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Koynarev V, Borgos KKA, Kohlbrecher J, Porcar L, Nielsen JE, Lund R. Antimicrobial Peptides Increase Line Tension in Raft-Forming Lipid Membranes. J Am Chem Soc 2024; 146:20891-20903. [PMID: 39018511 PMCID: PMC11295182 DOI: 10.1021/jacs.4c05377] [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: 04/19/2024] [Revised: 07/01/2024] [Accepted: 07/02/2024] [Indexed: 07/19/2024]
Abstract
The formation of phase separated membrane domains is believed to be essential for the function of the cell. The precise composition and physical properties of lipid bilayer domains play crucial roles in regulating protein activity and governing cellular processes. Perturbation of the domain structure in human cells can be related to neurodegenerative diseases and cancer. Lipid rafts are also believed to be essential in bacteria, potentially serving as targets for antibiotics. An important question is how the membrane domain structure is affected by bioactive and therapeutic molecules, such as surface-active peptides, which target cellular membranes. Here we focus on antimicrobial peptides (AMPs), crucial components of the innate immune system, to gain insights into their interaction with model lipid membranes containing domains. Using small-angle neutron/X-ray scattering (SANS/SAXS), we show that the addition of several natural AMPs (indolicidin, LL-37, magainin II, and aurein 2.2) causes substantial growth and restructuring of the domains, which corresponds to increased line tension. Contrast variation SANS and SAXS results demonstrate that the peptide inserts evenly in both phases, and the increased line tension can be related to preferential and concentration dependent thinning of the unsaturated membrane phase. We speculate that the lateral restructuring caused by the AMPs may have important consequences in affecting physiological functions of real cells. This work thus shines important light onto the complex interactions and lateral (re)organization in lipid membranes, which is relevant for a molecular understanding of diseases and the action of antibiotics.
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Affiliation(s)
| | | | - Joachim Kohlbrecher
- Laboratory
for Neutron Scattering and Imaging, Paul
Scherrer Institut, Villigen 5232, Switzerland
| | - Lionel Porcar
- Institut
Laue-Langevin, 71 Av. des Martyrs, 38000 Grenoble, France
| | | | - Reidar Lund
- Department
of Chemistry, University of Oslo, Postboks 1033 Blindern, 0315 Oslo, Norway
- Hylleraas
Centre for Quantum Molecular Sciences, University
of Oslo, Postboks 1033 Blindern, 0315 Oslo, Norway
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2
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Caselli L, Conti L, De Santis I, Berti D. Small-angle X-ray and neutron scattering applied to lipid-based nanoparticles: Recent advancements across different length scales. Adv Colloid Interface Sci 2024; 327:103156. [PMID: 38643519 DOI: 10.1016/j.cis.2024.103156] [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: 10/19/2023] [Revised: 02/28/2024] [Accepted: 04/08/2024] [Indexed: 04/23/2024]
Abstract
Lipid-based nanoparticles (LNPs), ranging from nanovesicles to non-lamellar assemblies, have gained significant attention in recent years, as versatile carriers for delivering drugs, vaccines, and nutrients. Small-angle scattering methods, employing X-rays (SAXS) or neutrons (SANS), represent unique tools to unveil structure, dynamics, and interactions of such particles on different length scales, spanning from the nano to the molecular scale. This review explores the state-of-the-art on scattering methods applied to unveil the structure of lipid-based nanoparticles and their interactions with drugs and bioactive molecules, to inform their rational design and formulation for medical applications. We will focus on complementary information accessible with X-rays or neutrons, ranging from insights on the structure and colloidal processes at a nanoscale level (SAXS) to details on the lipid organization and molecular interactions of LNPs (SANS). In addition, we will review new opportunities offered by Time-resolved (TR)-SAXS and -SANS for the investigation of dynamic processes involving LNPs. These span from real-time monitoring of LNPs structural evolution in response to endogenous or external stimuli (TR-SANS), to the investigation of the kinetics of lipid diffusion and exchange upon interaction with biomolecules (TR-SANS). Finally, we will spotlight novel combinations of SAXS and SANS with complementary on-line techniques, recently enabled at Large Scale Facilities for X-rays and neutrons. This emerging technology enables synchronized multi-method investigation, offering exciting opportunities for the simultaneous characterization of the structure and chemical or mechanical properties of LNPs.
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Affiliation(s)
- Lucrezia Caselli
- Physical Chemistry 1, University of Lund, S-221 00 Lund, Sweden.
| | - Laura Conti
- Consorzio Sistemi a Grande Interfase, Department of Chemistry, University of Florence, Sesto Fiorentino, Italy
| | - Ilaria De Santis
- Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, Florence 50019, Italy
| | - Debora Berti
- Department of Chemistry, University of Florence, Via della Lastruccia 3, Sesto Fiorentino, Florence 50019, Italy; Consorzio Sistemi a Grande Interfase, Department of Chemistry, University of Florence, Sesto Fiorentino, Italy.
