1
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Gres AT, Kirby KA, McFadden WM, Du H, Liu D, Xu C, Bryer AJ, Perilla JR, Shi J, Aiken C, Fu X, Zhang P, Francis AC, Melikyan GB, Sarafianos SG. Multidisciplinary studies with mutated HIV-1 capsid proteins reveal structural mechanisms of lattice stabilization. Nat Commun 2023; 14:5614. [PMID: 37699872 PMCID: PMC10497533 DOI: 10.1038/s41467-023-41197-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 08/25/2023] [Indexed: 09/14/2023] Open
Abstract
HIV-1 capsid (CA) stability is important for viral replication. E45A and P38A mutations enhance and reduce core stability, thus impairing infectivity. Second-site mutations R132T and T216I rescue infectivity. Capsid lattice stability was studied by solving seven crystal structures (in native background), including P38A, P38A/T216I, E45A, E45A/R132T CA, using molecular dynamics simulations of lattices, cryo-electron microscopy of assemblies, time-resolved imaging of uncoating, biophysical and biochemical characterization of assembly and stability. We report pronounced and subtle, short- and long-range rearrangements: (1) A38 destabilized hexamers by loosening interactions between flanking CA protomers in P38A but not P38A/T216I structures. (2) Two E45A structures showed unexpected stabilizing CANTD-CANTD inter-hexamer interactions, variable R18-ring pore sizes, and flipped N-terminal β-hairpin. (3) Altered conformations of E45Aa α9-helices compared to WT, E45A/R132T, WTPF74, WTNup153, and WTCPSF6 decreased PF74, CPSF6, and Nup153 binding, and was reversed in E45A/R132T. (4) An environmentally sensitive electrostatic repulsion between E45 and D51 affected lattice stability, flexibility, ion and water permeabilities, electrostatics, and recognition of host factors.
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Affiliation(s)
- Anna T Gres
- C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
- Department of Chemistry, University of Missouri, Columbia, MO, USA
| | - Karen A Kirby
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
- Children's Healthcare of Atlanta, Atlanta, GA, USA
| | - William M McFadden
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Haijuan Du
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA
| | - Dandan Liu
- C.S. Bond Life Sciences Center, University of Missouri, Columbia, MO, USA
- Department of Molecular Microbiology & Immunology, University of Missouri School of Medicine, Columbia, MO, USA
| | - Chaoyi Xu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - Alexander J Bryer
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
- Department of Physics & Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jiong Shi
- Department of Pathology, Immunology & Microbiology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Christopher Aiken
- Department of Pathology, Immunology & Microbiology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Xiaofeng Fu
- Department of Structural Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA, USA
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA, USA
- Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, UK
- Electron Bio-Imaging Centre, Diamond Light Sources, Harwell Science and Innovation Campus, Didcot, UK
| | - Ashwanth C Francis
- Department of Biological Science, Florida State University, Tallahassee, FL, USA
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA
| | - Gregory B Melikyan
- Children's Healthcare of Atlanta, Atlanta, GA, USA
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA
| | - Stefan G Sarafianos
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, USA.
- Children's Healthcare of Atlanta, Atlanta, GA, USA.
- Department of Molecular Microbiology & Immunology, University of Missouri School of Medicine, Columbia, MO, USA.
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2
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Gupta M, Pak AJ, Voth GA. Critical mechanistic features of HIV-1 viral capsid assembly. SCIENCE ADVANCES 2023; 9:eadd7434. [PMID: 36608139 PMCID: PMC9821859 DOI: 10.1126/sciadv.add7434 10.1126/sciadv.add7434] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/08/2022] [Indexed: 11/04/2023]
Abstract
The maturation of HIV-1 capsid protein (CA) into a cone-shaped lattice capsid is critical for viral infectivity. CA can self-assemble into a range of capsid morphologies made of ~175 to 250 hexamers and 12 pentamers. The cellular polyanion inositol hexakisphosphate (IP6) has recently been demonstrated to facilitate conical capsid formation by coordinating a ring of arginine residues within the central cavity of capsid hexamers and pentamers. However, the kinetic interplay of events during IP6 and CA coassembly is unclear. In this work, we use coarse-grained molecular dynamics simulations to elucidate the molecular mechanism of capsid formation, including the role played by IP6. We show that IP6, in small quantities at first, promotes curvature generation by trapping pentameric defects in the growing lattice and shifts assembly behavior toward kinetically favored outcomes. Our analysis also suggests that IP6 can stabilize metastable capsid intermediates and can induce structural pleomorphism in mature capsids.
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Affiliation(s)
- Manish Gupta
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | | | - Gregory A. Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
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3
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Gupta M, Pak AJ, Voth GA. Critical mechanistic features of HIV-1 viral capsid assembly. SCIENCE ADVANCES 2023; 9:eadd7434. [PMID: 36608139 PMCID: PMC9821859 DOI: 10.1126/sciadv.add7434+10.1126/sciadv.add7434] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/08/2022] [Indexed: 01/21/2024]
Abstract
The maturation of HIV-1 capsid protein (CA) into a cone-shaped lattice capsid is critical for viral infectivity. CA can self-assemble into a range of capsid morphologies made of ~175 to 250 hexamers and 12 pentamers. The cellular polyanion inositol hexakisphosphate (IP6) has recently been demonstrated to facilitate conical capsid formation by coordinating a ring of arginine residues within the central cavity of capsid hexamers and pentamers. However, the kinetic interplay of events during IP6 and CA coassembly is unclear. In this work, we use coarse-grained molecular dynamics simulations to elucidate the molecular mechanism of capsid formation, including the role played by IP6. We show that IP6, in small quantities at first, promotes curvature generation by trapping pentameric defects in the growing lattice and shifts assembly behavior toward kinetically favored outcomes. Our analysis also suggests that IP6 can stabilize metastable capsid intermediates and can induce structural pleomorphism in mature capsids.
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Affiliation(s)
- Manish Gupta
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
| | | | - Gregory A. Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637, USA
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4
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Gupta M, Pak AJ, Voth GA. Critical mechanistic features of HIV-1 viral capsid assembly. SCIENCE ADVANCES 2023; 9:eadd7434. [PMID: 36608139 PMCID: PMC9821859 DOI: 10.1126/sciadv.add7434] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 12/08/2022] [Indexed: 05/29/2023]
Abstract
The maturation of HIV-1 capsid protein (CA) into a cone-shaped lattice capsid is critical for viral infectivity. CA can self-assemble into a range of capsid morphologies made of ~175 to 250 hexamers and 12 pentamers. The cellular polyanion inositol hexakisphosphate (IP6) has recently been demonstrated to facilitate conical capsid formation by coordinating a ring of arginine residues within the central cavity of capsid hexamers and pentamers. However, the kinetic interplay of events during IP6 and CA coassembly is unclear. In this work, we use coarse-grained molecular dynamics simulations to elucidate the molecular mechanism of capsid formation, including the role played by IP6. We show that IP6, in small quantities at first, promotes curvature generation by trapping pentameric defects in the growing lattice and shifts assembly behavior toward kinetically favored outcomes. Our analysis also suggests that IP6 can stabilize metastable capsid intermediates and can induce structural pleomorphism in mature capsids.
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5
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Yang H, Talledge N, Arndt WG, Zhang W, Mansky LM. Human Immunodeficiency Virus Type 2 Capsid Protein Mutagenesis Reveals Amino Acid Residues Important for Virus Particle Assembly. J Mol Biol 2022; 434:167753. [PMID: 35868362 PMCID: PMC11057910 DOI: 10.1016/j.jmb.2022.167753] [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: 05/11/2022] [Revised: 07/13/2022] [Accepted: 07/13/2022] [Indexed: 11/16/2022]
Abstract
Human immunodeficiency virus (HIV) Gag drives virus particle assembly. The capsid (CA) domain is critical for Gag multimerization mediated by protein-protein interactions. The Gag protein interaction network defines critical aspects of the retroviral lifecycle at steps such as particle assembly and maturation. Previous studies have demonstrated that the immature particle morphology of HIV-2 is intriguingly distinct relative to that of HIV-1. Based upon this observation, we sought to determine the amino acid residues important for virus assembly that might help explain the differences between HIV-1 and HIV-2. To do this, we conducted site-directed mutagenesis of targeted locations in the HIV-2 CA domain of Gag and analyzed various aspects of virus particle assembly. A panel of 31 site-directed mutants of residues that reside at the HIV-2 CA inter-hexamer interface, intra-hexamer interface and CA inter-domain linker were created and analyzed for their effects on the efficiency of particle production, particle morphology, particle infectivity, Gag subcellular distribution and in vitro protein assembly. Seven conserved residues between HIV-1 and HIV-2 (L19, A41, I152, K153, K157, N194, D196) and two non-conserved residues (G38, N127) were found to significantly impact Gag multimerization and particle assembly. Taken together, these observations complement structural analyses of immature HIV-2 particle morphology and Gag lattice organization as well as provide important comparative insights into the key amino acid residues that can help explain the observed differences between HIV immature particle morphology and its association with virus replication and particle infectivity.
