1
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Kataoka-Hamai C. Triacylglycerol-droplet-induced bilayer spontaneous curvature in giant unilamellar vesicles. Biophys J 2024; 123:1857-1868. [PMID: 38822522 PMCID: PMC11267425 DOI: 10.1016/j.bpj.2024.05.030] [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: 01/16/2024] [Revised: 04/05/2024] [Accepted: 05/29/2024] [Indexed: 06/03/2024] Open
Abstract
This study investigated the incorporation of triacylglycerol droplets in the bilayers of giant unilamellar vesicles (GUVs) using four triacylglycerols and four phosphatidylcholines by confocal laser scanning microscopy. The triacylglycerol droplets were incorporated between the monolayer leaflets of the GUVs. Among the spherical droplets protruding on only one side of the bilayers, the droplets bound to the outer leaflets outnumbered those bound to the inner leaflets. The more frequent droplet binding to the outer leaflet caused transbilayer asymmetry in the droplet surface density. A vesicle consisting of a single-bilayer spherical segment and a double-bilayer spherical segment was also observed. The yield of these vesicles was comparable with or higher than that of the droplet-incorporating GUVs for many of the phosphatidylcholine-triacylglycerol combinations. In a vesicle consisting of single-bilayer and double-bilayer segments, most of the triacylglycerol droplets were localized on the outermost membrane surface along the segment boundary and in the double-bilayer segment. To rationalize the formation of these vesicle structures, we propose that the transbilayer asymmetry in the droplet surface density induces spontaneous curvature of the bilayer, with the bilayer spontaneously bending away from the droplets. Energy calculations performed assuming the existence of spontaneous curvature of the bilayer corroborated the experimentally determined membrane shapes for the vesicles consisting of unilamellar and bilamellar regions.
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Affiliation(s)
- Chiho Kataoka-Hamai
- Research Center for Macromolecules and Biomaterials, National Institute for Materials Science, Tsukuba, Ibaraki, Japan.
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2
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Ali Moussa HY, Shin KC, Ponraj J, Park SH, Lee OS, Mansour S, Park Y. PIP 2 Is An Electrostatic Catalyst for Vesicle Fusion by Lowering the Hydration Energy: Arresting Vesicle Fusion by Masking PIP 2. ACS NANO 2024; 18:12737-12748. [PMID: 38717305 DOI: 10.1021/acsnano.3c09614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Lipids are key factors in regulating membrane fusion. Lipids are not only structural components to form membranes but also active catalysts for vesicle fusion and neurotransmitter release, which are driven by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. SNARE proteins seem to be partially assembled before fusion, but the mechanisms that arrest vesicle fusion before Ca2+ influx are still not clear. Here, we show that phosphatidylinositol 4,5-bisphosphate (PIP2) electrostatically triggers vesicle fusion as an electrostatic catalyst by lowering the hydration energy and that a myristoylated alanine-rich C-kinase substrate (MARCKS), a PIP2-binding protein, arrests vesicle fusion in a vesicle docking state where the SNARE complex is partially assembled. Vesicle-mimicking liposomes fail to reproduce vesicle fusion arrest by masking PIP2, indicating that native vesicles are essential for the reconstitution of physiological vesicle fusion. PIP2 attracts cations to repel water molecules from membranes, thus lowering the hydration energy barrier.
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Affiliation(s)
- Houda Yasmine Ali Moussa
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Kyung Chul Shin
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Janarthanan Ponraj
- HBKU Core Laboratories, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | | | - One-Sun Lee
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, P. J. Šafárik University, Košice SK-04001, Slovakia
| | - Said Mansour
- HBKU Core Laboratories, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | - Yongsoo Park
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
- College of Health & Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
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3
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Krupa P, La Penna G, Li MS. Amyloid- β Tetramers and Divalent Cations at the Membrane/Water Interface: Simple Models Support a Functional Role. Int J Mol Sci 2023; 24:12698. [PMID: 37628878 PMCID: PMC10454299 DOI: 10.3390/ijms241612698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 08/04/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
Charge polarization at the membrane interface is a fundamental process in biology. Despite the lower concentration compared to the abundant monovalent ions, the relative abundance of divalent cations (Ca2+, Mg2+, Zn2+, Fe2+, Cu2+) in particular spaces, such as the neuron synapse, raised many questions on the possible effects of free multivalent ions and of the required protection of membranes by the eventual defects caused by the free forms of the cations. In this work, we first applied a recent realistic model of divalent cations to a well-investigated model of a polar lipid bilayer, di-myristoyl phosphatidyl choline (DMPC). The full atomistic model allows a fairly good description of changes in the hydration of charged and polar groups upon the association of cations to lipid atoms. The lipid-bound configurations were analyzed in detail. In parallel, amyloid-β 1-42 (Aβ42) peptides assembled into tetramers were modeled at the surface of the same bilayer. Two of the protein tetramers' models were loaded with four Cu2+ ions, the latter bound as in DMPC-free Aβ42 oligomers. The two Cu-bound models differ in the binding topology: one with each Cu ion binding each of the monomers in the tetramer; one with pairs of Cu ions linking two monomers into dimers, forming tetramers as dimers of dimers. The models here described provide hints on the possible role of Cu ions in synaptic plasticity and of Aβ42 oligomers in storing the same ions away from lipids. The release of structurally disordered peptides in the synapse can be a mechanism to recover ion homeostasis and lipid membranes from changes in the divalent cation concentration.
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Affiliation(s)
- Pawel Krupa
- Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland; (P.K.); (M.S.L.)
| | - Giovanni La Penna
- Institute of Chemistry of Organometallic Compounds, National Research Council, 50019 Sesto Fiorentino, Italy
- Section of Roma Tor Vergata, National Institute of Nuclear Physics, 00133 Roma, Italy
| | - Mai Suan Li
- Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw, Poland; (P.K.); (M.S.L.)
- Institute for Computational Science and Technology, Ho Chi Minh City 700000, Vietnam
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4
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Saldanha O, Schiller L, Hauser K. Calcium-induced compaction and clustering of vesicles tracked with molecular resolution. Biophys J 2023; 122:2646-2654. [PMID: 37218132 PMCID: PMC10397570 DOI: 10.1016/j.bpj.2023.05.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 04/20/2023] [Accepted: 05/18/2023] [Indexed: 05/24/2023] Open
Abstract
Theory and simulations predict the complex nature of calcium interaction with the lipid membrane. By maintaining the calcium concentrations at physiological conditions, herein we demonstrate experimentally the effect of Ca2+ in a minimalistic cell-like model. For this purpose, giant unilamellar vesicles (GUVs) with a neutral lipid DOPC are generated, and the ion-lipid interaction is observed with attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy providing molecular resolution. Firstly, Ca2+ encapsulated within the vesicle binds to the phosphate head groups of the inner leaflets and triggers vesicle compaction. This is tracked by changes in vibrational modes of the lipid groups. As the calcium concentration within the GUV increases, IR intensities change indicating vesicle dehydration and lateral compression of the membrane. Secondly, by inducing a calcium gradient across the membrane up to a ratio of 1:20, interaction between several vesicles occurs as Ca2+ can bind to the outer leaflets leading to vesicle clustering. It is observed that larger calcium gradients induce stronger interactions. These findings with an exemplary biomimetic model reveal that divalent calcium ions not only cause local changes to the lipid packing but also have macroscopic implications to initiate vesicle-vesicle interaction.
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Affiliation(s)
- Oliva Saldanha
- Department of Chemistry, University of Konstanz, Konstanz, Germany
| | - Laura Schiller
- Department of Chemistry, University of Konstanz, Konstanz, Germany
| | - Karin Hauser
- Department of Chemistry, University of Konstanz, Konstanz, Germany.
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5
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Caliari A, Hanczyc MM, Imai M, Xu J, Yomo T. Quantification of Giant Unilamellar Vesicle Fusion Products by High-Throughput Image Analysis. Int J Mol Sci 2023; 24:ijms24098241. [PMID: 37175944 PMCID: PMC10179211 DOI: 10.3390/ijms24098241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/29/2023] [Accepted: 05/02/2023] [Indexed: 05/15/2023] Open
Abstract
Artificial cells are based on dynamic compartmentalized systems. Thus, remodeling of membrane-bound systems, such as giant unilamellar vesicles, is finding applications beyond biological studies, to engineer cell-mimicking structures. Giant unilamellar vesicle fusion is rapidly becoming an essential experimental step as artificial cells gain prominence in synthetic biology. Several techniques have been developed to accomplish this step, with varying efficiency and selectivity. To date, characterization of vesicle fusion has relied on small samples of giant vesicles, examined either manually or by fluorometric assays on suspensions of small and large unilamellar vesicles. Automation of the detection and characterization of fusion products is now necessary for the screening and optimization of these fusion protocols. To this end, we implemented a fusion assay based on fluorophore colocalization on the membranes and in the lumen of vesicles. Fluorescence colocalization was evaluated within single compartments by image segmentation with minimal user input, allowing the application of the technique to high-throughput screenings. After detection, statistical information on vesicle fluorescence and morphological properties can be summarized and visualized, assessing lipid and content transfer for each object by the correlation coefficient of different fluorescence channels. Using this tool, we report and characterize the unexpected fusogenic activity of sodium chloride on phosphatidylcholine giant vesicles. Lipid transfer in most of the vesicles could be detected after 20 h of incubation, while content exchange only occurred with additional stimuli in around 8% of vesicles.
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Affiliation(s)
- Adriano Caliari
- Laboratory of Biology and Information Science, School of Life Sciences, East China Normal University, Shanghai 200062, China
- Laboratory for Artificial Biology, Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Polo Scientifico e Tecnologico Fabio Ferrari, Polo B, Via Sommarive 9, 38123 Povo, Italy
| | - Martin M Hanczyc
- Laboratory for Artificial Biology, Department of Cellular, Computational and Integrative Biology (CIBIO), University of Trento, Polo Scientifico e Tecnologico Fabio Ferrari, Polo B, Via Sommarive 9, 38123 Povo, Italy
| | - Masayuki Imai
- Department of Physics, Graduate School of Science, Tohoku University, 6-3 Aramaki, Aoba, Sendai 980-8578, Japan
| | - Jian Xu
- Laboratory of Biology and Information Science, School of Life Sciences, East China Normal University, Shanghai 200062, China
| | - Tetsuya Yomo
- Laboratory of Biology and Information Science, School of Life Sciences, East China Normal University, Shanghai 200062, China
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6
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Eremchev M, Roesel D, Dansette PM, Michailovas A, Roke S. High throughput wide field second harmonic imaging of giant unilamellar vesicles. Biointerphases 2023; 18:031202. [PMID: 37289033 DOI: 10.1116/6.0002640] [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: 03/05/2023] [Accepted: 05/16/2023] [Indexed: 06/09/2023] Open
Abstract
Cell-sized giant unilamellar vesicles (GUVs) are an ideal tool for understanding lipid membrane structure and properties. Label-free spatiotemporal images of their membrane potential and structure would greatly aid the quantitative understanding of membrane properties. In principle, second harmonic imaging is a great tool to do so, but the low degree of spatial anisotropy that arises from a single membrane limits its application. Here, we advance the use of wide-field high throughput SH imaging by SH imaging with the use of ultrashort laser pulses. We achieve a throughput improvement of 78% of the maximum theoretical value and demonstrate subsecond image acquisition times. We show how the interfacial water intensity can be converted into a quantitative membrane potential map. Finally, for GUV imaging, we compare this type of nonresonant SH imaging to resonant SH imaging and two photon imaging using fluorophores.
