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 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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Spencer RKW, Smirnova YG, Soleimani A, Müller M. Transient pores in hemifusion diaphragms. Biophys J 2024:S0006-3495(24)00392-8. [PMID: 38867448 DOI: 10.1016/j.bpj.2024.06.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 05/07/2024] [Accepted: 06/07/2024] [Indexed: 06/14/2024] Open
Abstract
Exchange of material across two membranes, as in the case of synaptic neurotransmitter release from a vesicle, involves the formation and poration of a hemifusion diaphragm (HD). The nontrivial geometry of the HD leads to environment-dependent control, regarding the stability and dynamics of the pores required for this kind of exocytosis. This work combines particle simulations, field-based calculations, and phenomenological modeling to explore the factors influencing the stability, dynamics, and possible control mechanisms of pores in HDs. We find that pores preferentially form at the HD rim, and that their stability is sensitive to a number of factors, including the three line tensions, membrane tension, HD size, and the ability of lipids to "flip-flop" across leaflets. Along with a detailed analysis of these factors, we discuss ways that vesicles or cells may use them to open and close pores and thereby quickly and efficiently transport material.
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Affiliation(s)
- Russell K W Spencer
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany.
| | - Yuliya G Smirnova
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany; Technische Universität Dortmund, Dortmund, Germany
| | - Alireza Soleimani
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany
| | - Marcus Müller
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany.
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3
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Spencer RKW, Santos-Pérez I, Rodríguez-Renovales I, Martinez Galvez JM, Shnyrova AV, Müller M. Membrane fission via transmembrane contact. Nat Commun 2024; 15:2793. [PMID: 38555357 PMCID: PMC10981662 DOI: 10.1038/s41467-024-47122-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 03/20/2024] [Indexed: 04/02/2024] Open
Abstract
Division of intracellular organelles often correlates with additional membrane wrapping, e.g., by the endoplasmic reticulum or the outer mitochondrial membrane. Such wrapping plays a vital role in proteome and lipidome organization. However, how an extra membrane impacts the mechanics of the division has not been investigated. Here we combine fluorescence and cryo-electron microscopy experiments with self-consistent field theory to explore the stress-induced instabilities imposed by membrane wrapping in a simple double-membrane tubular system. We find that, at physiologically relevant conditions, the outer membrane facilitates an alternative pathway for the inner-tube fission through the formation of a transient contact (hemi-fusion) between both membranes. A detailed molecular theory of the fission pathways in the double membrane system reveals the topological complexity of the process, resulting both in leaky and leakless intermediates, with energies and topologies predicting physiological events.
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Affiliation(s)
- Russell K W Spencer
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany.
| | - Isaac Santos-Pérez
- Electron Microscopy and Crystallography Platform, Center for Cooperative Research in Biosciences (CIC bioGUNE), Derio, Spain
| | - Izaro Rodríguez-Renovales
- BREM Basque Resource for Electron Microscopy, Leioa, Spain
- Instituto Biofisika (CSIC, UPV/EHU), Barrio Sarriena, Leioa, Spain
| | - Juan Manuel Martinez Galvez
- Instituto Biofisika (CSIC, UPV/EHU), Barrio Sarriena, Leioa, Spain
- Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain
| | - Anna V Shnyrova
- Instituto Biofisika (CSIC, UPV/EHU), Barrio Sarriena, Leioa, Spain.
- Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain.
| | - Marcus Müller
- Institute for Theoretical Physics, Georg-August University, Göttingen, Germany.
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4
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Di Bartolo AL, Caparotta M, Polo LM, Masone D. Myomerger Induces Membrane Hemifusion and Regulates Fusion Pore Expansion. Biochemistry 2024; 63:815-826. [PMID: 38349279 DOI: 10.1021/acs.biochem.3c00682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Membrane fusion is a crucial mechanism in a wide variety of important events in cell biology from viral infection to exocytosis. However, despite many efforts and much progress, cell-cell fusion has remained elusive to our understanding. Along the life of the fusion pore, large conformational changes take place from the initial lipid bilayer bending, passing through the hemifusion intermediates, and ending with the formation of the first nascent fusion pore. In this sense, computer simulations are an ideal technique for describing such complex lipid remodeling at the molecular level. In this work, we studied the role played by the muscle-specific membrane protein Myomerger during the formation of the fusion pore. We have conducted μs length atomistic and coarse-grained molecular dynamics, together with free-energy calculations using ad hoc collective variables. Our results show that Myomerger favors the hemifusion diaphragm-stalk transition, reduces the nucleation-expansion energy difference, and promotes the formation of nonenlarging fusion pores.
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Affiliation(s)
- Ary Lautaro Di Bartolo
- Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo (UNCuyo), 5500 Mendoza, Argentina
| | - Marcelo Caparotta
- Quantum Theory Project, Department of Chemistry, University of Florida, Gainesville, Florida 32611, United States
| | - Luis Mariano Polo
- Instituto de Histología y Embriología de Mendoza (IHEM)─Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
| | - Diego Masone
- Instituto de Histología y Embriología de Mendoza (IHEM)─Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
- Facultad de Ingeniería, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
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5
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Lira RB, Hammond JCF, Cavalcanti RRM, Rous M, Riske KA, Roos WH. The underlying mechanical properties of membranes tune their ability to fuse. J Biol Chem 2023; 299:105430. [PMID: 37926280 PMCID: PMC10716014 DOI: 10.1016/j.jbc.2023.105430] [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: 08/10/2023] [Revised: 10/16/2023] [Accepted: 10/23/2023] [Indexed: 11/07/2023] Open
Abstract
Membrane fusion is a ubiquitous process associated with a multitude of biological events. Although it has long been appreciated that membrane mechanics plays an important role in membrane fusion, the molecular interplay between mechanics and fusion has remained elusive. For example, although different lipids modulate membrane mechanics differently, depending on their composition, molar ratio, and complex interactions, differing lipid compositions may lead to similar mechanical properties. This raises the question of whether (i) the specific lipid composition or (ii) the average mesoscale mechanics of membranes acts as the determining factor for cellular function. Furthermore, little is known about the potential consequences of fusion on membrane disruption. Here, we use a combination of confocal microscopy, time-resolved imaging, and electroporation to shed light onto the underlying mechanical properties of membranes that regulate membrane fusion. Fusion efficiency follows a nearly universal behavior that depends on membrane fluidity parameters, such as membrane viscosity and bending rigidity, rather than on specific lipid composition. This helps explaining why the charged and fluid membranes of the inner leaflet of the plasma membrane are more fusogenic than their outer counterparts. Importantly, we show that physiological levels of cholesterol, a key component of biological membranes, has a mild effect on fusion but significantly enhances membrane mechanical stability against pore formation, suggesting that its high cellular levels buffer the membrane against disruption. The ability of membranes to efficiently fuse while preserving their integrity may have given evolutionary advantages to cells by enabling their function while preserving membrane stability.
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Affiliation(s)
- Rafael B Lira
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Groningen, Netherlands.
| | - Jayna C F Hammond
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Groningen, Netherlands
| | | | - Madelief Rous
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Groningen, Netherlands
| | - Karin A Riske
- Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Wouter H Roos
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Groningen, Netherlands.
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6
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Tror S, Jeon S, Nguyen HT, Huh E, Shin K. A Self-Regenerating Artificial Cell, that is One Step Closer to Living Cells: Challenges and Perspectives. SMALL METHODS 2023; 7:e2300182. [PMID: 37246263 DOI: 10.1002/smtd.202300182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 04/29/2023] [Indexed: 05/30/2023]
Abstract
Controllable, self-regenerating artificial cells (SRACs) can be a vital advancement in the field of synthetic biology, which seeks to create living cells by recombining various biological molecules in the lab. This represents, more importantly, the first step on a long journey toward creating reproductive cells from rather fragmentary biochemical mimics. However, it is still a difficult task to replicate the complex processes involved in cell regeneration, such as genetic material replication and cell membrane division, in artificially created spaces. This review highlights recent advances in the field of controllable, SRACs and the strategies to achieve the goal of creating such cells. Self-regenerating cells start by replicating DNA and transferring it to a location where proteins can be synthesized. Functional but essential proteins must be synthesized for sustained energy generation and survival needs and function in the same liposomal space. Finally, self-division and repeated cycling lead to autonomous, self-regenerating cells. The pursuit of controllable, SRACs will enable authors to make bold advances in understanding life at the cellular level, ultimately providing an opportunity to use this knowledge to understand the nature of life.
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Affiliation(s)
- Seangly Tror
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul, 04107, Republic of Korea
| | - SeonMin Jeon
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul, 04107, Republic of Korea
| | - Huong Thanh Nguyen
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul, 04107, Republic of Korea
| | - Eunjin Huh
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul, 04107, Republic of Korea
| | - Kwanwoo Shin
- Department of Chemistry and Institute of Biological Interfaces, Sogang University, Seoul, 04107, Republic of Korea
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7
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Fan Z, Deckel Y, Lowe LA, Loo DWK, Yomo T, Szostak JW, Nisler C, Wang A. Lipid Exchange Promotes Fusion of Model Protocells. SMALL METHODS 2023; 7:e2300126. [PMID: 37246261 DOI: 10.1002/smtd.202300126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/29/2023] [Indexed: 05/30/2023]
Abstract
Vesicle fusion is an important process underlying cell division, transport, and membrane trafficking. In phospholipid systems, a range of fusogens including divalent cations and depletants have been shown to induce adhesion, hemifusion, and then full content fusion between vesicles. This work shows that these fusogens do not perform the same function for fatty acid vesicles, which are used as model protocells (primitive cells). Even when fatty acid vesicles appear adhered or hemifused to each other, the intervening barriers between vesicles do not rupture. This difference is likely because fatty acids have a single aliphatic tail, and are more dynamic than their phospholipid counterparts. To address this, it is postulated that fusion could instead occur under conditions, such as lipid exchange, that disrupt lipid packing. Using both experiments and molecular dynamics simulations, it is verified that fusion in fatty acid systems can indeed be induced by lipid exchange. These results begin to probe how membrane biophysics could constrain the evolutionary dynamics of protocells.
