1
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Ngo VN, Winski DP, Aho B, Kamath PL, King BL, Waters H, Zimmerberg J, Sodt A, Hess ST. Conserved sequence features in intracellular domains of viral spike proteins. Virology 2024; 599:110198. [PMID: 39116647 DOI: 10.1016/j.virol.2024.110198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 07/23/2024] [Accepted: 07/31/2024] [Indexed: 08/10/2024]
Abstract
Viral spike proteins mutate frequently, but conserved features within these proteins often have functional importance and can inform development of anti-viral therapies which circumvent the effects of viral sequence mutations. Through analysis of large numbers of viral spike protein sequences from several viral families, we found highly (>99%) conserved patterns within their intracellular domains. The patterns generally consist of one or more basic amino acids (arginine or lysine) adjacent to a cysteine, many of which are known to undergo acylation. These patterns were not enriched in cellular proteins in general. Molecular dynamics simulations show direct electrostatic and hydrophobic interactions between these conserved residues in hemagglutinin (HA) from influenza A and B and the phosphoinositide PIP2. Super-resolution microscopy shows nanoscale colocalization of PIP2 and several of the same viral proteins. We propose the hypothesis that these conserved viral spike protein features can interact with phosphoinositides such as PIP2.
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Affiliation(s)
- Vinh-Nhan Ngo
- Department of Physics and Astronomy, 120 Bennett Hall, University of Maine, Orono, ME, 04469-5709, USA
| | - David P Winski
- Department of Physics and Astronomy, 120 Bennett Hall, University of Maine, Orono, ME, 04469-5709, USA
| | - Brandon Aho
- Department of Physics and Astronomy, 120 Bennett Hall, University of Maine, Orono, ME, 04469-5709, USA
| | - Pauline L Kamath
- School of Food and Agriculture, 342 Hitchner Hall, University of Maine, And Maine Center for Genetics in the Environment, Orono, ME, USA.
| | - Benjamin L King
- Department of Molecular and Biomedical Sciences, 5735 Hitchner Hall, University of Maine, Orono, ME, USA.
| | - Hang Waters
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Alexander Sodt
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Samuel T Hess
- Department of Physics and Astronomy, 120 Bennett Hall, University of Maine, Orono, ME, 04469-5709, USA.
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2
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Beiter J, Voth GA. Making the cut: Multiscale simulation of membrane remodeling. Curr Opin Struct Biol 2024; 87:102831. [PMID: 38740001 PMCID: PMC11283976 DOI: 10.1016/j.sbi.2024.102831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 04/17/2024] [Accepted: 04/22/2024] [Indexed: 05/16/2024]
Abstract
Biological membranes are dynamic heterogeneous materials, and their shape and organization are tightly coupled to the properties of the proteins in and around them. However, the length scales of lipid and protein dynamics are far below the size of membrane-bound organelles, much less an entire cell. Therefore, multiscale modeling approaches are often necessary to build a comprehensive picture of the interplay of these factors, and have provided critical insights into our understanding of membrane dynamics. Here, we review computational methods for studying membrane remodeling, as well as passive and active examples of protein-driven membrane remodeling. As the field advances towards the modeling of key aspects of organelles and whole cells - an increasingly accessible regime of study - we summarize here recent successes and offer comments on future trends.
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Affiliation(s)
- Jeriann Beiter
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL 60637, USA.
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3
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Kephart SM, Hom N, Lee KK. Visualizing intermediate stages of viral membrane fusion by cryo-electron tomography. Trends Biochem Sci 2024:S0968-0004(24)00160-9. [PMID: 39054240 DOI: 10.1016/j.tibs.2024.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 06/07/2024] [Accepted: 06/18/2024] [Indexed: 07/27/2024]
Abstract
Protein-mediated membrane fusion is the dynamic process where specialized protein machinery undergoes dramatic conformational changes that drive two membrane bilayers together, leading to lipid mixing and opening of a fusion pore between previously separate membrane-bound compartments. Membrane fusion is an essential stage of enveloped virus entry that results in viral genome delivery into host cells. Recent studies applying cryo-electron microscopy techniques in a time-resolved fashion provide unprecedented glimpses into the interaction of viral fusion proteins and membranes, revealing fusion intermediate states from the initiation of fusion to release of the viral genome. In combination with complementary structural, biophysical, and computation modeling approaches, these advances are shedding new light on the mechanics and dynamics of protein-mediated membrane fusion.
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Affiliation(s)
- Sally M Kephart
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA
| | - Nancy Hom
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA
| | - Kelly K Lee
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA; Biological Structure Physics and Design Graduate Program, University of Washington, Seattle, WA, USA.
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4
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Carter T, Iqbal M. The Influenza A Virus Replication Cycle: A Comprehensive Review. Viruses 2024; 16:316. [PMID: 38400091 PMCID: PMC10892522 DOI: 10.3390/v16020316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Revised: 02/15/2024] [Accepted: 02/17/2024] [Indexed: 02/25/2024] Open
Abstract
Influenza A virus (IAV) is the primary causative agent of influenza, colloquially called the flu. Each year, it infects up to a billion people, resulting in hundreds of thousands of human deaths, and causes devastating avian outbreaks with worldwide losses worth billions of dollars. Always present is the possibility that a highly pathogenic novel subtype capable of direct human-to-human transmission will spill over into humans, causing a pandemic as devastating if not more so than the 1918 influenza pandemic. While antiviral drugs for influenza do exist, they target very few aspects of IAV replication and risk becoming obsolete due to antiviral resistance. Antivirals targeting other areas of IAV replication are needed to overcome this resistance and combat the yearly epidemics, which exact a serious toll worldwide. This review aims to summarise the key steps in the IAV replication cycle, along with highlighting areas of research that need more focus.
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Affiliation(s)
- Toby Carter
- The Pirbright Institute, Ash Road, Pirbright, Woking GU24 0NF, UK;
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5
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Gonzalez KJ, Huang J, Criado MF, Banerjee A, Tompkins SM, Mousa JJ, Strauch EM. A general computational design strategy for stabilizing viral class I fusion proteins. Nat Commun 2024; 15:1335. [PMID: 38351001 PMCID: PMC10864359 DOI: 10.1038/s41467-024-45480-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: 04/04/2023] [Accepted: 01/24/2024] [Indexed: 02/16/2024] Open
Abstract
Many pathogenic viruses rely on class I fusion proteins to fuse their viral membrane with the host cell membrane. To drive the fusion process, class I fusion proteins undergo an irreversible conformational change from a metastable prefusion state to an energetically more stable postfusion state. Mounting evidence underscores that antibodies targeting the prefusion conformation are the most potent, making it a compelling vaccine candidate. Here, we establish a computational design protocol that stabilizes the prefusion state while destabilizing the postfusion conformation. With this protocol, we stabilize the fusion proteins of the RSV, hMPV, and SARS-CoV-2 viruses, testing fewer than a handful of designs. The solved structures of these designed proteins from all three viruses evidence the atomic accuracy of our approach. Furthermore, the humoral response of the redesigned RSV F protein compares to that of the recently approved vaccine in a mouse model. While the parallel design of two conformations allows the identification of energetically sub-optimal positions for one conformation, our protocol also reveals diverse molecular strategies for stabilization. Given the clinical significance of viruses using class I fusion proteins, our algorithm can substantially contribute to vaccine development by reducing the time and resources needed to optimize these immunogens.
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Affiliation(s)
- Karen J Gonzalez
- Institute of Bioinformatics, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Jiachen Huang
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
- Center for Vaccines and Immunology, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Miria F Criado
- Center for Vaccines and Immunology, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
- Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL, 36849, USA
| | - Avik Banerjee
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
- Center for Vaccines and Immunology, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Stephen M Tompkins
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
- Center for Vaccines and Immunology, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
| | - Jarrod J Mousa
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
- Center for Vaccines and Immunology, College of Veterinary Medicine, University of Georgia, Athens, GA, 30602, USA
- Department of Biochemistry and Molecular Biology, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, 30602, USA
| | - Eva-Maria Strauch
- Institute of Bioinformatics, Franklin College of Arts and Sciences, University of Georgia, Athens, GA, 30602, USA.
- Department of Pharmaceutical and Biomedical Sciences, College of Pharmacy, University of Georgia, Athens, GA, 30602, USA.
- Department of Medicine, School of Medicine, Washington University, St. Louis, MO, 63110, USA.
