1
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Rinaldin M, Ten Haaf SLD, Vegter EJ, van der Wel C, Fonda P, Giomi L, Kraft DJ. Lipid membranes supported by polydimethylsiloxane substrates with designed geometry. SOFT MATTER 2024. [PMID: 39046306 DOI: 10.1039/d4sm00380b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/25/2024]
Abstract
The membrane curvature of cells and intracellular compartments continuously adapts to enable cells to perform vital functions, from cell division to signal trafficking. Understanding how membrane geometry affects these processes in vivo is challenging because of the biochemical and geometrical complexity as well as the short time and small length scales involved in cellular processes. By contrast, in vitro model membranes with engineered curvature would provide a versatile platform for this investigation and applications to biosensing and biocomputing. Here, we present a strategy that allows fabrication of lipid membranes with designed shape by combining 3D micro-printing and replica-molding lithography with polydimethylsiloxane to create curved micrometer-sized scaffolds with virtually any geometry. The resulting supported lipid membranes are homogeneous and fluid. We demonstrate the versatility of the system by fabricating structures of interesting combinations of mean and Gaussian curvature. We study the lateral phase separation and how local curvature influences the effective diffusion coefficient. Overall, we offer a bio-compatible platform for understanding curvature-dependent cellular processes and developing programmable bio-interfaces for living cells and nanostructures.
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Affiliation(s)
- Melissa Rinaldin
- Leiden Institute of Physics, University of Leiden, 2300 RA Leiden, The Netherlands.
- Instituut-Lorentz, Universiteit Leiden, Leiden, 2300 RA, The Netherlands
| | | | - Ernst J Vegter
- Leiden Institute of Physics, University of Leiden, 2300 RA Leiden, The Netherlands.
| | - Casper van der Wel
- Leiden Institute of Physics, University of Leiden, 2300 RA Leiden, The Netherlands.
| | - Piermarco Fonda
- Instituut-Lorentz, Universiteit Leiden, Leiden, 2300 RA, The Netherlands
| | - Luca Giomi
- Instituut-Lorentz, Universiteit Leiden, Leiden, 2300 RA, The Netherlands
| | - Daniela J Kraft
- Leiden Institute of Physics, University of Leiden, 2300 RA Leiden, The Netherlands.
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2
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Cárdenas H, Kamrul-Bahrin MAH, Seddon D, Othman J, Cabral JT, Mejía A, Shahruddin S, Matar OK, Müller EA. Determining interfacial tension and critical micelle concentrations of surfactants from atomistic molecular simulations. J Colloid Interface Sci 2024; 674:1071-1082. [PMID: 39013277 DOI: 10.1016/j.jcis.2024.07.002] [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: 04/19/2024] [Revised: 06/27/2024] [Accepted: 07/01/2024] [Indexed: 07/18/2024]
Abstract
Hypothesis Atomistically-detailed models of surfactants provide quantitative information on the molecular interactions and spatial distributions at fluid interfaces. Hence, it should be possible to extract from this information, macroscopical thermophysical properties such as interfacial tension, critical micelle concentrations and the relationship between these properties and the bulk fluid surfactant concentrations. Simulations and Experiments Molecular-scale interfacial of systems containing n-dodecyl β-glucoside (APG12) are simulated using classical molecular dynamics. The bulk phases and the corresponding interfacial regions are all explicitly detailed using an all-atom force field (PCFF+). During the simulation, the behaviour of the interface is analyzed geometrically to obtain an approximated value of the critical micelle concentration (CMC) in terms of the surfactant area number density and the interfacial tension is assessed through the analysis of the forces amongst molecules. New experimental determinations are reported for the surface tension of APG12 at the water/air and at the water/n-decane interfaces. Findings We showcase the application of a thermodynamic framework that inter-relates interfacial tensions, surface densities, CMCs and bulk surfactant concentrations, which allows the in silico quantitative prediction of interfacial tension isotherms.
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Affiliation(s)
- Harry Cárdenas
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - M Ariif H Kamrul-Bahrin
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Dale Seddon
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Jofry Othman
- Specialty Chemical Technology, PETRONAS Research Sdn Bhd, Malaysia
| | - João T Cabral
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Andrés Mejía
- Departamento de Ingenieria Quimica, Universidad de Concepcion, Concepcion, Chile
| | - Sara Shahruddin
- Specialty Chemical Technology, PETRONAS Research Sdn Bhd, Malaysia
| | - Omar K Matar
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom
| | - Erich A Müller
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, SW7 2AZ, United Kingdom.
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3
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Sawyer EM, Jensen LE, Meehl JB, Larsen KP, Petito DA, Hurley JH, Voeltz GK. SigmaR1 shapes rough endoplasmic reticulum membrane sheets. Dev Cell 2024:S1534-5807(24)00382-4. [PMID: 38971154 DOI: 10.1016/j.devcel.2024.06.005] [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: 09/25/2023] [Revised: 02/12/2024] [Accepted: 06/07/2024] [Indexed: 07/08/2024]
Abstract
Rough endoplasmic reticulum (ER) sheets are a fundamental domain of the ER and the gateway into the secretory pathway. Although reticulon proteins stabilize high-curvature ER tubules, it is unclear whether other proteins scaffold the flat membranes of rough ER sheets. Through a proteomics screen using ER sheet-localized RNA-binding proteins as bait, we identify the sigma-1 receptor (SigmaR1) as an ER sheet-shaping factor. High-resolution live cell imaging and electron tomography assign SigmaR1 as an ER sheet-localized factor whose levels determine the amount of rough ER sheets in cells. Structure-guided mutagenesis and in vitro reconstitution on giant unilamellar vesicles further support a mechanism whereby SigmaR1 oligomers use their extended arrays of amphipathic helices to bind and flatten the lumenal leaflet of ER membranes to oppose membrane curvature and stabilize rough ER sheets.
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Affiliation(s)
- Eric M Sawyer
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Howard Hughes Medical Institute
| | - Liv E Jensen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Janet B Meehl
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Howard Hughes Medical Institute
| | - Kevin P Larsen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Daniel A Petito
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Howard Hughes Medical Institute
| | - James H Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Gia K Voeltz
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309, USA; Howard Hughes Medical Institute.
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4
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Reagle T, Xie Y, Li Z, Carnero W, Baumgart T. Methyl-β-cyclodextrin asymmetrically extracts phospholipid from bilayers, granting tunable control over differential stress in lipid vesicles. SOFT MATTER 2024; 20:4291-4307. [PMID: 38758097 PMCID: PMC11135146 DOI: 10.1039/d3sm01772a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 05/01/2024] [Indexed: 05/18/2024]
Abstract
Lipid asymmetry - that is, a nonuniform lipid distribution between the leaflets of a bilayer - is a ubiquitous feature of biomembranes and is implicated in several cellular phenomena. Differential tension - that is, unequal lateral monolayer tensions comparing the leaflets of a bilayer- is closely associated with lipid asymmetry underlying these varied roles. Because differential tension is not directly measurable in combination with the fact that common methods to adjust this quantity grant only semi-quantitative control over it, a detailed understanding of lipid asymmetry and differential tension are impeded. To overcome these challenges, we leveraged reversible complexation of phospholipid by methyl-β-cyclodextrin (mbCD) to tune the direction and magnitude of lipid asymmetry in synthetic vesicles. Lipid asymmetry generated in our study induced (i) vesicle shape changes and (ii) gel-liquid phase coexistence in 1-component vesicles. By applying mass-action considerations to interpret our findings, we discuss how this approach provides access to phospholipid thermodynamic potentials in bilayers containing lipid asymmetry (which are coupled to the differential tension of a bilayer). Because lipid asymmetry yielded by our approach is (i) tunable and (ii) maintained over minute to hour timescales, we anticipate that this approach will be a valuable addition to the experimental toolbox for systematic investigation into the biophysical role(s) of lipid asymmetry (and differential tension).
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Affiliation(s)
- Tyler Reagle
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
| | - Yuxin Xie
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
| | - Zheyuan Li
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
| | - Warner Carnero
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
| | - Tobias Baumgart
- University of Pennsylvania, Chemistry Department, 231 South 34th Street, Philadelphia, PA, 19104, USA.
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5
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Argudo PG. Lipids and proteins: Insights into the dynamics of assembly, recognition, condensate formation. What is still missing? Biointerphases 2024; 19:038501. [PMID: 38922634 DOI: 10.1116/6.0003662] [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: 04/03/2024] [Accepted: 06/03/2024] [Indexed: 06/27/2024] Open
Abstract
Lipid membranes and proteins, which are part of us throughout our lives, have been studied for decades. However, every year, new discoveries show how little we know about them. In a reader-friendly manner for people not involved in the field, this paper tries to serve as a bridge between physicists and biologists and new young researchers diving into the field to show its relevance, pointing out just some of the plethora of lines of research yet to be unraveled. It illustrates how new ways, from experimental to theoretical approaches, are needed in order to understand the structures and interactions that take place in a single lipid, protein, or multicomponent system, as we are still only scratching the surface.
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Affiliation(s)
- Pablo G Argudo
- Max Planck Institute for Polymer Research (MPI-P), Mainz 55128, Germany
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6
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Peruzzi JA, Steinkühler J, Vu TQ, Gunnels TF, Hu VT, Lu P, Baker D, Kamat NP. Hydrophobic mismatch drives self-organization of designer proteins into synthetic membranes. Nat Commun 2024; 15:3162. [PMID: 38605024 PMCID: PMC11009411 DOI: 10.1038/s41467-024-47163-1] [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: 12/19/2022] [Accepted: 03/22/2024] [Indexed: 04/13/2024] Open
Abstract
The organization of membrane proteins between and within membrane-bound compartments is critical to cellular function. Yet we lack approaches to regulate this organization in a range of membrane-based materials, such as engineered cells, exosomes, and liposomes. Uncovering and leveraging biophysical drivers of membrane protein organization to design membrane systems could greatly enhance the functionality of these materials. Towards this goal, we use de novo protein design, molecular dynamic simulations, and cell-free systems to explore how membrane-protein hydrophobic mismatch could be used to tune protein cotranslational integration and organization in synthetic lipid membranes. We find that membranes must deform to accommodate membrane-protein hydrophobic mismatch, which reduces the expression and co-translational insertion of membrane proteins into synthetic membranes. We use this principle to sort proteins both between and within membranes, thereby achieving one-pot assembly of vesicles with distinct functions and controlled split-protein assembly, respectively. Our results shed light on protein organization in biological membranes and provide a framework to design self-organizing membrane-based materials with applications such as artificial cells, biosensors, and therapeutic nanoparticles.
