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Syryamina VN, Aisenbrey C, Kardash M, Dzuba SA, Bechinger B. Self-assembly of spin-labeled antimicrobial peptides magainin 2 and PGLa in lipid bilayers. Biophys Chem 2024; 310:107251. [PMID: 38678820 DOI: 10.1016/j.bpc.2024.107251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/15/2024] [Accepted: 04/21/2024] [Indexed: 05/01/2024]
Abstract
The cationic antimicrobial peptides PGLa and magainin 2 (Mag2) are known for their antimicrobial activity and synergistic enhancement in antimicrobial and membrane leakage assays. Further use of peptides in combinatory therapy requires knowledge of the mechanisms of action of both individual peptides and their mixtures. Here, electron paramagnetic resonance (EPR), double electron-electron resonance (DEER, also known as PELDOR) and electron spin echo envelope modulation (ESEEM) spectroscopies were applied to study self-assembly and localization of spin-labeled PGLa and Mag2 in POPE/POPG membranes with a wide range of peptide/lipid ratios (P/L) from ∼1/1500 to 1/50. EPR and DEER data showed that both peptides tend to organize in clusters, which occurs already at the lowest peptide/lipid molar ratio of 1/1500 (0.067 mol%). For individual peptides, these clusters are quite dense with intermolecular distances of the order of ∼2 nm. In the presence of a synergistic peptide partner, these homo-clusters are transformed into lipid-diluted hetero-clusters. These clusters are characterized by a local surface density that is several times higher than expected from a random distribution. ESEEM data indicate a slightly different insertion depth of peptides in hetero-clusters when compared to homo-clusters.
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Affiliation(s)
- Victoria N Syryamina
- Voevodsky Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation
| | - Christopher Aisenbrey
- University of Strasbourg/CNRS, UMR7177, Strasbourg Institute of Chemistry, Membrane Biophysics and NMR, 67000 Strasbourg, France
| | - Maria Kardash
- University of Strasbourg/CNRS, UMR7177, Strasbourg Institute of Chemistry, Membrane Biophysics and NMR, 67000 Strasbourg, France
| | - Sergei A Dzuba
- Voevodsky Institute of Chemical Kinetics and Combustion, RAS, Novosibirsk 630090, Russian Federation; Department of Physics, Novosibirsk State University, 630090 Novosibirsk, Russian Federation.
| | - Burkhard Bechinger
- University of Strasbourg/CNRS, UMR7177, Strasbourg Institute of Chemistry, Membrane Biophysics and NMR, 67000 Strasbourg, France; Institut Universitaire de France, 75231 Paris, France.
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2
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Rzycki M, Drabik D. Multifaceted Activity of Fabimycin: Insights from Molecular Dynamics Studies on Bacterial Membrane Models. J Chem Inf Model 2024; 64:4204-4217. [PMID: 38733348 PMCID: PMC11134499 DOI: 10.1021/acs.jcim.4c00228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 04/29/2024] [Accepted: 04/30/2024] [Indexed: 05/13/2024]
Abstract
Membranes─cells' essential scaffolds─are valid molecular targets for substances with an antimicrobial effect. While certain substances, such as octenidine, have been developed to target membranes for antimicrobial purposes, the recently reported molecule, fabimycin (F2B)─a novel agent targeting drug-resistant Gram-negative bacteria─has not received adequate attention regarding its activity on membranes in the literature. The following study aims to investigate the effects of F2B on different bacterial membrane models, including simple planar bilayers and more complex bilayer systems that mimic the Escherichia coli shell equipped with double inner and outer bilayers. Our results show that F2B exhibited more pronounced interactions with bacterial membrane systems compared to the control PC system. Furthermore, we observed significant changes in local membrane property homeostasis in both the inner and outer membrane models, specifically in the case of lateral diffusion, membrane thickness, and membrane resilience (compressibility, tilt). Finally, our results showed that the effect of F2B differed in a complex system and a single membrane system. Our study provides new insights into the multifaceted activity of F2B, demonstrating its potential to disrupt bacterial membrane homeostasis, indicating that its activity extends the currently known mechanism of FabI enzyme inhibition. This disruption, coupled with the ability of F2B to penetrate the outer membrane layers, sheds new light on the behavior of this antimicrobial molecule. This highlights the importance of the interaction with the membrane, crucial in combating bacterial infections, particularly those caused by drug-resistant strains.
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Affiliation(s)
- Mateusz Rzycki
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw 50-370, Poland
| | - Dominik Drabik
- Department of Biomedical Engineering, Wroclaw University of Science and Technology, Wroclaw 50-370, Poland
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3
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Kumar K, Arnold AA, Gauthier R, Mamone M, Paquin JF, Warschawski DE, Marcotte I. 19F solid-state NMR approaches to probe antimicrobial peptide interactions with membranes in whole cells. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184269. [PMID: 38176532 DOI: 10.1016/j.bbamem.2023.184269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 12/19/2023] [Accepted: 12/21/2023] [Indexed: 01/06/2024]
Abstract
To address the global problem of bacterial antibiotic resistance, antimicrobial peptides (AMPs) are considered promising therapeutic candidates due to their broad-spectrum and membrane-lytic activity. As preferential interactions with bacteria are crucial, it is equally important to investigate and understand their impact on eukaryotic cells. In this study, we employed 19F solid-state nuclear magnetic resonance (ssNMR) as a novel approach to examine the interaction of AMPs with whole red blood cells (RBCs). We used RBC ghosts (devoid of hemoglobin) and developed a protocol to label their lipid membranes with palmitic acid (PA) monofluorinated at carbon positions 4, 8, or 14 on the acyl chain, allowing us to probe different locations in model and intact RBC ghost membranes. Our work revealed that changes in the 19F chemical shift anisotropy, monitored through a CF bond order parameter (SCF), can provide insights into lipid bilayer dynamics. This information was also obtained using magic-angle spinning 19F ssNMR spectra with and without 1H decoupling, by studying alterations in the second spectral moment (M2) as well as the 19F isotropic chemical shift, linewidth, T1, and T2 relaxation times. The appearance of an additional isotropic peak with a smaller chemical shift anisotropy, a narrower linewidth, and a shorter T1, induced by the AMP caerin 1.1, supports the presence of high-curvature regions in RBCs indicative of pore formation, analogous to its antimicrobial mechanism. In summary, the straightforward incorporation of monofluorinated FAs and rapid signal acquisition offer promising avenues for the study of whole cells using 19F ssNMR.
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Affiliation(s)
- Kiran Kumar
- Departement of Chemistry, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montreal H3C 3P8, Canada
| | - Alexandre A Arnold
- Departement of Chemistry, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montreal H3C 3P8, Canada
| | - Raphaël Gauthier
- PROTEO, CCVC, Département de chimie, Université Laval, 1045 Avenue de la Médecine, Québec, Québec G1V 0A6, Canada
| | - Marius Mamone
- PROTEO, CCVC, Département de chimie, Université Laval, 1045 Avenue de la Médecine, Québec, Québec G1V 0A6, Canada
| | - Jean-François Paquin
- PROTEO, CCVC, Département de chimie, Université Laval, 1045 Avenue de la Médecine, Québec, Québec G1V 0A6, Canada
| | - Dror E Warschawski
- Departement of Chemistry, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montreal H3C 3P8, Canada; Laboratoire des Biomolécules, LBM, CNRS UMR 7203, Sorbonne Université, École normale supérieure, PSL University, 75005 Paris, France.
| | - Isabelle Marcotte
- Departement of Chemistry, Université du Québec à Montréal, P.O. Box 8888, Downtown Station, Montreal H3C 3P8, Canada.
