1
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Ao Y, Grover JR, Gifford L, Han Y, Zhong G, Katte R, Li W, Bhattacharjee R, Zhang B, Sauve S, Qin W, Ghimire D, Haque MA, Arthos J, Moradi M, Mothes W, Lemke EA, Kwong PD, Melikyan GB, Lu M. Bioorthogonal click labeling of an amber-free HIV-1 provirus for in-virus single molecule imaging. Cell Chem Biol 2024; 31:487-501.e7. [PMID: 38232732 PMCID: PMC10960674 DOI: 10.1016/j.chembiol.2023.12.017] [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: 03/27/2023] [Revised: 10/13/2023] [Accepted: 12/21/2023] [Indexed: 01/19/2024]
Abstract
Structural dynamics of human immunodeficiency virus 1 (HIV-1) envelope (Env) glycoprotein mediate cell entry and facilitate immune evasion. Single-molecule FRET using peptides for Env labeling revealed structural dynamics of Env, but peptide use risks potential effects on structural integrity/dynamics. While incorporating noncanonical amino acids (ncAAs) into Env by amber stop-codon suppression, followed by click chemistry, offers a minimally invasive approach, this has proved to be technically challenging for HIV-1. Here, we develope an intact amber-free HIV-1 system that overcomes hurdles of preexisting viral amber codons. We achieved dual-ncAA incorporation into Env on amber-free virions, enabling single-molecule Förster resonance energy transfer (smFRET) studies of click-labeled Env that validated the previous peptide-based labeling approaches by confirming the intrinsic propensity of Env to dynamically sample multiple conformational states. Amber-free click-labeled Env also enabled real-time tracking of single virion internalization and trafficking in cells. Our system thus permits in-virus bioorthogonal labeling of proteins, compatible with studies of virus entry, trafficking, and egress from cells.
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Affiliation(s)
- Yuanyun Ao
- Department of Cellular and Molecular Biology, School of Medicine, University of Texas at Tyler Health Science Center, Tyler, TX 75708, USA
| | - Jonathan R Grover
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Levi Gifford
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Yang Han
- Department of Cellular and Molecular Biology, School of Medicine, University of Texas at Tyler Health Science Center, Tyler, TX 75708, USA
| | - Guohua Zhong
- Department of Cellular and Molecular Biology, School of Medicine, University of Texas at Tyler Health Science Center, Tyler, TX 75708, USA
| | - Revansiddha Katte
- Department of Cellular and Molecular Biology, School of Medicine, University of Texas at Tyler Health Science Center, Tyler, TX 75708, USA
| | - Wenwei Li
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Rajanya Bhattacharjee
- Biocentre, Departments of Biology and Chemistry, Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany; International PhD Program of the Institute of Molecular Biology, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany
| | - Baoshan Zhang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephanie Sauve
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Wenyi Qin
- Department of Cellular and Molecular Biology, School of Medicine, University of Texas at Tyler Health Science Center, Tyler, TX 75708, USA
| | - Dibya Ghimire
- Department of Cellular and Molecular Biology, School of Medicine, University of Texas at Tyler Health Science Center, Tyler, TX 75708, USA
| | - Md Anzarul Haque
- Department of Cellular and Molecular Biology, School of Medicine, University of Texas at Tyler Health Science Center, Tyler, TX 75708, USA
| | - James Arthos
- Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, USA
| | - Walther Mothes
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06510, USA
| | - Edward A Lemke
- Biocentre, Departments of Biology and Chemistry, Johannes Gutenberg-University Mainz, Hanns-Dieter-Hüsch-Weg 17, 55128 Mainz, Germany; Institute of Molecular Biology, Ackermannweg 4, 55128 Mainz, Germany
| | - Peter D Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gregory B Melikyan
- Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Maolin Lu
- Department of Cellular and Molecular Biology, School of Medicine, University of Texas at Tyler Health Science Center, Tyler, TX 75708, USA.
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2
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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: 2] [Impact Index Per Article: 2.0] [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.
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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
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3
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Volpato A, Ollech D, Alvelid J, Damenti M, Müller B, York AG, Ingaramo M, Testa I. Extending fluorescence anisotropy to large complexes using reversibly switchable proteins. Nat Biotechnol 2023; 41:552-559. [PMID: 36217028 PMCID: PMC10110461 DOI: 10.1038/s41587-022-01489-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 08/26/2022] [Indexed: 11/08/2022]
Abstract
The formation of macromolecular complexes can be measured by detection of changes in rotational mobility using time-resolved fluorescence anisotropy. However, this method is limited to relatively small molecules (~0.1-30 kDa), excluding the majority of the human proteome and its complexes. We describe selective time-resolved anisotropy with reversibly switchable states (STARSS), which overcomes this limitation and extends the observable mass range by more than three orders of magnitude. STARSS is based on long-lived reversible molecular transitions of switchable fluorescent proteins to resolve the relatively slow rotational diffusivity of large complexes. We used STARSS to probe the rotational mobility of several molecular complexes in cells, including chromatin, the retroviral Gag lattice and activity-regulated cytoskeleton-associated protein oligomers. Because STARSS can probe arbitrarily large structures, it is generally applicable to the entire human proteome.
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Affiliation(s)
- Andrea Volpato
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Dirk Ollech
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Jonatan Alvelid
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Martina Damenti
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Barbara Müller
- Department of Infectious Diseases, Virology, Centre for Integrative Infectious Disease Research, University Hospital Heidelberg, Heidelberg, Germany
| | - Andrew G York
- Calico Life Sciences LLC, South San Francisco, CA, USA
| | | | - Ilaria Testa
- Department of Applied Physics and Science for Life Laboratory, KTH Royal Institute of Technology, Stockholm, Sweden.
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4
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Ao Y, Grover JR, Han Y, Zhong G, Qin W, Ghimire D, Haque A, Bhattacharjee R, Zhang B, Arthos J, Lemke EA, Kwong PD, Lu M. An intact amber-free HIV-1 system for in-virus protein bioorthogonal click labeling that delineates envelope conformational dynamics. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.28.530526. [PMID: 36909529 PMCID: PMC10002649 DOI: 10.1101/2023.02.28.530526] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
The HIV-1 envelope (Env) glycoprotein is conformationally dynamic and mediates membrane fusion required for cell entry. Single-molecule fluorescence resonance energy transfer (smFRET) of Env using peptide tags has provided mechanistic insights into the dynamics of Env conformations. Nevertheless, using peptide tags risks potential effects on structural integrity. Here, we aim to establish minimally invasive smFRET systems of Env on the virus by combining genetic code expansion and bioorthogonal click chemistry. Amber stop-codon suppression allows site-specifically incorporating noncanonical/unnatural amino acids (ncAAs) at introduced amber sites into proteins. However, ncAA incorporation into Env (or other HIV-1 proteins) in the virus context has been challenging due to low copies of Env on virions and incomplete amber suppression in mammalian cells. Here, we developed an intact amber-free virus system that overcomes impediments from preexisting ambers in HIV-1. Using this system, we successfully incorporated dual ncAAs at amber-introduced sites into Env on intact virions. Dual-ncAA incorporated Env retained similar neutralization sensitivities to neutralizing antibodies as wildtype. smFRET of click-labeled Env on intact amber-free virions recapitulated conformational profiles of Env. The amber-free HIV-1 infectious system also permits in-virus protein bioorthogonal labeling, compatible with various advanced microscopic studies of virus entry, trafficking, and egress in living cells. Amber-free HIV-1 infectious systems actualized minimal invasive Env tagging for smFRET, versatile for in-virus bioorthogonal click labeling in advanced microscopic studies of virus-host interactions.
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5
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Negi G, Sharma A, Dey M, Dhanawat G, Parveen N. Membrane attachment and fusion of HIV-1, influenza A, and SARS-CoV-2: resolving the mechanisms with biophysical methods. Biophys Rev 2022; 14:1109-1140. [PMID: 36249860 PMCID: PMC9552142 DOI: 10.1007/s12551-022-00999-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 09/16/2022] [Indexed: 10/31/2022] Open
Abstract
Attachment to and fusion with cell membranes are two major steps in the replication cycle of many human viruses. We focus on these steps for three enveloped viruses, i.e., HIV-1, IAVs, and SARS-CoV-2. Viral spike proteins drive the membrane attachment and fusion of these viruses. Dynamic interactions between the spike proteins and membrane receptors trigger their specific attachment to the plasma membrane of host cells. A single virion on cell membranes can engage in binding with multiple receptors of the same or different types. Such dynamic and multivalent binding of these viruses result in an optimal attachment strength which in turn leads to their cellular entry and membrane fusion. The latter process is driven by conformational changes of the spike proteins which are also class I fusion proteins, providing the energetics of membrane tethering, bending, and fusion. These viruses exploit cellular and membrane factors in regulating the conformation changes and membrane processes. Herein, we describe the major structural and functional features of spike proteins of the enveloped viruses including highlights on their structural dynamics. The review delves into some of the case studies in the literature discussing the findings on multivalent binding, membrane hemifusion, and fusion of these viruses. The focus is on applications of biophysical tools with an emphasis on single-particle methods for evaluating mechanisms of these processes at the molecular and cellular levels.
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Affiliation(s)
- Geetanjali Negi
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India
| | - Anurag Sharma
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India
| | - Manorama Dey
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India
| | - Garvita Dhanawat
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India
| | - Nagma Parveen
- Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, India
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6
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Dynamics of HIV-1 Gag Processing as Revealed by Fluorescence Lifetime Imaging Microscopy and Single Virus Tracking. Viruses 2022; 14:v14020340. [PMID: 35215933 PMCID: PMC8874525 DOI: 10.3390/v14020340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/04/2022] [Accepted: 02/06/2022] [Indexed: 12/04/2022] Open
Abstract
The viral polyprotein Gag plays a central role for HIV-1 assembly, release and maturation. Proteolytic processing of Gag by the viral protease is essential for the structural rearrangements that mark the transition from immature to mature, infectious viruses. The timing and kinetics of Gag processing are not fully understood. Here, fluorescence lifetime imaging microscopy and single virus tracking are used to follow Gag processing in nascent HIV-1 particles in situ. Using a Gag polyprotein labelled internally with eCFP, we show that proteolytic release of the fluorophore from Gag is accompanied by an increase in its fluorescence lifetime. By tracking nascent virus particles in situ and analyzing the intensity and fluorescence lifetime of individual traces, we detect proteolytic cleavage of eCFP from Gag in a subset (6.5%) of viral particles. This suggests that for the majority of VLPs, Gag processing occurs with a delay after particle assembly.
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7
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Qu K, Ke Z, Zila V, Anders-Össwein M, Glass B, Mücksch F, Müller R, Schultz C, Müller B, Kräusslich HG, Briggs JAG. Maturation of the matrix and viral membrane of HIV-1. Science 2021; 373:700-704. [PMID: 34353956 DOI: 10.1126/science.abe6821] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 06/24/2021] [Indexed: 12/22/2022]
Abstract
Gag, the primary structural protein of HIV-1, is recruited to the plasma membrane for virus assembly by its matrix (MA) domain. Gag is subsequently cleaved into its component domains, causing structural maturation to repurpose the virion for cell entry. We determined the structure and arrangement of MA within immature and mature HIV-1 through cryo-electron tomography. We found that MA rearranges between two different hexameric lattices upon maturation. In mature HIV-1, a lipid extends out of the membrane to bind with a pocket in MA. Our data suggest that proteolytic maturation of HIV-1 not only assembles the viral capsid surrounding the genome but also repurposes the membrane-bound MA lattice for an entry or postentry function and results in the partial removal of up to 2500 lipids from the viral membrane.
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Affiliation(s)
- Kun Qu
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany
| | - Zunlong Ke
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany.,Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK
| | - Vojtech Zila
- Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Maria Anders-Össwein
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Bärbel Glass
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Frauke Mücksch
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Rainer Müller
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Carsten Schultz
- Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
| | - Barbara Müller
- Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany.,German Center for Infection Research, Heidelberg, Germany
| | - John A G Briggs
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, 69120 Heidelberg, Germany. .,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany.,Structural Studies Division, Medical Research Council Laboratory of Molecular Biology, CB2 0QH Cambridge, UK.,Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.,Molecular Medicine Partnership Unit, European Molecular Biology Laboratory and Universitätsklinikum Heidelberg, 69117 Heidelberg, Germany
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8
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Ritter C, Wollmann T, Lee JY, Imle A, Müller B, Fackler OT, Bartenschlager R, Rohr K. Data fusion and smoothing for probabilistic tracking of viral structures in fluorescence microscopy images. Med Image Anal 2021; 73:102168. [PMID: 34340105 DOI: 10.1016/j.media.2021.102168] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 06/10/2021] [Accepted: 07/07/2021] [Indexed: 10/20/2022]
Abstract
Automatic tracking of viral structures displayed as small spots in fluorescence microscopy images is an important task to determine quantitative information about cellular processes. We introduce a novel probabilistic approach for tracking multiple particles based on multi-sensor data fusion and Bayesian smoothing methods. The approach exploits multiple measurements as in a particle filter, both detection-based measurements and prediction-based measurements from a Kalman filter using probabilistic data association with elliptical sampling. Compared to previous probabilistic tracking methods, our approach exploits separate uncertainties for the detection-based and prediction-based measurements, and integrates them by a sequential multi-sensor data fusion method. In addition, information from both past and future time points is taken into account by a Bayesian smoothing method in conjunction with the covariance intersection algorithm for data fusion. Also, motion information based on displacements is used to improve correspondence finding. Our approach has been evaluated on data of the Particle Tracking Challenge and yielded state-of-the-art results or outperformed previous approaches. We also applied our approach to challenging time-lapse fluorescence microscopy data of human immunodeficiency virus type 1 and hepatitis C virus proteins acquired with different types of microscopes and spatial-temporal resolutions. It turned out, that our approach outperforms existing methods.
