1
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Kumar A, Jha KK, Olech B, Goral T, Malinska M, Woźniak K, Dominiak PM. TAAM refinement on high-resolution experimental and simulated 3D ED/MicroED data for organic molecules. Acta Crystallogr C Struct Chem 2024; 80:264-277. [PMID: 38934273 PMCID: PMC11225613 DOI: 10.1107/s2053229624005357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Accepted: 06/05/2024] [Indexed: 06/28/2024] Open
Abstract
3D electron diffraction (3D ED), or microcrystal electron diffraction (MicroED), has become an alternative technique for determining the high-resolution crystal structures of compounds from sub-micron-sized crystals. Here, we considered L-alanine, α-glycine and urea, which are known to form good-quality crystals, and collected high-resolution 3D ED data on our in-house TEM instrument. In this study, we present a comparison of independent atom model (IAM) and transferable aspherical atom model (TAAM) kinematical refinement against experimental and simulated data. TAAM refinement on both experimental and simulated data clearly improves the model fitting statistics (R factors and residual electrostatic potential) compared to IAM refinement. This shows that TAAM better represents the experimental electrostatic potential of organic crystals than IAM. Furthermore, we compared the geometrical parameters and atomic displacement parameters (ADPs) resulting from the experimental refinements with the simulated refinements, with the periodic density functional theory (DFT) calculations and with published X-ray and neutron crystal structures. The TAAM refinements on the 3D ED data did not improve the accuracy of the bond lengths between the non-H atoms. The experimental 3D ED data provided more accurate H-atom positions than the IAM refinements on the X-ray diffraction data. The IAM refinements against 3D ED data had a tendency to lead to slightly longer X-H bond lengths than TAAM, but the difference was statistically insignificant. Atomic displacement parameters were too large by tens of percent for L-alanine and α-glycine. Most probably, other unmodelled effects were causing this behaviour, such as radiation damage or dynamical scattering.
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Affiliation(s)
- Anil Kumar
- Biological and Chemical Research Centre Faculty of Chemistry University of Warsaw, ul Żwirki i Wigury 101 02-089 Warszawa Poland
| | - Kunal Kumar Jha
- Biological and Chemical Research Centre Faculty of Chemistry University of Warsaw, ul Żwirki i Wigury 101 02-089 Warszawa Poland
- Centre of New Technologies University of Warsaw, ul S Banacha 2c 02-097 Warszawa Poland
| | - Barbara Olech
- Biological and Chemical Research Centre Faculty of Chemistry University of Warsaw, ul Żwirki i Wigury 101 02-089 Warszawa Poland
- Centre of New Technologies University of Warsaw, ul S Banacha 2c 02-097 Warszawa Poland
| | - Tomasz Goral
- Biological and Chemical Research Centre Faculty of Chemistry University of Warsaw, ul Żwirki i Wigury 101 02-089 Warszawa Poland
- Centre of New Technologies University of Warsaw, ul S Banacha 2c 02-097 Warszawa Poland
| | - Maura Malinska
- Faculty of Chemistry University of Warsaw, Pasteura 1 02-093 Warszawa Poland
| | - Krzysztof Woźniak
- Centre of New Technologies University of Warsaw, ul S Banacha 2c 02-097 Warszawa Poland
- Faculty of Chemistry University of Warsaw, Pasteura 1 02-093 Warszawa Poland
| | - Paulina Maria Dominiak
- Biological and Chemical Research Centre Faculty of Chemistry University of Warsaw, ul Żwirki i Wigury 101 02-089 Warszawa Poland
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2
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Parkhurst JM, Varslot T, Dumoux M, Siebert CA, Darrow M, Basham M, Kirkland A, Grange M, Evans G, Naismith JH. Pillar data-acquisition strategies for cryo-electron tomography of beam-sensitive biological samples. Acta Crystallogr D Struct Biol 2024; 80:421-438. [PMID: 38829361 PMCID: PMC11154591 DOI: 10.1107/s2059798324004546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Accepted: 05/15/2024] [Indexed: 06/05/2024] Open
Abstract
For cryo-electron tomography (cryo-ET) of beam-sensitive biological specimens, a planar sample geometry is typically used. As the sample is tilted, the effective thickness of the sample along the direction of the electron beam increases and the signal-to-noise ratio concomitantly decreases, limiting the transfer of information at high tilt angles. In addition, the tilt range where data can be collected is limited by a combination of various sample-environment constraints, including the limited space in the objective lens pole piece and the possible use of fixed conductive braids to cool the specimen. Consequently, most tilt series are limited to a maximum of ±70°, leading to the presence of a missing wedge in Fourier space. The acquisition of cryo-ET data without a missing wedge, for example using a cylindrical sample geometry, is hence attractive for volumetric analysis of low-symmetry structures such as organelles or vesicles, lysis events, pore formation or filaments for which the missing information cannot be compensated by averaging techniques. Irrespective of the geometry, electron-beam damage to the specimen is an issue and the first images acquired will transfer more high-resolution information than those acquired last. There is also an inherent trade-off between higher sampling in Fourier space and avoiding beam damage to the sample. Finally, the necessity of using a sufficient electron fluence to align the tilt images means that this fluence needs to be fractionated across a small number of images; therefore, the order of data acquisition is also a factor to consider. Here, an n-helix tilt scheme is described and simulated which uses overlapping and interleaved tilt series to maximize the use of a pillar geometry, allowing the entire pillar volume to be reconstructed as a single unit. Three related tilt schemes are also evaluated that extend the continuous and classic dose-symmetric tilt schemes for cryo-ET to pillar samples to enable the collection of isotropic information across all spatial frequencies. A fourfold dose-symmetric scheme is proposed which provides a practical compromise between uniform information transfer and complexity of data acquisition.
