1
|
Biswas B, Lai KK, Bracey H, Datta SAK, Harvin D, Sowd GA, Aiken C, Rein A. Essential functions of inositol hexakisphosphate (IP6) in murine leukemia virus replication. mBio 2024; 15:e0115824. [PMID: 38912776 PMCID: PMC11253606 DOI: 10.1128/mbio.01158-24] [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: 04/18/2024] [Accepted: 05/14/2024] [Indexed: 06/25/2024] Open
Abstract
We have investigated the function of inositol hexakisphosphate (IP6) and inositol pentakisphosphate (IP5) in the replication of murine leukemia virus (MLV). While IP6 is known to be critical for the life cycle of HIV-1, its significance in MLV remains unexplored. We find that IP6 is indeed important for MLV replication. It significantly enhances endogenous reverse transcription (ERT) in MLV. Additionally, a pelleting-based assay reveals that IP6 can stabilize MLV cores, thereby facilitating ERT. We find that IP5 and IP6 are packaged in MLV particles. However, unlike HIV-1, MLV depends upon the presence of IP6 and IP5 in target cells for successful infection. This IP6/5 requirement for infection is reflected in impaired reverse transcription observed in IP6/5-deficient cell lines. In summary, our findings demonstrate the importance of capsid stabilization by IP6/5 in the replication of diverse retroviruses; we suggest possible reasons for the differences from HIV-1 that we observed in MLV.IMPORTANCEInositol hexakisphosphate (IP6) is crucial for the assembly and replication of HIV-1. IP6 is packaged in HIV-1 particles and stabilizes the viral core enabling it to synthesize viral DNA early in viral infection. While its importance for HIV-1 is well established, its significance for other retroviruses is unknown. Here we report the role of IP6 in the gammaretrovirus, murine leukemia virus (MLV). We found that like HIV-1, MLV packages IP6, and as in HIV-1, IP6 stabilizes the MLV core thus promoting reverse transcription. Interestingly, we discovered a key difference in the role of IP6 in MLV versus HIV-1: while HIV-1 is not dependent upon IP6 levels in target cells, MLV replication is significantly reduced in IP6-deficient cell lines. We suggest that this difference in IP6 requirements reflects key differences between HIV-1 and MLV replication.
Collapse
Affiliation(s)
- Banhi Biswas
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, Frederick, Maryland, USA
| | - Kin Kui Lai
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, Frederick, Maryland, USA
| | - Harrison Bracey
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Siddhartha A. K. Datta
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, Frederick, Maryland, USA
| | - Demetria Harvin
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, Frederick, Maryland, USA
| | - Gregory A. Sowd
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Christopher Aiken
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Alan Rein
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, Frederick, Maryland, USA
| |
Collapse
|
2
|
Arribas L, Menéndez-Arias L, Betancor G. May I Help You with Your Coat? HIV-1 Capsid Uncoating and Reverse Transcription. Int J Mol Sci 2024; 25:7167. [PMID: 39000271 PMCID: PMC11241228 DOI: 10.3390/ijms25137167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2024] [Revised: 06/26/2024] [Accepted: 06/27/2024] [Indexed: 07/16/2024] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) capsid is a protein core formed by multiple copies of the viral capsid (CA) protein. Inside the capsid, HIV-1 harbours all the viral components required for replication, including the genomic RNA and viral enzymes reverse transcriptase (RT) and integrase (IN). Upon infection, the RT transforms the genomic RNA into a double-stranded DNA molecule that is subsequently integrated into the host chromosome by IN. For this to happen, the viral capsid must open and release the viral DNA, in a process known as uncoating. Capsid plays a key role during the initial stages of HIV-1 replication; therefore, its stability is intimately related to infection efficiency, and untimely uncoating results in reverse transcription defects. How and where uncoating takes place and its relationship with reverse transcription is not fully understood, but the recent development of novel biochemical and cellular approaches has provided unprecedented detail on these processes. In this review, we present the latest findings on the intricate link between capsid stability, reverse transcription and uncoating, the different models proposed over the years for capsid uncoating, and the role played by other cellular factors on these processes.
Collapse
Affiliation(s)
- Laura Arribas
- Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS), Universidad de Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Spain;
| | - Luis Menéndez-Arias
- Centro de Biología Molecular “Severo Ochoa” (Consejo Superior de Investigaciones Científicas & Universidad Autónoma de Madrid), 28049 Madrid, Spain;
| | - Gilberto Betancor
- Instituto Universitario de Investigaciones Biomédicas y Sanitarias (IUIBS), Universidad de Las Palmas de Gran Canaria, 35016 Las Palmas de Gran Canaria, Spain;
| |
Collapse
|
3
|
Scott TM, Arnold LM, Powers JA, McCann DA, Christensen DE, Pereira MJ, Zhou W, Torrez RM, Iwasa JH, Kranzusch PJ, Sundquist WI, Johnson JS. Cell-free assays reveal the HIV-1 capsid protects reverse transcripts from cGAS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.22.590513. [PMID: 38712059 PMCID: PMC11071359 DOI: 10.1101/2024.04.22.590513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Retroviruses can be detected by the innate immune sensor cyclic GMP-AMP synthase (cGAS), which recognizes reverse-transcribed DNA and activates an antiviral response. However, the extent to which HIV-1 shields its genome from cGAS recognition remains unclear. To study this process in mechanistic detail, we reconstituted reverse transcription, genome release, and innate immune sensing of HIV-1 in a cell-free system. We found that wild-type HIV-1 capsids protect their genomes from cGAS even after completion of reverse transcription. Viral DNA could be "deprotected" by thermal stress, capsid mutations, or reduced concentrations of inositol hexakisphosphate (IP6) that destabilize the capsid. Strikingly, capsid inhibitors also disrupted viral cores and dramatically potentiated cGAS activity, both in vitro and in cellular infections. Our results provide biochemical evidence that the HIV-1 capsid lattice conceals the genome from cGAS and that chemical or physical disruption of the viral core can expose HIV-1 DNA and activate innate immune signaling.
