1
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Zimmer SE, Kowalczyk AP. The desmosome as a dynamic membrane domain. Curr Opin Cell Biol 2024; 90:102403. [PMID: 39079221 DOI: 10.1016/j.ceb.2024.102403] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 06/26/2024] [Accepted: 07/05/2024] [Indexed: 09/14/2024]
Abstract
Cell junctions integrate extracellular signals with intracellular responses to polarize tissues, pattern organs, and maintain tissue architecture by promoting cell-cell adhesion and communication. In this review, we explore the mechanisms whereby the adhesive junctions, adherens junctions and desmosomes, co-assemble and then segregate into unique plasma membrane domains. In addition, we highlight emerging evidence that these junctions are spatially and functionally integrated with the endoplasmic reticulum to mediate stress sensing and calcium homeostasis. We conclude with a discussion of the role of the endoplasmic reticulum in the mechanical stress response and how disruption of these connections may cause disease.
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Affiliation(s)
- Stephanie E Zimmer
- Departments of Dermatology and Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Andrew P Kowalczyk
- Departments of Dermatology and Cellular and Molecular Physiology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
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2
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Garza-Miyazato D, Hanashima S, Umegawa Y, Murata M, Kinoshita M, Matsumori N, Greimel P. Mode of molecular interaction of triterpenoid saponin ginsenoside Rh2 with membrane lipids in liquid-disordered phases. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184366. [PMID: 38960300 DOI: 10.1016/j.bbamem.2024.184366] [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: 02/03/2024] [Revised: 06/07/2024] [Accepted: 06/24/2024] [Indexed: 07/05/2024]
Abstract
Ginsenoside Rh2 (Rh2) is a ginseng saponin comprising a triterpene core and one unit of glucose and has attracted much attention due to its diverse biological activities. In the present study, we used small-angle X-ray diffraction, solid-state NMR, fluorescence microscopy, and MD simulations to investigate the molecular interaction of Rh2 with membrane lipids in the liquid-disordered (Ld) phase mainly composed of palmitoyloleoylphosphatidylcholine compared with those in liquid-ordered (Lo) phase mainly composed of sphingomyelin and cholesterol. The electron density profiles determined by X-ray diffraction patterns indicated that Rh2 tends to be present in the shallow interior of the bilayer in the Ld phase, while Rh2 accumulation was significantly smaller in the Lo phase. Order parameters at intermediate depths in the bilayer leaflet obtained from 2H NMR spectra and MD simulations indicated that Rh2 reduces the order of the acyl chains of lipids in the Ld phase. The dihydroxy group and glucose moiety at both ends of the hydrophobic triterpene core of Rh2 cause tilting of the molecular axis relative to the membrane normal, which may enhance membrane permeability by loosening the packing of lipid acyl chains. These features of Rh2 are distinct from steroidal saponins such as digitonin and dioscin, which exert strong membrane-disrupting activity.
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Affiliation(s)
- Darcy Garza-Miyazato
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Shinya Hanashima
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-cho Minami, Tottori 680-8552, Japan.
| | - Yuichi Umegawa
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Michio Murata
- Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan; Forefront Research Centre for Fundamental Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
| | - Masanao Kinoshita
- Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Nobuaki Matsumori
- Department of Chemistry, Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Peter Greimel
- Laboratory for Cell Function Dynamics, RIKEN Center for Brain Science, Wako, Saitama 351-0198, Japan
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3
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Sharma KD, Doktorova M, Waxham MN, Heberle FA. Cryo-EM images of phase-separated lipid bilayer vesicles analyzed with a machine-learning approach. Biophys J 2024; 123:2877-2891. [PMID: 38689500 PMCID: PMC11393711 DOI: 10.1016/j.bpj.2024.04.029] [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: 12/22/2023] [Revised: 03/08/2024] [Accepted: 04/26/2024] [Indexed: 05/02/2024] Open
Abstract
Lateral lipid heterogeneity (i.e., raft formation) in biomembranes plays a functional role in living cells. Three-component mixtures of low- and high-melting lipids plus cholesterol offer a simplified experimental model for raft domains in which a liquid-disordered (Ld) phase coexists with a liquid-ordered (Lo) phase. Using such models, we recently showed that cryogenic electron microscopy (cryo-EM) can detect phase separation in lipid vesicles based on differences in bilayer thickness. However, the considerable noise within cryo-EM data poses a significant challenge for accurately determining the membrane phase state at high spatial resolution. To this end, we have developed an image-processing pipeline that utilizes machine learning (ML) to predict the bilayer phase in projection images of lipid vesicles. Importantly, the ML method exploits differences in both the thickness and molecular density of Lo compared to Ld, which leads to improved phase identification. To assess accuracy, we used artificial images of phase-separated lipid vesicles generated from all-atom molecular dynamics simulations of Lo and Ld phases. Synthetic ground-truth data sets mimicking a series of compositions along a tieline of Ld + Lo coexistence were created and then analyzed with various ML models. For all tieline compositions, we find that the ML approach can correctly identify the bilayer phase with >90% accuracy, thus providing a means to isolate the intensity profiles of coexisting Ld and Lo phases, as well as accurately determine domain-size distributions, number of domains, and phase-area fractions. The method described here provides a framework for characterizing nanoscopic lateral heterogeneities in membranes and paves the way for a more detailed understanding of raft properties in biological contexts.
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Affiliation(s)
- Karan D Sharma
- Department of Chemistry, University of Tennessee, Knoxville, Tennessee
| | - Milka Doktorova
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - M Neal Waxham
- Department of Neurobiology and Anatomy, University of Texas Health Science Center, Houston, Texas
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4
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DiPasquale M, Marquardt D. Perceiving the functions of vitamin E through neutron and X-ray scattering. Adv Colloid Interface Sci 2024; 330:103189. [PMID: 38824717 DOI: 10.1016/j.cis.2024.103189] [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: 10/08/2023] [Revised: 05/14/2024] [Accepted: 05/17/2024] [Indexed: 06/04/2024]
Abstract
Take your vitamins, or don't? Vitamin E is one of the few lipophilic vitamins in the human diet and is considered an essential nutrient. Over the years it has proven to be a powerful antioxidant and is commercially used as such, but this association is far from linear in physiology. It is increasingly more likely that vitamin E has multiple legitimate biological roles. Here, we review past and current work using neutron and X-ray scattering to elucidate the influence of vitamin E on key features of model membranes that can translate to the biological function(s) of vitamin E. Although progress is being made, the hundred year-old mystery remains unsolved.
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Affiliation(s)
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ontario, Canada; Department of Physics, University of Windsor, Windsor, Ontario, Canada.
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5
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Kinnun JJ, Carrillo JMY, Collier CP, Smith MD, Katsaras J. Amantadine interactions with phase separated lipid membranes. Chem Phys Lipids 2024; 262:105397. [PMID: 38740276 DOI: 10.1016/j.chemphyslip.2024.105397] [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: 01/15/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/16/2024]
Abstract
Amantadine, a small amphilphic organic compound that consists of an adamantane backbone and an amino group, was first recognized as an antiviral in 1963 and received approval for prophylaxis against the type A influenza virus in 1976. Since then, it has also been used to treat Parkinson's disease-related dyskinesia and is being considered as a treatment for corona viruses. Since amantadine usually targets membrane-bound proteins, its interactions with the membrane are also thought to be important. Biological membranes are now widely understood to be laterally heterogeneous and certain proteins are known to preferentially co-localize within specific lipid domains. Does amantadine, therefore, preferentially localize in certain lipid composition domains? To address this question, we studied amantadine's interactions with phase separating membranes composed of cholesterol, DSPC (1,2-distearoyl-sn-glycero-3-phosphocholine), POPC (1-palmitoyl-2-oleoyl-glycero-3-phosphocholine), and DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine), as well as single-phase DPhPC (1,2-diphytanoyl-sn-glycero-3-phos-phocholine) membranes. From Langmuir trough and differential scanning calorimetry (DSC) measurements, we determined, respectively, that amantadine preferentially binds to disordered lipids, such as POPC, and lowers the phase transition temperature of POPC/DSPC/cholesterol mixtures, implying that amantadine increases membrane disorder. Further, using droplet interface bilayers (DIBs), we observed that amantadine disrupts DPhPC membranes, consistent with its disordering properties. Finally, we carried out molecular dynamics (MD) simulations on POPC/DSPC/cholesterol membranes with varying amounts of amantadine. Consistent with experiment, MD simulations showed that amantadine prefers to associate with disordered POPC-rich domains, domain boundaries, and lipid glycerol backbones. Since different proteins co-localize with different lipid domains, our results have possible implications as to which classes of proteins may be better targets for amantadine.
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Affiliation(s)
- Jacob J Kinnun
- Department of Chemistry, University of Tennessee, Knoxville, TN 37996, United States.
| | - Jan Michael Y Carrillo
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - C Patrick Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States
| | - Micholas Dean Smith
- Department of Biochemistry, Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, United States; UT/ORNL Center for Molecular Biophysics, Oak Ridge National Laboratory, Biosciences Division, Oak Ridge, TN 37831, United States
| | - John Katsaras
- Labs and Soft Matter Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States; Shull-Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States; Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, United States.
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6
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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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7
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Bepler T, Barrera MD, Rooney MT, Xiong Y, Kuang H, Goodell E, Goodwin MJ, Harbron E, Fu R, Mihailescu M, Narayanan A, Cotten ML. Antiviral activity of the host defense peptide piscidin 1: investigating a membrane-mediated mode of action. Front Chem 2024; 12:1379192. [PMID: 38988727 PMCID: PMC11233706 DOI: 10.3389/fchem.2024.1379192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 05/08/2024] [Indexed: 07/12/2024] Open
Abstract
Outbreaks of viral diseases are on the rise, fueling the search for antiviral therapeutics that act on a broad range of viruses while remaining safe to human host cells. In this research, we leverage the finding that the plasma membranes of host cells and the lipid bilayers surrounding enveloped viruses differ in lipid composition. We feature Piscidin 1 (P1), a cationic host defense peptide (HDP) that has antimicrobial effects and membrane activity associated with its N-terminal region where a cluster of aromatic residues and copper-binding motif reside. While few HDPs have demonstrated antiviral activity, P1 acts in the micromolar range against several enveloped viruses that vary in envelope lipid composition. Notably, it inhibits HIV-1, a virus that has an envelope enriched in cholesterol, a lipid associated with higher membrane order and stability. Here, we first document through plaque assays that P1 boasts strong activity against SARS-CoV-2, which has an envelope low in cholesterol. Second, we extend previous studies done with homogeneous bilayers and devise cholesterol-containing zwitterionic membranes that contain the liquid disordered (Ld; low in cholesterol) and ordered (Lo, rich in cholesterol) phases. Using dye leakage assays and cryo-electron microscopy on vesicles, we show that P1 has dramatic permeabilizing capability on the Lo/Ld, an effect matched by a strong ability to aggregate, fuse, and thin the membranes. Differential scanning calorimetry and NMR experiments demonstrate that P1 mixes the lipid content of vesicles and alters the stability of the Lo. Structural studies by NMR indicate that P1 interacts with the Lo/Ld by folding into an α-helix that lies parallel to the membrane surface. Altogether, these results show that P1 is more disruptive to phase-separated than homogenous cholesterol-containing bilayers, suggesting an ability to target domain boundaries. Overall, this multi-faceted research highlights how a peptide that interacts strongly with membranes through an aromatic-rich N-terminal motif disrupt viral envelope mimics. This represents an important step towards the development of novel peptides with broad-spectrum antiviral activity.