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3
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Semeraro EF, Frewein MPK, Pabst G. Structure of symmetric and asymmetric lipid membranes from joint SAXS/SANS. Methods Enzymol 2024; 700:349-383. [PMID: 38971607 DOI: 10.1016/bs.mie.2024.02.017] [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] [Indexed: 07/08/2024]
Abstract
Small-angle X-ray and neutron scattering (SAXS/SANS) techniques excel in unveiling intricate details of the internal structure of lipid membranes under physiologically relevant temperature and buffer conditions, all without the need to resort to bulky labels. By concurrently conducting and analyzing neutron and X-ray data, these methods harness the complete spectrum of contrast and resolution from various components constituting lipid membranes. Despite this, the literature exhibits only a sparse presence of applications compared to other techniques in membrane biophysics. This chapter serves as a primer for conducting joint SAXS/SANS analyses on symmetric and asymmetric large unilamellar vesicles, elucidating fundamental elements of the analysis process. Specifically, we introduce the basics of interactions of X-rays and neutrons with matter that lead to the scattering contrast and a description of membrane structure in terms of scattering length density profiles. These profiles allow fitting of the experimentally observed scattering intensity. We further integrate practical insights, unveiling strategies for successful data acquisition and providing a comprehensive assessment of the technique's advantages and drawbacks. By amalgamating theoretical underpinnings with practical considerations, this chapter aims to dismantle barriers hindering the adoption of joint SAXS/SANS approaches, thereby encouraging an influx of studies in this domain.
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Affiliation(s)
- Enrico F Semeraro
- Institute of Molecular Bioscience, NAWI Graz, University of Graz, Graz, Austria; Field of Excellence BioHealth-University of Graz, Graz, Austria
| | - Moritz P K Frewein
- Institute of Molecular Bioscience, NAWI Graz, University of Graz, Graz, Austria; Field of Excellence BioHealth-University of Graz, Graz, Austria
| | - Georg Pabst
- Institute of Molecular Bioscience, NAWI Graz, University of Graz, Graz, Austria; Field of Excellence BioHealth-University of Graz, Graz, Austria.
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4
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Häfner G, Müller M. Reaction-driven assembly: controlling changes in membrane topology by reaction cycles. SOFT MATTER 2023; 19:7281-7292. [PMID: 37605887 DOI: 10.1039/d3sm00876b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Chemical reaction cycles are prototypical examples how to drive systems out of equilibrium and introduce novel, life-like properties into soft-matter systems. We report simulations of amphiphilic molecules in aqueous solution. The molecule's head group is permanently hydrophilic, whereas the reaction cycle switches the molecule's tail from hydrophilic (precursor) to hydrophobic (amphiphile) and vice versa. The reaction cycle leads to an arrest in coalescence and results in uniform vesicle sizes that can be controlled by the reaction rate. Using a continuum description and particle-based simulation, we study the scaling of the vesicle size with the reaction rate. The chemically active vesicles are inflated by precursor, imparting tension onto the membrane and, for specific parameters, stabilize pores.
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Affiliation(s)
- Gregor Häfner
- Institute for Theoretical Physics, Georg-August University, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
- Max Planck School Matter to Life, Jahnstraße 29, 69120 Heidelberg, Germany
| | - Marcus Müller
- Institute for Theoretical Physics, Georg-August University, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
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5
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Ehm T, Philipp J, Barkey M, Ober M, Brinkop AT, Simml D, von Westphalen M, Nickel B, Beck R, Rädler JO. 3D-printed SAXS chamber for controlled in situ dialysis and optical characterization. JOURNAL OF SYNCHROTRON RADIATION 2022; 29:1014-1019. [PMID: 35787568 PMCID: PMC9255564 DOI: 10.1107/s1600577522005136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 05/12/2022] [Indexed: 06/15/2023]
Abstract
3D printing changes the scope of how samples can be mounted for small-angle X-ray scattering (SAXS). In this paper a 3D-printed X-ray chamber, which allows for in situ exchange of buffer and in situ optical transmission spectroscopy, is presented. The chamber is made of cyclic olefin copolymers (COC), including COC X-ray windows providing ultra-low SAXS background. The design integrates a membrane insert for in situ dialysis of the 100 µl sample volume against a reservoir, which enables measurements of the same sample under multiple conditions using an in-house X-ray setup equipped with a 17.4 keV molybdenum source. The design's capabilities are demonstrated by measuring reversible structural changes in lipid and polymer systems as a function of salt concentration and pH. In the same chambers optical light transmission spectroscopy was carried out measuring the optical turbidity of the mesophases and local pH values using pH-responsive dyes. Microfluidic exchange and optical spectroscopy combined with in situ X-ray scattering enables vast applications for the study of responsive materials.
