding of the temperature-triggered drug release from lysolipid-based thermosensitive liposomes (LTSLs) is needed to overcome the recent setbacks in developing this important drug delivery system. Enhanced drug release was previously rationalized in terms of detergent-like effects of the lysolipid monostearyl lysophosphatidylcholine (MSPC), stabilizing local membrane defects upon LTSL lipid melting. This is highly surprising and here referred to as the 'lysolipid paradox,' because detergents usually induce the opposite effect─they cause leakage upon freezing, not melting. Here, we aim at better answers to (i) why lysolipid does not compromise drug retention upon storage of LTSLs in the gel phase, (ii) how lysolipids can enhance drug release from LTSLs upon lipid melting, and (iii) why LTSLs typically anneal after some time so that not all drug gets released. To this end, we studied the phase transitions of mixtures of dipalmitoylphosphatidylcholine (DPPC) and MSPC by a combination of differential scanning and pressure perturbation calorimetry and identified the phase structures with small- and wide-angle X-ray scattering (SAXS and WAXS). The key result is that LTSLs, which contain the standard amount of 10 mol % MSPC, are at a eutectic point when they release their cargo upon melting at about 41 °C. The eutectic present below 41 °C consists of a MSPC-depleted gel phase as well as small domains of a hydrocarbon chain interdigitated gel phase containing some 30 mol % MSPC. In these interdigitated domains, the lysolipid is stored safely without compromising membrane integrity. At the eutectic temperature, both the MSPC-depleted bilayer and interdigitated MSPC-rich domains melt at once to fluid bilayers, respectively. Intact, fluid membranes tolerate much less MSPC than interdigitated domains─where the latter have melted, the high local MSPC content causes transient pores. These pores allow for fast drug release. However, these pores disappear, and the membrane seals again as the MSPC distributes more evenly over the membrane so that its local concentration decreases below the pore-stabilizing threshold. We provide a pseudobinary phase diagram of the DPPC-MSPC system and structural and volumetric data for the interdigitated phase.
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Affiliation(s)
- Daniel Eckhardt
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg D79104, Germany
| | - Enrico F Semeraro
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz 8010, Austria
- Field of Excellence BioHealth, University of Graz, Graz 8010, Austria
| | - Jessica Steigenberger
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg D79104, Germany
| | - Johannes Schnur
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg D79104, Germany
| | - Louma Kalie
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg D79104, Germany
| | - Ulrich Massing
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg D79104, Germany
| | - Georg Pabst
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz 8010, Austria
- Field of Excellence BioHealth, University of Graz, Graz 8010, Austria
| | - Heiko Heerklotz
- Institute of Pharmaceutical Sciences, University of Freiburg, Freiburg D79104, Germany
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
- BIOSS Signaling Research Center, Freiburg D79104, Germany
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3
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Schütz GJ, Pabst G. The asymmetric plasma membrane-A composite material combining different functionalities?: Balancing Barrier Function and Fluidity for Effective Signaling. Bioessays 2023; 45:e2300116. [PMID: 37712937 DOI: 10.1002/bies.202300116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/31/2023] [Accepted: 09/06/2023] [Indexed: 09/16/2023]
Abstract
One persistent puzzle in the life sciences is the asymmetric lipid composition of the cellular plasma membrane: while the exoplasmic leaflet is enriched in lipids carrying predominantly saturated fatty acids, the cytoplasmic leaflet hosts preferentially lipids with (poly-)unsaturated fatty acids. Given the high energy requirements necessary for cells to maintain this asymmetry, the question naturally arises regarding its inherent benefits. In this paper, we propose asymmetry to represent a potential solution for harmonizing two conflicting requirements for the plasma membrane: first, the need to build a barrier for the uncontrolled influx or efflux of substances; and second, the need to form a fluid and dynamic two-dimensional substrate for signaling processes. We hence view here the plasma membrane as a composite material, where the exoplasmic leaflet is mainly responsible for the functional integrity of the barrier and the cytoplasmic leaflet for fluidity. We reinforce the validity of the proposed mechanism by presenting quantitative data from the literature, along with multiple examples that bolster our model.
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Affiliation(s)
| | - Georg Pabst
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth-University of Graz, Graz, Austria
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4
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Javanainen M, Heftberger P, Madsen JJ, Miettinen MS, Pabst G, Ollila OHS. Quantitative Comparison against Experiments Reveals Imperfections in Force Fields' Descriptions of POPC-Cholesterol Interactions. J Chem Theory Comput 2023; 19:6342-6352. [PMID: 37616238 PMCID: PMC10536986 DOI: 10.1021/acs.jctc.3c00648] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Indexed: 08/26/2023]
Abstract
Cholesterol is a central building block in biomembranes, where it induces orientational order, slows diffusion, renders the membrane stiffer, and drives domain formation. Molecular dynamics (MD) simulations have played a crucial role in resolving these effects at the molecular level; yet, it has recently become evident that different MD force fields predict quantitatively different behavior. Although easily neglected, identifying such limitations is increasingly important as the field rapidly progresses toward simulations of complex membranes mimicking the in vivo conditions: pertinent multicomponent simulations must capture accurately the interactions between their fundamental building blocks, such as phospholipids and cholesterol. Here, we define quantitative quality measures for simulations of binary lipid mixtures in membranes against the C-H bond order parameters and lateral diffusion coefficients from NMR spectroscopy as well as the form factors from X-ray scattering. Based on these measures, we perform a systematic evaluation of the ability of commonly used force fields to describe the structure and dynamics of binary mixtures of palmitoyloleoylphosphatidylcholine (POPC) and cholesterol. None of the tested force fields clearly outperforms the others across the tested properties and conditions. Still, the Slipids parameters provide the best overall performance in our tests, especially when dynamic properties are included in the evaluation. The quality evaluation metrics introduced in this work will, particularly, foster future force field development and refinement for multicomponent membranes using automated approaches.
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Affiliation(s)
- Matti Javanainen
- Institute
of Organic Chemistry and Biochemistry, Academy
of Sciences of the Czech Republic, 16000 Prague 6, Czech Republic
- Institute
of Biotechnology, University of Helsinki, 00790 Helsinki, Finland
| | - Peter Heftberger
- Biophysics,
Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
| | - Jesper J. Madsen
- Global
and Planetary Health, College of Public Health, University of South Florida, Tampa, Florida 33612, United States
- Center
for Global Health and Infectious Diseases Research, College of Public
Health, University of South Florida, Tampa, Florida 33612, United States
- Department
of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida 33612, United States
| | - Markus S. Miettinen
- Fachbereich
Physik, Freie Universität Berlin, 14195 Berlin, Germany
- Department
of Chemistry, University of Bergen, 5007 Bergen, Norway
- Computational
Biology Unit, Department of Informatics, University of Bergen, 5008 Bergen, Norway
| | - Georg Pabst
- Biophysics,
Institute of Molecular Biosciences, NAWI Graz, University of Graz, 8010 Graz, Austria
- BioTechMed-Graz, 8010 Graz, Austria
- Field of Excellence
BioHealth—University of Graz, 8010 Graz, Austria
| | - O. H. Samuli Ollila
- Institute
of Biotechnology, University of Helsinki, 00790 Helsinki, Finland
- VTT Technical Research Centre of Finland, 02150 Espoo, Finland
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5
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Jennings J, Ašćerić D, Semeraro EF, Lohner K, Malanovic N, Pabst G. Combinatorial Screening of Cationic Lipidoids Reveals How Molecular Conformation Affects Membrane-Targeting Antimicrobial Activity. ACS Appl Mater Interfaces 2023; 15:40178-40190. [PMID: 37602460 PMCID: PMC10472336 DOI: 10.1021/acsami.3c05481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 08/04/2023] [Indexed: 08/22/2023]
Abstract
The search for next-generation antibacterial compounds that overcome the development of resistance can be facilitated by identifying how to target the cell membrane of bacteria. Understanding the key molecular features that enable interactions with lipids and lead to membrane disruption is therefore crucial. Here, we employ a library of lipid-like compounds (lipidoids) comprising modular structures with tunable hydrophobic and hydrophilic architecture to shed light on how the chemical functionality and molecular shape of synthetic amphiphilic compounds determine their activity against bacterial membranes. Synthesized from combinations of 8 different polyamines as headgroups and 13 acrylates as tails, 104 different lipidoids are tested for activity against a model Gram-positive bacterial strain (Bacillus subtilis). Results from the combinatorial screening assay show that lipidoids with the most potent antimicrobial properties (down to 2 μM) have intermediate tail hydrophobicity (i.e., c log P values between 3 and 4) and lower headgroup charge density (i.e., longer spacers between charged amines). However, the most important factor appeared to be the ability of a lipidoid to self-assemble into an inverse hexagonal liquid crystalline phase, as observed by small-angle X-ray scattering (SAXS) analysis. The lipidoids active at lowest concentrations, which induced the most significant membrane damage during propidium iodide (PI) permeabilization assays, were those that aggregated into highly curved inverse hexagonal liquid crystal phases. These observations suggest that the introduction of strong curvature stress into the membrane is one way to maximize membrane disruption and lipidoid antimicrobial activity. Lipidoids that demonstrated the ability to furnish this phase consisted of either (i) branched or linear headgroups with shorter linear tails or (ii) cyclic headgroups with 4 bulky nonlinear tails. On the contrary, lipidoids previously observed to adopt disc-like conformations that pack into bicontinuous cubic phases were significantly less effective against B. subtilis. The discovery of these structure-property relationships demonstrates that it is not simply a balance of hydrophobic and hydrophilic moieties that govern membrane-active antibacterial activity, but also their intrinsic curvature and collective behavior.
