1
|
Dos Santos Pacheco N, Tell I Puig A, Guérin A, Martinez M, Maco B, Tosetti N, Delgado-Betancourt E, Lunghi M, Striepen B, Chang YW, Soldati-Favre D. Sustained rhoptry docking and discharge requires Toxoplasma gondii intraconoidal microtubule-associated proteins. Nat Commun 2024; 15:379. [PMID: 38191574 PMCID: PMC10774369 DOI: 10.1038/s41467-023-44631-y] [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: 07/13/2023] [Accepted: 12/21/2023] [Indexed: 01/10/2024] Open
Abstract
In Apicomplexa, rhoptry discharge is essential for invasion and involves an apical vesicle (AV) docking one or two rhoptries to a macromolecular secretory apparatus. Toxoplasma gondii is armed with 10-12 rhoptries and 5-6 microtubule-associated vesicles (MVs) presumably for iterative rhoptry discharge. Here, we have addressed the localization and functional significance of two intraconoidal microtubule (ICMT)-associated proteins instrumental for invasion. Mechanistically, depletion of ICMAP2 leads to a dissociation of the ICMTs, their detachment from the conoid and dispersion of MVs and rhoptries. ICMAP3 exists in two isoforms that contribute to the control of the ICMTs length and the docking of the two rhoptries at the AV, respectively. This study illuminates the central role ICMTs play in scaffolding the discharge of multiple rhoptries. This process is instrumental for virulence in the mouse model of infection and in addition promotes sterile protection against T. gondii via the release of key effectors inducing immunity.
Collapse
Affiliation(s)
- Nicolas Dos Santos Pacheco
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Albert Tell I Puig
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Amandine Guérin
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Matthew Martinez
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Bohumil Maco
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Nicolò Tosetti
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Estefanía Delgado-Betancourt
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Matteo Lunghi
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Boris Striepen
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi-Wei Chang
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland.
| |
Collapse
|
2
|
Martinez M, Mageswaran SK, Guérin A, Chen WD, Thompson CP, Chavin S, Soldati-Favre D, Striepen B, Chang YW. Origin and arrangement of actin filaments for gliding motility in apicomplexan parasites revealed by cryo-electron tomography. Nat Commun 2023; 14:4800. [PMID: 37558667 PMCID: PMC10412601 DOI: 10.1038/s41467-023-40520-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 07/26/2023] [Indexed: 08/11/2023] Open
Abstract
The phylum Apicomplexa comprises important eukaryotic parasites that invade host tissues and cells using a unique mechanism of gliding motility. Gliding is powered by actomyosin motors that translocate host-attached surface adhesins along the parasite cell body. Actin filaments (F-actin) generated by Formin1 play a central role in this critical parasitic activity. However, their subcellular origin, path and ultrastructural arrangement are poorly understood. Here we used cryo-electron tomography to image motile Cryptosporidium parvum sporozoites and reveal the cellular architecture of F-actin at nanometer-scale resolution. We demonstrate that F-actin nucleates at the apically positioned preconoidal rings and is channeled into the pellicular space between the parasite plasma membrane and the inner membrane complex in a conoid extrusion-dependent manner. Within the pellicular space, filaments on the inner membrane complex surface appear to guide the apico-basal flux of F-actin. F-actin concordantly accumulates at the basal end of the parasite. Finally, analyzing a Formin1-depleted Toxoplasma gondii mutant pinpoints the upper preconoidal ring as the conserved nucleation hub for F-actin in Cryptosporidium and Toxoplasma. Together, we provide an ultrastructural model for the life cycle of F-actin for apicomplexan gliding motility.
