1
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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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2
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Sardar A, Bera T, Kumar Samal S, Dewangan N, Kamble M, Guha S, Tarafdar PK. C-Terminal Lipidation of SARS-CoV-2 Fusion Peptide Reinstates Superior Membrane Fusion Catalytic Ability. Chemistry 2023; 29:e202203034. [PMID: 36422064 DOI: 10.1002/chem.202203034] [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: 09/28/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/25/2022]
Abstract
The spike (S) protein of severe acute respiratory syndrome-associated coronavirus-2 (SARS-CoV-2) mediates a critical stage in infection, the fusion between viral and host membranes. The protein is categorized as a class I viral fusion protein and has two distinct cleavage sites that can be activated by proteases. The activation deploys the fusion peptide (FP) for insertion into the target cell membranes. Recent studies including our experiments showed that the FP was unable to modulate the kinetics of fusion at a low peptide-to-lipid ratio akin to the spike density at the viral surface. Therefore, we modified the C terminus of FP and attached a myristoyl chain (C-myr-FP) to restrict the C terminus near to the interface, bridge both membranes, and increase the effective local concentration. The lipidated FP (C-myr-FP) of SARS-CoV-2 greatly accelerates membrane fusion at a low peptide-to-lipid ratio as compared to the FP with no lipidation. Biophysical experiments suggest that C-myr-FP adopts a helical structure, perturbs the membrane interface, and increases water penetration to catalyze fusion. Scrambled peptide (C-myr-sFP) and truncated peptide (C-myr-8FP) could not significantly catalyze the fusion, thus suggesting the important role of myristoylation and the N terminus. C-myr-FP enhances murine coronavirus infection by promoting syncytia formation in L2 cells. The C-terminal lipidation of the FP might be a useful strategy to induce artificial fusion in biomedical applications.
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Affiliation(s)
- Avijit Sardar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, 741246, Mohanpur, India
| | - Tapas Bera
- Department of Chemistry, Jadavpur University, 700032, Kolkata, India
| | - Santosh Kumar Samal
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, 741246, Mohanpur, India
| | - Nikesh Dewangan
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, 741246, Mohanpur, India
| | - Mithila Kamble
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, 741246, Mohanpur, India
| | - Samit Guha
- Department of Chemistry, Jadavpur University, 700032, Kolkata, India
| | - Pradip K Tarafdar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, 741246, Mohanpur, India
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3
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Surmeier G, Dogan-Surmeier S, Paulus M, Albers C, Latarius J, Sternemann C, Schneider E, Tolan M, Nase J. The interaction of viral fusion peptides with lipid membranes. Biophys J 2022; 121:3811-3825. [PMID: 36110043 PMCID: PMC9674987 DOI: 10.1016/j.bpj.2022.09.011] [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: 01/24/2022] [Revised: 05/13/2022] [Accepted: 09/12/2022] [Indexed: 11/02/2022] Open
Abstract
In this paper, we studied fusogenic peptides of class I-III fusion proteins, which are relevant to membrane fusion for certain enveloped viruses, in contact with model lipid membranes. We resolved the vertical structure and examined the adsorption or penetration behavior of the fusogenic peptides at phospholipid Langmuir monolayers with different initial surface pressures with x-ray reflectometry. We show that the fusion loops of tick-borne encephalitis virus (TBEV) glycoprotein E and vesicular stomatitis virus (VSV) G-protein are not able to insert deeply into model lipid membranes, as they adsorbed mainly underneath the headgroups with only limited penetration depths into the lipid films. In contrast, we observed that the hemagglutinin 2 fusion peptide (HA2-FP) and the VSV-transmembrane domain (VSV-TMD) can penetrate deeply into the membranes. However, in the case of VSV-TMD, the penetration was suppressed already at low surface pressures, whereas HA2-FP was able to insert even into highly compressed films. Membrane fusion is accompanied by drastic changes of the membrane curvature. To investigate how the peptides affect the curvature of model lipid membranes, we examined the effect of the fusogenic peptides on the equilibration of cubic monoolein structures after a phase transition from a lamellar state induced by an abrupt hydrostatic pressure reduction. We monitored this process in presence and absence of the peptides with small-angle x-ray scattering and found that HA2-FP and VSV-TMD drastically accelerate the equilibration, while the fusion loops of TBEV and VSV stabilize the swollen state of the lipid structures. In this work, we show that the class I fusion peptide of HA2 penetrates deeply into the hydrophobic region of membranes and is able to promote and accelerate the formation of negative curvature. In contrast, we found that the class II and III fusion loops of TBEV and VSV tend to counteract negative membrane curvature.
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Affiliation(s)
- Göran Surmeier
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | | | - Michael Paulus
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | - Christian Albers
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | - Jan Latarius
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | | | - Eric Schneider
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | - Metin Tolan
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
| | - Julia Nase
- Fakultät Physik/DELTA, Technische Universität Dortmund, Dortmund, Germany
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4
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Michalski M, Setny P. Membrane-Bound Configuration and Lipid Perturbing Effects of Hemagglutinin Subunit 2 N-Terminus Investigated by Computer Simulations. Front Mol Biosci 2022; 9:826366. [PMID: 35155580 PMCID: PMC8830744 DOI: 10.3389/fmolb.2022.826366] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/04/2022] [Indexed: 01/08/2023] Open
Abstract
Hemagglutinin (HA) mediated fusion of influenza virus envelope with host lipid membrane is a critical step warrantying virus entry to the cell. Despite tremendous advances in structural biology methods, the knowledge concerning the details of HA2 subunit insertion into the target membrane and its subsequent bilayer perturbing effect is still rather limited. Herein, based on a set of molecular dynamics simulations, we investigate the structure and interaction with lipid membrane of the N-terminal HA2 region comprising a trimer of fusion peptides (HAfps) tethered by flexible linkers to a fragment of coiled-coil stem structure. We find that, prior to insertion into the membrane, HAfps within the trimers do not sample space individually but rather associate into a compact hydrophobic aggregate. Once within the membrane, they fold into tight helical hairpins, which remain at the lipid-water interface. However, they can also assume stable, membrane-spanning configurations of significantly increased membrane-perturbing potential. In this latter case, HAfps trimers centre around the well-hydrated transmembrane channel-forming distinct, symmetric assemblies, whose wedge-like shape may play a role in promoting membrane curvature. We also demonstrate that, following HAfps insertion, the coiled-coil stem spontaneously tilts to almost membrane-parallel orientation, reflecting experimentally observed configuration adopted in the course of membrane fusion by complete HA2 units at the rim of membrane contact zones.
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5
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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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6
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Basso LGM, Zeraik AE, Felizatti AP, Costa-Filho AJ. Membranotropic and biological activities of the membrane fusion peptides from SARS-CoV spike glycoprotein: The importance of the complete internal fusion peptide domain. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2021; 1863:183697. [PMID: 34274319 PMCID: PMC8280623 DOI: 10.1016/j.bbamem.2021.183697] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/05/2021] [Accepted: 07/10/2021] [Indexed: 11/28/2022]
Abstract
Fusion peptides (FP) are prominent hydrophobic segments of viral fusion proteins that play critical roles in viral entry. FPs interact with and insert into the host lipid membranes, triggering conformational changes in the viral protein that leads to the viral-cell fusion. Multiple membrane-active domains from the severe acute respiratory syndrome (SARS) coronavirus (CoV) spike protein have been reported to act as the functional fusion peptide such as the peptide sequence located between the S1/S2 and S2' cleavage sites (FP1), the S2'-adjacent fusion peptide domain (FP2), and the internal FP sequence (cIFP). Using a combined biophysical approach, we demonstrated that the α-helical coiled-coil-forming internal cIFP displayed the highest membrane fusion and permeabilizing activities along with membrane ordering effect in phosphatidylcholine (PC)/phosphatidylglycerol (PG) unilamellar vesicles compared to the other two N-proximal fusion peptide counterparts. While the FP1 sequence displayed intermediate membranotropic activities, the well-conserved FP2 peptide was substantially less effective in promoting fusion, leakage, and membrane ordering in PC/PG model membranes. Furthermore, Ca2+ did not enhance the FP2-induced lipid mixing activity in PC/phosphatidylserine/cholesterol lipid membranes, despite its strong erythrocyte membrane perturbation. Nonetheless, we found that the three putative SARS-CoV membrane-active fusion peptide sequences here studied altered the physical properties of model and erythrocyte membranes to different extents. The importance of the distinct membranotropic and biological activities of all SARS-CoV fusion peptide domains and the pronounced effect of the internal fusion peptide sequence to the whole spike-mediated membrane fusion process are discussed.
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Affiliation(s)
- Luis Guilherme Mansor Basso
- Laboratório de Ciências Físicas, Centro de Ciência e Tecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, 28013-602 Campos dos Goytacazes, RJ, Brazil; Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900, 14040-901 Ribeirão Preto, SP, Brazil.
| | - Ana Eliza Zeraik
- Laboratório de Química e Função de Proteínas e Peptídeos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Avenida Alberto Lamego, 2000, 28013-602 Campos dos Goytacazes, RJ, Brazil; Grupo de Biofísica e Biologia Estrutural "Sérgio Mascarenhas", Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, Centro, São Carlos, SP, Brazil
| | - Ana Paula Felizatti
- Laboratório de Produtos Naturais, Departamento de Química, Centro de Ciências Exatas e de Tecnologia, Universidade Federal de São Carlos, Rod. Washington Luiz, Km 235, Monjolinho, 13565905, São Carlos, SP, Brazil; Grupo de Biofísica e Biologia Estrutural "Sérgio Mascarenhas", Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, Centro, São Carlos, SP, Brazil
| | - Antonio José Costa-Filho
- Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes, 3900, 14040-901 Ribeirão Preto, SP, Brazil.
