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Raghunath G, Abbott EH, Marin M, Wu H, Reyes Ballista JM, Brindley MA, Melikyan GB. Disruption of Transmembrane Phosphatidylserine Asymmetry by HIV-1 Incorporated SERINC5 Is Not Responsible for Virus Restriction. Biomolecules 2024; 14:570. [PMID: 38785977 PMCID: PMC11118262 DOI: 10.3390/biom14050570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Revised: 04/26/2024] [Accepted: 05/08/2024] [Indexed: 05/25/2024] Open
Abstract
Host restriction factor SERINC5 (SER5) incorporates into the HIV-1 membrane and inhibits infectivity by a poorly understood mechanism. Recently, SER5 was found to exhibit scramblase-like activity leading to the externalization of phosphatidylserine (PS) on the viral surface, which has been proposed to be responsible for SER5's antiviral activity. This and other reports that document modulation of HIV-1 infectivity by viral lipid composition prompted us to investigate the role of PS in regulating SER5-mediated HIV-1 restriction. First, we show that the level of SER5 incorporation into virions correlates with an increase in PS levels in the outer leaflet of the viral membrane. We developed an assay to estimate the PS distribution across the viral membrane and found that SER5, but not SER2, which lacks antiviral activity, abrogates PS asymmetry by externalizing this lipid. Second, SER5 incorporation diminished the infectivity of pseudoviruses produced from cells lacking a flippase subunit CDC50a and, therefore, exhibited a higher baseline level of surface-accessible PS. Finally, exogenous manipulation of the viral PS levels utilizing methyl-alpha-cyclodextrin revealed a lack of correlation between external PS and virion infectivity. Taken together, our study implies that the increased PS exposure to SER5-containing virions itself is not directly linked to HIV-1 restriction.
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Affiliation(s)
- Gokul Raghunath
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Elizabeth H. Abbott
- Emory College of Arts and Sciences, Emory University, Atlanta, GA 30322, USA
| | - Mariana Marin
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Hui Wu
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (M.M.); (H.W.)
| | - Judith Mary Reyes Ballista
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA; (J.M.R.B.); (M.A.B.)
| | - Melinda A. Brindley
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA; (J.M.R.B.); (M.A.B.)
- Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Gregory B. Melikyan
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
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2
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Sid Ahmed S, Bajak K, Fackler OT. Beyond Impairment of Virion Infectivity: New Activities of the Anti-HIV Host Cell Factor SERINC5. Viruses 2024; 16:284. [PMID: 38400059 PMCID: PMC10892966 DOI: 10.3390/v16020284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/07/2024] [Accepted: 02/09/2024] [Indexed: 02/25/2024] Open
Abstract
Members of the serine incorporator (SERINC) protein family exert broad antiviral activity, and many viruses encode SERINC antagonists to circumvent these restrictions. Significant new insight was recently gained into the mechanisms that mediate restriction and antagonism. In this review, we summarize our current understanding of the mode of action and relevance of SERINC proteins in HIV-1 infection. Particular focus will be placed on recent findings that provided important new mechanistic insights into the restriction of HIV-1 virion infectivity, including the discovery of SERINC's lipid scramblase activity and its antagonism by the HIV-1 pathogenesis factor Nef. We also discuss the identification and implications of several additional antiviral activities by which SERINC proteins enhance pro-inflammatory signaling and reduce viral gene expression in myeloid cells. SERINC proteins emerge as versatile and multifunctional regulators of cell-intrinsic immunity against HIV-1 infection.
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Affiliation(s)
- Samy Sid Ahmed
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany; (S.S.A.); (K.B.)
| | - Kathrin Bajak
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany; (S.S.A.); (K.B.)
- German Centre for Infection Research (DZIF), Partner Site Heidelberg, 38124 Heidelberg, Germany
| | - Oliver T. Fackler
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, 69120 Heidelberg, Germany; (S.S.A.); (K.B.)
- German Centre for Infection Research (DZIF), Partner Site Heidelberg, 38124 Heidelberg, Germany
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3
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Merklinger L, Morth JP. Phospholipid Preparations to Characterize Protein-Lipid Interactions In Vitro. Bio Protoc 2023; 22:e4887. [PMID: 38026763 PMCID: PMC10665634 DOI: 10.21769/bioprotoc.4887] [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: 02/10/2023] [Revised: 09/08/2023] [Accepted: 09/18/2023] [Indexed: 12/01/2023] Open
Abstract
The lipid bilayers of the cell are composed of various lipid classes and species. These engage in cell signaling and regulation by recruiting cytosolic proteins to the membrane and interacting with membrane-embedded proteins to alternate their activity and stability. Like lipids, membrane proteins are amphipathic and are stabilized by the hydrophobic forces of the lipid bilayer. Membrane protein-lipid interactions are difficult to investigate since membrane proteins need to be reconstituted in a lipid-mimicking environment. A common and well-established approach is the detergent-based solubilization of the membrane proteins in detergent micelles. Nowadays, nanodiscs and liposomes are used to mimic the lipid bilayer and enable the work with membrane proteins in a more natural environment. However, these protocols need optimization and are labor intensive. The present protocol describes straightforward instructions on how the preparation of lipids is performed and how the lipid detergent mixture is integrated with the membrane protein MARCH5. The lipidation protocol was performed prior to an activity assay specific to membrane-bound E3 ubiquitin ligases and a stability assay that could be used for any membrane protein of choice.
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Affiliation(s)
- Lisa Merklinger
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - J. Preben Morth
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
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4
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Nkuwi E, Judicate GP, Tan TS, Barabona G, Toyoda M, Sunguya B, Kamori D, Ueno T. Relative resistance of patient-derived envelope sequences to SERINC5-mediated restriction of HIV-1 infectivity. J Virol 2023; 97:e0082323. [PMID: 37768085 PMCID: PMC10617508 DOI: 10.1128/jvi.00823-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Accepted: 08/13/2023] [Indexed: 09/29/2023] Open
Abstract
IMPORTANCE Pathogenesis of HIV-1 is enhanced through several viral-encoded proteins that counteract a range of host restriction molecules. HIV-1 Nef counteracts the cell membrane protein SERINC5 by downregulating it from the cell surface, thereby enhancing virion infectivity. Some subtype B reference Envelope sequences have shown the ability to bypass SERINC5 infectivity restriction independent of Nef. However, it is not clear if and to what extent circulating HIV-1 strains can exhibit resistance to SERINC5 restriction. Using a panel of Envelope sequences isolated from 50 Tanzanians infected with non-B HIV-1 subtypes, we show that the lentiviral reporters pseudotyped with patient-derived Envelopes have reduced sensitivity to SERINC5 and that this sensitivity differed among viral subtypes. Moreover, we found that SERINC5 sensitivity within patient-derived Envelopes can be modulated by separate regions, highlighting the complexity of viral/host interactions.
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Affiliation(s)
- Emmanuel Nkuwi
- Division of Infection and Immunity, Joint Research Center for Human Retrovirus Infection Kumamoto University, Kumamoto, Japan
- Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
- Department of Microbiology and Parasitology, The University of Dodoma, Dodoma, Tanzania
| | - George P. Judicate
- Division of Infection and Immunity, Joint Research Center for Human Retrovirus Infection Kumamoto University, Kumamoto, Japan
| | - Toong Seng Tan
- Division of Infection and Immunity, Joint Research Center for Human Retrovirus Infection Kumamoto University, Kumamoto, Japan
| | - Godfrey Barabona
- Division of Infection and Immunity, Joint Research Center for Human Retrovirus Infection Kumamoto University, Kumamoto, Japan
| | - Mako Toyoda
- Division of Infection and Immunity, Joint Research Center for Human Retrovirus Infection Kumamoto University, Kumamoto, Japan
| | - Bruno Sunguya
- Collaboration Unit for Infection, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
- Department of Community Health, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Doreen Kamori
- Collaboration Unit for Infection, Joint Research Center for Human Retrovirus Infection, Kumamoto University, Kumamoto, Japan
- Department of Microbiology and Immunology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Takamasa Ueno
- Division of Infection and Immunity, Joint Research Center for Human Retrovirus Infection Kumamoto University, Kumamoto, Japan
- Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
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5
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Leonhardt SA, Purdy MD, Grover JR, Yang Z, Poulos S, McIntire WE, Tatham EA, Erramilli SK, Nosol K, Lai KK, Ding S, Lu M, Uchil PD, Finzi A, Rein A, Kossiakoff AA, Mothes W, Yeager M. Antiviral HIV-1 SERINC restriction factors disrupt virus membrane asymmetry. Nat Commun 2023; 14:4368. [PMID: 37474505 PMCID: PMC10359404 DOI: 10.1038/s41467-023-39262-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 06/06/2023] [Indexed: 07/22/2023] Open
Abstract
The host proteins SERINC3 and SERINC5 are HIV-1 restriction factors that reduce infectivity when incorporated into the viral envelope. The HIV-1 accessory protein Nef abrogates incorporation of SERINCs via binding to intracellular loop 4 (ICL4). Here, we determine cryoEM maps of full-length human SERINC3 and an ICL4 deletion construct, which reveal that hSERINC3 is comprised of two α-helical bundles connected by a ~ 40-residue, highly tilted, "crossmember" helix. The design resembles non-ATP-dependent lipid transporters. Consistently, purified hSERINCs reconstituted into proteoliposomes induce flipping of phosphatidylserine (PS), phosphatidylethanolamine and phosphatidylcholine. Furthermore, SERINC3, SERINC5 and the scramblase TMEM16F expose PS on the surface of HIV-1 and reduce infectivity, with similar results in MLV. SERINC effects in HIV-1 and MLV are counteracted by Nef and GlycoGag, respectively. Our results demonstrate that SERINCs are membrane transporters that flip lipids, resulting in a loss of membrane asymmetry that is strongly correlated with changes in Env conformation and loss of infectivity.
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Grants
- P01 AI150471 NIAID NIH HHS
- P41 GM103311 NIGMS NIH HHS
- G20 RR031199 NCRR NIH HHS
- R01 GM117372 NIGMS NIH HHS
- U54 AI170856 NIAID NIH HHS
- S10 OD018149 NIH HHS
- U24 GM129539 NIGMS NIH HHS
- S10 RR025067 NCRR NIH HHS
- This work was supported by the National Institutes of Health (NIH) grants P50 AI15046 and U54 AI170856-01 (M.Y., W.M. and A.K.K.), R01 AI154092 (M.Y.), R01 GM117372 (A.A.K.) and P01 AI150471 (W.M.)., by the Intramural Research Program of the NIH, National Cancer Institute, Center for Cancer Research, and in part by the NIH Intramural AIDS Targeted Antiviral Program. S.D. and A.F. were supported by the CIHR grant 352417 and a Canada Research Chair. Some molecular graphics and analyses were performed with the University of California, San Francisco Chimera package. Chimera is developed by the Resource for Biocomputing, Visualization, and Informatics at the University of California, San Francisco (supported by the National Institute of General Medical Sciences Grant P41 GM103311).
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Affiliation(s)
- Susan A Leonhardt
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, University of Miami, Coral Gables, FL, 33146, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Michael D Purdy
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Molecular Electron Microscopy Core, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Jonathan R Grover
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Ziwei Yang
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Sandra Poulos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - William E McIntire
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, University of Miami, Coral Gables, FL, 33146, USA
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Elizabeth A Tatham
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Kamil Nosol
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Kin Kui Lai
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, P.O. Box B, Building 535, Frederick, MD, 21702, USA
| | - Shilei Ding
- Centre de Recherche du CHUM (CRCHUM), Montreal, QC, Canada
| | - Maolin Lu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA
- Department of Cellular and Molecular Biology, University of Texas Health Science Center, Tyler, TX, USA
| | - Pradeep D Uchil
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA
| | - Andrés Finzi
- Centre de Recherche du CHUM (CRCHUM), Montreal, QC, Canada
- Département de Microbiologie, Infectiologie et Immunologie, Université de Montréal, Montreal, QC, Canada
| | - Alan Rein
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, P.O. Box B, Building 535, Frederick, MD, 21702, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Walther Mothes
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, 06510, USA.
| | - Mark Yeager
- The Phillip and Patricia Frost Institute for Chemistry and Molecular Science, University of Miami, Coral Gables, FL, 33146, USA.