Collapse
Affiliation(s)
- Tiana M. Scott
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Lydia M. Arnold
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Jordan A. Powers
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Delaney A. McCann
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Devin E. Christensen
- Department of Biochemistry, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Miguel J. Pereira
- Department of Biochemistry, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Wen Zhou
- Department of Immunology and Microbiology, School of Life Sciences, Southern University of Science and Technology; Shenzhen, Guangdong 518055, China
| | - Rachel M. Torrez
- Department of Biochemistry, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Janet H. Iwasa
- Department of Biochemistry, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Philip J. Kranzusch
- Department of Microbiology, Harvard Medical School; Boston, MA 02115, USA
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute; Boston, MA 02115, USA
| | - Wesley I. Sundquist
- Department of Biochemistry, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| | - Jarrod S. Johnson
- Division of Microbiology and Immunology, Department of Pathology, University of Utah School of Medicine; Salt Lake City, UT 84112, USA
| |
Collapse
|
4
|
McFadden WM, Casey-Moore MC, Bare GAL, Kirby KA, Wen X, Li G, Wang H, Slack RL, Snyder AA, Lorson ZC, Kaufman IL, Cilento ME, Tedbury PR, Gembicky M, Olson AJ, Torbett BE, Sharpless KB, Sarafianos SG. Identification of clickable HIV-1 capsid-targeting probes for viral replication inhibition. Cell Chem Biol 2024; 31:477-486.e7. [PMID: 38518746 PMCID: PMC11257216 DOI: 10.1016/j.chembiol.2024.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 12/15/2023] [Accepted: 02/27/2024] [Indexed: 03/24/2024]
Abstract
Of the targets for HIV-1 therapeutics, the capsid core is a relatively unexploited but alluring drug target due to its indispensable roles throughout virus replication. Because of this, we aimed to identify "clickable" covalent modifiers of the HIV-1 capsid protein (CA) for future functionalization. We screened a library of fluorosulfate compounds that can undergo sulfur(VI) fluoride exchange (SuFEx) reactions, and five compounds were identified as hits. These molecules were further characterized for antiviral effects. Several compounds impacted in vitro capsid assembly. One compound, BBS-103, covalently bound CA via a SuFEx reaction to Tyr145 and had antiviral activity in cell-based assays by perturbing virus production, but not uncoating. The covalent binding of compounds that target the HIV-1 capsid could aid in the future design of antiretroviral drugs or chemical probes that will help study aspects of HIV-1 replication.
Collapse
Affiliation(s)
- William M McFadden
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Mary C Casey-Moore
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | - Grant A L Bare
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Karen A Kirby
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA; Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | - Xin Wen
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Gencheng Li
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Hua Wang
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ryan L Slack
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Alexa A Snyder
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Zachary C Lorson
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Isabella L Kaufman
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Maria E Cilento
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA
| | - Philip R Tedbury
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA; Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | - Milan Gembicky
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92521, United States
| | - Arthur J Olson
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Bruce E Torbett
- Center for Immunity and Immunotherapies, Seattle Children's Research Institute, Seattle, WA 98101, USA; Department of Pediatrics, University of Washington School of Medicine, Seattle, WA 98101, USA
| | - K Barry Sharpless
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Stefan G Sarafianos
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, 1760 Haygood Drive NE, Atlanta, GA 30322, USA; Children's Healthcare of Atlanta, Atlanta, GA 30322, USA; Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA; Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO 65212, USA.
| |
Collapse
|
5
|
Garza CM, Holcomb M, Santos-Martins D, Torbett BE, Forli S. IP6 and PF74 affect HIV-1 Capsid Stability through Modulation of Hexamer-Hexamer Tilt Angle Preference. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.11.584513. [PMID: 38559213 PMCID: PMC10979974 DOI: 10.1101/2024.03.11.584513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The HIV-1 capsid is an irregularly shaped complex of about 1200 protein chains containing the viral genome and several viral proteins. Together, these components are the key to unlocking passage into the nucleus, allowing for permanent integration of the viral genome into the host cell genome. Recent interest into the role of the capsid in viral replication has been driven by the approval of the first-in-class drug lenacapavir, which marks the first drug approved to target a non-enzymatic HIV-1 viral protein. In addition to lenacapavir, other small molecules such as the drug-like compound PF74, and the anionic sugar inositolhexakisphosphate (IP6), are known to impact capsid stability, and although this is widely accepted as a therapeutic effect, the mechanisms through which they do so remain unknown. In this study, we employed a systematic atomistic simulation approach to study the impact of molecules bound to hexamers at the central pore (IP6) and the FG-binding site (PF74) on capsid oligomer dynamics, compared to apo hexamers and pentamers. We found that neither small molecule had a sizeable impact on the free energy of binding of the interface between neighboring hexamers but that both had impacts on the free energy profiles of performing angular deformations to the pair of oligomers akin to the variations in curvature along the irregular surface of the capsid. The IP6 cofactor, on one hand, stabilizes a pair of neighboring hexamers in their flattest configurations, whereas without IP6, the hexamers prefer a high tilt angle between them. On the other hand, having PF74 bound introduces a strong preference for intermediate tilt angles. These results suggest that structural instability is a natural feature of the HIV-1 capsid which is modulated by molecules bound in either the central pore or the FG-binding site. Such modulators, despite sharing many of the same effects on non-bonded interactions at the various protein-protein interfaces, have decidedly different effects on the flexibility of the complex. This study provides a detailed model of the HIV-1 capsid and its interactions with small molecules, informing structure-based drug design, as well as experimental design and interpretation.
Collapse
|
6
|
Biswas B, Lai KK, Bracey H, Datta SA, Harvin D, Sowd GA, Aiken C, Rein A. Essential functions of Inositol hexakisphosphate (IP6) in Murine Leukemia Virus replication. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.27.581940. [PMID: 38464197 PMCID: PMC10925174 DOI: 10.1101/2024.02.27.581940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
We have investigated the function of inositol hexakisphosphate (IP6) and inositol pentakisphosphate (IP5) in the replication of murine leukemia virus (MLV). While IP6 is known to be critical for the life cycle of HIV-1, its significance in MLV remains unexplored. We find that IP6 is indeed important for MLV replication. It significantly enhances endogenous reverse transcription (ERT) in MLV. Additionally, a pelleting-based assay reveals that IP6 can stabilize MLV cores, thereby facilitating ERT. We find that IP5 and IP6 are packaged in MLV particles. However, unlike HIV-1, MLV depends upon the presence of IP6 and IP5 in target cells for successful infection. This IP6/5 requirement for infection is reflected in impaired reverse transcription observed in IP6/5-deficient cell lines. In summary, our findings demonstrate the importance of capsid stabilization by IP6/5 in the replication of diverse retroviruses; we suggest possible reasons for the differences from HIV-1 that we observed in MLV.
