1
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Starling T, Padilla-Parra S. HIV-1 Induced Cell-to-Cell Fusion or Syncytium Formation. Results Probl Cell Differ 2024; 71:319-328. [PMID: 37996684 DOI: 10.1007/978-3-031-37936-9_15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
HIV-1 cell-free infection has been thoroughly investigated; however, its relevance and importance in vitro are questionable. Cell-cell transmission is now thought to be the dominant mode of transmission within the host; however precise molecular details remain elusive. The considerable potency of cell-cell transmission hinges upon its ability to hijack and manipulate host immunological function to target uninfected cells, along with overcoming restriction factors and increasing the speed of latent pool formation. Another question of relevance is virus induced cell-cell fusion and how this process is regulated. How often HIV-1 induces the formation of syncytia? Is cell-cell function a potential process for HIV-1 transmission? These questions are discussed and reviewed together with a description of the most common ways of HIV-1 entry and transinfection.
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Affiliation(s)
- Tobias Starling
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK
| | - Sergi Padilla-Parra
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK.
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.
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2
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Li W, Qin Z, Nand E, Grunst MW, Grover JR, Bess JW, Lifson JD, Zwick MB, Tagare HD, Uchil PD, Mothes W. HIV-1 Env trimers asymmetrically engage CD4 receptors in membranes. Nature 2023; 623:1026-1033. [PMID: 37993716 PMCID: PMC10686830 DOI: 10.1038/s41586-023-06762-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 10/19/2023] [Indexed: 11/24/2023]
Abstract
Human immunodeficiency virus 1 (HIV-1) infection is initiated by binding of the viral envelope glycoprotein (Env) to the cell-surface receptor CD41-4. Although high-resolution structures of Env in a complex with the soluble domains of CD4 have been determined, the binding process is less understood in native membranes5-13. Here we used cryo-electron tomography to monitor Env-CD4 interactions at the membrane-membrane interfaces formed between HIV-1 and CD4-presenting virus-like particles. Env-CD4 complexes organized into clusters and rings, bringing the opposing membranes closer together. Env-CD4 clustering was dependent on capsid maturation. Subtomogram averaging and classification revealed that Env bound to one, two and finally three CD4 molecules, after which Env adopted an open state. Our data indicate that asymmetric HIV-1 Env trimers bound to one and two CD4 molecules are detectable intermediates during virus binding to host cell membranes, which probably has consequences for antibody-mediated immune responses and vaccine immunogen design.
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Affiliation(s)
- Wenwei Li
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA.
| | - Zhuan Qin
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Elizabeth Nand
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Michael W Grunst
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Jonathan R Grover
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Julian W Bess
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Jeffrey D Lifson
- AIDS and Cancer Virus Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Michael B Zwick
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, USA
| | - Hemant D Tagare
- Department of Radiology and Biomedical Imaging, Yale University, New Haven, CT, USA
| | - Pradeep D Uchil
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA
| | - Walther Mothes
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT, USA.
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3
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Starling T, Carlon-Andres I, Iliopoulou M, Kraemer B, Loidolt-Krueger M, Williamson DJ, Padilla-Parra S. Multicolor lifetime imaging and its application to HIV-1 uptake. Nat Commun 2023; 14:4994. [PMID: 37591879 PMCID: PMC10435470 DOI: 10.1038/s41467-023-40731-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 08/04/2023] [Indexed: 08/19/2023] Open
Abstract
Simultaneous imaging of nine fluorescent proteins is demonstrated in a single acquisition using fluorescence lifetime imaging microscopy combined with pulsed interleaved excitation of three laser lines. Multicolor imaging employing genetically encodable fluorescent proteins permits spatio-temporal live cell imaging of multiple cues. Here, we show that multicolor lifetime imaging allows visualization of quadruple labelled human immunodeficiency viruses on host cells that in turn are also labelled with genetically encodable fluorescent proteins. This strategy permits to simultaneously visualize different sub-cellular organelles (mitochondria, cytoskeleton, and nucleus) during the process of virus entry with the potential of imaging up to nine different spectral channels in living cells.
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Affiliation(s)
- Tobias Starling
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK
| | - Irene Carlon-Andres
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK
| | - Maro Iliopoulou
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
- Randall Division of Cell and Molecular Biophysics and Department of Physics, King's College London, London, UK
| | - Benedikt Kraemer
- PicoQuant GmbH, Rudower Chaussee 29 (IGZ), 12489, Berlin, Germany
| | | | - David J Williamson
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK
| | - Sergi Padilla-Parra
- Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London, UK.
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
- Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.
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4
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Yang W, Hou L, Luo C. When Super-Resolution Microscopy Meets Microfluidics: Enhanced Biological Imaging and Analysis with Unprecedented Resolution. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023; 19:e2207341. [PMID: 36895074 DOI: 10.1002/smll.202207341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 01/31/2023] [Indexed: 06/08/2023]
Abstract
Super-resolution microscopy is rapidly developed in recent years, allowing biologists to extract more quantitative information on subcellular processes in live cells that is usually not accessible with conventional techniques. However, super-resolution imaging is not fully exploited because of the lack of an appropriate and multifunctional experimental platform. As an important tool in life sciences, microfluidics is capable of cell manipulation and the regulation of the cellular environment because of its superior flexibility and biocompatibility. The combination of microfluidics and super-resolution microscopy revolutionizes the study of complex cellular properties and dynamics, providing valuable insights into cellular structure and biological functions at the single-molecule level. In this perspective, an overview of the main advantages of microfluidic technology that are essential to the performance of super-resolution microscopy are offered. The main benefits of performing super-resolution imaging with microfluidic devices are highlighted and perspectives on the diverse applications that are facilitated by combining these two powerful techniques are provided.