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Affiliation(s)
- M Eremchev
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineerinsg (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - D Roesel
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineerinsg (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - P-M Dansette
- Ekspla Ltd., Savanoriu Ave. 237, LT-02300 Vilnius, Lithuania
| | - A Michailovas
- Ekspla Ltd., Savanoriu Ave. 237, LT-02300 Vilnius, Lithuania
- Center for Physical Sciences and Technology, Savanoriu Ave. 231, LT-02300 Vilnius, Lithuania
| | - S Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineerinsg (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Institute of Materials Science and Engineering (IMX), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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7
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Eremchev M, Roesel D, Poojari CS, Roux A, Hub JS, Roke S. Passive transport of Ca 2+ ions through lipid bilayers imaged by widefield second harmonic microscopy. Biophys J 2023; 122:624-631. [PMID: 36659849 PMCID: PMC9989880 DOI: 10.1016/j.bpj.2023.01.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 01/04/2023] [Accepted: 01/17/2023] [Indexed: 01/21/2023] Open
Abstract
In biology, release of Ca2+ ions in the cytosol is essential to trigger or control many cell functions. Calcium signaling acutely depends on lipid membrane permeability to Ca2+. For proper understanding of membrane permeability to Ca2+, both membrane hydration and the structure of the hydrophobic core must be taken into account. Here, we vary the hydrophobic core of bilayer membranes and observe different types of behavior in high-throughput wide-field second harmonic imaging. Ca2+ translocation is observed through mono-unsaturated (DOPC:DOPA) membranes, reduced upon the addition of cholesterol, and completely inhibited for branched (DPhPC:DPhPA) and poly-unsaturated (SLPC:SLPA) lipid membranes. We propose, using molecular dynamics simulations, that ion transport occurs through ion-induced transient pores, which requires nonequilibrium membrane restructuring. This results in different rates at different locations and suggests that the hydrophobic structure of lipids plays a much more sophisticated regulating role than previously thought.
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Affiliation(s)
- Maksim Eremchev
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - David Roesel
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Chetan S Poojari
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany
| | - Aurélien Roux
- Biochemistry Department, University of Geneva, Geneva, Switzerland; Swiss National Centre for Competence in Research Programme Chemical Biology, Geneva, Switzerland; School of Chemistry and Biochemistry, University of Geneva, Geneva, Switzerland
| | - Jochen S Hub
- Theoretical Physics and Center for Biophysics, Saarland University, Saarbrücken, Germany
| | - Sylvie Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Institute of Materials Science and Engineering (IMX), School of Engineering (STI), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland; Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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8
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Campanile M, Oliva R, D'Errico G, Del Vecchio P, Petraccone L. The anticancer peptide LL-III alters the physico-chemical properties of a model tumor membrane promoting lipid bilayer permeabilization. Phys Chem Chem Phys 2023; 25:3639-3650. [PMID: 36541682 DOI: 10.1039/d2cp03528f] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
LL-III is an anticancer peptide and has the ability to translocate across tumor cell membranes, which indicates that its action mechanism could be non-membranolytic. However, the exact mechanism through which the peptide gains access into the cell cytoplasm is still unknown. Here, we use a plethora of physico-chemical techniques to characterize the interaction of LL-III with liposomes mimicking the lipid matrix of the tumor cell membrane and its effect on the microstructure and thermotropic properties of the membrane. Furthermore, the effect of the presence of Ca2+ cations at physiological concentration was also investigated. For comparison, the interaction of LL-III with liposomes mimicking the normal cell membrane was also studied. Our results show that the peptide selectively interacts with the model tumor cell membrane. This interaction does not disrupt the lipid bilayer but deeply alters its properties by promoting lipid lateral reorganization and increasing membrane permeability. Overall, our data provide a molecular level description of the interaction of the peptide with the model tumor membrane and are fully consistent with the non-membranolytic action mechanism.
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Affiliation(s)
- Marco Campanile
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126 Naples, Italy.
| | - Rosario Oliva
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126 Naples, Italy.
| | - Gerardino D'Errico
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126 Naples, Italy.
| | - Pompea Del Vecchio
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126 Naples, Italy.
| | - Luigi Petraccone
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, 80126 Naples, Italy.
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9
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Zabala-Ferrera O, Liu P, Beltramo PJ. Determining the Bending Rigidity of Free-Standing Planar Phospholipid Bilayers. MEMBRANES 2023; 13:129. [PMID: 36837632 PMCID: PMC9959114 DOI: 10.3390/membranes13020129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 01/14/2023] [Accepted: 01/17/2023] [Indexed: 06/18/2023]
Abstract
We describe a method to determine membrane bending rigidity from capacitance measurements on large area, free-standing, planar, biomembranes. The bending rigidity of lipid membranes is an important biological mechanical property that is commonly optically measured in vesicles, but difficult to quantify in a planar, unsupported system. To accomplish this, we simultaneously image and apply an electric potential to free-standing, millimeter area, planar lipid bilayers composed of DOPC and DOPG phospholipids to measure the membrane Young's (elasticity) modulus. The bilayer is then modeled as two adjacent thin elastic films to calculate bending rigidity from the electromechanical response of the membrane to the applied field. Using DOPC, we show that bending rigidities determined by this approach are in good agreement with the existing work using neutron spin echo on vesicles, atomic force spectroscopy on supported lipid bilayers, and micropipette aspiration of giant unilamellar vesicles. We study the effect of asymmetric calcium concentration on symmetric DOPC and DOPG membranes and quantify the resulting changes in bending rigidity. This platform offers the ability to create planar bilayers of controlled lipid composition and aqueous ionic environment, with the ability to asymmetrically alter both. We aim to leverage this high degree of compositional and environmental control, along with the capacity to measure physical properties, in the study of various biological processes in the future.
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10
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Warner JM, An D, Stratton BS, O'Shaughnessy B. A hemifused complex is the hub in a network of pathways to membrane fusion. Biophys J 2023; 122:374-385. [PMID: 36463406 PMCID: PMC9892611 DOI: 10.1016/j.bpj.2022.12.003] [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: 03/01/2022] [Revised: 06/25/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022] Open
Abstract
Membrane fusion is a critical step for many essential processes, from neurotransmission to fertilization. For over 40 years, protein-free fusion driven by calcium or other cationic species has provided a simplified model of biological fusion, but the mechanisms remain poorly understood. Cation-mediated membrane fusion and permeation are essential in their own right to drug delivery strategies based on cell-penetrating peptides or cation-bearing lipid nanoparticles. Experimental studies suggest calcium drives anionic membranes to a hemifused intermediate that constitutes a hub in a network of pathways, but the pathway selection mechanism is unknown. Here we develop a mathematical model that identifies the network hub as a highly dynamic hemifusion complex. Multivalent cations drive expansion of this high-tension hemifusion interface between interacting vesicles during a brief transient. The fate of this interface determines the outcome, either fusion, dead-end hemifusion, or vesicle lysis. The model reproduces the unexplained finding that calcium-driven fusion of vesicles with planar membranes typically stalls at hemifusion, and we show the equilibrated hemifused state is a novel lens-shaped complex. Thus, membrane fusion kinetics follow a stochastic trajectory within a network of pathways, with outcome weightings set by a hemifused complex intermediate.
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Affiliation(s)
- Jason M Warner
- Department of Chemical Engineering, Columbia University, New York, New York
| | - Dong An
- Department of Chemical Engineering, Columbia University, New York, New York
| | | | - Ben O'Shaughnessy
- Department of Chemical Engineering, Columbia University, New York, New York.
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11
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Gahan CG, Van Lehn RC, Blackwell HE, Lynn DM. Interactions of Bacterial Quorum Sensing Signals with Model Lipid Membranes: Influence of Membrane Composition on Membrane Remodeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:295-307. [PMID: 36534123 PMCID: PMC10038191 DOI: 10.1021/acs.langmuir.2c02506] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
We report the influence of membrane composition on the multiscale remodeling of multicomponent lipid bilayers initiated by contact with the amphiphilic bacterial quorum sensing signal N-(3-oxo)-dodecanoyl-l-homoserine lactone (3-oxo-C12-AHL) and its anionic headgroup hydrolysis product, 3-oxo-C12-HS. We used fluorescence microscopy and quartz crystal microbalance with dissipation (QCM-D) to characterize membrane reformation that occurs when these amphiphiles are placed in contact with supported lipid bilayers (SLBs) composed of (i) 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) containing varying amounts of cholesterol or (ii) mixtures of DOPC and either 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE, a conical zwitterionic lipid) or 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS, a model anionic lipid). In general, we observe these mixed-lipid membranes to undergo remodeling events, including the formation and subsequent collapse of long tubules and the formation of hemispherical caps, upon introduction to biologically relevant concentrations of 3-oxo-C12-AHL and 3-oxo-C12-HS in ways that differ substantially from those observed in single-component DOPC membranes. These differences in bilayer reformation and their associated dynamics can be understood in terms of the influence of membrane composition on the time scales of molecular flip-flop, lipid packing defects, and lipid phase segregation in these materials. The lipid components investigated here are representative of classes of lipids that comprise both naturally occurring cell membranes and many useful synthetic soft materials. These studies thus represent a first step toward understanding the ways in which membrane composition can impact interactions with this important class of bacterial signaling molecules.
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Affiliation(s)
- Curran G. Gahan
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
| | - Reid C. Van Lehn
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
| | - Helen E. Blackwell
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
| | - David M. Lynn
- Department of Chemical and Biological Engineering, University of Wisconsin–Madison, 1415 Engineering Dr., Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Ave., Madison, WI 53706, USA
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12
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Stephan MS, Dunsing V, Pramanik S, Chiantia S, Barbirz S, Robinson T, Dimova R. Biomimetic asymmetric bacterial membranes incorporating lipopolysaccharides. Biophys J 2022:S0006-3495(22)03927-3. [PMID: 36523159 DOI: 10.1016/j.bpj.2022.12.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/30/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Gram-negative bacteria are equipped with a cell wall that contains a complex matrix of lipids, proteins, and glycans, which form a rigid layer protecting bacteria from the environment. Major components of this outer membrane are the high-molecular weight and amphiphilic lipopolysaccharides (LPSs). They form the extracellular part of a heterobilayer with phospholipids. Understanding LPS properties within the outer membrane is therefore important to develop new antimicrobial strategies. Model systems, such as giant unilamellar vesicles (GUVs), provide a suitable platform for exploring membrane properties and interactions. However, LPS molecules contain large polysaccharide parts that confer high water solubility, which makes LPS incorporation in artificial membranes difficult; this hindrance is exacerbated for LPS with long polysaccharide chains, i.e., the smooth LPS. Here, a novel emulsification step of the inverted emulsion method is introduced to incorporate LPS in the outer or the inner leaflet of GUVs, exclusively. We developed an approach to determine the LPS content on individual GUVs and quantify membrane asymmetry. The asymmetric membranes with outer leaflet LPS show incorporations of 1-16 mol % smooth LPS (corresponding to 16-79 wt %), while vesicles with inner leaflet LPS reach coverages of 2-7 mol % smooth LPS (28-60 wt %). Diffusion coefficient measurements in the obtained GUVs showed that increasing LPS concentrations in the membranes resulted in decreased diffusivity.
