1
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Mitra S, Chandersekhar B, Li Y, Coopershlyak M, Mahoney ME, Evans B, Koenig R, Hall SCL, Klösgen B, Heinrich F, Deslouches B, Tristram-Nagle S. Novel non-helical antimicrobial peptides insert into and fuse lipid model membranes. SOFT MATTER 2024; 20:4088-4101. [PMID: 38712559 PMCID: PMC11109824 DOI: 10.1039/d4sm00220b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 04/26/2024] [Indexed: 05/08/2024]
Abstract
This research addresses the growing menace of antibiotic resistance by exploring antimicrobial peptides (AMPs) as alternatives to conventional antibiotics. Specifically, we investigate two linear amphipathic AMPs, LE-53 (12-mer) and LE-55 (16-mer), finding that the shorter LE-53 exhibits greater bactericidal activity against both Gram-negative (G(-)) and Gram-positive (G(+)) bacteria. Remarkably, both AMPs are non-toxic to eukaryotic cells. The heightened effectiveness of LE-53 is attributed to its increased hydrophobicity (H) compared to LE-55. Circular dichroism (CD) reveals that LE-53 and LE-55 both adopt β-sheet and random coil structures in lipid model membranes (LMMs) mimicking G(-) and G(+) bacteria, so secondary structure is not the cause of the potency difference. X-ray diffuse scattering (XDS) reveals increased lipid chain order in LE-53, a potential key distinction. Additionally, XDS study uncovers a significant link between LE-53's upper hydrocarbon location in G(-) and G(+) LMMs and its efficacy. Neutron reflectometry (NR) confirms the AMP locations determined using XDS. Solution small angle X-ray scattering (SAXS) demonstrates LE-53's ability to induce vesicle fusion in bacterial LMMs without affecting eukaryotic LMMs, offering a promising strategy to combat antibiotic-resistant strains while preserving human cell integrity, whereas LE-55 has a smaller ability to induce fusion.
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Affiliation(s)
- Saheli Mitra
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Bhairavi Chandersekhar
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Yunshu Li
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Mark Coopershlyak
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Margot E Mahoney
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Brandt Evans
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Rachel Koenig
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
| | - Stephen C L Hall
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire, OX11 0QX, UK
| | - Beate Klösgen
- University of Southern Denmark, Dept. Physics, Chemistry & Pharmacy, PhyLife, Campusvej 55, Odense M5230, Denmark
| | - Frank Heinrich
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Berthony Deslouches
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Stephanie Tristram-Nagle
- Biological Physics Group, Physics Department, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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2
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Ali Moussa HY, Shin KC, Ponraj J, Park SH, Lee OS, Mansour S, Park Y. PIP 2 Is An Electrostatic Catalyst for Vesicle Fusion by Lowering the Hydration Energy: Arresting Vesicle Fusion by Masking PIP 2. ACS NANO 2024; 18:12737-12748. [PMID: 38717305 DOI: 10.1021/acsnano.3c09614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Lipids are key factors in regulating membrane fusion. Lipids are not only structural components to form membranes but also active catalysts for vesicle fusion and neurotransmitter release, which are driven by soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins. SNARE proteins seem to be partially assembled before fusion, but the mechanisms that arrest vesicle fusion before Ca2+ influx are still not clear. Here, we show that phosphatidylinositol 4,5-bisphosphate (PIP2) electrostatically triggers vesicle fusion as an electrostatic catalyst by lowering the hydration energy and that a myristoylated alanine-rich C-kinase substrate (MARCKS), a PIP2-binding protein, arrests vesicle fusion in a vesicle docking state where the SNARE complex is partially assembled. Vesicle-mimicking liposomes fail to reproduce vesicle fusion arrest by masking PIP2, indicating that native vesicles are essential for the reconstitution of physiological vesicle fusion. PIP2 attracts cations to repel water molecules from membranes, thus lowering the hydration energy barrier.
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Affiliation(s)
- Houda Yasmine Ali Moussa
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Kyung Chul Shin
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
| | - Janarthanan Ponraj
- HBKU Core Laboratories, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | | | - One-Sun Lee
- Center for Interdisciplinary Biosciences, Technology and Innovation Park, P. J. Šafárik University, Košice SK-04001, Slovakia
| | - Said Mansour
- HBKU Core Laboratories, Hamad Bin Khalifa University (HBKU), Doha, Qatar
| | - Yongsoo Park
- Neurological Disorders Research Center, Qatar Biomedical Research Institute (QBRI), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
- College of Health & Life Sciences (CHLS), Hamad Bin Khalifa University (HBKU), Qatar Foundation, Doha, Qatar
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3
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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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Krok E, Franquelim HG, Chattopadhyay M, Orlikowska-Rzeznik H, Schwille P, Piatkowski L. Nanoscale structural response of biomimetic cell membranes to controlled dehydration. NANOSCALE 2023; 16:72-84. [PMID: 38062887 DOI: 10.1039/d3nr03078d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
Although cell membranes exist in excess of water under physiological conditions, there are a number of biochemical processes, such as adsorption of biomacromolecules or membrane fusion events, that require partial or even complete transient dehydration of lipid membranes. Even though the dehydration process is crucial for understanding all fusion events, still little is known about the structural adaptation of lipid membranes when their interfacial hydration layer is perturbed. Here, we present the study of the nanoscale structural reorganization of phase-separated, supported lipid bilayers (SLBs) under a wide range of hydration conditions. Model lipid membranes were characterised using a combination of fluorescence microscopy and atomic force microscopy and, crucially, without applying any chemical or physical modifications that have previously been considered essential for maintaining the membrane integrity upon dehydration. We revealed that decreasing the hydration state of the membrane leads to an enhanced mixing of lipids characteristic of the liquid-disordered (Ld) phase with those forming the liquid-ordered (Lo) phase. This is associated with a 2-fold decrease in the hydrophobic mismatch between the Ld and Lo lipid phases and a 3-fold decrease in the line tension for the fully desiccated membrane. Importantly, the observed changes in the hydrophobic mismatch, line tension, and lipid miscibility are fully reversible upon subsequent rehydration of the membrane. These findings provide a deeper insight into the fundamental processes, such as cell-cell fusion, that require partial dehydration at the interface of two membranes.
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Affiliation(s)
- Emilia Krok
- Poznan University of Technology, Faculty of Materials Engineering and Technical Physics, Institute of Physics, Piotrowo 3, 60-965 Poznan, Poland.
| | - Henri G Franquelim
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
- Leipzig University, Research and Transfer Center for Bioactive Matter, Deutscher Platz 5, 04103 Leipzig, Germany
| | - Madhurima Chattopadhyay
- Poznan University of Technology, Faculty of Materials Engineering and Technical Physics, Institute of Physics, Piotrowo 3, 60-965 Poznan, Poland.
| | - Hanna Orlikowska-Rzeznik
- Poznan University of Technology, Faculty of Materials Engineering and Technical Physics, Institute of Physics, Piotrowo 3, 60-965 Poznan, Poland.
| | - Petra Schwille
- Department of Cellular and Molecular Biophysics, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Lukasz Piatkowski
- Poznan University of Technology, Faculty of Materials Engineering and Technical Physics, Institute of Physics, Piotrowo 3, 60-965 Poznan, Poland.
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Bolik S, Schlaich A, Mukhina T, Amato A, Bastien O, Schneck E, Demé B, Jouhet J. Lipid bilayer properties potentially contributed to the evolutionary disappearance of betaine lipids in seed plants. BMC Biol 2023; 21:275. [PMID: 38017456 PMCID: PMC10685587 DOI: 10.1186/s12915-023-01775-z] [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: 09/18/2023] [Accepted: 11/21/2023] [Indexed: 11/30/2023] Open
Abstract
BACKGROUND Many organisms rely on mineral nutrients taken directly from the soil or aquatic environment, and therefore, developed mechanisms to cope with the limitation of a given essential nutrient. For example, photosynthetic cells have well-defined responses to phosphate limitation, including the replacement of cellular membrane phospholipids with non-phosphorous lipids. Under phosphate starvation, phospholipids in extraplastidial membranes are replaced by betaine lipids in microalgae. In higher plants, the synthesis of betaine lipid is lost, driving plants to other strategies to cope with phosphate starvation where they replace their phospholipids by glycolipids. RESULTS The aim of this work was to evaluate to what extent betaine lipids and PC lipids share physicochemical properties and could substitute for each other. By neutron diffraction experiments and dynamic molecular simulation of two synthetic lipids, the dipalmitoylphosphatidylcholine (DPPC) and the dipalmitoyl-diacylglyceryl-N,N,N-trimethylhomoserine (DP-DGTS), we found that DP-DGTS bilayers are thicker than DPPC bilayers and therefore are more rigid. Furthermore, DP-DGTS bilayers are more repulsive, especially at long range, maybe due to unexpected unscreened electrostatic contribution. Finally, DP-DGTS bilayers could coexist in the gel and fluid phases. CONCLUSION The different properties and hydration responses of PC and DGTS provide an explanation for the diversity of betaine lipids observed in marine organisms and for their disappearance in seed plants.