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Affiliation(s)
- Wei Yang
- Wenzhou Institute University of Chinese Academy of Sciences, 1 Jinlian Road, Wenzhou, Zhejiang, 325001, China
| | - Lei Hou
- UMR5298-LP2N, Institut d'Optique and CNRS, Rue François Mitterrand, Talence, 33400, France
| | - Chunxiong Luo
- Wenzhou Institute University of Chinese Academy of Sciences, 1 Jinlian Road, Wenzhou, Zhejiang, 325001, China
- The State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, 5 Summer Palace Road, Beijing, 100871, China
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, 5 Summer Palace Road, Beijing, 100871, China
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5
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Padilla-Parra S. Time-resolved single virus tracking and spectral imaging to understand HIV-1 entry and fusion. Biol Cell 2023; 115:e2200082. [PMID: 36440600 DOI: 10.1111/boc.202200082] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2022] [Revised: 11/02/2022] [Accepted: 11/18/2022] [Indexed: 11/29/2022]
Abstract
Single Virus Tracking (SVT) is a key technique to understand how individual viral particles evolve during the infection cycle. In the case of the human immunodeficiency virus (HIV-1), this technology, which can be employed using a simple and affordable wide-field microscope, has proven to be very useful in the first steps of infection, such as the kinetics of the fusion reaction or the point of fusion within live cells. Here, we describe how SVT in combination with other spectral imaging approaches is a powerful technique to illuminate crucial mechanistic aspects of the HIV-1 fusion reaction. We also stress the role of our laboratory in elucidating a few mechanistic aspects of retroviral fusion employing SVT such as: (i) the role of dynamin, (ii) how metabolism modulates membrane composition and cholesterol and its impact in fusion, (iii) the importance of envelope glycoprotein (Env) intra- and inter-molecular dynamics for neutralization, or (iv) the time-resolved fusion stoichiometry in three characteristic steps for the HIV-1 prefusion step. These observations constitute a good testimony of the complexity of retroviral fusion and show the strength of SVT when applied to live cells and combined with quantitative spectral approaches. Finally, we propose several crucial remaining questions around HIV-1 fusion and how the combined use of these technologies, always in live cells, will be able to shed light into the intricacies of arguably the most important step of the HIV-1 infection cycle.
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Affiliation(s)
- Sergi Padilla-Parra
- Faculty of Life Sciences & Medicine, Department of Infectious Diseases, King's College London, London, UK.,Randall Division of Cell and Molecular Biophysics, King's College London, London, UK
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6
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Padilla-Parra S. Next-generation single virus tracking. Nat Methods 2022; 19:1524-1525. [PMID: 36357693 DOI: 10.1038/s41592-022-01670-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Sergi Padilla-Parra
- Department of Infectious Diseases, Faculty of Life Sciences & Medicine, King's College London, London, UK. .,Randall Division of Cell and Molecular Biophysics, King's College London, London, UK.
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7
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Kuklina EM. T Lymphocytes as Targets for SARS-CoV-2. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:566-576. [PMID: 35790412 PMCID: PMC9201263 DOI: 10.1134/s0006297922060086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/17/2022] [Accepted: 05/17/2022] [Indexed: 01/11/2023]
Abstract
Despite numerous data on the absence or weak expression of the main functional receptor of SARS-CoV-2 angiotensin-converting enzyme 2 (ACE2) by T cells, it was recently demonstrated that the new coronavirus can efficiently infect T lymphocytes. Here, we analyze the data on the alternative (ACE2-independent) pathways of cell infection, identified T cell subpopulations that serve as the most plausible targets of SARS-CoV-2, discuss the mechanisms of virus-cell interaction, including both infectious and non-infectious pathways of T lymphocyte regulation, and estimate the role of the virus-dependent damage of T lymphocytes in COVID-19 pathogenesis. Particular attention is paid to regulatory T cells as potential targets of SARS-CoV-2, as well as to the possible involvement of exosomes in the sensitivity of peripheral T cells to the virus.
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Affiliation(s)
- Elena M Kuklina
- Perm Federal Research Center, Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, Perm, 614081, Russia.
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8
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Yu Y, Yoshimura SH. Investigating the morphological dynamics of the plasma membrane by high-speed atomic force microscopy. J Cell Sci 2021; 134:272010. [PMID: 34468000 DOI: 10.1242/jcs.243584] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Despite numerous recent developments in bioimaging techniques, nanoscale and live-cell imaging of the plasma membrane has been challenging because of the insufficient z-resolution of optical microscopes, as well as the lack of fluorescent probes to specifically label small membrane structures. High-speed atomic force microscopy (HS-AFM) is a powerful tool for visualising the dynamics of a specimen surface and is therefore suitable for observing plasma membrane dynamics. Recent developments in HS-AFM for live-cell imaging have enabled the visualisation of the plasma membrane and the network of cortical actin underneath the membrane in a living cell. Furthermore, correlative imaging with fluorescence microscopy allows for the direct visualisation of morphological changes of the plasma membrane together with the dynamic assembly or disassembly of proteins during the entire course of endocytosis in a living cell. Here, we review these recent advances in HS-AFM in order to analyse various cellular events occurring at the cell surface.
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Affiliation(s)
- Yiming Yu
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
| | - Shige H Yoshimura
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto 606-8501, Japan
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9
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Bennett AL, Henderson R. HIV-1 Envelope Conformation, Allostery, and Dynamics. Viruses 2021; 13:852. [PMID: 34067073 PMCID: PMC8150877 DOI: 10.3390/v13050852] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 04/28/2021] [Accepted: 05/04/2021] [Indexed: 11/16/2022] Open
Abstract
The HIV-1 envelope glycoprotein (Env) mediates host cell fusion and is the primary target for HIV-1 vaccine design. The Env undergoes a series of functionally important conformational rearrangements upon engagement of its host cell receptor, CD4. As the sole target for broadly neutralizing antibodies, our understanding of these transitions plays a critical role in vaccine immunogen design. Here, we review available experimental data interrogating the HIV-1 Env conformation and detail computational efforts aimed at delineating the series of conformational changes connecting these rearrangements. These studies have provided a structural mapping of prefusion closed, open, and transition intermediate structures, the allosteric elements controlling rearrangements, and state-to-state transition dynamics. The combination of these investigations and innovations in molecular modeling set the stage for advanced studies examining rearrangements at greater spatial and temporal resolution.