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
- Department of Chemistry, University of Miami, Coral Gables, FL, 33146, USA.
- Department of Biochemistry and Molecular Biology, University of Miami, Miami, FL, 33136, USA.
- Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
- Department of Medicine, Division of Cardiovascular Medicine, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
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6
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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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7
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Firrito C, Bertelli C, Rosa A, Chande A, Ananth S, van Dijk H, Fackler OT, Stoneham C, Singh R, Guatelli J, Pizzato M. A Conserved Acidic Residue in the C-Terminal Flexible Loop of HIV-1 Nef Contributes to the Activity of SERINC5 and CD4 Downregulation. Viruses 2023; 15:652. [PMID: 36992361 PMCID: PMC10057511 DOI: 10.3390/v15030652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/22/2023] [Accepted: 02/27/2023] [Indexed: 03/05/2023] Open
Abstract
The host transmembrane protein SERINC5 is incorporated into retrovirus particles and inhibits HIV-1 infectivity. The lentiviral Nef protein counteracts SERINC5 by downregulating it from the cell surface and preventing its incorporation into virions. The ability of Nef to antagonize the host factor varies in magnitude between different HIV-1 isolates. After having identified a subtype H nef allele unable to promote HIV-1 infectivity in the presence of SERINC5, we investigated the molecular determinants responsible for the defective counteraction of the host factor. Chimeric molecules with a subtype C Nef highly active against SERINC5 were constructed to locate Nef residues crucial for the activity against SERINC5. An Asn at the base of the C-terminal loop of the defective nef allele was found in place of a highly conserved acidic residue (D/E 150). The conversion of Asn to Asp restored the ability of the defective Nef to downregulate SERINC5 and promote HIV-1 infectivity. The substitution was also found to be crucial for the ability of Nef to downregulate CD4, but not for Nef activities that do not rely on the internalization of receptors from the cell surface, suggesting a general implication in promoting clathrin-mediated endocytosis. Accordingly, bimolecular fluorescence complementation revealed that the conserved acidic residue contributes to the recruitment of AP2 by Nef. Altogether, our results confirm that Nef downregulates SERINC5 and CD4 by engaging a similar machinery and indicates that, in addition to the di-leucine motif, other residues in the C-terminal flexible loop are important for the ability of the protein to sustain clathrin-mediated endocytosis.
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Affiliation(s)
- Claudia Firrito
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
| | - Cinzia Bertelli
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
| | - Annachiara Rosa
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
| | - Ajit Chande
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
| | - Swetha Ananth
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Hannah van Dijk
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany
| | - Oliver T. Fackler
- Department of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, 69120 Heidelberg, Germany
- German Center for Infection Research (DZIF), 69120 Heidelberg, Germany
| | - Charlotte Stoneham
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Rajendra Singh
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - John Guatelli
- Department of Medicine, University of California San Diego, La Jolla, CA 92093, USA
- VA San Diego Healthcare System, San Diego, CA 92161, USA
| | - Massimo Pizzato
- Department of Cellular, Computational and integrative Biology, University of Trento, 38123 Trento, Italy
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8
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Timilsina U, Stavrou S. SERINC5: One antiviral factor to bind them all. PLoS Pathog 2023; 19:e1011076. [PMID: 36656836 PMCID: PMC9851522 DOI: 10.1371/journal.ppat.1011076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Uddhav Timilsina
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, New York, United States of America
| | - Spyridon Stavrou
- Department of Microbiology and Immunology, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, New York, United States of America
- * E-mail:
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9
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Restriction of Influenza A Virus by SERINC5. mBio 2022; 13:e0292322. [PMID: 36409124 PMCID: PMC9765469 DOI: 10.1128/mbio.02923-22] [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: 11/23/2022] Open
Abstract
Serine incorporator 5 (Ser5), a transmembrane protein, has recently been identified as a host antiviral factor against human immunodeficiency virus (HIV)-1 and gammaretroviruses like murine leukemia viruses (MLVs). It is counteracted by HIV-1 Nef and MLV glycogag. We have investigated whether it has antiviral activity against influenza A virus (IAV), as well as retroviruses. Here, we demonstrated that Ser5 inhibited HIV-1-based pseudovirions bearing IAV hemagglutinin (HA); as expected, the Ser5 effect on this glycoprotein was antagonized by HIV-1 Nef protein. We found that Ser5 inhibited the virus-cell and cell-cell fusion of IAV, apparently by interacting with HA proteins. Most importantly, overexpressed and endogenous Ser5 inhibited infection by authentic IAV. Single-molecular fluorescent resonance energy transfer (smFRET) analysis further revealed that Ser5 both destabilized the pre-fusion conformation of IAV HA and inhibited the coiled-coil formation during membrane fusion. Ser5 is expressed in cultured small airway epithelial cells, as well as in immortal human cell lines. In summary, Ser5 is a host antiviral factor against IAV which acts by blocking HA-induced membrane fusion. IMPORTANCE SERINC5 (Ser5) is a cellular protein which has been found to interfere with the infectivity of HIV-1 and a number of other retroviruses. Virus particles produced in the presence of Ser5 are impaired in their ability to enter new host cells, but the mechanism of Ser5 action is not well understood. We now report that Ser5 also inhibits infectivity of Influenza A virus (IAV) and that it interferes with the conformational changes in IAV hemagglutinin protein involved in membrane fusion and virus entry. These findings indicate that the antiviral function of Ser5 extends to other viruses as well as retroviruses, and also provide some information on the molecular mechanism of its antiviral activity.
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10
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Raghunath G, Chen YC, Marin M, Wu H, Melikyan GB. SERINC5-Mediated Restriction of HIV-1 Infectivity Correlates with Resistance to Cholesterol Extraction but Not with Lipid Order of Viral Membrane. Viruses 2022; 14:v14081636. [PMID: 35893701 PMCID: PMC9332783 DOI: 10.3390/v14081636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 07/19/2022] [Accepted: 07/23/2022] [Indexed: 12/13/2022] Open
Abstract
Serine incorporator 5 (SER5) is a protein that upon incorporation into virions inhibits HIV-1 infectivity by interfering with the ability of the Env glycoprotein to promote viral fusion. The mechanisms by which SER5 antagonizes HIV-1 fusion are not well understood. A recent study of SER5's structure revealed a lipid-binding pocket, suggesting the ability to sequester lipids. This finding, along with the well-documented modulation of HIV-1 infectivity by viral lipids, especially cholesterol, prompted our examination of SER5's effect on the general lipid order of the HIV-1 membrane. Pseudoviruses bearing the SER5-sensitive HXB2-Env and containing SER5 or SER2, a control protein that lacks antiviral activity, were analyzed using two distinct lipid-order probes. We show that SER5 incorporation does not noticeably affect the lipid order of pseudoviruses. Although viral cholesterol extraction reduces HIV-1 infectivity, SER5+ viruses are less sensitive to cholesterol extraction than the control samples. In contrast, the virus' sensitivity to cholesterol oxidation was not affected by SER5 incorporation. The hydrolytic release of sphingomyelin-sequestered cholesterol had a minimal impact on the apparent resistance to cholesterol extraction. Based on these results, we propose that a subpopulation of more stable Env glycoproteins responsible for the residual infectivity of SER5+ viruses is less sensitive to the cholesterol content of the viral membrane.
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Affiliation(s)
- Gokul Raghunath
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (Y.-C.C.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Yen-Cheng Chen
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (Y.-C.C.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Mariana Marin
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (Y.-C.C.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Hui Wu
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (Y.-C.C.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Gregory B. Melikyan
- Department of Pediatrics, Division of Infectious Diseases, School of Medicine, Emory University, Atlanta, GA 30322, USA; (G.R.); (Y.-C.C.); (M.M.); (H.W.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
- Correspondence:
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11
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Kirschman J, Marin M, Chen YC, Chen J, Herschhorn A, Smith AB, Melikyan GB. SERINC5 Restricts HIV-1 Infectivity by Promoting Conformational Changes and Accelerating Functional Inactivation of Env. Viruses 2022; 14:1388. [PMID: 35891369 PMCID: PMC9323560 DOI: 10.3390/v14071388] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/18/2022] [Accepted: 06/23/2022] [Indexed: 12/16/2022] Open
Abstract
SERINC5 incorporates into HIV-1 particles and inhibits the ability of Env glycoprotein to mediate virus-cell fusion. SERINC5-resistance maps to Env, with primary isolates generally showing greater resistance than laboratory-adapted strains. Here, we examined a relationship between the inhibition of HIV-1 infectivity and the rate of Env inactivation using a panel of SERINC5-resistant and -sensitive HIV-1 Envs. SERINC5 incorporation into pseudoviruses resulted in a faster inactivation of sensitive compared to resistant Env strains. A correlation between fold reduction in infectivity and the rate of inactivation was also observed for multiple Env mutants known to stabilize and destabilize the closed Env structure. Unexpectedly, most mutations disfavoring the closed Env conformation rendered HIV-1 less sensitive to SERINC5. In contrast, functional inactivation of SERINC5-containing viruses was significantly accelerated in the presence of a CD4-mimetic compound, suggesting that CD4 binding sensitizes Env to SERINC5. Using a small molecule inhibitor that selectively targets the closed Env structure, we found that, surprisingly, SERINC5 increases the potency of this compound against a laboratory-adapted Env which prefers a partially open conformation, indicating that SERINC5 may stabilize the closed trimeric Env structure. Our results reveal a complex effect of SERINC5 on Env conformational dynamics that promotes Env inactivation and is likely responsible for the observed restriction phenotype.
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Affiliation(s)
- Junghwa Kirschman
- Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; (J.K.); (M.M.); (Y.-C.C.)
| | - Mariana Marin
- Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; (J.K.); (M.M.); (Y.-C.C.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Yen-Cheng Chen
- Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; (J.K.); (M.M.); (Y.-C.C.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Junhua Chen
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA; (J.C.); (A.B.S.III)
| | - Alon Herschhorn
- Division of Infectious Diseases and International Medicine, Department of Medicine, University of Minnesota, Minneapolis, MN 55455, USA;
| | - Amos B. Smith
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA; (J.C.); (A.B.S.III)
| | - Gregory B. Melikyan
- Department of Pediatrics, Emory University, Atlanta, GA 30322, USA; (J.K.); (M.M.); (Y.-C.C.)
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
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12
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SARS-CoV-2 ORF7a potently inhibits the antiviral effect of the host factor SERINC5. Nat Commun 2022; 13:2935. [PMID: 35618710 PMCID: PMC9135752 DOI: 10.1038/s41467-022-30609-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 04/22/2022] [Indexed: 01/03/2023] Open
Abstract
Serine Incorporator 5 (SERINC5), a cellular multipass transmembrane protein that is involved in sphingolipid and phosphatydilserine biogenesis, potently restricts a number of retroviruses, including Human Immunodeficiency Virus (HIV). SERINC5 is incorporated in the budding virions leading to the inhibition of virus infectivity. In turn, retroviruses, including HIV, encode factors that counteract the antiviral effect of SERINC5. While SERINC5 has been well studied in retroviruses, little is known about its role in other viral families. Due to the paucity of information regarding host factors targeting Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), we evaluated the effect of SERINC proteins on SARS-CoV-2 infection. Here, we show SERINC5 inhibits SARS-CoV-2 entry by blocking virus-cell fusion, and SARS-CoV-2 ORF7a counteracts the antiviral effect of SERINC5 by blocking the incorporation of over expressed SERINC5 in budding virions. SERINC5, is a cellular multipass transmembrane protein involved in sphingolipid and phosphatydilserine biogenesis and a known retroviral restriction factor. Here, Timilsina et al. show that SERINC5 is a host restriction factor for SARS-CoV-2 that prevents viral fusion during entry. Further they show that viral ORF7a counteracts SERINC5 anti-viral activity by blocking its incorporation into progeny virions.
