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Reinhardt SCM, Masullo LA, Baudrexel I, Steen PR, Kowalewski R, Eklund AS, Strauss S, Unterauer EM, Schlichthaerle T, Strauss MT, Klein C, Jungmann R. Ångström-resolution fluorescence microscopy. Nature 2023; 617:711-716. [PMID: 37225882 PMCID: PMC10208979 DOI: 10.1038/s41586-023-05925-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 03/07/2023] [Indexed: 05/26/2023]
Abstract
Fluorescence microscopy, with its molecular specificity, is one of the major characterization methods used in the life sciences to understand complex biological systems. Super-resolution approaches1-6 can achieve resolution in cells in the range of 15 to 20 nm, but interactions between individual biomolecules occur at length scales below 10 nm and characterization of intramolecular structure requires Ångström resolution. State-of-the-art super-resolution implementations7-14 have demonstrated spatial resolutions down to 5 nm and localization precisions of 1 nm under certain in vitro conditions. However, such resolutions do not directly translate to experiments in cells, and Ångström resolution has not been demonstrated to date. Here we introdue a DNA-barcoding method, resolution enhancement by sequential imaging (RESI), that improves the resolution of fluorescence microscopy down to the Ångström scale using off-the-shelf fluorescence microscopy hardware and reagents. By sequentially imaging sparse target subsets at moderate spatial resolutions of >15 nm, we demonstrate that single-protein resolution can be achieved for biomolecules in whole intact cells. Furthermore, we experimentally resolve the DNA backbone distance of single bases in DNA origami with Ångström resolution. We use our method in a proof-of-principle demonstration to map the molecular arrangement of the immunotherapy target CD20 in situ in untreated and drug-treated cells, which opens possibilities for assessing the molecular mechanisms of targeted immunotherapy. These observations demonstrate that, by enabling intramolecular imaging under ambient conditions in whole intact cells, RESI closes the gap between super-resolution microscopy and structural biology studies and thus delivers information key to understanding complex biological systems.
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Affiliation(s)
- Susanne C M Reinhardt
- Max Planck Institute of Biochemistry, Planegg, Germany
- Faculty of Physics and Center for NanoScience, Ludwig Maximilian University, Munich, Germany
| | | | - Isabelle Baudrexel
- Max Planck Institute of Biochemistry, Planegg, Germany
- Department of Chemistry and Biochemistry, Ludwig Maximilian University, Munich, Germany
| | - Philipp R Steen
- Max Planck Institute of Biochemistry, Planegg, Germany
- Faculty of Physics and Center for NanoScience, Ludwig Maximilian University, Munich, Germany
| | - Rafal Kowalewski
- Max Planck Institute of Biochemistry, Planegg, Germany
- Faculty of Physics and Center for NanoScience, Ludwig Maximilian University, Munich, Germany
| | - Alexandra S Eklund
- Max Planck Institute of Biochemistry, Planegg, Germany
- Department of Chemistry and Biochemistry, Ludwig Maximilian University, Munich, Germany
| | - Sebastian Strauss
- Max Planck Institute of Biochemistry, Planegg, Germany
- Faculty of Physics and Center for NanoScience, Ludwig Maximilian University, Munich, Germany
| | - Eduard M Unterauer
- Max Planck Institute of Biochemistry, Planegg, Germany
- Faculty of Physics and Center for NanoScience, Ludwig Maximilian University, Munich, Germany
| | - Thomas Schlichthaerle
- Max Planck Institute of Biochemistry, Planegg, Germany
- Faculty of Physics and Center for NanoScience, Ludwig Maximilian University, Munich, Germany
| | - Maximilian T Strauss
- Max Planck Institute of Biochemistry, Planegg, Germany
- Faculty of Physics and Center for NanoScience, Ludwig Maximilian University, Munich, Germany
| | - Christian Klein
- Department of Chemistry and Biochemistry, Ludwig Maximilian University, Munich, Germany
- Roche Innovation Center Zurich, Roche Pharma Research and Early Development, Schlieren, Switzerland
| | - Ralf Jungmann
- Max Planck Institute of Biochemistry, Planegg, Germany.
- Faculty of Physics and Center for NanoScience, Ludwig Maximilian University, Munich, Germany.
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Ferapontov A, Omer M, Baudrexel I, Nielsen JS, Dupont DM, Juul-Madsen K, Steen P, Eklund AS, Thiel S, Vorup-Jensen T, Jungmann R, Kjems J, Degn SE. Antigen footprint governs activation of the B cell receptor. Nat Commun 2023; 14:976. [PMID: 36813795 PMCID: PMC9947222 DOI: 10.1038/s41467-023-36672-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 02/10/2023] [Indexed: 02/24/2023] Open
Abstract
Antigen binding by B cell receptors (BCR) on cognate B cells elicits a response that eventually leads to production of antibodies. However, it is unclear what the distribution of BCRs is on the naïve B cell and how antigen binding triggers the first step in BCR signaling. Using DNA-PAINT super-resolution microscopy, we find that most BCRs are present as monomers, dimers, or loosely associated clusters on resting B cells, with a nearest-neighbor inter-Fab distance of 20-30 nm. We leverage a Holliday junction nanoscaffold to engineer monodisperse model antigens with precision-controlled affinity and valency, and find that the antigen exerts agonistic effects on the BCR as a function of increasing affinity and avidity. Monovalent macromolecular antigens can activate the BCR at high concentrations, whereas micromolecular antigens cannot, demonstrating that antigen binding does not directly drive activation. Based on this, we propose a BCR activation model determined by the antigen footprint.
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Affiliation(s)
- Alexey Ferapontov
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark.,Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark
| | - Marjan Omer
- Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark.,Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C, Denmark
| | - Isabelle Baudrexel
- Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark.,Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jesper Sejrup Nielsen
- Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark.,Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C, Denmark
| | - Daniel Miotto Dupont
- Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark.,Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C, Denmark
| | | | - Philipp Steen
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Faculty of Physics and Center for Nanoscience, Ludwig Maximilian University, Munich, Munich, Germany
| | - Alexandra S Eklund
- Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark.,Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Steffen Thiel
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark.,Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark
| | | | - Ralf Jungmann
- Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark.,Max Planck Institute of Biochemistry, Martinsried, Germany.,Faculty of Physics and Center for Nanoscience, Ludwig Maximilian University, Munich, Munich, Germany
| | - Jørgen Kjems
- Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark.,Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C, Denmark
| | - Søren Egedal Degn
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark. .,Center for Cellular Signal Patterns (CellPAT), Aarhus University, Aarhus C, Denmark.
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