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Affiliation(s)
| | - Rory Henderson
- Duke Human Vaccine Institute, Durham, NC 27710, USA;
- Department of Medicine, Duke University, Durham, NC 27710, USA
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10
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Cabrera-Rodríguez R, Pérez-Yanes S, Estévez-Herrera J, Márquez-Arce D, Cabrera C, Espert L, Blanco J, Valenzuela-Fernández A. The Interplay of HIV and Autophagy in Early Infection. Front Microbiol 2021; 12:661446. [PMID: 33995324 PMCID: PMC8113651 DOI: 10.3389/fmicb.2021.661446] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 03/31/2021] [Indexed: 12/11/2022] Open
Abstract
HIV/AIDS is still a global threat despite the notable efforts made by the scientific and health communities to understand viral infection, to design new drugs or to improve existing ones, as well as to develop advanced therapies and vaccine designs for functional cure and viral eradication. The identification and analysis of HIV-1 positive individuals that naturally control viral replication in the absence of antiretroviral treatment has provided clues about cellular processes that could interact with viral proteins and RNA and define subsequent viral replication and clinical progression. This is the case of autophagy, a degradative process that not only maintains cell homeostasis by recycling misfolded/old cellular elements to obtain nutrients, but is also relevant in the innate and adaptive immunity against viruses, such as HIV-1. Several studies suggest that early steps of HIV-1 infection, such as virus binding to CD4 or membrane fusion, allow the virus to modulate autophagy pathways preparing cells to be permissive for viral infection. Confirming this interplay, strategies based on autophagy modulation are able to inhibit early steps of HIV-1 infection. Moreover, autophagy dysregulation in late steps of the HIV-1 replication cycle may promote autophagic cell-death of CD4+ T cells or control of HIV-1 latency, likely contributing to disease progression and HIV persistence in infected individuals. In this scenario, understanding the molecular mechanisms underlying HIV/autophagy interplay may contribute to the development of new strategies to control HIV-1 replication. Therefore, the aim of this review is to summarize the knowledge of the interplay between autophagy and the early events of HIV-1 infection, and how autophagy modulation could impair or benefit HIV-1 infection and persistence, impacting viral pathogenesis, immune control of viral replication, and clinical progression of HIV-1 infected patients.
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Affiliation(s)
- Romina Cabrera-Rodríguez
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, e IUETSPC de la Universidad de La Laguna, Campus de Ofra s/n, Tenerife, Spain
| | - Silvia Pérez-Yanes
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, e IUETSPC de la Universidad de La Laguna, Campus de Ofra s/n, Tenerife, Spain
| | - Judith Estévez-Herrera
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, e IUETSPC de la Universidad de La Laguna, Campus de Ofra s/n, Tenerife, Spain
| | - Daniel Márquez-Arce
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, e IUETSPC de la Universidad de La Laguna, Campus de Ofra s/n, Tenerife, Spain
| | - Cecilia Cabrera
- AIDS Research Institute IrsiCaixa, Institut de Recerca en Ciències de la Salut Germans Trias i Pujol (IGTP), Barcelona, Spain
| | - Lucile Espert
- Institut de Recherche en Infectiologie de Montpellier, Université de Montpellier, CNRS, Montpellier, France
| | - Julià Blanco
- AIDS Research Institute IrsiCaixa, Institut de Recerca en Ciències de la Salut Germans Trias i Pujol (IGTP), Barcelona, Spain.,Universitat de Vic-Central de Catalunya (UVIC-UCC), Catalonia, Spain
| | - Agustín Valenzuela-Fernández
- Laboratorio de Inmunología Celular y Viral, Unidad de Farmacología, Sección de Medicina, Facultad de Ciencias de la Salud, e IUETSPC de la Universidad de La Laguna, Campus de Ofra s/n, Tenerife, Spain
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11
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Yandrapally S, Mohareer K, Arekuti G, Vadankula GR, Banerjee S. HIV co-receptor-tropism: cellular and molecular events behind the enigmatic co-receptor switching. Crit Rev Microbiol 2021; 47:499-516. [PMID: 33900141 DOI: 10.1080/1040841x.2021.1902941] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Recognition of cell-surface receptors and co-receptors is a crucial molecular event towards the establishment of HIV infection. HIV exists as several variants that differentially recognize the principal co-receptors, CCR5 and CXCR4, in different cell types, known as HIV co-receptor-tropism. The relative levels of these variants dynamically adjust to the changing host selection pressures to infect a vast repertoire of cells in a stage-specific manner. HIV infection sets in through immune cells such as dendritic cells, macrophages, and T-lymphocytes in the acute stage, while a wide range of other cells, including astrocytes, glial cells, B-lymphocytes, and epithelial cells, are infected during chronic stages. A change in tropism occurs during the transition from acute to a chronic phase, termed as co-receptor switching marked by a change in disease severity. The cellular and molecular events leading to co-receptor switching are poorly understood. This review aims to collate our present understanding of the dynamics of HIV co-receptor-tropism vis-à-vis host and viral factors, highlighting the cellular and molecular events involved therein. We present the possible correlations between virus entry, cell tropism, and co-receptor switching, speculating its consequences on disease progression, and proposing new scientific pursuits to help in an in-depth understanding of HIV biology.
