1
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Zhang H, Liang X, Li D, Zhang C, Wang W, Tang R, Zhang H, Kiflu AB, Liu C, Liang J, Li X, Luo TR. Apolipoprotein D facilitates rabies virus propagation by interacting with G protein and upregulating cholesterol. Front Immunol 2024; 15:1392804. [PMID: 38868762 PMCID: PMC11167634 DOI: 10.3389/fimmu.2024.1392804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 05/02/2024] [Indexed: 06/14/2024] Open
Abstract
Rabies virus (RABV) causes a fatal neurological disease, consisting of unsegmented negative-strand RNA, which encodes five structural proteins (3'-N-P-M-G-L-5'). Apolipoprotein D (ApoD), a lipocalin, is upregulated in the nervous system after injury or pathological changes. Few studies have focused on the role of ApoD during virus infection so far. This study demonstrated that ApoD is upregulated in the mouse brain (in vivo) and C8-D1A cells (in vitro) after RABV infection. By upregulating ApoD expression in C8-D1A cells, we found that ApoD facilitated RABV replication. Additionally, Co-immunoprecipitation demonstrated that ApoD interacted with RABV glycoprotein (G protein). The interaction could promote RABV replication by upregulating the cholesterol level. These findings revealed a novel role of ApoD in promoting RABV replication and provided a potential therapeutic target for rabies.
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Affiliation(s)
- Hongyan Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
| | - Xingxue Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
| | - Duoduo Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
| | - Chuanliang Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
| | - Wenfeng Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
| | - Rongze Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
| | - Hongyun Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
| | - Abraha Bahlbi Kiflu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
| | - Cheng Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
- Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Guangxi University, Nanning, China
- Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Guangxi University, Nanning, China
| | - Jingjing Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
- Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Guangxi University, Nanning, China
- Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Guangxi University, Nanning, China
| | - Xiaoning Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
- Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Guangxi University, Nanning, China
- Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Guangxi University, Nanning, China
| | - Ting Rong Luo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, Guangxi University, Nanning, China
- College of Animal Sciences and Veterinary Medicine, Guangxi University, Nanning, China
- Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Guangxi University, Nanning, China
- Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Guangxi University, Nanning, China
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2
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Birtles D, Abbas W, Lee J. Bis(Monoacylglycero)Phosphate Promotes Membrane Fusion Facilitated by the SARS-CoV-2 Fusion Domain. J Phys Chem B 2024; 128:2675-2683. [PMID: 38466655 DOI: 10.1021/acs.jpcb.3c07863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2024]
Abstract
Membrane fusion is a critical component of the viral lifecycle. For SARS-CoV-2, fusion is facilitated by the spike glycoprotein and can take place via either the plasma membrane or the endocytic pathway. The fusion domain (FD), which is found within the spike glycoprotein, is primarily responsible for the initiation of fusion as it embeds itself within the target cell's membrane. A preference for SARS-CoV-2 to fuse at low pH akin to the environment of the endocytic pathway has already been established; however, the impact of the target cell's lipid composition on the FD has yet to be explored. Here, we have shown that the SARS-CoV-2 FD preferentially initiates fusion at the late endosomal membrane over the plasma membrane, on the basis of lipid composition alone. A positive, fusogenic relationship with anionic lipids from the plasma membrane (POPS: 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine) and endosomal membrane (BMP: bis(monoacylglycero)phosphate) was established, with a large preference demonstrated for the latter. When comparing the binding affinity and secondary structure of the FD in the presence of different anionic lipids, little deviation was evident while the charge was maintained. However, it was discovered that BMP had a subtle, negative impact on lipid packing in comparison to that of POPS. Furthermore, an inverse relationship between lipid packing and the fusogenecity of the SARS-CoV-2 FD was witnessed. In conclusion, the SARS-CoV-2 FD preferentially initiates fusion at a membrane resembling that of the late endosomal compartment, predominately due to the presence of BMP and its impact on lipid packing.
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Affiliation(s)
- Daniel Birtles
- Department of Chemistry and Biochemistry, University of Maryland, College Park 20742, Maryland, United States
| | - Wafa Abbas
- Department of Chemistry and Biochemistry, University of Maryland, College Park 20742, Maryland, United States
| | - Jinwoo Lee
- Department of Chemistry and Biochemistry, University of Maryland, College Park 20742, Maryland, United States
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3
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Ward AE, Sokovikova D, Waxham MN, Heberle FA, Levental I, Levental KR, Kiessling V, White JM, Tamm LK. Serinc5 Restricts HIV Membrane Fusion by Altering Lipid Order and Heterogeneity in the Viral Membrane. ACS Infect Dis 2023; 9:773-784. [PMID: 36946615 PMCID: PMC10366416 DOI: 10.1021/acsinfecdis.2c00478] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
The host restriction factor, Serinc5, incorporates into budding HIV particles and inhibits their infection by an incompletely understood mechanism. We have previously reported that Serinc5 but not its paralogue, Serinc2, blocks HIV cell entry by membrane fusion, specifically by inhibiting fusion pore formation and dilation. A body of work suggests that Serinc5 may alter the conformation and clustering of the HIV fusion protein, Env. To contribute an additional perspective to the developing model of Serinc5 restriction, we assessed Serinc2 and Serinc5's effects on HIV pseudoviral membranes. By measuring pseudoviral membrane thickness via cryo-electron microscopy and order via the fluorescent dye, FLIPPER-TR, Serinc5 was found to increase membrane heterogeneity, skewing the distribution toward a larger fraction of the viral membrane in an ordered phase. We also directly observed for the first time the coexistence of membrane domains within individual viral membrane envelopes. Using a total internal reflection fluorescence-based single particle fusion assay, we found that treatment of HIV pseudoviral particles with phosphatidylethanolamine (PE) rescued HIV pseudovirus fusion from restriction by Serinc5, which was accompanied by decreased membrane heterogeneity and order. This effect was specific for PE and did not depend on acyl chain length or saturation. Together, these data suggest that Serinc5 alters multiple interrelated properties of the viral membrane─lipid chain order, rigidity, line tension, and lateral pressure─which decrease the accessibility of fusion intermediates and disfavor completion of fusion. These biophysical insights into Serinc5 restriction of HIV infectivity could contribute to the development of novel antivirals that exploit the same weaknesses.
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Affiliation(s)
- Amanda E. Ward
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Daria Sokovikova
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Melvin Neal Waxham
- Department of Neurobiology and Anatomy, The University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX 77030
| | | | - Ilya Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Kandice R. Levental
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
| | - Judith M. White
- Department of Cell Biology, University of Virginia Health System, Charlottesville, VA 22908
| | - Lukas K. Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia Health System, Charlottesville, VA 22908
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA 22908
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4
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The Lipid Raft-Associated Protein Stomatin Is Required for Accumulation of Dectin-1 in the Phagosomal Membrane and for Full Activity of Macrophages against Aspergillus fumigatus. mSphere 2023; 8:e0052322. [PMID: 36719247 PMCID: PMC9942578 DOI: 10.1128/msphere.00523-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Alveolar macrophages belong to the first line of defense against inhaled conidia of the human-pathogenic fungus Aspergillus fumigatus. In lung alveoli, they contribute to phagocytosis and elimination of conidia. As a counterdefense, conidia have a gray-green pigment that enables them to survive in phagosomes of macrophages for some time. Previously, we showed that this conidial pigment interferes with the formation of flotillin-dependent lipid raft microdomains in the phagosomal membrane, thereby preventing the formation of functional phagolysosomes. Besides flotillins, stomatin is a major component of lipid rafts and can be targeted to the membrane. However, only limited information on stomatin is available, in particular on its role in defense against pathogens. To determine the function of this integral membrane protein, a stomatin-deficient macrophage line was generated by CRISPR/Cas9 gene editing. Immunofluorescence microscopy and flow cytometry revealed that stomatin contributes to the phagocytosis of conidia and is important for recruitment of the β-glucan receptor dectin-1 to both the cytoplasmic membrane and phagosomal membrane. In stomatin knockout cells, fusion of phagosomes and lysosomes, recruitment of the vATPase to phagosomes, and tumor necrosis factor alpha (TNF-α) levels were reduced when cells were infected with pigmentless conidia. Thus, our data suggest that stomatin is involved in maturation of phagosomes via fostering fusion of phagosomes with lysosomes. IMPORTANCE Stomatin is an integral membrane protein that contributes to the uptake of microbes, e.g., spores of the human-pathogenic fungus Aspergillus fumigatus. By generation of a stomatin-deficient macrophage line by advanced genetic engineering, we found that stomatin is involved in the recruitment of the β-glucan receptor dectin-1 to the phagosomal membrane of macrophages. Furthermore, stomatin is involved in maturation of phagosomes via fostering fusion of phagosomes with lysosomes. The data provide new insights on the important role of stomatin in the immune response against human-pathogenic fungi.
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5
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Fei S, Xia J, Ma G, Zhang M, Sun J, Feng M, Wang Y. Apolipoprotein D facilitate the proliferation of BmNPV. Int J Biol Macromol 2022; 223:830-836. [PMID: 36372108 DOI: 10.1016/j.ijbiomac.2022.11.032] [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: 08/22/2022] [Revised: 10/30/2022] [Accepted: 11/02/2022] [Indexed: 11/13/2022]
Abstract
The silkworm, Bombyx mori, a model Lepidopteran specie, is an important economic insect. It is specifically infected by Bombyx mori nucleopolyhedrovirus (BmNPV), causing huge losses to the sericulture industry. Therefore, the understandings of the interaction mechanism between BmNPV and the host will help to provide the theoretical basis for the sericulture industry to control BmNPV. Apolipoprotein D (ApoD) is a member of lipid transport family and capable of binding to a variety of lipophilic ligands. ApoD is mainly used in neurodegenerative disease research in mammals, and there is little research on ApoD against viruses. Here, we explored the effects of Bombyx mori Apolipoprotein D (BmApoD) on BmNPV replication. We knocked out and overexpressed BmApoD in BmN cells and infected them with Bombyx mori nucleopolyhedrovirus (BmNPV). The results showed that BmApoD promote the replication of BmNPV in BmN cells. It was also confirmed that BmApoD promote the replication of BmNPV after knocking down BmApoD in silkworm larvae. This study is the first to explore the role of ApoD in insect-virus interactions, providing new insights into the functional role of ApoD.
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Affiliation(s)
- Shigang Fei
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Junming Xia
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Guangyu Ma
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Mengmeng Zhang
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China
| | - Jingchen Sun
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China.
| | - Min Feng
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China.
| | - Yeyuan Wang
- Guangdong Provincial Key Laboratory of Agro-Animal Genomics and Molecular Breeding, College of Animal Science, South China Agricultural University, Guangzhou, China.