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4
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Bowers SR, Lockhart C, Klimov DK. Binding and dimerization of PGLa peptides in anionic lipid bilayer studied by replica exchange molecular dynamics. Sci Rep 2024; 14:4972. [PMID: 38424117 PMCID: PMC10904749 DOI: 10.1038/s41598-024-55270-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Accepted: 02/21/2024] [Indexed: 03/02/2024] Open
Abstract
The 21-residue PGLa peptide is well known for antimicrobial activity attributed to its ability to compromize bacterial membranes. Using all-atom explicit solvent replica exchange molecular dynamics with solute tempering, we studied PGLa binding to a model anionic DMPC/DMPG bilayer at the high peptide:lipid ratio that promotes PGLa dimerization (a two peptides per leaflet system). As a reference we used our previous simulations at the low peptide:lipid ratio (a one peptide per leaflet system). We found that the increase in the peptide:lipid ratio suppresses PGLa helical propensity, tilts the bound peptide toward the bilayer hydrophobic core, and forces it deeper into the bilayer. Surprisingly, at the high peptide:lipid ratio PGLa binding induces weaker bilayer thinning, but deeper water permeation. We explain these effects by the cross-correlations between lipid shells surrounding PGLa that leads to a much diminished efflux of DMPC lipids from the peptide proximity at the high peptide:lipid ratio. Consistent with the experimental data the propensity for PGLa dimerization was found to be weak resulting in coexistence of monomers and dimers with distinctive properties. PGLa dimers assemble via apolar criss-cross interface and become partially expelled from the bilayer residing at the bilayer-water boundary. We rationalize their properties by the dimer tendency to preserve favorable electrostatic interactions between lysine and phosphate lipid groups as well as to avoid electrostatic repulsion between lysines in the low dielectric environment of the bilayer core. PGLa homedimer interface is predicted to be distinct from that involved in PGLa-magainin heterodimers.
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Affiliation(s)
- Steven R Bowers
- School of Systems Biology, George Mason University, Manassas, VA, 20110, USA
| | | | - Dmitri K Klimov
- School of Systems Biology, George Mason University, Manassas, VA, 20110, USA.
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Bowers SR, Lockhart C, Klimov DK. Replica Exchange with Hybrid Tempering Efficiently Samples PGLa Peptide Binding to Anionic Bilayer. J Chem Theory Comput 2023; 19:6532-6550. [PMID: 37676235 DOI: 10.1021/acs.jctc.3c00787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
Abstract
We evaluated the utility of a variant of the replica exchange method, a replica exchange with hybrid tempering (REHT), for all-atom explicit water biomolecular simulations and compared it with a more traditional replica exchange with the solute tempering (REST) algorithm. As a test system, we selected a 21-mer antimicrobial peptide PGLa binding to an anionic DMPC/DMPG lipid bilayer. Application of REHT revealed the following binding mechanism. Due to the strong hydrophobic moment, the bound PGLa adopts an extensive helical structure. The binding free energy landscape identifies two major bound states, a metastable surface bound state and a dominant inserted state. In both states, positively charged PGLa amino acids maintain electrostatic interactions with anionic phosphate groups by rotating the PGLa helix around its axis. PGLa binding causes an influx of anionic DMPG and an efflux of zwitterionic DMPC lipids from the peptide proximity. PGLa thins the bilayer and disorders the adjacent fatty acid tails. Deep invasion of water wires into the bilayer hydrophobic core is detected in the inserted peptide state. The analysis of charge density distributions indicated that peptide positive charges are nearly compensated for by lipid negative charges and water dipole ordering, whereas ions play no role in peptide binding. Thus, electrostatic interactions are the key energetic factor in binding cationic PGLa to an anionic DMPC/DMPG bilayer. Comparison of REHT and REST shows that due to exclusion of lipids from tempered partition, REST lags behind REHT in peptide equilibration, particularly, with respect to peptide insertion and helix acquisition. As a result, REST struggles to provide accurate details of PGLa binding, although it still qualitatively maps the bimodal binding mechanism. Importantly, REHT not only equilibrates PGLa in the bilayer faster than REST, but also with less computational effort. We conclude that REHT is a preferable choice for studying interfacial biomolecular systems.
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Affiliation(s)
- Steven R Bowers
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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6
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Roversi D, Troiano C, Salnikov E, Giordano L, Riccitelli F, De Zotti M, Casciaro B, Loffredo MR, Park Y, Formaggio F, Mangoni ML, Bechinger B, Stella L. Effects of antimicrobial peptides on membrane dynamics: A comparison of fluorescence and NMR experiments. Biophys Chem 2023; 300:107060. [PMID: 37336097 DOI: 10.1016/j.bpc.2023.107060] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 05/25/2023] [Accepted: 06/02/2023] [Indexed: 06/21/2023]
Abstract
Antimicrobial peptides (AMPs) represent a promising class of compounds to fight resistant infections. They are commonly thought to kill bacteria by perturbing the permeability of their cell membranes. However, bacterial killing requires a high coverage of the cell surface by bound peptides, at least in the case of cationic and amphipathic AMPs. Therefore, it is conceivable that peptide accumulation on the bacterial membranes might interfere with vital cellular functions also by perturbing bilayer dynamics, a hypothesis that has been termed "sand in the gearbox". Here we performed a systematic study of such possible effects, for two representative peptides (the cationic cathelicidin PMAP-23 and the peptaibol alamethicin), employing fluorescence and NMR spectroscopies. These approaches are commonly applied to characterize lipid order and dynamics, but sample different time-scales and could thus report on different membrane properties. In our case, fluorescence anisotropy measurements on liposomes labelled with probes localized at different depths in the bilayer showed that both peptides perturb membrane fluidity and order. Pyrene excimer-formation experiments showed a peptide-induced reduction in lipid lateral mobility. Finally, laurdan fluorescence indicated that peptide binding reduces water penetration below the headgroups region. Comparable effects were observed also in fluorescence experiments performed directly on live bacterial cells. By contrast, the fatty acyl chain order parameters detected by deuterium NMR spectroscopy remained virtually unaffected by addition of the peptides. The apparent discrepancy between the two techniques confirms previous sporadic observations and is discussed in terms of the different characteristic times of the two approaches. The perturbation of membrane dynamics in the ns timescale, indicated by the multiple fluorescence approaches reported here, could contribute to the antimicrobial activity of AMPs, by affecting the function of membrane proteins, which is strongly dependent on the physicochemical properties of the bilayer.
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Affiliation(s)
- Daniela Roversi
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy
| | - Cassandra Troiano
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy
| | - Evgeniy Salnikov
- RMN et Biophysique des membranes, Institut de Chimie de Strasbourg, CNRS/UMR 7177, Université de Strasbourg, 4, rue Blaise Pascal, Strasbourg 67000, France
| | - Lorenzo Giordano
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy
| | - Francesco Riccitelli
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy
| | - Marta De Zotti
- Department of Chemical Sciences, University of Padova, Padova 35131, Italy
| | - Bruno Casciaro
- Department of Biochemical Sciences, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome 00185, Italy
| | - Maria Rosa Loffredo
- Department of Biochemical Sciences, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome 00185, Italy
| | - Yoonkyung Park
- Department of Biomedical Science and Research Center for Proteinaceous Materials (RCPM), Chosun University, Gwangju, Republic of Korea
| | - Fernando Formaggio
- Department of Chemical Sciences, University of Padova, Padova 35131, Italy
| | - Maria Luisa Mangoni
- Department of Biochemical Sciences, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome 00185, Italy
| | - Burkhard Bechinger
- RMN et Biophysique des membranes, Institut de Chimie de Strasbourg, CNRS/UMR 7177, Université de Strasbourg, 4, rue Blaise Pascal, Strasbourg 67000, France; Institut Universitaire de France, Paris 75005, France
| | - Lorenzo Stella
- Department of Chemical Science and Technology, University of Rome Tor Vergata, Rome 00133, Italy.
