1
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Dutta M, Acharya P. Cryo-electron microscopy in the study of virus entry and infection. Front Mol Biosci 2024; 11:1429180. [PMID: 39114367 PMCID: PMC11303226 DOI: 10.3389/fmolb.2024.1429180] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Accepted: 06/12/2024] [Indexed: 08/10/2024] Open
Abstract
Viruses have been responsible for many epidemics and pandemics that have impacted human life globally. The COVID-19 pandemic highlighted both our vulnerability to viral outbreaks, as well as the mobilization of the scientific community to come together to combat the unprecedented threat to humanity. Cryo-electron microscopy (cryo-EM) played a central role in our understanding of SARS-CoV-2 during the pandemic and continues to inform about this evolving pathogen. Cryo-EM with its two popular imaging modalities, single particle analysis (SPA) and cryo-electron tomography (cryo-ET), has contributed immensely to understanding the structure of viruses and interactions that define their life cycles and pathogenicity. Here, we review how cryo-EM has informed our understanding of three distinct viruses, of which two - HIV-1 and SARS-CoV-2 infect humans, and the third, bacteriophages, infect bacteria. For HIV-1 and SARS-CoV-2 our focus is on the surface glycoproteins that are responsible for mediating host receptor binding, and host and cell membrane fusion, while for bacteriophages, we review their structure, capsid maturation, attachment to the bacterial cell surface and infection initiation mechanism.
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Affiliation(s)
- Moumita Dutta
- Duke Human Vaccine Institute, Durham, NC, United States
| | - Priyamvada Acharya
- Duke Human Vaccine Institute, Durham, NC, United States
- Department of Surgery, Durham, NC, United States
- Department of Biochemistry, Duke University, Durham, NC, United States
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2
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Pražák V, Mironova Y, Vasishtan D, Hagen C, Laugks U, Jensen Y, Sanders S, Heumann JM, Bosse JB, Klupp BG, Mettenleiter TC, Grange M, Grünewald K. Molecular plasticity of herpesvirus nuclear egress analysed in situ. Nat Microbiol 2024; 9:1842-1855. [PMID: 38918469 PMCID: PMC7616147 DOI: 10.1038/s41564-024-01716-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Accepted: 04/29/2024] [Indexed: 06/27/2024]
Abstract
The viral nuclear egress complex (NEC) allows herpesvirus capsids to escape from the nucleus without compromising the nuclear envelope integrity. The NEC lattice assembles on the inner nuclear membrane and mediates the budding of nascent nucleocapsids into the perinuclear space and their subsequent release into the cytosol. Its essential role makes it a potent antiviral target, necessitating structural information in the context of a cellular infection. Here we determined structures of NEC-capsid interfaces in situ using electron cryo-tomography, showing a substantial structural heterogeneity. In addition, while the capsid is associated with budding initiation, it is not required for curvature formation. By determining the NEC structure in several conformations, we show that curvature arises from an asymmetric assembly of disordered and hexagonally ordered lattice domains independent of pUL25 or other viral capsid vertex components. Our results advance our understanding of the mechanism of nuclear egress in the context of a living cell.
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Affiliation(s)
- Vojtěch Pražák
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute of Virology, Hamburg, Germany
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Yuliia Mironova
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute of Virology, Hamburg, Germany
- Department of Chemistry, University of Hamburg, Hamburg, Germany
| | - Daven Vasishtan
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute of Virology, Hamburg, Germany
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Christoph Hagen
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute of Virology, Hamburg, Germany
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Ulrike Laugks
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute of Virology, Hamburg, Germany
- Department of Chemistry, University of Hamburg, Hamburg, Germany
| | - Yannick Jensen
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute of Virology, Hamburg, Germany
- Department of Chemistry, University of Hamburg, Hamburg, Germany
- Hannover Medical School, Institute of Virology, Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Saskia Sanders
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute of Virology, Hamburg, Germany
- Hannover Medical School, Institute of Virology, Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - John M Heumann
- Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Jens B Bosse
- Centre for Structural Systems Biology, Hamburg, Germany
- Leibniz Institute of Virology, Hamburg, Germany
- Hannover Medical School, Institute of Virology, Hannover, Germany
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany
| | - Barbara G Klupp
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Thomas C Mettenleiter
- Institute of Molecular Virology and Cell Biology, Friedrich-Loeffler-Institut, Greifswald-Insel Riems, Germany
| | - Michael Grange
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
- Structural Biology, Rosalind Franklin Institute, Didcot, UK.
| | - Kay Grünewald
- Centre for Structural Systems Biology, Hamburg, Germany.
- Leibniz Institute of Virology, Hamburg, Germany.
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
- Department of Chemistry, University of Hamburg, Hamburg, Germany.
- Cluster of Excellence RESIST (EXC 2155), Hannover Medical School, Hannover, Germany.
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3
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Wang H, Liao S, Yu X, Zhang J, Zhou ZH. TomoNet: A streamlined cryogenic electron tomography software pipeline with automatic particle picking on flexible lattices. BIOLOGICAL IMAGING 2024; 4:e7. [PMID: 38828212 PMCID: PMC11140495 DOI: 10.1017/s2633903x24000060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/04/2024] [Accepted: 03/25/2024] [Indexed: 06/05/2024]
Abstract
Cryogenic electron tomography (cryoET) is capable of determining in situ biological structures of molecular complexes at near-atomic resolution by averaging half a million subtomograms. While abundant complexes/particles are often clustered in arrays, precisely locating and seamlessly averaging such particles across many tomograms present major challenges. Here, we developed TomoNet, a software package with a modern graphical user interface to carry out the entire pipeline of cryoET and subtomogram averaging to achieve high resolution. TomoNet features built-in automatic particle picking and three-dimensional (3D) classification functions and integrates commonly used packages to streamline high-resolution subtomogram averaging for structures in 1D, 2D, or 3D arrays. Automatic particle picking is accomplished in two complementary ways: one based on template matching and the other using deep learning. TomoNet's hierarchical file organization and visual display facilitate efficient data management as required for large cryoET datasets. Applications of TomoNet to three types of datasets demonstrate its capability of efficient and accurate particle picking on flexible and imperfect lattices to obtain high-resolution 3D biological structures: virus-like particles, bacterial surface layers within cellular lamellae, and membranes decorated with nuclear egress protein complexes. These results demonstrate TomoNet's potential for broad applications to various cryoET projects targeting high-resolution in situ structures.
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Affiliation(s)
- Hui Wang
- Department of Bioengineering, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
- California NanoSystems Institute, UCLA, Los Angeles, CA, USA
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA
| | - Shiqing Liao
- California NanoSystems Institute, UCLA, Los Angeles, CA, USA
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA
| | - Xinye Yu
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA
| | - Jiayan Zhang
- California NanoSystems Institute, UCLA, Los Angeles, CA, USA
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA
| | - Z. Hong Zhou
- Department of Bioengineering, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
- California NanoSystems Institute, UCLA, Los Angeles, CA, USA
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA, Los Angeles, CA, USA
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4
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Tsurutani N, Momose F, Ogawa K, Sano K, Morikawa Y. Intracellular trafficking of HIV-1 Gag via Syntaxin 6-positive compartments/vesicles: Involvement in tumor necrosis factor secretion. J Biol Chem 2024; 300:105687. [PMID: 38280430 PMCID: PMC10891346 DOI: 10.1016/j.jbc.2024.105687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 01/03/2024] [Accepted: 01/04/2024] [Indexed: 01/29/2024] Open
Abstract
HIV-1 Gag protein is synthesized in the cytosol and is transported to the plasma membrane, where viral particle assembly and budding occur. Endosomes are alternative sites of Gag accumulation. However, the intracellular transport pathways and carriers for Gag have not been clarified. We show here that Syntaxin6 (Syx6), a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) involved in membrane fusion in post-Golgi networks, is a molecule responsible for Gag trafficking and also for tumor necrosis factor-α (TNFα) secretion and that Gag and TNFα are cotransported via Syx6-positive compartments/vesicles. Confocal and live-cell imaging revealed that Gag colocalized and cotrafficked with Syx6, a fraction of which localizes in early and recycling endosomes. Syx6 knockdown reduced HIV-1 particle production, with Gag distributed diffusely throughout the cytoplasm. Coimmunoprecipitation and pulldown show that Gag binds to Syx6, but not its SNARE partners or their assembly complexes, suggesting that Gag preferentially binds free Syx6. The Gag matrix domain and the Syx6 SNARE domain are responsible for the interaction and cotrafficking. In immune cells, Syx6 knockdown/knockout similarly impaired HIV-1 production. Interestingly, HIV-1 infection facilitated TNFα secretion, and this enhancement did not occur in Syx6-depleted cells. Confocal and live-cell imaging revealed that TNFα and Gag partially colocalized and were cotransported via Syx6-positive compartments/vesicles. Biochemical analyses indicate that TNFα directly binds the C-terminal domain of Syx6. Altogether, our data provide evidence that both Gag and TNFα make use of Syx6-mediated trafficking machinery and suggest that Gag expression does not inhibit but rather facilitates TNFα secretion in HIV-1 infection.
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Affiliation(s)
- Naomi Tsurutani
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Fumitaka Momose
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Keiji Ogawa
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
| | - Kouichi Sano
- Osaka Medical and Pharmaceutical University, Takatsuki, Osaka, Japan
| | - Yuko Morikawa
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan.
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5
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Sha H, Zhu F. Hexagonal Lattices of HIV Capsid Proteins Explored by Simulations Based on a Thermodynamically Consistent Model. J Phys Chem B 2024; 128:960-972. [PMID: 38251836 DOI: 10.1021/acs.jpcb.3c06881] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2024]
Abstract
HIV capsid proteins (CAs) may self-assemble into a variety of shapes under in vivo and in vitro conditions. Here, we employed simulations based on a residue-level coarse-grained (CG) model with full conformational flexibility to investigate hexagonal lattices, which are the underlying structural pattern for CA aggregations. Facilitated by enhanced sampling simulations to rigorously calculate CA dimerization and polymerization affinities, we calibrated our model to reproduce the experimentally measured affinities. Using the calibrated model, we performed unbiased simulations on several large systems consisting of 1512 CA subunits, allowing reversible binding and unbinding of the CAs in a thermodynamically consistent manner. In one simulation, a preassembled hexagonal CA sheet developed spontaneous curvatures reminiscent of those observed in experiments, and the edges of the sheet exhibited local curvatures larger than those of the interior. In other simulations starting with randomly distributed CAs at different concentrations, existing CA assemblies grew by binding free capsomeres to the edges and by merging with other assemblies. At high CA concentrations, rapid establishment of predominant aggregates was followed by much slower adjustments toward more regular hexagonal lattices, with increasing numbers of intact CA hexamers and pentamers being formed. Our approach of adapting a general CG model to specific systems by using experimental binding data represents a practical and effective strategy for simulating and elucidating intricate protein aggregations.
