1
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Min S, Picou C, Jeong HJ, Bower A, Jeong K, Chung JK. Melittin-Phospholipase A 2 Synergism Is Mediated by Liquid-Liquid Miscibility Phase Transition in Giant Unilamellar Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:7456-7462. [PMID: 38546877 DOI: 10.1021/acs.langmuir.3c03920] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
The primary constituents of honeybee venom, melittin and phospholipase A2 (PLA2), display toxin synergism in which the PLA2 activity is significantly enhanced by the presence of melittin. It has been shown previously that this is accomplished by the disruption in lipid packing, which allows PLA2 to become processive on the membrane surface. In this work, we show that melittin is capable of driving miscibility phase transition in giant unilamellar vesicles (GUVs) and that it raises the miscibility transition temperature (Tmisc) in a concentration-dependent manner. The induced phase separation enhances the processivity of PLA2, particularly at its boundaries, where a substantial difference in domain thickness creates a membrane discontinuity. The catalytic action of PLA2, in response, induces changes in the membrane, rendering it more conducive to melittin binding. This, in turn, facilitates further lipid phase separation and eventual vesicle lysis. Overall, our results show that melittin has powerful membrane-altering capabilities that activate PLA2 in various membrane contexts. More broadly, they exemplify how this biochemical system actively modulates and capitalizes on the spatial distribution of membrane lipids to efficiently achieve its objectives.
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Affiliation(s)
- Sein Min
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 United States
| | - Cyrus Picou
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 United States
| | - Hye Jin Jeong
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 United States
| | - Adam Bower
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 United States
| | - Keunhong Jeong
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 United States
| | - Jean K Chung
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523 United States
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2
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Zhang T, Fu M, Yu T, Jiang F, Lyu S, Yang Q, Du Z, Liu X, Liu J, Yu Y. Molecular Interactions Between Egg White Peptides and Giant Unilamellar Vesicle Membranes: Effect of Peptide Localization on Membrane Fluidity. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024. [PMID: 38592417 DOI: 10.1021/acs.jafc.3c08291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
Bioactive peptides have been shown to affect cell membrane fluidity, which is an important indicator of the cell membrane structure and function. However, the underlying mechanism of egg white-derived bioactive peptide regulation of cell membrane fluidity has not been elucidated yet. The cell membrane fluidity was investigated by giant unilamellar vesicles in the present study. The results showed that peptides TCNW, ADWAK, ESIINF, VPIEGII, LVEEY, and WKLC connect to membranes through intermolecular interactions, such as hydrogen bonding and regulated membrane fluidity, in a concentration-dependent way. In addition, peptides prefer to localize in the hydrophobic core of the bilayers. This study provides a theoretical basis for analyzing the localization of egg white bioactive peptides in specific cell membrane regions and their influence on the cell membrane fluidity.
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Affiliation(s)
- Ting Zhang
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Menghan Fu
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Ting Yu
- Department of Nutrition, The Second Hospital of Jilin University, Changchun 130041, People's Republic of China
| | - Feng Jiang
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
- Department of Molecular & Integrative Physiology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Siwen Lyu
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Qi Yang
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Zhiyang Du
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Xuanting Liu
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Jingbo Liu
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Yiding Yu
- Jilin Provincial Key Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, People's Republic of China
- College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
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3
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Balakrishnan M, Kenworthy AK. Lipid Peroxidation Drives Liquid-Liquid Phase Separation and Disrupts Raft Protein Partitioning in Biological Membranes. J Am Chem Soc 2024; 146:1374-1387. [PMID: 38171000 PMCID: PMC10797634 DOI: 10.1021/jacs.3c10132] [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: 09/14/2023] [Revised: 12/06/2023] [Accepted: 12/07/2023] [Indexed: 01/05/2024]
Abstract
The peroxidation of membrane lipids by free radicals contributes to aging, numerous diseases, and ferroptosis, an iron-dependent form of cell death. Peroxidation changes the structure and physicochemical properties of lipids, leading to bilayer thinning, altered fluidity, and increased permeability of membranes in model systems. Whether and how lipid peroxidation impacts the lateral organization of proteins and lipids in biological membranes, however, remains poorly understood. Here, we employ cell-derived giant plasma membrane vesicles (GPMVs) as a model to investigate the impact of lipid peroxidation on ordered membrane domains, often termed membrane rafts. We show that lipid peroxidation induced by the Fenton reaction dramatically enhances the phase separation propensity of GPMVs into coexisting liquid-ordered (Lo) and liquid-disordered (Ld) domains and increases the relative abundance of the disordered phase. Peroxidation also leads to preferential accumulation of peroxidized lipids and 4-hydroxynonenal (4-HNE) adducts in the disordered phase, decreased lipid packing in both Lo and Ld domains, and translocation of multiple classes of raft proteins out of ordered domains. These findings indicate that the peroxidation of plasma membrane lipids disturbs many aspects of membrane rafts, including their stability, abundance, packing, and protein and lipid composition. We propose that these disruptions contribute to the pathological consequences of lipid peroxidation during aging and disease and thus serve as potential targets for therapeutic intervention.