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Affiliation(s)
- Tristan Bepler
- New York Structural Biology Center, New York, NY, United States
| | - Michael D. Barrera
- School of Systems Biology, George Mason University, Manassas, VA, United States
| | - Mary T. Rooney
- Department of Applied Science, William & Mary, Williamsburg, VA, United States
- Department of Chemistry, Hofstra University, Hempstead, NY, United States
| | - Yawei Xiong
- Department of Applied Science, William & Mary, Williamsburg, VA, United States
| | - Huihui Kuang
- New York Structural Biology Center, New York, NY, United States
| | - Evan Goodell
- Department of Applied Science, William & Mary, Williamsburg, VA, United States
| | - Matthew J. Goodwin
- Department of Chemistry, William & Mary, Williamsburg, VA, United States
| | - Elizabeth Harbron
- Department of Chemistry, William & Mary, Williamsburg, VA, United States
| | - Riqiang Fu
- National High Magnetic Field Laboratory, Tallahassee, FL, United States
| | - Mihaela Mihailescu
- Institute for Bioscience and Biotechnology Research, Rockville, MD, United States
| | - Aarthi Narayanan
- Department of Biology, George Mason University, Manassas, VA, United States
| | - Myriam L. Cotten
- Department of Applied Science, William & Mary, Williamsburg, VA, United States
- Department of Biochemistry and Biophysics, Oregon State University, Corvallis, OR, United States
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8
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Lee S, Bak JH, Lee Y, Jeong DW, Lee J, Lee KK, Cho H, Lee HH, Hyeon C, Choi MC. Water Hydrogen-Bond Mediated Layer by Layer Alignment of Lipid Rafts as a Precursor of Intermembrane Processes. J Am Chem Soc 2024; 146:13846-13853. [PMID: 38652033 DOI: 10.1021/jacs.4c00544] [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: 04/25/2024]
Abstract
Lipid rafts, which are dynamic nanodomains in the plasma membrane, play a crucial role in intermembrane processes by clustering together and growing in size within the plane of the membrane while also aligning with each other across different membranes. However, the physical origin of layer by layer alignment of lipid rafts remains to be elucidated. Here, by using fluorescence imaging and synchrotron X-ray reflectivity in a phase-separated multilayer system, we find that the alignment of raft-mimicking Lo domains is regulated by the distance between bilayers. Molecular dynamics simulations reveal that the aligned state is energetically preferred when the intermembrane distance is small due to its ability to minimize the volume of surface water, which has fewer water hydrogen bonds (HBs) compared to bulk water. Our results suggest that water HB-driven alignment of lipid rafts plays a role as a precursor of intermembrane processes such as cell-cell fusion, virus entry, and signaling.
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Affiliation(s)
- Suho Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - Ji Hyun Bak
- School of Computational Science, Korea Institute for Advanced Study, Seoul 02455, Korea
| | - Yuno Lee
- School of Computational Science, Korea Institute for Advanced Study, Seoul 02455, Korea
| | - Dae-Woong Jeong
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - Jaehee Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - KeunMin Ken Lee
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - Hasaeam Cho
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
| | - Hyun Hwi Lee
- Pohang Accelerator Lab, POSTECH, Pohang 37673, Korea
| | - Changbong Hyeon
- School of Computational Science, Korea Institute for Advanced Study, Seoul 02455, Korea
| | - Myung Chul Choi
- Department of Bio and Brain Engineering, KAIST, Daejeon 34141, Korea
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9
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Kambar N, Go YK, Snyder C, Do MN, Leal C. Structural characterization of lateral phase separation in polymer-lipid hybrid membranes. Methods Enzymol 2024; 700:235-273. [PMID: 38971602 DOI: 10.1016/bs.mie.2024.04.023] [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
Hierarchic self-assembly is the main mechanism used to create diverse structures using soft materials. This is a case for both synthetic materials and biomolecular systems, as exemplified by the non-covalent organization of lipids into membranes. In nature, lipids often assemble into single bilayers, but other nanostructures are encountered, such as bilayer stacks and tubular and vesicular aggregates. Synthetic block copolymers can be engineered to recapitulate many of the structures, forms, and functions of lipid systems. When block copolymers are amphiphilic, they can be inserted or co-assembled into hybrid membranes that exhibit synergistic structural, permeability, and mechanical properties. One example is the emergence of lateral phase separation akin to the raft formation in biomembranes. When higher-order structures, such as hybrid membranes, are formed, this lateral phase separation can be correlated across membranes in the stack. This chapter outlines a set of important methods, such as X-ray Scattering, Atomic Force Microscopy, and Cryo-Electron Microscopy, that are relevant to characterizing and evaluating lateral and correlated phase separation in hybrid membranes at the nano and mesoscales. Understanding the phase behavior of polymer-lipid hybrid materials could lead to innovative advancements in biomimetic membrane separation systems.
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Affiliation(s)
- Nurila Kambar
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Yoo Kyung Go
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Corey Snyder
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Minh N Do
- Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States
| | - Cecília Leal
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, United States.
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10
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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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11
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Suresh P, London E. MαCD-based plasma membrane outer leaflet lipid exchange in mammalian cells to study insulin receptor activity. Methods Enzymol 2024; 700:485-507. [PMID: 38971611 DOI: 10.1016/bs.mie.2024.03.027] [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
Signaling receptors on the plasma membrane, such as insulin receptor, can have their activity modulated to some extent by their surrounding lipids. Studying the contribution of membrane lipid properties such as presence of ordered lipid domains or bilayer thickness on the activity of receptors has been a challenging objective in living cells. Using methyl-alpha cyclodextrin-mediated lipid exchange, we are able to alter the lipids of the outer leaflet plasma membrane of mammalian cells to investigate the effect of the properties of the exchanged lipid upon receptor function in live cells. In this article, we describe the technique of lipid exchange in detail and how it can be applied to better understand lipid-mediated regulation of insulin receptor activity in cells.
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Affiliation(s)
- Pavana Suresh
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States.
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, United States
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12
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Heberle FA, Waxham MN. Phase separation in model lipid membranes investigated with cryogenic electron microscopy. Methods Enzymol 2024; 700:189-216. [PMID: 38971600 DOI: 10.1016/bs.mie.2024.03.003] [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
We describe a method for investigating lateral membrane heterogeneity using cryogenic electron microscopy (cryo-EM) images of liposomes. The method takes advantage of differences in the thickness and molecular density of ordered and disordered phases that are resolvable in phase contrast cryo-EM. Compared to biophysical techniques like FRET or neutron scattering that yield ensemble-averaged information, cryo-EM provides direct visualization of individual vesicles and can therefore reveal variability that would otherwise be obscured by averaging. Moreover, because the contrast mechanism involves inherent properties of the lipid phases themselves, no extrinsic probes are required. We explain and discuss various complementary analyses of spatially resolved thickness and intensity measurements that enable an assessment of the membrane's phase state. The method opens a window to nanodomain structure in synthetic and biological membranes that should lead to an improved understanding of lipid raft phenomena.
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Affiliation(s)
- Frederick A Heberle
- Department of Chemistry, University of Tennessee, Knoxville, TN, United States.
| | - M Neal Waxham
- Department of Neurobiology and Anatomy, University of Texas Health Science Center, Houston, TX, United States.
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13
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Collier CP, Bolmatov D, Elkins JG, Katsaras J. Nanoscopic lipid domains determined by microscopy and neutron scattering. Methods 2024; 223:127-135. [PMID: 38331125 DOI: 10.1016/j.ymeth.2024.01.020] [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: 11/07/2023] [Revised: 01/22/2024] [Accepted: 01/26/2024] [Indexed: 02/10/2024] Open
Abstract
Biological membranes are highly complex supramolecular assemblies, which play central roles in biology. However, their complexity makes them challenging to study their nanoscale structures. To overcome this challenge, model membranes assembled using reduced sets of membrane-associated biomolecules have been found to be both excellent and tractable proxies for biological membranes. Due to their relative simplicity, they have been studied using a range of biophysical characterization techniques. In this review article, we will briefly detail the use of fluorescence and electron microscopies, and X-ray and neutron scattering techniques used over the past few decades to study the nanostructure of biological membranes.
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Affiliation(s)
- Charles P Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Dima Bolmatov
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - James G Elkins
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - John Katsaras
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Neutron Scattering Division, Oak Ridge National Laboratorry, Oak Ridege, TN, USA
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14
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Wagner AM, Kostina NY, Xiao Q, Klein ML, Percec V, Rodriguez-Emmenegger C. Glycan-Driven Formation of Raft-Like Domains with Hierarchical Periodic Nanoarrays on Dendrimersome Synthetic Cells. Biomacromolecules 2024; 25:366-378. [PMID: 38064646 DOI: 10.1021/acs.biomac.3c01027] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2024]
Abstract
The accurate spatial segregation into distinct phases within cell membranes coordinates vital biochemical processes and functionalities in living organisms. One of nature's strategies to localize reactivity is the formation of dynamic raft domains. Most raft models rely on liquid-ordered L0 phases in a liquid-disordered Ld phase lacking correlation and remaining static, often necessitating external agents for phase separation. Here, we introduce a synthetic system of bicomponent glycodendrimersomes coassembled from Janus dendrimers and Janus glycodendrimers (JGDs), where lactose-lactose interactions exclusively drive lateral organization. This mechanism results in modulated phases across two length scales, yielding raft-like microdomains featuring nanoarrays at the nanoscale. By varying the density of lactose and molecular architecture of JGDs, the nanoarray type and size, shape, and spacing of the domains were controlled. Our findings offer insight into the potential primordial origins of rudimentary raft domains and highlight the crucial role of glycans within the glycocalyx.