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7
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Lozada C, Barlow TMA, Gonzalez S, Lubin-Germain N, Ballet S. Identification and Characteristics of Fusion Peptides Derived From Enveloped Viruses. Front Chem 2021; 9:689006. [PMID: 34497798 PMCID: PMC8419435 DOI: 10.3389/fchem.2021.689006] [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: 03/31/2021] [Accepted: 08/10/2021] [Indexed: 01/28/2023] Open
Abstract
Membrane fusion events allow enveloped viruses to enter and infect cells. The study of these processes has led to the identification of a number of proteins that mediate this process. These proteins are classified according to their structure, which vary according to the viral genealogy. To date, three classes of fusion proteins have been defined, but current evidence points to the existence of additional classes. Despite their structural differences, viral fusion processes follow a common mechanism through which they exert their actions. Additional studies of the viral fusion proteins have demonstrated the key role of specific proteinogenic subsequences within these proteins, termed fusion peptides. Such peptides are able to interact and insert into membranes for which they hold interest from a pharmacological or therapeutic viewpoint. Here, the different characteristics of fusion peptides derived from viral fusion proteins are described. These criteria are useful to identify new fusion peptides. Moreover, this review describes the requirements of synthetic fusion peptides derived from fusion proteins to induce fusion by themselves. Several sequences of the viral glycoproteins E1 and E2 of HCV were, for example, identified to be able to induce fusion, which are reviewed here.
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Affiliation(s)
- Camille Lozada
- BioCIS, CNRS, CY Cergy-Paris Université, Cergy-Pontoise, France
- Research Group of Organic Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
| | - Thomas M. A. Barlow
- Research Group of Organic Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
| | - Simon Gonzalez
- BioCIS, CNRS, CY Cergy-Paris Université, Cergy-Pontoise, France
| | | | - Steven Ballet
- Research Group of Organic Chemistry, Vrije Universiteit Brussel, Brussels, Belgium
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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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9
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The role of fusion peptides in depth-dependent membrane organization and dynamics in promoting membrane fusion. Chem Phys Lipids 2020; 234:105025. [PMID: 33301753 DOI: 10.1016/j.chemphyslip.2020.105025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 11/16/2020] [Accepted: 12/03/2020] [Indexed: 11/24/2022]
Abstract
Membrane fusion is an important event in the life of eukaryotes; occurs in several processes such as endocytosis, exocytosis, cellular trafficking, compartmentalization, import of nutrients and export of waste, vesiculation, inter cellular communication, and fertilization. The enveloped viruses as well utilize fusion between the viral envelope and host cell membrane for infection. The stretch of 20-25 amino acids located at the N-terminus of the fusion protein, known as fusion peptide, plays a decisive role in the fusion process. The stalk model of membrane fusion postulated a common route of bilayer transformation for stalk, transmembrane contact, and pore formation; and fusion peptide is believed to facilitate bilayer transformation to promote membrane fusion. The peptide-induced change in depth-dependent organization and dynamics could provide important information in understanding the role of fusion peptide in membrane fusion. In this review, we have discussed about three depth-dependent properties of the membrane such as rigidity, polarity and heterogeneity, and the impact of fusion peptide on these three membrane properties.
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Mechanistic insights of host cell fusion of SARS-CoV-1 and SARS-CoV-2 from atomic resolution structure and membrane dynamics. Biophys Chem 2020; 265:106438. [PMID: 32721790 PMCID: PMC7375304 DOI: 10.1016/j.bpc.2020.106438] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 01/04/2023]
Abstract
The emerging and re-emerging viral diseases are continuous threats to the wellbeing of human life. Previous outbreaks of Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS had evidenced potential threats of coronaviruses in human health. The recent pandemic due to SARS-CoV-2 is overwhelming and has been going beyond control. Vaccines and antiviral drugs are ungently required to mitigate the pandemic. Therefore, it is important to comprehend the mechanistic details of viral infection process. The fusion between host cell and virus being the first step of infection, understanding the fusion mechanism could provide crucial information to intervene the infection process. Interestingly, all enveloped viruses contain fusion protein on their envelope that acts as fusion machine. For coronaviruses, the spike or S glycoprotein mediates successful infection through receptor binding and cell fusion. The cell fusion process requires merging of virus and host cell membranes, and that is essentially performed by the S2 domain of the S glycoprotein. In this review, we have discussed cell fusion mechanism of SARS-CoV-1 from available atomic resolution structures and membrane binding of fusion peptides. We have further discussed about the cell fusion of SARS-CoV-2 in the context of present pandemic situation.
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11
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Levin A, Jeworrek C, Winter R, Weise K, Czeslik C. Lipid Phase Control and Secondary Structure of Viral Fusion Peptides Anchored in Monoolein Membranes. J Phys Chem B 2017; 121:8492-8502. [PMID: 28829131 DOI: 10.1021/acs.jpcb.7b06400] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The fusion of lipid membranes involves major changes of the membrane curvatures and is mediated by fusion proteins that bind to the lipid membranes. For a better understanding of the way fusion proteins steer this process, we have studied the interaction of two different viral fusion peptides, HA2-FP and TBEV-FP, with monoolein mesophases as a function of temperature and pressure at limited hydration. The fusion peptides are derived from the influenza virus hemagglutinin fusion protein (HA2-FP) and from the tick-borne encephalitis virus envelope glycoprotein E (TBEV-FP). By using synchrotron X-ray diffraction, the changes of the monoolein phase behavior upon binding the peptides have been determined and the concomitant secondary structures of the peptides have been analyzed by FTIR spectroscopy. As main results we have found that the fusion peptides interact differently with monoolein and change the pressure and temperature dependent lipid phase behavior to different extents. However, they both destabilize the fluid lamellar phase and favor phases with negative curvature, i.e. inverse bicontinuous cubic and inverse hexagonal phases. These peptide-induced phase changes can partially be reversed by the application of high pressure, demonstrating that the promotion of negative curvature is achieved by a less dense packing of the monoolein membranes by the fusion peptides. Pressure jumps across the cubic-lamellar phase transition reveal that HA2-FP has a negligible effect on the rates of the cubic and the lamellar phase formation. Interestingly, the secondary structures of the fusion peptides appear unaffected by monoolein fluid-fluid phase transitions, suggesting that the fusion peptides are the structure dominant species in the fusion process of lipid membranes.
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Affiliation(s)
- Artem Levin
- Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany
| | - Christoph Jeworrek
- Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany
| | - Roland Winter
- Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany
| | - Katrin Weise
- Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany
| | - Claus Czeslik
- Department of Chemistry and Chemical Biology, TU Dortmund University , D-44221 Dortmund, Germany
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12
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Basso LGM, Vicente EF, Crusca E, Cilli EM, Costa-Filho AJ. SARS-CoV fusion peptides induce membrane surface ordering and curvature. Sci Rep 2016; 6:37131. [PMID: 27892522 PMCID: PMC5125003 DOI: 10.1038/srep37131] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Accepted: 10/24/2016] [Indexed: 12/23/2022] Open
Abstract
Viral membrane fusion is an orchestrated process triggered by membrane-anchored viral fusion glycoproteins. The S2 subunit of the spike glycoprotein from severe acute respiratory syndrome (SARS) coronavirus (CoV) contains internal domains called fusion peptides (FP) that play essential roles in virus entry. Although membrane fusion has been broadly studied, there are still major gaps in the molecular details of lipid rearrangements in the bilayer during fusion peptide-membrane interactions. Here we employed differential scanning calorimetry (DSC) and electron spin resonance (ESR) to gather information on the membrane fusion mechanism promoted by two putative SARS FPs. DSC data showed the peptides strongly perturb the structural integrity of anionic vesicles and support the hypothesis that the peptides generate opposing curvature stresses on phosphatidylethanolamine membranes. ESR showed that both FPs increase lipid packing and head group ordering as well as reduce the intramembrane water content for anionic membranes. Therefore, bending moment in the bilayer could be generated, promoting negative curvature. The significance of the ordering effect, membrane dehydration, changes in the curvature properties and the possible role of negatively charged phospholipids in helping to overcome the high kinetic barrier involved in the different stages of the SARS-CoV-mediated membrane fusion are discussed.