Collapse
Affiliation(s)
- Matthew Martinez
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Shrawan Kumar Mageswaran
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Amandine Guérin
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - William David Chen
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Cameron Parker Thompson
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sabine Chavin
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular Medicine, Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Boris Striepen
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Yi-Wei Chang
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
- Pennsylvania Muscle Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|
3
|
Gorbea Colón JJ, Palao L, Chen SF, Kim HJ, Snyder L, Chang YW, Tsai KL, Murakami K. Structural basis of a transcription pre-initiation complex on a divergent promoter. Mol Cell 2023; 83:574-588.e11. [PMID: 36731470 PMCID: PMC10162435 DOI: 10.1016/j.molcel.2023.01.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 11/28/2022] [Accepted: 01/06/2023] [Indexed: 02/04/2023]
Abstract
Most eukaryotic promoter regions are divergently transcribed. As the RNA polymerase II pre-initiation complex (PIC) is intrinsically asymmetric and responsible for transcription in a single direction, it is unknown how divergent transcription arises. Here, the Saccharomyces cerevisiae Mediator complexed with a PIC (Med-PIC) was assembled on a divergent promoter and analyzed by cryoelectron microscopy. The structure reveals two distinct Med-PICs forming a dimer through the Mediator tail module, induced by a homodimeric activator protein localized near the dimerization interface. The tail dimer is associated with ∼80-bp upstream DNA, such that two flanking core promoter regions are positioned and oriented in a suitable form for PIC assembly in opposite directions. Also, cryoelectron tomography visualized the progress of the PIC assembly on the two core promoter regions, providing direct evidence for the role of the Med-PIC dimer in divergent transcription.
Collapse
Affiliation(s)
- Jose J Gorbea Colón
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Leon Palao
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Shin-Fu Chen
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
| | - Hee Jong Kim
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Laura Snyder
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yi-Wei Chang
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Kuang-Lei Tsai
- Department of Biochemistry and Molecular Biology, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, TX 77030, USA.
| | - Kenji Murakami
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Penn Center for Genome Integrity, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| |
Collapse
|
4
|
Martinez M, Chen WD, Cova MM, Molnár P, Mageswaran SK, Guérin A, John ARO, Lebrun M, Chang YW. Rhoptry secretion system structure and priming in Plasmodium falciparum revealed using in situ cryo-electron tomography. Nat Microbiol 2022; 7:1230-1238. [PMID: 35817892 PMCID: PMC7613239 DOI: 10.1038/s41564-022-01171-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 06/07/2022] [Indexed: 01/13/2023]
Abstract
Apicomplexan parasites secrete contents of the rhoptries, club-shaped organelles in the apical region, into host cells to permit their invasion and establishment of infection. The rhoptry secretory apparatus (RSA), which is critical for rhoptry secretion, was recently discovered in Toxoplasma and Cryptosporidium. It is unknown whether a similar molecular machinery exists in the malaria parasite Plasmodium. In this study, we use in situ cryo-electron tomography to investigate the rhoptry secretion system in P. falciparum merozoites. We identify the presence of an RSA at the cell apex and a morphologically distinct apical vesicle docking the tips of the two rhoptries to the RSA. We also discover two additional rhoptry organizations that lack the apical vesicle. Using subtomogram averaging, we reveal different conformations of the RSA structure corresponding to different rhoptry organizations. Our results highlight previously unknown steps in the process of rhoptry secretion and indicate a regulatory role for the conserved apical vesicle in host invasion by apicomplexan parasites.