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Affiliation(s)
- Anna M Wagner
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, Aachen 52074, Germany
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, Aachen 52074, Germany
| | - Nina Yu Kostina
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer de Baldiri Reixac 10-12, Barcelona 08028, Spain
| | - Qi Xiao
- Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
- Institute of Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Michael L Klein
- Institute of Computational Molecular Science, Temple University, Philadelphia, Pennsylvania 19122, United States
| | - Virgil Percec
- Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Cesar Rodriguez-Emmenegger
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, Aachen 52074, Germany
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology (BIST), Carrer de Baldiri Reixac 10-12, Barcelona 08028, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig Lluís Companys 23, Barcelona 08028, Spain
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15
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Enoki TA, Heberle FA. Experimentally determined leaflet-leaflet phase diagram of an asymmetric lipid bilayer. Proc Natl Acad Sci U S A 2023; 120:e2308723120. [PMID: 37939082 PMCID: PMC10655556 DOI: 10.1073/pnas.2308723120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 10/11/2023] [Indexed: 11/10/2023] Open
Abstract
We have determined the partial leaflet-leaflet phase diagram of an asymmetric lipid bilayer at ambient temperature using asymmetric giant unilamellar vesicles (aGUVs). Symmetric GUVs with varying amounts of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine) were hemifused to a supported lipid bilayer (SLB) composed of DOPC, resulting in lipid exchange between their outer leaflets. The GUVs and SLB contained a red and green lipid fluorophore, respectively, thus enabling the use of confocal fluorescence imaging to determine both the extent of lipid exchange (quantified for individual vesicles by the loss of red intensity and gain of green intensity) and the presence or absence of phase separation in aGUVs. Consistent with previous reports, we found that hemifusion results in large variation in outer leaflet exchange for individual GUVs, which allowed us to interrogate the phase behavior at multiple points within the asymmetric composition space of the binary mixture. When initially symmetric GUVs showed coexisting gel and fluid domains, aGUVs with less than ~50% outer leaflet exchange were also phase-separated. In contrast, aGUVs with greater than 50% outer leaflet exchange were uniform and fluid. In some cases, we also observed three coexisting bilayer-spanning phases: two registered phases and an anti-registered phase. These results suggest that a relatively large unfavorable midplane interaction between ordered and disordered phases in opposing leaflets (i.e., a midplane surface tension) can overwhelm the driving force for lateral phase separation within one of the leaflets, resulting in an asymmetric bilayer with two uniformly mixed leaflets that is poised to phase-separate upon leaflet scrambling.
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Affiliation(s)
- Thais A. Enoki
- Department of Chemistry, University of Tennessee, Knoxville, TN37996
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY14853
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16
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Shi Y, Ruan H, Xu Y, Zou C. Cholesterol, Eukaryotic Lipid Domains, and an Evolutionary Perspective of Transmembrane Signaling. Cold Spring Harb Perspect Biol 2023; 15:a041418. [PMID: 37604587 PMCID: PMC10626259 DOI: 10.1101/cshperspect.a041418] [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: 08/23/2023]
Abstract
Transmembrane signaling is essential for complex life forms. Communication across a bilayer lipid barrier is elaborately organized to convey precision and to fine-tune strength. Looking back, the steps that it has taken to enable this seemingly mundane errand are breathtaking, and with our survivorship bias, Darwinian. While this review is to discuss eukaryotic membranes in biological functions for coherence and theoretical footing, we are obliged to follow the evolution of the biological membrane through time. Such a visit is necessary for our hypothesis that constraints posited on cellular functions are mainly via the biomembrane, and relaxation thereof in favor of a coordinating membrane environment is the molecular basis for the development of highly specialized cellular activities, among them transmembrane signaling. We discuss the obligatory paths that have led to eukaryotic membrane formation, its intrinsic ability to signal, and how it set up the platform for later integration of protein-based receptor activation.
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Affiliation(s)
- Yan Shi
- Department of Basic Medical Sciences, Tsinghua-Peking University Joint Center for Life Sciences, School of Medicine; Institute for Immunology, Tsinghua University, Beijing 100084, China
- Department of Microbiology, Immunology and Infectious Diseases, Snyder Institute, University of Calgary, Calgary, Alberta T2N 4Z6, Canada
| | - Hefei Ruan
- Department of Basic Medical Sciences, Tsinghua-Peking University Joint Center for Life Sciences, School of Medicine; Institute for Immunology, Tsinghua University, Beijing 100084, China
- Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yanni Xu
- Department of Basic Medical Sciences, Tsinghua-Peking University Joint Center for Life Sciences, School of Medicine; Institute for Immunology, Tsinghua University, Beijing 100084, China
| | - Chunlin Zou
- Department of Basic Medical Sciences, Tsinghua-Peking University Joint Center for Life Sciences, School of Medicine; Institute for Immunology, Tsinghua University, Beijing 100084, China
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17
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Sarkar T, Farago O. Characterizing the heterogeneity of membrane liquid-ordered domains. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2023; 46:99. [PMID: 37847322 DOI: 10.1140/epje/s10189-023-00359-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 09/27/2023] [Indexed: 10/18/2023]
Abstract
We use a lattice model of a ternary mixture containing saturated and unsaturated lipids with cholesterol (Chol), to study the structural properties characterizing the coexistence between the liquid-disordered and liquid-ordered phases. Depending on the affinity of the saturated and unsaturated lipids, the system may exhibit macroscopic (thermodynamic) liquid-liquid phase separation or be divided into small-size liquid-ordered domains surrounded by a liquid-disordered matrix. In both cases, it is found that the nanoscale structure of the liquid-ordered regions is heterogeneous, and that they are partitioned into Chol-rich sub-domains and Chol-free, gel-like, nano-clusters. This emerges as a characteristic feature of the liquid-ordered state, which helps distinguishing between liquid-ordered domains in a two-phase mixture, and similar-looking domains in a one-phase mixture that are rich in saturated lipids and Chol, but are merely thermal density fluctuations. The nano-structure heterogeneity of the liquid-ordered phase can be detected by suitable experimental spectroscopic methods and is observed also in atomistic computer simulations.
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Affiliation(s)
- Tanmoy Sarkar
- Department of Theoretical Physics, Jožef Stefan Institute, Jamova 39, 1000, Ljubljana, Slovenia
| | - Oded Farago
- Biomedical Engineering Department, Ben Gurion University of the Negev, 84105, Beer Sheva, Israel.
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18
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Spinozzi F, Barbosa LRS, Corucci G, Mariani P, Itri R. Small-angle scattering from flat bilayers containing correlated scattering length density inhomogeneities. J Appl Crystallogr 2023; 56:1348-1360. [PMID: 37791360 PMCID: PMC10543680 DOI: 10.1107/s1600576723006143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 07/12/2023] [Indexed: 10/05/2023] Open
Abstract
Model lipid bilayers have been widely employed as a minimal system to investigate the structural properties of biological membranes by small-angle X-ray (SAXS) and neutron scattering (SANS) techniques. These have nanometre resolution and can give information regarding membrane thickness and scattering length densities (SLDs) of polar and apolar regions. However, biological membranes are complex systems containing different lipids and protein species, in which lipid domains can be dynamically assembled and disassembled. Therefore, SLD variations can occur within the biomembrane. In this work, a novel method has been developed to simulate SAXS and SANS profiles obtained from large unilamellar vesicles containing SLD inhomogeneities that are spatially correlated over the membrane surface. Such inhomogeneities are represented by cylindrical entities with equivalent SLDs. Stacking of bilayers is also included in the model, with no correlation between horizontal and vertical order. The model is applied to a lipid bilayer containing SLD inhomogeneities representing pores, lipid domains, and transmembrane, partially immersed and anchored proteins. It is demonstrated that all the structural information from the host lipid bilayer and from the SLD inhomogeneity can be consistently retrieved by a combined analysis of experimental SAXS and SANS data through the methodology proposed here.
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Affiliation(s)
- Francesco Spinozzi
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Leandro R. S. Barbosa
- Institute of Physics, University of São Paulo, São Paulo, Brazil
- Brazilian Synchrotron Light Laboratory (LNLS), Campinas, São Paulo, Brazil
| | - Giacomo Corucci
- Institut Laue–Langevin, Grenoble, France
- École Doctorale de Physique, Université Grenoble Alpes, Saint-Martin-d’Héres, France
| | - Paolo Mariani
- Department of Life and Environmental Sciences, Marche Polytechnic University, Ancona, Italy
| | - Rosangela Itri
- Institute of Physics, University of São Paulo, São Paulo, Brazil
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19
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Heller WT. Small-Angle Neutron Scattering Study of a Phosphatidylcholine-Phosphatidylethanolamine Mixture. ACS OMEGA 2023; 8:33755-33762. [PMID: 37744859 PMCID: PMC10515593 DOI: 10.1021/acsomega.3c04164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 08/23/2023] [Indexed: 09/26/2023]
Abstract
The properties of single-component phospholipid lipid bilayers have been extensively characterized. Natural cell membranes are not so simple, consisting of a diverse mixture of lipids and proteins. While having detailed structural information on complex membranes would be useful for understanding their structure and function, experimentally characterizing such membranes at a level of detail applied to model phospholipid bilayers is challenging. Here, small-angle neutron scattering with selective deuteration was used to characterize a binary lipid mixture composed of 1,2-dimyristoyl-3-sn-glycero-phosphatidylcholine and 1,2-dimyristoyl-3-sn-glycero-phosphatidylethanolamine. The data analysis provided the area per lipid in each leaflet as well as the asymmetry of the composition of the inner and outer leaflets of the bilayer. The results provide new insight into the structure of the lipid bilayer when this lipid mixture is used to prepare vesicles.
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Affiliation(s)
- William T. Heller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
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20
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Park S, Levental I, Pastor RW, Im W. Unsaturated Lipids Facilitate Partitioning of Transmembrane Peptides into the Liquid Ordered Phase. J Chem Theory Comput 2023; 19:5303-5314. [PMID: 37417947 PMCID: PMC10413867 DOI: 10.1021/acs.jctc.3c00398] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Indexed: 07/08/2023]
Abstract
The affinity of single-pass transmembrane (TM) proteins for ordered membrane phases has been reported to depend on their lipidation, TM length, and lipid accessible surface area. In this work, the raft affinities of the TM domain of the linker for activation of T cells and its depalmitoylated variant are assessed using free energy simulations in a binary bilayer system composed of two laterally patched bilayers of ternary liquid ordered (Lo) and liquid disordered (Ld) phases. These phases are modeled by distinct compositions of distearoylphosphatidylcholine, palmitoyloleoylphosphatidylcholine (POPC), and cholesterol, and the simulations were carried out for 4.5 μs/window. Both peptides are shown to preferentially partition into the Ld phase in agreement with model membrane experiments and previous simulations on ternary lipid mixtures but not with measurements on giant plasma membrane vesicles where the Lo is slightly preferred. However, the 500 ns average relaxation time of lipid rearrangement around the peptide precluded a quantitative analysis of free energy differences arising from peptide palmitoylation and two different lipid compositions. When in the Lo phase, peptides reside in regions rich in POPC and interact preferentially with its unsaturated tail. Hence, the detailed substructure of the Lo phase is an important modulator of peptide partitioning, in addition to the inherent properties of the peptide.