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Affiliation(s)
- Luis G M Basso
- Grupo de Biofísica Molecular Sérgio Mascarenhas, Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, Centro, São Carlos, SP, Brazil.,Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo. Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil
| | - Eduardo F Vicente
- Faculdade de Ciências e Engenharia, UNESP - Univ Estadual Paulista, Campus de Tupã. Rua Domingos da Costa Lopes, 780, 17602-496, Tupã, SP, Brazil
| | - Edson Crusca
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, UNESP - Univ Estadual Paulista. Rua Prof. Franscisco Degni, 55, 14800-900, Araraquara, SP, Brazil
| | - Eduardo M Cilli
- Departamento de Bioquímica e Tecnologia Química, Instituto de Química, UNESP - Univ Estadual Paulista. Rua Prof. Franscisco Degni, 55, 14800-900, Araraquara, SP, Brazil
| | - Antonio J Costa-Filho
- Laboratório de Biofísica Molecular, Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo. Av. Bandeirantes, 3900, 14040-901, Ribeirão Preto, SP, Brazil
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13
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Alteration of a Second Putative Fusion Peptide of Structural Glycoprotein E2 of Classical Swine Fever Virus Alters Virus Replication and Virulence in Swine. J Virol 2016; 90:10299-10308. [PMID: 27605674 DOI: 10.1128/jvi.01530-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 08/29/2016] [Indexed: 12/13/2022] Open
Abstract
E2, the major envelope glycoprotein of classical swine fever virus (CSFV), is involved in several critical virus functions, including cell attachment, host range susceptibility, and virulence in natural hosts. Functional structural analysis of E2 based on a Wimley-White interfacial hydrophobicity distribution predicted the involvement of a loop (residues 864 to 881) stabilized by a disulfide bond (869CKWGGNWTCV878, named FPII) in establishing interactions with the host cell membrane. This loop further contains an 872GG873 dipeptide, as well as two aromatic residues (871W and 875W) accessible to solvent. Reverse genetics utilizing a full-length infectious clone of the highly virulent CSFV strain Brescia (BICv) was used to evaluate how amino acid substitutions within FPII may affect replication of BICv in vitro and virus virulence in swine. Recombinant CSFVs containing mutations in different residues of FPII were constructed. A particular construct, harboring amino acid substitutions W871T, W875D, and V878T (FPII.2), demonstrated a significantly decreased ability to replicate in a swine cell line (SK6) and swine macrophage primary cell cultures. Interestingly, mutated virus FPII.2 was completely attenuated in pigs. Also, animals infected with FPII.2 virus were protected against virulent challenge with Brescia virus at 21 days postvaccination. Supporting a role for the E2 the loop from residues 864 to 881 in membrane fusion, only synthetic peptides that were based on the native E2 functional sequence were competent for insertion into model membranes and perturbation of their integrity, and this functionality was lost in synthetic peptides harboring amino acid substitutions W871T, W875D, and V878T in FPII.2. IMPORTANCE This report describes the identification and characterization of a putative fusion peptide (FP) in the major structural protein E2 of classical swine fever virus (CSFV). The FP identification was performed by functional structural analysis of E2. We characterized the functional significance of this FP by using artificial membranes. Replacement of critical amino acid residues within the FP radically alters how it interacts with the artificial membranes. When we introduced the same mutations into the viral sequence, there was a reduction in replication in cell cultures, and when we infected domestic swine, the natural host of CSFV host, we observed that the virus was now completely attenuated in swine. In addition, the virus mutant that was attenuated in vivo efficiently protected pigs against wild-type virus. These results provide the proof of principle to support as a strategy for vaccine development the discovery and manipulation of FPs.
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Structure and interaction with lipid membrane models of Semliki Forest virus fusion peptide. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:2671-2680. [PMID: 27425030 PMCID: PMC7172313 DOI: 10.1016/j.bbamem.2016.07.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/21/2016] [Accepted: 07/12/2016] [Indexed: 11/24/2022]
Abstract
Semliki Forest virus (SFV) is a well-characterized alphavirus that infects cells via endocytosis and an acid-triggered fusion step using class II fusion proteins. Membrane fusion is mediated by the viral spike protein, a heterotrimer of two transmembrane subunits, E1 and E2, and a peripheral protein, E3. Sequence analysis of the E1 ectodomain of a number of alphaviruses demonstrated the presence of a highly conserved hydrophobic domain on the E1 ectodomain. This sequence was proposed to be the fusion peptide of SFV and is believed to be the domain of E1 that interacts with the target membrane and triggers fusion. Here, we investigate the structure and the interaction with lipid membrane models of 76YQCKVYTGVYPFMWGGAYCFC96 sequence from SFV, named SFV21, using optical method (ellipsometry) and vibrational spectroscopiy approaches (Polarization Modulation infra-Red Reflection Absorption Spectroscopy, PMIRRAS, and polarized ATR-FTIR). We demonstrate a structural flexibility of SFV21 sequence whether the lateral pressure and the lipid environment. In a lipid environment that mimics eukaryotic cell membranes, a conformational transition from an α-helix to a β-sheet is induced in the presence of lipid by increasing the peptide to lipid ratio, which leads to important perturbations in the membrane organisation. SFV21 fusion peptide displays structural flexibility between α-helix and β-sheets. A conformational transition from an α-helix to a β-sheet is induced by the increase of the peptide to lipid ratio. SFV21 fusion peptide leads to important perturbations in the membrane organisation.
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Apellániz B, Nieva JL. Fusion-competent state induced by a C-terminal HIV-1 fusion peptide in cholesterol-rich membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1014-22. [PMID: 25617671 DOI: 10.1016/j.bbamem.2015.01.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 12/15/2014] [Accepted: 01/14/2015] [Indexed: 11/17/2022]
Abstract
The replicative cycle of the human immunodeficiency virus type-1 begins after fusion of the viral and target-cell membranes. The envelope glycoprotein gp41 transmembrane subunit contains conserved hydrophobic domains that engage and perturb the merging lipid bilayers. In this work, we have characterized the fusion-committed state generated in vesicles by CpreTM, a synthetic peptide derived from the sequence connecting the membrane-proximal external region (MPER) and the transmembrane domain (TMD) of gp41. Pre-loading cholesterol-rich vesicles with CpreTM rendered them competent for subsequent lipid-mixing with fluorescently-labeled target vesicles. Highlighting the physiological relevance of the lasting fusion-competent state, the broadly neutralizing antibody 4E10 bound to the CpreTM-primed vesicles and inhibited lipid-mixing. Heterotypic fusion assays disclosed dependence on the lipid composition of the vesicles that acted either as virus or cell membrane surrogates. Lipid-mixing exhibited above all a critical dependence on the cholesterol content in those experiments. We infer that the fusion-competent state described herein resembles bona-fide perturbations generated by the pre-hairpin MPER-TMD connection within the viral membrane.
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Affiliation(s)
- Beatriz Apellániz
- Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain.
| | - José L Nieva
- Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain.
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Ratnayake PU, Sackett K, Nethercott MJ, Weliky DP. pH-dependent vesicle fusion induced by the ectodomain of the human immunodeficiency virus membrane fusion protein gp41: Two kinetically distinct processes and fully-membrane-associated gp41 with predominant β sheet fusion peptide conformation. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1848:289-98. [PMID: 25078440 PMCID: PMC4258546 DOI: 10.1016/j.bbamem.2014.07.022] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2014] [Revised: 07/18/2014] [Accepted: 07/19/2014] [Indexed: 11/25/2022]
Abstract
The gp41 protein of the Human Immunodeficiency Virus (HIV) catalyzes fusion between HIV and host cell membranes. The ~180-residue ectodomain of gp41 is outside the virion and is the most important gp41 region for membrane fusion. The ectodomain consists of an apolar fusion peptide (FP) region hypothesized to bind to the host cell membrane followed by N-heptad repeat (NHR), loop, and C-heptad repeat (CHR) regions. The present study focuses on the large gp41 ectodomain constructs "Hairpin" (HP) containing NHR+loop+CHR and "FP-Hairpin" (FP-HP) containing FP+NHR+loop+CHR. Both proteins induce rapid and extensive fusion of anionic vesicles at pH4 where the protein is positively-charged but do not induce fusion at pH7 where the protein is negatively charged. This observation, along with lack of fusion of neutral vesicles at either pH supports the significance of attractive protein/membrane electrostatics in fusion. There are two kinetically distinct fusion processes at pH4: (1) a faster ~100 ms⁻¹ process with rate strongly positively correlated with vesicle charge; and (2) a slower ~5 ms⁻¹ process with extent strongly inversely correlated with this charge. The slower process may be more physiologically relevant because HIV/host cell fusion occurs at physiologic pH with gp41 restricted to the narrow region between the two membranes. Previous solid-state NMR (SSNMR) of membrane-associated FP-HP has supported protein oligomers with FP's in an intermolecular antiparallel sheet. There was an additional population of molecules with α helical FPs and the samples likely contained a mixture of membrane-bound and -unbound proteins. For the present study, samples were prepared with fully membrane-bound FP-HP and subsequent SSNMR showed dominant β FP conformation at both low and neutral pH. SSNMR also showed close contact of the FP with the lipid headgroups at both low and neutral pH whereas the NHR+CHR regions had contact at low pH and were more distant at neutral pH, consistent with the protein/membrane electrostatics.
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Affiliation(s)
- Punsisi U Ratnayake
- Department of Chemistry, Michigan State University, 578S. Shaw Lane, East Lansing, MI 48824, USA
| | - Kelly Sackett
- Department of Chemistry, Michigan State University, 578S. Shaw Lane, East Lansing, MI 48824, USA
| | - Matthew J Nethercott
- Department of Chemistry, Michigan State University, 578S. Shaw Lane, East Lansing, MI 48824, USA
| | - David P Weliky
- Department of Chemistry, Michigan State University, 578S. Shaw Lane, East Lansing, MI 48824, USA.
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Effect of specific amino acid substitutions in the putative fusion peptide of structural glycoprotein E2 on Classical Swine Fever Virus replication. Virology 2014; 456-457:121-30. [DOI: 10.1016/j.virol.2014.03.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Revised: 02/25/2014] [Accepted: 03/04/2014] [Indexed: 11/21/2022]
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18
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Hantavirus Gn and Gc envelope glycoproteins: key structural units for virus cell entry and virus assembly. Viruses 2014; 6:1801-22. [PMID: 24755564 PMCID: PMC4014721 DOI: 10.3390/v6041801] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Revised: 03/20/2014] [Accepted: 03/31/2014] [Indexed: 01/24/2023] Open
Abstract
In recent years, ultrastructural studies of viral surface spikes from three different genera within the Bunyaviridae family have revealed a remarkable diversity in their spike organization. Despite this structural heterogeneity, in every case the spikes seem to be composed of heterodimers formed by Gn and Gc envelope glycoproteins. In this review, current knowledge of the Gn and Gc structures and their functions in virus cell entry and exit is summarized. During virus cell entry, the role of Gn and Gc in receptor binding has not yet been determined. Nevertheless, biochemical studies suggest that the subsequent virus-membrane fusion activity is accomplished by Gc. Further, a class II fusion protein conformation has been predicted for Gc of hantaviruses, and novel crystallographic data confirmed such a fold for the Rift Valley fever virus (RVFV) Gc protein. During virus cell exit, the assembly of different viral components seems to be established by interaction of Gn and Gc cytoplasmic tails (CT) with internal viral ribonucleocapsids. Moreover, recent findings show that hantavirus glycoproteins accomplish important roles during virus budding since they self-assemble into virus-like particles. Collectively, these novel insights provide essential information for gaining a more detailed understanding of Gn and Gc functions in the early and late steps of the hantavirus infection cycle.
