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Iwamoto Y, Ye AA, Shirazinejad C, Hurley JH, Drubin DG. Kinetic investigation reveals an HIV-1 Nef-dependent increase in AP-2 recruitment and productivity at endocytic sites. Mol Biol Cell 2024; 35:ar9. [PMID: 37938925 PMCID: PMC10881171 DOI: 10.1091/mbc.e23-04-0126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 10/24/2023] [Accepted: 11/02/2023] [Indexed: 11/10/2023] Open
Abstract
The HIV-1 accessory protein Nef hijacks clathrin adaptors to degrade or mislocalize host proteins involved in antiviral defenses. Here, using quantitative live-cell microscopy in genome-edited Jurkat cells, we investigate the impact of Nef on clathrin-mediated endocytosis (CME), a major pathway for membrane protein internalization in mammalian cells. Nef is recruited to CME sites on the plasma membrane, and this recruitment is associated with an increase in the recruitment and lifetime of the CME coat protein AP-2 and the late-arriving CME protein dynamin2. Furthermore, we find that CME sites that recruit Nef are more likely to recruit dynamin2 and transferrin, suggesting that Nef recruitment to CME sites promotes site maturation to ensure high efficiency in host protein downregulation. Implications of these observations for HIV-1 infection are discussed.
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Affiliation(s)
- Yuichiro Iwamoto
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Anna A. Ye
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
| | - Cyna Shirazinejad
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720
| | - James H. Hurley
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720
| | - David G. Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720
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2
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Krchlíková V, Lotke R, Haußmann I, Reinišová M, Kučerová D, Pecnová Ľ, Ungrová L, Hejnar J, Sauter D, Elleder D. Independent loss events of a functional tetherin gene in galliform birds. J Virol 2023; 97:e0080323. [PMID: 37712707 PMCID: PMC10617486 DOI: 10.1128/jvi.00803-23] [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: 06/01/2023] [Accepted: 07/19/2023] [Indexed: 09/16/2023] Open
Abstract
IMPORTANCE Birds represent important hosts for numerous viruses, including zoonotic viruses and pathogens with the potential to cause major economic losses to the poultry industry. Viral replication and transmission can be inhibited or blocked by the action of antiviral restriction factors (RFs) encoded by the host. One well-characterized RF is tetherin, a protein that directly blocks the release of newly formed viral particles from infected cells. Here, we describe the evolutionary loss of a functional tetherin gene in two galliform birds, turkey (Meleagris gallopavo) and Mikado pheasant (Syrmaticus mikado). Moreover, we demonstrate that the structurally related protein TMCC(aT) exerts antiviral activity in several birds, albeit by a mechanism different from that of tetherin. The evolutionary scenario described here represents the first documented loss-of-tetherin cases in vertebrates.
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Affiliation(s)
- Veronika Krchlíková
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Rishikesh Lotke
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany
| | - Isabell Haußmann
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany
| | - Markéta Reinišová
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Dana Kučerová
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Ľubomíra Pecnová
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Lenka Ungrová
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Jiří Hejnar
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
| | - Daniel Sauter
- Institute for Medical Virology and Epidemiology of Viral Diseases, University Hospital Tübingen, Tübingen, Germany
| | - Daniel Elleder
- Institute of Molecular Genetics of the Czech Academy of Sciences, Prague, Czech Republic
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3
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Olabode AS, Mumby MJ, Wild TA, Muñoz-Baena L, Dikeakos JD, Poon AFY. Phylogenetic Reconstruction and Functional Characterization of the Ancestral Nef Protein of Primate Lentiviruses. Mol Biol Evol 2023; 40:msad164. [PMID: 37463439 PMCID: PMC10400143 DOI: 10.1093/molbev/msad164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 06/19/2023] [Accepted: 07/10/2023] [Indexed: 07/20/2023] Open
Abstract
Nef is an accessory protein unique to the primate HIV-1, HIV-2, and SIV lentiviruses. During infection, Nef functions by interacting with multiple host proteins within infected cells to evade the immune response and enhance virion infectivity. Notably, Nef can counter immune regulators such as CD4 and MHC-I, as well as the SERINC5 restriction factor in infected cells. In this study, we generated a posterior sample of time-scaled phylogenies relating SIV and HIV Nef sequences, followed by reconstruction of ancestral sequences at the root and internal nodes of the sampled trees up to the HIV-1 Group M ancestor. Upon expression of the ancestral primate lentivirus Nef protein within CD4+ HeLa cells, flow cytometry analysis revealed that the primate lentivirus Nef ancestor robustly downregulated cell-surface SERINC5, yet only partially downregulated CD4 from the cell surface. Further analysis revealed that the Nef-mediated CD4 downregulation ability evolved gradually, while Nef-mediated SERINC5 downregulation was recovered abruptly in the HIV-1/M ancestor. Overall, this study provides a framework to reconstruct ancestral viral proteins and enable the functional characterization of these proteins to delineate how functions could have changed throughout evolutionary history.