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6
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Villamil Giraldo AM, Mannsverk S, Kasson PM. Measuring single-virus fusion kinetics using an assay for nucleic acid exposure. Biophys J 2022; 121:4467-4475. [PMID: 36330566 PMCID: PMC9748363 DOI: 10.1016/j.bpj.2022.11.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 09/26/2022] [Accepted: 10/31/2022] [Indexed: 11/11/2022] Open
Abstract
The kinetics by which individual enveloped viruses fuse with membranes provide an important window into viral-entry mechanisms. We have developed a real-time assay using fluorescent probes for single-virus genome exposure than can report on stages of viral entry including or subsequent to fusion pore formation and prior to viral genome trafficking. We accomplish this using oxazole yellow nucleic-acid-binding dyes, which can be encapsulated in the lumen of target membranes to permit specific detection of fusion events. Since increased fluorescence of the dye occurs only when it encounters viral genome via a fusion pore and binds, this assay excludes content leakage without fusion. Using this assay, we show that influenza virus fuses with liposomes of different sizes with indistinguishable kinetics by both testing liposomes extruded through pores of different radii and showing that the fusion kinetics of individual liposomes are uncorrelated with the size of the liposome. These results suggest that the starting curvature of such liposomes does not control the rate-limiting steps in influenza entry.
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Affiliation(s)
- Ana M Villamil Giraldo
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Steinar Mannsverk
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - Peter M Kasson
- Science for Life Laboratory, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden; Departments of Molecular Physiology and Biomedical Engineering, University of Virginia, Charlottesville, Virginia.
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7
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Birtles D, Oh AE, Lee J. Exploring the
pH
dependence of the
SARS‐CoV
‐2 complete fusion domain and the role of its unique structural features. Protein Sci 2022. [PMCID: PMC9538437 DOI: 10.1002/pro.4390] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
SARS‐CoV‐2 may enter target cells through the process of membrane fusion at either the plasma (~pH 7.4–7.0) or endosomal (~pH 6.5–5.0) membrane in order to deliver its genetic information. The fusion domain (FD) of the spike glycoprotein is responsible for initiating fusion and is thus integral to the viral life cycle. The FD of SARS‐CoV‐2 is unique in that it consists of two structurally distinctive regions referred to as the fusion peptide (FP) and the fusion loop (FL); yet the molecular mechanisms behind how this FD perturbs the membrane to initiate fusion remains unclear. In this study via solution NMR, we witnessed only a slight conformational change in the FD between pH 7.4 and pH 5.0, resulting in a minor elongation of helix 1. However, we found that the FD's ability to mediate membrane fusion has a large and significant pH dependence, with fusion events being more readily induced at low pH. Interestingly, a biphasic relationship between the environmental pH and fusogenicity was discovered, suggesting a preference for the FD to initiate fusion at the late endosomal membrane. Furthermore, the conserved disulfide bond and hydrophobic motif “LLF” were found to be critical for the function of the complete FD, with minimal activity witnessed when either was perturbed. In conclusion, these findings indicate that the SARS‐CoV‐2 FD preferably initiates fusion at a pH similar to the late endosome through a mechanism that heavily relies on the internal disulfide bond of the FL and hydrophobic LLF motif within the FP.
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Affiliation(s)
- Daniel Birtles
- Department of Chemistry and Biochemistry University of Maryland College Park Maryland USA
| | - Anna E. Oh
- Department of Chemistry and Biochemistry University of Maryland College Park Maryland USA
| | - Jinwoo Lee
- Department of Chemistry and Biochemistry University of Maryland College Park Maryland USA
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8
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Louie AY, Tingling J, Dray E, Hussain J, McKim DB, Swanson KS, Steelman AJ. Dietary Cholesterol Causes Inflammatory Imbalance and Exacerbates Morbidity in Mice Infected with Influenza A Virus. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:2523-2539. [PMID: 35577367 DOI: 10.4049/jimmunol.2100927] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 03/21/2022] [Indexed: 12/27/2022]
Abstract
Influenza is a common cause of pneumonia-induced hospitalization and death, but how host factors function to influence disease susceptibility or severity has not been fully elucidated. Cellular cholesterol levels may affect the pathogenesis of influenza infection, as cholesterol is crucial for viral entry and replication, as well as immune cell proliferation and function. However, there is still conflicting evidence on the extent to which dietary cholesterol influences cholesterol metabolism. In this study, we examined the effects of a high-cholesterol diet in modulating the immune response to influenza A virus (IAV) infection in mice. Mice were fed a standard or a high-cholesterol diet for 5 wk before inoculation with mouse-adapted human IAV (Puerto Rico/8/1934), and tissues were collected at days 0, 4, 8, and 16 postinfection. Cholesterol-fed mice exhibited dyslipidemia characterized by increased levels of total serum cholesterol prior to infection and decreased triglycerides postinfection. Cholesterol-fed mice also displayed increased morbidity compared with control-fed mice, which was neither a result of immunosuppression nor changes in viral load. Instead, transcriptomic analysis of the lungs revealed that dietary cholesterol caused upregulation of genes involved in viral-response pathways and leukocyte trafficking, which coincided with increased numbers of cytokine-producing CD4+ and CD8+ T cells and infiltrating dendritic cells. Morbidity as determined by percent weight loss was highly correlated with numbers of cytokine-producing CD4+ and CD8+ T cells as well as granulocytes. Taken together, dietary cholesterol promoted IAV morbidity via exaggerated cellular immune responses that were independent of viral load.
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Affiliation(s)
- Allison Y Louie
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL
| | - Joseph Tingling
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL
| | - Evan Dray
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL
| | - Jamal Hussain
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL
| | - Daniel B McKim
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL.,Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL.,Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL; and
| | - Kelly S Swanson
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL.,Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL; and
| | - Andrew J Steelman
- Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, IL; .,Department of Animal Sciences, University of Illinois at Urbana-Champaign, Urbana, IL.,Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL; and.,Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL
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9
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Hwang J, Jung Y, Moon S, Yu S, Oh H, Kim S, Kim KW, Yoon JH, Chun J, Kim SJ, Chung WJ, Kweon DH. Nanodisc-Mediated Conversion of Virustatic Antiviral Antibody to Disrupt Virus Envelope in Infected Cells. SMALL METHODS 2022; 6:e2101516. [PMID: 35107214 DOI: 10.1002/smtd.202101516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Indexed: 06/14/2023]
Abstract
Many antibody-based antivirals, including broadly neutralizing antibodies (bnAbs) against various influenza virus strains, suffer from limited potency. A booster of the antiviral activity of an antibody is expected to facilitate development of antiviral therapeutics. In this study, a nanodisc (ND), a discoidal lipid bilayer encircled by membrane scaffold proteins, is engineered to provide virucidal properties to antibodies, thereby augmenting their antiviral activity. NDs carrying the Fc-binding peptide sequence form an antibody-ND complex (ANC), which can co-endocytose into cells infected with influenza virus. ANC efficiently inhibits endosome escape of viral RNA by dual complimentary mode of action. While the antibody moiety in an ANC inhibits hemagglutinin-mediated membrane fusion, its ND moiety destroys the viral envelope using free hemagglutinins that are not captured by antibodies. Providing virus-infected host cells with the ability to self-eliminate by the synergistic effect of ANC components dramatically amplifies the antiviral efficacy of a bnAb against influenza virus. When the efficacy of ANC is assessed in mouse models, administration of ANCs dramatically reduces morbidity and mortality compared to bnAb alone. This study is the first to demonstrate the novel nanoparticle ANC and its role in combating viral infections, suggesting that ANC is a versatile platform applicable to various viruses.
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Affiliation(s)
- Jaehyeon Hwang
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Younghun Jung
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Seokoh Moon
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Seokhyeon Yu
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Hyunseok Oh
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Soomin Kim
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Kyeong Won Kim
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jeong Hyeon Yoon
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jihwan Chun
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Sang Jick Kim
- Synthetic Biology and Bioengineering Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Korea
| | - Woo-Jae Chung
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Dae-Hyuk Kweon
- Department of Integrative Biotechnology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
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10
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Mittal A, Chauhan A. Aspects of Biological Replication and Evolution Independent of the Central Dogma: Insights from Protein-Free Vesicular Transformations and Protein-Mediated Membrane Remodeling. J Membr Biol 2022; 255:185-209. [PMID: 35333977 PMCID: PMC8951669 DOI: 10.1007/s00232-022-00230-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2022] [Accepted: 03/06/2022] [Indexed: 11/21/2022]
Abstract
Biological membrane remodeling is central to living systems. In spite of serving as “containers” of whole-living systems and functioning as dynamic compartments within living systems, biological membranes still find a “blue collar” treatment compared to the “white collar” nucleic acids and proteins in biology. This may be attributable to the fact that scientific literature on biological membrane remodeling is only 50 years old compared to ~ 150 years of literature on proteins and a little less than 100 years on nucleic acids. However, recently, evidence for symbiotic origins of eukaryotic cells from data only on biological membranes was reported. This, coupled with appreciation of reproducible amphiphilic self-assemblies in aqueous environments (mimicking replication), has already initiated discussions on origins of life beyond nucleic acids and proteins. This work presents a comprehensive compilation and meta-analyses of data on self-assembly and vesicular transformations in biological membranes—starting from model membranes to establishment of Influenza Hemagglutinin-mediated membrane fusion as a prototypical remodeling system to a thorough comparison between enveloped mammalian viruses and cellular vesicles. We show that viral membrane fusion proteins, in addition to obeying “stoichiometry-driven protein folding”, have tighter compositional constraints on their amino acid occurrences than general-structured proteins, regardless of type/class. From the perspective of vesicular assemblies and biological membrane remodeling (with and without proteins) we find that cellular vesicles are quite different from viruses. Finally, we propose that in addition to pre-existing thermodynamic frameworks, kinetic considerations in de novo formation of metastable membrane structures with available “third-party” constituents (including proteins) were not only crucial for origins of life but also continue to offer morphological replication and/or functional mechanisms in modern life forms, independent of the central dogma.
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Affiliation(s)
- Aditya Mittal
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi (IIT Delhi), Hauz Khas, New Delhi, 110016, India. .,Supercomputing Facility for Bioinformatics and Computational Biology (SCFBio), IIT Delhi, Hauz Khas, New Delhi, 110016, India.
| | - Akanksha Chauhan
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi (IIT Delhi), Hauz Khas, New Delhi, 110016, India
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11
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Pattnaik GP, Chakraborty H. Cholesterol: A key player in membrane fusion that modulates the efficacy of fusion inhibitor peptides. VITAMINS AND HORMONES 2021; 117:133-155. [PMID: 34420578 DOI: 10.1016/bs.vh.2021.06.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The interaction of cholesterol with the neighboring lipids modulates several physical properties of the membrane. Mostly, it affects membrane fluidity, membrane permeability, lateral diffusion of lipids, bilayer thickness, and water penetration into the lipid bilayer. Due to the smaller head group to hydrophobic cross-sectional area of the tail, cholesterol induces intrinsic negative curvature to the membrane. The interaction of cholesterol with sphingolipids forms lipid rafts; generates phase separation in the membrane. The cholesterol-dependent modifications of membrane physical properties modulate viral infections by affecting the fusion between viral and host cell membranes. Cholesterol demonstrates a strong impact on the structure, depth of penetration, conformation, and organization of fusion peptides in membrane milieu. Further, cholesterol has been implicated to modify the fusion inhibitory efficiency of peptide-based membrane fusion inhibitors.
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Affiliation(s)
| | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Burla, Odisha, India; Centre of Excellence in Natural Products and Therapeutics, Sambalpur University, Burla, Odisha, India.