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Affiliation(s)
- Hao Sha
- Department of Physics, Indiana University─Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
| | - Fangqiang Zhu
- Department of Physics, Indiana University─Purdue University Indianapolis, Indianapolis, Indiana 46202, United States
- Biochemical and Biophysical Systems Group, Biosciences and Biotechnology Division, Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, California 94550, United States
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6
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Dwivedi R, Prakash P, Kumbhar BV, Balasubramaniam M, Dash C. HIV-1 capsid and viral DNA integration. mBio 2024; 15:e0021222. [PMID: 38085100 PMCID: PMC10790781 DOI: 10.1128/mbio.00212-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2024] Open
Abstract
IMPORTANCE HIV-1 capsid protein (CA)-independently or by recruiting host factors-mediates several key steps of virus replication in the cytoplasm and nucleus of the target cell. Research in the recent years have established that CA is multifunctional and genetically fragile of all the HIV-1 proteins. Accordingly, CA has emerged as a validated and high priority therapeutic target, and the first CA-targeting antiviral drug was recently approved for treating multi-drug resistant HIV-1 infection. However, development of next generation CA inhibitors depends on a better understanding of CA's known roles, as well as probing of CA's novel roles, in HIV-1 replication. In this timely review, we present an updated overview of the current state of our understanding of CA's multifunctional role in HIV-1 replication-with a special emphasis on CA's newfound post-nuclear roles, highlight the pressing knowledge gaps, and discuss directions for future research.
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Affiliation(s)
- Richa Dwivedi
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
| | - Prem Prakash
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee, USA
| | - Bajarang Vasant Kumbhar
- Department of Biological Sciences, Sunandan Divatia School of Science, NMIMS (Deemed to be) University, Mumbai, Maharashtra, India
| | - Muthukumar Balasubramaniam
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee, USA
| | - Chandravanu Dash
- The Center for AIDS Health Disparities Research, Meharry Medical College, Nashville, Tennessee, USA
- Department of Microbiology, Immunology, and Physiology, Meharry Medical College, Nashville, Tennessee, USA
- Department of Biochemistry, Cancer Biology, Neuroscience and Pharmacology, Meharry Medical College, Nashville, Tennessee, USA
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7
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Banerjee P, Voth GA. Conformational transitions of the HIV-1 Gag polyprotein upon multimerization and gRNA binding. Biophys J 2024; 123:42-56. [PMID: 37978800 PMCID: PMC10808027 DOI: 10.1016/j.bpj.2023.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 10/25/2023] [Accepted: 11/16/2023] [Indexed: 11/19/2023] Open
Abstract
During the HIV-1 assembly process, the Gag polyprotein multimerizes at the producer cell plasma membrane, resulting in the formation of spherical immature virus particles. Gag-genomic RNA (gRNA) interactions play a crucial role in the multimerization process, which is yet to be fully understood. We performed large-scale all-atom molecular dynamics simulations of membrane-bound full-length Gag dimer, hexamer, and 18-mer. The inter-domain dynamic correlation of Gag, quantified by the heterogeneous elastic network model applied to the simulated trajectories, is observed to be altered by implicit gRNA binding, as well as the multimerization state of the Gag. The lateral dynamics of our simulated membrane-bound Gag proteins, with and without gRNA binding, agree with prior experimental data and help to validate our simulation models and methods. The gRNA binding is observed to affect mainly the SP1 domain of the 18-mer and the matrix-capsid linker domain of the hexamer. In the absence of gRNA binding, the independent dynamical motion of the nucleocapsid domain results in a collapsed state of the dimeric Gag. Unlike stable SP1 helices in the six-helix bundle, without IP6 binding, the SP1 domain undergoes a spontaneous helix-to-coil transition in the dimeric Gag. Together, our findings reveal conformational switches of Gag at different stages of the multimerization process and predict that the gRNA binding reinforces an efficient binding surface of Gag for multimerization, and also regulates the dynamic organization of the local membrane region itself.
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Affiliation(s)
- Puja Banerjee
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois.
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8
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Draganova EB, Wang H, Wu M, Liao S, Vu A, Gonzalez-Del Pino GL, Zhou ZH, Roller RJ, Heldwein EE. The universal suppressor mutation restores membrane budding defects in the HSV-1 nuclear egress complex by stabilizing the oligomeric lattice. PLoS Pathog 2024; 20:e1011936. [PMID: 38227586 PMCID: PMC10817169 DOI: 10.1371/journal.ppat.1011936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/26/2024] [Accepted: 01/01/2024] [Indexed: 01/18/2024] Open
Abstract
Nuclear egress is an essential process in herpesvirus replication whereby nascent capsids translocate from the nucleus to the cytoplasm. This initial step of nuclear egress-budding at the inner nuclear membrane-is coordinated by the nuclear egress complex (NEC). Composed of the viral proteins UL31 and UL34, NEC deforms the membrane around the capsid as the latter buds into the perinuclear space. NEC oligomerization into a hexagonal membrane-bound lattice is essential for budding because NEC mutants designed to perturb lattice interfaces reduce its budding ability. Previously, we identified an NEC suppressor mutation capable of restoring budding to a mutant with a weakened hexagonal lattice. Using an established in-vitro budding assay and HSV-1 infected cell experiments, we show that the suppressor mutation can restore budding to a broad range of budding-deficient NEC mutants thereby acting as a universal suppressor. Cryogenic electron tomography of the suppressor NEC mutant lattice revealed a hexagonal lattice reminiscent of wild-type NEC lattice instead of an alternative lattice. Further investigation using x-ray crystallography showed that the suppressor mutation promoted the formation of new contacts between the NEC hexamers that, ostensibly, stabilized the hexagonal lattice. This stabilization strategy is powerful enough to override the otherwise deleterious effects of mutations that destabilize the NEC lattice by different mechanisms, resulting in a functional NEC hexagonal lattice and restoration of membrane budding.
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Affiliation(s)
- Elizabeth B. Draganova
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Hui Wang
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, California, United States of America
- Department of Bioengineering, UCLA, Los Angeles, California, United States of America
- California NanoSystems Institute, UCLA, Los Angeles, California, United States of America
| | - Melanie Wu
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Australia
| | - Shiqing Liao
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, California, United States of America
- California NanoSystems Institute, UCLA, Los Angeles, California, United States of America
| | - Amber Vu
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Gonzalo L. Gonzalez-Del Pino
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Z. Hong Zhou
- Department of Microbiology, Immunology & Molecular Genetics, University of California, Los Angeles (UCLA), Los Angeles, California, United States of America
- Department of Bioengineering, UCLA, Los Angeles, California, United States of America
- California NanoSystems Institute, UCLA, Los Angeles, California, United States of America
| | - Richard J. Roller
- Department of Microbiology and Immunology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ekaterina E. Heldwein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
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9
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Tomishige N, Bin Nasim M, Murate M, Pollet B, Didier P, Godet J, Richert L, Sako Y, Mély Y, Kobayashi T. HIV-1 Gag targeting to the plasma membrane reorganizes sphingomyelin-rich and cholesterol-rich lipid domains. Nat Commun 2023; 14:7353. [PMID: 37990014 PMCID: PMC10663554 DOI: 10.1038/s41467-023-42994-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 10/26/2023] [Indexed: 11/23/2023] Open
Abstract
Although the human immunodeficiency virus type 1 lipid envelope has been reported to be enriched with host cell sphingomyelin and cholesterol, the molecular mechanism of the enrichment is not well understood. Viral Gag protein plays a central role in virus budding. Here, we report the interaction between Gag and host cell lipids using different quantitative and super-resolution microscopy techniques in combination with specific probes that bind endogenous sphingomyelin and cholesterol. Our results indicate that Gag in the inner leaflet of the plasma membrane colocalizes with the outer leaflet sphingomyelin-rich domains and cholesterol-rich domains, enlarges sphingomyelin-rich domains, and strongly restricts the mobility of sphingomyelin-rich domains. Moreover, Gag multimerization induces sphingomyelin-rich and cholesterol-rich lipid domains to be in close proximity in a curvature-dependent manner. Our study suggests that Gag binds, coalesces, and reorganizes pre-existing lipid domains during assembly.
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Affiliation(s)
- Nario Tomishige
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan.
| | - Maaz Bin Nasim
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
- Faculty of Pharmacy, The University of Lahore, Lahore, Pakistan
| | - Motohide Murate
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan
| | - Brigitte Pollet
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Pascal Didier
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Julien Godet
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Ludovic Richert
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France
| | - Yasushi Sako
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan
| | - Yves Mély
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
| | - Toshihide Kobayashi
- Laboratoire de Bioimagerie et Pathologies, UMR 7021 CNRS, Faculté de Pharmacie, Université de Strasbourg, Illkirch, France.
- Cellular Informatics Laboratory, RIKEN CPR, Wako, Saitama, Japan.
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10
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Zhu D, Cao D, Zhang X. Virus structures revealed by advanced cryoelectron microscopy methods. Structure 2023; 31:1348-1359. [PMID: 37797619 DOI: 10.1016/j.str.2023.09.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 08/25/2023] [Accepted: 09/11/2023] [Indexed: 10/07/2023]
Abstract
Before the resolution revolution, cryoelectron microscopy (cryo-EM) single-particle analysis (SPA) already achieved resolutions beyond 4 Å for certain icosahedral viruses, enabling ab initio atomic model building of these viruses. As the only samples that achieved such high resolution at that time, cryo-EM method development was closely intertwined with the improvement of reconstructions of symmetrical viruses. Viral morphology exhibits significant diversity, ranging from small to large, uniform to non-uniform, and from containing single symmetry to multiple symmetries. Furthermore, viruses undergo conformational changes during their life cycle. Several methods, such as asymmetric reconstruction, Ewald sphere correction, cryoelectron tomography (cryo-ET), and sub-tomogram averaging (STA), have been developed and applied to determine virus structures in vivo and in vitro. This review outlines current advanced cryo-EM methods for high-resolution structure determination of viruses and summarizes accomplishments obtained with these approaches. Moreover, persisting challenges in comprehending virus structures are discussed and we propose potential solutions.
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Affiliation(s)
- Dongjie Zhu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Duanfang Cao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xinzheng Zhang
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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11
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Graham M, Zhang P. Cryo-electron tomography to study viral infection. Biochem Soc Trans 2023; 51:1701-1711. [PMID: 37560901 PMCID: PMC10578967 DOI: 10.1042/bst20230103] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 07/19/2023] [Accepted: 07/31/2023] [Indexed: 08/11/2023]
Abstract
Developments in cryo-electron microscopy (cryo-EM) have been interwoven with the study of viruses ever since its first applications to biological systems. Following the success of single particle cryo-EM in the last decade, cryo-electron tomography (cryo-ET) is now rapidly maturing as a technology and catalysing great advancement in structural virology as its application broadens. In this review, we provide an overview of the use of cryo-ET to study viral infection biology, discussing the key workflows and strategies used in the field. We highlight the vast body of studies performed on purified viruses and virus-like particles (VLPs), as well as discussing how cryo-ET can characterise host-virus interactions and membrane fusion events. We further discuss the importance of in situ cellular imaging in revealing previously unattainable details of infection and highlight the need for validation of high-resolution findings from purified ex situ systems. We give perspectives for future developments to achieve the full potential of cryo-ET to characterise the molecular processes of viral infection.
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Affiliation(s)
- Miles Graham
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, U.K
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, U.K
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford OX3 7BN, U.K
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12
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Krebs AS, Liu HF, Zhou Y, Rey JS, Levintov L, Shen J, Howe A, Perilla JR, Bartesaghi A, Zhang P. Molecular architecture and conservation of an immature human endogenous retrovirus. Nat Commun 2023; 14:5149. [PMID: 37620323 PMCID: PMC10449913 DOI: 10.1038/s41467-023-40786-w] [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: 01/14/2023] [Accepted: 08/09/2023] [Indexed: 08/26/2023] Open
Abstract
The human endogenous retrovirus K (HERV-K) is the most recently acquired endogenous retrovirus in the human genome and is activated and expressed in many cancers and amyotrophic lateral sclerosis. We present the immature HERV-K capsid structure at 3.2 Å resolution determined from native virus-like particles using cryo-electron tomography and subtomogram averaging. The structure shows a hexamer unit oligomerized through a 6-helix bundle, which is stabilized by a small molecule analogous to IP6 in immature HIV-1 capsid. The HERV-K immature lattice is assembled via highly conserved dimer and trimer interfaces, as detailed through all-atom molecular dynamics simulations and supported by mutational studies. A large conformational change mediated by the linker between the N-terminal and the C-terminal domains of CA occurs during HERV-K maturation. Comparison between HERV-K and other retroviral immature capsid structures reveals a highly conserved mechanism for the assembly and maturation of retroviruses across genera and evolutionary time.