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Affiliation(s)
- Abayomi S Olabode
- Department of Pathology & Laboratory Medicine, Western University, London, Canada
| | - Mitchell J Mumby
- Department of Microbiology & Immunology, Western University, London, Canada
| | - Tristan A Wild
- Department of Microbiology & Immunology, Western University, London, Canada
| | - Laura Muñoz-Baena
- Department of Microbiology & Immunology, Western University, London, Canada
| | - Jimmy D Dikeakos
- Department of Microbiology & Immunology, Western University, London, Canada
| | - Art F Y Poon
- Department of Pathology & Laboratory Medicine, Western University, London, Canada
- Department of Microbiology & Immunology, Western University, London, Canada
- Department of Computer Science, Western University, London, Canada
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4
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Iwamoto Y, Ye A, Shirazinejad C, Hurley JH, Drubin DG. Kinetic investigation reveals an HIV-1 Nef-dependent increase in AP-2 recruitment and productivity at endocytic sites. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.18.537262. [PMID: 37131815 PMCID: PMC10153213 DOI: 10.1101/2023.04.18.537262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Lentiviruses express non-enzymatic accessory proteins whose function is to subvert cellular machinery in the infected host. The HIV-1 accessory protein Nef hijacks clathrin adaptors to degrade or mislocalize host proteins involved in antiviral defenses. Here, we investigate the interaction between Nef and clathrin-mediated endocytosis (CME), a major pathway for membrane protein internalization in mammalian cells, using quantitative live-cell microscopy in genome-edited Jurkat cells. Nef is recruited to CME sites on the plasma membrane, and this recruitment correlates with an increase in the recruitment and lifetime of CME coat protein AP-2 and late-arriving CME protein dynamin2. Furthermore, we find that CME sites that recruit Nef are more likely to recruit dynamin2, suggesting that Nef recruitment to CME sites promotes CME site maturation to ensure high efficiency in host protein downregulation.
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Affiliation(s)
- Yuichiro Iwamoto
- Department of Molecular and Cell Biology, University of California Berkeley; Berkeley CA 94720, USA
| | - Anna Ye
- Department of Molecular and Cell Biology, University of California Berkeley; Berkeley CA 94720, USA
| | - Cyna Shirazinejad
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
| | - James H Hurley
- Department of Molecular and Cell Biology, University of California Berkeley; Berkeley CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - David G Drubin
- Department of Molecular and Cell Biology, University of California Berkeley; Berkeley CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
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5
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Jinyu L, Shuying W, Panchan Z, Dan C, Chao C, Xingyu Y, Weiwei C. Bone marrow stromal cell antigen 2(BST2) suppresses the migration and invasion of trophoblasts in preeclampsia by downregulating matrix metallopeptidase 2(MMP2). Bioengineered 2022; 13:13174-13187. [PMID: 35635087 PMCID: PMC9276030 DOI: 10.1080/21655979.2022.2074712] [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] [Indexed: 11/09/2022] Open
Abstract
Preeclampsia is a grievous pregnancy-related complication with an incidence of approximately 5∼7% in pregnant women. Placental abnormalities and decreased placental perfusion associated with impaired trophoblast invasion are early pathological findings of preeclampsia. BST2 is a multifunctional transmembrane protein that plays critical roles in physiological and pathological processes, but its impacts and mechanisms of action in preeclampsia are inadequately understood. The aim of this manuscript was to investigate the functional impacts of BST2 and MMP2 on the biological behavior of trophoblast cells in preeclampsia. The expression of these proteins and their genes was analyzed by qRT-PCR, western blotting and immunohistochemistry. The results showed that the expression of BST2 and MMP2 was significantly downregulated in preeclampsia. The migration and invasion capacities of HTR-8/SVneo and JAR cells with overexpression or knockdown of BST2 were detected by wound healing assay and Transwell assays. It was found that BST2 overexpression could up-regulate MMP2 expression, and enhance the migration and invasion capacity of HTR-8/SVneo and JAR cells. BST2 knockdown could reverse these effects. MMP2 knockdown could downregulate the invasion capacity of HTR-8/SVneo cells, and MMP2 overexpression reversed these effects. Pearson correlation analysis demonstrated that the expression of MMP2 and BST2 were positively correlated. These results indicate that the downregulation of BST2 lowers MMP2 expression and restraint trophoblast functions, which probably explain its role in the pathogenesis of preeclampsia.