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Affiliation(s)
- Ziyan Fan
- School of Chemistry, Australian Centre for Astrobiology, ARC Centre of Excellence in Synthetic Biology, UNSW RNA Institute, UNSW Sydney, NSW 2052, Australia
| | - Yaam Deckel
- School of Chemistry, Australian Centre for Astrobiology, ARC Centre of Excellence in Synthetic Biology, UNSW RNA Institute, UNSW Sydney, NSW 2052, Australia
| | - Lauren A Lowe
- School of Chemistry, Australian Centre for Astrobiology, ARC Centre of Excellence in Synthetic Biology, UNSW RNA Institute, UNSW Sydney, NSW 2052, Australia
| | - Daniel W K Loo
- School of Chemistry, Australian Centre for Astrobiology, ARC Centre of Excellence in Synthetic Biology, UNSW RNA Institute, UNSW Sydney, NSW 2052, Australia
| | - Tetsuya Yomo
- Laboratory of Biology and Information Science, School of Life Sciences, East China Normal University, Shanghai, 200062, P. R. China
| | - Jack W Szostak
- Howard Hughes Medical Institute, and Department of Chemistry, The University of Chicago, Chicago, IL, 60637, USA
| | - Collin Nisler
- Howard Hughes Medical Institute, and Department of Chemistry, The University of Chicago, Chicago, IL, 60637, USA
| | - Anna Wang
- School of Chemistry, Australian Centre for Astrobiology, ARC Centre of Excellence in Synthetic Biology, UNSW RNA Institute, UNSW Sydney, NSW 2052, Australia
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8
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Shendrik P, Golani G, Dharan R, Schwarz US, Sorkin R. Membrane Tension Inhibits Lipid Mixing by Increasing the Hemifusion Stalk Energy. ACS NANO 2023; 17:18942-18951. [PMID: 37669531 PMCID: PMC7615193 DOI: 10.1021/acsnano.3c04293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Accepted: 08/23/2023] [Indexed: 09/07/2023]
Abstract
Fusion of biological membranes is fundamental in various physiological events. The fusion process involves several intermediate stages with energy barriers that are tightly dependent on the mechanical and physical properties of the system, one of which is membrane tension. As previously established, the late stages of fusion, including hemifusion diaphragm and pore expansions, are favored by membrane tension. However, a current understanding of how the energy barrier of earlier fusion stages is affected by membrane tension is lacking. Here, we apply a newly developed experimental approach combining micropipette-aspirated giant unilamellar vesicles and optically trapped membrane-coated beads, revealing that membrane tension inhibits lipid mixing. We show that lipid mixing is 6 times slower under a tension of 0.12 mN/m compared with tension-free membranes. Furthermore, using continuum elastic theory, we calculate the dependence of the hemifusion stalk formation energy on membrane tension and intermembrane distance and find the increase in the corresponding energy barrier to be 1.6 kBT in our setting, which can explain the increase in lipid mixing time delay. Finally, we show that tension can be a significant factor in the stalk energy if the pre-fusion intermembrane distance is on the order of several nanometers, while for membranes that are tightly docked, tension has a negligible effect.
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Affiliation(s)
- Petr Shendrik
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Gonen Golani
- Institute
for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, 69120, Heidelberg, Germany
| | - Raviv Dharan
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
| | - Ulrich S. Schwarz
- Institute
for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, 69120, Heidelberg, Germany
| | - Raya Sorkin
- School
of Chemistry, Raymond & Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv, 6997801, Israel
- Center
of Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv, 6997801, Israel
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9
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Mishra S, Chakraborty H. Phosphatidylethanolamine and Cholesterol Promote Hemifusion Formation: A Tug of War between Membrane Interfacial Order and Intrinsic Negative Curvature of Lipids. J Phys Chem B 2023; 127:7721-7729. [PMID: 37644708 DOI: 10.1021/acs.jpcb.3c04489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Membrane fusion is an important process for the survival of eukaryotes. The shape of lipids plays an important role in fusion by stabilizing nonlamellar fusion intermediates. Lipids with intrinsic positive curvature such as lysophosphatidylcholine and others inhibit hemifusion formation, whereas lipids having intrinsic negative curvature, e.g., phosphatidylethanolamine and cholesterol (CH), are known to promote hemifusion formation. In this work, we have measured the effect of dioleoylphosphatidylethanolamine (DOPE) and CH on the depth-dependent organization, dynamics, and fusion of dioleoylphosphatidylcholine membranes. Both DOPE and CH promote hemifusion formation despite their ability to order the interfacial and acyl chain region of the membrane and block water percolation at these regions. Generally, membrane ordering and inhibition of water percolation at the acyl chain region are detrimental to membrane fusion. This clearly emphasizes the importance of intrinsic negative curvature of lipids in membrane fusion. Interestingly, DOPE and CH show differential effects on the rate of hemifusion formation, which might be owing to their ability to induce order at the interfacial region and intrinsic negative curvature. Overall, our result is significant in understanding the role of lipidic shape in membrane fusion.
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Affiliation(s)
- Smruti Mishra
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla 768 019, Odisha, India
| | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla 768 019, Odisha, India
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10
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Tian X, Risgaard NA, Löffler PMG, Vogel S. DNA-Programmed Lipid Nanoreactors for Synthesis of Carbohydrate Mimetics by Fusion of Aqueous Sub-attoliter Compartments. J Am Chem Soc 2023; 145:19633-19641. [PMID: 37619973 PMCID: PMC10510321 DOI: 10.1021/jacs.3c04093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Indexed: 08/26/2023]
Abstract
Lipid nanoreactors are biomimetic reaction vessels (nanoreactors) that can host aqueous or membrane-associated chemical and enzymatic reactions. Nanoreactors provide ultra-miniaturization from atto- to zeptoliter volumes per reaction vessel with the major challenge of encoding and spatio-temporal control over reactions at the individual nanoreactor or population level, thereby controlling volumes several orders of magnitude below advanced microfluidic devices. We present DNA-programmed lipid nanoreactors (PLNs) functionalized with lipidated oligonucleotides (LiNAs) that allow programming and encoding of nanoreactor interactions by controlled membrane fusion, exemplified for a set of carbohydrate mimetics with mono- to hexasaccharide azide building blocks connected by click-chemistry. Programmed reactions are initiated by fusion of distinct populations of nanoreactors with individually encapsulated building blocks. A focused library of triazole-linked carbohydrate-Cy5 conjugates formed by strain-promoted azide-alkyne cycloadditions demonstrated LiNA-programmed chemistry, including two-step reaction schemes. The PLN method is developed toward a robust platform for synthesis in confined space employing fully programmable nanoreactors, applicable to multistep synthesis for the generation of combinatorial libraries with subsequent analysis of the molecules formed, based on the addressability of the lipid nanoreactors.
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Affiliation(s)
- Xinwei Tian
- Department of Physics, Chemistry
and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Nikolaj Alexander Risgaard
- Department of Physics, Chemistry
and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Philipp M. G. Löffler
- Department of Physics, Chemistry
and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
| | - Stefan Vogel
- Department of Physics, Chemistry
and Pharmacy, University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark
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11
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Golani G, Schwarz US. High curvature promotes fusion of lipid membranes: Predictions from continuum elastic theory. Biophys J 2023; 122:1868-1882. [PMID: 37077047 PMCID: PMC10209146 DOI: 10.1016/j.bpj.2023.04.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/19/2023] [Accepted: 04/14/2023] [Indexed: 04/21/2023] Open
Abstract
The fusion of lipid membranes progresses through a series of hemifusion intermediates with two significant energy barriers related to the formation of stalk and fusion pore, respectively. These energy barriers determine the speed and success rate of many critical biological processes, including the fusion of highly curved membranes, for example synaptic vesicles and enveloped viruses. Here we use continuum elastic theory of lipid monolayers to determine the relationship between membrane shape and energy barriers to fusion. We find that the stalk formation energy decreases with curvature by up to 31 kBT in a 20-nm-radius vesicle compared with planar membranes and by up to 8 kBT in the fusion of highly curved, long, tubular membranes. In contrast, the fusion pore formation energy barrier shows a more complicated behavior. Immediately after stalk expansion to the hemifusion diaphragm, the fusion pore formation energy barrier is low (15-25 kBT) due to lipid stretching in the distal monolayers and increased tension in highly curved vesicles. Therefore, the opening of the fusion pore is faster. However, these stresses relax over time due to lipid flip-flop from the proximal monolayer, resulting in a larger hemifusion diaphragm and a higher fusion pore formation energy barrier, up to 35 kBT. Therefore, if the fusion pore fails to open before significant lipid flip-flop takes place, the reaction proceeds to an extended hemifusion diaphragm state, which is a dead-end configuration in the fusion process and can be used to prevent viral infections. In contrast, in the fusion of long tubular compartments, the surface tension does not accumulate due to the formation of the diaphragm, and the energy barrier for pore expansion increases with curvature by up to 11 kBT. This suggests that inhibition of polymorphic virus infection could particularly target this feature of the second barrier.
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Affiliation(s)
- Gonen Golani
- Institute for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - Ulrich S Schwarz
- Institute for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany.
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12
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Winter SL, Golani G, Lolicato F, Vallbracht M, Thiyagarajah K, Ahmed SS, Lüchtenborg C, Fackler OT, Brügger B, Hoenen T, Nickel W, Schwarz US, Chlanda P. The Ebola virus VP40 matrix layer undergoes endosomal disassembly essential for membrane fusion. EMBO J 2023:e113578. [PMID: 37082863 DOI: 10.15252/embj.2023113578] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2023] [Revised: 03/09/2023] [Accepted: 03/22/2023] [Indexed: 04/22/2023] Open
Abstract
Ebola viruses (EBOVs) assemble into filamentous virions, whose shape and stability are determined by the matrix viral protein 40 (VP40). Virus entry into host cells occurs via membrane fusion in late endosomes; however, the mechanism of how the remarkably long virions undergo uncoating, including virion disassembly and nucleocapsid release into the cytosol, remains unknown. Here, we investigate the structural architecture of EBOVs entering host cells and discover that the VP40 matrix disassembles prior to membrane fusion. We reveal that VP40 disassembly is caused by the weakening of VP40-lipid interactions driven by low endosomal pH that equilibrates passively across the viral envelope without a dedicated ion channel. We further show that viral membrane fusion depends on VP40 matrix integrity, and its disassembly reduces the energy barrier for fusion stalk formation. Thus, pH-driven structural remodeling of the VP40 matrix acts as a molecular switch coupling viral matrix uncoating to membrane fusion during EBOV entry.