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6
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Bottacchiari M, Gallo M, Bussoletti M, Casciola CM. The local variation of the Gaussian modulus enables different pathways for fluid lipid vesicle fusion. Sci Rep 2024; 14:23. [PMID: 38168475 PMCID: PMC10762093 DOI: 10.1038/s41598-023-50922-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 12/28/2023] [Indexed: 01/05/2024] Open
Abstract
Viral infections, fertilization, neurotransmission, and many other fundamental biological processes rely on membrane fusion. Straightforward calculations based on the celebrated Canham-Helfrich elastic model predict a large topological energy barrier that prevents the fusion process from being thermally activated. While such high energy is in accordance with the physical barrier function of lipid membranes, it is difficult to reconcile with the biological mechanisms involved in fusion processes. In this work, we use a Ginzburg-Landau type of free energy that recovers the Canham-Helfrich model in the limit of small width-to-vesicle-extension ratio, with the additional ability to handle topological transitions. We show that a local modification of the Gaussian modulus in the merging region both dramatically lowers the elastic energy barrier and substantially changes the minimal energy pathway for fusion, in accordance with experimental evidence. Therefore, we discuss biological examples in which such a modification might play a crucial role.
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Affiliation(s)
- Matteo Bottacchiari
- Department of Mechanical and Aerospace Engineering, Sapienza Università di Roma, Rome, Italy
| | - Mirko Gallo
- Department of Mechanical and Aerospace Engineering, Sapienza Università di Roma, Rome, Italy
| | - Marco Bussoletti
- Department of Mechanical and Aerospace Engineering, Sapienza Università di Roma, Rome, Italy
| | - Carlo Massimo Casciola
- Department of Mechanical and Aerospace Engineering, Sapienza Università di Roma, Rome, Italy.
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7
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Xie P, Zhang H, Qin Y, Xiong H, Shi C, Zhou Z. Membrane Proteins and Membrane Curvature: Mutual Interactions and a Perspective on Disease Treatments. Biomolecules 2023; 13:1772. [PMID: 38136643 PMCID: PMC10741411 DOI: 10.3390/biom13121772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/30/2023] [Accepted: 12/07/2023] [Indexed: 12/24/2023] Open
Abstract
The pathogenesis of various diseases often involves an intricate interplay between membrane proteins and membrane curvature. Understanding the underlying mechanisms of this interaction could offer novel perspectives on disease treatment. In this review, we provide an introduction to membrane curvature and its association with membrane proteins. Furthermore, we delve into the impact and potential implications of this interaction in the context of disease treatment. Lastly, we discuss the prospects and challenges associated with harnessing these interactions for effective disease management, aiming to provide fresh insights into therapeutic strategies.
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Affiliation(s)
| | | | | | | | | | - Zijian Zhou
- State Key Laboratory of Vaccines for Infectious Diseases, Xiang An Biomedicine Laboratory & Center for Molecular Imaging and Translational Medicine, School of Public Health, Shenzhen Research Institute of Xiamen University, Xiamen University, Xiamen 361102, China; (P.X.); (H.Z.); (Y.Q.); (H.X.); (C.S.)
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8
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Van Doren SR, Scott BS, Koppisetti RK. SARS-CoV-2 fusion peptide sculpting of a membrane with insertion of charged and polar groups. Structure 2023; 31:1184-1199.e3. [PMID: 37625399 PMCID: PMC10592393 DOI: 10.1016/j.str.2023.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 07/10/2023] [Accepted: 07/31/2023] [Indexed: 08/27/2023]
Abstract
The fusion peptide of SARS-CoV-2 spike is essential for infection. How this charged and hydrophobic domain occupies and affects membranes needs clarification. Its depth in zwitterionic, bilayered micelles at pH 5 (resembling late endosomes) was measured by paramagnetic NMR relaxation enhancements used to bias molecular dynamics simulations. Asp830 inserted deeply, along with Lys825 or Lys835. Protonation of Asp830 appeared to enhance agreement of simulated and NMR-measured depths. While the fusion peptide occupied a leaflet of the DMPC bilayer, the opposite leaflet invaginated with influx of water and choline head groups in around Asp830 and bilayer-inserted polar side chains. NMR-detected hydrogen exchange found corroborating hydration of the backbone of Thr827-Phe833 inserted deeply in bicelles. Pinching of the membrane at the inserted charge and the intramembrane hydration of polar groups agree with theory. Formation of corridors of hydrated, inward-turned head groups was accompanied by flip-flop of head groups. Potential roles of the defects are discussed.
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Affiliation(s)
- Steven R Van Doren
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA; Institute for Data Science and Informatics, University of Missouri, Columbia, MO 65211, USA.
| | - Benjamin S Scott
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | - Rama K Koppisetti
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
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9
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Álvarez D, Sapia J, Vanni S. Computational modeling of membrane trafficking processes: From large molecular assemblies to chemical specificity. Curr Opin Cell Biol 2023; 83:102205. [PMID: 37451175 DOI: 10.1016/j.ceb.2023.102205] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 06/16/2023] [Accepted: 06/16/2023] [Indexed: 07/18/2023]
Abstract
In the last decade, molecular dynamics (MD) simulations have become an essential tool to investigate the molecular properties of membrane trafficking processes, often in conjunction with experimental approaches. The combination of MD simulations with recent developments in structural biology, such as cryo-electron microscopy and artificial intelligence-based structure determination, opens new, exciting possibilities for future investigations. However, the full potential of MD simulations to provide a molecular view of the complex and dynamic processes involving membrane trafficking can only be realized if certain limitations are addressed, and especially those concerning the quality of coarse-grain models, which, despite recent successes in describing large-scale systems, still suffer from far-from-ideal chemical accuracy. In this review, we will highlight recent success stories of MD simulations in the investigation of membrane trafficking processes, their implications for future research, and the challenges that lie ahead in this specific research domain.
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Affiliation(s)
- Daniel Álvarez
- Department of Biology, University of Fribourg, Switzerland; Departamento de Química Física y Analítica, Universidad de Oviedo, Spain
| | - Jennifer Sapia
- Department of Biology, University of Fribourg, Switzerland
| | - Stefano Vanni
- Department of Biology, University of Fribourg, Switzerland; Université Côte d'Azur, Inserm, CNRS, Institut de Pharmacologie Moléculaire et Cellulaire, Valbonne, France.
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10
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Zhang Y, Ghosh U, Xie L, Holmes D, Severin KG, Weliky DP. Lipid acyl chain protrusion induced by the influenza virus hemagglutinin fusion peptide detected by NMR paramagnetic relaxation enhancement. Biophys Chem 2023; 299:107028. [PMID: 37247572 PMCID: PMC10330521 DOI: 10.1016/j.bpc.2023.107028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 04/29/2023] [Accepted: 04/29/2023] [Indexed: 05/31/2023]
Abstract
The glycoprotein spikes of membrane-enveloped viruses include a subunit that catalyzes fusion (joining) of the viral and target cell membranes. For influenza virus, this is subunit 2 of hemagglutinin which has a ∼ 20-residue N-terminal fusion peptide (Fp) region that binds target membrane. An outstanding question is whether there are associated membrane changes important for fusion. Several computational studies have found increased "protrusion" of lipid acyl chains near Fp, i.e. one or more chain carbons are closer to the aqueous region than the headgroup phosphorus. Protrusion may accelerate initial joining of outer leaflets of the two membranes into a stalk intermediate. In this study, higher protrusion probability in membrane with vs. without Fp is convincingly detected by larger Mn2+-associated increases in chain 13C NMR transverse relaxation rates (Γ2's). Data analysis provides a ratio Γ2,neighbor/Γ2,distant for lipids neighboring vs. more distant from the Fp. The calculated ratio depends on the number of Fp-neighboring lipids and the experimentally-derived range of 4 to 24 matches the range of increased protrusion probabilities from different simulations. For samples either with or without Fp, the Γ2 values are well-fitted by an exponential decay as the 13C site moves closer to the chain terminus. The decays correlate with free-energy of protrusion proportional to the number of protruded -CH2 groups, with free energy per -CH2 of ∼0.25 kBT. The NMR data support one major fusion role of the Fp to be much greater protrusion of lipid chains, with highest protrusion probability for chain regions closest to the headgroups.