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Affiliation(s)
- Justin A Peruzzi
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, IL, 60208, USA
- Center for Synthetic Biology, Northwestern University, Evanston, IL, 60208, USA
| | - Jan Steinkühler
- Center for Synthetic Biology, Northwestern University, Evanston, IL, 60208, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Timothy Q Vu
- Center for Synthetic Biology, Northwestern University, Evanston, IL, 60208, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Taylor F Gunnels
- Center for Synthetic Biology, Northwestern University, Evanston, IL, 60208, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Vivian T Hu
- Center for Synthetic Biology, Northwestern University, Evanston, IL, 60208, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA
| | - Peilong Lu
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- Institute of Biology, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA
- Institute for Protein Design, University of Washington, Seattle, WA, 98195, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, 98195, USA
| | - Neha P Kamat
- Center for Synthetic Biology, Northwestern University, Evanston, IL, 60208, USA.
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, 60208, USA.
- Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, 60208, USA.
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7
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Golla VK, Boyd KJ, May ER. Curvature sensing lipid dynamics in a mitochondrial inner membrane model. Commun Biol 2024; 7:29. [PMID: 38182788 PMCID: PMC10770132 DOI: 10.1038/s42003-023-05657-6] [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: 02/24/2023] [Accepted: 11/30/2023] [Indexed: 01/07/2024] Open
Abstract
Membrane curvature is essential for many cellular structures and processes, and factors such as leaflet asymmetry, lipid composition, and proteins all play important roles. Cardiolipin is the signature lipid of mitochondrial membranes and is essential for maintaining the highly curved shapes of the inner mitochondrial membrane (IMM) and the spatial arrangement of membrane proteins. In this study, we investigate the partitioning behavior of various lipids present in the IMM using coarse-grained molecular dynamics simulations. This study explores curved bilayer systems containing phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cardiolipin (CDL) in binary and ternary component mixtures. Curvature properties such as mean and Gaussian curvatures, as well as the distribution of lipids into the various curved regions of the cristae models, are quantified. Overall, this work represents an advance beyond previous studies on lipid curvature sensing by simulating these systems in a geometry that has the morphological features and scales of curvature consistent with regions of the IMM. We find that CDL has a stronger preference for accumulating in regions of negative curvature than PE lipids, in agreement with previous results. Furthermore, we find lipid partitioning propensity is dominated by sensitivity to mean curvature, while there is a weaker correlation with Gaussian curvature.
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Affiliation(s)
- Vinaya Kumar Golla
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, 06269, USA
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, VA, 22903, USA
| | - Kevin J Boyd
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, 06269, USA
- NVIDIA, 2860 County Hwy G4, Santa Clara, CA, 95051, USA
| | - Eric R May
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, 06269, USA.
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8
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Pöhnl M, Trollmann MFW, Böckmann RA. Nonuniversal impact of cholesterol on membranes mobility, curvature sensing and elasticity. Nat Commun 2023; 14:8038. [PMID: 38081812 PMCID: PMC10713574 DOI: 10.1038/s41467-023-43892-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2023] [Accepted: 11/22/2023] [Indexed: 12/18/2023] Open
Abstract
Biological membranes, composed mainly of phospholipids and cholesterol, play a vital role as cellular barriers. They undergo localized reshaping in response to environmental cues and protein interactions, with the energetics of deformations crucial for exerting biological functions. This study investigates the non-universal role of cholesterol on the structure and elasticity of saturated and unsaturated lipid membranes. Our study uncovers a highly cooperative relationship between thermal membrane bending and local cholesterol redistribution, with cholesterol showing a strong preference for the compressed membrane leaflet. Remarkably, in unsaturated membranes, increased cholesterol mobility enhances cooperativity, resulting in membrane softening despite membrane thickening and lipid compression caused by cholesterol. These findings elucidate the intricate interplay between thermodynamic forces and local molecular interactions that govern collective properties of membranes.
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Affiliation(s)
- Matthias Pöhnl
- Computational Biology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Marius F W Trollmann
- Computational Biology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- Erlangen National High Perfomance Computing Center (NHR@FAU), Erlangen, Germany
| | - Rainer A Böckmann
- Computational Biology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
- Erlangen National High Perfomance Computing Center (NHR@FAU), Erlangen, Germany.
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9
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Stankunas E, Köhler A. The interplay of nuclear pores and lipids. Curr Opin Cell Biol 2023; 85:102251. [PMID: 37804774 DOI: 10.1016/j.ceb.2023.102251] [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: 05/08/2023] [Revised: 08/24/2023] [Accepted: 09/07/2023] [Indexed: 10/09/2023]
Abstract
Nuclear pore complexes (NPCs) mediate the bidirectional transport of cargo across the nuclear envelope (NE). NPCs are also membrane remodeling machines with a capacity to curve and fuse the membranes of the NE. However, little is known about the interplay of NPCs and lipids at a mechanistic level. A full understanding of NPC structure and function needs to encompass how the NPC shapes membranes and is itself shaped by lipids. Here we attempt to connect recent findings in NPC research with the broader field of membrane biochemistry to illustrate how an interplay between NPCs and lipids may facilitate the conformational plasticity of NPCs and the generation of a unique pore membrane topology. We highlight the need to better understand the NPC's lipid environment and outline experimental avenues towards that goal.
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Affiliation(s)
- Edvinas Stankunas
- Max Perutz Labs, University of Vienna and Medical University of Vienna, Vienna Biocenter Campus (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria; Vienna BioCenter PhD Program, Doctoral School of the University of Vienna and Medical University of Vienna, A-1030 Vienna, Austria
| | - Alwin Köhler
- Max Perutz Labs, University of Vienna and Medical University of Vienna, Vienna Biocenter Campus (VBC), Dr. Bohr-Gasse 9/3, 1030 Vienna, Austria.
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10
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Phuyal S, Romani P, Dupont S, Farhan H. Mechanobiology of organelles: illuminating their roles in mechanosensing and mechanotransduction. Trends Cell Biol 2023; 33:1049-1061. [PMID: 37236902 DOI: 10.1016/j.tcb.2023.05.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/02/2023] [Accepted: 05/02/2023] [Indexed: 05/28/2023]
Abstract
Mechanobiology studies the mechanisms by which cells sense and respond to physical forces, and the role of these forces in shaping cells and tissues themselves. Mechanosensing can occur at the plasma membrane, which is directly exposed to external forces, but also in the cell's interior, for example, through deformation of the nucleus. Less is known on how the function and morphology of organelles are influenced by alterations in their own mechanical properties, or by external forces. Here, we discuss recent advances on the mechanosensing and mechanotransduction of organelles, including the endoplasmic reticulum (ER), the Golgi apparatus, the endo-lysosmal system, and the mitochondria. We highlight open questions that need to be addressed to gain a broader understanding of the role of organelle mechanobiology.
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Affiliation(s)
- Santosh Phuyal
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Patrizia Romani
- Department of Molecular Medicine, University of Padua, Padua, Italy
| | - Sirio Dupont
- Department of Molecular Medicine, University of Padua, Padua, Italy.
| | - Hesso Farhan
- Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; Institute of Pathophysiology, Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
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11
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Xu J, Karra V, Large DE, Auguste DT, Hung FR. Understanding the Mechanical Properties of Ultradeformable Liposomes Using Molecular Dynamics Simulations. J Phys Chem B 2023; 127:9496-9512. [PMID: 37879075 PMCID: PMC10641833 DOI: 10.1021/acs.jpcb.3c04386] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 09/19/2023] [Accepted: 10/04/2023] [Indexed: 10/27/2023]
Abstract
Improving drug delivery efficiency to solid tumor sites is a central challenge in anticancer therapeutic research. Our previous experimental study (Guo et al., Nat. Commun. 2018, 9, 130) showed that soft, elastic liposomes had increased uptake and accumulation in cancer cells and tumors in vitro and in vivo respectively, relative to rigid particles. As a first step toward understanding how liposomes' molecular structure and composition modulates their elasticity, we performed all-atom and coarse-grained classical molecular dynamics (MD) simulations of lipid bilayers formed by mixing a long-tailed unsaturated phospholipid with a short-tailed saturated lipid with the same headgroup. The former types of phospholipids considered were 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoleoyl-sn-glycero-3-phosphocholine (termed here DPMPC). The shorter saturated lipids examined were 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC), 1,2-didecanoyl-sn-glycero-3-phosphocholine (DDPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). Several lipid concentrations and surface tensions were considered. Our results show that DOPC or DPMPC systems having 25-35 mol % of the shortest lipids DHPC or DDPC are the least rigid, having area compressibility moduli KA that are ∼10% smaller than the values observed in pure DOPC or DPMPC bilayers. These results agree with experimental measurements of the stretching modulus and lysis tension in liposomes with the same compositions. These mixed systems also have lower areas per lipid and form more uneven x-y interfaces with water, the tails of both primary and secondary lipids are more disordered, and the terminal methyl groups in the tails of the long lipid DOPC or DPMPC wriggle more in the vertical direction, compared to pure DOPC or DPMPC bilayers or their mixtures with the longer saturated lipid DLPC or DMPC. These observations confirm our hypothesis that adding increasing concentrations of the short unsaturated lipid DHPC or DDPC to DOPC or DPMPC bilayers alters lipid packing and thus makes the resulting liposomes more elastic and less rigid. No formation of lipid nanodomains was noted in our simulations, and no clear trends were observed in the lateral diffusivities of the lipids as the concentration, type of secondary lipid, and surface tension were varied.
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Affiliation(s)
- Jiaming Xu
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Vyshnavi Karra
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Danielle E. Large
- Department
of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Debra T. Auguste
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
- Department
of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Francisco R. Hung
- Department
of Chemical Engineering, Northeastern University, Boston, Massachusetts 02115, United States
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12
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Karal MAS, Billah MM, Ahmed M, Ahamed MK. A review on the measurement of the bending rigidity of lipid membranes. SOFT MATTER 2023; 19:8285-8304. [PMID: 37873600 DOI: 10.1039/d3sm00882g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
This review provides an overview of the latest developments in both experimental and simulation techniques used to assess the bending rigidity of lipid membranes. It places special emphasis on experimental methods that utilize model vesicles to manipulate lipid compositions and other experimental parameters to determine the bending rigidity of the membrane. It also describes two commonly used simulation methods for estimating bending rigidity. The impact of various factors on membrane bending rigidity is summarized, including cholesterol, lipids, salt concentration, surface charge, membrane phase state, peptides, proteins, and polyethylene glycol. These factors are shown to influence the bending rigidity, contributing to a better understanding of the biophysical properties of membranes and their role in biological processes. Furthermore, the review discusses future directions and potential advancements in this research field, highlighting areas where further investigation is required.