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Affiliation(s)
- Tamara Ehm
- School of Physics and Astronomy, Center for Physics and Chemistry of Living Systems, and Center for Nanoscience and Nanotechnology, Tel Aviv University, Ramat Aviv, Israel
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
| | - Julian Philipp
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
| | - Martin Barkey
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
| | - Martina Ober
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
| | - Achim Theo Brinkop
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
| | - David Simml
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
| | - Miriam von Westphalen
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
| | - Bert Nickel
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
| | - Roy Beck
- School of Physics and Astronomy, Center for Physics and Chemistry of Living Systems, and Center for Nanoscience and Nanotechnology, Tel Aviv University, Ramat Aviv, Israel
| | - Joachim O. Rädler
- Faculty of Physics, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, Munich, Germany
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6
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Ye Z, Wu Z, Jayaraman A. Computational Reverse Engineering Analysis for Scattering Experiments (CREASE) on Vesicles Assembled from Amphiphilic Macromolecular Solutions. JACS AU 2021; 1:1925-1936. [PMID: 34841410 PMCID: PMC8611670 DOI: 10.1021/jacsau.1c00305] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Indexed: 05/25/2023]
Abstract
In this paper we present the development and validation of the "Computational Reverse-Engineering Analysis for Scattering Experiments" (CREASE) method for analyzing scattering results from vesicle structures that are commonly found upon assembly of synthetic, biomimetic, or bioderived amphiphilic copolymers in solution. The two-step CREASE method takes the amphiphilic polymer chemistry and small-angle scattering intensity profile, I exp(q), as input and determines the vesicles' structural features on multiple length scales ranging from assembled vesicle wall's individual layer thicknesses to the monomer-level packing and distribution of polymer conformations. In the first step of CREASE, a genetic algorithm (GA) is used to determine the relevant vesicle dimensions from the input macromolecular solution information and I exp(q) by identifying the structure whose computed scattering profile best matches the input I exp(q). Then in the second step, the GA-determined dimensions are used for molecular reconstruction of the vesicle structure. To validate CREASE for vesicles, we test CREASE on input scattering intensity profiles generated mathematically (termed as in silico I exp(q) vs q) from a variety of vesicle sizes with known dimensions. We also test CREASE on in silico I exp(q) vs q generated from vesicles with dispersity in all relevant dimensions, resembling real experiments. After successful validation of CREASE, we compare the CREASE-determined dimensions against those obtained from the traditional approach of fitting the scattering intensity profile to relevant analytical model in SASVIEW package. We show that CREASE performs better than or as well as the core-multishell analytical model's fitting in SASVIEW in determining vesicle dimensions with dispersity. We also show that CREASE provides structural information beyond those possible from traditional scattering analysis using the core-multishell model, such as the distribution of solvophilic monomers between the vesicle wall's inner and outer layers in the vesicle wall and the chain-level packing within each vesicle layer.
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Affiliation(s)
- Ziyu Ye
- Colburn
Laboratory, Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, Delaware 19716, United States
| | - Zijie Wu
- Colburn
Laboratory, Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, Delaware 19716, United States
| | - Arthi Jayaraman
- Colburn
Laboratory, Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy Street, Newark, Delaware 19716, United States
- Department
of Materials Science and Engineering, University
of Delaware, Newark, Delaware 19716, United States
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7
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Teiwes NK, Mey I, Baumann PC, Strieker L, Unkelbach U, Steinem C. Pore-Spanning Plasma Membranes Derived from Giant Plasma Membrane Vesicles. ACS APPLIED MATERIALS & INTERFACES 2021; 13:25805-25812. [PMID: 34043315 DOI: 10.1021/acsami.1c06404] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Giant plasma membrane vesicles (GPMVs) are a highly promising model system for the eukaryotic plasma membrane. The unresolved challenge, however, is a path to surface-based structures that allows accessibility to both sides of the plasma membrane through high-resolution techniques. Such an approach would pave the way to advanced chip-based technologies for the analysis of complex cell surfaces to study the roles of membrane proteins, host-pathogen interactions, and many other bioanalytical and sensing applications. This study reports the generation of planar supported plasma membranes and for the first-time pore-spanning plasma membranes (PSPMs) derived from pure GPMVs that are spread on activated solid and highly ordered porous silicon substrates. GPMVs were produced by two different vesiculation agents and were first investigated with respect to their growth behavior and phase separation. Second, these GPMVs were spread onto silicon substrates to form planar supported plasma membrane patches. PSPMs were obtained by spreading of pure GPMVs on oxygen-plasma activated porous substrates with pore diameters of 3.5 μm. Fluorescence micrographs unambiguously showed that the PSPMs partially phase separate in a mobile ordered phase surrounded by a disordered phase, which was supported by cholesterol extraction using methyl-β-cyclodextrin.
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Affiliation(s)
- Nikolas K Teiwes
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstaße 2, 37077 Göttingen, Germany
| | - Ingo Mey
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstaße 2, 37077 Göttingen, Germany
| | - Phila C Baumann
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstaße 2, 37077 Göttingen, Germany
| | - Lena Strieker
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstaße 2, 37077 Göttingen, Germany
| | - Ulla Unkelbach
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstaße 2, 37077 Göttingen, Germany
| | - Claudia Steinem
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstaße 2, 37077 Göttingen, Germany
- Max Planck Institute for Dynamics and Self-Organization, Am Fassberg 17, 37077 Göttingen, Germany
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