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Affiliation(s)
- Stéphanie Bolik
- Laboratoire Physiologie Cellulaire Et Végétale, Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG, Grenoble, France
- Large Scale Structures Group, Institut Laue-Langevin, 38000, Grenoble, France
| | - Alexander Schlaich
- Institute for Computational Physics, Universität Stuttgart, Stuttgart, Germany
- Stuttgart Center for Simulation Science (SimTech), Universität Stuttgart, Stuttgart, Germany
| | - Tetiana Mukhina
- Institute for Condensed Matter Physics, Darmstadt, Darmstadt, TU, Germany
| | - Alberto Amato
- Laboratoire Physiologie Cellulaire Et Végétale, Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG, Grenoble, France
| | - Olivier Bastien
- Laboratoire Physiologie Cellulaire Et Végétale, Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG, Grenoble, France
| | - Emanuel Schneck
- Institute for Condensed Matter Physics, Darmstadt, Darmstadt, TU, Germany
| | - Bruno Demé
- Large Scale Structures Group, Institut Laue-Langevin, 38000, Grenoble, France.
| | - Juliette Jouhet
- Laboratoire Physiologie Cellulaire Et Végétale, Univ. Grenoble Alpes, CNRS, CEA, INRAE, IRIG, Grenoble, France.
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Beck K, Nandy J, Hoernke M. Membrane permeabilization can be crucially biased by a fusogenic lipid composition - leaky fusion caused by antimicrobial peptides in model membranes. SOFT MATTER 2023; 19:2919-2931. [PMID: 37010846 DOI: 10.1039/d2sm01691e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Induced membrane permeabilization or leakage is often taken as an indication for activity of membrane-active molecules, such as antimicrobial peptides (AMPs). The exact leakage mechanism is often unknown, but important, because certain mechanisms might actually contribute to microbial killing, while others are unselective, or potentially irrelevant in an in vivo situation. Using an antimicrobial example peptide (cR3W3), we illustrate one of the potentially misleading leakage mechanisms: leaky fusion, where leakage is coupled to membrane fusion. Like many others, we examine peptide-induced leakage in model vesicles consisting of binary mixtures of anionic and zwitterionic phospholipids. In fact, phosphatidylglycerol and phosphatidylethanolamine (PG/PE) are supposed to reflect bacterial membranes, but exhibit a high propensity for vesicle aggregation and fusion. We describe the implications of this vesicle fusion and aggregation for the reliability of model studies. The ambiguous role of the relatively fusogenic PE-lipids becomes clear as leakage decreases significantly when aggregation and fusion are prevented by sterical shielding. Furthermore, the mechanism of leakage changes if PE is exchanged for phosphatidylcholine (PC). We thus point out that the lipid composition of model membranes can be biased towards leaky fusion. This can lead to discrepancies between model studies and activity in true microbes, because leaky fusion is likely prevented by bacterial peptidoglycan layers. In conclusion, choosing the model membrane might implicate the type of effect (here leakage mechanism) that is observed. In the worst case, as with leaky fusion of PG/PE vesicles, this is not directly relevant for the intended antimicrobial application.
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Affiliation(s)
- Katharina Beck
- Chemistry and Pharmacy, Albert-Ludwigs-Universität, Freiburg i. Br., Germany.
| | - Janina Nandy
- Chemistry and Pharmacy, Albert-Ludwigs-Universität, Freiburg i. Br., Germany.
| | - Maria Hoernke
- Chemistry and Pharmacy, Albert-Ludwigs-Universität, Freiburg i. Br., Germany.
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7
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Molotkovsky RJ, Kuzmin PI. Fusion of Peroxisome and Lipid Droplet Membranes: Expansion of a π-Shaped Structure. BIOCHEMISTRY (MOSCOW), SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2022. [DOI: 10.1134/s1990747822050105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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8
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Shi S, Fan H, Hoernke M. Leaky membrane fusion: an ambivalent effect induced by antimicrobial polycations. NANOSCALE ADVANCES 2022; 4:5109-5122. [PMID: 36504745 PMCID: PMC9680940 DOI: 10.1039/d2na00464j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 10/24/2022] [Indexed: 05/28/2023]
Abstract
Both antimicrobial peptides and their synthetic mimics are potential alternatives to classical antibiotics. They can induce several membrane perturbations including permeabilization. Especially in model studies, aggregation of vesicles by such polycations is often reported. Here, we show that unintended vesicle aggregation or indeed fusion can cause apparent leakage in model studies that is not possible in most microbes, thus potentially leading to misinterpretations. The interactions of a highly charged and highly selective membrane-active polycation with negatively charged phosphatidylethanolamine/phosphatidylglycerol (PE/PG) vesicles are studied by a combination of biophysical methods. At low polycation concentrations, apparent vesicle aggregation was found to involve exchange of lipids. Upon neutralization of the negatively charged vesicles by the polycation, full fusion and leakage occurred and leaky fusion is suspected. To elucidate the interplay of leakage and fusion, we prevented membrane contacts by decorating the vesicles with PEG-chains. This inhibited fusion and also leakage activity. Leaky fusion is further corroborated by increased leakage with increasing likeliness of vesicle-vesicle contacts. Because of its similar appearance to other leakage mechanisms, leaky fusion is difficult to identify and might be overlooked and more common amongst polycationic membrane-active compounds. Regarding biological activity, leaky fusion needs to be carefully distinguished from other membrane permeabilization mechanisms, as it may be less relevant to bacteria, but potentially relevant for fungi. Furthermore, leaky fusion is an interesting effect that could help in endosomal escape for drug delivery. A comprehensive step-by-step protocol for membrane permeabilization/vesicle leakage using calcein fluorescence lifetime is provided in the ESI.
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Affiliation(s)
- Shuai Shi
- Chemistry and Pharmacy, Albert-Ludwigs-Universität 79104 Freiburg i.Br. Germany
| | - Helen Fan
- Leslie Dan Faculty of Pharmacy, University of Toronto Toronto Canada
| | - Maria Hoernke
- Chemistry and Pharmacy, Albert-Ludwigs-Universität 79104 Freiburg i.Br. Germany
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9
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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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10
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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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11
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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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12
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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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13
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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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14
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Vadakkan KI. Framework for internal sensation of pleasure using constraints from disparate findings in nucleus accumbens. World J Psychiatry 2021; 11:681-695. [PMID: 34733636 PMCID: PMC8546768 DOI: 10.5498/wjp.v11.i10.681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 06/27/2021] [Accepted: 09/02/2021] [Indexed: 02/06/2023] Open
Abstract
It is necessary to find a mechanism that generates first-person inner sensation of pleasure to understand what causes addiction and associated behaviour by drugs of abuse. The actual mechanism is expected to explain several disparate findings in nucleus accumbens (NAc), a brain region associated with pleasure, in an interconnected manner. Previously, it was possible to derive a mechanism for natural learning and explain: (1) Generation of inner sensation of memory using changes generated by learning; and (2) Long-term potentiation as an experimental delayed scaled-up change by the same mechanism that occur during natural learning. By extending these findings and by using disparate third person observations in NAc from several studies, present work provides a framework of a mechanism that generates internal sensation of pleasure that can provide interconnected explanations for: (1) Ability to induce robust long-term depression (LTD) in NAc from naïve animals; (2) Impaired ability to induce LTD in “addicted” state; (3) Attenuation of postsynaptic potentials by cocaine; and (4) Reduced firing of medium spiny neurons in response to cocaine or dopamine. Findings made by this work are testable.