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Affiliation(s)
- Huixin Yang
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA
| | - Nathaniel Talledge
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - William G Arndt
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Biochemistry, Molecular Biology & Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Wei Zhang
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Characterization Facility, College of Sciences and Engineering, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA; Biochemistry, Molecular Biology & Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
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6
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Krebs AS, Mendonça LM, Zhang P. Structural Analysis of Retrovirus Assembly and Maturation. Viruses 2021; 14:54. [PMID: 35062258 PMCID: PMC8778513 DOI: 10.3390/v14010054] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 12/30/2022] Open
Abstract
Retroviruses have a very complex and tightly controlled life cycle which has been studied intensely for decades. After a virus enters the cell, it reverse-transcribes its genome, which is then integrated into the host genome, and subsequently all structural and regulatory proteins are transcribed and translated. The proteins, along with the viral genome, assemble into a new virion, which buds off the host cell and matures into a newly infectious virion. If any one of these steps are faulty, the virus cannot produce infectious viral progeny. Recent advances in structural and molecular techniques have made it possible to better understand this class of viruses, including details about how they regulate and coordinate the different steps of the virus life cycle. In this review we summarize the molecular analysis of the assembly and maturation steps of the life cycle by providing an overview on structural and biochemical studies to understand these processes. We also outline the differences between various retrovirus families with regards to these processes.
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Affiliation(s)
- Anna-Sophia Krebs
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
| | - Luiza M. Mendonça
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford OX3 7BN, UK
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7
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McFadden WM, Snyder AA, Kirby KA, Tedbury PR, Raj M, Wang Z, Sarafianos SG. Rotten to the core: antivirals targeting the HIV-1 capsid core. Retrovirology 2021; 18:41. [PMID: 34937567 PMCID: PMC8693499 DOI: 10.1186/s12977-021-00583-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 11/09/2021] [Indexed: 12/20/2022] Open
Abstract
The capsid core of HIV-1 is a large macromolecular assembly that surrounds the viral genome and is an essential component of the infectious virus. In addition to its multiple roles throughout the viral life cycle, the capsid interacts with multiple host factors. Owing to its indispensable nature, the HIV-1 capsid has been the target of numerous antiretrovirals, though most capsid-targeting molecules have not had clinical success until recently. Lenacapavir, a long-acting drug that targets the HIV-1 capsid, is currently undergoing phase 2/3 clinical trials, making it the most successful capsid inhibitor to-date. In this review, we detail the role of the HIV-1 capsid protein in the virus life cycle, categorize antiviral compounds based on their targeting of five sites within the HIV-1 capsid, and discuss their molecular interactions and mechanisms of action. The diverse range of inhibition mechanisms provides insight into possible new strategies for designing novel HIV-1 drugs and furthers our understanding of HIV-1 biology. ![]()
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Affiliation(s)
- William M McFadden
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Alexa A Snyder
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Karen A Kirby
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Philip R Tedbury
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, 30322, USA.,Children's Healthcare of Atlanta, Atlanta, GA, 30322, USA
| | - Monika Raj
- Department of Chemistry, Emory University, Atlanta, GA, 30322, USA
| | - Zhengqiang Wang
- Center for Drug Design, College of Pharmacy, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Stefan G Sarafianos
- Laboratory of Biochemical Pharmacology, 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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8
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Mendonça L, Sun D, Ning J, Liu J, Kotecha A, Olek M, Frosio T, Fu X, Himes BA, Kleinpeter AB, Freed EO, Zhou J, Aiken C, Zhang P. CryoET structures of immature HIV Gag reveal six-helix bundle. Commun Biol 2021; 4:481. [PMID: 33863979 PMCID: PMC8052356 DOI: 10.1038/s42003-021-01999-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Accepted: 03/18/2021] [Indexed: 11/09/2022] Open
Abstract
Gag is the HIV structural precursor protein which is cleaved by viral protease to produce mature infectious viruses. Gag is a polyprotein composed of MA (matrix), CA (capsid), SP1, NC (nucleocapsid), SP2 and p6 domains. SP1, together with the last eight residues of CA, have been hypothesized to form a six-helix bundle responsible for the higher-order multimerization of Gag necessary for HIV particle assembly. However, the structure of the complete six-helix bundle has been elusive. Here, we determined the structures of both Gag in vitro assemblies and Gag viral-like particles (VLPs) to 4.2 Å and 4.5 Å resolutions using cryo-electron tomography and subtomogram averaging by emClarity. A single amino acid mutation (T8I) in SP1 stabilizes the six-helix bundle, allowing to discern the entire CA-SP1 helix connecting to the NC domain. These structures provide a blueprint for future development of small molecule inhibitors that can lock SP1 in a stable helical conformation, interfere with virus maturation, and thus block HIV-1 infection.
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Affiliation(s)
- Luiza Mendonça
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Dapeng Sun
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jiying Ning
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jiwei Liu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Abhay Kotecha
- Thermo Fisher Scientific, Eindhoven, The Netherlands
| | - Mateusz Olek
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
- Department of Chemistry, University of York, York, UK
| | - Thomas Frosio
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Xiaofeng Fu
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Benjamin A Himes
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Alex B Kleinpeter
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Jing Zhou
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK.
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Zhong Z, Ning J, Boggs EA, Jang S, Wallace C, Telmer C, Bruchez MP, Ahn J, Engelman AN, Zhang P, Watkins SC, Ambrose Z. Cytoplasmic CPSF6 Regulates HIV-1 Capsid Trafficking and Infection in a Cyclophilin A-Dependent Manner. mBio 2021; 12:e03142-20. [PMID: 33758083 PMCID: PMC8092277 DOI: 10.1128/mbio.03142-20] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/16/2021] [Indexed: 12/24/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) capsid binds host proteins during infection, including cleavage and polyadenylation specificity factor 6 (CPSF6) and cyclophilin A (CypA). We observe that HIV-1 infection induces higher-order CPSF6 formation, and capsid-CPSF6 complexes cotraffic on microtubules. CPSF6-capsid complex trafficking is impacted by capsid alterations that reduce CPSF6 binding or by excess cytoplasmic CPSF6 expression, both of which are associated with decreased HIV-1 infection. Higher-order CPSF6 complexes bind and disrupt HIV-1 capsid assemblies in vitro Disruption of HIV-1 capsid binding to CypA leads to increased CPSF6 binding and altered capsid trafficking, resulting in reduced infectivity. Our data reveal an interplay between CPSF6 and CypA that is important for cytoplasmic capsid trafficking and HIV-1 infection. We propose that CypA prevents HIV-1 capsid from prematurely engaging cytoplasmic CPSF6 and that differences in CypA cellular localization and innate immunity may explain variations in HIV-1 capsid trafficking and uncoating in CD4+ T cells and macrophages.IMPORTANCE HIV is the causative agent of AIDS, which has no cure. The protein shell that encases the viral genome, the capsid, is critical for HIV replication in cells at multiple steps. HIV capsid has been shown to interact with multiple cell proteins during movement to the cell nucleus in a poorly understood process that may differ during infection of different cell types. In this study, we show that premature or too much binding of one human protein, cleavage and polyadenylation specificity factor 6 (CPSF6), disrupts the ability of the capsid to deliver the viral genome to the cell nucleus. Another human protein, cyclophilin A (CypA), can shield HIV capsid from premature binding to CPSF6, which can differ in CD4+ T cells and macrophages. Better understanding of how HIV infects cells will allow better drugs to prevent or inhibit infection and pathogenesis.