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Affiliation(s)
- Yijin Zhang
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Ujjayini Ghosh
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Li Xie
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Daniel Holmes
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Kathryn G Severin
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - David P Weliky
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
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11
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Negi G, Sharma A, Chaudhary M, Gupta D, Harshan KH, Parveen N. SARS-CoV-2 Binding to Terminal Sialic Acid of Gangliosides Embedded in Lipid Membranes. ACS Infect Dis 2023; 9:1346-1361. [PMID: 37145972 DOI: 10.1021/acsinfecdis.3c00106] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Multiple recent reports indicate that the S protein of SARS-CoV-2 specifically interacts with membrane receptors and attachment factors other than ACE2. They likely have an active role in cellular attachment and entry of the virus. In this article, we examined the binding of SARS-CoV-2 particles to gangliosides embedded in supported lipid bilayers (SLBs), mimicking the cell membrane-like environment. We show that the virus specifically binds to sialylated (sialic acid (SIA)) gangliosides, i.e., GD1a, GM3, and GM1, as determined from the acquired single-particle fluorescence images using a time-lapse total internal reflection fluorescence (TIRF) microscope. The data of virus binding events, the apparent binding rate constant, and the maximum virus coverage on the ganglioside-rich SLBs show that the virus particles have a higher binding affinity toward the GD1a and GM3 compared to the GM1 ganglioside. Enzymatic hydrolysis of the SIA-Gal bond of the gangliosides confirms that the SIA sugar unit of GD1a and GM3 is essential for virus attachment to the SLBs and even the cell surface sialic acid is critical for the cellular attachment of the virus. The structural difference between GM3/GD1a and GM1 is the presence of SIA at the main or branched chain. We conclude that the number of SIA per ganglioside can weakly influence the initial binding rate of SARS-CoV-2 particles, whereas the terminal or more exposed SIA is critical for the virus binding to the gangliosides in SLBs.
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Affiliation(s)
- Geetanjali Negi
- Department of Chemistry, Indian Institute of Technology Kanpur, 208016 Kanpur, India
| | - Anurag Sharma
- Department of Chemistry, Indian Institute of Technology Kanpur, 208016 Kanpur, India
| | - Monika Chaudhary
- Department of Chemistry, Indian Institute of Technology Kanpur, 208016 Kanpur, India
| | - Divya Gupta
- CSIR-Centre for Cellular and Molecular Biology, 500007 Hyderabad, India
| | - Krishnan H Harshan
- CSIR-Centre for Cellular and Molecular Biology, 500007 Hyderabad, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Nagma Parveen
- Department of Chemistry, Indian Institute of Technology Kanpur, 208016 Kanpur, India
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12
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Michalski M, Setny P. Two modes of fusogenic action for influenza virus fusion peptide. PLoS Comput Biol 2023; 19:e1011174. [PMID: 37235589 DOI: 10.1371/journal.pcbi.1011174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
The entry of influenza virus into the host cell requires fusion of its lipid envelope with the host membrane. It is catalysed by viral hemagglutinin protein, whose fragments called fusion peptides become inserted into the target bilayer and initiate its merging with the viral membrane. Isolated fusion peptides are already capable of inducing lipid mixing between liposomes. Years of studies indicate that upon membrane binding they form bend helical structure whose degree of opening fluctuates between tightly closed hairpin and an extended boomerang. The actual way in which they initiate fusion remains elusive. In this work we employ atomistic simulations of wild type and fusion inactive W14A mutant of influenza fusion peptides confined between two closely apposed lipid bilayers. We characterise peptide induced membrane perturbation and determine the potential of mean force for the formation of the first fusion intermediate, an interbilayer lipid bridge called stalk. Our results demonstrate two routes through which the peptides can lower free energy barrier towards fusion. The first one assumes peptides capability to adopt transmembrane configuration which subsequently promotes the creation of a stalk-hole complex. The second involves surface bound peptide configuration and proceeds owing to its ability to stabilise stalk by fitting into the region of extreme negative membrane curvature resulting from its formation. In both cases, the active peptide conformation corresponds to tight helical hairpin, whereas extended boomerang geometry appears to be unable to provide favourable thermodynamic effect. The latter observation offers plausible explanation for long known inactivity of boomerang-stabilising W14A mutation.
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Affiliation(s)
- Michal Michalski
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Piotr Setny
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
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13
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Golani G, Schwarz US. High curvature promotes fusion of lipid membranes: Predictions from continuum elastic theory. Biophys J 2023; 122:1868-1882. [PMID: 37077047 PMCID: PMC10209146 DOI: 10.1016/j.bpj.2023.04.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/19/2023] [Accepted: 04/14/2023] [Indexed: 04/21/2023] Open
Abstract
The fusion of lipid membranes progresses through a series of hemifusion intermediates with two significant energy barriers related to the formation of stalk and fusion pore, respectively. These energy barriers determine the speed and success rate of many critical biological processes, including the fusion of highly curved membranes, for example synaptic vesicles and enveloped viruses. Here we use continuum elastic theory of lipid monolayers to determine the relationship between membrane shape and energy barriers to fusion. We find that the stalk formation energy decreases with curvature by up to 31 kBT in a 20-nm-radius vesicle compared with planar membranes and by up to 8 kBT in the fusion of highly curved, long, tubular membranes. In contrast, the fusion pore formation energy barrier shows a more complicated behavior. Immediately after stalk expansion to the hemifusion diaphragm, the fusion pore formation energy barrier is low (15-25 kBT) due to lipid stretching in the distal monolayers and increased tension in highly curved vesicles. Therefore, the opening of the fusion pore is faster. However, these stresses relax over time due to lipid flip-flop from the proximal monolayer, resulting in a larger hemifusion diaphragm and a higher fusion pore formation energy barrier, up to 35 kBT. Therefore, if the fusion pore fails to open before significant lipid flip-flop takes place, the reaction proceeds to an extended hemifusion diaphragm state, which is a dead-end configuration in the fusion process and can be used to prevent viral infections. In contrast, in the fusion of long tubular compartments, the surface tension does not accumulate due to the formation of the diaphragm, and the energy barrier for pore expansion increases with curvature by up to 11 kBT. This suggests that inhibition of polymorphic virus infection could particularly target this feature of the second barrier.
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Affiliation(s)
- Gonen Golani
- Institute for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - Ulrich S Schwarz
- Institute for Theoretical Physics and BioQuant Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany.
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14
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Sengar A, Cervantes M, Bondalapati ST, Hess T, Kasson PM. Single-Virus Fusion Measurements Reveal Multiple Mechanistically Equivalent Pathways for SARS-CoV-2 Entry. J Virol 2023; 97:e0199222. [PMID: 37133381 DOI: 10.1128/jvi.01992-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023] Open
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) binds to cell surface receptors and is activated for membrane fusion and cell entry via proteolytic cleavage. Phenomenological data have shown that SARS-CoV-2 can be activated for entry at either the cell surface or in endosomes, but the relative roles in different cell types and mechanisms of entry have been debated. Here, we used single-virus fusion experiments and exogenously controlled proteases to probe activation directly. We found that plasma membrane and an appropriate protease are sufficient to support SARS-CoV-2 pseudovirus fusion. Furthermore, fusion kinetics of SARS-CoV-2 pseudoviruses are indistinguishable no matter which of a broad range of proteases is used to activate the virus. This suggests that the fusion mechanism is insensitive to protease identity or even whether activation occurs before or after receptor binding. These data support a model for opportunistic fusion by SARS-CoV-2 in which the subcellular location of entry likely depends on the differential activity of airway, cellsurface, and endosomal proteases, but all support infection. Inhibition of any single host protease may thus reduce infection in some cells but may be less clinically robust. IMPORTANCE SARS-CoV-2 can use multiple pathways to infect cells, as demonstrated recently when new viral variants switched dominant infection pathways. Here, we used single-virus fusion experiments together with biochemical reconstitution to show that these multiple pathways coexist simultaneously and specifically that the virus can be activated by different proteases in different cellular compartments with mechanistically identical effects. The consequences of this are that the virus is evolutionarily plastic and that therapies targeting viral entry should address multiple pathways at once to achieve optimal clinical effects.
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Affiliation(s)
- Anjali Sengar
- Department of Molecular Physiology, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
- Department of Biomedical Engineering, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
| | - Marcos Cervantes
- Department of Molecular Physiology, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
- Department of Biomedical Engineering, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
| | - Sai T Bondalapati
- Department of Molecular Physiology, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
- Department of Biomedical Engineering, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
| | - Tobin Hess
- Department of Molecular Physiology, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
- Department of Biomedical Engineering, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
| | - Peter M Kasson
- Department of Molecular Physiology, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
- Department of Biomedical Engineering, Global Infectious Diseases Institute, University of Virginia, Charlottesville, Virginia, USA
- Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
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15
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Rogers JR, Geissler PL. Ceramide-1-phosphate transfer protein enhances lipid transport by disrupting hydrophobic lipid-membrane contacts. PLoS Comput Biol 2023; 19:e1010992. [PMID: 37036851 PMCID: PMC10085062 DOI: 10.1371/journal.pcbi.1010992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 03/03/2023] [Indexed: 04/11/2023] Open
Abstract
Cellular distributions of the sphingolipid ceramide-1-phosphate (C1P) impact essential biological processes. C1P levels are spatiotemporally regulated by ceramide-1-phosphate transfer protein (CPTP), which efficiently shuttles C1P between organelle membranes. Yet, how CPTP rapidly extracts and inserts C1P into a membrane remains unknown. Here, we devise a multiscale simulation approach to elucidate biophysical details of CPTP-mediated C1P transport. We find that CPTP binds a membrane poised to extract and insert C1P and that membrane binding promotes conformational changes in CPTP that facilitate C1P uptake and release. By significantly disrupting a lipid's local hydrophobic environment in the membrane, CPTP lowers the activation free energy barrier for passive C1P desorption and enhances C1P extraction from the membrane. Upon uptake of C1P, further conformational changes may aid membrane unbinding in a manner reminiscent of the electrostatic switching mechanism used by other lipid transfer proteins. Insertion of C1P into an acceptor membrane, eased by a decrease in membrane order by CPTP, restarts the transfer cycle. Most notably, we provide molecular evidence for CPTP's ability to catalyze C1P extraction by breaking hydrophobic C1P-membrane contacts with compensatory hydrophobic lipid-protein contacts. Our work, thus, provides biophysical insights into how CPTP efficiently traffics C1P between membranes to maintain sphingolipid homeostasis and, additionally, presents a simulation method aptly suited for uncovering the catalytic mechanisms of other lipid transfer proteins.