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Affiliation(s)
| | | | - Geethika Arekuti
- Department of Biochemistry, University of Hyderabad, Hyderabad, India
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12
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HIV-1 Entry and Membrane Fusion Inhibitors. Viruses 2021; 13:v13050735. [PMID: 33922579 PMCID: PMC8146413 DOI: 10.3390/v13050735] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Revised: 04/13/2021] [Accepted: 04/21/2021] [Indexed: 12/14/2022] Open
Abstract
HIV-1 (human immunodeficiency virus type 1) infection begins with the attachment of the virion to a host cell by its envelope glycoprotein (Env), which subsequently induces fusion of viral and cell membranes to allow viral entry. Upon binding to primary receptor CD4 and coreceptor (e.g., chemokine receptor CCR5 or CXCR4), Env undergoes large conformational changes and unleashes its fusogenic potential to drive the membrane fusion. The structural biology of HIV-1 Env and its complexes with the cellular receptors not only has advanced our knowledge of the molecular mechanism of how HIV-1 enters the host cells but also provided a structural basis for the rational design of fusion inhibitors as potential antiviral therapeutics. In this review, we summarize our latest understanding of the HIV-1 membrane fusion process and discuss related therapeutic strategies to block viral entry.
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13
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Lu M. Single-Molecule FRET Imaging of Virus Spike-Host Interactions. Viruses 2021; 13:v13020332. [PMID: 33669922 PMCID: PMC7924862 DOI: 10.3390/v13020332] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/18/2021] [Accepted: 02/18/2021] [Indexed: 02/07/2023] Open
Abstract
As a major surface glycoprotein of enveloped viruses, the virus spike protein is a primary target for vaccines and anti-viral treatments. Current vaccines aiming at controlling the COVID-19 pandemic are mostly directed against the SARS-CoV-2 spike protein. To promote virus entry and facilitate immune evasion, spikes must be dynamic. Interactions with host receptors and coreceptors trigger a cascade of conformational changes/structural rearrangements in spikes, which bring virus and host membranes in proximity for membrane fusion required for virus entry. Spike-mediated viral membrane fusion is a dynamic, multi-step process, and understanding the structure–function-dynamics paradigm of virus spikes is essential to elucidate viral membrane fusion, with the ultimate goal of interventions. However, our understanding of this process primarily relies on individual structural snapshots of endpoints. How these endpoints are connected in a time-resolved manner, and the order and frequency of conformational events underlying virus entry, remain largely elusive. Single-molecule Förster resonance energy transfer (smFRET) has provided a powerful platform to connect structure–function in motion, revealing dynamic aspects of spikes for several viruses: SARS-CoV-2, HIV-1, influenza, and Ebola. This review focuses on how smFRET imaging has advanced our understanding of virus spikes’ dynamic nature, receptor-binding events, and mechanism of antibody neutralization, thereby informing therapeutic interventions.
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Affiliation(s)
- Maolin Lu
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA
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14
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Yuan Y, Jacobs CA, Llorente Garcia I, Pereira PM, Lawrence SP, Laine RF, Marsh M, Henriques R. Single-Molecule Super-Resolution Imaging of T-Cell Plasma Membrane CD4 Redistribution upon HIV-1 Binding. Viruses 2021; 13:142. [PMID: 33478139 PMCID: PMC7835772 DOI: 10.3390/v13010142] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Revised: 01/14/2021] [Accepted: 01/15/2021] [Indexed: 12/21/2022] Open
Abstract
The first step of cellular entry for the human immunodeficiency virus type-1 (HIV-1) occurs through the binding of its envelope protein (Env) with the plasma membrane receptor CD4 and co-receptor CCR5 or CXCR4 on susceptible cells, primarily CD4+ T cells and macrophages. Although there is considerable knowledge of the molecular interactions between Env and host cell receptors that lead to successful fusion, the precise way in which HIV-1 receptors redistribute to sites of virus binding at the nanoscale remains unknown. Here, we quantitatively examine changes in the nanoscale organisation of CD4 on the surface of CD4+ T cells following HIV-1 binding. Using single-molecule super-resolution imaging, we show that CD4 molecules are distributed mostly as either individual molecules or small clusters of up to 4 molecules. Following virus binding, we observe a local 3-to-10-fold increase in cluster diameter and molecule number for virus-associated CD4 clusters. Moreover, a similar but smaller magnitude reorganisation of CD4 was also observed with recombinant gp120. For one of the first times, our results quantify the nanoscale CD4 reorganisation triggered by HIV-1 on host CD4+ T cells. Our quantitative approach provides a robust methodology for characterising the nanoscale organisation of plasma membrane receptors in general with the potential to link spatial organisation to function.
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Affiliation(s)
- Yue Yuan
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; (Y.Y.); (C.A.J.); (P.M.P.); (S.P.L.)
| | - Caron A. Jacobs
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; (Y.Y.); (C.A.J.); (P.M.P.); (S.P.L.)
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, Department of Pathology, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town 7925, South Africa
- Wellcome Centre for Infectious Diseases Research in Africa, University of Cape Town, Cape Town 7925, South Africa
| | | | - Pedro M. Pereira
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; (Y.Y.); (C.A.J.); (P.M.P.); (S.P.L.)
- Bacterial Cell Biology, MOSTMICRO, Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, 2780-157 Oeiras, Portugal
| | - Scott P. Lawrence
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; (Y.Y.); (C.A.J.); (P.M.P.); (S.P.L.)
| | - Romain F. Laine
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; (Y.Y.); (C.A.J.); (P.M.P.); (S.P.L.)
- The Francis Crick Institute, London NW1 1AT, UK
| | - Mark Marsh
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; (Y.Y.); (C.A.J.); (P.M.P.); (S.P.L.)
| | - Ricardo Henriques
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, UK; (Y.Y.); (C.A.J.); (P.M.P.); (S.P.L.)