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Affiliation(s)
- C Ritter
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Im Neuenheimer Feld 267, Heidelberg, Germany.
| | - T Wollmann
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Im Neuenheimer Feld 267, Heidelberg, Germany
| | - J-Y Lee
- Dept. of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - A Imle
- Dept. of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, Heidelberg, Germany; Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, Heidelberg, Germany
| | - B Müller
- Dept. of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, Heidelberg, Germany
| | - O T Fackler
- Dept. of Infectious Diseases, Integrative Virology, University Hospital Heidelberg, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - R Bartenschlager
- Dept. of Infectious Diseases, Molecular Virology, Heidelberg University, Im Neuenheimer Feld 344, Heidelberg, Germany; German Center for Infection Research (DZIF), Heidelberg Partner Site, Germany
| | - K Rohr
- Biomedical Computer Vision Group, BioQuant, IPMB, Heidelberg University, Im Neuenheimer Feld 267, Heidelberg, Germany.
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9
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Kalusche S, Vanshylla K, Kleipass F, Gruell H, Müller B, Zeng Z, Koch K, Stein S, Marcotte H, Klein F, Dietrich U. Lactobacilli Expressing Broadly Neutralizing Nanobodies against HIV-1 as Potential Vectors for HIV-1 Prophylaxis? Vaccines (Basel) 2020; 8:E758. [PMID: 33322227 PMCID: PMC7768517 DOI: 10.3390/vaccines8040758] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 12/07/2020] [Accepted: 12/11/2020] [Indexed: 12/27/2022] Open
Abstract
In the absence of an active prophylactic vaccine against HIV-1, passively administered, broadly neutralizing antibodies (bnAbs) identified in some chronically infected persons were shown to prevent HIV-1 infection in animal models. However, passive administration of bnAbs may not be suited to prevent sexual HIV-1 transmission in high-risk cohorts, as a continuous high level of active bnAbs may be difficult to achieve at the primary site of sexual transmission, the human vagina with its acidic pH. Therefore, we used Lactobacillus, a natural commensal in the healthy vaginal microbiome, to express bn nanobodies (VHH) against HIV-1 that we reported previously. After demonstrating that recombinant VHHA6 expressed in E. coli was able to protect humanized mice from mucosal infection by HIV-1Bal, we expressed VHHA6 in a soluble or in a cell-wall-anchored form in Lactobacillus rhamnosus DSM14870. This strain is already clinically applied for treatment of bacterial vaginosis. Both forms of VHHA6 neutralized a set of primary epidemiologically relevant HIV-1 strains in vitro. Furthermore, VHHA6 was still active at an acidic pH. Thus, lactobacilli expressing bn VHH potentially represent an attractive vector for the passive immunization of women in cohorts at high risk of HIV-1 transmission.
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Affiliation(s)
- Sarah Kalusche
- Georg-Speyer-Haus, Paul-Ehrlich-Straße 42-44, 60596 Frankfurt, Germany; (S.K.); (K.K.); (S.S.)
| | - Kanika Vanshylla
- Laboratory of Experimental Immunology, Institute of Virology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50931 Cologne, Germany; (K.V.); (F.K.); (H.G.)
| | - Franziska Kleipass
- Laboratory of Experimental Immunology, Institute of Virology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50931 Cologne, Germany; (K.V.); (F.K.); (H.G.)
| | - Henning Gruell
- Laboratory of Experimental Immunology, Institute of Virology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50931 Cologne, Germany; (K.V.); (F.K.); (H.G.)
| | - Barbara Müller
- Department of Infectious Diseases, Virology Centre for Integrative Infectious Diseases Research (CIID), University Hospital Heidelberg, 69120 Heidelberg, Germany;
| | - Zhu Zeng
- Department of Laboratory Medicine, Division of Clinical Immunology and Transfusion Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, 14186 Stockholm, Sweden;
| | - Kathrin Koch
- Georg-Speyer-Haus, Paul-Ehrlich-Straße 42-44, 60596 Frankfurt, Germany; (S.K.); (K.K.); (S.S.)
| | - Stefan Stein
- Georg-Speyer-Haus, Paul-Ehrlich-Straße 42-44, 60596 Frankfurt, Germany; (S.K.); (K.K.); (S.S.)
| | - Harold Marcotte
- Department of Laboratory Medicine, Division of Clinical Immunology and Transfusion Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, 14186 Stockholm, Sweden;
| | - Florian Klein
- Laboratory of Experimental Immunology, Institute of Virology, Faculty of Medicine and University Hospital Cologne, University of Cologne, 50931 Cologne, Germany; (K.V.); (F.K.); (H.G.)
| | - Ursula Dietrich
- Georg-Speyer-Haus, Paul-Ehrlich-Straße 42-44, 60596 Frankfurt, Germany; (S.K.); (K.K.); (S.S.)
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10
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Farrants H, Tarnawski M, Müller TG, Otsuka S, Hiblot J, Koch B, Kueblbeck M, Kräusslich HG, Ellenberg J, Johnsson K. Chemogenetic Control of Nanobodies. Nat Methods 2020; 17:279-282. [PMID: 32066961 DOI: 10.1038/s41592-020-0746-7] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 12/01/2019] [Accepted: 01/15/2020] [Indexed: 12/30/2022]
Abstract
We introduce an engineered nanobody whose affinity to green fluorescent protein (GFP) can be switched on and off with small molecules. By controlling the cellular localization of GFP fusion proteins, the engineered nanobody allows interrogation of their roles in basic biological processes, an approach that should be applicable to numerous previously described GFP fusions. We also outline how the binding affinities of other nanobodies can be controlled by small molecules.
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Affiliation(s)
- Helen Farrants
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany.,Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Miroslaw Tarnawski
- Protein Expression and Characterization Facility, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Thorsten G Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Shotaro Otsuka
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany.,Max Perutz Labs, a joint venture of the University of Vienna and the Medical University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | - Julien Hiblot
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Birgit Koch
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Moritz Kueblbeck
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Jan Ellenberg
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Kai Johnsson
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany. .,Institute of Chemical Sciences and Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
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11
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Abstract
The HIV-1 capsid performs essential functions during early viral replication and is an interesting target for novel antivirals. Thus, understanding molecular and structural details of capsid function will be important for elucidating early HIV-1 (and retroviral in general) replication in relevant target cells and may also aid antiviral development. Here, we show that HIV-1 capsids stay largely intact during transport to the nucleus of infected T cells but appear to uncoat upon entry into the nucleoplasm. These results support the hypothesis that capsids protect the HIV-1 genome from cytoplasmic defense mechanisms and target the genome toward the nucleus. A protective role of the capsid could be a paradigm that also applies to other viruses. Our findings raise the question of how reverse transcription of the HIV-1 genome is accomplished in the context of the capsid structure and whether the process is completed before the capsid is uncoated at the nuclear pore. HIV-1 infects host cells by fusion at the plasma membrane, leading to cytoplasmic entry of the viral capsid encasing the genome and replication machinery. The capsid eventually needs to disassemble, but time and location of uncoating are not fully characterized and may vary depending on the host cell. To study the fate of the capsid by fluorescence and superresolution (STED) microscopy, we established an experimental system that allows discrimination of subviral structures in the cytosol from intact virions at the plasma membrane or in endosomes without genetic modification of the virus. Quantitative microscopy of infected SupT1-R5 cells revealed that the CA signal on cytosolic HIV-1 complexes corresponded to ∼50% of that found in virions at the cell surface, in agreement with dissociation of nonassembled CA molecules from entering capsids after membrane fusion. The relative amount of CA in postfusion complexes remained stable until they reached the nuclear pore complex, while subviral structures in the nucleus of infected cells lacked detectable CA. An HIV-1 variant defective in binding of the host protein cleavage and polyadenylation specificity factor 6 (CPSF6) exhibited accumulation of CA-positive subviral complexes close to the nuclear envelope without loss of infectivity; STED microscopy revealed direct association of these complexes with nuclear pores. These results support previous observations indicating capsid uncoating at the nuclear pore in infected T-cell lines. They suggest that largely intact HIV-1 capsids dock at the nuclear pore in infected SupT1-R5 cells, with CPSF6 being a facilitator of nucleoplasmic entry in this cell type, as has been observed for infected macrophages.
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12
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Imle A, Kumberger P, Schnellbächer ND, Fehr J, Carrillo-Bustamante P, Ales J, Schmidt P, Ritter C, Godinez WJ, Müller B, Rohr K, Hamprecht FA, Schwarz US, Graw F, Fackler OT. Experimental and computational analyses reveal that environmental restrictions shape HIV-1 spread in 3D cultures. Nat Commun 2019; 10:2144. [PMID: 31086185 PMCID: PMC6514199 DOI: 10.1038/s41467-019-09879-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 04/04/2019] [Indexed: 11/09/2022] Open
Abstract
Pathogens face varying microenvironments in vivo, but suitable experimental systems and analysis tools to dissect how three-dimensional (3D) tissue environments impact pathogen spread are lacking. Here we develop an Integrative method to Study Pathogen spread by Experiment and Computation within Tissue-like 3D cultures (INSPECT-3D), combining quantification of pathogen replication with imaging to study single-cell and cell population dynamics. We apply INSPECT-3D to analyze HIV-1 spread between primary human CD4 T-lymphocytes using collagen as tissue-like 3D-scaffold. Measurements of virus replication, infectivity, diffusion, cellular motility and interactions are combined by mathematical analyses into an integrated spatial infection model to estimate parameters governing HIV-1 spread. This reveals that environmental restrictions limit infection by cell-free virions but promote cell-associated HIV-1 transmission. Experimental validation identifies cell motility and density as essential determinants of efficacy and mode of HIV-1 spread in 3D. INSPECT-3D represents an adaptable method for quantitative time-resolved analyses of 3D pathogen spread. Here, using an integrative experimental and computational approach, Imle et al. show how cell motility and density affect HIV cell-associated transmission in a three-dimensional tissue-like culture system of CD4+ T cells and collagen, and how different collagen matrices restrict infection by cell-free virions.
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Affiliation(s)
- Andrea Imle
- Department of Infectious Diseases, Centre for Integrative Infectious Disease Research (CIID), Integrative Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany.,Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, 69117, Heidelberg, Germany
| | - Peter Kumberger
- Centre for Modelling and Simulation in the Biosciences, BioQuant, Heidelberg University, 69120, Heidelberg, Germany
| | - Nikolas D Schnellbächer
- Institute for Theoretical Physics and BioQuant, Heidelberg University, 69120, Heidelberg, Germany
| | - Jana Fehr
- Centre for Modelling and Simulation in the Biosciences, BioQuant, Heidelberg University, 69120, Heidelberg, Germany.,Digital Health & Machine Learning, Hasso-Plattner Institute, 14482, Potsdam, Germany
| | - Paola Carrillo-Bustamante
- Centre for Modelling and Simulation in the Biosciences, BioQuant, Heidelberg University, 69120, Heidelberg, Germany.,Vector Biology Unit, Max-Planck Institute for Infection Biology, 10117, Berlin, Germany
| | - Janez Ales
- HCI/IWR, Heidelberg University, 69120, Heidelberg, Germany
| | - Philip Schmidt
- HCI/IWR, Heidelberg University, 69120, Heidelberg, Germany
| | - Christian Ritter
- Biomedical Computer Vision Group, BioQuant, IPMB, and DKFZ, Heidelberg University, 69120, Heidelberg, Germany
| | - William J Godinez
- Biomedical Computer Vision Group, BioQuant, IPMB, and DKFZ, Heidelberg University, 69120, Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Centre for Integrative Infectious Disease Research (CIID), Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany
| | - Karl Rohr
- Biomedical Computer Vision Group, BioQuant, IPMB, and DKFZ, Heidelberg University, 69120, Heidelberg, Germany
| | | | - Ulrich S Schwarz
- Institute for Theoretical Physics and BioQuant, Heidelberg University, 69120, Heidelberg, Germany
| | - Frederik Graw
- Centre for Modelling and Simulation in the Biosciences, BioQuant, Heidelberg University, 69120, Heidelberg, Germany
| | - Oliver T Fackler
- Department of Infectious Diseases, Centre for Integrative Infectious Disease Research (CIID), Integrative Virology, University Hospital Heidelberg, 69120, Heidelberg, Germany. .,German Centre for Infection Research (DZIF), Partner Site Heidelberg, Heidelberg, Germany.
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13
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Carravilla P, Chojnacki J, Rujas E, Insausti S, Largo E, Waithe D, Apellaniz B, Sicard T, Julien JP, Eggeling C, Nieva JL. Molecular recognition of the native HIV-1 MPER revealed by STED microscopy of single virions. Nat Commun 2019; 10:78. [PMID: 30622256 PMCID: PMC6325134 DOI: 10.1038/s41467-018-07962-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 12/07/2018] [Indexed: 11/09/2022] Open
Abstract
Antibodies against the Membrane-Proximal External Region (MPER) of the Env gp41 subunit neutralize HIV-1 with exceptional breadth and potency. Due to the lack of knowledge on the MPER native structure and accessibility, different and exclusive models have been proposed for the molecular mechanism of MPER recognition by broadly neutralizing antibodies. Here, accessibility of antibodies to the native Env MPER on single virions has been addressed through STED microscopy. STED imaging of fluorescently labeled Fabs reveals a common pattern of native Env recognition for HIV-1 antibodies targeting MPER or the surface subunit gp120. In the case of anti-MPER antibodies, the process evolves with extra contribution of interactions with the viral lipid membrane to binding specificity. Our data provide biophysical insights into the recognition of the potent and broadly neutralizing MPER epitope on HIV virions, and as such is of importance for the design of therapeutic interventions.