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Affiliation(s)
- Anna-Sophia Krebs
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Hsuan-Fu Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Ye Zhou
- Department of Computer Science, Duke University, Durham, NC, 27708, USA
| | - Juan S Rey
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Lev Levintov
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA
| | - Juan Shen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Andrew Howe
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
| | - Juan R Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE, 19716, USA.
| | - Alberto Bartesaghi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, 27710, USA.
- Department of Computer Science, Duke University, Durham, NC, 27708, USA.
- Department of Electrical and Computer Engineering, Duke University, Durham, NC, 27708, USA.
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK.
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, OX3 7BN, UK.
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13
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Banerjee P, Voth GA. Conformational transitions of the HIV-1 Gag polyprotein upon multimerization and gRNA binding. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.16.553549. [PMID: 37645781 PMCID: PMC10462060 DOI: 10.1101/2023.08.16.553549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
During the HIV-1 assembly process, the Gag polyprotein multimerizes at the producer cell plasma membrane, resulting in the formation of spherical immature virus particles. Gag-gRNA interactions play a crucial role in the multimerization process, which is yet to be fully understood. We have performed large-scale all-atom molecular dynamics simulations of membrane-bound full-length Gag dimer, hexamer, and 18-mer. The inter-domain dynamic correlation of Gag, quantified by the heterogeneous elastic network model (hENM) applied to the simulated trajectories, is observed to be altered by implicit gRNA binding, as well as the multimerization state of the Gag. The lateral dynamics of our simulated membrane-bound Gag proteins, with and without gRNA binding, agree with prior experimental data and help to validate our simulation models and methods. The gRNA binding is observed to impact mainly the SP1 domain of the 18-mer and the MA-CA linker domain of the hexamer. In the absence of gRNA binding, the independent dynamical motion of the NC domain results in a collapsed state of the dimeric Gag. Unlike stable SP1 helices in the six-helix bundle, without IP6 binding, the SP1 domain undergoes a spontaneous helix-to-coil transition in the dimeric Gag. Together, our findings reveal conformational switches of Gag at different stages of the multimerization process and predict that the gRNA binding reinforces an efficient binding surface of Gag for multimerization, as well as regulates the dynamic organization of the local membrane region itself. Significance Gag(Pr 55 Gag ) polyprotein orchestrates many essential events in HIV-1 assembly, including packaging of the genomic RNA (gRNA) in the immature virion. Although various experimental techniques, such as cryo-ET, X-ray, and NMR, have revealed structural properties of individual domains in the immature Gag clusters, structural and biophysical characterization of a full-length Gag molecule remains a challenge for existing experimental techniques. Using atomistic molecular dynamics simulations of the different model systems of Gag polyprotein, we present here a detailed structural characterization of Gag molecules in different multimerization states and interrogate the synergy between Gag-Gag, Gag-membrane, and Gag-gRNA interactions during the viral assembly process.
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14
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Qian Y, Evans D, Mishra B, Fu Y, Liu ZH, Guo S, Johnson ME. Temporal control by cofactors prevents kinetic trapping in retroviral Gag lattice assembly. Biophys J 2023; 122:3173-3190. [PMID: 37393432 PMCID: PMC10432227 DOI: 10.1016/j.bpj.2023.06.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 06/21/2023] [Accepted: 06/27/2023] [Indexed: 07/03/2023] Open
Abstract
For retroviruses like HIV to proliferate, they must form virions shaped by the self-assembly of Gag polyproteins into a rigid lattice. This immature Gag lattice has been structurally characterized and reconstituted in vitro, revealing the sensitivity of lattice assembly to multiple cofactors. Due to this sensitivity, the energetic criterion for forming stable lattices is unknown, as are their corresponding rates. Here, we use a reaction-diffusion model designed from the cryo-ET structure of the immature Gag lattice to map a phase diagram of assembly outcomes controlled by experimentally constrained rates and free energies, over experimentally relevant timescales. We find that productive assembly of complete lattices in bulk solution is extraordinarily difficult due to the large size of this ∼3700 monomer complex. Multiple Gag lattices nucleate before growth can complete, resulting in loss of free monomers and frequent kinetic trapping. We therefore derive a time-dependent protocol to titrate or "activate" the Gag monomers slowly within the solution volume, mimicking the biological roles of cofactors. This general strategy works remarkably well, yielding productive growth of self-assembled lattices for multiple interaction strengths and binding rates. By comparing to the in vitro assembly kinetics, we can estimate bounds on rates of Gag binding to Gag and the cellular cofactor IP6. Our results show that Gag binding to IP6 can provide the additional time delay necessary to support smooth growth of the immature lattice with relatively fast assembly kinetics, mostly avoiding kinetic traps. Our work provides a foundation for predicting and disrupting formation of the immature Gag lattice via targeting specific protein-protein binding interactions.
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Affiliation(s)
- Yian Qian
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Daniel Evans
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Bhavya Mishra
- Department of Physics, and Center for Cellular and Biomolecular Machines, University of California, Merced, California
| | - Yiben Fu
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Zixiu Hugh Liu
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Sikao Guo
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland
| | - Margaret E Johnson
- TC Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, Maryland.
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15
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Obr M, Percipalle M, Chernikova D, Yang H, Thader A, Pinke G, Porley D, Mansky LM, Dick RA, Schur FKM. Unconventional stabilization of the human T-cell leukemia virus type 1 immature Gag lattice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.24.548988. [PMID: 37546793 PMCID: PMC10402013 DOI: 10.1101/2023.07.24.548988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) has an atypical immature particle morphology compared to other retroviruses. This indicates that these particles are formed in a way that is unique. Here we report the results of cryo-electron tomography (cryo-ET) studies of HTLV-1 virus-like particles (VLPs) assembled in vitro, as well as derived from cells. This work shows that HTLV-1 employs an unconventional mechanism of Gag-Gag interactions to form the immature viral lattice. Analysis of high-resolution structural information from immature CA tubular arrays reveals that the primary stabilizing component in HTLV-1 is CA-NTD. Mutagenesis and biophysical analysis support this observation. This distinguishes HTLV-1 from other retroviruses, in which the stabilization is provided primarily by the CA-CTD. These results are the first to provide structural details of the quaternary arrangement of Gag for an immature deltaretrovirus, and this helps explain why HTLV-1 particles are morphologically distinct.
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Affiliation(s)
- Martin Obr
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Mathias Percipalle
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Darya Chernikova
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Huixin Yang
- Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA
| | - Andreas Thader
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Gergely Pinke
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Dario Porley
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA
| | - Robert A Dick
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, USA
| | - Florian KM Schur
- Institute of Science and Technology Austria (ISTA), Klosterneuburg, Austria
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16
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Guo S, Saha I, Saffarian S, Johnson ME. Structure of the HIV immature lattice allows for essential lattice remodeling within budded virions. eLife 2023; 12:e84881. [PMID: 37435945 PMCID: PMC10361719 DOI: 10.7554/elife.84881] [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: 11/12/2022] [Accepted: 07/12/2023] [Indexed: 07/13/2023] Open
Abstract
For HIV virions to become infectious, the immature lattice of Gag polyproteins attached to the virion membrane must be cleaved. Cleavage cannot initiate without the protease formed by the homo-dimerization of domains linked to Gag. However, only 5% of the Gag polyproteins, termed Gag-Pol, carry this protease domain, and they are embedded within the structured lattice. The mechanism of Gag-Pol dimerization is unknown. Here, we use spatial stochastic computer simulations of the immature Gag lattice as derived from experimental structures, showing that dynamics of the lattice on the membrane is unavoidable due to the missing 1/3 of the spherical protein coat. These dynamics allow for Gag-Pol molecules carrying the protease domains to detach and reattach at new places within the lattice. Surprisingly, dimerization timescales of minutes or less are achievable for realistic binding energies and rates despite retaining most of the large-scale lattice structure. We derive a formula allowing extrapolation of timescales as a function of interaction free energy and binding rate, thus predicting how additional stabilization of the lattice would impact dimerization times. We further show that during assembly, dimerization of Gag-Pol is highly likely and therefore must be actively suppressed to prevent early activation. By direct comparison to recent biochemical measurements within budded virions, we find that only moderately stable hexamer contacts (-12kBT<∆G<-8kBT) retain both the dynamics and lattice structures that are consistent with experiment. These dynamics are likely essential for proper maturation, and our models quantify and predict lattice dynamics and protease dimerization timescales that define a key step in understanding formation of infectious viruses.
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Affiliation(s)
- Sikao Guo
- TC Jenkins Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - Ipsita Saha
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of HealthFrederickUnited States
| | - Saveez Saffarian
- Center for Cell and Genome Science, University of UtahSalt Lake CityUnited States
- Department of Physics and Astronomy, University of UtahSalt Lake CityUnited States
- School of Biological Sciences, University of UtahSalt Lake CityUnited States
| | - Margaret E Johnson
- TC Jenkins Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
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17
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Hudait A, Hurley JH, Voth GA. Dynamics of upstream ESCRT organization at the HIV-1 budding site. Biophys J 2023; 122:2655-2674. [PMID: 37218128 PMCID: PMC10397573 DOI: 10.1016/j.bpj.2023.05.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/27/2023] [Accepted: 05/11/2023] [Indexed: 05/24/2023] Open
Abstract
In the late stages of the HIV-1 life cycle, membrane localization and self-assembly of Gag polyproteins induce membrane deformation and budding. Release of the virion requires direct interaction between immature Gag lattice and upstream ESCRT machinery at the viral budding site, followed by assembly of downstream ESCRT-III factors, culminating in membrane scission. However, molecular details of upstream ESCRT assembly dynamics at the viral budding site remain unclear. In this work, using coarse-grained (CG) molecular dynamics (MD) simulations, we investigated the interactions between Gag, ESCRT-I, ESCRT-II, and membrane to delineate the dynamical mechanisms by which upstream ESCRTs assemble templated by late-stage immature Gag lattice. We first systematically derived "bottom-up" CG molecular models and interactions of upstream ESCRT proteins from experimental structural data and extensive all-atom MD simulations. Using these molecular models, we performed CG MD simulations of ESCRT-I oligomerization and ESCRT-I/II supercomplex formation at the neck of the budding virion. Our simulations demonstrate that ESCRT-I can effectively oligomerize to higher-order complexes templated by the immature Gag lattice both in the absence of ESCRT-II and when multiple copies of ESCRT-II are localized at the bud neck. The ESCRT-I/II supercomplexes formed in our simulations exhibit predominantly columnar structures, which has important implications for the nucleation pathway of downstream ESCRT-III polymers. Importantly, ESCRT-I/II supercomplexes bound to Gag initiate membrane neck constriction by pulling the inner edge of the bud neck closer to the ESCRT-I headpiece ring. Our findings serve to elucidate a network of interactions between upstream ESCRT machinery, immature Gag lattice, and membrane neck that regulate protein assembly dynamics at the HIV-1 budding site.
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Affiliation(s)
- Arpa Hudait
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois
| | - James H Hurley
- Department of Molecular and Cell Biology and California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, California; California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, California
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois.