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Affiliation(s)
- Liu Jinyu
- International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Embryo Original Disease, Shanghai, China
- Institute of Birth Defects and Rare Diseases, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Wang Shuying
- International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zheng Panchan
- International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chen Dan
- International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Chen Chao
- International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Embryo Original Disease, Shanghai, China
- Institute of Birth Defects and Rare Diseases, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yang Xingyu
- International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
- Shanghai Key Laboratory of Embryo Original Disease, Shanghai, China
| | - Cheng Weiwei
- International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
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Substitutions in Nef That Uncouple Tetherin and SERINC5 Antagonism Impair Simian Immunodeficiency Virus Replication in Primary Rhesus Macaque Lymphocytes. J Virol 2022; 96:e0017622. [PMID: 35536019 DOI: 10.1128/jvi.00176-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Most simian immunodeficiency viruses (SIVs) use Nef to counteract restriction by the tetherin proteins of their nonhuman primate hosts. In addition to counteracting tetherin, SIV Nef has a number of other functions, including the downmodulation of CD3, CD4, and major histocompatibility complex class I (MHC I) molecules from the surface of SIV-infected cells and the enhancement of viral infectivity by preventing the incorporation of SERINC5 into virions. Although these activities require different surfaces of Nef, they can be difficult to separate because of their dependence on similar interactions with AP-1 or AP-2 for clathrin-mediated endocytosis. We previously observed extensive overlap of the SIV Nef residues required for counteracting tetherin and SERINC5. Here, we define substitutions in Nef that separate anti-tetherin activity from SERINC5 antagonism and other activities of Nef. This information was used to engineer an infectious molecular clone of SIV (SIVmac239nefSA) that is sensitive to tetherin but retains CD3, CD4, MHC I, and SERINC5 downmodulation. In primary rhesus macaque CD4+ T cells, SIVmac239nefSA exhibits impaired replication compared to wild-type SIVmac239 under conditions of interferon-induced upregulation of tetherin. These results demonstrate that tetherin antagonism can be separated from other Nef functions and that resistance to tetherin is essential for optimal replication in primary CD4+ T cells. IMPORTANCE Tetherin is an interferon-inducible transmembrane protein that prevents the detachment of enveloped viruses from infected cells by physically tethering nascent virions to cellular membranes. SIV Nef downmodulates simian tetherin to overcome this restriction in nonhuman primate hosts. Nef also enhances virus infectivity by preventing the incorporation of SERINC5 into virions and contributes to immune evasion by downmodulating other proteins from the cell surface. To assess the contribution of tetherin antagonism to virus replication, we engineered an infectious molecular clone of SIV with substitutions in Nef that uncouple tetherin antagonism from other Nef functions. These substitutions impaired virus replication in interferon-treated macaque CD4+ T cells, revealing the impact of tetherin on SIV replication under physiological conditions in primary CD4+ lymphocytes.
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7
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Wang B, Yang R, Tian Y, Yin Q. Reconstituting and Purifying Assembly Intermediates of Clathrin Adaptors AP1 and AP2. Methods Mol Biol 2022; 2473:195-212. [PMID: 35819768 DOI: 10.1007/978-1-0716-2209-4_15] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Clathrin-coated vesicles mediate membrane cargo transportation from the plasma membrane, the trans-Golgi network, the endosome, and the lysosome. Heterotetrameric adaptor complexes 1 and 2 (AP1 and AP2) are bridges that link cargo-loaded membranes to clathrin coats. Assembly of AP2 was previously considered to be spontaneous; however, a recent study found AP2 assembly is a highly orchestrated process controlled by alpha and gamma adaptin binding protein (AAGAB). Evidence shows that AAGAB controls AP1 assembly in a similar way. Insights into the orchestrated assembly process and three-dimensional structures of assembly intermediates are only emerging. Here, we describe a protocol for reconstitution and purification of the complexes containing AAGAB and AP1 or AP2 subunits, known as AP1 and AP2 hemicomplexes. Our purification routinely yields milligrams of pure complexes suitable for structural analysis by X-ray crystallography and electron microscopy.