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Affiliation(s)
- Muthuraj Balakrishnan
- Center
for Membrane and Cell Physiology, University
of Virginia, Charlottesville, Virginia 22903, United States
- Department
of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22903, United States
| | - Anne K. Kenworthy
- Center
for Membrane and Cell Physiology, University
of Virginia, Charlottesville, Virginia 22903, United States
- Department
of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22903, United States
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4
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Shelby SA, Veatch SL. The Membrane Phase Transition Gives Rise to Responsive Plasma Membrane Structure and Function. Cold Spring Harb Perspect Biol 2023; 15:a041395. [PMID: 37553204 PMCID: PMC10626261 DOI: 10.1101/cshperspect.a041395] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2023]
Abstract
Several groups have recently reported evidence for the emergence of domains in cell plasma membranes when membrane proteins are organized by ligand binding or assembly of membrane proximal scaffolds. These domains recruit and retain components that favor the liquid-ordered phase, adding to a decades-old literature interrogating the contribution of membrane phase separation in plasma membrane organization and function. Here we propose that both past and present observations are consistent with a model in which membranes have a high compositional susceptibility, arising from their thermodynamic state in a single phase that is close to a miscibility phase transition. This rigorous framework naturally allows for both transient structure in the form of composition fluctuations and long-lived structure in the form of induced domains. In this way, the biological tuning of plasma membrane composition enables a responsive compositional landscape that facilitates and augments cellular biochemistry vital to plasma membrane functions.
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Affiliation(s)
- Sarah A Shelby
- Biochemistry & Cellular and Molecular Biology, University of Tennessee Knoxville, Knoxville, Tennessee 37996, USA
| | - Sarah L Veatch
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan 48109, USA
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5
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Balakrishnan M, Kenworthy AK. Lipid peroxidation drives liquid-liquid phase separation and disrupts raft protein partitioning in biological membranes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.12.557355. [PMID: 37745342 PMCID: PMC10515805 DOI: 10.1101/2023.09.12.557355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The peroxidation of membrane lipids by free radicals contributes to aging, numerous diseases, and ferroptosis, an iron-dependent form of cell death. Peroxidation changes the structure, conformation and physicochemical properties of lipids, leading to major membrane alterations including bilayer thinning, altered fluidity, and increased permeability. Whether and how lipid peroxidation impacts the lateral organization of proteins and lipids in biological membranes, however, remains poorly understood. Here, we employ cell-derived giant plasma membrane vesicles (GPMVs) as a model to investigate the impact of lipid peroxidation on ordered membrane domains, often termed membrane rafts. We show that lipid peroxidation induced by the Fenton reaction dramatically enhances phase separation propensity of GPMVs into co-existing liquid ordered (raft) and liquid disordered (non-raft) domains and increases the relative abundance of the disordered, non-raft phase. Peroxidation also leads to preferential accumulation of peroxidized lipids and 4-hydroxynonenal (4-HNE) adducts in the disordered phase, decreased lipid packing in both raft and non-raft domains, and translocation of multiple classes of proteins out of rafts. These findings indicate that peroxidation of plasma membrane lipids disturbs many aspects of membrane rafts, including their stability, abundance, packing, and protein and lipid composition. We propose that these disruptions contribute to the pathological consequences of lipid peroxidation during aging and disease, and thus serve as potential targets for therapeutic intervention.
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Affiliation(s)
- Muthuraj Balakrishnan
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Anne K. Kenworthy
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
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6
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Santiago JA, Monroy F. Inhomogeneous Canham-Helfrich Abscission in Catenoid Necks under Critical Membrane Mosaicity. MEMBRANES 2023; 13:796. [PMID: 37755218 PMCID: PMC10534449 DOI: 10.3390/membranes13090796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 09/12/2023] [Accepted: 09/12/2023] [Indexed: 09/28/2023]
Abstract
The mechanical effects of membrane compositional inhomogeneities are analyzed in a process analogous to neck formation in cellular membranes. We cast on the Canham-Helfrich model of fluid membranes with both the spontaneous curvature and the surface tension being non-homogeneous functions along the cell membrane. The inhomogeneous distribution of necking forces is determined by the equilibrium mechanical equations and the boundary conditions as considered in the axisymmetric setting compatible with the necking process. To establish the role played by mechanical inhomogeneity, we focus on the catenoid, a surface of zero mean curvature. Analytic solutions are shown to exist for the spontaneous curvature and the constrictive forces in terms of the border radii. Our theoretical analysis shows that the inhomogeneous distribution of spontaneous curvature in a mosaic-like neck constrictional forces potentially contributes to the membrane scission under minimized work in living cells.
