1
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Bauda E, Gallet B, Moravcova J, Effantin G, Chan H, Novacek J, Jouneau PH, Rodrigues CDA, Schoehn G, Moriscot C, Morlot C. Ultrastructure of macromolecular assemblies contributing to bacterial spore resistance revealed by in situ cryo-electron tomography. Nat Commun 2024; 15:1376. [PMID: 38355696 PMCID: PMC10867305 DOI: 10.1038/s41467-024-45770-6] [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: 09/06/2023] [Accepted: 02/02/2024] [Indexed: 02/16/2024] Open
Abstract
Bacterial spores owe their incredible resistance capacities to molecular structures that protect the cell content from external aggressions. Among the determinants of resistance are the quaternary structure of the chromosome and an extracellular shell made of proteinaceous layers (the coat), the assembly of which remains poorly understood. Here, in situ cryo-electron tomography on lamellae generated by cryo-focused ion beam micromachining provides insights into the ultrastructural organization of Bacillus subtilis sporangia. The reconstructed tomograms reveal that early during sporulation, the chromosome in the forespore adopts a toroidal structure harboring 5.5-nm thick fibers. At the same stage, coat proteins at the surface of the forespore form a stack of amorphous or structured layers with distinct electron density, dimensions and organization. By analyzing mutant strains using cryo-electron tomography and transmission electron microscopy on resin sections, we distinguish seven nascent coat regions with different molecular properties, and propose a model for the contribution of coat morphogenetic proteins.
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Affiliation(s)
- Elda Bauda
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France
| | - Benoit Gallet
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France
| | - Jana Moravcova
- CEITEC-Central European Institute of Technology, Masaryk University, 62500, Brno, Czech Republic
| | | | - Helena Chan
- University of Technology Sydney, 2007, Ultimo, NSW, Australia
| | - Jiri Novacek
- CEITEC-Central European Institute of Technology, Masaryk University, 62500, Brno, Czech Republic
| | | | | | - Guy Schoehn
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France
| | | | - Cecile Morlot
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000, Grenoble, France.
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2
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Berkamp S, Daviran D, Smeets M, Caignard A, Jani RA, Sundermeyer P, Jonker C, Gerlach S, Hoffmann B, Lau K, Sachse C. Correlative Light and Electron Cryo-Microscopy Workflow Combining Micropatterning, Ice Shield, and an In-Chamber Fluorescence Light Microscope. Bio Protoc 2023; 13:e4901. [PMID: 38156035 PMCID: PMC10751236 DOI: 10.21769/bioprotoc.4901] [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: 08/10/2023] [Revised: 10/26/2023] [Accepted: 10/31/2023] [Indexed: 12/30/2023] Open
Abstract
In situ cryo-electron tomography (cryo-ET) is the most current, state-of-the-art technique to study cell machinery in its hydrated near-native state. The method provides ultrastructural details at sub-nanometer resolution for many components within the cellular context. Making use of recent advances in sample preparation techniques and combining this method with correlative light and electron microscopy (CLEM) approaches have enabled targeted molecular visualization. Nevertheless, the implementation has also added to the complexity of the workflow and introduced new obstacles in the way of streamlining and achieving high throughput, sample yield, and sample quality. Here, we report a detailed protocol by combining multiple newly available technologies to establish an integrated, high-throughput, optimized, and streamlined cryo-CLEM workflow for improved sample yield. Key features • PRIMO micropatterning allows precise cell positioning and maximum number of cell targets amenable to thinning with cryo focused-ion-beam-scanning electron microscopy. • CERES ice shield ensures that the lamellae remain free of ice contamination during the batch milling process. • METEOR in-chamber fluorescence microscope facilitates the targeted cryo focused-ion-beam (cryo FIB) milling of these targets. • Combining the three technologies into one cryo-CLEM workflow maximizes sample yield, throughput, and efficiency. Graphical overview.
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Affiliation(s)
- Sabrina Berkamp
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons, ER-C-3/Structural Biology, Forschungszentrum Jülich, Jülich, Germany
- Institute of Biological Information Processing, IBI-6: Structural Cell Biology, Forschungszentrum Jülich, Jülich, Germany
| | | | | | | | | | - Pia Sundermeyer
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons, ER-C-3/Structural Biology, Forschungszentrum Jülich, Jülich, Germany
- Institute of Biological Information Processing, IBI-6: Structural Cell Biology, Forschungszentrum Jülich, Jülich, Germany
| | | | - Sven Gerlach
- Institute of Biological Information Processing, IBI-2: Mechanobiology Forschungszentrum Jülich, Jülich, Germany
| | - Bernd Hoffmann
- Institute of Biological Information Processing, IBI-2: Mechanobiology Forschungszentrum Jülich, Jülich, Germany
| | | | - Carsten Sachse
- Ernst-Ruska Centre for Microscopy and Spectroscopy with Electrons, ER-C-3/Structural Biology, Forschungszentrum Jülich, Jülich, Germany
- Institute of Biological Information Processing, IBI-6: Structural Cell Biology, Forschungszentrum Jülich, Jülich, Germany
- Department of Biology, Heinrich Heine University, Düsseldorf, Germany
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3
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Mageswaran SK, Grotjahn DA, Zeng X, Barad BA, Medina M, Hoang MH, Dobro MJ, Chang YW, Xu M, Yang WY, Jensen GJ. Nanoscale details of mitochondrial constriction revealed by cryoelectron tomography. Biophys J 2023; 122:3768-3782. [PMID: 37533259 PMCID: PMC10541493 DOI: 10.1016/j.bpj.2023.07.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/14/2023] [Accepted: 07/31/2023] [Indexed: 08/04/2023] Open
Abstract
Mitochondria adapt to changing cellular environments, stress stimuli, and metabolic demands through dramatic morphological remodeling of their shape, and thus function. Such mitochondrial dynamics is often dependent on cytoskeletal filament interactions. However, the precise organization of these filamentous assemblies remains speculative. Here, we apply cryogenic electron tomography to directly image the nanoscale architecture of the cytoskeletal-membrane interactions involved in mitochondrial dynamics in response to damage. We induced mitochondrial damage via membrane depolarization, a cellular stress associated with mitochondrial fragmentation and mitophagy. We find that, in response to acute membrane depolarization, mammalian mitochondria predominantly organize into tubular morphology that abundantly displays constrictions. We observe long bundles of both unbranched actin and septin filaments enriched at these constrictions. We also observed septin-microtubule interactions at these sites and elsewhere, suggesting that these two filaments guide each other in the cytosolic space. Together, our results provide empirical parameters for the architecture of mitochondrial constriction factors to validate/refine existing models and inform the development of new ones.
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Affiliation(s)
- Shrawan Kumar Mageswaran
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California; Department of Biophysics and Biochemistry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Danielle Ann Grotjahn
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California; Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California.
| | - Xiangrui Zeng
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Benjamin Asher Barad
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California
| | - Michaela Medina
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California
| | - My Hanh Hoang
- Department of Biophysics and Biochemistry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Yi-Wei Chang
- Department of Biophysics and Biochemistry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Min Xu
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Wei Yuan Yang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California; Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah.
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4
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House KL, Pan L, O'Carroll DM, Xu S. Applications of scanning electron microscopy and focused ion beam milling in dental research. Eur J Oral Sci 2022; 130:e12853. [PMID: 35288994 DOI: 10.1111/eos.12853] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 01/06/2022] [Indexed: 12/15/2022]
Abstract
The abilities of scanning electron microscopy (SEM) and focused ion beam (FIB) milling for obtaining high-resolution images from top surfaces, cross-sectional surfaces, and even in three dimensions, are becoming increasingly important for imaging and analyzing tooth structures such as enamel and dentin. FIB was originally developed for material research in the semiconductor industry. However, use of SEM/FIB has been growing recently in dental research due to the versatility of dual platform instruments that can be used as a milling device to obtain low-artifact cross-sections of samples combined with high-resolution images. The advent of the SEM/FIB system and accessories may offer access to previously inaccessible length scales for characterizing tooth structures for dental research, opening exciting opportunities to address many central questions in dental research. New discoveries and fundamental breakthroughs in understanding are likely to follow. This review covers the applications, key findings, and future direction of SEM/FIB in dental research in morphology imaging, specimen preparation for transmission electron microscopy (TEM) analysis, and three-dimensional volume imaging using SEM/FIB tomography.