- The Francis Crick Institute, London NW1 1AT, UK
- Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal
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15
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Salmon M, Carlon-Andres I, Padilla-Parra S. Endogenous Labeling for Light Microscopy during HIV-1 Immune Responses. Trends Immunol 2020; 41:1056-1059. [PMID: 33148466 DOI: 10.1016/j.it.2020.10.009] [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: 07/14/2020] [Revised: 10/02/2020] [Accepted: 10/09/2020] [Indexed: 11/17/2022]
Abstract
New approaches in single molecule spectroscopy and microscopy are able to resolve the spatial and temporal resolution of T cell receptor signaling in the context of immune responses to HIV-1 infection. These approaches need to be complemented with novel techniques that endogenously tag the protein or proteins of interest, yet avoid overexpression, to image protein dynamics under physiological conditions.
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Affiliation(s)
- Minette Salmon
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Irene Carlon-Andres
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Sergi Padilla-Parra
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; Department of Infectious Diseases, King's College London, Faculty of Life Sciences and Medicine, London SE1 9RT, UK; Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 9RT, UK.
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16
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Rozbesky D, Verhagen MG, Karia D, Nagy GN, Alvarez L, Robinson RA, Harlos K, Padilla‐Parra S, Pasterkamp RJ, Jones EY. Structural basis of semaphorin-plexin cis interaction. EMBO J 2020; 39:e102926. [PMID: 32500924 PMCID: PMC7327498 DOI: 10.15252/embj.2019102926] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 01/05/2023] Open
Abstract
Semaphorin ligands interact with plexin receptors to contribute to functions in the development of myriad tissues including neurite guidance and synaptic organisation within the nervous system. Cell-attached semaphorins interact in trans with plexins on opposing cells, but also in cis on the same cell. The interplay between trans and cis interactions is crucial for the regulated development of complex neural circuitry, but the underlying molecular mechanisms are uncharacterised. We have discovered a distinct mode of interaction through which the Drosophila semaphorin Sema1b and mouse Sema6A mediate binding in cis to their cognate plexin receptors. Our high-resolution structural, biophysical and in vitro analyses demonstrate that monomeric semaphorins can mediate a distinctive plexin binding mode. These findings suggest the interplay between monomeric vs dimeric states has a hereto unappreciated role in semaphorin biology, providing a mechanism by which Sema6s may balance cis and trans functionalities.
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Affiliation(s)
- Daniel Rozbesky
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Marieke G Verhagen
- Department of Translational NeuroscienceUMC Utrecht Brain CenterUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Dimple Karia
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Gergely N Nagy
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Luis Alvarez
- Cellular ImagingWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Ross A Robinson
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
- Present address:
Immunocore LtdAbingdonUK
| | - Karl Harlos
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
| | - Sergi Padilla‐Parra
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
- Cellular ImagingWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
- Present address:
Department of Infectious DiseasesFaculty of Life Sciences & MedicineKing's College LondonLondonUK
- Present address:
Randall Centre for Cell and Molecular BiophysicsKing's College LondonLondonUK
| | - R Jeroen Pasterkamp
- Department of Translational NeuroscienceUMC Utrecht Brain CenterUniversity Medical Center UtrechtUtrecht UniversityUtrechtThe Netherlands
| | - Edith Yvonne Jones
- Division of Structural BiologyWellcome Centre for Human GeneticsUniversity of OxfordOxfordUK
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17
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Llorente García I, Marsh M. A biophysical perspective on receptor-mediated virus entry with a focus on HIV. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2020; 1862:183158. [PMID: 31863725 PMCID: PMC7156917 DOI: 10.1016/j.bbamem.2019.183158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/12/2019] [Accepted: 12/13/2019] [Indexed: 12/14/2022]
Abstract
As part of their entry and infection strategy, viruses interact with specific receptor molecules expressed on the surface of target cells. The efficiency and kinetics of the virus-receptor interactions required for a virus to productively infect a cell is determined by the biophysical properties of the receptors, which are in turn influenced by the receptors' plasma membrane (PM) environments. Currently, little is known about the biophysical properties of these receptor molecules or their engagement during virus binding and entry. Here we review virus-receptor interactions focusing on the human immunodeficiency virus type 1 (HIV), the etiological agent of acquired immunodeficiency syndrome (AIDS), as a model system. HIV is one of the best characterised enveloped viruses, with the identity, roles and structure of the key molecules required for infection well established. We review current knowledge of receptor-mediated HIV entry, addressing the properties of the HIV cell-surface receptors, the techniques used to measure these properties, and the macromolecular interactions and events required for virus entry. We discuss some of the key biophysical principles underlying receptor-mediated virus entry and attempt to interpret the available data in the context of biophysical mechanisms. We also highlight crucial outstanding questions and consider how new tools might be applied to advance understanding of the biophysical properties of viral receptors and the dynamic events leading to virus entry.
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Affiliation(s)
| | - Mark Marsh
- Medical Research Council Laboratory for Molecular Cell Biology, University College London, London, UK
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18
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Chen L, Wu Z, Wu X, Liao Y, Dai X, Shi X. The Application of Coarse-Grained Molecular Dynamics to the Evaluation of Liposome Physical Stability. AAPS PharmSciTech 2020; 21:138. [PMID: 32419093 DOI: 10.1208/s12249-020-01680-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 04/09/2020] [Indexed: 12/16/2022] Open
Abstract
Physical stability is one of critical characteristics of liposome, especially to its clinical application. Vesicle fusion was one of the common physical stability phenomena that occurred during the long storage period. Because vesicle fusion could be easily checked by the change of vesicle size, it was widely applied in the evaluation of liposome physical stability. However, since the method requires the liposome to be placed under certain conditions for long-term observation, a liposome physical stability test usually takes several weeks, which greatly hinders the research efficiency. In this study, to speed up the research efficiency, coarse-grained molecular dynamics was first applied in the study of liposome physical stability. By analyzing the microprocess of vesicle fusion, two parameters including diffusion constant and the total time of the vesicle morphology transition process were employed to study the liposome physical stability. Then, in order to verify the applicability of two parameters, the physical stability of elastic liposomes and conventional liposomes was compared at 3 different temperatures. It was found that the fusion probability and speed of elastic liposomes were higher than those of conventional liposomes. Thus, elastic liposomes showed a worse physical stability compared with that of conventional liposomes, which was consistent with former research. Through this research, a new efficient method based on coarse-grained molecular dynamics was proposed for the study of liposome physical stability.