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12
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4D analysis of malaria parasite invasion offers insights into erythrocyte membrane remodeling and parasitophorous vacuole formation. Nat Commun 2021; 12:3620. [PMID: 34131147 PMCID: PMC8206130 DOI: 10.1038/s41467-021-23626-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 04/30/2021] [Indexed: 12/15/2022] Open
Abstract
Host membrane remodeling is indispensable for viruses, bacteria, and parasites, to subvert the membrane barrier and obtain entry into cells. The malaria parasite Plasmodium spp. induces biophysical and molecular changes to the erythrocyte membrane through the ordered secretion of its apical organelles. To understand this process and address the debate regarding how the parasitophorous vacuole membrane (PVM) is formed, we developed an approach using lattice light-sheet microscopy, which enables the parasite interaction with the host cell membrane to be tracked and characterized during invasion. Our results show that the PVM is predominantly formed from the erythrocyte membrane, which undergoes biophysical changes as it is remodeled across all stages of invasion, from pre-invasion through to PVM sealing. This approach enables a functional interrogation of parasite-derived lipids and proteins in PVM biogenesis and echinocytosis during Plasmodium falciparum invasion and promises to yield mechanistic insights regarding how this is more generally orchestrated by other intracellular pathogens. Here, Geoghegan, Evelyn et al. provide a lattice light-sheet microscopy based 4D imaging pipeline to quantitatively investigate Plasmodium spp. invasion and show that the nascent parasitophorous vacuole is predominantly formed from host’s erythrocyte membrane and undergoes continuous remodeling throughout invasion.
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13
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Jain V, Shelby T, Patel T, Mekhedov E, Petersen JD, Zimmerberg J, Ranaweera A, Weliky DP, Dandawate P, Anant S, Sulthana S, Vasquez Y, Banerjee T, Santra S. A Bimodal Nanosensor for Probing Influenza Fusion Protein Activity Using Magnetic Relaxation. ACS Sens 2021; 6:1899-1909. [PMID: 33905237 DOI: 10.1021/acssensors.1c00253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Viral fusion is a critical step in the entry pathway of enveloped viruses and remains a viable target for antiviral exploration. The current approaches for studying fusion mechanisms include ensemble fusion assays, high-resolution cryo-TEM, and single-molecule fluorescence-based methods. While these methods have provided invaluable insights into the dynamic events underlying fusion processes, they come with their own limitations. These often include extensive data and image analysis in addition to experimental time and technical requirements. This work proposes the use of the spin-spin T2 relaxation technique as a sensitive bioanalytical method for the rapid quantification of interactions between viral fusion proteins and lipids in real time. In this study, new liposome-coated iron oxide nanosensors (LIONs), which mimic as magnetic-labeled host membranes, are reported to detect minute interactions occurring between the membrane and influenza's fusion glycoprotein, hemagglutinin (HA). The influenza fusion protein's interaction with the LION membrane is detected by measuring changes in the sensitive spin-spin T2 magnetic relaxation time using a bench-top NMR instrument. More data is gleaned from including the fluorescent dye DiI into the LION membrane. In addition, the effects of environmental factors on protein-lipid interaction that affect fusion such as pH, time of incubation, trypsin, and cholesterol were also examined. Furthermore, the efficacy and sensitivity of the spin-spin T2 relaxation assay in quantifying similar protein/lipid interactions with more native configurations of HA were demonstrated using virus-like particles (VLPs). Shorter domains derived from HA were used to start a reductionist path to identify the parts of HA responsible for the NMR changes observed. Finally, the known fusion inhibitor Arbidol was employed in our spin-spin T2 relaxation-based fusion assay to demonstrate the application of LIONs in real-time monitoring of this aspect of fusion for evaluation of potential fusion inhibitors.
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Affiliation(s)
- Vedant Jain
- Department of Chemistry, Pittsburg State University, Pittsburg, Kansas 66762, United States
| | - Tyler Shelby
- Department of Chemistry, Pittsburg State University, Pittsburg, Kansas 66762, United States
| | - Truptiben Patel
- Department of Chemistry, Pittsburg State University, Pittsburg, Kansas 66762, United States
| | - Elena Mekhedov
- Section on Integrative Biophysics, Division of Basic and Translational Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Jennifer D Petersen
- Section on Integrative Biophysics, Division of Basic and Translational Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Division of Basic and Translational Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Ahinsa Ranaweera
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - David P Weliky
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, United States
| | - Prasad Dandawate
- Department of Molecular and Integrative Physiology and Department of Surgery, The University of Kansas Medical Center, Kansas City, Kansas 66160, United States
| | - Shrikant Anant
- Department of Molecular and Integrative Physiology and Department of Surgery, The University of Kansas Medical Center, Kansas City, Kansas 66160, United States
| | - Shoukath Sulthana
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Yolanda Vasquez
- Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74078, United States
| | - Tuhina Banerjee
- Department of Chemistry, Pittsburg State University, Pittsburg, Kansas 66762, United States
| | - Santimukul Santra
- Department of Chemistry, Pittsburg State University, Pittsburg, Kansas 66762, United States
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14
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Pattnaik GP, Chakraborty H. Fusogenic Effect of Cholesterol Prevails over the Inhibitory Effect of a Peptide-Based Membrane Fusion Inhibitor. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3477-3489. [PMID: 33689373 DOI: 10.1021/acs.langmuir.1c00319] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Membrane fusion is the primary step in the entry of enveloped viruses into the host cell. Membrane composition modulates the membrane fusion by changing the organization dynamics of the fusion proteins, peptides, and membranes. The asymmetric lipid compositions of the viral envelope and the host cell influence the membrane fusion. Cholesterol is an important constituent of mammalian cells and plays a vital role in the entry of several viruses. In our pursuit of developing peptide-based general fusion inhibitors, we have previously shown that a coronin 1-derived peptide, TG-23, inhibited polyethylene glycol-induced fusion between symmetric membranes without cholesterol. In this work, we have studied the effect of TG-23 on the polyethylene glycol-mediated fusion between 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), and 1,2-dioleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DOPG) (60/30/10 mol %) and DOPC/DOPE/DOPG/CH (50/30/10/10 mol %) membranes and between DOPC/DOPE/DOPG (60/30/10 mol %) and DOPC/DOPE/DOPG/CH (40/30/10/20 mol %) membranes. Our results demonstrate that the TG-23 peptide inhibited the fusion between membranes containing 0 and 10 mol % cholesterol though the efficacy is less than that of symmetric fusion between membranes devoid of cholesterol, and the inhibitory efficacy becomes negligible in the fusion between membranes containing 0 and 20 mol % cholesterol. Several steady-state and time-resolved fluorescence spectroscopic techniques have been successfully utilized to evaluate the organization, dynamics, and membrane penetration of the TG-23 peptide. Taken together, our results demonstrate that the reduction of the inhibitory effect of TG-23 in asymmetric membrane fusion containing cholesterol of varying concentrations is not due to the altered peptide structure, organization, and dynamics, rather owing to the intrinsic negative curvature-inducing property of cholesterol. Therefore, the membrane composition is an added complexity in the journey of developing peptide-based membrane fusion inhibitors.
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Affiliation(s)
| | - Hirak Chakraborty
- School of Chemistry, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India
- Centre of Excellence in Natural Products and Therapeutics, Sambalpur University, Jyoti Vihar, Burla, Odisha 768 019, India
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15
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Roles of Cholesterol in Early and Late Steps of the Nipah Virus Membrane Fusion Cascade. J Virol 2021; 95:JVI.02323-20. [PMID: 33408170 DOI: 10.1128/jvi.02323-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 12/11/2020] [Indexed: 02/06/2023] Open
Abstract
Cholesterol has been implicated in various viral life cycle steps for different enveloped viruses, including viral entry into host cells, cell-cell fusion, and viral budding from infected cells. Enveloped viruses acquire their membranes from their host cells. Although cholesterol has been associated with the binding and entry of various enveloped viruses into cells, cholesterol's exact function in the viral-cell membrane fusion process remains largely elusive, particularly for the paramyxoviruses. Furthermore, paramyxoviral fusion occurs at the host cell membrane and is essential for both virus entry (virus-cell fusion) and syncytium formation (cell-cell fusion), central to viral pathogenicity. Nipah virus (NiV) is a deadly member of the Paramyxoviridae family, which also includes Hendra, measles, mumps, human parainfluenza, and various veterinary viruses. The zoonotic NiV causes severe encephalitis, vasculopathy, and respiratory symptoms, leading to a high mortality rate in humans. We used NiV as a model to study the role of membrane cholesterol in paramyxoviral membrane fusion. We used a combination of methyl-beta cyclodextrin (MβCD), lovastatin, and cholesterol to deplete or enrich cell membrane cholesterol outside cytotoxic concentrations. We found that the levels of cellular membrane cholesterol directly correlated with the levels of cell-cell fusion induced. These phenotypes were paralleled using NiV/vesicular stomatitis virus (VSV)-pseudotyped viral infection assays. Remarkably, our mechanistic studies revealed that cholesterol reduces an early F-triggering step but enhances a late fusion pore formation step in the NiV membrane fusion cascade. Thus, our results expand our mechanistic understanding of the paramyxoviral/henipaviral entry and cell-cell fusion processes.IMPORTANCE Cholesterol has been implicated in various steps of the viral life cycle for different enveloped viruses. Nipah virus (NiV) is a highly pathogenic enveloped virus in the Henipavirus genus within the Paramyxoviridae family, capable of causing a high mortality rate in humans and high morbidity in domestic and agriculturally important animals. The role of cholesterol for NiV or the henipaviruses is unknown. Here, we show that the levels of cholesterol influence the levels of NiV-induced cell-cell membrane fusion during syncytium formation and virus-cell membrane fusion during viral entry. Furthermore, the specific role of cholesterol in membrane fusion is not well defined for the paramyxoviruses. We show that the levels of cholesterol affect an early F-triggering step and a late fusion pore formation step during the membrane fusion cascade. Thus, our results expand our mechanistic understanding of the viral entry and cell-cell fusion processes, which may aid the development of antivirals.
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16
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Lee J, Kreutzberger AJB, Odongo L, Nelson EA, Nyenhuis DA, Kiessling V, Liang B, Cafiso DS, White JM, Tamm LK. Ebola virus glycoprotein interacts with cholesterol to enhance membrane fusion and cell entry. Nat Struct Mol Biol 2021; 28:181-189. [PMID: 33462517 PMCID: PMC7992113 DOI: 10.1038/s41594-020-00548-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 12/07/2020] [Indexed: 12/14/2022]
Abstract
Cholesterol serves critical roles in enveloped virus fusion by modulating membrane properties. The glycoprotein (GP) of Ebola virus (EBOV) promotes fusion in the endosome, a process that requires the endosomal cholesterol transporter NPC1. However, the role of cholesterol in EBOV fusion is unclear. Here we show that cholesterol in GP-containing membranes enhances fusion and the membrane-proximal external region and transmembrane (MPER/TM) domain of GP interacts with cholesterol via several glycine residues in the GP2 TM domain, notably G660. Compared to wild-type (WT) counterparts, a G660L mutation caused a more open angle between MPER and TM domains in an MPER/TM construct, higher probability of stalling at hemifusion for GP2 proteoliposomes and lower cell entry of virus-like particles (VLPs). VLPs with depleted cholesterol show reduced cell entry, and VLPs produced under cholesterol-lowering statin conditions show less frequent entry than respective controls. We propose that cholesterol-TM interactions affect structural features of GP2, thereby facilitating fusion and cell entry.