Collapse
Affiliation(s)
- Matthew Martinez
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - William David Chen
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | | | - Petra Molnár
- Department of Pediatrics, Division of Infectious Diseases, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Shrawan Kumar Mageswaran
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Amandine Guérin
- Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Audrey R Odom John
- Department of Pediatrics, Division of Infectious Diseases, Children's Hospital of Philadelphia, Philadelphia, PA, USA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Maryse Lebrun
- LPHI, UMR 5235 CNRS, Université de Montpellier, Montpellier, France
| | - Yi-Wei Chang
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|
5
|
Chang WH, Huang SH, Lin HH, Chung SC, Tu IP. Cryo-EM Analyses Permit Visualization of Structural Polymorphism of Biological Macromolecules. FRONTIERS IN BIOINFORMATICS 2021; 1:788308. [PMID: 36303748 PMCID: PMC9580929 DOI: 10.3389/fbinf.2021.788308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 11/16/2021] [Indexed: 11/13/2022] Open
Abstract
The functions of biological macromolecules are often associated with conformational malleability of the structures. This phenomenon of chemically identical molecules with different structures is coined structural polymorphism. Conventionally, structural polymorphism is observed directly by structural determination at the density map level from X-ray crystal diffraction. Although crystallography approach can report the conformation of a macromolecule with the position of each atom accurately defined in it, the exploration of structural polymorphism and interpreting biological function in terms of crystal structures is largely constrained by the crystal packing. An alternative approach to studying the macromolecule of interest in solution is thus desirable. With the advancement of instrumentation and computational methods for image analysis and reconstruction, cryo-electron microscope (cryo-EM) has been transformed to be able to produce “in solution” structures of macromolecules routinely with resolutions comparable to crystallography but without the need of crystals. Since the sample preparation of single-particle cryo-EM allows for all forms co-existing in solution to be simultaneously frozen, the image data contain rich information as to structural polymorphism. The ensemble of structure information can be subsequently disentangled through three-dimensional (3D) classification analyses. In this review, we highlight important examples of protein structural polymorphism in relation to allostery, subunit cooperativity and function plasticity recently revealed by cryo-EM analyses, and review recent developments in 3D classification algorithms including neural network/deep learning approaches that would enable cryo-EM analyese in this regard. Finally, we brief the frontier of cryo-EM structure determination of RNA molecules where resolving the structural polymorphism is at dawn.
Collapse
Affiliation(s)
- Wei-Hau Chang
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan
- *Correspondence: Wei-Hau Chang,
| | | | - Hsin-Hung Lin
- Institute of Chemistry, Academia Sinica, Taipei, Taiwan
| | - Szu-Chi Chung
- Department of Applied Mathematics, National Sun Yat-sen University, Kaohsiung, Taiwan
| | - I-Ping Tu
- Institute of Statistical Science, Academia Sinica, Taipei, Taiwan
| |
Collapse
|
6
|
In situ ultrastructures of two evolutionarily distant apicomplexan rhoptry secretion systems. Nat Commun 2021; 12:4983. [PMID: 34404783 PMCID: PMC8371170 DOI: 10.1038/s41467-021-25309-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Accepted: 08/03/2021] [Indexed: 12/03/2022] Open
Abstract
Parasites of the phylum Apicomplexa cause important diseases including malaria, cryptosporidiosis and toxoplasmosis. These intracellular pathogens inject the contents of an essential organelle, the rhoptry, into host cells to facilitate invasion and infection. However, the structure and mechanism of this eukaryotic secretion system remain elusive. Here, using cryo-electron tomography and subtomogram averaging, we report the conserved architecture of the rhoptry secretion system in the invasive stages of two evolutionarily distant apicomplexans, Cryptosporidium parvum and Toxoplasma gondii. In both species, we identify helical filaments, which appear to shape and compartmentalize the rhoptries, and an apical vesicle (AV), which facilitates docking of the rhoptry tip at the parasite’s apical region with the help of an elaborate ultrastructure named the rhoptry secretory apparatus (RSA); the RSA anchors the AV at the parasite plasma membrane. Depletion of T. gondii Nd9, a protein required for rhoptry secretion, disrupts the RSA ultrastructure and AV-anchoring. Moreover, T. gondii contains a line of AV-like vesicles, which interact with a pair of microtubules and accumulate towards the AV, leading to a working model for AV-reloading and discharging of multiple rhoptries. Together, our analyses provide an ultrastructural framework to understand how these important parasites deliver effectors into host cells. The rhoptry is an apical secretory organelle of apicomplexan parasites that is essential for host cell invasion. Here, Mageswaran et al. provide in situ ultrastructures of rhoptries from two pathogens, revealing a conserved architecture including luminal filaments and a distinct docking mechanism.