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Mhlongo JT, Waddad AY, Albericio F, de la Torre BG. Antimicrobial Peptide Synergies for Fighting Infectious Diseases. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2300472. [PMID: 37407512 PMCID: PMC10502873 DOI: 10.1002/advs.202300472] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 05/28/2023] [Indexed: 07/07/2023]
Abstract
Antimicrobial peptides (AMPs) are essential elements of thehost defense system. Characterized by heterogenous structures and broad-spectrumaction, they are promising candidates for combating multidrug resistance. Thecombined use of AMPs with other antimicrobial agents provides a new arsenal ofdrugs with synergistic action, thereby overcoming the drawback of monotherapiesduring infections. AMPs kill microbes via pore formation, thus inhibitingintracellular functions. This mechanism of action by AMPs is an advantage overantibiotics as it hinders the development of drug resistance. The synergisticeffect of AMPs will allow the repurposing of conventional antimicrobials andenhance their clinical outcomes, reduce toxicity, and, most significantly,prevent the development of resistance. In this review, various synergies ofAMPs with antimicrobials and miscellaneous agents are discussed. The effect ofstructural diversity and chemical modification on AMP properties is firstaddressed and then different combinations that can lead to synergistic action,whether this combination is between AMPs and antimicrobials, or AMPs andmiscellaneous compounds, are attended. This review can serve as guidance whenredesigning and repurposing the use of AMPs in combination with other antimicrobialagents for enhanced clinical outcomes.
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Affiliation(s)
- Jessica T. Mhlongo
- KwaZulu‐Natal Research Innovation and Sequencing Platform (KRISP)School of Laboratory Medicine and Medical SciencesCollege of Health SciencesUniversity of KwaZulu‐NatalDurban4041South Africa
- Peptide Science LaboratorySchool of Chemistry and PhysicsUniversity of KwaZulu‐NatalWestvilleDurban4000South Africa
| | - Ayman Y. Waddad
- Peptide Science LaboratorySchool of Chemistry and PhysicsUniversity of KwaZulu‐NatalWestvilleDurban4000South Africa
| | - Fernando Albericio
- Peptide Science LaboratorySchool of Chemistry and PhysicsUniversity of KwaZulu‐NatalWestvilleDurban4000South Africa
- CIBER‐BBNNetworking Centre on BioengineeringBiomaterials and Nanomedicineand Department of Organic ChemistryUniversity of BarcelonaBarcelona08028Spain
| | - Beatriz G. de la Torre
- KwaZulu‐Natal Research Innovation and Sequencing Platform (KRISP)School of Laboratory Medicine and Medical SciencesCollege of Health SciencesUniversity of KwaZulu‐NatalDurban4041South Africa
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8
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Adélaïde M, Salnikov E, Ramos-Martín F, Aisenbrey C, Sarazin C, Bechinger B, D’Amelio N. The Mechanism of Action of SAAP-148 Antimicrobial Peptide as Studied with NMR and Molecular Dynamics Simulations. Pharmaceutics 2023; 15:pharmaceutics15030761. [PMID: 36986623 PMCID: PMC10051583 DOI: 10.3390/pharmaceutics15030761] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 02/18/2023] [Accepted: 02/21/2023] [Indexed: 03/02/2023] Open
Abstract
Background: SAAP-148 is an antimicrobial peptide derived from LL-37. It exhibits excellent activity against drug-resistant bacteria and biofilms while resisting degradation in physiological conditions. Despite its optimal pharmacological properties, its mechanism of action at the molecular level has not been explored. Methods: The structural properties of SAAP-148 and its interaction with phospholipid membranes mimicking mammalian and bacterial cells were studied using liquid and solid-state NMR spectroscopy as well as molecular dynamics simulations. Results: SAAP-148 is partially structured in solution and stabilizes its helical conformation when interacting with DPC micelles. The orientation of the helix within the micelles was defined by paramagnetic relaxation enhancements and found similar to that obtained using solid-state NMR, where the tilt and pitch angles were determined based on 15N chemical shift in oriented models of bacterial membranes (POPE/POPG). Molecular dynamic simulations revealed that SAAP-148 approaches the bacterial membrane by forming salt bridges between lysine and arginine residues and lipid phosphate groups while interacting minimally with mammalian models containing POPC and cholesterol. Conclusions: SAAP-148 stabilizes its helical fold onto bacterial-like membranes, placing its helix axis almost perpendicular to the surface normal, thus probably acting by a carpet-like mechanism on the bacterial membrane rather than forming well-defined pores.
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Affiliation(s)
- Morgane Adélaïde
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, 80039 Amiens, France
| | - Evgeniy Salnikov
- Institut de Chimie, UMR7177, Université de Strasbourg/CNRS, 67000 Strasbourg, France
| | - Francisco Ramos-Martín
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, 80039 Amiens, France
- Correspondence: (F.R.-M.); (N.D.); Tel.: +33-3-22-82-74-73 (F.R.-M. & N.D.)
| | - Christopher Aisenbrey
- Institut de Chimie, UMR7177, Université de Strasbourg/CNRS, 67000 Strasbourg, France
| | - Catherine Sarazin
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, 80039 Amiens, France
| | - Burkhard Bechinger
- Institut de Chimie, UMR7177, Université de Strasbourg/CNRS, 67000 Strasbourg, France
| | - Nicola D’Amelio
- Unité de Génie Enzymatique et Cellulaire UMR 7025 CNRS, Université de Picardie Jules Verne, 80039 Amiens, France
- Correspondence: (F.R.-M.); (N.D.); Tel.: +33-3-22-82-74-73 (F.R.-M. & N.D.)
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9
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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] [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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10
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The potential of antifungal peptide Sesquin as natural food preservative. Biochimie 2022; 203:51-64. [PMID: 35395327 DOI: 10.1016/j.biochi.2022.03.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 12/16/2022]
Abstract
Sesquin is a wide spectrum antimicrobial peptide displaying a remarkable activity on fungi. Contrarily to most antimicrobial peptides, it presents an overall negative charge. In the present study, we elucidate the molecular basis of its mode of action towards biomimetic membranes by NMR and MD experiments. While a specific recognition of phosphatidylethanolamine (PE) might explain its activity in a variety of different organisms (including bacteria), a further interaction with ergosterol accounts for its strong antifungal activity. NMR data reveal a charge gradient along its amide protons allowing the peptide to reach the membrane phosphate groups despite its negative charge. Subsequently, the peptide gets structured inside the bilayer, reducing its order. MD simulations predict that its activity is retained in conditions commonly used for food preservation: low temperatures, high pressure, or the presence of electric field pulses, making Sesquin a good candidate as food preservative.
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11
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Salnikov E, Bechinger B. Effect of lipid saturation on the topology and oligomeric state of helical membrane polypeptides. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:184001. [PMID: 35817122 DOI: 10.1016/j.bbamem.2022.184001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/27/2022] [Accepted: 06/28/2022] [Indexed: 06/15/2023]
Abstract
Natural liquid crystalline membranes are made up of many different lipids carrying a mixture of saturated and unsaturated fatty acyl chains. Whereas in the past considerable attention has been paid to cholesterol content, the phospholipid head groups and the membrane surface charge the detailed fatty acyl composition was often considered less important. However, recent investigations indicate that the detailed fatty acyl chain composition has pronounced effects on the oligomerization of the transmembrane helical anchoring domains of the MHC II receptor or the membrane alignment of the cationic antimicrobial peptide PGLa. In contrast the antimicrobial peptides magainin 2 and alamethicin are less susceptible to lipid saturation. Using histidine-rich LAH4 designer peptides the high energetic contributions of lipid saturation in stabilizing transmembrane helical alignments are quantitatively evaluated. These observations can have important implications for the biological regulation of membrane proteins and should be taken into considerations during biophysical or structural experiments.
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Affiliation(s)
- Evgeniy Salnikov
- University of Strasbourg/CNRS, UMR7177 Chemistry Institute, Membrane Biophysics and NMR, Strasbourg, France
| | - Burkhard Bechinger
- University of Strasbourg/CNRS, UMR7177 Chemistry Institute, Membrane Biophysics and NMR, Strasbourg, France; Institut Universitaire de France, France.