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Affiliation(s)
- José Antonio Santiago
- Departamento de Matemáticas Aplicadas y Sistemas, Universidad Autónoma Metropolitana Cuajimalpa, Vasco de Quiroga 4871, Ciudad de México 05384, Mexico
- Departamento de Química Física, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid, Spain;
- Translational Biophysics, Institute for Biomedical Research, Hospital Doce de Octubre (imas12), Av. Andalucía s/n, 28041 Madrid, Spain
| | - Francisco Monroy
- Departamento de Química Física, Universidad Complutense de Madrid, Av. Complutense s/n, 28040 Madrid, Spain;
- Translational Biophysics, Institute for Biomedical Research, Hospital Doce de Octubre (imas12), Av. Andalucía s/n, 28041 Madrid, Spain
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7
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Sakamoto K, Akimoto T, Muramatsu M, Sansom MSP, Metzler R, Yamamoto E. Heterogeneous biological membranes regulate protein partitioning via fluctuating diffusivity. PNAS NEXUS 2023; 2:pgad258. [PMID: 37593200 PMCID: PMC10427746 DOI: 10.1093/pnasnexus/pgad258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 06/22/2023] [Accepted: 07/27/2023] [Indexed: 08/19/2023]
Abstract
Cell membranes phase separate into ordered L o and disordered L d domains depending on their compositions. This membrane compartmentalization is heterogeneous and regulates the localization of specific proteins related to cell signaling and trafficking. However, it is unclear how the heterogeneity of the membranes affects the diffusion and localization of proteins in L o and L d domains. Here, using Langevin dynamics simulations coupled with the phase-field (LDPF) method, we investigate several tens of milliseconds-scale diffusion and localization of proteins in heterogeneous biological membrane models showing phase separation into L o and L d domains. The diffusivity of proteins exhibits temporal fluctuations depending on the field composition. Increases in molecular concentrations and domain preference of the molecule induce subdiffusive behavior due to molecular collisions by crowding and confinement effects, respectively. Moreover, we quantitatively demonstrate that the protein partitioning into the L o domain is determined by the difference in molecular diffusivity between domains, molecular preference of domain, and molecular concentration. These results pave the way for understanding how biological reactions caused by molecular partitioning may be controlled in heterogeneous media. Moreover, the methodology proposed here is applicable not only to biological membrane systems but also to the study of diffusion and localization phenomena of molecules in various heterogeneous systems.
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Affiliation(s)
- Ken Sakamoto
- Department of System Design Engineering, Keio University, Yokohama, Kanagawa 223-8522, Japan
| | - Takuma Akimoto
- Department of Physics, Tokyo University of Science, Noda, Chiba 278-8510, Japan
| | - Mayu Muramatsu
- Department of Mechanical Engineering, Keio University, Yokohama, Kanagawa 223-8522, Japan
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Ralf Metzler
- Institute of Physics & Astronomy, University of Potsdam, Potsdam-Golm 14476, Germany
- Asia Pacific Centre for Theoretical Physics, Pohang 37673, Republic of Korea
| | - Eiji Yamamoto
- Department of System Design Engineering, Keio University, Yokohama, Kanagawa 223-8522, Japan
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8
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Whiting R, Stanton S, Kucheriava M, Smith AR, Pitts M, Robertson D, Kammer J, Li Z, Fologea D. Hypo-Osmotic Stress and Pore-Forming Toxins Adjust the Lipid Order in Sheep Red Blood Cell Membranes. MEMBRANES 2023; 13:620. [PMID: 37504986 PMCID: PMC10385129 DOI: 10.3390/membranes13070620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/07/2023] [Accepted: 06/22/2023] [Indexed: 07/29/2023]
Abstract
Lipid ordering in cell membranes has been increasingly recognized as an important factor in establishing and regulating a large variety of biological functions. Multiple investigations into lipid organization focused on assessing ordering from temperature-induced phase transitions, which are often well outside the physiological range. However, particular stresses elicited by environmental factors, such as hypo-osmotic stress or protein insertion into membranes, with respect to changes in lipid status and ordering at constant temperature are insufficiently described. To fill these gaps in our knowledge, we exploited the well-established ability of environmentally sensitive membrane probes to detect intramembrane changes at the molecular level. Our steady state fluorescence spectroscopy experiments focused on assessing changes in optical responses of Laurdan and diphenylhexatriene upon exposure of red blood cells to hypo-osmotic stress and pore-forming toxins at room temperature. We verified our utilized experimental systems by a direct comparison of the results with prior reports on artificial membranes and cholesterol-depleted membranes undergoing temperature changes. The significant changes observed in the lipid order after exposure to hypo-osmotic stress or pore-forming toxins resembled phase transitions of lipids in membranes, which we explained by considering the short-range interactions between membrane components and the hydrophobic mismatch between membrane thickness and inserted proteins. Our results suggest that measurements of optical responses from the membrane probes constitute an appropriate method for assessing the status of lipids and phase transitions in target membranes exposed to mechanical stresses or upon the insertion of transmembrane proteins.