Collapse
Affiliation(s)
- Banhi Biswas
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, P.O. Box B, Frederick, MD 21702-1201, USA
| | - Kin Kui Lai
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, P.O. Box B, Frederick, MD 21702-1201, USA
| | - Harrison Bracey
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232-3263, USA
| | - Siddhartha A.K. Datta
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, P.O. Box B, Frederick, MD 21702-1201, USA
| | - Demetria Harvin
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, P.O. Box B, Frederick, MD 21702-1201, USA
| | - Gregory A. Sowd
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232-3263, USA
| | - Christopher Aiken
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232-3263, USA
| | - Alan Rein
- HIV Dynamics and Replication Program, National Cancer Institute-Frederick, P.O. Box B, Frederick, MD 21702-1201, USA
| |
Collapse
|
7
|
Faysal KMR, Walsh JC, Renner N, Márquez CL, Shah VB, Tuckwell AJ, Christie MP, Parker MW, Turville SG, Towers GJ, James LC, Jacques DA, Böcking T. Pharmacologic hyperstabilisation of the HIV-1 capsid lattice induces capsid failure. eLife 2024; 13:e83605. [PMID: 38347802 PMCID: PMC10863983 DOI: 10.7554/elife.83605] [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: 09/21/2022] [Accepted: 01/12/2024] [Indexed: 02/15/2024] Open
Abstract
The HIV-1 capsid has emerged as a tractable target for antiretroviral therapy. Lenacapavir, developed by Gilead Sciences, is the first capsid-targeting drug approved for medical use. Here, we investigate the effect of lenacapavir on HIV capsid stability and uncoating. We employ a single particle approach that simultaneously measures capsid content release and lattice persistence. We demonstrate that lenacapavir's potent antiviral activity is predominantly due to lethal hyperstabilisation of the capsid lattice and resultant loss of compartmentalisation. This study highlights that disrupting capsid metastability is a powerful strategy for the development of novel antivirals.
Collapse
Affiliation(s)
- KM Rifat Faysal
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, UNSWSydneyAustralia
| | - James C Walsh
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, UNSWSydneyAustralia
| | - Nadine Renner
- MRC Laboratory of Molecular BiologyCambridgeUnited Kingdom
| | - Chantal L Márquez
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, UNSWSydneyAustralia
| | - Vaibhav B Shah
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, UNSWSydneyAustralia
| | - Andrew J Tuckwell
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, UNSWSydneyAustralia
| | - Michelle P Christie
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of MelbourneMelbourneAustralia
| | - Michael W Parker
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of MelbourneMelbourneAustralia
- Structural Biology Unit, St. Vincent’s Institute of Medical ResearchFitzroyAustralia
| | | | - Greg J Towers
- Division of Infection and Immunity, University College LondonLondonUnited Kingdom
| | - Leo C James
- MRC Laboratory of Molecular BiologyCambridgeUnited Kingdom
| | - David A Jacques
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, UNSWSydneyAustralia
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science, School of Biomedical Sciences, UNSWSydneyAustralia
| |
Collapse
|
8
|
Jang S, Engelman AN. Capsid-host interactions for HIV-1 ingress. Microbiol Mol Biol Rev 2023; 87:e0004822. [PMID: 37750702 PMCID: PMC10732038 DOI: 10.1128/mmbr.00048-22] [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] [Indexed: 09/27/2023] Open
Abstract
The HIV-1 capsid, composed of approximately 1,200 copies of the capsid protein, encases genomic RNA alongside viral nucleocapsid, reverse transcriptase, and integrase proteins. After cell entry, the capsid interacts with a myriad of host factors to traverse the cell cytoplasm, pass through the nuclear pore complex (NPC), and then traffic to chromosomal sites for viral DNA integration. Integration may very well require the dissolution of the capsid, but where and when this uncoating event occurs remains hotly debated. Based on size constraints, a long-prevailing view was that uncoating preceded nuclear transport, but recent research has indicated that the capsid may remain largely intact during nuclear import, with perhaps some structural remodeling required for NPC traversal. Completion of reverse transcription in the nucleus may further aid capsid uncoating. One canonical type of host factor, typified by CPSF6, leverages a Phe-Gly (FG) motif to bind capsid. Recent research has shown these peptides reside amid prion-like domains (PrLDs), which are stretches of protein sequence devoid of charged residues. Intermolecular PrLD interactions along the exterior of the capsid shell impart avid host factor binding for productive HIV-1 infection. Herein we overview capsid-host interactions implicated in HIV-1 ingress and discuss important research questions moving forward. Highlighting clinical relevance, the long-acting ultrapotent inhibitor lenacapavir, which engages the same capsid binding pocket as FG host factors, was recently approved to treat people living with HIV.
Collapse
Affiliation(s)
- Sooin Jang
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Alan N. Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
9
|
Badieyan S, Lichon D, Andreas MP, Gillies JP, Peng W, Shi J, DeSantis ME, Aiken CR, Böcking T, Giessen TW, Campbell EM, Cianfrocco MA. HIV-1 binds dynein directly to hijack microtubule transport machinery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.29.555335. [PMID: 37693451 PMCID: PMC10491134 DOI: 10.1101/2023.08.29.555335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Viruses exploit host cytoskeletal elements and motor proteins for trafficking through the dense cytoplasm. Yet the molecular mechanism that describes how viruses connect to the motor machinery is unknown. Here, we demonstrate the first example of viral microtubule trafficking from purified components: HIV-1 hijacking microtubule transport machinery. We discover that HIV-1 directly binds to the retrograde microtubule-associated motor, dynein, and not via a cargo adaptor, as previously suggested. Moreover, we show that HIV-1 motility is supported by multiple, diverse dynein cargo adaptors as HIV-1 binds to dynein light and intermediate chains on dynein's tail. Further, we demonstrate that multiple dynein motors tethered to rigid cargoes, like HIV-1 capsids, display reduced motility, distinct from the behavior of multiple motors on membranous cargoes. Our results introduce a new model of viral trafficking wherein a pathogen opportunistically 'hijacks' the microtubule transport machinery for motility, enabling multiple transport pathways through the host cytoplasm.