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Affiliation(s)
- Zhou Zhong
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Jiying Ning
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Emerson A Boggs
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Sooin Jang
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Callen Wallace
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Cheryl Telmer
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Marcel P Bruchez
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
| | - Jinwoo Ahn
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Alan N Engelman
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, England
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, United Kingdom
| | - Simon C Watkins
- Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
| | - Zandrea Ambrose
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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10
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Novikova M, Zhang Y, Freed EO, Peng K. Multiple Roles of HIV-1 Capsid during the Virus Replication Cycle. Virol Sin 2019; 34:119-134. [PMID: 31028522 PMCID: PMC6513821 DOI: 10.1007/s12250-019-00095-3] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Accepted: 01/16/2019] [Indexed: 11/29/2022] Open
Abstract
Human immunodeficiency virus-1 capsid (HIV-1 CA) is involved in different stages of the viral replication cycle. During virion assembly, CA drives the formation of the hexameric lattice in immature viral particles, while in mature virions CA monomers assemble in cone-shaped cores surrounding the viral RNA genome and associated proteins. In addition to its functions in late stages of the viral replication cycle, CA plays key roles in a number of processes during early phases of HIV-1 infection including trafficking, uncoating, recognition by host cellular proteins and nuclear import of the viral pre-integration complex. As a result of efficient cooperation of CA with other viral and cellular proteins, integration of the viral genetic material into the host genome, which is an essential step for productive viral infection, successfully occurs. In this review, we will summarize available data on CA functions in HIV-1 replication, describing in detail its roles in late and early phases of the viral replication cycle.
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Affiliation(s)
- Mariia Novikova
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Yulan Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA.
| | - Ke Peng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China.
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11
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Identification of a Structural Element in HIV-1 Gag Required for Virus Particle Assembly and Maturation. mBio 2018; 9:mBio.01567-18. [PMID: 30327442 PMCID: PMC6191540 DOI: 10.1128/mbio.01567-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Late in the HIV-1 replication cycle, the viral structural protein Gag is targeted to virus assembly sites at the plasma membrane of infected cells. The capsid (CA) domain of Gag plays a critical role in the formation of the hexameric Gag lattice in the immature virion, and, during particle release, CA is cleaved from the Gag precursor by the viral protease and forms the conical core of the mature virion. A highly conserved Pro-Pro-Ile-Pro (PPIP) motif (CA residues 122 to 125) [PPIP(122-125)] in a loop connecting CA helices 6 and 7 resides at a 3-fold axis formed by neighboring hexamers in the immature Gag lattice. In this study, we characterized the role of this PPIP(122-125) loop in HIV-1 assembly and maturation. While mutations P123A and P125A were relatively well tolerated, mutation of P122 and I124 significantly impaired virus release, caused Gag processing defects, and abolished infectivity. X-ray crystallography indicated that the P122A and I124A mutations induce subtle changes in the structure of the mature CA lattice which were permissive for in vitro assembly of CA tubes. Transmission electron microscopy and cryo-electron tomography demonstrated that the P122A and I124A mutations induce severe structural defects in the immature Gag lattice and abrogate conical core formation. Propagation of the P122A and I124A mutants in T-cell lines led to the selection of compensatory mutations within CA. Our findings demonstrate that the CA PPIP(122-125) loop comprises a structural element critical for the formation of the immature Gag lattice.IMPORTANCE Capsid (CA) plays multiple roles in the HIV-1 replication cycle. CA-CA domain interactions are responsible for multimerization of the Gag polyprotein at virus assembly sites, and in the mature virion, CA monomers assemble into a conical core that encapsidates the viral RNA genome. Multiple CA regions that contribute to the assembly and release of HIV-1 particles have been mapped and investigated. Here, we identified and characterized a Pro-rich loop in CA that is important for the formation of the immature Gag lattice. Changes in this region disrupt viral production and abrogate the formation of infectious, mature virions. Propagation of the mutants in culture led to the selection of second-site compensatory mutations within CA. These results expand our knowledge of the assembly and maturation steps in the viral replication cycle and may be relevant for development of antiviral drugs targeting CA.
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12
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Wang M, Quinn CM, Perilla JR, Zhang H, Shirra R, Hou G, Byeon IJ, Suiter CL, Ablan S, Urano E, Nitz TJ, Aiken C, Freed EO, Zhang P, Schulten K, Gronenborn AM, Polenova T. Quenching protein dynamics interferes with HIV capsid maturation. Nat Commun 2017; 8:1779. [PMID: 29176596 PMCID: PMC5701193 DOI: 10.1038/s41467-017-01856-y] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Accepted: 10/19/2017] [Indexed: 11/14/2022] Open
Abstract
Maturation of HIV-1 particles encompasses a complex morphological transformation of Gag via an orchestrated series of proteolytic cleavage events. A longstanding question concerns the structure of the C-terminal region of CA and the peptide SP1 (CA–SP1), which represents an intermediate during maturation of the HIV-1 virus. By integrating NMR, cryo-EM, and molecular dynamics simulations, we show that in CA–SP1 tubes assembled in vitro, which represent the features of an intermediate assembly state during maturation, the SP1 peptide exists in a dynamic helix–coil equilibrium, and that the addition of the maturation inhibitors Bevirimat and DFH-055 causes stabilization of a helical form of SP1. Moreover, the maturation-arresting SP1 mutation T8I also induces helical structure in SP1 and further global dynamical and conformational changes in CA. Overall, our results show that dynamics of CA and SP1 are critical for orderly HIV-1 maturation and that small molecules can inhibit maturation by perturbing molecular motions. The process of HIV particle maturation involves complex molecular transitions. Here the authors combine NMR spectroscopy, cryo-EM, and molecular dynamics simulations to provide insight into the conformational equilibria in CA-SP1 assemblies relevant to HIV-1 maturation intermediates formation.
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Affiliation(s)
- Mingzhang Wang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Caitlin M Quinn
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA. .,University of Illinois, Theoretical and Computational Biophysics Group, Urbana, IL, 61801, USA.
| | - Huilan Zhang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Randall Shirra
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.,Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Guangjin Hou
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - In-Ja Byeon
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.,Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Christopher L Suiter
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA
| | - Sherimay Ablan
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Emiko Urano
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | | | - Christopher Aiken
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.,Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Eric O Freed
- HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA
| | - Peijun Zhang
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.,Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.,Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford, OX3 7BN, UK
| | - Klaus Schulten
- University of Illinois, Theoretical and Computational Biophysics Group, Urbana, IL, 61801, USA
| | - Angela M Gronenborn
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA. .,Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
| | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA. .,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, 1051 Biomedical Science Tower 3, 3501 Fifth Ave., Pittsburgh, PA, 15261, USA.
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13
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In vitro assembly of the Rous Sarcoma Virus capsid protein into hexamer tubes at physiological temperature. Sci Rep 2017; 7:2913. [PMID: 28588198 PMCID: PMC5460288 DOI: 10.1038/s41598-017-02060-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 04/06/2017] [Indexed: 12/21/2022] Open
Abstract
During a proteolytically-driven maturation process, the orthoretroviral capsid protein (CA) assembles to form the convex shell that surrounds the viral genome. In some orthoretroviruses, including Rous Sarcoma Virus (RSV), CA carries a short and hydrophobic spacer peptide (SP) at its C-terminus early in the maturation process, which is progressively removed as maturation proceeds. In this work, we show that RSV CA assembles in vitro at near-physiological temperatures, forming hexamer tubes that effectively model the mature capsid surface. Tube assembly is strongly influenced by electrostatic effects, and is a nucleated process that remains thermodynamically favored at lower temperatures, but is effectively arrested by the large Gibbs energy barrier associated with nucleation. RSV CA tubes are multi-layered, being formed by nested and concentric tubes of capsid hexamers. However the spacer peptide acts as a layering determinant during tube assembly. If only a minor fraction of CA-SP is present, multi-layered tube formation is blocked, and single-layered tubes predominate. This likely prevents formation of biologically aberrant multi-layered capsids in the virion. The generation of single-layered hexamer tubes facilitated 3D helical image reconstruction from cryo-electron microscopy data, revealing the basic tube architecture.