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Affiliation(s)
- Rose Whiting
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Sevio Stanton
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | | | - Aviana R Smith
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Matt Pitts
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
| | - Daniel Robertson
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Jacob Kammer
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Department of Family Medicine, Idaho College of Osteopathic Medicine, Meridian, ID 83642, USA
| | - Zhiyu Li
- Department of Physics, Boise State University, Boise, ID 83725, USA
| | - Daniel Fologea
- Department of Physics, Boise State University, Boise, ID 83725, USA
- Biomolecular Sciences Graduate Program, Boise State University, Boise, ID 83725, USA
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9
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Shelby SA, Castello-Serrano I, Wisser KC, Levental I, Veatch SL. Membrane phase separation drives responsive assembly of receptor signaling domains. Nat Chem Biol 2023; 19:750-758. [PMID: 36997644 PMCID: PMC10771812 DOI: 10.1038/s41589-023-01268-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 01/17/2023] [Indexed: 04/01/2023]
Abstract
Plasma membrane heterogeneity has been tied to a litany of cellular functions and is often explained by analogy to membrane phase separation; however, models based on phase separation alone fall short of describing the rich organization available within cell membranes. Here we present comprehensive experimental evidence motivating an updated model of plasma membrane heterogeneity in which membrane domains assemble in response to protein scaffolds. Quantitative super-resolution nanoscopy measurements in live B lymphocytes detect membrane domains that emerge upon clustering B cell receptors (BCRs). These domains enrich and retain membrane proteins based on their preference for the liquid-ordered phase. Unlike phase-separated membranes that consist of binary phases with defined compositions, membrane composition at BCR clusters is modulated through the protein constituents in clusters and the composition of the membrane overall. This tunable domain structure is detected through the variable sorting of membrane probes and impacts the magnitude of BCR activation.
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Affiliation(s)
- Sarah A Shelby
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee Knoxville, Knoxville, TN, USA
| | - Ivan Castello-Serrano
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | | | - Ilya Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Sarah L Veatch
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA.
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10
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Rubio-Sánchez R, Mognetti BM, Cicuta P, Di Michele L. DNA-Origami Line-Actants Control Domain Organization and Fission in Synthetic Membranes. J Am Chem Soc 2023; 145:11265-11275. [PMID: 37163977 DOI: 10.1021/jacs.3c01493] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Cells can precisely program the shape and lateral organization of their membranes using protein machinery. Aiming to replicate a comparable degree of control, here we introduce DNA-origami line-actants (DOLAs) as synthetic analogues of membrane-sculpting proteins. DOLAs are designed to selectively accumulate at the line-interface between coexisting domains in phase-separated lipid membranes, modulating the tendency of the domains to coalesce. With experiments and coarse-grained simulations, we demonstrate that DOLAs can reversibly stabilize two-dimensional analogues of Pickering emulsions on synthetic giant liposomes, enabling dynamic programming of membrane lateral organization. The control afforded over membrane structure by DOLAs extends to three-dimensional morphology, as exemplified by a proof-of-concept synthetic pathway leading to vesicle fission. With DOLAs we lay the foundations for mimicking, in synthetic systems, some of the critical membrane-hosted functionalities of biological cells, including signaling, trafficking, sensing, and division.
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Affiliation(s)
- Roger Rubio-Sánchez
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, United Kingdom
- fabriCELL, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, United Kingdom
- Biological and Soft Systems, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Bortolo Matteo Mognetti
- Interdisciplinary Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles (ULB), Campus Plaine, CP 231, Boulevard du Triomphe, B-1050 Brussels, Belgium
| | - Pietro Cicuta
- Biological and Soft Systems, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Lorenzo Di Michele
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge CB3 0AS, United Kingdom
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, United Kingdom
- fabriCELL, Molecular Sciences Research Hub, Imperial College London, London W12 0BZ, United Kingdom
- Biological and Soft Systems, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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11
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Liu Z, Yethiraj A, Cui Q. Sensitive and selective polymer condensation at membrane surface driven by positive co-operativity. Proc Natl Acad Sci U S A 2023; 120:e2212516120. [PMID: 37018196 PMCID: PMC10104518 DOI: 10.1073/pnas.2212516120] [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: 07/20/2022] [Accepted: 03/06/2023] [Indexed: 04/06/2023] Open
Abstract
Biomolecular phase separation has emerged as an essential mechanism for cellular organization. How cells respond to environmental stimuli in a robust and sensitive manner to build functional condensates at the proper time and location is only starting to be understood. Recently, lipid membranes have been recognized as an important regulatory center for biomolecular condensation. However, how the interplay between the phase behaviors of cellular membranes and surface biopolymers may contribute to the regulation of surface condensation remains to be elucidated. Using simulations and a mean-field theoretical model, we show that two key factors are the membrane's tendency to phase-separate and the surface polymer's ability to reorganize local membrane composition. Surface condensate forms with high sensitivity and selectivity in response to features of biopolymer when positive co-operativity is established between coupled growth of the condensate and local lipid domains. This effect relating the degree of membrane-surface polymer co-operativity and condensate property regulation is shown to be robust by different ways of tuning the co-operativity, such as varying membrane protein obstacle concentration, lipid composition, and the affinity between lipid and polymer. The general physical principle emerged from the current analysis may have implications in other biological processes and beyond.