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12
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Salnikov E, Aisenbrey C, Bechinger B. Lipid saturation and head group composition have a pronounced influence on the membrane insertion equilibrium of amphipathic helical polypeptides. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183844. [PMID: 34954200 DOI: 10.1016/j.bbamem.2021.183844] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 10/19/2022]
Abstract
The histidine-rich peptides of the LAH4 family were designed using cationic antimicrobial peptides such as magainin and PGLa as templates. The LAH4 amphipathic helical sequences exhibit a multitude of interesting biological properties such as antimicrobial activity, cell penetration of a large variety of cargo and lentiviral transduction enhancement. The parent peptide associates with lipid bilayers where it changes from an orientation along the membrane interface into a transmembrane configuration in a pH-dependent manner. Here we show that LAH4 adopts a transmembrane configuration in fully saturated DMPC membranes already at pH 3.5, i.e. much below the pKa of the histidines whereas the transition pH in POPC correlates closely with histidine neutralization. In contrast in POPG membranes the in-planar configuration is stabilized by about one pH unit. The differences in pH can be converted into energetic contributions for the in-plane to transmembrane transition equilibrium, where the shift in the transition pH due to lipid saturation corresponds to energies which are otherwise obtained by the exchange of several cationic with hydrophobic residues. A similar dependence on lipid saturation has also been observed when the PGLa and magainin antimicrobial peptides interact within lipid bilayers suggesting that the quantitative evaluation presented in this paper also applies to other membrane polypeptides.
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Affiliation(s)
- Evgeniy Salnikov
- University of Strasbourg/CNRS, UMR7177 Chemistry Institute, Membrane Biophysics and NMR, Strasbourg, France
| | - Christopher Aisenbrey
- University of Strasbourg/CNRS, UMR7177 Chemistry Institute, Membrane Biophysics and NMR, Strasbourg, France
| | - Burkhard Bechinger
- University of Strasbourg/CNRS, UMR7177 Chemistry Institute, Membrane Biophysics and NMR, Strasbourg, France; Institut Universitaire de France, France.
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13
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Bowers SR, Klimov DK, Lockhart C. Mechanisms of Binding of Antimicrobial Peptide PGLa to DMPC/DMPG Membrane. J Chem Inf Model 2022; 62:1525-1537. [PMID: 35266698 DOI: 10.1021/acs.jcim.1c01518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PGLa belongs to a class of antimicrobial peptides showing strong affinity to anionic bacterial membranes. Using all-atom explicit solvent replica exchange molecular dynamics with solute tempering, we studied binding of PGLa to a model anionic dimyristoylphosphatidylcholine/dimyristoylphosphatidylglycerol (DMPC/DMPG) bilayer. Due to a strong hydrophobic moment, PGLa upon binding adopts a helical structure and two distinct bound states separated by a significant free energy barrier. In these states, the C-terminus helix is either surface bound or inserted into the bilayer, whereas the N-terminus remains anchored in the bilayer. Analysis of the free energy landscape indicates that the transition between the two states involves a C-terminus helix rotation permitting the peptide to preserve the interactions between cationic Lys amino acids and anionic lipid phosphorus groups. We calculated the free energy of PGLa binding and showed that it is mostly governed by the balance between desolvation of PGLa positive charges and formation of electrostatic PGLa-lipid interactions. PGLa binding induces minor bilayer thinning but causes pronounced lipid redistribution resulting from an influx of DMPG lipids into the binding footprint and efflux of DMPC lipids. Our in silico results rationalize the S-state detected in NMR experiments.
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Affiliation(s)
- Steven R Bowers
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Dmitri K Klimov
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
| | - Christopher Lockhart
- School of Systems Biology, George Mason University, Manassas, Virginia 20110, United States
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14
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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] [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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15
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Booth V. Deuterium Solid State NMR Studies of Intact Bacteria Treated With Antimicrobial Peptides. FRONTIERS IN MEDICAL TECHNOLOGY 2022; 2:621572. [PMID: 35047897 PMCID: PMC8757836 DOI: 10.3389/fmedt.2020.621572] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 12/10/2020] [Indexed: 11/13/2022] Open
Abstract
Solid state NMR has been tremendously useful in characterizing the structure and dynamics of model membranes composed of simple lipid mixtures. Model lipid studies employing solid state NMR have included important work revealing how membrane bilayer structure and dynamics are affected by molecules such as antimicrobial peptides (AMPs). However, solid state NMR need not be applied only to model membranes, but can also be used with living, intact cells. NMR of whole cells holds promise for helping resolve some unsolved mysteries about how bacteria interact with AMPs. This mini-review will focus on recent studies using 2H NMR to study how treatment with AMPs affect membranes in intact bacteria.
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Affiliation(s)
- Valerie Booth
- Department of Biochemistry and Department of Physics and Physical Oceanograpy, Memorial University of Newfoundland, St. John's, NL, Canada
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16
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Juhl DW, Glattard E, Aisenbrey C, Bechinger B. Antimicrobial peptides: mechanism of action and lipid-mediated synergistic interactions within membranes. Faraday Discuss 2021; 232:419-434. [PMID: 34533138 DOI: 10.1039/d0fd00041h] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Biophysical and structural studies of peptide-lipid interactions, peptide topology and dynamics have changed our view of how antimicrobial peptides insert and interact with membranes. Clearly, both peptides and lipids are highly dynamic, and change and mutually adapt their conformation, membrane penetration and detailed morphology on a local and a global level. As a consequence, peptides and lipids can form a wide variety of supramolecular assemblies in which the more hydrophobic sequences preferentially, but not exclusively, adopt transmembrane alignments and have the potential to form oligomeric structures similar to those suggested by the transmembrane helical bundle model. In contrast, charged amphipathic sequences tend to stay intercalated at the membrane interface. Although the membranes are soft and can adapt, at increasing peptide density they cause pronounced disruptions of the phospholipid fatty acyl packing. At even higher local or global concentrations the peptides cause transient membrane openings, rupture and ultimately lysis. Interestingly, mixtures of peptides such as magainin 2 and PGLa, which are stored and secreted naturally as a cocktail, exhibit considerably enhanced antimicrobial activities when investigated together in antimicrobial assays and also in pore forming experiments applied to biophysical model systems. Our most recent investigations reveal that these peptides do not form stable complexes but act by specific lipid-mediated interactions and the nanoscale properties of phospholipid bilayers.
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Affiliation(s)
- Dennis W Juhl
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, 4, rue Blaise Pascal, 67070 Strasbourg, France.
| | - Elise Glattard
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, 4, rue Blaise Pascal, 67070 Strasbourg, France.
| | - Christopher Aisenbrey
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, 4, rue Blaise Pascal, 67070 Strasbourg, France.
| | - Burkhard Bechinger
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, 4, rue Blaise Pascal, 67070 Strasbourg, France. .,Institut Universitaire de France, France
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17
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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: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [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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18
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Cisse A, Marquette A, Altangerel M, Peters J, Bechinger B. Investigation of the Action of Peptides on Lipid Membranes. J Phys Chem B 2021; 125:10213-10223. [PMID: 34464136 DOI: 10.1021/acs.jpcb.1c06388] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Calorimetric and incoherent neutron scattering methods were employed to investigate the action of magainin 2 and PGLa peptides on the phase behavior and molecular dynamics of lipids mimicking cytoplasmic membranes of Gram-negative bacteria. The impact of the peptides, tested individually and cooperatively by differential scanning calorimetry, presented a broadened peak, sometimes with a second shoulder, depicting the phase transition temperature around 21 °C. Neutron scattering revealed a small but significant variation of the membrane dynamics due to the peptides in both in-plane and out-of-plane directions. Although we did not find a clear hint for synergy in the interplay of the two peptides, the calorimetric and neutron data give compatible results in terms of a decrease of the enthalpy due to the presence of the peptides, which destabilize the membrane. The dynamics in the two directions was differentiated when the individual peptides were added to the membranes, but the impact was smaller when both peptides were added together.