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14
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Ning J, Erdemci-Tandogan G, Yufenyuy EL, Wagner J, Himes BA, Zhao G, Aiken C, Zandi R, Zhang P. In vitro protease cleavage and computer simulations reveal the HIV-1 capsid maturation pathway. Nat Commun 2016; 7:13689. [PMID: 27958264 PMCID: PMC5159922 DOI: 10.1038/ncomms13689] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 10/24/2016] [Indexed: 12/23/2022] Open
Abstract
HIV-1 virions assemble as immature particles containing Gag polyproteins that are processed by the viral protease into individual components, resulting in the formation of mature infectious particles. There are two competing models for the process of forming the mature HIV-1 core: the disassembly and de novo reassembly model and the non-diffusional displacive model. To study the maturation pathway, we simulate HIV-1 maturation in vitro by digesting immature particles and assembled virus-like particles with recombinant HIV-1 protease and monitor the process with biochemical assays and cryoEM structural analysis in parallel. Processing of Gag in vitro is accurate and efficient and results in both soluble capsid protein and conical or tubular capsid assemblies, seemingly converted from immature Gag particles. Computer simulations further reveal probable assembly pathways of HIV-1 capsid formation. Combining the experimental data and computer simulations, our results suggest a sequential combination of both displacive and disassembly/reassembly processes for HIV-1 maturation. Two competing models—disassembly/reassembly and displacive—have been proposed for how immature spherical HIV virions transform into mature particles with conical cores. Here the authors provide evidence that both disassembly/reassembly and displacive processes occur sequentially during the maturation process.
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Affiliation(s)
- Jiying Ning
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
| | - Gonca Erdemci-Tandogan
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Ernest L Yufenyuy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Jef Wagner
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Benjamin A Himes
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA
| | - Gongpu Zhao
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
| | - Christopher Aiken
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA.,Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
| | - Roya Zandi
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 5th Avenue, Pittsburgh, Pennsylvania 15260, USA.,Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA.,Division of Structural Biology, University of Oxford, The Henry Wellcome Building for Genomic Medicine, Headington, Oxford OX3 7BN, UK.,Electron Bio-Imaging Centre, Diamond Light Sources, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
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15
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Abbadessa D, Smurthwaite CA, Reed CW, Wolkowicz R. A Single-Cell Platform for Monitoring Viral Proteolytic Cleavage in Different Cellular Compartments. BIOCHEMISTRY INSIGHTS 2016; 8:23-31. [PMID: 27688710 PMCID: PMC5034881 DOI: 10.4137/bci.s30379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/17/2016] [Accepted: 08/19/2016] [Indexed: 11/08/2022]
Abstract
Infectious diseases affect human health despite advances in biomedical research and drug discovery. Among these, viruses are especially difficult to tackle due to the sudden transfer from animals to humans, high mutational rates, resistance to current treatments, and the intricacies of their molecular interactions with the host. As an example of these interactions, we describe a cell-based approach to monitor specific proteolytic events executed by either the viral-encoded protease or by host proteins on the virus. We then emphasize the significance of examining proteolysis within the subcellular compartment where cleavage occurs naturally. We show the power of stable expression, highlighting the usefulness of the cell-based multiplexed approach, which we have adapted to two independent assays previously developed to monitor (a) the activity of the HIV-1-encoded protease or (b) the cleavage of the HIV-1-encoded envelope protein by the host. Multiplexing was achieved by mixing cells each carrying a different assay or, alternatively, by engineering cells expressing two assays. Multiplexing relies on the robustness of the individual assays and their clear discrimination, further enhancing screening capabilities in an attempt to block proteolytic events required for viral infectivity and spread.
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Affiliation(s)
- Darin Abbadessa
- Department of Biology, San Diego State University, San Diego, CA, USA
| | | | - Connor W Reed
- Department of Biology, San Diego State University, San Diego, CA, USA
| | - Roland Wolkowicz
- Department of Biology, San Diego State University, San Diego, CA, USA
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16
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Bayro MJ, Ganser-Pornillos BK, Zadrozny KK, Yeager M, Tycko R. Helical Conformation in the CA-SP1 Junction of the Immature HIV-1 Lattice Determined from Solid-State NMR of Virus-like Particles. J Am Chem Soc 2016; 138:12029-32. [PMID: 27593947 DOI: 10.1021/jacs.6b07259] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Maturation of HIV-1 requires disassembly of the Gag polyprotein lattice, which lines the viral membrane in the immature state, and subsequent assembly of the mature capsid protein lattice, which encloses viral RNA in the mature state. Metastability of the immature lattice has been proposed to depend on the existence of a structurally ordered, α-helical segment spanning the junction between capsid (CA) and spacer peptide 1 (SP1) subunits of Gag, a segment that is dynamically disordered in the mature capsid lattice. We report solid state nuclear magnetic resonance (ssNMR) measurements on the immature lattice in noncrystalline, spherical virus-like particles (VLPs) derived from Gag. The ssNMR data provide definitive evidence for this critical α-helical segment in the VLPs. Differences in ssNMR chemical shifts and signal intensities between immature and mature lattice assemblies also support a major rearrangement of intermolecular interactions in the maturation process, consistent with recent models from electron cryomicroscopy and X-ray crystallography.
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Affiliation(s)
- Marvin J Bayro
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0520, United States
| | - Barbie K Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Seridan G. Snyder Translational Research Building, 480 Ray C. Hunt Drive, Charlottesville, Virginia 22908, United States
| | - Kaneil K Zadrozny
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Seridan G. Snyder Translational Research Building, 480 Ray C. Hunt Drive, Charlottesville, Virginia 22908, United States
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine , Seridan G. Snyder Translational Research Building, 480 Ray C. Hunt Drive, Charlottesville, Virginia 22908, United States.,Department of Medicine, Division of Cardiovascular Medicine, University of Virginia Health System , Charlottesville, Virginia 22908, United States.,Center for Membrane and Cell Physiology, University of Virginia School of Medicine , Charlottesville, Virginia 22908, United States
| | - Robert Tycko
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , Bethesda, Maryland 20892-0520, United States
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17
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Contributions of Charged Residues in Structurally Dynamic Capsid Surface Loops to Rous Sarcoma Virus Assembly. J Virol 2016; 90:5700-5714. [PMID: 27053549 DOI: 10.1128/jvi.00378-16] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 03/29/2016] [Indexed: 01/08/2023] Open
Abstract
UNLABELLED Extensive studies of orthoretroviral capsids have shown that many regions of the CA protein play unique roles at different points in the virus life cycle. The N-terminal domain (NTD) flexible-loop (FL) region is one such example: exposed on the outer capsid surface, it has been implicated in Gag-mediated particle assembly, capsid maturation, and early replication events. We have now defined the contributions of charged residues in the FL region of the Rous sarcoma virus (RSV) CA to particle assembly. Effects of mutations on assembly were assessed in vivo and in vitro and analyzed in light of new RSV Gag lattice models. Virus replication was strongly dependent on the preservation of charge at a few critical positions in Gag-Gag interfaces. In particular, a cluster of charges at the beginning of FL contributes to an extensive electrostatic network that is important for robust Gag assembly and subsequent capsid maturation. Second-site suppressor analysis suggests that one of these charged residues, D87, has distal influence on interhexamer interactions involving helix α7. Overall, the tolerance of FL to most mutations is consistent with current models of Gag lattice structures. However, the results support the interpretation that virus evolution has achieved a charge distribution across the capsid surface that (i) permits the packing of NTD domains in the outer layer of the Gag shell, (ii) directs the maturational rearrangements of the NTDs that yield a functional core structure, and (iii) supports capsid function during the early stages of virus infection. IMPORTANCE The production of infectious retrovirus particles is a complex process, a choreography of protein and nucleic acid that occurs in two distinct stages: formation and release from the cell of an immature particle followed by an extracellular maturation phase during which the virion proteins and nucleic acids undergo major rearrangements that activate the infectious potential of the virion. This study examines the contributions of charged amino acids on the surface of the Rous sarcoma virus capsid protein in the assembly of appropriately formed immature particles and the maturational transitions that create a functional virion. The results provide important biological evidence in support of recent structural models of the RSV immature virions and further suggest that immature particle assembly and virion maturation are controlled by an extensive network of electrostatic interactions and long-range communication across the capsid surface.