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Affiliation(s)
- Julia R Rogers
- Department of Chemistry, University of California, Berkeley, California, United States of America
| | - Phillip L Geissler
- Department of Chemistry, University of California, Berkeley, California, United States of America
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America
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16
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Rice A, Zimmerberg J, Pastor RW. Initiation and evolution of pores formed by influenza fusion peptides probed by lysolipid inclusion. Biophys J 2023; 122:1018-1032. [PMID: 36575795 PMCID: PMC10111278 DOI: 10.1016/j.bpj.2022.12.029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 12/09/2022] [Accepted: 12/21/2022] [Indexed: 12/28/2022] Open
Abstract
The fusion peptide (FP) domain is necessary for the fusogenic activity of spike proteins in a variety of enveloped viruses, allowing the virus to infect the host cell, and is the only part of the protein that interacts directly with the target membrane lipid tails during fusion. There are consistent findings of poration by this domain in experimental model membrane systems, and, in certain conditions, the isolated FPs can generate pores. Here, we use molecular dynamics simulations to investigate the specifics of how these FP-induced pores form in membranes with different compositions of lysolipid and POPC. The simulations show that pores form spontaneously at high lysolipid concentrations via hybrid intermediates, where FP aggregates in the cis leaflet tilt to form a funnel-like structure that spans the leaflet and locally reduces the hydrophobic thickness that must be traversed by water to form a pore. By restraining a single FP within an FP aggregate to this tilted conformation, pores can be formed in lower-lysolipid-content membranes, including pure POPC, on the 100-ns timescale, much more rapidly than in unbiased simulations in bilayers with the same composition. The pore formation pathway is similar to the spontaneous formation in high lysolipid concentrations. Depending on the membrane composition, the pores can be metastable (as seen in POPC) or lead to membrane rupture.
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Affiliation(s)
- Amy Rice
- Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland
| | - Richard W Pastor
- Laboratory of Computational Biology, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland.
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17
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van Tilburg M, Hilbers PAJ, Markvoort AJ. On the role of membrane embedding, protein rigidity and transmembrane length in lipid membrane fusion. SOFT MATTER 2023; 19:1791-1802. [PMID: 36786821 DOI: 10.1039/d2sm01582j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
The fusion of biological membranes is ubiquitous in natural processes like exo- and endocytosis, intracellular trafficking and viral entry. Membrane fusion is also utilized in artificial biomimetic fusion systems, e.g. for drug delivery. Both the natural and the biomimetic fusion systems rely on a wide range of (artificial) proteins mediating the fusion process. Although the exact mechanisms of these proteins differ, clear analogies in their general behavior can be observed in bringing the membranes in close proximity and mediating the fusion reaction. In our study, we use molecular dynamics simulations with coarse grained models, mimicking the general behavior of fusion proteins (spikes), to systematically examine the effects of specific characteristics of these proteins on the fusion process. The protein characteristics considered are (i) the type of membrane embedding, i.e., either transmembrane or not, (ii) the rigidity, and (iii) the transmembrane domain (TMD) length. The results show essential differences in fusion pathway between monotopic and transmembrane spikes, in which transmembrane spikes seem to inhibit the formation of hemifusion diaphragms, leading to a faster fusion development. Furthermore, we observed that an increased rigidity and a decreased TMD length both proved to contribute to a faster fusion development. Finally, we show that a single spike may suffice to successfully induce a fusion reaction, provided that the spike is sufficiently rigid and attractive. Not only does this shed light on biological fusion of membranes, it also provides clear design rules for artificial membrane fusion systems.
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Affiliation(s)
- Marco van Tilburg
- Department of Biomedical Engineering, Computational Biology Group, Eindhoven University of Technology, The Netherlands.
| | - Peter A J Hilbers
- Department of Biomedical Engineering, Computational Biology Group, Eindhoven University of Technology, The Netherlands.
- Institute of Complex Molecular Systems, Eindhoven University of Technology, The Netherlands
| | - Albert J Markvoort
- Department of Biomedical Engineering, Computational Biology Group, Eindhoven University of Technology, The Netherlands.
- Institute of Complex Molecular Systems, Eindhoven University of Technology, The Netherlands
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18
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Rokonujjaman M, Sahyouni A, Wolfe R, Jia L, Ghosh U, Weliky DP. A large HIV gp41 construct with trimer-of-hairpins structure exhibits V2E mutation-dominant attenuation of vesicle fusion and helicity very similar to V2E attenuation of HIV fusion and infection and supports: (1) hairpin stabilization of membrane apposition with larger distance for V2E; and (2) V2E dominance by an antiparallel β sheet with interleaved fusion peptide strands from two gp41 trimers. Biophys Chem 2023; 293:106933. [PMID: 36508984 PMCID: PMC9879285 DOI: 10.1016/j.bpc.2022.106933] [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: 09/29/2022] [Revised: 11/13/2022] [Accepted: 11/14/2022] [Indexed: 11/27/2022]
Abstract
There is complete attenuation of fusion and infection mediated by HIV gp160 with gp41 subunit with V2E mutation, and also V2E dominance with WT/V2E mixtures. V2E is at the N-terminus of the ∼25-residue fusion peptide (Fp) which likely binds the target membrane. In this study, large V2E attenuation and dominance were observed for vesicle fusion induced by FP_HM, a large gp41 ectodomain construct with Fp followed by hyperthermostable hairpin with N- and C-helices, and membrane-proximal external region (Mper). FP_HM is a trimer-of-hairpins, the final gp41 structure during fusion. Vesicle fusion and helicity were measured for FP_HM using trimers with different fractions (f's) of WT and V2E proteins. Reductions in FP_HM fusion and helicity vs. fV2E were quantitatively-similar to those for gp160-mediated fusion and infection. Global fitting of all V2E data supports 6 WT gp41 (2 trimers) required for fusion. These data are understood by a model in which the ∼25 kcal/mol free energy for initial membrane apposition is compensated by the thermostable hairpin between the Fp in target membrane and Mper/transmembrane domain in virus membrane. The data support a structural model for V2E dominance with a membrane-bound Fp with antiparallel β sheet and interleaved strands from the two trimers. Relative to fV2E = 0, a longer Fp sheet is stabilized with small fV2E because of salt-bridge and/or hydrogen bonds between E2 on one strand and C-terminal Fp residues on adjacent strands, like R22. A longer Fp sheet results in shorter N- and C-helices, and larger separation during membrane apposition which hinders fusion.
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Affiliation(s)
- Md Rokonujjaman
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Abdulrazak Sahyouni
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Robert Wolfe
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Lihui Jia
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - Ujjayini Ghosh
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | - David P Weliky
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
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19
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Mannsverk S, Villamil Giraldo AM, Kasson PM. Influenza Virus Membrane Fusion Is Promoted by the Endosome-Resident Phospholipid Bis(monoacylglycero)phosphate. J Phys Chem B 2022; 126:10445-10451. [PMID: 36468619 PMCID: PMC9761668 DOI: 10.1021/acs.jpcb.2c06642] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The phospholipid bis(monoacylglycero)phosphate (BMP) is enriched in late endosomal and endolysosomal membranes and is believed to be involved in membrane deformation and generation of intralumenal vesicles within late endosomes. Previous studies have demonstrated that BMP promotes membrane fusion of several enveloped viruses, but a limited effect has been found on influenza virus. Here, we report the use of single-virus fusion assays to dissect BMP's effect on influenza virus fusion in greater depth. In agreement with prior reports, we found that hemifusion kinetics and efficiency were unaffected by the addition of 10-20 mol % BMP to the target membrane. However, using an assay for fusion pore formation and genome exposure, we found full fusion efficiency to be substantially enhanced by the addition of 10-20 mol % BMP to the target membrane, while the kinetics remained unaffected. By comparing BMP to other negatively charged phospholipids, we found the effect on fusion efficiency mainly attributable to headgroup charge, although we also hypothesize a role for BMP's unusual chemical structure. Our results suggest that BMP function as a permissive factor for a wider range of viruses than previously reported. We hypothesize that BMP may be a general cofactor for endosomal entry of enveloped viruses.