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Affiliation(s)
- Bing Wang
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Rui Yang
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Yuan Tian
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
| | - Qian Yin
- Department of Biological Science, Florida State University, Tallahassee, FL, USA.
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL, USA.
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8
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SIVgsn-99CM71 Vpu employs different amino acids to antagonize human and greater spot-nosed monkey BST-2. J Virol 2021; 96:e0152721. [PMID: 34878886 DOI: 10.1128/jvi.01527-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Viral protein U (Vpu) is an accessory protein encoded by human immunodeficiency virus type 1 (HIV-1) and certain simian immunodeficiency virus (SIV) strains. Some of these viruses were reported to use Vpu to overcome restriction by BST-2 of their natural hosts. Our own recent report revealed that Vpu of SIVgsn-99CM71 (SIVgsn71) antagonizes human BST-2 through two AxxxxxxxW motifs (A22W30 and A25W33) whereas antagonizing BST-2 of its natural host, greater spot-nosed monkey (GSN), involved only A22W30 motif. Here we show that residues A22, A25, W30, and W33 of SIVgsn71 Vpu are all essential to antagonize human BST-2, while, neither single mutation of A22 nor W30 affected the ability to antagonize GSN BST-2. Similar to A18, which is located in the middle of the A14xxxxxxxW22 motif in HIV-1 NL4-3 Vpu and is essential to antagonize human BST-2, A29, located in the middle of the A25W33 motif of SIVgsn71 Vpu was found to be necessary for antagonizing human but not GSN BST-2. Further mutational analyses revealed that residues L21 and K32 of SIVgsn71 Vpu were also essential for antagonizing human BST-2. On the other hand, the ability of SIVgsn71 Vpu to target GSN BST-2 was unaffected by single amino acid substitutions but required multiple mutations to render SIVgsn71 Vpu inactive against GSN BST-2. These results suggest additional requirements for SIVgsn71 Vpu antagonizing human BST-2, implying evolution of the bst-2 gene under strong selective pressure. Importance Genes related to survival against life-threating pathogens are important determinants of natural selection in animal evolution. For instance, BST-2, a protein showing broad-spectrum antiviral activity, shows polymorphisms entailing different phenotypes even among primate species, suggesting that the bst-2 gene of primates has been subject to strong selective pressure during evolution. At the same time, viruses readily adapt to these evolutionary changes. Thus, we found that Vpu of an SIVgsn isolate (SIVgsn-99CM71) can target BST-2 from humans as well as from its natural host thus potentially facilitating zoonosis. Here we mapped residues in SIVgsn71 Vpu potentially contributing to cross-species transmission. We found that the requirements for targeting human BST-2 are distinct from and more complex than those for targeting GSN BST-2. Our results suggest that the human bst-2 gene might have evolved to acquire more restrictive phenotype than GSN bst-2 against viral proteins after being derived from their common ancestor.
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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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10
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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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11
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Profile of James H. Hurley. Proc Natl Acad Sci U S A 2021; 118:2103243118. [PMID: 33688055 DOI: 10.1073/pnas.2103243118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Sauter D, Kirchhoff F. Evolutionary conflicts and adverse effects of antiviral factors. eLife 2021; 10:e65243. [PMID: 33450175 PMCID: PMC7811402 DOI: 10.7554/elife.65243] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/06/2021] [Indexed: 12/13/2022] Open
Abstract
Human cells are equipped with a plethora of antiviral proteins protecting them against invading viral pathogens. In contrast to apoptotic or pyroptotic cell death, which serves as ultima ratio to combat viral infections, these cell-intrinsic restriction factors may prevent or at least slow down viral spread while allowing the host cell to survive. Nevertheless, their antiviral activity may also have detrimental effects on the host. While the molecular mechanisms underlying the antiviral activity of restriction factors are frequently well investigated, potential undesired effects of their antiviral functions on the host cell are hardly explored. With a focus on antiretroviral proteins, we summarize in this review how individual restriction factors may exert adverse effects as trade-off for efficient defense against attacking pathogens.