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18
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Erdemci-Tandogan G, Wagner J, van der Schoot P, Zandi R. Role of Genome in the Formation of Conical Retroviral Shells. J Phys Chem B 2016; 120:6298-305. [PMID: 27128962 DOI: 10.1021/acs.jpcb.6b02712] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Human immunodeficiency virus (HIV) capsid proteins spontaneously assemble around the genome into a protective protein shell called the capsid, which can take on a variety of shapes broadly classified as conical, cylindrical, and irregular. The majority of capsids seen in in vivo studies are conical in shape, while in vitro experiments have shown a preference for cylindrical capsids. The factors involved in the selection of the unique shape of HIV capsids are not well understood, and in particular the impact of RNA on the formation of the capsid is not known. In this work, we study the role of the genome and its interaction with the capsid protein by modeling the genomic RNA through a mean-field theory. Our results show that the confinement free energy for a homopolymeric model genome confined in a conical capsid is lower than that in a cylindrical capsid, at least when the genome does not interact with the capsid, which seems to be the case in in vivo experiments. Conversely, the confinement free energy for the cylinder is lower than that for a conical capsid if the genome is attracted to the capsid proteins as the in vitro experiments. Understanding the factors that contribute to the formation of conical capsids may shed light on the infectivity of HIV particles.
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Affiliation(s)
- Gonca Erdemci-Tandogan
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
| | - Jef Wagner
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
| | - Paul van der Schoot
- Group Theory of Polymers and Soft Matter, Eindhoven University of Technology , P.O. Box 513, 5600 MB Eindhoven, The Netherlands.,Institute for Theoretical Physics, Utrecht University , Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
| | - Roya Zandi
- Department of Physics and Astronomy, University of California , Riverside, California 92521, United States
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19
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Khwaja A, Galilee M, Marx A, Alian A. Structure of FIV capsid C-terminal domain demonstrates lentiviral evasion of genetic fragility by coevolved substitutions. Sci Rep 2016; 6:24957. [PMID: 27102180 PMCID: PMC4840305 DOI: 10.1038/srep24957] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/08/2016] [Indexed: 12/22/2022] Open
Abstract
Viruses use a strategy of high mutational rates to adapt to environmental and therapeutic pressures, circumventing the deleterious effects of random single-point mutations by coevolved compensatory mutations, which restore protein fold, function or interactions damaged by initial ones. This mechanism has been identified as contributing to drug resistance in the HIV-1 Gag polyprotein and especially its capsid proteolytic product, which forms the viral capsid core and plays multifaceted roles in the viral life cycle. Here, we determined the X-ray crystal structure of C-terminal domain of the feline immunodeficiency virus (FIV) capsid and through interspecies analysis elucidate the structural basis of co-evolutionarily and spatially correlated substitutions in capsid sequences, which when otherwise uncoupled and individually substituted into HIV-1 capsid impair virion assembly and infectivity. The ability to circumvent the deleterious effects of single amino acid substitutions by cooperative secondary substitutions allows mutational flexibility that may afford viruses an important survival advantage. The potential of such interspecies structural analysis for preempting viral resistance by identifying such alternative but functionally equivalent patterns is discussed.
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Affiliation(s)
- Aya Khwaja
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
| | - Meytal Galilee
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
| | - Ailie Marx
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
| | - Akram Alian
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
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20
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Lu JX, Bayro MJ, Tycko R. Major Variations in HIV-1 Capsid Assembly Morphologies Involve Minor Variations in Molecular Structures of Structurally Ordered Protein Segments. J Biol Chem 2016; 291:13098-112. [PMID: 27129282 DOI: 10.1074/jbc.m116.720557] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Indexed: 12/13/2022] Open
Abstract
We present the results of solid state nuclear magnetic resonance (NMR) experiments on HIV-1 capsid protein (CA) assemblies with three different morphologies, namely wild-type CA (WT-CA) tubes with 35-60 nm diameters, planar sheets formed by the Arg(18)-Leu mutant (R18L-CA), and R18L-CA spheres with 20-100 nm diameters. The experiments are intended to elucidate molecular structural variations that underlie these variations in CA assembly morphology. We find that multidimensional solid state NMR spectra of (15)N,(13)C-labeled CA assemblies are remarkably similar for the three morphologies, with only small differences in (15)N and (13)C chemical shifts, no significant differences in NMR line widths, and few differences in the number of detectable NMR cross-peaks. Thus, the pronounced differences in morphology do not involve major differences in the conformations and identities of structurally ordered protein segments. Instead, morphological variations are attributable to variations in conformational distributions within disordered segments, which do not contribute to the solid state NMR spectra. Variations in solid state NMR signals from certain amino acid side chains are also observed, suggesting differences in the intermolecular dimerization interface between curved and planar CA lattices, as well as possible differences in intramolecular helix-helix packing.
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Affiliation(s)
- Jun-Xia Lu
- From the Laboratory of Chemical Physics, NIDKK, National Institutes of Health, Bethesda, Maryland 20892-0520
| | - Marvin J Bayro
- From the Laboratory of Chemical Physics, NIDKK, National Institutes of Health, Bethesda, Maryland 20892-0520
| | - Robert Tycko
- From the Laboratory of Chemical Physics, NIDKK, National Institutes of Health, Bethesda, Maryland 20892-0520
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21
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Hagan MF, Zandi R. Recent advances in coarse-grained modeling of virus assembly. Curr Opin Virol 2016; 18:36-43. [PMID: 27016708 DOI: 10.1016/j.coviro.2016.02.012] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 02/29/2016] [Indexed: 01/08/2023]
Affiliation(s)
- Michael F Hagan
- Martin Fisher School of Physics, Brandeis University, Waltham, MA 02453, USA.
| | - Roya Zandi
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA.
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22
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Gupta R, Lu M, Hou G, Caporini MA, Rosay M, Maas W, Struppe J, Suiter C, Ahn J, Byeon IJL, Franks WT, Orwick-Rydmark M, Bertarello A, Oschkinat H, Lesage A, Pintacuda G, Gronenborn AM, Polenova T. Dynamic Nuclear Polarization Enhanced MAS NMR Spectroscopy for Structural Analysis of HIV-1 Protein Assemblies. J Phys Chem B 2016; 120:329-39. [PMID: 26709853 DOI: 10.1021/acs.jpcb.5b12134] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mature infectious HIV-1 virions contain conical capsids composed of CA protein, generated by the proteolytic cleavage cascade of the Gag polyprotein, termed maturation. The mechanism of capsid core formation through the maturation process remains poorly understood. We present DNP-enhanced MAS NMR studies of tubular assemblies of CA and Gag CA-SP1 maturation intermediate and report 20-64-fold sensitivity enhancements due to DNP at 14.1 T. These sensitivity enhancements enabled direct observation of spacer peptide 1 (SP1) resonances in CA-SP1 by dipolar-based correlation experiments, unequivocally indicating that the SP1 peptide is unstructured in assembled CA-SP1 at cryogenic temperatures, corroborating our earlier results. Furthermore, the dependence of DNP enhancements and spectral resolution on magnetic field strength (9.4-18.8 T) and temperature (109-180 K) was investigated. Our results suggest that DNP-based measurements could potentially provide residue-specific dynamics information by allowing for the extraction of the temperature dependence of the anisotropic tensorial or relaxation parameters. With DNP, we were able to detect multiple well-resolved isoleucine side-chain conformers; unique intermolecular correlations across two CA molecules; and functionally relevant conformationally disordered states such as the 14-residue SP1 peptide, none of which are visible at ambient temperatures. The detection of isolated conformers and intermolecular correlations can provide crucial constraints for structure determination of these assemblies. Overall, our results establish DNP-based MAS NMR spectroscopy as an excellent tool for the characterization of HIV-1 assemblies.