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Affiliation(s)
- Mohammad Abu Sayem Karal
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000, Bangladesh.
| | - Md Masum Billah
- Department of Physics, Jashore University of Science and Technology, Jashore 7408, Bangladesh
| | - Marzuk Ahmed
- Integrated Bioscience Section, Graduate School of Science and Technology, Shizuoka University, Shizuoka 422-8529, Japan
| | - Md Kabir Ahamed
- Radiation, Transport and Waste Safety Division, Bangladesh Atomic Energy Regulatory Authority, Agargaon, Dhaka 1207, Bangladesh
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13
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Valdivieso González D, Makowski M, Lillo MP, Cao‐García FJ, Melo MN, Almendro‐Vedia VG, López‐Montero I. Rotation of the c-Ring Promotes the Curvature Sorting of Monomeric ATP Synthases. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301606. [PMID: 37705095 PMCID: PMC10625105 DOI: 10.1002/advs.202301606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 07/07/2023] [Indexed: 09/15/2023]
Abstract
ATP synthases are proteins that catalyse the formation of ATP through the rotatory movement of their membrane-spanning subunit. In mitochondria, ATP synthases are found to arrange as dimers at the high-curved edges of cristae. Here, a direct link is explored between the rotatory movement of ATP synthases and their preference for curved membranes. An active curvature sorting of ATP synthases in lipid nanotubes pulled from giant vesicles is found. Coarse-grained simulations confirm the curvature-seeking behaviour of rotating ATP synthases, promoting reversible and frequent protein-protein contacts. The formation of transient protein dimers relies on the membrane-mediated attractive interaction of the order of 1.5 kB T produced by a hydrophobic mismatch upon protein rotation. Transient dimers are sustained by a conic-like arrangement characterized by a wedge angle of θ ≈ 50°, producing a dynamic coupling between protein shape and membrane curvature. The results suggest a new role of the rotational movement of ATP synthases for their dynamic self-assembly in biological membranes.
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Affiliation(s)
- David Valdivieso González
- Departamento Química FísicaUniversidad Complutense de MadridAvda. Complutense s/nMadrid28040Spain
- Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12)Avenida de Córdoba s/nMadrid28041Spain
| | - Marcin Makowski
- Instituto de Medicina MolecularFacultade de MedicinaUniversidade de LisboaLisbon1649‐028Portugal
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da RepúblicaOeiras2780‐157Portugal
| | - M. Pilar Lillo
- Departamento Química Física BiológicaInstituto de Química‐Física “Blas Cabrera” (CSIC)Serrano 119Madrid28006Spain
| | - Francisco J. Cao‐García
- Departamento de Estructura de la MateriaFísica Térmica y ElectrónicaUniversidad Complutense de MadridPlaza de Ciencias 1Madrid28040Spain
- Instituto Madrileño de Estudios Avanzados en NanocienciaIMDEA NanocienciaC/ Faraday 9Madrid28049Spain
| | - Manuel N. Melo
- Instituto de Tecnologia Química e Biológica António XavierUniversidade Nova de LisboaAv. da RepúblicaOeiras2780‐157Portugal
| | - Víctor G. Almendro‐Vedia
- Departamento Química FísicaUniversidad Complutense de MadridAvda. Complutense s/nMadrid28040Spain
- Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12)Avenida de Córdoba s/nMadrid28041Spain
| | - Iván López‐Montero
- Departamento Química FísicaUniversidad Complutense de MadridAvda. Complutense s/nMadrid28040Spain
- Instituto de Investigación Biomédica Hospital Doce de Octubre (imas12)Avenida de Córdoba s/nMadrid28041Spain
- Instituto PluridisciplinarPaseo Juan XXIII 1Madrid28040Spain
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14
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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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15
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Träger J, Meister A, Hause G, Harauz G, Hinderberger D. Shaping membrane interfaces in lipid vesicles mimicking the cytoplasmic leaflet of myelin through variation of cholesterol and myelin basic protein contents. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184179. [PMID: 37244538 DOI: 10.1016/j.bbamem.2023.184179] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 04/23/2023] [Accepted: 05/20/2023] [Indexed: 05/29/2023]
Abstract
Myelin basic protein (MBP) is an intrinsically disordered protein and in the central nervous system (CNS) mainly responsible for connecting the cytoplasmic surfaces of the multilamellar, compact myelin. Increased posttranslational modification of MBP is linked to both, the natural development (from adolescent to adult brains) of myelin, and features of multiple sclerosis. Here, we study how a combination of this intrinsically disordered myelin protein with varying the natural cholesterol content may alter the characteristics of myelin-like membranes and interactions between these membranes. Large unilamellar vesicles (LUVs) with a composition mimicking the cytoplasmic leaflet of myelin were chosen as the model system, in which different parameters contributing to the interactions between the lipid membrane and MBP were investigated. While we use cryo-transmission electron microscopy (TEM) for imaging, dynamic light scattering (DLS) and electrophoretic measurements through continuously-monitored phase-analysis light scattering (cmPALS) were used for a more global overview of particle size and charge, and electron paramagnetic resonance (EPR) spectroscopy was utilized for local behavior of lipids in the vesicles' membranes in aqueous solution. The cholesterol content was varied from 060 % in these LUVs and measurements were performed in the presence and absence of MBP. We find that the composition of the lipid layers is relevant to the interaction with MBP. Not only the size, the shape and the aggregation behavior of the vesicles depend on the cholesterol content, but also within each membrane, cholesterol's freedom of movement, its environmental polarity and its distribution were found to depend on the content using the EPR-active spin-labeled cholesterol (CSOSL). In addition, DLS and EPR measurements probing the transition temperatures of the lipid phases allow a correlation of specific behavior with the human body temperature of 37 °C. Overall, our results aid in understanding the importance of the native cholesterol content in the healthy myelin membrane, which serves as the basis for stable and optimum protein-bilayer interactions. Although studied in this specific myelin-like system, from a more general and materials science-oriented point of view, we could establish how membrane and vesicle properties depend on cholesterol and/or MBP content, which might be useful generally when specific membrane and vesicle characteristics are sought for.
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Affiliation(s)
- Jennica Träger
- Institute of Chemistry, Physical Chemistry - Complex Self-organizing Systems, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Saxony-Anhalt, Germany; Interdisciplinary Research Center HALOmem at the Martin-Luther-Universität Halle-Wittenberg, Germany
| | - Annette Meister
- Interdisciplinary Research Center HALOmem at the Martin-Luther-Universität Halle-Wittenberg, Germany; Institute of Biochemistry, Physical Biotechnology, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany
| | - Gerd Hause
- Biocenter, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Germany
| | - George Harauz
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Dariush Hinderberger
- Institute of Chemistry, Physical Chemistry - Complex Self-organizing Systems, Martin-Luther-Universität Halle-Wittenberg, Halle (Saale), Saxony-Anhalt, Germany; Interdisciplinary Research Center HALOmem at the Martin-Luther-Universität Halle-Wittenberg, Germany.
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16
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Fiorin G, Forrest LR, Faraldo-Gómez JD. Membrane free-energy landscapes derived from atomistic dynamics explain nonuniversal cholesterol-induced stiffening. PNAS NEXUS 2023; 2:pgad269. [PMID: 37637198 PMCID: PMC10456217 DOI: 10.1093/pnasnexus/pgad269] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 07/31/2023] [Accepted: 08/03/2023] [Indexed: 08/29/2023]
Abstract
All lipid membranes have inherent morphological preferences and resist deformation. Yet adaptations in membrane shape can and do occur at multiple length scales. While this plasticity is crucial for cellular physiology, the factors controlling the morphological energetics of lipid bilayers and the dominant mechanisms of membrane remodeling remain to be fully understood. An ongoing debate regarding the universality of the stiffening effect of cholesterol underscores the challenges facing this field, both experimentally and theoretically, even for simple lipid mixtures. On the computational side, we have argued that enhanced-sampling all-atom molecular dynamics simulations are uniquely suited for the quantification of membrane conformational energetics, as they minimize a priori assumptions and permit analysis of bilayers in deformed states. To showcase this approach, we examine reported inconsistencies between alternative experimental measurements of bending moduli for cholesterol-enriched membranes. Specifically, we analyze lipid bilayers with different chain saturation and compute free-energy landscapes for curvature deformations distributed over areas from ∼5 to ∼60 nm2 . These enhanced simulations, totaling over 100 μs of sampling time, enable us to directly quantify both bending and tilt moduli and to dissect the contributing factors and molecular mechanisms of curvature generation at each length scale. Our results show that the effects of cholesterol on bending rigidity are lipid-specific and suggest that this specificity arises from differences in the torsional dynamics of the acyl chains. In summary, we demonstrate that quantitative relationships can now be established between lipid structure and bending energetics, paving the way for addressing open fundamental questions in cell membrane mechanics.
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Affiliation(s)
- Giacomo Fiorin
- National Institute for Neurological Disorders and Stroke, Bethesda, MD 20892, USA
- National Heart, Lung and Blood Institute, Bethesda, MD 20894, USA
| | - Lucy R Forrest
- National Institute for Neurological Disorders and Stroke, Bethesda, MD 20892, USA
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17
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Sapp K, Aleksanyan M, Kerr K, Dimova R, Sodt A. Kinetic relaxation of giant vesicles validates diffusional softening in a binary lipid mixture. Phys Rev E 2023; 107:054403. [PMID: 37329029 PMCID: PMC10548837 DOI: 10.1103/physreve.107.054403] [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: 10/12/2022] [Accepted: 03/15/2023] [Indexed: 06/18/2023]
Abstract
The stiffness of biological membranes determines the work required by cellular machinery to form and dismantle vesicles and other lipidic shapes. Model membrane stiffness can be determined from the equilibrium distribution of giant unilamellar vesicle surface undulations observable by phase contrast microscopy. With two or more components, lateral fluctuations of composition will couple to surface undulations depending on the curvature sensitivity of the constituent lipids. The result is a broader distribution of undulations whose complete relaxation is partially determined by lipid diffusion. In this work, kinetic analysis of the undulations of giant unilamellar vesicles made of phosphatidylcholine-phosphatidylethanolamine mixtures validates the molecular mechanism by which the membrane is made 25% softer than a single-component one. The mechanism is relevant to biological membranes, which have diverse and curvature-sensitive lipids.