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Affiliation(s)
- Aline Cisse
- Univ. Grenoble-Alpes, CNRS, LiPhy, 38000 Grenoble, France.,Institut Laue-Langevin, 38000 Grenoble, France
| | - Arnaud Marquette
- University of Strasbourg/CNRS, Chemistry Institute, Membrane Biophysics and NMR, UMR7177 Strasbourg, France
| | - Munkhtuguldur Altangerel
- Univ. Grenoble-Alpes, CNRS, LiPhy, 38000 Grenoble, France.,Institut Laue-Langevin, 38000 Grenoble, France
| | - Judith Peters
- Univ. Grenoble-Alpes, CNRS, LiPhy, 38000 Grenoble, France.,Institut Laue-Langevin, 38000 Grenoble, France.,Institut Universitaire de France, 75231 Paris, France
| | - Burkhard Bechinger
- University of Strasbourg/CNRS, Chemistry Institute, Membrane Biophysics and NMR, UMR7177 Strasbourg, France.,Institut Universitaire de France, 75231 Paris, France
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19
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Kabelka I, Vácha R. Advances in Molecular Understanding of α-Helical Membrane-Active Peptides. Acc Chem Res 2021; 54:2196-2204. [PMID: 33844916 DOI: 10.1021/acs.accounts.1c00047] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Biological membranes separate the interior of cells or cellular compartments from their outer environments. This barrier function of membranes can be disrupted by membrane-active peptides, some of which can spontaneously penetrate through the membranes or open leaky transmembrane pores. However, the origin of their activity/toxicity is not sufficiently understood for the development of more potent peptides. To this day, there are no design rules that would be generally valid, and the role of individual amino acids tends to be sequence-specific.In this Account, we describe recent progress in understanding the design principles that govern the activity of membrane-active peptides. We focus on α-helical amphiphilic peptides and their ability to (1) translocate across phospholipid bilayers, (2) form transmembrane pores, or (3) act synergistically, i.e., to produce a significantly more potent effect in a mixture than the individual components.We refined the description of peptide translocation using computer simulations and demonstrated the effect of selected residues. Our simulations showed the necessity to explicitly include charged residues in the translocation description to correctly sample the membrane perturbations they can cause. Using this description, we calculated the translocation of helical peptides with and without the kink induced by the proline/glycine residue. The presence of the kink had no effect on the translocation barrier, but it decreased the peptide affinity to the membrane and reduced the peptide stability inside the membrane. Interestingly, the effects were mainly caused by the peptide's increased polarity, not the higher flexibility of the kink.Flexibility plays a crucial role in pore formation and affects distinct pore structures in different ways. The presence of a kink destabilizes barrel-stave pores, because the kink prevents the tight packing of peptides in the bundle, which is characteristic of the barrel-stave structure. In contrast, the kink facilitates the formation of toroidal pores, where the peptides are only loosely arranged and do not need to closely assemble. The exact position of the kink in the sequence further determines the preferred arrangement of peptides in the pore, i.e., an hourglass or U-shaped structure. In addition, we demonstrated that two self-associated (via termini) helical peptides could mimic the behavior of peptides with a helix-kink-helix motif.Finally, we review the recent findings on the peptide synergism of the archetypal mixture of Magainin 2 and PGLa peptides. We focused on a bacterial plasma membrane mimic that contains negatively charged lipids and lipids with negative intrinsic curvature. We showed that the synergistic action of peptides was highly dependent on the lipid composition. When the lipid composition and peptide/lipid ratios were changed, the systems exhibited more complex behavior than just the previously reported pore formation. We observed membrane adhesion, fusion, and even the formation of the sponge phase in this regime. Furthermore, enhanced adhesion/partitioning to the membrane was reported to be caused by lipid-induced peptide aggregation.In conclusion, the provided molecular insight into the complex behavior of membrane-active peptides provides clues for the design and modification of antimicrobial peptides or toxins.
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Affiliation(s)
- Ivo Kabelka
- CEITEC − Central European Institute of Technology, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University Kamenice 5, 625 00 Brno, Czech Republic
| | - Robert Vácha
- CEITEC − Central European Institute of Technology, Masaryk University, Kamenice 753/5, 625 00 Brno, Czech Republic
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University Kamenice 5, 625 00 Brno, Czech Republic
- Department of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotlářská 267/2, 611 37 Brno, Czech Republic
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20
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Simcock PW, Bublitz M, Cipcigan F, Ryadnov MG, Crain J, Stansfeld PJ, Sansom MSP. Membrane Binding of Antimicrobial Peptides Is Modulated by Lipid Charge Modification. J Chem Theory Comput 2021; 17:1218-1228. [PMID: 33395285 DOI: 10.1021/acs.jctc.0c01025] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide interactions with lipid bilayers play a key role in a range of biological processes and depend on electrostatic interactions between charged amino acids and lipid headgroups. Antimicrobial peptides (AMPs) initiate the killing of bacteria by binding to and destabilizing their membranes. The multiple peptide resistance factor (MprF) provides a defense mechanism for bacteria against a broad range of AMPs. MprF reduces the negative charge of bacterial membranes through enzymatic conversion of the anionic lipid phosphatidyl glycerol (PG) to either zwitterionic alanyl-phosphatidyl glycerol (Ala-PG) or cationic lysyl-phosphatidyl glycerol (Lys-PG). The resulting change in the membrane charge is suggested to reduce the binding of AMPs to membranes, thus impeding downstream AMP activity. Using coarse-grained molecular dynamics to investigate the effects of these modified lipids on AMP binding to model membranes, we show that AMPs have substantially reduced affinity for model membranes containing Ala-PG or Lys-PG. More than 5000 simulations in total are used to define the relationship between lipid bilayer composition, peptide sequence (using five different membrane-active peptides), and peptide binding to membranes. The degree of interaction of a peptide with a membrane correlates with the membrane surface charge density. Free energy profile (potential of mean force) calculations reveal that the lipid modifications due to MprF alter the energy barrier to peptide helix penetration of the bilayer. These results will offer a guide to the design of novel peptides, which addresses the issue of resistance via MprF-mediated membrane modification.
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Affiliation(s)
- Patrick W Simcock
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
| | - Maike Bublitz
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
| | | | - Maxim G Ryadnov
- National Physical Laboratory, Hampton Road, Teddington TW11 0LW, U.K
| | - Jason Crain
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
- IBM Research UK, Hartree Centre, Daresbury WA4 4AD, U.K
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
- School of Life Sciences and Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, U.K
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21
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Bechinger B, Juhl DW, Glattard E, Aisenbrey C. Revealing the Mechanisms of Synergistic Action of Two Magainin Antimicrobial Peptides. FRONTIERS IN MEDICAL TECHNOLOGY 2020; 2:615494. [PMID: 35047895 PMCID: PMC8757784 DOI: 10.3389/fmedt.2020.615494] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 11/30/2020] [Indexed: 12/18/2022] Open
Abstract
The study of peptide-lipid and peptide-peptide interactions as well as their topology and dynamics using biophysical and structural approaches have changed our view how antimicrobial peptides work and function. It has become obvious that both the peptides and the lipids arrange in soft supramolecular arrangements which are highly dynamic and able to change and mutually adapt their conformation, membrane penetration, and detailed morphology. This can occur on a local and a global level. This review focuses on cationic amphipathic peptides of the magainin family which were studied extensively by biophysical approaches. They are found intercalated at the membrane interface where they cause membrane thinning and ultimately lysis. Interestingly, mixtures of two of those peptides namely magainin 2 and PGLa which occur naturally as a cocktail in the frog skin exhibit synergistic enhancement of antimicrobial activities when investigated together in antimicrobial assays but also in biophysical experiments with model membranes. Detailed dose-response curves, presented here for the first time, show a cooperative behavior for the individual peptides which is much increased when PGLa and magainin are added as equimolar mixture. This has important consequences for their bacterial killing activities and resistance development. In membranes that carry unsaturations both peptides align parallel to the membrane surface where they have been shown to arrange into mesophases involving the peptides and the lipids. This supramolecular structuration comes along with much-increased membrane affinities for the peptide mixture. Because this synergism is most pronounced in membranes representing the bacterial lipid composition it can potentially be used to increase the therapeutic window of pharmaceutical formulations.
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Affiliation(s)
- Burkhard Bechinger
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
- Institut Universitaire de France (IUF), Paris, France
| | - Dennis Wilkens Juhl
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
| | - Elise Glattard
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
| | - Christopher Aisenbrey
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
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22
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Weber DK, Veglia G. A theoretical assessment of structure determination of multi-span membrane proteins by oriented sample solid-state NMR spectroscopy. Aust J Chem 2020; 73:246-251. [PMID: 33162560 DOI: 10.1071/ch19307] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Oriented sample solid state NMR (OS-ssNMR) spectroscopy allows direct determination of the structure and topology of membrane proteins reconstituted into aligned lipid bilayers. While OS-ssNMR theoretically has no upper size limit, its application to multi-span membrane proteins has not been established since most studies have been restricted to single or dual span proteins and peptides. Here, we present a critical assessment of the application of this method to multi-span membrane proteins. We used molecular dynamics simulations to back-calculate [15N-1H] separated local field (SLF) spectra from a G protein-coupled receptor (GPCR) and show that fully resolved spectra can be obtained theoretically for a multi-span membrane protein with currently achievable resonance linewidths.