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13
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Li S, Li R, Ahmad I, Liu X, Johnson SF, Sun L, Zheng YH. Cul3-KLHL20 E3 ubiquitin ligase plays a key role in the arms race between HIV-1 Nef and host SERINC5 restriction. Nat Commun 2022; 13:2242. [PMID: 35474067 PMCID: PMC9042822 DOI: 10.1038/s41467-022-30026-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 04/11/2022] [Indexed: 11/17/2022] Open
Abstract
HIV-1 must counteract various host restrictions to establish productive infection. SERINC5 is a potent restriction factor that blocks HIV-1 entry from virions, but its activity is counteracted by Nef. The SERINC5 and Nef activities are both initiated from the plasma membrane, where SERINC5 is packaged into virions for viral inhibition or downregulated by Nef via lysosomal degradation. However, it is still unclear how SERINC5 is localized to and how its expression is regulated on the plasma membrane. We now report that Cullin 3-KLHL20, a trans-Golgi network (TGN)-localized E3 ubiquitin ligase, polyubiquitinates SERINC5 at lysine 130 via K33/K48-linked ubiquitination. The K33-linked polyubiquitination determines SERINC5 expression on the plasma membrane, and the K48-linked polyubiquitination contributes to SERINC5 downregulation from the cell surface. Our study reveals an important role of K130 polyubiquitination and K33/K48-linked ubiquitin chains in HIV-1 infection by regulating SERINC5 post-Golgi trafficking and degradation. SERINC5 is a host-restriction factor preventing HIV progeny entry, which is counteracted by interactions with HIV Nef. Here, Li et al. show that E3 ubiquitin ligase Cullin 3 polyubiquitinates SERINC5 at Lys 130 via K48- and K33-linked ubiquitin chains and provide evidence that this modification is not only required for its membrane localization and anti-viral activity but also relevant for Nef counteractive activity.
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Affiliation(s)
- Sunan Li
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Rongrong Li
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Iqbal Ahmad
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Xiaomeng Liu
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Silas F Johnson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Yong-Hui Zheng
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China. .,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA.
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14
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Tu M, Saputo S. From Beginning to End: Expanding the SERINC3 Interactome Through an in silico Analysis. Bioinform Biol Insights 2022; 16:11779322221092944. [PMID: 35494555 PMCID: PMC9052817 DOI: 10.1177/11779322221092944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 03/07/2022] [Indexed: 11/15/2022] Open
Abstract
The serine incorporator (SERINC) family of proteins are a family of multipass transmembrane proteins associated with biosynthesis of serine-containing phospholipids and sphingolipids. Humans have 5 paralogs, SERINC1-5, which have been linked to disease including variable expression in tumor lines and possessing activity as restriction factors against HIV-1. Despite recent studies, the cellular function of SERINC proteins have yet to be fully elucidated. The goal of this study as to investigate the role of SERINC3 by expanding upon its interactome. We used a variety of bioinformatic tools to identify cellular factors that interact with SERINC3 and assessed how sequence variation might alter these interactions. Analysis of the promoter region indicates that SERINC3 is putatively regulated by transcription factors involved in tissue-specific development. Analysis of the unique 3′-untranslated region of one variant of HsSERINC3 revealed that this region serves as a conserved site of regulation by both RNA binding proteins and miRNA. In addition, SERINC3 is putatively regulated at the protein level by several posttranslational modifications. Our results show that extra-membrane portions of SERINC3 are subject to variation in the coding sequence as well as areas of relatively low conservation. Overall, our data suggest that regions of low homology as well as presence of variations in the nucleotide and protein sequences of HsSERINC3 suggest that these variations may lead to aberrant function and alternative regulatory mechanisms in homologs. The functional consequences of these sequence and structural variations need to be explored systematically to fully appreciate the role of SERINC3 in both health and disease.
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Affiliation(s)
- Mckenzie Tu
- Department of Chemistry and Biochemistry, SUNY Brockport, Brockport, NY, USA
| | - Sarah Saputo
- Department of Chemistry and Biochemistry, SUNY Brockport, Brockport, NY, USA
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15
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Xu S, Zheng Z, Pathak JL, Cheng H, Zhou Z, Chen Y, Wu Q, Wang L, Zeng M, Wu L. The Emerging Role of the Serine Incorporator Protein Family in Regulating Viral Infection. Front Cell Dev Biol 2022; 10:856468. [PMID: 35433679 PMCID: PMC9010877 DOI: 10.3389/fcell.2022.856468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/09/2022] [Indexed: 11/25/2022] Open
Abstract
Serine incorporator (SERINC) proteins 1–5 (SERINC1-5) are involved in the progression of several diseases. SERINC2-4 are carrier proteins that incorporate the polar amino acid serine into membranes to facilitate the synthesis of phosphatidylserine and sphingolipids. SERINC genes are also differentially expressed in tumors. Abnormal expression of SERINC proteins occurs in human cancers of the breast, lung, colon, liver, and various glands, as well as in mouse testes. SERINC proteins also affect cleft lip and palate and nerve-related diseases, such as seizure Parkinsonism and borderline personality. Moreover, SERINC proteins have garnered significant interest as retroviral restriction factors, spurring efforts to define their function and elucidate the mechanisms through which they operate when associated with viruses. Human SERINC proteins possess antiviral potential against human immunodeficiency virus (HIV), SARS-COV-2, murine leukemia virus (MLV), equine infectious anemia virus (EIAV), and hepatitis B virus (HBV). Furthermore, the crystal structure is known, and the critical residues of SERINC5 that act against HIV have been identified. In this review, we discuss the most prevalent mechanisms by which SERINC3 and SERINC5 antagonize viruses and focus on the potential therapeutic applications of SERINC5/3 against HIV.
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Affiliation(s)
- Shaofen Xu
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
| | - Zhichao Zheng
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
- Department of Basic Oral Medicine, Guangzhou Medical University School and Hospital of Stomatology, Guangzhou, China
| | - Janak L. Pathak
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
| | - Haoyu Cheng
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
| | - Ziliang Zhou
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
| | - Yanping Chen
- Center of Emphasis in Infectious Diseases, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX, United States
| | - Qiuyu Wu
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
| | - Lijing Wang
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
- Vascular Biology Research Institute, Guangdong Pharmaceutical University, Guangzhou Higher Education Mega Center, Guangzhou, China
- *Correspondence: Lihong Wu, ; Mingtao Zeng, ; Lijing Wang,
| | - Mingtao Zeng
- Center of Emphasis in Infectious Diseases, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX, United States
- *Correspondence: Lihong Wu, ; Mingtao Zeng, ; Lijing Wang,
| | - Lihong Wu
- Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, China
- Department of Basic Oral Medicine, Guangzhou Medical University School and Hospital of Stomatology, Guangzhou, China
- *Correspondence: Lihong Wu, ; Mingtao Zeng, ; Lijing Wang,
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16
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Schneiter R, Choudhary V. Seipin collaborates with the ER membrane to control the sites of lipid droplet formation. Curr Opin Cell Biol 2022; 75:102070. [PMID: 35306312 PMCID: PMC7615794 DOI: 10.1016/j.ceb.2022.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 02/07/2022] [Accepted: 02/09/2022] [Indexed: 12/24/2022]
Abstract
Most cells store metabolic energy in lipid droplets (LDs). LDs are composed of a hydrophobic core, covered by a phospholipid monolayer, and functionalized by a specific set of proteins. Formation of LDs takes place in the endoplasmic reticulum (ER), where neutral lipid biosynthetic enzymes are located. Recent evidence indicate that this process is confined to specific ER subdomains, where proteins meet to initiate LD assembly. The lipodystrophy protein Seipin, is emerging as a major coordinator of LD biogenesis. Seipin forms a large oligomeric toroidal structure, which traps neutral lipids to promote LD nucleation. Here, we discuss the role of LD biogenesis factors that associate with Seipin to assemble functional LDs.
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Affiliation(s)
- Roger Schneiter
- University of Fribourg, Department of Biology, 1700, Fribourg, Switzerland.
| | - Vineet Choudhary
- All India Institute of Medical Sciences (AIIMS), Department of Biotechnology, New Delhi, 110029, India.
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17
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Cano-Ortiz L, Luedde T, Münk C. HIV-1 restriction by SERINC5. Med Microbiol Immunol 2022; 212:133-140. [PMID: 35333966 PMCID: PMC10085909 DOI: 10.1007/s00430-022-00732-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 03/08/2022] [Indexed: 11/25/2022]
Abstract
Serine incorporator 5 (SERINC5 or SER5) is a multipass transmembrane protein with ill-defined cellular activities. SER5 was recently described as a human immunodeficiency virus 1 (HIV-1) restriction factor capable of inhibiting HIV-1 that does not express its accessory protein Nef (Δ Nef). SER5 incorporated into the viral membrane impairs the entry of HIV-1 by disrupting the fusion between the viral and the plasma membrane after envelope receptor interaction induced the first steps of the fusion process. The mechanisms of how SER5 prevents membrane fusion are not fully understood and viral envelope proteins were identified that escape the SER5-mediated restriction. Primate lentiviruses, such as HIV-1 and simian immunodeficiency viruses (SIVs), use their accessory protein Nef to downregulate SER5 from the plasma membrane by inducing an endocytic pathway. In addition to being directly antiviral, recent data suggest that SER5 is an important adapter protein in innate signaling pathways leading to the induction of inflammatory cytokines. This review discusses the current knowledge about HIV-1 restriction by SER5.
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Affiliation(s)
- Lucía Cano-Ortiz
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Building 23.12.U1.82, Moorenstr. 5, 40225, Düsseldorf, Germany
- Laboratório de Virologia, Departamento de Microbiologia, Imunologia e Parasitologia, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Tom Luedde
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Building 23.12.U1.82, Moorenstr. 5, 40225, Düsseldorf, Germany
| | - Carsten Münk
- Clinic for Gastroenterology, Hepatology, and Infectiology, Medical Faculty, Heinrich-Heine-University Düsseldorf, Building 23.12.U1.82, Moorenstr. 5, 40225, Düsseldorf, Germany.