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Affiliation(s)
- Soohyung Park
- Departments
of Biological Sciences and Chemistry, Lehigh
University, Bethlehem, Pennsylvania 18015, United States
| | - Ilya Levental
- Department
of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22903-1738, United States
| | - Richard W. Pastor
- Laboratory
of Computational Biology, National Heart,
Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Wonpil Im
- Departments
of Biological Sciences and Chemistry, Lehigh
University, Bethlehem, Pennsylvania 18015, United States
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21
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Nojima Y, Takaya T, Iwata K. Energy Transfer Characteristics of Lipid Bilayer Membranes of Liposomes Examined with Picosecond Time-Resolved Raman Spectroscopy. J Phys Chem B 2023; 127:6684-6693. [PMID: 37481745 DOI: 10.1021/acs.jpcb.3c02120] [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: 07/25/2023]
Abstract
A number of biochemical reactions proceed inside biomembranes. Since the rate of a chemical reaction is influenced by chemical properties of the surrounding environment, it is important to examine the chemical environment inside the biomembranes. Although the energy transfer characteristics are a basic and important property of a reaction medium, experimental investigation of the thermal conducting capabilities of the biomembranes is a challenging task. We have examined the energy transfer characteristics of lipid bilayer membranes of liposomes, a good model system for the biomembrane, with picosecond time-resolved Raman spectroscopy. The cooling kinetics of the first excited singlet (S1) state of trans-stilbene solubilized within the lipid bilayer membranes is observed as a peak shift of the 1570 cm-1 Raman band of S1 trans-stilbene. The cooling rate constant of S1 trans-stilbene is obtained in six lipid bilayer membranes formed by phospholipids with different hydrocarbon chains, DSPC, DPPC, DMPC, DLPC, DOPC, and egg-PC. We estimate the thermal diffusivity of the lipid bilayer membranes with a known correlation between the cooling rate constant and the thermal diffusivity of the solvent. The thermal diffusivity estimated for the liquid-crystal-phase lipid bilayer membranes is 8.9 × 10-8 to 9.4 × 10-8 m2 s-1, while that for the gel-phase lipid bilayer membranes is 8.4 × 10-8 to 8.5 × 10-8 m2 s-1. The difference in thermal diffusivity between the two phases is explained by a one-dimensional diffusion equation of heat.
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Affiliation(s)
- Yuki Nojima
- Department of Chemistry, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
- Department of Chemistry, Graduate School of Science and Technology, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan
| | - Tomohisa Takaya
- Department of Chemistry, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
- Department of Electrical and Electronic Engineering, Faculty of Engineering, Toyama Prefectural University, Imizu, Toyama 939-0398, Japan
| | - Koichi Iwata
- Department of Chemistry, Faculty of Science, Gakushuin University, Toshima-ku, Tokyo 171-8588, Japan
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22
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Mitchison-Field LM, Belin BJ. Bacterial lipid biophysics and membrane organization. Curr Opin Microbiol 2023; 74:102315. [PMID: 37058914 PMCID: PMC10523990 DOI: 10.1016/j.mib.2023.102315] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 04/16/2023]
Abstract
The formation of lateral microdomains is emerging as a central organizing principle in bacterial membranes. These microdomains are targets of antibiotic development and have the potential to enhance natural product synthesis, but the rules governing their assembly are unclear. Previous studies have suggested that microdomain formation is promoted by lipid phase separation, particularly by cardiolipin (CL) and isoprenoid lipids, and there is strong evidence that CL biosynthesis is required for recruitment of membrane proteins to cell poles and division sites. New work demonstrates that additional bacterial lipids may mediate membrane protein localization and function, opening the field for mechanistic evaluation of lipid-driven membrane organization in vivo.
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Affiliation(s)
- Lorna My Mitchison-Field
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA; Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Brittany J Belin
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA; Department of Biology, Johns Hopkins University, Baltimore, MD, USA.
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23
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Garvey CJ, Bryant SJ, Elbourne A, Hunt T, Kent B, Kreuzer M, Strobl M, Steitz R, Bryant G. Phase separation in a ternary DPPC/DOPC/POPC system with reducing hydration. J Colloid Interface Sci 2023; 638:719-732. [PMID: 36774881 DOI: 10.1016/j.jcis.2023.01.145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/10/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023]
Abstract
The maintenance of plasma membrane structure is vital for the viability of cells. Disruption of this structure can lead to cell death. One important example is the macroscopic phase separation observed during dehydration associated with desiccation and freezing, often leading to loss of permeability and cell death. It has previously been shown that the hybrid lipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) can act as a line-active component in ternary lipid systems, inhibiting macroscopic phase separation and stabilising membrane microdomains in lipid vesicles [1]. The domain size is found to decrease with increasing POPC concentration until complete mixing is observed. However, no such studies have been carried out at reduced hydration. To examine if this phase separation is unique to vesicles in excess water, we have conducted studies on several binary and ternary model membrane systems at both reduced hydration ("powder" type samples and oriented membrane stacks) and in excess water (supported lipid bilayers) at 0.2 mol fraction POPC, in the range where microdomain stabilisation is reported. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) are used to map phase transition temperatures, with X-ray and neutron scattering providing details of the changes in lipid packing and phase information within these boundaries. Atomic force microscopy (AFM) is used to image bilayers on a substrate in excess water. In all cases, macroscopic phase separation was observed rather than microdomain formation at this molar ratio. Thus POPC does not stabilise microdomains under these conditions, regardless of the type of model membrane, hydration or temperature. Thus we conclude that the driving force for separation under these conditions overcomes any linactant effects of the hybrid lipid.
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Affiliation(s)
- Christopher J Garvey
- Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstraße 1, 85748 Garching, Germany.
| | | | - Aaron Elbourne
- School of Science, RMIT University, Melbourne, Australia
| | - Taavi Hunt
- School of Science, RMIT University, Melbourne, Australia
| | - Ben Kent
- Centre for Advanced Macromolecular Design, School of Chemistry, The University of New South Wales, Sydney 2052, Australia; Institute for Soft Matter and Functional Materials, Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, Berlin, Germany
| | - Martin Kreuzer
- Institute for Soft Matter and Functional Materials, Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, Berlin, Germany; ALBA Synchrotron, Barcelona, Spain
| | - Markus Strobl
- Institute for Soft Matter and Functional Materials, Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, Berlin, Germany; Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institut, 5232 Villigen, Switzerland
| | - Roland Steitz
- Institute for Soft Matter and Functional Materials, Helmholtz Zentrum Berlin, Hahn-Meitner-Platz 1, Berlin, Germany
| | - Gary Bryant
- School of Science, RMIT University, Melbourne, Australia.
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24
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Kusumi A, Tsunoyama TA, Tang B, Hirosawa KM, Morone N, Fujiwara TK, Suzuki KGN. Cholesterol- and actin-centered view of the plasma membrane: updating the Singer-Nicolson fluid mosaic model to commemorate its 50th anniversary †. Mol Biol Cell 2023; 34:pl1. [PMID: 37039596 PMCID: PMC10162409 DOI: 10.1091/mbc.e20-12-0809] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 12/07/2022] [Accepted: 02/07/2023] [Indexed: 04/12/2023] Open
Abstract
Two very polarized views exist for understanding the cellular plasma membrane (PM). For some, it is the simple fluid described by the original Singer-Nicolson fluid mosaic model. For others, due to the presence of thousands of molecular species that extensively interact with each other, the PM forms various clusters and domains that are constantly changing and therefore, no simple rules exist that can explain the structure and molecular dynamics of the PM. In this article, we propose that viewing the PM from its two predominant components, cholesterol and actin filaments, provides an excellent and transparent perspective of PM organization, dynamics, and mechanisms for its functions. We focus on the actin-induced membrane compartmentalization and lipid raft domains coexisting in the PM and how they interact with each other to perform PM functions. This view provides an important update of the fluid mosaic model.
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Affiliation(s)
- Akihiro Kusumi
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa 904-0495, Japan
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Taka A. Tsunoyama
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa 904-0495, Japan
| | - Bo Tang
- Membrane Cooperativity Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa 904-0495, Japan
| | - Koichiro M. Hirosawa
- Institute for Glyco-Core Research (iGCORE), Gifu University, Gifu 501-1193, Japan
| | - Nobuhiro Morone
- MRC Toxicology Unit, University of Cambridge, Cambridge CB2 1QR, UK
| | - Takahiro K. Fujiwara
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
| | - Kenichi G. N. Suzuki
- Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto 606-8501, Japan
- Institute for Glyco-Core Research (iGCORE), Gifu University, Gifu 501-1193, Japan
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25
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Sharma KD, Heberle FA, Waxham MN. Visualizing lipid membrane structure with cryo-EM: past, present, and future. Emerg Top Life Sci 2023; 7:55-65. [PMID: 36606590 PMCID: PMC10355340 DOI: 10.1042/etls20220090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/14/2022] [Accepted: 12/20/2022] [Indexed: 01/07/2023]
Abstract
The development of electron cryomicroscopy (cryo-EM) has evolved immensely in the last several decades and is now well-established in the analysis of protein structure both in isolation and in their cellular context. This review focuses on the history and application of cryo-EM to the analysis of membrane architecture. Parallels between the levels of organization of protein structure are useful in organizing the discussion of the unique parameters that influence membrane structure and function. Importantly, the timescales of lipid motion in bilayers with respect to the timescales of sample vitrification is discussed and reveals what types of membrane structure can be reliably extracted in cryo-EM images of vitrified samples. Appreciating these limitations, a review of the application of cryo-EM to examine the lateral organization of ordered and disordered domains in reconstituted and biologically derived membranes is provided. Finally, a brief outlook for further development and application of cryo-EM to the analysis of membrane architecture is provided.
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Affiliation(s)
- Karan D. Sharma
- Department of Chemistry, University of Tennessee, Knoxville, TN
| | | | - M. Neal Waxham
- Department of Neurobiology and Anatomy, University of Texas Health Science Center, Houston, TX
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26
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Ermilova I, Swenson J. Ionizable lipids penetrate phospholipid bilayers with high phase transition temperatures: perspectives from free energy calculations. Chem Phys Lipids 2023; 253:105294. [PMID: 37003484 DOI: 10.1016/j.chemphyslip.2023.105294] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/14/2023] [Accepted: 03/24/2023] [Indexed: 04/03/2023]
Abstract
The efficacies of modern gene-therapies strongly depend on their contents. At the same time the most potent formulations might not contain the best compounds. In this work we investigated the effect of phospholipids and their saturation on the binding ability of (6Z,9Z,28Z,31Z)-heptatriacont-6,9,28,31-tetraene-19-yl 4-(dimethylamino) butanoate (DLin-MC3-DMA) to model membranes at the neutral pH. We discovered that DLin-MC3-DMA has affinity to the most saturated monocomponent lipid bilayer 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) and an aversion to the unsaturated one 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). The preference to a certain membrane was also well-correlated to the phase transition temperatures of phospholipid bilayers, and to their structural and dynamical properties. Additionally, in the case of the presence of DLin-MC3-DMA in the membrane with DOPC the ionizable lipid penetrated it, which indicates possible synergistic effects. Comparisons with other ionizable lipids were performed using a model lipid bilayer of 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC). Particularly, the lipids heptadecan-9-yl 8-[2-hydroxyethyl-(6-oxo-6-undecoxyhexyl)amino]octanoate (SM-102) and [(4-Hydroxybutyl) azanediyl] di(hexane-6,1-diyl) bis(2-hexyldecanoate) (ALC-0315) from modern mRNA-vaccines against COVID-19 were investigated and force fields parameters were derived for those new lipids. It was discovered that ALC-0315 binds strongest to the membrane, while DLin-MC3-DMA is not able to reside in the bilayer center. The ability to penetrate the membrane POPC by SM-102 and ALC-0315 can be related to their saturation, comparing to DLin-MC3-DMA.