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Affiliation(s)
- Zhuang Liu
- Department of Physics, Boston University, Boston, MA02215
| | - Arun Yethiraj
- Department of Chemistry, University of Wisconsin, Madison, WI53706
| | - Qiang Cui
- Department of Physics, Boston University, Boston, MA02215
- Department of Chemistry, Boston University, Boston, MA02215
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12
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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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13
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Shaw TR, Wisser KC, Schaffner TA, Gaffney AD, Machta BB, Veatch SL. Chemical potential measurements constrain models of cholesterol-phosphatidylcholine interactions. Biophys J 2023; 122:1105-1117. [PMID: 36785512 PMCID: PMC10111267 DOI: 10.1016/j.bpj.2023.02.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 12/12/2022] [Accepted: 02/01/2023] [Indexed: 02/15/2023] Open
Abstract
Bilayer membranes composed of cholesterol and phospholipids exhibit diverse forms of nonideal mixing. In particular, many previous studies document macroscopic liquid-liquid phase separation as well as nanometer-scale heterogeneity in membranes of phosphatidylcholine (PC) lipids and cholesterol. Here, we present experimental measurements of cholesterol chemical potential (μc) in binary membranes containing dioleoyl PC (DOPC), 1-palmitoyl-2-oleoyl PC (POPC), or dipalmitoyl PC (DPPC), and in ternary membranes of DOPC and DPPC, referenced to crystalline cholesterol. μc is the thermodynamic quantity that dictates the availability of cholesterol to bind other factors, and notably must be equal between coexisting phases of a phase separated mixture. It is simply related to concentration under conditions of ideal mixing, but is far from ideal for the majority of lipid mixtures investigated here. Measurements of μc can vary with phospholipid composition by 1.5 kBT at constant cholesterol mole fraction implying a more than fivefold change in its availability for binding receptors and other reactions. Experimental measurements are fit to thermodynamic models including cholesterol-DPPC complexes or pairwise interactions between lipid species to provide intuition about the magnitude of interactions. These findings reinforce that μc depends on membrane composition overall, suggesting avenues for cells to alter the availability of cholesterol without varying cholesterol concentration.
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Affiliation(s)
- Thomas R Shaw
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan; Program in Applied Physics, University of Michigan, Ann Arbor, Michigan
| | | | | | - Anna D Gaffney
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan
| | | | - Sarah L Veatch
- Program in Biophysics, University of Michigan, Ann Arbor, Michigan; Program in Applied Physics, University of Michigan, Ann Arbor, Michigan.
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14
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Veatch SL, Rogers N, Decker A, Shelby SA. The plasma membrane as an adaptable fluid mosaic. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184114. [PMID: 36581017 PMCID: PMC9922517 DOI: 10.1016/j.bbamem.2022.184114] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/18/2022] [Accepted: 12/20/2022] [Indexed: 12/27/2022]
Abstract
The fluid mosaic model proposed by Singer and Nicolson established a powerful framework to interrogate biological membranes that has stood the test of time. They proposed that the membrane is a simple fluid, meaning that proteins and lipids are randomly distributed over distances larger than those dictated by direct interactions. Here we present an update to this model that describes a spatially adaptable fluid membrane capable of tuning local composition in response to forces originating outside the membrane plane. This revision is rooted in the thermodynamics of lipid mixtures, draws from recent experimental results, and suggests new modes of membrane function.
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Affiliation(s)
- Sarah L Veatch
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA.
| | - Nat Rogers
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA
| | - Adam Decker
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA
| | - Sarah A Shelby
- Program in Biophysics, University of Michigan, Ann Arbor, MI, USA.
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15
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Duncan AL, Pezeshkian W. Mesoscale simulations: An indispensable approach to understand biomembranes. Biophys J 2023:S0006-3495(23)00123-6. [PMID: 36809878 DOI: 10.1016/j.bpj.2023.02.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/10/2022] [Accepted: 02/13/2023] [Indexed: 02/23/2023] Open
Abstract
Computer simulation techniques form a versatile tool, a computational microscope, for exploring biological processes. This tool has been particularly effective in exploring different features of biological membranes. In recent years, thanks to elegant multiscale simulation schemes, some fundamental limitations of investigations by distinct simulation techniques have been resolved. As a result, we are now capable of exploring processes spanning multiple scales beyond the capacity of any single technique. In this perspective, we argue that mesoscale simulations require more attention and must be further developed to fill evident gaps in a quest toward simulating and modeling living cell membranes.