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Affiliation(s)
| | - Valentin Dunsing
- Aix-Marseille Université, CNRS, IBDM, Turing Center for Living Systems, Marseille, France; University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Shreya Pramanik
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Salvatore Chiantia
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Stefanie Barbirz
- Department Humanmedizin, MSB Medical School Berlin, Berlin, Germany
| | - Tom Robinson
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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13
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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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14
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Somberg NH, Wu WW, Medeiros-Silva J, Dregni AJ, Jo H, DeGrado WF, Hong M. SARS-CoV-2 Envelope Protein Forms Clustered Pentamers in Lipid Bilayers. Biochemistry 2022; 61:2280-2294. [PMID: 36219675 PMCID: PMC9583936 DOI: 10.1021/acs.biochem.2c00464] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 09/26/2022] [Indexed: 11/30/2022]
Abstract
The SARS-CoV-2 envelope (E) protein is a viroporin associated with the acute respiratory symptoms of COVID-19. E forms cation-selective ion channels that assemble in the lipid membrane of the endoplasmic reticulum Golgi intermediate compartment. The channel activity of E is linked to the inflammatory response of the host cell to the virus. Like many viroporins, E is thought to oligomerize with a well-defined stoichiometry. However, attempts to determine the E stoichiometry have led to inconclusive results and suggested mixtures of oligomers whose exact nature might vary with the detergent used. Here, we employ 19F solid-state nuclear magnetic resonance and the centerband-only detection of exchange (CODEX) technique to determine the oligomeric number of E's transmembrane domain (ETM) in lipid bilayers. The CODEX equilibrium value, which corresponds to the inverse of the oligomeric number, indicates that ETM assembles into pentamers in lipid bilayers, without any detectable fraction of low-molecular-weight oligomers. Unexpectedly, at high peptide concentrations and in the presence of the lipid phosphatidylinositol, the CODEX data indicate that more than five 19F spins are within a detectable distance of about 2 nm, suggesting that the ETM pentamers cluster in the lipid bilayer. Monte Carlo simulations that take into account peptide-peptide and peptide-lipid interactions yielded pentamer clusters that reproduced the CODEX data. This supramolecular organization is likely important for E-mediated virus assembly and budding and for the channel function of the protein.
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Affiliation(s)
- Noah H. Somberg
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Westley W. Wu
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - João Medeiros-Silva
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Aurelio J. Dregni
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Hyunil Jo
- Department of Pharmaceutical Chemistry, 555 Mission Bay Blvd. South, University of California, San Francisco, San Francisco, CA 94158
| | - William F. DeGrado
- Department of Pharmaceutical Chemistry, 555 Mission Bay Blvd. South, University of California, San Francisco, San Francisco, CA 94158
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
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15
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Li S, Feng X, Zhang X, Xie S, Ma F. Phospholipid and antioxidant responses of oleaginous fungus Cunninghamella echinulata against hydrogen peroxide stress. Arch Biochem Biophys 2022; 731:109447. [DOI: 10.1016/j.abb.2022.109447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 11/02/2022]
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16
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Kurakin S, Ivankov O, Skoi V, Kuklin A, Uhríková D, Kučerka N. Cations Do Not Alter the Membrane Structure of POPC—A Lipid With an Intermediate Area. Front Mol Biosci 2022; 9:926591. [PMID: 35898308 PMCID: PMC9312375 DOI: 10.3389/fmolb.2022.926591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 06/07/2022] [Indexed: 12/02/2022] Open
Abstract
Combining small-angle neutron scattering (SANS), small-angle X-ray scattering (SAXS), and densitometric measurements, we have studied the interactions of the divalent cations Ca2+ and Mg2+ with the lipid vesicles prepared of a mixed-chain palmitoyl-oleoyl-phosphatidylcholine (POPC) at 25°C. The structural parameters of the POPC bilayer, such as the bilayer thickness, lateral area, and volume per lipid, displayed no changes upon the ion addition at concentrations up to 30 mM and minor changes at > 30 mM Ca2+ and Mg2+, while some decrease in the vesicle radius was observed over the entire concentration range studied. This examination allows us to validate the concept of lipid–ion interactions governed by the area per lipid suggested previously and to propose the mixed mode of those interactions that emerge in the POPC vesicles. We speculate that the average area per POPC lipid that corresponds to the cutoff length of lipid–ion interactions generates an equal but opposite impact on ion bridges and separate lipid–ion pairs. As a result of the dynamic equilibrium, the overall structural properties of bilayers are not affected. As the molecular mechanism proposed is affected by the structural properties of a particular lipid, it might help us to understand the fundamentals of processes occurring in complex multicomponent membrane systems.
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Affiliation(s)
- Sergei Kurakin
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
- Institute of Physics, Kazan Federal University, Kazan, Russia
| | - Oleksandr Ivankov
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
| | - Vadim Skoi
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
- Moscow Institute of Physics and Technology, Dolgoprudnyi, Russia
| | - Alexander Kuklin
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
- Moscow Institute of Physics and Technology, Dolgoprudnyi, Russia
| | - Daniela Uhríková
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Bratislava, Slovakia
| | - Norbert Kučerka
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Russia
- Department of Physical Chemistry of Drugs, Faculty of Pharmacy, Comenius University Bratislava, Bratislava, Slovakia
- *Correspondence: Norbert Kučerka,
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17
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Varani J, McClintock SD, Knibbs RN, Harber I, Zeidan D, Jawad-Makki MAH, Aslam MN. Liver Protein Expression in NASH Mice on a High-Fat Diet: Response to Multi-Mineral Intervention. Front Nutr 2022; 9:859292. [PMID: 35634402 PMCID: PMC9130755 DOI: 10.3389/fnut.2022.859292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 04/05/2022] [Indexed: 11/13/2022] Open
Abstract
Male MS-NASH mice were maintained on a high-fat diet for 16 weeks with and without red algae-derived minerals. Obeticholic acid (OCA) was used as a comparator in the same strain and diet. C57BL/6 mice maintained on a standard (low-fat) rodent chow diet were used as a control. At the end of the in-life portion of the study, body weight, liver weight, liver enzyme levels and liver histology were assessed. Samples obtained from individual livers were subjected to Tandem Mass Tag labeling / mass spectroscopy for protein profile determination. As compared to mice maintained on the low-fat diet, all high-fat-fed mice had increased whole-body and liver weight, increased liver enzyme (aminotransferases) levels and widespread steatosis / ballooning hepatocyte degeneration. Histological evidence for liver inflammation and collagen deposition was also present, but changes were to a lesser extent. A moderate reduction in ballooning degeneration and collagen deposition was observed with mineral supplementation. Control mice on the high-fat diet alone demonstrated multiple protein changes associated with dysregulated fat and carbohydrate metabolism, lipotoxicity and oxidative stress. Cholesterol metabolism and bile acid formation were especially sensitive to diet. In mice receiving multi-mineral supplementation along with the high-fat diet, there was reduced liver toxicity as evidenced by a decrease in levels of several cytochrome P450 enzymes and other oxidant-generating moieties. Additionally, elevated expression of several keratins was also detected in mineral-supplemented mice. The protein changes observed with mineral supplementation were not seen with OCA. Our previous studies have shown that mice maintained on a high-fat diet for up to 18 months develop end-stage liver injury including hepatocellular carcinoma. Mineral-supplemented mice were substantially protected against tumor formation and other end-state consequences of high-fat feeding. The present study identifies early (16-week) protein changes occurring in the livers of the high-fat diet-fed mice, and how the expression of these proteins is influenced by mineral supplementation. These findings help elucidate early protein changes that contribute to end-stage liver injury and potential mechanisms by which dietary minerals may mitigate such damage.
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Affiliation(s)
- James Varani
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, MI, United States
| | - Shannon D McClintock
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, MI, United States
| | - Randall N Knibbs
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, MI, United States
| | - Isabelle Harber
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, MI, United States
| | - Dania Zeidan
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, MI, United States
| | | | - Muhammad N Aslam
- Department of Pathology, The University of Michigan Medical School, Ann Arbor, MI, United States
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18
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Raut P, Weller SR, Obeng B, Soos BL, West BE, Potts CM, Sangroula S, Kinney MS, Burnell JE, King BL, Gosse JA, Hess ST. Cetylpyridinium chloride (CPC) reduces zebrafish mortality from influenza infection: Super-resolution microscopy reveals CPC interference with multiple protein interactions with phosphatidylinositol 4,5-bisphosphate in immune function. Toxicol Appl Pharmacol 2022; 440:115913. [PMID: 35149080 PMCID: PMC8824711 DOI: 10.1016/j.taap.2022.115913] [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: 10/15/2021] [Revised: 01/04/2022] [Accepted: 02/04/2022] [Indexed: 01/12/2023]
Abstract
The COVID-19 pandemic raises significance for a potential influenza therapeutic compound, cetylpyridinium chloride (CPC), which has been extensively used in personal care products as a positively-charged quaternary ammonium antibacterial agent. CPC is currently in clinical trials to assess its effects on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) morbidity. Two published studies have provided mouse and human data indicating that CPC may alleviate influenza infection, and here we show that CPC (0.1 μM, 1 h) reduces zebrafish mortality and viral load following influenza infection. However, CPC mechanisms of action upon viral-host cell interaction are currently unknown. We have utilized super-resolution fluorescence photoactivation localization microscopy to probe the mode of CPC action. Reduction in density of influenza viral protein hemagglutinin (HA) clusters is known to reduce influenza infectivity: here, we show that CPC (at non-cytotoxic doses, 5-10 μM) reduces HA density and number of HA molecules per cluster within the plasma membrane of NIH-3T3 mouse fibroblasts. HA is known to colocalize with the negatively-charged mammalian lipid phosphatidylinositol 4,5-bisphosphate (PIP2); here, we show that nanoscale co-localization of HA with the PIP2-binding Pleckstrin homology (PH) reporter in the plasma membrane is diminished by CPC. CPC also dramatically displaces the PIP2-binding protein myristoylated alanine-rich C-kinase substrate (MARCKS) from the plasma membrane of rat RBL-2H3 mast cells; this disruption of PIP2 is correlated with inhibition of mast cell degranulation. Together, these findings offer a PIP2-focused mechanism underlying CPC disruption of influenza and suggest potential pharmacological use of this drug as an influenza therapeutic to reduce global deaths from viral disease.
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Affiliation(s)
- Prakash Raut
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Sasha R Weller
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Bright Obeng
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Brandy L Soos
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Bailey E West
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Christian M Potts
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Suraj Sangroula
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Marissa S Kinney
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - John E Burnell
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Benjamin L King
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA
| | - Julie A Gosse
- Department of Molecular and Biomedical Sciences, University of Maine, Orono, ME, USA.
| | - Samuel T Hess
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA.
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19
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Abstract
Constitutive vesicle trafficking is the default pathway used by all cells for movement of intracellular cargoes between subcellular compartments and in and out of the cell. Classically, constitutive trafficking was thought to be continuous and unregulated, in contrast to regulated secretion, wherein vesicles are stored intracellularly until undergoing synchronous membrane fusion following a Ca2+ signal. However, as shown in the literature reviewed here, many continuous trafficking steps can be up- or down-regulated by Ca2+, including several steps associated with human pathologies. Notably, we describe a series of Ca2+ pumps, channels, Ca2+-binding effector proteins, and their trafficking machinery targets that together regulate the flux of cargo in response to genetic alterations as well as baseline and agonist-dependent Ca2+ signals. Here, we review the most recent advances, organized by organellar location, that establish the importance of these components in trafficking steps. Ultimately, we conclude that Ca2+ regulates an expanding series of distinct mechanistic steps. Furthermore, the involvement of Ca2+ in trafficking is complex. For example, in some cases, the same Ca2+ effectors regulate surprisingly distinct trafficking steps, or even the same trafficking step with opposing influences, through binding to different target proteins.