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Affiliation(s)
- Rupal Gupta
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
| | - Manman Lu
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
| | - Guangjin Hou
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
| | - Marc A Caporini
- Bruker Biospin Corporation , 15 Fortune Drive, Billerica, Massachusetts United States
| | - Melanie Rosay
- Bruker Biospin Corporation , 15 Fortune Drive, Billerica, Massachusetts United States
| | - Werner Maas
- Bruker Biospin Corporation , 15 Fortune Drive, Billerica, Massachusetts United States
| | - Jochem Struppe
- Bruker Biospin Corporation , 15 Fortune Drive, Billerica, Massachusetts United States
| | - Christopher Suiter
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
| | | | | | - W Trent Franks
- Leibniz-Institut für Molekulare Pharmakologie , Robert-Roessle-Straße 10, 13125 Berlin, Germany
| | - Marcella Orwick-Rydmark
- Leibniz-Institut für Molekulare Pharmakologie , Robert-Roessle-Straße 10, 13125 Berlin, Germany
| | - Andrea Bertarello
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques, UMR 5280 CNRS/Ecole Normale Supérieure de Lyon , 5 rue de la Doua, 69100 Villeurbanne (Lyon), France
| | - Hartmut Oschkinat
- Leibniz-Institut für Molekulare Pharmakologie , Robert-Roessle-Straße 10, 13125 Berlin, Germany
| | - Anne Lesage
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques, UMR 5280 CNRS/Ecole Normale Supérieure de Lyon , 5 rue de la Doua, 69100 Villeurbanne (Lyon), France
| | - Guido Pintacuda
- Centre de RMN à Très Hauts Champs, Institut des Sciences Analytiques, UMR 5280 CNRS/Ecole Normale Supérieure de Lyon , 5 rue de la Doua, 69100 Villeurbanne (Lyon), France
| | | | - Tatyana Polenova
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
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23
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Goh BC, Perilla JR, England MR, Heyrana KJ, Craven RC, Schulten K. Atomic Modeling of an Immature Retroviral Lattice Using Molecular Dynamics and Mutagenesis. Structure 2015; 23:1414-1425. [PMID: 26118533 PMCID: PMC4526393 DOI: 10.1016/j.str.2015.05.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 05/18/2015] [Accepted: 05/25/2015] [Indexed: 10/23/2022]
Abstract
Defining the molecular interaction between Gag proteins in an assembled hexagonal lattice of immature retrovirus particles is crucial for elucidating the mechanisms of virus assembly and maturation. Recent advances in cryo-electron microscopy have yielded subnanometer structural information on the morphology of immature Gag lattices, making computational modeling and simulations feasible for investigating the Gag-Gag interactions at the atomic level. We have examined the structure of Rous sarcoma virus (RSV) using all-atom molecular dynamics simulations and in vitro assembly, to create the first all-atom model of an immature retroviral lattice. Microseconds-long replica exchange molecular dynamics simulation of the spacer peptide (SP)-nucleocapsid (NC) subdomains results in a six-helix bundle with amphipathic properties. The resulting model of the RSV Gag lattice shows features and dynamics of the capsid protein with implications for the maturation process, and confirms the stabilizing role of the upstream and downstream regions of Gag, namely p10 and SP-NC.
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Affiliation(s)
- Boon Chong Goh
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Juan R Perilla
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Matthew R England
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Katrina J Heyrana
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Rebecca C Craven
- Department of Microbiology and Immunology, Penn State University College of Medicine, Hershey, PA 17033, USA
| | - Klaus Schulten
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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24
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Gres AT, Kirby KA, KewalRamani VN, Tanner JJ, Pornillos O, Sarafianos SG. STRUCTURAL VIROLOGY. X-ray crystal structures of native HIV-1 capsid protein reveal conformational variability. Science 2015; 349:99-103. [PMID: 26044298 DOI: 10.1126/science.aaa5936] [Citation(s) in RCA: 181] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 05/27/2015] [Indexed: 12/19/2022]
Abstract
The detailed molecular interactions between native HIV-1 capsid protein (CA) hexamers that shield the viral genome and proteins have been elusive. We report crystal structures describing interactions between CA monomers related by sixfold symmetry within hexamers (intrahexamer) and threefold and twofold symmetry between neighboring hexamers (interhexamer). The structures describe how CA builds hexagonal lattices, the foundation of mature capsids. Lattice structure depends on an adaptable hydration layer modulating interactions among CA molecules. Disruption of this layer alters interhexamer interfaces, highlighting an inherent structural variability. A CA-targeting antiviral affects capsid stability by binding across CA molecules and subtly altering interhexamer interfaces remote to the ligand-binding site. Inherent structural plasticity, hydration layer rearrangement, and effector binding affect capsid stability and have functional implications for the retroviral life cycle.
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Affiliation(s)
- Anna T Gres
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA. Department of Chemistry, University of Missouri, Columbia, MO 65211, USA
| | - Karen A Kirby
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA. Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO 65211, USA
| | - Vineet N KewalRamani
- Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - John J Tanner
- Department of Chemistry, University of Missouri, Columbia, MO 65211, USA. Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA
| | - Stefan G Sarafianos
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA. Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, Columbia, MO 65211, USA. Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA.
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25
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Frank GA, Narayan K, Bess JW, Del Prete GQ, Wu X, Moran A, Hartnell LM, Earl LA, Lifson JD, Subramaniam S. Maturation of the HIV-1 core by a non-diffusional phase transition. Nat Commun 2015; 6:5854. [PMID: 25569620 PMCID: PMC4288007 DOI: 10.1038/ncomms6854] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 11/14/2014] [Indexed: 02/07/2023] Open
Abstract
The formation of the HIV-1 core is the final step in the viral maturation pathway, resulting in the formation of infectious virus. Most current models for HIV-1 core formation suggest that, upon proteolytic cleavage from the immature Gag, capsid (CA) dissociates into the viral interior before reforming into the core. Here we present evidence for an alternate view of core formation by taking advantage of our serendipitous observation of large membrane-enclosed structures in HIV-1 supernatants from infected cells. Cryo-electron tomographic studies show that these structures, which contain ordered arrays of what is likely the membrane-associated matrix protein, contain multiple cores that can be captured at different stages of maturation. Our studies suggest that HIV maturation involves a non-diffusional phase transition in which the detaching layer of the cleaved CA lattice is gradually converted into a roll that ultimately forms the surface of the mature conical core.
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Affiliation(s)
- Gabriel A. Frank
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Kedar Narayan
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Julian W. Bess
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, Maryland 21702, USA
| | - Gregory Q. Del Prete
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, Maryland 21702, USA
| | - Xiongwu Wu
- Laboratory of Computational Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Amy Moran
- National Laboratory of Medicine, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Lisa M. Hartnell
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Lesley A. Earl
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jeffrey D. Lifson
- AIDS and Cancer Virus Program, Leidos Biomedical Research, Inc., Frederick National Laboratory, Frederick, Maryland 21702, USA
| | - Sriram Subramaniam
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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26
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Electron cryotomography studies of maturing HIV-1 particles reveal the assembly pathway of the viral core. J Virol 2014; 89:1267-77. [PMID: 25392219 DOI: 10.1128/jvi.02997-14] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED To better characterize the assembly of the HIV-1 core, we have used electron cryotomography (ECT) to image infected cells and the viral particles cryopreserved next to them. We observed progressive stages of virus assembly and egress, including flower-like flat Gag lattice assemblies, hemispherical budding profiles, and virus buds linked to the plasma membrane via a thin membrane neck. The population of budded viral particles contains immature, maturation-intermediate, and mature core morphologies. Structural characteristics of the maturation intermediates suggest that the core assembly pathway involves the formation of a CA sheet that associates with the condensed ribonucleoprotein (RNP) complex. Our analysis also reveals a correlation between RNP localization within the viral particle and the formation of conical cores, suggesting that the RNP helps drive conical core assembly. Our findings support an assembly pathway for the HIV-1 core that begins with a small CA sheet that associates with the RNP to form the core base, followed by polymerization of the CA sheet along one side of the conical core toward the tip, and then closure around the body of the cone. IMPORTANCE During HIV-1 assembly and release, the Gag polyprotein is organized into a signature hexagonal lattice, termed the immature lattice. To become infectious, the newly budded virus must disassemble the immature lattice by proteolyzing Gag and then reassemble the key proteolytic product, the structural protein p24 (CA), into a distinct, mature hexagonal lattice during a process termed maturation. The mature HIV-1 virus contains a conical capsid that encloses the condensed viral genome at its wide base. Mutations or small molecules that interfere with viral maturation also disrupt viral infectivity. Little is known about the assembly pathway that results in the conical core and genome encapsidation. Here, we have used electron cryotomography to structurally characterize HIV-1 particles that are actively maturing. Based on the morphologies of core assembly intermediates, we propose that CA forms a sheet-like structure that associates with the condensed viral genome to produce the mature infectious conical core.