Collapse
Affiliation(s)
| | - Drew Lichon
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, IL, USA
| | - Michael P Andreas
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - John P Gillies
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Sciences, and the Arts, University of Michigan, Ann Arbor, MI USA
| | - Wang Peng
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Jiong Shi
- Department of Pathology, Microbiology, and Immunology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Morgan E DeSantis
- Department of Molecular, Cellular, and Developmental Biology, College of Literature, Sciences, and the Arts, University of Michigan, Ann Arbor, MI USA
| | - Christopher R Aiken
- Department of Pathology, Microbiology, and Immunology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW Sydney, Sydney, New South Wales, Australia
| | - Tobias W Giessen
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Edward M Campbell
- Department of Microbiology and Immunology, Stritch School of Medicine, Loyola University Chicago, IL, USA
| | - Michael A Cianfrocco
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
- Department of Biological Chemistry, Michigan Medicine, University of Michigan, Ann Arbor, MI, USA
| |
Collapse
|
10
|
Padron A, Prakash P, Pandhare J, Luban J, Aiken C, Balasubramaniam M, Dash C. Emerging role of cyclophilin A in HIV-1 infection: from producer cell to the target cell nucleus. J Virol 2023; 97:e0073223. [PMID: 37843371 PMCID: PMC10688351 DOI: 10.1128/jvi.00732-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2023] Open
Abstract
The HIV-1 genome encodes a small number of proteins with structural, enzymatic, regulatory, and accessory functions. These viral proteins interact with a number of host factors to promote the early and late stages of HIV-1 infection. During the early stages of infection, interactions between the viral proteins and host factors enable HIV-1 to enter the target cell, traverse the cytosol, dock at the nuclear pore, gain access to the nucleus, and integrate into the host genome. Similarly, the viral proteins recruit another set of host factors during the late stages of infection to orchestrate HIV-1 transcription, translation, assembly, and release of progeny virions. Among the host factors implicated in HIV-1 infection, Cyclophilin A (CypA) was identified as the first host factor to be packaged within HIV-1 particles. It is now well established that CypA promotes HIV-1 infection by directly binding to the viral capsid. Mechanistic models to pinpoint CypA's role have spanned from an effect in the producer cell to the early steps of infection in the target cell. In this review, we will describe our understanding of the role(s) of CypA in HIV-1 infection, highlight the current knowledge gaps, and discuss the potential role of this host factor in the post-nuclear entry steps of HIV-1 infection.
Collapse
Affiliation(s)
- Adrian Padron
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
- School of Graduate Studies, Meharry Medical College, Nashville, Tennessee, USA
| | - Prem Prakash
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Pharmacology and Neuroscience, Meharry Medical College, Nashville, Tennessee, USA
| | - Jui Pandhare
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
- School of Graduate Studies, Meharry Medical College, Nashville, Tennessee, USA
| | - Jeremy Luban
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Chris Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Muthukumar Balasubramaniam
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Pharmacology and Neuroscience, Meharry Medical College, Nashville, Tennessee, USA
| | - Chandravanu Dash
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Pharmacology and Neuroscience, Meharry Medical College, Nashville, Tennessee, USA
| |
Collapse
|
11
|
Cilento ME, Wen X, Reeve AB, Ukah OB, Snyder AA, Carrillo CM, Smith CP, Edwards K, Wahoski CC, Kitzler DR, Kodama EN, Mitsuya H, Parniak MA, Tedbury PR, Sarafianos SG. HIV-1 Resistance to Islatravir/Tenofovir Combination Therapy in Wild-Type or NRTI-Resistant Strains of Diverse HIV-1 Subtypes. Viruses 2023; 15:1990. [PMID: 37896768 PMCID: PMC10612037 DOI: 10.3390/v15101990] [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: 08/09/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 10/29/2023] Open
Abstract
Tenofovir disoproxil fumarate (TDF) and islatravir (ISL, 4'-ethynyl-2-fluoro-2'-deoxyadensine, or MK-8591) are highly potent nucleoside reverse transcriptase inhibitors. Resistance to TDF and ISL is conferred by K65R and M184V, respectively. Furthermore, K65R and M184V increase sensitivity to ISL and TDF, respectively. Therefore, these two nucleoside analogs have opposing resistance profiles and could present a high genetic barrier to resistance. To explore resistance to TDF and ISL in combination, we performed passaging experiments with HIV-1 WT, K65R, or M184V in the presence of ISL and TDF. We identified K65R, M184V, and S68G/N mutations. The mutant most resistant to ISL was S68N/M184V, yet it remained susceptible to TDF. To further confirm our cellular findings, we implemented an endogenous reverse transcriptase assay to verify in vitro potency. To better understand the impact of these resistance mutations in the context of global infection, we determined potency of ISL and TDF against HIV subtypes A, B, C, D, and circulating recombinant forms (CRF) 01_AE and 02_AG with and without resistance mutations. In all isolates studied, we found K65R imparted hypersensitivity to ISL whereas M184V conferred resistance. We demonstrated that the S68G polymorphism can enhance fitness of drug-resistant mutants in some genetic backgrounds. Collectively, the data suggest that the opposing resistance profiles of ISL and TDF suggest that a combination of the two drugs could be a promising drug regimen for the treatment of patients infected with any HIV-1 subtype, including those who have failed 3TC/FTC-based therapies.
Collapse
Affiliation(s)
- Maria E. Cilento
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Xin Wen
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Aaron B. Reeve
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Obiaara B. Ukah
- CS Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Alexa A. Snyder
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ciro M. Carrillo
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Cole P. Smith
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Kristin Edwards
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Claudia C. Wahoski
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Deborah R. Kitzler
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Eiichi N. Kodama
- Division of Infectious Disease, International Institute of Disaster Science, Tohoku University, Sendai 980-8572, Japan
| | - Hiroaki Mitsuya
- Department of Refractory Viral Infections, National Center for Global Health & Medicine Research Institute, Tokyo 162-8655, Japan
- Experimental Retrovirology Section, HIV and AIDS Malignancy Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Clinical Sciences, Kumamoto University Hospital, Kumamoto 860-8556, Japan
| | - Michael A. Parniak
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219, USA
| | - Philip R. Tedbury
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Stefan G. Sarafianos
- Center for ViroScience and Cure, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| |
Collapse
|
12
|
Sowd GA, Shi J, Fulmer A, Aiken C. HIV-1 capsid stability enables inositol phosphate-independent infection of target cells and promotes integration into genes. PLoS Pathog 2023; 19:e1011423. [PMID: 37267431 PMCID: PMC10266667 DOI: 10.1371/journal.ppat.1011423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 06/14/2023] [Accepted: 05/14/2023] [Indexed: 06/04/2023] Open
Abstract
The mature HIV-1 capsid is stabilized by host and viral determinants. The capsid protein CA binds to the cellular metabolites inositol hexakisphosphate (IP6) and its precursor inositol (1, 3, 4, 5, 6) pentakisphosphate (IP5) to stabilize the mature capsid. In target cells, capsid destabilization by the antiviral compounds lenacapavir and PF74 reveals a HIV-1 infectivity defect due to IP5/IP6 (IP5/6) depletion. To test whether intrinsic HIV-1 capsid stability and/or host factor binding determines HIV-1 insensitivity to IP5/6 depletion, a panel of CA mutants was assayed for infection of IP5/6-depleted T cells and wildtype cells. Four CA mutants with unstable capsids exhibited dependence on host IP5/6 for infection and reverse transcription (RTN). Adaptation of one such mutant, Q219A, by spread in culture resulted in Vpu truncation and a capsid three-fold interface mutation, T200I. T200I increased intrinsic capsid stability as determined by in vitro uncoating of purified cores and partially reversed the IP5/6-dependence in target cells for each of the four CA mutants. T200I further rescued the changes to lenacapavir sensitivity associated with the parental mutation. The premature dissolution of the capsid caused by the IP5/6-dependent mutations imparted a unique defect in integration targeting that was rescued by T200I. Collectively, these results demonstrate that T200I restored other capsid functions after RTN for the panel of mutants. Thus, the hyperstable T200I mutation stabilized the instability defects imparted by the parental IP5/6-dependent CA mutation. The contribution of Vpu truncation to mutant adaptation was linked to BST-2 antagonization, suggesting that cell-to-cell transfer promoted replication of the mutants. We conclude that interactions at the three-fold interface are adaptable, key mediators of capsid stability in target cells and are able to antagonize even severe capsid instability to promote infection.