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Affiliation(s)
- James Jennings
- Institute
of Molecular Biosciences, University of
Graz, NAWI Graz, 8010 Graz, Austria
- Field
of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Dunja Ašćerić
- Institute
of Molecular Biosciences, University of
Graz, NAWI Graz, 8010 Graz, Austria
- Field
of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Enrico Federico Semeraro
- Institute
of Molecular Biosciences, University of
Graz, NAWI Graz, 8010 Graz, Austria
- Field
of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Karl Lohner
- Institute
of Molecular Biosciences, University of
Graz, NAWI Graz, 8010 Graz, Austria
- Field
of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Nermina Malanovic
- Institute
of Molecular Biosciences, University of
Graz, NAWI Graz, 8010 Graz, Austria
- Field
of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Georg Pabst
- Institute
of Molecular Biosciences, University of
Graz, NAWI Graz, 8010 Graz, Austria
- Field
of Excellence BioHealth, University of Graz, 8010 Graz, Austria
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6
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Jennings J, Ašćerić D, Malanovic N, Pabst G. Structure-Activity Relationships of Cationic Lipidoids against Escherichia coli. Antibiotics (Basel) 2023; 12:1300. [PMID: 37627720 PMCID: PMC10451255 DOI: 10.3390/antibiotics12081300] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/02/2023] [Accepted: 08/05/2023] [Indexed: 08/27/2023] Open
Abstract
Membrane-active molecules provide a promising strategy to target and kill pathogenic bacteria. Understanding how specific molecular features drive interactions with membrane components and subsequently cause disruption that leads to antimicrobial activity is a crucial step in designing next-generation treatments. Here, we test a library of lipid-like compounds (lipidoids) against Gram-negative bacteria Escherichia coli to garner in-depth structure-activity relationships using antimicrobial assays. Modular lipidoid molecules were synthesized in high-throughput, such that we could analyze 104 compounds with variable combinations of hydrophobic tails and cationic headgroups. Antibacterial activity was strongly correlated to specific structural features, including tail hydrophobicity and headgroup charge density, and also to the overall molecular shape and propensity for self-assembly into curved liquid crystalline phases. Dye permeabilization assays showed that E. coli membranes were permeabilized by lipidoids, confirming their membrane-active nature. The reduced permeabilization, as compared to Gram-positive Bacillus subtilis, alludes to the challenge of permeabilizing the additional outer membrane layer of E. coli. The effect of headgroup solubility in gemini-type lipidoids was also demonstrated, revealing that a headgroup with a more hydrophilic spacer between amine groups had enhanced activity against B. subtilis but not E. coli. This provides insight into features enabling outer membrane penetration and governing selectivity between bacterial species.
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Affiliation(s)
- James Jennings
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Dunja Ašćerić
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria
| | - Nermina Malanovic
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Georg Pabst
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
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Angerer N, Piller P, Semeraro EF, Keller S, Pabst G. Interaction of detergent with complex mimics of bacterial membranes. Biophys Chem 2023; 296:107002. [PMID: 36921495 DOI: 10.1016/j.bpc.2023.107002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/02/2023] [Accepted: 03/02/2023] [Indexed: 03/18/2023]
Abstract
Detergents are valuable tools to extract membrane proteins for biophysical, biochemical, and structural scrutiny. The detergent-driven solubilization of bilayers made from a single lipid species is commonly described in terms of pseudo-phase diagrams and a three-stage model accounting for three ranges comprising (i) intact vesicles, (ii) vesicle/micelle co-existence, or (iii) mixed micelles. Moreover, the pseudo-phase boundaries thus determined can often be quantitatively rationalized in terms of the molecular shapes of the lipid and the detergent used. Yet, it has remained unclear to what extent this approach can be applied to multi-component lipid membranes that more closely mimic the compositional complexity of cellular membranes. Here, we studied how lipid mixtures composed of palmitoyl oleoyl phosphatidylethanolamine (POPE), palmitoyl oleoyl phosphatidylglycerol (POPG), and tetraoleoyl cardiolipin (TOCL) are solubilized by the commonly used zwitterionic detergent lauryldimethylamine N-oxide using isothermal titration calorimetry. While phase diagrams of the diverse lipid mixtures showed the typical ranges of the three-stage model, we found that POPG-rich POPE/POPG bilayers are more difficult to solubilize than POPG-poor POPE/POPG bilayers. In turn, POPE/POPG/TOCL bilayers became increasingly resistant to detergent with increasing TOCL content. Since POPG is nearly cylindrically shaped and TOCL adopts inverted cone-like shapes under current buffer conditions, our solubilization data do not align with shape-based arguments. Instead, additional electrostatic interactions between lipids and detergents lead to non-additive mixing behavior affecting the resilience of complex lipid bilayers against solubilization.
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Affiliation(s)
- Nadine Angerer
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Humboldtstr. 50/III, Graz 8010, Austria; BioTechMed Graz, Graz, Austria; Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Paulina Piller
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Humboldtstr. 50/III, Graz 8010, Austria; BioTechMed Graz, Graz, Austria; Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Enrico F Semeraro
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Humboldtstr. 50/III, Graz 8010, Austria; BioTechMed Graz, Graz, Austria; Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Sandro Keller
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Humboldtstr. 50/III, Graz 8010, Austria; BioTechMed Graz, Graz, Austria; Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Georg Pabst
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Humboldtstr. 50/III, Graz 8010, Austria; BioTechMed Graz, Graz, Austria; Field of Excellence BioHealth - University of Graz, Graz, Austria.
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8
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Piller P, Semeraro EF, Rechberger GN, Keller S, Pabst G. Allosteric modulation of integral protein activity by differential stress in asymmetric membranes. PNAS Nexus 2023; 2:pgad126. [PMID: 37143864 PMCID: PMC10153742 DOI: 10.1093/pnasnexus/pgad126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 03/07/2023] [Accepted: 04/06/2023] [Indexed: 05/06/2023]
Abstract
The activity of integral membrane proteins is tightly coupled to the properties of the surrounding lipid matrix. In particular, transbilayer asymmetry, a hallmark of all plasma membranes, might be exploited to control membrane-protein activity. Here, we hypothesized that the membrane-embedded enzyme outer membrane phospholipase A (OmpLA) is susceptible to the lateral pressure differences that build up between such asymmetric membrane leaflets. Upon reconstituting OmpLA into synthetic, chemically well-defined phospholipid bilayers exhibiting different lateral pressure profiles, we indeed observed a substantial decrease in the enzyme's hydrolytic activity with increasing membrane asymmetry. No such effects were observed in symmetric mixtures of the same lipids. To quantitatively rationalize how the differential stress in asymmetric lipid bilayers inhibits OmpLA, we developed a simple allosteric model within the lateral pressure framework. Thus, we find that membrane asymmetry can serve as the dominant factor in controlling membrane-protein activity, even in the absence of specific, chemical cues or other physical membrane determinants such as hydrophobic mismatch.
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Affiliation(s)
- Paulina Piller
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz 8010, Austria
- BioTechMed Graz, Graz 8010, Austria
- Field of Excellence BioHealth—University of Graz, Graz 8010, Austria
| | - Enrico F Semeraro
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz 8010, Austria
- BioTechMed Graz, Graz 8010, Austria
- Field of Excellence BioHealth—University of Graz, Graz 8010, Austria
| | - Gerald N Rechberger
- Field of Excellence BioHealth—University of Graz, Graz 8010, Austria
- Biochemistry, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz 8010, Austria
- Omics Center Graz, BioTechMed Graz, Graz 8010, Austria
| | - Sandro Keller
- Biophysics, Institute of Molecular Bioscience (IMB), NAWI Graz, University of Graz, Graz 8010, Austria
- BioTechMed Graz, Graz 8010, Austria
- Field of Excellence BioHealth—University of Graz, Graz 8010, Austria
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9
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Frewein MP, Piller P, Semeraro EF, Czakkel O, Gerelli Y, Porcar L, Pabst G. Distributing Aminophospholipids Asymmetrically Across Leaflets Causes Anomalous Membrane Stiffening. Biophys J 2023:S0006-3495(23)00296-5. [PMID: 37120716 DOI: 10.1016/j.bpj.2023.04.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 03/10/2023] [Accepted: 04/25/2023] [Indexed: 05/01/2023] Open
Abstract
We studied the mechanical leaflet coupling of prototypic mammalian plasma membranes using neutron spin-echo spectroscopy. In particular, we examined a series of asymmetric phospholipid vesicles with phosphatidylcholine and sphingomyelin enriched in the outer leaflet and inner leaflets composed of phosphatidylethanolamine / phosphatidylserine mixtures. The bending rigidities of most asymmetric membranes were anomalously high, exceeding even those of symmetric membranes formed from their cognate leaflets. Only asymmetric vesicles with outer leaflets enriched in sphingolipid displayed bending rigidities in conformity with these symmetric controls. We performed complementary small-angle neutron and X-ray experiments on the same vesicles to examine possible links to structural coupling mechanisms, which would show up in corresponding changes in membrane thickness. Additionally, we estimated differential stress between leaflets originating either from a mismatch of their lateral areas or spontaneous curvatures. However, no correlation with asymmetry-induced membrane stiffening was observed. To reconcile our findings, we speculate that an asymmetric distribution charged or H-bond forming lipids may induce an intraleaflet coupling which increases the weight of hard undulatory modes of membrane fluctuations and hence the overall membrane stiffness.
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Affiliation(s)
- Moritz Pk Frewein
- Biophysics, Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria; Institut Laue-Langevin, 38042 Grenoble, France; BioTechMed Graz, 8010 Graz, Austria; Field of Excellence BioHealth, 8010 Graz, Austria
| | - Paulina Piller
- Biophysics, Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria; Field of Excellence BioHealth, 8010 Graz, Austria
| | - Enrico F Semeraro
- Biophysics, Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria; Field of Excellence BioHealth, 8010 Graz, Austria
| | | | - Yuri Gerelli
- CNR Institute for Complex Systems, Uos Sapienza, Piazzale Aldo Moro 2, 00185 Roma, Italy; Department of Physics, Sapienza University of Rome, Piazzale Aldo Moro 2, 00185 Roma, Italy
| | | | - Georg Pabst
- Biophysics, Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria; Field of Excellence BioHealth, 8010 Graz, Austria.