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27
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Sargeant DP, Deverasetty S, Strong CL, Alaniz IJ, Bartlett A, Brandon NR, Brooks SB, Brown FA, Bufi F, Chakarova M, David RP, Dobritch KM, Guerra HP, Hedden MW, Kumra R, Levitt KS, Mathew KR, Matti R, Maza DQ, Mistry S, Novakovic N, Pomerantz A, Portillo J, Rafalski TF, Rathnayake VR, Rezapour N, Songao S, Tuggle SL, Yousif S, Dorsky DI, Schiller MR. The HIVToolbox 2 web system integrates sequence, structure, function and mutation analysis. PLoS One 2014; 9:e98810. [PMID: 24886930 PMCID: PMC4041786 DOI: 10.1371/journal.pone.0098810] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Accepted: 05/06/2014] [Indexed: 12/15/2022] Open
Abstract
There is enormous interest in studying HIV pathogenesis for improving the treatment of patients with HIV infection. HIV infection has become one of the best-studied systems for understanding how a virus can hijack a cell. To help facilitate discovery, we previously built HIVToolbox, a web system for visual data mining. The original HIVToolbox integrated information for HIV protein sequence, structure, functional sites, and sequence conservation. This web system has been used for almost 40,000 searches. We report improvements to HIVToolbox including new functions and workflows, data updates, and updates for ease of use. HIVToolbox2, is an improvement over HIVToolbox with new functions. HIVToolbox2 has new functionalities focused on HIV pathogenesis including drug-binding sites, drug-resistance mutations, and immune epitopes. The integrated, interactive view enables visual mining to generate hypotheses that are not readily revealed by other approaches. Most HIV proteins form multimers, and there are posttranslational modification and protein-protein interaction sites at many of these multimerization interfaces. Analysis of protease drug binding sites reveals an anatomy of drug resistance with different types of drug-resistance mutations regionally localized on the surface of protease. Some of these drug-resistance mutations have a high prevalence in specific HIV-1 M subtypes. Finally, consolidation of Tat functional sites reveals a hotspot region where there appear to be 30 interactions or posttranslational modifications. A cursory analysis with HIVToolbox2 has helped to identify several global patterns for HIV proteins. An initial analysis with this tool identifies homomultimerization of almost all HIV proteins, functional sites that overlap with multimerization sites, a global drug resistance anatomy for HIV protease, and specific distributions of some DRMs in specific HIV M subtypes. HIVToolbox2 is an open-access web application available at [http://hivtoolbox2.bio-toolkit.com].
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Affiliation(s)
- David P. Sargeant
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Sandeep Deverasetty
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Christy L. Strong
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Izua J. Alaniz
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Alexandria Bartlett
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Nicholas R. Brandon
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Steven B. Brooks
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Frederick A. Brown
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Flaviona Bufi
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Monika Chakarova
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Roxanne P. David
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Karlyn M. Dobritch
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Horacio P. Guerra
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Michael W. Hedden
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Rma Kumra
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Kelvy S. Levitt
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Kiran R. Mathew
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Ray Matti
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Dorothea Q. Maza
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Sabyasachy Mistry
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Nemanja Novakovic
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Austin Pomerantz
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Josue Portillo
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Timothy F. Rafalski
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Viraj R. Rathnayake
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Noura Rezapour
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Sarah Songao
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Sean L. Tuggle
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - Sandy Yousif
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
| | - David I. Dorsky
- Department of Medicine, University of Connecticut Health Center, Farmington, Connecticut, United States of America
| | - Martin R. Schiller
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, Nevada, United States of America
- * E-mail:
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28
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McKinstry WJ, Hijnen M, Tanwar HS, Sparrow LG, Nagarajan S, Pham ST, Mak J. Expression and purification of soluble recombinant full length HIV-1 Pr55(Gag) protein in Escherichia coli. Protein Expr Purif 2014; 100:10-8. [PMID: 24810910 DOI: 10.1016/j.pep.2014.04.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/23/2014] [Accepted: 04/25/2014] [Indexed: 11/17/2022]
Abstract
The HIV-1 Gag precursor protein, Pr55(Gag), is a multi-domain polyprotein that drives HIV-1 assembly. The morphological features of HIV-1 suggested Pr55(Gag) assumes a variety of different conformations during virion assembly and maturation, yet structural determination of HIV-1 Pr55(Gag) has not been possible due to an inability to express and to isolate large amounts of full-length recombinant Pr55(Gag) for biophysical and biochemical analyses. This challenge is further complicated by HIV-1 Gag's natural propensity to multimerize for the formation of viral particle (with ∼2500 Gag molecules per virion), and this has led Pr55(Gag) to aggregate and be expressed as inclusion bodies in a number of in vitro protein expression systems. This study reported the production of a recombinant form of HIV-1 Pr55(Gag) using a bacterial heterologous expression system. Recombinant HIV-1 Pr55(Gag) was expressed with a C-terminal His×6 tag, and purified using a combination of immobilized metal affinity chromatography and size exclusion chromatography. This procedure resulted in the production of milligram quantities of high purity HIV-1 Pr55(Gag) that has a mobility that resembles a trimer in solution using size exclusion chromatography analysis. The high quantity and purity of the full length HIV Gag will be suitable for structural and functional studies to further understand the process of viral assembly, maturation and the development of inhibitors to interfere with the process.
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Affiliation(s)
| | - Marcel Hijnen
- Centre for Virology, Burnet Institute, Melbourne, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Hanumant S Tanwar
- CSIRO Materials Science and Engineering, Parkville, Victoria, Australia; School of Medicine, Deakin University, Geelong, Australia
| | - Lindsay G Sparrow
- CSIRO Materials Science and Engineering, Parkville, Victoria, Australia
| | - Sureshbabu Nagarajan
- School of Medicine, Deakin University, Geelong, Australia; CSIRO, Australian Animal Health Laboratory, Geelong, Australia
| | - Son T Pham
- School of Medicine, Deakin University, Geelong, Australia; CSIRO, Australian Animal Health Laboratory, Geelong, Australia
| | - Johnson Mak
- Centre for Virology, Burnet Institute, Melbourne, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia; School of Medicine, Deakin University, Geelong, Australia; CSIRO, Australian Animal Health Laboratory, Geelong, Australia.
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29
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Abstract
UNLABELLED Purified retroviral Gag proteins can assemble in vitro to form immature virus-like particles (VLPs). By cryoelectron tomography, Rous sarcoma virus VLPs show an organized hexameric lattice consisting chiefly of the capsid (CA) domain, with periodic stalk-like densities below the lattice. We hypothesize that the structure represented by these densities is formed by amino acid residues immediately downstream of the folded CA, namely, the short spacer peptide SP, along with a dozen flanking residues. These 24 residues comprise the SP assembly (SPA) domain, and we propose that neighboring SPA units in a Gag hexamer coalesce to form a six-helix bundle. Using in vitro assembly, alanine scanning mutagenesis, and biophysical analyses, we have further characterized the structure and function of SPA. Most of the amino acid residues in SPA could not be mutated individually without abrogating assembly, with the exception of a few residues near the N and C termini, as well as three hydrophilic residues within SPA. We interpret these results to mean that the amino acids that do not tolerate mutations contribute to higher-order structures in VLPs. Hydrogen-deuterium exchange analyses of unassembled Gag compared that of assembled VLPs showed strong protection at the SPA region, consistent with a higher-order structure. Circular dichroism revealed that a 29mer SPA peptide shifts from a random coil to a helix in a concentration-dependent manner. Analytical ultracentrifugation showed concentration-dependent self-association of the peptide into a hexamer. Taken together, these results provide strong evidence for the formation of a critical six-helix bundle in Gag assembly. IMPORTANCE The structure of a retrovirus like HIV is created by several thousand molecules of the viral Gag protein, which assemble to form the known hexagonal protein lattice in the virus particle. How the Gag proteins pack together in the lattice is incompletely understood. A short segment of Gag known to be critical for proper assembly has been hypothesized to form a six-helix bundle, which may be the nucleating event that leads to lattice formation. The experiments reported here, using the avian Rous sarcoma virus as a model system, further define the nature of this segment of Gag, show that it is in a higher-order structure in the virus particle, and provide the first direct evidence that it forms a six-helix bundle in retrovirus assembly. Such knowledge may provide underpinnings for the development of antiretroviral drugs that interfere with virus assembly.
