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Chiliveri SC, Louis JM, Best RB, Bax A. Real-time Exchange of the Lipid-bound Intermediate and Post-fusion States of the HIV-1 gp41 Ectodomain. J Mol Biol 2022; 434:167683. [PMID: 35700771 PMCID: PMC9378563 DOI: 10.1016/j.jmb.2022.167683] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 06/03/2022] [Accepted: 06/08/2022] [Indexed: 11/17/2022]
Abstract
The envelope glycoprotein gp41 of the HIV-1 virus mediates its entry into the host cell. During this process, gp41 undergoes large conformational changes and the energy released in the remodeling events is utilized to overcome the barrier associated with fusing the viral and host membranes. Although the structural intermediates of this fusion process are attractive targets for drug development, no detailed high-resolution structural information or quantitative thermodynamic characterization are available. By measuring the dynamic equilibrium between the lipid-bound intermediate and the post-fusion six-helical bundle (6HB) states of the gp41 ectodomain in the presence of bilayer membrane mimetics, we derived both the reaction kinetics and energies associated with these two states by solution NMR spectroscopy. At equilibrium, an exchange time constant of about 12 seconds at 38 °C is observed, and the post-fusion conformation is energetically more stable than the lipid-bound state by 3.4 kcal mol-1. The temperature dependence of the kinetics indicates that the folding occurs through a high-energy transition state which may resemble a 5HB structure. The energetics and kinetics of gp41 folding in the context of membrane bilayers provide a molecular basis for an improved understanding of viral membrane fusion.
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Affiliation(s)
- Sai Chaitanya Chiliveri
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA. https://twitter.com/SaiChiliveri
| | - John M Louis
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Robert B Best
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ad Bax
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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Yu C, Li S, Zhang X, Khan I, Ahmad I, Zhou Y, Li S, Shi J, Wang Y, Zheng YH. MARCH8 Inhibits Ebola Virus Glycoprotein, Human Immunodeficiency Virus Type 1 Envelope Glycoprotein, and Avian Influenza Virus H5N1 Hemagglutinin Maturation. mBio 2020; 11:e01882-20. [PMID: 32934085 DOI: 10.1128/mBio.01882-20] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Enveloped viruses express three classes of fusion proteins that are required for their entry into host cells via mediating virus and cell membrane fusion. Class I fusion proteins are produced from influenza viruses, retroviruses, Ebola viruses, and coronaviruses. They are first synthesized as a type I transmembrane polypeptide precursor that is subsequently glycosylated and oligomerized. Most of these precursors are cleaved en route to the plasma membrane by a cellular protease furin in the late secretory pathway, generating the trimeric N-terminal receptor-binding and C-terminal fusion subunits. Here, we show that a cellular protein, MARCH8, specifically inhibits the furin-mediated cleavage of EBOV GP, HIV-1 Env, and H5N1 HA. Further analyses uncovered that MARCH8 blocked the EBOV GP glycosylation in the Golgi and inhibited its transport from the Golgi to the plasma membrane. Thus, MARCH8 has a very broad antiviral activity by specifically inactivating different viral fusion proteins. Membrane-associated RING-CH-type 8 (MARCH8) strongly blocks human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) incorporation into virions by downregulating its cell surface expression, but the mechanism is still unclear. We now report that MARCH8 also blocks the Ebola virus (EBOV) glycoprotein (GP) incorporation via surface downregulation. To understand how these viral fusion proteins are downregulated, we investigated the effects of MARCH8 on EBOV GP maturation and externalization via the conventional secretion pathway. MARCH8 interacted with EBOV GP and furin when detected by immunoprecipitation and retained the GP/furin complex in the Golgi when their location was tracked by a bimolecular fluorescence complementation (BiFC) assay. MARCH8 did not reduce the GP expression or affect the GP modification by high-mannose N-glycans in the endoplasmic reticulum (ER), but it inhibited the formation of complex N-glycans on the GP in the Golgi. Additionally, the GP O-glycosylation and furin-mediated proteolytic cleavage were also inhibited. Moreover, we identified a novel furin cleavage site on EBOV GP and found that only those fully glycosylated GPs were processed by furin and incorporated into virions. Furthermore, the GP shedding and secretion were all blocked by MARCH8. MARCH8 also blocked the furin-mediated cleavage of HIV-1 Env (gp160) and the highly pathogenic avian influenza virus H5N1 hemagglutinin (HA). We conclude that MARCH8 has a very broad antiviral activity by prohibiting different viral fusion proteins from glycosylation and proteolytic cleavage in the Golgi, which inhibits their transport from the Golgi to the plasma membrane and incorporation into virions.