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10
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Jennings J, Pabst G. Multiple Routes to Bicontinuous Cubic Liquid Crystal Phases Discovered by High-Throughput Self-Assembly Screening of Multi-Tail Lipidoids. Small 2023:e2206747. [PMID: 37026678 DOI: 10.1002/smll.202206747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 03/16/2023] [Indexed: 06/19/2023]
Abstract
Bicontinuous cubic phases offer advantageous routes to a broad range of applied materials ranging from drug delivery devices to membranes. However, a priori design of molecules that assemble into these phases remains a technological challenge. In this article, a high-throughput synthesis of lipidoids that undergo protonation-driven self-assembly (PrSA) into liquid crystalline (LC) phases is conducted. With this screening approach, 12 different multi-tail lipidoid structures capable of assembling into the bicontinuous double gyroid phase are discovered. The large volume of small-angle X-ray scattering (SAXS) data uncovers unexpected design criteria that enable phase selection as a function of lipidoid headgroup size and architecture, tail length and architecture, and counterion identity. Surprisingly, combining branched headgroups with bulky tails forces lipidoids to adopt unconventional pseudo-disc conformations that pack into double gyroid networks, entirely distinct from other synthetic or biological amphiphiles within bicontinuous cubic phases. From a multitude of possible applications, two examples of functional materials from lipidoid liquid crystals are demonstrated. First, the fabrication of gyroid nanostructured films by interfacial PrSA, which are rapidly responsive to the external medium. Second, it is shown that colloidally-dispersed lipidoid cubosomes, for example, for drug delivery, are easily assembled using top-down solvent evaporation methods.
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Affiliation(s)
- James Jennings
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, Graz, 8010, Austria
- Field of Excellence BioHealth, University of Graz, Graz, 8010, Austria
| | - Georg Pabst
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, Graz, 8010, Austria
- Field of Excellence BioHealth, University of Graz, Graz, 8010, Austria
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11
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Porcar L, Frewein M, Pabst G, Perez-Salas UA. Determination of water permeability through stress-free lipid membranes using time-resolved small angle neutron scattering. Biophys J 2023; 122:366a. [PMID: 36783860 DOI: 10.1016/j.bpj.2022.11.2019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
| | - Moritz Frewein
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Georg Pabst
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
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12
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Semeraro EF, Pajtinka P, Marx L, Kabelka I, Leber R, Lohner K, Vácha R, Pabst G. Magainin 2 and PGLa in bacterial membrane mimics IV: Membrane curvature and partitioning. Biophys J 2022; 121:4689-4701. [PMID: 36258677 PMCID: PMC9748257 DOI: 10.1016/j.bpj.2022.10.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Revised: 10/10/2022] [Accepted: 10/12/2022] [Indexed: 12/15/2022] Open
Abstract
We previously reported that the synergistically enhanced antimicrobial activity of magainin 2 (MG2a) and PGLa is related to membrane adhesion and fusion. Here, we demonstrate that equimolar mixtures of MG2a and L18W-PGLa induce positive monolayer curvature stress and sense, at the same time, positive mean and Gaussian bilayer curvatures already at low amounts of bound peptide. The combination of both abilities-membrane curvature sensing and inducing-is most likely the base for the synergistically enhanced peptide activity. In addition, our coarse-grained simulations suggest that fusion stalks are promoted by decreasing the free-energy barrier for their formation rather than by stabilizing their shape. We also interrogated peptide partitioning as a function of lipid and peptide concentration using tryptophan fluorescence spectroscopy and peptide-induced leakage of dyes from lipid vesicles. In agreement with a previous report, we find increased membrane partitioning of L18W-PGLa in the presence of MG2a. However, this effect does not prevail to lipid concentrations higher than 1 mM, above which all peptides associate with the lipid bilayers. This implies that synergistic effects of MG2a and L18W-PGLa in previously reported experiments with lipid concentrations >1 mM are due to peptide-induced membrane remodeling and not their specific membrane partitioning.
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Affiliation(s)
- Enrico F Semeraro
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Peter Pajtinka
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic; Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Lisa Marx
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Ivo Kabelka
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Regina Leber
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Karl Lohner
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Robert Vácha
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic; Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic.
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria.
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13
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Mukhina T, Pabst G, Ruysschaert JM, Brezesinski G, Schneck E. pH-Dependent physicochemical properties of ornithine lipid in mono- and bilayers. Phys Chem Chem Phys 2022; 24:22778-22791. [PMID: 36111816 DOI: 10.1039/d2cp01045c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In certain bacteria, phosphatidylethanolamine lipids (PEL) get largely replaced by phosphate-free ornithine lipids (OL) under conditions of phosphate starvation. It has so far been unknown how much these two lipid types deviate in their physicochemical properties, and how strongly bacteria thus have to adapt in order to compensate for the difference. Here, we use differential scanning calorimetry, X-ray scattering, and X-ray fluorescence to investigate the properties of OL with saturated C14 alkyl chains in mono- and bilayers. OL is found to have a greater tendency than chain-analogous PEL to form ordered structures and, in contrast to PEL, even a molecular superlattice based on a hydrogen bonding network between the headgroups. This superlattice is virtually electrically uncharged and persists over a wide pH range. Our results indicate that OL and PEL behave very differently in ordered single-component membranes but may behave more similarly in fluid multicomponent membranes.
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Affiliation(s)
- Tetiana Mukhina
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrase 8, 64289 Darmstadt, Germany.
| | - Georg Pabst
- Insitute of Molecular Biosciences, University of Graz, Universitätsplatz 3, 8010, Graz, Austria
| | - Jean-Marie Ruysschaert
- Laboratoire de Structure et Fonction des Membranes Biologiques, Université Libre de Bruxelles, 1050 Bruxelles, Belgium
| | - Gerald Brezesinski
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrase 8, 64289 Darmstadt, Germany.
| | - Emanuel Schneck
- Institute for Condensed Matter Physics, TU Darmstadt, Hochschulstrase 8, 64289 Darmstadt, Germany.
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14
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DiPasquale M, Nguyen MHL, Pabst G, Marquardt D. Partial Volumes of Phosphatidylcholines and Vitamin E: α-Tocopherol Prefers Disordered Membranes. J Phys Chem B 2022; 126:6691-6699. [PMID: 36027485 DOI: 10.1021/acs.jpcb.2c04209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Despite its discovery over 95 years ago, the biological and nutritional roles of vitamin E remain subjects of much controversy. Though it is known to possess antioxidant properties, recent assertions have implied that vitamin E may not be limited to this function in living systems. Through densitometry measurements and small-angle X-ray scattering we observe favorable interactions between α-tocopherol and unsaturated phospholipids, with more favorable interactions correlating to an increase in lipid chain unsaturation. Our data provide evidence that vitamin E may preferentially associate with oxygen sensitive lipids─an association that is considered innate for a viable membrane antioxidant.
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Affiliation(s)
- Mitchell DiPasquale
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Michael H L Nguyen
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada
| | - Georg Pabst
- Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Graz 8010, Austria.,BioTechMed-Graz, Graz 8010, Austria
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario N9B 3P4, Canada.,Department of Physics, University of Windsor, Windsor, Ontario N9B 3P4, Canada
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15
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Frewein MPK, Piller P, Semeraro EF, Batchu KC, Heberle FA, Scott HL, Gerelli Y, Porcar L, Pabst G. Interdigitation-Induced Order and Disorder in Asymmetric Membranes. J Membr Biol 2022; 255:407-421. [PMID: 35471665 PMCID: PMC9581838 DOI: 10.1007/s00232-022-00234-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 03/26/2022] [Indexed: 12/31/2022]
Abstract
We studied the transleaflet coupling of compositionally asymmetric liposomes in the fluid phase. The vesicles were produced by cyclodextrin-mediated lipid exchange and contained dipalmitoyl phosphatidylcholine (DPPC) in the inner leaflet and different mixed-chain phosphatidylcholines (PCs) as well as milk sphingomyelin (MSM) in the outer leaflet. In order to jointly analyze the obtained small-angle neutron and X-ray scattering data, we adapted existing models of trans-bilayer structures to measure the overlap of the hydrocarbon chain termini by exploiting the contrast of the terminal methyl ends in X-ray scattering. In all studied systems, the bilayer-asymmetry has large effects on the lipid packing density. Fully saturated mixed-chain PCs interdigitate into the DPPC-containing leaflet and evoke disorder in one or both leaflets. The long saturated acyl chains of MSM penetrate even deeper into the opposing leaflet, which in turn has an ordering effect on the whole bilayer. These results are qualitatively understood in terms of a balance of entropic repulsion of fluctuating hydrocarbon chain termini and van der Waals forces, which is modulated by the interdigitation depth. Monounsaturated PCs in the outer leaflet also induce disorder in DPPC despite vestigial or even absent interdigitation. Instead, the transleaflet coupling appears to emerge here from a matching of the inner leaflet lipids to the larger lateral lipid area of the outer leaflet lipids.
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Affiliation(s)
- Moritz P K Frewein
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010, Graz, Austria.,Institut Laue-Langevin, 38042, Grenoble, France.,BioTechMed Graz, 8010, Graz, Austria.,Field of Excellence BioHealth, 8010, Graz, Austria
| | - Paulina Piller
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010, Graz, Austria.,BioTechMed Graz, 8010, Graz, Austria.,Field of Excellence BioHealth, 8010, Graz, Austria
| | - Enrico F Semeraro
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010, Graz, Austria.,BioTechMed Graz, 8010, Graz, Austria.,Field of Excellence BioHealth, 8010, Graz, Austria
| | | | | | - Haden L Scott
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN, 37996, USA.,Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Yuri Gerelli
- Department of Life and Environmental Sciences, Università Politecnica delle Marche, 60131, Ancona, Italy
| | | | - Georg Pabst
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010, Graz, Austria. .,BioTechMed Graz, 8010, Graz, Austria. .,Field of Excellence BioHealth, 8010, Graz, Austria.
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16
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Kabelka I, Georgiev V, Marx L, Pajtinka P, Lohner K, Pabst G, Dimova R, Vácha R. Magainin 2 and PGLa in bacterial membrane mimics III: Membrane fusion and disruption. Biophys J 2022; 121:852-861. [PMID: 35134334 PMCID: PMC8943694 DOI: 10.1016/j.bpj.2021.12.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/27/2021] [Accepted: 12/22/2021] [Indexed: 11/30/2022] Open
Abstract
We previously speculated that the synergistically enhanced antimicrobial activity of Magainin 2 and PGLa is related to membrane adhesion, fusion, and further membrane remodeling. Here we combined computer simulations with time-resolved in vitro fluorescence microscopy, cryoelectron microscopy, and small-angle X-ray scattering to interrogate such morphological and topological changes of vesicles at nanoscopic and microscopic length scales in real time. Coarse-grained simulations revealed formation of an elongated and bent fusion zone between vesicles in the presence of equimolar peptide mixtures. Vesicle adhesion and fusion were observed to occur within a few seconds by cryoelectron microscopy and corroborated by small-angle X-ray scattering measurements. The latter experiments indicated continued and time-extended structural remodeling for individual peptides or chemically linked peptide heterodimers but with different kinetics. Fluorescence microscopy further captured peptide-dependent adhesion, fusion, and occasional bursting of giant unilamellar vesicles a few seconds after peptide addition. The synergistic interactions between the peptides shorten the time response of vesicles and enhance membrane fusogenic and disruption properties of the equimolar mixture compared with the individual peptides.