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Affiliation(s)
- James M. Parkhurst
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Trond Varslot
- Thermo Fisher Scientific, Vlastimila Pecha, Brno, Czechia
| | - Maud Dumoux
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
| | - C. Alistair Siebert
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Michele Darrow
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
| | - Mark Basham
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
| | - Angus Kirkland
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
- Electron Physical Science Imaging Centre, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
- Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, United Kingdom
| | - Michael Grange
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
| | - Gwyndaf Evans
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - James H. Naismith
- Rosalind Franklin Institute, Harwell Science and Innovation Campus, Didcot OX11 0FA, United Kingdom
- Division of Structural Biology, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, United Kingdom
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3
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Haymaker A, Nannenga BL. Advances and applications of microcrystal electron diffraction (MicroED). Curr Opin Struct Biol 2024; 84:102741. [PMID: 38086321 PMCID: PMC10882645 DOI: 10.1016/j.sbi.2023.102741] [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: 01/01/2023] [Revised: 11/17/2023] [Accepted: 11/19/2023] [Indexed: 02/08/2024]
Abstract
Microcrystal electron diffraction, commonly referred to as MicroED, has become a powerful tool for high-resolution structure determination. The method makes use of cryogenic transmission electron microscopes to collect electron diffraction data from crystals that are several orders of magnitude smaller than those used by other conventional diffraction techniques. MicroED has been used on a variety of samples including soluble proteins, membrane proteins, small organic molecules, and materials. Here we will review the MicroED method and highlight recent advancements to the methodology, as well as describe applications of MicroED within the fields of structural biology and chemical crystallography.
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Affiliation(s)
- Alison Haymaker
- Chemical Engineering, School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ 85287, USA; Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ, USA
| | - Brent L Nannenga
- Chemical Engineering, School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ 85287, USA; Center for Applied Structural Discovery, The Biodesign Institute, Arizona State University, Tempe, AZ, USA.
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4
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Moriscot C, Schoehn G, Housset D. High pressure freezing and cryo-sectioning can be used for protein structure determination by electron diffraction. Ultramicroscopy 2023; 254:113834. [PMID: 37666105 DOI: 10.1016/j.ultramic.2023.113834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 07/17/2023] [Accepted: 08/17/2023] [Indexed: 09/06/2023]
Abstract
Electron diffraction of three-dimensional nanometer sized crystals has emerged since 2013 as an efficient technique to solve the structure of both small organic molecules and model proteins. However, the major bottleneck of the technique when applied to protein samples is to produce nano-crystals that do not exceed 200 to 300 nm in at least one dimension and to deposit them on a grid while keeping the minimum amount of solvent around them. Since the presence of amorphous solvent around the crystal, necessary to preserve its integrity, increases the amount of diffuse scattering, thus degrading the signal-to noise ratio of the diffraction signal, other sample preparation strategies have been developed. One of them is the milling of thin crystal lamella using focused ion beam (FIB), which was successfully applied to several protein crystals. Here, we present a new approach that uses cryo-sectioning after high pressure freezing of dextran embedded protein crystals. 150 to 200 nm thick cryo-sections of hen egg white lysozyme tetragonal crystals where used for electron diffraction experiments. Complete diffraction data up to 2.9 Å resolution have been collected and the lysozyme structure has been solved by molecular replacement and refined against these data. Our data demonstrate that cryo-sectioning can preserve protein structure at high resolution and can be used as a new sample preparation technique for 3D electron diffraction experiments of protein crystals. The different orientations found in the crystal chips and their large number resulting from the cryo-sectioning make the latter an attractive approach as it combines advantages from both blotting approaches (number of crystals) and FIB-milling (controlled thickness and absence of solvent around the crystal).