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Affiliation(s)
- Kayla Sapp
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, 20892 Maryland, USA
| | - Mina Aleksanyan
- Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Kaitlyn Kerr
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, 20892 Maryland, USA
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - Alexander Sodt
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, 20892 Maryland, USA
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18
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Ebrahimkutty M, Duan J, Nüsse H, Klingauf J, Galic M. Negatively curved cellular membranes promote BAIAP2 signaling hub assembly. NANOSCALE 2023; 15:6759-6769. [PMID: 36943331 DOI: 10.1039/d2nr05719k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Plasma membrane deformations are associated with curvature-dependent protein enrichment that contributes to a wide array of cellular functions. While the spatio-temporal protein dynamics at membrane indentations is well characterized, relatively little is known about protein kinetics at outwardly deforming membrane sites. This is in part due to the lack of high throughput approaches to systematically probe the curvature-dependence of protein-membrane interactions. Here, we developed a nanopatterned array for multiplexed analysis of protein dynamics at negatively curved cellular membranes. Taking advantage of this robust and versatile platform, we explored how membrane shape influences the prototypic negative curvature sensing protein BAIAP2 and its effector proteins. We find assembly of multi-protein signaling hubs and increased actin polymerization at outwardly deformed membrane sections, indicative of curvature-dependent BAIAP2 activation. Collectively, this study presents technical and conceptual advancements towards a quantitative understanding of spatio-temporal protein dynamics at negatively curved membranes.
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Affiliation(s)
- Mirsana Ebrahimkutty
- Institute of Medical Physics and Biophysics, University of Muenster, Germany.
- 'Cells in Motion' Interfaculty Centre, University of Muenster, Germany
- CIM-IMPRS Graduate School, Muenster, Germany
| | - Junxiu Duan
- Institute of Medical Physics and Biophysics, University of Muenster, Germany.
- 'Cells in Motion' Interfaculty Centre, University of Muenster, Germany
- CIM-IMPRS Graduate School, Muenster, Germany
| | - Harald Nüsse
- Institute of Medical Physics and Biophysics, University of Muenster, Germany.
| | - Jürgen Klingauf
- Institute of Medical Physics and Biophysics, University of Muenster, Germany.
- 'Cells in Motion' Interfaculty Centre, University of Muenster, Germany
| | - Milos Galic
- Institute of Medical Physics and Biophysics, University of Muenster, Germany.
- 'Cells in Motion' Interfaculty Centre, University of Muenster, Germany
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19
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Tapie P, Prevost AM, Montel L, Pontani LL, Wandersman E. A simple method to make, trap and deform a vesicle in a gel. Sci Rep 2023; 13:5375. [PMID: 37009808 PMCID: PMC10068607 DOI: 10.1038/s41598-023-31996-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 03/21/2023] [Indexed: 04/04/2023] Open
Abstract
We present a simple method to produce giant lipid pseudo-vesicles (vesicles with an oily cap on the top), trapped in an agarose gel. The method can be implemented using only a regular micropipette and relies on the formation of a water/oil/water double droplet in liquid agarose. We characterize the produced vesicle with fluorescence imaging and establish the presence and integrity of the lipid bilayer by the successful insertion of [Formula: see text]-Hemolysin transmembrane proteins. Finally, we show that the vesicle can be easily mechanically deformed, non-intrusively, by indenting the surface of the gel.
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Affiliation(s)
- Pierre Tapie
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), 4 place Jussieu, 75005, Paris, France
| | - Alexis M Prevost
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), 4 place Jussieu, 75005, Paris, France
| | - Lorraine Montel
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), 4 place Jussieu, 75005, Paris, France
| | - Léa-Laetitia Pontani
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), 4 place Jussieu, 75005, Paris, France.
| | - Elie Wandersman
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire Jean Perrin (LJP), 4 place Jussieu, 75005, Paris, France.
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20
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van Hilten N, Methorst J, Verwei N, Risselada HJ. Physics-based generative model of curvature sensing peptides; distinguishing sensors from binders. SCIENCE ADVANCES 2023; 9:eade8839. [PMID: 36930719 PMCID: PMC10022891 DOI: 10.1126/sciadv.ade8839] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 02/09/2023] [Indexed: 06/18/2023]
Abstract
Proteins can specifically bind to curved membranes through curvature-induced hydrophobic lipid packing defects. The chemical diversity among such curvature "sensors" challenges our understanding of how they differ from general membrane "binders" that bind without curvature selectivity. Here, we combine an evolutionary algorithm with coarse-grained molecular dynamics simulations (Evo-MD) to resolve the peptide sequences that optimally recognize the curvature of lipid membranes. We subsequently demonstrate how a synergy between Evo-MD and a neural network (NN) can enhance the identification and discovery of curvature sensing peptides and proteins. To this aim, we benchmark a physics-trained NN model against experimental data and show that we can correctly identify known sensors and binders. We illustrate that sensing and binding are phenomena that lie on the same thermodynamic continuum, with only subtle but explainable differences in membrane binding free energy, consistent with the serendipitous discovery of sensors.
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Affiliation(s)
- Niek van Hilten
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden, 2333 CC, Netherlands
| | - Jeroen Methorst
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden, 2333 CC, Netherlands
| | - Nino Verwei
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden, 2333 CC, Netherlands
| | - Herre Jelger Risselada
- Leiden Institute of Chemistry, Leiden University, Einsteinweg 55, Leiden, 2333 CC, Netherlands
- Department of Physics, Technical University Dortmund, Otto-Hahn-Strasse 4, Dortmund, 44227, Germany
- Institute of Theoretical Physics, Georg-August-University Göttingen, Friedrich-Hund-Platz 1, Göttingen, 37077, Germany
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21
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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: 11] [Impact Index Per Article: 11.0] [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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22
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Tetraspanin 4 stabilizes membrane swellings and facilitates their maturation into migrasomes. Nat Commun 2023; 14:1037. [PMID: 36823145 PMCID: PMC9950420 DOI: 10.1038/s41467-023-36596-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Accepted: 02/06/2023] [Indexed: 02/25/2023] Open
Abstract
Migrasomes are newly discovered cell organelles forming by local swelling of retraction fibers. The migrasome formation critically depends on tetraspanin proteins present in the retraction fiber membranes and is modulated by the membrane tension and bending rigidity. It remained unknown how and in which time sequence these factors are involved in migrasome nucleation, growth, and stabilization, and what are the possible intermediate stages of migrasome biogenesis. Here using live cell imaging and a biomimetic system for migrasomes and retraction fibers, we reveal that migrasome formation is a two-stage process. At the first stage, which in biomimetic system is mediated by membrane tension, local swellings largely devoid of tetraspanin 4 form on the retraction fibers. At the second stage, tetraspanin 4 molecules migrate toward and onto these swellings, which grow up to several microns in size and transform into migrasomes. This tetraspanin 4 recruitment to the swellings is essential for migrasome growth and stabilization. Based on these findings we propose that the major role of tetraspanin proteins is in stabilizing the migrasome structure, while the migrasome nucleation and initial growth stages can be driven by membrane mechanical stresses.
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23
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Fiorin G, Forrest LR, Faraldo-Gómez JD. Membrane free-energy landscapes derived from atomistic dynamics explain nonuniversal cholesterol-induced stiffening. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.525347. [PMID: 36778237 PMCID: PMC9915699 DOI: 10.1101/2023.02.02.525347] [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
All lipid membranes have inherent morphological preferences and resist deformation. Yet adaptations in membrane shape can and do occur at multiple length scales. While this plasticity is crucial for cellular physiology, the factors controlling the morphological energetics of lipid bilayers and the dominant mechanisms of membrane remodeling remain unclear. An ongoing debate regarding the universality of the stiffening effect of cholesterol underscores the challenges facing this field, both experimentally and theoretically, even for simple lipid mixtures. On the computational side, we have argued that enhanced- sampling all-atom molecular dynamics simulations are uniquely suited for quantification of membrane conformational energetics, not only because they minimize a-priori assumptions, but also because they permit analysis of bilayers in deformed states. To showcase this approach, we examine reported inconsistencies between alternative experimental measurements of bending moduli for cholesterol-enriched membranes. Specifically, we analyze lipid bilayers with different chain saturation, and compute free-energy landscapes for curvature deformations distributed over areas from ∼5 to ∼60 nm 2 . These enhanced simulations, totaling over 100 microseconds of sampling time, enable us to directly quantify both bending and tilt moduli, and to dissect the contributing factors and molecular mechanisms of curvature generation at each length scale. Our results show that cholesterol effects are lipid-specific, in agreement with giantvesicle measurements, and explain why experiments probing nanometer scale lipid dynamics diverge. In summary, we demonstrate that quantitative structure-mechanics relationships can now be established for heterogenous membranes, paving the way for addressing open fundamental questions in cell membrane mechanics. Significance Elucidating the energetics and mechanisms of membrane remodeling is an essential step towards understanding cell physiology. This problem is challenging, however, because membrane bending involves both large-scale and atomic-level dynamics, which are difficult to measure simultaneously. A recent controversy regarding the stiffening effect of cholesterol, which is ubiquitous in animal cells, illustrates this challenge. We show how enhanced molecular-dynamics simulations can bridge this length-scale gap and reconcile seemingly incongruent observations. This approach facilitates a conceptual connection between lipid chemistry and membrane mechanics, thereby providing a solid basis for future research on remodeling phenomena, such as in membrane trafficking or viral infection.
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Affiliation(s)
- Giacomo Fiorin
- National Institute for Neurological Disorders and Stroke, Bethesda, MD, USA
- National Heart, Lung and Blood Institute, Bethesda, MD, USA
| | - Lucy R Forrest
- National Institute for Neurological Disorders and Stroke, Bethesda, MD, USA
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24
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Saha T, Heuer A, Galic M. Systematic analysis of curvature-dependent lipid dynamics in a stochastic 3D membrane model. SOFT MATTER 2023; 19:1330-1341. [PMID: 36692259 DOI: 10.1039/d2sm01260j] [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
To minimize the free energy of the system, lipid membranes display curvature-dependent rearrangements at the local and global scale. The optimal membrane shape is generally approximated by averaging the curvature preference of individual lipids across the whole surface. Potential stress due to imperfections in lipid packing caused by local lipid inhomogeneities, however, is frequently neglected. Here, we developed a stochastic 3D membrane model to investigate the relevance of this parameter for shape-dependent lipid and membrane dynamics. A systematic analysis of the discretized Helfrich type Hamiltonian indicates that stress-energy arising from imperfections in packing is analogous to van der Waals interactions, jointly determining membrane shape and localization of curvature-sensitive lipids based on their relative strengths. Insights from this work can be used to characterize natural and design synthetic agents for membrane-shape changes.
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Affiliation(s)
- Tanumoy Saha
- Institute of Medical Physics and Biophysics, University of Muenster, Germany.
- Cells in Motion' Interfaculty Centre, University of Muenster, Germany.
- CIM-IMPRS Graduate School, Muenster, Germany
| | - Andreas Heuer
- Cells in Motion' Interfaculty Centre, University of Muenster, Germany.
- Institute of Physical Chemistry, University of Muenster, Germany
| | - Milos Galic
- Institute of Medical Physics and Biophysics, University of Muenster, Germany.