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Affiliation(s)
- Ivo Kabelka
- CEITEC – Central European Institute of Technology, Masaryk University, Brno, Czech Republic,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Vasil Georgiev
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - Lisa Marx
- Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Graz, Austria,BioTechMed Graz, Graz, Austria
| | - Peter Pajtinka
- CEITEC – Central European Institute of Technology, Masaryk University, Brno, Czech Republic,National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic,Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Karl Lohner
- Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Graz, Austria,BioTechMed Graz, Graz, Austria
| | - Georg Pabst
- Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, Graz, Austria,BioTechMed Graz, Graz, Austria
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, Potsdam, Germany
| | - Robert Vácha
- CEITEC - Central European Institute of Technology, Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic; Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic.
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17
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Semeraro EF, Marx L, Mandl J, Letofsky-Papst I, Mayrhofer C, Frewein MPK, Scott HL, Prévost S, Bergler H, Lohner K, Pabst G. Lactoferricins impair the cytosolic membrane of Escherichia coli within a few seconds and accumulate inside the cell. eLife 2022; 11:72850. [PMID: 35670565 PMCID: PMC9352351 DOI: 10.7554/elife.72850] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 06/06/2022] [Indexed: 12/29/2022] Open
Abstract
We report the real-time response of Escherichia coli to lactoferricin-derived antimicrobial peptides (AMPs) on length scales bridging microscopic cell sizes to nanoscopic lipid packing using millisecond time-resolved synchrotron small-angle X-ray scattering. Coupling a multiscale scattering data analysis to biophysical assays for peptide partitioning revealed that the AMPs rapidly permeabilize the cytosolic membrane within less than 3 s-much faster than previously considered. Final intracellular AMP concentrations of ∼80-100 mM suggest an efficient obstruction of physiologically important processes as the primary cause of bacterial killing. On the other hand, damage of the cell envelope and leakage occurred also at sublethal peptide concentrations, thus emerging as a collateral effect of AMP activity that does not kill the bacteria. This implies that the impairment of the membrane barrier is a necessary but not sufficient condition for microbial killing by lactoferricins. The most efficient AMP studied exceeds others in both speed of permeabilizing membranes and lowest intracellular peptide concentration needed to inhibit bacterial growth.
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Affiliation(s)
- Enrico F Semeraro
- University of Graz, Institute of Molecular Biosciences, NAWI GrazGrazAustria,BioTechMed GrazGrazAustria,Field of Excellence BioHealth – University of GrazGrazAustria
| | - Lisa Marx
- University of Graz, Institute of Molecular Biosciences, NAWI GrazGrazAustria,BioTechMed GrazGrazAustria,Field of Excellence BioHealth – University of GrazGrazAustria
| | - Johannes Mandl
- University of Graz, Institute of Molecular Biosciences, NAWI GrazGrazAustria,BioTechMed GrazGrazAustria,Field of Excellence BioHealth – University of GrazGrazAustria
| | - Ilse Letofsky-Papst
- Institute of Electron Microscopy and Nanoanalysis and Center for Electron Microscopy, Graz University of Technology, NAWI GrazGrazAustria
| | | | - Moritz PK Frewein
- University of Graz, Institute of Molecular Biosciences, NAWI GrazGrazAustria,BioTechMed GrazGrazAustria,Field of Excellence BioHealth – University of GrazGrazAustria,Institut Laue-LangevinGrenobleFrance
| | - Haden L Scott
- Center for Environmental Biotechnology, University of TennesseeKnoxvilleUnited States,Shull Wollan Center, Oak Ridge National LaboratoryOak RidgeUnited States
| | | | - Helmut Bergler
- University of Graz, Institute of Molecular Biosciences, NAWI GrazGrazAustria,BioTechMed GrazGrazAustria,Field of Excellence BioHealth – University of GrazGrazAustria
| | - Karl Lohner
- University of Graz, Institute of Molecular Biosciences, NAWI GrazGrazAustria,BioTechMed GrazGrazAustria,Field of Excellence BioHealth – University of GrazGrazAustria
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, NAWI GrazGrazAustria,BioTechMed GrazGrazAustria,Field of Excellence BioHealth – University of GrazGrazAustria
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18
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Aguilar M, Al Nahas K, Barrera F, Bassereau P, Bastos M, Beales P, Bechinger B, Bonev B, Brand I, Chattopadhyay A, Clarke RJ, DeGrado W, Deplazes E, Garcia Saez AJ, Hoogenboom B, Lund R, Milán Rodríguez P, O'Shea P, Pabst G, Pal S, Roux A, Sanderson J, Semeraro EF, Sengupta D, Siegel DP, van 't Hag L, Vijayakumar A, Zoranić L. Theoretical and experimental studies of complex peptide-membrane systems: general discussion. Faraday Discuss 2021; 232:256-281. [PMID: 34909814 DOI: 10.1039/d1fd90066h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Aguilar M, Bassereau P, Bastos M, Beales P, Bechinger B, Bonev B, Brand I, Chalouhi E, Clarke RJ, Deplazes E, Fraternali F, Fuchs P, Hoogenboom B, Lund R, Mahmoudi N, Milán Rodríguez P, O'Shea P, Pabst G, Pal S, Rice A, Sanderson J, Seddon J, Sengupta D, Siegel DP, Srivastava A, Utterström J, Vácha R, van 't Hag L, Vijayakumar A, Zoranić L. Peptide-membrane interactions and biotechnology; enabling next-generation synthetic biology: general discussion. Faraday Discuss 2021; 232:463-481. [PMID: 34909808 DOI: 10.1039/d1fd90068d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Aguilar MI, Al Nahas K, Barrera FN, Bassereau P, Bechinger B, Brand I, Chattopadhyay A, Clarke RJ, DeGrado WF, Deplazes E, Fletcher M, Fraternali F, Fuchs P, Garcia-Saez AJ, Gilbert R, Hoogenboom BW, Jarin Z, O'Shea P, Pabst G, Pal S, Sanderson JM, Seddon JM, Sengupta D, Siegel DP, Srivastava A, Tieleman DP, Tripathy M, Utterström J, Vácha R, Vanni S, Voth GA. Theoretical and experimental comparisons of simple peptide-membrane systems; towards defining the reaction space: general discussion. Faraday Discuss 2021; 232:149-171. [PMID: 34908093 DOI: 10.1039/d1fd90065j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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21
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Aguilar M, Al Nahas K, Barrera F, Bassereau P, Bastos M, Beales P, Bechinger B, Bonev B, Brand I, Chattopadhyay A, DeGrado W, Fuchs P, Garcia Saez AJ, Hoogenboom B, Kapoor S, Milán Rodríguez P, Molloy J, O'Shea P, Pabst G, Pal S, Rice A, Roux A, Sanderson J, Seddon J, Tamm LK, Vijayakumar A. Behaviour and interactions of proteins and peptides with and within membranes; from simple models to cellular membranes: general discussion. Faraday Discuss 2021; 232:375-398. [PMID: 34909817 DOI: 10.1039/d1fd90067f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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22
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Marx L, Frewein MPK, Semeraro EF, Rechberger GN, Lohner K, Porcar L, Pabst G. Antimicrobial peptide activity in asymmetric bacterial membrane mimics. Faraday Discuss 2021; 232:435-447. [PMID: 34532723 PMCID: PMC8704130 DOI: 10.1039/d1fd00039j] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 07/21/2021] [Indexed: 11/21/2022]
Abstract
We report on the response of asymmetric lipid membranes composed of palmitoyl oleoyl phosphatidylethanolamine and palmitoyl oleoyl phosphatidylglycerol, to interactions with the frog peptides L18W-PGLa and magainin 2 (MG2a), as well as the lactoferricin derivative LF11-215. In particular we determined the peptide-induced lipid flip-flop, as well as membrane partitioning of L18W-PGLa and LF11-215, and vesicle dye-leakage induced by L18W-PGLa. The ability of L18W-PGLa and MG2a to translocate through the membrane appears to correlate with the observed lipid flip-flop, which occurred at the fastest rate for L18W-PGLa. The higher structural flexibility of LF11-215 in turn allows this peptide to insert into the bilayers without detectable changes of membrane asymmetry. The increased vulnerability of asymmetric membranes to L18W-PGLa in terms of permeability, appears to be a consequence of tension differences between the compositionally distinct leaflets, but not due to increased peptide partitioning.
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Affiliation(s)
- Lisa Marx
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.
- Field of Excellence BioHealth, University of Graz, Graz, Austria
| | - Moritz P K Frewein
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.
- Field of Excellence BioHealth, University of Graz, Graz, Austria
- Institut Laue-Langevin, 38043 Grenoble, France
| | - Enrico F Semeraro
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.
- Field of Excellence BioHealth, University of Graz, Graz, Austria
| | - Gerald N Rechberger
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.
- Field of Excellence BioHealth, University of Graz, Graz, Austria
| | - Karl Lohner
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.
- Field of Excellence BioHealth, University of Graz, Graz, Austria
| | | | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.
- Field of Excellence BioHealth, University of Graz, Graz, Austria
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23
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Schönfeldová T, Piller P, Kovacik F, Pabst G, Okur HI, Roke S. Lipid Melting Transitions Involve Structural Redistribution of Interfacial Water. J Phys Chem B 2021; 125:12457-12465. [PMID: 34730965 PMCID: PMC8607985 DOI: 10.1021/acs.jpcb.1c06868] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2021] [Revised: 10/15/2021] [Indexed: 11/29/2022]
Abstract
Morphological and gel-to-liquid phase transitions of lipid membranes are generally considered to primarily depend on the structural motifs in the hydrophobic core of the bilayer. Structural changes in the aqueous headgroup phase are typically not considered, primarily because they are difficult to quantify. Here, we investigate structural changes of the hydration shells around large unilamellar vesicles (LUVs) in aqueous solution, using differential scanning calorimetry (DSC), and temperature-dependent ζ-potential and high-throughput angle-resolved second harmonic scattering measurements (AR-SHS). Varying the lipid composition from 1,2-dimyristoyl-sn-glycero-3-phosphocholine(DMPC) to 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA), to 1,2-dimyristoyl-sn-glycero-3-phospho-l-serine (DMPS), we observe surprisingly distinct behavior for the different systems that depend on the chemical composition of the hydrated headgroups. These differences involve changes in hydration following temperature-induced counterion redistribution, or changes in hydration following headgroup reorientation and Stern layer compression.