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Affiliation(s)
- Inna Ermilova
- Department of Physics, Chalmers Uiversity of Technology, SE 412 96, Gothenburg, Sweden.
| | - Jan Swenson
- Department of Physics, Chalmers Uiversity of Technology, SE 412 96, Gothenburg, Sweden.
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27
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Sarkar T, Farago O. A lattice model of ternary mixtures of lipids and cholesterol with tunable domain sizes. SOFT MATTER 2023; 19:2417-2429. [PMID: 36930060 DOI: 10.1039/d2sm01025a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Much of our understanding of the physical properties of raft domains in biological membranes, and some insight into the mechanisms underlying their formation stem from atomistic simulations of simple model systems, especially ternary mixtures consisting of saturated and unsaturated lipids, and cholesterol (Chol). To explore the properties of such systems at large spatial scales, we here present a simple ternary mixture lattice model, involving a small number of nearest neighbor interaction terms. Monte Carlo simulations of mixtures with different compositions show excellent agreement with experimental and atomistic simulation observations across multiple scales, ranging from the local distributions of lipids to the phase diagram of the system. The simplicity of the model allows us to identify the roles played by the different interactions between components, and the interplay between them. Importantly, by changing the value of one of the model parameters, we can tune the size of the liquid-ordered domains, thereby simulating both Type II mixtures exhibiting macroscopic phase separation and Type I mixtures with nanoscopic domains. The Type II mixture simulation results fit well to the experimentally determined phase diagram of mixtures containing saturated DPPC/unsaturated DOPC/Chol. When the tunable parameter is changed, we obtain the Type I version of DPPC/DOPC/Chol, i.e., a mixture not showing thermodynamic phase transitions but one that may be fitted to the same phase diagram if local measures are used to distinguish between the different states. Our model results suggest that short range packing is likely to be a key regulator of the stability and size distribution of biological rafts.
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Affiliation(s)
- Tanmoy Sarkar
- Department of Biomedical Engineering, Ben Gurion University of the Negev, Be'er Sheva 84105, Israel.
| | - Oded Farago
- Department of Biomedical Engineering, Ben Gurion University of the Negev, Be'er Sheva 84105, Israel.
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28
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Cavazos AT, Pennington ER, Dadoo S, Gowdy KM, Wassall SR, Shaikh SR. OxPAPC stabilizes liquid-ordered domains in biomimetic membranes. Biophys J 2023; 122:1130-1139. [PMID: 36840353 PMCID: PMC10111260 DOI: 10.1016/j.bpj.2023.02.024] [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: 08/30/2022] [Revised: 11/16/2022] [Accepted: 02/17/2023] [Indexed: 02/26/2023] Open
Abstract
Long-chain polyunsaturated fatty acids (PUFAs) are prone to nonenzymatic oxidation in response to differing environmental stressors and endogenous cellular sources. There is increasing evidence that phospholipids containing oxidized PUFA acyl chains control the inflammatory response. However, the underlying mechanism(s) of action by which oxidized PUFAs exert their functional effects remain unclear. Herein, we tested the hypothesis that replacement of 1-palmitoyl-2-arachidonyl-phosphatidylcholine (PAPC) with oxidized 1-palmitoyl-2-arachidonyl-phosphatidylcholine (oxPAPC) regulates membrane architecture. Specifically, with solid-state 2H NMR of biomimetic membranes, we investigated how substituting oxPAPC for PAPC modulates the molecular organization of liquid-ordered (Lo) domains. 2H NMR spectra for bilayer mixtures of 1,2-dipalmitoylphosphatidylcholine-d62 (an analog of DPPC deuterated throughout sn-1 and -2 chains) and cholesterol to which PAPC or oxPAPC was added revealed that replacing PAPC with oxPAPC disrupted molecular organization, indicating that oxPAPC does not mix favorably in a tightly packed Lo phase. Furthermore, unlike PAPC, adding oxPAPC stabilized 1,2-dipalmitoylphosphatidylcholine-d6-rich/cholesterol-rich Lo domains formed in mixtures with 1,2-dioleoylphosphatidylcholine while decreasing the molecular order within 1,2-dioleoylphosphatidylcholine-rich liquid-disordered regions of the membrane. Collectively, these results suggest a mechanism in which oxPAPC stabilizes Lo domains-by disordering the surrounding liquid-disordered region. Changes in the structure, and thereby functionality, of Lo domains may underly regulation of plasma membrane-based inflammatory signaling by oxPAPC.
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Affiliation(s)
- Andres T Cavazos
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis Indiana
| | - Edward Ross Pennington
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill North Carolina
| | - Sahil Dadoo
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill North Carolina
| | - Kymberly M Gowdy
- Pulmonary, Critical Care and Sleep Medicine, Ohio State University Wexner Medical Center, Davis Heart and Lung Research Institute, Columbus, Ohio
| | - Stephen R Wassall
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis Indiana.
| | - Saame Raza Shaikh
- Department of Nutrition, Gillings School of Global Public Health and School of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill North Carolina.
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29
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Kinnun JJ, Scott HL, Bolmatov D, Collier CP, Charlton TR, Katsaras J. Biophysical studies of lipid nanodomains using different physical characterization techniques. Biophys J 2023; 122:931-949. [PMID: 36698312 PMCID: PMC10111277 DOI: 10.1016/j.bpj.2023.01.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 01/12/2023] [Accepted: 01/19/2023] [Indexed: 01/26/2023] Open
Abstract
For the past 50 years, evidence for the existence of functional lipid domains has been steadily accumulating. Although the notion of functional lipid domains, also known as "lipid rafts," is now widely accepted, this was not always the case. This ambiguity surrounding lipid domains could be partly attributed to the fact that they are highly dynamic, nanoscopic structures. Since most commonly used techniques are sensitive to microscale structural features, it is therefore, not surprising that it took some time to reach a consensus regarding their existence. In this review article, we will discuss studies that have used techniques that are inherently sensitive to nanoscopic structural features (i.e., neutron scatting, nuclear magnetic resonance, and Förster resonance energy transfer). We will also mention techniques that may be of use in the future (i.e., cryoelectron microscopy, droplet interface bilayers, inelastic x-ray scattering, and neutron reflectometry), which can further our understanding of the different and unique physicochemical properties of nanoscopic lipid domains.
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Affiliation(s)
- Jacob J Kinnun
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
| | - Haden L Scott
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Dima Bolmatov
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee
| | - C Patrick Collier
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - Timothy R Charlton
- Large Scale Structures Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee
| | - John Katsaras
- Shull Wollan Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee; Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee; Labs and Soft Matter Group, Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee.
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30
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Krzyzanowski N, Porcar L, Perez-Salas U. A Small-Angle Neutron Scattering, Calorimetry and Densitometry Study to Detect Phase Boundaries and Nanoscale Domain Structure in a Binary Lipid Mixture. MEMBRANES 2023; 13:323. [PMID: 36984710 PMCID: PMC10051979 DOI: 10.3390/membranes13030323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Revised: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 06/18/2023]
Abstract
Techniques that can probe nanometer length scales, such as small-angle neutron scattering (SANS), have become increasingly popular to detect phase separation in membranes. But to extract the phase composition and domain structure from the SANS traces, complementary information is needed. Here, we present a SANS, calorimetry and densitometry study of a mixture of two saturated lipids that exhibits solidus-liquidus phase coexistence: 1,2-dipalmitoyl-d62-sn-glycero-3-phosphocholine (dDPPC, tail-deuterated DPPC) and 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC). With calorimetry, we investigated the phase diagram for this system and found that the boundary traces for both multilamellar vesicles (MLVs) as well as 50 nm unilamellar vesicles overlap. Because the solidus boundary was mostly inaccessible by calorimetry, we investigated it by both SANS and molecular volume measurements for a 1:1 dDPPC:DLPC lipid mixture. From the temperature behavior of the molecular volume for the 1:1 dDPPC:DLPC mixture, as well as the individual molecular volume of each lipid species, we inferred that the liquidus phase consists of only fluid-state lipids while the solidus phase consists of lipids that are in gel-like states. Using this solidus-liquidus phase model, the SANS data were analyzed with an unrestricted shape model analysis software: MONSA. The resulting fits show irregular domains with dendrite-like features as those previously observed on giant unilamellar vesicles (GUVs). The surface pair correlation function describes a characteristic domain size for the minority phase that decreases with temperature, a behavior found to be consistent with a concomitant decrease in membrane mismatch between the liquidus and solidus phases.
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Affiliation(s)
- Natalie Krzyzanowski
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60608, USA
| | - Lionel Porcar
- Large Scale Structures Group, Institut Laue-Langevin, CEDEX 9, 38042 Grenoble, France
| | - Ursula Perez-Salas
- Department of Physics, University of Illinois at Chicago, Chicago, IL 60608, USA
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31
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Structural diversity of photoswitchable sphingolipids for optodynamic control of lipid microdomains. Biophys J 2023:S0006-3495(23)00135-2. [PMID: 36869591 DOI: 10.1016/j.bpj.2023.02.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 01/22/2023] [Accepted: 02/27/2023] [Indexed: 03/05/2023] Open
Abstract
Sphingolipids are a structurally diverse class of lipids predominantly found in the plasma membrane of eukaryotic cells. These lipids can laterally segregate with other rigid lipids and cholesterol into liquid-ordered domains that act as organizing centers within biomembranes. Owing the vital role of sphingolipids for lipid segregation, controlling their lateral organization is of utmost significance. Hence, we made use of the light-induced trans-cis isomerization of azobenzene-modified acyl chains to develop a set of photoswitchable sphingolipids with different headgroups (hydroxyl, galactosyl, phosphocholine) and backbones (sphingosine, phytosphingosine, tetrahydropyran-blocked sphingosine) that are able to shuttle between liquid-ordered and liquid-disordered regions of model membranes upon irradiation with UV-A (λ = 365 nm) and blue (λ = 470 nm) light, respectively. Using combined high-speed atomic force microscopy, fluorescence microscopy, and force spectroscopy, we investigated how these active sphingolipids laterally remodel supported bilayers upon photoisomerization, notably in terms of domain area changes, height mismatch, line tension, and membrane piercing. Hereby, we show that the sphingosine-based (Azo-β-Gal-Cer, Azo-SM, Azo-Cer) and phytosphingosine-based (Azo-α-Gal-PhCer, Azo-PhCer) photoswitchable lipids promote a reduction in liquid-ordered microdomain area when in the UV-adapted cis-isoform. In contrast, azo-sphingolipids having tetrahydropyran groups that block H-bonding at the sphingosine backbone (lipids named Azo-THP-SM, Azo-THP-Cer) induce an increase in the liquid-ordered domain area when in cis, accompanied by a major rise in height mismatch and line tension. These changes were fully reversible upon blue light-triggered isomerization of the various lipids back to trans, pinpointing the role of interfacial interactions for the formation of stable liquid-ordered domains.