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18
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Cano-Ortiz L, Gu Q, de Sousa-Pereira P, Zhang Z, Chiapella C, Penda Twizerimana A, Lin C, Cláudia Franco A, VandeWoude S, Luedde T, Baldauf HM, Münk C. Feline Leukemia Virus-B Envelope together with its GlycoGag and Human Immunodeficiency Virus-1 Nef Mediate Resistance to Feline SERINC5. J Mol Biol 2021; 434:167421. [DOI: 10.1016/j.jmb.2021.167421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 11/29/2022]
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19
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The KT Jeang Retrovirology prize 2021: Peter Cherepanov. Retrovirology 2021; 18:28. [PMID: 34565404 PMCID: PMC8474919 DOI: 10.1186/s12977-021-00573-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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20
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Zeng C, Waheed AA, Li T, Yu J, Zheng YM, Yount JS, Wen H, Freed EO, Liu SL. SERINC proteins potentiate antiviral type I IFN production and proinflammatory signaling pathways. Sci Signal 2021; 14:eabc7611. [PMID: 34520227 DOI: 10.1126/scisignal.abc7611] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Cong Zeng
- Center for Retrovirus Research, Ohio State University, Columbus, OH 43210, USA.,Department of Veterinary Biosciences, Ohio State University, Columbus, OH 43210, USA
| | - Abdul A Waheed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, Frederick, MD 21702, USA
| | - Tianliang Li
- Department of Microbial Infection and Immunity, Ohio State University, Columbus, OH 43210, USA
| | - Jingyou Yu
- Center for Retrovirus Research, Ohio State University, Columbus, OH 43210, USA.,Department of Veterinary Biosciences, Ohio State University, Columbus, OH 43210, USA
| | - Yi-Min Zheng
- Center for Retrovirus Research, Ohio State University, Columbus, OH 43210, USA.,Department of Veterinary Biosciences, Ohio State University, Columbus, OH 43210, USA
| | - Jacob S Yount
- Department of Microbial Infection and Immunity, Ohio State University, Columbus, OH 43210, USA
| | - Haitao Wen
- Department of Microbial Infection and Immunity, Ohio State University, Columbus, OH 43210, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, National Cancer Institute, Frederick, Frederick, MD 21702, USA
| | - Shan-Lu Liu
- Center for Retrovirus Research, Ohio State University, Columbus, OH 43210, USA.,Department of Veterinary Biosciences, Ohio State University, Columbus, OH 43210, USA.,Department of Microbial Infection and Immunity, Ohio State University, Columbus, OH 43210, USA.,Viruses and Emerging Pathogens Program, Infectious Diseases Institute, Ohio State University, Columbus, OH 43210, USA
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21
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Aromatic Side Chain at Position 412 of SERINC5 Exerts Restriction Activity toward HIV-1 and Other Retroviruses. J Virol 2021; 95:e0063421. [PMID: 34190600 DOI: 10.1128/jvi.00634-21] [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] [Indexed: 12/24/2022] Open
Abstract
The host transmembrane protein SERINC5 is incorporated into viral particles and restricts infection by certain retroviruses. However, what motif of SERINC5 mediates this process remains elusive. By conducting mutagenesis analyses, we found that the substitution of phenylalanine with alanine at position 412 (F412A) resulted in a >75-fold reduction in SERINC5's restriction function. The F412A substitution also resulted in the loss of SERINC5's function to sensitize HIV-1 neutralization by antibodies recognizing the envelope's membrane proximal region. A series of biochemical analyses revealed that F412A showed steady-state protein expression, localization at the cellular membrane, and incorporation into secreted virus particles to a greater extent than in the wild type. Furthermore, introduction of several amino acid mutations at this position revealed that the aromatic side chains, including phenylalanine, tyrosine, and tryptophan, were required to maintain SERINC5 functions to impair the virus-cell fusion process and virion infectivity. Moreover, the wild-type SERINC5 restricted infection of lentiviruses pseudotyped with envelopes of murine leukemia viruses, simian immunodeficiency virus, and HIV-2, and F412A abrogated this function. Taken together, our results highlight the importance of the aromatic side chain at SERINC5 position 412 to maintain its restriction function against diverse retrovirus envelopes. IMPORTANCE The host protein SERINC5 is incorporated into progeny virions of certain retroviruses and restricts the infectivity of these viruses or sensitizes the envelope glycoprotein to a class of neutralizing antibodies. However, how and which part of SERINC5 engages with the diverse array of retroviral envelopes and exerts its antiretroviral functions remain elusive. During mutagenesis analyses, we eventually found that the single substitution of phenylalanine with alanine, but not with tyrosine or tryptophan, at position 412 (F412A) resulted in the loss of SERINC5's functions toward diverse retroviruses, whereas F412A showed steady-state protein expression, localization at the cellular membrane, and incorporation into progeny virions to a greater extent than the wild type. Results suggest that the aromatic side chain at position 412 of SERINC5 plays a critical role in mediating antiviral functions toward various retroviruses, thus providing additional important information regarding host and retrovirus interaction.
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22
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Chai Q, Li S, Collins MK, Li R, Ahmad I, Johnson SF, Frabutt DA, Yang Z, Shen X, Sun L, Hu J, Hultquist JF, Peterlin BM, Zheng YH. HIV-1 Nef interacts with the cyclin K/CDK13 complex to antagonize SERINC5 for optimal viral infectivity. Cell Rep 2021; 36:109514. [PMID: 34380030 PMCID: PMC8385645 DOI: 10.1016/j.celrep.2021.109514] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 06/17/2021] [Accepted: 07/20/2021] [Indexed: 11/03/2022] Open
Abstract
HIV-1-negative factor (Nef) protein antagonizes serine incorporator 5 (SERINC5) by redirecting this potent restriction factor to the endosomes and lysosomes for degradation. However, the precise mechanism remains unclear. Using affinity purification/mass spectrometry, we identify cyclin K (CycK) and cyclin-dependent kinase 13 (CDK13) as a Nef-associated kinase complex. CycK/CDK13 phosphorylates the serine at position 360 (S360) in SERINC5, which is required for Nef downregulation of SERINC5 from the cell surface and its counteractivity of the SERINC5 antiviral activity. To understand the role of S360 phosphorylation, we generate chimeric proteins between CD8 and SERINC5 to study their response to Nef. Nef not only downregulates but, importantly, also binds to this chimera in an S360-dependent manner. Thus, S360 phosphorylation increases interactions between Nef and SERINC5 and initiates the destruction of SERINC5 by the endocytic machinery.
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Affiliation(s)
- Qingqing Chai
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Sunan Li
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Morgan K Collins
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Rongrong Li
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Iqbal Ahmad
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Silas F Johnson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA; Department of Biology, Hillsdale College, Hillsdale, MI, USA
| | - Dylan A Frabutt
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
| | - Zhichang Yang
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Xiaojing Shen
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, East Lansing, MI, USA
| | - Jian Hu
- Department of Chemistry, Michigan State University, East Lansing, MI, USA; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Judd F Hultquist
- Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - B Matija Peterlin
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA; Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Yong-Hui Zheng
- Harbin Veterinary Research Institute, CAAS-Michigan State University Joint Laboratory of Innate Immunity, State Key Laboratory of Veterinary Biotechnology, Chinese Academy of Agricultural Sciences, Harbin, China; Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA.
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23
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An Amino Acid Polymorphism within the HIV-1 Nef Dileucine Motif Functionally Uncouples Cell Surface CD4 and SERINC5 Downregulation. J Virol 2021; 95:e0058821. [PMID: 34037423 DOI: 10.1128/jvi.00588-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Serine incorporator 5 (SERINC5) reduces the infectivity of progeny HIV-1 virions by incorporating into the outer host-derived viral membrane during egress. To counter SERINC5, the HIV-1 accessory protein Nef triggers SERINC5 internalization by engaging the adaptor protein 2 (AP-2) complex using the [D/E]xxxL[L/I]167 Nef dileucine motif. Nef also engages AP-2 via its dileucine motif to downregulate the CD4 receptor. Although these two Nef functions are related, the mechanisms governing SERINC5 downregulation are incompletely understood. Here, we demonstrate that two primary Nef isolates, referred to as 2410 and 2391 Nef, acquired from acutely HIV-1 infected women from Zimbabwe, both downregulate CD4 from the cell surface. However, only 2410 Nef retains the ability to downregulate cell surface SERINC5. Using a series of Nef chimeras, we mapped the region of 2391 Nef responsible for the functional uncoupling of these two antagonistic pathways to the dileucine motif. Modifications of the first and second x positions of the 2410 Nef dileucine motif to asparagine and aspartic acid residues, respectively (ND164), impaired cell surface SERINC5 downregulation, which resulted in reduced infectious virus yield in the presence of SERINC5. The ND164 mutation additionally partially impaired, but did not completely abrogate, Nef-mediated cell surface CD4 downregulation. Furthermore, the patient infected with HIV-1 encoding 2391 Nef had stable CD4+ T cell counts, whereas infection with HIV-1 encoding 2410 Nef resulted in CD4+ T cell decline and disease progression. IMPORTANCE A contributing factor to HIV-1 persistence is evasion of the host immune response. HIV-1 uses the Nef accessory protein to evade the antiviral roles of the adaptive and intrinsic innate immune responses. Nef targets SERINC5, a restriction factor which potently impairs HIV-1 infection by triggering SERINC5 removal from the cell surface. The molecular determinants underlying this Nef function remain incompletely understood. Recent studies have found a correlation between the extent of Nef-mediated SERINC5 downregulation and the rate of disease progression. Furthermore, single-residue polymorphisms outside the known Nef functional motifs can modulate SERINC5 downregulation. The identification of a naturally occurring Nef polymorphism impairing SERINC5 downregulation in this study supports a link between Nef downregulation of SERINC5 and the rate of plasma CD4+ T cell decline. Moreover, the observed functional impairments of this polymorphism could provide clues to further elucidate unknown aspects of the SERINC5 antagonistic pathway via Nef.
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24
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Molnar S, Wieczorek L, Zemil M, Schulte B, Martinez E, Gift S, Tang L, Streeck H, Gramzinski RA, Michael NL, Joyce G, Polonis VR. Novel monoclonal antibodies to the SERINC5 HIV-1 restriction factor detect endogenous andvirion-associated SERINC5. MAbs 2021; 12:1802187. [PMID: 32835602 PMCID: PMC7531522 DOI: 10.1080/19420862.2020.1802187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
SERINC5 is a multi-pass transmembrane protein that is thought to play a role in serine incorporation during cellular membrane biosynthesis. This protein has also been identified as a human immunodeficiency virus Type 1 (HIV-1) restriction factor. The paucity of monoclonal antibodies (mAbs) against SERINC5 has posed a challenge for the study of the endogenous protein. Here we report the development of novel anti-SERINC5 mAbs that target three distinct loops on the protein. We demonstrate that these SERINC5 mAbs can be used to detect endogenously expressed SERINC5 protein in various cell lines using Western blot, whole-cell ELISA, flow cytometry, and immunocytochemistry. We further show that some of these antibodies can detect SERINC5 that is present in HIV-1 viral stocks. These antibodies will aid in the characterization of the functions and mechanisms of action of SERINC5 in different cell types.
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Affiliation(s)
- Sebastian Molnar
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine , Bethesda, MD, USA
| | - Lindsay Wieczorek
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine , Bethesda, MD, USA
| | - Michelle Zemil
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine , Bethesda, MD, USA
| | - Bianca Schulte
- Institute for Virology, University Hospital Bonn , Bonn, Germany
| | - Elizabeth Martinez
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine , Bethesda, MD, USA
| | - Syna Gift
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine , Bethesda, MD, USA
| | - Lan Tang
- Biologics Department, GenScript , Piscataway, NJ, USA
| | - Hendrik Streeck
- Institute for Virology, University Hospital Bonn , Bonn, Germany
| | - Robert A Gramzinski
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA
| | - Nelson L Michael
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA
| | - Gordon Joyce
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA.,Henry M. Jackson Foundation for the Advancement of Military Medicine , Bethesda, MD, USA
| | - Victoria R Polonis
- Military HIV Research Program, Walter Reed Army Institute of Research , Silver Spring, MD, USA
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25
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Coelacanth SERINC2 Inhibits HIV-1 Infectivity and Is Counteracted by Envelope Glycoprotein from Foamy Virus. J Virol 2021; 95:e0022921. [PMID: 33883219 PMCID: PMC8316019 DOI: 10.1128/jvi.00229-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
SERINC5 restricts nef-defective HIV-1 by affecting early steps of the virus life cycle. Distantly related retroviruses with a wide host range encode virulent factors in response to challenge by SERINC5. However, the evolutionary origins of this antiretroviral activity, its prevalence among the paralogs, and its ability to target retroviruses remain understudied. In agreement with previous studies, we found that four human SERINC paralogs inhibit nef-defective HIV-1, with SERINC2 being an exception. Here, we demonstrate that this lack of activity in human SERINC2 is associated with its post-whole-genome duplication (post-WGD) divergence, as evidenced by the ability of pre-WGD orthologs from Saccharomyces cerevisiae and flies and a post-WGD-proximate SERINC2 from coelacanths to inhibit the virus. Intriguingly, Nef is unable to counter coelacanth SERINC2, indicating that such activity was directed toward other retroviruses found in coelacanths (like foamy viruses). However, foamy virus-derived vectors are intrinsically resistant to the action of SERINC2, and we show that the foamy virus envelope confers this resistance by affecting its steady-state levels. Our study highlights an ancient origin of antiretroviral activity in SERINCs and a hitherto-unknown interaction with a foamy virus. IMPORTANCESERINC5 constitutes a critical barrier to the propagation of retroviruses, as highlighted by parallel emergence of anti-SERINC5 activities among distant retroviral lineages. Therefore, understanding the origin and evolution of these host factors will provide key information about virus-host relationships that can be exploited for future drug development. Here, we show that SERINC5-mediated nef-defective HIV-1 infection inhibition is evolutionarily conserved. SERINC2 from coelacanth restricts HIV-1, and it was functionally adapted to target foamy viruses. Our findings provide insights into the evolutionary origin of antiretroviral activity in the SERINC gene family and uncover the role of SERINCs in shaping the long-term conflicts between retroviruses and their hosts.