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Affiliation(s)
| | - Guy Schoehn
- Univ. Grenoble Alpes, CNRS, CEA, IBS, F-38000 Grenoble, France
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5
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Parkhurst JM, Crawshaw AD, Siebert CA, Dumoux M, Owen CD, Nunes P, Waterman D, Glen T, Stuart DI, Naismith JH, Evans G. Investigation of the milling characteristics of different focused-ion-beam sources assessed by three-dimensional electron diffraction from crystal lamellae. IUCRJ 2023; 10:270-287. [PMID: 36952226 PMCID: PMC10161776 DOI: 10.1107/s2052252523001902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/01/2023] [Indexed: 05/06/2023]
Abstract
Three-dimensional electron diffraction (3DED) from nanocrystals of biological macromolecules requires the use of very small crystals. These are typically less than 300 nm-thick in the direction of the electron beam due to the strong interaction between electrons and matter. In recent years, focused-ion-beam (FIB) milling has been used in the preparation of thin samples for 3DED. These instruments typically use a gallium liquid metal ion source. Inductively coupled plasma (ICP) sources in principle offer faster milling rates. Little work has been done to quantify the damage these sources cause to delicate biological samples at cryogenic temperatures. Here, an analysis of the effect that milling with plasma FIB (pFIB) instrumentation has on lysozyme crystals is presented. This work evaluates both argon and xenon plasmas and compares them with crystals milled with a gallium source. A milling protocol was employed that utilizes an overtilt to produce wedge-shaped lamellae with a shallow thickness gradient which yielded very thin crystalline samples. 3DED data were then acquired and standard data-processing statistics were employed to assess the quality of the diffraction data. An upper bound to the depth of the pFIB-milling damage layer of between 42.5 and 50 nm is reported, corresponding to half the thickness of the thinnest lamellae that resulted in usable diffraction data. A lower bound of between 32.5 and 40 nm is also reported, based on a literature survey of the minimum amount of diffracting material required for 3DED.
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Affiliation(s)
- James M Parkhurst
- Rosalind Franklin Insititute, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QX, United Kingdom
| | - Adam D Crawshaw
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QS, United Kingdom
| | - C Alistair Siebert
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QS, United Kingdom
| | - Maud Dumoux
- Rosalind Franklin Insititute, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QX, United Kingdom
| | - C David Owen
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QS, United Kingdom
| | - Pedro Nunes
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QS, United Kingdom
| | - David Waterman
- Research Complex at Harwell, Harwell Science and Innovation Campus, Harwell, Oxford OX11 0FA, United Kingdom
| | - Thomas Glen
- Rosalind Franklin Insititute, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QX, United Kingdom
| | - David I Stuart
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QS, United Kingdom
| | - James H Naismith
- Rosalind Franklin Insititute, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QX, United Kingdom
| | - Gwyndaf Evans
- Rosalind Franklin Insititute, Harwell Science and Innovation Campus, Didcot, Oxford OX11 0QX, United Kingdom
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6
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Martynowycz MW, Shiriaeva A, Clabbers MTB, Nicolas WJ, Weaver SJ, Hattne J, Gonen T. A robust approach for MicroED sample preparation of lipidic cubic phase embedded membrane protein crystals. Nat Commun 2023; 14:1086. [PMID: 36841804 PMCID: PMC9968316 DOI: 10.1038/s41467-023-36733-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/15/2023] [Indexed: 02/26/2023] Open
Abstract
Crystallizing G protein-coupled receptors (GPCRs) in lipidic cubic phase (LCP) often yields crystals suited for the cryogenic electron microscopy (cryoEM) method microcrystal electron diffraction (MicroED). However, sample preparation is challenging. Embedded crystals cannot be targeted topologically. Here, we use an integrated fluorescence light microscope (iFLM) inside of a focused ion beam and scanning electron microscope (FIB-SEM) to identify fluorescently labeled GPCR crystals. Crystals are targeted using the iFLM and LCP is milled using a plasma focused ion beam (pFIB). The optimal ion source for preparing biological lamellae is identified using standard crystals of proteinase K. Lamellae prepared using either argon or xenon produced the highest quality data and structures. MicroED data are collected from the milled lamellae and the structures are determined. This study outlines a robust approach to identify and mill membrane protein crystals for MicroED and demonstrates plasma ion-beam milling is a powerful tool for preparing biological lamellae.