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Affiliation(s)
- Krystal L House
- Colgate Palmolive Company, Piscataway, New Jersey, USA.,Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA
| | - Long Pan
- Colgate Palmolive Company, Piscataway, New Jersey, USA
| | - Deirdre M O'Carroll
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA.,Department of Materials Science and Engineering, Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, USA
| | - Shiyou Xu
- Colgate Palmolive Company, Piscataway, New Jersey, USA
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5
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Yang JE, Larson MR, Sibert BS, Shrum S, Wright ER. CorRelator: Interactive software for real-time high precision cryo-correlative light and electron microscopy. J Struct Biol 2021; 213:107709. [PMID: 33610654 PMCID: PMC8601405 DOI: 10.1016/j.jsb.2021.107709] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 01/06/2021] [Accepted: 02/11/2021] [Indexed: 12/31/2022]
Abstract
Cryo-correlative light and electron microscopy (CLEM) is a technique that uses the spatiotemporal cues from fluorescence light microscopy (FLM) to investigate the high-resolution ultrastructure of biological samples by cryo-electron microscopy (cryo-EM). Cryo-CLEM provides advantages for identifying and distinguishing fluorescently labeled proteins, macromolecular complexes, and organelles from the cellular environment. Challenges remain on how correlation workflows and software tools are implemented on different microscope platforms to support automated cryo-EM data acquisition. Here, we present CorRelator: an open-source desktop application that bridges between cryo-FLM and real-time cryo-EM/ET automated data collection. CorRelator implements a pixel-coordinate-to-stage-position transformation for flexible, high accuracy on-the-fly and post-acquisition correlation. CorRelator can be integrated into cryo-CLEM workflows and easily adapted to standard fluorescence and transmission electron microscope (TEM) system configurations. CorRelator was benchmarked under live-cell and cryogenic conditions using several FLM and TEM instruments, demonstrating that CorRelator reliably supports real-time, automated correlative cryo-EM/ET acquisition, through a combination of software-aided and interactive alignment. CorRelator is a cross-platform software package featuring an intuitive Graphical User Interface (GUI) that guides the user through the correlation process. CorRelator source code is available at: https://github.com/wright-cemrc-projects/corr.
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Affiliation(s)
- Jie E Yang
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Cryo-Electron Microscopy Research Center, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States
| | - Matthew R Larson
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Cryo-Electron Microscopy Research Center, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States
| | - Bryan S Sibert
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Cryo-Electron Microscopy Research Center, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States
| | - Samantha Shrum
- Biophysics Graduate Program, University of Wisconsin, Madison, WI 53706, United States
| | - Elizabeth R Wright
- Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Cryo-Electron Microscopy Research Center, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States; Biophysics Graduate Program, University of Wisconsin, Madison, WI 53706, United States; Morgridge Institute for Research, Madison, WI, 53715, United States; Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin, Madison, WI 53706, United States.
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6
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Abstract
Cryo-electron microscopy (cryo-EM) has become the technique of choice for structural biology of macromolecular assemblies, after the 'resolution revolution' that has occurred in this field since 2012. With a suitable instrument, an appropriate electron detector and, last but not least, a cooperative sample it is now possible to collect images from which macromolecular structures can be determined to better than 2 Å resolution, where reliable atomic models can be built. By electron tomography and sub-tomogram averaging of cryo-samples, it is also possible to reconstruct subcellular structures to sub-nanometre resolution. This review describes the infrastructure that is needed to achieve this goal. Ideally, a cryo-EM lab will have a dedicated 300 kV electron microscope for data recording and a 200 kV instrument for screening cryo-samples, both with direct electron detectors, and at least one 120 kV EM for negative-stain screening at room temperature. Added to this should be ancillary equipment for specimen preparation, including a light microscope, carbon coater, plasma cleaner, glow discharge unit, a device for fast, robotic sample freezing, liquid nitrogen storage Dewars and a ready supply of clean liquid nitrogen. In practice, of course, the available budget will determine the number and types of microscopes and how elaborate the lab can be. The cryo-EM lab should be designed with adequate space for the electron microscopes and ancillary equipment, and should allow for sufficient storage space. Each electron microscope room should be connected to the image-processing computers by fibre-optic cables for the rapid transfer of large datasets. The cryo-EM lab should be overseen by a facility manager whose responsibilities include the day-to-day tasks to ensure that all microscopes are operating perfectly, organising service and repairs to minimise downtime, and controlling the budget. Large facilities will require additional support staff who help to oversee the operation of the facility and instruct new users.
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7
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Cheung YWS, Nam SE, Yip CK. Recent Advances in Single-Particle Electron Microscopic Analysis of Autophagy Degradation Machinery. Int J Mol Sci 2020; 21:E8051. [PMID: 33126766 PMCID: PMC7663694 DOI: 10.3390/ijms21218051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/25/2020] [Accepted: 10/25/2020] [Indexed: 12/31/2022] Open
Abstract
Macroautophagy (also known as autophagy) is a major pathway for selective degradation of misfolded/aggregated proteins and damaged organelles and non-selective degradation of cytoplasmic constituents for the generation of power during nutrient deprivation. The multi-step degradation process, from sequestering cytoplasmic cargo into the double-membrane vesicle termed autophagosome to the delivery of the autophagosome to the lysosome or lytic vacuole for breakdown, is mediated by the core autophagy machinery composed of multiple Atg proteins, as well as the divergent sequence family of selective autophagy receptors. Single-particle electron microscopy (EM) is a molecular imaging approach that has become an increasingly important tool in the structural characterization of proteins and macromolecular complexes. This article summarizes the contributions single-particle EM have made in advancing our understanding of the core autophagy machinery and selective autophagy receptors. We also discuss current technical challenges and roadblocks, as well as look into the future of single-particle EM in autophagy research.
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Affiliation(s)
| | | | - Calvin K. Yip
- Life Sciences Institute, Department of Biochemistry and Molecular Biology, The University of British Columbia, Vancouver, BC V6T 1Z3, Canada; (Y.W.S.C.); (S.-E.N.)
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8
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DE Winter DAM, Hsieh C, Marko M, Hayles MF. Cryo-FIB preparation of whole cells and tissue for cryo-TEM: use of high-pressure frozen specimens in tubes and planchets. J Microsc 2020; 281:125-137. [PMID: 32691851 PMCID: PMC7891314 DOI: 10.1111/jmi.12943] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/27/2020] [Accepted: 07/13/2020] [Indexed: 01/15/2023]
Abstract
The desire to study macromolecular complexes within their cellular context requires the ability to produce thin samples suitable for cryo‐TEM (cryo‐transmission electron microscope) investigations. In this paper, we discuss two similar approaches, which were developed independently in Utrecht (the Netherlands) and Albany (USA). The methods are particularly suitable for both tissue samples and cell suspensions prepared by a high‐pressure freezer (HPF). The workflows are explained with particular attention to potential pitfalls, while underlying principles are highlighted (‘why to do so’). Although both workflows function with a high success rate, full execution requires considerable experience and remains demanding. In addition, throughput is low. We hope to encourage other research groups worldwide to take on the challenge of improving the HPF– cryo‐FIB‐SEM – cryo‐TEM workflow. We discuss a number of suggestions to this end. Lay Description Life is ultimately dictated by the interaction of molecules in our bodies. Highly complex equipment is being used and further developed to study these interactions. The present paper describes methods to prepare small, very thin lamellae (area of 5×5 µm2, thickness 50–300 nm) of a cell to be studied in a cryo‐transmission electron microscope (cryo‐TEM). Special care must be taken to preserve the natural state of molecules in their natural environment. In the case of cryo‐TEM, the samples must be frozen and kept frozen to be compatible with the vacuum conditions in the microscope. The frozen condition imposes technical challenges which are addressed. Two approaches to obtain the thin lamellae are described. Both make use of a focused ion beam (FIB) microscope. The FIB allows removal of material with nanometre precision by focusing a beam of ionised atoms (gallium ions) onto the sample. Careful control of the FIB allows cutting out of the required thin lamellae. In both strategies, the thin lamellae remain attached to the original sample, and the ensemble of sample with section and sample holder is transported from the FIB microscope to the TEM while being kept frozen.