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Affiliation(s)
- Daniel Sauter
- Institute of Molecular Virology, Ulm University Medical CenterUlmGermany
- Institute of Medical Virology and Epidemiology of Viral Diseases, University Hospital TübingenTübingenGermany
| | - Frank Kirchhoff
- Institute of Molecular Virology, Ulm University Medical CenterUlmGermany
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13
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Retroviral Restriction Factors and Their Viral Targets: Restriction Strategies and Evolutionary Adaptations. Microorganisms 2020; 8:microorganisms8121965. [PMID: 33322320 PMCID: PMC7764263 DOI: 10.3390/microorganisms8121965] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/30/2020] [Accepted: 12/08/2020] [Indexed: 12/17/2022] Open
Abstract
The evolutionary conflict between retroviruses and their vertebrate hosts over millions of years has led to the emergence of cellular innate immune proteins termed restriction factors as well as their viral antagonists. Evidence accumulated in the last two decades has substantially increased our understanding of the elaborate mechanisms utilized by these restriction factors to inhibit retroviral replication, mechanisms that either directly block viral proteins or interfere with the cellular pathways hijacked by the viruses. Analyses of these complex interactions describe patterns of accelerated evolution for these restriction factors as well as the acquisition and evolution of their virus-encoded antagonists. Evidence is also mounting that many restriction factors identified for their inhibition of specific retroviruses have broader antiviral activity against additional retroviruses as well as against other viruses, and that exposure to these multiple virus challenges has shaped their adaptive evolution. In this review, we provide an overview of the restriction factors that interfere with different steps of the retroviral life cycle, describing their mechanisms of action, adaptive evolution, viral targets and the viral antagonists that evolved to counter these factors.
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Editorial overview: Membrane traffic in the time of COVID-19. Curr Opin Cell Biol 2020; 65:iii-v. [PMID: 33077165 PMCID: PMC7566815 DOI: 10.1016/j.ceb.2020.09.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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15
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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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16
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Kwon Y, Kaake RM, Echeverria I, Suarez M, Karimian Shamsabadi M, Stoneham C, Ramirez PW, Kress J, Singh R, Sali A, Krogan N, Guatelli J, Jia X. Structural basis of CD4 downregulation by HIV-1 Nef. Nat Struct Mol Biol 2020; 27:822-828. [PMID: 32719457 PMCID: PMC7483821 DOI: 10.1038/s41594-020-0463-z] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 06/16/2020] [Indexed: 02/06/2023]
Abstract
The HIV-1 Nef protein suppresses multiple immune surveillance mechanisms to promote viral pathogenesis and is an attractive target for the development of novel therapeutics. A key function of Nef is to remove the CD4 receptor from the cell surface by hijacking clathrin- and adaptor protein complex 2 (AP2)-dependent endocytosis. However, exactly how Nef does this has been elusive. Here, we describe the underlying mechanism as revealed by a 3.0-Å crystal structure of a fusion protein comprising Nef and the cytoplasmic domain of CD4 bound to the tetrameric AP2 complex. An intricate combination of conformational changes occurs in both Nef and AP2 to enable CD4 binding and downregulation. A pocket on Nef previously identified as crucial for recruiting class I MHC is also responsible for recruiting CD4, revealing a potential approach to inhibit two of Nef's activities and sensitize the virus to immune clearance.
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Affiliation(s)
- Yonghwa Kwon
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, Dartmouth, MA, USA
| | - Robyn M Kaake
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
- Gladstone Institutes, San Francisco, CA, USA
| | - Ignacia Echeverria
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
| | | | | | - Charlotte Stoneham
- The VA San Diego Healthcare System, San Diego, CA, USA
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Peter W Ramirez
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Jacob Kress
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, Dartmouth, MA, USA
| | - Rajendra Singh
- The VA San Diego Healthcare System, San Diego, CA, USA
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, CA, USA
- Department of Pharmaceutical Chemistry and Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, CA, USA
| | - Nevan Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, USA
- Gladstone Institutes, San Francisco, CA, USA
| | - John Guatelli
- The VA San Diego Healthcare System, San Diego, CA, USA
- Department of Medicine, University of California, San Diego, La Jolla, CA, USA
| | - Xiaofei Jia
- Department of Chemistry and Biochemistry, University of Massachusetts Dartmouth, Dartmouth, MA, USA.