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Affiliation(s)
- Sophie L Winter
- Schaller Research Groups, Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
- BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - Gonen Golani
- BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
- Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany
| | - Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg, Germany
- Department of Physics, University of Helsinki, Helsinki, Finland
| | - Melina Vallbracht
- Schaller Research Groups, Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
- BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - Keerthihan Thiyagarajah
- Schaller Research Groups, Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
- BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - Samy Sid Ahmed
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Heidelberg, Germany
| | | | - Oliver T Fackler
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Heidelberg, Germany
- German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany
| | - Britta Brügger
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Thomas Hoenen
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Insitut, Greifswald-Insel Riems, Greifswald, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg, Germany
| | - Ulrich S Schwarz
- BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
- Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany
| | - Petr Chlanda
- Schaller Research Groups, Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
- BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
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13
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Klein S, Golani G, Lolicato F, Lahr C, Beyer D, Herrmann A, Wachsmuth-Melm M, Reddmann N, Brecht R, Hosseinzadeh M, Kolovou A, Makroczyova J, Peterl S, Schorb M, Schwab Y, Brügger B, Nickel W, Schwarz US, Chlanda P. IFITM3 blocks influenza virus entry by sorting lipids and stabilizing hemifusion. Cell Host Microbe 2023; 31:616-633.e20. [PMID: 37003257 DOI: 10.1016/j.chom.2023.03.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 11/15/2022] [Accepted: 03/06/2023] [Indexed: 04/03/2023]
Abstract
Interferon-induced transmembrane protein 3 (IFITM3) inhibits the entry of numerous viruses through undefined molecular mechanisms. IFITM3 localizes in the endosomal-lysosomal system and specifically affects virus fusion with target cell membranes. We found that IFITM3 induces local lipid sorting, resulting in an increased concentration of lipids disfavoring viral fusion at the hemifusion site. This increases the energy barrier for fusion pore formation and the hemifusion dwell time, promoting viral degradation in lysosomes. In situ cryo-electron tomography captured IFITM3-mediated arrest of influenza A virus membrane fusion. Observation of hemifusion diaphragms between viral particles and late endosomal membranes confirmed hemifusion stabilization as a molecular mechanism of IFITM3. The presence of the influenza fusion protein hemagglutinin in post-fusion conformation close to hemifusion sites further indicated that IFITM3 does not interfere with the viral fusion machinery. Collectively, these findings show that IFITM3 induces lipid sorting to stabilize hemifusion and prevent virus entry into target cells.
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Affiliation(s)
- Steffen Klein
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Gonen Golani
- BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany; Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany
| | - Fabio Lolicato
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany; Department of Physics, University of Helsinki, Helsinki, Finland
| | - Carmen Lahr
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Daniel Beyer
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany
| | - Alexia Herrmann
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany
| | - Moritz Wachsmuth-Melm
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Nina Reddmann
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Romy Brecht
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Mehdi Hosseinzadeh
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Androniki Kolovou
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Jana Makroczyova
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Sarah Peterl
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany
| | - Martin Schorb
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Yannick Schwab
- Electron Microscopy Core Facility, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Britta Brügger
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany
| | - Walter Nickel
- Heidelberg University Biochemistry Center, Heidelberg University, 69120 Heidelberg, Germany
| | - Ulrich S Schwarz
- BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany; Institute for Theoretical Physics, Heidelberg University, 69120 Heidelberg, Germany
| | - Petr Chlanda
- Schaller Research Group, Department of Infectious Diseases, Virology, Heidelberg University Hospital, 69120 Heidelberg, Germany; BioQuant Center for Quantitative Biology, Heidelberg University, 69120 Heidelberg, Germany.
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14
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Joardar A, Chakraborty H. Differential Behavior of Eicosapentaenoic and Docosahexaenoic Acids on the Organization, Dynamics, and Fusion of Homogeneous and Heterogeneous Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:4439-4449. [PMID: 36931902 DOI: 10.1021/acs.langmuir.3c00119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Membrane fusion is a common course in innumerable biological processes that helps in the survival of eukaryotes. Enveloped viruses utilize this process to enter the host cells. Generally, the membrane lipid compositions play an important role in membrane fusion by modulating the membrane's physical properties and the behavior of membrane proteins in the cellular milieu. In this work, we have demonstrated the role of polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids, on the organization, dynamics, and fusion of homogeneous and heterogeneous membranes. We have exploited arrays of steady-state and time-resolved fluorescence spectroscopic methods and polyethylene glycol-induced membrane fusion assay to elucidate the behavior of EPA and DHA on dioleoyl phosphatidylcholine (DOPC)/cholesterol (CH) homogeneous and DOPC/sphingomyelin/CH heterogeneous membranes. Our results suggest that EPA and DHA display differential effects on two different membranes. The effects of PUFAs in homogeneous membranes are majorly attributed to their flexible chain dynamics, whereas the ability of PUFA-induced cholesterol transfer from the lo to the ld phase rules their behavior in heterogeneous membranes. Overall, our results provide detailed information on the effect of PUFAs on homogeneous and heterogeneous membranes.
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Affiliation(s)
- Ankita Joardar
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India
| | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India
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15
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van Tilburg M, Hilbers PAJ, Markvoort AJ. On the role of membrane embedding, protein rigidity and transmembrane length in lipid membrane fusion. SOFT MATTER 2023; 19:1791-1802. [PMID: 36786821 DOI: 10.1039/d2sm01582j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The fusion of biological membranes is ubiquitous in natural processes like exo- and endocytosis, intracellular trafficking and viral entry. Membrane fusion is also utilized in artificial biomimetic fusion systems, e.g. for drug delivery. Both the natural and the biomimetic fusion systems rely on a wide range of (artificial) proteins mediating the fusion process. Although the exact mechanisms of these proteins differ, clear analogies in their general behavior can be observed in bringing the membranes in close proximity and mediating the fusion reaction. In our study, we use molecular dynamics simulations with coarse grained models, mimicking the general behavior of fusion proteins (spikes), to systematically examine the effects of specific characteristics of these proteins on the fusion process. The protein characteristics considered are (i) the type of membrane embedding, i.e., either transmembrane or not, (ii) the rigidity, and (iii) the transmembrane domain (TMD) length. The results show essential differences in fusion pathway between monotopic and transmembrane spikes, in which transmembrane spikes seem to inhibit the formation of hemifusion diaphragms, leading to a faster fusion development. Furthermore, we observed that an increased rigidity and a decreased TMD length both proved to contribute to a faster fusion development. Finally, we show that a single spike may suffice to successfully induce a fusion reaction, provided that the spike is sufficiently rigid and attractive. Not only does this shed light on biological fusion of membranes, it also provides clear design rules for artificial membrane fusion systems.
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Affiliation(s)
- Marco van Tilburg
- Department of Biomedical Engineering, Computational Biology Group, Eindhoven University of Technology, The Netherlands.
| | - Peter A J Hilbers
- Department of Biomedical Engineering, Computational Biology Group, Eindhoven University of Technology, The Netherlands.
- Institute of Complex Molecular Systems, Eindhoven University of Technology, The Netherlands
| | - Albert J Markvoort
- Department of Biomedical Engineering, Computational Biology Group, Eindhoven University of Technology, The Netherlands.
- Institute of Complex Molecular Systems, Eindhoven University of Technology, The Netherlands
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16
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Potential of siRNA-Bearing Subtilosomes in the Treatment of Diethylnitrosamine-Induced Hepatocellular Carcinoma. Molecules 2023; 28:molecules28052191. [PMID: 36903437 PMCID: PMC10004640 DOI: 10.3390/molecules28052191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 02/10/2023] [Accepted: 02/15/2023] [Indexed: 03/02/2023] Open
Abstract
Therapeutics, based on small interfering RNA (siRNA), have demonstrated tremendous potential for treating cancer. However, issues such as non-specific targeting, premature degradation, and the intrinsic toxicity of the siRNA, have to be solved before they are ready for use in translational medicines. To address these challenges, nanotechnology-based tools might help to shield siRNA and ensure its specific delivery to the target site. Besides playing a crucial role in prostaglandin synthesis, the cyclo-oxygenase-2 (COX-2) enzyme has been reported to mediate carcinogenesis in various types of cancer, including hepatocellular carcinoma (HCC). We encapsulated COX-2-specific siRNA in Bacillus subtilis membrane lipid-based liposomes (subtilosomes) and evaluated their potential in the treatment of diethylnitrosamine (DEN)-induced hepatocellular carcinoma. Our findings suggested that the subtilosome-based formulation was stable, releasing COX-2 siRNA in a sustained manner, and has the potential to abruptly release encapsulated material at acidic pH. The fusogenic property of subtilosomes was revealed by FRET, fluorescence dequenching, content-mixing assay, etc. The subtilosome-based siRNA formulation was successful in inhibiting TNF-α expression in the experimental animals. The apoptosis study indicated that the subtilosomized siRNA inhibits DEN-induced carcinogenesis more effectively than free siRNA. The as-developed formulation also suppressed COX-2 expression, which in turn up-regulated the expression of wild-type p53 and Bax on one hand and down-regulated Bcl-2 expression on the other. The survival data established the increased efficacy of subtilosome-encapsulated COX-2 siRNA against hepatocellular carcinoma.
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17
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Joardar A, Pandia S, Chakraborty H. Effect of polyunsaturated free fatty acids on the membrane fusion mechanism. SOFT MATTER 2023; 19:733-742. [PMID: 36617878 DOI: 10.1039/d2sm01474b] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Membrane fusion is one of the important processes for the survival of eukaryotic cells and the entry of enveloped viruses into the host cells. Lipid composition plays a crucial role by modulating the organization and dynamics of the membrane, as well as the structure and conformation of membrane proteins. The diversity of the lipid acyl chain in its length and degree of unsaturation originates from the variation in free fatty acids (FFAs). We have studied the effect of linoleic (LA) and alpha-linolenic (ALA) acids on the depth-dependent organization, dynamics, and fusion of DOPC/DOPE (70/30 mol%) membranes utilizing steady-state and time-resolved fluorescence spectroscopic methods. Our results suggest that membranes with 5 mol% LA stabilize the stalk-intermediate and promote lipid mixing at the early stage of the process, i.e., the fusion follows the classical stalk model. Conversely, the extents of lipid and content mixing at the stalk intermediate are similar in the presence of 5 mol% of ALA, indicating the fusion mechanism as a nonclassical one like in the DOPC/DOPE (70/30 mol%) membranes. Our results provide an in-depth insight into the effect of the increasing degree of fatty acid tail unsaturation on membrane organization and dynamics and their impact on the membrane fusion mechanism.
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Affiliation(s)
- Ankita Joardar
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India.
| | - Swaratmika Pandia
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India.
| | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India.
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18
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Wehrum S, Siukstaite L, Williamson DJ, Branson TR, Sych T, Madl J, Wildsmith GC, Dai W, Kempmann E, Ross JF, Thomsen M, Webb ME, Römer W, Turnbull WB. Membrane Fusion Mediated by Non-covalent Binding of Re-engineered Cholera Toxin Assemblies to Glycolipids. ACS Synth Biol 2022; 11:3929-3938. [PMID: 36367814 PMCID: PMC9764410 DOI: 10.1021/acssynbio.2c00266] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Membrane fusion is essential for the transport of macromolecules and viruses across membranes. While glycan-binding proteins (lectins) often initiate cellular adhesion, subsequent fusion events require additional protein machinery. No mechanism for membrane fusion arising from simply a protein binding to membrane glycolipids has been described thus far. Herein, we report that a biotinylated protein derived from cholera toxin becomes a fusogenic lectin upon cross-linking with streptavidin. This novel reengineered protein brings about hemifusion and fusion of vesicles as demonstrated by mixing of fluorescently labeled lipids between vesicles as well as content mixing of liposomes filled with fluorescently labeled dextran. Exclusion of the complex at vesicle-vesicle interfaces could also be observed, indicating the formation of hemifusion diaphragms. Discovery of this fusogenic lectin complex demonstrates that new emergent properties can arise from simple changes in protein architecture and provides insights into new mechanisms of lipid-driven fusion.