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Affiliation(s)
- Pablo Carravilla
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain
| | - Jakub Chojnacki
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Edurne Rujas
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain
| | - Sara Insausti
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain
| | - Eneko Largo
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain
| | - Dominic Waithe
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Beatriz Apellaniz
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain
| | - Taylor Sicard
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Jean-Philippe Julien
- Program in Molecular Medicine, The Hospital for Sick Children Research Institute, Toronto, ON, M5G 0A4, Canada
- Department of Biochemistry, University of Toronto, Toronto, ON, M5S 1A8, Canada
- Department of Immunology, University of Toronto, Toronto, ON, M5S 1A8, Canada
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
- Institute of Applied Optics Friedrich-Schiller-University Jena, Max-Wien Platz 4, 07743, Jena, Germany.
- Leibniz Institute of Photonic Technology e.V., Albert-Einstein-Straße 9, 07745, Jena, Germany.
| | - José L Nieva
- Biofisika Institute (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain.
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14
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Li Q, Yin W, Li W, Zhang Z, Zhang X, Zhang XE, Cui Z. Encapsulating Quantum Dots within HIV-1 Virions through Site-Specific Decoration of the Matrix Protein Enables Single Virus Tracking in Live Primary Macrophages. NANO LETTERS 2018; 18:7457-7468. [PMID: 30398057 DOI: 10.1021/acs.nanolett.8b02800] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Labeling and imaging with quantum dots (QDs) provides powerful tools to visualize viral infection in living cells. Encapsulating QDs within virions represents a novel strategy for virus labeling. Here, we developed infectious HIV-1 virions encapsulating QDs through site-specific decoration of the viral matrix protein (MA) and used them to visualize early infection events in human primary macrophages by single-particle imaging. The MA protein was fused to a biotin acceptor peptide (BAP) tag, biotinylated, complexed with streptavidin-conjugated QDs in live cells, and incorporated into virions during virus assembly. The QD-encapsulated virions were tracked during infection of macrophages at a single particle level. The dynamic dissociation of MA and Vpr was also tracked in real time, and the results demonstrated that MA has multiple dynamic behaviors and functions during virus entry. More importantly, we tracked the dynamic interplay of QD-encapsulated virions with cellular mitochondria in live primary macrophages. We also found that HIV-1 can induce fission of mitochondria during the early phases of infection. In summary, we have constructed a type of QD-encapsulated virus particle and used this technology to further our understanding of the early events of HIV-1 infection.
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Affiliation(s)
- Qin Li
- State Key Laboratory of Virology, Wuhan Institute of Virology , Chinese Academy of Sciences , Wuhan , People's Republic of China
- Engineering Research Center of Industrial Microbiology, Ministry of Education, College of Life Sciences , Fujian Normal University , Fujian 350007 , People's Republic of China
| | - Wen Yin
- State Key Laboratory of Virology, Wuhan Institute of Virology , Chinese Academy of Sciences , Wuhan , People's Republic of China
| | - Wei Li
- State Key Laboratory of Virology, Wuhan Institute of Virology , Chinese Academy of Sciences , Wuhan , People's Republic of China
| | - Zhiping Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology , Chinese Academy of Sciences , Wuhan , People's Republic of China
| | - Xiaowei Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology , Chinese Academy of Sciences , Wuhan , People's Republic of China
| | - Xian-En Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics , Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Zongqiang Cui
- State Key Laboratory of Virology, Wuhan Institute of Virology , Chinese Academy of Sciences , Wuhan , People's Republic of China
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15
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Keller BM, Maier J, Secker KA, Egetemaier SM, Parfyonova Y, Rothbauer U, Traenkle B. Chromobodies to Quantify Changes of Endogenous Protein Concentration in Living Cells. Mol Cell Proteomics 2018; 17:2518-2533. [PMID: 30228193 DOI: 10.1074/mcp.tir118.000914] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 09/04/2018] [Indexed: 11/06/2022] Open
Abstract
Understanding cellular processes requires the determination of dynamic changes in the concentration of genetically nonmodified, endogenous proteins, which, to date, is commonly accomplished by end-point assays in vitro Molecular probes such as fluorescently labeled nanobodies (chromobodies, CBs) are powerful tools to visualize the dynamic subcellular localization of endogenous proteins in living cells. Here, we employed the dependence of intracellular levels of chromobodies on the amount of their endogenous antigens, a phenomenon, which we termed antigen-mediated CB stabilization (AMCBS), for simultaneous monitoring of time-resolved changes in the concentration and localization of native proteins. To improve the dynamic range of AMCBS we generated turnover-accelerated CBs and demonstrated their application in visualization and quantification of fast reversible changes in antigen concentration upon compound treatment by quantitative live-cell imaging. We expect that this broadly applicable strategy will enable unprecedented insights into the dynamic regulation of proteins, e.g. during cellular signaling, cell differentiation, or upon drug action.
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Affiliation(s)
| | - Julia Maier
- Pharmaceutical Biotechnology, Eberhard Karls University Tuebingen, Germany
| | - Kathy-Ann Secker
- Pharmaceutical Biotechnology, Eberhard Karls University Tuebingen, Germany
| | | | - Yana Parfyonova
- Pharmaceutical Biotechnology, Eberhard Karls University Tuebingen, Germany
| | - Ulrich Rothbauer
- Pharmaceutical Biotechnology, Eberhard Karls University Tuebingen, Germany; Natural and Medical Sciences Institute at the University of Tuebingen, Reutlingen, Germany.
| | - Bjoern Traenkle
- Pharmaceutical Biotechnology, Eberhard Karls University Tuebingen, Germany.
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16
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High-resolution structures of HIV-1 Gag cleavage mutants determine structural switch for virus maturation. Proc Natl Acad Sci U S A 2018; 115:E9401-E9410. [PMID: 30217893 PMCID: PMC6176557 DOI: 10.1073/pnas.1811237115] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The main structural component of HIV-1 is the Gag polyprotein. During virus release, Gag is cleaved by the viral protease at five sites, triggering a major change in the structure and morphology of the virus. This transition, called maturation, is required to make an infectious virion. We used cryoelectron tomography to obtain high-resolution structures of Gag inside virus particles carrying mutations that block specific combinations of cleavage sites. Analysis of these structures suggests that different combinations of cleavages can destabilize a bundle of alpha-helices at the C terminus of CA. This destabilization, rather than formation of a beta-hairpin at the N terminus of CA as previously suggested, acts as the structural switch for maturation of the virus into its infectious form. HIV-1 maturation occurs via multiple proteolytic cleavages of the Gag polyprotein, causing rearrangement of the virus particle required for infectivity. Cleavage results in beta-hairpin formation at the N terminus of the CA (capsid) protein and loss of a six-helix bundle formed by the C terminus of CA and the neighboring SP1 peptide. How individual cleavages contribute to changes in protein structure and interactions, and how the mature, conical capsid forms, are poorly understood. Here, we employed cryoelectron tomography to determine morphology and high-resolution CA lattice structures for HIV-1 derivatives in which Gag cleavage sites are mutated. These analyses prompt us to revise current models for the crucial maturation switch. Unlike previously proposed, cleavage on either terminus of CA was sufficient, in principle, for lattice maturation, while complete processing was needed for conical capsid formation. We conclude that destabilization of the six-helix bundle, rather than beta-hairpin formation, represents the main determinant of structural maturation.
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17
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Nieto-Garai JA, Glass B, Bunn C, Giese M, Jennings G, Brankatschk B, Agarwal S, Börner K, Contreras FX, Knölker HJ, Zankl C, Simons K, Schroeder C, Lorizate M, Kräusslich HG. Lipidomimetic Compounds Act as HIV-1 Entry Inhibitors by Altering Viral Membrane Structure. Front Immunol 2018; 9:1983. [PMID: 30233582 PMCID: PMC6131562 DOI: 10.3389/fimmu.2018.01983] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/13/2018] [Indexed: 12/16/2022] Open
Abstract
The envelope of Human Immunodeficiency Virus type 1 (HIV-1) consists of a liquid-ordered membrane enriched in raft lipids and containing the viral glycoproteins. Previous studies demonstrated that changes in viral membrane lipid composition affecting membrane structure or curvature can impair infectivity. Here, we describe novel antiviral compounds that were identified by screening compound libraries based on raft lipid-like scaffolds. Three distinct molecular structures were chosen for mode-of-action studies, a sterol derivative (J391B), a sphingosine derivative (J582C) and a long aliphatic chain derivative (IBS70). All three target the viral membrane and inhibit virus infectivity at the stage of fusion without perturbing virus stability or affecting virion-associated envelope glycoproteins. Their effect did not depend on the expressed envelope glycoproteins or a specific entry route, being equally strong in HIV pseudotypes carrying VSV-G or MLV-Env glycoproteins. Labeling with laurdan, a reporter of membrane order, revealed different membrane structure alterations upon compound treatment of HIV-1, which correlated with loss of infectivity. J582C and IBS70 decreased membrane order in distinctive ways, whereas J391B increased membrane order. The compounds' effects on membrane order were reproduced in liposomes generated from extracted HIV lipids and thus independent both of virion proteins and of membrane leaflet asymmetry. Remarkably, increase of membrane order by J391B required phosphatidylserine, a lipid enriched in the HIV envelope. Counterintuitively, mixtures of two compounds with opposite effects on membrane order, J582C and J391B, did not neutralize each other but synergistically inhibited HIV infection. Thus, altering membrane order, which can occur by different mechanisms, constitutes a novel antiviral mode of action that may be of general relevance for enveloped viruses and difficult to overcome by resistance development.
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Affiliation(s)
- Jon Ander Nieto-Garai
- Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Bilbao, Spain
| | - Bärbel Glass
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | | | | | | | - Beate Brankatschk
- JADO Technologies, Dresden, Germany.,Membrane Biochemistry Group, Paul-Langerhans-Institute Dresden, Helmholtz Zentrum München at the University Hospital and Faculty of Medicine Carl Gustav Carus, Dresden, Germany
| | - Sameer Agarwal
- JADO Technologies, Dresden, Germany.,Department of Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Kathleen Börner
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - F Xabier Contreras
- Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Bilbao, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Spain
| | - Hans-Joachim Knölker
- JADO Technologies, Dresden, Germany.,Department of Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Claudia Zankl
- JADO Technologies, Dresden, Germany.,Department of Chemistry, Technische Universität Dresden, Dresden, Germany
| | - Kai Simons
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Cornelia Schroeder
- JADO Technologies, Dresden, Germany.,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany.,Department of Anatomy, Medical Faculty Carl-Gustav-Carus, Technische Universität Dresden, Dresden, Germany
| | - Maier Lorizate
- Departamento de Bioquímica y Biología Molecular, Instituto Biofisika (CSIC, UPV/EHU), Universidad del País Vasco, Bilbao, Spain
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany
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18
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Peerboom N, Schmidt E, Trybala E, Block S, Bergström T, Pace HP, Bally M. Cell Membrane Derived Platform To Study Virus Binding Kinetics and Diffusion with Single Particle Sensitivity. ACS Infect Dis 2018; 4:944-953. [PMID: 29688001 DOI: 10.1021/acsinfecdis.7b00270] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Discovery and development of new antiviral therapies essentially rely on two key factors: an in-depth understanding of the mechanisms involved in viral infection and the development of fast and versatile drug screening platforms. To meet those demands, we present a biosensing platform to probe virus-cell membrane interactions on a single particle level. Our method is based on the formation of supported lipid bilayers from cell membrane material. Using total internal reflection fluorescence microscopy, we report the contribution of viral and cellular components to the interaction kinetics of herpes simplex virus type 1 with the cell membrane. Deletion of glycoprotein C (gC), the main viral attachment glycoprotein, or deletion of heparan sulfate, an attachment factor on the cell membrane, leads to an overall decrease in association of virions to the membrane and faster dissociation from the membrane. In addition to this, we perform binding inhibition studies using the antiviral compound heparin to estimate its IC50 value. Finally, single particle tracking is used to characterize the diffusive behavior of the virus particles on the supported lipid bilayers. Altogether, our results promote this platform as a complement to existing bioanalytical assays, being at the interface between simplified artificial membrane models and live cell experiments.
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Affiliation(s)
- Nadia Peerboom
- Department of Physics, Chalmers University of Technology, Fysikgränd 3, 412 96 Göteborg, Sweden
| | - Eneas Schmidt
- Department of Physics, Chalmers University of Technology, Fysikgränd 3, 412 96 Göteborg, Sweden
| | - Edward Trybala
- Department of Infectious Diseases, Section for Clinical Virology, Institute of Biomedicine, University of Gothenburg, Guldhedsgatan 10B, 413 46 Göteborg, Sweden
| | - Stephan Block
- Department of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 141 95 Berlin, Germany
| | - Tomas Bergström
- Department of Infectious Diseases, Section for Clinical Virology, Institute of Biomedicine, University of Gothenburg, Guldhedsgatan 10B, 413 46 Göteborg, Sweden
| | - Hudson P. Pace
- Department of Physics, Chalmers University of Technology, Fysikgränd 3, 412 96 Göteborg, Sweden
| | - Marta Bally
- Department of Physics, Chalmers University of Technology, Fysikgränd 3, 412 96 Göteborg, Sweden
- Wallenberg Centre for Molecular Medicine and Department of Clinical Microbiology, Umeå University, NUS Målpunkt R, 901 85 Umeå, Sweden
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19
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Eberle JP, Muranyi W, Erfle H, Gunkel M. Fully Automated Targeted Confocal and Single-Molecule Localization Microscopy. Methods Mol Biol 2018; 1663:139-152. [PMID: 28924665 DOI: 10.1007/978-1-4939-7265-4_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
Single-molecule localization microscopy (SMLM) enables imaging of biological structures in the nanometre range. Long measurement times are the consequence of this kind of microscopy due to the need of acquiring thousands of images. We built a setup that automatically detects target structures using confocal microscopy and images them with SMLM. Utilizing the Konstanz Information Miner (KNIME), we were able to connect a confocal microscope with an SMLM unit for targeted screening. In this process, we developed KNIME plugins to communicate with the microscope components and combined them to a workflow. Thus, measuring biological nanometre-sized structures in a sufficient number to get statistical significance becomes feasible. For proof of principle HIV-1 assembly complexes in HeLa cells derived from transfection of replication deficient viral construct were imaged by a fully automated screen.