- Cells in Motion' Interfaculty Centre, University of Muenster, Germany.
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25
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Moss FR, Lincoff J, Tucker M, Mohammed A, Grabe M, Frost A. Brominated lipid probes expose structural asymmetries in constricted membranes. Nat Struct Mol Biol 2023; 30:167-175. [PMID: 36624348 PMCID: PMC9935397 DOI: 10.1038/s41594-022-00898-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 11/11/2022] [Indexed: 01/11/2023]
Abstract
Lipids in biological membranes are thought to be functionally organized, but few experimental tools can probe nanoscale membrane structure. Using brominated lipids as contrast probes for cryo-EM and a model ESCRT-III membrane-remodeling system composed of human CHMP1B and IST1, we observed leaflet-level and protein-localized structural lipid patterns within highly constricted and thinned membrane nanotubes. These nanotubes differed markedly from protein-free, flat bilayers in leaflet thickness, lipid diffusion rates and lipid compositional and conformational asymmetries. Simulations and cryo-EM imaging of brominated stearoyl-docosahexanenoyl-phosphocholine showed how a pair of phenylalanine residues scored the outer leaflet with a helical hydrophobic defect where polyunsaturated docosahexaenoyl tails accumulated at the bilayer surface. Combining cryo-EM of halogenated lipids with molecular dynamics thus enables new characterizations of the composition and structure of membranes on molecular length scales.
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Affiliation(s)
- Frank R Moss
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- SLAC National Accelerator Laboratory, Menlo Park, CA, USA
- Altos Labs, Redwood City, CA, USA
| | - James Lincoff
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - Maxwell Tucker
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA
- Cardiovascular Research Institute, University of California San Francisco (UCSF), San Francisco, CA, USA
| | - Arshad Mohammed
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA
- University of California Berkeley, Berkeley, CA, USA
- Altos Labs, Redwood City, CA, USA
| | - Michael Grabe
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, USA.
- Cardiovascular Research Institute, University of California San Francisco (UCSF), San Francisco, CA, USA.
| | - Adam Frost
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
- Department of Biochemistry, University of Utah, Salt Lake City, UT, USA.
- Altos Labs, Redwood City, CA, USA.
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26
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Kalutskii MA, Galimzyanov TR, Pinigin KV. Determination of elastic parameters of lipid membranes from simulation under varied external pressure. Phys Rev E 2023; 107:024414. [PMID: 36932616 DOI: 10.1103/physreve.107.024414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
Many cellular processes such as endocytosis, exocytosis, and vesicle trafficking involve membrane deformations, which can be analyzed in the framework of the elastic theories of lipid membranes. These models operate with phenomenological elastic parameters. A connection between these parameters and the internal structure of lipid membranes can be provided by three-dimensional (3D) elastic theories. Considering a membrane as a 3D layer, Campelo et al. [F. Campelo et al., Adv. Colloid Interface Sci. 208, 25 (2014)10.1016/j.cis.2014.01.018] developed a theoretical basis for the calculation of elastic parameters. In this work we generalize and improve this approach by considering a more general condition of global incompressibility instead of local incompressibility. Crucially, we find an important correction to the theory of Campelo et al., which if not taken into account leads to a significant miscalculation of elastic parameters. With the total volume conservation taken into account, we derive an expression for the local Poisson's ratio, which determines how the local volume changes upon stretching and permits a more precise determination of elastic parameters. Also, we substantially simplify the procedure by calculating the derivatives of the moments of the local tension with respect to stretching instead of calculating the local stretching modulus. We obtain a relation between the Gaussian curvature modulus as a function of stretching and the bending modulus, showing that these two elastic parameters are not independent, as was previously assumed. The proposed algorithm is applied to membranes composed of pure dipalmitoylphosphatidylcholine (DPPC), dioleoylphosphatidylcholine (DOPC), and their mixture. The following elastic parameters of these systems are obtained: the monolayer bending and stretching moduli, spontaneous curvature, neutral surface position, and local Poisson's ratio. It is shown that the bending modulus of the DPPC/DOPC mixture follows a more complex trend than predicted by the classical Reuss averaging, which is often employed in theoretical frameworks.
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Affiliation(s)
- Maksim A Kalutskii
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, Moscow 119071, Russia
- 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, 31/4 Leninskiy Prospekt, Moscow 119071, Russia
- Department of Theoretical Physics and Quantum Technologies, National University of Science and Technology "MISiS," 4 Leninskiy Prospekt, 119049 Moscow, Russia
| | - Konstantin V Pinigin
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, Moscow 119071, Russia
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Close, but not too close: a mesoscopic description of (a)symmetry and membrane shaping mechanisms. Emerg Top Life Sci 2023; 7:81-93. [PMID: 36645200 DOI: 10.1042/etls20220078] [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: 10/28/2022] [Revised: 12/13/2022] [Accepted: 12/22/2022] [Indexed: 01/17/2023]
Abstract
Biomembranes are fundamental to our understanding of the cell, the basic building block of all life. An intriguing aspect of membranes is their ability to assume a variety of shapes, which is crucial for cell function. Here, we review various membrane shaping mechanisms with special focus on the current understanding of how local curvature and local rigidity induced by membrane proteins leads to emerging forces and consequently large-scale membrane deformations. We also argue that describing the interaction of rigid proteins with membranes purely in terms of local membrane curvature is incomplete and that changes in the membrane rigidity moduli must also be considered.
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28
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Li L, Ji J, Song F, Hu J. Intercellular Receptor-ligand Binding: Effect of Protein-membrane Interaction. J Mol Biol 2023; 435:167787. [PMID: 35952805 DOI: 10.1016/j.jmb.2022.167787] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/03/2022] [Accepted: 08/04/2022] [Indexed: 02/04/2023]
Abstract
Gaining insights into the intercellular receptor-ligand binding is of great importance for understanding numerous physiological and pathological processes, and stimulating new strategies in drug design and discovery. In contrast to the in vitro protein interaction in solution, the anchored receptor and ligand molecules interact with membrane in situ, which affects the intercellular receptor-ligand binding. Here, we review theoretical, simulation and experimental works regarding the regulatory effects of protein-membrane interactions on intercellular receptor-ligand binding mainly from the following aspects: membrane fluctuations, membrane curvature, glycocalyx, and lipid raft. In addition, we discuss biomedical significances and possible research directions to advance the field and highlight the importance of understanding of coupling effects of these factors in pharmaceutical development.
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Affiliation(s)
- Long Li
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, 210023 Nanjing, China; State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, 100190 Beijing, China
| | - Jing Ji
- Key Laboratory of Biomechanics and Mechanobiology (Beihang University), Ministry of Education Beijing Advanced Innovation Center for Biomedical Engineering School of Biological Science and Medical Engineering, Beihang University, Beijing 100083, China.
| | - Fan Song
- State Key Laboratory of Nonlinear Mechanics and Beijing Key Laboratory of Engineered Construction and Mechanobiology, Institute of Mechanics, Chinese Academy of Sciences, 100190 Beijing, China; School of Engineering Science, University of Chinese Academy of Sciences, 100049 Beijing, China
| | - Jinglei Hu
- Kuang Yaming Honors School and Institute for Brain Sciences, Nanjing University, 210023 Nanjing, China.
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29
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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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30
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Rosenhouse-Dantsker A, Gazgalis D, Logothetis DE. PI(4,5)P 2 and Cholesterol: Synthesis, Regulation, and Functions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1422:3-59. [PMID: 36988876 DOI: 10.1007/978-3-031-21547-6_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) is the most abundant membrane phosphoinositide and cholesterol is an essential component of the plasma membrane (PM). Both lipids play key roles in a variety of cellular functions including as signaling molecules and major regulators of protein function. This chapter provides an overview of these two important lipids. Starting from a brief description of their structure, synthesis, and regulation, the chapter continues to describe the primary functions and signaling processes in which PI(4,5)P2 and cholesterol are involved. While PI(4,5)P2 and cholesterol can act independently, they often act in concert or affect each other's impact. The chapters in this volume on "Cholesterol and PI(4,5)P2 in Vital Biological Functions: From Coexistence to Crosstalk" focus on the emerging relationship between cholesterol and PI(4,5)P2 in a variety of biological systems and processes. In this chapter, the next section provides examples from the ion channel field demonstrating that PI(4,5)P2 and cholesterol can act via common mechanisms. The chapter ends with a discussion of future directions.
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Affiliation(s)
| | - Dimitris Gazgalis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
| | - Diomedes E Logothetis
- Department of Pharmaceutical Sciences, School of Pharmacy and Pharmaceutical Sciences, Bouvé College of Health Sciences, Northeastern University, Boston, MA, USA
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31
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Park H, Sut TN, Yoon BK, Zhdanov VP, Cho NJ, Jackman JA. Unraveling How Cholesterol Affects Multivalency-Induced Membrane Deformation of Sub-100 nm Lipid Vesicles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:15950-15959. [PMID: 36515977 DOI: 10.1021/acs.langmuir.2c02252] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Cholesterol plays a critical role in modulating the lipid membrane properties of biological and biomimetic systems and recent attention has focused on its role in the functions of sub-100 nm lipid vesicles and lipid nanoparticles. These functions often rely on multivalent ligand-receptor interactions involving membrane attachment and dynamic shape transformations while the extent to which cholesterol can influence such interaction processes is largely unknown. To address this question, herein, we investigated the attachment of sub-100 nm lipid vesicles containing varying cholesterol fractions (0-45 mol %) to membrane-mimicking supported lipid bilayer (SLB) platforms. Biotinylated lipids and streptavidin proteins were used as model ligands and receptors, respectively, while the localized surface plasmon resonance sensing technique was employed to track vesicle attachment kinetics in combination with analytical modeling of vesicle shape changes. Across various conditions mimicking low and high multivalency, our findings revealed that cholesterol-containing vesicles could bind to receptor-functionalized membranes but underwent appreciably less multivalency-induced shape deformation than vesicles without cholesterol, which can be explained by a cholesterol-mediated increase in membrane bending rigidity. Interestingly, the extent of vesicle deformation that occurred in response to increasingly strong multivalent interactions was less pronounced for vesicles with greater cholesterol fraction. The latter trend was rationalized by taking into account the strong dependence of the membrane bending energy on the area of the vesicle-SLB contact region and such insights can aid the engineering of membrane-enveloped nanoparticles with tailored biophysical properties.