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Affiliation(s)
- D A M DE Winter
- Environmental Hydrogeology, Department of Earth Sciences, Utrecht University, Princetonlaan 8a, Utrecht, the Netherlands
| | - C Hsieh
- New York State Department of Health, Wadsworth Center, Empire State Plaza, Albany, New York, U.S.A
| | - M Marko
- New York State Department of Health, Wadsworth Center, Empire State Plaza, Albany, New York, U.S.A.,College of Nanoscale Science and Engineering, SUNY Polytechnic Institute, Albany, New York, U.S.A
| | - M F Hayles
- Cryo-FIB-SEM Technologist, Eindhoven, the Netherlands
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9
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Schaffer M, Pfeffer S, Mahamid J, Kleindiek S, Laugks T, Albert S, Engel BD, Rummel A, Smith AJ, Baumeister W, Plitzko JM. A cryo-FIB lift-out technique enables molecular-resolution cryo-ET within native Caenorhabditis elegans tissue. Nat Methods 2019; 16:757-762. [DOI: 10.1038/s41592-019-0497-5] [Citation(s) in RCA: 115] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 06/18/2019] [Indexed: 01/01/2023]
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10
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Pfeffer S, Mahamid J. Unravelling molecular complexity in structural cell biology. Curr Opin Struct Biol 2018; 52:111-118. [PMID: 30339965 DOI: 10.1016/j.sbi.2018.08.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 06/18/2018] [Accepted: 08/29/2018] [Indexed: 12/14/2022]
Abstract
Structural and cell biology have traditionally been separate disciplines and employed techniques that were well defined within the realm of either one or the other. Recent technological breakthroughs propelled electron microscopy of frozen hydrated specimens (cryo-EM) followed by single-particle analysis (SPA) to become a widely applied approach for obtaining near-atomic resolution structures of purified macromolecules. In parallel, ongoing developments on sample preparation are increasingly successful in bringing molecular views into cell biology. Cryo-electron tomography (cryo-ET) has so far served as the main imaging modality employed in these efforts towards obtaining three-dimensional (3D) volumes of heterogeneous molecular assemblies. We review the state-of-the-art in cryo-ET and computational processing and describe the current opportunities and frontiers for in-cell applications.
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Affiliation(s)
- Stefan Pfeffer
- Centre for Molecular Biology of Heidelberg University (ZMBH), 69120 Heidelberg, Germany
| | - Julia Mahamid
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
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11
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Noble JM, Lubieniecki J, Savitzky BH, Plitzko J, Engelhardt H, Baumeister W, Kourkoutis LF. Connectivity of centermost chromatophores in Rhodobacter sphaeroides bacteria. Mol Microbiol 2018; 109:812-825. [PMID: 29995992 DOI: 10.1111/mmi.14077] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 07/05/2018] [Accepted: 07/12/2018] [Indexed: 01/20/2023]
Abstract
The size of whole Rhodobacter sphaeroides prevents 3D visualization of centermost chromatophores in their native environment. This study combines cryo-focused ion beam milling with cryo-electron tomography to probe vesicle architecture both in situ and in 3D. Developing chromatophores are membrane-bound buds that remain in topological continuity with the cytoplasmic membrane and detach into vesicles when mature. Mature chromatophores closest to the cell wall are typically isolated vesicles, whereas centermost chromatophores are either linked to neighboring chromatophores or contain smaller, budding structures. Isolated chromatophores comprised a minority of centermost chromatophores. Connections between vesicles in growing bacteria are through ~10 nm-long, ~5 nm-wide linkers, and are thus physical rather than functional in terms of converting photons to ATP. In cells in the stationary phase, chromatophores fuse with neighboring vesicles, lose their spherical structure, and greatly increase in volume. The fusion and morphological changes seen in older bacteria are likely a consequence of the aging process, and are not representative of connectivity in healthy R. sphaeroides. Our results suggest that chromatophores can adopt either isolated or connected morphologies within a single bacterium. Revealing the organization of chromatophore vesicles throughout the cell is an important step in understanding the photosynthetic mechanisms in R. sphaeroides.
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Affiliation(s)
- Jade M Noble
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, USA
| | - Johann Lubieniecki
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | | | - Jürgen Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Harald Engelhardt
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Lena F Kourkoutis
- School of Applied and Engineering Physics, Cornell University, Ithaca, NY, USA.,Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, USA
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12
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Möbius W, Posthuma G. Sugar and ice: Immunoelectron microscopy using cryosections according to the Tokuyasu method. Tissue Cell 2018; 57:90-102. [PMID: 30201442 DOI: 10.1016/j.tice.2018.08.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/26/2018] [Accepted: 08/22/2018] [Indexed: 11/29/2022]
Abstract
Since the pioneering work of Kiyoteru Tokuyasu in the 70ths the use of thawed cryosections prepared according to the "Tokuyasu-method" for immunoelectron microscopy did not lose popularity. We owe this method a whole subcellular world described by discrete gold particles pointing at cargo, receptors and organelle markers on delicate images of the inner life of a cell. Here we explain the procedure of sample preparation, sectioning and immunolabeling in view of recent developments and the reasoning behind protocols including some historical perspective. Cryosections are prepared from chemically fixed and sucrose infiltrated samples and labeled with affinity probes and electron dense markers. These sections are ideal substrates for immunolabeling, since antigens are not exposed to organic solvent dehydration or masked by resin. Instead, the structures remain fully hydrated throughout the labeling procedure. Furthermore, target molecules inside dense intercellular structural elements, cells and organelles are accessible to antibodies from the section surface. For the validation of antibody specificity several approaches are recommended including knock-out tissue and reagent controls. Correlative light and electron microscopy strategies involving correlative probes are possible as well as correlation of live imaging with the underlying ultrastructure. By applying stereology, gold labeling can be quantified and evaluated for specificity.
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Affiliation(s)
- Wiebke Möbius
- Electron Microscopy Core Unit, Department of Neurogenetics, Max Planck Institute of Experimental Medicine, 37075, Göttingen, Germany; Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Göttingen, Germany.
| | - George Posthuma
- Department of Cell Biology, Cell Microscopy Core, University Medical Center Utrecht, Utrecht University, P.O. Box 85500, 3508 GA, Utrecht, The Netherlands.
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13
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Melia CE, Bharat TAM. Locating macromolecules and determining structures inside bacterial cells using electron cryotomography. BIOCHIMICA ET BIOPHYSICA ACTA. PROTEINS AND PROTEOMICS 2018; 1866:973-981. [PMID: 29908328 PMCID: PMC6052677 DOI: 10.1016/j.bbapap.2018.06.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 05/30/2018] [Accepted: 06/11/2018] [Indexed: 01/01/2023]
Abstract
Electron cryotomography (cryo-ET) is an imaging technique uniquely suited to the study of bacterial ultrastructure and cell biology. Recent years have seen a surge in structural and cell biology research on bacteria using cryo-ET. This research has driven major technical developments in the field, with applications emerging to address a wide range of biological questions. In this review, we explore the diversity of cryo-ET approaches used for structural and cellular microbiology, with a focus on in situ localization and structure determination of macromolecules. The first section describes strategies employed to locate target macromolecules within large cellular volumes. Next, we explore methods to study thick specimens by sample thinning. Finally, we review examples of macromolecular structure determination in a cellular context using cryo-ET. The examples outlined serve as powerful demonstrations of how the cellular location, structure, and function of any bacterial macromolecule of interest can be investigated using cryo-ET.