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17
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Briant K, Redlingshöfer L, Brodsky FM. Clathrin's life beyond 40: Connecting biochemistry with physiology and disease. Curr Opin Cell Biol 2020; 65:141-149. [PMID: 32836101 DOI: 10.1016/j.ceb.2020.06.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/23/2020] [Accepted: 06/27/2020] [Indexed: 01/21/2023]
Abstract
Understanding of the range and mechanisms of clathrin functions has developed exponentially since clathrin's discovery in 1975. Here, newly established molecular mechanisms that regulate clathrin activity and connect clathrin pathways to differentiation, disease and physiological processes such as glucose metabolism are reviewed. Diversity and commonalities of clathrin pathways across the tree of life reveal species-specific differences enabling functional plasticity in both membrane traffic and cytokinesis. New structural information on clathrin coat formation and cargo interactions emphasises the interplay between clathrin, adaptor proteins, lipids and cargo, and how this interplay regulates quality control of clathrin's function and is compromised in infection and neurological disease. Roles for balancing clathrin-mediated cargo transport are defined in stem cell development and additional disease states.
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Affiliation(s)
- Kit Briant
- Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck and University College London, 14 Malet Street, London WC1E 7HX, UK
| | - Lisa Redlingshöfer
- Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck and University College London, 14 Malet Street, London WC1E 7HX, UK
| | - Frances M Brodsky
- Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK; Institute of Structural and Molecular Biology, Birkbeck and University College London, 14 Malet Street, London WC1E 7HX, UK.
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18
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Schouest B, Leslie GJ, Hoxie JA, Maness NJ. Tetherin downmodulation by SIVmac Nef lost with the H196Q escape variant is restored by an upstream variant. PLoS One 2020; 15:e0225420. [PMID: 32764749 PMCID: PMC7413475 DOI: 10.1371/journal.pone.0225420] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 07/13/2020] [Indexed: 01/17/2023] Open
Abstract
The H196 residue in SIVmac239 Nef is conserved across the majority of HIV and SIV isolates, lies immediately adjacent to the AP-2 (adaptor protein 2) binding di-leucine domain (ExxxLM195), and is critical for several described AP-2 dependent Nef functions, including the downregulation of tetherin (BST-2/CD317), CD4, and others. Surprisingly, many stocks of the closely related SIVmac251 swarm virus harbor a nef allele encoding a Q196. In SIVmac239, this variant is associated with loss of multiple AP-2 dependent functions. Publicly available sequences for SIVmac251 stocks were mined for variants linked to Q196 that might compensate for functional defects associated with this residue. Variants were engineered into the SIVmac239 backbone and in Nef expression plasmids and flow cytometry was used to examine surface tetherin expression in primary CD4 T cells and surface CD4 expression in SupT1 cells engineered to express rhesus CD4. We found that SIVmac251 stocks that encode a Q196 residue in Nef uniformly also encode an upstream R191 residue. We show that R191 restores the ability of Nef to downregulate tetherin in the presence of Q196 and has a similar but less pronounced impact on CD4 expression. However, a published report showed Q196 commonly evolves to H196 in vivo, suggesting a fitness cost. R191 may represent compensatory evolution to restore the ability to downregulate tetherin lost in viruses harboring Q196.
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Affiliation(s)
- Blake Schouest
- Division of Microbiology, Tulane National Primate Research Center, Covington, LA, United States of America
| | - George J. Leslie
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - James A. Hoxie
- Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States of America
| | - Nicholas J. Maness
- Division of Microbiology, Tulane National Primate Research Center, Covington, LA, United States of America
- Department of Microbiology and Immunology, School of Medicine, Tulane University Health Sciences Center, New Orleans, LA, United States of America
- * E-mail:
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19
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Engen JR, Komives EA. Complementarity of Hydrogen/Deuterium Exchange Mass Spectrometry and Cryo-Electron Microscopy. Trends Biochem Sci 2020; 45:906-918. [PMID: 32487353 DOI: 10.1016/j.tibs.2020.05.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/23/2020] [Accepted: 05/08/2020] [Indexed: 12/18/2022]
Abstract
Methodological improvements in both single particle cryo-electron microscopy (cryo-EM) and hydrogen/deuterium exchange mass spectrometry (HDX-MS) mean that the two methods are being more frequently used together to tackle complex problems in structural biology. There are many benefits to this combination, including for the analysis of low-resolution density, for structural validation, in the analysis of individual proteins versus the same proteins in large complexes, studies of allostery, protein quality control during cryo-EM construct optimization, and in the study of protein movements/dynamics during function. As will be highlighted in this review, through careful considerations of potential sample and conformational heterogeneity, many joint studies have recently been demonstrated, and many future studies using this combination are anticipated.