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26
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Downregulation of SERINC5 expression in buffy coats of HIV-1-infected patients with detectable or undetectable viral load. Mol Biol Rep 2021; 48:4247-4252. [PMID: 34097204 DOI: 10.1007/s11033-021-06438-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 05/26/2021] [Indexed: 10/21/2022]
Abstract
Among the host restriction factors against HIV, SERINC5 has been described in vitro, but the mRNA level of SERINC5 in vivo has been little studied. We compare SERINC5 expression in subjects with HIV-1 (highly active antiretroviral treatment (HAART) and HAART-naïve) with and without suppression of viral load. A cross-sectional study was performed with 107 individuals distributed as follows: 24 with HAART-naïve and detectable viral load (> 50 copies/mL), 13 with HAART and detectable viral load (> 50 copies/mL), 50 with HAART and undetectable viral load (≤ 50 copies/mL), and 20 without HIV-1. SERINC5 expression in buffy coats was determined using RT-qPCR. The viral load was determined using real-time PCR and the amount of CD4 + and CD8 + T-lymphocytes was measured using flow cytometry. The data were normalized with the Shapiro-Wilk test and the Kruskal-Wallis test was subsequently performed. The relative expression was compared with a T-test and the remaining data with the Mann-Whitney U-test. ANCOVA multiple linear regression analysis was performed between characteristics of patients with SERINC5 expression. The mean and SD of the SERINC5 expression in the three groups with HIV-1 was 0.9 ± 0.2 and without HIV-1 was 1.7 ± 0.14 (P < 0.001). Multiple linear regression did not show the participation of CD4 +, CD8 + , viral load, infection time, or treatment time. No differences in the SERINC5 expression were found among the studied groups of patients with HIV-1. When comparing the groups with and without HIV-1 infection, SERINC5 was downregulation in the HIV-1 groups.
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27
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Structure and function at the lipid-protein interface of a pentameric ligand-gated ion channel. Proc Natl Acad Sci U S A 2021; 118:2100164118. [PMID: 34083441 DOI: 10.1073/pnas.2100164118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although it has long been proposed that membrane proteins may contain tightly bound lipids, their identity, the structure of their binding sites, and their functional and structural relevance have remained elusive. To some extent, this is because tightly bound lipids are often located at the periphery of proteins, where the quality of density maps is usually poorer, and because they may be outcompeted by detergent molecules used during standard purification procedures. As a step toward characterizing natively bound lipids in the superfamily of pentameric ligand-gated ion channels (pLGICs), we applied single-particle cryogenic electron microscopy to fragments of native membrane obtained in the complete absence of detergent-solubilization steps. Because of the heterogeneous lipid composition of membranes in the secretory pathway of eukaryotic cells, we chose to study a bacterial pLGIC (ELIC) expressed in Escherichia coli's inner membrane. We obtained a three-dimensional reconstruction of unliganded ELIC (2.5-Å resolution) that shows clear evidence for two types of tightly bound lipid at the protein-bulk-membrane interface. One of them was consistent with a "regular" diacylated phospholipid, in the cytoplasmic leaflet, whereas the other one was consistent with the tetra-acylated structure of cardiolipin, in the periplasmic leaflet. Upon reconstitution in E. coli polar-lipid bilayers, ELIC retained the functional properties characteristic of members of this superfamily, and thus, the fitted atomic model is expected to represent the (long-debated) unliganded-closed, "resting" conformation of this ion channel. Notably, the addition of cardiolipin to phosphatidylcholine membranes restored the ion-channel activity that is largely lost in phosphatidylcholine-only bilayers.
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28
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Alli-Balogun GO, Levine TP. Fungal Ice2p is in the same superfamily as SERINCs, restriction factors for HIV and other viruses. Proteins 2021; 89:1240-1250. [PMID: 33982326 DOI: 10.1002/prot.26145] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Accepted: 05/10/2021] [Indexed: 12/13/2022]
Abstract
Ice2p is an integral endoplasmic reticulum (ER) membrane protein in budding yeast S. cerevisiae named ICE because it is required for Inheritance of Cortical ER. Ice2p has also been reported to be involved in an ER metabolic branch-point that regulates the flux of lipid either to be stored in lipid droplets or to be used as membrane components. Alternately, Ice2p has been proposed to act as a tether that physically bridges the ER at contact sites with both lipid droplets and the plasma membrane via a long loop on the protein's cytoplasmic face that contains multiple predicted amphipathic helices. Here we carried out a bioinformatic analysis to increase understanding of Ice2p. First, regarding topology, we found that diverse members of the fungal Ice2 family have 10 transmembrane helices (TMHs), which places the long loop on the exofacial face of Ice2p, where it cannot form inter-organelle bridges. Second, we identified Ice2p as a full-length homolog of SERINC (serine incorporator), a family of proteins with 10 TMHs found universally in eukaryotes. Since SERINCs are potent restriction factors for HIV and other viruses, study of Ice2p may reveal functions or mechanisms that shed light on viral restriction by SERINCs.
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Affiliation(s)
| | - Tim P Levine
- UCL Institute of Ophthalmology, University College London, London, UK
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29
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Arista-Romero M, Pujals S, Albertazzi L. Towards a Quantitative Single Particle Characterization by Super Resolution Microscopy: From Virus Structures to Antivirals Design. Front Bioeng Biotechnol 2021; 9:647874. [PMID: 33842446 PMCID: PMC8033170 DOI: 10.3389/fbioe.2021.647874] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 03/08/2021] [Indexed: 12/15/2022] Open
Abstract
In the last year the COVID19 pandemic clearly illustrated the potential threat that viruses pose to our society. The characterization of viral structures and the identification of key proteins involved in each step of the cycle of infection are crucial to develop treatments. However, the small size of viruses, invisible under conventional fluorescence microscopy, make it difficult to study the organization of protein clusters within the viral particle. The applications of super-resolution microscopy have skyrocketed in the last years, converting this group into one of the leading techniques to characterize viruses and study the viral infection in cells, breaking the diffraction limit by achieving resolutions up to 10 nm using conventional probes such as fluorescent dyes and proteins. There are several super-resolution methods available and the selection of the right one it is crucial to study in detail all the steps involved in the viral infection, quantifying and creating models of infection for relevant viruses such as HIV-1, Influenza, herpesvirus or SARS-CoV-1. Here we review the use of super-resolution microscopy (SRM) to study all steps involved in the viral infection and antiviral design. In light of the threat of new viruses, these studies could inspire future assays to unveil the viral mechanism of emerging viruses and further develop successful antivirals against them.
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Affiliation(s)
- Maria Arista-Romero
- Nanoscopy for Nanomedicine Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Silvia Pujals
- Nanoscopy for Nanomedicine Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Department of Electronics and Biomedical Engineering, Faculty of Physics, Universitat de Barcelona, Barcelona, Spain
| | - Lorenzo Albertazzi
- Nanoscopy for Nanomedicine Group, Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Department of Biomedical Engineering, Institute for Complex Molecular Systems (ICMS), Eindhoven University of Technology, Eindhoven, Netherlands
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30
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Selective Disruption of SERINC5 Antagonism by Nef Impairs SIV Replication in Primary CD4 + T Cells. J Virol 2021; 95:JVI.01911-20. [PMID: 33504599 PMCID: PMC8103682 DOI: 10.1128/jvi.01911-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Nef proteins of HIV-1 and SIV enhance viral infectivity by preventing the incorporation of the multipass transmembrane protein serine incorporator 5 (SERINC5), and to a lesser extent SERINC3, into virions. In addition to counteracting SERINCs, SIV Nef also downmodulates several transmembrane proteins from the surface of virus-infected cells, including simian tetherin, CD4 and MHC class I (MHC I) molecules. From a systematic analysis of alanine substitutions throughout the SIVmac239 Nef protein, we identified residues that are required to counteract SERINC5. This information was used to engineer an infectious molecular clone of SIV (SIVmac239nef AV), which differs by two amino acids in the N-terminal domain of Nef that make the virus sensitive to SERINC5 while retaining other activities of Nef. SIVmac239nef AV downmodulates CD3, CD4, MHC I and simian tetherin, but cannot counteract SERINC5. In primary rhesus macaque CD4+ T cells, SIVmac239nef AV exhibits impaired infectivity and replication compared to wild-type SIVmac239. These results demonstrate that SERINC5 antagonism can be separated from other Nef functions and reveal the impact of SERINC5 on lentiviral replication.Importance: SERINC5, a multipass transmembrane protein, is incorporated into retroviral particles during assembly. This leads to a reduction of particle infectivity by inhibiting virus fusion with the target cell membrane. The Nef proteins of HIV-1 and SIV enhance viral infectivity by preventing the incorporation of SERINC5 into virions. However, the relevance of this restriction factor in viral replication has not been elucidated. Here we report a systematic mapping of Nef residues required for SERINC5 antagonism. Counter screens for three other functions of Nef helped identify two residues in the N-terminal domain of Nef, which when mutated make Nef selectively susceptible to SERINC5. Since Nef is multi-functional, genetic separation of SERINC5 antagonism from its other functions affords comparison of the replication of isogenic viruses that are or are not sensitive to SERINC5. Such a strategy revealed the impact of SERINC5 on SIV replication in primary rhesus macaque CD4+ T-cells.
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31
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Rosa A, Pye VE, Graham C, Muir L, Seow J, Ng KW, Cook NJ, Rees-Spear C, Parker E, dos Santos MS, Rosadas C, Susana A, Rhys H, Nans A, Masino L, Roustan C, Christodoulou E, Ulferts R, Wrobel A, Short CE, Fertleman M, Sanders RW, Heaney J, Spyer M, Kjær S, Riddell A, Malim MH, Beale R, MacRae JI, Taylor GP, Nastouli E, van Gils MJ, Rosenthal PB, Pizzato M, McClure MO, Tedder RS, Kassiotis G, McCoy LE, Doores KJ, Cherepanov P. SARS-CoV-2 recruits a haem metabolite to evade antibody immunity. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2021:2021.01.21.21249203. [PMID: 33532784 PMCID: PMC7852234 DOI: 10.1101/2021.01.21.21249203] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The coronaviral spike is the dominant viral antigen and the target of neutralizing antibodies. We show that SARS-CoV-2 spike binds biliverdin and bilirubin, the tetrapyrrole products of haem metabolism, with nanomolar affinity. Using cryo-electron microscopy and X-ray crystallography we mapped the tetrapyrrole interaction pocket to a deep cleft on the spike N-terminal domain (NTD). At physiological concentrations, biliverdin significantly dampened the reactivity of SARS-CoV-2 spike with immune sera and inhibited a subset of neutralizing antibodies. Access to the tetrapyrrole-sensitive epitope is gated by a flexible loop on the distal face of the NTD. Accompanied by profound conformational changes in the NTD, antibody binding requires relocation of the gating loop, which folds into the cleft vacated by the metabolite. Our results indicate that the virus co-opts the haem metabolite for the evasion of humoral immunity via allosteric shielding of a sensitive epitope and demonstrate the remarkable structural plasticity of the NTD.