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Affiliation(s)
- Jinwoo Lee
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA
| | - Alex J B Kreutzberger
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Laura Odongo
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Elizabeth A Nelson
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - David A Nyenhuis
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Volker Kiessling
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - Binyong Liang
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA
| | - David S Cafiso
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Chemistry, University of Virginia, Charlottesville, VA, USA
| | - Judith M White
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA
- Department of Cell Biology, University of Virginia, Charlottesville, VA, USA
| | - Lukas K Tamm
- Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, VA, USA.
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA, USA.
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17
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Balgoma D, Gil-de-Gómez L, Montero O. Lipidomics Issues on Human Positive ssRNA Virus Infection: An Update. Metabolites 2020; 10:E356. [PMID: 32878290 PMCID: PMC7569815 DOI: 10.3390/metabo10090356] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 08/24/2020] [Accepted: 08/27/2020] [Indexed: 12/29/2022] Open
Abstract
The pathogenic mechanisms underlying the Biology and Biochemistry of viral infections are known to depend on the lipid metabolism of infected cells. From a lipidomics viewpoint, there are a variety of mechanisms involving virus infection that encompass virus entry, the disturbance of host cell lipid metabolism, and the role played by diverse lipids in regard to the infection effectiveness. All these aspects have currently been tackled separately as independent issues and focused on the function of proteins. Here, we review the role of cholesterol and other lipids in ssRNA+ infection.
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Affiliation(s)
- David Balgoma
- Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Husarg. 3, 75123 Uppsala, Sweden;
| | - Luis Gil-de-Gómez
- Center of Childhood Cancer Center, Children’s Hospital of Philadelphia, Colket Translational Research Center, 3501 Civic Center Blvd, Philadelphia, PA 19104, USA;
| | - Olimpio Montero
- Spanish National Research Council (CSIC), Boecillo’s Technological Park Bureau, Av. Francisco Vallés 8, 47151 Boecillo, Spain
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18
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Bukrinsky MI, Mukhamedova N, Sviridov D. Lipid rafts and pathogens: the art of deception and exploitation. J Lipid Res 2020; 61:601-610. [PMID: 31615838 PMCID: PMC7193957 DOI: 10.1194/jlr.tr119000391] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 10/07/2019] [Indexed: 02/06/2023] Open
Abstract
Lipid rafts, solid regions of the plasma membrane enriched in cholesterol and glycosphingolipids, are essential parts of a cell. Functionally, lipid rafts present a platform that facilitates interaction of cells with the outside world. However, the unique properties of lipid rafts required to fulfill this function at the same time make them susceptible to exploitation by pathogens. Many steps of pathogen interaction with host cells, and sometimes all steps within the entire lifecycle of various pathogens, rely on host lipid rafts. Such steps as binding of pathogens to the host cells, invasion of intracellular parasites into the cell, the intracellular dwelling of parasites, microbial assembly and exit from the host cell, and microbe transfer from one cell to another all involve lipid rafts. Interaction also includes modification of lipid rafts in host cells, inflicted by pathogens from both inside and outside the cell, through contact or remotely, to advance pathogen replication, to utilize cellular resources, and/or to mitigate immune response. Here, we provide a systematic overview of how and why pathogens interact with and exploit host lipid rafts, as well as the consequences of this interaction for the host, locally and systemically, and for the microbe. We also raise the possibility of modulation of lipid rafts as a therapeutic approach against a variety of infectious agents.
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Affiliation(s)
- Michael I Bukrinsky
- Department of Microbiology, Immunology, and Tropical Medicine,George Washington University School of Medicine and Health Science, Washington, DC 20037
| | | | - Dmitri Sviridov
- Baker Heart and Diabetes Institute, Melbourne 3004, Australia. mailto:
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Benhaim MA, Lee KK. New Biophysical Approaches Reveal the Dynamics and Mechanics of Type I Viral Fusion Machinery and Their Interplay with Membranes. Viruses 2020; 12:E413. [PMID: 32276357 PMCID: PMC7232462 DOI: 10.3390/v12040413] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 04/04/2020] [Accepted: 04/04/2020] [Indexed: 12/27/2022] Open
Abstract
Protein-mediated membrane fusion is a highly regulated biological process essential for cellular and organismal functions and infection by enveloped viruses. During viral entry the membrane fusion reaction is catalyzed by specialized protein machinery on the viral surface. These viral fusion proteins undergo a series of dramatic structural changes during membrane fusion where they engage, remodel, and ultimately fuse with the host membrane. The structural and dynamic nature of these conformational changes and their impact on the membranes have long-eluded characterization. Recent advances in structural and biophysical methodologies have enabled researchers to directly observe viral fusion proteins as they carry out their functions during membrane fusion. Here we review the structure and function of type I viral fusion proteins and mechanisms of protein-mediated membrane fusion. We highlight how recent technological advances and new biophysical approaches are providing unprecedented new insight into the membrane fusion reaction.
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Affiliation(s)
- Mark A. Benhaim
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195-7610, USA;
| | - Kelly K. Lee
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195-7610, USA;
- Biological Physics Structure and Design Program, University of Washington, Seattle, WA 98195-7610, USA
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20
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Amphipathic Helices of Cellular Proteins Can Replace the Helix in M2 of Influenza A Virus with Only Small Effects on Virus Replication. J Virol 2020; 94:JVI.01605-19. [PMID: 31694941 DOI: 10.1128/jvi.01605-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 11/04/2019] [Indexed: 11/20/2022] Open
Abstract
M2 of influenza virus functions as a proton channel during virus entry. In addition, an amphipathic helix in its cytoplasmic tail plays a role during budding. It targets M2 to the assembly site where it inserts into the inner membrane leaflet to induce curvature that causes virus scission. Since vesicularization of membranes can be performed by a variety of amphiphilic peptides, we used reverse genetics to investigate whether the peptides can substitute for M2's helix. Virus could not be generated if M2's helix was deleted or replaced by a peptide predicted not to form an amphiphilic helix. In contrast, viruses could be rescued if the M2 helix was exchanged by helices known to induce membrane curvature. Infectious virus titers were marginally reduced if M2 contains the helix of the amphipathic lipid packing sensor from the Epsin N-terminal homology domain or the nonnatural membrane inducer RW16. Transmission electron microscopy of infected cells did not reveal unequivocal evidence that virus budding or membrane scission was disturbed in any of the mutants. Instead, individual virus mutants exhibit other defects in M2, such as reduced surface expression, incorporation into virus particles, and ion channel activity. The protein composition and specific infectivity were also altered for mutant virions. We conclude that the presence of an amphiphilic helix in M2 is essential for virus replication but that other helices can replace its basic (curvature-inducing) function.IMPORTANCE Influenza virus is unique among enveloped viruses since it does not rely on the cellular ESCRT machinery for budding. Instead, viruses encode their own scission machine, the M2 protein. M2 is targeted to the edge of the viral assembly site, where it inserts an amphiphilic helix into the membrane to induce curvature. Cellular proteins utilize a similar mechanism for scission of vesicles. We show that the helix of M2 can be replaced by helices from cellular proteins with only small effects on virus replication. No evidence was obtained that budding is disturbed, but individual mutants exhibit other defects in M2 that explain the reduced virus titers. In contrast, no virus could be generated if the helix of M2 is deleted or replaced by irrelevant sequences. These experiments support the concept that M2 requires an amphiphilic helix to induce membrane curvature, but its biophysical properties are more important than the amino acid sequence.
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Cholesterol Binding to the Transmembrane Region of a Group 2 Hemagglutinin (HA) of Influenza Virus Is Essential for Virus Replication, Affecting both Virus Assembly and HA Fusion Activity. J Virol 2019; 93:JVI.00555-19. [PMID: 31118253 DOI: 10.1128/jvi.00555-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 05/14/2019] [Indexed: 12/21/2022] Open
Abstract
Hemagglutinin (HA) of influenza virus is incorporated into cholesterol-enriched nanodomains of the plasma membrane. Phylogenetic group 2 HAs contain the conserved cholesterol consensus motif (CCM) YKLW in the transmembrane region. We previously reported that mutations in the CCM retarded intracellular transport of HA and decreased its nanodomain association. Here, we analyzed whether cholesterol interacts with the CCM. Incorporation of photocholesterol into HA was significantly reduced if the whole CCM is replaced by alanine, both using immunoprecipitated HA and when HA is embedded in the membrane. We next used reverse genetics to investigate the significance of the CCM for virus replication. No virus was rescued if the whole motif is exchanged (YKLW4A); singly (LA) or doubly (YK2A and LW2A) mutated virus showed decreased titers and a comparative fitness disadvantage. In polarized cells, transport of HA mutants to the apical membrane was not disturbed. Reduced amounts of HA and cholesterol were incorporated into the viral membrane. Mutant viruses exhibit a decrease in hemolysis, which is only partially corrected if the membrane is replenished with cholesterol. More specifically, viruses have a defect in hemifusion, as demonstrated by fluorescence dequenching. Cells expressing HA YKLW4A fuse with erythrocytes, but the number of events is reduced. Even after acidification unfused erythrocytes remain cell bound, a phenomenon not observed with wild-type HA. We conclude that cholesterol binding to a group 2 HA is essential for virus replication. It has pleiotropic effects on virus assembly and membrane fusion, mainly on lipid mixing and possibly a preceding step.IMPORTANCE The glycoprotein HA is a major pathogenicity factor of influenza viruses. Whereas the structure and function of HA's ectodomain is known in great detail, similar data for the membrane-anchoring part of the protein are missing. Here, we demonstrate that the transmembrane region of a group 2 HA interacts with cholesterol, the major lipid of the plasma membrane and the defining element of the viral budding site nanodomains of the plasma membrane. The cholesterol binding motif is essential for virus replication. Its partial removal affects various steps of the viral life cycle, such as assembly of new virus particles and their subsequent cell entry via membrane fusion. A cholesterol binding pocket in group 2 HAs might be a promising target for a small lipophilic drug that inactivates the virus.
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22
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Kong B, Moon S, Kim Y, Heo P, Jung Y, Yu SH, Chung J, Ban C, Kim YH, Kim P, Hwang BJ, Chung WJ, Shin YK, Seong BL, Kweon DH. Virucidal nano-perforator of viral membrane trapping viral RNAs in the endosome. Nat Commun 2019; 10:185. [PMID: 30643128 PMCID: PMC6331592 DOI: 10.1038/s41467-018-08138-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 12/18/2018] [Indexed: 11/09/2022] Open
Abstract
Membrane-disrupting agents that selectively target virus versus host membranes could potentially inhibit a broad-spectrum of enveloped viruses, but currently such antivirals are lacking. Here, we develop a nanodisc incorporated with a decoy virus receptor that inhibits virus infection. Mechanistically, nanodiscs carrying the viral receptor sialic acid bind to influenza virions and are co-endocytosed into host cells. At low pH in the endosome, the nanodiscs rupture the viral envelope, trapping viral RNAs inside the endolysosome for enzymatic decomposition. In contrast, liposomes containing a decoy receptor show weak antiviral activity due to the lack of membrane disruption. The nanodiscs inhibit influenza virus infection and reduce morbidity and mortality in a mouse model. Our results suggest a new class of antivirals applicable to other enveloped viruses that cause irreversible physical damage specifically to virus envelope by viruses' own fusion machine. In conclusion, the lipid nanostructure provides another dimension for antiviral activity of decoy molecules.