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Apellániz B, Huarte N, Largo E, Nieva JL. The three lives of viral fusion peptides. Chem Phys Lipids 2014; 181:40-55. [PMID: 24704587 PMCID: PMC4061400 DOI: 10.1016/j.chemphyslip.2014.03.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Revised: 03/19/2014] [Accepted: 03/20/2014] [Indexed: 02/07/2023]
Abstract
The presence of a fusion peptide (FP) is a hallmark of viral fusion glycoproteins. Structure–function relationships underlying FP conservation remain greatly unknown. FPs establish interactions satisfying their folding within pre-fusion glycoproteins. Upon fusion activation FPs insert into and restructure target membranes. FPs can finally combine with transmembrane domains to form integral membrane bundles.
Fusion peptides comprise conserved hydrophobic domains absolutely required for the fusogenic activity of glycoproteins from divergent virus families. After 30 years of intensive research efforts, the structures and functions underlying their high degree of sequence conservation are not fully elucidated. The long-hydrophobic viral fusion peptide (VFP) sequences are structurally constrained to access three successive states after biogenesis. Firstly, the VFP sequence must fulfill the set of native interactions required for (meta) stable folding within the globular ectodomains of glycoprotein complexes. Secondly, at the onset of the fusion process, they get transferred into the target cell membrane and adopt specific conformations therein. According to commonly accepted mechanistic models, membrane-bound states of the VFP might promote the lipid bilayer remodeling required for virus-cell membrane merger. Finally, at least in some instances, several VFPs co-assemble with transmembrane anchors into membrane integral helical bundles, following a locking movement hypothetically coupled to fusion-pore expansion. Here we review different aspects of the three major states of the VFPs, including the functional assistance by other membrane-transferring glycoprotein regions, and discuss briefly their potential as targets for clinical intervention.
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Affiliation(s)
- Beatriz Apellániz
- Biophysics Unit (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain
| | - Nerea Huarte
- Biophysics Unit (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain
| | - Eneko Largo
- Biophysics Unit (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain
| | - José L Nieva
- Biophysics Unit (CSIC-UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain.
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Sackett K, Nethercott MJ, Zheng Z, Weliky DP. Solid-state NMR spectroscopy of the HIV gp41 membrane fusion protein supports intermolecular antiparallel β sheet fusion peptide structure in the final six-helix bundle state. J Mol Biol 2014; 426:1077-94. [PMID: 24246500 PMCID: PMC3944376 DOI: 10.1016/j.jmb.2013.11.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2013] [Revised: 10/18/2013] [Accepted: 11/11/2013] [Indexed: 11/21/2022]
Abstract
The HIV gp41 protein catalyzes fusion between viral and target cell membranes. Although the ~20-residue N-terminal fusion peptide (FP) region is critical for fusion, the structure of this region is not well characterized in large gp41 constructs that model the gp41 state at different times during fusion. This paper describes solid-state NMR (SSNMR) studies of FP structure in a membrane-associated construct (FP-Hairpin), which likely models the final fusion state thought to be thermostable trimers with six-helix bundle structure in the region C-terminal of the FP. The SSNMR data show that there are populations of FP-Hairpin with either α helical or β sheet FP conformation. For the β sheet population, measurements of intermolecular (13)C-(13)C proximities in the FP are consistent with a significant fraction of intermolecular antiparallel β sheet FP structure with adjacent strand crossing near L7 and F8. There appears to be negligible in-register parallel structure. These findings support assembly of membrane-associated gp41 trimers through interleaving of N-terminal FPs from different trimers. Similar SSNMR data are obtained for FP-Hairpin and a construct containing the 70 N-terminal residues of gp41 (N70), which is a model for part of the putative pre-hairpin intermediate state of gp41. FP assembly may therefore occur at an early fusion stage. On a more fundamental level, similar SSNMR data are obtained for FP-Hairpin and a construct containing the 34 N-terminal gp41 residues (FP34) and support the hypothesis that the FP is an autonomous folding domain.
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Affiliation(s)
- Kelly Sackett
- Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA
| | | | - Zhaoxiong Zheng
- 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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21
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Luat LX, Tun MMN, Buerano CC, Aoki K, Morita K, Hayasaka D. Pathologic potential of variant clones of the oshima strain of far-eastern subtype tick-borne encephalitis virus. Trop Med Health 2014; 42:15-23. [PMID: 24808743 PMCID: PMC3965841 DOI: 10.2149/tmh.2013-27] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Accepted: 10/20/2013] [Indexed: 12/30/2022] Open
Abstract
Tick-borne encephalitis virus (TBEV) is a zoonotic agent that causes acute central nervous system (CNS) disease in humans. We previously suggested that immune response in addition to CNS infection contribute to mouse mortality following TBEV infection. However, we did not examine the influence of virus variants in the previous study. Therefore, in this study, we investigated the biological and pathologic potentials of the variant clones in the TBEV Oshima strain. We isolated eight variant clones from the stock virus of the Oshima 5-10. These variants exhibited different plaque morphologies in BHK cells and pathogenic potentials in mice. Full sequences of viral genomes revealed that each of the variant clones except one had specific combinations of nucleotide and amino acid changes at certain positions different from the parent strain. We also showed that an amino acid substitution of Glu122→Gly in the E protein could have affected virus infection and replication in vivo, as well as the attenuated pathogenicity in mice. These data confirm the presence of virus variants or quasispecies from the parent strain. Further elucidation of the effect of each variant clone on immune responses such as the T-cell response is an important priority in the development of an effective vaccine and treatment strategies for tick-borne encephalitis.
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Affiliation(s)
- Le Xuan Luat
- Department of Virology, Institute of Tropical Medicine, Nagasaki University
| | - Mya Myat Ngwe Tun
- Department of Virology, Institute of Tropical Medicine, Nagasaki University
| | - Corazon C Buerano
- Department of Virology, Institute of Tropical Medicine, Nagasaki University
| | - Kotaro Aoki
- Department of Virology, Institute of Tropical Medicine, Nagasaki University
| | - Kouichi Morita
- Department of Virology, Institute of Tropical Medicine, Nagasaki University
| | - Daisuke Hayasaka
- Department of Virology, Institute of Tropical Medicine, Nagasaki University
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22
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Gabrys CM, Qiang W, Sun Y, Xie L, Schmick SD, Weliky DP. Solid-state nuclear magnetic resonance measurements of HIV fusion peptide 13CO to lipid 31P proximities support similar partially inserted membrane locations of the α helical and β sheet peptide structures. J Phys Chem A 2013; 117:9848-59. [PMID: 23418890 PMCID: PMC3932798 DOI: 10.1021/jp312845w] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Fusion of the human immunodeficiency virus (HIV) membrane and the host cell membrane is an initial step of infection of the host cell. Fusion is catalyzed by gp41, which is an integral membrane protein of HIV. The fusion peptide (FP) is the ∼25 N-terminal residues of gp41 and is a domain of gp41 that plays a key role in fusion catalysis likely through interaction with the host cell membrane. Much of our understanding of the FP domain has been accomplished with studies of "HFP", i.e., a ∼25-residue peptide composed of the FP sequence but lacking the rest of gp41. HFP catalyzes fusion between membrane vesicles and serves as a model system to understand fusion catalysis. HFP binds to membranes and the membrane location of HFP is likely a significant determinant of fusion catalysis perhaps because the consequent membrane perturbation reduces the fusion activation energy. In the present study, many HFPs were synthesized and differed in the residue position that was (13)CO backbone labeled. Samples were then prepared that each contained a singly (13)CO labeled HFP incorporated into membranes that lacked cholesterol. HFP had distinct molecular populations with either α helical or oligomeric β sheet structure. Proximity between the HFP (13)CO nuclei and (31)P nuclei in the membrane headgroups was probed by solid-state NMR (SSNMR) rotational-echo double-resonance (REDOR) measurements. For many samples, there were distinct (13)CO shifts for the α helical and β sheet structures so that the proximities to (31)P nuclei could be determined for each structure. Data from several differently labeled HFPs were then incorporated into a membrane location model for the particular structure. In addition to the (13)CO labeled residue position, the HFPs also differed in sequence and/or chemical structure. "HFPmn" was a linear peptide that contained the 23 N-terminal residues of gp41. "HFPmn_V2E" contained the V2E mutation that for HIV leads to greatly reduced extent of fusion and infection. The present study shows that HFPmn_V2E induces much less vesicle fusion than HFPmn. "HFPtr" contained three strands with HFPmn sequence that were chemically cross-linked near their C-termini. HFPtr mimics the trimeric topology of gp41 and induces much more rapid and extensive vesicle fusion than HFPmn. For HFPmn and HFPtr, well-resolved α and β peaks were observed for A6-, L9-, and L12-labeled samples. For each of these samples, there were similar HFP (13)CO to lipid (31)P proximities in the α and β structures, which evidenced comparable membrane locations of the HFP in either structure including insertion into a single membrane leaflet. The data were also consistent with deeper insertion of HFPtr relative to HFPmn in both the α and β structures. The results supported a strong correlation between the membrane insertion depth of the HFP and its fusogenicity. More generally, the results supported membrane location of the HFP as an important determinant of its fusogenicity. The deep insertion of HFPtr in both the α and β structures provides the most relevant membrane location of the FP for HIV gp41-catalyzed membrane fusion because HIV gp41 is natively trimeric. Well-resolved α and β signals were observed in the HFPmn_V2E samples with L9- and L12- but not A6-labeling. The α signals were much more dominant for L9- and L12-labeled HFPmn_V2E than the corresponding HFPmn or HFPtr. The structural model for the less fusogenic HFPmn_V2E includes a shorter helix and less membrane insertion than either HFPmn or HFPtr. This greater helical population and different helical structure and membrane location could result in less membrane perturbation and lower fusogenicity of HFPmn_V2E and suggest that the β sheet fusion peptide is the most functionally relevant structure of HFPmn, HFPtr, and gp41.