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15
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Tang J, Frascaroli G, Zhou X, Knickmann J, Brune W. Cell Fusion and Syncytium Formation in Betaherpesvirus Infection. Viruses 2021; 13:v13101973. [PMID: 34696402 PMCID: PMC8537622 DOI: 10.3390/v13101973] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 09/22/2021] [Accepted: 09/28/2021] [Indexed: 12/14/2022] Open
Abstract
Cell–cell fusion is a fundamental and complex process that occurs during reproduction, organ and tissue growth, cancer metastasis, immune response, and infection. All enveloped viruses express one or more proteins that drive the fusion of the viral envelope with cellular membranes. The same proteins can mediate the fusion of the plasma membranes of adjacent cells, leading to the formation of multinucleated syncytia. While cell–cell fusion triggered by alpha- and gammaherpesviruses is well-studied, much less is known about the fusogenic potential of betaherpesviruses such as human cytomegalovirus (HCMV) and human herpesviruses 6 and 7 (HHV-6 and HHV-7). These are slow-growing viruses that are highly prevalent in the human population and associated with several diseases, particularly in individuals with an immature or impaired immune system such as fetuses and transplant recipients. While HHV-6 and HHV-7 are strictly lymphotropic, HCMV infects a very broad range of cell types including epithelial, endothelial, mesenchymal, and myeloid cells. Syncytia have been observed occasionally for all three betaherpesviruses, both during in vitro and in vivo infection. Since cell–cell fusion may allow efficient spread to neighboring cells without exposure to neutralizing antibodies and other host immune factors, viral-induced syncytia may be important for viral dissemination, long-term persistence, and pathogenicity. In this review, we provide an overview of the viral and cellular factors and mechanisms identified so far in the process of cell–cell fusion induced by betaherpesviruses and discuss the possible consequences for cellular dysfunction and pathogenesis.
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Affiliation(s)
- Jiajia Tang
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (J.T.); (G.F.); (X.Z.); (J.K.)
- Center for Single-Cell Omics, School of Medicine, Shanghai Jiao Tong University, Shanghai 200025, China
| | - Giada Frascaroli
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (J.T.); (G.F.); (X.Z.); (J.K.)
| | - Xuan Zhou
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (J.T.); (G.F.); (X.Z.); (J.K.)
| | - Jan Knickmann
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (J.T.); (G.F.); (X.Z.); (J.K.)
| | - Wolfram Brune
- Leibniz Institute for Experimental Virology (HPI), 20251 Hamburg, Germany; (J.T.); (G.F.); (X.Z.); (J.K.)
- Correspondence:
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16
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Abstract
Fertilization is a multistep process that culminates in the fusion of sperm and egg, thus marking the beginning of a new organism in sexually reproducing species. Despite its importance for reproduction, the molecular mechanisms that regulate this singular event, particularly sperm-egg fusion, have remained mysterious for many decades. Here, we summarize our current molecular understanding of sperm-egg interaction, focusing mainly on mammalian fertilization. Given the fundamental importance of sperm-egg fusion yet the lack of knowledge of this process in vertebrates, we discuss hallmarks and emerging themes of cell fusion by drawing from well-studied examples such as viral entry, placenta formation, and muscle development. We conclude by identifying open questions and exciting avenues for future studies in gamete fusion. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Victoria E Deneke
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria; ,
| | - Andrea Pauli
- Research Institute of Molecular Pathology (IMP), Vienna BioCenter (VBC), 1030 Vienna, Austria; ,
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17
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Chattopadhyay M, Orlikowska H, Krok E, Piatkowski L. Sensing Hydration of Biomimetic Cell Membranes. BIOSENSORS 2021; 11:241. [PMID: 34356712 PMCID: PMC8301980 DOI: 10.3390/bios11070241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/06/2021] [Accepted: 07/06/2021] [Indexed: 11/17/2022]
Abstract
Biological membranes play a vital role in cell functioning, providing structural integrity, controlling signal transduction, and controlling the transport of various chemical species. Owing to the complex nature of biomembranes, the self-assembly of lipids in aqueous media has been utilized to develop model systems mimicking the lipid bilayer structure, paving the way to elucidate the mechanisms underlying various biological processes, as well as to develop a number of biomedical and technical applications. The hydration properties of lipid bilayers are crucial for their activity in various cellular processes. Of particular interest is the local membrane dehydration, which occurs in membrane fusion events, including neurotransmission, fertilization, and viral entry. The lack of universal technique to evaluate the local hydration state of the membrane components hampers understanding of the molecular-level mechanisms of these processes. Here, we present a new approach to quantify the hydration state of lipid bilayers. It takes advantage of the change in the lateral diffusion of lipids that depends on the number of water molecules hydrating them. Using fluorescence recovery after photobleaching technique, we applied this approach to planar single and multicomponent supported lipid bilayers. The method enables the determination of the hydration level of a biomimetic membrane down to a few water molecules per lipid.
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Affiliation(s)
| | | | | | - Lukasz Piatkowski
- Faculty of Materials Engineering and Technical Physics, Institute of Physics, Division of Molecular Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland; (H.O.); (E.K.)
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18
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Tight docking of membranes before fusion represents a metastable state with unique properties. Nat Commun 2021; 12:3606. [PMID: 34127664 PMCID: PMC8203622 DOI: 10.1038/s41467-021-23722-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 05/11/2021] [Indexed: 12/26/2022] Open
Abstract
Membrane fusion is fundamental to biological processes as diverse as membrane trafficking or viral infection. Proteins catalyzing membrane fusion need to overcome energy barriers to induce intermediate steps in which the integrity of bilayers is lost. Here, we investigate the structural features of tightly docked intermediates preceding hemifusion. Using lipid vesicles in which progression to hemifusion is arrested, we show that the metastable intermediate does not require but is enhanced by divalent cations and is characterized by the absence of proteins and local membrane thickening. Molecular dynamics simulations reveal that thickening is due to profound lipid rearrangements induced by dehydration of the membrane surface. Proteins need to overcome energy barriers to induce intermediate steps in membrane fusion. Using lipid vesicles in which progression to hemifusion is arrested, the authors show that the metastable intermediate is enhanced by divalent cations and is characterized by the absence of proteins and local membrane thickening. Simulations reveal that thickening is induced by dehydration of the membrane surface.
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19
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Schlich M, Palomba R, Costabile G, Mizrahy S, Pannuzzo M, Peer D, Decuzzi P. Cytosolic delivery of nucleic acids: The case of ionizable lipid nanoparticles. Bioeng Transl Med 2021; 6:e10213. [PMID: 33786376 PMCID: PMC7995196 DOI: 10.1002/btm2.10213] [Citation(s) in RCA: 124] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Revised: 01/22/2021] [Accepted: 01/25/2021] [Indexed: 12/14/2022] Open
Abstract
Ionizable lipid nanoparticles (LNPs) are the most clinically advanced nano-delivery system for therapeutic nucleic acids. The great effort put in the development of ionizable lipids with increased in vivo potency brought LNPs from the laboratory benches to the FDA approval of patisiran in 2018 and the ongoing clinical trials for mRNA-based vaccines against SARS-CoV-2. Despite these success stories, several challenges remain in RNA delivery, including what is known as "endosomal escape." Reaching the cytosol is mandatory for unleashing the therapeutic activity of RNA molecules, as their accumulation in other intracellular compartments would simply result in efficacy loss. In LNPs, the ability of ionizable lipids to form destabilizing non-bilayer structures at acidic pH is recognized as the key for endosomal escape and RNA cytosolic delivery. This is motivating a surge in studies aiming at designing novel ionizable lipids with improved biodegradation and safety profiles. In this work, we describe the journey of RNA-loaded LNPs across multiple intracellular barriers, from the extracellular space to the cytosol. In silico molecular dynamics modeling, in vitro high-resolution microscopy analyses, and in vivo imaging data are systematically reviewed to distill out the regulating mechanisms underlying the endosomal escape of RNA. Finally, a comparison with strategies employed by enveloped viruses to deliver their genetic material into cells is also presented. The combination of a multidisciplinary analytical toolkit for endosomal escape quantification and a nature-inspired design could foster the development of future LNPs with improved cytosolic delivery of nucleic acids.