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Affiliation(s)
- Byoungjae Kong
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Seokoh Moon
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Yuna Kim
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Paul Heo
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Younghun Jung
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Seok-Hyeon Yu
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Jinhyo Chung
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Choongjin Ban
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Yong Ho Kim
- Biomedical Institute for Convergence, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Paul Kim
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
| | - Beom Jeung Hwang
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
| | - Woo-Jae Chung
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Yeon-Kyun Shin
- Department of Biochemistry Biophysics and Molecular Biology, Iowa State University, Iowa, IA, 50011, USA
| | - Baik Lin Seong
- Department of Biotechnology, College of Life Science and Biotechnology, Yonsei University, Seoul, 03722, Republic of Korea
| | - Dae-Hyuk Kweon
- Department of Integrative Biotechnology, College of Biotechnology and Bioengineering, Sungkyunkwan University, Suwon, 16419, Republic of Korea. .,Biomedical Institute for Convergence, Sungkyunkwan University, Suwon, 16419, Republic of Korea.
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23
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Falanga A, Galdiero M, Morelli G, Galdiero S. Membranotropic peptides mediating viral entry. Pept Sci (Hoboken) 2018; 110:e24040. [PMID: 32328541 PMCID: PMC7167733 DOI: 10.1002/pep2.24040] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 11/27/2017] [Accepted: 12/20/2017] [Indexed: 02/06/2023]
Abstract
The means used by enveloped viruses to bypass cellular membranes are well characterized; however, the mechanisms used by non-enveloped viruses to deliver their genome inside the cell remain unresolved and poorly defined. The discovery of short, membrane interacting, amphipathic or hydrophobic sequences (known as membranotropic peptides) in both enveloped and non-enveloped viruses suggests that these small peptides are strongly involved in breaching the host membrane and in the delivery of the viral genome into the host cell. Thus, in spite of noticeable differences in entry, this short stretches of membranotropic peptides are probably associated with similar entry-related events. This review will uncover the intrinsic features of viral membranotropic peptides involved in viral entry of both naked viruses and the ones encircled with a biological membrane with the objective to better elucidate their different functional properties and possible applications in the biomedical field.
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Affiliation(s)
- Annarita Falanga
- Department of Pharmacy, School of MedicineNaples80134Italy
- CIRPEB University of Naples Federico II, Via Mezzocannone 16Naples80134Italy
| | - Massimiliano Galdiero
- CIRPEB University of Naples Federico II, Via Mezzocannone 16Naples80134Italy
- Department of Experimental MedicineUniversity of Campania “Luigi Vanvitelli,” Via de CrecchioNaples80134Italy
| | - Giancarlo Morelli
- Department of Pharmacy, School of MedicineNaples80134Italy
- CIRPEB University of Naples Federico II, Via Mezzocannone 16Naples80134Italy
| | - Stefania Galdiero
- Department of Pharmacy, School of MedicineNaples80134Italy
- CIRPEB University of Naples Federico II, Via Mezzocannone 16Naples80134Italy
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24
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van der Borg G, Braddock S, Blijleven JS, van Oijen AM, Roos WH. Single-particle fusion of influenza viruses reveals complex interactions with target membranes. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:204005. [PMID: 29623903 PMCID: PMC7104739 DOI: 10.1088/1361-648x/aabc21] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Revised: 03/27/2018] [Accepted: 04/06/2018] [Indexed: 05/03/2023]
Abstract
The first step in infection of influenza A virus is contact with the host cell membrane, with which it later fuses. The composition of the target bilayer exerts a complex influence on both fusion efficiency and time. Here, an in vitro, single-particle approach is used to study this effect. Using total internal reflection fluorescence (TIRF) microscopy and a microfluidic flow cell, the hemifusion of single virions is visualized. Hemifusion efficiency and kinetics are studied while altering target bilayer cholesterol content and sialic-acid donor. Cholesterol ratios tested were 0%, 10%, 20%, and 40%. Sialic-acid donors GD1a and GYPA were used. Both cholesterol ratio and sialic-acid donors proved to have a significant effect on hemifusion efficiency. Furthermore, comparison between GD1a and GYPA conditions shows that the cholesterol dependence of the hemifusion time is severely affected by the sialic-acid donor. Only GD1a shows a clear increasing trend in hemifusion efficiency and time with increasing cholesterol concentration of the target bilayer with maximum rates for GD1A and 40% cholesterol. Overall our results show that sialic acid donor and target bilayer composition should be carefully chosen, depending on the desired hemifusion time and efficiency in the experiment.
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Affiliation(s)
- Guus van der Borg
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Netherlands
| | - Scarlett Braddock
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Netherlands
| | - Jelle S Blijleven
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Netherlands
| | | | - Wouter H Roos
- Moleculaire Biofysica, Zernike Instituut, Rijksuniversiteit Groningen, Netherlands
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25
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Fathali H, Cans AS. Amperometry methods for monitoring vesicular quantal size and regulation of exocytosis release. Pflugers Arch 2017; 470:125-134. [PMID: 28951968 PMCID: PMC5748430 DOI: 10.1007/s00424-017-2069-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Revised: 09/12/2017] [Accepted: 09/14/2017] [Indexed: 11/30/2022]
Abstract
Chemical signaling strength during intercellular communication can be regulated by secretory cells through controlling the amount of signaling molecules that are released from a secretory vesicle during the exocytosis process. In addition, the chemical signal can also be influenced by the amount of neurotransmitters that is accumulated and stored inside the secretory vesicle compartment. Here, we present the development of analytical methodologies and cell model systems that have been applied in neuroscience research for gaining better insights into the biophysics and the molecular mechanisms, which are involved in the regulatory aspects of the exocytosis machinery affecting the output signal of chemical transmission at neuronal and neuroendocrine cells.
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Affiliation(s)
- Hoda Fathali
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 42196, Gothenburg, Sweden
| | - Ann-Sofie Cans
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 42196, Gothenburg, Sweden.
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26
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Sorkin R, Kampf N, Klein J. Effect of Cholesterol on the Stability and Lubrication Efficiency of Phosphatidylcholine Surface Layers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:7459-7467. [PMID: 28666386 DOI: 10.1021/acs.langmuir.7b01521] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The lubrication properties of saturated PC lipid vesicles containing high cholesterol content under high loads were examined by detailed surface force balance measurements of normal and shear forces between two surface-attached lipid layers. Forces between two opposing mica surfaces bearing distearoylphosphatidylcholine (PC) (DSPC) small unilamellar vesicles (SUVs, or liposomes), or bilayers, with varying cholesterol content were measured across water, whereas dimyristoyl PC (DMPC), dipalmitoyl PC (DPPC), and DSPC SUVs containing 40% cholesterol were measured across liposome dispersions of SUVs of the same lipid composition as in the adsorbed layers. The results clearly demonstrate decreased stability and resistance to normal load with the increase in cholesterol content of DSPC SUVs. Friction coefficients between two 10% cholesterol PC-bilayers were in the same range as for 40% cholesterol bilayers (μ ≈ 10-3), indicating that cholesterol has a more substantial effect on the mechanical properties of a bilayer than on its lubrication performance. We further find that the lubrication efficiency of DMPC and DPPC with 40% cholesterol is superior to that of DSPC 40% cholesterol, most likely because of enhanced hydration-lubrication in these systems. We previously found that when experiments are performed in the presence of a lipid reservoir, layers can self-heal and therefore their robustness is less important under such conditions. We conclude that the effect of cholesterol in decreasing the stability is more pronounced than its effect on hydration, but the stability is, in turn, less important when a lipid reservoir is present. This study complements our previous work and sheds light on the effect of cholesterol, a prominent and important physiological lipid, on the mechanical and lubrication properties of gel-phase lipid layers.
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Affiliation(s)
- Raya Sorkin
- Materials and Interfaces Department, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Nir Kampf
- Materials and Interfaces Department, Weizmann Institute of Science , Rehovot 76100, Israel
| | - Jacob Klein
- Materials and Interfaces Department, Weizmann Institute of Science , Rehovot 76100, Israel
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27
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Cholesterol Increases the Openness of SNARE-Mediated Flickering Fusion Pores. Biophys J 2016; 110:1538-1550. [PMID: 27074679 DOI: 10.1016/j.bpj.2016.02.019] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 11/22/2022] Open
Abstract
Flickering of fusion pores during exocytotic release of hormones and neurotransmitters is well documented, but without assays that use biochemically defined components and measure single-pore dynamics, the mechanisms remain poorly understood. We used total internal reflection fluorescence microscopy to quantify fusion-pore dynamics in vitro and to separate the roles of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) proteins and lipid bilayer properties. When small unilamellar vesicles bearing neuronal v-SNAREs fused with planar bilayers reconstituted with cognate t-SNARES, lipid and soluble cargo transfer rates were severely reduced, suggesting that pores flickered. From the lipid release times we computed pore openness, the fraction of time the pore is open, which increased dramatically with cholesterol. For most lipid compositions tested, SNARE-mediated and nonspecifically nucleated pores had similar openness, suggesting that pore flickering was controlled by lipid bilayer properties. However, with physiological cholesterol levels, SNAREs substantially increased the fraction of fully open pores and fusion was so accelerated that there was insufficient time to recruit t-SNAREs to the fusion site, consistent with t-SNAREs being preclustered by cholesterol into functional docking and fusion platforms. Our results suggest that cholesterol opens pores directly by reducing the fusion-pore bending energy, and indirectly by concentrating several SNAREs into individual fusion events.
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28
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Lee JH, Hsieh CF, Liu HW, Chen CY, Wu SC, Chen TW, Hsu CS, Liao YH, Yang CY, Shyu JF, Fischer WB, Lin CH. Lipid raft-associated stomatin enhances cell fusion. FASEB J 2016; 31:47-59. [PMID: 27663861 DOI: 10.1096/fj.201600643r] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Accepted: 09/07/2016] [Indexed: 01/25/2023]
Abstract
Membrane fusions that occur during vesicle transport, virus infection, and tissue development, involve receptors that mediate membrane contact and initiate fusion and effectors that execute membrane reorganization and fusion pore formation. Some of these fusogenic receptors/effectors are preferentially recruited to lipid raft membrane microdomains. Therefore, major constituents of lipid rafts, such as stomatin, may be involved in the regulation of cell-cell fusion. Stomatin produced in cells can be released to the extracellular environment, either through protein refolding to pass across lipid bilayer or through exosome trafficking. We report that cells expressing more stomatin or exposed to exogenous stomatin are more prone to undergoing cell fusion. During osteoclastogenesis, depletion of stomatin inhibited cell fusion but had little effect on tartrate-resistant acid phosphatase production. Moreover, in stomatin transgenic mice, increased cell fusion leading to enhanced bone resorption and subsequent osteoporosis were observed. With its unique molecular topology, stomatin forms molecular assembly within lipid rafts or on the appositional plasma membranes, and promotes membrane fusion by modulating fusogenic protein engagement.-Lee, J.-H., Hsieh, C.-F., Liu, H.-W., Chen, C.-Y., Wu, S.-C., Chen, T.-W., Hsu, C.-S., Liao, Y.-H., Yang, C.-Y., Shyu, J.-F., Fischer, W. B., Lin, C.-H. Lipid raft-associated stomatin enhances cell fusion.