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Affiliation(s)
- Charles M. Gabrys
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824
| | - Wei Qiang
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824
| | - Yan Sun
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824
| | - Li Xie
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824
| | - Scott D. Schmick
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824
| | - David P. Weliky
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824
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Mendes YS, Alves NS, Souza TLF, Sousa IP, Bianconi ML, Bernardi RC, Pascutti PG, Silva JL, Gomes AMO, Oliveira AC. The structural dynamics of the flavivirus fusion peptide-membrane interaction. PLoS One 2012; 7:e47596. [PMID: 23094066 PMCID: PMC3477123 DOI: 10.1371/journal.pone.0047596] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 09/18/2012] [Indexed: 11/18/2022] Open
Abstract
Membrane fusion is a crucial step in flavivirus infections and a potential target for antiviral strategies. Lipids and proteins play cooperative roles in the fusion process, which is triggered by the acidic pH inside the endosome. This acidic environment induces many changes in glycoprotein conformation and allows the action of a highly conserved hydrophobic sequence, the fusion peptide (FP). Despite the large volume of information available on the virus-triggered fusion process, little is known regarding the mechanisms behind flavivirus-cell membrane fusion. Here, we evaluated the contribution of a natural single amino acid difference on two flavivirus FPs, FLA(G) ((98)DRGWGNGCGLFGK(110)) and FLA(H) ((98)DRGWGNHCGLFGK(110)), and investigated the role of the charge of the target membrane on the fusion process. We used an in silico approach to simulate the interaction of the FPs with a lipid bilayer in a complementary way and used spectroscopic approaches to collect conformation information. We found that both peptides interact with neutral and anionic micelles, and molecular dynamics (MD) simulations showed the interaction of the FPs with the lipid bilayer. The participation of the indole ring of Trp appeared to be important for the anchoring of both peptides in the membrane model, as indicated by MD simulations and spectroscopic analyses. Mild differences between FLA(G) and FLA(H) were observed according to the pH and the charge of the target membrane model. The MD simulations of the membrane showed that both peptides adopted a bend structure, and an interaction between the aromatic residues was strongly suggested, which was also observed by circular dichroism in the presence of micelles. As the FPs of viral fusion proteins play a key role in the mechanism of viral fusion, understanding the interactions between peptides and membranes is crucial for medical science and biology and may contribute to the design of new antiviral drugs.
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Affiliation(s)
- Ygara S. Mendes
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, and Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nathalia S. Alves
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, and Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Theo L. F. Souza
- Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Ivanildo P. Sousa
- Programa de Vacinas Virais, Instituto de Tecnologia em Imunobiológicos, Fundação Oswaldo Cruz, Rio de Janeiro, Rio de Janeiro, Brazil
| | - M. Lucia Bianconi
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, and Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rafael C. Bernardi
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Pedro G. Pascutti
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Jerson L. Silva
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, and Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Andre M. O. Gomes
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, and Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
| | - Andréa C. Oliveira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica, and Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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Mura M, Dennison SR, Zvelindovsky AV, Phoenix DA. Aurein 2.3 functionality is supported by oblique orientated α-helical formation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:586-94. [PMID: 22960040 DOI: 10.1016/j.bbamem.2012.08.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 08/20/2012] [Accepted: 08/24/2012] [Indexed: 10/27/2022]
Abstract
In this study, an amphibian antimicrobial peptide, aurein 2.3, was predicted to use oblique orientated α-helix formation in its mechanism of membrane destabilisation. Molecular dynamic (MD) simulations and circular dichroism (CD) experimental data suggested that aurein 2.3 exists in solution as unstructured monomers and folds to form predominantly α-helical structures in the presence of a dimyristoylphosphatidylcholine membrane. MD showed that the peptide was highly surface active, which supported monolayer data where the peptide induced surface pressure changes>34 mNm(-1). In the presence of a lipid membrane MD simulations suggested that under hydrophobic mismatch the peptide is seen to insert via oblique orientation with a phenylalanine residue (PHE3) playing a key role in the membrane interaction. There is evidence of snorkelling leucine residues leading to further membrane disruption and supporting the high level of lysis observed using calcein release assays (76%). Simulations performed at higher peptide/lipid ratio show peptide cooperativity is key to increased efficiency leading to pore-formation.
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Affiliation(s)
- Manuela Mura
- Computational Physics Group and Institute for nanotechnology and Bioengineering, University of Central Lancashire, Preston PR1 2HE, UK
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25
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Mechanism of membrane perturbation by the HIV-1 gp41 membrane-proximal external region and its modulation by cholesterol. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2521-8. [PMID: 22692008 DOI: 10.1016/j.bbamem.2012.06.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 05/29/2012] [Accepted: 06/04/2012] [Indexed: 11/20/2022]
Abstract
Membrane-activity of the glycoprotein 41 membrane-proximal external region (MPER) is required for HIV-1 membrane fusion. Consequently, its inhibition results in viral neutralization by the antibody 4E10. Previous studies suggested that MPER might act during fusion by locally perturbing the viral membrane, i.e., following a mechanism similar to that proposed for certain antimicrobial peptides. Here, we explore the molecular mechanism of how MPER permeates lipid monolayers containing cholesterol, a main component of the viral envelope, using grazing incidence X-ray diffraction and X-ray reflectivity. Our studies reveal that helical MPER forms lytic pores under conditions not affecting the lateral packing order of lipids. Moreover, we observe an increment of the surface area occupied by MPER helices in cholesterol-enriched membranes, which correlates with an enhancement of the 4E10 epitope accessibility in lipid vesicles. Thus, our data support the view that curvature generation by MPER hydrophobic insertion into the viral membrane is functionally more relevant than lipid packing disruption.
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26
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Lorizate M, Kräusslich HG. Role of lipids in virus replication. Cold Spring Harb Perspect Biol 2011; 3:a004820. [PMID: 21628428 DOI: 10.1101/cshperspect.a004820] [Citation(s) in RCA: 181] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Viruses intricately interact with and modulate cellular membranes at several stages of their replication, but much less is known about the role of viral lipids compared to proteins and nucleic acids. All animal viruses have to cross membranes for cell entry and exit, which occurs by membrane fusion (in enveloped viruses), by transient local disruption of membrane integrity, or by cell lysis. Furthermore, many viruses interact with cellular membrane compartments during their replication and often induce cytoplasmic membrane structures, in which genome replication and assembly occurs. Recent studies revealed details of membrane interaction, membrane bending, fission, and fusion for a number of viruses and unraveled the lipid composition of raft-dependent and -independent viruses. Alterations of membrane lipid composition can block viral release and entry, and certain lipids act as fusion inhibitors, suggesting a potential as antiviral drugs. Here, we review viral interactions with cellular membranes important for virus entry, cytoplasmic genome replication, and virus egress.
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Affiliation(s)
- Maier Lorizate
- Department of Infectious Diseases, Virology, University Heidelberg, D-69120 Heidelberg, Germany
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27
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Read JA, Duncan R. Biophysical and functional assays for viral membrane fusion peptides. Methods 2011; 55:122-6. [PMID: 21958986 DOI: 10.1016/j.ymeth.2011.09.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 09/12/2011] [Accepted: 09/13/2011] [Indexed: 11/26/2022] Open
Abstract
Membrane fusion is a protein catalyzed biophysical reaction that involves the simultaneous intermixing of two phospholipid bilayers and of the aqueous compartments bound by their respective bilayers. In the case of enveloped virus fusogens, short hydrophobic or amphipathic fusion peptides that are components of the larger fusion complex are essential for the membrane merger event. The process of cell-cell membrane fusion and syncytium formation induced by the nonenveloped fusogenic orthoreoviruses is driven by the Fusion-Associated Small Transmembrane (FAST) proteins, which are similarly dependent on the action of fusion peptides. In this article, we describe some simple methods for the biophysical characterization of viral membrane fusion peptides. Liposomes serve as an ideal model system for characterizing peptide-membrane interactions because their size, shape and composition can be readily manipulated. We present details of fluorescence assays used to elucidate the kinetics of membrane fusion as well as complimentary assays used to characterize peptide-induced liposome binding and aggregation.
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Affiliation(s)
- Jolene A Read
- Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, Canada B3H4R2
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28
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Nieva JL, Apellaniz B, Huarte N, Lorizate M. A new paradigm in molecular recognition? specific antibody binding to membrane-inserted HIV-1 epitopes. J Mol Recognit 2011; 24:642-6. [DOI: 10.1002/jmr.1092] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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29
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Schmick SD, Weliky DP. Major antiparallel and minor parallel β sheet populations detected in the membrane-associated human immunodeficiency virus fusion peptide. Biochemistry 2010; 49:10623-35. [PMID: 21077643 PMCID: PMC3005821 DOI: 10.1021/bi101389r] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The HIV gp41 protein catalyzes fusion between viral and host cell membranes, and its apolar N-terminal region or "fusion peptide" binds to the host cell membrane and plays a key role in fusion. "HFP" is a construct containing the fusion peptide sequence, induces membrane vesicle fusion, and is an important fusion model system. Earlier solid-state nuclear magnetic resonance (SSNMR) studies showed that when HFP is associated with membranes with ∼30 mol % cholesterol, the first 16 residues have predominant β strand secondary structure and a fraction of the strands form antiparallel β sheet structure with residue 16→1/1→16 or 17→1/1→17 registries for adjacent strands. In some contrast, other SSNMR and infrared studies have been interpreted to support a large fraction of an approximately in-register parallel registry of adjacent strands. However, the samples had extensive isotopic labeling, and other structural models were also consistent with the data. This SSNMR study uses sparse labeling schemes that reduce ambiguity in the determination of the fraction of HFP molecules with parallel β registry. Quantitative analysis of the data shows that the parallel fraction is at most 0.15 with a much greater fraction of antiparallel 16→1/1→16 and 17→1/1→17 registries. These data strongly support a model of HFP-induced vesicle fusion caused by antiparallel rather than parallel registries and provide insight into the arrangement of gp41 molecules during HIV-host cell fusion. This study is an example of quantitative determination of a complex structural distribution by SSNMR, including experimentally validated inclusion of natural abundance contributions to the SSNMR data.