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19
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Rozbesky D, Monistrol J, Jain V, Hillier J, Padilla-Parra S, Jones EY. Drosophila OTK Is a Glycosaminoglycan-Binding Protein with High Conformational Flexibility. Structure 2020; 28:507-515.e5. [PMID: 32187531 PMCID: PMC7203548 DOI: 10.1016/j.str.2020.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Revised: 01/29/2020] [Accepted: 02/27/2020] [Indexed: 11/25/2022]
Abstract
The transmembrane protein OTK plays an essential role in plexin and Wnt signaling during Drosophila development. We have determined a crystal structure of the last three domains of the OTK ectodomain and found that OTK shows high conformational flexibility resulting from mobility at the interdomain interfaces. We failed to detect direct binding between Drosophila Plexin A (PlexA) and OTK, which was suggested previously. We found that, instead of PlexA, OTK directly binds semaphorin 1a. Our binding analyses further revealed that glycosaminoglycans, heparin and heparan sulfate, are ligands for OTK and thus may play a role in the Sema1a-PlexA axon guidance system.
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Affiliation(s)
- Daniel Rozbesky
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
| | - Jim Monistrol
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Vitul Jain
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - James Hillier
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Sergi Padilla-Parra
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; Cellular imaging, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; Department of Infectious Diseases, King's College London, Faculty of Life Sciences & Medicine, London SE1 9RT, UK; Randall Centre for Cell and Molecular Biology, King's College London, London SE1 1UL, UK
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
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20
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Izumida M, Togawa K, Hayashi H, Matsuyama T, Kubo Y. Production of Vesicular Stomatitis Virus Glycoprotein-Pseudotyped Lentiviral Vector Is Enhanced by Ezrin Silencing. Front Bioeng Biotechnol 2020; 8:368. [PMID: 32411688 PMCID: PMC7201057 DOI: 10.3389/fbioe.2020.00368] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 04/02/2020] [Indexed: 11/17/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1)-based viral vector is widely used as a biomaterial to transfer a gene of interest into target cells in many biological study fields including gene therapy. Vesicular stomatitis virus glycoprotein (VSV-G)-containing HIV-1 vector much more efficiently transduces various mammalian cells than other viral envelope proteins-containing vectors. Understanding the mechanism would contribute to development of a novel method of efficient HIV-1 vector production. HIV-1 vector is generally constructed by transient transfection of human 293T or African green monkey COS7 cells. It was found in this study that HIV-1 Gag protein is constitutively digested in lysosomes of African green monkey cells. Surprisingly, VSV-G elevated HIV-1 Gag protein levels, suggesting that VSV-G protects Gag protein from the lysosomal degradation. Unphosphorylated ezrin, but not phosphorylated ezrin, was detected in COS7 cells, and ezrin silencing elevated Gag protein levels in the presence of VSV-G. Expression of unphosphorylated ezrin reduced Gag protein amounts. These results indicate that unphosphorylated ezrin proteins inhibit the VSV-G-mediated stabilization of HIV-1 Gag protein. Trafficking of HIV-1 Gag-associated intracellular vesicles may be controlled by ezrin. Finally, this study found that ezrin silencing yields higher amount of VSV-G-pseudotyped HIV-1 vector.
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Affiliation(s)
- Mai Izumida
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.,Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Kei Togawa
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Hideki Hayashi
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.,Medical University Research Administrator, Nagasaki University School of Medicine, Nagasaki, Japan
| | - Toshifumi Matsuyama
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.,Department of Cancer Stem Cell Biology, Institute of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Yoshinao Kubo
- Department of Molecular Microbiology and Immunology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.,Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.,Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
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21
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Carravilla P, Nieva JL, Eggeling C. Fluorescence Microscopy of the HIV-1 Envelope. Viruses 2020; 12:E348. [PMID: 32245254 PMCID: PMC7150788 DOI: 10.3390/v12030348] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 03/19/2020] [Accepted: 03/20/2020] [Indexed: 12/18/2022] Open
Abstract
Human immunodeficiency virus (HIV) infection constitutes a major health and social issue worldwide. HIV infects cells by fusing its envelope with the target cell plasma membrane. This process is mediated by the viral Env glycoprotein and depends on the envelope lipid composition. Fluorescent microscopy has been employed to investigate the envelope properties, and the processes of viral assembly and fusion, but the application of this technique to the study of HIV is still limited by a number of factors, such as the small size of HIV virions or the difficulty to label the envelope components. Here, we review fluorescence imaging studies of the envelope lipids and proteins, focusing on labelling strategies and model systems.