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Affiliation(s)
- John Sargeant
- Division of Biological Sciences & Center for Structural & Functional Neuroscience, University of Montana, 32 Campus Drive, Missoula, MT 59812, USA
| | - Jesse C Hay
- Division of Biological Sciences & Center for Structural & Functional Neuroscience, University of Montana, 32 Campus Drive, Missoula, MT 59812, USA
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20
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Molaei M, Kandy SK, Graber ZT, Baumgart T, Radhakrishnan R, Crocker JC. Probing lipid membrane bending mechanics using gold nanorod tracking. PHYSICAL REVIEW RESEARCH 2022; 4:L012027. [PMID: 35373142 PMCID: PMC8975244 DOI: 10.1103/physrevresearch.4.l012027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Lipid bilayer membranes undergo rapid bending undulations with wavelengths from tens of nanometers to tens of microns due to thermal fluctuations. Here, we probe such undulations and the membranes' mechanics by measuring the time-varying orientation of single gold nanorods (GNRs) adhered to the membrane, using high-speed dark field microscopy. In a lipid vesicle, such measurements allow the determination of the membrane's viscosity, bending rigidity, and tension as well as the friction coefficient for sliding of the monolayers over one another. The in-plane rotation of the GNR is hindered by undulations in a tension dependent manner, consistent with simulations. The motion of single GNRs adhered to the plasma membrane of living cultured cells similarly reveals the membrane's complex physics and coupling to the cell's actomyosin cortex.
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Affiliation(s)
- Mehdi Molaei
- Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Sreeja Kutti Kandy
- Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Zachary T. Graber
- Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Tobias Baumgart
- Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Ravi Radhakrishnan
- Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - John C. Crocker
- Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Corresponding author:
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21
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Lipowsky R. Multispherical shapes of vesicles highlight the curvature elasticity of biomembranes. Adv Colloid Interface Sci 2022; 301:102613. [PMID: 35228127 DOI: 10.1016/j.cis.2022.102613] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 01/29/2022] [Accepted: 01/30/2022] [Indexed: 11/01/2022]
Abstract
Giant lipid vesicles form unusual multispherical or "multi-balloon" shapes consisting of several spheres that are connected by membrane necks. Such multispherical shapes have been recently observed when the two sides of the membranes were exposed to different sugar solutions. This sugar asymmetry induced a spontaneous curvature, the sign of which could be reversed by swapping the interior with the exterior solution. Here, previous studies of multispherical shapes are reviewed and extended to develop a comprehensive theory for these shapes. Each multisphere consists of large and small spheres, characterized by two radii, the large-sphere radius, Rl, and the small-sphere radius, Rs. For positive spontaneous curvature, the multisphere can be built up from variable numbers Nl and Ns of large and small spheres. In addition, multispheres consisting of N*=Nl+Ns equally sized spheres are also possible and provide examples for constant-mean-curvature surfaces. For negative spontaneous curvature, all multispheres consist of one large sphere that encloses a variable number Ns of small spheres. These general features of multispheres arise from two basic properties of curvature elasticity: the local shape equation for spherical membrane segments and the stability conditions for closed membrane necks. In addition, the (Nl+Ns)-multispheres can form several (Nl+Ns)-patterns that differ in the way, in which the spheres are mutually connected. These patterns may involve multispherical junctions consisting of individual spheres that are connected to more than two neighboring spheres. The geometry of the multispheres is governed by two polynomial equations which imply that (Nl+Ns)-multispheres can only be formed within a certain restricted range of vesicle volumes. Each (Nl+Ns)-pattern can be characterized by a certain stability regime that depends both on the stability of the closed necks and on the multispherical geometry. Interesting and challenging topics for future studies include the response of multispheres to locally applied external forces, membrane fusion between spheres to create multispherical shapes of higher-genus topology, and the enlarged morphological complexity of multispheres arising from lipid phase separation and intramembrane domains.
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22
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Mechanism of negative membrane curvature generation by I-BAR domains. Structure 2021; 29:1440-1452.e4. [PMID: 34520736 DOI: 10.1016/j.str.2021.07.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/16/2021] [Accepted: 07/22/2021] [Indexed: 11/23/2022]
Abstract
The membrane sculpting ability of BAR domains has been attributed to the intrinsic curvature of their banana-shaped dimeric structure. However, there is often a mismatch between this intrinsic curvature and the diameter of the membrane tubules generated. I-BAR domains are especially mysterious since they are almost flat but generate high negative membrane curvature. Here, we use atomistic implicit-solvent computer modeling to show that the membrane bending of the IRSp53 I-BAR domain is dictated by its higher oligomeric structure, whose curvature is completely unrelated to the intrinsic curvature of the dimer. Two other I-BARs give similar results, whereas a flat F-BAR sheet develops a concave membrane-binding interface, consistent with its observed positive membrane curvature generation. Laterally interacting helical spirals of I-BAR dimers on tube interiors are stable and have an enhanced binding energy that is sufficient for membrane bending to experimentally observed tubule diameters at a reasonable surface density.
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23
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Kasprzycka W, Trębińska-Stryjewska A, Lewandowski RB, Stępińska M, Osuchowska PN, Dobrzyńska M, Achour Y, Osuchowski ŁP, Starzyński J, Mierczyk Z, Trafny EA. Nanosecond Pulsed Electric Field Only Transiently Affects the Cellular and Molecular Processes of Leydig Cells. Int J Mol Sci 2021; 22:ijms222011236. [PMID: 34681896 PMCID: PMC8541366 DOI: 10.3390/ijms222011236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 12/11/2022] Open
Abstract
The purpose of this study was to verify whether the nanosecond pulsed electric field, not eliciting thermal effects, permanently changes the molecular processes and gene expression of Leydig TM3 cells. The cells were exposed to a moderate electric field (80 quasi-rectangular shape pulses, 60 ns pulse width, and an electric field of 14 kV/cm). The putative disturbances were recorded over 24 h. After exposure to the nanosecond pulsed electric field, a 19% increase in cell diameter, a loss of microvilli, and a 70% reduction in cell adhesion were observed. Some cells showed the nonapoptotic externalization of phosphatidylserine through the pores in the plasma membrane. The cell proportion in the subG1 phase increased by 8% at the expense of the S and G2/M phases, and the DNA was fragmented in a small proportion of the cells. The membrane mitochondrial potential and superoxide content decreased by 37% and 23%, respectively. Microarray’s transcriptome analysis demonstrated a negative transient effect on the expression of genes involved in oxidative phosphorylation, DNA repair, cell proliferation, and the overexpression of plasma membrane proteins. We conclude that nanosecond pulsed electric field affected the physiology and gene expression of TM3 cells transiently, with a noticeable heterogeneity of cellular responses.
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Affiliation(s)
- Wiktoria Kasprzycka
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
| | - Alicja Trębińska-Stryjewska
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
| | - Rafał Bogdan Lewandowski
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
| | - Małgorzata Stępińska
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
| | - Paulina Natalia Osuchowska
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
| | - Monika Dobrzyńska
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
| | - Yahia Achour
- Faculty of Electronics, Military University of Technology, 00-908 Warsaw, Poland; (Y.A.); (J.S.)
| | - Łukasz Paweł Osuchowski
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
| | - Jacek Starzyński
- Faculty of Electronics, Military University of Technology, 00-908 Warsaw, Poland; (Y.A.); (J.S.)
| | - Zygmunt Mierczyk
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
| | - Elżbieta Anna Trafny
- Biomedical Engineering Centre, Institute of Optoelectronics, Military University of Technology, 00-908 Warsaw, Poland; (W.K.); (A.T.-S.); (R.B.L.); (M.S.); (P.N.O.); (M.D.); (Ł.P.O.); (Z.M.)
- Correspondence:
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24
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Jin R, Baumgart T. Asymmetric desorption of lipid oxidation products induces membrane bending. SOFT MATTER 2021; 17:7506-7515. [PMID: 34338699 PMCID: PMC8425771 DOI: 10.1039/d1sm00652e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Lipid oxidation, detected in metabolic processes, is induced in excess when the cellular membrane suffers extra oxidative stress. Lipid oxidation can compromise biomembrane function in part through perturbations of lipid packing, membrane permeability, and morphology. Two major types of oxidation products, one with a partially truncated lipid tail with a hydrophilic group at the tail-end, and secondly, a lysolipid (with one of the chains completely truncated) can disturb the membrane bilayer packing significantly. However, they also have an increased tendency to desorb from the membrane. In this study we investigated desorption kinetics of two characteristic lipid oxidation products (PAzePC and 18 : 1 LysoPC) from a model membrane system, and we evaluated the consequences of this process on membrane shape transitions. Using a microfluidic chamber coupled with micropipette aspiration, we observed the incorporation of the two lipids into the membrane of a giant unilamellar vesicle (GUV) and further determined their desorption rates, association rates and flip-flop rates. For both lipids, the desorption is on the time scale of seconds, one to two orders of magnitude faster than their flipping rates. Dilution of the outer solution of the GUVs allowed asymmetric desorption of these two lipids from the GUVs. This process induced lipid number asymmetry and charge asymmetry, specifically for PAzePC containing GUVs, and caused membrane tubulation. Our results indicate that the desorption of lipid oxidation products can alter the local structure of biomembranes and result in morphological changes that may relate to membrane function.
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Affiliation(s)
- Rui Jin
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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Allolio C, Harries D. Calcium Ions Promote Membrane Fusion by Forming Negative-Curvature Inducing Clusters on Specific Anionic Lipids. ACS NANO 2021; 15:12880-12887. [PMID: 34338519 DOI: 10.1021/acsnano.0c08614] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Vesicles enriched in certain negatively charged lipids, such as phosphatidylserine and PIP2, are known to undergo fusion in the presence of calcium ions without assistance from protein assemblies. Other lipids do not exhibit this propensity, even if they are negatively charged. Using our recently developed methodology, we extract elastic properties of a representative set of lipids. This allows us to trace the origin of lipid-calcium selectivity in membrane fusion to the formation of lipid clusters with long-range correlations that induce negative curvature on the membrane surface. Furthermore, the clusters generate lateral tension in the headgroup region at the membrane surface, concomitantly also stabilizing negative Gaussian curvature. Finally, calcium binding also reduces the orientational polarization of water around the membrane head groups, potentially reducing the hydration force acting between membranes. Binding calcium only weakly increases membrane bending rigidity and tilt moduli, in agreement with experiments. We show how the combined effects of calcium binding to membranes lower the barriers along the fusion pathway that lead to the formation of the fusion stalk as well as the fusion pore.