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Affiliation(s)
- Charlotte E Melia
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
| | - Tanmay A M Bharat
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom; Central Oxford Structural and Molecular Imaging Centre, University of Oxford, Oxford OX1 3RE, United Kingdom.
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14
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Robust workflow and instrumentation for cryo-focused ion beam milling of samples for electron cryotomography. Ultramicroscopy 2018; 190:1-11. [DOI: 10.1016/j.ultramic.2018.04.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 03/28/2018] [Accepted: 04/04/2018] [Indexed: 01/11/2023]
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15
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Medeiros JM, Böck D, Pilhofer M. Imaging bacteria inside their host by cryo-focused ion beam milling and electron cryotomography. Curr Opin Microbiol 2018; 43:62-68. [DOI: 10.1016/j.mib.2017.12.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 12/13/2017] [Accepted: 12/18/2017] [Indexed: 11/28/2022]
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16
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Engelhardt H, Bollschweiler D. Cryo-Electron Microscopy of Extremely Halophilic Microbes. J Microbiol Methods 2018. [DOI: 10.1016/bs.mim.2018.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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17
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Chen Y, Wang Z, Zhang J, Li L, Wan X, Sun F, Zhang F. Accelerating electron tomography reconstruction algorithm ICON with GPU. BIOPHYSICS REPORTS 2017; 3:36-42. [PMID: 28781999 PMCID: PMC5516007 DOI: 10.1007/s41048-017-0041-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/07/2017] [Indexed: 10/30/2022] Open
Abstract
Electron tomography (ET) plays an important role in studying in situ cell ultrastructure in three-dimensional space. Due to limited tilt angles, ET reconstruction always suffers from the "missing wedge" problem. With a validation procedure, iterative compressed-sensing optimized NUFFT reconstruction (ICON) demonstrates its power in the restoration of validated missing information for low SNR biological ET dataset. However, the huge computational demand has become a major problem for the application of ICON. In this work, we analyzed the framework of ICON and classified the operations of major steps of ICON reconstruction into three types. Accordingly, we designed parallel strategies and implemented them on graphics processing units (GPU) to generate a parallel program ICON-GPU. With high accuracy, ICON-GPU has a great acceleration compared to its CPU version, up to 83.7×, greatly relieving ICON's dependence on computing resource.
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Affiliation(s)
- Yu Chen
- Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190 China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Zihao Wang
- Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190 China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Jingrong Zhang
- Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190 China.,University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Lun Li
- Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190 China.,School of Mathematical Sciences, University of Chinese Academy of Sciences, Beijing, 100049 China
| | - Xiaohua Wan
- Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190 China
| | - Fei Sun
- University of Chinese Academy of Sciences, Beijing, 100049 China.,National Key Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China.,Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing, 100101 China
| | - Fa Zhang
- Key Laboratory of Intelligent Information Processing, Institute of Computing Technology, Chinese Academy of Sciences, Beijing, 100190 China
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18
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Clare DK, Siebert CA, Hecksel C, Hagen C, Mordhorst V, Grange M, Ashton AW, Walsh MA, Grünewald K, Saibil HR, Stuart DI, Zhang P. Electron Bio-Imaging Centre (eBIC): the UK national research facility for biological electron microscopy. Acta Crystallogr D Struct Biol 2017; 73:488-495. [PMID: 28580910 PMCID: PMC5458490 DOI: 10.1107/s2059798317007756] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Accepted: 05/24/2017] [Indexed: 12/13/2022] Open
Abstract
The recent resolution revolution in cryo-EM has led to a massive increase in demand for both time on high-end cryo-electron microscopes and access to cryo-electron microscopy expertise. In anticipation of this demand, eBIC was set up at Diamond Light Source in collaboration with Birkbeck College London and the University of Oxford, and funded by the Wellcome Trust, the UK Medical Research Council (MRC) and the Biotechnology and Biological Sciences Research Council (BBSRC) to provide access to high-end equipment through peer review. eBIC is currently in its start-up phase and began by offering time on a single FEI Titan Krios microscope equipped with the latest generation of direct electron detectors from two manufacturers. Here, the current status and modes of access for potential users of eBIC are outlined. In the first year of operation, 222 d of microscope time were delivered to external research groups, with 95 visits in total, of which 53 were from unique groups. The data collected have generated multiple high- to intermediate-resolution structures (2.8-8 Å), ten of which have been published. A second Krios microscope is now in operation, with two more due to come online in 2017. In the next phase of growth of eBIC, in addition to more microscope time, new data-collection strategies and sample-preparation techniques will be made available to external user groups. Finally, all raw data are archived, and a metadata catalogue and automated pipelines for data analysis are being developed.
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Affiliation(s)
- Daniel K. Clare
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - C. Alistair Siebert
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Corey Hecksel
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Christoph Hagen
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Valerie Mordhorst
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Michael Grange
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Alun W. Ashton
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
| | - Martin A. Walsh
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Research Complex at Harwell, Harwell Science and Innovation Campus, Didcot OX11 0FA, England
| | - Kay Grünewald
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Helen R. Saibil
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Crystallography, Institute for Structural and Molecular Biology, Birkbeck College, Malet Street, London WC1E 7HX, England
| | - David I. Stuart
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
| | - Peijun Zhang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, England
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, England
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19
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20
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Chen Y, Zhang Y, Zhang K, Deng Y, Wang S, Zhang F, Sun F. FIRT: Filtered iterative reconstruction technique with information restoration. J Struct Biol 2016; 195:49-61. [DOI: 10.1016/j.jsb.2016.04.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 04/27/2016] [Accepted: 04/28/2016] [Indexed: 12/31/2022]
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21
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Jasnin M, Ecke M, Baumeister W, Gerisch G. Actin Organization in Cells Responding to a Perforated Surface, Revealed by Live Imaging and Cryo-Electron Tomography. Structure 2016; 24:1031-43. [PMID: 27320835 DOI: 10.1016/j.str.2016.05.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/04/2016] [Accepted: 05/06/2016] [Indexed: 12/29/2022]
Abstract
In a 3D environment, motile cells accommodate their protruding and retracting activities to geometrical cues. Dictyostelium cells migrating on a perforated film explored its holes by forming actin rings around their border and extending protrusions through the free space. The response was initiated when an actin wave passed a hole, and the rings persisted only in the PIP3-rich territories surrounded by a wave. To reconstruct actin structures from cryo-electron tomograms, actin rings were identified by cryo-correlative light and electron microscopy, and thin wedges of relevant regions were obtained by cryo-focused ion-beam milling. Retracting stages were distinguished from protruding ones by the accumulation of myosin-II. Early actin rings consisted of filaments pointing upright from the membrane, entangled with a meshwork of filaments close to the membrane. Branches identified at later stages suggested that formin-based nucleation of filaments was followed by Arp2/3-mediated network stabilization, which prevented buckling of the force-generating filaments.
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Affiliation(s)
- Marion Jasnin
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Mary Ecke
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Wolfgang Baumeister
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
| | - Günther Gerisch
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
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22
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Metzger M, Konrad A, Skandary S, Ashraf I, Meixner AJ, Brecht M. Resolution enhancement for low-temperature scanning microscopy by cryo-immersion. OPTICS EXPRESS 2016; 24:13023-13032. [PMID: 27410321 DOI: 10.1364/oe.24.013023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Here we report a simple way to enhance the resolution of a confocal scanning microscope under cryogenic conditions. Using a microscope objective (MO) with high numerical aperture (NA = 1.25) and 1-propanol as an immersion fluid with low freezing temperature we were able to reach an imaging resolution at 160 K comparable to ambient conditions. The MO and the sample were both placed inside the inner chamber of the cryostat to reduce distortions induced by temperature gradients. The image quality of our commercially available MO was further enhanced by scanning the sample (sample scanning) in contrast to beam scanning. The ease of the whole procedure marks an essential step towards the development of cryo high-resolution microscopy and correlative light and electron cryo microscopy (cryoCLEM).