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Affiliation(s)
- John R Engen
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, MA 02115, USA.
| | - Elizabeth A Komives
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093, USA
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20
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Tavakoli-Tameh A, Janaka SK, Zarbock K, O’Connor S, Crosno K, Capuano S, Uno H, Lifson JD, Evans DT. Loss of tetherin antagonism by Nef impairs SIV replication during acute infection of rhesus macaques. PLoS Pathog 2020; 16:e1008487. [PMID: 32302364 PMCID: PMC7190186 DOI: 10.1371/journal.ppat.1008487] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 04/29/2020] [Accepted: 03/21/2020] [Indexed: 12/13/2022] Open
Abstract
Most simian immunodeficiency viruses use Nef to counteract the tetherin proteins of their nonhuman primate hosts. Nef also downmodulates cell-surface CD4 and MHC class I (MHC I) molecules and enhances viral infectivity by counteracting SERINC5. We previously demonstrated that tetherin antagonism by SIV Nef is genetically separable from CD4- and MHC I-downmodulation. Here we show that disruption of tetherin antagonism by Nef impairs virus replication during acute SIV infection of rhesus macaques. A combination of mutations was introduced into the SIVmac239 genome resulting in three amino acid substitutions in Nef that impair tetherin antagonism, but not CD3-, CD4- or MHC I-downmodulation. Further characterization of this mutant (SIVmac239AAA) revealed that these changes also result in partial sensitivity to SERINC5. Separate groups of four rhesus macaques were infected with either wild-type SIVmac239 or SIVmac239AAA, and viral RNA loads in plasma and sequence changes in the viral genome were monitored. Viral loads were significantly lower during acute infection in animals infected with SIVmac239AAA than in animals infected with wild-type SIVmac239. Sequence analysis of the virus population in plasma confirmed that the substitutions in Nef were retained during acute infection; however, changes were observed by week 24 post-infection that fully restored anti-tetherin activity and partially restored anti-SERINC5 activity. These observations reveal overlap in the residues of SIV Nef required for counteracting tetherin and SERINC5 and selective pressure to overcome these restriction factors in vivo.
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Affiliation(s)
- Aidin Tavakoli-Tameh
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Sanath Kumar Janaka
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Katie Zarbock
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Shelby O’Connor
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Kristin Crosno
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Saverio Capuano
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Hajime Uno
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - Jeffrey D. Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - David T. Evans
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Wisconsin National Primate Research Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
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21
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Fung SY, Yuen KS, Ye ZW, Chan CP, Jin DY. A tug-of-war between severe acute respiratory syndrome coronavirus 2 and host antiviral defence: lessons from other pathogenic viruses. Emerg Microbes Infect 2020; 9:558-570. [PMID: 32172672 PMCID: PMC7103735 DOI: 10.1080/22221751.2020.1736644] [Citation(s) in RCA: 255] [Impact Index Per Article: 63.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
World Health Organization has declared the ongoing outbreak of coronavirus disease 2019 (COVID-19) a Public Health Emergency of International Concern. The virus was named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by the International Committee on Taxonomy of Viruses. Human infection with SARS-CoV-2 leads to a wide range of clinical manifestations ranging from asymptomatic, mild, moderate to severe. The severe cases present with pneumonia, which can progress to acute respiratory distress syndrome. The outbreak provides an opportunity for real-time tracking of an animal coronavirus that has just crossed species barrier to infect humans. The outcome of SARS-CoV-2 infection is largely determined by virus-host interaction. Here, we review the discovery, zoonotic origin, animal hosts, transmissibility and pathogenicity of SARS-CoV-2 in relation to its interplay with host antiviral defense. A comparison with SARS-CoV, Middle East respiratory syndrome coronavirus, community-acquired human coronaviruses and other pathogenic viruses including human immunodeficiency viruses is made. We summarize current understanding of the induction of a proinflammatory cytokine storm by other highly pathogenic human coronaviruses, their adaptation to humans and their usurpation of the cell death programmes. Important questions concerning the interaction between SARS-CoV-2 and host antiviral defence, including asymptomatic and presymptomatic virus shedding, are also discussed.