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Affiliation(s)
- Pablo Carravilla
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-University Jena, Max-Wien Platz 1, 07743 Jena, Germany;
- Leibniz Institute of Photonic Technology, Albert Einstein Strasse 9, 07743 Jena, Germany
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain;
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, E-48940 Leioa, Spain
| | - José L. Nieva
- Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080 Bilbao, Spain;
- Instituto Biofisika (UPV/EHU, CSIC), University of the Basque Country, E-48940 Leioa, Spain
| | - Christian Eggeling
- Institute of Applied Optics and Biophysics, Friedrich-Schiller-University Jena, Max-Wien Platz 1, 07743 Jena, Germany;
- Leibniz Institute of Photonic Technology, Albert Einstein Strasse 9, 07743 Jena, Germany
- MRC Weatherall Institute of Molecular Medicine, University of Oxford, Headley Way, Oxford OX3 9DS, UK
- Jena Center for Soft Matter (JCSM), Friedrich-Schiller-University Jena, Philosophenweg 7, 07743 Jena, Germany
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22
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Carlon-Andres I, Padilla-Parra S. Quantitative FRET-FLIM-BlaM to Assess the Extent of HIV-1 Fusion in Live Cells. Viruses 2020; 12:E206. [PMID: 32059513 PMCID: PMC7077196 DOI: 10.3390/v12020206] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 02/06/2020] [Accepted: 02/10/2020] [Indexed: 11/16/2022] Open
Abstract
The first steps of human immunodeficiency virus (HIV) infection go through the engagement of HIV envelope (Env) with CD4 and coreceptors (CXCR4 or CCR5) to mediate viral membrane fusion between the virus and the host. New approaches are still needed to better define both the molecular mechanistic underpinnings of this process but also the point of fusion and its kinetics. Here, we have developed a new method able to detect and quantify HIV-1 fusion in single live cells. We present a new approach that employs fluorescence lifetime imaging microscopy (FLIM) to detect Förster resonance energy transfer (FRET) when using the β-lactamase (BlaM) assay. This novel approach allows comparing different populations of single cells regardless the concentration of CCF2-AM FRET reporter in each cell, and more importantly, is able to determine the relative amount of viruses internalized per cell. We have applied this approach in both reporter TZM-bl cells and primary T cell lymphocytes.
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Affiliation(s)
| | - Sergi Padilla-Parra
- Division of Structural Biology, University of Oxford, Wellcome Centre for Human Genetics, Headington, Oxford OX3 7BN, UK;
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23
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Lin M, Da LT. Refolding Dynamics of gp41 from Pre-fusion to Pre-hairpin States during HIV-1 Entry. J Chem Inf Model 2019; 60:162-174. [DOI: 10.1021/acs.jcim.9b00746] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Mengna Lin
- Key Laboratory of System Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
| | - Lin-Tai Da
- Key Laboratory of System Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China
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24
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Da LT, Lin M. Opening dynamics of HIV-1 gp120 upon receptor binding is dictated by a key hydrophobic core. Phys Chem Chem Phys 2019; 21:26003-26016. [PMID: 31764922 DOI: 10.1039/c9cp04613e] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
HIV-1 entry is mediated firstly by the molecular recognition between the viral glycoprotein gp120 and its receptor CD4 on host T-cells. As a key antigen that can be targeted by neutralizing antibodies, gp120 has been a focus for extensive studies with efforts to understand its structural properties and conformational dynamics upon receptor binding. An atomistic-level revelation of gp120 opening dynamics activated by CD4, however, is still unknown. Here, by constructing a Markov State Model (MSM) based on hundreds of Molecular Dynamics (MD) simulations with an aggregated simulation time of ∼20 microseconds (μs), we identify the key metastable states of gp120 during its opening dynamics upon CD4 binding. The MSM provides a clear dynamic model whereby the identified metastable states coexist and can reach an equilibrium. More importantly, a hydrophobic core flanked by variable loops (V1V2 and V3) and the β20/21 region plays an essential role in triggering the gp120 opening. Any destabilizing effects introduced into the hydrophobic core, therefore, can be expected to promote transition of gp120 to an open state. Moreover, the variable loops demonstrate high flexibilities in fully open gp120. In particular, the V3 region is capable of exploring both closed and open conformations, even with the V1/V2 loops largely adopting an open form. In addition, the bridging sheet formation in gp120 is likely induced by the incoming co-receptor/antibody recognitions, since the V1/V2 structure is highly heterogeneous so that the bridging-sheet formed conformation is not the most populated state. Our studies provide deep insights into the dynamic features of gp120 and its molecular recognitions to the broadly neutralizing antibodies, which guides future attempts to design more effective gp120 immunogens.
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Affiliation(s)
- Lin-Tai Da
- Key Laboratory of System Biomedicine (Ministry of Education), Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240, China.
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25
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Developments in single-molecule and single-particle fluorescence-based approaches for studying viral envelope glycoprotein dynamics and membrane fusion. Adv Virus Res 2019; 104:123-146. [PMID: 31439147 DOI: 10.1016/bs.aivir.2019.05.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Fusion of viral and cellular membranes is an essential step in the entry pathway of all enveloped viruses. This is a dynamic and multistep process, which has been extensively studied, resulting in the endpoints of the reaction being firmly established, and many essential cellular factors identified. What remains is to elucidate the dynamic events that underlie this process, including the order and timing of glycoprotein conformational changes, receptor-binding events, and movement of the glycoprotein on the surface of the virion. Due to the inherently asynchronous nature of these dynamics, there has been an increased focus on the study of single virions and single molecules. These techniques provide researchers the high precision and resolution necessary to bridge the gaps in our understanding of viral membrane fusion. This review highlights the advancement of single-molecule and single-particle fluorescence-based techniques, with a specific focus on how these techniques have been used to study the dynamic nature of the viral fusion pathway.