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18
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Krebs AS, Liu HF, Zhou Y, Rey JS, Levintov L, Shen J, Howe A, Perilla JR, Bartesaghi A, Zhang P. Molecular architecture and conservation of an immature human endogenous retrovirus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.07.544027. [PMID: 37333227 PMCID: PMC10274761 DOI: 10.1101/2023.06.07.544027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
A significant part of the human genome consists of endogenous retroviruses sequences. Human endogenous retrovirus K (HERV-K) is the most recently acquired endogenous retrovirus, is activated and expressed in many cancers and amyotrophic lateral sclerosis and possibly contributes to the aging process. To understand the molecular architecture of endogenous retroviruses, we determined the structure of immature HERV-K from native virus-like particles (VLPs) using cryo-electron tomography and subtomogram averaging (cryoET STA). The HERV-K VLPs show a greater distance between the viral membrane and immature capsid lattice, correlating with the presence of additional peptides, SP1 and p15, between the capsid (CA) and matrix (MA) proteins compared to the other retroviruses. The resulting cryoET STA map of the immature HERV-K capsid at 3.2 Å resolution shows a hexamer unit oligomerized through a 6-helix bundle which is further stabilized by a small molecule in the same way as the IP6 in immature HIV-1 capsid. The HERV-K immature CA hexamer assembles into the immature lattice via highly conserved dimmer and trimer interfaces, whose interactions were further detailed through all-atom molecular dynamics simulations and supported by mutational studies. A large conformational change mediated by the flexible linker between the N-terminal and the C-terminal domains of CA occurs between the immature and the mature HERV-K capsid protein, analogous to HIV-1. Comparison between HERV-K and other retroviral immature capsid structures reveals a highly conserved mechanism for the assembly and maturation of retroviruses across genera and evolutionary time.
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Affiliation(s)
- Anna-Sophia Krebs
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Hsuan-Fu Liu
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
| | - Ye Zhou
- Department of Computer Science, Duke University, Durham, NC 27708, USA
| | - Juan S. Rey
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Lev Levintov
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Juan Shen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Andrew Howe
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
| | - Juan R. Perilla
- Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA
| | - Alberto Bartesaghi
- Department of Biochemistry, Duke University School of Medicine, Durham, NC 27710, USA
- Department of Computer Science, Duke University, Durham, NC 27708, USA
- Department of Electrical and Computer Engineering, Duke University, Durham, NC 27708, USA
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, OX3 7BN, UK
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19
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White JA, Wu F, Yasin S, Moskovljevic M, Varriale J, Dragoni F, Camilo-Contreras A, Duan J, Zheng MY, Tadzong NF, Patel HB, Quiambao JMC, Rhodehouse K, Zhang H, Lai J, Beg SA, Delannoy M, Kilcrease C, Hoffmann CJ, Poulin S, Chano F, Tremblay C, Cherian J, Barditch-Crovo P, Chida N, Moore RD, Summers MF, Siliciano RF, Siliciano JD, Simonetti FR. Clonally expanded HIV-1 proviruses with 5'-leader defects can give rise to nonsuppressible residual viremia. J Clin Invest 2023; 133:165245. [PMID: 36602866 PMCID: PMC10014112 DOI: 10.1172/jci165245] [Citation(s) in RCA: 39] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 01/04/2023] [Indexed: 01/06/2023] Open
Abstract
BackgroundAntiretroviral therapy (ART) halts HIV-1 replication, decreasing viremia to below the detection limit of clinical assays. However, some individuals experience persistent nonsuppressible viremia (NSV) originating from CD4+ T cell clones carrying infectious proviruses. Defective proviruses represent over 90% of all proviruses persisting during ART and can express viral genes, but whether they can cause NSV and complicate ART management is unknown.MethodsWe undertook an in-depth characterization of proviruses causing NSV in 4 study participants with optimal adherence and no drug resistance. We investigated the impact of the observed defects on 5'-leader RNA properties, virus infectivity, and gene expression. Integration-site specific assays were used to track these proviruses over time and among cell subsets.ResultsClones carrying proviruses with 5'-leader defects can cause persistent NSV up to approximately 103 copies/mL. These proviruses had small, often identical deletions or point mutations involving the major splicing donor (MSD) site and showed partially reduced RNA dimerization and nucleocapsid binding. Nevertheless, they were inducible and produced noninfectious virions containing viral RNA, but lacking envelope.ConclusionThese findings show that proviruses with 5'-leader defects in CD4+ T cell clones can give rise to NSV, affecting clinical care. Sequencing of the 5'-leader can help in understanding failure to completely suppress viremia.FundingOffice of the NIH Director and National Institute of Dental and Craniofacial Research, NIH; Howard Hughes Medical Institute; Johns Hopkins University Center for AIDS Research; National Institute for Allergy and Infectious Diseases (NIAID), NIH, to the PAVE, BEAT-HIV, and DARE Martin Delaney collaboratories.
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Affiliation(s)
- Jennifer A White
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Fengting Wu
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Saif Yasin
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, USA
| | - Milica Moskovljevic
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Joseph Varriale
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Filippo Dragoni
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Jiayi Duan
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Mei Y Zheng
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, USA
| | - Ndeh F Tadzong
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, USA
| | - Heer B Patel
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, USA
| | - Jeanelle Mae C Quiambao
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, USA
| | - Kyle Rhodehouse
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hao Zhang
- Department of Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Jun Lai
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Subul A Beg
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Michael Delannoy
- Institute for Basic Biomedical Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christin Kilcrease
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Christopher J Hoffmann
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | | | - Cécile Tremblay
- Centre de Recherche du Centre Hospitalier de l'Université de Montréal (CHUM), Montreal, Canada.,Département de Microbiologie, Immunologie et Infectiologie, Université de Montréal, Montreal, Canada
| | - Jerald Cherian
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Patricia Barditch-Crovo
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Natasha Chida
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Richard D Moore
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Michael F Summers
- Department of Chemistry and Biochemistry, University of Maryland, Baltimore County, Baltimore, Maryland, USA.,Howard Hughes Medical Institute, Baltimore, Maryland, USA
| | - Robert F Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA.,Howard Hughes Medical Institute, Baltimore, Maryland, USA
| | - Janet D Siliciano
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Francesco R Simonetti
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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20
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Smith RA, Raugi DN, Nixon RS, Song J, Seydi M, Gottlieb GS. Intrinsic resistance of HIV-2 and SIV to the maturation inhibitor GSK2838232. PLoS One 2023; 18:e0280568. [PMID: 36652466 PMCID: PMC9847912 DOI: 10.1371/journal.pone.0280568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/02/2023] [Indexed: 01/19/2023] Open
Abstract
GSK2838232 (GSK232) is a novel maturation inhibitor that blocks the proteolytic cleavage of HIV-1 Gag at the junction of capsid and spacer peptide 1 (CA/SP1), rendering newly-formed virions non-infectious. To our knowledge, GSK232 has not been tested against HIV-2, and there are limited data regarding the susceptibility of HIV-2 to other HIV-1 maturation inhibitors. To assess the potential utility of GSK232 as an option for HIV-2 treatment, we determined the activity of the compound against a panel of HIV-1, HIV-2, and SIV isolates in culture. GSK232 was highly active against HIV-1 isolates from group M subtypes A, B, C, D, F, and group O, with IC50 values ranging from 0.25-0.92 nM in spreading (multi-cycle) assays and 1.5-2.8 nM in a single cycle of infection. In contrast, HIV-2 isolates from groups A, B, and CRF01_AB, and SIV isolates SIVmac239, SIVmac251, and SIVagm.sab-2, were highly resistant to GSK232. To determine the role of CA/SP1 in the observed phenotypes, we constructed a mutant of HIV-2ROD9 in which the sequence of CA/SP1 was modified to match the corresponding sequence found in HIV-1. The resulting variant was fully susceptible to GSK232 in the single-cycle assay (IC50 = 1.8 nM). Collectively, our data indicate that the HIV-2 and SIV isolates tested in our study are intrinsically resistant to GSK232, and that the determinants of resistance map to CA/SP1. The molecular mechanism(s) responsible for the differential susceptibility of HIV-1 and HIV-2/SIV to GSK232 require further investigation.
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Affiliation(s)
- Robert A. Smith
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- * E-mail:
| | - Dana N. Raugi
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Robert S. Nixon
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Jennifer Song
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
| | - Moussa Seydi
- Service des Maladies Infectieuses et Tropicales, CHNU de Fann, Dakar, Senegal
| | - Geoffrey S. Gottlieb
- Center for Emerging and Reemerging Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, Washington, United States of America
- Department of Global Health, University of Washington, Seattle, Washington, United States of America
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21
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Vijayakrishnan S. In Situ Imaging of Virus-Infected Cells by Cryo-Electron Tomography: An Overview. Subcell Biochem 2023; 106:3-36. [PMID: 38159222 DOI: 10.1007/978-3-031-40086-5_1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Cryo-electron tomography (cryo-ET) has emerged as a powerful tool in structural biology to study viruses and is undergoing a resolution revolution. Enveloped viruses comprise several RNA and DNA pleomorphic viruses that are pathogens of clinical importance to humans and animals. Considerable efforts in cryogenic correlative light and electron microscopy (cryo-CLEM), cryogenic focused ion beam milling (cryo-FIB), and integrative structural techniques are helping to identify virus structures within cells leading to a rise of in situ discoveries shedding light on how viruses interact with their hosts during different stages of infection. This chapter reviews recent advances in the application of cryo-ET in imaging enveloped viruses and the structural and mechanistic insights revealed studying the viral infection cycle within their eukaryotic cellular hosts, with particular attention to viral entry, replication, assembly, and egress during infection.
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Affiliation(s)
- Swetha Vijayakrishnan
- MRC-University of Glasgow Centre for Virus Research, Sir Michael Stoker Building, Garscube Campus, Glasgow, Scotland, UK.
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22
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Lovatt M, Leistner C, Frank RAW. Bridging length scales from molecules to the whole organism by cryoCLEM and cryoET. Faraday Discuss 2022; 240:114-126. [PMID: 35959706 PMCID: PMC9642002 DOI: 10.1039/d2fd00081d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Resolving atomic structures of isolated proteins has uncovered mechanisms and fundamental processes in biology. However, many functions can only be tested in the context of intact cells and tissues that are many orders of magnitude larger than the macromolecules on which they depend. Therefore, methods that interrogate macromolecular structure in situ provide a means of directly relating structure to function across length scales. Here, we developed several workflows using cryogenic correlated light and electron microscopy (cryoCLEM) and electron tomography (cryoET) that can bridge this gap to reveal the molecular infrastructure that underlies higher order functions within cells and tissues. We also describe experimental design considerations, including cryoCLEM labelling, sample preparation, and quality control, for determining the in situ molecular architectures within native, hydrated cells and tissues.