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Affiliation(s)
- Michele Schlich
- Fondazione Istituto Italiano di TecnologiaLaboratory of Nanotechnology for Precision MedicineGenoaItaly
- Department of Life and Environmental SciencesUniversity of CagliariCagliariItaly
| | - Roberto Palomba
- Fondazione Istituto Italiano di TecnologiaLaboratory of Nanotechnology for Precision MedicineGenoaItaly
| | - Gabriella Costabile
- Fondazione Istituto Italiano di TecnologiaLaboratory of Nanotechnology for Precision MedicineGenoaItaly
| | - Shoshy Mizrahy
- Fondazione Istituto Italiano di TecnologiaLaboratory of Nanotechnology for Precision MedicineGenoaItaly
- Laboratory of Precision NanoMedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of EngineeringTel Aviv UniversityTel AvivIsrael
- Center for Nanoscience and NanotechnologyTel Aviv UniversityTel AvivIsrael
- Cancer Biology Research CenterTel Aviv UniversityTel AvivIsrael
| | - Martina Pannuzzo
- Fondazione Istituto Italiano di TecnologiaLaboratory of Nanotechnology for Precision MedicineGenoaItaly
| | - Dan Peer
- Laboratory of Precision NanoMedicine, Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life SciencesTel Aviv UniversityTel AvivIsrael
- Department of Materials Sciences and Engineering, Iby and Aladar Fleischman Faculty of EngineeringTel Aviv UniversityTel AvivIsrael
- Center for Nanoscience and NanotechnologyTel Aviv UniversityTel AvivIsrael
- Cancer Biology Research CenterTel Aviv UniversityTel AvivIsrael
| | - Paolo Decuzzi
- Fondazione Istituto Italiano di TecnologiaLaboratory of Nanotechnology for Precision MedicineGenoaItaly
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20
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Witt H, Savić F, Verbeek S, Dietz J, Tarantola G, Oelkers M, Geil B, Janshoff A. Membrane fusion studied by colloidal probes. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:223-237. [PMID: 33599795 PMCID: PMC8071799 DOI: 10.1007/s00249-020-01490-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 12/19/2020] [Indexed: 12/12/2022]
Abstract
Membrane-coated colloidal probes combine the benefits of solid-supported membranes with a more complex three-dimensional geometry. This combination makes them a powerful model system that enables the visualization of dynamic biological processes with high throughput and minimal reliance on fluorescent labels. Here, we want to review recent applications of colloidal probes for the study of membrane fusion. After discussing the advantages and disadvantages of some classical vesicle-based fusion assays, we introduce an assay using optical detection of fusion between membrane-coated glass microspheres in a quasi two-dimensional assembly. Then, we discuss free energy considerations of membrane fusion between supported bilayers, and show how colloidal probes can be combined with atomic force microscopy or optical tweezers to access the fusion process with even greater detail.
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Affiliation(s)
- Hannes Witt
- Institute for Physical Chemistry, University of Göttingen, 37075, Göttingen, Germany
- Physics of Living Systems, Vrije Universiteit Amsterdam, 1081 HV, Amsterdam, The Netherlands
| | - Filip Savić
- Institute for Physical Chemistry, University of Göttingen, 37075, Göttingen, Germany
| | - Sarah Verbeek
- Institute for Physical Chemistry, University of Göttingen, 37075, Göttingen, Germany
| | - Jörn Dietz
- Institute for Physical Chemistry, University of Göttingen, 37075, Göttingen, Germany
| | - Gesa Tarantola
- Institute for Physical Chemistry, University of Göttingen, 37075, Göttingen, Germany
| | - Marieelen Oelkers
- Institute for Physical Chemistry, University of Göttingen, 37075, Göttingen, Germany
| | - Burkhard Geil
- Institute for Physical Chemistry, University of Göttingen, 37075, Göttingen, Germany
| | - Andreas Janshoff
- Institute for Physical Chemistry, University of Göttingen, 37075, Göttingen, Germany.
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21
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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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22
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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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23
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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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24
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Bowers MR, Reist NE. Synaptotagmin: Mechanisms of an electrostatic switch. Neurosci Lett 2020; 722:134834. [DOI: 10.1016/j.neulet.2020.134834] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 02/06/2020] [Accepted: 02/09/2020] [Indexed: 02/09/2023]
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25
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Gundersen CB. Fast, synchronous neurotransmitter release: Past, present and future. Neuroscience 2019; 439:22-27. [PMID: 31047980 DOI: 10.1016/j.neuroscience.2019.04.030] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 04/11/2019] [Accepted: 04/12/2019] [Indexed: 01/23/2023]
Abstract
This mini-review starts with a summary of the crucial contributions Ricardo Miledi made to our understanding of how the action potential triggers fast, synchronous transmitter release. It then transitions to the discovery of synaptotagmin and its role as the exocytotic Ca2+ sensor at nerve terminals. The final section confronts the array of unique models that have been proposed to explain the membrane fusion step of exocytosis. More than a dozen different hypotheses seek to explain the terminal steps of the exocytotic cascade. It will be an interesting challenge for the field to distinguish among these possibilities. Nevertheless, with ongoing technological advances, perhaps we will have a better picture of this process by the end of the coming decade. This article is part of a Special Issue entitled: Honoring Ricardo Miledi - outstanding neuroscientist of XX-XXI centuries.
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Affiliation(s)
- Cameron B Gundersen
- Department of Molecular and Medical Pharmacology, David Geffen UCLA School of Medicine, Los Angeles, CA 90095.
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26
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27
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Vadakkan KI. A potential mechanism for first-person internal sensation of memory provides evidence for the relationship between learning and LTP induction. Behav Brain Res 2018; 360:16-35. [PMID: 30502355 DOI: 10.1016/j.bbr.2018.11.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2018] [Revised: 11/26/2018] [Accepted: 11/26/2018] [Indexed: 12/21/2022]
Abstract
Studies conducted to verify learning-induced changes anticipated from Hebb's postulate led to the finding of long-term potentiation (LTP). Even though several correlations have been found between behavioural markers of memory retrieval and LTP, it is not known how memories are retrieved using learning-induced changes. In this context, the following non-correlated findings between learning and LTP induction provide constraints for discovering the mechanism: 1) Requirement of high stimulus intensity for LTP induction in contrast to what is expected for a learning mechanism, 2) Delay of at least 20 to 30 s from stimulation to LTP induction, in contrast to mere milliseconds for associative learning, and 3) A sudden drop in peak-potentiated effect (short-term potentiation) that matches with short-lasting changes expected during working memory and occurs only at the time of delayed LTP induction. When memories are viewed as first-person internal sensations, a newly uncovered mechanism provides explanation for the relationship between memory and LTP. This work interconnects large number of findings from the fields of neuroscience and psychology and provides a further verifiable mechanism of learning.
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28
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Molotkovsky RJ, Alexandrova VV, Galimzyanov TR, Jiménez-Munguía I, Pavlov KV, Batishchev OV, Akimov SA. Lateral Membrane Heterogeneity Regulates Viral-Induced Membrane Fusion during HIV Entry. Int J Mol Sci 2018; 19:ijms19051483. [PMID: 29772704 PMCID: PMC5983600 DOI: 10.3390/ijms19051483] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 05/08/2018] [Accepted: 05/14/2018] [Indexed: 11/16/2022] Open
Abstract
Sphingomyelin- and cholesterol- enriched membrane domains, commonly referred to as “rafts” play a crucial role in a large number of intra- and intercellular processes. Recent experiments suggest that not only the volumetric inhomogeneity of lipid distribution in rafts, but also the arrangement of the 1D boundary between the raft and the surrounding membrane is important for the membrane-associated processes. The reason is that the boundary preferentially recruits different peptides, such as HIV (human immunodeficiency virus) fusion peptide. In the present work, we report a theoretical investigation of mechanisms of influence of the raft boundary arrangement upon virus-induced membrane fusion. We theoretically predict that the raft boundary can act as an attractor for viral fusion peptides, which preferentially distribute into the vicinity of the boundary, playing the role of ‘line active components’ of the membrane (‘linactants’). We have calculated the height of the fusion energy barrier and demonstrated that, in the case of fusion between HIV membrane and the target cell, presence of the raft boundary in the vicinity of the fusion site facilitates fusion. The results we obtained can be further generalized to be applicable to other enveloped viruses.
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Affiliation(s)
- Rodion J Molotkovsky
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia.
| | - Veronika V Alexandrova
- Faculty of Physics, M.V. Lomonosov Moscow State University, 1-2 Leninskie Gory, 119991 Moscow, Russia.
| | - Timur R Galimzyanov
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 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.
| | - Irene Jiménez-Munguía
- Department of Engineering of Technological Equipment, National University of Science and Technology "MISiS", 4 Leninskiy Prospekt, 119049 Moscow, Russia.
| | - Konstantin V Pavlov
- Laboratory of Electrophysiology, Federal Clinical Center of Physical-Chemical Medicine of FMBA, 1a Malaya Pirogovskaya Street, 119435 Moscow, Russia.
| | - 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.