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Affiliation(s)
- Steinar Mannsverk
- Science
for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala 75124, Sweden
| | - Ana M. Villamil Giraldo
- 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, Virginia 22908, United States,
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20
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Villamil Giraldo AM, Mannsverk S, Kasson PM. Measuring single-virus fusion kinetics using an assay for nucleic acid exposure. Biophys J 2022; 121:4467-4475. [PMID: 36330566 PMCID: PMC9748363 DOI: 10.1016/j.bpj.2022.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 09/26/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022] Open
Abstract
The kinetics by which individual enveloped viruses fuse with membranes provide an important window into viral-entry mechanisms. We have developed a real-time assay using fluorescent probes for single-virus genome exposure than can report on stages of viral entry including or subsequent to fusion pore formation and prior to viral genome trafficking. We accomplish this using oxazole yellow nucleic-acid-binding dyes, which can be encapsulated in the lumen of target membranes to permit specific detection of fusion events. Since increased fluorescence of the dye occurs only when it encounters viral genome via a fusion pore and binds, this assay excludes content leakage without fusion. Using this assay, we show that influenza virus fuses with liposomes of different sizes with indistinguishable kinetics by both testing liposomes extruded through pores of different radii and showing that the fusion kinetics of individual liposomes are uncorrelated with the size of the liposome. These results suggest that the starting curvature of such liposomes does not control the rate-limiting steps in influenza entry.
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Affiliation(s)
- Ana M Villamil Giraldo
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Steinar Mannsverk
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Peter M Kasson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden; Departments of Molecular Physiology and Biomedical Engineering, University of Virginia, Charlottesville, Virginia.
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21
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Haldar S. Recent Developments in Single-Virus Fusion Assay. J Membr Biol 2022; 255:747-755. [PMID: 36173449 DOI: 10.1007/s00232-022-00270-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Accepted: 09/13/2022] [Indexed: 12/24/2022]
Abstract
Viral infection is a global health hazard. A crucial step in the infection cycle of enveloped viruses is the fusion of viral and host cellular membranes, which permits the transfer of the viral genome to the host cells. Membrane fusion is a ubiquitous process involved in sperm-egg fusion, exocytosis, vesicular trafficking, and viral entry to host cells. While different protein machineries catalyze the diverse fusion processes, the essential step, i.e., merging of two lipid bilayers against a kinetic energy barrier, is the same. Therefore, viral fusion machineries/pathways are not only the sites for antiviral drug development but also serve as model fusogens. Ensemble-based spectroscopic approaches or bulk fusion assays have yielded valuable insights regarding the fusion processes. However, due to the stochastic nature of the fusion events, ensemble-based assays do not permit synchronization of all the fusion events, and the molecular steps leading to fusion pore opening cannot be resolved entirely and correlated with the structural changes in viral fusion proteins. Several single-virus fusion assays have been developed to circumvent these issues. The review describes the recent advancements in single-virus/particle fusion assays using the Influenza virus as a paradigm.
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Affiliation(s)
- Sourav Haldar
- Division of Virus Research and Therapeutics, CSIR-Central Drug Research Institute, Lucknow, Uttar Pradesh, 226031, India. .,Academy of Scientific and Innovative Research, Ghaziabad, Uttar Pradesh, India.
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22
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Larsen AH. Molecular Dynamics Simulations of Curved Lipid Membranes. Int J Mol Sci 2022; 23:8098. [PMID: 35897670 PMCID: PMC9331392 DOI: 10.3390/ijms23158098] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 07/19/2022] [Accepted: 07/20/2022] [Indexed: 02/04/2023] Open
Abstract
Eukaryotic cells contain membranes with various curvatures, from the near-plane plasma membrane to the highly curved membranes of organelles, vesicles, and membrane protrusions. These curvatures are generated and sustained by curvature-inducing proteins, peptides, and lipids, and describing these mechanisms is an important scientific challenge. In addition to that, some molecules can sense membrane curvature and thereby be trafficked to specific locations. The description of curvature sensing is another fundamental challenge. Curved lipid membranes and their interplay with membrane-associated proteins can be investigated with molecular dynamics (MD) simulations. Various methods for simulating curved membranes with MD are discussed here, including tools for setting up simulation of vesicles and methods for sustaining membrane curvature. The latter are divided into methods that exploit scaffolding virtual beads, methods that use curvature-inducing molecules, and methods applying virtual forces. The variety of simulation tools allow researcher to closely match the conditions of experimental studies of membrane curvatures.
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23
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Marrink SJ, Monticelli L, Melo MN, Alessandri R, Tieleman DP, Souza PCT. Two decades of Martini: Better beads, broader scope. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1620] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Siewert J. Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute & Zernike Institute for Advanced Materials University of Groningen Groningen The Netherlands
| | - Luca Monticelli
- Molecular Microbiology and Structural Biochemistry (MMSB ‐ UMR 5086) CNRS & University of Lyon Lyon France
| | - Manuel N. Melo
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa Oeiras Portugal
| | - Riccardo Alessandri
- Pritzker School of Molecular Engineering University of Chicago Chicago Illinois USA
| | - D. Peter Tieleman
- Centre for Molecular Simulation and Department of Biological Sciences University of Calgary Alberta Canada
| | - Paulo C. T. Souza
- Molecular Microbiology and Structural Biochemistry (MMSB ‐ UMR 5086) CNRS & University of Lyon Lyon France
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24
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Valério M, Mendonça DA, Morais J, Buga CC, Cruz CH, Castanho MA, Melo MN, Soares CM, Veiga AS, Lousa D. Parainfluenza Fusion Peptide Promotes Membrane Fusion by Assembling into Oligomeric Porelike Structures. ACS Chem Biol 2022; 17:1831-1843. [PMID: 35500279 PMCID: PMC9295702 DOI: 10.1021/acschembio.2c00208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Paramyxoviruses are enveloped viruses harboring a negative-sense RNA genome that must enter the host's cells to replicate. In the case of the parainfluenza virus, the cell entry process starts with the recognition and attachment to target receptors, followed by proteolytic cleavage of the fusion glycoprotein (F) protein, exposing the fusion peptide (FP) region. The FP is responsible for binding to the target membrane, and it is believed to play a crucial role in the fusion process, but the mechanism by which the parainfluenza FP (PIFP) promotes membrane fusion is still unclear. To elucidate this matter, we performed biophysical experimentation of the PIFP in membranes, together with coarse grain (CG) and atomistic (AA) molecular dynamics (MD) simulations. The simulation results led to the pinpointing of the most important PIFP amino acid residues for membrane fusion and show that, at high concentrations, the peptide induces the formation of a water-permeable porelike structure. This structure promotes lipid head intrusion and lipid tail protrusion, which facilitates membrane fusion. Biophysical experimental results validate these findings, showing that, depending on the peptide/lipid ratio, the PIFP can promote fusion and/or membrane leakage. Our work furthers the understanding of the PIFP-induced membrane fusion process, which might help foster development in the field of viral entry inhibition.
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Affiliation(s)
- Mariana Valério
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Diogo A. Mendonça
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - João Morais
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Carolina C. Buga
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Carlos H. Cruz
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Miguel A.R.B. Castanho
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Manuel N. Melo
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Cláudio M. Soares
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
| | - Ana Salomé Veiga
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Professor Egas Moniz, 1649-028 Lisboa, Portugal
| | - Diana Lousa
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Av. da República, 2780-157 Oeiras, Portugal
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25
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Kasson PM. Modeling biomolecular kinetics with large-scale simulation. Curr Opin Struct Biol 2022; 72:95-102. [PMID: 34592698 PMCID: PMC9476681 DOI: 10.1016/j.sbi.2021.08.009] [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: 08/18/2021] [Revised: 08/26/2021] [Accepted: 08/27/2021] [Indexed: 02/03/2023]
Abstract
The molecular details of biomolecular kinetics present a challenging estimation problem because the identities of relevant intermediates and the rates of exchange between them must be determined. These can be derived from prior knowledge, but in recent years, great advances have been made in the development and application of methods to systematically determine states and rates using biomolecular simulation. Doing this for biological systems of reasonable complexity requires substantial computational power, and contemporary methods leverage distributed computing or leadership-class computing resources to accomplish this. The result has been substantial insight into pressing contemporary problems, including structural activation of pandemic viruses. Here, we highlight recent developments in both methodology and exciting applications.