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Affiliation(s)
- Megan Lovatt
- Astbury Centre of Structural Molecular Biology, School of Biomedical Sciences, Faculty of Biological Sciences, University of LeedsLS2 9JTUK
| | - Conny Leistner
- Astbury Centre of Structural Molecular Biology, School of Biomedical Sciences, Faculty of Biological Sciences, University of LeedsLS2 9JTUK
| | - René A. W. Frank
- Astbury Centre of Structural Molecular Biology, School of Biomedical Sciences, Faculty of Biological Sciences, University of LeedsLS2 9JTUK
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23
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Yang H, Talledge N, Arndt WG, Zhang W, Mansky LM. Human Immunodeficiency Virus Type 2 Capsid Protein Mutagenesis Reveals Amino Acid Residues Important for Virus Particle Assembly. J Mol Biol 2022; 434:167753. [PMID: 35868362 PMCID: PMC11057910 DOI: 10.1016/j.jmb.2022.167753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/13/2022] [Accepted: 07/13/2022] [Indexed: 11/16/2022]
Abstract
Human immunodeficiency virus (HIV) Gag drives virus particle assembly. The capsid (CA) domain is critical for Gag multimerization mediated by protein-protein interactions. The Gag protein interaction network defines critical aspects of the retroviral lifecycle at steps such as particle assembly and maturation. Previous studies have demonstrated that the immature particle morphology of HIV-2 is intriguingly distinct relative to that of HIV-1. Based upon this observation, we sought to determine the amino acid residues important for virus assembly that might help explain the differences between HIV-1 and HIV-2. To do this, we conducted site-directed mutagenesis of targeted locations in the HIV-2 CA domain of Gag and analyzed various aspects of virus particle assembly. A panel of 31 site-directed mutants of residues that reside at the HIV-2 CA inter-hexamer interface, intra-hexamer interface and CA inter-domain linker were created and analyzed for their effects on the efficiency of particle production, particle morphology, particle infectivity, Gag subcellular distribution and in vitro protein assembly. Seven conserved residues between HIV-1 and HIV-2 (L19, A41, I152, K153, K157, N194, D196) and two non-conserved residues (G38, N127) were found to significantly impact Gag multimerization and particle assembly. Taken together, these observations complement structural analyses of immature HIV-2 particle morphology and Gag lattice organization as well as provide important comparative insights into the key amino acid residues that can help explain the observed differences between HIV immature particle morphology and its association with virus replication and particle infectivity.
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Affiliation(s)
- Huixin Yang
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA
| | - Nathaniel Talledge
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - William G Arndt
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Biochemistry, Molecular Biology & Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA
| | - Wei Zhang
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Characterization Facility, College of Sciences and Engineering, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
| | - Louis M Mansky
- Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Comparative Molecular Biosciences Graduate Program, University of Minnesota - Twin Cities, St. Paul, MN 55108, USA; Biochemistry, Molecular Biology & Biophysics Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
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24
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Shi D, Huang R. Analysis and comparison of electron radiation damage assessments in Cryo-EM by single particle analysis and micro-crystal electron diffraction. Front Mol Biosci 2022; 9:988928. [PMID: 36275612 PMCID: PMC9585622 DOI: 10.3389/fmolb.2022.988928] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 08/05/2022] [Indexed: 11/25/2022] Open
Abstract
Electron radiation damage to macromolecules is an inevitable resolution limit factor in all major structural determination applications using cryo-electron microscopy (cryo-EM). Single particle analysis (SPA) and micro-crystal electron diffraction (MicroED) have been employed to assess radiation damage with a variety of protein complexes. Although radiation induced sidechain density loss and resolution decay were observed by both methods, the minimum dose of electron irradiation reducing high-resolution limit reported by SPA is more than ten folds higher than measured by MicroED using the conventional dose concept, and there is a gap between the attained resolutions assessed by these two methods. We compared and analyzed these two approaches side-by-side in detail from several aspects to identify some crucial determinants and to explain this discrepancy. Probability of a high energy electron being inelastically scattered by a macromolecule is proportional to number of layers of the molecules in its transmission path. As a result, the same electron dose could induce much more site-specific damage to macromolecules in 3D protein crystal than single particle samples. Major differences in data collection and processing scheme are the key factors to different levels of sensitivity to radiation damage at high resolution between the two methods. High resolution electron diffraction in MicroED dataset is very sensitive to global damage to 3D protein crystals with low dose accumulation, and its intensity attenuation rates at atomic resolution shell could be applied for estimating ratio of damaged and total selected single particles for SPA. More in-depth systematically radiation damage assessments using SPA and MicroED will benefit all applications of cryo-EM, especially cellular structure analysis by tomography.
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Affiliation(s)
- Dan Shi
- Center for Structural Biology, Center for Cancer Research, National Cancer Institute, Frederick, MD, United States
- *Correspondence: Dan Shi,
| | - Rick Huang
- Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, United States
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25
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Regueiro-Ren A, Sit SY, Chen Y, Chen J, Swidorski JJ, Liu Z, Venables BL, Sin N, Hartz RA, Protack T, Lin Z, Zhang S, Li Z, Wu DR, Li P, Kempson J, Hou X, Gupta A, Rampulla R, Mathur A, Park H, Sarjeant A, Benitex Y, Rahematpura S, Parker D, Phillips T, Haskell R, Jenkins S, Santone KS, Cockett M, Hanumegowda U, Dicker I, Meanwell NA, Krystal M. The Discovery of GSK3640254, a Next-Generation Inhibitor of HIV-1 Maturation. J Med Chem 2022; 65:11927-11948. [PMID: 36044257 DOI: 10.1021/acs.jmedchem.2c00879] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
GSK3640254 is an HIV-1 maturation inhibitor (MI) that exhibits significantly improved antiviral activity toward a range of clinically relevant polymorphic variants with reduced sensitivity toward the second-generation MI GSK3532795 (BMS-955176). The key structural difference between GSK3640254 and its predecessor is the replacement of the para-substituted benzoic acid moiety attached at the C-3 position of the triterpenoid core with a cyclohex-3-ene-1-carboxylic acid substituted with a CH2F moiety at the carbon atom α- to the pharmacophoric carboxylic acid. This structural element provided a new vector with which to explore structure-activity relationships (SARs) and led to compounds with improved polymorphic coverage while preserving pharmacokinetic (PK) properties. The approach to the design of GSK3640254, the development of a synthetic route and its preclinical profile are discussed. GSK3640254 is currently in phase IIb clinical trials after demonstrating a dose-related reduction in HIV-1 viral load over 7-10 days of dosing to HIV-1-infected subjects.
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Affiliation(s)
- Alicia Regueiro-Ren
- Small Molecule Drug Discovery, Bristol Myers Squibb Research and Early Development, Princeton, New Jersey08543, United States
| | - Sing-Yuen Sit
- Department of Discovery Chemistry, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Yan Chen
- Department of Discovery Chemistry, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Jie Chen
- Department of Discovery Chemistry, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Jacob J Swidorski
- Department of Discovery Chemistry, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Zheng Liu
- Department of Discovery Chemistry, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Brian L Venables
- Department of Discovery Chemistry, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Ny Sin
- Department of Discovery Chemistry, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Richard A Hartz
- Department of Discovery Chemistry, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Tricia Protack
- Department of Virology, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Zeyu Lin
- Department of Virology, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Sharon Zhang
- Department of Virology, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Zhufang Li
- Department of Virology, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Dauh-Rurng Wu
- Department of Discovery Synthesis, Bristol Myers Squibb Research and Early Development, PO Box 4000, Princeton, New Jersey08543, United States
| | - Peng Li
- Department of Discovery Synthesis, Bristol Myers Squibb Research and Early Development, PO Box 4000, Princeton, New Jersey08543, United States
| | - James Kempson
- Department of Discovery Synthesis, Bristol Myers Squibb Research and Early Development, PO Box 4000, Princeton, New Jersey08543, United States
| | - Xiaoping Hou
- Department of Discovery Synthesis, Bristol Myers Squibb Research and Early Development, PO Box 4000, Princeton, New Jersey08543, United States
| | - Anuradha Gupta
- Department of Discovery Synthesis; Bristol Myers Squibb Research and Early Development, Bangalore 560099, India
| | - Richard Rampulla
- Department of Discovery Synthesis, Bristol Myers Squibb Research and Early Development, PO Box 4000, Princeton, New Jersey08543, United States
| | - Arvind Mathur
- Department of Discovery Synthesis, Bristol Myers Squibb Research and Early Development, PO Box 4000, Princeton, New Jersey08543, United States
| | - Hyunsoo Park
- Bristol Myers Squibb Chemical and Synthetic Development, New Brunswick, New Jersey08901, United States
| | - Amy Sarjeant
- Bristol Myers Squibb Chemical and Synthetic Development, New Brunswick, New Jersey08901, United States
| | - Yulia Benitex
- Department of Pharmaceutical Candidate Optimization, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Sandhya Rahematpura
- Department of Pharmaceutical Candidate Optimization, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Dawn Parker
- Department of Pharmaceutical Candidate Optimization, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Thomas Phillips
- Department of Pharmaceutical Candidate Optimization, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Roy Haskell
- Department of Pharmaceutical Candidate Optimization, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Susan Jenkins
- Department of Pharmaceutical Candidate Optimization, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Kenneth S Santone
- Department of Pharmaceutical Candidate Optimization, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Mark Cockett
- Department of Virology, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Umesh Hanumegowda
- Department of Pharmaceutical Candidate Optimization, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Ira Dicker
- Department of Virology, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
| | - Nicholas A Meanwell
- Small Molecule Drug Discovery, Bristol Myers Squibb Research and Early Development, Princeton, New Jersey08543, United States
| | - Mark Krystal
- Department of Virology, Bristol Myers Squibb Research and Early Development, 5 Research Parkway, Wallingford, Connecticut06492, United States
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26
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Thorsen MK, Draganova EB, Heldwein EE. The nuclear egress complex of Epstein-Barr virus buds membranes through an oligomerization-driven mechanism. PLoS Pathog 2022; 18:e1010623. [PMID: 35802751 PMCID: PMC9299292 DOI: 10.1371/journal.ppat.1010623] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 07/20/2022] [Accepted: 05/28/2022] [Indexed: 11/21/2022] Open
Abstract
During replication, herpesviral capsids are translocated from the nucleus into the cytoplasm by an unusual mechanism, termed nuclear egress, that involves capsid budding at the inner nuclear membrane. This process is mediated by the viral nuclear egress complex (NEC) that deforms the membrane around the capsid. Although the NEC is essential for capsid nuclear egress across all three subfamilies of the Herpesviridae, most studies to date have focused on the NEC homologs from alpha- and beta- but not gammaherpesviruses. Here, we report the crystal structure of the NEC from Epstein-Barr virus (EBV), a prototypical gammaherpesvirus. The structure resembles known structures of NEC homologs yet is conformationally dynamic. We also show that purified, recombinant EBV NEC buds synthetic membranes in vitro and forms membrane-bound coats of unknown geometry. However, unlike other NEC homologs, EBV NEC forms dimers in the crystals instead of hexamers. The dimeric interfaces observed in the EBV NEC crystals are similar to the hexameric interfaces observed in other NEC homologs. Moreover, mutations engineered to disrupt the dimeric interface reduce budding. Putting together these data, we propose that EBV NEC-mediated budding is driven by oligomerization into membrane-bound coats. Herpesviruses, which infect most of the world’s population for life, translocate their capsids from the nucleus, where they are formed, into the cytoplasm, where they mature into infectious virions, by an unusual mechanism, termed nuclear egress. During nuclear budding, an early step in this process, the inner nuclear membrane is deformed around the capsid by the complex of two viral proteins termed the nuclear egress complex (NEC). The NEC is conserved across all three subfamilies of Herpesviruses and essential for nuclear egress. However, most studies to date have focused on the NEC homologs from alpha- and betaherpesviruses while less is known about the NEC from gammaherpesviruses. Here, we determined the crystal structure of the NEC from Epstein-Barr virus (EBV), a prototypical gammaherpesvirus, and investigated its membrane budding properties in vitro. Our data show that the ability to vesiculate membranes by forming membrane-bound coats and the structure are conserved across the NEC homologs from all three subfamilies. However, the EBV NEC may employ a distinct membrane-budding mechanism due to its structural flexibility and the ability to form coats of different geometry.