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Walls AC, Xiong X, Park YJ, Tortorici MA, Snijder J, Quispe J, Cameroni E, Gopal R, Dai M, Lanzavecchia A, Zambon M, Rey FA, Corti D, Veesler D. Unexpected Receptor Functional Mimicry Elucidates Activation of Coronavirus Fusion. Cell 2019; 176:1026-1039.e15. [PMID: 30712865 PMCID: PMC6751136 DOI: 10.1016/j.cell.2018.12.028] [Citation(s) in RCA: 454] [Impact Index Per Article: 90.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Revised: 10/29/2018] [Accepted: 12/17/2018] [Indexed: 12/27/2022]
Abstract
Recent outbreaks of severe acute respiratory syndrome and Middle East respiratory syndrome, along with the threat of a future coronavirus-mediated pandemic, underscore the importance of finding ways to combat these viruses. The trimeric spike transmembrane glycoprotein S mediates entry into host cells and is the major target of neutralizing antibodies. To understand the humoral immune response elicited upon natural infections with coronaviruses, we structurally characterized the SARS-CoV and MERS-CoV S glycoproteins in complex with neutralizing antibodies isolated from human survivors. Although the two antibodies studied blocked attachment to the host cell receptor, only the anti-SARS-CoV S antibody triggered fusogenic conformational changes via receptor functional mimicry. These results provide a structural framework for understanding coronavirus neutralization by human antibodies and shed light on activation of coronavirus membrane fusion, which takes place through a receptor-driven ratcheting mechanism.
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Affiliation(s)
- Alexandra C Walls
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
| | - Xiaoli Xiong
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
| | - Young-Jun Park
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
| | - M Alejandra Tortorici
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA; Institute Pasteur & CNRS UMR 3569, Unité de Virologie Structurale, 75015, Paris, France
| | - Joost Snijder
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
| | - Joel Quispe
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA
| | | | - Robin Gopal
- National Infection Service, Public Health England, London NW9 5HT, UK
| | - Mian Dai
- Crick Worldwide Influenza Centre, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Antonio Lanzavecchia
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana, 6500 Bellinzona, Switzerland
| | - Maria Zambon
- National Infection Service, Public Health England, London NW9 5HT, UK
| | - Félix A Rey
- Institute Pasteur & CNRS UMR 3569, Unité de Virologie Structurale, 75015, Paris, France
| | - Davide Corti
- Humabs Biomed SA, Vir Biotechnology, 6500 Bellinzona, Switzerland
| | - David Veesler
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, USA.
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Leemans A, Boeren M, Van der Gucht W, Pintelon I, Roose K, Schepens B, Saelens X, Bailey D, Martinet W, Caljon G, Maes L, Cos P, Delputte P. Removal of the N-Glycosylation Sequon at Position N116 Located in p27 of the Respiratory Syncytial Virus Fusion Protein Elicits Enhanced Antibody Responses after DNA Immunization. Viruses 2018; 10:E426. [PMID: 30110893 PMCID: PMC6115940 DOI: 10.3390/v10080426] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/08/2018] [Accepted: 08/13/2018] [Indexed: 11/16/2022] Open
Abstract
Prevention of severe lower respiratory tract infections in infants caused by the human respiratory syncytial virus (hRSV) remains a major public health priority. Currently, the major focus of vaccine development relies on the RSV fusion (F) protein since it is the main target protein for neutralizing antibodies induced by natural infection. The protein conserves 5 N-glycosylation sites, two of which are located in the F2 subunit (N27 and N70), one in the F1 subunit (N500) and two in the p27 peptide (N116 and N126). To study the influence of the loss of one or more N-glycosylation sites on RSV F immunogenicity, BALB/c mice were immunized with plasmids encoding RSV F glycomutants. In comparison with F WT DNA immunized mice, higher neutralizing titres were observed following immunization with F N116Q. Moreover, RSV A2-K-line19F challenge of mice that had been immunized with mutant F N116Q DNA was associated with lower RSV RNA levels compared with those in challenged WT F DNA immunized animals. Since p27 is assumed to be post-translationally released after cleavage and thus not present on the mature RSV F protein, it remains to be elucidated how deletion of this glycan can contribute to enhanced antibody responses and protection upon challenge. These findings provide new insights to improve the immunogenicity of RSV F in potential vaccine candidates.