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23
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Zhang J, Ji G, Huang X, Xu W, Sun F. An improved cryo-FIB method for fabrication of frozen hydrated lamella. J Struct Biol 2016; 194:218-23. [DOI: 10.1016/j.jsb.2016.02.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 01/02/2016] [Accepted: 02/11/2016] [Indexed: 10/22/2022]
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24
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Bykov YS, Cortese M, Briggs JAG, Bartenschlager R. Correlative light and electron microscopy methods for the study of virus-cell interactions. FEBS Lett 2016; 590:1877-95. [PMID: 27008928 DOI: 10.1002/1873-3468.12153] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2016] [Revised: 03/09/2016] [Accepted: 03/22/2016] [Indexed: 12/21/2022]
Abstract
Electron microscopy (EM) is an invaluable tool to study the interactions of viruses with cells, and the ultrastructural changes induced in host cells by virus infection. Light microscopy (LM) is a complementary tool with the potential to locate rare events, label specific components, and obtain dynamic information. The combination of LM and EM in correlative light and electron microscopy (CLEM) is particularly powerful. It can be used to complement a static EM image with dynamic data from live imaging, identify the ultrastructure observed in LM, or, conversely, provide molecular specificity data for a known ultrastructure. Here, we describe methods and strategies for CLEM, discuss their advantages and limitations, and review applications of CLEM to study virus-host interactions.
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Affiliation(s)
- Yury S Bykov
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Mirko Cortese
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Germany
| | - John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Ralf Bartenschlager
- Department of Infectious Diseases, Molecular Virology, Heidelberg University, Germany
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25
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Oikonomou CM, Chang YW, Jensen GJ. A new view into prokaryotic cell biology from electron cryotomography. Nat Rev Microbiol 2016; 14:205-20. [PMID: 26923112 PMCID: PMC5551487 DOI: 10.1038/nrmicro.2016.7] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Electron cryotomography (ECT) enables intact cells to be visualized in 3D in an essentially native state to 'macromolecular' (∼4 nm) resolution, revealing the basic architectures of complete nanomachines and their arrangements in situ. Since its inception, ECT has advanced our understanding of many aspects of prokaryotic cell biology, from morphogenesis to subcellular compartmentalization and from metabolism to complex interspecies interactions. In this Review, we highlight how ECT has provided structural and mechanistic insights into the physiology of bacteria and archaea and discuss prospects for the future.
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Affiliation(s)
- Catherine M Oikonomou
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
| | - Yi-Wei Chang
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
| | - Grant J Jensen
- Howard Hughes Medical Institute; Division of Biology and Biological Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, California 91125, USA
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26
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Thompson RF, Walker M, Siebert CA, Muench SP, Ranson NA. An introduction to sample preparation and imaging by cryo-electron microscopy for structural biology. Methods 2016; 100:3-15. [PMID: 26931652 PMCID: PMC4854231 DOI: 10.1016/j.ymeth.2016.02.017] [Citation(s) in RCA: 148] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 02/11/2016] [Accepted: 02/25/2016] [Indexed: 11/22/2022] Open
Abstract
Transmission electron microscopy (EM) is a versatile technique that can be used to image biological specimens ranging from intact eukaryotic cells to individual proteins >150 kDa. There are several strategies for preparing samples for imaging by EM, including negative staining and cryogenic freezing. In the last few years, cryo-EM has undergone a ‘resolution revolution’, owing to both advances in imaging hardware, image processing software, and improvements in sample preparation, leading to growing number of researchers using cryo-EM as a research tool. However, cryo-EM is still a rapidly growing field, with unique challenges. Here, we summarise considerations for imaging of a range of specimens from macromolecular complexes to cells using EM.
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Affiliation(s)
- Rebecca F Thompson
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
| | - Matt Walker
- MLW Consulting, 11 Race Hill, Launceston, Cornwall PL15 9BB, United Kingdom
| | - C Alistair Siebert
- Electron Bio-Imaging Centre, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom
| | - Stephen P Muench
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Neil A Ranson
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom.
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27
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Abstract
A quiet revolution is under way in technologies used for nanoscale cellular imaging. Focused ion beams, previously restricted to the materials sciences and semiconductor fields, are rapidly becoming powerful tools for ultrastructural imaging of biological samples. Cell and tissue architecture, as preserved in plastic-embedded resin or in plunge-frozen form, can be investigated in three dimensions by scanning electron microscopy imaging of freshly created surfaces that result from the progressive removal of material using a focused ion beam. The focused ion beam can also be used as a sculpting tool to create specific specimen shapes such as lamellae or needles that can be analyzed further by transmission electron microscopy or by methods that probe chemical composition. Here we provide an in-depth primer to the application of focused ion beams in biology, including a guide to the practical aspects of using the technology, as well as selected examples of its contribution to the generation of new insights into subcellular architecture and mechanisms underlying host-pathogen interactions.
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28
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In Situ Cryo-Electron Tomography: A Post-Reductionist Approach to Structural Biology. J Mol Biol 2016; 428:332-343. [DOI: 10.1016/j.jmb.2015.09.030] [Citation(s) in RCA: 128] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/28/2015] [Accepted: 09/30/2015] [Indexed: 11/24/2022]
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29
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Strnad M, Elsterová J, Schrenková J, Vancová M, Rego ROM, Grubhoffer L, Nebesářová J. Correlative cryo-fluorescence and cryo-scanning electron microscopy as a straightforward tool to study host-pathogen interactions. Sci Rep 2015; 5:18029. [PMID: 26658551 PMCID: PMC4674872 DOI: 10.1038/srep18029] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 11/09/2015] [Indexed: 01/04/2023] Open
Abstract
Correlative light and electron microscopy is an imaging technique that enables identification and targeting of fluorescently tagged structures with subsequent imaging at near-to-nanometer resolution. We established a novel correlative cryo-fluorescence microscopy and cryo-scanning electron microscopy workflow, which enables imaging of the studied object of interest very close to its natural state, devoid of artifacts caused for instance by slow chemical fixation. This system was tested by investigating the interaction of the zoonotic bacterium Borrelia burgdorferi with two mammalian cell lines of neural origin in order to broaden our knowledge about the cell-association mechanisms that precedes the entry of the bacteria into the cell. This method appears to be an unprecedentedly fast (<3 hours), straightforward, and reliable solution to study the finer details of pathogen-host cell interactions and provides important insights into the complex and dynamic relationship between a pathogen and a host.
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Affiliation(s)
- Martin Strnad
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice CZ-37005, Czech Republic.,Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 1760, České Budějovice CZ-37005, Czech Republic
| | - Jana Elsterová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice CZ-37005, Czech Republic.,Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 1760, České Budějovice CZ-37005, Czech Republic.,Department of Virology, Veterinary Research Institute, Brno CZ-62100, Czech Republic
| | - Jana Schrenková
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice CZ-37005, Czech Republic.,Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 1760, České Budějovice CZ-37005, Czech Republic
| | - Marie Vancová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice CZ-37005, Czech Republic.,Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 1760, České Budějovice CZ-37005, Czech Republic
| | - Ryan O M Rego
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice CZ-37005, Czech Republic
| | - Libor Grubhoffer
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice CZ-37005, Czech Republic.,Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 1760, České Budějovice CZ-37005, Czech Republic
| | - Jana Nebesářová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, Branišovská 31, České Budějovice CZ-37005, Czech Republic.,Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 1760, České Budějovice CZ-37005, Czech Republic.,Faculty of Science, Charles University in Prague, Viničná 1594/7, Praha CZ-12800, Czech Republic
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30
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Frankl A, Mari M, Reggiori F. Electron microscopy for ultrastructural analysis and protein localization in Saccharomyces cerevisiae. MICROBIAL CELL 2015; 2:412-428. [PMID: 28357267 PMCID: PMC5349205 DOI: 10.15698/mic2015.11.237] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The yeast Saccharomyces cerevisiae is a key model system for studying of a multitude of cellular processes because of its amenability to genetics, molecular biology and biochemical procedures. Ultrastructural examinations of this organism, though, are traditionally difficult because of the presence of a thick cell wall and the high density of cytoplasmic proteins. A series of recent methodological and technical developments, however, has revived interest in morphological analyses of yeast (e.g. 123). Here we present a review of established and new methods, from sample preparation to imaging, for the ultrastructural analysis of S. cerevisiae. We include information for the use of different fixation methods, embedding procedures, approaches for contrast enhancement, and sample visualization techniques, with references to successful examples. The goal of this review is to guide researchers that want to investigate a particular process at the ultrastructural level in yeast by aiding in the selection of the most appropriate approach to visualize a specific structure or subcellular compartment.