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Affiliation(s)
- Michael K. Thorsen
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Graduate Program in Cellular, Molecular, and Developmental Biology, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Elizabeth B. Draganova
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
| | - Ekaterina E. Heldwein
- Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- Graduate Program in Cellular, Molecular, and Developmental Biology, Graduate School of Biomedical Sciences, Tufts University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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27
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Pak A, Gupta M, Yeager M, Voth GA. Inositol Hexakisphosphate (IP6) Accelerates Immature HIV-1 Gag Protein Assembly toward Kinetically Trapped Morphologies. J Am Chem Soc 2022; 144:10417-10428. [PMID: 35666943 PMCID: PMC9204763 DOI: 10.1021/jacs.2c02568] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
During the late stages of the HIV-1 lifecycle, immature virions are produced by the concerted activity of Gag polyproteins, primarily mediated by the capsid (CA) and spacer peptide 1 (SP1) domains, which assemble into a spherical lattice, package viral genomic RNA, and deform the plasma membrane. Recently, inositol hexakisphosphate (IP6) has been identified as an essential assembly cofactor that efficiently produces both immature virions in vivo and immature virus-like particles in vitro. To date, however, several distinct mechanistic roles for IP6 have been proposed on the basis of independent functional, structural, and kinetic studies. In this work, we investigate the molecular influence of IP6 on the structural outcomes and dynamics of CA/SP1 assembly using coarse-grained (CG) molecular dynamics (MD) simulations and free energy calculations. Here, we derive a bottom-up, low-resolution, and implicit-solvent CG model of CA/SP1 and IP6, and simulate their assembly under conditions that emulate both in vitro and in vivo systems. Our analysis identifies IP6 as an assembly accelerant that promotes curvature generation and fissure-like defects throughout the lattice. Our findings suggest that IP6 induces kinetically trapped immature morphologies, which may be physiologically important for later stages of viral morphogenesis and potentially useful for virus-like particle technologies.
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Affiliation(s)
- Alexander
J. Pak
- Department
of Chemistry, Chicago Center for Theoretical Chemistry, Institute
for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | - Manish Gupta
- Department
of Chemistry, Chicago Center for Theoretical Chemistry, Institute
for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | - Mark Yeager
- Department
of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States,Center
for Membrane Biology, University of Virginia
School of Medicine, Charlottesville, Virginia 22908, United States, United States,Cardiovascular
Research Center, University of Virginia
School of Medicine, Charlottesville, Virginia 22908, United States,Department
of Medicine, Division of Cardiovascular Medicine, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States
| | - Gregory A. Voth
- Department
of Chemistry, Chicago Center for Theoretical Chemistry, Institute
for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States,E-mail:
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28
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Ruml T. The Present and Future of Virology in the Czech Republic-A New Phoenix Made of Ashes? Viruses 2022; 14:v14061303. [PMID: 35746773 PMCID: PMC9231214 DOI: 10.3390/v14061303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/10/2022] [Accepted: 06/10/2022] [Indexed: 12/10/2022] Open
Affiliation(s)
- Tomas Ruml
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, 166 28 Prague, Czech Republic
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29
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Meissner ME, Talledge N, Mansky LM. Molecular Biology and Diversification of Human Retroviruses. FRONTIERS IN VIROLOGY 2022; 2:872599. [PMID: 35783361 PMCID: PMC9242851 DOI: 10.3389/fviro.2022.872599] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Studies of retroviruses have led to many extraordinary discoveries that have advanced our understanding of not only human diseases, but also molecular biology as a whole. The most recognizable human retrovirus, human immunodeficiency virus type 1 (HIV-1), is the causative agent of the global AIDS epidemic and has been extensively studied. Other human retroviruses, such as human immunodeficiency virus type 2 (HIV-2) and human T-cell leukemia virus type 1 (HTLV-1), have received less attention, and many of the assumptions about the replication and biology of these viruses are based on knowledge of HIV-1. Existing comparative studies on human retroviruses, however, have revealed that key differences between these viruses exist that affect evolution, diversification, and potentially pathogenicity. In this review, we examine current insights on disparities in the replication of pathogenic human retroviruses, with a particular focus on the determinants of structural and genetic diversity amongst HIVs and HTLV.
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Affiliation(s)
- Morgan E. Meissner
- Institute for Molecular Virology, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Molecular, Cellular, Developmental Biology and Genetics Graduate Program, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
| | - Nathaniel Talledge
- Institute for Molecular Virology, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Division of Basic Sciences, School of Dentistry, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Masonic Cancer Center, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
| | - Louis M. Mansky
- Institute for Molecular Virology, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Division of Basic Sciences, School of Dentistry, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Molecular, Cellular, Developmental Biology and Genetics Graduate Program, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
- Masonic Cancer Center, University of Minnesota – Twin Cities, Minneapolis, MN 55455 USA
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30
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Sumner C, Ono A. Relationship between HIV-1 Gag Multimerization and Membrane Binding. Viruses 2022; 14:v14030622. [PMID: 35337029 PMCID: PMC8949992 DOI: 10.3390/v14030622] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/06/2022] [Accepted: 03/09/2022] [Indexed: 12/11/2022] Open
Abstract
HIV-1 viral particle assembly occurs specifically at the plasma membrane and is driven primarily by the viral polyprotein Gag. Selective association of Gag with the plasma membrane is a key step in the viral assembly pathway, which is traditionally attributed to the MA domain. MA regulates specific plasma membrane binding through two primary mechanisms including: (1) specific interaction of the MA highly basic region (HBR) with the plasma membrane phospholipid phosphatidylinositol (4,5) bisphosphate [PI(4,5)P2], and (2) tRNA binding to the MA HBR, which prevents Gag association with non-PI(4,5)P2 containing membranes. Gag multimerization, driven by both CA–CA inter-protein interactions and NC-RNA binding, also plays an essential role in viral particle assembly, mediating the establishment and growth of the immature Gag lattice on the plasma membrane. In addition to these functions, the multimerization of HIV-1 Gag has also been demonstrated to enhance its membrane binding activity through the MA domain. This review provides an overview of the mechanisms regulating Gag membrane binding through the MA domain and multimerization through the CA and NC domains, and examines how these two functions are intertwined, allowing for multimerization mediated enhancement of Gag membrane binding.
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31
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Yu A, Lee EMY, Briggs JAG, Ganser-Pornillos BK, Pornillos O, Voth GA. Strain and rupture of HIV-1 capsids during uncoating. Proc Natl Acad Sci U S A 2022; 119:e2117781119. [PMID: 35238630 PMCID: PMC8915963 DOI: 10.1073/pnas.2117781119] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 01/25/2022] [Indexed: 12/18/2022] Open
Abstract
SignificanceThe mature capsids of HIV-1 are transiently stable complexes that self-assemble around the viral genome during maturation, and uncoat to release preintegration complexes that archive a double-stranded DNA copy of the virus in the host cell genome. However, a detailed view of how HIV cores rupture remains lacking. Here, we elucidate the physical properties involved in capsid rupture using a combination of large-scale all-atom molecular dynamics simulations and cryo-electron tomography. We find that intrinsic strain on the capsid forms highly correlated patterns along the capsid surface, along which cracks propagate. Capsid rigidity also increases with high strain. Our findings provide fundamental insight into viral capsid uncoating.
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Affiliation(s)
- Alvin Yu
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637
| | - Elizabeth M. Y. Lee
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL 60637
| | - John A. G. Briggs
- Department of Cell and Virus Structure, Max Planck Institute of Biochemistry, 82152 Martinsried, Germany
| | - Barbie K. Ganser-Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903
| | - Owen Pornillos
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, VA 22903
| | - Gregory A. Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, IL 60637
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32
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Vankadari N, Shepherd DC, Carter SD, Ghosal D. Three-dimensional insights into human enveloped viruses in vitro and in situ. Biochem Soc Trans 2022; 50:95-105. [PMID: 35076655 PMCID: PMC9022983 DOI: 10.1042/bst20210433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/22/2021] [Accepted: 12/23/2021] [Indexed: 11/17/2022]
Abstract
Viruses can be enveloped or non-enveloped, and require a host cell to replicate and package their genomes into new virions to infect new cells. To accomplish this task, viruses hijack the host-cell machinery to facilitate their replication by subverting and manipulating normal host cell function. Enveloped viruses can have severe consequences for human health, causing various diseases such as acquired immunodeficiency syndrome (AIDS), seasonal influenza, COVID-19, and Ebola virus disease. The complex arrangement and pleomorphic architecture of many enveloped viruses pose a challenge for the more widely used structural biology techniques, such as X-ray crystallography. Cryo-electron tomography (cryo-ET), however, is a particularly well-suited tool for overcoming the limitations associated with visualizing the irregular shapes and morphology enveloped viruses possess at macromolecular resolution. The purpose of this review is to explore the latest structural insights that cryo-ET has revealed about enveloped viruses, with particular attention given to their architectures, mechanisms of entry, replication, assembly, maturation and egress during infection. Cryo-ET is unique in its ability to visualize cellular landscapes at 3-5 nanometer resolution. Therefore, it is the most suited technique to study asymmetric elements and structural rearrangements of enveloped viruses during infection in their native cellular context.
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Affiliation(s)
- Naveen Vankadari
- Monash Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC, Australia
| | - Doulin C. Shepherd
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Stephen D. Carter
- Centre for Virus Research, Medical Research Council-University of Glasgow Centre for Virus Research, Glasgow, U.K
| | - Debnath Ghosal
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
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33
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Lerner G, Weaver N, Anokhin B, Spearman P. Advances in HIV-1 Assembly. Viruses 2022; 14:v14030478. [PMID: 35336885 PMCID: PMC8952333 DOI: 10.3390/v14030478] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/22/2022] [Accepted: 02/24/2022] [Indexed: 12/10/2022] Open
Abstract
The assembly of HIV-1 particles is a concerted and dynamic process that takes place on the plasma membrane of infected cells. An abundance of recent discoveries has advanced our understanding of the complex sequence of events leading to HIV-1 particle assembly, budding, and release. Structural studies have illuminated key features of assembly and maturation, including the dramatic structural transition that occurs between the immature Gag lattice and the formation of the mature viral capsid core. The critical role of inositol hexakisphosphate (IP6) in the assembly of both the immature and mature Gag lattice has been elucidated. The structural basis for selective packaging of genomic RNA into virions has been revealed. This review will provide an overview of the HIV-1 assembly process, with a focus on recent advances in the field, and will point out areas where questions remain that can benefit from future investigation.
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Mangala Prasad V, Leaman DP, Lovendahl KN, Croft JT, Benhaim MA, Hodge EA, Zwick MB, Lee KK. Cryo-ET of Env on intact HIV virions reveals structural variation and positioning on the Gag lattice. Cell 2022; 185:641-653.e17. [PMID: 35123651 PMCID: PMC9000915 DOI: 10.1016/j.cell.2022.01.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 10/19/2021] [Accepted: 01/18/2022] [Indexed: 01/11/2023]
Abstract
HIV-1 Env mediates viral entry into host cells and is the sole target for neutralizing antibodies. However, Env structure and organization in its native virion context has eluded detailed characterization. Here, we used cryo-electron tomography to analyze Env in mature and immature HIV-1 particles. Immature particles showed distinct Env positioning relative to the underlying Gag lattice, providing insights into long-standing questions about Env incorporation. A 9.1-Å sub-tomogram-averaged reconstruction of virion-bound Env in conjunction with structural mass spectrometry revealed unexpected features, including a variable central core of the gp41 subunit, heterogeneous glycosylation between protomers, and a flexible stalk that allows Env tilting and variable exposure of neutralizing epitopes. Together, our results provide an integrative understanding of HIV assembly and structural variation in Env antigen presentation.