Collapse
|
7
|
An overview of the recent advances in cryo-electron microscopy for life sciences. Emerg Top Life Sci 2021; 5:151-168. [PMID: 33760078 DOI: 10.1042/etls20200295] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/26/2021] [Accepted: 03/09/2021] [Indexed: 01/18/2023]
Abstract
Cryo-electron microscopy (CryoEM) has superseded X-ray crystallography and NMR to emerge as a popular and effective tool for structure determination in recent times. It has become indispensable for the characterization of large macromolecular assemblies, membrane proteins, or samples that are limited, conformationally heterogeneous, and recalcitrant to crystallization. Besides, it is the only tool capable of elucidating high-resolution structures of macromolecules and biological assemblies in situ. A state-of-the-art electron microscope operable at cryo-temperature helps preserve high-resolution details of the biological sample. The structures can be determined, either in isolation via single-particle analysis (SPA) or helical reconstruction, electron diffraction (ED) or within the cellular environment via cryo-electron tomography (cryoET). All the three streams of SPA, ED, and cryoET (along with subtomogram averaging) have undergone significant advancements in recent times. This has resulted in breaking the boundaries with respect to both the size of the macromolecules/assemblies whose structures could be determined along with the visualization of atomic details at resolutions unprecedented for cryoEM. In addition, the collection of larger datasets combined with the ability to sort and process multiple conformational states from the same sample are providing the much-needed link between the protein structures and their functions. In overview, these developments are helping scientists decipher the molecular mechanism of critical cellular processes, solve structures of macromolecules that were challenging targets for structure determination until now, propelling forward the fields of biology and biomedicine. Here, we summarize recent advances and key contributions of the three cryo-electron microscopy streams of SPA, ED, and cryoET.
Collapse
|
8
|
Ramachandra R, Mackey MR, Hu J, Peltier ST, Xuong NH, Ellisman MH, Adams SR. Elemental mapping of labelled biological specimens at intermediate energy loss in an energy-filtered TEM acquired using a direct detection device. J Microsc 2021; 283:127-144. [PMID: 33844293 PMCID: PMC8316382 DOI: 10.1111/jmi.13014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 03/11/2021] [Accepted: 04/04/2021] [Indexed: 12/30/2022]
Abstract
The technique of colour EM that was recently developed enabled localisation of specific macromolecules/proteins of interest by the targeted deposition of diaminobenzidine (DAB) conjugated to lanthanide chelates. By acquiring lanthanide elemental maps by energy‐filtered transmission electron microscopy (EFTEM) and overlaying them in pseudo‐colour over the conventional greyscale TEM image, a colour EM image is generated. This provides a powerful tool for visualising subcellular component/s, by the ability to clearly distinguish them from the general staining of the endogenous cellular material. Previously, the lanthanide elemental maps were acquired at the high‐loss M4,5 edge (excitation of 3d electrons), where the characteristic signal is extremely low and required considerably long exposures. In this paper, we explore the possibility of acquiring the elemental maps of lanthanides at their N4,5 edge (excitation of 4d electrons), which occurring at a much lower energy‐loss regime, thereby contains significantly greater total characteristic signal owing to the higher inelastic scattering cross‐sections at the N4,5 edge. Acquiring EFTEM lanthanide elemental maps at the N4,5 edge instead of the M4,5 edge, provides ∼4× increase in signal‐to‐noise and ∼2× increase in resolution. However, the interpretation of the lanthanide maps acquired at the N4,5 edge by the traditional 3‐window method, is complicated due to the broad shape of the edge profile and the lower signal‐above‐background ratio. Most of these problems can be circumvented by the acquisition of elemental maps with the more sophisticated technique of EFTEM Spectrum Imaging (EFTEM SI). Here, we also report the chemical synthesis of novel second‐generation DAB lanthanide metal chelate conjugates that contain 2 lanthanide ions per DAB molecule in comparison with 0.5 lanthanide ion per DAB in the first generation. Thereby, fourfold more Ln3+ per oxidised DAB would be deposited providing significant amplification of signal. This paper applies the colour EM technique at the intermediate‐loss energy‐loss regime to three different cellular targets, namely using mitochondrial matrix‐directed APEX2, histone H2B‐Nucleosome and EdU‐DNA. All the examples shown in the paper are single colour EM images only.