- Department of Physics of Living Systems, Moscow Institute of Physics and Technology (State University), 9 Institutskiy Lane, Dolgoprudniy, 141700 Moscow Region, Russia.
| | - 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.
- Department of Theoretical Physics and Quantum Technologies, National University of Science and Technology "MISiS", 4 Leninskiy Prospekt, 119049 Moscow, Russia.
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29
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Akimov SA, Polynkin MA, Jiménez-Munguía I, Pavlov KV, Batishchev OV. Phosphatidylcholine Membrane Fusion Is pH-Dependent. Int J Mol Sci 2018; 19:ijms19051358. [PMID: 29751591 PMCID: PMC5983597 DOI: 10.3390/ijms19051358] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 04/26/2018] [Accepted: 04/30/2018] [Indexed: 12/12/2022] Open
Abstract
Membrane fusion mediates multiple vital processes in cell life. Specialized proteins mediate the fusion process, and a substantial part of their energy is used for topological rearrangement of the membrane lipid matrix. Therefore, the elastic parameters of lipid bilayers are of crucial importance for fusion processes and for determination of the energy barriers that have to be crossed for the process to take place. In the case of fusion of enveloped viruses (e.g., influenza) with endosomal membrane, the interacting membranes are in an acidic environment, which can affect the membrane’s mechanical properties. This factor is often neglected in the analysis of virus-induced membrane fusion. In the present work, we demonstrate that even for membranes composed of zwitterionic lipids, changes of the environmental pH in the physiologically relevant range of 4.0 to 7.5 can affect the rate of the membrane fusion notably. Using a continual model, we demonstrated that the key factor defining the height of the energy barrier is the spontaneous curvature of the lipid monolayer. Changes of this parameter are likely to be caused by rearrangements of the polar part of lipid molecules in response to changes of the pH of the aqueous solution bathing the membrane.
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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.
- Department of Theoretical Physics and Quantum Technologies, National University of Science and Technology "MISiS", 4 Leninskiy Prospekt, 119049 Moscow, Russia.
| | - Michael A Polynkin
- Laboratory of Bioelectrochemistry, A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/4 Leninskiy Prospekt, 119071 Moscow, Russia.
| | - Irene Jiménez-Munguía
- Department of Engineering of Technological Equipment, National University of Science and Technology "MISiS", 4 Leninskiy Prospekt, 119049 Moscow, Russia.
| | - Konstantin V Pavlov
- Laboratory of Electrophysiology, Federal Clinical Center of Physical-Chemical Medicine of FMBA, 1a Malaya Pirogovskaya Street, 119435 Moscow, Russia.
| | - 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.
- Department of Physics of Living Systems, Moscow Institute of Physics and Technology (State University), 9 Institutskiy Lane, 141700 Dolgoprudniy Moscow Region, Russia.
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30
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Abstract
Cell-cell fusion is essential for fertilization and organ development. Dedicated proteins known as fusogens are responsible for mediating membrane fusion. However, until recently, these proteins either remained unidentified or were poorly understood at the mechanistic level. Here, we review how fusogens surmount multiple energy barriers to mediate cell-cell fusion. We describe how early preparatory steps bring membranes to a distance of ∼10 nm, while fusogens act in the final approach between membranes. The mechanical force exerted by cell fusogens and the accompanying lipidic rearrangements constitute the hallmarks of cell-cell fusion. Finally, we discuss the relationship between viral and eukaryotic fusogens, highlight a classification scheme regrouping a superfamily of fusogens called Fusexins, and propose new questions and avenues of enquiry.
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Affiliation(s)
- Javier M Hernández
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Benjamin Podbilewicz
- Department of Biology, Technion - Israel Institute of Technology, Haifa 32000, Israel
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31
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Switching between Successful and Dead-End Intermediates in Membrane Fusion. Int J Mol Sci 2017; 18:ijms18122598. [PMID: 29207481 PMCID: PMC5751201 DOI: 10.3390/ijms18122598] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 11/21/2017] [Accepted: 12/01/2017] [Indexed: 11/16/2022] Open
Abstract
Fusion of cellular membranes during normal biological processes, including proliferation, or synaptic transmission, is mediated and controlled by sophisticated protein machinery ensuring the preservation of the vital barrier function of the membrane throughout the process. Fusion of virus particles with host cell membranes is more sparingly arranged and often mediated by a single fusion protein, and the virus can afford to be less discriminative towards the possible different outcomes of fusion attempts. Formation of leaky intermediates was recently observed in some fusion processes, and an alternative trajectory of the process involving formation of π-shaped structures was suggested. In this study, we apply the methods of elasticity theory and Lagrangian formalism augmented by phenomenological and molecular geometry constraints and boundary conditions to investigate the traits of this trajectory and the drivers behind the choice of one of the possible scenarios depending on the properties of the system. The alternative pathway proved to be a dead end, and, depending on the parameters of the participating membranes and fusion proteins, the system can either reversibly enter the corresponding “leaky” configuration or be trapped in it. A parametric study in the biologically relevant range of variables emphasized the fusion protein properties crucial for the choice of the fusion scenario.
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32
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Kowalik B, Schlaich A, Kanduč M, Schneck E, Netz RR. Hydration Repulsion Difference between Ordered and Disordered Membranes Due to Cancellation of Membrane-Membrane and Water-Mediated Interactions. J Phys Chem Lett 2017; 8:2869-2874. [PMID: 28590133 DOI: 10.1021/acs.jpclett.7b00977] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hydration repulsion acts between all sufficiently polar surfaces in water at small separations and prevents dry adhesion up to kilobar pressures. Yet it remained unclear whether this ubiquitous force depends on surface structure or is a sole water property. We demonstrate that previous deviations among different experimental measurements of hydration pressures in phospholipid bilayer stacks disappear when plotting data consistently as a function of repeat distance or membrane surface distance. The resulting pressure versus distance curves agree quantitatively with our atomistic simulation results and exhibit different decay lengths in the ordered gel and the disordered fluid states. This suggests that hydration forces are not caused by water ordering effects alone. Splitting the simulated total pressure into membrane-membrane and water-mediated parts shows that these contributions are opposite in sign and of similar magnitude, thus they are equally important. The resulting net hydration pressure between membranes is what remains from the near-cancellation of these ambivalent contributions.
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Affiliation(s)
- Bartosz Kowalik
- Department of Physics, Freie Universität Berlin , 14195 Berlin, Germany
| | | | - Matej Kanduč
- Institut für Weiche Materie und Funktionale Materialien, Helmholtz-Zentrum Berlin , 14109 Berlin, Germany
| | - Emanuel Schneck
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces , 14476 Potsdam, Germany
| | - Roland R Netz
- Department of Physics, Freie Universität Berlin , 14195 Berlin, Germany
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33
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Briscoe WH. Aqueous boundary lubrication: Molecular mechanisms, design strategy, and terra incognita. Curr Opin Colloid Interface Sci 2017. [DOI: 10.1016/j.cocis.2016.09.002] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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34
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Basso LGM, Vicente EF, Crusca E, Cilli EM, Costa-Filho AJ. SARS-CoV fusion peptides induce membrane surface ordering and curvature. Sci Rep 2016; 6:37131. [PMID: 27892522 PMCID: PMC5125003 DOI: 10.1038/srep37131] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 10/24/2016] [Indexed: 12/23/2022] Open
Abstract
Viral membrane fusion is an orchestrated process triggered by membrane-anchored viral fusion glycoproteins. The S2 subunit of the spike glycoprotein from severe acute respiratory syndrome (SARS) coronavirus (CoV) contains internal domains called fusion peptides (FP) that play essential roles in virus entry. Although membrane fusion has been broadly studied, there are still major gaps in the molecular details of lipid rearrangements in the bilayer during fusion peptide-membrane interactions. Here we employed differential scanning calorimetry (DSC) and electron spin resonance (ESR) to gather information on the membrane fusion mechanism promoted by two putative SARS FPs. DSC data showed the peptides strongly perturb the structural integrity of anionic vesicles and support the hypothesis that the peptides generate opposing curvature stresses on phosphatidylethanolamine membranes. ESR showed that both FPs increase lipid packing and head group ordering as well as reduce the intramembrane water content for anionic membranes. Therefore, bending moment in the bilayer could be generated, promoting negative curvature. The significance of the ordering effect, membrane dehydration, changes in the curvature properties and the possible role of negatively charged phospholipids in helping to overcome the high kinetic barrier involved in the different stages of the SARS-CoV-mediated membrane fusion are discussed.