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26
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Chen B. Molecular Mechanism of HIV-1 Entry. Trends Microbiol 2019; 27:878-891. [PMID: 31262533 DOI: 10.1016/j.tim.2019.06.002] [Citation(s) in RCA: 161] [Impact Index Per Article: 32.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 05/20/2019] [Accepted: 06/05/2019] [Indexed: 11/19/2022]
Abstract
HIV-1 envelope glycoprotein [Env; trimeric (gp160)3 cleaved to (gp120/gp41)3] attaches the virion to a susceptible cell and induces fusion of viral and cell membranes to initiate infection. It interacts with the primary receptor CD4 and coreceptor (e.g., chemokine receptor CCR5 or CXCR4) to allow viral entry by triggering large structural rearrangements and unleashing the fusogenic potential of gp41 to induce membrane fusion. Recent advances in structural biology of HIV-1 Env and its complexes with the cellular receptors have revealed molecular details of HIV-1 entry and yielded new mechanistic insights. In this review, I summarize our latest understanding of the HIV-1 membrane fusion process and discuss possible pathways for productive viral entry.
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Affiliation(s)
- Bing Chen
- Division of Molecular Medicine, Boston Children's Hospital, and Department of Pediatrics, Harvard Medical School, 3 Blackfan Street, Boston, MA 02115, USA.
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27
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Pereira PM, Albrecht D, Culley S, Jacobs C, Marsh M, Mercer J, Henriques R. Fix Your Membrane Receptor Imaging: Actin Cytoskeleton and CD4 Membrane Organization Disruption by Chemical Fixation. Front Immunol 2019; 10:675. [PMID: 31024536 PMCID: PMC6460894 DOI: 10.3389/fimmu.2019.00675] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 03/12/2019] [Indexed: 12/25/2022] Open
Abstract
Single-molecule localization microscopy (SMLM) techniques allow near molecular scale resolution (~ 20 nm) as well as precise and robust analysis of protein organization at different scales. SMLM hardware, analytics and probes have been the focus of a variety of studies and are now commonly used in laboratories across the world. Protocol reliability and artifact identification are increasingly seen as important aspects of super-resolution microscopy. The reliability of these approaches thus requires in-depth evaluation so that biological findings are based on solid foundations. Here we explore how different fixation approaches that disrupt or preserve the actin cytoskeleton affect membrane protein organization. Using CD4 as a model, we show that fixation-mediated disruption of the actin cytoskeleton correlates with changes in CD4 membrane organization. We highlight how these artifacts are easy to overlook and how careful sample preparation is essential for extracting meaningful results from super-resolution microscopy.
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Affiliation(s)
- Pedro M. Pereira
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
| | - David Albrecht
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Siân Culley
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
| | - Caron Jacobs
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Mark Marsh
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Jason Mercer
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
| | - Ricardo Henriques
- MRC-Laboratory for Molecular Cell Biology, University College London, London, United Kingdom
- The Francis Crick Institute, London, United Kingdom
- Institute for the Physics of Living Systems, University College London, London, United Kingdom
- Department of Cell and Developmental Biology, University College London, London, United Kingdom
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28
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Ivan B, Sun Z, Subbaraman H, Friedrich N, Trkola A. CD4 occupancy triggers sequential pre-fusion conformational states of the HIV-1 envelope trimer with relevance for broadly neutralizing antibody activity. PLoS Biol 2019; 17:e3000114. [PMID: 30650070 PMCID: PMC6351000 DOI: 10.1371/journal.pbio.3000114] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 01/29/2019] [Accepted: 01/04/2019] [Indexed: 12/18/2022] Open
Abstract
During the entry process, the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) trimer undergoes a sequence of conformational changes triggered by both CD4 and coreceptor engagement. Resolving the conformation of these transient entry intermediates has proven challenging. Here, we fine-mapped the antigenicity of entry intermediates induced by increasing CD4 engagement of cell surface–expressed Env. Escalating CD4 triggering led to the sequential adoption of different pre-fusion conformational states of the Env trimer, up to the pre-hairpin conformation, that we assessed for antibody epitope presentation. Maximal accessibility of the coreceptor binding site was detected below Env saturation by CD4. Exposure of the fusion peptide and heptad repeat 1 (HR1) required higher CD4 occupancy. Analyzing the diverse antigenic states of the Env trimer, we obtained key insights into the transitions in epitope accessibility of broadly neutralizing antibodies (bnAbs). Several bnAbs preferentially bound CD4-triggered Env, indicating a potential capacity to neutralize both pre- and post-CD4 engagement, which needs to be explored. Assessing binding and neutralization activity of bnAbs, we confirm antibody dissociation rates as a driver of incomplete neutralization. Collectively, our findings highlight a need to resolve Env conformations that are neutralization-relevant to provide guidance for immunogen development. Comprehensive mapping of conformational stages adopted by the HIV‐1 envelope glycoprotein trimer during entry into the cell reveals the preference of broadly neutralizing antibodies for distinct pre-fusion states of the trimer. The trimeric human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) mediates HIV-1 entry into its target cells. Entry is initiated by sequential triggering of Env upon interaction with its primary receptor CD4 and a coreceptor on target cells. The ensuing structural rearrangements of the Env trimer bring the viral membrane in close vicinity of the cellular membrane, enabling fusion. Resolving the structural differences between the consecutive conformations Env adopts during the entry process is of high interest, as different antigenic domains are exposed, which may affect the capacity of neutralizing antibodies to bind to Env and inhibit entry. Here, we compared the conformation of unliganded closed Env with the transitional CD4-bound Env forms by studying the antigenicity of cell surface–expressed Env with and without CD4 triggering. We show that incremental triggering by soluble CD4 allows the capture of the full continuum of conformational changes, including events that follow coreceptor interaction. Thus, the setup we introduce here turns a simple binding assay into a powerful tool to study transitional conformation changes in HIV-1 Env. Analyzing the capacity of Env-reactive antibodies to recognize the diverse Env stages, our study reveals novel aspects of the binding preferences of neutralizing antibodies that affect their inhibitory activity.
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Affiliation(s)
- Branislav Ivan
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Zhaozhi Sun
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Harini Subbaraman
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Nikolas Friedrich
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
| | - Alexandra Trkola
- Institute of Medical Virology, University of Zurich, Zurich, Switzerland
- * E-mail:
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