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Affiliation(s)
- Hyeonjin Park
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore
| | | | - Bo Kyeong Yoon
- School of Healthcare and Biomedical Engineering, Chonnam National University, Yeosu 59626, Republic of Korea
| | - Vladimir P Zhdanov
- Division of Nano and Biophysics, Department of Physics, Chalmers University of Technology, Gothenburg 41296, Sweden
- Boreskov Institute of Catalysis, Russian Academy of Sciences, Novosibirsk 630090, Russia
| | - Nam-Joon Cho
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Drive, Singapore 637553, Singapore
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32
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Wubshet NH, Liu AP. Methods to mechanically perturb and characterize GUV-based minimal cell models. Comput Struct Biotechnol J 2022; 21:550-562. [PMID: 36659916 PMCID: PMC9816913 DOI: 10.1016/j.csbj.2022.12.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 12/15/2022] [Accepted: 12/15/2022] [Indexed: 12/23/2022] Open
Abstract
Cells shield organelles and the cytosol via an active boundary predominantly made of phospholipids and membrane proteins, yet allowing communication between the intracellular and extracellular environment. Micron-sized liposome compartments commonly known as giant unilamellar vesicles (GUVs) are used to model the cell membrane and encapsulate biological materials and processes in a cell-like confinement. In the field of bottom-up synthetic biology, many have utilized GUVs as substrates to study various biological processes such as protein-lipid interactions, cytoskeletal assembly, and dynamics of protein synthesis. Like cells, it is ideal that GUVs are also mechanically durable and able to stay intact when the inner and outer environment changes. As a result, studies have demonstrated approaches to tune the mechanical properties of GUVs by modulating membrane composition and lumenal material property. In this context, there have been many different methods developed to test the mechanical properties of GUVs. In this review, we will survey various perturbation techniques employed to mechanically characterize GUVs.
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Affiliation(s)
- Nadab H. Wubshet
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
| | - Allen P. Liu
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109, USA
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
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33
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Jensen LE, Rao S, Schuschnig M, Cada AK, Martens S, Hummer G, Hurley JH. Membrane curvature sensing and stabilization by the autophagic LC3 lipidation machinery. SCIENCE ADVANCES 2022; 8:eadd1436. [PMID: 36516251 PMCID: PMC9750143 DOI: 10.1126/sciadv.add1436] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 11/10/2022] [Indexed: 05/28/2023]
Abstract
How the highly curved phagophore membrane is stabilized during autophagy initiation is a major open question in autophagosome biogenesis. Here, we use in vitro reconstitution on membrane nanotubes and molecular dynamics simulations to investigate how core autophagy proteins in the LC3 (Microtubule-associated proteins 1A/1B light chain 3) lipidation cascade interact with curved membranes, providing insight into their possible roles in regulating membrane shape during autophagosome biogenesis. ATG12(Autophagy-related 12)-ATG5-ATG16L1 was up to 100-fold enriched on highly curved nanotubes relative to flat membranes. At high surface density, ATG12-ATG5-ATG16L1 binding increased the curvature of the nanotubes. While WIPI2 (WD repeat domain phosphoinositide-interacting protein 2) binding directs membrane recruitment, the amphipathic helix α2 of ATG16L1 is responsible for curvature sensitivity. Molecular dynamics simulations revealed that helix α2 of ATG16L1 inserts shallowly into the membrane, explaining its curvature-sensitive binding to the membrane. These observations show how the binding of the ATG12-ATG5-ATG16L1 complex to the early phagophore rim could stabilize membrane curvature and facilitate autophagosome growth.
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Affiliation(s)
- Liv E. Jensen
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
| | - Shanlin Rao
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Martina Schuschnig
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Vienna, Austria
| | - A. King Cada
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
| | - Sascha Martens
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Department of Biochemistry and Cell Biology, Max Perutz Labs, University of Vienna, Vienna BioCenter, Vienna, Austria
| | - Gerhard Hummer
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
- Institute of Biophysics, Goethe University Frankfurt, Frankfurt am Main 60438, Germany
| | - James H. Hurley
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
- Aligning Science Across Parkinson’s (ASAP) Collaborative Research Network, Chevy Chase, MD 20815, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
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34
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Cheppali SK, Dharan R, Sorkin R. Forces of Change: Optical Tweezers in Membrane Remodeling Studies. J Membr Biol 2022; 255:677-690. [PMID: 35616705 DOI: 10.1007/s00232-022-00241-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 04/22/2022] [Indexed: 12/24/2022]
Abstract
Optical tweezers allow precise measurement of forces and distances with piconewton and nanometer precision, and have thus been instrumental in elucidating the mechanistic details of various biological processes. Some examples include the characterization of motor protein activity, studies of protein-DNA interactions, and characterizing protein folding trajectories. The use of optical tweezers (OT) to study membranes is, however, much less abundant. Here, we review biophysical studies of membranes that utilize optical tweezers, with emphasis on various assays that have been developed and their benefits and limitations. First, we discuss assays that employ membrane-coated beads, and overview protein-membrane interactions studies based on manipulation of such beads. We further overview a body of studies that make use of a very powerful experimental tool, the combination of OT, micropipette aspiration, and fluorescence microscopy, that allow detailed studies of membrane curvature generation and sensitivity. Finally, we describe studies focused on membrane fusion and fission. We then summarize the overall progress in the field and outline future directions.
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Affiliation(s)
- Sudheer K Cheppali
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel.,Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, Israel.,Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel.,Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv, Israel
| | - Raviv Dharan
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel.,Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, Israel.,Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel.,Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv, Israel
| | - Raya Sorkin
- Raymond and Beverly Sackler Faculty of Exact Sciences, School of Chemistry, Tel Aviv University, Tel Aviv, Israel. .,Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, Israel. .,Center for Nanoscience and Nanotechnology, Tel Aviv University, Tel Aviv, Israel. .,Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv, Israel.
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35
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Molugu TR, Thurmond RL, Alam TM, Trouard TP, Brown MF. Phospholipid headgroups govern area per lipid and emergent elastic properties of bilayers. Biophys J 2022; 121:4205-4220. [PMID: 36088534 PMCID: PMC9674990 DOI: 10.1016/j.bpj.2022.09.005] [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: 03/15/2022] [Revised: 08/10/2022] [Accepted: 09/06/2022] [Indexed: 11/24/2022] Open
Abstract
Phospholipid bilayers are liquid-crystalline materials whose intermolecular interactions at mesoscopic length scales have key roles in the emergence of membrane physical properties. Here we investigated the combined effects of phospholipid polar headgroups and acyl chains on biophysical functions of membranes with solid-state 2H NMR spectroscopy. We compared the structural and dynamic properties of phosphatidylethanolamine and phosphatidylcholine with perdeuterated acyl chains in the solid-ordered (so) and liquid-disordered (ld) phases. Our analysis of spectral lineshapes of 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE-d62) and 1,2-diperdeuteriopalmitoyl-sn-glycero-3-phosphocholine (DPPC-d62) in the so (gel) phase indicated an all-trans rotating chain structure for both lipids. Greater segmental order parameters (SCD) were observed in the ld (liquid-crystalline) phase for DPPE-d62 than for DPPC-d62 membranes, while their mixtures had intermediate values irrespective of the deuterated lipid type. Our results suggest the SCD profiles of the acyl chains are governed by methylation of the headgroups and are averaged over the entire system. Variations in the acyl chain molecular dynamics were further investigated by spin-lattice (R1Z) and quadrupolar-order relaxation (R1Q) measurements. The two acyl-perdeuterated lipids showed distinct differences in relaxation behavior as a function of the order parameter. The R1Z rates had a square-law dependence on SCD, implying collective mesoscopic dynamics, with a higher bending rigidity for DPPE-d62 than for DPPC-d62 lipids. Remodeling of lipid average and dynamic properties by methylation of the headgroups thus provides a mechanism to control the actions of peptides and proteins in biomembranes.
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Affiliation(s)
- Trivikram R Molugu
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona
| | | | - Todd M Alam
- Department of Organic Materials Science, Sandia National Laboratories, Albuquerque, New Mexico
| | - Theodore P Trouard
- Department of Biomedical Engineering, University of Arizona, Tucson, Arizona
| | - Michael F Brown
- Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona; Department of Physics, University of Arizona, Tucson, Arizona.
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36
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Aleksanyan M, Faizi HA, Kirmpaki MA, Vlahovska PM, Riske KA, Dimova R. Assessing membrane material properties from the response of giant unilamellar vesicles to electric fields. ADVANCES IN PHYSICS: X 2022; 8:2125342. [PMID: 36211231 PMCID: PMC9536468 DOI: 10.1080/23746149.2022.2125342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 09/12/2022] [Indexed: 06/16/2023] Open
Abstract
Knowledge of the material properties of membranes is crucial to understanding cell viability and physiology. A number of methods have been developed to probe membranes in vitro, utilizing the response of minimal biomimetic membrane models to an external perturbation. In this review, we focus on techniques employing giant unilamellar vesicles (GUVs), model membrane systems, often referred to as minimal artificial cells because of the potential they offer to mimick certain cellular features. When exposed to electric fields, GUV deformation, dynamic response and poration can be used to deduce properties such as bending rigidity, pore edge tension, membrane capacitance, surface shear viscosity, excess area and membrane stability. We present a succinct overview of these techniques, which require only simple instrumentation, available in many labs, as well as reasonably facile experimental implementation and analysis.
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Affiliation(s)
- Mina Aleksanyan
- Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
- Institute for Chemistry and Biochemistry, Free University of Berlin, 14195 Berlin, Germany
| | - Hammad A Faizi
- Department of Mechanical Engineering, Northwestern University, Evanston, IL, USA
| | - Maria-Anna Kirmpaki
- Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
| | - Petia M Vlahovska
- Engineering Sciences and Applied Mathematics, Northwestern University, Evanston, IL, USA
| | - Karin A Riske
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, 04039-032 Brazil
| | - Rumiana Dimova
- Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, 14476 Potsdam, Germany
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37
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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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38
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Cada AK, Pavlin MR, Castillo JP, Tong AB, Larsen KP, Ren X, Yokom AL, Tsai FC, Shiah JV, Bassereau PM, Bustamante CJ, Hurley JH. Friction-driven membrane scission by the human ESCRT-III proteins CHMP1B and IST1. Proc Natl Acad Sci U S A 2022; 119:e2204536119. [PMID: 35858336 PMCID: PMC9303997 DOI: 10.1073/pnas.2204536119] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Accepted: 05/31/2022] [Indexed: 12/15/2022] Open
Abstract
The endosomal sorting complexes required for transport (ESCRT) system is an ancient and ubiquitous membrane scission machinery that catalyzes the budding and scission of membranes. ESCRT-mediated scission events, exemplified by those involved in the budding of HIV-1, are usually directed away from the cytosol ("reverse topology"), but they can also be directed toward the cytosol ("normal topology"). The ESCRT-III subunits CHMP1B and IST1 can coat and constrict positively curved membrane tubes, suggesting that these subunits could catalyze normal topology membrane severing. CHMP1B and IST1 bind and recruit the microtubule-severing AAA+ ATPase spastin, a close relative of VPS4, suggesting that spastin could have a VPS4-like role in normal-topology membrane scission. Here, we reconstituted the process in vitro using membrane nanotubes pulled from giant unilamellar vesicles using an optical trap in order to determine whether CHMP1B and IST1 are capable of membrane severing on their own or in concert with VPS4 or spastin. CHMP1B and IST1 copolymerize on membrane nanotubes, forming stable scaffolds that constrict the tubes, but do not, on their own, lead to scission. However, CHMP1B-IST1 scaffolded tubes were severed when an additional extensional force was applied, consistent with a friction-driven scission mechanism. We found that spastin colocalized with CHMP1B-enriched sites but did not disassemble the CHMP1B-IST1 coat from the membrane. VPS4 resolubilized CHMP1B and IST1 without leading to scission. These observations show that the CHMP1B-IST1 ESCRT-III combination is capable of severing membranes by a friction-driven mechanism that is independent of VPS4 and spastin.