Collapse
Affiliation(s)
- Ranjan Ramachandra
- Department of Neurosciences, University of California, San Diego, La Jolla, California, USA.,Center for Research in Biological Systems, National Center for Microscopy and, Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - Mason R Mackey
- Department of Neurosciences, University of California, San Diego, La Jolla, California, USA.,Center for Research in Biological Systems, National Center for Microscopy and, Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - Junru Hu
- Department of Neurosciences, University of California, San Diego, La Jolla, California, USA.,Center for Research in Biological Systems, National Center for Microscopy and, Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - Steven T Peltier
- Department of Neurosciences, University of California, San Diego, La Jolla, California, USA.,Center for Research in Biological Systems, National Center for Microscopy and, Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - Nguyen-Huu Xuong
- Center for Research in Biological Systems, National Center for Microscopy and, Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - Mark H Ellisman
- Department of Neurosciences, University of California, San Diego, La Jolla, California, USA.,Center for Research in Biological Systems, National Center for Microscopy and, Imaging Research, University of California, San Diego, La Jolla, California, USA
| | - Stephen R Adams
- Department of Pharmacology, University of California, San Diego, La Jolla, California, USA
| |
Collapse
|
9
|
Bulk and local structures of metal-organic frameworks unravelled by high-resolution electron microscopy. Commun Chem 2020; 3:99. [PMID: 36703329 PMCID: PMC9814830 DOI: 10.1038/s42004-020-00361-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 07/21/2020] [Indexed: 01/29/2023] Open
Abstract
The periodic bulk structures of metal-organic frameworks (MOFs) can be solved by diffraction-based techniques; however, their non-periodic local structures-such as crystal surfaces, grain boundaries, defects, and guest molecules-have long been elusive due to a lack of suitable characterization tools. Recent advances in (scanning) transmission electron microscopy ((S)TEM) has made it possible to probe the local structures of MOFs at atomic resolution. In this article, we discuss why high-resolution (S)TEM of MOFs is challenging and how the new low-dose techniques overcome this challenge, and we review various MOF structural features observed by (S)TEM and important insights gained from these observations. Our discussions focus on real-space imaging, excluding other TEM-related characterization techniques (e.g. electron diffraction and spectroscopy).
Collapse
|
10
|
Zhang C, Feng J, DaCosta LR, Voyles PM. Atomic resolution convergent beam electron diffraction analysis using convolutional neural networks. Ultramicroscopy 2019; 210:112921. [PMID: 31978635 DOI: 10.1016/j.ultramic.2019.112921] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 12/09/2019] [Accepted: 12/22/2019] [Indexed: 11/17/2022]
Abstract
Two types of convolutional neural network (CNN) models, a discrete classification network and a continuous regression network, were trained to determine local sample thickness from convergent beam diffraction (CBED) patterns of SrTiO3 collected in a scanning transmission electron microscope (STEM) at atomic column resolution. Acquisition of atomic resolution CBED patterns for this purpose requires careful balancing of CBED feature size in pixels, acquisition speed, and detector dynamic range. The training datasets were derived from multislice simulations, which must be convolved with incoherent source broadening. Sample thicknesses were also determined using quantitative high-angle annular dark-field (HAADF) STEM images acquired simultaneously. The regression CNN performed well on sample thinner than 35 nm, with 70% of the CNN results within 1 nm of HAADF thickness, and 1.0 nm overall root mean square error between the two measurements. The classification CNN was trained for a thicknesses up to 100 nm and yielded 66% of CNN results within one classification increment of 2 nm of HAADF thickness. Our approach depends on methods from computer vision including transfer learning and image augmentation.