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Affiliation(s)
- Luis G M Basso
- Grupo de Biofísica Molecular Sérgio Mascarenhas, Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, Centro, São Carlos, SP, Brazil.,Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo. Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil
| | - Eduardo F Vicente
- Faculdade de Ciências e Engenharia, UNESP - Univ Estadual Paulista, Campus de Tupã. Rua Domingos da Costa Lopes, 780, 17602-496, Tupã, SP, Brazil
| | - Edson Crusca
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, UNESP - Univ Estadual Paulista. Rua Prof. Franscisco Degni, 55, 14800-900, Araraquara, SP, Brazil
| | - Eduardo M Cilli
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, UNESP - Univ Estadual Paulista. Rua Prof. Franscisco Degni, 55, 14800-900, Araraquara, SP, Brazil
| | - Antonio J Costa-Filho
- Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo. Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil
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35
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Kawamoto S, Klein ML, Shinoda W. Coarse-grained molecular dynamics study of membrane fusion: Curvature effects on free energy barriers along the stalk mechanism. J Chem Phys 2016; 143:243112. [PMID: 26723597 DOI: 10.1063/1.4933087] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The effects of membrane curvature on the free energy barrier for membrane fusion have been investigated using coarse-grained molecular dynamics (CG-MD) simulations, assuming that fusion takes place through a stalk intermediate. Free energy barriers were estimated for stalk formation as well as for fusion pore formation using the guiding potential method. Specifically, the three different geometries of two apposed membranes were considered: vesicle-vesicle, vesicle-planar, and planar-planar membranes. The free energy barriers for the resulting fusion were found to depend importantly on the fusing membrane geometries; the lowest barrier was obtained for vesicular membranes. Further, lipid sorting was observed in fusion of the mixed membranes of dimyristoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine (DOPE). Specifically, DOPE molecules were found to assemble around the stalk to support the highly negative curved membrane surface. A consistent result for lipid sorting was observed when a simple continuum model (CM) was used, where the Helfrich energy and mixing entropy of the lipids were taken into account. However, the CM predicts a much higher free energy barrier than found using CG-MD. This discrepancy originates from the conformational changes of lipids, which were not considered in the CM. The results of the CG-MD simulations reveal that a large conformational change in the lipid takes place around the stalk region, which results in a reduction of free energy barriers along the stalk mechanism of membrane fusion.
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Affiliation(s)
- Shuhei Kawamoto
- Department of Applied Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
| | - Michael L Klein
- Institute for Computational Molecular Science, Temple University, SERC Building 1925 North 12th Street, Philadelphia, Pennsylvania 19122, USA
| | - Wataru Shinoda
- Department of Applied Chemistry, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603, Japan
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36
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Vadakkan KI. Neurodegenerative disorders share common features of "loss of function" states of a proposed mechanism of nervous system functions. Biomed Pharmacother 2016; 83:412-430. [PMID: 27424323 DOI: 10.1016/j.biopha.2016.06.042] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 06/07/2016] [Accepted: 06/25/2016] [Indexed: 12/11/2022] Open
Abstract
Neurodegenerative disorders are highly heterogeneous for the locations affected and the nature of the aggregated proteins. Nearly 80% of the neurodegenerative disorders occur sporadically, indicating that certain factors must combine to initiate the degenerative changes. The contiguous extension of degenerative changes from cell to cell, the association with viral fusion proteins, loss of dendritic spines (postsynaptic terminals), and the eventual degeneration of cells indicate the presence of a unique mechanism for inter-cellular spread of pathology. It is not known whether the "loss of function" states of the still unknown normal nervous system operations can lead to neurodegenerative disorders. Here, the possible loss of function states of a proposed normal nervous system function are examined. A reversible inter-postsynaptic functional LINK (IPL) mechanism, consisting of transient inter-postsynaptic membrane (IPM) hydration exclusion and partial to complete IPM hemifusions, was proposed as a critical step necessary for the binding process and the induction of internal sensations of higher brain functions. When various findings from different neurodegenerative disorders are systematically organized and examined, disease features match the effects of loss of function states of different IPLs. Changes in membrane composition, enlargement of dendritic spines by dopamine and viral fusion proteins are capable of altering the IPLs to form IPM fusion. The latter can lead to the observed lateral spread of pathology, inter-neuronal cytoplasmic content mixing and abnormal protein aggregation. Since both the normal mechanism of reversible IPM hydration exclusion and the pathological process of transient IPM fusion can evade detection, testing their occurrence may provide preventive and therapeutic opportunities for these disorders.
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37
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Vadakkan KI. A framework for the first-person internal sensation of visual perception in mammals and a comparable circuitry for olfactory perception in Drosophila. SPRINGERPLUS 2015; 4:833. [PMID: 26753120 PMCID: PMC4695467 DOI: 10.1186/s40064-015-1568-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 11/26/2015] [Indexed: 02/02/2023]
Abstract
Perception is a first-person internal sensation induced within the nervous system at the time of arrival of sensory stimuli from objects in the environment. Lack of access to the first-person properties has limited viewing perception as an emergent property and it is currently being studied using third-person observed findings from various levels. One feasible approach to understand its mechanism is to build a hypothesis for the specific conditions and required circuit features of the nodal points where the mechanistic operation of perception take place for one type of sensation in one species and to verify it for the presence of comparable circuit properties for perceiving a different sensation in a different species. The present work explains visual perception in mammalian nervous system from a first-person frame of reference and provides explanations for the homogeneity of perception of visual stimuli above flicker fusion frequency, the perception of objects at locations different from their actual position, the smooth pursuit and saccadic eye movements, the perception of object borders, and perception of pressure phosphenes. Using results from temporal resolution studies and the known details of visual cortical circuitry, explanations are provided for (a) the perception of rapidly changing visual stimuli, (b) how the perception of objects occurs in the correct orientation even though, according to the third-person view, activity from the visual stimulus reaches the cortices in an inverted manner and (c) the functional significance of well-conserved columnar organization of the visual cortex. A comparable circuitry detected in a different nervous system in a remote species-the olfactory circuitry of the fruit fly Drosophila melanogaster-provides an opportunity to explore circuit functions using genetic manipulations, which, along with high-resolution microscopic techniques and lipid membrane interaction studies, will be able to verify the structure-function details of the presented mechanism of perception.
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Affiliation(s)
- Kunjumon I Vadakkan
- Division of Neurology, Department of Medicine, University of Toronto, Sunnybrook health Sciences Centre, 2075 Bayview Ave. Room A4-08, Toronto, ON M4N3M5 Canada ; Neurosearch Center, 76 Henry St., Toronto, ON M5T1X2 Canada
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38
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Demurtas D, Guichard P, Martiel I, Mezzenga R, Hébert C, Sagalowicz L. Direct visualization of dispersed lipid bicontinuous cubic phases by cryo-electron tomography. Nat Commun 2015; 6:8915. [PMID: 26573367 DOI: 10.1038/ncomms9915] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 10/16/2015] [Indexed: 02/08/2023] Open
Abstract
Bulk and dispersed cubic liquid crystalline phases (cubosomes), present in the body and in living cell membranes, are believed to play an essential role in biological phenomena. Moreover, their biocompatibility is attractive for nutrient or drug delivery system applications. Here the three-dimensional organization of dispersed cubic lipid self-assembled phases is fully revealed by cryo-electron tomography and compared with simulated structures. It is demonstrated that the interior is constituted of a perfect bicontinuous cubic phase, while the outside shows interlamellar attachments, which represent a transition state between the liquid crystalline interior phase and the outside vesicular structure. Therefore, compositional gradients within cubosomes are inferred, with a lipid bilayer separating at least one water channel set from the external aqueous phase. This is crucial to understand and enhance controlled release of target molecules and calls for a revision of postulated transport mechanisms from cubosomes to the aqueous phase.