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Affiliation(s)
- Daniel K Weber
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Gianluigi Veglia
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.,Department of Chemistry, University of Minnesota, Minneapolis, MN 55455, USA
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23
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Antibiofilm Activity on Candida albicans and Mechanism of Action on Biomembrane Models of the Antimicrobial Peptide Ctn[15-34]. Int J Mol Sci 2020; 21:ijms21218339. [PMID: 33172206 PMCID: PMC7664368 DOI: 10.3390/ijms21218339] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 12/18/2022] Open
Abstract
Ctn[15–34], the C-terminal fragment of crotalicidin, an antimicrobial peptide from the South American rattlesnake Crotalus durissus terrificus venom, displays remarkable anti-infective and anti-proliferative activities. Herein, its activity on Candida albicans biofilms and its interaction with the cytoplasmic membrane of the fungal cell and with a biomembrane model in vitro was investigated. A standard C. albicans strain and a fluconazole-resistant clinical isolate were exposed to the peptide at its minimum inhibitory concentration (MIC) (10 µM) and up to 100 × MIC to inhibit biofilm formation and its eradication. A viability test using XTT and fluorescent dyes, confocal laser scanning microscopy, and atomic force microscopy (AFM) were used to observe the antibiofilm effect. To evaluate the importance of membrane composition on Ctn[15–34] activity, C. albicans protoplasts were also tested. Fluorescence assays using di-8-ANEPPS, dynamic light scattering, and zeta potential measurements using liposomes, protoplasts, and C. albicans cells indicated a direct mechanism of action that was dependent on membrane interaction and disruption. Overall, Ctn[15–34] showed to be an effective antifungal peptide, displaying antibiofilm activity and, importantly, interacting with and disrupting fungal plasma membrane.
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24
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Juhl DW, Glattard E, Lointier M, Bampilis P, Bechinger B. The Reversible Non-covalent Aggregation Into Fibers of PGLa and Magainin 2 Preserves Their Antimicrobial Activity and Synergism. Front Cell Infect Microbiol 2020; 10:526459. [PMID: 33102247 PMCID: PMC7554302 DOI: 10.3389/fcimb.2020.526459] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 08/18/2020] [Indexed: 01/29/2023] Open
Abstract
Magainin 2 and PGLa are antimicrobial peptides found together in frog skin secretions. When added as a mixture they show an order of magnitude increase in antibacterial activity and in model membrane permeation assays. Here we demonstrate that both peptides can form fibers with beta-sheet/turn signature in ATR-FTIR- and CD-spectroscopic analyses, but with different morphologies in EM images. Whereas, fiber formation results in acute reduction of the antimicrobial activity of the individual peptides, the synergistic enhancement of activity remains for the equimolar mixture of PGLa and magainin 2 also after fibril formation. The biological significance and potential applications of such supramolecular aggregates are discussed.
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Affiliation(s)
- Dennis Wilkens Juhl
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
| | - Elise Glattard
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
| | - Morane Lointier
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
| | - Panos Bampilis
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
| | - Burkhard Bechinger
- University of Strasbourg/CNRS, UMR7177, Institut de Chimie de Strasbourg, Strasbourg, France
- Institut Universitaire de France (IUF), Paris, France
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Lointier M, Aisenbrey C, Marquette A, Tan JH, Kichler A, Bechinger B. Membrane pore-formation correlates with the hydrophilic angle of histidine-rich amphipathic peptides with multiple biological activities. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183212. [DOI: 10.1016/j.bbamem.2020.183212] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/27/2020] [Accepted: 01/29/2020] [Indexed: 01/06/2023]
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Highly synergistic antimicrobial activity of magainin 2 and PGLa peptides is rooted in the formation of supramolecular complexes with lipids. Sci Rep 2020; 10:11652. [PMID: 32669585 PMCID: PMC7363891 DOI: 10.1038/s41598-020-68416-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 06/22/2020] [Indexed: 11/21/2022] Open
Abstract
Magainin 2 and PGLa are cationic, amphipathic antimicrobial peptides which when added as equimolar mixture exhibit a pronounced synergism in both their antibacterial and pore-forming activities. Here we show for the first time that the peptides assemble into defined supramolecular structures along the membrane interface. The resulting mesophases are quantitatively described by state-of-the art fluorescence self-quenching and correlation spectroscopies. Notably, the synergistic behavior of magainin 2 and PGLa correlates with the formation of hetero-domains and an order-of-magnitude increased membrane affinity of both peptides. Enhanced membrane association of the peptide mixture is only observed in the presence of phophatidylethanolamines but not of phosphatidylcholines, lipids that dominate bacterial and eukaryotic membranes, respectively. Thereby the increased membrane-affinity of the peptide mixtures not only explains their synergistic antimicrobial activity, but at the same time provides a new concept to increase the therapeutic window of combinatorial drugs.
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Ma W, Sun S, Li W, Zhang Z, Lin Z, Xia Y, Yuan B, Yang K. Individual Roles of Peptides PGLa and Magainin 2 in Synergistic Membrane Poration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:7190-7199. [PMID: 32529830 DOI: 10.1021/acs.langmuir.0c00194] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Synergy between antimicrobial peptides PGLa and Magainin 2 (MAG2) provides an efficient way to enhance their antimicrobial ability. However, the underlying molecular mechanism of such synergy, especially the individual roles of each peptide, remains poorly understood. We combined a giant unilamellar vesicle leakage assay, in situ interfacial photovoltage testing, and molecular dynamics to investigate membrane poration under the action of PGLa, MAG2, or a PGLa/MAG2 mixture. Our results clearly show the different membrane action modes of the three systems and demonstrate the importance of forming PGLa-MAG2 heterodimers in the membrane poration process. PGLa inserted into and extracted from a membrane rapidly and continually with minimal aggregation and produced only transient, small pores. In contrast, MAG2 peptides tended to aggregate together on the membrane surface or only shallowly embed in the membrane. Additionally, the PGLa and MAG2 residues were well integrated into the membrane via the formation of PGLa-MAG2 heterodimers. The membrane defect produced by the rapid insertion of PGLa was stabilized by MAG2, which further recruited other peptides for the formation of PGLa-MAG2 heterodimers and even heterodimer clusters. Growth in pore size then occurred in a step-by-step process involving the formation and assembly of heterodimer clusters within the membrane. Our results provide insight into the complicated synergy that occurs between PGLa and MAG2 during membrane poration and will assist in the design of new antimicrobial peptides.