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Affiliation(s)
- Christoph Allolio
- Charles University, Faculty of Mathematics and Physics, Mathematical Institute, Sokolovská 83, 186 75 Prague 8, Czech Republic
- Institute of Chemistry, The Fritz Haber Center, and The Center for Nanoscience and Nanotechnology, The Hebrew University, E.J. Safra Campus, Jerusalem 9190401, Israel
| | - Daniel Harries
- Institute of Chemistry, The Fritz Haber Center, and The Center for Nanoscience and Nanotechnology, The Hebrew University, E.J. Safra Campus, Jerusalem 9190401, Israel
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Regulation of Store-Operated Ca 2+ Entry by SARAF. Cells 2021; 10:cells10081887. [PMID: 34440656 PMCID: PMC8391525 DOI: 10.3390/cells10081887] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/19/2021] [Accepted: 07/22/2021] [Indexed: 12/14/2022] Open
Abstract
Calcium (Ca2+) signaling plays a dichotomous role in cellular biology, controlling cell survival and proliferation on the one hand and cellular toxicity and cell death on the other. Store-operated Ca2+ entry (SOCE) by CRAC channels represents a major pathway for Ca2+ entry in non-excitable cells. The CRAC channel has two key components, the endoplasmic reticulum Ca2+ sensor stromal interaction molecule (STIM) and the plasma-membrane Ca2+ channel Orai. Physical coupling between STIM and Orai opens the CRAC channel and the resulting Ca2+ flux is regulated by a negative feedback mechanism of slow Ca2+ dependent inactivation (SCDI). The identification of the SOCE-associated regulatory factor (SARAF) and investigations of its role in SCDI have led to new functional and molecular insights into how SOCE is controlled. In this review, we provide an overview of the functional and molecular mechanisms underlying SCDI and discuss how the interaction between SARAF, STIM1, and Orai1 shapes Ca2+ signaling in cells.
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Calcium mediated DNA binding in non-lamellar structures formed by DOPG/glycerol monooleate. Chem Phys Lipids 2021; 239:105118. [PMID: 34280362 DOI: 10.1016/j.chemphyslip.2021.105118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/28/2021] [Accepted: 07/14/2021] [Indexed: 11/21/2022]
Abstract
In order to test an encapsulation method of short fragmented DNA (∼ 20-300 bp), we study the solubilisation in 150 mM solution of NaCl of a cubic phase formed by glycerol monooleate (GMO) with negatively charged dioleoylphosphatidylglycerol (DOPG) up to the level of unilamellar vesicles and, subsequently, the restoration of the cubic phase using Ca2+ cations. We performed small angle X-ray and neutron scattering (SAXS and SANS) to follow structural changes in DOPG/GMO mixtures induced by increasing DOPG content. The cubic phase (Pn3m space group) is preserved up to ∼ 11 mol% of DOPG in DOPG/GMO. Above 20 mol%, the SANS curves are typical of unilamellar vesicles. The thickness of the DOPG/GMO lipid bilayer (dL) decreases slightly with increasing fraction of DOPG. The addition of 15 mM of CaCl2 solution shields the electrostatic repulsions of DOPG molecules, increases slightly dL and restores the cubic structures in the mixtures up to ∼ 37 mol% of DOPG. Zeta potential shows negative surface charge. The analysis of the data provides the radius of the water nano-channels of the formed non-lamellar structures. We discuss their dimensions with respect to DNA binding. In addition, Ca2+ mediates DNA - DOPG/GMO binding. The formed hexagonal phase, HII, binds less of DNA in comparison with cubic phases (∼ 6 wt% and ∼ 20 wt% of the total amount, respectively). The studied system can be utilized as anionic QII delivery vector for genetic material.
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Galassi VV, Wilke N. On the Coupling between Mechanical Properties and Electrostatics in Biological Membranes. MEMBRANES 2021; 11:478. [PMID: 34203412 PMCID: PMC8306103 DOI: 10.3390/membranes11070478] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 06/18/2021] [Accepted: 06/22/2021] [Indexed: 12/24/2022]
Abstract
Cell membrane structure is proposed as a lipid matrix with embedded proteins, and thus, their emerging mechanical and electrostatic properties are commanded by lipid behavior and their interconnection with the included and absorbed proteins, cytoskeleton, extracellular matrix and ionic media. Structures formed by lipids are soft, dynamic and viscoelastic, and their properties depend on the lipid composition and on the general conditions, such as temperature, pH, ionic strength and electrostatic potentials. The dielectric constant of the apolar region of the lipid bilayer contrasts with that of the polar region, which also differs from the aqueous milieu, and these changes happen in the nanometer scale. Besides, an important percentage of the lipids are anionic, and the rest are dipoles or higher multipoles, and the polar regions are highly hydrated, with these water molecules forming an active part of the membrane. Therefore, electric fields (both, internal and external) affects membrane thickness, density, tension and curvature, and conversely, mechanical deformations modify membrane electrostatics. As a consequence, interfacial electrostatics appears as a highly important parameter, affecting the membrane properties in general and mechanical features in particular. In this review we focus on the electromechanical behavior of lipid and cell membranes, the physicochemical origin and the biological implications, with emphasis in signal propagation in nerve cells.
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Affiliation(s)
- Vanesa Viviana Galassi
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza M5500, Argentina;
- Instituto Interdisciplinario de Ciencias Básicas (ICB), Universidad Nacional de Cuyo, CONICET, Mendoza M5500, Argentina
| | - Natalia Wilke
- Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba X5000HUA, Argentina
- Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), Universidad Nacional de Córdoba, CONICET, Córdoba X5000HUA, Argentina
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29
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Lira RB, Leomil FSC, Melo RJ, Riske KA, Dimova R. To Close or to Collapse: The Role of Charges on Membrane Stability upon Pore Formation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:e2004068. [PMID: 34105299 PMCID: PMC8188222 DOI: 10.1002/advs.202004068] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/14/2020] [Indexed: 05/28/2023]
Abstract
Resealing of membrane pores is crucial for cell survival. Membrane surface charge and medium composition are studied as defining regulators of membrane stability. Pores are generated by electric field or detergents. Giant vesicles composed of zwitterionic and negatively charged lipids mixed at varying ratios are subjected to a strong electric pulse. Interestingly, charged vesicles appear prone to catastrophic collapse transforming them into tubular structures. The spectrum of destabilization responses includes the generation of long-living submicroscopic pores and partial vesicle bursting. The origin of these phenomena is related to the membrane edge tension, which governs pore closure. This edge tension significantly decreases as a function of the fraction of charged lipids. Destabilization of charged vesicles upon pore formation is universal-it is also observed with other poration stimuli. Disruption propensity is enhanced for membranes made of lipids with higher degree of unsaturation. It can be reversed by screening membrane charge in the presence of calcium ions. The observed findings in light of theories of stability and curvature generation are interpreted and mechanisms acting in cells to prevent total membrane collapse upon poration are discussed. Enhanced membrane stability is crucial for the success of electroporation-based technologies for cancer treatment and gene transfer.
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Affiliation(s)
- Rafael B. Lira
- Departamento de BiofísicaUniversidade Federal de São PauloSão Paulo04039‐032Brazil
- Department of Theory and BiosystemsMax Planck Institute of Colloids and InterfacesPotsdam14424Germany
- Present address:
Moleculaire BiofysicaZernike InstituutRijksuniversiteitGroningen9747 AGThe Netherlands
| | | | - Renan J. Melo
- Instituto de FísicaUniversidade de São PauloSão Paulo05508‐090Brazil
| | - Karin A. Riske
- Departamento de BiofísicaUniversidade Federal de São PauloSão Paulo04039‐032Brazil
| | - Rumiana Dimova
- Department of Theory and BiosystemsMax Planck Institute of Colloids and InterfacesPotsdam14424Germany
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Guo X, Steinkühler J, Marin M, Li X, Lu W, Dimova R, Melikyan GB. Interferon-Induced Transmembrane Protein 3 Blocks Fusion of Diverse Enveloped Viruses by Altering Mechanical Properties of Cell Membranes. ACS NANO 2021; 15:8155-8170. [PMID: 33656312 PMCID: PMC8159881 DOI: 10.1021/acsnano.0c10567] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Interferon-induced transmembrane protein 3 (IFITM3) potently inhibits entry of diverse enveloped viruses by trapping the viral fusion at a hemifusion stage, but the underlying mechanism remains unclear. Here, we show that recombinant IFITM3 reconstituted into lipid vesicles induces negative membrane curvature and that this effect maps to its small amphipathic helix (AH). We demonstrate that AH (i) partitions into lipid-disordered domains where IAV fusion occurs, (ii) induces negative membrane curvature, and (iii) increases lipid order and membrane stiffness. These effects on membrane properties correlate with the fusion-inhibitory activity, as targeting the ectopically expressed AH peptide to the cytoplasmic leaflet of the cell plasma membrane diminishes IAV-cell surface fusion induced by exposure to acidic pH. Our results thus imply that IFITM3 inhibits the transition from hemifusion to full fusion by imposing an unfavorable membrane curvature and increasing the order and stiffness of the cytoplasmic leaflet of endosomal membranes. Our findings reveal a universal mechanism by which cells block entry of diverse enveloped viruses.
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Affiliation(s)
- Xiangyang Guo
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Jan Steinkühler
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Mariana Marin
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, United States
| | - Xiang Li
- School of Pharmacy, Second Military Medical University, Shanghai, 200433, China
| | - Wuyuan Lu
- Institute of Human Virology and Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland 21201, United States
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany
| | - Gregory B. Melikyan
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, United States
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
- Corresponding author: Gregory B. Melikyan,
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31
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Transport mechanisms of SARS-CoV-E viroporin in calcium solutions: Lipid-dependent Anomalous Mole Fraction Effect and regulation of pore conductance. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183590. [PMID: 33621516 PMCID: PMC7896491 DOI: 10.1016/j.bbamem.2021.183590] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/04/2021] [Accepted: 02/06/2021] [Indexed: 02/06/2023]
Abstract
The envelope protein E of the SARS-CoV coronavirus is an archetype of viroporin. It is a small hydrophobic protein displaying ion channel activity that has proven highly relevant in virus-host interaction and virulence. Ion transport through E channel was shown to alter Ca2+ homeostasis in the cell and trigger inflammation processes. Here, we study transport properties of the E viroporin in mixed solutions of potassium and calcium chloride that contain a fixed total concentration (mole fraction experiments). The channel is reconstituted in planar membranes of different lipid compositions, including a lipid mixture that mimics the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) membrane where the virus localizes within the cell. We find that the E ion conductance changes non-monotonically with the total ionic concentration displaying an Anomalous Mole Fraction Effect (AMFE) only when charged lipids are present in the membrane. We also observe that E channel insertion in ERGIC-mimic membranes – including lipid with intrinsic negative curvature – enhances ion permeation at physiological concentrations of pure CaCl2 or KCl solutions, with a preferential transport of Ca2+ in mixed KCl-CaCl2 solutions. Altogether, our findings demonstrate that the presence of calcium modulates the transport properties of the E channel by interacting preferentially with charged lipids through different mechanisms including direct Coulombic interactions and possibly inducing changes in membrane morphology.
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32
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Kostina NY, Wagner AM, Haraszti T, Rahimi K, Xiao Q, Klein ML, Percec V, Rodriguez-Emmenegger C. Unraveling topology-induced shape transformations in dendrimersomes. SOFT MATTER 2021; 17:254-267. [PMID: 32789415 DOI: 10.1039/d0sm01097a] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The vital functions of cell membranes require their ability to quickly change shape to perform complex tasks such as motion, division, endocytosis, and apoptosis. Membrane curvature in cells is modulated by very complex processes such as changes in lipid composition, the oligomerization of curvature-scaffolding proteins, and the reversible insertion of protein regions that act like wedges in the membrane. But, could much simpler mechanisms support membrane shape transformation? In this work, we demonstrate how the change of amphiphile topology in the bilayer can drive shape transformations of cell membrane models. To tackle this, we have designed and synthesized new types of amphiphiles-Janus dendrimers-that self-assemble into uni-, multilamellar, or smectic-ordered vesicles, named dendrimersomes. We synthesized Janus dendrimers containing a photo-labile bond that upon UV-Vis irradiation cleavage lose a part of the hydrophilic dendron. This leads to a change from a cylindrically to a wedge-shaped amphiphile. The high mobility of these dendrimers allows for the concentration of the wedge-shaped amphiphiles and the generation of transmembrane asymmetries. The concentration of the wedges and their rate of segregation allowed control of the budding and generation of structures such as tubules and high genus vesicles.