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Affiliation(s)
- Jan Philipp Eberle
- High-Content Analysis of the Cell (HiCell) and Advanced Biological Screening Facility, BioQuant, Heidelberg University, Heidelberg, Germany
| | - Walter Muranyi
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Holger Erfle
- High-Content Analysis of the Cell (HiCell) and Advanced Biological Screening Facility, BioQuant, Heidelberg University, Heidelberg, Germany.
| | - Manuel Gunkel
- High-Content Analysis of the Cell (HiCell) and Advanced Biological Screening Facility, BioQuant, Heidelberg University, Heidelberg, Germany
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20
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Witte R, Andriasyan V, Georgi F, Yakimovich A, Greber UF. Concepts in Light Microscopy of Viruses. Viruses 2018; 10:E202. [PMID: 29670029 PMCID: PMC5923496 DOI: 10.3390/v10040202] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 04/12/2018] [Accepted: 04/16/2018] [Indexed: 12/11/2022] Open
Abstract
Viruses threaten humans, livestock, and plants, and are difficult to combat. Imaging of viruses by light microscopy is key to uncover the nature of known and emerging viruses in the quest for finding new ways to treat viral disease and deepening the understanding of virus–host interactions. Here, we provide an overview of recent technology for imaging cells and viruses by light microscopy, in particular fluorescence microscopy in static and live-cell modes. The review lays out guidelines for how novel fluorescent chemical probes and proteins can be used in light microscopy to illuminate cells, and how they can be used to study virus infections. We discuss advantages and opportunities of confocal and multi-photon microscopy, selective plane illumination microscopy, and super-resolution microscopy. We emphasize the prevalent concepts in image processing and data analyses, and provide an outlook into label-free digital holographic microscopy for virus research.
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Affiliation(s)
- Robert Witte
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Vardan Andriasyan
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Fanny Georgi
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| | - Artur Yakimovich
- MRC Laboratory for Molecular Cell Biology, University College London, Gower St., London WC1E 6BT, UK.
| | - Urs F Greber
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
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21
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IL-2 Inducible Kinase ITK is Critical for HIV-1 Infection of Jurkat T-cells. Sci Rep 2018; 8:3217. [PMID: 29453458 PMCID: PMC5816632 DOI: 10.1038/s41598-018-21344-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 01/15/2018] [Indexed: 01/04/2023] Open
Abstract
Successful replication of Human immunodeficiency virus (HIV)-1 depends on the expression of various cellular host factors, such as the interleukin-2 inducible T-cell kinase (ITK), a member of the protein family of TEC-tyrosine kinases. ITK is selectively expressed in T-cells and coordinates signaling pathways downstream of the T-cell receptor and chemokine receptors, including PLC-1 activation, Ca2+-release, transcription factor mobilization, and actin rearrangements. The exact role of ITK during HIV-1 infection is still unknown. We analyzed the function of ITK during HIV-1 replication and showed that attachment, fusion of virions with the cell membrane and entry into Jurkat T-cells was inhibited when ITK was knocked down. In contrast, reverse transcription and provirus expression were not affected by ITK deficiency. Inhibited ITK expression did not affect the CXCR4 receptor on the cell surface, whereas CD4 and LFA-1 integrin levels were slightly enhanced in ITK knockdown cells and heparan sulfate (HS) expression was completely abolished in ITK depleted T-cells. However, neither HS expression nor other attachment factors could explain the impaired HIV-1 binding to ITK-deficient cells, which suggests that a more complex cellular process is influenced by ITK or that not yet discovered molecules contribute to restriction of HIV-1 binding and entry.
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22
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Kushida Y, Arai Y, Shimono K, Nagai T. Biomimetic Chemical Sensing by Fluorescence Signals Using a Virus-like Particle-Based Platform. ACS Sens 2018; 3:87-92. [PMID: 29256249 DOI: 10.1021/acssensors.7b00537] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The chemical receptors present in living organisms are promising tools for developing biomimetic chemical sensors. However, these receptors require lipid membranes for functioning under physiological conditions, which prevents their utilization in the production of cell-free in vitro chemical sensing systems. Here, we report the development of a cell-free biomimetic sensing platform using virus-like particles (VLPs) with intact ligand-gated Ca2+ channels and genetically encoded Ca2+ indicator (GECI). We observed that targeting GECI to the plasma membrane was essential for efficient loading GECI in the VLPs. Although the physiological Ca2+ concentration [Ca2+] maintained in the cells was low (∼10 nM), the concentration in the VLPs was high. This prevented the detection of the increase in [Ca2+] caused by binding of the ligand to the receptor. To address this problem, we employed Lyn-R-CEPIA1, which had low affinity for Ca2+, and a membrane targeting sequence. Thus, we succeeded in monitoring the activation of cyclic nucleotide-gated channels (CNG) on the VLPs by measuring the increase in fluorescence of Lyn-R-CEPIA1. Our VLP-based sensing system can act as a fundamental platform for all kinds of ligand-gated channels.
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Affiliation(s)
- Yuki Kushida
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita 565-0871, Japan
- Advanced
Research Division, Panasonic Corporation, 3-4 Hikaridai,
Seika, Soraku, Kyoto 619-0237, Japan
| | - Yoshiyuki Arai
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita 565-0871, Japan
- Department
of Biomolecular Science and Engineering, The Institute of Scientific
and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan
| | - Ken Shimono
- Advanced
Research Division, Panasonic Corporation, 3-4 Hikaridai,
Seika, Soraku, Kyoto 619-0237, Japan
| | - Takeharu Nagai
- Department
of Biotechnology, Graduate School of Engineering, Osaka University, 2-1
Yamadaoka, Suita 565-0871, Japan
- Department
of Biomolecular Science and Engineering, The Institute of Scientific
and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki 567-0047, Japan
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23
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Chojnacki J, Waithe D, Carravilla P, Huarte N, Galiani S, Enderlein J, Eggeling C. Envelope glycoprotein mobility on HIV-1 particles depends on the virus maturation state. Nat Commun 2017; 8:545. [PMID: 28916807 PMCID: PMC5601426 DOI: 10.1038/s41467-017-00515-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 06/30/2017] [Indexed: 12/02/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) assembles as immature particles, which require the proteolytic cleavage of structural polyprotein Gag and the clustering of envelope glycoprotein Env for infectivity. The details of mechanisms underlying Env clustering remain unknown. Here, we determine molecular dynamics of Env on the surface of individual HIV-1 particles using scanning fluorescence correlation spectroscopy on a super-resolution STED microscope. We find that Env undergoes a maturation-induced increase in mobility, highlighting diffusion as one cause for Env clustering. This mobility increase is dependent on Gag-interacting Env tail but not on changes in viral envelope lipid order. Diffusion of Env and other envelope incorporated proteins in mature HIV-1 is two orders of magnitude slower than in the plasma membrane, indicating that HIV-1 envelope is intrinsically a low mobility environment, mainly due to its general high lipid order. Our results provide insights into dynamic properties of proteins on the surface of individual virus particles.To become infectious, HIV-1 particles undergo a maturation process involving the clustering of envelope glycoprotein Env. Here, Chojnacki et al. employ super-resolution STED-FCS microscopy to study dynamics of Env molecules on HIV-1 particles and show that Env undergoes a maturation-induced increase in mobility.
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Affiliation(s)
- Jakub Chojnacki
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, Oxford, UK.
| | - Dominic Waithe
- Wolfson Imaging Centre, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, Oxford, UK
| | - Pablo Carravilla
- Biofisika Institute (UPV/EHU, CSIC) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain
| | - Nerea Huarte
- Biofisika Institute (UPV/EHU, CSIC) and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), P.O. Box 644, 48080, Bilbao, Spain
| | - Silvia Galiani
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, Oxford, UK
| | - Jörg Enderlein
- Third Institute of Physics, Georg August University, 37077, Göttingen, Germany
| | - Christian Eggeling
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, OX3 9DS, Oxford, UK.
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24
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Mücksch F, Laketa V, Müller B, Schultz C, Kräusslich HG. Synchronized HIV assembly by tunable PIP 2 changes reveals PIP 2 requirement for stable Gag anchoring. eLife 2017; 6. [PMID: 28574338 PMCID: PMC5495570 DOI: 10.7554/elife.25287] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 05/25/2017] [Indexed: 12/15/2022] Open
Abstract
HIV-1 assembles at the plasma membrane (PM) of infected cells. PM association of the main structural protein Gag depends on its myristoylated MA domain and PM PI(4,5)P2. Using a novel chemical biology tool that allows rapidly tunable manipulation of PI(4,5)P2 levels in living cells, we show that depletion of PI(4,5)P2 completely prevents Gag PM targeting and assembly site formation. Unexpectedly, PI(4,5)P2 depletion also caused loss of pre-assembled Gag lattices from the PM. Subsequent restoration of PM PI(4,5)P2 reinduced assembly site formation even in the absence of new protein synthesis, indicating that the dissociated Gag molecules remained assembly competent. These results reveal an important role of PI(4,5)P2 for HIV-1 morphogenesis beyond Gag recruitment to the PM and suggest a dynamic equilibrium of Gag-lipid interactions. Furthermore, they establish an experimental system that permits synchronized induction of HIV-1 assembly leading to induced production of infectious virions by targeted modulation of Gag PM targeting.
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Affiliation(s)
- Frauke Mücksch
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Vibor Laketa
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany.,German Center for Infectious Disease Research, Partner site Heidelberg, Braunschweig, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Carsten Schultz
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Heidelberg, Germany.,Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, United States
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany.,German Center for Infectious Disease Research, Partner site Heidelberg, Braunschweig, Germany
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25
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Liu X, Ouyang T, Ouyang H, Ren L. Single particle labeling of RNA virus in live cells. Virus Res 2017; 237:14-21. [PMID: 28506790 DOI: 10.1016/j.virusres.2017.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2017] [Revised: 05/10/2017] [Accepted: 05/10/2017] [Indexed: 12/17/2022]
Abstract
Real-time and visual tracking of viral infection is crucial for elucidating the infectious and pathogenesis mechanisms. To track the virus successfully, an efficient labeling method is necessary. In this review, we first discuss the practical labeling techniques for virus tracking in live cells. We then describe the current knowledge of interactions between RNA viruses (especially influenza viruses, immunodeficiency viruses, and Flaviviruses) and host cellular structures, obtained using single particle labeling techniques combined with real-time fluorescence microscopy. Single particle labeling provides an easy system for understanding the RNA virus life cycle.
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Affiliation(s)
- Xiaohui Liu
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, Changchun, Jilin 130062, China
| | - Ting Ouyang
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, Changchun, Jilin 130062, China
| | - Hongsheng Ouyang
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, Changchun, Jilin 130062, China
| | - Linzhu Ren
- Jilin Provincial Key Laboratory of Animal Embryo Engineering, College of Animal Sciences, Jilin University, Changchun, Jilin 130062, China.
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26
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Sakin V, Hanne J, Dunder J, Anders-Össwein M, Laketa V, Nikić I, Kräusslich HG, Lemke EA, Müller B. A Versatile Tool for Live-Cell Imaging and Super-Resolution Nanoscopy Studies of HIV-1 Env Distribution and Mobility. Cell Chem Biol 2017; 24:635-645.e5. [PMID: 28457706 DOI: 10.1016/j.chembiol.2017.04.007] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 02/12/2017] [Accepted: 04/06/2017] [Indexed: 12/27/2022]
Abstract
The envelope glycoproteins (Env) of HIV-1 mediate cell entry through fusion of the viral envelope with a target cell membrane. Intramembrane mobility and clustering of Env trimers at the viral budding site are essential for its function. Previous live-cell and super-resolution microscopy studies were limited by lack of a functional fluorescent Env derivative, requiring antibody labeling for detection. Introduction of a bio-orthogonal amino acid by genetic code expansion, combined with click chemistry, offers novel possibilities for site-specific, minimally invasive labeling. Using this approach, we established efficient incorporation of non-canonical amino acids within HIV-1 Env in mammalian cells. The engineered protein retained plasma membrane localization, glycosylation, virion incorporation, and fusogenic activity, and could be rapidly and specifically labeled with synthetic dyes. This strategy allowed us to revisit Env dynamics and nanoscale distribution at the plasma membrane close to its native state, applying fluorescence recovery after photo bleaching and STED nanoscopy, respectively.