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Affiliation(s)
- Tereza Schönfeldová
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), Institute of Materials
Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale
de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Paulina Piller
- Institute
of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstrasse 50/III, Graz 8010, Austria
| | - Filip Kovacik
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), Institute of Materials
Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale
de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Georg Pabst
- Institute
of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Humboldtstrasse 50/III, Graz 8010, Austria
| | - Halil I. Okur
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), Institute of Materials
Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale
de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Department
of Chemistry and National Nanotechnology Research Center (UNAM), Bilkent University, 06800 Ankara, Turkey
| | - Sylvie Roke
- Laboratory
for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), Institute of Materials
Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale
de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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24
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Pfeffermann J, Eicher B, Boytsov D, Hannesschlaeger C, Galimzyanov TR, Glasnov TN, Pabst G, Akimov SA, Pohl P. Photoswitching of model ion channels in lipid bilayers. J Photochem Photobiol B 2021; 224:112320. [PMID: 34600201 DOI: 10.1016/j.jphotobiol.2021.112320] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/27/2021] [Accepted: 09/20/2021] [Indexed: 11/19/2022]
Abstract
Membrane proteins can be regulated by alterations in material properties intrinsic to the hosting lipid bilayer. Here, we investigated whether the reversible photoisomerization of bilayer-embedded diacylglycerols (OptoDArG) with two azobenzene-containing acyl chains may trigger such regulatory events. We observed an augmented open probability of the mechanosensitive model channel gramicidin A (gA) upon photoisomerizing OptoDArG's acyl chains from trans to cis: integral planar bilayer conductance brought forth by hundreds of simultaneously conducting gA dimers increased by typically >50% - in good agreement with the observed increase in single-channel lifetime. Further, (i) increments in the electrical capacitance of planar lipid bilayers and protrusion length of aspirated giant unilamellar vesicles into suction pipettes, as well as (ii) changes of small-angle X-ray scattering of multilamellar vesicles indicated that spontaneous curvature, hydrophobic thickness, and bending elasticity decreased upon switching from trans- to cis-OptoDArG. Our bilayer elasticity model for gA supports the causal relationship between changes in gA activity and bilayer material properties upon photoisomerization. Thus, we conclude that photolipids are deployable for converting bilayers of potentially diverse origins into light-gated actuators for mechanosensitive proteins.
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Affiliation(s)
- Juergen Pfeffermann
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, Linz 4020, Austria
| | - Barbara Eicher
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed Graz, Austria
| | - Danila Boytsov
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, Linz 4020, Austria
| | | | - Timur R Galimzyanov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy prospekt, Moscow 119071, Russia
| | - Toma N Glasnov
- University of Graz, Institute of Chemistry, NAWI Graz, Graz, Austria
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, Graz, Austria; BioTechMed Graz, Austria
| | - Sergey A Akimov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy prospekt, Moscow 119071, Russia
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, Linz 4020, Austria.
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25
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Frewein MPK, Doktorova M, Heberle FA, Scott HL, Semeraro EF, Porcar L, Pabst G. Structure and Interdigitation of Chain-Asymmetric Phosphatidylcholines and Milk Sphingomyelin in the Fluid Phase. Symmetry (Basel) 2021; 13. [PMID: 35530371 PMCID: PMC9075682 DOI: 10.3390/sym13081441] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
We addressed the frequent occurrence of mixed-chain lipids in biological membranes and their impact on membrane structure by studying several chain-asymmetric phosphatidylcholines and the highly asymmetric milk sphingomyelin. Specifically, we report trans-membrane structures of the corresponding fluid lamellar phases using small-angle X-ray and neutron scattering, which were jointly analyzed in terms of a membrane composition-specific model, including a headgroup hydration shell. Focusing on terminal methyl groups at the bilayer center, we found a linear relation between hydrocarbon chain length mismatch and the methyl-overlap for phosphatidylcholines, and a non-negligible impact of the glycerol backbone-tilting, letting the sn1-chain penetrate deeper into the opposing leaflet by half a CH2 group. That is, penetration-depth differences due to the ester-linked hydrocarbons at the glycerol backbone, previously reported for gel phase structures, also extend to the more relevant physiological fluid phase, but are significantly reduced. Moreover, milk sphingomyelin was found to follow the same linear relationship suggesting a similar tilt of the sphingosine backbone. Complementarily performed molecular dynamics simulations revealed that there is always a part of the lipid tails bending back, even if there is a high interdigitation with the opposing chains. The extent of this back-bending was similar to that in chain symmetric bilayers. For both cases of adaptation to chain length mismatch, chain-asymmetry has a large impact on hydrocarbon chain ordering, inducing disorder in the longer of the two hydrocarbons.
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Affiliation(s)
- Moritz P. K. Frewein
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria
- Institut Laue-Langevin, 38043 Grenoble, France
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | - Milka Doktorova
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22903, USA
| | - Frederick A. Heberle
- Department of Chemistry, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| | - Haden L. Scott
- Center for Environmental Biotechnology, University of Tennessee, Knoxville, TN 37996, USA
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Enrico F. Semeraro
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
| | | | - Georg Pabst
- Institute of Molecular Biosciences, University of Graz, NAWI Graz, 8010 Graz, Austria
- BioTechMed Graz, 8010 Graz, Austria
- Field of Excellence BioHealth, University of Graz, 8010 Graz, Austria
- Correspondence: ; Tel.: +43-316-380-4989
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26
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Kaltenegger M, Kremser J, Frewein MPK, Ziherl P, Bonthuis DJ, Pabst G. Intrinsic lipid curvatures of mammalian plasma membrane outer leaflet lipids and ceramides. Biochim Biophys Acta Biomembr 2021; 1863:183709. [PMID: 34332987 DOI: 10.1016/j.bbamem.2021.183709] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/16/2021] [Accepted: 07/20/2021] [Indexed: 01/26/2023]
Abstract
We developed a global X-ray data analysis method to determine the intrinsic curvatures of lipids hosted in inverted hexagonal phases. In particular, we combined compositional modelling with molecular shape-based arguments to account for non-linear mixing effects of guest-in-host lipids on intrinsic curvature. The technique was verified by all-atom molecular dynamics simulations and applied to sphingomyelin and a series of phosphatidylcholines and ceramides with differing composition of the hydrocarbon chains. We report positive lipid curvatures for sphingomyelin and all phosphatidylcholines with disaturated and monounsaturated hydrocarbons. Phosphatidylcholines with diunsaturated hydrocarbons in turn yielded intrinsic lipid curvatures with negative values. All ceramides, with chain lengths varying between C2:0 and C24:0, displayed significant negative lipid curvature values. Moreover, we report non-additive mixing for C2:0 ceramide and sphingomyelin. This suggests for sphingolipids that in addition to lipid headgroup and hydrocarbon chain volumes also lipid-specific interactions are important contributors to membrane curvature stress.
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Affiliation(s)
- Michael Kaltenegger
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria; Field of Excellence BioHealth, University of Graz, Graz, Austria
| | - Johannes Kremser
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria; Field of Excellence BioHealth, University of Graz, Graz, Austria
| | - Moritz P K Frewein
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria; Field of Excellence BioHealth, University of Graz, Graz, Austria; Institut Laue-Langevin, 38043 Grenoble, France
| | - Primož Ziherl
- Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia; Jožef Stefan Institute, Ljubljana, Slovenia
| | - Douwe J Bonthuis
- Graz University of Technology, Institute of Theoretical and Computational Physics, NAWI Graz, 8010 Graz, Austria
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria; BioTechMed Graz, 8010 Graz, Austria; Field of Excellence BioHealth, University of Graz, Graz, Austria.
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27
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Semeraro EF, Marx L, Mandl J, Frewein MPK, Scott HL, Prévost S, Bergler H, Lohner K, Pabst G. Evolution of the analytical scattering model of live Escherichia coli. J Appl Crystallogr 2021; 54:473-485. [PMID: 33953653 PMCID: PMC8056759 DOI: 10.1107/s1600576721000169] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 01/05/2021] [Indexed: 11/10/2022] Open
Abstract
A previously reported multi-scale model for (ultra-)small-angle X-ray (USAXS/SAXS) and (very) small-angle neutron scattering (VSANS/SANS) of live Escherichia coli was revised on the basis of compositional/metabolomic and ultrastructural constraints. The cellular body is modeled, as previously described, by an ellipsoid with multiple shells. However, scattering originating from flagella was replaced by a term accounting for the oligosaccharide cores of the lipopolysaccharide leaflet of the outer membrane including its cross-term with the cellular body. This was mainly motivated by (U)SAXS experiments showing indistinguishable scattering for bacteria in the presence and absence of flagella or fimbrae. The revised model succeeded in fitting USAXS/SAXS and differently contrasted VSANS/SANS data of E. coli ATCC 25922 over four orders of magnitude in length scale. Specifically, this approach provides detailed insight into structural features of the cellular envelope, including the distance of the inner and outer membranes, as well as the scattering length densities of all bacterial compartments. The model was also successfully applied to E. coli K12, used for the authors' original modeling, as well as for two other E. coli strains. Significant differences were detected between the different strains in terms of bacterial size, intermembrane distance and its positional fluctuations. These findings corroborate the general applicability of the approach outlined here to quantitatively study the effect of bactericidal compounds on ultrastructural features of Gram-negative bacteria without the need to resort to any invasive staining or labeling agents.