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Affiliation(s)
- Davide Demurtas
- Interdisciplinary Centre for Electron Microscopy, Swiss Federal Institute of Technology (EPFL), Lausanne 1015, Switzerland
| | - Paul Guichard
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Swiss Federal Institute of Technology (EPFL), Lausanne 1015, Switzerland
| | - Isabelle Martiel
- Department of Health Science and Technology, ETH Zurich, Zurich 8092, Switzerland
| | - Raffaele Mezzenga
- Department of Health Science and Technology, ETH Zurich, Zurich 8092, Switzerland
| | - Cécile Hébert
- Interdisciplinary Centre for Electron Microscopy, Swiss Federal Institute of Technology (EPFL), Lausanne 1015, Switzerland
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39
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Vadakkan KI. A pressure-reversible cellular mechanism of general anesthetics capable of altering a possible mechanism for consciousness. SPRINGERPLUS 2015; 4:485. [PMID: 26380161 PMCID: PMC4561946 DOI: 10.1186/s40064-015-1283-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 08/28/2015] [Indexed: 12/20/2022]
Abstract
Different anesthetics are known to modulate different types of membrane-bound receptors. Their common mechanism of action is expected to alter the mechanism for consciousness. Consciousness is hypothesized as the integral of all the units of internal sensations induced by reactivation of inter-postsynaptic membrane functional LINKs during mechanisms that lead to oscillating potentials. The thermodynamics of the spontaneous lateral curvature of lipid membranes induced by lipophilic anesthetics can lead to the formation of non-specific inter-postsynaptic membrane functional LINKs by different mechanisms. These include direct membrane contact by excluding the inter-membrane hydrophilic region and readily reversible partial membrane hemifusion. The constant reorganization of the lipid membranes at the lateral edges of the postsynaptic terminals (dendritic spines) resulting from AMPA receptor-subunit vesicle exocytosis and endocytosis can favor the effect of anesthetic molecules on lipid membranes at this location. Induction of a large number of non-specific LINKs can alter the conformation of the integral of the units of internal sensations that maintain consciousness. Anesthetic requirement is reduced in the presence of dopamine that causes enlargement of dendritic spines. Externally applied pressure can transduce from the middle ear through the perilymph, cerebrospinal fluid, and the recently discovered glymphatic pathway to the extracellular matrix space, and finally to the paravenular space. The pressure gradient reduce solubility and displace anesthetic molecules from the membranes into the paravenular space, explaining the pressure reversal of anesthesia. Changes in membrane composition and the conversion of membrane hemifusion to fusion due to defects in the checkpoint mechanisms can lead to cytoplasmic content mixing between neurons and cause neurodegenerative changes. The common mechanism of anesthetics presented here can operate along with the known specific actions of different anesthetics.
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Affiliation(s)
- Kunjumon I Vadakkan
- Division of Neurology, Department of Medicine, University of Toronto, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, Room A4-08, Toronto, ON M4N 3M5 Canada
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40
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Galimzyanov TR, Molotkovsky RJ, Bozdaganyan ME, Cohen FS, Pohl P, Akimov SA. Elastic Membrane Deformations Govern Interleaflet Coupling of Lipid-Ordered Domains. PHYSICAL REVIEW LETTERS 2015; 115:088101. [PMID: 26340212 PMCID: PMC4750487 DOI: 10.1103/physrevlett.115.088101] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Indexed: 05/19/2023]
Abstract
The mechanism responsible for domain registration in two membrane leaflets has thus far remained enigmatic. Using continuum elasticity theory, we show that minimum line tension is achieved along the rim between thicker (ordered) and thinner (disordered) domains by shifting the rims in opposing leaflets by a few nanometers relative to each other. Increasing surface tension yields an increase in line tension, resulting in larger domains. Because domain registration is driven by lipid deformation energy, it does not require special lipid components or interactions at the membrane midplane.
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Affiliation(s)
- Timur R Galimzyanov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy prospekt, Moscow 119071, Russia
- National University of Science and Technology "MISiS", 4 Leninskiy prospekt, Moscow 119049, Russia
| | - Rodion J Molotkovsky
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy prospekt, Moscow 119071, Russia
| | - Marine E Bozdaganyan
- M.V. Lomonosov Moscow State University, 1 Leninskie Gory, Moscow 119991, Russia
- Federal Research Clinical Center of the Specialized Types of Health Care and Medical Technologies FMBA of Russia, 28 Orekhovyi bulvar, Moscow 115692, Russia
| | - Fredric S Cohen
- Rush University Medical Center, 1750 W. Harrison Street, Chicago, Illinois 60612, USA
| | - Peter Pohl
- Institute of Biophysics, Johannes Kepler University Linz, Gruberstrasse 40-42, Linz 4020, Austria
| | - Sergey A Akimov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31/5 Leninskiy prospekt, Moscow 119071, Russia
- National University of Science and Technology "MISiS", 4 Leninskiy prospekt, Moscow 119049, Russia
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41
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Al-Dossary AA, Bathala P, Caplan JL, Martin-DeLeon PA. Oviductosome-Sperm Membrane Interaction in Cargo Delivery: DETECTION OF FUSION AND UNDERLYING MOLECULAR PLAYERS USING THREE-DIMENSIONAL SUPER-RESOLUTION STRUCTURED ILLUMINATION MICROSCOPY (SR-SIM). J Biol Chem 2015; 290:17710-17723. [PMID: 26023236 DOI: 10.1074/jbc.m114.633156] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Indexed: 11/06/2022] Open
Abstract
Oviductosomes ((OVS), exosomes/microvesicles), which deliver the Ca(2+) efflux pump, plasma membrane Ca(2+)ATPase 4 (PMCA4), to sperm are likely to play an important role in sperm fertilizing ability (Al-Dossary, A. A., Strehler, E. E., and Martin-DeLeon, P. A. (2013) PloS one 8, e80181). It is unknown how exosomes/microvesicles deliver transmembrane proteins such as PMCA4 to sperm. Here we define a novel experimental approach for the assessment of the interaction of OVS with sperm at a nanoscale level, using a lipophilic dye (FM4-64FX) and three-dimensional SR/SIM, which has an 8-fold increase in volumetric resolution, compared with conventional confocal microscopy. Coincubation assays detected fusion of prelabeled OVS with sperm, primarily over the head and midpiece. Immunofluorescence revealed oviductosomal delivery of PMCA4a to WT and Pmca4 KO sperm, and also endogenous PMCA4a on the inner acrosomal membrane. Fusion was confirmed by transmission immunoelectron microscopy, showing immunogold particles in OVS, and fusion stalks on sperm membrane. Immunofluorescence colocalized OVS with the αv integrin subunit which, along with CD9, resides primarily on the sperm head and midpiece. In capacitated and acrosome reacted sperm, fusion was significantly (p < 0.001) inhibited by blocking integrin/ligand interactions via antibodies, exogenous ligands (vitronectin and fibronectin), and their RGD recognition motif. Our results provide evidence that receptor/ligand interactions, involving αvβ3 and α5β1integrins on sperm and OVS, facilitate fusion of OVS in the delivery of transmembrane proteins to sperm. The mechanism uncovered is likely to be also involved in cargo delivery of prostasomes, epididymosomes, and uterosomes.
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Affiliation(s)
- Amal A Al-Dossary
- Department of Biological Sciences, University of Delaware, Newark, Delaware 19716
| | - Pradeepthi Bathala
- Department of Biological Sciences, University of Delaware, Newark, Delaware 19716
| | - Jeffrey L Caplan
- Department of Biological Sciences, University of Delaware, Newark, Delaware 19716; Delaware Biotechnology Institute, Newark, Delaware 19711
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42
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Pronk S, Lindahl E, Kasson PM. Coupled diffusion in lipid bilayers upon close approach. J Am Chem Soc 2015; 137:708-14. [PMID: 25535654 PMCID: PMC4308745 DOI: 10.1021/ja508803d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Indexed: 11/28/2022]
Abstract
Biomembrane interfaces create regions of slowed water dynamics in their vicinity. When two lipid bilayers come together, this effect is further accentuated, and the associated slowdown can affect the dynamics of larger-scale processes such as membrane fusion. We have used molecular dynamics simulations to examine how lipid and water dynamics are affected as two lipid bilayers approach each other. These two interacting fluid systems, lipid and water, both slow and become coupled when the lipid membranes are separated by a thin water layer. We show in particular that the water dynamics become glassy, and diffusion of lipids in the apposed leaflets becomes coupled across the water layer, while the "outer" leaflets remain unaffected. This dynamic coupling between bilayers appears mediated by lipid-water-lipid hydrogen bonding, as it occurs at bilayer separations where water-lipid hydrogen bonds become more common than water-water hydrogen bonds. We further show that such coupling occurs in simulations of vesicle-vesicle fusion prior to the fusion event itself. Such altered dynamics at membrane-membrane interfaces may both stabilize the interfacial contact and slow fusion stalk formation within the interface region.