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Affiliation(s)
- Anna L Duncan
- Department of Chemistry, Aarhus University, Aarhus C, Denmark.
| | - Weria Pezeshkian
- Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
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16
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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: 17] [Impact Index Per Article: 17.0] [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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17
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Woodward X, Javanainen M, Fábián B, Kelly CV. Nanoscale membrane curvature sorts lipid phases and alters lipid diffusion. Biophys J 2023:S0006-3495(23)00001-2. [PMID: 36604961 DOI: 10.1016/j.bpj.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/23/2022] [Accepted: 01/03/2023] [Indexed: 01/06/2023] Open
Abstract
The precise spatiotemporal control of nanoscale membrane shape and composition is the result of a complex interplay of individual and collective molecular behaviors. Here, we employed single-molecule localization microscopy and computational simulations to observe single-lipid diffusion and sorting in model membranes with varying compositions, phases, temperatures, and curvatures. Supported lipid bilayers were created over 50-nm-radius nanoparticles to mimic the size of naturally occurring membrane buds, such as endocytic pits and the formation of viral envelopes. The curved membranes recruited liquid-disordered lipid phases while altering the diffusion and sorting of tracer lipids. Disorder-preferring fluorescent lipids sorted to and experienced faster diffusion on the nanoscale curvature only when embedded in a membrane capable of sustaining lipid phase separation at low temperatures. The curvature-induced sorting and faster diffusion even occurred when the sample temperature was above the miscibility temperature of the planar membrane, implying that the nanoscale curvature could induce phase separation in otherwise homogeneous membranes. Further confirmation and understanding of these results are provided by continuum and coarse-grained molecular dynamics simulations with explicit and spontaneous curvature-phase coupling, respectively. The curvature-induced membrane compositional heterogeneity and altered dynamics were achieved only with a coupling of the curvature with a lipid phase separation. These cross-validating results demonstrate the complex interplay of lipid phases, molecular diffusion, and nanoscale membrane curvature that are critical for membrane functionality.
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Affiliation(s)
- Xinxin Woodward
- Department of Physics and Astronomy, Wayne State University, Detroit, Michigan
| | - Matti Javanainen
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic; Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Balázs Fábián
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Prague, Czech Republic
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, Michigan.
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18
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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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19
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Jiang F, Liu J, Du Z, Liu X, Shang X, Yu Y, Zhang T. Soybean meal peptides regulated membrane phase of giant unilamellar vesicles: A key role for bilayer amphipathic region localization. Food Res Int 2022; 162:111924. [DOI: 10.1016/j.foodres.2022.111924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Revised: 07/25/2022] [Accepted: 09/07/2022] [Indexed: 11/29/2022]
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20
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Influence of Phase Transitions on Diffusive Molecular Transport Across Biological Membranes. Angew Chem Int Ed Engl 2022; 61:e202205608. [DOI: 10.1002/anie.202205608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Indexed: 11/07/2022]
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21
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Wu T, Wilhelm MJ, Ma J, Li Y, Wu Y, Dai HL. Influence of Phase Transitions on Diffusive Molecular Transport Across Biological Membranes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tong Wu
- Temple University Department of Chemistry UNITED STATES
| | - Michael J. Wilhelm
- Temple University Department of Chemistry 1901 N. 13th Street 19122 Philadelphia UNITED STATES
| | - Jianqiang Ma
- Temple University Department of Chemistry UNITED STATES
| | - Yujie Li
- Temple University Department of Chemistry UNITED STATES
| | - Yuhao Wu
- Temple University Department of Chemistry UNITED STATES
| | - Hai-Lung Dai
- Temple University Department of Chemistry UNITED STATES
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22
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Haldar S. Delving into Membrane Heterogeneity Utilizing Fluorescence Lifetime Distribution Analysis. J Membr Biol 2022; 255:553-561. [PMID: 35486159 DOI: 10.1007/s00232-022-00235-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 03/29/2022] [Indexed: 12/12/2022]
Abstract
Lipid bilayer membranes are indispensable parts of cellular architecture. One of the integral properties of bilayer membranes is the environmental heterogeneity over a wide range of spatiotemporal scales. The environmental heterogeneity is a manifestation of the dynamic and compositional anisotropy in the plane of the membrane as well as along the bilayer normal. Fluorescence lifetime distribution analysis provides a spectroscopic tool to quantitatively characterize such heterogeneities. The review discusses recent applications of fluorescence lifetime distribution analysis utilizing the maximum entropy method to characterize horizontal and vertical heterogeneities in membranes.