Collapse
Affiliation(s)
- Gregory A. Sowd
- Department of Pathology, Microbiology, and Immunology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jiong Shi
- Department of Pathology, Microbiology, and Immunology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Ashley Fulmer
- Department of Pathology, Microbiology, and Immunology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Christopher Aiken
- Department of Pathology, Microbiology, and Immunology, Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| |
Collapse
|
13
|
Papa G, Albecka A, Mallery D, Vaysburd M, Renner N, James LC. IP6-stabilised HIV capsids evade cGAS/STING-mediated host immune sensing. EMBO Rep 2023; 24:e56275. [PMID: 36970882 PMCID: PMC10157305 DOI: 10.15252/embr.202256275] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 03/06/2023] [Accepted: 03/10/2023] [Indexed: 03/29/2023] Open
Abstract
HIV-1 uses inositol hexakisphosphate (IP6) to build a metastable capsid capable of delivering its genome into the host nucleus. Here, we show that viruses that are unable to package IP6 lack capsid protection and are detected by innate immunity, resulting in the activation of an antiviral state that inhibits infection. Disrupting IP6 enrichment results in defective capsids that trigger cytokine and chemokine responses during infection of both primary macrophages and T-cell lines. Restoring IP6 enrichment with a single mutation rescues the ability of HIV-1 to infect cells without being detected. Using a combination of capsid mutants and CRISPR-derived knockout cell lines for RNA and DNA sensors, we show that immune sensing is dependent upon the cGAS-STING axis and independent of capsid detection. Sensing requires the synthesis of viral DNA and is prevented by reverse transcriptase inhibitors or reverse transcriptase active-site mutation. These results demonstrate that IP6 is required to build capsids that can successfully transit the cell and avoid host innate immune sensing.
Collapse
Affiliation(s)
- Guido Papa
- MRC Laboratory of Molecular Biology, Protein & Nucleic Acid DivisionCambridgeUK
| | - Anna Albecka
- MRC Laboratory of Molecular Biology, Protein & Nucleic Acid DivisionCambridgeUK
| | - Donna Mallery
- MRC Laboratory of Molecular Biology, Protein & Nucleic Acid DivisionCambridgeUK
| | - Marina Vaysburd
- MRC Laboratory of Molecular Biology, Protein & Nucleic Acid DivisionCambridgeUK
| | - Nadine Renner
- MRC Laboratory of Molecular Biology, Protein & Nucleic Acid DivisionCambridgeUK
| | - Leo C James
- MRC Laboratory of Molecular Biology, Protein & Nucleic Acid DivisionCambridgeUK
| |
Collapse
|
14
|
Identification of New L-Heptanoylphosphatidyl Inositol Pentakisphosphate Derivatives Targeting the Interaction with HIV-1 Gag by Molecular Modelling Studies. Pharmaceuticals (Basel) 2022; 15:ph15101255. [PMID: 36297367 PMCID: PMC9610595 DOI: 10.3390/ph15101255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Revised: 09/29/2022] [Accepted: 10/08/2022] [Indexed: 11/16/2022] Open
Abstract
The HIV-1 Gag protein binds to the host cell membrane and assembles into immature particles. Then, in the course of immature virion budding, activated protease cleaves Gag into its main components: MA, CA, NC, and p6 proteins. The highly basic residues of MA predominantly interact with the acidic head of phosphatidyl-inositol-4,5-bisphosphate (PI(4,5)P2) inserted into the membrane. Our research group developed L-Heptanoylphosphatidyl Inositol Pentakisphosphate (L-HIPPO) and previously confirmed that this compound bound to the MA more strongly than PI(4,5)P2 and inositol hexakisphosphate (IP6) did. Therefore, herein we rationally designed eight new L-HIPPO derivatives based on the fact that the most changeable parts of L-HIPPO were two acyl chains. After that, we employed molecular docking for eight compounds via Maestro software using high-resolution crystal structures of MA in complex with IP6 (PDB IDs: 7E1I, 7E1J, and 7E1K), which were recently elucidated by our research group. The most promising docking scores were obtained with benzene-inserted compounds. Thus, we generated a library containing 213 new aromatic group-inserted L-HIPPO derivatives and performed the same molecular docking procedure. According to the results, we determined the nine new L-HIPPO derivatives most effectively binding to the MA with the most favorable scoring functions and pharmacokinetic properties for further exploration.
Collapse
|
15
|
Müller TG, Zila V, Müller B, Kräusslich HG. Nuclear Capsid Uncoating and Reverse Transcription of HIV-1. Annu Rev Virol 2022; 9:261-284. [PMID: 35704745 DOI: 10.1146/annurev-virology-020922-110929] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
After cell entry, human immunodeficiency virus type 1 (HIV-1) replication involves reverse transcription of the RNA genome, nuclear import of the subviral complex without nuclear envelope breakdown, and integration of the viral complementary DNA into the host genome. Here, we discuss recent evidence indicating that completion of reverse transcription and viral genome uncoating occur in the nucleus rather than in the cytoplasm, as previously thought, and suggest a testable model for nuclear import and uncoating. Multiple recent studies indicated that the cone-shaped capsid, which encases the genome and replication proteins, not only serves as a reaction container for reverse transcription and as a shield from innate immune sensors but also may constitute the elusive HIV-1 nuclear import factor. Rupture of the capsid may be triggered in the nucleus by completion of reverse transcription, by yet-unknown nuclear factors, or by physical damage, and it appears to occur in close temporal and spatial association with the integration process. Expected final online publication date for the Annual Review of Virology, Volume 9 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- Thorsten G Müller
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany;
| | - Vojtech Zila
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany;
| | - Barbara Müller
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany;
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Heidelberg University, Heidelberg, Germany; .,German Center for Infection Research, Heidelberg, Germany
| |
Collapse
|
16
|
Insights into HIV uncoating from single-particle imaging techniques. Biophys Rev 2022; 14:23-32. [PMID: 35340594 PMCID: PMC8921429 DOI: 10.1007/s12551-021-00922-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 11/23/2021] [Indexed: 01/13/2023] Open
Abstract
Human immunodeficiency virus (HIV) is the most extensively researched human pathogen. Despite this massive scientific endeavour, several fundamental viral processes remain enigmatic. One such critical process is uncoating-the event that releases the viral genome from the proteinaceous shell of the capsid during infection. While this process is conceptually simple, the molecular underpinnings, timing, regulation, and cellular location of uncoating remain contentious. This review describes the hurdles that have limited our understanding in this area and presents recently deployed in vitro and in cellulo techniques that have been developed expressly with the aim of directly visualising capsid uncoating at the single-particle level and understanding the mechanics behind this essential aspect of HIV infection.