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Affiliation(s)
- Scott D. Schmick
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
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30
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Aromatic and polar residues spanning the candidate fusion peptide of the Andes virus Gc protein are essential for membrane fusion and infection. J Gen Virol 2010; 92:552-63. [DOI: 10.1099/vir.0.027235-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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31
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Li J, Das P, Zhou R. Single mutation effects on conformational change and membrane deformation of influenza hemagglutinin fusion peptides. J Phys Chem B 2010; 114:8799-806. [PMID: 20552971 DOI: 10.1021/jp1029163] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The single mutation effect on the conformational change and membrane permeation of influenza hemagglutinin fusion peptides has been studied with molecular dynamics simulations. A total of seven peptides, including wild-type fusion peptide and its six single point mutants (G1E, G1S, G1V, G4V, E11A, and W14A, all with no fusion or hemifusion activity) are examined systematically, which covers a wide range of mutation sites as well as mutant residue types (both hydrophobic and hydrophilic). The wild-type shows a kink structure (inversed V-shape), which facilitates the interaction between the fusion peptide and the lipid bilayer, as well as the interaction between the two arms of the fusion peptide. All mutants show a strong tendency toward a linear alpha-helix conformation, with the initial kink structure in the wild-type broken. More interestingly, one of the key hydrophobic residues around the initial kink region, Phe-9, is found to flip away from the membrane surface in most of these mutants. This conformational change causes a loss of key interactions between the original two arms of the inversed V-shape of the wild-type, thus disabling the kink structure, which results in the stabilization of the linear alpha-helix structure. The fusion peptides also display significant impact on the membrane structure deformation. The thickness of the lipid bilayer surrounding the wild-type fusion peptide decreases significantly, which induces a positive curvature of lipid bilayer. All the single mutations examined here reduce this membrane structural deformation, supporting the fusion activity data from experiments.
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Affiliation(s)
- Jingyuan Li
- Department of Physics, Zhejiang University, Hangzhou, 310027, China
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32
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Sackett K, Nethercott MJ, Epand RF, Epand RM, Kindra DR, Shai Y, Weliky DP. Comparative analysis of membrane-associated fusion peptide secondary structure and lipid mixing function of HIV gp41 constructs that model the early pre-hairpin intermediate and final hairpin conformations. J Mol Biol 2010; 397:301-15. [PMID: 20080102 PMCID: PMC2830311 DOI: 10.1016/j.jmb.2010.01.018] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2009] [Revised: 12/30/2009] [Accepted: 01/07/2010] [Indexed: 11/26/2022]
Abstract
Fusion between viral and host cell membranes is the initial step of human immunodeficiency virus infection and is mediated by the gp41 protein, which is embedded in the viral membrane. The approximately 20-residue N-terminal fusion peptide (FP) region of gp41 binds to the host cell membrane and plays a critical role in fusion catalysis. Key gp41 fusion conformations include an early pre-hairpin intermediate (PHI) characterized by extended coiled-coil structure in the region C-terminal of the FP and a final hairpin state with compact six-helix bundle structure. The large "N70" (gp41 1-70) and "FP-Hairpin" constructs of the present study contained the FP and respectively modeled the PHI and hairpin conformations. Comparison was also made to the shorter "FP34" (gp41 1-34) fragment. Studies were done in membranes with physiologically relevant cholesterol content and in membranes without cholesterol. In either membrane type, there were large differences in fusion function among the constructs with little fusion induced by FP-Hairpin, moderate fusion for FP34, and very rapid fusion for N70. Overall, our findings support acceleration of gp41-induced membrane fusion by early PHI conformation and fusion arrest after folding to the final six-helix bundle structure. FP secondary structure at Leu7 of the membrane-associated constructs was probed by solid-state nuclear magnetic resonance and showed populations of molecules with either beta-sheet or helical structure with greater beta-sheet population observed for FP34 than for N70 or FP-Hairpin. The large differences in fusion function among the constructs were not obviously correlated with FP secondary structure. Observation of cholesterol-dependent FP structure for fusogenic FP34 and N70 and cholesterol-independent structure for non-fusogenic FP-Hairpin was consistent with membrane insertion of the FP for FP34 and N70 and with lack of insertion for FP-Hairpin. Membrane insertion of the FP may therefore be associated with the early PHI conformation and FP withdrawal with the final hairpin conformation.
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Affiliation(s)
- Kelly Sackett
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
| | | | - Raquel F. Epand
- Department of Biochemistry and Biomedical Science, McMaster University, L8N 3Z5 Hamilton, Canada
| | - Richard M. Epand
- Department of Biochemistry and Biomedical Science, McMaster University, L8N 3Z5 Hamilton, Canada
| | - Douglas R. Kindra
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
| | - Yechiel Shai
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - David P. Weliky
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824
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33
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Sun Y, Weliky DP. 13C-13C correlation spectroscopy of membrane-associated influenza virus fusion peptide strongly supports a helix-turn-helix motif and two turn conformations. J Am Chem Soc 2010; 131:13228-9. [PMID: 19711890 DOI: 10.1021/ja905198q] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The influenza virus fusion peptide (IFP) is the N-terminal domain of the viral hemagglutinin protein, binds to the endosomal membrane, and plays a critical role in fusion between the viral and endosomal membranes which is a primary step in infection. The IFP is also an important system for testing simulation methods for membrane-associated peptides. In detergent, the IFP forms helix-turn-helix and helix-turn-strand structures at pH 5.0 and 7.4, respectively, while simulations in membranes by different groups have yielded conflicting results with some reports of a continuous helix without a turn. In this study, (13)C-(13)C NMR correlation spectra were obtained for the membrane-associated IFP and the (13)C chemical shifts supported a helix-turn-helix motif at both pH 5.0 and 7.4 with an alternate turn conformation at pH 5.0 that was absent at pH 7.4. The alternate conformation was correlated with protonation of the side chain of Glu-11 in the turn and with greater fusion at pH 5.0. The structures are overall consistent with the hypothesis of "inverted V" membrane location of the IFP with insertion of the N-terminal region into the membrane and contact of the turn with the lipid/water interface. The positions of hydrophobic residues in the pH 5.0 structure may favor membrane insertion with resultant increased membrane perturbation and fusion rate. In addition to their functional relevance, these IFP structures are important reference data for simulations of the membrane-associated IFP which can in principle detect the full conformational distribution of the IFP.
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Affiliation(s)
- Yan Sun
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
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34
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Role of membrane lipids for the activity of pore forming peptides and proteins. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 677:31-55. [PMID: 20687479 DOI: 10.1007/978-1-4419-6327-7_4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Bilayer lipids, far from being passive elements, have multiple roles in polypeptide-dependent pore formation. Lipids participate at all stages of the formation of pores by providing the binding site for proteins and peptides, conditioning their active structure and modulating the molecular reorganization of the membrane complex. Such general functions of lipids superimpose to other particular roles, from electrostatic and curvature effects to more specific actions in cases like cholesterol, sphingolipids or cardiolipin. Pores are natural phenomena in lipid membranes. Driven by membrane fluctuations and packing defects, transient water pores are related to spontaneous lipid flip-flop and non-assisted ion permeation. In the absence ofproteins or peptides, these are rare short living events, with properties dependent on the lipid composition of the membrane. Their frequency increases under conditions of internal membrane disturbance of the lipid packing, like in the presence of membrane-bound proteins or peptides. These latter molecules, in fact, form dynamic supramolecular assemblies together with the lipids and transmembrane pores are one of the possible structures of the complex. Active peptides and proteins can thus be considered inducers or enhancers of pores which increase their probability and lifetime by modifying the thermodynamic membrane balance. This includes destabilizing the membrane lamellar structure, lowering the activation energy for pore formation and stabilizing the open pore structure.
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35
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Apellániz B, Nir S, Nieva JL. Distinct mechanisms of lipid bilayer perturbation induced by peptides derived from the membrane-proximal external region of HIV-1 gp41. Biochemistry 2009; 48:5320-31. [PMID: 19449801 DOI: 10.1021/bi900504t] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The conserved, membrane-proximal external region (MPER) of the human immunodeficiency virus type-1 envelope glycoprotein 41 subunit is required for fusogenic activity. It has been proposed that MPER functions by disrupting the virion membrane. Supporting its critical role in viral entry as a membrane-bound entity, MPER constitutes the target for broadly neutralizing antibodies that have evolved mechanisms to recognize membrane-inserted epitopes. We have analyzed here the molecular mechanisms of membrane permeabilization induced by N-preTM and PreTM-C, two peptides derived from MPER sequences showing a tendency to associate with the bilayer interface or to transfer into the hydrocarbon core, respectively. Both peptides contained the full epitope sequence recognized by the 4E10 monoclonal antibody (MAb4E10), which was subsequently used to probe peptide accessibility from the water phase. Capacities of N-preTM and PreTM-C for associating with vesicles and inducing their permeabilization were comparable. However, MAb4E10 specifically blocked the permeabilization induced by N-preTM but did not appreciably affect that induced by PreTM-C. Supporting the existence of different membrane-bound lytic structures, N-preTM was running as a monomer on SDS-PAGE and induced the graded release of vesicular contents, whereas PreTM-C migrated on SDS-PAGE as dimers and permeabilized vesicles following an all-or-none mechanism, reminiscent of that underlying melittin-induced membrane lysis. These results support the functional segmentation of gp41 membrane regions into hydrophobic subdomains, which might expose neutralizing epitopes and induce membrane-disrupting effects following distinct patterns during the fusion cascade.