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Affiliation(s)
- Sarah Wehrum
- Faculty
of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany,Bioss-Centre
for Biological Signalling Studies, Albert-Ludwigs-University
Freiburg, Schänzlestraße
18, 79104 Freiburg, Germany
| | - Lina Siukstaite
- Faculty
of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany,Bioss-Centre
for Biological Signalling Studies, Albert-Ludwigs-University
Freiburg, Schänzlestraße
18, 79104 Freiburg, Germany
| | - Daniel J. Williamson
- School
of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT Leeds, U.K..
| | - Thomas R. Branson
- School
of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT Leeds, U.K..
| | - Taras Sych
- Faculty
of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany,Bioss-Centre
for Biological Signalling Studies, Albert-Ludwigs-University
Freiburg, Schänzlestraße
18, 79104 Freiburg, Germany,Freiburg
Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany,Science
for Life Laboratory, Department of Women’s and Children’s
Health, Karolinska Institutet, 17165 Solna, Sweden
| | - Josef Madl
- Faculty
of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany,Bioss-Centre
for Biological Signalling Studies, Albert-Ludwigs-University
Freiburg, Schänzlestraße
18, 79104 Freiburg, Germany,Freiburg
Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
| | - Gemma C. Wildsmith
- School
of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT Leeds, U.K..
| | - Wenyue Dai
- School
of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT Leeds, U.K..
| | - Erik Kempmann
- Faculty
of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany,Bioss-Centre
for Biological Signalling Studies, Albert-Ludwigs-University
Freiburg, Schänzlestraße
18, 79104 Freiburg, Germany
| | - James F. Ross
- School
of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT Leeds, U.K..
| | - Maren Thomsen
- School of
Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT Leeds, U.K..
| | - Michael E. Webb
- School
of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT Leeds, U.K..
| | - Winfried Römer
- Faculty
of Biology, Albert-Ludwigs-University Freiburg, Schänzlestraße 1, 79104 Freiburg, Germany,Bioss-Centre
for Biological Signalling Studies, Albert-Ludwigs-University
Freiburg, Schänzlestraße
18, 79104 Freiburg, Germany,Freiburg
Center for Interactive Materials and Bioinspired Technology (FIT), Albert-Ludwigs-University Freiburg, Georges-Köhler-Allee 105, 79110 Freiburg, Germany,
| | - W. Bruce Turnbull
- School
of Chemistry and Astbury Centre for Structural Molecular Biology, University of Leeds, LS2 9JT Leeds, U.K..,
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19
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Villamil Giraldo AM, Mannsverk S, Kasson PM. Measuring single-virus fusion kinetics using an assay for nucleic acid exposure. Biophys J 2022; 121:4467-4475. [PMID: 36330566 PMCID: PMC9748363 DOI: 10.1016/j.bpj.2022.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 09/26/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022] Open
Abstract
The kinetics by which individual enveloped viruses fuse with membranes provide an important window into viral-entry mechanisms. We have developed a real-time assay using fluorescent probes for single-virus genome exposure than can report on stages of viral entry including or subsequent to fusion pore formation and prior to viral genome trafficking. We accomplish this using oxazole yellow nucleic-acid-binding dyes, which can be encapsulated in the lumen of target membranes to permit specific detection of fusion events. Since increased fluorescence of the dye occurs only when it encounters viral genome via a fusion pore and binds, this assay excludes content leakage without fusion. Using this assay, we show that influenza virus fuses with liposomes of different sizes with indistinguishable kinetics by both testing liposomes extruded through pores of different radii and showing that the fusion kinetics of individual liposomes are uncorrelated with the size of the liposome. These results suggest that the starting curvature of such liposomes does not control the rate-limiting steps in influenza entry.
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Affiliation(s)
- Ana M Villamil Giraldo
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Steinar Mannsverk
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Peter M Kasson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden; Departments of Molecular Physiology and Biomedical Engineering, University of Virginia, Charlottesville, Virginia.
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20
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Yeo XY, Lim YT, Chae WR, Park C, Park H, Jung S. Alterations of presynaptic proteins in autism spectrum disorder. Front Mol Neurosci 2022; 15:1062878. [DOI: 10.3389/fnmol.2022.1062878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 10/31/2022] [Indexed: 11/19/2022] Open
Abstract
The expanded use of hypothesis-free gene analysis methods in autism research has significantly increased the number of genetic risk factors associated with the pathogenesis of autism. A further examination of the implicated genes directly revealed the involvement in processes pertinent to neuronal differentiation, development, and function, with a predominant contribution from the regulators of synaptic function. Despite the importance of presynaptic function in synaptic transmission, the regulation of neuronal network activity, and the final behavioral output, there is a relative lack of understanding of the presynaptic contribution to the pathology of autism. Here, we will review the close association among autism-related mutations, autism spectrum disorders (ASD) phenotypes, and the altered presynaptic protein functions through a systematic examination of the presynaptic risk genes relating to the critical stages of synaptogenesis and neurotransmission.
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21
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Kalutsky MA, Galimzyanov TR, Molotkovsky RJ. A Model of Lipid Monolayer-Bilayer Fusion of Lipid Droplets and Peroxisomes. MEMBRANES 2022; 12:membranes12100992. [PMID: 36295751 PMCID: PMC9612070 DOI: 10.3390/membranes12100992] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Revised: 10/06/2022] [Accepted: 10/10/2022] [Indexed: 06/01/2023]
Abstract
Lipid droplets are unique organelles that store neutral lipids encapsulated by the lipid monolayer. In some processes of cellular metabolism, lipid droplets interact with peroxisomes resulting in the fusion of their envelopes and the formation of protrusions of the peroxisome monolayer, called pexopodia. The formation of pexopodia is facilitated by free fatty acids generated during lipolysis within lipid droplets. In this work, we studied the fusion of monolayer and bilayer membranes during the interaction between lipid droplets and peroxisomes. To this end, we built the energy trajectory of this process using the continuum elasticity theory and investigated the molecular details of the fusion structures utilizing molecular dynamics. We divided the fusion process into two stages: formation of a stalk and its consequent expansion into pexopodia. We found that in the considered system, the stalk was energetically more stable and had a lower energy barrier of formation compared to the case of bilayer fusion. The further evolution of the stalk depended on the value of the spontaneous curvature of the membrane in a threshold manner. We attributed the possible expansion of the stalk to the incorporation of free fatty acids into the stalk region. The developed model allowed describing quantitatively the process of monolayer-bilayer fusion.
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Affiliation(s)
- Maksim A. Kalutsky
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy Prospekt, 119071 Moscow, Russia
- Department of Theoretical Physics and Quantum Technologies, National University of Science and Technology “MISiS”, 4 Leninskiy Prospekt, 119049 Moscow, Russia
| | - Timur R. Galimzyanov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy Prospekt, 119071 Moscow, Russia
| | - Rodion J. Molotkovsky
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy Prospekt, 119071 Moscow, Russia
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22
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Zucker B, Golani G, Kozlov MM. Model for ring closure in ER tubular network dynamics. Biophys J 2022:S0006-3495(22)00825-6. [DOI: 10.1016/j.bpj.2022.10.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/23/2022] [Accepted: 10/04/2022] [Indexed: 11/29/2022] Open
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23
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Mion D, Bunel L, Heo P, Pincet F. The beginning and the end of SNARE-induced membrane fusion. FEBS Open Bio 2022; 12:1958-1979. [PMID: 35622519 PMCID: PMC9623537 DOI: 10.1002/2211-5463.13447] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 05/11/2022] [Accepted: 05/25/2022] [Indexed: 01/25/2023] Open
Abstract
Membrane fusion is not a spontaneous process. Physiologically, the formation of coiled-coil protein complexes, the SNAREpins, bridges the membrane of a vesicle and a target membrane, brings them in close contact, and provides the energy necessary for their fusion. In this review, we utilize results from in vitro experiments and simple physics and chemistry models to dissect the kinetics and energetics of the fusion process from the encounter of the two membranes to the full expansion of a fusion pore. We find three main energy barriers that oppose the fusion process: SNAREpin initiation, fusion pore opening, and expansion. SNAREpin initiation is inherent to the proteins and makes in vitro fusion kinetic experiments rather slow. The kinetics are physiologically accelerated by effectors. The energy barriers that precede pore opening and pore expansion can be overcome by several SNAREpins acting in concert.
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Affiliation(s)
- Delphine Mion
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSLCNRS, Sorbonne Université, Université Paris CitéFrance
| | - Louis Bunel
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSLCNRS, Sorbonne Université, Université Paris CitéFrance
| | - Paul Heo
- Institute of Psychiatry and Neuroscience of Paris (IPNP)INSERM U1266ParisFrance
| | - Frédéric Pincet
- Laboratoire de Physique de l'École Normale Supérieure, ENS, Université PSLCNRS, Sorbonne Université, Université Paris CitéFrance
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24
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Cai Y. Tilt Modulus of Bilayer Membranes Self-Assembled from Rod-Coil Diblock Copolymers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:5820-5828. [PMID: 35437996 DOI: 10.1021/acs.langmuir.2c00427] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Quantitatively understanding membrane fission and fusion requires a mathematical model taking their underlying elastic degrees of freedom, such as the molecule's tilt, into account. Hamm-Kozlov's model is such a framework that includes a tilt modulus along with the bending modulus and Gaussian modulus. This paper investigates the tilt modulus of liquid-crystalline bilayer membranes by applying self-consistent field theory. Unlike the widely used method in molecular dynamics simulation which extracts the tilt modulus by simulating bilayer buckles with various single modes, we introduce a tilt constrain term in the free energy to stabilize bilayers with various tilt angles. Fitting the energy curve as a function of the tilt angle to Hamm-Kozlov's elastic energy allows us to extract the tilt modulus directly. Based on this novel scheme and focused on the bilayers self-assembled from rod-coil diblock copolymers, we carry out a systematic study of the dependence of the tensionless A-phase bilayer's tilt modulus on the microscopic parameters.