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Affiliation(s)
- Volkan Sakin
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Janina Hanne
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany; Optical Nanoscopy Division, German Cancer Research Center, 69120 Heidelberg, Germany
| | - Jessica Dunder
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Maria Anders-Össwein
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Vibor Laketa
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany; German Center for Infection Research, Partner Site Heidelberg, 69120 Heidelberg, Germany
| | - Ivana Nikić
- Structural and Computational Biology Unit, Cell Biology and Biophysics Unit, EMBL, 69117 Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany; German Center for Infection Research, Partner Site Heidelberg, 69120 Heidelberg, Germany
| | - Edward A Lemke
- Structural and Computational Biology Unit, Cell Biology and Biophysics Unit, EMBL, 69117 Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany.
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27
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Li Q, Li W, Yin W, Guo J, Zhang ZP, Zeng D, Zhang X, Wu Y, Zhang XE, Cui Z. Single-Particle Tracking of Human Immunodeficiency Virus Type 1 Productive Entry into Human Primary Macrophages. ACS NANO 2017; 11:3890-3903. [PMID: 28371581 DOI: 10.1021/acsnano.7b00275] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Macrophages are one of the major targets of human immunodeficiency virus (HIV-1), but the viral entry pathway remains poorly understood in these cells. Noninvasive virus labeling and single-virus tracking are effective tools for studying virus entry. Here, we constructed a quantum dot (QD)-encapsulated infectious HIV-1 particle to track viral entry at a single-particle level in live human primary macrophages. QDs were encapsulated in HIV-1 virions by incorporating viral accessory protein Vpr-conjugated QDs during virus assembly. With the HIV-1 particles encapsulating QDs, we monitored the early phase of viral infection in real time and observed that, during infection, HIV-1 was endocytosed in a clathrin-mediated manner; the particles were translocated into Rab5A-positive endosomes, and the core was released into the cytoplasm by viral envelope-mediated endosomal fusion. Drug inhibition assays verified that endosome fusion contributes to HIV-1 productive infection in primary macrophages. Additionally, we observed that a dynamic actin cytoskeleton is critical for HIV-1 entry and intracellular migration in primary macrophages. HIV-1 dynamics and infection could be blocked by multiple different actin inhibitors. Our study revealed a productive entry pathway in macrophages that requires both endosomal function and actin dynamics, which may assist in the development of inhibitors to block the HIV entry in macrophages.
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Affiliation(s)
- Qin Li
- College of Life Science and Technology, Huazhong University of Science and Technology , Wuhan 430074, P.R. China
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, P.R. China
| | - Wei Li
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, P.R. China
| | - Wen Yin
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, P.R. China
| | - Jia Guo
- National Center for Biodefense and Infectious Diseases, Department of Molecular and Microbiology, George Mason University , Manassas, Virginia 20110, United States
| | - Zhi-Ping Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, P.R. China
| | - Dejun Zeng
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, P.R. China
| | - Xiaowei Zhang
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, P.R. China
| | - Yuntao Wu
- National Center for Biodefense and Infectious Diseases, Department of Molecular and Microbiology, George Mason University , Manassas, Virginia 20110, United States
| | - Xian-En Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences , Beijing 100101, P.R. China
| | - Zongqiang Cui
- State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan 430071, P.R. China
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28
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Huang YF, Zhuo GY, Chou CY, Lin CH, Chang W, Hsieh CL. Coherent Brightfield Microscopy Provides the Spatiotemporal Resolution To Study Early Stage Viral Infection in Live Cells. ACS NANO 2017; 11:2575-2585. [PMID: 28067508 DOI: 10.1021/acsnano.6b05601] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Affiliation(s)
- Yi-Fan Huang
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Guan-Yu Zhuo
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Chun-Yu Chou
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Cheng-Hao Lin
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
| | - Wen Chang
- Institute
of Molecular Biology, Academia Sinica, Taipei 11529, Taiwan
| | - Chia-Lung Hsieh
- Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
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29
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Heun Y, Hildebrand S, Heidsieck A, Gleich B, Anton M, Pircher J, Ribeiro A, Mykhaylyk O, Eberbeck D, Wenzel D, Pfeifer A, Woernle M, Krötz F, Pohl U, Mannell H. Targeting of Magnetic Nanoparticle-coated Microbubbles to the Vascular Wall Empowers Site-specific Lentiviral Gene Delivery in vivo. Theranostics 2017; 7:295-307. [PMID: 28042335 PMCID: PMC5197065 DOI: 10.7150/thno.16192] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 09/13/2016] [Indexed: 12/13/2022] Open
Abstract
In the field of vascular gene therapy, targeting systems are promising advancements to improve site-specificity of gene delivery. Here, we studied whether incorporation of magnetic nanoparticles (MNP) with different magnetic properties into ultrasound sensitive microbubbles may represent an efficient way to enable gene targeting in the vascular system after systemic application. Thus, we associated novel silicon oxide-coated magnetic nanoparticle containing microbubbles (SO-Mag MMB) with lentiviral particles carrying therapeutic genes and determined their physico-chemical as well as biological properties compared to MMB coated with polyethylenimine-coated magnetic nanoparticles (PEI-Mag MMB). While there were no differences between both MMB types concerning size and lentivirus binding, SO-Mag MMB exhibited superior characteristics regarding magnetic moment, magnetizability as well as transduction efficiency under static and flow conditions in vitro. Focal disruption of lentiviral SO-Mag MMB by ultrasound within isolated vessels exposed to an external magnetic field decisively improved localized VEGF expression in aortic endothelium ex vivo and enhanced the angiogenic response. Using the same system in vivo, we achieved a highly effective, site-specific lentiviral transgene expression in microvessels of the mouse dorsal skin after arterial injection. Thus, we established a novel lentiviral MMB technique, which has great potential towards site-directed vascular gene therapy.
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30
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Hanne J, Göttfert F, Schimer J, Anders-Össwein M, Konvalinka J, Engelhardt J, Müller B, Hell SW, Kräusslich HG. Stimulated Emission Depletion Nanoscopy Reveals Time-Course of Human Immunodeficiency Virus Proteolytic Maturation. ACS NANO 2016; 10:8215-8222. [PMID: 27517329 DOI: 10.1021/acsnano.6b03850] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Concomitant with human immunodeficiency virus type 1 (HIV-1) budding from a host cell, cleavage of the structural Gag polyproteins by the viral protease (PR) triggers complete remodeling of virion architecture. This maturation process is essential for virus infectivity. Electron tomography provided structures of immature and mature HIV-1 with a diameter of 120-140 nm, but information about the sequence and dynamics of structural rearrangements is lacking. Here, we employed super-resolution STED (stimulated emission depletion) fluorescence nanoscopy of HIV-1 carrying labeled Gag to visualize the virion architecture. The incomplete Gag lattice of immature virions was clearly distinguishable from the condensed distribution of mature protein subunits. Synchronized activation of PR within purified particles by photocleavage of a caged PR inhibitor enabled time-resolved in situ observation of the induction of proteolysis and maturation by super-resolution microscopy. This study shows the rearrangement of subviral structures in a super-resolution light microscope over time, outwitting phototoxicity and fluorophore bleaching through synchronization of a biological process by an optical switch.
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Affiliation(s)
- Janina Hanne
- Department of Infectious Diseases, Virology, Heidelberg University , Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
- Optical Nanoscopy Division, German Cancer Research Center (DKFZ) , Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Fabian Göttfert
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry , Am Fassberg 11, 37077 Göttingen, Germany
| | - Jiří Schimer
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center , Flemingovo n.2, 166 10 Prague 6, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University in Prague , Hlavova 8, 12843 Prague 2, Czech Republic
| | - Maria Anders-Össwein
- Department of Infectious Diseases, Virology, Heidelberg University , Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Jan Konvalinka
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center , Flemingovo n.2, 166 10 Prague 6, Czech Republic
- Department of Biochemistry, Faculty of Science, Charles University in Prague , Hlavova 8, 12843 Prague 2, Czech Republic
| | - Johann Engelhardt
- Optical Nanoscopy Division, German Cancer Research Center (DKFZ) , Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, Heidelberg University , Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
- Molecular Medicine Partnership Unit , Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Stefan W Hell
- Optical Nanoscopy Division, German Cancer Research Center (DKFZ) , Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry , Am Fassberg 11, 37077 Göttingen, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Heidelberg University , Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
- Molecular Medicine Partnership Unit , Meyerhofstrasse 1, 69117 Heidelberg, Germany
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31
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Vosen S, Rieck S, Heidsieck A, Mykhaylyk O, Zimmermann K, Plank C, Gleich B, Pfeifer A, Fleischmann BK, Wenzel D. Improvement of vascular function by magnetic nanoparticle-assisted circumferential gene transfer into the native endothelium. J Control Release 2016; 241:164-173. [PMID: 27667178 DOI: 10.1016/j.jconrel.2016.09.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 12/22/2022]
Abstract
Gene therapy is a promising approach for chronic disorders that require continuous treatment such as cardiovascular disease. Overexpression of vasoprotective genes has generated encouraging results in animal models, but not in clinical trials. One major problem in humans is the delivery of sufficient amounts of genetic vectors to the endothelium which is impeded by blood flow, whereas prolonged stop-flow conditions impose the risk of ischemia. In the current study we have therefore developed a strategy for the efficient circumferential lentiviral gene transfer in the native endothelium under constant flow conditions. For that purpose we perfused vessels that were exposed to specially designed magnetic fields with complexes of lentivirus and magnetic nanoparticles thereby enabling overexpression of therapeutic genes such as endothelial nitric oxide synthase (eNOS) and vascular endothelial growth factor (VEGF). This treatment enhanced NO and VEGF production in the transduced endothelium and resulted in a reduction of vascular tone and increased angiogenesis. Thus, the combination of MNPs with magnetic fields is an innovative strategy for site-specific and efficient vascular gene therapy.
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Affiliation(s)
- Sarah Vosen
- Institute of Physiology I, Life & Brain Center, University Clinic of Bonn, Germany
| | - Sarah Rieck
- Institute of Physiology I, Life & Brain Center, University Clinic of Bonn, Germany
| | | | - Olga Mykhaylyk
- Institute of Experimental Oncology and Therapy Research, TU München, Germany
| | - Katrin Zimmermann
- Institute of Pharmacology and Toxicology, University Clinic of Bonn, Germany
| | - Christian Plank
- Institute of Experimental Oncology and Therapy Research, TU München, Germany
| | - Bernhard Gleich
- Zentralinstitut für Medizintechnik (IMETUM), TU München, Germany
| | - Alexander Pfeifer
- Institute of Pharmacology and Toxicology, University Clinic of Bonn, Germany
| | - Bernd K Fleischmann
- Institute of Physiology I, Life & Brain Center, University Clinic of Bonn, Germany
| | - Daniela Wenzel
- Institute of Physiology I, Life & Brain Center, University Clinic of Bonn, Germany.
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32
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HIV-1 Vpu Antagonizes CD317/Tetherin by Adaptor Protein-1-Mediated Exclusion from Virus Assembly Sites. J Virol 2016; 90:6709-6723. [PMID: 27170757 DOI: 10.1128/jvi.00504-16] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/06/2016] [Indexed: 01/22/2023] Open
Abstract
UNLABELLED The host cell restriction factor CD317/tetherin traps virions at the surface of producer cells to prevent their release. The HIV-1 accessory protein Vpu antagonizes this restriction. Vpu reduces the cell surface density of the restriction factor and targets it for degradation; however, these activities are dispensable for enhancing particle release. Instead, Vpu has been suggested to antagonize CD317/tetherin by preventing recycling of internalized CD317/tetherin to the cell surface, blocking anterograde transport of newly synthesized CD317/tetherin, and/or displacing the restriction factor from virus assembly sites at the plasma membrane. At the molecular level, antagonism relies on the physical interaction of Vpu with CD317/tetherin. Recent findings suggested that phosphorylation of a diserine motif enables Vpu to bind to adaptor protein 1 (AP-1) trafficking complexes via two independent interaction motifs and to couple CD317/tetherin to the endocytic machinery. Here, we used a panel of Vpu proteins with specific mutations in individual interaction motifs to define which interactions are required for antagonism of CD317/tetherin. Impairing recycling or anterograde transport of CD317/tetherin to the plasma membrane was insufficient for antagonism. In contrast, excluding CD317/tetherin from HIV-1 assembly sites depended on Vpu motifs for interaction with AP-1 and CD317/tetherin and correlated with antagonism of the particle release restriction. Consistently, interference with AP-1 function or its expression blocked these Vpu activities. Our results define displacement from HIV-1 assembly sites as active principle of CD317/tetherin antagonism by Vpu and support a role of tripartite complexes between Vpu, AP-1, and CD317/tetherin in this process. IMPORTANCE CD317/tetherin poses an intrinsic barrier to human immunodeficiency virus type 1 (HIV-1) replication in human cells by trapping virus particles at the surface of producer cells and thereby preventing their release. The viral protein Vpu antagonizes this restriction, and molecular interactions with the restriction factor and adaptor protein complex 1 (AP-1) were suggested to mediate this activity. Vpu modulates intracellular trafficking of CD317/tetherin and excludes the restriction factor from HIV-1 assembly sites at the plasma membrane, but the relative contribution of these effects to antagonism remain elusive. Using a panel of Vpu mutants, as well as interference with AP-1 function and expression, we show here that Vpu antagonizes CD317/tetherin by blocking its recruitment to viral assembly sites in an AP-1-dependent manner. These results refine our understanding of the molecular mechanisms of CD317/tetherin antagonism and suggest complexes of Vpu with the restriction factor and AP-1 as targets for potential therapeutic intervention.