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Affiliation(s)
- Beatriz Apellániz
- Unidad de Biofisica (CSIC-UPV/EHU) and Departamento de Bioquimica, Universidad del Pais Vasco, Aptdo. 644, 48080 Bilbao, Spain
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36
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Abad C, Martínez-Gil L, Tamborero S, Mingarro I. Membrane topology of gp41 and amyloid precursor protein: interfering transmembrane interactions as potential targets for HIV and Alzheimer treatment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:2132-41. [PMID: 19619504 PMCID: PMC7094694 DOI: 10.1016/j.bbamem.2009.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Revised: 06/29/2009] [Accepted: 07/13/2009] [Indexed: 01/08/2023]
Abstract
The amyloid precursor protein (APP), that plays a critical role in the development of senile plaques in Alzheimer disease (AD), and the gp41 envelope protein of the human immunodeficiency virus (HIV), the causative agent of the acquired immunodeficiency syndrome (AIDS), are single-spanning type-1 transmembrane (TM) glycoproteins with the ability to form homo-oligomers. In this review we describe similarities, both in structural terms and sequence determinants of their TM and juxtamembrane regions. The TM domains are essential not only for anchoring the proteins in membranes but also have functional roles. Both TM segments contain GxxxG motifs that drive TM associations within the lipid bilayer. They also each possess similar sequence motifs, positioned at the membrane interface preceding their TM domains. These domains are known as cholesterol recognition/interaction amino acid consensus (CRAC) motif in gp41 and CRAC-like motif in APP. Moreover, in the cytoplasmic domain of both proteins other α-helical membranotropic regions with functional implications have been identified. Recent drug developments targeting both diseases are reviewed and the potential use of TM interaction modulators as therapeutic targets is discussed.
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Affiliation(s)
- Concepción Abad
- Departament de Bioquímica i Biologia Molecular, Universitat de València. Dr. Moliner, 50, E-46100 Burjassot, Spain
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37
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A charged second-site mutation in the fusion peptide rescues replication of a mutant avian sarcoma and leukosis virus lacking critical cysteine residues flanking the internal fusion domain. J Virol 2009; 83:8575-86. [PMID: 19515762 DOI: 10.1128/jvi.00526-09] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The entry process of the avian sarcoma and leukosis virus (ASLV) family of retroviruses requires first a specific interaction between the viral surface (SU) glycoproteins and a receptor on the cell surface at a neutral pH, triggering conformational changes in the viral SU and transmembrane (TM) glycoproteins, followed by exposure to low pH to complete fusion. The ASLV TM glycoprotein has been proposed to adopt a structure similar to that of the Ebola virus GP2 protein: each contains an internal fusion peptide flanked by cysteine residues predicted to be in a disulfide bond. In a previous study, we concluded that the cysteines flanking the internal fusion peptide in ASLV TM are critical for efficient function of the ASLV viral glycoproteins in mediating entry. In this study, replication-competent ASLV mutant subgroup A [ASLV(A)] variants with these cysteine residues mutated were constructed and genetically selected for improved replication capacity in chicken fibroblasts. Viruses with single cysteine-to-serine mutations reverted to the wild-type sequence. However, viruses with both C9S and C45S (C9,45S) mutations retained both mutations and acquired a second-site mutation that significantly improved the infectivity of the genetically selected virus population. A charged-amino-acid second-site substitution in the TM internal fusion peptide at position 30 is preferred to rescue the C9,45S mutant ASLV(A). ASLV(A) envelope glycoproteins that contain the C9,45S and G30R mutations bind the Tva receptor at wild-type levels and have improved abilities to trigger conformational changes and to form stable TM oligomers compared to those of the C9,45S mutant glycoprotein.
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38
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Herrera E, Gomara MJ, Mazzini S, Ragg E, Haro I. Synthetic Peptides of Hepatitis G Virus (GBV-C/HGV) in the Selection of Putative Peptide Inhibitors of the HIV-1 Fusion Peptide. J Phys Chem B 2009; 113:7383-91. [DOI: 10.1021/jp900707t] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Elena Herrera
- Unit of Synthesis and Biomedical Applications of Peptides, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain, and Department of Agri-Food Molecular Sciences, Università degli Studi, via Celoria 2, 20133 Milano, Italy
| | - Maria J. Gomara
- Unit of Synthesis and Biomedical Applications of Peptides, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain, and Department of Agri-Food Molecular Sciences, Università degli Studi, via Celoria 2, 20133 Milano, Italy
| | - Stefania Mazzini
- Unit of Synthesis and Biomedical Applications of Peptides, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain, and Department of Agri-Food Molecular Sciences, Università degli Studi, via Celoria 2, 20133 Milano, Italy
| | - Enzio Ragg
- Unit of Synthesis and Biomedical Applications of Peptides, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain, and Department of Agri-Food Molecular Sciences, Università degli Studi, via Celoria 2, 20133 Milano, Italy
| | - Isabel Haro
- Unit of Synthesis and Biomedical Applications of Peptides, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain, and Department of Agri-Food Molecular Sciences, Università degli Studi, via Celoria 2, 20133 Milano, Italy
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The membrane-proximal external region of the human immunodeficiency virus type 1 envelope: dominant site of antibody neutralization and target for vaccine design. Microbiol Mol Biol Rev 2008; 72:54-84, table of contents. [PMID: 18322034 DOI: 10.1128/mmbr.00020-07] [Citation(s) in RCA: 202] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Enormous efforts have been made to produce a protective vaccine against human immunodeficiency virus type 1; there has been little success. However, the identification of broadly neutralizing antibodies against epitopes on the highly conserved membrane-proximal external region (MPER) of the gp41 envelope protein has delineated this region as an attractive vaccine target. Furthermore, emerging structural information on the MPER has provided vaccine designers with new insights for building relevant immunogens. This review describes the current state of the field regarding (i) the structure and function of the gp41 MPER; (ii) the structure and binding mechanisms of the broadly neutralizing antibodies 2F5, 4E10, and Z13; and (iii) the development of an MPER-targeting vaccine. In addition, emerging approaches to vaccine design are presented.
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40
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Weise K, Reed J. Fusion Peptides and Transmembrane Domains of Fusion Proteins are Characterized by Different but Specific Structural Properties. Chembiochem 2008; 9:934-43. [DOI: 10.1002/cbic.200700386] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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41
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Bodner ML, Gabrys CM, Struppe JO, Weliky DP. C13–C13 and N15–C13 correlation spectroscopy of membrane-associated and uniformly labeled human immunodeficiency virus and influenza fusion peptides: Amino acid-type assignments and evidence for multiple conformations. J Chem Phys 2008; 128:052319. [DOI: 10.1063/1.2829984] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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42
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Viard M, Ablan SD, Zhou M, Veenstra TD, Freed EO, Raviv Y, Blumenthal R. Photoinduced reactivity of the HIV-1 envelope glycoprotein with a membrane-embedded probe reveals insertion of portions of the HIV-1 Gp41 cytoplasmic tail into the viral membrane. Biochemistry 2008; 47:1977-83. [PMID: 18198900 DOI: 10.1021/bi701920f] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The interactions of HIV-1 Env (gp120-gp41) with CD4 and coreceptors trigger a barrage of conformational changes in Env that drive the membrane fusion process. Various regions of gp41 have profound effects on HIV entry and budding. However, the precise interactions between gp41 and the membrane have not been elucidated. To examine portions of membrane proteins that are embedded in membrane lipids, we have studied photoinduced chemical reactions in membranes using the lipid bilayer specific probe iodonaphthyl azide (INA). Here we show that in addition to the transmembrane anchor, amphipatic sequences in the cytoplasmic tail (CT) of HIV-1 gp41 are labeled by INA. INA labeling of the HIV-1 gp41 CT was similar whether wild-type or a mutant HIV-1 was used with uncleaved p55 Gag, which does not allow entry. These results shed light on the disposition of the HIV-1 gp41 CT with respect to the membrane. Moreover, our data have general implications for topology of membrane proteins and their in situ interactions with the lipid bilayer.
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Affiliation(s)
- Mathias Viard
- Center of Cancer Research Nanobiology Program, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, USA
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43
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Lorizate M, Huarte N, Sáez-Cirión A, Nieva JL. Interfacial pre-transmembrane domains in viral proteins promoting membrane fusion and fission. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:1624-39. [PMID: 18222166 PMCID: PMC7094410 DOI: 10.1016/j.bbamem.2007.12.018] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/05/2007] [Revised: 12/17/2007] [Accepted: 12/20/2007] [Indexed: 12/02/2022]
Abstract
Membrane fusion and fission underlie two limiting steps of enveloped virus replication cycle: access to the interior of the host-cell (entry) and dissemination of viral progeny after replication (budding), respectively. These dynamic processes proceed mediated by specialized proteins that disrupt and bend the lipid bilayer organization transiently and locally. We introduced Wimley–White membrane-water partitioning free energies of the amino acids as an algorithm for predicting functional domains that may transmit protein conformational energy into membranes. It was found that many viral products possess unusually extended, aromatic-rich pre-transmembrane stretches predicted to stably reside at the membrane interface. Here, we review structure–function studies, as well as data reported on the interaction of representative peptides with model membranes, all of which sustain a functional role for these domains in viral fusion and fission. Since pre-transmembrane sequences also constitute antigenic determinants in a membrane-bound state, we also describe some recent results on their recognition and blocking at membrane interface by neutralizing antibodies.