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Affiliation(s)
- Andri Frankl
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Muriel Mari
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Fulvio Reggiori
- Department of Cell Biology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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31
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Cryo-focused-ion-beam applications in structural biology. Arch Biochem Biophys 2015; 581:122-30. [DOI: 10.1016/j.abb.2015.02.009] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 02/06/2015] [Accepted: 02/11/2015] [Indexed: 01/30/2023]
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32
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Abstract
We acquired molecular-resolution structures of the Golgi within its native cellular environment. Vitreous Chlamydomonas cells were thinned by cryo-focused ion beam milling and then visualized by cryo-electron tomography. These tomograms revealed structures within the Golgi cisternae that have not been seen before. Narrow trans-Golgi lumina were spanned by asymmetric membrane-associated protein arrays that had ∼6-nm lateral periodicity. Subtomogram averaging showed that the arrays may determine the narrow central spacing of the trans-Golgi cisternae through zipper-like interactions, thereby forcing cargo to the trans-Golgi periphery. Additionally, we observed dense granular aggregates within cisternae and intracisternal filament bundles associated with trans-Golgi buds. These native in situ structures provide new molecular insights into Golgi architecture and function.
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33
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Fontana J, Steven AC. Influenza virus-mediated membrane fusion: Structural insights from electron microscopy. Arch Biochem Biophys 2015; 581:86-97. [PMID: 25958107 DOI: 10.1016/j.abb.2015.04.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Revised: 04/21/2015] [Accepted: 04/27/2015] [Indexed: 12/26/2022]
Abstract
Influenza virus, the causative agent of flu, enters the host cell by endocytosis. The low pH encountered inside endosomes triggers conformational changes in the viral glycoprotein hemagglutinin (HA), that mediate fusion of the viral and cellular membranes. This releases the viral genome into the cytoplasm of the infected cell, establishing the onset of the replication cycle. To investigate the structural basis of HA-mediated membrane fusion, a number of techniques have been employed. These include X-ray crystallography, which has provided atomic models of the HA ectodomain in its initial (pre-fusion) state and of part of HA in its final (post-fusion) state. However, this left an information deficit concerning many other aspects of the fusion process. Electron microscopy (EM) approaches are helping to fill this void. For example, influenza virions at neutral pH have been imaged by cryo-EM and cryo-electron tomography (cryo-ET); thin section EM has shown that influenza viruses enter the cell by endocytosis; the large-scale structural changes in HA when virions are exposed to low pH (pre-fusion to post-fusion states) have been visualized by negative staining and cryo-EM; acidification also induces structural changes in the M1 matrix layer and its separation from the viral envelope; intermediate HA conformations between its pre- and post-fusion states have been detected by cryo-ET supplemented with subtomogram averaging; and fusion of influenza virions with liposomes has been visualized by cryo-ET. In this review, we survey EM-based contributions towards the characterization of influenza virus-mediated membrane fusion and anticipate the potential for future developments.
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Affiliation(s)
- Juan Fontana
- Laboratory of Structural Biology Research, National Institute of Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Alasdair C Steven
- Laboratory of Structural Biology Research, National Institute of Arthritis, Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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34
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Wagenknecht T, Hsieh C, Marko M. Skeletal Muscle Triad Junction Ultrastructure by Focused-Ion-Beam Milling of Muscle and Cryo-Electron Tomography. Eur J Transl Myol 2015; 25:4823. [PMID: 26913145 PMCID: PMC4748973 DOI: 10.4081/ejtm.2015.4823] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 01/09/2015] [Accepted: 01/15/2015] [Indexed: 11/23/2022] Open
Abstract
Cryo-electron tomography (cryo-ET) has emerged as perhaps the only practical technique for revealing nanometer-level three-dimensional structural details of subcellular macromolecular complexes in their native context, inside the cell. As currently practiced, the specimen should be 0.1-0.2 microns in thickness to achieve optimal resolution. Thus, application of cryo-ET to intact frozen (vitreous) tissues, such as skeletal muscle, requires that they be sectioned. Cryo-ultramicrotomy is notoriously difficult and artifact-prone when applied to frozen cells and tissue, but a new technique, focused ion beam milling (cryo-FIB), shows great promise for “thinning” frozen biological specimens. Here we describe our initial results in applying cryo-FIB and cryo-ET to triad junctions of skeletal muscle.
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Affiliation(s)
- Terence Wagenknecht
- New York State Department of Health, Wadsworth Cente, Empire State Plaza, Albany, NY, USA.,Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY, USA
| | - Chyongere Hsieh
- New York State Department of Health, Wadsworth Cente, Empire State Plaza, Albany, NY, USA
| | - Michael Marko
- New York State Department of Health, Wadsworth Cente, Empire State Plaza, Albany, NY, USA
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35
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Engel BD, Schaffer M, Kuhn Cuellar L, Villa E, Plitzko JM, Baumeister W. Native architecture of the Chlamydomonas chloroplast revealed by in situ cryo-electron tomography. eLife 2015; 4. [PMID: 25584625 PMCID: PMC4292175 DOI: 10.7554/elife.04889] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 12/08/2014] [Indexed: 12/19/2022] Open
Abstract
Chloroplast function is orchestrated by the organelle's intricate architecture. By combining cryo-focused ion beam milling of vitreous Chlamydomonas cells with cryo-electron tomography, we acquired three-dimensional structures of the chloroplast in its native state within the cell. Chloroplast envelope inner membrane invaginations were frequently found in close association with thylakoid tips, and the tips of multiple thylakoid stacks converged at dynamic sites on the chloroplast envelope, implicating lipid transport in thylakoid biogenesis. Subtomogram averaging and nearest neighbor analysis revealed that RuBisCO complexes were hexagonally packed within the pyrenoid, with ∼15 nm between their centers. Thylakoid stacks and the pyrenoid were connected by cylindrical pyrenoid tubules, physically bridging the sites of light-dependent photosynthesis and light-independent carbon fixation. Multiple parallel minitubules were bundled within each pyrenoid tubule, possibly serving as conduits for the targeted one-dimensional diffusion of small molecules such as ATP and sugars between the chloroplast stroma and the pyrenoid matrix. DOI:http://dx.doi.org/10.7554/eLife.04889.001 Many organisms can harvest light to produce their own energy through a process called photosynthesis. In plant and algal cells, photosynthesis takes place within the chloroplasts, which are compartments that contain stacks of structures called thylakoids. Inside the thylakoids, proteins absorb energy from light and convert it into biochemical energy that can be used by the cell. This energy then powers a series of reactions that result in carbon dioxide being incorporated into energy-rich sugars. The enzyme RuBisCO is essential for this process, and is believed to be the most abundant protein on Earth. In land plants, RuBisCO is found throughout the chloroplast, but in algae it is limited to a specialized area called the pyrenoid. Much of our current knowledge of chloroplast structure comes from transmission electron microscopy (TEM) images. However, the traditional methods used to prepare cells for TEM can damage their internal structures. Also, previous studies have focused primarily on the chloroplasts of land plants, even though aquatic organisms—including the alga Chlamydomonas—account for over 50% of photosynthesis on the planet. Here, Engel et al. provide the first three-dimensional structures of Chlamydomonas chloroplasts in their natural state. They used several recently-developed techniques to study cells that were preserved in a close-to-living condition. The cells were rapidly frozen, thinned with a technique called cryo-focused ion beam milling, and then imaged by a type of TEM called cryo-electron tomography. The three-dimensional images provide many insights into the Chlamydomonas chloroplast, including evidence that lipids and proteins move between the membrane that surrounds the chloroplast—called the chloroplast envelope—and the tips of the thylakoids. These images show how thylakoids may be built by the transport of molecules from the chloroplast envelope. In addition, the images reveal the detailed structures of the tubes that connect the thylakoids to the pyrenoid, which could explain how the two stages of photosynthesis (light harvesting and the conversion of carbon dioxide) can be coordinated even though they occur at different places within the chloroplast. Engel et al. also observed that RuBisCO enzymes are arranged in a hexagonal pattern inside the pyrenoid, but are spaced too far apart to make direct contact with each other. To understand how the pyrenoid is assembled, a future goal will be to determine what causes RuBisCO to be arranged in this way. DOI:http://dx.doi.org/10.7554/eLife.04889.002