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Affiliation(s)
- Enrico F Semeraro
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Lisa Marx
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Johannes Mandl
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Moritz P K Frewein
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria.,Institut Laue-Langevin, 38043 Grenoble, France
| | - Haden L Scott
- University of Tennessee, Center for Environmental Biotechnology, Knoxville, Tennessee, USA
| | | | - Helmut Bergler
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Karl Lohner
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria.,Field of Excellence BioHealth - University of Graz, Graz, Austria
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28
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Marx L, Semeraro EF, Mandl J, Kremser J, Frewein MP, Malanovic N, Lohner K, Pabst G. Bridging the Antimicrobial Activity of Two Lactoferricin Derivatives in E. coli and Lipid-Only Membranes. Front Med Technol 2021; 3:625975. [PMID: 35047906 PMCID: PMC8757871 DOI: 10.3389/fmedt.2021.625975] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Accepted: 01/19/2021] [Indexed: 11/13/2022] Open
Abstract
We coupled the antimicrobial activity of two well-studied lactoferricin derivatives, LF11-215 and LF11-324, in Escherichia coli and different lipid-only mimics of its cytoplasmic membrane using a common thermodynamic framework for peptide partitioning. In particular, we combined an improved analysis of microdilution assays with ζ-potential measurements, which allowed us to discriminate between the maximum number of surface-adsorbed peptides and peptides fully partitioned into the bacteria. At the same time, we measured the partitioning of the peptides into vesicles composed of phosphatidylethanolamine (PE), phosphatidylgylcerol (PG), and cardiolipin (CL) mixtures using tryptophan fluorescence and determined their membrane activity using a dye leakage assay and small-angle X-ray scattering. We found that the vast majority of LF11-215 and LF11-324 readily enter inner bacterial compartments, whereas only 1-5% remain surface bound. We observed comparable membrane binding of both peptides in membrane mimics containing PE and different molar ratios of PG and CL. The peptides' activity caused a concentration-dependent dye leakage in all studied membrane mimics; however, it also led to the formation of large aggregates, part of which contained collapsed multibilayers with sandwiched peptides in the interstitial space between membranes. This effect was least pronounced in pure PG vesicles, requiring also the highest peptide concentration to induce membrane permeabilization. In PE-containing systems, we additionally observed an effective shielding of the fluorescent dyes from leakage even at highest peptide concentrations, suggesting a coupling of the peptide activity to vesicle fusion, being mediated by the intrinsic lipid curvatures of PE and CL. Our results thus show that LF11-215 and LF11-324 effectively target inner bacterial components, while the stored elastic stress makes membranes more vulnerable to peptide translocation.
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Affiliation(s)
- Lisa Marx
- Department of Biophysics, Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth—University of Graz, Graz, Austria
| | - Enrico F. Semeraro
- Department of Biophysics, Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth—University of Graz, Graz, Austria
| | - Johannes Mandl
- Department of Biophysics, Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth—University of Graz, Graz, Austria
| | - Johannes Kremser
- Department of Biophysics, Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth—University of Graz, Graz, Austria
| | - Moritz P. Frewein
- Department of Biophysics, Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth—University of Graz, Graz, Austria
- Soft Matter Science and Support Group, Institut Laue-Langevin, Grenoble, France
| | - Nermina Malanovic
- Department of Biophysics, Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth—University of Graz, Graz, Austria
| | - Karl Lohner
- Department of Biophysics, Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth—University of Graz, Graz, Austria
| | - Georg Pabst
- Department of Biophysics, Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth—University of Graz, Graz, Austria
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29
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Semeraro EF, Marx L, Frewein MPK, Pabst G. Increasing complexity in small-angle X-ray and neutron scattering experiments: from biological membrane mimics to live cells. Soft Matter 2021; 17:222-232. [PMID: 32104874 DOI: 10.1039/c9sm02352f] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Small-angle X-ray and neutron scattering are well-established, non-invasive experimental techniques to interrogate global structural properties of biological membrane mimicking systems under physiologically relevant conditions. Recent developments, both in bottom-up sample preparation techniques for increasingly complex model systems, and in data analysis techniques have opened the path toward addressing long standing issues of biological membrane remodelling processes. These efforts also include emerging quantitative scattering studies on live cells, thus enabling a bridging of molecular to cellular length scales. Here, we review recent progress in devising compositional models for joint small-angle X-ray and neutron scattering studies on diverse membrane mimics - with a specific focus on membrane structural coupling to amphiphatic peptides and integral proteins - and live Escherichia coli. In particular, we outline the present state-of-the-art in small-angle scattering methods applied to complex membrane systems, highlighting how increasing system complexity must be followed by an advance in compositional modelling and data-analysis tools.
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Affiliation(s)
- Enrico F Semeraro
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria. and BioTechMed Graz, 8010 Graz, Austria
| | - Lisa Marx
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria. and BioTechMed Graz, 8010 Graz, Austria
| | - Moritz P K Frewein
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria. and BioTechMed Graz, 8010 Graz, Austria and Institut Laue-Langevin, 38000 Grenoble, France
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria. and BioTechMed Graz, 8010 Graz, Austria
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30
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Malanovic N, Ön A, Pabst G, Zellner A, Lohner K. Octenidine: Novel insights into the detailed killing mechanism of Gram-negative bacteria at a cellular and molecular level. Int J Antimicrob Agents 2020; 56:106146. [DOI: 10.1016/j.ijantimicag.2020.106146] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 07/28/2020] [Accepted: 08/19/2020] [Indexed: 01/30/2023]
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31
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Malanovic N, Marx L, Blondelle SE, Pabst G, Semeraro EF. Experimental concepts for linking the biological activities of antimicrobial peptides to their molecular modes of action. Biochim Biophys Acta Biomembr 2020; 1862:183275. [PMID: 32173291 DOI: 10.1016/j.bbamem.2020.183275] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/09/2020] [Accepted: 03/10/2020] [Indexed: 02/07/2023]
Abstract
The search for novel compounds to combat multi-resistant bacterial infections includes exploring the potency of antimicrobial peptides and derivatives thereof. Complementary to high-throughput screening techniques, biophysical and biochemical studies of the biological activity of these compounds enable deep insight, which can be exploited in designing antimicrobial peptides with improved efficacy. This approach requires the combination of several techniques to study the effect of such peptides on both bacterial cells and simple mimics of their cell envelope, such as lipid-only vesicles. These efforts carry the challenge of bridging results across techniques and sample systems, including the proper choice of membrane mimics. This review describes some important concepts toward the development of potent antimicrobial peptides and how they translate to frequently applied experimental techniques, along with an outline of the biophysics pertaining to the killing mechanism of antimicrobial peptides.
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Affiliation(s)
- Nermina Malanovic
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, Graz, Austria.
| | - Lisa Marx
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, Graz, Austria
| | | | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, Graz, Austria
| | - Enrico F Semeraro
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, Graz, Austria
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32
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Marquardt D, Heberle FA, Pan J, Cheng X, Pabst G, Harroun TA, Kučerka N, Katsaras J. The structures of polyunsaturated lipid bilayers by joint refinement of neutron and X-ray scattering data. Chem Phys Lipids 2020; 229:104892. [PMID: 32061581 DOI: 10.1016/j.chemphyslip.2020.104892] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/18/2020] [Accepted: 02/10/2020] [Indexed: 11/29/2022]
Abstract
We present the detailed structural analysis of polyunsaturated fatty acid-containing phospholipids namely, 1-palmitoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (PDPC) and 1-stearoyl-2-docosahexaenoyl-sn-glycero-3-phosphocholine (SDPC). A newly developed molecular dynamics (MD) simulation parsing scheme for lipids containing fatty acids with multiple double bonds was implemented into the scattering density profile (SDP) model to simultaneously refine differently contrasted neutron and X-ray scattering data. SDP analyses of scattering data at 30 °C yielded lipid areas of 71.1 Å2 and 70.4 Å2 for PDPC and SDPC bilayers, respectively, and a model free analysis of PDPC at 30 °C resulted in a lipid area of 72 Å2. In addition to bilayer structural parameters, using area-constrained MD simulations we determined the area compressibility modulus, KA, to be 246.4 mN/m, a value similar to other neutral phospholipids.
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Affiliation(s)
- Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, Canada; Department of Physics, University of Windsor, Windsor, ON, Canada.
| | | | - Jianjun Pan
- Department of Physics, University of South Florida, Tampa, FL USA
| | - Xiaolin Cheng
- Division of Medicinal Chemistry and Pharmacognosy, The Ohio State University, Columbus, OH, USA
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, 8010 Graz, Austria
| | - Thad A Harroun
- Department of Physics, Brock University, St. Catharines, ON, Canada
| | - Norbert Kučerka
- Joint Institute for Nuclear Research, Frank Laboratory of Neutron Physics, Dubna, Russia and Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University in Bratislava, Slovakia
| | - John Katsaras
- Department of Physics, Brock University, St. Catharines, ON, Canada; The Bredesen Center, University of Tennessee, Knoxville, TN, USA; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Large Scale Structures Group, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA.
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33
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Semeraro EF, Mandl J, Marx L, Narayanan T, Prévost S, Bergler H, Lohner K, Pabst G. Antimicrobial Peptides Impair Bacteria Cell Structures within Seconds. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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34
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Pabst G. Asymmetric Lipid Bilayers: Insights from Leaflet-specific Structural Studies. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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35
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Frewein MP, Scott HL, Doktorova M, Heberle FA, Gerelli Y, Porcar L, Pabst G. Coupling of Leaflet Structure in Asymmetric Lipid Vesicles. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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36
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Marx L, Semeraro EF, Pabst G, Lohner K. Peptide Kinetics in Symmetric and Asymmetric Membrane Mimics of Gram-Negative Bacteria. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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37
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Castillo-Sanchez JC, Andersson JM, Eicher B, Batllori-Badia E, Galindo A, Pabst G, Cruz A, Roger K, Perez-Gil J. Structure of Lung Surfactant from Different Sources: A Small-Angle-X-Ray Scattering (SAXS) Study. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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38
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Eckhardt D, Schnur J, Steigenberger J, Kalie L, Massing U, Pabst G, Heerklotz HH. Eutectic Explains Function of Thermoresponsive Liposomes - Resolving the Lysolipid Paradox. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.1346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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39
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Kabelka I, Pachler M, Prévost S, Letofsky-Papst I, Lohner K, Pabst G, Vácha R. Magainin 2 and PGLa in Bacterial Membrane Mimics II: Membrane Fusion and Sponge Phase Formation. Biophys J 2019; 118:612-623. [PMID: 31952806 DOI: 10.1016/j.bpj.2019.12.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/06/2019] [Accepted: 12/16/2019] [Indexed: 12/23/2022] Open
Abstract
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 article of this series, 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 the 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.