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Affiliation(s)
- Vidya Mangala Prasad
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Daniel P Leaman
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Klaus N Lovendahl
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Jacob T Croft
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Mark A Benhaim
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Edgar A Hodge
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA
| | - Michael B Zwick
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA 92037, USA.
| | - Kelly K Lee
- Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195, USA; Biological Physics, Structure and Design Graduate Program, University of Washington, Seattle, WA 98195, USA; Department of Microbiology, University of Washington, Seattle, WA 98195, USA.
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35
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Weiner E, Pinskey JM, Nicastro D, Otegui MS. Electron microscopy for imaging organelles in plants and algae. PLANT PHYSIOLOGY 2022; 188:713-725. [PMID: 35235662 PMCID: PMC8825266 DOI: 10.1093/plphys/kiab449] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 08/23/2021] [Indexed: 05/31/2023]
Abstract
Recent developments in both instrumentation and image analysis algorithms have allowed three-dimensional electron microscopy (3D-EM) to increase automated image collections through large tissue volumes using serial block-face scanning EM (SEM) and to achieve near-atomic resolution of macromolecular complexes using cryo-electron tomography (cryo-ET) and sub-tomogram averaging. In this review, we discuss applications of cryo-ET to cell biology research on plant and algal systems and the special opportunities they offer for understanding the organization of eukaryotic organelles with unprecedently resolution. However, one of the most challenging aspects for cryo-ET is sample preparation, especially for multicellular organisms. We also discuss correlative light and electron microscopy (CLEM) approaches that have been developed for ET at both room and cryogenic temperatures.
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Affiliation(s)
- Ethan Weiner
- Department of Botany, University of Wisconsin, Madison 53706, Wisconsin
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison 53706, Wisconsin
| | - Justine M Pinskey
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas 75390, Texas
| | - Daniela Nicastro
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas 75390, Texas
| | - Marisa S Otegui
- Department of Botany, University of Wisconsin, Madison 53706, Wisconsin
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison 53706, Wisconsin
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36
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Gilmer O, Mailler E, Paillart JC, Mouhand A, Tisné C, Mak J, Smyth RP, Marquet R, Vivet-Boudou V. Structural maturation of the HIV-1 RNA 5' untranslated region by Pr55 Gag and its maturation products. RNA Biol 2022; 19:191-205. [PMID: 35067194 PMCID: PMC8786341 DOI: 10.1080/15476286.2021.2021677] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Maturation of the HIV-1 viral particles shortly after budding is required for infectivity. During this process, the Pr55Gag precursor undergoes a cascade of proteolytic cleavages, and whilst the structural rearrangements of the viral proteins are well understood, the concomitant maturation of the genomic RNA (gRNA) structure is unexplored, despite evidence that it is required for infectivity. To get insight into this process, we systematically analysed the interactions between Pr55Gag or its maturation products (NCp15, NCp9 and NCp7) and the 5ʹ gRNA region and their structural consequences, in vitro. We show that Pr55Gag and its maturation products mostly bind at different RNA sites and with different contributions of their two zinc knuckle domains. Importantly, these proteins have different transient and permanent effects on the RNA structure, the late NCp9 and NCp7 inducing dramatic structural rearrangements. Altogether, our results reveal the distinct contributions of the different Pr55Gag maturation products on the gRNA structural maturation.
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Affiliation(s)
- Orian Gilmer
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Elodie Mailler
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Jean-Christophe Paillart
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Assia Mouhand
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-chimique, Paris, France
| | - Carine Tisné
- Expression Génétique Microbienne, UMR 8261, CNRS, Université de Paris, Institut de Biologie Physico-chimique, Paris, France
| | - Johnson Mak
- Institute for Glycomics, Griffith University, Gold Coast, Australia
| | - Redmond P Smyth
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Roland Marquet
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
| | - Valérie Vivet-Boudou
- Université de Strasbourg, CNRS, Architecture et Réactivité de l'ARN, UPR 9002, IBMC, Strasbourg, France
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37
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Targeting the Virus Capsid as a Tool to Fight RNA Viruses. Viruses 2022; 14:v14020174. [PMID: 35215767 PMCID: PMC8879806 DOI: 10.3390/v14020174] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 12/10/2022] Open
Abstract
Several strategies have been developed to fight viral infections, not only in humans but also in animals and plants. Some of them are based on the development of efficient vaccines, to target the virus by developed antibodies, others focus on finding antiviral compounds with activities that inhibit selected virus replication steps. Currently, there is an increasing number of antiviral drugs on the market; however, some have unpleasant side effects, are toxic to cells, or the viruses quickly develop resistance to them. As the current situation shows, the combination of multiple antiviral strategies or the combination of the use of various compounds within one strategy is very important. The most desirable are combinations of drugs that inhibit different steps in the virus life cycle. This is an important issue especially for RNA viruses, which replicate their genomes using error-prone RNA polymerases and rapidly develop mutants resistant to applied antiviral compounds. Here, we focus on compounds targeting viral structural capsid proteins, thereby inhibiting virus assembly or disassembly, virus binding to cellular receptors, or acting by inhibiting other virus replication mechanisms. This review is an update of existing papers on a similar topic, by focusing on the most recent advances in the rapidly evolving research of compounds targeting capsid proteins of RNA viruses.
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Krebs AS, Mendonça LM, Zhang P. Structural Analysis of Retrovirus Assembly and Maturation. Viruses 2021; 14:54. [PMID: 35062258 PMCID: PMC8778513 DOI: 10.3390/v14010054] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 12/30/2022] Open
Abstract
Retroviruses have a very complex and tightly controlled life cycle which has been studied intensely for decades. After a virus enters the cell, it reverse-transcribes its genome, which is then integrated into the host genome, and subsequently all structural and regulatory proteins are transcribed and translated. The proteins, along with the viral genome, assemble into a new virion, which buds off the host cell and matures into a newly infectious virion. If any one of these steps are faulty, the virus cannot produce infectious viral progeny. Recent advances in structural and molecular techniques have made it possible to better understand this class of viruses, including details about how they regulate and coordinate the different steps of the virus life cycle. In this review we summarize the molecular analysis of the assembly and maturation steps of the life cycle by providing an overview on structural and biochemical studies to understand these processes. We also outline the differences between various retrovirus families with regards to these processes.
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Affiliation(s)
- Anna-Sophia Krebs
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
| | - Luiza M. Mendonça
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
| | - Peijun Zhang
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK; (A.-S.K.); (L.M.M.)
- Electron Bio-Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford OX3 7BN, UK
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39
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Determining structures in a native environment using single-particle cryoelectron microscopy images. ACTA ACUST UNITED AC 2021; 2:100166. [PMID: 34632438 PMCID: PMC8488058 DOI: 10.1016/j.xinn.2021.100166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 05/21/2021] [Indexed: 12/05/2022]
Abstract
Cryo-electron tomography is a powerful tool for structure determination in the native environment. However, this method requires the acquisition of tilt series, which is time-consuming and severely slows structure determination. By treating the densities of non-target protein as non-Gaussian noise, we developed a new target function that greatly improves the efficiency of recognizing the target protein in a single cryo-electron microscopy image. Moreover, we developed a sorting function that effectively eliminates the model dependence and improved the resolution during the subsequent structure refinement procedure. By eliminating model bias, our method allows using homolog proteins as models to recognize the target proteins in a complex context. Together, we developed an in situ single-particle analysis method. Our method was successfully applied to solve structures of glycoproteins on the surface of a non-icosahedral virus and Rubisco inside the carboxysome. Both data were collected within 24 h, thus allowing fast and simple structural determination. Structures could be achieved when proteins are overlapped with surroundings free of tilt series The particle detection efficiency is significantly improved Allowing the usage of homolog proteins as templates The throughput of structure determination is remarkably enhanced
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40
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Pak AJ, Purdy MD, Yeager M, Voth GA. Preservation of HIV-1 Gag Helical Bundle Symmetry by Bevirimat Is Central to Maturation Inhibition. J Am Chem Soc 2021; 143:19137-19148. [PMID: 34739240 DOI: 10.1021/jacs.1c08922] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The assembly and maturation of human immunodeficiency virus type 1 (HIV-1) require proteolytic cleavage of the Gag polyprotein. The rate-limiting step resides at the junction between the capsid protein CA and spacer peptide 1, which assembles as a six-helix bundle (6HB). Bevirimat (BVM), the first-in-class maturation inhibitor drug, targets the 6HB and impedes proteolytic cleavage, yet the molecular mechanisms of its activity, and relatedly, the escape mechanisms of mutant viruses, remain unclear. Here, we employed extensive molecular dynamics (MD) simulations and free energy calculations to quantitatively investigate molecular structure-activity relationships, comparing wild-type and mutant viruses in the presence and absence of BVM and inositol hexakisphosphate (IP6), an assembly cofactor. Our analysis shows that the efficacy of BVM is directly correlated with preservation of 6-fold symmetry in the 6HB, which exists as an ensemble of structural states. We identified two primary escape mechanisms, and both lead to loss of symmetry, thereby facilitating helix uncoiling to aid access of protease. Our findings also highlight specific interactions that can be targeted for improved inhibitor activity and support the use of MD simulations for future inhibitor design.
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Affiliation(s)
- Alexander J Pak
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
| | - Michael D Purdy
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States.,Center for Membrane Biology, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States.,Cardiovascular Research Center, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States.,Department of Medicine, Division of Cardiovascular Medicine, University of Virginia School of Medicine, Charlottesville, Virginia 22908, United States
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, United States
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41
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Stephan Oroszlan and the Proteolytic Processing of Retroviral Proteins: Following A Pro. Viruses 2021; 13:v13112218. [PMID: 34835024 PMCID: PMC8621278 DOI: 10.3390/v13112218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/22/2021] [Accepted: 10/24/2021] [Indexed: 12/26/2022] Open
Abstract
Steve Oroszlan determined the sequences at the ends of virion proteins for a number of different retroviruses. This work led to the insight that the amino-terminal amino acid of the mature viral CA protein is always proline. In this remembrance, we review Steve’s work that led to this insight and show how that insight was a necessary precursor to the work we have done in the subsequent years exploring the cleavage rate determinants of viral protease processing sites and the multiple roles the amino-terminal proline of CA plays after protease cleavage liberates it from its position in a protease processing site.
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42
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Precursors of Viral Proteases as Distinct Drug Targets. Viruses 2021; 13:v13101981. [PMID: 34696411 PMCID: PMC8537868 DOI: 10.3390/v13101981] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/25/2021] [Accepted: 09/28/2021] [Indexed: 12/16/2022] Open
Abstract
Viral proteases are indispensable for successful virion maturation, thus making them a prominent drug target. Their enzyme activity is tightly spatiotemporally regulated by expression in the precursor form with little or no activity, followed by activation via autoprocessing. These cleavage events are frequently triggered upon transportation to a specific compartment inside the host cell. Typically, precursor oligomerization or the presence of a co-factor is needed for activation. A detailed understanding of these mechanisms will allow ligands with non-canonical mechanisms of action to be designed, which would specifically modulate the initial irreversible steps of viral protease autoactivation. Binding sites exclusive to the precursor, including binding sites beyond the protease domain, can be exploited. Both inhibition and up-regulation of the proteolytic activity of viral proteases can be detrimental for the virus. All these possibilities are discussed using examples of medically relevant viruses including herpesviruses, adenoviruses, retroviruses, picornaviruses, caliciviruses, togaviruses, flaviviruses, and coronaviruses.