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Affiliation(s)
- Yongqiang Cai
- School of Mathematical Sciences, Laboratory of Mathematics and Complex Systems, MOE, Beijing Normal University, 100875 Beijing, China
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25
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Joardar A, Pattnaik GP, Chakraborty H. Mechanism of Membrane Fusion: Interplay of Lipid and Peptide. J Membr Biol 2022; 255:211-224. [PMID: 35435451 PMCID: PMC9014786 DOI: 10.1007/s00232-022-00233-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 03/25/2022] [Indexed: 11/26/2022]
Abstract
Membrane fusion is an essential process for the survival of eukaryotes and the entry of enveloped viruses into host cells. A proper understanding of the mechanism of membrane fusion would provide us a handle to manipulate several biological pathways, and design efficient vaccines against emerging and re-emerging viral infections. Although fusion proteins take the central stage in catalyzing the process, role of lipid composition is also of paramount importance. Lipid composition modulates membrane organization and dynamics and impacts the lipid–protein (peptide) interaction. Moreover, the intrinsic curvature of lipids has strong impact on the formation of stalk and hemifusion diaphragm. Detection of transiently stable intermediates remains the bottleneck in the understanding of fusion mechanism. In order to circumvent this challenge, analytical methods can be employed to determine the kinetic parameters from ensemble average measurements of observables, such as lipid mixing, content mixing, and content leakage. The current review aims to present an analytical method that would aid our understanding of the fusion mechanism, provides a better insight into the role of lipid shape, and discusses the interplay of lipid and peptide in membrane fusion.
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Affiliation(s)
- Ankita Joardar
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha, 768019, India
| | | | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha, 768019, India.
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26
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Liu X, Stenhammar J, Wennerström H, Sparr E. Vesicles Balance Osmotic Stress with Bending Energy That Can Be Released to Form Daughter Vesicles. J Phys Chem Lett 2022; 13:498-507. [PMID: 35005979 PMCID: PMC8785185 DOI: 10.1021/acs.jpclett.1c03369] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
The bending energy of the lipid membrane is central to biological processes involving vesicles, such as endocytosis and exocytosis. To illustrate the role of bending energy in these processes, we study the response of single-component giant unilamellar vesicles (GUVs) subjected to external osmotic stress by glucose addition. For osmotic pressures exceeding 0.15 atm, an abrupt shape change from spherical to prolate occurs, showing that the osmotic pressure is balanced by the free energy of membrane bending. After equilibration, the external glucose solution was exchanged for pure water, yielding rapid formation of monodisperse daughter vesicles inside the GUVs through an endocytosis-like process. Our theoretical analysis shows that this process requires significant free energies stored in the deformed membrane to be kinetically allowed. The results indicate that bending energies stored in GUVs are much higher than previously implicated, with potential consequences for vesicle fusion/fission and the osmotic regulation in living cells.
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Affiliation(s)
- Xiaoyan Liu
- Physical Chemistry, Lund University, 221 00 Lund, Sweden
| | | | | | - Emma Sparr
- Physical Chemistry, Lund University, 221 00 Lund, Sweden
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27
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Batishchev OV. Physico-Chemical Mechanisms of the Functioning of Membrane-Active Proteins of Enveloped Viruses. BIOCHEMISTRY (MOSCOW) SUPPLEMENT. SERIES A, MEMBRANE AND CELL BIOLOGY 2022; 16:247-260. [PMCID: PMC9734521 DOI: 10.1134/s1990747822050038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/01/2022] [Accepted: 06/02/2022] [Indexed: 12/14/2022]
Abstract
Over the past few years, the attention of the whole world has been riveted to the emergence of new dangerous strains of viruses, among which a special place is occupied by coronaviruses that have overcome the interspecies barrier in the past 20 years: SARS viruses (SARS), Middle East respiratory syndrome (MERS), as well as a new coronavirus infection (SARS-CoV-2), which caused the largest pandemic since the Spanish flu in 1918. Coronaviruses are members of a class of enveloped viruses that have a lipoprotein envelope. This class also includes such serious pathogens as human immunodeficiency virus (HIV), hepatitis, Ebola virus, influenza, etc. Despite significant differences in the clinical picture of the course of disease caused by enveloped viruses, they themselves have a number of characteristic features, which determine their commonality. Regardless of the way of penetration into the cell—by endocytosis or direct fusion with the cell membrane—enveloped viruses are characterized by the following stages of interaction with the target cell: binding to receptors on the cell surface, interaction of the surface glycoproteins of the virus with the membrane structures of the infected cell, fusion of the lipid envelope of the virion with plasma or endosomal membrane, destruction of the protein capsid and its dissociation from the viral nucleoprotein. Subsequently, within the infected cell, the newly synthesized viral proteins must self-assemble on various membrane structures to form a progeny virion. Thus, both the initial stages of viral infection and the assembly and release of new viral particles are associated with the activity of viral proteins in relation to the cell membrane and its organelles. This review is devoted to the analysis of physicochemical mechanisms of functioning of the main structural proteins of a number of enveloped viruses in order to identify possible strategies for the membrane activity of such proteins at various stages of viral infection of the cell.
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Affiliation(s)
- O. V. Batishchev
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russia
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28
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Tuerkova A, Kasson PM. Computational methods to study enveloped viral entry. Biochem Soc Trans 2021; 49:2527-2537. [PMID: 34783344 PMCID: PMC10184508 DOI: 10.1042/bst20210190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/25/2021] [Accepted: 10/27/2021] [Indexed: 12/15/2022]
Abstract
The protein-membrane interactions that mediate viral infection occur via loosely ordered, transient assemblies, creating challenges for high-resolution structure determination. Computational methods and in particular molecular dynamics simulation have thus become important adjuncts for integrating experimental data, developing mechanistic models, and suggesting testable hypotheses regarding viral function. However, the large molecular scales of virus-host interaction also create challenges for detailed molecular simulation. For this reason, continuum membrane models have played a large historical role, although they have become less favored for high-resolution models of protein assemblies and lipid organization. Here, we review recent progress in the field, with an emphasis on the insight that has been gained using a mixture of coarse-grained and atomic-resolution molecular dynamics simulations. Based on successes and challenges to date, we suggest a multiresolution strategy that should yield the best mixture of computational efficiency and physical fidelity. This strategy may facilitate further simulations of viral entry by a broader range of viruses, helping illuminate the diversity of viral entry strategies and the essential common elements that can be targeted for antiviral therapies.
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Affiliation(s)
- Alzbeta Tuerkova
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala 75124, Sweden
| | - Peter M Kasson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala 75124, Sweden
- Departments of Molecular Physiology and Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, U.S.A
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29
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Joardar A, Pattnaik GP, Chakraborty H. Effect of Phosphatidylethanolamine and Oleic Acid on Membrane Fusion: Phosphatidylethanolamine Circumvents the Classical Stalk Model. J Phys Chem B 2021; 125:13192-13202. [PMID: 34839659 DOI: 10.1021/acs.jpcb.1c08044] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Membrane fusion is one of the most important processes for the survival of eukaryotic cells and entry of enveloped viruses to the host cells. Lipid composition plays a crucial role in the process by modulating the organization and dynamics of the membrane, as well as the structure and conformation of membrane proteins. Phosphatidylethanolamine (PE), a lipid molecule with intrinsic negative curvature, promotes membrane fusion by stabilizing the non-lamellar intermediate structures in the fusion process. Conversely, oleic acid (OA), with intrinsic positive curvature, inhibits membrane fusion. The current study aimed to investigate polyethylene glycol-mediated lipid mixing, content mixing, content leakage, and depth-dependent membrane organization and dynamics, using arrays of steady-state and time-resolved fluorescence techniques, to determine the causative role of PE and OA in membrane fusion. The results demonstrated that the presence of 30 mol % PE in the membrane promotes membrane fusion through a mechanism that circumvents the classical stalk model. On the contrary, membranes containing OA showed reduced rate and extent of fusion, despite following the same mechanism. Collectively, our findings in terms of membrane organization and dynamics indicated a plausible role of PE and OA in membrane fusion.
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Affiliation(s)
- Ankita Joardar
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India
| | | | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India
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30
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Iriondo MN, Etxaniz A, Antón Z, Montes LR, Alonso A. Molecular and mesoscopic geometries in autophagosome generation. A review. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183731. [PMID: 34419487 DOI: 10.1016/j.bbamem.2021.183731] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/12/2021] [Accepted: 08/15/2021] [Indexed: 01/18/2023]
Abstract
Autophagy is an essential process in cell self-repair and survival. The centre of the autophagic event is the generation of the so-called autophagosome (AP), a vesicle surrounded by a double membrane (two bilayers). The AP delivers its cargo to a lysosome, for degradation and re-use of the hydrolysis products as new building blocks. AP formation is a very complex event, requiring dozens of specific proteins, and involving numerous instances of membrane biogenesis and architecture, including membrane fusion and fission. Many stages of AP generation can be rationalised in terms of curvature, both the molecular geometry of lipids interpreted in terms of 'intrinsic curvature', and the overall mesoscopic curvature of the whole membrane, as observed with microscopy techniques. The present contribution intends to bring together the worlds of biophysics and cell biology of autophagy, in the hope that the resulting cross-pollination will generate abundant fruit.
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Affiliation(s)
- Marina N Iriondo
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Asier Etxaniz
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Zuriñe Antón
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - L Ruth Montes
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain
| | - Alicia Alonso
- Instituto Biofisika (CSIC, UPV/EHU) and Departamento de Bioquímica y Biología Molecular, Universidad del País Vasco, 48940 Leioa, Spain.
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31
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Arribas Perez M, Beales PA. Biomimetic Curvature and Tension-Driven Membrane Fusion Induced by Silica Nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:13917-13931. [PMID: 34788054 DOI: 10.1021/acs.langmuir.1c02492] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Fusion events in living cells are intricate phenomena that require the coordinate action of multicomponent protein complexes. However, simpler synthetic tools to control membrane fusion in artificial cells are highly desirable. Native membrane fusion machinery mediates fusion, driving a delicate balance of membrane curvature and tension between two closely apposed membranes. Here, we show that silica nanoparticles (SiO2 NPs) at a size close to the cross-over between tension-driven and curvature-driven interaction regimes initiate efficient fusion of biomimetic model membranes. Fusion efficiency and mechanisms are studied by Förster resonance energy transfer and confocal fluorescence microscopy. SiO2 NPs induce a slight increase in lipid packing likely to increase the lateral tension of the membrane. We observe a connection between membrane tension and fusion efficiency. Finally, real-time confocal fluorescence microscopy reveals three distinct mechanistic pathways for membrane fusion. SiO2 NPs show significant potential for inclusion in the synthetic biology toolkit for membrane remodeling and fusion in artificial cells.