Collapse
|
17
|
Gruenke PR, Aneja R, Welbourn S, Ukah OB, Sarafianos SG, Burke DH, Lange MJ. Selection and identification of an RNA aptamer that specifically binds the HIV-1 capsid lattice and inhibits viral replication. Nucleic Acids Res 2022; 50:1701-1717. [PMID: 35018437 PMCID: PMC8860611 DOI: 10.1093/nar/gkab1293] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/23/2021] [Accepted: 12/16/2021] [Indexed: 01/25/2023] Open
Abstract
The HIV-1 capsid core participates in several replication processes. The mature capsid core is a lattice composed of capsid (CA) monomers thought to assemble first into CA dimers, then into ∼250 CA hexamers and 12 CA pentamers. CA assembly requires conformational flexibility of each unit, resulting in the presence of unique, solvent-accessible surfaces. Significant advances have improved our understanding of the roles of the capsid core in replication; however, the contributions of individual CA assembly forms remain unclear and there are limited tools available to evaluate these forms in vivo. Here, we have selected aptamers that bind CA lattice tubes. We describe aptamer CA15-2, which selectively binds CA lattice, but not CA monomer or CA hexamer, suggesting that it targets an interface present and accessible only on CA lattice. CA15-2 does not compete with PF74 for binding, indicating that it likely binds a non-overlapping site. Furthermore, CA15-2 inhibits HIV-1 replication when expressed in virus producer cells, but not target cells, suggesting that it binds a biologically-relevant site during virus production that is either not accessible during post-entry replication steps or is accessible but unaltered by aptamer binding. Importantly, CA15-2 represents the first aptamer that specifically recognizes the HIV-1 CA lattice.
Collapse
Affiliation(s)
- Paige R Gruenke
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA.,Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA
| | - Rachna Aneja
- Department of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA
| | - Sarah Welbourn
- Emory Vaccine Center and Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, USA
| | - Obiaara B Ukah
- Department of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA
| | - Stefan G Sarafianos
- Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Donald H Burke
- Department of Biochemistry, University of Missouri, Columbia, MO 65211, USA.,Bond Life Sciences Center, University of Missouri, Columbia, MO 65211, USA.,Department of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA
| | - Margaret J Lange
- Department of Molecular Microbiology & Immunology, School of Medicine, University of Missouri, Columbia, MO 65211, USA
| |
Collapse
|
18
|
Ricaña CL, Dick RA. Inositol Phosphates and Retroviral Assembly: A Cellular Perspective. Viruses 2021; 13:v13122516. [PMID: 34960784 PMCID: PMC8703376 DOI: 10.3390/v13122516] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/09/2021] [Accepted: 12/11/2021] [Indexed: 12/13/2022] Open
Abstract
Understanding the molecular mechanisms of retroviral assembly has been a decades-long endeavor. With the recent discovery of inositol hexakisphosphate (IP6) acting as an assembly co-factor for human immunodeficiency virus (HIV), great strides have been made in retroviral research. In this review, the enzymatic pathways to synthesize and metabolize inositol phosphates (IPs) relevant to retroviral assembly are discussed. The functions of these enzymes and IPs are outlined in the context of the cellular biology important for retroviruses. Lastly, the recent advances in understanding the role of IPs in retroviral biology are surveyed.
Collapse
|
19
|
HIV-1 CA Inhibitors Are Antagonized by Inositol Phosphate Stabilization of the Viral Capsid in Cells. J Virol 2021; 95:e0144521. [PMID: 34613803 PMCID: PMC8610598 DOI: 10.1128/jvi.01445-21] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The HIV-1 capsid, composed of the CA protein, is the target of the novel antiretroviral drug lenacapavir (LCV). CA inhibitors block host factor binding and alter capsid stability to prevent nuclear entry and reverse transcription (RTN), respectively. Capsid stability is mediated in vitro by binding to the host cell metabolite inositol hexakisphosphate (IP6). IP6 depletion in target cells has little effect on HIV-1 infection. We hypothesized that capsid-altering concentrations of CA inhibitors might reveal an effect of IP6 depletion on HIV-1 infection in target cells. To test this, we studied the effects of IP6 depletion on inhibition of infection by the CA inhibitors PF74 and LCV. At low doses of either compound that affect HIV-1 nuclear entry, no effect of IP6 depletion on antiviral activity was observed. Increased antiviral activity was observed in IP6-depleted cells at inhibitor concentrations that affect capsid stability, correlating with increased RTN inhibition. Assays of uncoating and endogenous RTN of purified cores in vitro provided additional support. Our results show that inositol phosphates stabilize the HIV-1 capsid in target cells, thereby dampening the antiviral effects of capsid-targeting antiviral compounds. We propose that targeting of the IP6-binding site in conjunction with CA inhibitors will lead to robust antiretroviral therapy (ART). IMPORTANCE HIV-1 infection and subsequent depletion of CD4+ T cells result in AIDS. Antiretroviral therapy treatment of infected individuals prevents progression to AIDS. The HIV-1 capsid has recently become an ART target. Capsid inhibitors block HIV-1 infection at multiple steps, offering advantages over current ART. The cellular metabolite inositol hexakisphosphate (IP6) binds the HIV-1 capsid, stabilizing it in vitro. However, the function of this interaction in target cells is unclear. Our results imply that IP6 stabilizes the incoming HIV-1 capsid in cells, thus limiting the antiviral efficiency of capsid-destabilizing antivirals. We present a model of capsid inhibitor function and propose that targeting of the IP6-binding site in conjunction with capsid inhibitors currently in development will lead to more robust ART.