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43
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Saha I, Preece B, Peterson A, Durden H, MacArthur B, Lowe J, Belnap D, Vershinin M, Saffarian S. Gag-Gag Interactions Are Insufficient to Fully Stabilize and Order the Immature HIV Gag Lattice. Viruses 2021; 13:1946. [PMID: 34696376 PMCID: PMC8540168 DOI: 10.3390/v13101946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/24/2021] [Accepted: 09/24/2021] [Indexed: 11/16/2022] Open
Abstract
Immature HIV virions harbor a lattice of Gag molecules with significant ordering in CA-NTD, CA-CTD and SP1 regions. This ordering plays a major role during HIV maturation. To test the condition in which the Gag lattice forms in vivo, we assembled virus like particles (VLPs) by expressing only HIV Gag in mammalian cells. Here we show that these VLPs incorporate a similar number of Gag molecules compared to immature HIV virions. However, within these VLPs, Gag molecules diffuse with a pseudo-diffusion rate of 10 nm2/s, this pseudo-diffusion is abrogated in the presence of melittin and is sensitive to mutations within the SP1 region. Using cryotomography, we show that unlike immature HIV virions, in the Gag lattice of VLPs the CA-CTD and SP1 regions are significantly less ordered. Our observations suggest that within immature HIV virions, other viral factors in addition to Gag, contribute to ordering in the CA-CTD and SP1 regions.
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Affiliation(s)
- Ipsita Saha
- Laboratory of Cell and Developmental Signaling, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD 21702, USA;
| | - Benjamin Preece
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Abby Peterson
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Haley Durden
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Brian MacArthur
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
| | - Jake Lowe
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (D.B.)
| | - David Belnap
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (D.B.)
- Department of Biochemistry, University of Utah, Salt Lake City, UT 84112, USA
| | - Michael Vershinin
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (D.B.)
| | - Saveez Saffarian
- Center for Cell and Genome Science, University of Utah, Salt Lake City, UT 84112, USA; (B.P.); (A.P.); (H.D.); (B.M.); (M.V.)
- Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA; (J.L.); (D.B.)
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44
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A Structural Perspective of the Role of IP6 in Immature and Mature Retroviral Assembly. Viruses 2021; 13:v13091853. [PMID: 34578434 PMCID: PMC8473085 DOI: 10.3390/v13091853] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/10/2021] [Accepted: 09/12/2021] [Indexed: 11/17/2022] Open
Abstract
The small cellular molecule inositol hexakisphosphate (IP6) has been known for ~20 years to promote the in vitro assembly of HIV-1 into immature virus-like particles. However, the molecular details underlying this effect have been determined only recently, with the identification of the IP6 binding site in the immature Gag lattice. IP6 also promotes formation of the mature capsid protein (CA) lattice via a second IP6 binding site, and enhances core stability, creating a favorable environment for reverse transcription. IP6 also enhances assembly of other retroviruses, from both the Lentivirus and the Alpharetrovirus genera. These findings suggest that IP6 may have a conserved function throughout the family Retroviridae. Here, we discuss the different steps in the viral life cycle that are influenced by IP6, and describe in detail how IP6 interacts with the immature and mature lattices of different retroviruses.
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45
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Li S. Cryo-electron tomography of enveloped viruses. Trends Biochem Sci 2021; 47:173-186. [PMID: 34511334 DOI: 10.1016/j.tibs.2021.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/12/2021] [Accepted: 08/18/2021] [Indexed: 10/20/2022]
Abstract
Viruses are macromolecular machineries that hijack cellular metabolism for replication. Enveloped viruses comprise a large variety of RNA and DNA viruses, many of which are notorious human or animal pathogens. Despite their importance, the presence of lipid bilayers in their assembly has made most enveloped viruses too pleomorphic to be reconstructed as a whole by traditional structural biology methods. Furthermore, structural biology of the viral lifecycle was hindered by the sample thickness. Here, I review the recent advances in the applications of cryo-electron tomography (cryo-ET) on enveloped viral structures and intracellular viral activities.
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Affiliation(s)
- Sai Li
- School of Life Sciences, Tsinghua University, Beijing 100084, China; Beijing Advanced Innovation Center for Structural Biology and Frontier Research Center for Biological Structure, Tsinghua University, Beijing 100084, China; Tsinghua-Peking Center for Life Sciences, Tsinghua University, Beijing 100084, China.
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46
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Affiliation(s)
- Yuta Hikichi
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA
| | - Eric O Freed
- Virus-Cell Interaction Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, MD, USA.
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47
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Structural determinants of virion assembly and release in the C-terminus of the M-PMV capsid protein. J Virol 2021; 95:e0061521. [PMID: 34287037 DOI: 10.1128/jvi.00615-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The transition from an immature to a fully infectious mature retrovirus particle is associated with molecular switches that trigger dramatic conformational changes in the structure of the Gag proteins. A dominant maturation switch that stabilizes the immature capsid lattice is located downstream of the capsid (CA) protein in many retroviral Gags. The HIV-1 Gag contains a stretch of five amino acid residues termed the 'clasp motif', important for the organization of the hexameric subunits that provide stability to the overall immature HIV-1 shell. Sequence alignment of the CA C-terminal domains (CTDs) of the HIV-1 and Mason-Pfizer Monkey Virus (M-PMV) highlighted a spacer-like domain in M-PMV that may provide comparable function. The importance of the sequences spanning the CA-NC cleavage has been demonstrated by mutagenesis, but the specific requirements for the clasp motif in several steps of M-PMV particle assembly and maturation have not been determined in detail. In the present study we report an examination of the role of the clasp motif in the M-PMV life cycle. We generated a series of M-PMV Gag mutants and assayed for assembly of the recombinant protein in vitro, and for the assembly, maturation, release, genomic RNA packaging, and infectivity of the mutant virus in vivo. The mutants revealed major defects in virion assembly and release in 293T and HeLa cells, and even larger defects in infectivity. Our data identifies the clasp motif as a fundamental contributor to CA-CTD interactions necessary for efficient viral infection. Importance The C-terminal domain of the capsid protein of many retroviruses has been shown to be critical for virion assembly and maturation, but the functions of this region of M-PMV are uncertain. We show that a short 'clasp' motif in the capsid domain of the M-PMV Gag protein plays a key role in M-PMV virion assembly, genome packaging, and infectivity.
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Structure of the mature Rous sarcoma virus lattice reveals a role for IP6 in the formation of the capsid hexamer. Nat Commun 2021; 12:3226. [PMID: 34050170 PMCID: PMC8163826 DOI: 10.1038/s41467-021-23506-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Accepted: 05/03/2021] [Indexed: 02/08/2023] Open
Abstract
Inositol hexakisphosphate (IP6) is an assembly cofactor for HIV-1. We report here that IP6 is also used for assembly of Rous sarcoma virus (RSV), a retrovirus from a different genus. IP6 is ~100-fold more potent at promoting RSV mature capsid protein (CA) assembly than observed for HIV-1 and removal of IP6 in cells reduces infectivity by 100-fold. Here, visualized by cryo-electron tomography and subtomogram averaging, mature capsid-like particles show an IP6-like density in the CA hexamer, coordinated by rings of six lysines and six arginines. Phosphate and IP6 have opposing effects on CA in vitro assembly, inducing formation of T = 1 icosahedrons and tubes, respectively, implying that phosphate promotes pentamer and IP6 hexamer formation. Subtomogram averaging and classification optimized for analysis of pleomorphic retrovirus particles reveal that the heterogeneity of mature RSV CA polyhedrons results from an unexpected, intrinsic CA hexamer flexibility. In contrast, the CA pentamer forms rigid units organizing the local architecture. These different features of hexamers and pentamers determine the structural mechanism to form CA polyhedrons of variable shape in mature RSV particles.
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Immature HIV-1 assembles from Gag dimers leaving partial hexamers at lattice edges as potential substrates for proteolytic maturation. Proc Natl Acad Sci U S A 2021; 118:2020054118. [PMID: 33397805 PMCID: PMC7826355 DOI: 10.1073/pnas.2020054118] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
HIV-1 particle assembly is driven by the viral Gag protein, which oligomerizes into a hexameric array on the inner surface of the viral envelope, forming a truncated spherical lattice containing large and small gaps. Gag is then cut by the viral protease, disassembles, and rearranges to form the mature, infectious virus. Here, we present structures and molecular dynamics simulations of the edges of the immature Gag lattice. Our analysis shows that Gag dimers are the basic assembly unit of the HIV-1 particle, lattice edges are partial hexamers, and partial hexamers are prone to structural changes allowing protease to cut Gag. These findings provide insights into assembly of the immature virus, its structure, and how it disassembles during maturation. The CA (capsid) domain of immature HIV-1 Gag and the adjacent spacer peptide 1 (SP1) play a key role in viral assembly by forming a lattice of CA hexamers, which adapts to viral envelope curvature by incorporating small lattice defects and a large gap at the site of budding. This lattice is stabilized by intrahexameric and interhexameric CA-CA interactions, which are important in regulating viral assembly and maturation. We applied subtomogram averaging and classification to determine the oligomerization state of CA at lattice edges and found that CA forms partial hexamers. These structures reveal the network of interactions formed by CA-SP1 at the lattice edge. We also performed atomistic molecular dynamics simulations of CA-CA interactions stabilizing the immature lattice and partial CA-SP1 helical bundles. Free energy calculations reveal increased propensity for helix-to-coil transitions in partial hexamers compared to complete six-helix bundles. Taken together, these results suggest that the CA dimer is the basic unit of lattice assembly, partial hexamers exist at lattice edges, these are in a helix-coil dynamic equilibrium, and partial helical bundles are more likely to unfold, representing potential sites for HIV-1 maturation initiation.
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Perilla JR, Hadden-Perilla JA, Gronenborn AM, Polenova T. Integrative structural biology of HIV-1 capsid protein assemblies: combining experiment and computation. Curr Opin Virol 2021; 48:57-64. [PMID: 33901736 DOI: 10.1016/j.coviro.2021.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/11/2021] [Accepted: 03/20/2021] [Indexed: 12/31/2022]
Abstract
HIV-1 is the causative agent of acquired immunodeficiency syndrome (AIDS), a global pandemic that has claimed 32.7 million lives since 1981. Despite decades of research, there is no cure for the disease, with 38 million people currently infected with HIV. Attractive therapeutic targets for drug development are mature HIV-1 capsids, immature Gag polyprotein assemblies, and Gag maturation intermediates, although their complex architectures, pleomorphism, and dynamics render these assemblies challenging for structural biology. The recent development of integrative approaches, combining experimental and computational methods has enabled atomic-level characterization of structures and dynamics of capsid and Gag assemblies, and revealed their interactions with small-molecule inhibitors and host factors. These structures provide important insights that will guide the development of capsid and maturation inhibitors.
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Affiliation(s)
- Juan R Perilla
- University of Delaware, Department of Chemistry and Biochemistry, Newark, DE, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States
| | - Jodi A Hadden-Perilla
- University of Delaware, Department of Chemistry and Biochemistry, Newark, DE, United States
| | - Angela M Gronenborn
- Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States; Department of Structural Biology, University of Pittsburgh School of Medicine, 3501 Fifth Ave., Pittsburgh, PA 15261, United States.
| | - Tatyana Polenova
- University of Delaware, Department of Chemistry and Biochemistry, Newark, DE, United States; Pittsburgh Center for HIV Protein Interactions, University of Pittsburgh School of Medicine, Pittsburgh, PA, United States.
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