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Affiliation(s)
- Marcos Arribas Perez
- Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
| | - Paul A Beales
- Astbury Centre for Structural Molecular Biology and School of Chemistry, University of Leeds, Leeds LS2 9JT, U.K
- Bragg Centre for Materials Research, University of Leeds, Leeds LS2 9JT, U.K
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32
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François-Martin C, Bacle A, Rothman JE, Fuchs PFJ, Pincet F. Cooperation of Conical and Polyunsaturated Lipids to Regulate Initiation and Processing of Membrane Fusion. Front Mol Biosci 2021; 8:763115. [PMID: 34746239 PMCID: PMC8566721 DOI: 10.3389/fmolb.2021.763115] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 09/23/2021] [Indexed: 12/03/2022] Open
Abstract
The shape of lipids has long been suspected to be a critical determinant for the control of membrane fusion. To experimentally test this assertion, we used conical and malleable lipids and measured their influence on the fusion kinetics. We found that, as previously suspected, both types of lipids accelerate fusion. However, the implicated molecular mechanisms are strikingly different. Malleable lipids, with their ability to change shape with low energy cost, favor fusion by decreasing the overall activation energy. On the other hand, conical lipids, with their small polar head relative to the area occupied by the hydrophobic chains, tend to make fusion less energetically advantageous because they tend to migrate towards the most favorable lipid leaflet, hindering fusion pore opening. They could however facilitate fusion by generating hydrophobic defects on the membranes; this is suggested by the similar trend observed between the experimental rate of fusion nucleation and the surface occupied by hydrophobic defects obtained by molecular simulations. The synergy of dual-process, activation energy and nucleation kinetics, could facilitate membrane fusion regulation in vivo.
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Affiliation(s)
- Claire François-Martin
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, CNRS, Université PSL, Sorbonne Université, Université de Paris, Paris, France
| | - Amélie Bacle
- Laboratoire Coopératif "Lipotoxicity and Channelopathies-ConicMeds", Université de Poitiers, Poitiers, France
| | - James E Rothman
- Department of Cell Biology, School of Medicine, Yale University, New Haven, CT, United States.,Nanobiology Institute, Yale School of Medicine, West Haven, CT, United States
| | - Patrick F J Fuchs
- Laboratoire des Biomolécules (LBM), CNRS, Ecole Normale Supérieure, Sorbonne Université, PSL Research University, Paris, France.,UFR Sciences Du Vivant, Université de Paris, Paris, France
| | - Frédéric Pincet
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, CNRS, Université PSL, Sorbonne Université, Université de Paris, Paris, France
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33
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The late endosome-resident lipid bis(monoacylglycero)phosphate is a cofactor for Lassa virus fusion. PLoS Pathog 2021; 17:e1009488. [PMID: 34492091 PMCID: PMC8448326 DOI: 10.1371/journal.ppat.1009488] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 09/17/2021] [Accepted: 08/25/2021] [Indexed: 11/20/2022] Open
Abstract
Arenavirus entry into host cells occurs through a low pH-dependent fusion with late endosomes that is mediated by the viral glycoprotein complex (GPC). The mechanisms of GPC-mediated membrane fusion and of virus targeting to late endosomes are not well understood. To gain insights into arenavirus fusion, we examined cell-cell fusion induced by the Old World Lassa virus (LASV) GPC complex. LASV GPC-mediated cell fusion is more efficient and occurs at higher pH with target cells expressing human LAMP1 compared to cells lacking this cognate receptor. However, human LAMP1 is not absolutely required for cell-cell fusion or LASV entry. We found that GPC-induced fusion progresses through the same lipid intermediates as fusion mediated by other viral glycoproteins–a lipid curvature-sensitive intermediate upstream of hemifusion and a hemifusion intermediate downstream of acid-dependent steps that can be arrested in the cold. Importantly, GPC-mediated fusion and LASV pseudovirus entry are specifically augmented by an anionic lipid, bis(monoacylglycero)phosphate (BMP), which is highly enriched in late endosomes. This lipid also specifically promotes cell fusion mediated by Junin virus GPC, an unrelated New World arenavirus. We show that BMP promotes late steps of LASV fusion downstream of hemifusion–the formation and enlargement of fusion pores. The BMP-dependence of post-hemifusion stages of arenavirus fusion suggests that these viruses evolved to use this lipid as a cofactor to selectively fuse with late endosomes. Pathogenic arenaviruses pose a serious health threat. The viral envelope glycoprotein GPC mediates attachment to host cells and drives virus entry via endocytosis and low pH-dependent fusion within late endosomes. Understanding the host factors and processes that are essential for arenavirus fusion may identify novel therapeutic targets. To delineate the mechanism of arenavirus entry, we examined cell-cell fusion induced by the Old World Lassa virus GPC proteins at low pH. Lassa GPC-mediated fusion was augmented by the human LAMP1 receptor and progressed through lipid curvature-sensitive intermediates, such as hemifusion (merger of contacting leaflets of viral and cell membrane without the formation of a fusion pore). We found that most GPC-mediated fusion events were off-path hemifusion structures and that the transition from hemifusion to full fusion and fusion pore enlargement were specifically promoted by an anionic lipid, bis(monoacylglycero)phosphate, which is highly enriched in late endosomes. This lipid also specifically promotes fusion of unrelated New World Junin arenavirus. Our results imply that arenaviruses evolved to use bis(monoacylglycero)phosphate to enter cells from late endosomes.
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34
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Goto M, Kazama A, Fukuhara K, Sato H, Tamai N, Ito HO, Matsuki H. Membrane fusion of phospholipid bilayers under high pressure: Spherical and irreversible growth of giant vesicles. Biophys Chem 2021; 277:106639. [PMID: 34171580 DOI: 10.1016/j.bpc.2021.106639] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/29/2021] [Accepted: 06/04/2021] [Indexed: 10/21/2022]
Abstract
Membrane fusion of giant vesicles (GVs) for binary bilayers of unsaturated phospholipids, dioleoylphosphatidyl-ethanolamine (DOPE) having an ability to promote membrane fusion, and its homolog dioleoylphosphatidylcholine (DOPC) having an ability to form GV, was investigated under atmospheric and high pressure. While DOPC formed GVs in the presence of inorganic salts with a multivalent metal ion under atmospheric pressure, an equimolar mixture of DOPE and DOPC formed GVs both in the absence and the presence of LaCl3. We examined the change in size and shape of the GVs of this binary mixture in the absence and presence of LaCl3 as a function of time under atmospheric and high pressure. The size and shape of the GVs in the absence of LaCl3 under atmospheric and high pressure and those in the presence of LaCl3 under atmospheric pressure hardly changed with time. By contrast, the GV in the presence of LaCl3 under high pressure gradually changed in the size and shape with time on a time scale of several hours. Namely, the GV became larger than the original GV due to accelerated membrane fusion and its shape became more spherical. This pressure-induced membrane fusion was completely irreversible, and the growth rate was correlated with the applied pressure. The reason for the GV growth by applying pressure was considered on the basis of thermodynamic phase diagrams. We concluded that the growth is attributable to a closer packing of lipid molecules in the bilayer resulting from their preference of smaller volumes under high pressure. Furthermore, the molecular mechanism of the pressure-induced membrane fusion was explored by observing the fusion of two GVs with almost the same size. From their morphological changes, we revealed that the fusion is caused by the actions of Laplace and osmotic pressure.
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Affiliation(s)
- Masaki Goto
- Department of Bioengineering, Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8513, Japan
| | - Akira Kazama
- Department of Biological Science and Technology, Faculty of Engineering, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Kensuke Fukuhara
- Department of Biological Science and Technology, Faculty of Engineering, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Honami Sato
- Department of Biological Science and Technology, Faculty of Engineering, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8506, Japan
| | - Nobutake Tamai
- Department of Bioengineering, Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8513, Japan
| | - Hiro-O Ito
- Department of Preventive Dentistry, Division of Oral Science, Graduate School of Biomedical Sciences, Tokushima University, 3-8-15 Kuramoto-cho, Tokushima 770-8504, Japan
| | - Hitoshi Matsuki
- Department of Bioengineering, Division of Bioscience and Bioindustry, Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 2-1 Minamijosanjima-cho, Tokushima 770-8513, Japan.
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35
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Smirnova YG, Müller M. How does curvature affect the free-energy barrier of stalk formation? Small vesicles vs apposing, planar membranes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:253-264. [PMID: 33547940 PMCID: PMC8071802 DOI: 10.1007/s00249-020-01494-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 12/08/2020] [Accepted: 12/31/2020] [Indexed: 11/26/2022]
Abstract
Using molecular simulations of POPC lipids in conjunction with the calculation of the Minimum Free-Energy Path (MFEP), we study the effect of strong membrane curvature on the formation of the first fusion intermediate—the stalk between a vesicle and its periodic image. We find that the thermodynamic stability of this hourglass-shaped, hydrophobic connection between two vesicles is largely increased by the strong curvature of small vesicles, whereas the intrinsic barrier to form a stalk, i.e., associated with dimple formation and lipid tails protrusions, is similar to the case of two, apposing, planar membranes. A significant reduction of the barrier of stalk formation, however, stems from the lower dehydration free energy that is required to bring highly curved vesicle into a distance, at which stalk formation may occur, compared to the case of apposing, planar membranes.
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Affiliation(s)
- Y G Smirnova
- Institute for Theoretical Physics, Georg-August University, 37077, Göttingen, Germany.
| | - M Müller
- Institute for Theoretical Physics, Georg-August University, 37077, Göttingen, Germany
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36
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Golani G, Leikina E, Melikov K, Whitlock JM, Gamage DG, Luoma-Overstreet G, Millay DP, Kozlov MM, Chernomordik LV. Myomerger promotes fusion pore by elastic coupling between proximal membrane leaflets and hemifusion diaphragm. Nat Commun 2021; 12:495. [PMID: 33479215 PMCID: PMC7820291 DOI: 10.1038/s41467-020-20804-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 12/08/2020] [Indexed: 01/09/2023] Open
Abstract
Myomerger is a muscle-specific membrane protein involved in formation of multinucleated muscle cells by mediating the transition from the early hemifusion stage to complete fusion. Here, we considered the physical mechanism of the Myomerger action based on the hypothesis that Myomerger shifts the spontaneous curvature of the outer membrane leaflets to more positive values. We predicted, theoretically, that Myomerger generates the outer leaflet elastic stresses, which propagate into the hemifusion diaphragm and accelerate the fusion pore formation. We showed that Myomerger ectodomain indeed generates positive spontaneous curvature of lipid monolayers. We substantiated the mechanism by experiments on myoblast fusion and influenza hemagglutinin-mediated cell fusion. In both processes, the effects of Myomerger ectodomain were strikingly similar to those of lysophosphatidylcholine known to generate a positive spontaneous curvature of lipid monolayers. The control of post-hemifusion stages by shifting the spontaneous curvature of proximal membrane monolayers may be utilized in diverse fusion processes.
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Affiliation(s)
- Gonen Golani
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Evgenia Leikina
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Kamran Melikov
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jarred M Whitlock
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Dilani G Gamage
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Gracia Luoma-Overstreet
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Douglas P Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH, 45229, USA
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel.
| | - Leonid V Chernomordik
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA.