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Affiliation(s)
- Sourav Haldar
- Division of Virus Research and Therapeutics, CSIR- Central Drug Research Institute, Lucknow, Uttar Pradesh, 226031, India.
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23
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Bag N, London E, Holowka DA, Baird BA. Transbilayer Coupling of Lipids in Cells Investigated by Imaging Fluorescence Correlation Spectroscopy. J Phys Chem B 2022; 126:2325-2336. [PMID: 35294838 DOI: 10.1021/acs.jpcb.2c00117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Plasma membranes host numerous receptors, sensors, and ion channels involved in cellular signaling. Phase separation within the plasma membrane has emerged as a key biophysical regulator of signaling reactions in multiple physiological and pathological contexts. There is much evidence that plasma membrane composition supports the coexistence of liquid-ordered (Lo) and liquid-disordered (Ld) phases or domains at physiological conditions. However, this phase/domain separation is nanoscopic and transient in live cells. It has been recently proposed that transbilayer coupling between the inner and outer leaflets of the plasma membrane is driven by their asymmetric lipid distribution and by dynamic cytoskeleton-lipid composites that contribute to the formation and transience of Lo/Ld phase separation in live cells. In this Perspective, we highlight new approaches to investigate how transbilayer coupling may influence phase separation. For quantitative evaluation of the impact of these interactions, we introduce an experimental strategy centered around Imaging Fluorescence Correlation Spectroscopy (ImFCS), which measures membrane diffusion with very high precision. To demonstrate this strategy, we choose two well-established model systems for transbilayer interactions: cross-linking by multivalent antigen of immunoglobulin E bound to receptor FcεRI and cross-linking by cholera toxin B of GM1 gangliosides. We discuss emerging methods to systematically perturb membrane lipid composition, particularly exchange of outer leaflet lipids with exogenous lipids using methyl alpha cyclodextrin. These selective perturbations may be quantitatively evaluated with ImFCS and other high-resolution biophysical tools to discover novel principles of lipid-mediated phase separation in live cells in the context of their pathophysiological relevance.
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Affiliation(s)
- Nirmalya Bag
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Erwin London
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York 11794, United States
| | - David A Holowka
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
| | - Barbara A Baird
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States
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24
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Jiang F, Liu J, Niu X, Zhang D, Wang E, Zhang T. Egg White Peptides Increased the Membrane Liquid-Ordered Phase of Giant Unilamellar Vesicles: Visualization, Localization, and Phase Regulation Mechanism. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:2042-2050. [PMID: 35129984 DOI: 10.1021/acs.jafc.1c07846] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Cell membranes are heterogeneous and consist of liquid-ordered (Lo) and liquid-disordered (Ld) phases due to phase separation. Membrane regulation of egg white peptides (LCAY and QVPLW) was confirmed in our previous study. However, the underlying mechanism of phase regulation by the peptides has not been elucidated. This study aimed to explore the effect of LCAY and QVPLW on the membrane phase separation and illustrate their mechanism by giant unilamellar vesicles (GUVs). Based on phase separation visualization, LCAY and QVPLW were found to increase the Lo phase by rearranging lipids and ordering the Ld phase. LCAY and QVPLW can bind to the GUVs and localize in the amphiphilic region of the membrane. By hydrogen bonds and hydrophobic interactions, LCAY and QVPLW may play a cholesterol-like role in regulating phase separation.
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Affiliation(s)
- Feng Jiang
- Jilin Provincial Key Laboratory of Nutrition and Functional Food and College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Jingbo Liu
- Jilin Provincial Key Laboratory of Nutrition and Functional Food and College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Xiaodi Niu
- Jilin Provincial Key Laboratory of Nutrition and Functional Food and College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Deju Zhang
- Food and Nutritional Sciences, School of Biological Sciences, The University of Hong Kong 999077, Pokfulam, Hong Kong
| | - Erlei Wang
- Jilin Provincial Key Laboratory of Nutrition and Functional Food and College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
| | - Ting Zhang
- Jilin Provincial Key Laboratory of Nutrition and Functional Food and College of Food Science and Engineering, Jilin University, Changchun 130062, People's Republic of China
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25
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Gohrbandt M, Lipski A, Grimshaw JW, Buttress JA, Baig Z, Herkenhoff B, Walter S, Kurre R, Deckers-Hebestreit G, Strahl H. Low membrane fluidity triggers lipid phase separation and protein segregation in living bacteria. EMBO J 2022; 41:e109800. [PMID: 35037270 PMCID: PMC8886542 DOI: 10.15252/embj.2021109800] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/19/2021] [Accepted: 12/21/2021] [Indexed: 11/09/2022] Open
Abstract
All living organisms adapt their membrane lipid composition in response to changes in their environment or diet. These conserved membrane‐adaptive processes have been studied extensively. However, key concepts of membrane biology linked to regulation of lipid composition including homeoviscous adaptation maintaining stable levels of membrane fluidity, and gel‐fluid phase separation resulting in domain formation, heavily rely upon in vitro studies with model membranes or lipid extracts. Using the bacterial model organisms Escherichia coli and Bacillus subtilis, we now show that inadequate in vivo membrane fluidity interferes with essential complex cellular processes including cytokinesis, envelope expansion, chromosome replication/segregation and maintenance of membrane potential. Furthermore, we demonstrate that very low membrane fluidity is indeed capable of triggering large‐scale lipid phase separation and protein segregation in intact, protein‐crowded membranes of living cells; a process that coincides with the minimal level of fluidity capable of supporting growth. Importantly, the in vivo lipid phase separation is not associated with a breakdown of the membrane diffusion barrier function, thus explaining why the phase separation process induced by low fluidity is biologically reversible.