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Affiliation(s)
- Ivo Kabelka
- CEITEC-Central European Institute of Technology, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Michael Pachler
- Biophysics Division, Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | | | - Ilse Letofsky-Papst
- Institute for Electron Microscopy and Nanoanalysis and Center for Electron Microscopy, Graz University of Technology, Graz, Austria
| | - Karl Lohner
- Biophysics Division, Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Georg Pabst
- Biophysics Division, Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Robert Vácha
- CEITEC-Central European Institute of Technology, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic; Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic.
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40
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Bernecker C, Köfeler H, Pabst G, Trötzmüller M, Kolb D, Strohmayer K, Trajanoski S, Holzapfel GA, Schlenke P, Dorn I. Cholesterol Deficiency Causes Impaired Osmotic Stability of Cultured Red Blood Cells. Front Physiol 2019; 10:1529. [PMID: 31920725 PMCID: PMC6933518 DOI: 10.3389/fphys.2019.01529] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Accepted: 12/04/2019] [Indexed: 11/17/2022] Open
Abstract
Ex vivo generation of red blood cells (cRBCs) is an attractive tool in basic research and for replacing blood components donated by volunteers. As a prerequisite for the survival of cRBCs during storage as well as in the circulation, the quality of the membrane is of utmost importance. Besides the cytoskeleton and embedded proteins, the lipid bilayer is critical for membrane integrity. Although cRBCs suffer from increased fragility, studies investigating the lipid content of their membrane are still lacking. We investigated the membrane lipid profile of cRBCs from CD34+ human stem and progenitor cells compared to native red blood cells (nRBCs) and native reticulocytes (nRETs). Ex vivo erythropoiesis was performed in a well-established liquid assay. cRBCs showed a maturation grade between nRETs and nRBCs. High-resolution mass spectrometry analysis for cholesterol and the major phospholipid classes, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, sphingomyelin and lysophosphatidylcholin, demonstrated severe cholesterol deficiency in cRBCs. Although cRBCs showed normal deformability capacity, they suffered from increased hemolysis due to minimal changes in the osmotic conditions. After additional lipid supplementation, especially cholesterol during culturing, the cholesterol content of cRBCs increased to a subnormal amount. Concurrently, the osmotic resistance recovered completely and became comparable to that of nRETs. Minor differences in the amount of phospholipids in cRBCs compared to native cells could mainly be attributed to the ongoing membrane remodeling process from the reticulocyte to the erythrocyte stage. Obtained results demonstrate severe cholesterol deficiency as a reason for enhanced fragility of cRBCs. Therefore, the supplementation of lipids, especially cholesterol during ex vivo erythropoiesis may overcome this limitation and strengthens the survival of cRBCs ex vivo and in vivo.
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Affiliation(s)
- Claudia Bernecker
- Department for Blood Group Serology and Transfusion Medicine, Medical University of Graz, Graz, Austria
| | - Harald Köfeler
- Center for Medical Research, Medical University of Graz, Graz, Austria
| | - Georg Pabst
- Institute of Molecular Biosciences, University of Graz, Biophysics Division, BioTechMed Graz, Graz, Austria
| | | | - Dagmar Kolb
- Center for Medical Research, Medical University of Graz, Graz, Austria.,Division of Cell Biology, Histology and Embryology, Gottfried Schatz Research Center, Medical University of Graz, Graz, Austria
| | - Karl Strohmayer
- Institute of Biomechanics, Graz University of Technology, Graz, Austria
| | - Slave Trajanoski
- Center for Medical Research, Medical University of Graz, Graz, Austria
| | - Gerhard A Holzapfel
- Institute of Biomechanics, Graz University of Technology, Graz, Austria.,Department of Structural Engineering, Norwegian University of Science and Technology, Trondheim, Norway
| | - Peter Schlenke
- Department for Blood Group Serology and Transfusion Medicine, Medical University of Graz, Graz, Austria
| | - Isabel Dorn
- Department for Blood Group Serology and Transfusion Medicine, Medical University of Graz, Graz, Austria
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Pachler M, Kabelka I, Appavou MS, Lohner K, Vácha R, Pabst G. Magainin 2 and PGLa in Bacterial Membrane Mimics I: Peptide-Peptide and Lipid-Peptide Interactions. Biophys J 2019; 117:1858-1869. [PMID: 31703802 PMCID: PMC7031808 DOI: 10.1016/j.bpj.2019.10.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 10/08/2019] [Accepted: 10/15/2019] [Indexed: 11/30/2022] Open
Abstract
We addressed the onset of synergistic activity of the two well-studied antimicrobial peptides magainin 2 (MG2a) and PGLa using lipid-only mimics of Gram-negative cytoplasmic membranes. Specifically, we coupled a joint analysis of small-angle x-ray and neutron scattering experiments on fully hydrated lipid vesicles in the presence of MG2a and L18W-PGLa to all-atom and coarse-grained molecular dynamics simulations. In agreement with previous studies, both peptides, as well as their equimolar mixture, were found to remain upon adsorption in a surface-aligned topology and to induce significant membrane perturbation, as evidenced by membrane thinning and hydrocarbon order parameter changes in the vicinity of the inserted peptide. These effects were particularly pronounced for the so-called synergistic mixture of 1:1 (mol/mol) L18W-PGLa/MG2a and cannot be accounted for by a linear combination of the membrane perturbations of two peptides individually. Our data are consistent with the formation of parallel heterodimers at concentrations below a synergistic increase of dye leakage from vesicles. Our simulations further show that the heterodimers interact via salt bridges and hydrophobic forces, which apparently makes them more stable than putatively formed antiparallel L18W-PGLa and MG2a homodimers. Moreover, dimerization of L18W-PGLa and MG2a leads to a relocation of the peptides within the lipid headgroup region as compared to the individual peptides. The early onset of dimerization of L18W-PGLa and MG2a at low peptide concentrations consequently appears to be key to their synergistic dye-releasing activity from lipid vesicles at high concentrations.
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Affiliation(s)
- Michael Pachler
- Biophysics Division, Institute of Molecular Biosciences, University of Graz, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Ivo Kabelka
- CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Marie-Sousai Appavou
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum, Forschungszentrum Jülich GmbH, Germany
| | - Karl Lohner
- Biophysics Division, Institute of Molecular Biosciences, University of Graz, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Robert Vácha
- CEITEC-Central European Institute of Technology, Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic; Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Georg Pabst
- Biophysics Division, Institute of Molecular Biosciences, University of Graz, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria.
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Eicher B, Marquardt D, Heberle FA, Letofsky-Papst I, Rechberger GN, Appavou MS, Katsaras J, Pabst G. Intrinsic Curvature-Mediated Transbilayer Coupling in Asymmetric Lipid Vesicles. Biophys J 2019; 114:146-157. [PMID: 29320681 PMCID: PMC5773765 DOI: 10.1016/j.bpj.2017.11.009] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 10/30/2017] [Accepted: 11/09/2017] [Indexed: 11/16/2022] Open
Abstract
We measured the effect of intrinsic lipid curvature, J0, on structural properties of asymmetric vesicles made of palmitoyl-oleoyl-phosphatidylethanolamine (POPE; J0<0) and palmitoyl-oleoyl-phosphatidylcholine (POPC; J0∼0). Electron microscopy and dynamic light scattering were used to determine vesicle size and morphology, and x-ray and neutron scattering, combined with calorimetric experiments and solution NMR, yielded insights into leaflet-specific lipid packing and melting processes. Below the lipid melting temperature we observed strong interleaflet coupling in asymmetric vesicles with POPE inner bilayer leaflets and outer leaflets enriched in POPC. This lipid arrangement manifested itself by lipids melting cooperatively in both leaflets, and a rearrangement of lipid packing in both monolayers. On the other hand, no coupling was observed in vesicles with POPC inner bilayer leaflets and outer leaflets enriched in POPE. In this case, the leaflets melted independently and did not affect each other’s acyl chain packing. Furthermore, we found no evidence for transbilayer structural coupling above the melting temperature of either sample preparation. Our results are consistent with the energetically preferred location of POPE residing in the inner leaflet, where it also resides in natural membranes, most likely causing the coupling of both leaflets. The loss of this coupling in the fluid bilayers is most likely the result of entropic contributions.
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Affiliation(s)
- Barbara Eicher
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz; BioTechMed-Graz, Graz, Austria
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada
| | - Frederick A Heberle
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee; The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee; Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Ilse Letofsky-Papst
- Institute for Electron Microscopy and Nanoanalysis and Center for Electron Microscopy, Graz University of Technology, NAWI Graz
| | - Gerald N Rechberger
- Institute of Molecular Biosciences, University of Graz, Graz, Austria; Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Marie-Sousai Appavou
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Garching, Germany; Forschungszentrum Jülich GmbH, Institut für Festkörperforschung, Jülich Center for Neutron Science at FRM II Outstation, Garching, Germany
| | - John Katsaras
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee; The Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, Tennessee; Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz; BioTechMed-Graz, Graz, Austria.
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Leber R, Pachler M, Kabelka I, Svoboda I, Enkoller D, Vácha R, Lohner K, Pabst G. Synergism of Antimicrobial Frog Peptides Couples to Membrane Intrinsic Curvature Strain. Biophys J 2019; 114:1945-1954. [PMID: 29694871 PMCID: PMC5937145 DOI: 10.1016/j.bpj.2018.03.006] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/07/2018] [Accepted: 03/12/2018] [Indexed: 01/11/2023] Open
Abstract
Mixtures of the frog peptides magainin 2 and PGLa are well-known for their pronounced synergistic killing of Gram-negative bacteria. We aimed to gain insight into the underlying biophysical mechanism by interrogating the permeabilizing efficacies of the peptides as a function of stored membrane curvature strain. For Gram-negative bacterial-inner-membrane mimics, synergism was only observed when the anionic bilayers exhibited significant negative intrinsic curvatures imposed by monounsaturated phosphatidylethanolamine. In contrast, the peptides and their mixtures did not exhibit significant activities in charge-neutral mammalian mimics, including those with negative curvature, which is consistent with the requirement of charge-mediated peptide binding to the membrane. Our experimental findings are supported by computer simulations showing a significant decrease of the peptide-insertion free energy in membranes upon shifting intrinsic curvatures toward more positive values. The physiological relevance of our model studies is corroborated by a remarkable agreement with the peptide’s synergistic activity in Escherichia coli. We propose that synergism is related to a lowering of a membrane-curvature-strain-mediated free-energy barrier by PGLa that assists membrane insertion of magainin 2, and not by strict pairwise interactions of the two peptides as suggested previously.