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Affiliation(s)
- Jui-Hao Lee
- Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan.,Institute of Microbiology and Immunology.,Institute of Biochemistry and Molecular Biology
| | | | - Hong-Wen Liu
- Institute of Microbiology and Immunology.,Chong Hin Loon Memorial Cancer and Biotherapy Research Center, and
| | - Chin-Yau Chen
- Institute of Microbiology and Immunology.,Department of Surgery, I-Lan, Taiwan
| | - Shao-Chin Wu
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Tung-Wei Chen
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | | | - Yu-Hsiu Liao
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Chih-Yung Yang
- Department of Education and Research, Taipei City Hospital, Taipei, Taiwan; and
| | - Jia-Fwu Shyu
- Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan
| | - Wolfgang B Fischer
- Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
| | - Chi-Hung Lin
- Taiwan International Graduate Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan; .,Institute of Microbiology and Immunology.,Institute of Biophotonics, National Yang-Ming University, Taipei, Taiwan
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29
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Najafinobar N, Mellander LJ, Kurczy ME, Dunevall J, Angerer TB, Fletcher JS, Cans AS. Cholesterol Alters the Dynamics of Release in Protein Independent Cell Models for Exocytosis. Sci Rep 2016; 6:33702. [PMID: 27650365 PMCID: PMC5030643 DOI: 10.1038/srep33702] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/01/2016] [Indexed: 11/25/2022] Open
Abstract
Neurons communicate via an essential process called exocytosis. Cholesterol, an abundant lipid in both secretory vesicles and cell plasma membrane can affect this process. In this study, amperometric recordings of vesicular dopamine release from two different artificial cell models created from a giant unilamellar liposome and a bleb cell plasma membrane, show that with higher membrane cholesterol the kinetics for vesicular release are decelerated in a concentration dependent manner. This reduction in exocytotic speed was consistent for two observed modes of exocytosis, full and partial release. Partial release events, which only occurred in the bleb cell model due to the higher tension in the system, exhibited amperometric spikes with three distinct shapes. In addition to the classic transient, some spikes displayed a current ramp or plateau following the maximum peak current. These post spike features represent neurotransmitter release from a dilated pore before constriction and show that enhancing membrane rigidity via cholesterol adds resistance to a dilated pore to re-close. This implies that the cholesterol dependent biophysical properties of the membrane directly affect the exocytosis kinetics and that membrane tension along with membrane rigidity can influence the fusion pore dynamics and stabilization which is central to regulation of neurochemical release.
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Affiliation(s)
- Neda Najafinobar
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Lisa J. Mellander
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | - Michael E. Kurczy
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Johan Dunevall
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Tina B. Angerer
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96 Gothenburg, Sweden
| | - John S. Fletcher
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Ann-Sofie Cans
- Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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30
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Domanska MK, Dunning RA, Dryden KA, Zawada KE, Yeager M, Kasson PM. Hemagglutinin Spatial Distribution Shifts in Response to Cholesterol in the Influenza Viral Envelope. Biophys J 2016; 109:1917-24. [PMID: 26536268 DOI: 10.1016/j.bpj.2015.09.014] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 08/29/2015] [Accepted: 09/18/2015] [Indexed: 12/18/2022] Open
Abstract
Influenza virus delivers its genome to the host cytoplasm via a process of membrane fusion mediated by the viral hemagglutinin protein. Optimal fusion likely requires multiple hemagglutinin trimers, so the spatial distribution of hemagglutinin on the viral envelope may influence fusion mechanism. We have previously shown that moderate depletion of cholesterol from the influenza viral envelope accelerates fusion kinetics even though it decreases fusion efficiency, both in a reversible manner. Here, we use electron cryo-microscopy to measure how the hemagglutinin lateral density in the viral envelope changes with cholesterol extraction. We extract this information by measuring the radial distribution function of electron density in >4000 viral images per sample, assigning hemagglutinin density by comparing images with and without anti-HA Fab bound. On average, hemagglutinin trimers move closer together: we estimate that the typical trimer-trimer spacing reduces from 94 to 84 Å when ∼90% of cholesterol is removed from the viral membrane. Upon restoration of viral envelope cholesterol, this spacing once again expands. This finding can qualitatively explain the observed changes to fusion kinetics: contemporary models from single-virus microscopy are that fusion requires the engagement of several hemagglutinin trimers in close proximity. If removing cholesterol increases the lateral density of hemagglutinin, this should result in an increase in the rate of fusion.
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Affiliation(s)
- Marta K Domanska
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Rebecca A Dunning
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Kelly A Dryden
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Katarzyna E Zawada
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Mark Yeager
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia
| | - Peter M Kasson
- Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia.
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31
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Influenza viral membrane fusion is sensitive to sterol concentration but surprisingly robust to sterol chemical identity. Sci Rep 2016; 6:29842. [PMID: 27431907 PMCID: PMC4949436 DOI: 10.1038/srep29842] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 06/24/2016] [Indexed: 12/20/2022] Open
Abstract
Influenza virions are enriched in cholesterol relative to the plasma membrane from which they bud. Previous work has shown that fusion between influenza virus and synthetic liposomes is sensitive to the amount of cholesterol in either the virus or the target membrane. Here, we test the chemical properties of cholesterol required to promote influenza fusion by replacing cholesterol with other sterols and assaying viral fusion kinetics. We find that influenza fusion with liposomes is surprisingly robust to sterol chemical identity, showing no significant dependence on sterol identity in target membranes for any of the sterols tested. In the viral membrane, lanosterol slowed fusion somewhat, while polar sterols produced a more pronounced slowing and inhibition of fusion. No other sterols tested showed a significant perturbation in fusion rates, including ones previously shown to alter membrane bending moduli or phase behavior. Although fusion rates depend on viral cholesterol, they thus do not require cholesterol’s ability to support liquid-liquid phase coexistence. Using electron cryo-microscopy, we further find that sterol-dependent changes to hemagglutinin spatial patterning in the viral membrane do not require liquid-liquid phase coexistence. We therefore speculate that local sterol-hemagglutinin interactions in the viral envelope may control the rate-limiting step of fusion.
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32
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Visualization and Sequencing of Membrane Remodeling Leading to Influenza Virus Fusion. J Virol 2016; 90:6948-6962. [PMID: 27226364 DOI: 10.1128/jvi.00240-16] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Accepted: 05/14/2016] [Indexed: 12/31/2022] Open
Abstract
UNLABELLED Protein-mediated membrane fusion is an essential step in many fundamental biological events, including enveloped virus infection. The nature of protein and membrane intermediates and the sequence of membrane remodeling during these essential processes remain poorly understood. Here we used cryo-electron tomography (cryo-ET) to image the interplay between influenza virus and vesicles with a range of lipid compositions. By following the population kinetics of membrane fusion intermediates imaged by cryo-ET, we found that membrane remodeling commenced with the hemagglutinin fusion protein spikes grappling onto the target membrane, followed by localized target membrane dimpling as local clusters of hemagglutinin started to undergo conformational refolding. The local dimples then transitioned to extended, tightly apposed contact zones where the two proximal membrane leaflets were in most cases indistinguishable from each other, suggesting significant dehydration and possible intermingling of the lipid head groups. Increasing the content of fusion-enhancing cholesterol or bis-monoacylglycerophosphate in the target membrane led to an increase in extended contact zone formation. Interestingly, hemifused intermediates were found to be extremely rare in the influenza virus fusion system studied here, most likely reflecting the instability of this state and its rapid conversion to postfusion complexes, which increased in population over time. By tracking the populations of fusion complexes over time, the architecture and sequence of membrane reorganization leading to efficient enveloped virus fusion were thus resolved. IMPORTANCE Enveloped viruses employ specialized surface proteins to mediate fusion of cellular and viral membranes that results in the formation of pores through which the viral genetic material is delivered to the cell. For influenza virus, the trimeric hemagglutinin (HA) glycoprotein spike mediates host cell attachment and membrane fusion. While structures of a subset of conformations and parts of the fusion machinery have been characterized, the nature and sequence of membrane deformations during fusion have largely eluded characterization. Building upon studies that focused on early stages of HA-mediated membrane remodeling, here cryo-electron tomography (cryo-ET) was used to image the three-dimensional organization of intact influenza virions at different stages of fusion with liposomes, leading all the way to completion of the fusion reaction. By monitoring the evolution of fusion intermediate populations over the course of acid-induced fusion, we identified the progression of membrane reorganization that leads to efficient fusion by an enveloped virus.
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33
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The role of cholesterol in membrane fusion. Chem Phys Lipids 2016; 199:136-143. [PMID: 27179407 DOI: 10.1016/j.chemphyslip.2016.05.003] [Citation(s) in RCA: 235] [Impact Index Per Article: 29.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/07/2016] [Accepted: 05/10/2016] [Indexed: 12/21/2022]
Abstract
Cholesterol modulates the bilayer structure of biological membranes in multiple ways. It changes the fluidity, thickness, compressibility, water penetration and intrinsic curvature of lipid bilayers. In multi-component lipid mixtures, cholesterol induces phase separations, partitions selectively between different coexisting lipid phases, and causes integral membrane proteins to respond by changing conformation or redistribution in the membrane. But, which of these often overlapping properties are important for membrane fusion?-Here we review a range of recent experiments that elucidate the multiple roles that cholesterol plays in SNARE-mediated and viral envelope glycoprotein-mediated membrane fusion.
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34
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Chlanda P, Zimmerberg J. Protein-lipid interactions critical to replication of the influenza A virus. FEBS Lett 2016; 590:1940-54. [PMID: 26921878 DOI: 10.1002/1873-3468.12118] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/08/2016] [Accepted: 02/21/2016] [Indexed: 12/12/2022]
Abstract
Influenza A virus (IAV) assembles on the plasma membrane where viral proteins localize to form a bud encompassing the viral genome, which ultimately pinches off to give rise to newly formed infectious virions. Upon entry, the virus faces the opposite task-fusion with the endosomal membrane and disassembly to deliver the viral genome to the cytoplasm. There are at least four influenza proteins-hemagglutinin (HA), neuraminidase (NA), matrix 1 protein (M1), and the M2 ion channel-that are known to directly interact with the cellular membrane and modify membrane curvature in order to both assemble and disassemble membrane-enveloped virions. Here, we summarize and discuss current knowledge of the interactions of lipids and membrane proteins involved in the IAV replication cycle.