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Affiliation(s)
- Sin-Yee Fung
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Kit-San Yuen
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Zi-Wei Ye
- Department of Microbiology, The University of Hong Kong, Pokfulam, Hong Kong
| | - Chi-Ping Chan
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Dong-Yan Jin
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
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22
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Hirao K, Andrews S, Kuroki K, Kusaka H, Tadokoro T, Kita S, Ose T, Rowland-Jones SL, Maenaka K. Structure of HIV-2 Nef Reveals Features Distinct from HIV-1 Involved in Immune Regulation. iScience 2019; 23:100758. [PMID: 31927483 PMCID: PMC6956826 DOI: 10.1016/j.isci.2019.100758] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/24/2019] [Accepted: 12/03/2019] [Indexed: 01/07/2023] Open
Abstract
The human immunodeficiency virus (HIV) accessory protein Nef plays a major role in establishing and maintaining infection, particularly through immune evasion. Many HIV-2-infected people experience long-term viral control and survival, resembling HIV-1 elite control. HIV-2 Nef has overlapping but also distinct functions from HIV-1 Nef. Here we report the crystal structure of HIV-2 Nef core. The di-leucine sorting motif forms a helix bound to neighboring molecules, and moreover, isothermal titration calorimetry demonstrated that the CD3 endocytosis motif can directly bind to HIV-2 Nef, ensuring AP-2-mediated endocytosis for CD3. The highly conserved C-terminal region forms a α-helix, absent from HIV-1. We further determined the structure of simian immunodeficiency virus (SIV) Nef harboring this region, demonstrating similar C-terminal α-helix, which may contribute to AP-1 binding for MHC-I downregulation. These results provide insights into the distinct pathogenesis of HIV-2 infection. Structure of HIV-2 Nef revealed a conserved C-terminal α-helix not present in HIV-1 C-terminal structure is conserved in SIV Nef, likely involved in MHC-I downregulation Di-leucine AP-2-mediated sorting motif forms a helix bound to the α1 and α2 helices ITC demonstrated that the CD3 endocytosis motif can directly bind to HIV-2 Nef
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Affiliation(s)
- Kengo Hirao
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Sophie Andrews
- Nuffield Department of Medicine, University of Oxford, NDM Research Building, Oxford OX3 7FZ, UK
| | - Kimiko Kuroki
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Hiroki Kusaka
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Takashi Tadokoro
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Shunsuke Kita
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Toyoyuki Ose
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan; Faculty of Advanced Life Science, Hokkaido University, Sapporo 060-0810, Japan
| | - Sarah L Rowland-Jones
- Nuffield Department of Medicine, University of Oxford, NDM Research Building, Oxford OX3 7FZ, UK.
| | - Katsumi Maenaka
- Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
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23
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Abstract
The accessory protein Nef of human immunodeficiency virus (HIV) is a primary determinant of viral pathogenesis. Nef is abundantly expressed during infection and reroutes a variety of cell surface proteins to disrupt host immunity and promote the viral replication cycle. Nef counteracts host defenses by sequestering and/or degrading its targets via the endocytic and secretory pathways. Nef does this by physically engaging a number of host trafficking proteins. Substantial progress has been achieved in identifying the targets of Nef, and a structural and mechanistic understanding of Nef's ability to command the protein trafficking machinery has recently started to coalesce. Comparative analysis of HIV and simian immunodeficiency virus (SIV) Nef proteins in the context of recent structural advances sheds further light on both viral evolution and the mechanisms whereby trafficking is hijacked. This review describes how advances in cell and structural biology are uncovering in growing detail how Nef subverts the host immune system, facilitates virus release, and enhances viral infectivity.
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24
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Johnson WE, McCarthy KR. Complex Problems Require Ternary Solutions: Another Lesson from SIV Nef. Cell Host Microbe 2019; 26:299-300. [PMID: 31513765 DOI: 10.1016/j.chom.2019.08.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
In this issue of Cell Host & Microbe, Buffalo et al. describe a cryo-EM structure of SIV Nef complexed with AP-2 and tetherin. The structure helps explain why human tetherin is Nef-resistant and why lentiviruses that successfully emerged in humans (HIV-1 and HIV-2) had to evolve novel anti-tetherin strategies.
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Affiliation(s)
- Welkin E Johnson
- Biology Department, Boston College, Chestnut Hill, MA 02467, USA.
| | - Kevin R McCarthy
- Laboratory of Molecular Medicine, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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