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Affiliation(s)
- Wendong Ma
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China
| | - Shuqing Sun
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China
| | - Wenwen Li
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China
| | - Zhihong Zhang
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China
| | - Zhao Lin
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China
| | - Yu Xia
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China
| | - Bing Yuan
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China
| | - Kai Yang
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou 215006, P. R. China
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Heterodimer and pore formation of magainin 2 and PGLa: The anchoring and tilting of peptides in lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183305. [DOI: 10.1016/j.bbamem.2020.183305] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 03/30/2020] [Accepted: 04/07/2020] [Indexed: 01/13/2023]
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2 H NMR of oriented phospholipid/cholesterol bilayers containing an amphiphilic peptide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183196. [DOI: 10.1016/j.bbamem.2020.183196] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 12/17/2019] [Accepted: 01/10/2020] [Indexed: 10/25/2022]
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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] [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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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] [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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Salnikov ES, Aisenbrey C, Pokrandt B, Brügger B, Bechinger B. Structure, Topology, and Dynamics of Membrane-Inserted Polypeptides and Lipids by Solid-State NMR Spectroscopy: Investigations of the Transmembrane Domains of the DQ Beta-1 Subunit of the MHC II Receptor and of the COP I Protein p24. Front Mol Biosci 2019; 6:83. [PMID: 31608287 PMCID: PMC6769064 DOI: 10.3389/fmolb.2019.00083] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Accepted: 08/23/2019] [Indexed: 01/04/2023] Open
Abstract
MHC class II receptors carry important function in adaptive immunity and their malfunctioning is associated with diabetes type I, chronic inflammatory diseases and other autoimmune diseases. The protein assembles from the DQ alpha-1 and DQ beta-1 subunits where the transmembrane domains of these type I membrane proteins have been shown to be involved in homo- and heterodimer formation. Furthermore, the DQ alpha 1 chain carries a sequence motif that has been first identified in the context of p24, a protein involved in the formation of COPI vesicles of the intracellular transport machinery, to specifically interact with sphingomyelin-C18 (SM-C18). Here we investigated the membrane interactions and dynamics of DQ beta-1 in liquid crystalline POPC phospholipid bilayers by oriented 15N solid-state NMR spectroscopy. The 15N resonances are indicative of a helical tilt angle of the membrane anchor sequence around 20°. Two populations can be distinguished by their differential dynamics probably corresponding the DQ beta-1 mono- and homodimer. Whereas, this equilibrium is hardly affected by the addition of 5 mole% SM-C18 a single population is visible in DMPC lipid bilayers suggesting that the lipid saturation is an important parameter. Furthermore, the DQ alpha-1, DQ beta-1 and p24 transmembrane helical domains were reconstituted into POPC or POPC/SM-C18 lipid bilayers where the fatty acyl chain of either the phosphatidylcholine or of the sphingolipid have been deuterated. Interestingly in the presence of both sphingolipid and polypeptide a strong decrease in the innermost membrane order of the POPC palmitoyl chain is observed, an effect that is strongest for DQ beta-1. In contrast, for the first time the polypeptide interactions were monitored by deuteration of the stearoyl chain of SM-C18. The resulting 2H solid-state NMR spectra show an increase in order for p24 and DQ alpha-1 which both carry the SM recognition motif. Thereby the data are suggestive that SM-C18 together with the transmembrane domains form structures imposing positive curvature strain on the surrounding POPC lipids. This effect is attenuated when SM-C18 is recognized by the protein.
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Affiliation(s)
- Evgeniy S Salnikov
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, Strasbourg, France
| | | | - Bianca Pokrandt
- Biochemiezentrum der Universität Heidelberg, Heidelberg, Germany
| | - Britta Brügger
- Biochemiezentrum der Universität Heidelberg, Heidelberg, Germany
| | - Burkhard Bechinger
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, Strasbourg, France
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Ilyas H, Kim J, Lee D, Malmsten M, Bhunia A. Structural insights into the combinatorial effects of antimicrobial peptides reveal a role of aromatic-aromatic interactions in antibacterial synergism. J Biol Chem 2019; 294:14615-14633. [PMID: 31383740 DOI: 10.1074/jbc.ra119.009955] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 08/02/2019] [Indexed: 01/10/2023] Open
Abstract
The recent development of plants that overexpress antimicrobial peptides (AMPs) provides opportunities for controlling plant diseases. Because plants employ a broad-spectrum antimicrobial defense, including those based on AMPs, transgenic modification for AMP overexpression represents a potential way to utilize a defense system already present in plants. Herein, using an array of techniques and approaches, we report on VG16KRKP and KYE28, two antimicrobial peptides, which in combination exhibit synergistic antimicrobial effects against plant pathogens and are resistant against plant proteases. Investigating the structural origin of these synergistic antimicrobial effects with NMR spectroscopy of the complex formed between these two peptides and their mutated analogs, we demonstrate the formation of an unusual peptide complex, characterized by the formation of a bulky hydrophobic hub, stabilized by aromatic zippers. Using three-dimensional structure analyses of the complex in bacterial outer and inner membrane components and when bound to lipopolysaccharide (LPS) or bacterial membrane mimics, we found that this structure is key for elevating antimicrobial potency of the peptide combination. We conclude that the synergistic antimicrobial effects of VG16KRKP and KYE28 arise from the formation of a well-defined amphiphilic dimer in the presence of LPS and also in the cytoplasmic bacterial membrane environment. Together, these findings highlight a new application of solution NMR spectroscopy to solve complex structures to study peptide-peptide interactions, and they underscore the importance of structural insights for elucidating the antimicrobial effects of AMP mixtures.
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Affiliation(s)
- Humaira Ilyas
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata 700054, India
| | - JaeWoong Kim
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 139743, Korea
| | - DongKuk Lee
- Department of Fine Chemistry, Seoul National University of Science and Technology, Seoul 139743, Korea
| | - Martin Malmsten
- Department of Pharmacy, Uppsala University, SE-75123 Uppsala, Sweden .,Department of Pharmacy, University of Copenhagen, DK 2100, Copenhagen, Denmark
| | - Anirban Bhunia
- Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII (M), Kolkata 700054, India
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Salnikov ES, Aussenac F, Abel S, Purea A, Tordo P, Ouari O, Bechinger B. Dynamic Nuclear Polarization / solid-state NMR of membranes. Thermal effects and sample geometry. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2019; 100:70-76. [PMID: 30995597 DOI: 10.1016/j.ssnmr.2019.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 03/18/2019] [Accepted: 03/18/2019] [Indexed: 06/09/2023]
Abstract
Whereas specially designed dinitroxide biradicals, reconstitution protocols, oriented sample geometries and NMR probes have helped to much increase the DNP enhancement factors of membrane samples they still lag considerably behind those obtained from glasses made of protein solutions. Here we show that not only the MAS rotor material but also the distribution of the membrane samples within the NMR rotor have a pronounced effect on the DNP enhancement. These observations are rationalized with the cooling efficiency and the internal properties of the sample, monitored by their T1 relaxation, microwave ON versus OFF signal intensities and DNP effect. The data are suggestive that for membranes the speed of cooling has a pronounced effect on the membrane properties and concomitantly the distribution of biradicals within the sample.
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Affiliation(s)
| | | | - Sebastian Abel
- Aix-Marseille University, CNRS, UMR 7273, Institut de Chimie Radicalaire, 13013, Marseille, France
| | | | - Paul Tordo
- Aix-Marseille University, CNRS, UMR 7273, Institut de Chimie Radicalaire, 13013, Marseille, France
| | - Olivier Ouari
- Aix-Marseille University, CNRS, UMR 7273, Institut de Chimie Radicalaire, 13013, Marseille, France
| | - Burkhard Bechinger
- Institute of Chemistry, University of Strasbourg / CNRS, UMR7177, 67070, Strasbourg, France.
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Solid-State NMR Approaches to Study Protein Structure and Protein-Lipid Interactions. Methods Mol Biol 2019. [PMID: 31218633 DOI: 10.1007/978-1-4939-9512-7_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Solid-state NMR spectroscopy has been developed for the investigation of membrane-associated polypeptides and remains one of the few techniques to reveal high-resolution structural information in liquid-disordered phospholipid bilayers. In particular, oriented samples have been used to investigate the structure, dynamics and topology of membrane polypeptides. Much of the previous solid-state NMR work has been developed and performed on peptides but the technique is constantly expanding towards larger membrane proteins. Here, a number of protocols are presented describing among other the reconstitution of membrane proteins into oriented membranes, monitoring membrane alignment by 31P solid-state NMR spectroscopy, investigations of the protein by one- and two-dimensional 15N solid-state NMR and measurements of the lipid order parameters using 2H solid-state NMR spectroscopy. Using such methods solid-state NMR spectroscopy has revealed a detailed picture of the ensemble of both lipids and proteins and their mutual interdependence in the bilayer environment.