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Affiliation(s)
- Sander Pronk
- 'Department
of Theoretical Physics, KTH Royal Institute
of Technology, AlbaNova, 106 91 Stockholm, Sweden
| | - Erik Lindahl
- 'Department
of Theoretical Physics, KTH Royal Institute
of Technology, AlbaNova, 106 91 Stockholm, Sweden
- Science
for Life Laboratory, 171
21 Stockholm, Sweden
| | - Peter M. Kasson
- Department
of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908, United States
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Affiliation(s)
- Benjamin Podbilewicz
- Department of Biology, Technion–Israel Institute of Technology, Haifa 32000, Israel;
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Akimov SA, Molotkovsky RJ, Galimzyanov TR, Radaev AV, Shilova LA, Kuzmin PI, Batishchev OV, Voronina GF, Chizmadzhev YA. Model of membrane fusion: Continuous transition to fusion pore with regard of hydrophobic and hydration interactions. BIOCHEMISTRY (MOSCOW) SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2014. [DOI: 10.1134/s1990747814010024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Molotkovsky RJ, Akimov SA. Stabilization of a complex of fusion proteins by membrane deformations. Biophysics (Nagoya-shi) 2013. [DOI: 10.1134/s0006350913050096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Synaptotagmins 1 and 2 as mediators of rapid exocytosis at nerve terminals: The dyad hypothesis. J Theor Biol 2013; 332:149-60. [DOI: 10.1016/j.jtbi.2013.04.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 04/24/2013] [Indexed: 11/16/2022]
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Shnyrova AV, Bashkirov PV, Akimov SA, Pucadyil TJ, Zimmerberg J, Schmid SL, Frolov VA. Geometric catalysis of membrane fission driven by flexible dynamin rings. Science 2013; 339:1433-6. [PMID: 23520112 PMCID: PMC3980720 DOI: 10.1126/science.1233920] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Biological membrane fission requires protein-driven stress. The guanosine triphosphatase (GTPase) dynamin builds up membrane stress by polymerizing into a helical collar that constricts the neck of budding vesicles. How this curvature stress mediates nonleaky membrane remodeling is actively debated. Using lipid nanotubes as substrates to directly measure geometric intermediates of the fission pathway, we found that GTP hydrolysis limits dynamin polymerization into short, metastable collars that are optimal for fission. Collars as short as two rungs translated radial constriction to reversible hemifission via membrane wedging of the pleckstrin homology domains (PHDs) of dynamin. Modeling revealed that tilting of the PHDs to conform with membrane deformations creates the low-energy pathway for hemifission. This local coordination of dynamin and lipids suggests how membranes can be remodeled in cells.
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Affiliation(s)
- Anna V. Shnyrova
- Biophysics Unit (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain
| | - Pavel V. Bashkirov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow 119991, Russia
| | - Sergey A. Akimov
- A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow 119991, Russia
| | | | - Joshua Zimmerberg
- Program in Physical Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sandra L. Schmid
- Department of Cell Biology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Vadim A. Frolov
- Biophysics Unit (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country, Leioa, Spain
- IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
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Mondal Roy S, Sarkar M. Membrane fusion induced by small molecules and ions. J Lipids 2011; 2011:528784. [PMID: 21660306 PMCID: PMC3108104 DOI: 10.1155/2011/528784] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Revised: 01/28/2011] [Accepted: 02/25/2011] [Indexed: 01/11/2023] Open
Abstract
Membrane fusion is a key event in many biological processes. These processes are controlled by various fusogenic agents of which proteins and peptides from the principal group. The fusion process is characterized by three major steps, namely, inter membrane contact, lipid mixing forming the intermediate step, pore opening and finally mixing of inner contents of the cells/vesicles. These steps are governed by energy barriers, which need to be overcome to complete fusion. Structural reorganization of big molecules like proteins/peptides, supplies the required driving force to overcome the energy barrier of the different intermediate steps. Small molecules/ions do not share this advantage. Hence fusion induced by small molecules/ions is expected to be different from that induced by proteins/peptides. Although several reviews exist on membrane fusion, no recent review is devoted solely to small moleculs/ions induced membrane fusion. Here we intend to present, how a variety of small molecules/ions act as independent fusogens. The detailed mechanism of some are well understood but for many it is still an unanswered question. Clearer understanding of how a particular small molecule can control fusion will open up a vista to use these moleucles instead of proteins/peptides to induce fusion both in vivo and in vitro fusion processes.
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Affiliation(s)
- Sutapa Mondal Roy
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Sector 1, Block AF, Bidhannagar, Kolkata 700064, India
| | - Munna Sarkar
- Chemical Sciences Division, Saha Institute of Nuclear Physics, Sector 1, Block AF, Bidhannagar, Kolkata 700064, India
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Nikolaus J, Warner JM, O'Shaughnessy B, Herrmann A. The pathway to membrane fusion through hemifusion. CURRENT TOPICS IN MEMBRANES 2011; 68:1-32. [PMID: 21771493 DOI: 10.1016/b978-0-12-385891-7.00001-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Jörg Nikolaus
- Department of Biology, Faculty of Mathematics and Natural Sciences I, Humboldt-University Berlin, Berlin, Germany
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Kasson PM, Lindahl E, Pande VS. Atomic-resolution simulations predict a transition state for vesicle fusion defined by contact of a few lipid tails. PLoS Comput Biol 2010; 6:e1000829. [PMID: 20585620 PMCID: PMC2891707 DOI: 10.1371/journal.pcbi.1000829] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Accepted: 05/21/2010] [Indexed: 11/30/2022] Open
Abstract
Membrane fusion is essential to both cellular vesicle trafficking and infection by enveloped viruses. While the fusion protein assemblies that catalyze fusion are readily identifiable, the specific activities of the proteins involved and nature of the membrane changes they induce remain unknown. Here, we use many atomic-resolution simulations of vesicle fusion to examine the molecular mechanisms for fusion in detail. We employ committor analysis for these million-atom vesicle fusion simulations to identify a transition state for fusion stalk formation. In our simulations, this transition state occurs when the bulk properties of each lipid bilayer remain in a lamellar state but a few hydrophobic tails bulge into the hydrophilic interface layer and make contact to nucleate a stalk. Additional simulations of influenza fusion peptides in lipid bilayers show that the peptides promote similar local protrusion of lipid tails. Comparing these two sets of simulations, we obtain a common set of structural changes between the transition state for stalk formation and the local environment of peptides known to catalyze fusion. Our results thus suggest that the specific molecular properties of individual lipids are highly important to vesicle fusion and yield an explicit structural model that could help explain the mechanism of catalysis by fusion proteins. Membrane fusion is a common underlying process critical to neurotransmitter release, cellular trafficking, and infection by many viruses. Proteins have been identified that catalyze fusion, and mutations to these proteins have yielded important information on how fusion occurs. However, the precise mechanism by which membrane fusion begins is the subject of active investigation. We have used atomic-resolution simulations to model the process of vesicle fusion and to identify a transition state for the formation of an initial fusion stalk. Doing so required substantial technical advances in combining high-performance simulation and distributed computing to analyze the transition state of a complex reaction in a large system. The transition state we identify in our simulations involves specific structural changes by a few lipid molecules. We also simulate fusion peptides from influenza hemagglutinin and show that they promote the same structural changes as are required for fusion in our model. We therefore hypothesize that these changes to individual lipid molecules may explain a portion of the catalytic activity of fusion proteins such as influenza hemagglutinin.
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Affiliation(s)
- Peter M. Kasson
- Department of Chemistry, Stanford University, Stanford, California, United States of America
- Center for Biomembrane Research, Stockholm University, Stockholm, Sweden
| | - Erik Lindahl
- Center for Biomembrane Research, Stockholm University, Stockholm, Sweden
| | - Vijay S. Pande
- Department of Chemistry, Stanford University, Stanford, California, United States of America
- * E-mail:
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