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Kephart SM, Hom N, Lee KK. Visualizing intermediate stages of viral membrane fusion by cryo-electron tomography. Trends Biochem Sci 2024; 49:916-931. [PMID: 39054240 PMCID: PMC11455608 DOI: 10.1016/j.tibs.2024.06.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 06/07/2024] [Accepted: 06/18/2024] [Indexed: 07/27/2024]
Abstract
Protein-mediated membrane fusion is the dynamic process where specialized protein machinery undergoes dramatic conformational changes that drive two membrane bilayers together, leading to lipid mixing and opening of a fusion pore between previously separate membrane-bound compartments. Membrane fusion is an essential stage of enveloped virus entry that results in viral genome delivery into host cells. Recent studies applying cryo-electron microscopy techniques in a time-resolved fashion provide unprecedented glimpses into the interaction of viral fusion proteins and membranes, revealing fusion intermediate states from the initiation of fusion to release of the viral genome. In combination with complementary structural, biophysical, and computation modeling approaches, these advances are shedding new light on the mechanics and dynamics of protein-mediated membrane fusion.
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Affiliation(s)
- Sally M Kephart
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA
| | - Nancy Hom
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA
| | - Kelly K Lee
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, USA; Biological Structure Physics and Design Graduate Program, University of Washington, Seattle, WA, USA.
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Noble AJ, de Marco A. Cryo-focused ion beam for in situ structural biology: State of the art, challenges, and perspectives. Curr Opin Struct Biol 2024; 87:102864. [PMID: 38901373 DOI: 10.1016/j.sbi.2024.102864] [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: 01/29/2024] [Revised: 05/24/2024] [Accepted: 05/26/2024] [Indexed: 06/22/2024]
Abstract
Cryogenic-focused ion beam (cryo-FIB) instruments became essential for high-resolution imaging in cryo-preserved cells and tissues. Cryo-FIBs use accelerated ions to thin samples that would otherwise be too thick for cryo-electron microscopy (cryo-EM). This allows visualizing cellular ultrastructures in near-native frozen hydrated states. This review describes the current state-of-the-art capabilities of cryo-FIB technology and its applications in structural cell and tissue biology. We discuss recent advances in instrumentation, imaging modalities, automation, sample preparation protocols, and targeting techniques. We outline remaining challenges and future directions to make cryo-FIB more precise, enable higher throughput, and be widely accessible. Further improvements in targeting, efficiency, robust sample preparation, emerging ion sources, automation, and downstream electron tomography have the potential to reveal intricate molecular architectures across length scales inside cells and tissues. Cryo-FIB is poised to become an indispensable tool for preparing native biological systems in situ for high-resolution 3D structural analysis.
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Affiliation(s)
- Alex J Noble
- Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Avenue New York, NY, 10027, USA. https://twitter.com/alexjamesnoble
| | - Alex de Marco
- Simons Electron Microscopy Center, New York Structural Biology Center, 89 Convent Avenue New York, NY, 10027, USA.
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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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Galaz-Montoya JG. The advent of preventive high-resolution structural histopathology by artificial-intelligence-powered cryogenic electron tomography. Front Mol Biosci 2024; 11:1390858. [PMID: 38868297 PMCID: PMC11167099 DOI: 10.3389/fmolb.2024.1390858] [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: 02/24/2024] [Accepted: 05/08/2024] [Indexed: 06/14/2024] Open
Abstract
Advances in cryogenic electron microscopy (cryoEM) single particle analysis have revolutionized structural biology by facilitating the in vitro determination of atomic- and near-atomic-resolution structures for fully hydrated macromolecular complexes exhibiting compositional and conformational heterogeneity across a wide range of sizes. Cryogenic electron tomography (cryoET) and subtomogram averaging are rapidly progressing toward delivering similar insights for macromolecular complexes in situ, without requiring tags or harsh biochemical purification. Furthermore, cryoET enables the visualization of cellular and tissue phenotypes directly at molecular, nanometric resolution without chemical fixation or staining artifacts. This forward-looking review covers recent developments in cryoEM/ET and related technologies such as cryogenic focused ion beam milling scanning electron microscopy and correlative light microscopy, increasingly enhanced and supported by artificial intelligence algorithms. Their potential application to emerging concepts is discussed, primarily the prospect of complementing medical histopathology analysis. Machine learning solutions are poised to address current challenges posed by "big data" in cryoET of tissues, cells, and macromolecules, offering the promise of enabling novel, quantitative insights into disease processes, which may translate into the clinic and lead to improved diagnostics and targeted therapeutics.
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Affiliation(s)
- Jesús G. Galaz-Montoya
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA, United States
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Asarnow D, Becker VA, Bobe D, Dubbledam C, Johnston JD, Kopylov M, Lavoie NR, Li Q, Mattingly JM, Mendez JH, Paraan M, Turner J, Upadhye V, Walsh RM, Gupta M, Eng ET. Recent advances in infectious disease research using cryo-electron tomography. Front Mol Biosci 2024; 10:1296941. [PMID: 38288336 PMCID: PMC10822977 DOI: 10.3389/fmolb.2023.1296941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 12/07/2023] [Indexed: 01/31/2024] Open
Abstract
With the increasing spread of infectious diseases worldwide, there is an urgent need for novel strategies to combat them. Cryogenic sample electron microscopy (cryo-EM) techniques, particularly electron tomography (cryo-ET), have revolutionized the field of infectious disease research by enabling multiscale observation of biological structures in a near-native state. This review highlights the recent advances in infectious disease research using cryo-ET and discusses the potential of this structural biology technique to help discover mechanisms of infection in native environments and guiding in the right direction for future drug discovery.
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Affiliation(s)
- Daniel Asarnow
- Department of Biochemistry, University of Washington, Seattle, WA, United States
| | - Vada A. Becker
- Department of Medicinal Chemistry, University of Washington, Seattle, WA, United States
| | - Daija Bobe
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, United States
| | - Charlie Dubbledam
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, United States
| | - Jake D. Johnston
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, United States
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, United States
| | - Mykhailo Kopylov
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, United States
| | - Nathalie R. Lavoie
- Department of Molecular Biology and Microbiology, School of Medicine, Tufts University, Boston, MA, United States
| | - Qiuye Li
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Jacob M. Mattingly
- Department of Chemistry, College of Arts and Sciences, Emory University, Atlanta, GA, United States
| | - Joshua H. Mendez
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, United States
| | - Mohammadreza Paraan
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, United States
| | - Jack Turner
- European Bioinformatics Institute (EMBL-EBI), Cambridge, United Kingdom
| | - Viraj Upadhye
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, United States
| | - Richard M. Walsh
- Harvard Cryo-Electron Microscopy Center for Structural Biology and Harvard Medical School, Boston, MA, United States
| | - Meghna Gupta
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, United States
| | - Edward T. Eng
- Simons Electron Microscopy Center, New York Structural Biology Center, New York, NY, United States
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