Collapse
Affiliation(s)
- Chenyu Zhang
- Department of Materials Science and Engineering, University of Wisconsin-Madison, United States
| | - Jie Feng
- Department of Materials Science and Engineering, University of Wisconsin-Madison, United States
| | - Luis Rangel DaCosta
- Department of Materials Science and Engineering, University of Wisconsin-Madison, United States
| | - Paul M Voyles
- Department of Materials Science and Engineering, University of Wisconsin-Madison, United States.
| |
Collapse
|
11
|
Nievergelt AP, Viar GA, Pigino G. Towards a mechanistic understanding of cellular processes by cryoEM. Curr Opin Struct Biol 2019; 58:149-158. [PMID: 31349128 DOI: 10.1016/j.sbi.2019.06.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 06/04/2019] [Accepted: 06/18/2019] [Indexed: 01/12/2023]
Abstract
A series of recent hardware and software developments have transformed cryo-electron microscopy (cryoEM) from a niche tool into a method that has become indispensable in structural and functional biology. Samples that are rapidly frozen are encased in a near-native state inside a layer of amorphous ice, and then imaged in an electron microscope cooled to cryogenic temperatures. Despite being conceptually simple, cryoEM owns its success to a plethora of technological developments from numerous research groups. Here, we review the key technologies that have made this astonishing transformation possible and highlight recent trends with a focus on cryo-electron tomography. Additionally, we discuss how correlated microscopy is an exciting and perpendicular development route forward in this already rapidly growing field. We specifically discuss microscopy techniques that allow to complement time-dependent information of dynamic processes to the unique high resolution obtained in cryoEM.
Collapse
Affiliation(s)
| | - Gonzalo Alvarez Viar
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Gaia Pigino
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| |
Collapse
|
12
|
|
13
|
Neumann E, Farias Estrozi L, Effantin G, Breyton C, Schoehn G. Prix Nobel de Chimie 2017 : Jacques Dubochet, Joachim Frank et Richard Henderson. Med Sci (Paris) 2017; 33:1111-1117. [DOI: 10.1051/medsci/20173212019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
14
|
Ramachandra R, Bouwer JC, Mackey MR, Bushong E, Peltier ST, Xuong NH, Ellisman MH. Improving signal to noise in labeled biological specimens using energy-filtered TEM of sections with a drift correction strategy and a direct detection device. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2014; 20:706-14. [PMID: 24641915 PMCID: PMC4178974 DOI: 10.1017/s1431927614000452] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Energy filtered transmission electron microscopy techniques are regularly used to build elemental maps of spatially distributed nanoparticles in materials and biological specimens. When working with thick biological sections, electron energy loss spectroscopy techniques involving core-loss electrons often require exposures exceeding several minutes to provide sufficient signal to noise. Image quality with these long exposures is often compromised by specimen drift, which results in blurring and reduced resolution. To mitigate drift artifacts, a series of short exposure images can be acquired, aligned, and merged to form a single image. For samples where the target elements have extremely low signal yields, the use of charge coupled device (CCD)-based detectors for this purpose can be problematic. At short acquisition times, the images produced by CCDs can be noisy and may contain fixed pattern artifacts that impact subsequent correlative alignment. Here we report on the use of direct electron detection devices (DDD's) to increase the signal to noise as compared with CCD's. A 3× improvement in signal is reported with a DDD versus a comparably formatted CCD, with equivalent dose on each detector. With the fast rolling-readout design of the DDD, the duty cycle provides a major benefit, as there is no dead time between successive frames.