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32
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Refinement of Singer-Nicolson fluid-mosaic model by microscopy imaging: Lipid rafts and actin-induced membrane compartmentalization. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184093. [PMID: 36423676 DOI: 10.1016/j.bbamem.2022.184093] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Revised: 11/09/2022] [Accepted: 11/10/2022] [Indexed: 11/22/2022]
Abstract
This year celebrates the 50th anniversary of the Singer-Nicolson fluid mosaic model for biological membranes. The next level of sophistication we have achieved for understanding plasma membrane (PM) structures, dynamics, and functions during these 50 years includes the PM interactions with cortical actin filaments and the partial demixing of membrane constituent molecules in the PM, particularly raft domains. Here, first, we summarize our current knowledge of these two structures and emphasize that they are interrelated. Second, we review the structure, molecular dynamics, and function of raft domains, with main focuses on raftophilic glycosylphosphatidylinositol-anchored proteins (GPI-APs) and their signal transduction mechanisms. We pay special attention to the results obtained by single-molecule imaging techniques and other advanced microscopy methods. We also clarify the limitations of present optical microscopy methods for visualizing raft domains, but emphasize that single-molecule imaging techniques can "detect" raft domains associated with molecules of interest in the PM.
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33
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Reorganization of the outer layer of a model of the plasma membrane induced by a neuroprotective aminosterol. Colloids Surf B Biointerfaces 2023; 222:113115. [PMID: 36603410 DOI: 10.1016/j.colsurfb.2022.113115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 12/07/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022]
Abstract
Trodusquemine is an amphipathic aminosterol that has recently shown therapeutic benefit in neurodegenerative diseases altering the binding of misfolded proteins to the cell membrane. To unravel the underlying mechanism, we studied the interactions between Trodusquemine (TRO) and lipid monolayers simulating the outer layer of the plasma membrane. We selected two different compositions of dioleoylphosphatidylcholine (DOPC), sphingomyelin (SM), cholesterol (Chol) and monosialotetrahexosylganglioside (GM1) lipid mixture mimicking either a lipid-raft containing membrane (Ld+So phases) or a single-phase disordered membrane (Ld phase). Surface pressure-area isotherms and surface compressional modulus-area combined with Brewster Angle Microscopy (BAM) provided the thermodynamic and morphological information on the lipid monolayer in the presence of increasing amounts of TRO in the monolayer. Experiments revealed that TRO forms stable spreading monolayers at the buffer-air interface where it undergoes multiple reversible phase transitions to bi- and tri-layers at the interface. When TRO was spread at the interface with the lipid mixtures, we found that it distributes in the lipid monolayer for both the selected lipid compositions, but a maximum TRO uptake in the rafts-containing monolayer was observed for a Lipid/TRO molar ratio equal to 3:2. Statistical analysis of BAM images revealed that TRO induces a decrease in the size of the condensed domains, an increase in their number and in the thickness mismatch between the Ld and So phase. Experiments and MD simulations converge to indicate that TRO adsorbs preferentially at the border of the So domains. Removal of GM1 from the lipid Ld+So mixture resulted in an even greater TRO-mediated reduction of the size of the So domains suggesting that the presence of GM1 hinders the localization of TRO at the So domains boundaries. Taken together these observations suggest that Trodusquemine influences the organization of lipid rafts within the neuronal membrane in a dose-dependent manner whereas it evenly distributes in disordered expanded phases of the membrane model.
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34
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Ko TH, Chen YF. Correlation between the In-Plane Critical Behavior and Out-of-Plane Interaction of Ternary Lipid Membranes. MEMBRANES 2022; 13:6. [PMID: 36676813 PMCID: PMC9860714 DOI: 10.3390/membranes13010006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
Liquid-liquid phase-separating lipid membranes belong to the 2-D Ising universality class. While their in-plane critical behaviors are well studied, how the behaviors modulate out-of-plane interactions is rarely explored, despite its profound implications for biomembranes and 2-D ferromagnets. Here, we examine how the interlayer interaction, manifested as membrane fusion, is affected by the membranes' critical fluctuations. Remarkably, the critical fluctuations suppress membrane fusion, suggesting a correlation between critical behaviors and interlayer interactions for 2-D Ising systems.
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35
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Ho PS, Kao TY, Li CC, Lan YJ, Lai YC, Chiang YW. Nanodisc Lipids Exhibit Singular Behaviors Implying Critical Phenomena. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:15372-15383. [PMID: 36454955 DOI: 10.1021/acs.langmuir.2c02596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Nanodiscs are broadly used for characterization of membrane proteins as they are generally assumed to provide a near-native environment. In fact, it is an open question whether the physical properties of lipids in nanodiscs and membrane vesicles of the same lipid composition are identical. Here, we investigate the properties of lipids (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, 1,2-dilauroyl-sn-glycero-3-phosphocholine, and their mixtures) in two different sample types, nanodiscs and multilamellar vesicles, by means of spin-label electron spin resonance techniques. Our results provide a quantitative description of lipid dynamics and ordering, elucidating the molecular details of how lipids in the two sample types behave differently in response to temperature and lipid composition. We show that the properties of lipids are altered in nanodiscs such that the dissimilarity of the fluid and gel lipid phases is reduced, and the first-order phase transitions are largely abolished in nanodiscs. We unveil that the ensemble of lipids in the middle of a nanodisc bilayer, as probed by the end-chain spin-label 16-PC, is promoted to a state close to a miscibility critical point, thereby rendering the phase transitions continuous. Critical phenomena have recently been proposed to explain features of the heterogeneity in native cell membranes. Our results lay the groundwork for how to establish a near-native environment in nanodiscs with simple organization of lipid components.
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Affiliation(s)
- Pei-Shan Ho
- Department of Chemistry, National Tsing Hua University, Hsinchu 300-044, Taiwan
| | - Te-Yu Kao
- Department of Chemistry, National Tsing Hua University, Hsinchu 300-044, Taiwan
| | - Chieh-Chin Li
- Department of Chemistry, National Tsing Hua University, Hsinchu 300-044, Taiwan
| | - Yu-Jing Lan
- Department of Chemistry, National Tsing Hua University, Hsinchu 300-044, Taiwan
| | - Yei-Chen Lai
- Department of Chemistry, National Chung Hsing University, Taichung 402-002, Taiwan
| | - Yun-Wei Chiang
- Department of Chemistry, National Tsing Hua University, Hsinchu 300-044, Taiwan
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36
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Heller WT. Small-Angle Neutron Scattering for Studying Lipid Bilayer Membranes. Biomolecules 2022; 12:1591. [PMID: 36358941 PMCID: PMC9687511 DOI: 10.3390/biom12111591] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 10/18/2022] [Accepted: 10/26/2022] [Indexed: 09/23/2023] Open
Abstract
Small-angle neutron scattering (SANS) is a powerful tool for studying biological membranes and model lipid bilayer membranes. The length scales probed by SANS, being from 1 nm to over 100 nm, are well-matched to the relevant length scales of the bilayer, particularly when it is in the form of a vesicle. However, it is the ability of SANS to differentiate between isotopes of hydrogen as well as the availability of deuterium labeled lipids that truly enable SANS to reveal details of membranes that are not accessible with the use of other techniques, such as small-angle X-ray scattering. In this work, an overview of the use of SANS for studying unilamellar lipid bilayer vesicles is presented. The technique is briefly presented, and the power of selective deuteration and contrast variation methods is discussed. Approaches to modeling SANS data from unilamellar lipid bilayer vesicles are presented. Finally, recent examples are discussed. While the emphasis is on studies of unilamellar vesicles, examples of the use of SANS to study intact cells are also presented.
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Affiliation(s)
- William T Heller
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
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37
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DiPasquale M, Nguyen MHL, Castillo SR, Dib IJ, Kelley EG, Marquardt D. Vitamin E Does Not Disturb Polyunsaturated Fatty Acid Lipid Domains. Biochemistry 2022; 61:2366-2376. [PMID: 36227768 DOI: 10.1021/acs.biochem.2c00405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The function of vitamin E in biomembranes remains a prominent topic of discussion. As its limitations as an antioxidant persist and novel functions are discovered, our understanding of the role of vitamin E becomes increasingly enigmatic. As a group of lipophilic molecules (tocopherols and tocotrienols), vitamin E has been shown to influence the properties of its host membrane, and a wealth of research has connected vitamin E to polyunsaturated fatty acid (PUFA) lipids. Here, we use contrast-matched small-angle neutron scattering and differential scanning calorimetry to integrate these fields by examining the influence of vitamin E on lipid domain stability in PUFA-based lipid mixtures. The influence of α-tocopherol, γ-tocopherol, and α-tocopherylquinone on the lateral organization of a 1:1 lipid mixture of saturated distearoylphosphatidylcholine (DSPC) and polyunsaturated palmitoyl-linoleoylphosphatidylcholine (PLiPC) with cholesterol provides a complement to our growing understanding of the influence of tocopherol on lipid phases. Characterization of domain melting suggests a slight depression in the transition temperature and a decrease in transition cooperativity. Tocopherol concentrations that are an order of magnitude higher than anticipated physiological concentrations (2 mol percent) do not significantly perturb lipid domains; however, addition of 10 mol percent is able to destabilize domains and promote lipid mixing. In contrast to this behavior, increasing concentrations of the oxidized product of α-tocopherol (α-tocopherylquinone) induces a proportional increase in domain stabilization. We speculate how the contrasting effect of the oxidized product may supplement the antioxidant response of vitamin E.