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Affiliation(s)
- Peter M Kasson
- Departments of Molecular Physiology and Biomedical Engineering, University of Virginia, Box 800886, Charlottesville, VA, 22908, USA; Department of Cell and Molecular Biology, Uppsala University, Box 256, Uppsala 75105, Sweden.
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26
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Siegel DP. Bicontinuous inverted cubic phase stabilization as an index of antimicrobial and membrane fusion peptide activity. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183815. [PMID: 34748744 DOI: 10.1016/j.bbamem.2021.183815] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/06/2021] [Accepted: 10/29/2021] [Indexed: 02/07/2023]
Abstract
Some antimicrobial peptides (AMPs) and membrane fusion-catalyzing peptides (FPs) stabilize bicontinuous inverted cubic (QII) phases. Previous authors proposed a topological rationale: since AMP-induced pores, fusion intermediates, and QII phases all have negative Gaussian curvature (NGC), peptides which produce NGC in one structure also do it in another. This assumes that peptides change the curvature energy of the lipid membranes. Here I test this with a Helfrich curvature energy model. First, experimentally, I show that lipid systems often used to study peptide NGC have NGC without peptides at higher temperatures. To determine the net effect of an AMP on NGC, the equilibrium phase behavior of the host lipids must be determined. Second, the model shows that AMPs must make large changes in the curvature energy to stabilize AMP-induced pores. Peptide-induced changes in elastic constants affect pores and QII phase differently. Changes in spontaneous curvature affect them in opposite ways. The observed correlation between QII phase stabilization and AMP activity doesn't show that AMPs act by lowering pore curvature energy. A different rationale is proposed. In theory, AMPs could simultaneously stabilize QII phase and pores by drastically changing two particular elastic constants. This could be tested by measuring AMP effects on the individual constants. I propose experiments to do that. Unlike AMPs, FPs must make only small changes in the curvature energy to catalyze fusion. It they act in this way, their fusion activity should correlate with their ability to stabilize QII phases.
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Affiliation(s)
- D P Siegel
- Givaudan Inc., 1199 Edison Drive, Cincinnati, OH 45216, United States of America.
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27
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Ramoji A, Pahlow S, Pistiki A, Rueger J, Shaik TA, Shen H, Wichmann C, Krafft C, Popp J. Understanding Viruses and Viral Infections by Biophotonic Methods. TRANSLATIONAL BIOPHOTONICS 2022. [DOI: 10.1002/tbio.202100008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Anuradha Ramoji
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4 Jena Germany
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
- Center for Sepsis Control and Care Jena University Hospital, Am Klinikum 1, 07747 Jena Germany
| | - Susanne Pahlow
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4 Jena Germany
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
- InfectoGnostics Research Campus Jena, Philosophenweg 7, 07743 Jena Germany
| | - Aikaterini Pistiki
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4 Jena Germany
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
| | - Jan Rueger
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
| | - Tanveer Ahmed Shaik
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
| | - Haodong Shen
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4 Jena Germany
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
- InfectoGnostics Research Campus Jena, Philosophenweg 7, 07743 Jena Germany
| | - Christina Wichmann
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4 Jena Germany
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
- InfectoGnostics Research Campus Jena, Philosophenweg 7, 07743 Jena Germany
| | - Christoph Krafft
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
| | - Juergen Popp
- Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University, Helmholtzweg 4 Jena Germany
- Leibniz Institute of Photonic Technology Jena (a member of Leibniz Health Technologies) , Albert‐Einstein Str. 9 Jena Germany
- Center for Sepsis Control and Care Jena University Hospital, Am Klinikum 1, 07747 Jena Germany
- InfectoGnostics Research Campus Jena, Philosophenweg 7, 07743 Jena Germany
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28
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Tuerkova A, Kasson PM. Computational methods to study enveloped viral entry. Biochem Soc Trans 2021; 49:2527-2537. [PMID: 34783344 PMCID: PMC10184508 DOI: 10.1042/bst20210190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 10/25/2021] [Accepted: 10/27/2021] [Indexed: 12/15/2022]
Abstract
The protein-membrane interactions that mediate viral infection occur via loosely ordered, transient assemblies, creating challenges for high-resolution structure determination. Computational methods and in particular molecular dynamics simulation have thus become important adjuncts for integrating experimental data, developing mechanistic models, and suggesting testable hypotheses regarding viral function. However, the large molecular scales of virus-host interaction also create challenges for detailed molecular simulation. For this reason, continuum membrane models have played a large historical role, although they have become less favored for high-resolution models of protein assemblies and lipid organization. Here, we review recent progress in the field, with an emphasis on the insight that has been gained using a mixture of coarse-grained and atomic-resolution molecular dynamics simulations. Based on successes and challenges to date, we suggest a multiresolution strategy that should yield the best mixture of computational efficiency and physical fidelity. This strategy may facilitate further simulations of viral entry by a broader range of viruses, helping illuminate the diversity of viral entry strategies and the essential common elements that can be targeted for antiviral therapies.
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Affiliation(s)
- Alzbeta Tuerkova
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala 75124, Sweden
| | - Peter M Kasson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala 75124, Sweden
- Departments of Molecular Physiology and Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, U.S.A
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29
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Liu KN, Boxer SG. Single-virus content-mixing assay reveals cholesterol-enhanced influenza membrane fusion efficiency. Biophys J 2021; 120:4832-4841. [PMID: 34536389 DOI: 10.1016/j.bpj.2021.09.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 08/05/2021] [Accepted: 09/09/2021] [Indexed: 10/20/2022] Open
Abstract
To infect a cell, enveloped viruses must first undergo membrane fusion, which proceeds through a hemifusion intermediate, followed by the formation of a fusion pore through which the viral genome is transferred to a target cell. Single-virus fusion studies to elucidate the dynamics of content mixing typically require extensive fluorescent labeling of viral contents. The labeling process must be optimized depending on the virus identity and strain and can potentially be perturbative to viral fusion behavior. Here, we introduce a single-virus assay in which content-labeled vesicles are bound to unlabeled influenza A virus (IAV) to eliminate the problematic step of content-labeling virions. We use fluorescence microscopy to observe individual, pH-triggered content mixing and content-loss events between IAV and target vesicles of varying cholesterol compositions. We show that target membrane cholesterol increases the efficiency of IAV content mixing and decreases the fraction of content-mixing events that result in content loss. These results are consistent with previous findings that cholesterol stabilizes pore formation in IAV entry and limits leakage after pore formation. We also show that content loss due to hemagglutinin fusion peptide engagement with the target membrane is independent of composition. This approach is a promising strategy for studying the single-virus content-mixing kinetics of other enveloped viruses.
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Affiliation(s)
- Katherine N Liu
- Department of Chemistry, Stanford University, Stanford, California
| | - Steven G Boxer
- Department of Chemistry, Stanford University, Stanford, California.
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30
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Lousa D, Soares CM. Molecular mechanisms of the influenza fusion peptide: insights from experimental and simulation studies. FEBS Open Bio 2021; 11:3253-3261. [PMID: 34710289 PMCID: PMC8634857 DOI: 10.1002/2211-5463.13323] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 10/11/2021] [Accepted: 10/27/2021] [Indexed: 12/29/2022] Open
Abstract
A key step in infections by enveloped viruses, such as influenza, is the fusion between the viral envelope and the host cell membrane, which allows the virus to insert its genetic material into the host cell and replicate. The influenza virus fusion process is promoted by hemagglutinin (HA), a glycoprotein that contains three identical monomers composed of two polypeptide chains (HA1 and HA2). Early studies on this protein revealed that HA-mediated fusion involves the insertion of the HA2 N-terminal segment into the host membrane and that this segment, known as the fusion peptide, is a key player in the fusion process. This mini-review highlights the main findings that have been obtained by experimental and computational studies on the HA fusion peptide, which give us a glimpse of its mode of action.
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Affiliation(s)
- Diana Lousa
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Cláudio M Soares
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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31
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Jones PE, Pérez-Segura C, Bryer AJ, Perilla JR, Hadden-Perilla JA. Molecular dynamics of the viral life cycle: progress and prospects. Curr Opin Virol 2021; 50:128-138. [PMID: 34464843 PMCID: PMC8651149 DOI: 10.1016/j.coviro.2021.08.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 08/09/2021] [Accepted: 08/09/2021] [Indexed: 01/29/2023]
Abstract
Molecular dynamics (MD) simulations across spatiotemporal resolutions are widely applied to study viruses and represent the central technique uniting the field of computational virology. We discuss the progress of MD in elucidating the dynamics of the viral life cycle, including the status of modeling intact extracellular virions and leveraging advanced simulations to mimic active life cycle processes. We further remark on the prospects of MD for continued contributions to the basic science characterization of viruses, especially given the increasing availability of high-quality experimental data and supercomputing power. Overall, integrative computational methods that are closely guided by experiments are unmatched in the level of detail they provide, enabling-now and in the future-new discoveries relevant to thwarting viral infection.