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Schorb M, Gaechter L, Avinoam O, Sieckmann F, Clarke M, Bebeacua C, Bykov YS, Sonnen AFP, Lihl R, Briggs JAG. New hardware and workflows for semi-automated correlative cryo-fluorescence and cryo-electron microscopy/tomography. J Struct Biol 2016; 197:83-93. [PMID: 27368127 PMCID: PMC5287355 DOI: 10.1016/j.jsb.2016.06.020] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 06/17/2016] [Accepted: 06/27/2016] [Indexed: 12/17/2022]
Abstract
Correlative light and electron microscopy allows features of interest defined by fluorescence signals to be located in an electron micrograph of the same sample. Rare dynamic events or specific objects can be identified, targeted and imaged by electron microscopy or tomography. To combine it with structural studies using cryo-electron microscopy or tomography, fluorescence microscopy must be performed while maintaining the specimen vitrified at liquid-nitrogen temperatures and in a dry environment during imaging and transfer. Here we present instrumentation, software and an experimental workflow that improves the ease of use, throughput and performance of correlated cryo-fluorescence and cryo-electron microscopy. The new cryo-stage incorporates a specially modified high-numerical aperture objective lens and provides a stable and clean imaging environment. It is combined with a transfer shuttle for contamination-free loading of the specimen. Optimized microscope control software allows automated acquisition of the entire specimen area by cryo-fluorescence microscopy. The software also facilitates direct transfer of the fluorescence image and associated coordinates to the cryo-electron microscope for subsequent fluorescence-guided automated imaging. Here we describe these technological developments and present a detailed workflow, which we applied for automated cryo-electron microscopy and tomography of various specimens.
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Affiliation(s)
- Martin Schorb
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Electron Microscopy Core Facility, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Leander Gaechter
- Leica Microsystems (Schweiz) AG, Max Schmidheiny-Strasse 201, 9435 Heerbrugg, Switzerland
| | - Ori Avinoam
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Frank Sieckmann
- Leica Microsystems GmbH, Am Friedensplatz 3, 68165 Mannheim, Germany
| | - Mairi Clarke
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Cecilia Bebeacua
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Yury S Bykov
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Andreas F-P Sonnen
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Molecular Medicine Partnership Unit, EMBL/Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Reinhard Lihl
- Leica Mikrosysteme GmbH, Hernalser Hauptstraße 219, 1170 Vienna, Austria
| | - John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Molecular Medicine Partnership Unit, EMBL/Universitätsklinikum Heidelberg, Heidelberg, Germany.
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Oum YH, Desai TM, Marin M, Melikyan GB. Click labeling of unnatural sugars metabolically incorporated into viral envelope glycoproteins enables visualization of single particle fusion. J Virol Methods 2016; 233:62-71. [PMID: 27033181 DOI: 10.1016/j.jviromet.2016.02.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Accepted: 02/11/2016] [Indexed: 10/22/2022]
Abstract
Enveloped viruses infect target cells by fusing their membrane with cellular membrane through a process that is mediated by specialized viral glycoproteins. The inefficient and highly asynchronous nature of viral fusion complicates studies of virus entry on a population level. Single virus imaging in living cells has become an important tool for delineating the entry pathways and for mechanistic studies of viral fusion. We have previously demonstrated that incorporation of fluorescent labels into the viral membrane and trapping fluorescent proteins in the virus interior enables the visualization of single virus fusion in living cells. Here, we implement a new approach to non-invasively label the viral membrane glycoproteins through metabolic incorporation of unnatural sugars followed by click-reaction with organic fluorescent dyes. This approach allows for efficient labeling of diverse viral fusion glycoproteins on the surface of HIV pseudoviruses. Incorporation of a content marker into surface-labeled viral particles enables sensitive detection of single virus fusion with live cells.
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Affiliation(s)
- Yoon Hyeun Oum
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, USA
| | - Tanay M Desai
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, USA
| | - Mariana Marin
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, USA
| | - Gregory B Melikyan
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, USA; Children's Healthcare of Atlanta, Atlanta, GA, USA.
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Breaking the diffraction limit of light-sheet fluorescence microscopy by RESOLFT. Proc Natl Acad Sci U S A 2016; 113:3442-6. [PMID: 26984498 DOI: 10.1073/pnas.1522292113] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present a plane-scanning RESOLFT [reversible saturable/switchable optical (fluorescence) transitions] light-sheet (LS) nanoscope, which fundamentally overcomes the diffraction barrier in the axial direction via confinement of the fluorescent molecular state to a sheet of subdiffraction thickness around the focal plane. To this end, reversibly switchable fluorophores located right above and below the focal plane are transferred to a nonfluorescent state at each scanning step. LS-RESOLFT nanoscopy offers wide-field 3D imaging of living biological specimens with low light dose and axial resolution far beyond the diffraction barrier. We demonstrate optical sections that are thinner by 5-12-fold compared with their conventional diffraction-limited LS analogs.
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Desai TM, Marin M, Sood C, Shi J, Nawaz F, Aiken C, Melikyan GB. Fluorescent protein-tagged Vpr dissociates from HIV-1 core after viral fusion and rapidly enters the cell nucleus. Retrovirology 2015; 12:88. [PMID: 26511606 PMCID: PMC4625717 DOI: 10.1186/s12977-015-0215-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 10/16/2015] [Indexed: 02/06/2023] Open
Abstract
Background HIV-1 Vpr is recruited into virions during assembly and appears to remain associated with the viral core after the reverse transcription and uncoating steps of entry. This feature has prompted the use of fluorescently labeled Vpr to visualize viral particles and to follow trafficking of post-fusion HIV-1 cores in the cytoplasm. Results Here, we tracked single pseudovirus entry and fusion and observed that fluorescently tagged Vpr gradually dissociates from post-fusion viral cores over the course of several minutes and accumulates in the nucleus. Kinetics measurements showed that fluorescent Vpr released from the cores very rapidly entered the cell nucleus. More than 10,000 Vpr molecules can be delivered into the cell nucleus within 45 min of infection by HIV-1 particles pseudotyped with the avian sarcoma and leukosis virus envelope glycoprotein. The fraction of Vpr from cell-bound viruses that accumulated in the nucleus was proportional to the extent of virus-cell fusion and was fully blocked by viral fusion inhibitors. Entry of virus-derived Vpr into the nucleus occurred independently of envelope glycoproteins or target cells. Fluorescence correlation spectroscopy revealed two forms of nuclear Vpr—monomers and very large complexes, likely involving host factors. The kinetics of viral Vpr entering the nucleus after fusion was not affected by point mutations in the capsid protein that alter the stability of the viral core. Conclusions The independence of Vpr shedding of capsid stability and its relatively rapid dissociation from post-fusion cores suggest that this process may precede capsid uncoating, which appears to occur on a slower time scale. Our results thus demonstrate that a bulk of fluorescently labeled Vpr incorporated into HIV-1 particles is released shortly after fusion. Future studies will address the question whether the quick and efficient nuclear delivery of Vpr derived from incoming viruses can regulate subsequent steps of HIV-1 infection. Electronic supplementary material The online version of this article (doi:10.1186/s12977-015-0215-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tanay M Desai
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA.
| | - Mariana Marin
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA.
| | - Chetan Sood
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA.
| | - Jiong Shi
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, 37232, USA.
| | - Fatima Nawaz
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, 37232, USA.
| | - Christopher Aiken
- Department of Pathology, Microbiology and Immunology, Vanderbilt University, Nashville, TN, 37232, USA.
| | - Gregory B Melikyan
- Division of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, GA, USA. .,Children's Healthcare of Atlanta, Atlanta, GA, USA.
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RNA and Nucleocapsid Are Dispensable for Mature HIV-1 Capsid Assembly. J Virol 2015; 89:9739-47. [PMID: 26178992 DOI: 10.1128/jvi.00750-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2015] [Accepted: 07/09/2015] [Indexed: 12/23/2022] Open
Abstract
UNLABELLED Human immunodeficiency virus type 1 (HIV-1) is released from infected cells in an immature, noninfectious form in which the structural polyprotein Gag is arranged in a hexameric lattice, forming an incomplete spherical shell. Maturation to the infectious form is mediated by the viral protease, which cleaves Gag at five sites, releasing the CA (capsid) protein, which forms a conical capsid encasing the condensed RNA genome. The pathway of this structural rearrangement is currently not understood, and it is unclear how cone assembly is initiated. RNA represents an integral structural component of retroviruses, and the viral nucleoprotein core has previously been proposed to nucleate mature capsid assembly. We addressed this hypothesis by replacing the RNA-binding NC (nucleocapsid) domain of HIV-1 Gag and the adjacent spacer peptide 2 (SP2) by a leucine zipper (LZ) protein-protein interaction domain [Gag(LZ)] in the viral context. We found that Gag(LZ)-carrying virus [HIV(LZ)] was efficiently released and viral polyproteins were proteolytically processed, though with reduced efficiency. Cryo-electron tomography revealed that the particles lacked a condensed nucleoprotein and contained an increased proportion of aberrant core morphologies caused either by the absence of RNA or by altered Gag processing. Nevertheless, a significant proportion of HIV(LZ) particles contained mature capsids with the wild-type morphology. These results clearly demonstrate that the nucleoprotein complex is dispensable as a nucleator for mature HIV-1 capsid assembly in the viral context. IMPORTANCE Formation of a closed conical capsid encasing the viral RNA genome is essential for HIV-1 infectivity. It is currently unclear what viral components initiate and regulate the formation of the capsid during virus morphogenesis, but it has been proposed that the ribonucleoprotein complex plays a role. To test this, we prepared virus-like particles lacking the viral nucleocapsid protein and RNA and analyzed their three-dimensional structure by cryo-electron tomography. While most virions displayed an abnormal morphology under these conditions, some particles showed a normal mature morphology with closed conical capsids. These data demonstrate that the presence of RNA and the nucleocapsid protein is not required for the formation of a mature, cone-shaped HIV-1 capsid.
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Pino M, Erkizia I, Benet S, Erikson E, Fernández-Figueras MT, Guerrero D, Dalmau J, Ouchi D, Rausell A, Ciuffi A, Keppler OT, Telenti A, Kräusslich HG, Martinez-Picado J, Izquierdo-Useros N. HIV-1 immune activation induces Siglec-1 expression and enhances viral trans-infection in blood and tissue myeloid cells. Retrovirology 2015; 12:37. [PMID: 25947229 PMCID: PMC4423124 DOI: 10.1186/s12977-015-0160-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 03/24/2015] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Myeloid cells are key players in the recognition and response of the host against invading viruses. Paradoxically, upon HIV-1 infection, myeloid cells might also promote viral pathogenesis through trans-infection, a mechanism that promotes HIV-1 transmission to target cells via viral capture and storage. The receptor Siglec-1 (CD169) potently enhances HIV-1 trans-infection and is regulated by immune activating signals present throughout the course of HIV-1 infection, such as interferon α (IFNα). RESULTS Here we show that IFNα-activated dendritic cells, monocytes and macrophages have an enhanced ability to capture and trans-infect HIV-1 via Siglec-1 recognition of viral membrane gangliosides. Monocytes from untreated HIV-1-infected individuals trans-infect HIV-1 via Siglec-1, but this capacity diminishes after effective antiretroviral treatment. Furthermore, Siglec-1 is expressed on myeloid cells residing in lymphoid tissues, where it can mediate viral trans-infection. CONCLUSIONS Siglec-1 on myeloid cells could fuel novel CD4(+) T-cell infections and contribute to HIV-1 dissemination in vivo.
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Affiliation(s)
- Maria Pino
- AIDS Research Institute IrsiCaixa, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol IGTP, Universitat Autònoma de Barcelona, Badalona, Spain.
| | - Itziar Erkizia
- AIDS Research Institute IrsiCaixa, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol IGTP, Universitat Autònoma de Barcelona, Badalona, Spain.
| | - Susana Benet
- AIDS Research Institute IrsiCaixa, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol IGTP, Universitat Autònoma de Barcelona, Badalona, Spain.
| | - Elina Erikson
- Institute of Medical Virology, National Reference Center for Retroviruses, University of Frankfurt, Frankfurt, Germany. .,Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany.
| | | | | | - Judith Dalmau
- AIDS Research Institute IrsiCaixa, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol IGTP, Universitat Autònoma de Barcelona, Badalona, Spain.
| | - Dan Ouchi
- AIDS Research Institute IrsiCaixa, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol IGTP, Universitat Autònoma de Barcelona, Badalona, Spain.
| | - Antonio Rausell
- Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland. .,Swiss Institute of Bioinformatics (SIB) - Vital-IT, Lausanne, Switzerland.
| | - Angela Ciuffi
- Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland.
| | - Oliver T Keppler
- Institute of Medical Virology, National Reference Center for Retroviruses, University of Frankfurt, Frankfurt, Germany.
| | - Amalio Telenti
- Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland. .,Current address: The J. Craig Venter Institute, La Jolla, CA, USA.
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, Universitätsklinikum Heidelberg, Heidelberg, Germany.
| | - Javier Martinez-Picado
- AIDS Research Institute IrsiCaixa, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol IGTP, Universitat Autònoma de Barcelona, Badalona, Spain. .,Institució Catalana de Recerca i Estudis Avançats ICREA, Barcelona, Spain. .,University of Vic-Central University of Catalonia (UVic-UCC), Vic, Spain.
| | - Nuria Izquierdo-Useros
- AIDS Research Institute IrsiCaixa, Institut d'Investigació en Ciències de la Salut Germans Trias i Pujol IGTP, Universitat Autònoma de Barcelona, Badalona, Spain.