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MESH Headings
- Animals
- Antibodies, Neutralizing/biosynthesis
- Antibodies, Neutralizing/blood
- Antibodies, Viral/biosynthesis
- Antibodies, Viral/blood
- Female
- Glycosylation
- Humans
- Hydrolysis
- Immunization
- Mice
- Mice, Inbred BALB C
- Models, Molecular
- Mutation
- Plasmids/administration & dosage
- Plasmids/genetics
- Plasmids/immunology
- Protein Engineering
- Protein Subunits/administration & dosage
- Protein Subunits/genetics
- Protein Subunits/immunology
- Respiratory Syncytial Virus Infections/immunology
- Respiratory Syncytial Virus Infections/prevention & control
- Respiratory Syncytial Virus Infections/virology
- Respiratory Syncytial Virus Vaccines/administration & dosage
- Respiratory Syncytial Virus Vaccines/genetics
- Respiratory Syncytial Virus Vaccines/immunology
- Respiratory Syncytial Virus, Human/drug effects
- Respiratory Syncytial Virus, Human/genetics
- Respiratory Syncytial Virus, Human/immunology
- Vaccines, DNA/administration & dosage
- Vaccines, DNA/genetics
- Vaccines, DNA/immunology
- Viral Fusion Proteins/administration & dosage
- Viral Fusion Proteins/genetics
- Viral Fusion Proteins/immunology
- Viral Load/drug effects
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Affiliation(s)
- Annelies Leemans
- Laboratory of Microbiology, Parasitology and Hygiene, University of Antwerp, B-2610 Antwerp, Belgium.
| | - Marlies Boeren
- Laboratory of Microbiology, Parasitology and Hygiene, University of Antwerp, B-2610 Antwerp, Belgium.
| | - Winke Van der Gucht
- Laboratory of Microbiology, Parasitology and Hygiene, University of Antwerp, B-2610 Antwerp, Belgium.
| | - Isabel Pintelon
- Laboratory of Cell Biology and Histology, University of Antwerp, B-2610 Antwerp, Belgium.
| | - Kenny Roose
- Medical Biotechnology Centre, VIB, B-9052 Ghent, Belgium.
- Department of Biomedical Molecular Biology, Ghent University, B-9052 Ghent, Belgium.
| | - Bert Schepens
- Medical Biotechnology Centre, VIB, B-9052 Ghent, Belgium.
- Department of Biomedical Molecular Biology, Ghent University, B-9052 Ghent, Belgium.
| | - Xavier Saelens
- Medical Biotechnology Centre, VIB, B-9052 Ghent, Belgium.
- Department of Biomedical Molecular Biology, Ghent University, B-9052 Ghent, Belgium.
| | | | - Wim Martinet
- Laboratory of Physiopharmacology, University of Antwerp, B-2610 Antwerp, Belgium.
| | - Guy Caljon
- Laboratory of Microbiology, Parasitology and Hygiene, University of Antwerp, B-2610 Antwerp, Belgium.
| | - Louis Maes
- Laboratory of Microbiology, Parasitology and Hygiene, University of Antwerp, B-2610 Antwerp, Belgium.
| | - Paul Cos
- Laboratory of Microbiology, Parasitology and Hygiene, University of Antwerp, B-2610 Antwerp, Belgium.
| | - Peter Delputte
- Laboratory of Microbiology, Parasitology and Hygiene, University of Antwerp, B-2610 Antwerp, Belgium.
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