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Affiliation(s)
- Peter Eugene Jones
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Carolina Pérez-Segura
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Alexander J Bryer
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States
| | - Jodi A Hadden-Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, United States.
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32
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Ghosh U, Weliky DP. Rapid 2H NMR Transverse Relaxation of Perdeuterated Lipid Acyl Chains of Membrane with Bound Viral Fusion Peptide Supports Large-Amplitude Motions of These Chains That Can Catalyze Membrane Fusion. Biochemistry 2021; 60:2637-2651. [PMID: 34436856 DOI: 10.1021/acs.biochem.1c00316] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
An early step in cellular infection by a membrane-enveloped virus like HIV or influenza is joining (fusion) of the viral and cell membranes. Fusion is catalyzed by a viral protein that typically includes an apolar "fusion peptide" (fp) segment that binds the target membrane prior to fusion. In this study, the effects of nonhomologous HIV and influenza fp's on lipid acyl chain motion are probed with 2H NMR transverse relaxation rates (R2's) of a perdeuterated DMPC membrane. Measurements were made between 35 and 0 °C, which brackets the membrane liquid-crystalline-to-gel phase transitions. Samples were made with either HIV "GPfp" at pH 7 or influenza "HAfp" at pH 5 or 7. GPfp induces vesicle fusion at pH 7, and HAfp induces more fusion at pH 5 vs 7. GPfp bound to DMPC adopts an intermolecular antiparallel β sheet structure, whereas HAfp is a monomer helical hairpin. The R2's of the no peptide and HAfp, pH 7, samples increase gradually as temperature is lowered. The R2's of GPfp and HAfp, pH 5, samples have very different temperature dependence, with a ∼10× increase in R2CD2 when temperature is reduced from 25 to 20 °C and smaller but still substantial R2's at 10 and 0 °C. The large R2's with GPfp and HAfp, pH 5, are consistent with large-amplitude motions of lipid acyl chains that can aid fusion catalysis by increasing the population of chains near the aqueous phase, which is the chain location for transition states between membrane fusion intermediates.
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Affiliation(s)
- Ujjayini Ghosh
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - David P Weliky
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
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33
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Lujan P, Campelo F. Should I stay or should I go? Golgi membrane spatial organization for protein sorting and retention. Arch Biochem Biophys 2021; 707:108921. [PMID: 34038703 DOI: 10.1016/j.abb.2021.108921] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/12/2021] [Accepted: 05/03/2021] [Indexed: 12/23/2022]
Abstract
The Golgi complex is the membrane-bound organelle that lies at the center of the secretory pathway. Its main functions are to maintain cellular lipid homeostasis, to orchestrate protein processing and maturation, and to mediate protein sorting and export. These functions are not independent of one another, and they all require that the membranes of the Golgi complex have a well-defined biochemical composition. Importantly, a finely-regulated spatiotemporal organization of the Golgi membrane components is essential for the correct performance of the organelle. In here, we review our current mechanistic and molecular understanding of how Golgi membranes are spatially organized in the lateral and axial directions to fulfill their functions. In particular, we highlight the current evidence and proposed models of intra-Golgi transport, as well as the known mechanisms for the retention of Golgi residents and for the sorting and export of transmembrane cargo proteins. Despite the controversies, conflicting evidence, clashes between models, and technical limitations, the field has moved forward and we have gained extensive knowledge in this fascinating topic. However, there are still many important questions that remain to be completely answered. We hope that this review will help boost future investigations on these issues.
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Affiliation(s)
- Pablo Lujan
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain.
| | - Felix Campelo
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860, Barcelona, Spain.
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34
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Transient Excursions to Membrane Core as Determinants of Influenza Virus Fusion Peptide Activity. Int J Mol Sci 2021; 22:ijms22105301. [PMID: 34069905 PMCID: PMC8157580 DOI: 10.3390/ijms22105301] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/06/2021] [Accepted: 05/13/2021] [Indexed: 12/19/2022] Open
Abstract
Fusion of viral and host cell membranes is a critical step in the life cycle of enveloped viruses. In the case of influenza virus, it is mediated by subunit 2 of hemagglutinin (HA) glycoprotein whose N-terminal fragments insert into the target membrane and initiate lipid exchange. These isolated fragments, known as fusion peptides (HAfp), already possess own fusogenic activity towards liposomes. Although they have long been studied with the hope to uncover the details of HA-mediated fusion, their actual mechanism of action remains elusive. Here, we use extensive molecular dynamics simulations combined with experimental studies of three HAfp variants to fully characterize their free energy landscape and interaction with lipid bilayer. In addition to customary assumed peptides localization at lipid-water interface, we characterize membrane-spanning configurations, which turn out to be metastable for active HAfps and unstable for the fusion inactive W14A mutant. We show that, while the degree of membrane perturbation by surface peptide configurations is relatively low and does not show any mutation-related differences, the effect of deeply inserted configurations is significant and correlates with insertion depth of the N-terminal amino group which is the highest for the wild type HAfp. Finally, we demonstrate the feasibility of spontaneous peptide transition to intramembrane location and the critical role of strictly conserved tryptofan residue 14 in this process.
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35
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Risselada HJ, Grubmüller H. How proteins open fusion pores: insights from molecular simulations. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:279-293. [PMID: 33340336 PMCID: PMC8071795 DOI: 10.1007/s00249-020-01484-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/16/2020] [Accepted: 11/24/2020] [Indexed: 02/06/2023]
Abstract
Fusion proteins can play a versatile and involved role during all stages of the fusion reaction. Their roles go far beyond forcing the opposing membranes into close proximity to drive stalk formation and fusion. Molecular simulations have played a central role in providing a molecular understanding of how fusion proteins actively overcome the free energy barriers of the fusion reaction up to the expansion of the fusion pore. Unexpectedly, molecular simulations have revealed a preference of the biological fusion reaction to proceed through asymmetric pathways resulting in the formation of, e.g., a stalk-hole complex, rim-pore, or vertex pore. Force-field based molecular simulations are now able to directly resolve the minimum free-energy path in protein-mediated fusion as well as quantifying the free energies of formed reaction intermediates. Ongoing developments in Graphics Processing Units (GPUs), free energy calculations, and coarse-grained force-fields will soon gain additional insights into the diverse roles of fusion proteins.
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Affiliation(s)
- H. Jelger Risselada
- Department of Theoretical Physics, Georg-August University of Göttingen, Göttingen, Germany
- Leiden University, Leiden Institute of Chemistry (LIC), Leiden, The Netherlands
| | - Helmut Grubmüller
- Max Planck Institute for Biophysical Chemistry, Theoretical and Computational Biophysics Department, Göttingen, Germany
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36
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Golani G, Leikina E, Melikov K, Whitlock JM, Gamage DG, Luoma-Overstreet G, Millay DP, Kozlov MM, Chernomordik LV. Myomerger promotes fusion pore by elastic coupling between proximal membrane leaflets and hemifusion diaphragm. Nat Commun 2021; 12:495. [PMID: 33479215 PMCID: PMC7820291 DOI: 10.1038/s41467-020-20804-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 12/08/2020] [Indexed: 01/09/2023] Open
Abstract
Myomerger is a muscle-specific membrane protein involved in formation of multinucleated muscle cells by mediating the transition from the early hemifusion stage to complete fusion. Here, we considered the physical mechanism of the Myomerger action based on the hypothesis that Myomerger shifts the spontaneous curvature of the outer membrane leaflets to more positive values. We predicted, theoretically, that Myomerger generates the outer leaflet elastic stresses, which propagate into the hemifusion diaphragm and accelerate the fusion pore formation. We showed that Myomerger ectodomain indeed generates positive spontaneous curvature of lipid monolayers. We substantiated the mechanism by experiments on myoblast fusion and influenza hemagglutinin-mediated cell fusion. In both processes, the effects of Myomerger ectodomain were strikingly similar to those of lysophosphatidylcholine known to generate a positive spontaneous curvature of lipid monolayers. The control of post-hemifusion stages by shifting the spontaneous curvature of proximal membrane monolayers may be utilized in diverse fusion processes.
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Affiliation(s)
- Gonen Golani
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Evgenia Leikina
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Kamran Melikov
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jarred M Whitlock
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Dilani G Gamage
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Gracia Luoma-Overstreet
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Douglas P Millay
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH, 45229, USA
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel.
| | - Leonid V Chernomordik
- Section on Membrane Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA.