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Affiliation(s)
- Mitchell DiPasquale
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, OntarioN9B3P4, Canada
| | - Michael H L Nguyen
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, OntarioN9B3P4, Canada
| | - Stuart R Castillo
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, OntarioN9B3P4, Canada
| | - Isabelle J Dib
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, OntarioN9B3P4, Canada
| | - Elizabeth G Kelley
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland20878, United States
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, OntarioN9B3P4, Canada.,Department of Physics, University of Windsor, Windsor, OntarioN9B3P4, Canada
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38
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Heterogeneity and deformation behavior of lipid vesicles. Curr Opin Colloid Interface Sci 2022. [DOI: 10.1016/j.cocis.2022.101646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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39
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Scheidegger L, Stricker L, Beltramo PJ, Vermant J. Domain Size Regulation in Phospholipid Model Membranes Using Oil Molecules and Hybrid Lipids. J Phys Chem B 2022; 126:5842-5854. [PMID: 35895895 PMCID: PMC9377339 DOI: 10.1021/acs.jpcb.2c02862] [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: 04/25/2022] [Revised: 07/06/2022] [Indexed: 11/29/2022]
Abstract
The formation of domains in multicomponent lipid mixtures has been suggested to play a role in moderating signal transduction in cells. Understanding how domain size may be regulated by both hybrid lipid molecules and impurities is important for understanding real biological processes; at the same time, developing model systems where domain size can be regulated is crucial to enable systematic studies of domain formation kinetics and thermodynamics. Here, we perform a model study of the effects of oil molecules, which swell the bilayer, and line-active hybrid phospholipids using a thermally induced liquid-solid phase separation in planar, free-standing lipid bilayers consisting of DOPC and DPPC (1,2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine, respectively). The experiments show that the kinetics of domain growth are significantly affected by the type and molecular structure of the oil (squalene, hexadecane, or decane), with the main contributing factors being the degree of swelling of the bilayer and the changes in line tension induced by the different oils, with smaller domains resulting from systems with smaller values of the line tension. POPC (1-palmitoyl-sn-2-oleoyl-glycero-3-phosphocholine), on the other hand, acts as a line-active hybrid lipid, reducing the domain size when added in small amounts and slowing down domain coarsening. Finally, we show that despite the regulation of domain size by both methods, the phase transition temperature is influenced by the presence of oil molecules but not significantly by the presence of hybrid lipids. Overall, our results show how to regulate domain size in binary membrane model systems, over a wide range of length scales, by incorporating oil molecules and hybrid lipids.
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Affiliation(s)
- Laura Scheidegger
- Department
of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Laura Stricker
- Department
of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
| | - Peter J. Beltramo
- Department
of Chemical Engineering, University of Massachusetts
Amherst, Amherst, Massachusetts 01003, United States
| | - Jan Vermant
- Department
of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
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40
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DiPasquale M, Deering TG, Desai D, Sharma AK, Amin S, Fox TE, Kester M, Katsaras J, Marquardt D, Heberle FA. Influence of ceramide on lipid domain stability studied with small-angle neutron scattering: The role of acyl chain length and unsaturation. Chem Phys Lipids 2022; 245:105205. [PMID: 35483419 PMCID: PMC9320172 DOI: 10.1016/j.chemphyslip.2022.105205] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 04/11/2022] [Indexed: 12/13/2022]
Abstract
Ceramides and diacylglycerols are groups of lipids capable of nucleating and stabilizing ordered lipid domains, structures that have been implicated in a range of biological processes. Previous studies have used fluorescence reporter molecules to explore the influence of ceramide acyl chain structure on sphingolipid-rich ordered phases. Here, we use small-angle neutron scattering (SANS) to examine the ability of ceramides and diacylglycerols to promote lipid domain formation in the well-characterized domain-forming mixture DPPC/DOPC/cholesterol. SANS is a powerful, probe-free technique for interrogating membrane heterogeneity, as it is differentially sensitive to hydrogen's stable isotopes protium and deuterium. Specifically, neutron contrast is generated through selective deuteration of lipid species, thus enabling the detection of nanoscopic domains enriched in deuterated saturated lipids dispersed in a matrix of protiated unsaturated lipids. Using large unilamellar vesicles, we found that upon replacing 10 mol% DPPC with either C16:0 or C18:0 ceramide, or 16:0 diacylglycerol (dag), lipid domains persisted to higher temperatures. However, when DPPC was replaced with short chain (C6:0 or C12:0) or very long chain (C24:0) ceramides, or ceramides with unsaturated acyl chains of any length (C6:1(3), C6:1(5), C18:1, and C24:1), as well as C18:1-dag, lipid domains were destabilized, melting at lower temperatures than those in the DPPC/DOPC/cholesterol system. These results show how ceramide acyl chain length and unsaturation influence lipid domains and have implications for how cell membranes might modify their function through the generation of different ceramide species.
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Affiliation(s)
- Mitchell DiPasquale
- Department of Chemistry and Biochemistry, University of Windsor, Windsor N9B 3P4, ON, Canada
| | - Tye G Deering
- Department of Pharmacology, University of Virginia, Charlottesville 22908, VA, USA
| | - Dhimant Desai
- Department of Pharmacology, Penn State University, University Park 16801, PA, USA
| | - Arun K Sharma
- Department of Pharmacology, Penn State University, University Park 16801, PA, USA
| | - Shantu Amin
- Department of Pharmacology, Penn State University, University Park 16801, PA, USA
| | - Todd E Fox
- Department of Pharmacology, University of Virginia, Charlottesville 22908, VA, USA
| | - Mark Kester
- Department of Pharmacology, University of Virginia, Charlottesville 22908, VA, USA; Department of Molecular Physiology and Biophysics, University of Virginia, Charlottesville 22908, VA, USA
| | - John Katsaras
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge 37831, TN, USA; Joint Institute for Neutron Sciences, Oak Ridge National Laboratory, Oak Ridge 37831, TN, USA; Department of Physics and Astronomy, University of Tennessee, Knoxville 37996, TN, USA.
| | - Drew Marquardt
- Department of Chemistry and Biochemistry, University of Windsor, Windsor N9B 3P4, ON, Canada; Department of Physics, University of Windsor, Windsor N9B 3P4, ON, Canada.
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41
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Benedetto A, Kelley EG. Absorption of the [bmim][Cl] Ionic Liquid in DMPC Lipid Bilayers across Their Gel, Ripple, and Fluid Phases. J Phys Chem B 2022; 126:3309-3318. [PMID: 35472281 PMCID: PMC9082605 DOI: 10.1021/acs.jpcb.2c00710] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 04/11/2022] [Indexed: 12/19/2022]
Abstract
Lipid bilayers are a key component of cell membranes and play a crucial role in life and in bio-nanotechnology. As a result, controlling their physicochemical properties holds the promise of effective therapeutic strategies. Ionic liquids (ILs)─a vast class of complex organic electrolytes─have shown a high degree of affinity with lipid bilayers and can be exploited in this context. However, the chemical physics of IL absorption and partitioning into lipid bilayers is yet to be fully understood. This work focuses on the absorption of the model IL [bmim][Cl] into 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid bilayers across their gel, ripple, and fluid phases. Here, by small-angle neutron scattering, we show that (i) the IL cations are absorbed in the lipid bilayer in all its thermodynamic phases and (ii) the amount of IL inserted into the lipid phase increased with increasing temperature, changing from three to four IL cations per 10 lipids with increasing temperature from 10 °C in the gel phase to 40 °C in the liquid phase, respectively. An explicative hypothesis, based on the entropy gain coming from the IL hydration water, is presented to explain the observed temperature trend. The ability to control IL absorption with temperature can be used as a handle to tune the effect of ILs on biomembranes and can be exploited in bio-nanotechnological applications.
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Affiliation(s)
- Antonio Benedetto
- Department
of Science, University of Roma Tre, 00146 Rome, Italy
- School
of Physics, and Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland
- Laboratory
for Neutron Scattering, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Elizabeth G. Kelley
- NIST
Center for Neutron Research, National Institute
of Standards and Technology, Gaithersburg, Maryland 20899, United States
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42
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Saitov A, Kalutsky MA, Galimzyanov TR, Glasnov T, Horner A, Akimov SA, Pohl P. Determinants of Lipid Domain Size. Int J Mol Sci 2022; 23:ijms23073502. [PMID: 35408861 PMCID: PMC8998648 DOI: 10.3390/ijms23073502] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/21/2022] [Accepted: 03/21/2022] [Indexed: 12/20/2022] Open
Abstract
Lipid domains less than 200 nm in size may form a scaffold, enabling the concerted function of plasma membrane proteins. The size-regulating mechanism is under debate. We tested the hypotheses that large values of spontaneous monolayer curvature are incompatible with micrometer-sized domains. Here, we used the transition of photoswitchable lipids from their cylindrical conformation to a conical conformation to increase the negative curvature of a bilayer-forming lipid mixture. In contrast to the hypothesis, pre-existing micrometer-sized domains did not dissipate in our planar bilayers, as indicated by fluorescence images and domain mobility measurements. Elasticity theory supports the observation by predicting the zero free energy gain for splitting large domains into smaller ones. It also indicates an alternative size-determining mechanism: The cone-shaped photolipids reduce the line tension associated with lipid deformations at the phase boundary and thus slow down the kinetics of domain fusion. The competing influence of two approaching domains on the deformation of the intervening lipids is responsible for the kinetic fusion trap. Our experiments indicate that the resulting local energy barrier may restrict the domain size in a dynamic system.
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Affiliation(s)
- Ali Saitov
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, 4020 Linz, Austria; (A.S.); (A.H.)
| | - Maksim A. Kalutsky
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy Prospekt, 119071 Moscow, Russia; (M.A.K.); (T.R.G.); (S.A.A.)
- Department of Theoretical Physics and Quantum Technologies, National University of Science and Technology “MISiS”, 4 Leninskiy Prospekt, 119049 Moscow, Russia
| | - Timur R. Galimzyanov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy Prospekt, 119071 Moscow, Russia; (M.A.K.); (T.R.G.); (S.A.A.)
| | - Toma Glasnov
- Institute of Chemistry, University of Graz, 8010 Graz, Austria;
| | - Andreas Horner
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, 4020 Linz, Austria; (A.S.); (A.H.)
| | - Sergey A. Akimov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy Prospekt, 119071 Moscow, Russia; (M.A.K.); (T.R.G.); (S.A.A.)
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstraße 40, 4020 Linz, Austria; (A.S.); (A.H.)