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Affiliation(s)
- Nina Yu Kostina
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
| | - Anna M Wagner
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
| | - Tamás Haraszti
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
| | - Khosrow Rahimi
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstraße 50, 52074 Aachen, Germany.
| | - Qi Xiao
- Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA and Institute of Computational Molecular Science, Temple University, Philadelphia, PA 19122, USA
| | - Michael L Klein
- Institute of Computational Molecular Science, Temple University, Philadelphia, PA 19122, USA
| | - Virgil Percec
- Roy & Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA
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Bernier SC, Millette MA, Roy S, Cantin L, Coutinho A, Salesse C. Structural information and membrane binding of truncated RGS9-1 Anchor Protein and its C-terminal hydrophobic segment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183566. [PMID: 33453187 DOI: 10.1016/j.bbamem.2021.183566] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/22/2020] [Accepted: 01/10/2021] [Indexed: 01/19/2023]
Abstract
Visual phototransduction takes place in photoreceptor cells. Light absorption by rhodopsin leads to the activation of transducin as a result of the exchange of its GDP for GTP. The GTP-bound ⍺-subunit of transducin then activates phosphodiesterase (PDE), which in turn hydrolyzes cGMP leading to photoreceptor hyperpolarization. Photoreceptors return to the dark state upon inactivation of these proteins. In particular, PDE is inactivated by the protein complex R9AP/RGS9-1/Gβ5. R9AP (RGS9-1 anchor protein) is responsible for the membrane anchoring of this protein complex to photoreceptor outer segment disk membranes most likely by the combined involvement of its C-terminal hydrophobic domain as well as other types of interactions. This study thus aimed to gather information on the structure and membrane binding of the C-terminal hydrophobic segment of R9AP as well as of truncated R9AP (without its C-terminal domain, R9AP∆TM). Circular dichroism and infrared spectroscopic measurements revealed that the secondary structure of R9AP∆TM mainly includes ⍺-helical structural elements. Moreover, intrinsic fluorescence measurements of native R9AP∆TM and individual mutants lacking one tryptophan demonstrated that W79 is more buried than W173 but that they are both located in a hydrophobic environment. This method also revealed that membrane binding of R9AP∆TM does not involve regions near its tryptophan residues, while infrared spectroscopy validated its binding to lipid vesicles. Additional fluorescence measurements showed that the C-terminal segment of R9AP is membrane embedded. Maximum insertion pressure and synergy data using Langmuir monolayers suggest that interactions with specific phospholipids could be involved in the membrane binding of R9AP∆TM.
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Affiliation(s)
- Sarah C Bernier
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Marc-Antoine Millette
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Sarah Roy
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Line Cantin
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada
| | - Ana Coutinho
- iBB-Institute for Bioengineering and Biosciences, Department of Bioengineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal; Department of Chemistry and Biochemistry, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Christian Salesse
- CUO-Recherche, Centre de recherche du CHU de Québec and Département d'ophtalmologie, Faculté de Médecine, and Regroupement Stratégique PROTEO, Université Laval, Québec, Québec, Canada.
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Jiang Y, Idikuda V, Chowdhury S, Chanda B. Activation of the archaeal ion channel MthK is exquisitely regulated by temperature. eLife 2020; 9:e59055. [PMID: 33274718 PMCID: PMC7717905 DOI: 10.7554/elife.59055] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/17/2020] [Indexed: 11/13/2022] Open
Abstract
Physiological response to thermal stimuli in mammals is mediated by a structurally diverse class of ion channels, many of which exhibit polymodal behavior. To probe the diversity of biophysical mechanisms of temperature-sensitivity, we characterized the temperature-dependent activation of MthK, a two transmembrane calcium-activated potassium channel from thermophilic archaebacteria. Our functional complementation studies show that these channels are more efficient at rescuing K+ transport at 37°C than at 24°C. Electrophysiological activity of the purified MthK is extremely sensitive (Q10 >100) to heating particularly at low-calcium concentrations whereas channels lacking the calcium-sensing RCK domain are practically insensitive. By analyzing single-channel activities at limiting calcium concentrations, we find that temperature alters the coupling between the cytoplasmic RCK domains and the pore domain. These findings reveal a hitherto unexplored mechanism of temperature-dependent regulation of ion channel gating and shed light on ancient origins of temperature-sensitivity.
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Affiliation(s)
- Yihao Jiang
- Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
- Center for the Investigation of Membrane Excitability Diseases (CIMED)St. LouisUnited States
| | - Vinay Idikuda
- Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
- Center for the Investigation of Membrane Excitability Diseases (CIMED)St. LouisUnited States
| | - Sandipan Chowdhury
- Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
- Center for the Investigation of Membrane Excitability Diseases (CIMED)St. LouisUnited States
| | - Baron Chanda
- Department of Anesthesiology, Washington University School of MedicineSt. LouisUnited States
- Center for the Investigation of Membrane Excitability Diseases (CIMED)St. LouisUnited States
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Murakami K, Ebihara R, Kono T, Chiba T, Sakuma Y, Ziherl P, Imai M. Morphologies of Vesicle Doublets: Competition among Bending Elasticity, Surface Tension, and Adhesion. Biophys J 2020; 119:1735-1748. [PMID: 33080225 DOI: 10.1016/j.bpj.2020.09.030] [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: 05/15/2020] [Revised: 09/20/2020] [Accepted: 09/25/2020] [Indexed: 11/20/2022] Open
Abstract
To study the mechanical laws governing the form of multicellular organisms, we examine the morphology of adhering vesicle doublets as the simplest model system. We monitor the morphological transformations of doublets induced by changes of adhesion strength and volume/area ratio, which are controlled by intermembrane interactions and thermal area expansion, respectively. When we increase the temperature in the weak adhesion regime, a dumbbell flat-contact doublet is transformed to a parallel-prolate doublet, whereas in the strong adhesion regime, heating transforms the dumbbell flat-contact doublet into a spherical sigmoid-contact doublet. We reproduce the observed doublet morphologies by numerically minimizing the total energy, including the contact-potential adhesion term as well as the surface and bending terms, using the Surface Evolver package. From the reproduced morphologies, we extract the adhesion strength, the surface tension, and the volume/area ratio of the vesicles, which reveals the detailed mechanisms of the morphological transitions in doublets.
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Affiliation(s)
- Kei Murakami
- Department of Physics, Tohoku University, Aoba, Sendai, Japan
| | - Ryuta Ebihara
- Department of Physics, Tohoku University, Aoba, Sendai, Japan
| | - Takuma Kono
- Department of Physics, Tohoku University, Aoba, Sendai, Japan
| | - Toshikaze Chiba
- Department of Physics, Tohoku University, Aoba, Sendai, Japan
| | - Yuka Sakuma
- Department of Physics, Tohoku University, Aoba, Sendai, Japan
| | - Primož Ziherl
- Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia; Jožef Stefan Institute, Ljubljana, Slovenia
| | - Masayuki Imai
- Department of Physics, Tohoku University, Aoba, Sendai, Japan.
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36
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Poyton MF, Pullanchery S, Sun S, Yang T, Cremer PS. Zn 2+ Binds to Phosphatidylserine and Induces Membrane Blebbing. J Am Chem Soc 2020; 142:18679-18686. [PMID: 33078929 DOI: 10.1021/jacs.0c09103] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Herein, we show that Zn2+ binds to phosphatidylserine (PS) lipids in supported lipid bilayers (SLBs), forming a PS-Zn2+ complex with an equilibrium dissociation constant of ∼100 μM. Significantly, Zn2+ binding to SLBs containing more than 10 mol % PS induces extensive reordering of the bilayer. This reordering is manifest through bright spots of high fluorescence intensity that can be observed when the bilayer contains a dye-labeled lipid. Measurements using atomic force microscopy (AFM) reveal that these spots represent three-dimensional unilamellar blebs. Bleb formation is ion specific, inducible by exposing the bilayer to μM concentrations of Zn2+ but not Mg2+, Cu2+, Co2+, or Mn2+. Moreover, Ca2+ can induce some blebbing at mM concentrations but not nearly as effectively as Zn2+. The interactions of divalent metal cations with PS lipids were further investigated by a combination of vibrational sum frequency spectroscopy (VSFS) and surface pressure-area isotherm measurements. VSFS revealed that Zn2+ and Ca2+ were bound to the phosphate and carboxylate moieties on PS via contact ion pairing, dehydrating the lipid headgroup, whereas Mg2+ and Cu2+ were bound without perturbing the hydration of these functional groups. Additionally, Zn2+ was found to dramatically reduce the area per lipid in lipid monolayers, while Mg2+ and Cu2+ did not. Ca2+ could also reduce the area per lipid but only when significantly higher surface pressures were applied. These measurements suggest that Zn2+ caused lipid blebbing by decreasing the area per lipid on the side of the bilayer to which the salt was exposed. Such findings have implications for blebbing, fusion, oxidation, and related properties of PS-rich membranes in biological systems where Zn2+ concentrations are asymmetrically distributed.
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Lamparter L, Galic M. Cellular Membranes, a Versatile Adaptive Composite Material. Front Cell Dev Biol 2020; 8:684. [PMID: 32850810 PMCID: PMC7419611 DOI: 10.3389/fcell.2020.00684] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 07/06/2020] [Indexed: 12/17/2022] Open
Abstract
Cellular membranes belong to the most vital yet least understood biomaterials of live matter. For instance, its biomechanical requirements substantially vary across species and subcellular sites, raising the question how membranes manage to adjust to such dramatic changes. Central to its adaptability at the cell surface is the interplay between the plasma membrane and the adjacent cell cortex, forming an adaptive composite material that dynamically adjusts its mechanical properties. Using a hypothetical composite material, we identify core challenges, and discuss how cellular membranes solved these tasks. We further muse how pathological changes in material properties affect membrane mechanics and cell function, before closing with open questions and future challenges arising when studying cellular membranes.
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Affiliation(s)
- Lucas Lamparter
- Institute of Medical Physics and Biophysics, Faculty of Medicine, University of Münster, Münster, Germany.,Cells in Motion Interfaculty Centre, University of Müenster, Münster, Germany
| | - Milos Galic
- Institute of Medical Physics and Biophysics, Faculty of Medicine, University of Münster, Münster, Germany.,Cells in Motion Interfaculty Centre, University of Müenster, Münster, Germany
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38
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Sahoo A, Matysiak S. Microscopic Picture of Calcium-Assisted Lipid Demixing and Membrane Remodeling Using Multiscale Simulations. J Phys Chem B 2020; 124:7327-7335. [PMID: 32786720 DOI: 10.1021/acs.jpcb.0c03067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The specificity of anionic phospholipids-calcium ion interaction and lipid demixing has been established as a key regulatory mechanism in several cellular signaling processes. The mechanism and implications of this calcium-assisted demixing have not been elucidated from a microscopic point of view. Here, we present an overview of atomic interactions between calcium and phospholipids that can drive nonideal mixing of lipid molecules in a model lipid bilayer composed of zwitterionic (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)) and anionic (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine (POPS)) lipids with computer simulations at multiple resolutions. Lipid nanodomain formation and growth were driven by calcium-enabled lipid bridging of the charged phosphatidylserine (PS) headgroups, which were favored against inter-POPS dipole interactions. Consistent with several experimental studies of calcium-associated membrane sculpting, our analyses also suggest modifications in local membrane curvature and cross-leaflet couplings as a response to such induced lateral heterogeneity. In addition, reverse mapping to a complementary atomistic description revealed structural insights in the presence of anionic nanodomains, at timescales not accessed by previous computational studies. This work bridges information across multiple scales to reveal a mechanistic picture of calcium ion's impact on membrane biophysics.