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37
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Borkotoky S, Dey D, Banerjee M. Computational Insight Into the Mechanism of SARS-CoV-2 Membrane Fusion. J Chem Inf Model 2021; 61:423-431. [PMID: 33412850 DOI: 10.1021/acs.jcim.0c01231] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Membrane fusion, a key step in the early stages of virus propagation, allows the release of the viral genome in the host cell cytoplasm. The process is initiated by fusion peptides that are small, hydrophobic components of viral membrane-embedded glycoproteins and are typically conserved within virus families. Here, we attempted to identify the correct fusion peptide region in the Spike protein of SARS-CoV-2 by all-atom molecular dynamics simulations of dual membrane systems with varied oligomeric units of putative candidate peptides. Of all of the systems tested, only a trimeric unit of a 40-amino-acid region (residues 816-855 of SARS-CoV-2 Spike) was effective in triggering the initial stages of membrane fusion, within 200 ns of simulation time. Association of this trimeric unit with dual membranes resulted in the migration of lipids from the upper leaflet of the lower bilayer toward the lower leaflet of the upper bilayer to create a structural unit reminiscent of a fusion bridge. We submit that residues 816-855 of Spike represent the bona fide fusion peptide of SARS-CoV-2 and that computational methods represent an effective way to identify fusion peptides in viral glycoproteins.
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Affiliation(s)
- Subhomoi Borkotoky
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Debajit Dey
- School of Medicine, University of Maryland, Baltimore, Maryland 21201, United States
| | - Manidipa Banerjee
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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38
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Haldar S, Okamoto K, Dunning RA, Kasson PM. Precise Triggering and Chemical Control of Single-Virus Fusion within Endosomes. J Virol 2020; 95:e01982-20. [PMID: 33115879 PMCID: PMC7737740 DOI: 10.1128/jvi.01982-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 10/07/2020] [Indexed: 11/20/2022] Open
Abstract
Many enveloped viruses infect cells within endocytic compartments. The pH drop that accompanies endosomal maturation, often in conjunction with proteolysis, triggers viral proteins to insert into the endosomal membrane and drive fusion. Fusion dynamics have been studied by tracking viruses within living cells, which limits the precision with which fusion can be synchronized and controlled, and reconstituting viral fusion to synthetic membranes, which introduces nonphysiological membrane curvature and composition. To overcome these limitations, we report chemically controllable triggering of single-virus fusion within endosomes. We isolated influenza (A/Aichi/68; H3N2) virus:endosome conjugates from cells, immobilized them in a microfluidic flow cell, and rapidly and controllably triggered fusion. Observed lipid-mixing kinetics were surprisingly similar to those of influenza virus fusion with model membranes of opposite curvature: 80% of single-virus events had indistinguishable kinetics. This result suggests that endosomal membrane curvature is not a key permissive feature for viral entry, at least lipid mixing. The assay preserved endosomal membrane asymmetry and protein composition, providing a platform to test how cellular restriction factors and altered endosomal trafficking affect viral membrane fusion.IMPORTANCE Many enveloped viruses infect cells via fusion to endosomes, but controlling this process within living cells has been challenging. We studied the fusion of influenza virus virions to endosomes in a chemically controllable manner. Extracting virus:endosome conjugates from cells and exogenously triggering fusion permits precise study of virus:endosome fusion kinetics. Surprisingly, endosomal curvature does not grossly alter fusion kinetics, although membrane deformability does. This supports a model for influenza virus entry where cells restrict or permit membrane fusion by changing deformability, for instance, using interferon-induced proteins.
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Affiliation(s)
- Sourav Haldar
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Kenta Okamoto
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Rebecca A Dunning
- Department of Molecular Physiology, University of Virginia, Charlottesville, Virginia, USA
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
| | - Peter M Kasson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
- Department of Molecular Physiology, University of Virginia, Charlottesville, Virginia, USA
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia, USA
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39
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Lousa D, Pinto ART, Campos SRR, Baptista AM, Veiga AS, Castanho MARB, Soares CM. Effect of pH on the influenza fusion peptide properties unveiled by constant-pH molecular dynamics simulations combined with experiment. Sci Rep 2020; 10:20082. [PMID: 33208852 PMCID: PMC7674464 DOI: 10.1038/s41598-020-77040-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 11/02/2020] [Indexed: 12/27/2022] Open
Abstract
The influenza virus fusion process, whereby the virus fuses its envelope with the host endosome membrane to release the genetic material, takes place in the acidic late endosome environment. Acidification triggers a large conformational change in the fusion protein, hemagglutinin (HA), which enables the insertion of the N-terminal region of the HA2 subunit, known as the fusion peptide, into the membrane of the host endosome. However, the mechanism by which pH modulates the molecular properties of the fusion peptide remains unclear. To answer this question, we performed the first constant-pH molecular dynamics simulations of the influenza fusion peptide in a membrane, extending for 40 µs of aggregated time. The simulations were combined with spectroscopic data, which showed that the peptide is twofold more active in promoting lipid mixing of model membranes at pH 5 than at pH 7.4. The realistic treatment of protonation introduced by the constant-pH molecular dynamics simulations revealed that low pH stabilizes a vertical membrane-spanning conformation and leads to more frequent contacts between the fusion peptide and the lipid headgroups, which may explain the increase in activity. The study also revealed that the N-terminal region is determinant for the peptide’s effect on the membrane.
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Affiliation(s)
- Diana Lousa
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
| | - Antónia R T Pinto
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Professor Egas Moniz, 1649-028, Lisboa, Portugal
| | - Sara R R Campos
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - António M Baptista
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal
| | - Ana S Veiga
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Professor Egas Moniz, 1649-028, Lisboa, Portugal
| | - Miguel A R B Castanho
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Professor Egas Moniz, 1649-028, Lisboa, Portugal
| | - Cláudio M Soares
- ITQB NOVA, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Av. da República, 2780-157, Oeiras, Portugal.
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40
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Villamil Giraldo AM, Kasson PM. Bilayer-Coated Nanoparticles Reveal How Influenza Viral Entry Depends on Membrane Deformability but Not Curvature. J Phys Chem Lett 2020; 11:7190-7196. [PMID: 32808796 DOI: 10.1021/acs.jpclett.0c01778] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Enveloped viruses infect cells via fusion between the viral envelope and a cellular membrane. This membrane fusion process is driven by viral proteins, but slow stochastic protein activation dominates the fusion kinetics, making it challenging to probe the role of membrane mechanics in viral entry directly. Furthermore, many changes to the interacting membranes alter the curvature, deformability, and spatial organization of membranes simultaneously. We have used bilayer-coated silica nanoparticles to restrict the deformability of lipid membranes in a controllable manner. The single-event kinetics for fusion of influenza virus to coated nanoparticles permits independent testing of how the membrane curvature and deformability control the free energy barriers to fusion. Varying the free energy of membrane deformation, but not membrane curvature, causes a corresponding response in the fusion kinetics and fusion protein stoichiometry. Thus, the main free energy barrier to lipid mixing by influenza virus is controlled by membrane deformability and not the initial membrane curvature.
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Affiliation(s)
- Ana M Villamil Giraldo
- 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, Virginia 22908, United States
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Influenza hemagglutinin drives viral entry via two sequential intramembrane mechanisms. Proc Natl Acad Sci U S A 2020; 117:7200-7207. [PMID: 32188780 DOI: 10.1073/pnas.1914188117] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Enveloped viruses enter cells via a process of membrane fusion between the viral envelope and a cellular membrane. For influenza virus, mutational data have shown that the membrane-inserted portions of the hemagglutinin protein play a critical role in achieving fusion. In contrast to the relatively well-understood ectodomain, a predictive mechanistic understanding of the intramembrane mechanisms by which influenza hemagglutinin drives fusion has been elusive. We used molecular dynamics simulations of fusion between a full-length hemagglutinin proteoliposome and a lipid bilayer to analyze these mechanisms. In our simulations, hemagglutinin first acts within the membrane to increase lipid tail protrusion and promote stalk formation and then acts to engage the distal leaflets of each membrane and promote stalk widening, curvature, and eventual fusion. These two sequential mechanisms, one occurring before stalk formation and one after, are consistent with our experimental measurements of single-virus fusion kinetics to liposomes of different sizes. The resulting model also helps explain and integrate previous mutational and biophysical data, particularly the mutational sensitivity of the fusion peptide N terminus and the length sensitivity of the transmembrane domain. We hypothesize that entry by other enveloped viruses may also use sequential processes of acyl tail exposure, followed by membrane curvature and distal leaflet engagement.
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