Collapse
Affiliation(s)
- Ranjan Ramachandra
- Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - James C. Bouwer
- Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Mason R. Mackey
- Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Eric Bushong
- Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Steven T. Peltier
- Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Nguyen-Huu Xuong
- Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
| | - Mark H. Ellisman
- Center for Research in Biological Systems, National Center for Microscopy and Imaging Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093, USA
| |
Collapse
|
15
|
McMullan G, Faruqi A, Henderson R, Guerrini N, Turchetta R, Jacobs A, van Hoften G. Experimental observation of the improvement in MTF from backthinning a CMOS direct electron detector. Ultramicroscopy 2009; 109:1144-7. [PMID: 19541421 PMCID: PMC2937214 DOI: 10.1016/j.ultramic.2009.05.005] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 04/03/2009] [Accepted: 05/01/2009] [Indexed: 11/23/2022]
Abstract
The advantages of backthinning monolithic active pixel sensors (MAPS) based on complementary metal oxide semiconductor (CMOS) direct electron detectors for electron microscopy have been discussed previously; they include better spatial resolution (modulation transfer function or MTF) and efficiency at all spatial frequencies (detective quantum efficiency or DQE). It was suggested that a 'thin' CMOS detector would have the most outstanding properties [1-3] because of a reduction in the proportion of backscattered electrons. In this paper we show, theoretically (using Monte Carlo simulations of electron trajectories) and experimentally that this is indeed the case. The modulation transfer functions of prototype backthinned CMOS direct electron detectors have been measured at 300keV. At zero spatial frequency, in non-backthinned 700-mum-thick detectors, the backscattered component makes up over 40% of the total signal but, by backthinning to 100, 50 or 35mum, this can be reduced to 25%, 15% and 10%, respectively. For the 35mum backthinned detector, this reduction in backscatter increases the MTF by 40% for spatial frequencies between 0.1 and 1.0 Nyquist. As discussed in the main text, reducing backscattering in backthinned detectors should also improve DQE.
Collapse
Affiliation(s)
- G. McMullan
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - A.R. Faruqi
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - R. Henderson
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 0QH, UK
| | - N. Guerrini
- STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK
| | - R. Turchetta
- STFC Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK
| | - A. Jacobs
- Technical University of Eindhoven, 5600 MB Eindhoven, Netherlands
| | | |
Collapse
|
16
|
Li Z, Jensen GJ. Electron cryotomography: a new view into microbial ultrastructure. Curr Opin Microbiol 2009; 12:333-40. [PMID: 19427259 PMCID: PMC2747746 DOI: 10.1016/j.mib.2009.03.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 03/20/2009] [Accepted: 03/25/2009] [Indexed: 10/20/2022]
Abstract
Electron cryotomography (ECT) is an emerging technology that allows thin samples such as small bacterial cells to be imaged in 3D in a nearly native state to 'molecular' (approximately 4nm) resolution. As such, ECT is beginning to deliver long-awaited insight into the positions and structures of cytoskeletal filaments, cell wall elements, motility machines, chemoreceptor arrays, internal compartments, and other ultrastructures. Here we briefly explain ECT, review its recent contributions to microbiology, and conclude with a discussion of future prospects.
Collapse
Affiliation(s)
- Zhuo Li
- Division of Biology, California Institute of Technology, Pasadena, CA 91125, USA
| | | |
Collapse
|
17
|
Jin L, Milazzo AC, Kleinfelder S, Li S, Leblanc P, Duttweiler F, Bouwer JC, Peltier ST, Ellisman MH, Xuong NH. Applications of direct detection device in transmission electron microscopy. J Struct Biol 2007; 161:352-8. [PMID: 18054249 DOI: 10.1016/j.jsb.2007.10.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Revised: 10/18/2007] [Accepted: 10/19/2007] [Indexed: 10/22/2022]
Abstract
A prototype direct detection device (DDD) camera system has shown great promise in improving both the spatial resolution and the signal to noise ratio for electron microscopy at 120-400 keV beam energies (Xuong et al., 2007. Methods in Cell Biology, 79, 721-739). Without the need for a resolution-limiting scintillation screen as in the charge coupled device (CCD), the DDD camera can outperform CCD based systems in terms of spatial resolution, due to its small pixel size (5 microm). In this paper, the modulation transfer function (MTF) of the DDD prototype is measured and compared with the specifications of commercial scientific CCD camera systems. Combining the fast speed of the DDD with image mosaic techniques, fast wide-area imaging is now possible. In this paper, the first large area mosaic image and the first tomography dataset from the DDD camera are presented, along with an image processing algorithm to correct the specimen drift utilizing the fast readout of the DDD system.
Collapse
Affiliation(s)
- Liang Jin
- University of California at San Diego, La Jolla, CA 92093, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|