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Affiliation(s)
- Annachiara Rosa
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK
| | - Valerie E. Pye
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK
| | - Carl Graham
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, UK
| | - Luke Muir
- Institute of Immunity and Transplantation, Division of Infection and Immunity, University College London, London, UK
| | - Jeffrey Seow
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, UK
| | - Kevin W. Ng
- Retroviral Immunology Laboratory, The Francis Crick Institute, London, UK
| | - Nicola J. Cook
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK
| | - Chloe Rees-Spear
- Institute of Immunity and Transplantation, Division of Infection and Immunity, University College London, London, UK
| | - Eleanor Parker
- Department of Infectious Disease, St-Mary’s Campus, Imperial College London, UK
| | | | - Carolina Rosadas
- Department of Infectious Disease, St-Mary’s Campus, Imperial College London, UK
| | - Alberto Susana
- Department of Cellular, Computational and Integrative Biology, University of Trento, Italy
| | - Hefin Rhys
- Flow Cytometry Science and Technology Platform, The Francis Crick Institute, London, UK
| | - Andrea Nans
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK
| | - Laura Masino
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK
| | - Chloe Roustan
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK
| | | | - Rachel Ulferts
- Cell Biology of Infection Laboratory, The Francis Crick Institute, London, UK
| | - Antoni Wrobel
- Structural Biology of Disease Processes Laboratory, The Francis Crick Institute, London, UK
| | - Charlotte-Eve Short
- Department of Infectious Disease, St-Mary’s Campus, Imperial College London, UK
| | | | - Rogier W. Sanders
- Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam Institute for Infection and Immunity, Amsterdam, Netherlands
- Weill Medical College of Cornell University, New York, US
| | - Judith Heaney
- Advanced Pathogen Diagnostic Unit, University College London Hospitals NHS Foundation Trust, London, UK
- Crick COVID-19 Consortium, The Francis Crick Institute, London, UK
| | - Moira Spyer
- Advanced Pathogen Diagnostic Unit, University College London Hospitals NHS Foundation Trust, London, UK
- Crick COVID-19 Consortium, The Francis Crick Institute, London, UK
- Department of Infection, Immunity and Inflammation, UCL Great Ormond Street Institute of Child Health
| | - Svend Kjær
- Structural Biology Science Technology Platform, The Francis Crick Institute, London, UK
| | - Andy Riddell
- Flow Cytometry Science and Technology Platform, The Francis Crick Institute, London, UK
| | - Michael H. Malim
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, UK
| | - Rupert Beale
- Cell Biology of Infection Laboratory, The Francis Crick Institute, London, UK
| | - James I. MacRae
- Metabolomics Science Technology Platform, The Francis Crick Institute, London, UK
| | - Graham P. Taylor
- Department of Infectious Disease, St-Mary’s Campus, Imperial College London, UK
| | - Eleni Nastouli
- Advanced Pathogen Diagnostic Unit, University College London Hospitals NHS Foundation Trust, London, UK
- Crick COVID-19 Consortium, The Francis Crick Institute, London, UK
- Department of Infection, Immunity and Inflammation, UCL Great Ormond Street Institute of Child Health
| | - Marit J. van Gils
- Department of Medical Microbiology, Amsterdam UMC, University of Amsterdam, Amsterdam Institute for Infection and Immunity, Amsterdam, Netherlands
| | - Peter B. Rosenthal
- Structural Biology of Cells and Viruses Laboratory, The Francis Crick Institute, London, UK
| | - Massimo Pizzato
- Department of Cellular, Computational and Integrative Biology, University of Trento, Italy
| | - Myra O. McClure
- Department of Infectious Disease, St-Mary’s Campus, Imperial College London, UK
| | - Richard S. Tedder
- Department of Infectious Disease, St-Mary’s Campus, Imperial College London, UK
| | - George Kassiotis
- Retroviral Immunology Laboratory, The Francis Crick Institute, London, UK
- Department of Infectious Disease, St-Mary’s Campus, Imperial College London, UK
| | - Laura E. McCoy
- Institute of Immunity and Transplantation, Division of Infection and Immunity, University College London, London, UK
| | - Katie J. Doores
- Department of Infectious Diseases, School of Immunology & Microbial Sciences, King’s College London, UK
| | - Peter Cherepanov
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London, UK
- Department of Infectious Disease, St-Mary’s Campus, Imperial College London, UK
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32
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Ng KW, Faulkner N, Cornish GH, Rosa A, Harvey R, Hussain S, Ulferts R, Earl C, Wrobel AG, Benton DJ, Roustan C, Bolland W, Thompson R, Agua-Doce A, Hobson P, Heaney J, Rickman H, Paraskevopoulou S, Houlihan CF, Thomson K, Sanchez E, Shin GY, Spyer MJ, Joshi D, O'Reilly N, Walker PA, Kjaer S, Riddell A, Moore C, Jebson BR, Wilkinson M, Marshall LR, Rosser EC, Radziszewska A, Peckham H, Ciurtin C, Wedderburn LR, Beale R, Swanton C, Gandhi S, Stockinger B, McCauley J, Gamblin SJ, McCoy LE, Cherepanov P, Nastouli E, Kassiotis G. Preexisting and de novo humoral immunity to SARS-CoV-2 in humans. Science 2020; 370:1339-1343. [PMID: 33159009 DOI: 10.1101/2020.05.14] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/29/2020] [Indexed: 05/20/2023]
Abstract
Zoonotic introduction of novel coronaviruses may encounter preexisting immunity in humans. Using diverse assays for antibodies recognizing SARS-CoV-2 proteins, we detected preexisting humoral immunity. SARS-CoV-2 spike glycoprotein (S)-reactive antibodies were detectable using a flow cytometry-based method in SARS-CoV-2-uninfected individuals and were particularly prevalent in children and adolescents. They were predominantly of the immunoglobulin G (IgG) class and targeted the S2 subunit. By contrast, SARS-CoV-2 infection induced higher titers of SARS-CoV-2 S-reactive IgG antibodies targeting both the S1 and S2 subunits, and concomitant IgM and IgA antibodies, lasting throughout the observation period. SARS-CoV-2-uninfected donor sera exhibited specific neutralizing activity against SARS-CoV-2 and SARS-CoV-2 S pseudotypes. Distinguishing preexisting and de novo immunity will be critical for our understanding of susceptibility to and the natural course of SARS-CoV-2 infection.
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Affiliation(s)
- Kevin W Ng
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK
| | - Nikhil Faulkner
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK
| | | | - Annachiara Rosa
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Ruth Harvey
- Worldwide Influenza Centre, The Francis Crick Institute, London NW1 1AT, UK
| | - Saira Hussain
- Worldwide Influenza Centre, The Francis Crick Institute, London NW1 1AT, UK
| | - Rachel Ulferts
- Cell Biology of Infection Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Christopher Earl
- Signalling and Structural Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Antoni G Wrobel
- Structural Biology of Disease Processes Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Donald J Benton
- Structural Biology of Disease Processes Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Chloe Roustan
- Structural Biology STP, The Francis Crick Institute, London NW1 1AT, UK
| | - William Bolland
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK
| | - Rachael Thompson
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK
| | - Ana Agua-Doce
- Flow Cytometry STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Philip Hobson
- Flow Cytometry STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Judith Heaney
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | - Hannah Rickman
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | | | - Catherine F Houlihan
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
- Division of Infection and Immunity, University College London (UCL), London WC1E 6BT, UK
| | - Kirsty Thomson
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | - Emilie Sanchez
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | - Gee Yen Shin
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | - Moira J Spyer
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
- Department of Population, Policy and Practice, Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Dhira Joshi
- Peptide Chemistry, The Francis Crick Institute, London NW1 1AT, UK
| | - Nicola O'Reilly
- Peptide Chemistry, The Francis Crick Institute, London NW1 1AT, UK
| | - Philip A Walker
- Structural Biology STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Svend Kjaer
- Structural Biology STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Andrew Riddell
- Flow Cytometry STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Catherine Moore
- Public Health Wales, University Hospital of Wales, Cardiff CF14 4XW, UK
| | - Bethany R Jebson
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- UCL Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Meredyth Wilkinson
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- UCL Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Lucy R Marshall
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- UCL Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Elizabeth C Rosser
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- Centre for Rheumatology Research, Division of Medicine, UCL, London, WC1E 6BT, UK
| | - Anna Radziszewska
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- Centre for Rheumatology Research, Division of Medicine, UCL, London, WC1E 6BT, UK
| | - Hannah Peckham
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- Centre for Rheumatology Research, Division of Medicine, UCL, London, WC1E 6BT, UK
| | - Coziana Ciurtin
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- Centre for Rheumatology Research, Division of Medicine, UCL, London, WC1E 6BT, UK
| | - Lucy R Wedderburn
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- UCL Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Rupert Beale
- Cell Biology of Infection Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Charles Swanton
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Sonia Gandhi
- Neurodegeneration Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | | | - John McCauley
- Worldwide Influenza Centre, The Francis Crick Institute, London NW1 1AT, UK
| | - Steve J Gamblin
- Structural Biology of Disease Processes Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Laura E McCoy
- Division of Infection and Immunity, University College London (UCL), London WC1E 6BT, UK.
| | - Peter Cherepanov
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
| | - Eleni Nastouli
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK.
- Department of Population, Policy and Practice, Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - George Kassiotis
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK.
- Department of Medicine, Faculty of Medicine, Imperial College London, London W2 1PG, UK
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33
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Ng KW, Faulkner N, Cornish GH, Rosa A, Harvey R, Hussain S, Ulferts R, Earl C, Wrobel AG, Benton DJ, Roustan C, Bolland W, Thompson R, Agua-Doce A, Hobson P, Heaney J, Rickman H, Paraskevopoulou S, Houlihan CF, Thomson K, Sanchez E, Shin GY, Spyer MJ, Joshi D, O'Reilly N, Walker PA, Kjaer S, Riddell A, Moore C, Jebson BR, Wilkinson M, Marshall LR, Rosser EC, Radziszewska A, Peckham H, Ciurtin C, Wedderburn LR, Beale R, Swanton C, Gandhi S, Stockinger B, McCauley J, Gamblin SJ, McCoy LE, Cherepanov P, Nastouli E, Kassiotis G. Preexisting and de novo humoral immunity to SARS-CoV-2 in humans. Science 2020; 370:1339-1343. [PMID: 33159009 PMCID: PMC7857411 DOI: 10.1126/science.abe1107] [Citation(s) in RCA: 589] [Impact Index Per Article: 147.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/29/2020] [Indexed: 12/11/2022]
Abstract
Zoonotic introduction of novel coronaviruses may encounter preexisting immunity in humans. Using diverse assays for antibodies recognizing SARS-CoV-2 proteins, we detected preexisting humoral immunity. SARS-CoV-2 spike glycoprotein (S)-reactive antibodies were detectable using a flow cytometry-based method in SARS-CoV-2-uninfected individuals and were particularly prevalent in children and adolescents. They were predominantly of the immunoglobulin G (IgG) class and targeted the S2 subunit. By contrast, SARS-CoV-2 infection induced higher titers of SARS-CoV-2 S-reactive IgG antibodies targeting both the S1 and S2 subunits, and concomitant IgM and IgA antibodies, lasting throughout the observation period. SARS-CoV-2-uninfected donor sera exhibited specific neutralizing activity against SARS-CoV-2 and SARS-CoV-2 S pseudotypes. Distinguishing preexisting and de novo immunity will be critical for our understanding of susceptibility to and the natural course of SARS-CoV-2 infection.