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Affiliation(s)
| | | | | | - José L. Nieva
- Corresponding author. Unidad de Biofísica, Universidad del País Vasco, Aptdo. 644, 48080 Bilbao, Spain. Tel.: +34 94 6013353; fax: +34 94 6013360.
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Barz B, Wong TC, Kosztin I. Membrane curvature and surface area per lipid affect the conformation and oligomeric state of HIV-1 fusion peptide: a combined FTIR and MD simulation study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1778:945-53. [PMID: 18177732 DOI: 10.1016/j.bbamem.2007.11.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 11/19/2007] [Accepted: 11/21/2007] [Indexed: 11/29/2022]
Abstract
Fourier-transformed infrared spectroscopy (FTIR) and molecular dynamics (MD) simulation results are presented to support our hypothesis that the conformation and the oligomeric state of the HIV-1 gp41 fusion domain or fusion peptide (gp41-FP) are determined by the membrane surface area per lipid (APL), which is affected by the membrane curvature. FTIR of the gp41-FP in the Aerosol-OT (AOT) reversed micellar system showed that as APL decreases from approximately 50 to 35 A2 by varying the AOT/water ratio, the FP changes from the monomeric alpha-helical to the oligomeric beta-sheet structure. MD simulations in POPE lipid bilayer systems showed that as the APL decreases by applying a negative surface tension, helical monomers start to unfold into turn-like structures. Furthermore, an increase in the applied lateral pressure during nonequilibrium MD simulations favored the formation of beta-sheet structure. These results provide better insight into the relationship between the structures of the gp41-FP and the membrane, which is essential in understanding the membrane fusion process. The implication of the results of this work on what is the fusogenic structure of the HIV-1 FP is discussed.
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Affiliation(s)
- Bogdan Barz
- Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO 65211, USA
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Affiliation(s)
- Kevin R Mackenzie
- Department of Biochemistry and Cell Biology, Rice University, Houston, Texas 77005, USA
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46
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Lorin A, Lins L, Stroobant V, Brasseur R, Charloteaux B. The minimal fusion peptide of simian immunodeficiency virus corresponds to the 11 first residues of gp32. J Pept Sci 2007; 14:423-8. [DOI: 10.1002/psc.949] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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47
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Gabrys CM, Weliky DP. Chemical shift assignment and structural plasticity of a HIV fusion peptide derivative in dodecylphosphocholine micelles. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:3225-34. [PMID: 17935693 DOI: 10.1016/j.bbamem.2007.07.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2007] [Revised: 07/31/2007] [Accepted: 07/31/2007] [Indexed: 10/22/2022]
Abstract
A "HFPK3" peptide containing the 23 residues of the human immunodeficiency virus (HIV) fusion peptide (HFP) plus three non-native C-terminal lysines was studied in dodecylphosphocholine (DPC) micelles with 2D 1H NMR spectroscopy. The HFP is at the N-terminus of the gp41 fusion protein and plays an important role in fusing viral and target cell membranes which is a critical step in viral infection. Unlike HFP, HFPK3 is monomeric in detergent-free buffered aqueous solution which may be a useful property for functional and structural studies. H alpha chemical shifts indicated that DPC-associated HFPK3 was predominantly helical from I4 to L12. In addition to the highest-intensity crosspeaks used for the first chemical shift assignment (denoted I), there were additional crosspeaks whose intensities were approximately 10% of those used for assignment I. A second assignment (II) for residues G5 to L12 as well as a few other residues was derived from these lower-intensity crosspeaks. Relative to the I shifts, the II shifts were different by 0.01-0.23 ppm with the largest differences observed for HN. Comparison of the shifts of DPC-associated HFPK3 with those of detergent-associated HFP and HFP derivatives provided information about peptide structures and locations in micelles.
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Affiliation(s)
- Charles M Gabrys
- Department of Chemistry, Michigan State University, East Lansing, MI 48824-1320, USA
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Mazzini S, Fernandez-Vidal M, Galbusera V, Castro-Roman F, Bellucci MC, Ragg E, Haro I. 3D-Structure of the interior fusion peptide of HGV/GBV-C by 1H NMR, CD and molecular dynamics studies. Arch Biochem Biophys 2007; 465:187-96. [PMID: 17603997 DOI: 10.1016/j.abb.2007.05.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 05/28/2007] [Accepted: 05/30/2007] [Indexed: 11/24/2022]
Abstract
In this work, we present a structural characterization of the putative fusion peptide E2(279-298) corresponding to the E2 envelope protein of the HGV/GBV-C virus by (1)H NMR, CD and MD studies performed in H(2)O/TFE and in lipid model membranes. The peptide is largely unstructured in water, whereas in H(2)O/TFE and in model membranes it adopts an helical structure (approximately 65-70%). The partitioning free energy DeltaG ranges from -6 to -7.5 kcal mol(-1). OCD measurements on peptide-containing hydrated and oriented lipid multilayers showed that the peptide adopts a predominantly surface orientation. The (1)H NMR data (observed NOEs, deuterium exchange rates, Halpha chemical shift index and vicinal coupling constants) and the molecular dynamics calculations support the conclusions that the peptide adopts a stable helix in the C-terminal 9-18 residues slightly inserted into the lipid bilayer and a major mobility in the amino terminus of the sequence (1-8 residues).
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Affiliation(s)
- S Mazzini
- Department of Agri-Food Molecular Sciences, Università degli Studi, via Celoria 2, 20133 Milano, Italy.
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Carneiro FA, Vandenbussche G, Juliano MA, Juliano L, Ruysschaert JM, Da Poian AT. Charged residues are involved in membrane fusion mediated by a hydrophilic peptide located in vesicular stomatitis virus G protein. Mol Membr Biol 2007; 23:396-406. [PMID: 17060157 DOI: 10.1080/09687860600780892] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Membrane fusion is an essential step of the internalization process of the enveloped animal viruses. Vesicular stomatitis virus (VSV) infection is mediated by virus spike glycoprotein G, which induces membrane fusion at the acidic environment of the endosomal compartment. In a previous work, we identified a specific sequence in VSV G protein, comprising the residues 145 to 164, directly involved in membrane interaction and fusion. Unlike fusion peptides from other viruses, this sequence is very hydrophilic, containing six charged residues, but it was as efficient as the virus in catalyzing membrane fusion at pH 6.0. Using a carboxyl-modifying agent, dicyclohexylcarbodiimide (DCCD), and several synthetic mutant peptides, we demonstrated that the negative charges of peptide acidic residues, especially Asp153 and Glu158, participate in the formation of a hydrophobic domain at pH 6.0, which is necessary to the peptide-induced membrane fusion. The formation of the hydrophobic region and the membrane fusion itself were dependent on peptide concentration in a higher than linear fashion, suggesting the involvement of peptide oligomerization. His148 was also necessary to hydrophobicity and fusion, suggesting that peptide oligomerization occurs through intermolecular electrostatic interactions between the positively-charged His and a negatively-charged acidic residue of two peptide molecules. Oligomerization of hydrophilic peptides creates a hydrophobic region that is essential for the interaction with the membrane that results in fusion.
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Affiliation(s)
- Fabiana A Carneiro
- Instituto de Bioquímica Médica, Programa de Biologia Molecular e Biotecnologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Zheng Z, Yang R, Bodner ML, Weliky DP. Conformational flexibility and strand arrangements of the membrane-associated HIV fusion peptide trimer probed by solid-state NMR spectroscopy. Biochemistry 2006; 45:12960-75. [PMID: 17059213 PMCID: PMC2570372 DOI: 10.1021/bi0615902] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human immunodeficiency virus (HIV) fusion peptide (HFP) is the N-terminal apolar region of the HIV gp41 fusion protein and interacts with target cell membranes and promotes membrane fusion. The free peptide catalyzes vesicle fusion at least to the lipid mixing stage and serves as a useful model fusion system. For gp41 constructs which lack the HFP, high-resolution structures show trimeric protein and suggest that at least three HFPs interact with the membrane with their C-termini in close proximity. In addition, previous studies have demonstrated that HFPs which are cross-linked at their C-termini to form trimers (HFPtr) catalyze fusion at a rate which is 15-40 times greater than that of non-cross-linked HFP. In the present study, the structure of membrane-associated HFPtr was probed with solid-state nuclear magnetic resonance (NMR) methods. Chemical shift and intramolecular (13)CO-(15)N distance measurements show that the conformation of the Leu-7 to Phe-11 region of HFPtr has predominant helical conformation in membranes without cholesterol and beta strand conformation in membranes containing approximately 30 mol % cholesterol. Interstrand (13)CO-(13)CO and (13)CO-(15)N distance measurements were not consistent with an in-register parallel strand arrangement but were consistent with either (1) parallel arrangement with adjacent strands two residues out-of-register or (2) antiparallel arrangement with adjacent strand crossing between Phe-8 and Leu-9. Arrangement 1 could support the rapid fusion rate of HFPtr because of placement of the apolar N-terminal regions of all strands on the same side of the oligomer while arrangement 2 could support the assembly of multiple fusion protein trimers.
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Affiliation(s)
- Zhaoxiong Zheng
- Department of Chemistry Michigan State University East Lansing, MI 48824
| | - Rong Yang
- Department of Physiology and Cellular Biophysics Columbia University New York, NY 11032
| | - Michele L. Bodner
- Department of Chemistry Michigan State University East Lansing, MI 48824
| | - David P. Weliky
- Department of Chemistry Michigan State University East Lansing, MI 48824
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