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Aisenbrey C, Salnikov ES, Bechinger B. Solid-State NMR Investigations of the MHC II Transmembrane Domains: Topological Equilibria and Lipid Interactions. J Membr Biol 2019; 252:371-384. [PMID: 31187155 DOI: 10.1007/s00232-019-00071-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Accepted: 05/25/2019] [Indexed: 10/26/2022]
Abstract
The major histocompatibility complex class II (MHC II) membrane proteins are key players in the adaptive immune response. An aberrant function of these molecules is associated with a large number of autoimmune diseases such as diabetes type I and chronic inflammatory diseases. The MHC class II is assembled from DQ alpha 1 and DQ beta 1 which come together as a heterodimer through GXXXG-mediated protein-protein interactions and a highly specific protein-sphingomyelin-C18 interaction motif located on DQA1. This association can have important consequences in regulating the function of these membrane proteins. Here, we investigated the structure and topology of the DQA1 and DQB1 transmembrane helical domains by CD-, oriented 2H and 15N solid-state NMR spectroscopies. The spectra at peptide-to-lipid ratios of 0.5 to 2 mol% are indicative of a topological equilibrium involving a helix crossing the membrane with a tilt angle of about 20° and another transmembrane topology with around 30° tilt. The latter is probably representing a dimer. Furthermore, at the lowest peptide-to-lipid ratio, a third polypeptide population becomes obvious. Interestingly, the DQB1 and to a lesser extent the DQA1 transmembrane helical domains exhibit a strong fatty acyl chain disordering effect on the inner segments of the 2H-labelled palmitoyl chain of POPC bilayers. This phosphatidylcholine disordering requires the presence of sphingomyelin-C18 suggesting that the ensemble of transmembrane polypeptide and sphingolipid exerts positive curvature strain.
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Affiliation(s)
- Christopher Aisenbrey
- Institut de Chimie, Université de Strasbourg/CNRS, UMR7177, 4, Rue Blaise Pascal, 67070, Strasbourg, France
| | - Evgeniy S Salnikov
- Institut de Chimie, Université de Strasbourg/CNRS, UMR7177, 4, Rue Blaise Pascal, 67070, Strasbourg, France
| | - Burkhard Bechinger
- Institut de Chimie, Université de Strasbourg/CNRS, UMR7177, 4, Rue Blaise Pascal, 67070, Strasbourg, France.
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Puthumadathil N, Jayasree P, Santhosh Kumar K, Nampoothiri KM, Bajaj H, Mahendran KR. Detecting the structural assembly pathway of human antimicrobial peptide pores at single-channel level. Biomater Sci 2019; 7:3226-3237. [PMID: 31165117 DOI: 10.1039/c9bm00181f] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The pore-forming structures of an anionic human antimicrobial peptide dermcidin (DCD) in a membrane environment has not been demonstrated previously. Using single-channel electrical recordings, we characterized the structural and functional properties of the DCD peptide channel in lipid membranes. We show that a 48-residue, 8 nm long anionic DCD-1L peptide is folded in the right conformation in sodium dodecyl sulfate (SDS) that spontaneously inserts into lipid bilayers to form well-defined channels. However, the DCD-1L peptides are not properly folded in n-dodecyl-β-d-maltoside (DDM), resulting in unstable channels suggesting the significance of specific detergent in stable channel formation. Furthermore, a 25-residue cationic DCD SSL-25 peptide formed channels both in SDS and DDM micelles as the length of the peptide matches with the thickness of the membrane. Finally, we quantified the permeation of small molecules through the DCD channels in liposome assays. Accordingly, we propose a molecular model demonstrating the structural self-assembly of the DCD channels in the membrane. We suggest that an understanding of the mechanism of action of DCD peptides at single-channel resolution will lead to developing peptide-based therapeutics.
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Affiliation(s)
- Neethu Puthumadathil
- Membrane Biology Laboratory, Interdisciplinary Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695014, India. and Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Poornendhu Jayasree
- Membrane Biology Laboratory, Interdisciplinary Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695014, India.
| | - K Santhosh Kumar
- Membrane Biology Laboratory, Interdisciplinary Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695014, India.
| | - K Madhavan Nampoothiri
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Thiruvananthapuram 695019, India
| | - Harsha Bajaj
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Thiruvananthapuram 695019, India
| | - Kozhinjampara R Mahendran
- Membrane Biology Laboratory, Interdisciplinary Research Program, Rajiv Gandhi Centre for Biotechnology, Thiruvananthapuram 695014, India.
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Salnikov ES, Aisenbrey C, Anantharamaiah G, Bechinger B. Solid-state NMR structural investigations of peptide-based nanodiscs and of transmembrane helices in bicellar arrangements. Chem Phys Lipids 2019; 219:58-71. [DOI: 10.1016/j.chemphyslip.2019.01.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/29/2019] [Accepted: 01/29/2019] [Indexed: 02/08/2023]
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Varga JFA, Bui-Marinos MP, Katzenback BA. Frog Skin Innate Immune Defences: Sensing and Surviving Pathogens. Front Immunol 2019; 9:3128. [PMID: 30692997 PMCID: PMC6339944 DOI: 10.3389/fimmu.2018.03128] [Citation(s) in RCA: 94] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Accepted: 12/18/2018] [Indexed: 01/26/2023] Open
Abstract
Amphibian skin is a mucosal surface in direct and continuous contact with a microbially diverse and laden aquatic and/or terrestrial environment. As such, frog skin is an important innate immune organ and first line of defence against pathogens in the environment. Critical to the innate immune functions of frog skin are the maintenance of physical, chemical, cellular, and microbiological barriers and the complex network of interactions that occur across all the barriers. Despite the global decline in amphibian populations, largely as a result of emerging infectious diseases, we understand little regarding the cellular and molecular mechanisms that underlie the innate immune function of amphibian skin and defence against pathogens. In this review, we discuss the structure, cell composition and cellular junctions that contribute to the skin physical barrier, the antimicrobial peptide arsenal that, in part, comprises the chemical barrier, the pattern recognition receptors involved in recognizing pathogens and initiating innate immune responses in the skin, and the contribution of commensal microbes on the skin to pathogen defence. We briefly discuss the influence of environmental abiotic factors (natural and anthropogenic) and pathogens on the immunocompetency of frog skin defences. Although some aspects of frog innate immunity, such as antimicrobial peptides are well-studied; other components and how they contribute to the skin innate immune barrier, are lacking. Elucidating the complex network of interactions occurring at the interface of the frog's external and internal environments will yield insight into the crucial role amphibian skin plays in host defence and the environmental factors leading to compromised barrier integrity, disease, and host mortality.
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Affiliation(s)
- Joseph F A Varga
- Department of Biology, University of Waterloo, Waterloo, ON, Canada
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Aisenbrey C, Marquette A, Bechinger B. The Mechanisms of Action of Cationic Antimicrobial Peptides Refined by Novel Concepts from Biophysical Investigations. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1117:33-64. [PMID: 30980352 DOI: 10.1007/978-981-13-3588-4_4] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Even 30 years after the discovery of magainins, biophysical and structural investigations on how these peptides interact with membranes can still bear surprises and add new interesting detail to how these peptides exert their antimicrobial action. Early on, using oriented solid-state NMR spectroscopy, it was found that the amphipathic helices formed by magainins are active when being oriented parallel to the membrane surface. More recent investigations indicate that this in-planar alignment is also found when PGLa and magainin in combination exert synergistic pore-forming activities, where studies on the mechanism of synergistic interaction are ongoing. In a related manner, the investigation of dimeric antimicrobial peptide sequences has become an interesting topic of research which bears promise to refine our views how antimicrobial action occurs. The molecular shape concept has been introduced to explain the effects of lipids and peptides on membrane morphology, locally and globally, and in particular of cationic amphipathic helices that partition into the membrane interface. This concept has been extended in this review to include more recent ideas on soft membranes that can adapt to external stimuli including membrane-disruptive molecules. In this manner, the lipids can change their shape in the presence of low peptide concentrations, thereby maintaining the bilayer properties. At higher peptide concentrations, phase transitions occur which lead to the formation of pores and membrane lytic processes. In the context of the molecular shape concept, the properties of lipopeptides, including surfactins, are shortly presented, and comparisons with the hydrophobic alamethicin sequence are made.
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Affiliation(s)
| | - Arnaud Marquette
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, Strasbourg, France
| | - Burkhard Bechinger
- Université de Strasbourg/CNRS, UMR7177, Institut de Chimie, Strasbourg, France. .,Faculté de chimie, Institut le Bel, Strasbourg, France.
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