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Affiliation(s)
- Marvin Gohrbandt
- Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
| | - André Lipski
- Lebensmittelmikrobiologie und -hygiene, Institut für Ernährungs- und Lebensmittelwissenschaften, Rheinische Friedrich-Wilhelms-Universität Bonn, Bonn, Germany
| | - James W Grimshaw
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Jessica A Buttress
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Zunera Baig
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Brigitte Herkenhoff
- Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
| | - Stefan Walter
- Mikrobiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Osnabrück, Germany
| | - Rainer Kurre
- Center of Cellular Nanoanalytics, Integrated Bioimaging Facility, Universität Osnabrück, Osnabrück, Germany
| | | | - Henrik Strahl
- Centre for Bacterial Cell Biology, Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
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26
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Steck TL, Tabei SMA, Lange Y. A basic model for cell cholesterol homeostasis. Traffic 2021; 22:471-481. [PMID: 34528339 DOI: 10.1111/tra.12816] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/26/2021] [Accepted: 09/13/2021] [Indexed: 11/30/2022]
Abstract
Cells manage their cholesterol by negative feedback using a battery of sterol-responsive proteins. How these activities are coordinated so as to specify the abundance and distribution of the sterol is unclear. We present a simple mathematical model that addresses this question. It assumes that almost all of the cholesterol is associated with phospholipids in stoichiometric complexes. A small fraction of the sterol is uncomplexed and thermodynamically active. It equilibrates among the organelles, setting their sterol level according to the affinity of their phospholipids. The activity of the homeostatic proteins in the cytoplasmic membranes is then set by their fractional saturation with uncomplexed cholesterol in competition with the phospholipids. The high-affinity phospholipids in the plasma membrane (PM) are filled to near stoichiometric equivalence, giving it most of the cell sterol. Notably, the affinity of the phospholipids in the endomembranes (EMs) is lower by orders of magnitude than that of the phospholipids in the PM. Thus, the small amount of sterol in the EMs rests far below stoichiometric capacity. Simulations match a variety of experimental data. The model captures the essence of cell cholesterol homeostasis, makes coherent a diverse set of experimental findings, provides a surprising prediction and suggests new experiments.
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Affiliation(s)
- Theodore L Steck
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA
| | - S M Ali Tabei
- Department of Physics, University of Northern Iowa, Cedar Falls, Iowa, USA
| | - Yvonne Lange
- Department of Pathology, Rush University Medical Center, Chicago, Illinois, USA
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27
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Preferential Protein Partitioning in Biological Membrane with Coexisting Liquid Ordered and Liquid Disordered Phase Behavior: Underlying Design Principles. J Membr Biol 2020; 253:551-562. [PMID: 33170308 DOI: 10.1007/s00232-020-00150-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 10/31/2020] [Indexed: 12/17/2022]
Abstract
Several studies now show that certain proteins exhibit selective preference toward liquid ordered (L[Formula: see text]) or toward liquid disordered (L[Formula: see text]) regions of the heterogeneous membrane and some of them have preference for the L[Formula: see text]-L[Formula: see text] interface. Spatially heterogenous organization of lipids, enriched in specific protein molecules, function as platforms for signaling and are involved in several other physiologically critical functions. In this review, we collate together some of the experimental observations of cases where proteins preferentially segregate into different phases and highlight the importance of these preferential localization in terms of underlying functions. We also try to understand the structural features and chemical makeup of the membrane-interacting motifs of these proteins. Finally, we put forth some preliminary analysis on class I viral fusion proteins, some of which are known to partition at the L[Formula: see text]-L[Formula: see text] interface, and through them we try to understand the evolutionary design principles of phase segregating proteins. Put together, this review summarizes the existing studies on preferential partitioning of proteins into different membrane phases while emphasizing the need to understand the molecular design-level features that can help us "engineer" functionally rich peptides and proteins with a programmed membrane partitioning.
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