Collapse
|
20
|
Ni T, Zhu Y, Yang Z, Xu C, Chaban Y, Nesterova T, Ning J, Böcking T, Parker MW, Monnie C, Ahn J, Perilla JR, Zhang P. Structure of native HIV-1 cores and their interactions with IP6 and CypA. SCIENCE ADVANCES 2021; 7:eabj5715. [PMID: 34797722 PMCID: PMC8604400 DOI: 10.1126/sciadv.abj5715] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Accepted: 10/01/2021] [Indexed: 05/24/2023]
Abstract
The viral capsid plays essential roles in HIV replication and is a major platform engaging host factors. To overcome challenges in study native capsid structure, we used the perfringolysin O to perforate the membrane of HIV-1 particles, thus allowing host proteins and small molecules to access the native capsid while improving cryo–electron microscopy image quality. Using cryo–electron tomography and subtomogram averaging, we determined the structures of native capsomers in the presence and absence of inositol hexakisphosphate (IP6) and cyclophilin A and constructed an all-atom model of a complete HIV-1 capsid. Our structures reveal two IP6 binding sites and modes of cyclophilin A interactions. Free energy calculations substantiate the two binding sites at R18 and K25 and further show a prohibitive energy barrier for IP6 to pass through the pentamer. Our results demonstrate that perfringolysin O perforation is a valuable tool for structural analyses of enveloped virus capsids and interactions with host cell factors.
Collapse
Affiliation(s)
- Tao Ni
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Yanan Zhu
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Zhengyi Yang
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - Chaoyi Xu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - Yuriy Chaban
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - Tanya Nesterova
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - Jiying Ning
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Till Böcking
- EMBL Australia Node in Single Molecule Science and ARC Centre of Excellence in Advanced Molecular Imaging, School of Medical Sciences, UNSW, Sydney, Australia
| | - Michael W. Parker
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia
- St. Vincent’s Institute of Medical Research, Fitzroy, Victoria 3065, Australia
| | - Christina Monnie
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jinwoo Ahn
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Juan R. Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, USA
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
- 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
| |
Collapse
|
21
|
Shen Q, Wu C, Freniere C, Tripler TN, Xiong Y. Nuclear Import of HIV-1. Viruses 2021; 13:2242. [PMID: 34835048 PMCID: PMC8619967 DOI: 10.3390/v13112242] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/26/2021] [Accepted: 11/01/2021] [Indexed: 12/12/2022] Open
Abstract
The delivery of the HIV-1 genome into the nucleus is an indispensable step in retroviral infection of non-dividing cells, but the mechanism of HIV-1 nuclear import has been a longstanding debate due to controversial experimental evidence. It was commonly believed that the HIV-1 capsid would need to disassemble (uncoat) in the cytosol before nuclear import because the capsid is larger than the central channel of nuclear pore complexes (NPCs); however, increasing evidence demonstrates that intact, or nearly intact, HIV-1 capsid passes through the NPC to enter the nucleus. With the protection of the capsid, the HIV-1 core completes reverse transcription in the nucleus and is translocated to the integration site. Uncoating occurs while, or after, the viral genome is released near the integration site. These independent discoveries reveal a compelling new paradigm of this important step of the HIV-1 life cycle. In this review, we summarize the recent studies related to HIV-1 nuclear import, highlighting the spatial-temporal relationship between the nuclear entry of the virus core, reverse transcription, and capsid uncoating.
Collapse
Affiliation(s)
| | | | | | | | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06511, USA; (Q.S.); (C.W.); (C.F.); (T.N.T.)
| |
Collapse
|
22
|
Saito A, Yamashita M. HIV-1 capsid variability: viral exploitation and evasion of capsid-binding molecules. Retrovirology 2021; 18:32. [PMID: 34702294 PMCID: PMC8549334 DOI: 10.1186/s12977-021-00577-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 10/13/2021] [Indexed: 11/17/2022] Open
Abstract
The HIV-1 capsid, a conical shell encasing viral nucleoprotein complexes, is involved in multiple post-entry processes during viral replication. Many host factors can directly bind to the HIV-1 capsid protein (CA) and either promote or prevent HIV-1 infection. The viral capsid is currently being explored as a novel target for therapeutic interventions. In the past few decades, significant progress has been made in our understanding of the capsid–host interactions and mechanisms of action of capsid-targeting antivirals. At the same time, a large number of different viral capsids, which derive from many HIV-1 mutants, naturally occurring variants, or diverse lentiviruses, have been characterized for their interactions with capsid-binding molecules in great detail utilizing various experimental techniques. This review provides an overview of how sequence variation in CA influences phenotypic properties of HIV-1. We will focus on sequence differences that alter capsid–host interactions and give a brief account of drug resistant mutations in CA and their mutational effects on viral phenotypes. Increased knowledge of the sequence-function relationship of CA helps us deepen our understanding of the adaptive potential of the viral capsid.
Collapse
Affiliation(s)
- Akatsuki Saito
- Department of Veterinary Medicine, Faculty of Agriculture, University of Miyazaki, Miyazaki, Miyazaki, Japan.,Center for Animal Disease Control, University of Miyazaki, Miyazaki, Miyazaki, Japan
| | - Masahiro Yamashita
- Aaron Diamond AIDS Research Center, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA.
| |
Collapse
|
23
|
Aiken C, Rousso I. The HIV-1 capsid and reverse transcription. Retrovirology 2021; 18:29. [PMID: 34563203 PMCID: PMC8466977 DOI: 10.1186/s12977-021-00566-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 07/20/2021] [Indexed: 02/08/2023] Open
Abstract
The viral capsid plays a key role in HIV-1 reverse transcription. Recent studies have demonstrated that the small molecule IP6 dramatically enhances reverse transcription in vitro by stabilizing the viral capsid. Reverse transcription results in marked changes in the biophysical properties of the capsid, ultimately resulting in its breakage and disassembly. Here we review the research leading to these advances and describe hypotheses for capsid-dependent HIV-1 reverse transcription and a model for reverse transcription-primed HIV-1 uncoating.
Collapse
Affiliation(s)
- Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Itay Rousso
- Department of Physiology and Cell Biology, Ben-Gurion University of the Negev, Beer Sheva, Israel
| |
Collapse
|
24
|
Engelman KD, Engelman AN. Long-Acting Cabotegravir for HIV/AIDS Prophylaxis. Biochemistry 2021; 60:1731-1740. [PMID: 34029457 DOI: 10.1021/acs.biochem.1c00157] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The retrovirus HIV-1 is the etiological agent of the decades-long AIDS pandemic. Although vaccination is the most common preexposure route to prevent acquisition of viral disease, scalable efficacious vaccination strategies have yet to be developed for HIV-1. By contrast, small molecule inhibitors of the HIV-1 enzymes reverse transcriptase, integrase, and protease have been developed that effectively block virus replication. Three different drug compounds are commonly prescribed for people living with HIV as once-daily oral tablets. Once-daily pills composed of two different reverse transcriptase inhibitors are moreover approved as preexposure prophylaxis (PrEP) treatment for virus naïve individuals who may partake in behaviors associated with increased risk of HIV-1 acquisition such as unprotected sex or injection drug use. Long-acting (LA) injectable HIV-1 enzyme inhibitors are at the same time being developed to sidestep adherence noncompliance issues that can arise from self-administered once-daily oral dosing regimens. Cabotegravir (CAB)-LA, which inhibits integrase strand transfer activity, has in recent clinical trials been shown to prevent HIV-1 acquisition more effectively than once-daily oral dosed reverse transcriptase inhibitors. In this Perspective, we examine bench to bedside aspects of CAB-LA treatment and development, starting from the biochemical basis of HIV-1 integration and pharmacological inhibition of integrase catalysis. We also review the results of recent clinical trials that evaluated CAB-LA, as well as the promises and challenges that surround its use for HIV/AIDS PrEP.