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Affiliation(s)
- A. King Cada
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
| | - Mark R. Pavlin
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
- Graduate Group in Biophysics, University of California, Berkeley, CA 94720
| | - Juan P. Castillo
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Alexander B. Tong
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
- Department of Chemistry, University of California, Berkeley, CA 94720
| | - Kevin P. Larsen
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
| | - Xuefeng Ren
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
| | - Adam L. Yokom
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
| | - Feng-Ching Tsai
- Laboratoire Physico-Chimie Curie, Institut Curie, Université Paris Sciences & Letters, CNRS UMR168, Sorbonne Université, Paris, 75005 France
| | - Jamie V. Shiah
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
| | - Patricia M. Bassereau
- Laboratoire Physico-Chimie Curie, Institut Curie, Université Paris Sciences & Letters, CNRS UMR168, Sorbonne Université, Paris, 75005 France
| | - Carlos J. Bustamante
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
- Graduate Group in Biophysics, University of California, Berkeley, CA 94720
- Department of Chemistry, University of California, Berkeley, CA 94720
- Department of Physics, University of California, Berkeley, CA 94720
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720
- Kavli Energy Nanoscience Institute, University of California, Berkeley, CA 94720
| | - James H. Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720
- Graduate Group in Biophysics, University of California, Berkeley, CA 94720
- Helen Wills Institute of Neuroscience, University of California, Berkeley, CA 94720
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39
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Schmieder SS, Tatituri R, Anderson M, Kelly K, Lencer WI. Structural basis for acyl chain control over glycosphingolipid sorting and vesicular trafficking. Cell Rep 2022; 40:111063. [PMID: 35830800 PMCID: PMC9358721 DOI: 10.1016/j.celrep.2022.111063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 12/13/2021] [Accepted: 06/15/2022] [Indexed: 11/17/2022] Open
Abstract
The complex sphingolipids exhibit a diversity of ceramide acyl chain structures that influence their trafficking and intracellular distributions, but it remains unclear how the cell discerns among the different ceramides to affect such sorting. To address the mechanism, we synthesize a library of GM1 glycosphingolipids with naturally varied acyl chains and quantitatively assess their sorting among different endocytic pathways. We find that a stretch of at least 14 saturated carbons extending from C1 at the water-bilayer interface dictate lysosomal sorting by exclusion from endosome sorting tubules. Sorting to the lysosome by the C14∗ motif is cholesterol dependent. Perturbations of the C14∗ motif by unsaturation enable GM1 entry into endosomal sorting tubules of the recycling and retrograde pathways independent of cholesterol. Unsaturation occurring beyond the C14∗ motif in very long acyl chains rescues lysosomal sorting. These results define a structural motif underlying the membrane organization of sphingolipids and implicate cholesterol-sphingolipid nanodomain formation in sorting mechanisms.
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Affiliation(s)
| | - Raju Tatituri
- Division of Rheumatology, Brigham and Women's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA
| | - Michael Anderson
- Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Digestive Diseases Center, Boston, MA 02115, USA
| | - Kate Kelly
- Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Wayne I Lencer
- Division of Gastroenterology, Boston Children's Hospital, Boston, MA 02115, USA; Harvard Medical School, Boston, MA 02115, USA; Harvard Digestive Diseases Center, Boston, MA 02115, USA.
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40
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Jin R, Cao R, Baumgart T. Curvature dependence of BAR protein membrane association and dissociation kinetics. Sci Rep 2022; 12:7676. [PMID: 35538113 PMCID: PMC9091223 DOI: 10.1038/s41598-022-11221-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Accepted: 04/18/2022] [Indexed: 11/09/2022] Open
Abstract
BAR (Bin/Amphiphysin/Rvs) domain containing proteins function as lipid bilayer benders and curvature sensors, and they contribute to membrane shaping involved in cell signaling and metabolism. The mechanism for their membrane shape sensing has been investigated by both equilibrium binding and kinetic studies. In prior research, stopped-flow spectroscopy has been used to deduce a positive dependence on membrane curvature for the binding rate constant, kon, of a BAR protein called endophilin. However, the impact of bulk diffusion of endophilin, on the kinetic binding parameters has not been thoroughly considered. Employing similar methods, and using lipid vesicles of multiple sizes, we obtained a linear dependence of kon on vesicle curvature. However, we found that the observed relation can be explained without considering the local curvature sensing ability of endophilin in the membrane association process. In contrast, the diffusion-independent unbinding rate constant (koff) obtained from stopped-flow measurements shows a negative dependence on membrane curvature, which is controlled/mediated by endophilin-membrane interactions. This latter dependency, in addition to protein-protein interactions on the membrane, explains the selective binding of BAR proteins to highly curved membranes in equilibrium binding experiments.
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Affiliation(s)
- Rui Jin
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA
| | - Rui Cao
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.,Division of Biostatistics, University of Minnesota, Minneapolis, MN, USA
| | - Tobias Baumgart
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA.
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41
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Bashkirov PV, Kuzmin PI, Vera Lillo J, Frolov VA. Molecular Shape Solution for Mesoscopic Remodeling of Cellular Membranes. Annu Rev Biophys 2022; 51:473-497. [PMID: 35239417 PMCID: PMC10787580 DOI: 10.1146/annurev-biophys-011422-100054] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cellular membranes self-assemble from and interact with various molecular species. Each molecule locally shapes the lipid bilayer, the soft elastic core of cellular membranes. The dynamic architecture of intracellular membrane systems is based on elastic transformations and lateral redistribution of these elementary shapes, driven by chemical and curvature stress gradients. The minimization of the total elastic stress by such redistribution composes the most basic, primordial mechanism of membrane curvature-composition coupling (CCC). Although CCC is generally considered in the context of dynamic compositional heterogeneity of cellular membrane systems, in this article we discuss a broader involvement of CCC in controlling membrane deformations. We focus specifically on the mesoscale membrane transformations in open, reservoir-governed systems, such as membrane budding, tubulation, and the emergence of highly curved sites of membrane fusion and fission. We reveal that the reshuffling of molecular shapes constitutes an independent deformation mode with complex rheological properties.This mode controls effective elasticity of local deformations as well as stationary elastic stress, thus emerging as a major regulator of intracellular membrane remodeling.
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Affiliation(s)
- Pavel V Bashkirov
- Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, Russia
- Department of Molecular and Biological Physics, Moscow Institute of Physics and Technology, Moscow, Russia
| | - Peter I Kuzmin
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia
| | - Javier Vera Lillo
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain;
| | - Vadim A Frolov
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain;
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
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42
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Sachdev S, Potočnik T, Rems L, Miklavčič D. Revisiting the role of pulsed electric fields in overcoming the barriers to in vivo gene electrotransfer. Bioelectrochemistry 2022; 144:107994. [PMID: 34930678 DOI: 10.1016/j.bioelechem.2021.107994] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 10/15/2021] [Accepted: 11/02/2021] [Indexed: 12/21/2022]
Abstract
Gene therapies are revolutionizing medicine by providing a way to cure hitherto incurable diseases. The scientific and technological advances have enabled the first gene therapies to become clinically approved. In addition, with the ongoing COVID-19 pandemic, we are witnessing record speeds in the development and distribution of gene-based vaccines. For gene therapy to take effect, the therapeutic nucleic acids (RNA or DNA) need to overcome several barriers before they can execute their function of producing a protein or silencing a defective or overexpressing gene. This includes the barriers of the interstitium, the cell membrane, the cytoplasmic barriers and (in case of DNA) the nuclear envelope. Gene electrotransfer (GET), i.e., transfection by means of pulsed electric fields, is a non-viral technique that can overcome these barriers in a safe and effective manner. GET has reached the clinical stage of investigations where it is currently being evaluated for its therapeutic benefits across a wide variety of indications. In this review, we formalize our current understanding of GET from a biophysical perspective and critically discuss the mechanisms by which electric field can aid in overcoming the barriers. We also identify the gaps in knowledge that are hindering optimization of GET in vivo.
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Affiliation(s)
- Shaurya Sachdev
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Tjaša Potočnik
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Lea Rems
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia
| | - Damijan Miklavčič
- University of Ljubljana, Faculty of Electrical Engineering, Tržaška cesta 25, 1000 Ljubljana, Slovenia.
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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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Vyas P, Kumar PBS, Das SL. Sorting of proteins with shape and curvature anisotropy on a lipid bilayer tube. SOFT MATTER 2022; 18:1653-1665. [PMID: 35132986 DOI: 10.1039/d2sm00077f] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Curvature induced sorting of lipid membrane bound proteins has been widely studied through experiments that induce curvature variation in a giant unilamellar lipid-bilayer vesicle with adsorbed proteins by pulling thin cylindrical tethers. In the theoretical space, this has been supplemented with models that capture curvature dependent interaction between membrane and idealized protein particles, through free energy contributions. Many membrane proteins such as the BAR domain proteins are known to have extremely anisotropic shapes and soft interacting potentials, whereas the idealizations of protein particles explored in models have only assumed them as hard disk-like particles with curvature anisotropy. Here, we present a model of sorting of the proteins while including the effects of softness in their interaction potentials, shape anisotropy in the protein structure, and curvature anisotropy in the interactions with the membrane. This is based on a clean separation of free energy contributions from non-ideal fluid behavior of soft anisotropic particles and curvature interactions between proteins and membranes. We probe the behavior of the sorting function under limiting conditions and show that it converges to the previously derived models. In addition to this, we present a comparison of the variation in sorting ratio due to the observed variation in the shape parameter values in known membrane proteins. Finally, using published experimental data for membrane proteins, we perform fitting and derive model parameters. We observe that shape anisotropy adversely affects the sorting of proteins to a high curvature region, whereas curvature anisotropy and softer interaction between proteins favor sorting.