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37
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Bubnis G, Grubmüller H. Sequential Water and Headgroup Merger: Membrane Poration Paths and Energetics from MD Simulations. Biophys J 2020; 119:2418-2430. [PMID: 33189685 PMCID: PMC7822740 DOI: 10.1016/j.bpj.2020.10.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 10/07/2020] [Accepted: 10/23/2020] [Indexed: 01/06/2023] Open
Abstract
Membrane topology changes such as poration, stalk formation, and hemifusion rupture are essential to cellular function, but their molecular details, energetics, and kinetics are still not fully understood. Here, we present a unified energetic and mechanistic picture of metastable pore defects in tensionless lipid membranes. We used an exhaustive committor analysis to test and select optimal reaction coordinates and also to determine the nucleation mechanism. These reaction coordinates were used to calculate free-energy landscapes that capture the full process and end states. The identified barriers agree with the committor analysis. To enable sufficient sampling of the complete transition path for our molecular dynamics simulations, we developed a “gizmo” potential biasing scheme. The simulations suggest that the essential step in the nucleation is the initial merger of lipid headgroups at the nascent pore center. To facilitate this event, an indentation pathway is energetically preferred to a hydrophobic defect. Continuous water columns that span the indentation were determined to be on-path transients that precede the nucleation barrier. This study gives a quantitative description of the nucleation mechanism and energetics of small metastable pores and illustrates a systematic approach to uncover the mechanisms of diverse cellular membrane remodeling processes.
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Affiliation(s)
- Greg Bubnis
- Department of Theoretical and Computational Biophysics, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany; Weill Institute for Neurosciences and Department of Neurology, University of California San Francisco, San Francisco, California.
| | - Helmut Grubmüller
- Department of Theoretical and Computational Biophysics, Max-Planck-Institute for Biophysical Chemistry, Göttingen, Germany.
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38
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Dezanet C, Kempf J, Mingeot-Leclercq MP, Décout JL. Amphiphilic Aminoglycosides as Medicinal Agents. Int J Mol Sci 2020; 21:ijms21197411. [PMID: 33049963 PMCID: PMC7583001 DOI: 10.3390/ijms21197411] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2020] [Revised: 09/27/2020] [Accepted: 10/02/2020] [Indexed: 12/25/2022] Open
Abstract
The conjugation of hydrophobic group(s) to the polycationic hydrophilic core of the antibiotic drugs aminoglycosides (AGs), targeting ribosomal RNA, has led to the development of amphiphilic aminoglycosides (AAGs). These drugs exhibit numerous biological effects, including good antibacterial effects against susceptible and multidrug-resistant bacteria due to the targeting of bacterial membranes. In the first part of this review, we summarize our work in identifying and developing broad-spectrum antibacterial AAGs that constitute a new class of antibiotic agents acting on bacterial membranes. The target-shift strongly improves antibiotic activity against bacterial strains that are resistant to the parent AG drugs and to antibiotic drugs of other classes, and renders the emergence of resistant Pseudomonas aeruginosa strains highly difficult. Structure–activity and structure–eukaryotic cytotoxicity relationships, specificity and barriers that need to be crossed in their development as antibacterial agents are delineated, with a focus on their targets in membranes, lipopolysaccharides (LPS) and cardiolipin (CL), and the corresponding mode of action against Gram-negative bacteria. At the end of the first part, we summarize the other recent advances in the field of antibacterial AAGs, mainly published since 2016, with an emphasis on the emerging AAGs which are made of an AG core conjugated to an adjuvant or an antibiotic drug of another class (antibiotic hybrids). In the second part, we briefly illustrate other biological and biochemical effects of AAGs, i.e., their antifungal activity, their use as delivery vehicles of nucleic acids, of short peptide (polyamide) nucleic acids (PNAs) and of drugs, as well as their ability to cleave DNA at abasic sites and to inhibit the functioning of connexin hemichannels. Finally, we discuss some aspects of structure–activity relationships in order to explain and improve the target selectivity of AAGs.
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Affiliation(s)
- Clément Dezanet
- Molecular Pharmacochemistry Department, University Grenoble Alpes, CNRS, 470 Rue de la Chimie, F-38000 Grenoble, France; (C.D.); (J.K.)
| | - Julie Kempf
- Molecular Pharmacochemistry Department, University Grenoble Alpes, CNRS, 470 Rue de la Chimie, F-38000 Grenoble, France; (C.D.); (J.K.)
| | - Marie-Paule Mingeot-Leclercq
- Cellular and Molecular Pharmacology Unit, Louvain Drug Research Institute, Catholic University of Louvain, Avenue E. Mounier 73, UCL B1.73.05, 1200 Brussels, Belgium
- Correspondence: (M.-P.M.-L.); (J.-L.D.)
| | - Jean-Luc Décout
- Molecular Pharmacochemistry Department, University Grenoble Alpes, CNRS, 470 Rue de la Chimie, F-38000 Grenoble, France; (C.D.); (J.K.)
- Correspondence: (M.-P.M.-L.); (J.-L.D.)
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Mechanistic insights of host cell fusion of SARS-CoV-1 and SARS-CoV-2 from atomic resolution structure and membrane dynamics. Biophys Chem 2020; 265:106438. [PMID: 32721790 PMCID: PMC7375304 DOI: 10.1016/j.bpc.2020.106438] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 01/04/2023]
Abstract
The emerging and re-emerging viral diseases are continuous threats to the wellbeing of human life. Previous outbreaks of Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS had evidenced potential threats of coronaviruses in human health. The recent pandemic due to SARS-CoV-2 is overwhelming and has been going beyond control. Vaccines and antiviral drugs are ungently required to mitigate the pandemic. Therefore, it is important to comprehend the mechanistic details of viral infection process. The fusion between host cell and virus being the first step of infection, understanding the fusion mechanism could provide crucial information to intervene the infection process. Interestingly, all enveloped viruses contain fusion protein on their envelope that acts as fusion machine. For coronaviruses, the spike or S glycoprotein mediates successful infection through receptor binding and cell fusion. The cell fusion process requires merging of virus and host cell membranes, and that is essentially performed by the S2 domain of the S glycoprotein. In this review, we have discussed cell fusion mechanism of SARS-CoV-1 from available atomic resolution structures and membrane binding of fusion peptides. We have further discussed about the cell fusion of SARS-CoV-2 in the context of present pandemic situation.
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Chen YC, Sood C, Marin M, Aaron J, Gratton E, Salaita K, Melikyan GB. Super-Resolution Fluorescence Imaging Reveals That Serine Incorporator Protein 5 Inhibits Human Immunodeficiency Virus Fusion by Disrupting Envelope Glycoprotein Clusters. ACS NANO 2020; 14:10929-10943. [PMID: 32441921 PMCID: PMC8274448 DOI: 10.1021/acsnano.0c02699] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Serine incorporator protein 5 (SERINC5) is the host antiretroviral factor that reduces HIV-1 infectivity by incorporating into virions and inhibiting the envelope glycoprotein (Env) mediated virus fusion with target cells. We and others have shown that SERINC5 incorporation into virions alters the Env structure and sensitizes the virus to broadly neutralizing antibodies targeting cryptic Env epitopes. We have also found that SERINC5 accelerates the loss of Env function over time compared to control viruses. However, the exact mechanism by which SERINC5 inhibits HIV-1 fusion is not understood. Here, we utilized 2D and 3D super-resolution microscopy to examine the effect of SERINC5 on the distribution of Env glycoproteins on single HIV-1 particles. We find that, in agreement with a previous report, Env glycoproteins form clusters on the surface of mature virions. Importantly, incorporation of SERINC5, but not SERINC2, which lacks antiviral activity, disrupted Env clusters without affecting the overall Env content. We also show that SERINC5 and SERINC2 also form clusters on single virions. Unexpectedly, Env and SERINC molecules exhibited poor codistribution on virions, as evidenced by much greater Env-SERINC pairwise distances compared to Env-Env distances. This observation is inconsistent with the previously reported interaction between Env and SERINC5 and suggests an indirect effect of SERINC5 on Env cluster formation. Collectively, our results reveal a multifaceted mechanism of SERINC5-mediated restriction of HIV-1 fusion that, aside from the effects on individual Env trimers, involves disruption of Env clusters, which likely serve as sites of viral fusion with target cells.
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Affiliation(s)
- Yen-Cheng Chen
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Chetan Sood
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Mariana Marin
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jesse Aaron
- Janelia Research Campus, Ashburn, VA, 20147, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, University of California Irvine, Irvine, CA 92617, USA
| | - Khalid Salaita
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Gregory B. Melikyan
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
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Akimov SA, Kondrashov OV, Zimmerberg J, Batishchev OV. Ectodomain Pulling Combines with Fusion Peptide Inserting to Provide Cooperative Fusion for Influenza Virus and HIV. Int J Mol Sci 2020; 21:ijms21155411. [PMID: 32751407 PMCID: PMC7432320 DOI: 10.3390/ijms21155411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/24/2020] [Accepted: 07/28/2020] [Indexed: 12/18/2022] Open
Abstract
Enveloped viruses include the most dangerous human and animal pathogens, in particular coronavirus, influenza virus, and human immunodeficiency virus (HIV). For these viruses, receptor binding and entry are accomplished by a single viral envelope protein (termed the fusion protein), the structural changes of which trigger the remodeling and merger of the viral and target cellular membranes. The number of fusion proteins required for fusion activity is still under debate, and several studies report this value to range from 1 to 9 for type I fusion proteins. Here, we consider the earliest stage of viral fusion based on the continuum theory of membrane elasticity. We demonstrate that membrane deformations induced by the oblique insertion of amphipathic fusion peptides mediate the lateral interaction of these peptides and drive them to form into a symmetric fusion rosette. The pulling force produced by the structural rearrangements of the fusion protein ectodomains gives additional torque, which deforms the membrane and additionally stabilizes the symmetric fusion rosette, thus allowing a reduction in the number of fusion peptides needed for fusion. These findings can resolve the large range of published cooperativity indices for HIV, influenza, and other type I fusion proteins.
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Affiliation(s)
- Sergey A. Akimov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia; (O.V.K.); (O.V.B.)
- Correspondence: ; Tel.: +7-495-955-4776
| | - Oleg V. Kondrashov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia; (O.V.K.); (O.V.B.)
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA;
| | - Oleg V. Batishchev
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia; (O.V.K.); (O.V.B.)