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Affiliation(s)
- Benjamin D Engel
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Miroslava Schaffer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Luis Kuhn Cuellar
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Elizabeth Villa
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
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Engel BD, Schaffer M, Kuhn Cuellar L, Villa E, Plitzko JM, Baumeister W. Native architecture of the Chlamydomonas chloroplast revealed by in situ cryo-electron tomography. eLife 2015. [PMID: 25584625 DOI: 10.7554/elife.04889#sthash.yy91intr.dpuf] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Chloroplast function is orchestrated by the organelle's intricate architecture. By combining cryo-focused ion beam milling of vitreous Chlamydomonas cells with cryo-electron tomography, we acquired three-dimensional structures of the chloroplast in its native state within the cell. Chloroplast envelope inner membrane invaginations were frequently found in close association with thylakoid tips, and the tips of multiple thylakoid stacks converged at dynamic sites on the chloroplast envelope, implicating lipid transport in thylakoid biogenesis. Subtomogram averaging and nearest neighbor analysis revealed that RuBisCO complexes were hexagonally packed within the pyrenoid, with ~15 nm between their centers. Thylakoid stacks and the pyrenoid were connected by cylindrical pyrenoid tubules, physically bridging the sites of light-dependent photosynthesis and light-independent carbon fixation. Multiple parallel minitubules were bundled within each pyrenoid tubule, possibly serving as conduits for the targeted one-dimensional diffusion of small molecules such as ATP and sugars between the chloroplast stroma and the pyrenoid matrix.
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Affiliation(s)
- Benjamin D Engel
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Miroslava Schaffer
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Luis Kuhn Cuellar
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Elizabeth Villa
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Jürgen M Plitzko
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Wolfgang Baumeister
- Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, Martinsried, Germany
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37
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Cinquin BP, Do M, McDermott G, Walters AD, Myllys M, Smith EA, Cohen-Fix O, Le Gros MA, Larabell CA. Putting molecules in their place. J Cell Biochem 2014; 115:209-16. [PMID: 23966233 DOI: 10.1002/jcb.24658] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 08/14/2013] [Indexed: 12/18/2022]
Abstract
Each class of microscope is limited to imaging specific aspects of cell structure and/or molecular organization. However, imaging the specimen by complementary microscopes and correlating the data can overcome this limitation. Whilst not a new approach, the field of correlative imaging is currently benefitting from the emergence of new microscope techniques. Here we describe the correlation of cryogenic fluorescence tomography (CFT) with soft X-ray tomography (SXT). This amalgamation of techniques integrates 3D molecular localization data (CFT) with a high-resolution, 3D cell reconstruction of the cell (SXT). Cells are imaged in both modalities in a near-native, cryopreserved state. Here we describe the current state of the art in correlative CFT-SXT, and discuss the future outlook for this method.
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Affiliation(s)
- Bertrand P Cinquin
- Department of Anatomy, University of California San Francisco, San Francisco, California
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38
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Risco C, de Castro IF, Sanz-Sánchez L, Narayan K, Grandinetti G, Subramaniam S. Three-Dimensional Imaging of Viral Infections. Annu Rev Virol 2014; 1:453-73. [PMID: 26958730 DOI: 10.1146/annurev-virology-031413-085351] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Three-dimensional (3D) imaging technologies are beginning to have significant impact in the field of virology, as they are helping us understand how viruses take control of cells. In this article we review several methodologies for 3D imaging of cells and show how these technologies are contributing to the study of viral infections and the characterization of specialized structures formed in virus-infected cells. We include 3D reconstruction by transmission electron microscopy (TEM) using serial sections, electron tomography, and focused ion beam scanning electron microscopy (FIB-SEM). We summarize from these methods selected contributions to our understanding of viral entry, replication, morphogenesis, egress and propagation, and changes in the spatial architecture of virus-infected cells. In combination with live-cell imaging, correlative microscopy, and new techniques for molecular mapping in situ, the availability of these methods for 3D imaging is expected to provide deeper insights into understanding the structural and dynamic aspects of viral infection.
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Affiliation(s)
- Cristina Risco
- Cell Structure Laboratory, National Center for Biotechnology (CNB-CSIC), Madrid 28049, Spain;
| | | | - Laura Sanz-Sánchez
- Cell Structure Laboratory, National Center for Biotechnology (CNB-CSIC), Madrid 28049, Spain;
| | - Kedar Narayan
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
| | - Giovanna Grandinetti
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
| | - Sriram Subramaniam
- Laboratory of Cell Biology, National Cancer Institute, Bethesda, Maryland 20892;
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39
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KIZILYAPRAK C, DARASPE J, HUMBEL B. Focused ion beam scanning electron microscopy in biology. J Microsc 2014; 254:109-14. [DOI: 10.1111/jmi.12127] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2013] [Accepted: 03/12/2014] [Indexed: 12/27/2022]
Affiliation(s)
- C. KIZILYAPRAK
- Electron Microscopy Facility; University of Lausanne; Biophore 1015 Lausanne Switzerland
| | - J. DARASPE
- Electron Microscopy Facility; University of Lausanne; Biophore 1015 Lausanne Switzerland
| | - B.M. HUMBEL
- Electron Microscopy Facility; University of Lausanne; Biophore 1015 Lausanne Switzerland
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40
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Lučič V, Rigort A, Baumeister W. Cryo-electron tomography: the challenge of doing structural biology in situ. ACTA ACUST UNITED AC 2013; 202:407-19. [PMID: 23918936 PMCID: PMC3734081 DOI: 10.1083/jcb.201304193] [Citation(s) in RCA: 259] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Electron microscopy played a key role in establishing cell biology as a discipline, by producing fundamental insights into cellular organization and ultrastructure. Many seminal discoveries were made possible by the development of new sample preparation methods and imaging modalities. Recent technical advances include sample vitrification that faithfully preserves molecular structures, three-dimensional imaging by electron tomography, and improved image-processing methods. These new techniques have enabled the extraction of high fidelity structural information and are beginning to reveal the macromolecular organization of unperturbed cellular environments.