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Schimer J, Pávová M, Anders M, Pachl P, Šácha P, Cígler P, Weber J, Majer P, Řezáčová P, Kräusslich HG, Müller B, Konvalinka J. Triggering HIV polyprotein processing by light using rapid photodegradation of a tight-binding protease inhibitor. Nat Commun 2015; 6:6461. [PMID: 25751579 PMCID: PMC4366505 DOI: 10.1038/ncomms7461] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/29/2015] [Indexed: 12/23/2022] Open
Abstract
HIV protease (PR) is required for proteolytic maturation in the late phase of HIV replication and represents a prime therapeutic target. The regulation and kinetics of viral polyprotein processing and maturation are currently not understood in detail. Here we design, synthesize, validate and apply a potent, photodegradable HIV PR inhibitor to achieve synchronized induction of proteolysis. The compound exhibits subnanomolar inhibition in vitro. Its photolabile moiety is released on light irradiation, reducing the inhibitory potential by 4 orders of magnitude. We determine the structure of the PR-inhibitor complex, analyze its photolytic products, and show that the enzymatic activity of inhibited PR can be fully restored on inhibitor photolysis. We also demonstrate that proteolysis of immature HIV particles produced in the presence of the inhibitor can be rapidly triggered by light enabling thus to analyze the timing, regulation and spatial requirements of viral processing in real time. The study of HIV proteolysis during maturation and replication can be difficult since different steps in these processes occur simultaneously. Here, the authors present a photolabile HIV protease inhibitor which can be deactivated by light irradiation, allowing synchronized induction of viral maturation.
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Affiliation(s)
- Jiří Schimer
- 1] Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic [2] Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43, Prague 2, Czech Republic
| | - Marcela Pávová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic
| | - Maria Anders
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany
| | - Petr Pachl
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic
| | - Pavel Šácha
- 1] Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic [2] Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43, Prague 2, Czech Republic
| | - Petr Cígler
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic
| | - Jan Weber
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic
| | - Pavel Majer
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic
| | - Pavlína Řezáčová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic
| | - Hans-Georg Kräusslich
- 1] Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany [2] Molecular Medicine Partnership Unit, Heidelberg, Germany
| | - Barbara Müller
- 1] Department of Infectious Diseases, Virology, University Hospital Heidelberg, Im Neuenheimer Feld 324, 69120 Heidelberg, Germany [2] Molecular Medicine Partnership Unit, Heidelberg, Germany
| | - Jan Konvalinka
- 1] Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Gilead Sciences and IOCB Research Center, Flemingovo n.2, 166 10, Prague 6, Czech Republic [2] Department of Biochemistry, Faculty of Science, Charles University in Prague, Hlavova 8, 128 43, Prague 2, Czech Republic
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Super-resolution imaging of ESCRT-proteins at HIV-1 assembly sites. PLoS Pathog 2015; 11:e1004677. [PMID: 25710462 PMCID: PMC4339578 DOI: 10.1371/journal.ppat.1004677] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 01/12/2015] [Indexed: 11/19/2022] Open
Abstract
The cellular endosomal sorting complex required for transport (ESCRT) machinery is involved in membrane budding processes, such as multivesicular biogenesis and cytokinesis. In HIV-infected cells, HIV-1 hijacks the ESCRT machinery to drive HIV release. Early in the HIV-1 assembly process, the ESCRT-I protein Tsg101 and the ESCRT-related protein ALIX are recruited to the assembly site. Further downstream, components such as the ESCRT-III proteins CHMP4 and CHMP2 form transient membrane associated lattices, which are involved in virus-host membrane fission. Although various geometries of ESCRT-III assemblies could be observed, the actual membrane constriction and fission mechanism is not fully understood. Fission might be driven from inside the HIV-1 budding neck by narrowing the membranes from the outside by larger lattices surrounding the neck, or from within the bud. Here, we use super-resolution fluorescence microscopy to elucidate the size and structure of the ESCRT components Tsg101, ALIX, CHMP4B and CHMP2A during HIV-1 budding below the diffraction limit. To avoid the deleterious effects of using fusion proteins attached to ESCRT components, we performed measurements on the endogenous protein or, in the case of CHMP4B, constructs modified with the small HA tag. Due to the transient nature of the ESCRT interactions, the fraction of HIV-1 assembly sites with colocalizing ESCRT complexes was low (1.5%-3.4%). All colocalizing ESCRT clusters exhibited closed, circular structures with an average size (full-width at half-maximum) between 45 and 60 nm or a diameter (determined using a Ripley's L-function analysis) of roughly 60 to 100 nm. The size distributions for colocalizing clusters were narrower than for non-colocalizing clusters, and significantly smaller than the HIV-1 bud. Hence, our results support a membrane scission process driven by ESCRT protein assemblies inside a confined structure, such as the bud neck, rather than by large lattices around the neck or in the bud lumen. In the case of ALIX, a cloud of individual molecules surrounding the central clusters was often observed, which we attribute to ALIX molecules incorporated into the nascent HIV-1 Gag shell. Experiments performed using YFP-tagged Tsg101 led to an over 10-fold increase in ESCRT structures colocalizing with HIV-1 budding sites indicating an influence of the fusion protein tag on the function of the ESCRT protein.
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Godinez WJ, Rohr K. Tracking multiple particles in fluorescence time-lapse microscopy images via probabilistic data association. IEEE TRANSACTIONS ON MEDICAL IMAGING 2015; 34:415-432. [PMID: 25252280 DOI: 10.1109/tmi.2014.2359541] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Tracking subcellular structures as well as viral structures displayed as 'particles' in fluorescence microscopy images yields quantitative information on the underlying dynamical processes. We have developed an approach for tracking multiple fluorescent particles based on probabilistic data association. The approach combines a localization scheme that uses a bottom-up strategy based on the spot-enhancing filter as well as a top-down strategy based on an ellipsoidal sampling scheme that uses the Gaussian probability distributions computed by a Kalman filter. The localization scheme yields multiple measurements that are incorporated into the Kalman filter via a combined innovation, where the association probabilities are interpreted as weights calculated using an image likelihood. To track objects in close proximity, we compute the support of each image position relative to the neighboring objects of a tracked object and use this support to recalculate the weights. To cope with multiple motion models, we integrated the interacting multiple model algorithm. The approach has been successfully applied to synthetic 2-D and 3-D images as well as to real 2-D and 3-D microscopy images, and the performance has been quantified. In addition, the approach was successfully applied to the 2-D and 3-D image data of the recent Particle Tracking Challenge at the IEEE International Symposium on Biomedical Imaging (ISBI) 2012.
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Role of the nucleocapsid domain in HIV-1 Gag oligomerization and trafficking to the plasma membrane: a fluorescence lifetime imaging microscopy investigation. J Mol Biol 2015; 427:1480-1494. [PMID: 25644662 DOI: 10.1016/j.jmb.2015.01.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Revised: 01/26/2015] [Accepted: 01/27/2015] [Indexed: 11/20/2022]
Abstract
The Pr55 Gag of human immunodeficiency virus type 1 orchestrates viral particle assembly in producer cells, which requires the genomic RNA and a lipid membrane as scaffolding platforms. The nucleocapsid (NC) domain with its two invariant CCHC zinc fingers flanked by unfolded basic sequences is thought to direct genomic RNA selection, dimerization and packaging during virus assembly. To further investigate the role of NC domain, we analyzed the assembly of Gag with deletions in the NC domain in parallel with that of wild-type Gag using fluorescence lifetime imaging microscopy combined with Förster resonance energy transfer in HeLa cells. We found that, upon binding to nucleic acids, the NC domain promotes the formation of compact Gag oligomers in the cytoplasm. Moreover, the intracellular distribution of the population of oligomers further suggests that oligomers progressively assemble during their trafficking toward the plasma membrane (PM), but with no dramatic changes in their compact arrangement. This ultimately results in the accumulation at the PM of closely packed Gag oligomers that likely arrange in hexameric lattices, as revealed by the perfect match between the experimental Förster resonance energy transfer value and the one calculated from the structural model of Gag in immature viruses. The distal finger and flanking basic sequences, but not the proximal finger, appear to be essential for Gag oligomer compaction and membrane binding. Moreover, the full NC domain was found to be instrumental in the kinetics of Gag oligomerization and intracellular trafficking. These findings further highlight the key roles played by the NC domain in virus assembly.
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Peng K, Muranyi W, Glass B, Laketa V, Yant SR, Tsai L, Cihlar T, Müller B, Kräusslich HG. Quantitative microscopy of functional HIV post-entry complexes reveals association of replication with the viral capsid. eLife 2014; 3:e04114. [PMID: 25517934 PMCID: PMC4293571 DOI: 10.7554/elife.04114] [Citation(s) in RCA: 130] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 12/15/2014] [Indexed: 12/17/2022] Open
Abstract
The steps from HIV-1 cytoplasmic entry until integration of the reverse transcribed genome are currently enigmatic. They occur in ill-defined reverse-transcription- and pre-integration-complexes (RTC, PIC) with various host and viral proteins implicated. In this study, we report quantitative detection of functional RTC/PIC by labeling nascent DNA combined with detection of viral integrase. We show that the viral CA (capsid) protein remains associated with cytoplasmic RTC/PIC but is lost on nuclear PIC in a HeLa-derived cell line. In contrast, nuclear PIC were almost always CA-positive in primary human macrophages, indicating nuclear import of capsids or capsid-like structures. We further show that the CA-targeted inhibitor PF74 exhibits a bimodal mechanism, blocking RTC/PIC association with the host factor CPSF6 and nuclear entry at low, and abrogating reverse transcription at high concentrations. The newly developed system is ideally suited for studying retroviral post-entry events and the roles of host factors including DNA sensors and signaling molecules.
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Affiliation(s)
- Ke Peng
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | - Walter Muranyi
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | - Bärbel Glass
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | - Vibor Laketa
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | | | - Luong Tsai
- Gilead Sciences Inc., Foster City, United States
| | - Tomas Cihlar
- Gilead Sciences Inc., Foster City, United States
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University of Heidelberg, Heidelberg, Germany
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HIV-1 entry in SupT1-R5, CEM-ss, and primary CD4+ T cells occurs at the plasma membrane and does not require endocytosis. J Virol 2014; 88:13956-70. [PMID: 25253335 DOI: 10.1128/jvi.01543-14] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
UNLABELLED Cytoplasmic entry of HIV-1 requires binding of the viral glycoproteins to the cellular receptor and coreceptor, leading to fusion of viral and cellular membranes. Early studies suggested that productive HIV-1 infection occurs by direct fusion at the plasma membrane. Endocytotic uptake of HIV-1 was frequently observed but was considered to constitute an unspecific dead-end pathway. More recent evidence suggested that endocytosis contributes to productive HIV-1 entry and may even represent the predominant or exclusive route of infection. We have analyzed HIV-1 binding, endocytosis, cytoplasmic entry, and infection in T-cell lines and in primary CD4(+) T cells. Efficient cell binding and endocytosis required viral glycoproteins and CD4, but not the coreceptor. The contribution of endocytosis to cytoplasmic entry and infection was assessed by two strategies: (i) expression of dominant negative dynamin-2 was measured and was found to efficiently block HIV-1 endocytosis but to not affect fusion or productive infection. (ii) Making use of the fact that HIV-1 fusion is blocked at temperatures below 23 °C, cells were incubated with HIV-1 at 22 °C for various times, and endocytosis was quantified by parallel analysis of transferrin and fluorescent HIV-1 uptake. Subsequently, entry at the plasma membrane was blocked by high concentrations of the peptidic fusion inhibitor T-20, which does not reach previously endocytosed particles. HIV-1 infection was scored after cells were shifted to 37 °C in the presence of T-20. These experiments revealed that productive HIV-1 entry occurs predominantly at the plasma membrane in SupT1-R5, CEM-ss, and primary CD4(+) T cells, with little, if any, contribution coming from endocytosed virions. IMPORTANCE HIV-1, like all enveloped viruses, reaches the cytoplasm by fusion of the viral and cellular membranes. Many viruses enter the cytoplasm by endosomal uptake and fusion from the endosome, while cell entry can also occur by direct fusion at the plasma membrane in some cases. Conflicting evidence regarding the site of HIV-1 fusion has been reported, with some studies claiming that fusion occurs predominantly at the plasma membrane, while others have suggested predominant or even exclusive fusion from the endosome. We have revisited HIV-1 entry using a T-cell line that exhibits HIV-1 endocytosis dependent on the viral glycoproteins and the cellular CD4 receptor; results with this cell line were confirmed for another T-cell line and primary CD4(+) T cells. Our studies show that fusion and productive entry occur predominantly at the plasma membrane, and we conclude that endocytosis is dispensable for HIV-1 infectivity in these T-cell lines and in primary CD4(+) T cells.