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Affiliation(s)
- Petr Chlanda
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Joshua Zimmerberg
- Section on Integrative Biophysics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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35
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Smrt ST, Lorieau JL. Membrane Fusion and Infection of the Influenza Hemagglutinin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 966:37-54. [PMID: 27966108 DOI: 10.1007/5584_2016_174] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
The influenza virus is a major health concern associated with an estimated 5000 to 30,000 deaths every year (Reed et al. 2015) and a significant economic impact with the development of treatments, vaccinations and research (Molinari et al. 2007). The entirety of the influenza genome is comprised of only eleven coding genes. An enormous degree of variation in non-conserved regions leads to significant challenges in the development of inclusive inhibitors for treatment. The fusion peptide domain of the influenza A hemagglutinin (HA) is a promising candidate for treatment since it is one of the most highly conserved sequences in the influenza genome (Heiny et al. 2007), and it is vital to the viral life cycle. Hemagglutinin is a class I viral fusion protein that catalyzes the membrane fusion process during cellular entry and infection. Impediment of the hemagglutinin's function, either through incomplete post-translational processing (Klenk et al. 1975; Lazarowitz and Choppin 1975) or through mutations (Cross et al. 2001), leads to non-infective virus particles. This review will investigate current research on the role of hemagglutinin in the virus life cycle, its structural biology and mechanism as well as the central role of the hemagglutinin fusion peptide (HAfp) to influenza membrane fusion and infection.
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Affiliation(s)
- Sean T Smrt
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, 60607, USA
| | - Justin L Lorieau
- Department of Chemistry, University of Illinois at Chicago, Chicago, IL, 60607, USA.
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36
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Curthoys NM, Parent M, Mlodzianoski M, Nelson AJ, Lilieholm J, Butler MB, Valles M, Hess ST. Dances with Membranes: Breakthroughs from Super-resolution Imaging. CURRENT TOPICS IN MEMBRANES 2015; 75:59-123. [PMID: 26015281 PMCID: PMC5584789 DOI: 10.1016/bs.ctm.2015.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Biological membrane organization mediates numerous cellular functions and has also been connected with an immense number of human diseases. However, until recently, experimental methodologies have been unable to directly visualize the nanoscale details of biological membranes, particularly in intact living cells. Numerous models explaining membrane organization have been proposed, but testing those models has required indirect methods; the desire to directly image proteins and lipids in living cell membranes is a strong motivation for the advancement of technology. The development of super-resolution microscopy has provided powerful tools for quantification of membrane organization at the level of individual proteins and lipids, and many of these tools are compatible with living cells. Previously inaccessible questions are now being addressed, and the field of membrane biology is developing rapidly. This chapter discusses how the development of super-resolution microscopy has led to fundamental advances in the field of biological membrane organization. We summarize the history and some models explaining how proteins are organized in cell membranes, and give an overview of various super-resolution techniques and methods of quantifying super-resolution data. We discuss the application of super-resolution techniques to membrane biology in general, and also with specific reference to the fields of actin and actin-binding proteins, virus infection, mitochondria, immune cell biology, and phosphoinositide signaling. Finally, we present our hopes and expectations for the future of super-resolution microscopy in the field of membrane biology.
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Affiliation(s)
- Nikki M. Curthoys
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Matthew Parent
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | | | - Andrew J. Nelson
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Jennifer Lilieholm
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Michael B. Butler
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Matthew Valles
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
| | - Samuel T. Hess
- Department of Physics and Astronomy, University of Maine, Orono, ME, USA
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37
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A cholesterol consensus motif is required for efficient intracellular transport and raft association of a group 2 HA from influenza virus. Biochem J 2015; 465:305-14. [DOI: 10.1042/bj20141114] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The external part of the transmembrane region of HA (haemagglutinin) of influenza virus contains a cholesterol consensus motif originally identified in G-protein-coupled receptors. Various mutations in this motif retard transport of HA through the Golgi and reduce raft association.
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Fedorenko G, Neginskaya M, Fedorenko A, Uzdensky A. The paired neuroglial and interglial membranes in the crayfish stretch receptor and their local disorganization. J Neurosci Res 2014; 93:707-13. [DOI: 10.1002/jnr.23530] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 10/19/2014] [Accepted: 11/10/2014] [Indexed: 11/10/2022]
Affiliation(s)
- Grigory Fedorenko
- Academy of Biology and Biotechnology; Southern Federal University; Rostov-on-Don Russia
- Institute of Arid Zones; RAN, Rostov-on-Don; Russia
| | - Marya Neginskaya
- Academy of Biology and Biotechnology; Southern Federal University; Rostov-on-Don Russia
| | - Alexej Fedorenko
- Academy of Biology and Biotechnology; Southern Federal University; Rostov-on-Don Russia
| | - Anatoly Uzdensky
- Academy of Biology and Biotechnology; Southern Federal University; Rostov-on-Don Russia
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Domanska MK, Wrona D, Kasson PM. Multiphasic effects of cholesterol on influenza fusion kinetics reflect multiple mechanistic roles. Biophys J 2014; 105:1383-7. [PMID: 24047989 DOI: 10.1016/j.bpj.2013.08.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 07/13/2013] [Accepted: 08/06/2013] [Indexed: 10/26/2022] Open
Abstract
The envelope lipid composition of influenza virus differs from that of the cellular plasma membrane from which it buds. Viruses also appear to fuse preferentially to specific membrane compartments, suggesting that the lipid environment may influence permissiveness for fusion. Here, we investigated the influence of the membrane environment on fusion, focusing on cholesterol composition. Strikingly, manipulating cholesterol levels in the viral membrane had different effects on fusion kinetics compared with analogous changes to the target membrane. Increasing cholesterol content in target vesicles increased lipid- and contents-mixing rates. Moderate cholesterol depletion from the viral membrane sped fusion rates, whereas severe depletion slowed the process. The pleiotropic effects of cholesterol include alterations in both membrane-bending moduli and lateral organization. Because influenza virions have demonstrated cholesterol-dependent lateral organization, to separate these effects, we deliberately selected a target vesicle composition that does not support lateral heterogeneity. We therefore postulate that the monotonic response of fusion kinetics to target membrane cholesterol reflects bending and curvature effects, whereas the multiphasic response to viral cholesterol levels reflects the combined effects of lateral organization and material properties.
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Affiliation(s)
- Marta K Domanska
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia; Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
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Desai TM, Marin M, Chin CR, Savidis G, Brass AL, Melikyan GB. IFITM3 restricts influenza A virus entry by blocking the formation of fusion pores following virus-endosome hemifusion. PLoS Pathog 2014; 10:e1004048. [PMID: 24699674 PMCID: PMC3974867 DOI: 10.1371/journal.ppat.1004048] [Citation(s) in RCA: 239] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 02/18/2014] [Indexed: 02/04/2023] Open
Abstract
Interferon-induced transmembrane proteins (IFITMs) inhibit infection of diverse enveloped viruses, including the influenza A virus (IAV) which is thought to enter from late endosomes. Recent evidence suggests that IFITMs block virus hemifusion (lipid mixing in the absence of viral content release) by altering the properties of cell membranes. Consistent with this mechanism, excess cholesterol in late endosomes of IFITM-expressing cells has been reported to inhibit IAV entry. Here, we examined IAV restriction by IFITM3 protein using direct virus-cell fusion assay and single virus imaging in live cells. IFITM3 over-expression did not inhibit lipid mixing, but abrogated the release of viral content into the cytoplasm. Although late endosomes of IFITM3-expressing cells accumulated cholesterol, other interventions leading to aberrantly high levels of this lipid did not inhibit virus fusion. These results imply that excess cholesterol in late endosomes is not the mechanism by which IFITM3 inhibits the transition from hemifusion to full fusion. The IFITM3's ability to block fusion pore formation at a post-hemifusion stage shows that this protein stabilizes the cytoplasmic leaflet of endosomal membranes without adversely affecting the lumenal leaflet. We propose that IFITM3 interferes with pore formation either directly, through partitioning into the cytoplasmic leaflet of a hemifusion intermediate, or indirectly, by modulating the lipid/protein composition of this leaflet. Alternatively, IFITM3 may redirect IAV fusion to a non-productive pathway, perhaps by promoting fusion with intralumenal vesicles within multivesicular bodies/late endosomes. Interferon-induced transmembrane proteins (IFITMs) block infection of many enveloped viruses, including the influenza A virus (IAV) that enters from late endosomes. IFITMs are thought to prevent virus hemifusion (merger of contacting leaflets without formation of a fusion pore) by altering the properties of cell membranes. Here we performed single IAV imaging and found that IFITM3 did not interfere with hemifusion, but prevented complete fusion. Also, contrary to a current view that excess cholesterol in late endosomes of IFITM3-expressing cells inhibits IAV entry, we show that cholesterol-laden endosomes are permissive for virus fusion. The ability of IFITM3 to block the formation of fusion pores implies that this protein stabilizes the cytoplasmic leaflet of endosomal membranes, either directly or indirectly, through altering its physical properties. IFITM3 may also redirect IAV to a non-productive pathway by promoting fusion with intralumenal vesicles of late endosomes instead of their limiting membrane.
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Affiliation(s)
- Tanay M. Desai
- Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta, Georgia, United States of America
| | - Mariana Marin
- Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta, Georgia, United States of America
| | - Christopher R. Chin
- Microbiology and Physiological Systems (MaPS) Department, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - George Savidis
- Microbiology and Physiological Systems (MaPS) Department, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Abraham L. Brass
- Microbiology and Physiological Systems (MaPS) Department, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Gregory B. Melikyan
- Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta, Georgia, United States of America
- Children's Healthcare of Atlanta, Atlanta, Georgia, United States of America
- * E-mail:
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Abstract
Lipid droplets are intracellular organelles that are found in most cells, where they have fundamental roles in metabolism. They function prominently in storing oil-based reserves of metabolic energy and components of membrane lipids. Lipid droplets are the dispersed phase of an oil-in-water emulsion in the aqueous cytosol of cells, and the importance of basic biophysical principles of emulsions for lipid droplet biology is now being appreciated. Because of their unique architecture, with an interface between the dispersed oil phase and the aqueous cytosol, specific mechanisms underlie their formation, growth and shrinkage. Such mechanisms enable cells to use emulsified oil when the demands for metabolic energy or membrane synthesis change. The regulation of the composition of the phospholipid surfactants at the surface of lipid droplets is crucial for lipid droplet homeostasis and protein targeting to their surfaces.
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Mutations of two transmembrane cysteines of hemagglutinin (HA) from influenza A H3N2 virus affect HA thermal stability and fusion activity. Virus Genes 2013; 47:20-6. [PMID: 23749101 DOI: 10.1007/s11262-013-0924-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Accepted: 05/22/2013] [Indexed: 10/26/2022]
Abstract
Influenza A H3N2 virus caused 1968 Hong Kong influenza pandemic, and has since been one of the most prevalent seasonal influenza viruses in global populations, representing a credible pandemic candidate in future. Previous studies have established that the hemagglutinin (HA) protein is the predominant antigen and executes receptor binding and membrane fusion. Homologous sequence analysis of all HA subtypes of influenza viruses revealed that two cysteine residues (540 and 544) are uniquely present in the transmembrane domain (TM) of HA proteins from all influenza A H3N2 viruses. However, the functions of these two cysteines have not been fully studied. Here, we generated three mutants (C540S, C544L, and 2C/SL) to investigate the effects of the two TM cysteines on the biological functions of H3 HA. We herein presented evidences that the mutations of one or two of the cysteines did not affect the proper expressions of HA proteins in cells, and more importantly all mutant H3 HAs showed decreased thermal stability but increased fusion activity in comparison with wildtype HA. Our results taken together demonstrated that the two TM cysteines are important for the biological functions of H3 HA proteins.