Collapse
Affiliation(s)
- Kathleen D Engelman
- MassBiologics, University of Massachusetts Medical School, 460 Walk Hill Street, Boston, Massachusetts 02126, United States
| | - Alan N Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, Massachusetts 02215, United States.,Department of Medicine, Harvard Medical School, 25 Shattuck Street, Boston, Massachusetts 02115, United States
| |
Collapse
|
25
|
HIV-1 uncoating occurs via a series of rapid biomechanical changes in the core related to individual stages of reverse transcription. J Virol 2021; 95:JVI.00166-21. [PMID: 33692202 PMCID: PMC8139671 DOI: 10.1128/jvi.00166-21] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The HIV core consists of the viral genome and associated proteins encased by a cone-shaped protein shell termed the capsid. Successful infection requires reverse transcription of the viral genome and disassembly of the capsid shell within a cell in a process known as uncoating. The integrity of the viral capsid is critical for reverse transcription, yet the viral capsid must be breached to release the nascent viral DNA prior to integration. We employed atomic force microscopy to study the stiffness changes in HIV-1 cores during reverse transcription in vitro in reactions containing the capsid-stabilizing host metabolite IP6 Cores exhibited a series of stiffness spikes, with up to three spikes typically occurring between 10-30, 40-80, and 120-160 minutes after initiation of reverse transcription. Addition of the reverse transcriptase (RT) inhibitor efavirenz eliminated the appearance of these spikes and the subsequent disassembly of the capsid, thus establishing that both result from reverse transcription. Using timed addition of efavirenz, and analysis of an RNAseH-defective RT mutant, we established that the first stiffness spike requires minus-strand strong stop DNA synthesis, with subsequent spikes requiring later stages of reverse transcription. Additional rapid AFM imaging experiments revealed repeated morphological changes in cores that were temporally correlated with the observed stiffness spikes. Our study reveals discrete mechanical changes in the viral core that are likely related to specific stages of reverse transcription. These reverse-transcription-induced changes in the capsid progressively remodel the viral core to prime it for temporally accurate uncoating in target cells.ImportanceFor successful infection, the HIV-1 genome, which is enclosed inside a capsid shell, must be reverse transcribed into double-stranded DNA and released from the capsid (in a process known as uncoating) before it can be integrated into the target cell genome. The mechanism of HIV-1 uncoating is a pivotal question of long standing. Using atomic force microscopy to analyze individual HIV-1 cores during reverse transcription, we observe a reproducible pattern of stiffness spikes. These spikes were shown to be associated with distinct stages of the reverse transcription reaction. Our findings suggest that these reverse-transcription-induced alterations gradually prepared the core for uncoating at the right time and location in target cells.
Collapse
|
26
|
Wilbourne M, Zhang P. Visualizing HIV-1 Capsid and Its Interactions with Antivirals and Host Factors. Viruses 2021; 13:246. [PMID: 33557422 PMCID: PMC7914784 DOI: 10.3390/v13020246] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 01/31/2021] [Accepted: 02/01/2021] [Indexed: 02/03/2023] Open
Abstract
Understanding of the construction and function of the HIV capsid has advanced considerably in the last decade. This is due in large part to the development of more sophisticated structural techniques, particularly cryo-electron microscopy (cryoEM) and cryo-electron tomography (cryoET). The capsid is known to be a pleomorphic fullerene cone comprised of capsid protein monomers arranged into 200-250 hexamers and 12 pentamers. The latter of these induce high curvature necessary to close the cone at both ends. CryoEM/cryoET, NMR, and X-ray crystallography have collectively described these interactions to atomic or near-atomic resolutions. Further, these techniques have helped to clarify the role the HIV capsid plays in several parts of the viral life cycle, from reverse transcription to nuclear entry and integration into the host chromosome. This includes visualizing the capsid bound to host factors. Multiple proteins have been shown to interact with the capsid. Cyclophilin A, nucleoporins, and CPSF6 promote viral infectivity, while MxB and Trim5α diminish the viral infectivity. Finally, structural insights into the intra- and intermolecular interactions that govern capsid function have enabled development of small molecules, peptides, and truncated proteins to disrupt or stabilize the capsid to inhibit HIV replication. The most promising of these, GS6207, is now in clinical trial.
Collapse
Affiliation(s)
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| |
Collapse
|
27
|
Engelman AN. HIV Capsid and Integration Targeting. Viruses 2021; 13:125. [PMID: 33477441 PMCID: PMC7830116 DOI: 10.3390/v13010125] [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: 12/13/2020] [Revised: 01/13/2021] [Accepted: 01/15/2021] [Indexed: 12/20/2022] Open
Abstract
Integration of retroviral reverse transcripts into the chromosomes of the cells that they infect is required for efficient viral gene expression and the inheritance of viral genomes to daughter cells. Before integration can occur, retroviral reverse transcription complexes (RTCs) must access the nuclear environment where the chromosomes reside. Retroviral integration is non-random, with different types of virus-host interactions impacting where in the host chromatin integration takes place. Lentiviruses such as HIV efficiently infect interphase cells because their RTCs have evolved to usurp cellular nuclear import transport mechanisms, and research over the past decade has revealed specific interactions between the HIV capsid protein and nucleoporin (Nup) proteins such as Nup358 and Nup153. The interaction of HIV capsid with cleavage and polyadenylation specificity factor 6 (CPSF6), which is a component of the cellular cleavage and polyadenylation complex, helps to dictate nuclear import as well as post-nuclear RTC invasion. In the absence of the capsid-CPSF6 interaction, RTCs are precluded from reaching nuclear speckles and gene-rich regions of chromatin known as speckle-associated domains, and instead mis-target lamina-associated domains out at the nuclear periphery. Highlighting this area of research, small molecules that inhibit capsid-host interactions important for integration site targeting are highly potent antiviral compounds.
Collapse
Affiliation(s)
- Alan N. Engelman
- Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Boston, MA 02215, USA; ; Tel.: +1-617-632-4361
- Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
| |
Collapse
|