- Correspondence:
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43
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Porras-Gómez M, Shoaib T, Steer D, Espinosa-Marzal RM, Leal C. Pathological cardiolipin-promoted membrane hemifusion stiffens pulmonary surfactant membranes. Biophys J 2022; 121:886-896. [PMID: 35176270 PMCID: PMC8943818 DOI: 10.1016/j.bpj.2022.02.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 01/17/2022] [Accepted: 02/09/2022] [Indexed: 11/27/2022] Open
Abstract
Lower tract respiratory diseases such as pneumonia are pervasive, affecting millions of people every year. The stability of the air/water interface in alveoli and the mechanical performance during the breathing cycle are regulated by the structural and elastic properties of pulmonary surfactant membranes (PSMs). Respiratory dysfunctions and pathologies often result in, or are caused by, impairment of the PSMs. However, a gap remains between our knowledge of the etiology of lung diseases and the fundamental properties of PSMs. For example, bacterial pneumonia in humans and mice has been associated with aberrant levels of cardiolipin, a mitochondrial-specific, highly unsaturated 4-tailed anionic phospholipid, in lung fluid, which likely disrupts the structural and mechanical integrity of PSMs. Specifically, cardiolipin is expected to significantly alter PSM elasticity due to its intrinsic molecular properties favoring membrane folding away from a flat configuration. In this paper, we investigate the structural and mechanical properties of the lipidic components of PSMs using lipid-based models as well as bovine extracts affected by the addition of pathological cardiolipin levels. Specifically, using a combination of optical and atomic force microscopy with a surface force apparatus, we demonstrate that cardiolipin strongly promotes hemifusion of PSMs and that these local membrane contacts propagate at larger scales, resulting in global stiffening of lung membranes.
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Affiliation(s)
- Marilyn Porras-Gómez
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois
| | - Tooba Shoaib
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois
| | - Dylan Steer
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois
| | - Rosa Maria Espinosa-Marzal
- Department of Civil and Environmental Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois
| | - Cecília Leal
- Department of Materials Science and Engineering, University of Illinois Urbana-Champaign, Urbana, Illinois.
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44
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Suresh P, London E. Using cyclodextrin-induced lipid substitution to study membrane lipid and ordered membrane domain (raft) function in cells. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183774. [PMID: 34534531 PMCID: PMC9128603 DOI: 10.1016/j.bbamem.2021.183774] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/30/2021] [Accepted: 09/08/2021] [Indexed: 02/03/2023]
Abstract
Methods for efficient cyclodextrin-induced lipid exchange have been developed in our lab. These make it possible to almost completely replace the lipids in the outer leaflet of artificial membranes or the plasma membranes of living cells with exogenous lipids. Lipid replacement/substitution allows detailed studies of how lipid composition and asymmetry influence the structure and function of membrane domains and membrane proteins. In this review, we both summarize progress on cyclodextrin exchange in cells, mainly by the use of methyl-alpha cyclodextrin to exchange phospholipids and sphingolipids, and discuss the issues to consider when carrying out lipid exchange experiments upon cells. Issues that impact interpretation of lipid exchange are also discussed. This includes how overly naïve interpretation of how lipid exchange-induced changes in domain formation can impact protein function.
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45
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Identifying Membrane Lateral Organization by Contrast-Matched Small Angle Neutron Scattering. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2022; 2402:163-177. [PMID: 34854044 DOI: 10.1007/978-1-0716-1843-1_14] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Lipid domains in model membranes are routinely studied to provide insight into the physical interactions that drive raft formation in cellular membranes. Using small angle neutron scattering, contrast-matching techniques enable the detection of lipid domains ranging from tens to hundreds of nanometers which are not accessible to other techniques without the use of extrinsic probes. Here, we describe a probe-free experimental approach and model-free analysis to identify lipid domains in freely floating vesicles of ternary phase separating lipid mixtures.
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46
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Fauquignon M, Ibarboure E, Le Meins JF. Hybrid polymer/lipid vesicles: Influence of polymer architecture and molar mass on line tension. Biophys J 2022; 121:61-67. [PMID: 34890579 PMCID: PMC8758416 DOI: 10.1016/j.bpj.2021.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 10/27/2021] [Accepted: 12/06/2021] [Indexed: 01/07/2023] Open
Abstract
Hybrid polymer/lipid vesicles are self-assembled structures that have been the subject of an increasing number of studies in recent years. They are particularly promising tools in the development of cell membrane models because they offer the possibility to fine-tune their membrane structure by adjusting the distribution of components (presence or absence of "raft-like" lipid domains), which is of prime importance to control their membrane properties. Line tension in multiphase membranes is known to be a key parameter on membrane structuration, but remains unexplored, either experimentally or by computer modeling for hybrid polymer/lipid vesicles. In this study, we were able to measure the line tension on different budded hybrid vesicles, using a micropipette aspiration technique, and show the influence of the molar mass and the architecture of block copolymers on line tension and its consequences for membrane structuration.
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Affiliation(s)
- Martin Fauquignon
- Université de Bordeaux, CNRS, Bordeaux INP, LCPO, UMR 5629, Pessac, France
| | - Emmanuel Ibarboure
- Université de Bordeaux, CNRS, Bordeaux INP, LCPO, UMR 5629, Pessac, France
| | - Jean-François Le Meins
- Université de Bordeaux, CNRS, Bordeaux INP, LCPO, UMR 5629, Pessac, France,Corresponding author
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47
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Hitaishi P, Mandal P, Ghosh SK. Partitioning of a Hybrid Lipid in Domains of Saturated and Unsaturated Lipids in a Model Cellular Membrane. ACS OMEGA 2021; 6:34546-34554. [PMID: 34963939 PMCID: PMC8697375 DOI: 10.1021/acsomega.1c04835] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Accepted: 11/30/2021] [Indexed: 06/14/2023]
Abstract
The cellular membranes are composed of hundreds of components such as lipids, proteins, and sterols that are chemically and physically distinct from each other. The lipid-lipid and lipid-protein interactions form domains in this membrane, which play vital roles in membrane physiology. The hybrid lipids (HLs) with one saturated and one unsaturated chain can control the shape and size of these domains, ensuring the thermodynamic stability of a membrane. In this study, the thermodynamics of mixing of a HL and its structural effects on the phase separated domains in a model membrane composed of a saturated and an unsaturated lipid have been investigated. The HL is observed to mix into an unsaturated lipid reducing the Gibbs free energy, whereas the mixing is unfavorable in a saturated lipid. The presence of an HL in an unsaturated lipid tends to increase its area fraction, which is reflected in the enhanced correlation length across the bilayers in a multilayered sample. There is a feeble effect on the domain structure of the saturated lipid due to the presence of the HLs at the phase boundary. This study concludes that the HLs preferentially participate in the unsaturated lipid regions compared to that of a saturated lipid.
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48
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Canner SW, Feller SE, Wassall SR. Molecular Organization of a Raft-like Domain in a Polyunsaturated Phospholipid Bilayer: A Supervised Machine Learning Analysis of Molecular Dynamics Simulations. J Phys Chem B 2021; 125:13158-13167. [PMID: 34812629 DOI: 10.1021/acs.jpcb.1c06511] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Numerous health benefits are associated with omega-3 polyunsaturated fatty acids (n-3 PUFA) consumed in fish oils. An understanding of the mechanism remains elusive. The plasma membrane as a site of action is the focus in this study. With large-scale all-atom MD simulations run on a model membrane (1050 lipid molecules), we observed the evolution over time (6 μs) of a circular (raft-like) domain composed of N-palmitoylsphingomyelin (PSM) and cholesterol embedded into a surrounding (non-raft) patch composed of polyunsaturated 1-palmitoyl-2-docosahexaenoylphosphatylcholine (PDPC) (1:1:1 mol). A supervised machine learning algorithm was developed to characterize the migration of each lipid based on molecular conformation and the local environment. PDPC molecules were seen to infiltrate the ordered raft-like domain in a small amount, while a small concentration of PSM and cholesterol molecules was seen to migrate into the disordered non-raft region. Enclosing the raft-like domain, a narrow (∼2 nm in width) interfacial zone composed of PDPC, PSM, and cholesterol that buffers the substantial difference in order (ΔSCD ≈ 0.12) between raft-like and non-raft environments was seen to form. Our results suggest that n-3 PUFA regulate the architecture of lipid rafts enriched in sphingolipids and cholesterol with a minimal effect on order within their interior in membranes.
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Affiliation(s)
- Samuel W Canner
- Department of Physics, IUPUI, Indianapolis, Indiana 46202-3273, United States.,Department of Computer and Information Science, IUPUI, Indianapolis, Indiana 46202-5132, United States
| | - Scott E Feller
- Department of Chemistry, Wabash College, Crawfordsville, Indiana 47933, United States
| | - Stephen R Wassall
- Department of Physics, IUPUI, Indianapolis, Indiana 46202-3273, United States
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49
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Perez-Salas U, Garg S, Gerelli Y, Porcar L. Deciphering lipid transfer between and within membranes with time-resolved small-angle neutron scattering. CURRENT TOPICS IN MEMBRANES 2021; 88:359-412. [PMID: 34862031 DOI: 10.1016/bs.ctm.2021.10.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This review focuses on time-resolved neutron scattering, particularly time-resolved small angle neutron scattering (TR-SANS), as a powerful in situ noninvasive technique to investigate intra- and intermembrane transport and distribution of lipids and sterols in lipid membranes. In contrast to using molecular analogues with potentially large chemical tags that can significantly alter transport properties, small angle neutron scattering relies on the relative amounts of the two most abundant isotope forms of hydrogen: protium and deuterium to detect complex membrane architectures and transport processes unambiguously. This review discusses advances in our understanding of the mechanisms that sustain lipid asymmetry in membranes-a key feature of the plasma membrane of cells-as well as the transport of lipids between membranes, which is an essential metabolic process.
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Affiliation(s)
- Ursula Perez-Salas
- Physics Department, University of Illinois at Chicago, Chicago, IL, United States.
| | - Sumit Garg
- Physics Department, University of Illinois at Chicago, Chicago, IL, United States
| | - Yuri Gerelli
- Department of Life and Environmental Sciences, Universita` Politecnica delle Marche, Ancona, Italy
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50
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Iriondo MN, Etxaniz A, Antón Z, Montes LR, Alonso A. Molecular and mesoscopic geometries in autophagosome generation. A review. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183731. [PMID: 34419487 DOI: 10.1016/j.bbamem.2021.183731] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/12/2021] [Accepted: 08/15/2021] [Indexed: 01/18/2023]
Abstract
Autophagy is an essential process in cell self-repair and survival. The centre of the autophagic event is the generation of the so-called autophagosome (AP), a vesicle surrounded by a double membrane (two bilayers). The AP delivers its cargo to a lysosome, for degradation and re-use of the hydrolysis products as new building blocks. AP formation is a very complex event, requiring dozens of specific proteins, and involving numerous instances of membrane biogenesis and architecture, including membrane fusion and fission. Many stages of AP generation can be rationalised in terms of curvature, both the molecular geometry of lipids interpreted in terms of 'intrinsic curvature', and the overall mesoscopic curvature of the whole membrane, as observed with microscopy techniques. The present contribution intends to bring together the worlds of biophysics and cell biology of autophagy, in the hope that the resulting cross-pollination will generate abundant fruit.
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Affiliation(s)
- Marina N Iriondo
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Asier Etxaniz
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Zuriñe Antón
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - L Ruth Montes
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Alicia Alonso
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain.
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