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Affiliation(s)
- Abhilash Sahoo
- Biophysics Program, Institute of Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States
| | - Silvina Matysiak
- Biophysics Program, Institute of Physical Science and Technology, University of Maryland, College Park, Maryland 20742, United States.,Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
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Pankratenko AV, Atabekova AK, Morozov SY, Solovyev AG. Membrane Contacts in Plasmodesmata: Structural Components and Their Functions. BIOCHEMISTRY (MOSCOW) 2020; 85:531-544. [DOI: 10.1134/s0006297920050028] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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40
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Bradley RP, Slochower DR, Janmey PA, Radhakrishnan R. Divalent cations bind to phosphoinositides to induce ion and isomer specific propensities for nano-cluster initiation in bilayer membranes. ROYAL SOCIETY OPEN SCIENCE 2020; 7:192208. [PMID: 32537210 PMCID: PMC7277276 DOI: 10.1098/rsos.192208] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/14/2020] [Indexed: 05/22/2023]
Abstract
We report all-atom molecular dynamics simulations of asymmetric bilayers containing phosphoinositides in the presence of monovalent and divalent cations. We have characterized the molecular mechanism by which these divalent cations interact with phosphoinositides. Ca2+ desolvates more readily, consistent with single-molecule calculations, and forms a network of ionic-like bonds that serve as a 'molecular glue' that allows a single ion to coordinate with up to three phosphatidylinositol-(4,5)-bisphosphate (PI(4, 5)P2) lipids. The phosphatidylinositol-(3,5)-bisphosphate isomer shows no such effect and neither does PI(4, 5)P2 in the presence of Mg2+. The resulting network of Ca2+-mediated lipid-lipid bonds grows to span the entire simulation space and therefore has implications for the lateral distribution of phosophoinositides in the bilayer. We observe context-specific differences in lipid diffusion rates, lipid surface densities and bilayer structure. The molecular-scale delineation of ion-lipid arrangements reported here provides insight into similar nanocluster formation induced by peripheral proteins to regulate the formation of functional signalling complexes on the membrane.
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Affiliation(s)
- Ryan P. Bradley
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - David R. Slochower
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Paul A. Janmey
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Ravi Radhakrishnan
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
- Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
- Author for correspondence: Ravi Radhakrishnan e-mail:
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Aggregation of Lipid A Variants: A Hybrid Particle-Field Model. Biochim Biophys Acta Gen Subj 2020; 1865:129570. [PMID: 32105775 DOI: 10.1016/j.bbagen.2020.129570] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/10/2020] [Accepted: 02/19/2020] [Indexed: 12/23/2022]
Abstract
Lipid A is one of the three components of bacterial lipopolysaccharides constituting the outer membrane of Gram-negative bacteria, and is recognized to have an important biological role in the inflammatory response of mammalians. Its biological activity is modulated by the number of acyl-chains that are present in the lipid and by the dielectric medium, i.e., the type of counter-ions, through electrostatic interactions. In this paper, we report on a coarse-grained model of chemical variants of Lipid A based on the hybrid particle-field/molecular dynamics approach (hPF-MD). In particular, we investigate the stability of Lipid A bilayers for two different hexa- and tetra-acylated structures. Comparing particle density profiles along bilayer cross-sections, we find good agreement between the hPF-MD model and reference all-atom simulation for both chemical variants of Lipid A. hPF-MD models of constituted bilayers composed by hexa-acylated Lipid A in water are stable within the simulation time. We further validate our model by verifying that the phase behavior of Lipid A/counterion/water mixtures is correctly reproduced. In particular, hPF-MD simulations predict the correct self-assembly of different lamellar and micellar phases from an initially random distribution of Lipid A molecules with counterions in water. Finally, it is possible to observe the spontaneous formation and stability of Lipid A vesicles by fusion of micellar aggregates.
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Miranda ÉGA, Araujo-Chaves JC, Kawai C, Brito AMM, Dias IWR, Arantes JT, Nantes-Cardoso IL. Cardiolipin Structure and Oxidation Are Affected by Ca 2+ at the Interface of Lipid Bilayers. Front Chem 2020; 7:930. [PMID: 32039150 PMCID: PMC6986261 DOI: 10.3389/fchem.2019.00930] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 12/20/2019] [Indexed: 12/13/2022] Open
Abstract
Ca2+-overload contributes to the oxidation of mitochondrial membrane lipids and associated events such as the permeability transition pore (MPTP) opening. Numerous experimental studies about the Ca2+/cardiolipin (CL) interaction are reported in the literature, but there are few studies in conjunction with theoretical approaches based on ab initio calculations. In the present study, the lipid fraction of the inner mitochondrial membrane was modeled as POPC/CL large unilamellar vesicles (LUVs). POPC/CL and, comparatively, POPC, and CL LUVs were challenged by singlet molecular oxygen using the anionic porphyrin TPPS4 as a photosensitizer and by free radicals produced by Fe2+-citrate. Calcium ion favored both types of lipid oxidation in a lipid composition-dependent manner. In membranes containing predominantly or exclusively POPC, Ca2+ increased the oxidation at later reaction times while the oxidation of CL membranes was exacerbated at the early times of reaction. Considering that Ca2+ interaction affects the lipid structure and packing, density functional theory (DFT) calculations were applied to the Ca2+ association with totally and partially protonated and deprotonated CL, in the presence of water. The interaction of totally and partially protonated CL head groups with Ca2+ decreased the intramolecular P-P distance and increased the hydrophobic volume of the acyl chains. Consistently with the theoretically predicted effect of Ca2+ on CL, in the absence of pro-oxidants, giant unilamellar vesicles (GUVs) challenged by Ca2+ formed buds and many internal vesicles. Therefore, Ca2+ induces changes in CL packing and increases the susceptibility of CL to the oxidation promoted by free radicals and excited species.
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Affiliation(s)
- Érica G A Miranda
- Laboratory of Nanostructures for Biology and Advanced Materials, NanoBioMAv, Center of Natural Sciences and Humanities, Federal University of ABC, Santo André, Brazil
| | - Juliana C Araujo-Chaves
- Laboratory of Nanostructures for Biology and Advanced Materials, NanoBioMAv, Center of Natural Sciences and Humanities, Federal University of ABC, Santo André, Brazil
| | - Cintia Kawai
- Laboratory of Nanostructures for Biology and Advanced Materials, NanoBioMAv, Center of Natural Sciences and Humanities, Federal University of ABC, Santo André, Brazil
| | - Adrianne M M Brito
- Laboratory of Nanostructures for Biology and Advanced Materials, NanoBioMAv, Center of Natural Sciences and Humanities, Federal University of ABC, Santo André, Brazil
| | - Igor W R Dias
- Center of Engineering, Modeling, and Applied Social Sciences, Federal University of ABC, Santo André, Brazil
| | - Jeverson T Arantes
- Center of Engineering, Modeling, and Applied Social Sciences, Federal University of ABC, Santo André, Brazil
| | - Iseli L Nantes-Cardoso
- Laboratory of Nanostructures for Biology and Advanced Materials, NanoBioMAv, Center of Natural Sciences and Humanities, Federal University of ABC, Santo André, Brazil
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Petersen EN, Pavel MA, Wang H, Hansen SB. Disruption of palmitate-mediated localization; a shared pathway of force and anesthetic activation of TREK-1 channels. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183091. [PMID: 31672538 PMCID: PMC6907892 DOI: 10.1016/j.bbamem.2019.183091] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/15/2019] [Accepted: 09/17/2019] [Indexed: 12/22/2022]
Abstract
TWIK related K+ channel (TREK-1) is a mechano- and anesthetic sensitive channel that when activated attenuates pain and causes anesthesia. Recently the enzyme phospholipase D2 (PLD2) was shown to bind to the channel and generate a local high concentration of phosphatidic acid (PA), an anionic signaling lipid that gates TREK-1. In a biological membrane, the cell harnesses lipid heterogeneity (lipid compartments) to control gating of TREK-1 using palmitate-mediated localization of PLD2. Here we discuss the ability of mechanical force and anesthetics to disrupt palmitate-mediated localization of PLD2 giving rise to TREK-1's mechano- and anesthetic-sensitive properties. The likely consequences of this indirect lipid-based mechanism of activation are discussed in terms of a putative model for excitatory and inhibitory mechano-effectors and anesthetic sensitive ion channels in a biological context. Lastly, we discuss the ability of locally generated PA to reach mM concentrations near TREK-1 and the biophysics of localized signaling. Palmitate-mediated localization of PLD2 emerges as a central control mechanism of TREK-1 responding to mechanical force and anesthetic action. This article is part of a Special Issue entitled: Molecular biophysics of membranes and membrane proteins.
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Affiliation(s)
- E Nicholas Petersen
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Mahmud Arif Pavel
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Hao Wang
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA
| | - Scott B Hansen
- Department of Molecular Medicine, The Scripps Research Institute, Jupiter, FL 33458, USA; Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
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Kataoka-Hamai C, Kawakami K. Interaction Mechanisms of Giant Unilamellar Vesicles with Hydrophobic Glass Surfaces and Silicone Oil-Water Interfaces: Adsorption, Deformation, Rupture, Dynamic Shape Changes, Internal Vesicle Formation, and Desorption. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:16136-16145. [PMID: 31697503 DOI: 10.1021/acs.langmuir.9b02472] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Phospholipid monolayers at oil-water interfaces are often obtained via vesicle adsorption. However, the interaction mechanisms of vesicles with these oil-water interfaces remain unclear. Herein, we studied the adsorption of giant unilamellar vesicles (GUVs) of approximately 2-5 μm diameter onto silicone oil-water interfaces and glass surfaces modified with hexamethyldisilazane (HMDS) and octadecyltrimethoxysilane (ODTMS) using fluorescence microscopy. The GUVs exhibited various modes of interaction, adsorbing on the silanized glass surfaces without sizable deformation, whereas GUVs bound to the silicone oil-water interface exhibited large deformation. After adsorption, GUV rupture occurred within 350, 110, and 3 ms on HMDS-modified glass, ODTMS-modified glass, and silicone oil-water interface, respectively. On glass surfaces, GUV rupture was often initiated and proceeded with pore formation near the surface. The monolayer patches formed by GUV rupture on HMDS-modified glass remained for at least 1 h over an area approximately twice of that estimated from the original GUV. On the ODTMS-modified glass and silicone oil surfaces, the monolayer patch structures disappeared in milliseconds owing to lipid diffusion across the interface. When adsorbed on the oil-water interface, the GUVs spontaneously underwent dynamic shape changes, internal vesicle formation, and desorption without rupture. Thus, it can be concluded that these different pathways arose from different lipid-surface affinities.