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30
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Han Y, Hou G, Suiter CL, Ahn J, Byeon IJL, Lipton AS, Burton S, Hung I, Gor'kov PL, Gan Z, Brey W, Rice D, Gronenborn AM, Polenova T. Magic angle spinning NMR reveals sequence-dependent structural plasticity, dynamics, and the spacer peptide 1 conformation in HIV-1 capsid protein assemblies. J Am Chem Soc 2013; 135:17793-803. [PMID: 24164646 DOI: 10.1021/ja406907h] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
A key stage in HIV-1 maturation toward an infectious virion requires sequential proteolytic cleavage of the Gag polyprotein leading to the formation of a conical capsid core that encloses the viral RNA genome and a small complement of proteins. The final step of this process involves severing the SP1 peptide from the CA-SP1 maturation intermediate, which triggers the condensation of the CA protein into the capsid shell. The details of the overall mechanism, including the conformation of the SP1 peptide in CA-SP1, are still under intense debate. In this report, we examine tubular assemblies of CA and the CA-SP1 maturation intermediate using magic angle spinning (MAS) NMR spectroscopy. At magnetic fields of 19.9 T and above, outstanding quality 2D and 3D MAS NMR spectra were obtained for tubular CA and CA-SP1 assemblies, permitting resonance assignments for subsequent detailed structural characterization. Dipolar- and scalar-based correlation experiments unequivocally indicate that SP1 peptide is in a random coil conformation and mobile in the assembled CA-SP1. Analysis of two CA protein sequence variants reveals that, unexpectedly, the conformations of the SP1 tail, the functionally important CypA loop, and the loop preceding helix 8 are modulated by residue variations at distal sites. These findings provide support for the role of SP1 as a trigger of the disassembly of the immature CA capsid for its subsequent de novo reassembly into mature cores and establish the importance of sequence-dependent conformational plasticity in CA assembly.
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Affiliation(s)
- Yun Han
- Department of Chemistry and Biochemistry, University of Delaware , Newark, Delaware 19716, United States
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31
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A two-pronged structural analysis of retroviral maturation indicates that core formation proceeds by a disassembly-reassembly pathway rather than a displacive transition. J Virol 2013; 87:13655-64. [PMID: 24109217 DOI: 10.1128/jvi.01408-13] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Retrovirus maturation involves sequential cleavages of the Gag polyprotein, initially arrayed in a spherical shell, leading to formation of capsids with polyhedral or conical morphology. Evidence suggests that capsids assemble de novo inside maturing virions from dissociated capsid (CA) protein, but the possibility persists of a displacive pathway in which the CA shell remains assembled but is remodeled. Inhibition of the final cleavage between CA and spacer peptide SP1/SP blocks the production of mature capsids. We investigated whether retention of SP might render CA assembly incompetent by testing the ability of Rous sarcoma virus (RSV) CA-SP to assemble in vitro into icosahedral capsids. Capsids were indeed assembled and were indistinguishable from those formed by CA alone, indicating that SP was disordered. We also used cryo-electron tomography to characterize HIV-1 particles produced in the presence of maturation inhibitor PF-46396 or with the cleavage-blocking CA5 mutation. Inhibitor-treated virions have a shell that resembles the CA layer of the immature Gag shell but is less complete. Some CA protein is generated but usually not enough for a mature core to assemble. We propose that inhibitors like PF-46396 bind to the Gag lattice where they deny the protease access to the CA-SP1 cleavage site and prevent the release of CA. CA5 particles, which exhibit no cleavage at the CA-SP1 site, have spheroidal shells with relatively thin walls. It appears that this lattice progresses displacively toward a mature-like state but produces neither conical cores nor infectious virions. These observations support the disassembly-reassembly pathway for core formation.
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32
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Zhao G, Perilla JR, Yufenyuy EL, Meng X, Chen B, Ning J, Ahn J, Gronenborn AM, Schulten K, Aiken C, Zhang P. Mature HIV-1 capsid structure by cryo-electron microscopy and all-atom molecular dynamics. Nature 2013; 497:643-6. [PMID: 23719463 DOI: 10.1038/nature12162] [Citation(s) in RCA: 552] [Impact Index Per Article: 50.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Accepted: 04/05/2013] [Indexed: 12/23/2022]
Abstract
Retroviral capsid proteins are conserved structurally but assemble into different morphologies. The mature human immunodeficiency virus-1 (HIV-1) capsid is best described by a 'fullerene cone' model, in which hexamers of the capsid protein are linked to form a hexagonal surface lattice that is closed by incorporating 12 capsid-protein pentamers. HIV-1 capsid protein contains an amino-terminal domain (NTD) comprising seven α-helices and a β-hairpin, a carboxy-terminal domain (CTD) comprising four α-helices, and a flexible linker with a 310-helix connecting the two structural domains. Structures of the capsid-protein assembly units have been determined by X-ray crystallography; however, structural information regarding the assembled capsid and the contacts between the assembly units is incomplete. Here we report the cryo-electron microscopy structure of a tubular HIV-1 capsid-protein assembly at 8 Å resolution and the three-dimensional structure of a native HIV-1 core by cryo-electron tomography. The structure of the tubular assembly shows, at the three-fold interface, a three-helix bundle with critical hydrophobic interactions. Mutagenesis studies confirm that hydrophobic residues in the centre of the three-helix bundle are crucial for capsid assembly and stability, and for viral infectivity. The cryo-electron-microscopy structures enable modelling by large-scale molecular dynamics simulation, resulting in all-atom models for the hexamer-of-hexamer and pentamer-of-hexamer elements as well as for the entire capsid. Incorporation of pentamers results in closer trimer contacts and induces acute surface curvature. The complete atomic HIV-1 capsid model provides a platform for further studies of capsid function and for targeted pharmacological intervention.
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Affiliation(s)
- Gongpu Zhao
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15260, USA
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33
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Yufenyuy EL, Aiken C. The NTD-CTD intersubunit interface plays a critical role in assembly and stabilization of the HIV-1 capsid. Retrovirology 2013; 10:29. [PMID: 23497318 PMCID: PMC3623829 DOI: 10.1186/1742-4690-10-29] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Accepted: 02/18/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Lentiviruses exhibit a cone-shaped capsid composed of subunits of the viral CA protein. The intrinsic stability of the capsid is critical for HIV-1 infection, since both stabilizing and destabilizing mutations compromise viral infectivity. Structural studies have identified three intersubunit interfaces in the HIV-1 capsid, two of which have been previously studied by mutational analysis. In this present study we analyzed the role of a third interface, that which is formed between the amino terminal domain (NTD) and carboxyl terminal domain (CTD) of adjacent subunits. RESULTS We provided evidence for the presence of the NTD-CTD interface in HIV-1 particles by engineering intersubunit NTD-CTD disulfide crosslinks, resulting in accumulation of disulfide-linked oligomers up to hexamers. We also generated and characterized a panel of HIV-1 mutants containing substitutions at this interface. Some mutants showed processing defects and altered morphology from that of wild type, indicating that the interface is important for capsid assembly. Analysis of these mutants by transmission electron microscopy corroborated the importance of this interface in assembly. Other mutants exhibited quantitative changes in capsid stability, many with unstable capsids, and one mutant with a hyperstable capsid. Analysis of the mutants for their capacity to saturate TRIMCyp-mediated restriction in trans confirmed that the unstable mutants undergo premature uncoating in target cells. All but one of the mutants were markedly attenuated in replication owing to impaired reverse transcription in target cells. CONCLUSIONS Our results demonstrate that the NTD-CTD intersubunit interface is present in the mature HIV-1 capsid and is critical for proper capsid assembly and stability.
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Affiliation(s)
- Ernest L Yufenyuy
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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Bell NM, Lever AML. HIV Gag polyprotein: processing and early viral particle assembly. Trends Microbiol 2013; 21:136-44. [PMID: 23266279 DOI: 10.1016/j.tim.2012.11.006] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2012] [Revised: 11/22/2012] [Accepted: 11/29/2012] [Indexed: 12/22/2022]
Affiliation(s)
- Neil M Bell
- Department of Medicine, University of Cambridge, Level 5, Addenbrooke's Hospital, Hills Road, Cambridge CB2 2QQ, UK
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