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Schaap IAT, Eghiaian F, des Georges A, Veigel C. Effect of envelope proteins on the mechanical properties of influenza virus. J Biol Chem 2012; 287:41078-88. [PMID: 23048030 DOI: 10.1074/jbc.m112.412726] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The envelope of the influenza virus undergoes extensive structural change during the viral life cycle. However, it is unknown how lipid and protein components of the viral envelope contribute to its mechanical properties. Using atomic force microscopy, here we show that the lipid envelope of spherical influenza virions is ∼10 times softer (∼0.05 nanonewton nm(-1)) than a viral protein-capsid coat and sustains deformations of one-third of the virion's diameter. Compared with phosphatidylcholine liposomes, it is twice as stiff, due to membrane-attached protein components. We found that virus indentation resulted in a biphasic force-indentation response. We propose that the first phase, including a stepwise reduction in stiffness at ∼10-nm indentation and ∼100 piconewtons of force, is due to mobilization of membrane proteins by the indenting atomic force microscope tip, consistent with the glycoprotein ectodomains protruding ∼13 nm from the bilayer surface. This phase was obliterated for bromelain-treated virions with the ectodomains removed. Following pH 5 treatment, virions were as soft as pure liposomes, consistent with reinforcing proteins detaching from the lipid bilayer. We propose that the soft, pH-dependent mechanical properties of the envelope are critical for the pH-regulated life cycle and support the persistence of the virus inside and outside the host.
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Affiliation(s)
- Iwan A T Schaap
- National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom
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44
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Abstract
The article summarises the results of more than 30 years of research on palmitoylation (S‐acylation) of viral proteins, the post‐translational attachment of fatty acids to cysteine residues of integral and peripheral membrane proteins. Analysing viral proteins is not only important to characterise the cellular pathogens but also instrumental to decipher the palmitoylation machinery of cells. This comprehensive review describes methods to identify S‐acylated proteins and covers the fundamental biochemistry of palmitoylation: the location of palmitoylation sites in viral proteins, the fatty acid species found in S‐acylated proteins, the intracellular site of palmitoylation and the enzymology of the reaction. Finally, the functional consequences of palmitoylation are discussed regarding binding of proteins to membranes or membrane rafts, entry of enveloped viruses into target cells by spike‐mediated membrane fusion as well as assembly and release of virus particles from infected cells. The topics are described mainly for palmitoylated proteins of influenza virus, but proteins of other important pathogens, such as the causative agents of AIDS and severe acute respiratory syndrome, and of model viruses are discussed.
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Affiliation(s)
- Michael Veit
- Department of Immunology and Molecular Biology, Free University, Berlin, Germany.
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45
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46
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Laliberte JP, Weisberg AS, Moss B. The membrane fusion step of vaccinia virus entry is cooperatively mediated by multiple viral proteins and host cell components. PLoS Pathog 2011; 7:e1002446. [PMID: 22194690 PMCID: PMC3240603 DOI: 10.1371/journal.ppat.1002446] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 11/03/2011] [Indexed: 01/05/2023] Open
Abstract
For many viruses, one or two proteins allow cell attachment and entry, which occurs through the plasma membrane or following endocytosis at low pH. In contrast, vaccinia virus (VACV) enters cells by both neutral and low pH routes; four proteins mediate cell attachment and twelve that are associated in a membrane complex and conserved in all poxviruses are dedicated to entry. The aim of the present study was to determine the roles of cellular and viral proteins in initial stages of entry, specifically fusion of the membranes of the mature virion and cell. For analysis of the role of cellular components, we used well characterized inhibitors and measured binding of a recombinant VACV virion containing Gaussia luciferase fused to a core protein; viral and cellular membrane lipid mixing with a self-quenching fluorescent probe in the virion membrane; and core entry with a recombinant VACV expressing firefly luciferase and electron microscopy. We determined that inhibitors of tyrosine protein kinases, dynamin GTPase and actin dynamics had little effect on binding of virions to cells but impaired membrane fusion, whereas partial cholesterol depletion and inhibitors of endosomal acidification and membrane blebbing had a severe effect at the later stage of core entry. To determine the role of viral proteins, virions lacking individual membrane components were purified from cells infected with members of a panel of ten conditional-lethal inducible mutants. Each of the entry protein-deficient virions had severely reduced infectivity and except for A28, L1 and L5 greatly impaired membrane fusion. In addition, a potent neutralizing L1 monoclonal antibody blocked entry at a post-membrane lipid-mixing step. Taken together, these results suggested a 2-step entry model and implicated an unprecedented number of viral proteins and cellular components involved in signaling and actin rearrangement for initiation of virus-cell membrane fusion during poxvirus entry. Poxviruses are large DNA viruses that cause diseases in humans and other animals. To initiate infection, the core of the large, membrane-enveloped particle must penetrate into the cytoplasm where replication occurs. For most enveloped viruses only one or two proteins are needed for attachment and penetration. However, at least sixteen poxvirus proteins are dedicated to entry: four for attachment and twelve for penetration. The latter proteins form the entry fusion complex (EFC) and are conserved in all poxviruses indicating that the entry mechanism has been retained since the origin of the family. The purpose of the present study was to determine the cellular processes and poxviral proteins needed for fusion of the viral and cellular membranes. We found that a variety of inhibitors that interfered with cell signaling and reorganization of the actin cytoskeleton prevented membrane fusion as determined by lipid mixing, whereas others targeted the subsequent stage in entry. In addition, seven viral protein components of the EFC were required for the initial membrane fusion step, whereas three were not. A neutralizing monoclonal antibody to one of the latter also did not interfere with membrane lipid mixing but still prevented core entry supporting a 2-step poxvirus entry model.
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Affiliation(s)
- Jason P. Laliberte
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Andrea S. Weisberg
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Bernard Moss
- Laboratory of Viral Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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47
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Association of influenza virus proteins with membrane rafts. Adv Virol 2011; 2011:370606. [PMID: 22312341 PMCID: PMC3265303 DOI: 10.1155/2011/370606] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Accepted: 05/02/2011] [Indexed: 12/12/2022] Open
Abstract
Assembly and budding of influenza virus proceeds in the viral budozone, a domain in the plasma membrane with characteristics of cholesterol/sphingolipid-rich membrane rafts. The viral transmembrane glycoproteins hemagglutinin (HA) and neuraminidase (NA) are intrinsically targeted to these domains, while M2 is seemingly targeted to the edge of the budozone. Virus assembly is orchestrated by the matrix protein M1, binding to all viral components and the membrane. Budding progresses by protein- and lipid-mediated membrane bending and particle scission probably mediated by M2. Here, we summarize the experimental evidence for this model with emphasis on the raft-targeting features of HA, NA, and M2 and review the functional importance of raft domains for viral protein transport, assembly and budding, environmental stability, and membrane fusion.
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48
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Promotion of vesicular stomatitis virus fusion by the endosome-specific phospholipid bis(monoacylglycero)phosphate (BMP). FEBS Lett 2011; 585:865-9. [PMID: 21333650 DOI: 10.1016/j.febslet.2011.02.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 02/08/2011] [Accepted: 02/11/2011] [Indexed: 11/22/2022]
Abstract
Vesicular stomatitis virus (VSV) is a prototypic virus commonly used in studies of endocytosis and membrane trafficking. One proposed mechanism for VSV entry involves initial fusion with internal vesicles of multivesicular endosomes followed by back-fusion of these vesicles into the cytoplasm. One feature of endosomal internal vesicles is that they contain the lipid bis(monoacylglycero)phosphate (BMP). Here, we show that the presence of BMP significantly increases the rate of VSV G-mediated membrane fusion. The increased fusion was selective for VSV and was not evident for another enveloped virus, influenza virus. Our data provide a biological rationale for a two-step infection reaction during VSV entry, and suggest that BMP preferentially affects the ability of VSV G to mediate lipid mixing during membrane fusion.
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Freitas MS, Follmer C, Costa LT, Vilani C, Bianconi ML, Achete CA, Silva JL. Measuring the strength of interaction between the Ebola fusion peptide and lipid rafts: implications for membrane fusion and virus infection. PLoS One 2011; 6:e15756. [PMID: 21249196 PMCID: PMC3020948 DOI: 10.1371/journal.pone.0015756] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Accepted: 11/23/2010] [Indexed: 12/17/2022] Open
Abstract
The Ebola fusion peptide (EBO16) is a hydrophobic domain that belongs to the GP2 membrane fusion protein of the Ebola virus. It adopts a helical structure in the presence of mimetic membranes that is stabilized by the presence of an aromatic-aromatic interaction established by Trp8 and Phe12. In spite of its infectious cycle becoming better understood recently, several steps still remain unclear, a lacuna that makes it difficult to develop strategies to block infection. In order to gain insight into the mechanism of membrane fusion, we probed the structure, function and energetics of EBO16 and its mutant W8A, in the absence or presence of different lipid membranes, including isolated domain-resistant membranes (DRM), a good experimental model for lipid rafts. The depletion of cholesterol from living mammalian cells reduced the ability of EBO16 to induce lipid mixing. On the other hand, EBO16 was structurally sensitive to interaction with lipid rafts (DRMs), but the same was not observed for W8A mutant. In agreement with these data, W8A showed a poor ability to promote membrane aggregation in comparison to EBO16. Single molecule AFM experiments showed a high affinity force pattern for the interaction of EBO16 and DRM, which seems to be a complex energetic event as observed by the calorimetric profile. Our study is the first to show a strong correlation between the initial step of Ebola virus infection and cholesterol, thus providing a rationale for Ebola virus proteins being co-localized with lipid-raft domains. In all, the results show how small fusion peptide sequences have evolved to adopt highly specific and strong interactions with membrane domains. Such features suggest these processes are excellent targets for therapeutic and vaccine approaches to viral diseases.
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Affiliation(s)
- Mônica S. Freitas
- Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica, Instituto Nacional de Ciências e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Cristian Follmer
- Departamento de Físico-Química, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lilian T. Costa
- Divisão de Metrologia de Materiais (DIMAT), Inmetro, Rio de Janeiro, Brazil
| | - Cecília Vilani
- Divisão de Metrologia de Materiais (DIMAT), Inmetro, Rio de Janeiro, Brazil
| | - M. Lucia Bianconi
- Laboratorio de Biocalorimetria, Instituto de Bioqumica Medica, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Carlos Alberto Achete
- Divisão de Metrologia de Materiais (DIMAT), Inmetro, Rio de Janeiro, Brazil
- Programa de Engenharia Metalúrgica e de Materiais, COPPE, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil
| | - Jerson L. Silva
- Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica, Instituto Nacional de Ciências e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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50
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The fusion of synaptic vesicle membranes studied by lipid mixing: the R18 fluorescence assay validity. Chem Phys Lipids 2010; 163:778-86. [DOI: 10.1016/j.chemphyslip.2010.09.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2010] [Revised: 09/03/2010] [Accepted: 09/07/2010] [Indexed: 12/27/2022]
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