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Affiliation(s)
- Vladan Lučič
- Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
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Schorb M, Briggs JAG. Correlated cryo-fluorescence and cryo-electron microscopy with high spatial precision and improved sensitivity. Ultramicroscopy 2013; 143:24-32. [PMID: 24275379 DOI: 10.1016/j.ultramic.2013.10.015] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 10/29/2013] [Accepted: 10/31/2013] [Indexed: 01/24/2023]
Abstract
Performing fluorescence microscopy and electron microscopy on the same sample allows fluorescent signals to be used to identify and locate features of interest for subsequent imaging by electron microscopy. To carry out such correlative microscopy on vitrified samples appropriate for structural cryo-electron microscopy it is necessary to perform fluorescence microscopy at liquid-nitrogen temperatures. Here we describe an adaptation of a cryo-light microscopy stage to permit use of high-numerical aperture objectives. This allows high-sensitivity and high-resolution fluorescence microscopy of vitrified samples. We describe and apply a correlative cryo-fluorescence and cryo-electron microscopy workflow together with a fiducial bead-based image correlation procedure. This procedure allows us to locate fluorescent bacteriophages in cryo-electron microscopy images with an accuracy on the order of 50 nm, based on their fluorescent signal. It will allow the user to precisely and unambiguously identify and locate objects and events for subsequent high-resolution structural study, based on fluorescent signals.
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Affiliation(s)
- Martin Schorb
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany
| | - John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany; Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, D-69117 Heidelberg, Germany.
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42
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Hsieh C, Schmelzer T, Kishchenko G, Wagenknecht T, Marko M. Practical workflow for cryo focused-ion-beam milling of tissues and cells for cryo-TEM tomography. J Struct Biol 2013; 185:32-41. [PMID: 24211822 DOI: 10.1016/j.jsb.2013.10.019] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 10/29/2013] [Accepted: 10/31/2013] [Indexed: 11/30/2022]
Abstract
Vitreous freezing offers a way to study cells and tissue in a near-native state by cryo-transmission electron microscopy (cryo-TEM), which is important when structural information at the macromolecular level is required. Many cells - especially those in tissue - are too thick to study intact in the cryo-TEM. Cryo focused-ion-beam (cryo-FIB) milling is being used in a few laboratories to thin vitreously frozen specimens, thus avoiding the artifacts and difficulties of cryo-ultramicrotomy. However, the technique is challenging because of the need to avoid devitrification and frost accumulation during the entire process, from the initial step of freezing to the final step of loading the specimen into the cryo-TEM. We present a robust workflow that makes use of custom fixtures and devices that can be used for high-pressure-frozen bulk tissue samples as well as for samples frozen on TEM grids.
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Affiliation(s)
- Chyongere Hsieh
- New York State Department of Health, Wadsworth Center, Empire State Plaza, Albany, NY 12201, USA
| | - Thomas Schmelzer
- TGS Technologies, 702 Little Creek Lane, Cranberry Township, PA 16066, USA
| | - Gregory Kishchenko
- New York State Department of Health, Wadsworth Center, Empire State Plaza, Albany, NY 12201, USA
| | - Terence Wagenknecht
- New York State Department of Health, Wadsworth Center, Empire State Plaza, Albany, NY 12201, USA; Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY 12203, USA
| | - Michael Marko
- New York State Department of Health, Wadsworth Center, Empire State Plaza, Albany, NY 12201, USA; College of Nanoscale Science and Engineering, University at Albany, 251 Fuller Rd., Albany, NY 12203, USA.
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43
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Han HM, Bouchet-Marquis C, Huebinger J, Grabenbauer M. Golgi apparatus analyzed by cryo-electron microscopy. Histochem Cell Biol 2013; 140:369-81. [PMID: 23954988 PMCID: PMC3787787 DOI: 10.1007/s00418-013-1136-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/03/2013] [Indexed: 11/28/2022]
Abstract
In 1898, the Golgi apparatus was discovered by light microscopy, and since the 1950s, the ultrastructure composition is known by electron microscopic investigation. The complex three-dimensional morphology fascinated researchers and was sometimes even the driving force to develop novel visualization techniques. However, the highly dynamic membrane systems of Golgi apparatus are delicate and prone to fixation artifacts. Therefore, the understanding of Golgi morphology and its function has been improved significantly with the development of better preparation methods. Nowadays, cryo-fixation is the method of choice to arrest instantly all dynamic and physiological processes inside cells, tissues, and small organisms. Embedded in amorphous ice, such samples can be further processed by freeze substitution or directly analyzed in their fully hydrated state by cryo-electron microscopy and tomography. Even though the overall morphology of vitrified Golgi stacks is comparable to well-prepared and resin-embedded samples, previously unknown structural details can be observed solely based on their native density. At this point, any further improvement of sample preparation would gain novel insights, perhaps not in terms of general morphology, but on fine structural details of this dynamic organelle.
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Affiliation(s)
- Hong-Mei Han
- Department of Systemic Cell Biology, Max-Planck-Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Cedric Bouchet-Marquis
- Department of Molecular Cellular and Developmental Biology, University of Colorado, Boulder, CO USA
- FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, OR 97124 USA
| | - Jan Huebinger
- Department of Systemic Cell Biology, Max-Planck-Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227 Dortmund, Germany
| | - Markus Grabenbauer
- Institute of Anatomy and Cell Biology, Heidelberg University, INF 307, 69120 Heidelberg, Germany
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44
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Opening windows into the cell: focused-ion-beam milling for cryo-electron tomography. Curr Opin Struct Biol 2013; 23:771-7. [DOI: 10.1016/j.sbi.2013.08.006] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 08/12/2013] [Accepted: 08/29/2013] [Indexed: 11/16/2022]
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In-situ integrity control of frozen-hydrated, vitreous lamellas prepared by the cryo-focused ion beam-scanning electron microscope. J Struct Biol 2013; 183:11-8. [PMID: 23742839 DOI: 10.1016/j.jsb.2013.05.016] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2013] [Revised: 05/14/2013] [Accepted: 05/28/2013] [Indexed: 11/22/2022]
Abstract
Recently a number of new approaches have been presented with the intention to produce electron beam transparent cryo-sections (lamellas in FIB-SEM terminology) from hydrated vitreously frozen cryo samples with a Focused Ion Beam (FIB) system, suitable for cryo-Transmission Electron Microscopy (cryo-TEM). As the workflow is still challenging and time consuming, it is important to be able to determine the integrity and suitability (cells vs. no cells; vitreous vs. crystalline) of the lamellas. Here we present an in situ method that tests both conditions by using the cryo-Scanning Electron Microscope (cryo-SEM) in transmission mode (TSEM; Transmission Scanning Electron Microscope) once the FIB-made lamella is ready. Cryo-TSEM imaging of unstained cells yields strong contrast, enabling direct imaging of material present in the lamellas. In addition, orientation contrast is shown to be suitable for distinguishing crystalline lamellas from vitreous lamellas. Tilting the stage a few degrees results in changes of contrast between ice grains as a function of the tilt angle, whereas the contrast of areas with vitreous ice remains unchanged as a function of the tilt angle. This orientation contrast has subsequently been validated by cryo-Electron BackScattered Diffraction (EBSD) in transmission mode. Integration of the presented method is discussed and the role it can play in future developments for a new and innovative all-in-one cryo-FIB-SEM life sciences instrument.
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46
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Briggs JAG. Structural biology in situ--the potential of subtomogram averaging. Curr Opin Struct Biol 2013; 23:261-7. [PMID: 23466038 DOI: 10.1016/j.sbi.2013.02.003] [Citation(s) in RCA: 170] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2012] [Revised: 02/12/2013] [Accepted: 02/13/2013] [Indexed: 12/27/2022]
Abstract
Cryo-electron tomography provides low-resolution 3D views of cells, organelles, or viruses. Macromolecular complexes present in multiple copies can be subsequently identified within the 3D reconstruction (the tomogram), computationally extracted, and averaged to obtain higher resolution 3D structures, as well as a map of their spatial distribution. This method, called subtomogram averaging or subvolume averaging, allows structures of macromolecular complexes to be resolved in situ. Recent applications have provided in situ structural data at resolutions of 2-4 nm on samples including polysomes, nuclear pores, vesicle coats, and viral surface proteins. Here I describe the method and discuss limitations, advances and recent applications. I speculate how the method will solve more structures at higher resolution, allowing in situ structural biology.
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Affiliation(s)
- John A G Briggs
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
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