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Abstract
UNLABELLED HIV-1 assembles at the plasma membrane of virus-producing cells as an immature, noninfectious particle. Processing of the Gag and Gag-Pol polyproteins by the viral protease (PR) activates the viral enzymes and results in dramatic structural rearrangements within the virion--termed maturation--that are a prerequisite for infectivity. Despite its fundamental importance for viral replication, little is currently known about the regulation of proteolysis and about the dynamics and structural intermediates of maturation. This is due mainly to the fact that HIV-1 release and maturation occur asynchronously both at the level of individual cells and at the level of particle release from a single cell. Here, we report a method to synchronize HIV-1 proteolysis in vitro based on protease inhibitor (PI) washout from purified immature virions, thereby temporally uncoupling virus assembly and maturation. Drug washout resulted in the induction of proteolysis with cleavage efficiencies correlating with the off-rate of the respective PR-PI complex. Proteolysis of Gag was nearly complete and yielded the correct products with an optimal half-life (t(1/2)) of ~5 h, but viral infectivity was not recovered. Failure to gain infectivity following PI washout may be explained by the observed formation of aberrant viral capsids and/or by pronounced defects in processing of the reverse transcriptase (RT) heterodimer associated with a lack of RT activity. Based on our results, we hypothesize that both the polyprotein processing dynamics and the tight temporal coupling of immature particle assembly and PR activation are essential for correct polyprotein processing and morphological maturation and thus for HIV-1 infectivity. IMPORTANCE Cleavage of the Gag and Gag-Pol HIV-1 polyproteins into their functional subunits by the viral protease activates the viral enzymes and causes major structural rearrangements essential for HIV-1 infectivity. This proteolytic maturation occurs concomitant with virus release, and investigation of its dynamics is hampered by the fact that virus populations in tissue culture contain particles at all stages of assembly and maturation. Here, we developed an inhibitor washout strategy to synchronize activation of protease in wild-type virus. We demonstrated that nearly complete Gag processing and resolution of the immature virus architecture are accomplished under optimized conditions. Nevertheless, most of the resulting particles displayed irregular morphologies, Gag-Pol processing was not faithfully reconstituted, and infectivity was not recovered. These data show that HIV-1 maturation is sensitive to the dynamics of processing and also that a tight temporal link between virus assembly and PR activation is required for correct polyprotein processing.
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Stauffer S, Rahman SA, de Marco A, Carlson LA, Glass B, Oberwinkler H, Herold N, Briggs JAG, Müller B, Grünewald K, Kräusslich HG. The nucleocapsid domain of Gag is dispensable for actin incorporation into HIV-1 and for association of viral budding sites with cortical F-actin. J Virol 2014; 88:7893-903. [PMID: 24789788 PMCID: PMC4097806 DOI: 10.1128/jvi.00428-14] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Accepted: 04/24/2014] [Indexed: 12/24/2022] Open
Abstract
Actin and actin-binding proteins are incorporated into HIV-1 particles, and F-actin has been suggested to bind the NC domain in HIV-1 Gag. Furthermore, F-actin has been frequently observed in the vicinity of HIV-1 budding sites by cryo-electron tomography (cET). Filamentous structures emanating from viral buds and suggested to correspond to actin filaments have been observed by atomic force microscopy. To determine whether the NC domain of Gag is required for actin association with viral buds and for actin incorporation into HIV-1, we performed comparative analyses of virus-like particles (VLPs) obtained by expression of wild-type HIV-1 Gag or a Gag variant where the entire NC domain had been replaced by a dimerizing leucine zipper [Gag(LZ)]. The latter protein yielded efficient production of VLPs with near-wild-type assembly kinetics and size and exhibited a regular immature Gag lattice. Typical HIV-1 budding sites were detected by using cET in cells expressing either Gag or Gag(LZ), and no difference was observed regarding the association of buds with the F-actin network. Furthermore, actin was equally incorporated into wild-type HIV-1 and Gag- or Gag(LZ)-derived VLPs, with less actin per particle observed than had been reported previously. Incorporation appeared to correlate with the relative intracellular actin concentration, suggesting an uptake of cytosol rather than a specific recruitment of actin. Thus, the NC domain in HIV-1 Gag does not appear to have a role in actin recruitment or actin incorporation into HIV-1 particles. Importance: HIV-1 particles bud from the plasma membrane, which is lined by a network of actin filaments. Actin was found to interact with the nucleocapsid domain of the viral structural protein Gag and is incorporated in significant amounts into HIV-1 particles, suggesting that it may play an active role in virus release. Using electron microscopy techniques, we previously observed bundles of actin filaments near HIV-1 buds, often seemingly in contact with the Gag layer. Here, we show that this spatial association is observed independently of the proposed actin-binding domain of HIV-1. The absence of this domain also did not affect actin incorporation and had a minor effect on the viral assembly rate. Furthermore, actin was not enriched in the virus compared to the average levels in the respective producing cell. Our data argue against a specific recruitment of actin to HIV-1 budding sites by the nucleocapsid domain of Gag.
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Affiliation(s)
- Sarah Stauffer
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Sheikh Abdul Rahman
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Alex de Marco
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
| | - Lars-Anders Carlson
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Bärbel Glass
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Heike Oberwinkler
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Nikolas Herold
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
| | - Barbara Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Kay Grünewald
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Hans-Georg Kräusslich
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany Molecular Medicine Partnership Unit, Heidelberg, Germany
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Padilla-Parra S, Marin M, Kondo N, Melikyan GB. Pinpointing retrovirus entry sites in cells expressing alternatively spliced receptor isoforms by single virus imaging. Retrovirology 2014; 11:47. [PMID: 24935247 PMCID: PMC4065388 DOI: 10.1186/1742-4690-11-47] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2014] [Accepted: 06/07/2014] [Indexed: 12/29/2022] Open
Abstract
Background The majority of viruses enter host cells via endocytosis. Current knowledge of viral entry pathways is largely based upon infectivity measurements following genetic and/or pharmacological interventions that disrupt vesicular trafficking and maturation. Imaging of single virus entry in living cells provides a powerful means to delineate viral trafficking pathways and entry sites under physiological conditions. Results Here, we visualized single avian retrovirus co-trafficking with markers for early (Rab5) and late (Rab7) endosomes, acidification of endosomal lumen and the resulting viral fusion measured by the viral content release into the cytoplasm. Virus-carrying vesicles either merged with the existing Rab5-positive early endosomes or slowly accumulated Rab5. The Rab5 recruitment to virus-carrying endosomes correlated with acidification of their lumen. Viral fusion occurred either in early (Rab5-positive) or intermediate (Rab5- and Rab7-positive) compartments. Interestingly, different isoforms of the cognate receptor directed virus entry from distinct endosomes. In cells expressing the transmembrane receptor, viruses preferentially entered and fused with slowly maturing early endosomes prior to accumulation of Rab7. By comparison, in cells expressing the GPI-anchored receptor, viruses entered both slowly and quickly maturing endosomes and fused with early (Rab5-positive) and intermediate (Rab5- and Rab7-positive) compartments. Conclusions Since the rate of low pH-triggered fusion was independent of the receptor isoform, we concluded that the sites of virus entry are determined by the kinetic competition between endosome maturation and viral fusion. Our findings demonstrate the ability of this retrovirus to enter cells via alternative endocytic pathways and establish infection by releasing its content from distinct endosomal compartments.
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Affiliation(s)
| | | | | | - Gregory B Melikyan
- Division of Pediatric Infectious Diseases, Emory University Children's Center, Atlanta, GA 30322, USA.
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Müller B, Anders M, Reinstein J. In vitro analysis of human immunodeficiency virus particle dissociation: gag proteolytic processing influences dissociation kinetics. PLoS One 2014; 9:e99504. [PMID: 24915417 PMCID: PMC4051761 DOI: 10.1371/journal.pone.0099504] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 05/15/2014] [Indexed: 11/18/2022] Open
Abstract
Human immunodeficiency virus particles undergo a step of proteolytic maturation, in which the main structural polyprotein Gag is cleaved into its mature subunits matrix (MA), capsid (CA), nucleocapsid (NC) and p6. Gag proteolytic processing is accompanied by a dramatic structural rearrangement within the virion, which is necessary for virus infectivity and has been proposed to proceed through a sequence of dissociation and reformation of the capsid lattice. Morphological maturation appears to be tightly regulated, with sequential cleavage events and two small spacer peptides within Gag playing important roles by regulating the disassembly of the immature capsid layer and formation of the mature capsid lattice. In order to measure the influence of individual Gag domains on lattice stability, we established Förster's resonance energy transfer (FRET) reporter virions and employed rapid kinetic FRET and light scatter measurements. This approach allowed us to measure dissociation properties of HIV-1 particles assembled in eukaryotic cells containing Gag proteins in different states of proteolytic processing. While the complex dissociation behavior of the particles prevented an assignment of kinetic rate constants to individual dissociation steps, our analyses revealed characteristic differences in the dissociation properties of the MA layer dependent on the presence of additional domains. The most striking effect observed here was a pronounced stabilization of the MA-CA layer mediated by the presence of the 14 amino acid long spacer peptide SP1 at the CA C-terminus, underlining the crucial role of this peptide for the resolution of the immature particle architecture.
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Affiliation(s)
- Barbara Müller
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
- * E-mail:
| | - Maria Anders
- Department of Infectious Diseases, Virology, University Hospital Heidelberg, Heidelberg, Germany
| | - Jochen Reinstein
- Department of Biomolecular Mechanisms, Max Planck Institute for Medical Research, Heidelberg, Germany
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Investigating the role of F-actin in human immunodeficiency virus assembly by live-cell microscopy. J Virol 2014; 88:7904-14. [PMID: 24789789 DOI: 10.1128/jvi.00431-14] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Human immunodeficiency virus type 1 (HIV-1) particles assemble at the plasma membrane, which is lined by a dense network of filamentous actin (F-actin). Large amounts of actin have been detected in HIV-1 virions, proposed to be incorporated by interactions with the nucleocapsid domain of the viral polyprotein Gag. Previous studies addressing the role of F-actin in HIV-1 particle formation using F-actin-interfering drugs did not yield consistent results. Filamentous structures pointing toward nascent HIV-1 budding sites, detected by cryo-electron tomography and atomic force microscopy, prompted us to revisit the role of F-actin in HIV-1 assembly by live-cell microscopy. HeLa cells coexpressing HIV-1 carrying fluorescently labeled Gag and a labeled F-actin-binding peptide were imaged by live-cell total internal reflection fluorescence microscopy (TIR-FM). Computational analysis of image series did not reveal characteristic patterns of F-actin in the vicinity of viral budding sites. Furthermore, no transient recruitment of F-actin during bud formation was detected by monitoring fluorescence intensity changes at nascent HIV-1 assembly sites. The chosen approach allowed us to measure the effect of F-actin-interfering drugs on the assembly of individual virions in parallel with monitoring changes in the F-actin network of the respective cell. Treatment of cells with latrunculin did not affect the efficiency and dynamics of Gag assembly under conditions resulting in the disruption of F-actin filaments. Normal assembly rates were also observed upon transient stabilization of F-actin by short-term treatment with jasplakinolide. Taken together, these findings indicate that actin filament dynamics are dispensable for HIV-1 Gag assembly at the plasma membrane of HeLa cells. Importance: HIV-1 particles assemble at the plasma membrane of virus-producing cells. This membrane is lined by a dense network of actin filaments that might either present a physical obstacle to the formation of virus particles or generate force promoting the assembly process. Drug-mediated interference with the actin cytoskeleton showed different results for the formation of retroviral particles in different studies, likely due to general effects on the cell upon prolonged drug treatment. Here, we characterized the effect of actin-interfering compounds on the HIV-1 assembly process by direct observation of virus formation in live cells, which allowed us to measure assembly rate constants directly upon drug addition. Virus assembly proceeded with normal rates when actin filaments were either disrupted or stabilized. Taken together with the absence of characteristic actin filament patterns at viral budding sites in our analyses, this indicates that the actin network is dispensable for HIV-1 assembly.
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50
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Borrenberghs D, Thys W, Rocha S, Demeulemeester J, Weydert C, Dedecker P, Hofkens J, Debyser Z, Hendrix J. HIV virions as nanoscopic test tubes for probing oligomerization of the integrase enzyme. ACS NANO 2014; 8:3531-45. [PMID: 24654558 PMCID: PMC4004294 DOI: 10.1021/nn406615v] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Employing viruses as nanoscopic lipid-enveloped test tubes allows the miniaturization of protein-protein interaction (PPI) assays while preserving the physiological environment necessary for particular biological processes. Applied to the study of the human immunodeficiency virus type 1 (HIV-1), viral biology and pathology can also be investigated in novel ways, both in vitro as well as in infected cells. In this work we report on an experimental strategy that makes use of engineered HIV-1 viral particles, to allow for probing PPIs of the HIV-1 integrase (IN) inside viruses with single-molecule Förster resonance energy transfer (FRET) using fluorescent proteins (FP). We show that infectious fluorescently labeled viruses can be obtained and that the quantity of labels can be accurately measured and controlled inside individual viral particles. We demonstrate, with proper control experiments, the formation of IN oligomers in single viral particles and inside viral complexes in infected cells. Finally, we show a clear effect on IN oligomerization of small molecule inhibitors of interactions of IN with its natural human cofactor LEDGF/p75, corroborating that IN oligomer enhancing drugs are active already at the level of the virus and strongly suggesting the presence of a dynamic, enhanceable equilibrium between the IN dimer and tetramer in viral particles. Although applied to the HIV-1 IN enzyme, our methodology for utilizing HIV virions as nanoscopic test tubes for probing PPIs is generic, i.e., other PPIs targeted into the HIV-1, or PPIs targeted into other viruses, can potentially be studied with a similar strategy.
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Affiliation(s)
- Doortje Borrenberghs
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
| | - Wannes Thys
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Kapucijnenvoer 33, 3000 Leuven, Flanders, Belgium
| | - Susana Rocha
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
| | - Jonas Demeulemeester
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Kapucijnenvoer 33, 3000 Leuven, Flanders, Belgium
| | - Caroline Weydert
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Kapucijnenvoer 33, 3000 Leuven, Flanders, Belgium
| | - Peter Dedecker
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
| | - Johan Hofkens
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
- Nano-Science Center, Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Zeger Debyser
- Laboratory for Molecular Virology and Gene Therapy, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Kapucijnenvoer 33, 3000 Leuven, Flanders, Belgium
| | - Jelle Hendrix
- Laboratory for Photochemistry and Spectroscopy, Department of Chemistry, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Flanders, Belgium
- Address correspondence to
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