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Affiliation(s)
- Regina Leber
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Michael Pachler
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Ivo Kabelka
- Central European Institute of Technology, Brno, Czech Republic; Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Irene Svoboda
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | | | - Robert Vácha
- Central European Institute of Technology, Brno, Czech Republic; Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Karl Lohner
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria
| | - Georg Pabst
- Institute of Molecular Biosciences, Biophysics Division, University of Graz, NAWI Graz, Graz, Austria; BioTechMed Graz, Graz, Austria.
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44
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Frewein MPK, Rumetshofer M, Pabst G. Global small-angle scattering data analysis of inverted hexagonal phases. J Appl Crystallogr 2019; 52:403-414. [PMID: 30996718 PMCID: PMC6448687 DOI: 10.1107/s1600576719002760] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 02/23/2019] [Indexed: 11/29/2022] Open
Abstract
A global small-angle scattering model for unoriented, fully hydrated, inverted hexagonal phases is provided. The model is evaluated using Bayesian probability theory to obtain reliable estimates for the structural parameters. A global analysis model has been developed for randomly oriented, fully hydrated, inverted hexagonal (HII) phases formed by many amphiphiles in aqueous solution, including membrane lipids. The model is based on a structure factor for hexagonally packed rods and a compositional model for the scattering length density, enabling also the analysis of positionally weakly correlated HII phases. Bayesian probability theory was used for optimization of the adjustable parameters, which allows parameter correlations to be retrieved in much more detail than standard analysis techniques and thereby enables a realistic error analysis. The model was applied to different phosphatidylethanolamines, including previously unreported HII data for diC14:0 and diC16:1 phosphatidylethanolamine. The extracted structural features include intrinsic lipid curvature, hydrocarbon chain length and area per lipid at the position of the neutral plane.
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Affiliation(s)
- Moritz P K Frewein
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria
| | - Michael Rumetshofer
- Graz University of Technology, Institute of Theoretical Physics and Computational Physics, NAWI Graz, 8010 Graz, Austria
| | - Georg Pabst
- University of Graz, Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, 8010 Graz, Austria.,BioTechMed Graz, 8010 Graz, Austria
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45
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Frewein MP, Kremser J, Ziherl P, Pabst G. Intrinsic Curvatures from Global X-Ray Scattering Data Analysis of Inverted Hexagonal Phases. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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46
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Pachler M, Kabelka I, Leber R, Letofsky-Papst I, Lohner K, Vacha R, Pabst G. Synergism of Magainins is Not Coupled to the Formation of a Well-Defined Peptide Pore. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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47
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Eicher B, Marquardt D, Heberle FA, Letofsky-Papst I, Katsaras J, Pabst G. Curvature-Mediated Transmembrane Coupling in Asymmetric Lipids Vesicles. Biophys J 2018. [DOI: 10.1016/j.bpj.2017.11.2104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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48
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Russo P, Papa V, Russo S, Bella AD, Pabst G, Milazzo G, Balestrazzi A, Caporossi A, Anselmetti G, Lorenzi U, Orsi R, Faletti P, Bindella G, Boccassini G, Kropp B, Calabria G, Campagna P, Ciurlo C, Caporossi A, Tasciotti A, Licignano R, Balestrazzi A, Caprioglio G, Birattari F, Franch A, Darondeau J, Blanluet G, Ouen S, Guerra R, Saccarola P, Lenz W, Schuff O, Lùpidi G, Coiràn M, Checcucci M, Burattini L, Foligno, Mastropasqua L, Ciancaglini M, Ciafrè M, Cerulli A, Moretti G, Padovano S, Rotondo SG, Neuhann T, Okrafka K, Ratiglia R, Oldani A, Reiss H, Rochefort J, Coulombe B, Sborgia C, Lorusso V, Palmisano C, Moramarco N, Spinelli D, Curatola M, Maruccia A, Vaona P, Faraldi F, Villani C, Schiavone M, Gisoldi RC. Topical Nonsteroidal Anti-Inflammatory Drugs in Uncomplicated Cataract Surgery: Effect of Sodium Naproxen. Eur J Ophthalmol 2018. [DOI: 10.1177/112067210501500510] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Purpose To investigate whether topical nonsteroidal anti inflammatory drugs (NSAIDs) are useful, in the absence of concomitant corticosteroid therapy, in limiting postoperative inflammation after uncomplicated cataract surgery. Methods A total of 328 patients were enrolled in a prospective, randomized, double-masked, parallel-group, active-controlled study. Anterior chamber inflammation (ACI) was evaluated as the primary efficacy parameter. Only patients with moderate inflammation (ACI score of ≤4) the day after surgery were randomized and treated with NSAIDs. A novel topical formulation containing 0.2% sodium naproxen was compared with 0.1% diclofenac. Both were administered three times a day for 14 consecutive days. Ocular inflammation was measured after 7 and 14 days by using slit-lamp biomicroscopy. Safety parameters were also evaluated at the same time. Results Both treatments were equally effective in controlling postsurgical inflammation. No statistically significant differences between treatment groups were observed for the safety variables. No serious adverse events (AEs) occurred during the course of the study. The most frequent AE reported with naproxen was eye redness. Conclusions NSAIDs can effectively be used without concurrent administration of corticosteroids to control postoperative inflammation after uncomplicated cataract surgery. In addition, naproxen ophthalmic solution may be considered a suitable alternative to the currently available NSAIDs.
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Affiliation(s)
- P. Russo
- Medical Department SIFI SpA, Catania - Italy
| | - V. Papa
- Medical Department SIFI SpA, Catania - Italy
| | - S. Russo
- Medical Department SIFI SpA, Catania - Italy
| | - A. Dl Bella
- Medical Department SIFI SpA, Catania - Italy
| | - G. Pabst
- AAI Deutschland GmbH & Co KG, Neu-Ulm - Germany
| | - G. Milazzo
- Medical Department SIFI SpA, Catania - Italy
| | - A. Balestrazzi
- Department of Ophthalmology, University of Siena, Siena - Italy
| | - A. Caporossi
- Department of Ophthalmology, University of Siena, Siena - Italy
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Oluwole AO, Klingler J, Danielczak B, Babalola JO, Vargas C, Pabst G, Keller S. Formation of Lipid-Bilayer Nanodiscs by Diisobutylene/Maleic Acid (DIBMA) Copolymer. Langmuir 2017; 33:14378-14388. [PMID: 29160078 DOI: 10.1021/acs.langmuir.7b03742] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Membrane proteins usually need to be extracted from their native environment and separated from other membrane components for in-depth in vitro characterization. The use of styrene/maleic acid (SMA) copolymers to solubilize membrane proteins and their surrounding lipids into bilayer nanodiscs is an attractive approach toward this goal. We have recently shown that a diisobutylene/maleic acid (DIBMA) copolymer similarly solubilizes model and cellular membranes but, unlike SMA(3:1), has a mild impact on lipid acyl-chain order and thermotropic phase behavior. Here, we used fluorescence spectroscopy, small-angle X-ray scattering, size-exclusion chromatography, dynamic light scattering, and 31P nuclear magnetic resonance spectroscopy to examine the self-association of DIBMA and its membrane-solubilization properties against lipids differing in acyl-chain length and saturation. Although DIBMA is less hydrophobic than commonly used SMA(3:1) and SMA(2:1) copolymers, it efficiently formed lipid-bilayer nanodiscs that decreased in size with increasing polymer/lipid ratio while maintaining the overall thickness of the membrane. DIBMA fractions of different molar masses were similarly efficient in solubilizing a saturated lipid. Coulomb screening at elevated ionic strength or reduced charge density on the polymer at low pH enhanced the solubilization efficiency of DIBMA. The free-energy penalty for transferring phospholipids from vesicular bilayers into nanodiscs became more unfavorable with increasing acyl-chain length and unsaturation. Altogether, these findings provide a rational framework for using DIBMA in membrane-protein research by shedding light on the effects of polymer and lipid properties as well as experimental conditions on membrane solubilization.
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Affiliation(s)
- Abraham Olusegun Oluwole
- Molecular Biophysics, University of Kaiserslautern , Erwin-Schrödinger-Str. 13, 67663 Kaiserslautern, Germany
- Department of Chemistry, University of Ibadan , 200284 Ibadan, Nigeria
| | - Johannes Klingler
- Molecular Biophysics, University of Kaiserslautern , Erwin-Schrödinger-Str. 13, 67663 Kaiserslautern, Germany
| | - Bartholomäus Danielczak
- Molecular Biophysics, University of Kaiserslautern , Erwin-Schrödinger-Str. 13, 67663 Kaiserslautern, Germany
| | | | - Carolyn Vargas
- Molecular Biophysics, University of Kaiserslautern , Erwin-Schrödinger-Str. 13, 67663 Kaiserslautern, Germany
| | - Georg Pabst
- Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz , Humboldtstr. 50/III, 8010 Graz, Austria
- BioTechMed-Graz , 8010 Graz, Austria
| | - Sandro Keller
- Molecular Biophysics, University of Kaiserslautern , Erwin-Schrödinger-Str. 13, 67663 Kaiserslautern, Germany
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Abstract
Biomimetic lipid vesicles are indispensable tools for gaining insight into the biophysics of cell physiology on the molecular level. The level of complexity of these model systems has steadily increased, and now spans from domain-forming lipid mixtures to asymmetric lipid bilayers. Here, we review recent progress in the development and application of elastic neutron and X-ray scattering techniques for studying these systems in situ and under physiologically relevant conditions on the nanometer to sub-nanometer length scales. In particular, we focus on: (1) structural details of coexisting liquid-ordered and liquid-disordered domains, including their thickness and lipid packing mismatch as a function of a size transition from nanoscopic to macroscopic domains; (2) membrane-mediated protein partitioning into lipid domains; (3) the role of the aqueous medium in tuning interactions between membranes and domains; and (4) leaflet-specific structure in asymmetric bilayers and passive lipid flip-flop.
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Affiliation(s)
- Frederick A Heberle
- The Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA.,Joint Institute for Biological Sciences and Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
| | - Georg Pabst
- Institute of Molecular Biosciences, Biophysics Division, NAWI Graz, University of Graz, 8010, Graz, Austria. .,BioTechMed-Graz, 8010, Graz, Austria.
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