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Akimov SA, Molotkovsky RJ, Kuzmin PI, Galimzyanov TR, Batishchev OV. Continuum Models of Membrane Fusion: Evolution of the Theory. Int J Mol Sci 2020; 21:E3875. [PMID: 32485905 PMCID: PMC7312925 DOI: 10.3390/ijms21113875] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/24/2020] [Accepted: 05/27/2020] [Indexed: 12/18/2022] Open
Abstract
Starting from fertilization, through tissue growth, hormone secretion, synaptic transmission, and sometimes morbid events of carcinogenesis and viral infections, membrane fusion regulates the whole life of high organisms. Despite that, a lot of fusion processes still lack well-established models and even a list of main actors. A merger of membranes requires their topological rearrangements controlled by elastic properties of a lipid bilayer. That is why continuum models based on theories of membrane elasticity are actively applied for the construction of physical models of membrane fusion. Started from the view on the membrane as a structureless film with postulated geometry of fusion intermediates, they developed along with experimental and computational techniques to a powerful tool for prediction of the whole process with molecular accuracy. In the present review, focusing on fusion processes occurring in eukaryotic cells, we scrutinize the history of these models, their evolution and complication, as well as open questions and remaining theoretical problems. We show that modern approaches in this field allow continuum models of membrane fusion to stand shoulder to shoulder with molecular dynamics simulations, and provide the deepest understanding of this process in multiple biological systems.
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Affiliation(s)
- Sergey A. Akimov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia; (R.J.M.); (P.I.K.); (T.R.G.); (O.V.B.)
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Bruininks BM, Souza PC, Ingolfsson H, Marrink SJ. A molecular view on the escape of lipoplexed DNA from the endosome. eLife 2020; 9:52012. [PMID: 32297853 PMCID: PMC7170654 DOI: 10.7554/elife.52012] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 02/24/2020] [Indexed: 12/23/2022] Open
Abstract
The use of non-viral vectors for in vivo gene therapy could drastically increase safety, whilst reducing the cost of preparing the vectors. A promising approach to non-viral vectors makes use of DNA/cationic liposome complexes (lipoplexes) to deliver the genetic material. Here we use coarse-grained molecular dynamics simulations to investigate the molecular mechanism underlying efficient DNA transfer from lipoplexes. Our computational fusion experiments of lipoplexes with endosomal membrane models show two distinct modes of transfection: parallel and perpendicular. In the parallel fusion pathway, DNA aligns with the membrane surface, showing very quick release of genetic material shortly after the initial fusion pore is formed. The perpendicular pathway also leads to transfection, but release is slower. We further show that the composition and size of the lipoplex, as well as the lipid composition of the endosomal membrane, have a significant impact on fusion efficiency in our models.
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Affiliation(s)
- Bart Mh Bruininks
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh, Netherlands
| | - Paulo Ct Souza
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh, Netherlands
| | - Helgi Ingolfsson
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh, Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh, Netherlands
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44
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Influenza hemagglutinin drives viral entry via two sequential intramembrane mechanisms. Proc Natl Acad Sci U S A 2020; 117:7200-7207. [PMID: 32188780 DOI: 10.1073/pnas.1914188117] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Enveloped viruses enter cells via a process of membrane fusion between the viral envelope and a cellular membrane. For influenza virus, mutational data have shown that the membrane-inserted portions of the hemagglutinin protein play a critical role in achieving fusion. In contrast to the relatively well-understood ectodomain, a predictive mechanistic understanding of the intramembrane mechanisms by which influenza hemagglutinin drives fusion has been elusive. We used molecular dynamics simulations of fusion between a full-length hemagglutinin proteoliposome and a lipid bilayer to analyze these mechanisms. In our simulations, hemagglutinin first acts within the membrane to increase lipid tail protrusion and promote stalk formation and then acts to engage the distal leaflets of each membrane and promote stalk widening, curvature, and eventual fusion. These two sequential mechanisms, one occurring before stalk formation and one after, are consistent with our experimental measurements of single-virus fusion kinetics to liposomes of different sizes. The resulting model also helps explain and integrate previous mutational and biophysical data, particularly the mutational sensitivity of the fusion peptide N terminus and the length sensitivity of the transmembrane domain. We hypothesize that entry by other enveloped viruses may also use sequential processes of acyl tail exposure, followed by membrane curvature and distal leaflet engagement.
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Galimzyanov TR, Bashkirov PV, Blank PS, Zimmerberg J, Batishchev OV, Akimov SA. Monolayerwise application of linear elasticity theory well describes strongly deformed lipid membranes and the effect of solvent. SOFT MATTER 2020; 16:1179-1189. [PMID: 31934707 DOI: 10.1039/c9sm02079a] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The theory of elasticity of lipid membranes is used widely to describe processes of cell membrane remodeling. Classically, the functional of a membrane's elastic energy is derived under assumption of small deformations; the membrane is considered as an infinitely thin film. This functional is quadratic on membrane surface curvature, with half of the splay modulus as its proportionality coefficient; it is generally applicable for small deformations only. Any validity of this functional for the regime of strong deformations should be verified experimentally. Recently, research using molecular dynamics simulations challenged the validity of this classic, linear model, i.e. the constancy of the splay modulus for strongly bent membranes. Here we demonstrate that the quadratic energy functional still can be applied for calculation of the elastic energy of strongly deformed membranes without introducing higher order terms with additional elastic moduli, but only if applied separately for each lipid monolayer. For cylindrical membranes, both classic and monolayerwise models yield equally accurate results. For cylindrical deformations we experimentally show that the elastic energy of lipid monolayers is additive: a low molecular weight solvent leads to an approximately twofold decrease in the membrane bending stiffness. Accumulation of solvent molecules in the inner monolayer of a membrane cylinder can explain these results, as the solvent partially prevents lipid molecules from splaying there. Thus, the linear theory of elasticity can be expanded through the range from weak to strong deformations-its simplicity and physical transparency describe various membrane phenomena.
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Affiliation(s)
- Timur R Galimzyanov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, Moscow 119071, Russia
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Joensuu M, Wallis TP, Saber SH, Meunier FA. Phospholipases in neuronal function: A role in learning and memory? J Neurochem 2020; 153:300-333. [PMID: 31745996 DOI: 10.1111/jnc.14918] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 10/29/2019] [Accepted: 11/15/2019] [Indexed: 12/20/2022]
Abstract
Despite the human brain being made of nearly 60% fat, the vast majority of studies on the mechanisms of neuronal communication which underpin cognition, memory and learning, primarily focus on proteins and/or (epi)genetic mechanisms. Phospholipids are the main component of all cellular membranes and function as substrates for numerous phospholipid-modifying enzymes, including phospholipases, which release free fatty acids (FFAs) and other lipid metabolites that can alter the intrinsic properties of the membranes, recruit and activate critical proteins, and act as lipid signalling molecules. Here, we will review brain specific phospholipases, their roles in membrane remodelling, neuronal function, learning and memory, as well as their disease implications. In particular, we will highlight key roles of unsaturated FFAs, particularly arachidonic acid, in neurotransmitter release, neuroinflammation and memory. In light of recent findings, we will also discuss the emerging role of phospholipase A1 and the creation of saturated FFAs in the brain.
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Affiliation(s)
- Merja Joensuu
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Qld, Australia.,Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Tristan P Wallis
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Qld, Australia
| | - Saber H Saber
- Laboratory of Molecular Cell Biology, Department of Zoology, Faculty of Science, Assiut University, Assiut, Egypt
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Qld, Australia
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Han Y, Xu Z, Shi AC, Zhang L. Pathways connecting two opposed bilayers with a fusion pore: a molecularly-informed phase field approach. SOFT MATTER 2020; 16:366-374. [PMID: 31799560 DOI: 10.1039/c9sm01983a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A phase field model with two phase fields, representing the concentration and the head-tail separation of amphiphilic molecules, respectively, has been constructed using an extension of the Ohta-Kawasaki model (Macromolecules, 1986, 19, 2621-2632). It is shown that this molecularly-informed phase field model is capable of producing various self-assembled amphiphilic aggregates, such as bilayers, vesicles and micelles. Furthermore, pathways connecting two opposed bilayers with a fusion pore are obtained by using a combination of the phase field model and the string method. Multiple fusion pathways, including a classical pathway and a leaky pathway, have been obtained depending on the initial separation of the two bilayers. The study shed light on the understanding of the membrane fusion pathways and, more importantly, laid a foundation for further investigation of more complex membrane morphologies and transitions.
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Affiliation(s)
- Yucen Han
- Beijing International Center for Mathematical Research, Peking University, Beijing 100871, China.
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48
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Kumar S, Kaur N, Mithu VS. Amphiphilic ionic liquid induced fusion of phospholipid liposomes. Phys Chem Chem Phys 2020; 22:25255-25263. [DOI: 10.1039/d0cp04014b] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The impact of increasing concentration of imidazolium-based ionic liquids ([CnMIM]+[Br]−) on the structural integrity of large unilamellar vesicles (LUVs) made of pure phosphatidylcholine (PC) and phosphatidylglycerol (PG) lipids.
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Affiliation(s)
- Sandeep Kumar
- Department of Chemistry
- Guru Nanak Dev University
- Amritsar-143005
- India
| | - Navleen Kaur
- Department of Chemistry
- Guru Nanak Dev University
- Amritsar-143005
- India
| | - Venus Singh Mithu
- Department of Chemistry
- Guru Nanak Dev University
- Amritsar-143005
- India
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49
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Tanguy E, Wang Q, Vitale N. Role of Phospholipase D-Derived Phosphatidic Acid in Regulated Exocytosis and Neurological Disease. Handb Exp Pharmacol 2020; 259:115-130. [PMID: 30570690 DOI: 10.1007/164_2018_180] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Lipids play a vital role in numerous cellular functions starting from a structural role as major constituents of membranes to acting as signaling intracellular or extracellular entities. Accordingly, it has been known for decades that lipids, especially those coming from diet, are important to maintain normal physiological functions and good health. On the other side, the exact molecular nature of these beneficial or deleterious lipids, as well as their precise mode of action, is only starting to be unraveled. This recent improvement in our knowledge is largely resulting from novel pharmacological, molecular, cellular, and genetic tools to study lipids in vitro and in vivo. Among these important lipids, phosphatidic acid plays a unique and central role in a great variety of cellular functions. This review will focus on the proposed functions of phosphatidic acid generated by phospholipase D in the last steps of regulated exocytosis with a specific emphasis on hormonal and neurotransmitter release and its potential impact on different neurological diseases.
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Affiliation(s)
- Emeline Tanguy
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Qili Wang
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France
| | - Nicolas Vitale
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212 and Université de Strasbourg, Strasbourg, France.
- INSERM, Paris, Cedex 13, France.
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50
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Agrawal A, Ramachandran R. Exploring the links between lipid geometry and mitochondrial fission: Emerging concepts. Mitochondrion 2019; 49:305-313. [DOI: 10.1016/j.mito.2019.07.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 07/22/2019] [Accepted: 07/24/2019] [Indexed: 01/08/2023]
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