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Affiliation(s)
- Kevin W Ng
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK
| | - Nikhil Faulkner
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK
| | | | - Annachiara Rosa
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Ruth Harvey
- Worldwide Influenza Centre, The Francis Crick Institute, London NW1 1AT, UK
| | - Saira Hussain
- Worldwide Influenza Centre, The Francis Crick Institute, London NW1 1AT, UK
| | - Rachel Ulferts
- Cell Biology of Infection Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Christopher Earl
- Signalling and Structural Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Antoni G Wrobel
- Structural Biology of Disease Processes Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Donald J Benton
- Structural Biology of Disease Processes Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Chloe Roustan
- Structural Biology STP, The Francis Crick Institute, London NW1 1AT, UK
| | - William Bolland
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK
| | - Rachael Thompson
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK
| | - Ana Agua-Doce
- Flow Cytometry STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Philip Hobson
- Flow Cytometry STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Judith Heaney
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | - Hannah Rickman
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | | | - Catherine F Houlihan
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
- Division of Infection and Immunity, University College London (UCL), London WC1E 6BT, UK
| | - Kirsty Thomson
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | - Emilie Sanchez
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | - Gee Yen Shin
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
| | - Moira J Spyer
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK
- Department of Population, Policy and Practice, Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Dhira Joshi
- Peptide Chemistry, The Francis Crick Institute, London NW1 1AT, UK
| | - Nicola O'Reilly
- Peptide Chemistry, The Francis Crick Institute, London NW1 1AT, UK
| | - Philip A Walker
- Structural Biology STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Svend Kjaer
- Structural Biology STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Andrew Riddell
- Flow Cytometry STP, The Francis Crick Institute, London NW1 1AT, UK
| | - Catherine Moore
- Public Health Wales, University Hospital of Wales, Cardiff CF14 4XW, UK
| | - Bethany R Jebson
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- UCL Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Meredyth Wilkinson
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- UCL Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Lucy R Marshall
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- UCL Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Elizabeth C Rosser
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- Centre for Rheumatology Research, Division of Medicine, UCL, London, WC1E 6BT, UK
| | - Anna Radziszewska
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- Centre for Rheumatology Research, Division of Medicine, UCL, London, WC1E 6BT, UK
| | - Hannah Peckham
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- Centre for Rheumatology Research, Division of Medicine, UCL, London, WC1E 6BT, UK
| | - Coziana Ciurtin
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- Centre for Rheumatology Research, Division of Medicine, UCL, London, WC1E 6BT, UK
| | - Lucy R Wedderburn
- Centre for Adolescent Rheumatology Versus Arthritis at UCL, UCLH, Great Ormond Street Hospital (GOSH), London WC1N 3JH, UK
- UCL Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - Rupert Beale
- Cell Biology of Infection Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Charles Swanton
- Cancer Evolution and Genome Instability Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Sonia Gandhi
- Neurodegeneration Biology Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | | | - John McCauley
- Worldwide Influenza Centre, The Francis Crick Institute, London NW1 1AT, UK
| | - Steve J Gamblin
- Structural Biology of Disease Processes Laboratory, The Francis Crick Institute, London NW1 1AT, UK
| | - Laura E McCoy
- Division of Infection and Immunity, University College London (UCL), London WC1E 6BT, UK.
| | - Peter Cherepanov
- Chromatin Structure and Mobile DNA Laboratory, The Francis Crick Institute, London NW1 1AT, UK.
| | - Eleni Nastouli
- University College London Hospitals (UCLH) NHS Trust, London NW1 2BU, UK.
- Department of Population, Policy and Practice, Great Ormond Street Institute for Child Health (ICH), UCL, London WC1N 1EH, UK
| | - George Kassiotis
- Retroviral Immunology, The Francis Crick Institute, London NW1 1AT, UK.
- Department of Medicine, Faculty of Medicine, Imperial College London, London W2 1PG, UK
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34
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Qiu X, Eke IE, Johnson SF, Ding C, Zheng YH. Proteasomal degradation of human SERINC4: A potent host anti-HIV-1 factor that is antagonized by nef. ACTA ACUST UNITED AC 2020; 1. [PMID: 33521797 PMCID: PMC7842267 DOI: 10.1016/j.crviro.2020.100002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The serine incorporator (SERINC) protein family has five paralogous members with 9–11 transmembrane domains. SERINC5 is a potent host restriction factor and antagonized by HIV-1 Nef and two other retroviral accessory proteins via the lysosomal degradation pathway. Here, we investigated human SERINC4 expression and antiviral mechanisms. Unlike its four paralogs, human SERINC4 is subjected to proteasome-mediated turnover, resulting in ~250-fold lower expression than SERINC5. However, when expression was normalized, human SERINC4 restricted HIV-1 replication as effectively as SERINC5, and SERINC4 was also antagonized by Nef via the lysosomal pathway. Although SERINC4 proteins are conserved within primates or rodents, their N-terminal regions are highly variable across species. Interestingly, unlike human SERINC4, murine SERINC4 was stably expressed but had a very poor antiviral activity. We created stable SERINC4 chimeras by replacing the N-terminal region and found that the 1–34 and 35–92 amino acids determine SERINC4 antiviral activity or protein expression, respectively. Using these chimeras, we demonstrate that SERINC4 is incorporated into HIV-1 virions and restricts Tier 1 HIV-1 more effectively than Tier 3 HIV-1. Importantly, SERINC4 increases HIV-1 sensitivity to broadly neutralizing antibodies. Thus, human SERINC4 strongly restricts HIV-1 replication when it is overexpressed, which reflects a potential antiviral activity of this gene product under physiological conditions.
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Affiliation(s)
- Xusheng Qiu
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Ifeanyichukwu E. Eke
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
| | - Silas F. Johnson
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
- Department of Biology, Hillsdale College, Hillsdale, MI, 49242, USA
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Yong-Hui Zheng
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
- Corresponding author. (Y.-H. Zheng)
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35
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Ward AE, Kiessling V, Pornillos O, White JM, Ganser-Pornillos BK, Tamm LK. HIV-cell membrane fusion intermediates are restricted by Serincs as revealed by cryo-electron and TIRF microscopy. J Biol Chem 2020; 295:15183-15195. [PMID: 32788212 PMCID: PMC7650252 DOI: 10.1074/jbc.ra120.014466] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/19/2020] [Indexed: 12/13/2022] Open
Abstract
To enter a cell and establish infection, HIV must first fuse its lipid envelope with the host cell plasma membrane. Whereas the process of HIV membrane fusion can be tracked by fluorescence microscopy, the 3D configuration of proteins and lipids at intermediate steps can only be resolved with cryo-electron tomography (cryoET). However, cryoET of whole cells is technically difficult. To overcome this problem, we have adapted giant plasma membrane vesicles (or blebs) from native cell membranes expressing appropriate receptors as targets for fusion with HIV envelope glycoprotein-expressing pseudovirus particles with and without Serinc host restriction factors. The fusion behavior of these particles was probed by TIRF microscopy on bleb-derived supported membranes. Timed snapshots of fusion of the same particles with blebs were examined by cryo-ET. The combination of these methods allowed us to characterize the structures of various intermediates on the fusion pathway and showed that when Serinc3 or Serinc5 (but not Serinc2) were present, later fusion products were more prevalent, suggesting that Serinc3/5 act at multiple steps to prevent progression to full fusion. In addition, the antifungal amphotericin B reversed Serinc restriction, presumably by intercalation into the fusing membranes. Our results provide a highly detailed view of Serinc restriction of HIV-cell membrane fusion and thus extend current structural and functional information on Serinc as a lipid-binding protein.
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Affiliation(s)
- Amanda E Ward
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Volker Kiessling
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Judith M White
- Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA.
| | - Lukas K Tamm
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia, USA; Department of Cell Biology, University of Virginia School of Medicine, Charlottesville, Virginia, USA.
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36
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Featherstone A, Aiken C. SERINC5 Inhibits HIV-1 Infectivity by Altering the Conformation of gp120 on HIV-1 Particles. J Virol 2020; 94:e00594-20. [PMID: 32796070 PMCID: PMC7527050 DOI: 10.1128/jvi.00594-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 08/03/2020] [Indexed: 01/25/2023] Open
Abstract
SERINC5 is a 10-transmembrane-domain cellular protein that is incorporated into budding HIV-1 particles and reduces HIV-1 infectivity by inhibiting virus-cell fusion. HIV-1 susceptibility to SERINC5 is determined by sequences in the viral Env glycoprotein gp120, and the antiviral effect of SERINC5 is counteracted by the viral accessory protein Nef. While the precise mechanism by which SERINC5 inhibits HIV-1 infectivity is unclear, previous studies have suggested that SERINC5 affects Env conformation. To define the effects of SERINC5 on Env conformation, we quantified the binding of HIV-1 particles to immobilized Env-specific monoclonal antibodies. We observed that SERINC5 reduced the binding of HIV-1 particles bearing a SERINC5-susceptible Env to antibodies that recognize the V3 loop, a soluble CD4 (sCD4)-induced epitope, and an N-linked glycan. In contrast, SERINC5 did not alter the capture of HIV-1 particles bearing the SERINC5-resistant Env protein. Moreover, the effect of SERINC5 on antibody-dependent virus capture was abrogated by Nef expression. Our results indicate that SERINC5 inhibits HIV-1 infectivity by altering the conformation of gp120 on virions and/or physical masking of specific HIV-1 Env epitopes.IMPORTANCE SERINC5 is a host cell protein that inhibits the infectivity of HIV-1 by a novel and poorly understood mechanism. Here, we provide evidence that the SERINC5 protein alters the conformation of the HIV-1 Env proteins and that this action is correlated with SERINC5's ability to inhibit HIV-1 infectivity. Defining the specific effects of SERINC5 on the HIV-1 glycoprotein conformation may be useful for designing new antiviral strategies targeting Env.
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Affiliation(s)
- Austin Featherstone
- Vanderbilt University Medical Center, Department of Pathology, Microbiology and Immunology, Nashville, Tennessee, USA
| | - Christopher Aiken
- Vanderbilt University Medical Center, Department of Pathology, Microbiology and Immunology, Nashville, Tennessee, USA
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37
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Chen YC, Sood C, Marin M, Aaron J, Gratton E, Salaita K, Melikyan GB. Super-Resolution Fluorescence Imaging Reveals That Serine Incorporator Protein 5 Inhibits Human Immunodeficiency Virus Fusion by Disrupting Envelope Glycoprotein Clusters. ACS NANO 2020; 14:10929-10943. [PMID: 32441921 PMCID: PMC8274448 DOI: 10.1021/acsnano.0c02699] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Serine incorporator protein 5 (SERINC5) is the host antiretroviral factor that reduces HIV-1 infectivity by incorporating into virions and inhibiting the envelope glycoprotein (Env) mediated virus fusion with target cells. We and others have shown that SERINC5 incorporation into virions alters the Env structure and sensitizes the virus to broadly neutralizing antibodies targeting cryptic Env epitopes. We have also found that SERINC5 accelerates the loss of Env function over time compared to control viruses. However, the exact mechanism by which SERINC5 inhibits HIV-1 fusion is not understood. Here, we utilized 2D and 3D super-resolution microscopy to examine the effect of SERINC5 on the distribution of Env glycoproteins on single HIV-1 particles. We find that, in agreement with a previous report, Env glycoproteins form clusters on the surface of mature virions. Importantly, incorporation of SERINC5, but not SERINC2, which lacks antiviral activity, disrupted Env clusters without affecting the overall Env content. We also show that SERINC5 and SERINC2 also form clusters on single virions. Unexpectedly, Env and SERINC molecules exhibited poor codistribution on virions, as evidenced by much greater Env-SERINC pairwise distances compared to Env-Env distances. This observation is inconsistent with the previously reported interaction between Env and SERINC5 and suggests an indirect effect of SERINC5 on Env cluster formation. Collectively, our results reveal a multifaceted mechanism of SERINC5-mediated restriction of HIV-1 fusion that, aside from the effects on individual Env trimers, involves disruption of Env clusters, which likely serve as sites of viral fusion with target cells.
