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Gentner C, Rogez B, Robert HML, Aggoun A, Tessier G, Bon P, Berto P. Enhanced Quantitative Wavefront Imaging for Nano-Object Characterization. ACS NANO 2024. [PMID: 38981602 DOI: 10.1021/acsnano.4c05152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/11/2024]
Abstract
Quantitative phase imaging enables precise and label-free characterizations of individual nano-objects within a large volume, without a priori knowledge of the sample or imaging system. While emerging common path implementations are simple enough to promise a broad dissemination, their phase sensitivity still falls short of precisely estimating the mass or polarizability of vesicles, viruses, or nanoparticles in single-shot acquisitions. In this paper, we revisit the Zernike filtering concept, originally crafted for intensity-only detectors, with the aim of adapting it to wavefront imaging. We demonstrate, through numerical simulation and experiments based on high-resolution wavefront sensing, that a simple Fourier-plane add-on can significantly enhance phase sensitivity for subdiffraction objects─achieving over an order of magnitude increase (×12)─while allowing the quantitative retrieval of both intensity and phase. This advancement allows for more precise nano-object detection and metrology.
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Affiliation(s)
- Clémence Gentner
- Institut de la Vision, Sorbonne Université, CNRS-UMR 7210, Inserm-UMR S968, Paris 75012, France
| | - Benoit Rogez
- Institut de la Vision, Sorbonne Université, CNRS-UMR 7210, Inserm-UMR S968, Paris 75012, France
- L2n, Université de technologie de Troyes, CNRS-UMR 7076, Troyes 10004, France
| | - Hadrien M L Robert
- Institut de la Vision, Sorbonne Université, CNRS-UMR 7210, Inserm-UMR S968, Paris 75012, France
| | - Anis Aggoun
- Institut de la Vision, Sorbonne Université, CNRS-UMR 7210, Inserm-UMR S968, Paris 75012, France
| | - Gilles Tessier
- Institut de la Vision, Sorbonne Université, CNRS-UMR 7210, Inserm-UMR S968, Paris 75012, France
| | - Pierre Bon
- Université de Limoges, CNRS, XLIM, UMR 7252, Limoges 87000, France
| | - Pascal Berto
- Institut de la Vision, Sorbonne Université, CNRS-UMR 7210, Inserm-UMR S968, Paris 75012, France
- Université Paris Cité, Paris 75006, France
- Institut Universitaire de France (IUF), Paris 75231, France
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Martin MF, Bonaventure B, McCray NE, Peersen OB, Rozen-Gagnon K, Stapleford KA. Distinct chikungunya virus polymerase palm subdomains contribute to virus replication and virion assembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.15.575630. [PMID: 38293111 PMCID: PMC10827052 DOI: 10.1101/2024.01.15.575630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Alphaviruses encode an error-prone RNA-dependent RNA polymerase (RdRp), nsP4, required for genome synthesis, yet how the RdRp functions in the complete alphavirus life cycle is not well-defined. Previous work using chikungunya virus (CHIKV) has established the importance of the nsP4 residue cysteine 483 in maintaining viral genetic fidelity. Given the location of residue C483 in the nsP4 palm domain, we hypothesized that other residues within this domain and surrounding subdomains would also contribute to polymerase function. To test this hypothesis, we designed a panel of nsP4 variants via homology modeling based on the Coxsackievirus B3 3 polymerase. We rescued each variant in both mammalian and mosquito cells and discovered that the palm domain and ring finger subdomain contribute to polymerase host-specific replication and genetic stability. Surprisingly, in mosquito cells, these variants in the ring finger and palm domain were replication competent and produced viral structural proteins, but they were unable to produce infectious progeny, indicating a yet uncharacterized role for the polymerase in viral assembly. Finally, we have identified additional residues in the nsP4 palm domain that influence the genetic diversity of the viral progeny, potentially via an alteration in NTP binding and/or discrimination by the polymerase. Taken together, these studies highlight that distinct nsP4 subdomains regulate multiple processes of the alphavirus life cycle, placing nsP4 in a central role during the switch from RNA synthesis to packaging and assembly.
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Affiliation(s)
- Marie-France Martin
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Boris Bonaventure
- Department of Microbiology, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Nia E. McCray
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
| | - Olve B. Peersen
- Department of Biochemistry & Molecular Biology, Colorado State University, Fort Collins, CO, USA
| | | | - Kenneth A. Stapleford
- Department of Microbiology, New York University Grossman School of Medicine, New York, New York, USA
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Dibsy R, Inamdar K, Favard C, Muriaux D. Visualizing HIV-1 Assembly at the T-Cell Plasma Membrane Using Single-Molecule Localization Microscopy. Methods Mol Biol 2024; 2807:61-76. [PMID: 38743221 DOI: 10.1007/978-1-0716-3862-0_5] [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: 05/16/2024]
Abstract
The 20-year revolution in optical fluorescence microscopy, supported by the optimization of both spatial resolution and timely acquisition, allows the visualization of nanoscaled objects in cell biology. Currently, the use of a recent generation of super-resolution fluorescence microscope coupled with improved fluorescent probes gives the possibility to study the replicative cycle of viruses in living cells, at the single-virus particle or protein level. Here, we highlight the protocol for visualizing HIV-1 Gag assembly at the host T-cell plasma membrane using super-resolution light microscopy. Total internal reflection fluorescence microscopy (TIRF-M) coupled with single-molecule localization microscopy (SMLM) enables the detection and characterization of the assembly of viral proteins at the plasma membrane of infected host cells at the single protein level. Here, we describe the TIRF equipment, the T-cell culture for HIV-1, the sample preparation for single-molecule localization microscopies such as PALM and STORM, acquisition protocols, and Gag assembling cluster analysis.
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Affiliation(s)
- Rayane Dibsy
- CNRS, University of Montpellier, Institut de Recherche en Infectiologie de Montpellier - IRIM, UMR9004, Montpellier, France
| | - Kaushik Inamdar
- CNRS, University of Montpellier, Institut de Recherche en Infectiologie de Montpellier - IRIM, UMR9004, Montpellier, France
| | - Cyril Favard
- CNRS, University of Montpellier, Institut de Recherche en Infectiologie de Montpellier - IRIM, UMR9004, Montpellier, France
| | - Delphine Muriaux
- CNRS, University of Montpellier, Institut de Recherche en Infectiologie de Montpellier - IRIM, UMR9004, Montpellier, France.
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