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Affiliation(s)
- Chiho Kataoka-Hamai
- International Center for Materials Nanoarchitectonics (WPI-MANA) , National Institute for Materials Science , 1-1 Namiki , Tsukuba , Ibaraki 305-0044 , Japan
| | - Kohsaku Kawakami
- International Center for Materials Nanoarchitectonics (WPI-MANA) , National Institute for Materials Science , 1-1 Namiki , Tsukuba , Ibaraki 305-0044 , Japan
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45
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Piontek MC, Lira RB, Roos WH. Active probing of the mechanical properties of biological and synthetic vesicles. Biochim Biophys Acta Gen Subj 2019; 1865:129486. [PMID: 31734458 DOI: 10.1016/j.bbagen.2019.129486] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 11/05/2019] [Accepted: 11/09/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND The interest in mechanics of synthetic and biological vesicles has been continuously growing during the last decades. Liposomes serve as model systems for investigating fundamental membrane processes and properties. More recently, extracellular vesicles (EVs) have been investigated mechanically as well. EVs are widely studied in fundamental and applied sciences, but their material properties remained elusive until recently. Elucidating the mechanical properties of vesicles is essential to unveil the mechanisms behind a variety of biological processes, e.g. budding, vesiculation and cellular uptake mechanisms. SCOPE OF REVIEW The importance of mechanobiology for studies of vesicles and membranes is discussed, as well as the different available techniques to probe their mechanical properties. In particular, the mechanics of vesicles and membranes as obtained by nanoindentation, micropipette aspiration, optical tweezers, electrodeformation and electroporation experiments is addressed. MAJOR CONCLUSIONS EVs and liposomes possess an astonishing rich, diverse behavior. To better understand their properties, and for optimization of their applications in nanotechnology, an improved understanding of their mechanical properties is needed. Depending on the size of the vesicles and the specific scientific question, different techniques can be chosen for their mechanical characterization. GENERAL SIGNIFICANCE Understanding the mechanical properties of vesicles is necessary to gain deeper insight in the fundamental biological mechanisms involved in vesicle generation and cellular uptake. This furthermore facilitates technological applications such as using vesicles as targeted drug delivery vehicles. Liposome studies provide insight into fundamental membrane processes and properties, whereas the role and functioning of EVs in biology and medicine are increasingly elucidated.
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Affiliation(s)
- Melissa C Piontek
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
| | - Rafael B Lira
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
| | - Wouter H Roos
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands.
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PIP2 Reshapes Membranes through Asymmetric Desorption. Biophys J 2019; 117:962-974. [PMID: 31445680 DOI: 10.1016/j.bpj.2019.07.047] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2019] [Revised: 07/21/2019] [Accepted: 07/24/2019] [Indexed: 11/24/2022] Open
Abstract
Phosphatidylinositol-4,5-bisphosphate (PIP2) is an important signaling lipid in eukaryotic cell plasma membranes, playing an essential role in diverse cellular processes. The headgroup of PIP2 is highly negatively charged, and this lipid displays a high critical micellar concentration compared to housekeeping phospholipid analogs. Given the crucial role of PIP2, it is imperative to study its localization, interaction with proteins, and membrane-shaping properties. Biomimetic membranes have served extensively to elucidate structural and functional aspects of cell membranes including protein-lipid and lipid-lipid interactions, as well as membrane mechanics. Incorporation of PIP2 into biomimetic membranes, however, has at times resulted in discrepant findings described in the literature. With the goal to elucidate the mechanical consequences of PIP2 incorporation, we studied the desorption of PIP2 from biomimetic giant unilamellar vesicles by means of a fluorescent marker. A decrease in fluorescence intensity with the age of the vesicles suggested that PIP2 lipids were being desorbed from the outer leaflet of the membrane. To evaluate whether this desorption was asymmetric, the vesicles were systematically diluted. This resulted in an increase in the number of internally tubulated vesicles within minutes after dilution, suggesting that the desorption was asymmetric and also generated membrane curvature. By means of a saturated chain homolog of PIP2, we showed that the fast desorption of PIP2 is facilitated by presence of an arachidonic lipid tail and is possibly due to its oxidation. Through measurements of the pulling force of membrane tethers, we quantified the effect of this asymmetric desorption on the spontaneous membrane curvature. Furthermore, we found that the spontaneous curvature could be modulated by externally increasing the concentration of PIP2 micelles. Given that the local concentration of PIP2 in biological membranes is variable, spontaneous curvature generated by PIP2 may affect the formation of highly curved structures that can serve as initiators for signaling events.
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Kolašinac R, Jaksch S, Dreissen G, Braeutigam A, Merkel R, Csiszár A. Influence of Environmental Conditions on the Fusion of Cationic Liposomes with Living Mammalian Cells. NANOMATERIALS 2019; 9:nano9071025. [PMID: 31319557 PMCID: PMC6669649 DOI: 10.3390/nano9071025] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2019] [Revised: 07/12/2019] [Accepted: 07/12/2019] [Indexed: 12/12/2022]
Abstract
Lipid-based nanoparticles, also called vesicles or liposomes, can be used as carriers for drugs or many types of biological macromolecules, including DNA and proteins. Efficiency and speed of cargo delivery are especially high for carrier vesicles that fuse with the cellular plasma membrane. This occurs for lipid mixture containing equal amounts of the cationic lipid DOTAP and a neutral lipid with an additional few percents of an aromatic substance. The fusion ability of such particles depends on lipid composition with phosphoethanolamine (PE) lipids favoring fusion and phosphatidyl-choline (PC) lipids endocytosis. Here, we examined the effects of temperature, ionic strength, osmolality, and pH on fusion efficiency of cationic liposomes with Chinese hamster ovary (CHO) cells. The phase state of liposomes was analyzed by small angle neutron scattering (SANS). Our results showed that PC containing lipid membranes were organized in the lamellar phase. Here, fusion efficiency depended on buffer conditions and remained vanishingly small at physiological conditions. In contrast, SANS indicated the coexistence of very small (~50 nm) objects with larger, most likely lamellar structures for PE containing lipid particles. The fusion of such particles to cell membranes occurred with very high efficiency at all buffer conditions. We hypothesize that the altered phase state resulted in a highly reduced energetic barrier against fusion.
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Affiliation(s)
- Rejhana Kolašinac
- Forschungszentrum Jülich GmbH, Institute of Complex Systems: ICS-7 Biomechanics, 52428 Jülich, Germany
| | - Sebastian Jaksch
- Forschungszentrum Jülich GmbH, Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), 85748 Garching, Germany
| | - Georg Dreissen
- Forschungszentrum Jülich GmbH, Institute of Complex Systems: ICS-7 Biomechanics, 52428 Jülich, Germany
| | - Andrea Braeutigam
- Forschungszentrum Jülich GmbH, Institute of Complex Systems: ICS-2 Theoretical Soft Matter and Biophysics, 52428 Jülich, Germany
| | - Rudolf Merkel
- Forschungszentrum Jülich GmbH, Institute of Complex Systems: ICS-7 Biomechanics, 52428 Jülich, Germany
| | - Agnes Csiszár
- Forschungszentrum Jülich GmbH, Institute of Complex Systems: ICS-7 Biomechanics, 52428 Jülich, Germany.
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Köksal ES, Liese S, Kantarci I, Olsson R, Carlson A, Gözen I. Nanotube-Mediated Path to Protocell Formation. ACS NANO 2019; 13:6867-6878. [PMID: 31177769 DOI: 10.1021/acsnano.9b01646] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cellular compartments are membrane-enclosed, spatially distinct microenvironments that confine and protect biochemical reactions in the biological cell. On the early Earth, the autonomous formation of compartments is thought to have led to the encapsulation of nucleotides, thereby satisfying a starting condition for the emergence of life. Recently, surfaces have come into focus as potential platforms for the self-assembly of prebiotic compartments, as significantly enhanced vesicle formation was reported in the presence of solid interfaces. The detailed mechanism of such formation at the mesoscale is still under discussion. We report here on the spontaneous transformation of solid-surface-adhered lipid deposits to unilamellar membrane compartments through a straightforward sequence of topological changes, proceeding via a network of interconnected lipid nanotubes. We show that this transformation is entirely driven by surface-free energy minimization and does not require hydrolysis of organic molecules or external stimuli such as electrical currents or mechanical agitation. The vesicular structures take up and encapsulate their external environment during formation and can subsequently separate and migrate upon exposure to hydrodynamic flow. This may link the self-directed transition from weakly organized bioamphiphile assemblies on solid surfaces to protocells with secluded internal contents.
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Affiliation(s)
- Elif S Köksal
- Centre for Molecular Medicine Norway, Faculty of Medicine , University of Oslo , 0318 Oslo , Norway
| | - Susanne Liese
- Department of Chemistry, Faculty of Mathematics and Natural Sciences , University of Oslo , 0315 Oslo , Norway
| | - Ilayda Kantarci
- Centre for Molecular Medicine Norway, Faculty of Medicine , University of Oslo , 0318 Oslo , Norway
| | - Ragni Olsson
- Centre for Molecular Medicine Norway, Faculty of Medicine , University of Oslo , 0318 Oslo , Norway
| | - Andreas Carlson
- Department of Chemistry, Faculty of Mathematics and Natural Sciences , University of Oslo , 0315 Oslo , Norway
| | - Irep Gözen
- Centre for Molecular Medicine Norway, Faculty of Medicine , University of Oslo , 0318 Oslo , Norway
- Department of Mathematics, Faculty of Mathematics and Natural Sciences , University of Oslo , 0315 Oslo , Norway
- Department of Chemistry and Chemical Engineering , Chalmers University of Technology , SE-412 96 Göteborg , Sweden
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Dimova R. Giant Vesicles and Their Use in Assays for Assessing Membrane Phase State, Curvature, Mechanics, and Electrical Properties. Annu Rev Biophys 2019; 48:93-119. [DOI: 10.1146/annurev-biophys-052118-115342] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Giant unilamellar vesicles represent a promising and extremely useful model biomembrane system for systematic measurements of mechanical, thermodynamic, electrical, and rheological properties of lipid bilayers as a function of membrane composition, surrounding media, and temperature. The most important advantage of giant vesicles over other model membrane systems is that the membrane responses to external factors such as ions, (macro)molecules, hydrodynamic flows, or electromagnetic fields can be directly observed under the microscope. Here, we briefly review approaches for giant vesicle preparation and describe several assays used for deducing the membrane phase state and measuring a number of material properties, with further emphasis on membrane reshaping and curvature.
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Affiliation(s)
- Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Science Park Golm, 14424 Potsdam, Germany
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50
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Han Y, Lin H, Ding M, Li R, Shi T. Flow-induced translocation of vesicles through a narrow pore. SOFT MATTER 2019; 15:3307-3314. [PMID: 30892355 DOI: 10.1039/c9sm00116f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We use finite element method to investigate the flow-induced translocation of vesicles through a narrow pore from a dynamic point of view. In order to complete the coupling between fluid flow and the vesicle membranes, we employ the fluid-structure interactions with the arbitrary Lagrangian-Eulerian method. Our results demonstrate that the vesicle shows similar shape change from bullet-like to dumbbell-like, dumbbell-like to bulb-like, and bulb-like to parachute-like if it is pushed by flow field to pass through a narrow pore smaller than its size. We further find that the strain energy exhibits a higher peak and a lower peak in the whole translocation process, where the higher peak corresponds to the dumbbell-like shape and the lower peak corresponds to the parachute-like shape due to more stretching of the membrane for the dumbbell-like shape than that of the parachute-like shape. The translocation time of the vesicle from one side to the other side of the narrow pore decreases with the increase of inlet velocity, but the strain energy exhibits an increase, which implies that the vesicle needs more time to complete the translocation with the lower inlet velocity, but the requirement for the mechanical properties of the membrane is lower. Our work answers the mapping between the positions of the vesicles and deformed states with the stress distribution and change of strain energy, which can provide helpful information on the utilization of vesicles in pharmaceutical, chemical, and physiological processes.
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Affiliation(s)
- Yunlong Han
- State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China.
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