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Affiliation(s)
- Yen-Cheng Chen
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Chetan Sood
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Mariana Marin
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jesse Aaron
- Janelia Research Campus, Ashburn, VA, 20147, USA
| | - Enrico Gratton
- Laboratory for Fluorescence Dynamics, University of California Irvine, Irvine, CA 92617, USA
| | - Khalid Salaita
- Department of Chemistry, Emory University, Atlanta, GA 30322, USA
| | - Gregory B. Melikyan
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
- Children’s Healthcare of Atlanta, Atlanta, GA 30322, USA
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38
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Staudt RP, Smithgall TE. Nef homodimers down-regulate SERINC5 by AP-2-mediated endocytosis to promote HIV-1 infectivity. J Biol Chem 2020; 295:15540-15552. [PMID: 32873704 DOI: 10.1074/jbc.ra120.014668] [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: 06/02/2020] [Revised: 08/24/2020] [Indexed: 12/13/2022] Open
Abstract
SERINC5 is a multipass intrinsic membrane protein that suppresses HIV-1 infectivity when incorporated into budding virions. The HIV-1 Nef virulence factor prevents viral incorporation of SERINC5 by triggering its down-regulation from the producer cell membrane through an AP-2-dependent endolysosomal pathway. However, the mechanistic basis for SERINC5 down-regulation by Nef remains elusive. Here we demonstrate that Nef homodimers are important for SERINC5 down-regulation, trafficking to late endosomes, and exclusion from newly synthesized viral particles. Based on previous X-ray crystal structures, we mutated three conserved residues in the Nef dimer interface (Leu112, Tyr115, and Phe121) and demonstrated attenuated homodimer formation in a cell-based fluorescence complementation assay. Point mutations at each position reduced the infectivity of HIV-1 produced from transfected 293T cells, the Jurkat TAg T-cell line, and donor mononuclear cells in a SERINC5-dependent manner. In SERINC5-transfected 293T cells, virion incorporation of SERINC5 was increased by dimerization-defective Nef mutants, whereas down-regulation of SERINC5 from the membrane of transfected Jurkat cells by these mutants was significantly reduced. Nef dimer interface mutants also failed to trigger internalization of SERINC5 and localization to Rab7+ late endosomes in T cells. Importantly, fluorescence complementation assays demonstrated that dimerization-defective Nef mutants retained interaction with both SERINC5 and AP-2. These results show that down-regulation of SERINC5 and subsequent enhancement of viral infectivity require Nef homodimers and support a mechanism by which the Nef dimer bridges SERINC5 to AP-2 for endocytosis. Pharmacological disruption of Nef homodimers may control HIV-1 infectivity and viral spread by enhancing virion incorporation of SERINC5.
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Affiliation(s)
- Ryan P Staudt
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh, School of Medicine, Pittsburgh, Pennsylvania, USA.
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39
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Jin SW, Mwimanzi FM, Mann JK, Bwana MB, Lee GQ, Brumme CJ, Hunt PW, Martin JN, Bangsberg DR, Ndung’u T, Brumme ZL, Brockman MA. Variation in HIV-1 Nef function within and among viral subtypes reveals genetically separable antagonism of SERINC3 and SERINC5. PLoS Pathog 2020; 16:e1008813. [PMID: 32925973 PMCID: PMC7515180 DOI: 10.1371/journal.ppat.1008813] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 09/24/2020] [Accepted: 07/15/2020] [Indexed: 12/14/2022] Open
Abstract
HIV Nef counteracts cellular host restriction factors SERINC3 and SERINC5, but our understanding of how naturally occurring global Nef sequence diversity impacts these activities is limited. Here, we quantify SERINC3 and SERINC5 internalization function for 339 Nef clones, representing the major pandemic HIV-1 group M subtypes A, B, C and D. We describe distinct subtype-associated hierarchies for Nef-mediated internalization of SERINC5, for which subtype B clones display the highest activities on average, and of SERINC3, for which subtype B clones display the lowest activities on average. We further identify Nef polymorphisms that modulate its ability to counteract SERINC proteins, including substitutions in the N-terminal domain that selectively impair SERINC3 internalization. Our findings demonstrate that the SERINC antagonism activities of HIV Nef differ markedly among major viral subtypes and between individual isolates within a subtype, suggesting that variation in these functions may contribute to global differences in viral pathogenesis.
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Affiliation(s)
- Steven W. Jin
- Faculty of Health Sciences, Simon Fraser University, Burnaby, Canada
| | | | - Jaclyn K. Mann
- HIV Pathogenesis Programme, The Doris Duke Medical Research Institute, University of KwaZulu-Natal, Durban, South Africa
| | - Mwebesa Bosco Bwana
- Faculty of Medicine, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Guinevere Q. Lee
- British Columbia Centre for Excellence in HIV/AIDS, Vancouver, Canada
| | - Chanson J. Brumme
- British Columbia Centre for Excellence in HIV/AIDS, Vancouver, Canada
- Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Peter W. Hunt
- School of Medicine, University of California, San Francisco, United States of America
| | - Jeff N. Martin
- School of Medicine, University of California, San Francisco, United States of America
| | - David R. Bangsberg
- School of Public Health, Oregon Health Science University, Portland, United States of America
| | - Thumbi Ndung’u
- HIV Pathogenesis Programme, The Doris Duke Medical Research Institute, University of KwaZulu-Natal, Durban, South Africa
- Africa Health Research Institute, Durban, South Africa
- Ragon Institute of MGH, MIT, and Harvard University, Cambridge, United States of America
- Max Planck Institute for Infection Biology, Berlin, Germany
- Division of Infection and Immunity, University College London, London, United Kingdom
| | - Zabrina L. Brumme
- Faculty of Health Sciences, Simon Fraser University, Burnaby, Canada
- British Columbia Centre for Excellence in HIV/AIDS, Vancouver, Canada
| | - Mark A. Brockman
- Faculty of Health Sciences, Simon Fraser University, Burnaby, Canada
- British Columbia Centre for Excellence in HIV/AIDS, Vancouver, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, Canada
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Differential Pressures of SERINC5 and IFITM3 on HIV-1 Envelope Glycoprotein over the Course of HIV-1 Infection. J Virol 2020; 94:JVI.00514-20. [PMID: 32493821 DOI: 10.1128/jvi.00514-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Accepted: 05/25/2020] [Indexed: 12/23/2022] Open
Abstract
Infection of human immunodeficiency virus type 1 (HIV-1) is subject to restriction by cellular factors. Serine incorporator 5 (SERINC5) and interferon-inducible transmembrane 3 (IFITM3) proteins represent two of these restriction factors, which inhibit HIV-1 entry into target cells. Both proteins impede fusion of the viral membrane with the cellular membrane and the formation of a viral fusion pore, and both are countered by the HIV-1 envelope glycoprotein (Env). Given the immense and lasting pressure which Env endures from host adaptive immune responses, it is important to understand whether and how HIV-1 Env is able to maintain the resistance to SERINC5 and IFITM3 throughout the course of infection. We have thus examined a panel of HIV-1 Env clones that were isolated at different stages of viral infection-transmission, acute, and chronic. While HIV-1 Env clones from the transmission stage are resistant to both SERINC5 and IFITM3, as infection progresses into the acute and chronic stages, the resistance to IFITM3 but not to SERINC5 is gradually lost. We further discovered a significant correlation between the resistance of HIV-1 Env to soluble CD4 inhibition and the resistance to SERINC5 but not to IFITM3. Interestingly, the miniprotein CD4 mimetic M48U1 sensitizes HIV-1 Env to the inhibition by SERINC5 but not IFITM3. Together, these data indicate that SERINC5 and IFITM3 exert differential inhibitory pressures on HIV-1 Env over different stages of HIV-1 infection and that HIV-1 Env uses varied strategies to resist these two restriction factors.IMPORTANCE HIV-1 Env protein is exposed to the inhibition not only by humoral response, but also by host restriction factors, including serine incorporator 5 (SERINC5) and interferon-inducible transmembrane 3 (IFITM3). This study investigates how HIV-1 envelope glycoprotein (Env) manages to overcome the pressures from all these different host inhibition mechanisms over the long course of viral infection. HIV-1 Env preserves the resistance to SERINC5 but becomes sensitive to IFITM3 when infection progresses into the chronic stage. Our study also supports the possibility of using CD4 mimetic compounds to sensitize HIV-1 Env to the inhibition by SERINC5 as a potential therapeutic strategy.
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Kriesel F, Schelle L, Baldauf HM. Same same but different - Antiviral factors interfering with the infectivity of HIV particles. Microbes Infect 2020; 22:416-422. [PMID: 32450247 DOI: 10.1016/j.micinf.2020.05.009] [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: 04/05/2020] [Revised: 05/11/2020] [Accepted: 05/12/2020] [Indexed: 11/29/2022]
Abstract
Human immunodeficiency virus (HIV) is the causative agent of acquired immunodeficiency syndrome (AIDS). Novel strategies to combat this pandemic include the discovery of cellular proteins targeting distinct steps of the HIV replication cycle. Here, we summarize our current knowledge on antiviral proteins interfering with the infectivity of released HIV particles.
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Affiliation(s)
- Fabian Kriesel
- Max von Pettenkofer Institute & Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, LMU München, Munich, Germany
| | - Luca Schelle
- Max von Pettenkofer Institute & Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, LMU München, Munich, Germany
| | - Hanna-Mari Baldauf
- Max von Pettenkofer Institute & Gene Center, Virology, National Reference Center for Retroviruses, Faculty of Medicine, LMU München, Munich, Germany.
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Loss of Nef-mediated CD3 down-regulation in the HIV-1 lineage increases viral infectivity and spread. Proc Natl Acad Sci U S A 2020; 117:7382-7391. [PMID: 32179688 PMCID: PMC7132320 DOI: 10.1073/pnas.1921135117] [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] [Indexed: 12/22/2022] Open
Abstract
Lentiviruses encode accessory proteins to manipulate their host cells in order to efficiently replicate and evade antiviral defenses. Interestingly, most lentiviral Nefs down-regulate CD3 from the surface of infected T cells to perturb immune responses. However, for reasons that are incompletely understood, HIV-1 and its simian immunodeficiency virus ancestors lack this function. Here, we report that engineering HIV-1 for Nef-mediated down-regulation of CD3 reduces Env-dependent HIV-1 infectivity, resulting in less efficient cell-to-cell spread and replication. Our data suggest that HIV-1 may have evolved to lose the CD3 down-modulation function of Nef in order to allow T cell activation and to boost viral replication, possibly at the cost of less effective immune evasion and increased pathogenicity. Nef is an accessory protein of primate lentiviruses that is essential for efficient replication and pathogenesis of HIV-1. A conserved feature of Nef proteins from different lentiviral lineages is the ability to modulate host protein trafficking and down-regulate a number of cell surface receptors to enhance replication and promote immune evasion. Notably, the inability of Nef to down-regulate CD3 from infected T cells distinguishes HIV-1 Nef and its direct simian precursors from other primate lentiviruses. Why HIV-1 does not employ this potential immune evasion strategy is not fully understood. Using chimeric HIV-1 constructs expressing lentiviral Nef proteins that differ in their ability to down-modulate CD3, we show that retaining CD3 on the surface of infected primary T cells results in increased viral replication and cell-to-cell spread. We identified increased expression of envelope (Env) trimers at the cell surface and increased Env incorporation into virions as the determinants for the Nef- and CD3-dependent enhancement of viral infectivity. Importantly, this was independent of Nef-mediated antagonism of the host restriction factor SERINC5. CD3 retention on the surface of infected primary T cells also correlated with increased T cell signaling, activation, and cell death during cell-to-cell spread. Taken together, our results show that loss of an otherwise conserved function of Nef has a positive effect on HIV-1 replication, allowing for more efficient replication while potentially contributing to HIV-1 pathogenesis by triggering T cell activation and cell death during viral spread.
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