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Affiliation(s)
- Pranav Vyas
- Department of Bioengineering, Stanford University, Stanford, California 94305, USA.
| | - P B Sunil Kumar
- Department of Physics, Indian Institute of Technology Palakkad, Palakkad 678623, India
| | - Sovan Lal Das
- Physical and Chemical Biology Laboratory and Department of Mechanical Engineering, Indian Institute of Technology Palakkad, Palakkad 678623, India
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45
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Sun W, Gao X, Lei H, Wang W, Cao Y. Biophysical Approaches for Applying and Measuring Biological Forces. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2105254. [PMID: 34923777 PMCID: PMC8844594 DOI: 10.1002/advs.202105254] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Indexed: 05/13/2023]
Abstract
Over the past decades, increasing evidence has indicated that mechanical loads can regulate the morphogenesis, proliferation, migration, and apoptosis of living cells. Investigations of how cells sense mechanical stimuli or the mechanotransduction mechanism is an active field of biomaterials and biophysics. Gaining a further understanding of mechanical regulation and depicting the mechanotransduction network inside cells require advanced experimental techniques and new theories. In this review, the fundamental principles of various experimental approaches that have been developed to characterize various types and magnitudes of forces experienced at the cellular and subcellular levels are summarized. The broad applications of these techniques are introduced with an emphasis on the difficulties in implementing these techniques in special biological systems. The advantages and disadvantages of each technique are discussed, which can guide readers to choose the most suitable technique for their questions. A perspective on future directions in this field is also provided. It is anticipated that technical advancement can be a driving force for the development of mechanobiology.
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Affiliation(s)
- Wenxu Sun
- School of SciencesNantong UniversityNantong226019P. R. China
| | - Xiang Gao
- Key Laboratory of Intelligent Optical Sensing and IntegrationNational Laboratory of Solid State Microstructureand Department of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210023P. R. China
- Institute of Brain ScienceNanjing UniversityNanjing210023P. R. China
| | - Hai Lei
- Key Laboratory of Intelligent Optical Sensing and IntegrationNational Laboratory of Solid State Microstructureand Department of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210023P. R. China
- Institute of Brain ScienceNanjing UniversityNanjing210023P. R. China
- Chemistry and Biomedicine Innovation CenterNanjing UniversityNanjing210023P. R. China
| | - Wei Wang
- Key Laboratory of Intelligent Optical Sensing and IntegrationNational Laboratory of Solid State Microstructureand Department of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210023P. R. China
- Institute of Brain ScienceNanjing UniversityNanjing210023P. R. China
| | - Yi Cao
- Key Laboratory of Intelligent Optical Sensing and IntegrationNational Laboratory of Solid State Microstructureand Department of PhysicsCollaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210023P. R. China
- Institute of Brain ScienceNanjing UniversityNanjing210023P. R. China
- MOE Key Laboratory of High Performance Polymer Materials and TechnologyDepartment of Polymer Science & EngineeringCollege of Chemistry & Chemical EngineeringNanjing UniversityNanjing210023P. R. China
- Chemistry and Biomedicine Innovation CenterNanjing UniversityNanjing210023P. R. China
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46
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Karal MAS, Mokta NA, Levadny V, Belaya M, Ahmed M, Ahamed MK, Ahammed S. Effects of cholesterol on the size distribution and bending modulus of lipid vesicles. PLoS One 2022; 17:e0263119. [PMID: 35089965 PMCID: PMC8797199 DOI: 10.1371/journal.pone.0263119] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 01/12/2022] [Indexed: 11/19/2022] Open
Abstract
The influence of cholesterol fraction in the membranes of giant unilamellar vesicles (GUVs) on their size distributions and bending moduli has been investigated. The membranes of GUVs were synthesized by a mixture of two elements: electrically neutral lipid 1, 2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cholesterol and also a mixture of three elements: electrically charged lipid 1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DOPG), DOPC and cholesterol. The size distributions of GUVs have been presented by a set of histograms. The classical lognormal distribution is well fitted to the histograms, from where the average size of vesicle is obtained. The increase of cholesterol content in the membranes of GUVs increases the average size of vesicles in the population. Using the framework of Helmholtz free energy of the system, the theory developed by us is extended to explain the experimental results. The theory determines the influence of cholesterol on the bending modulus of membranes from the fitting of the proper histograms. The increase of cholesterol in GUVs increases both the average size of vesicles in population and the bending modulus of membranes.
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Affiliation(s)
- Mohammad Abu Sayem Karal
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
- * E-mail:
| | - Nadia Akter Mokta
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - Victor Levadny
- Theoretical Problem Center of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
| | - Marina Belaya
- Department of Mathematics of Russian State University for the Humanities, Moscow, Russia
| | - Marzuk Ahmed
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - Md. Kabir Ahamed
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
| | - Shareef Ahammed
- Department of Physics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh
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47
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Ozdemir ES, Koester AM, Nan X. Ras Multimers on the Membrane: Many Ways for a Heart-to-Heart Conversation. Genes (Basel) 2022; 13:219. [PMID: 35205266 PMCID: PMC8872464 DOI: 10.3390/genes13020219] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 01/20/2022] [Accepted: 01/21/2022] [Indexed: 12/31/2022] Open
Abstract
Formation of Ras multimers, including dimers and nanoclusters, has emerged as an exciting, new front of research in the 'old' field of Ras biomedicine. With significant advances made in the past few years, we are beginning to understand the structure of Ras multimers and, albeit preliminary, mechanisms that regulate their formation in vitro and in cells. Here we aim to synthesize the knowledge accrued thus far on Ras multimers, particularly the presence of multiple globular (G-) domain interfaces, and discuss how membrane nanodomain composition and structure would influence Ras multimer formation. We end with some general thoughts on the potential implications of Ras multimers in basic and translational biology.
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Affiliation(s)
- E. Sila Ozdemir
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute, Oregon Health & Science University, 2720 S Moody Ave., Portland, OR 97201, USA;
| | - Anna M. Koester
- Program in Quantitative and Systems Biology, Department of Biomedical Engineering, Oregon Health & Science University, 2730 S Moody Ave., Portland, OR 97201, USA;
| | - Xiaolin Nan
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute, Oregon Health & Science University, 2720 S Moody Ave., Portland, OR 97201, USA;
- Program in Quantitative and Systems Biology, Department of Biomedical Engineering, Oregon Health & Science University, 2730 S Moody Ave., Portland, OR 97201, USA;
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48
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Roux A. Common principles of surface deformation in biology. Faraday Discuss 2021; 232:347-357. [PMID: 34854444 DOI: 10.1039/d1fd00040c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Living organisms, whether they are cells or multicellular organisms, are separated from their environment by an interface. For example, cells are delimited by lipid bilayers while embryos or individuals are delimited by epithelia, ectoderms or epiderms. These biological interfaces, while being different in nature and composition, and at very different scales, share common properties: they are surfaces, their thickness being very small compared to their size. They are materials of chemical composition or cell type that is unique and different from the core of the material they envelop. They are visco-elastic sheets, meaning that components can flow in the plane of the surface. The shape of cells and of embryos is inherently dictated by the shape of their envelope, and because these interfaces have common properties, we explore in this commentary article the different mechanisms that remodel these different biological surfaces, and their common principles.
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Affiliation(s)
- Aurélien Roux
- Department of Biochemistry, University of Geneva, CH-1211 Geneva, Switzerland. .,National Center of Competence in Research Chemical Biology, University of Geneva, CH-1211 Geneva, Switzerland
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49
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Kumar D, Schroeder CM. Nonlinear Transient and Steady State Stretching of Deflated Vesicles in Flow. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13976-13984. [PMID: 34813335 DOI: 10.1021/acs.langmuir.1c01275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Membrane-bound vesicles and organelles exhibit a wide array of nonspherical shapes at equilibrium, including biconcave and tubular morphologies. Despite recent progress, the stretching dynamics of deflated vesicles is not fully understood, particularly far from equilibrium where complex nonspherical shapes undergo large deformations in flow. Here, we directly observe the transient and steady-state nonlinear stretching dynamics of deflated vesicles in extensional flow using a Stokes trap. Automated flow control is used to observe vesicle dynamics over a wide range of flow rates, shape anisotropy, and viscosity contrast. Our results show that deflated vesicle membranes stretch into highly deformed shapes in flow above a critical capillary number Cac1. We further identify a second critical capillary number Cac2, above which vesicle stretch diverges in flow. Vesicles are robust to multiple nonlinear stretch-relax cycles, evidenced by relaxation of dumbbell-shaped vesicles containing thin lipid tethers following flow cessation. An analytical model is developed for vesicle deformation in flow, which enables comparison of nonlinear steady-state stretching results with theories for different reduced volumes. Our results show that the model captures the steady-state stretching of moderately deflated vesicles; however, it underpredicts the steady-state nonlinear stretching of highly deflated vesicles. Overall, these results provide a new understanding of the nonlinear stretching dynamics and membrane mechanics of deflated vesicles in flow.
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Affiliation(s)
- Dinesh Kumar
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Charles M Schroeder
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
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50
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Gorelova V, Sprakel J, Weijers D. Plant cell polarity as the nexus of tissue mechanics and morphogenesis. NATURE PLANTS 2021; 7:1548-1559. [PMID: 34887521 DOI: 10.1038/s41477-021-01021-w] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 10/13/2021] [Indexed: 05/20/2023]
Abstract
How reproducible body patterns emerge from the collective activity of individual cells is a key question in developmental biology. Plant cells are encaged in their walls and unable to migrate. Morphogenesis thus relies on directional cell division, by precise positioning of division planes, and anisotropic cellular growth, mediated by regulated mechanical inhomogeneity of the walls. Both processes require the prior establishment of cell polarity, marked by the formation of polar domains at the plasma membrane, in a number of developmental contexts. The establishment of cell polarity involves biochemical cues, but increasing evidence suggests that mechanical forces also play a prominent instructive role. While evidence for mutual regulation between cell polarity and tissue mechanics is emerging, the nature of this bidirectional feedback remains unclear. Here we review the role of cell polarity at the interface of tissue mechanics and morphogenesis. We also aim to integrate biochemistry-centred insights with concepts derived from physics and physical chemistry. Lastly, we propose a set of questions that will help address the fundamental nature of cell polarization and its mechanistic basis.
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Affiliation(s)
- Vera Gorelova
- Laboratory of Biochemistry, Wageningen University and Research, Wageningen, the Netherlands
| | - Joris Sprakel
- Physical Chemistry and Soft Matter, Wageningen University and Research, Wageningen, the Netherlands
| | - Dolf Weijers
- Laboratory of Biochemistry, Wageningen University and Research, Wageningen, the Netherlands.
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