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Affiliation(s)
- Michael W Martynowycz
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Anna Shiriaeva
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Max T B Clabbers
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - William J Nicolas
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Sara J Weaver
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Johan Hattne
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA.,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA
| | - Tamir Gonen
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, 90095, USA. .,Department of Biological Chemistry, University of California, Los Angeles, CA, 90095, USA. .,Department of Physiology, University of California, Los Angeles, CA, 90095, USA.
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7
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Abstract
![]()
Electron crystallography
has a storied history which rivals that
of its more established X-ray-enabled counterpart. Recent advances
in data collection and analysis have sparked a renaissance in the
field, opening a new chapter for this venerable technique. Burgeoning
interest in electron crystallography has spawned innovative methods
described by various interchangeable labels (3D ED, MicroED, cRED,
etc.). This Review covers concepts and findings relevant to the practicing
crystallographer, with an emphasis on experiments aimed at using electron
diffraction to elucidate the atomic structure of three-dimensional
molecular crystals.
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Affiliation(s)
- Ambarneil Saha
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California 90095, United States.,Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - Shervin S Nia
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California 90095, United States.,Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
| | - José A Rodríguez
- UCLA-DOE Institute for Genomics and Proteomics, University of California, Los Angeles, Los Angeles, California 90095, United States.,Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, California 90095, United States
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8
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Clabbers MTB, Shiriaeva A, Gonen T. MicroED: conception, practice and future opportunities. IUCRJ 2022; 9:169-179. [PMID: 35371502 PMCID: PMC8895021 DOI: 10.1107/s2052252521013063] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 12/08/2021] [Indexed: 06/14/2023]
Abstract
This article documents a keynote seminar presented at the IUCr Congress in Prague, 2021. The cryo-EM method microcrystal electron diffraction is described and put in the context of macromolecular electron crystallography from its origins in 2D crystals of membrane proteins to today's application to 3D crystals a millionth the size of that needed for X-ray crystallography. Milestones in method development and applications are described with an outlook to the future.
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Affiliation(s)
- Max T. B. Clabbers
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA
| | - Anna Shiriaeva
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA
| | - Tamir Gonen
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095, USA
- Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095, USA
- Department of Physiology, University of California, Los Angeles, CA 90095, USA
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9
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Martynowycz MW, Clabbers MTB, Hattne J, Gonen T. Ab initio phasing macromolecular structures using electron-counted MicroED data. Nat Methods 2022; 19:724-729. [PMID: 35637302 PMCID: PMC9184278 DOI: 10.1038/s41592-022-01485-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Accepted: 04/07/2022] [Indexed: 12/31/2022]
Abstract
Structures of two globular proteins were determined ab initio using microcrystal electron diffraction (MicroED) data that were collected on a direct electron detector in counting mode. Microcrystals were identified using a scanning electron microscope (SEM) and thinned with a focused ion beam (FIB) to produce crystalline lamellae of ideal thickness. Continuous-rotation data were collected using an ultra-low exposure rate to enable electron counting in diffraction. For the first sample, triclinic lysozyme extending to a resolution of 0.87 Å, an ideal helical fragment of only three alanine residues provided initial phases. These phases were improved using density modification, allowing the entire atomic structure to be built automatically. A similar approach was successful on a second macromolecular sample, proteinase K, which is much larger and diffracted to a resolution of 1.5 Å. These results demonstrate that macromolecules can be determined to sub-ångström resolution by MicroED and that ab initio phasing can be successfully applied to counting data.
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Affiliation(s)
- Michael W. Martynowycz
- grid.19006.3e0000 0000 9632 6718Howard Hughes Medical Institute, University of California, Los Angeles, CA USA ,grid.19006.3e0000 0000 9632 6718Department of Biological Chemistry, University of California, Los Angeles, CA USA
| | - Max T. B. Clabbers
- grid.19006.3e0000 0000 9632 6718Department of Biological Chemistry, University of California, Los Angeles, CA USA
| | - Johan Hattne
- grid.19006.3e0000 0000 9632 6718Howard Hughes Medical Institute, University of California, Los Angeles, CA USA ,grid.19006.3e0000 0000 9632 6718Department of Biological Chemistry, University of California, Los Angeles, CA USA
| | - Tamir Gonen
- Howard Hughes Medical Institute, University of California, Los Angeles, CA, USA. .,Department of Biological Chemistry, University of California, Los Angeles, CA, USA. .,Department of Physiology, University of California, Los Angeles, CA, USA.
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10
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Martynowycz MW, Clabbers MTB, Unge J, Hattne J, Gonen T. Benchmarking the ideal sample thickness in cryo-EM. Proc Natl Acad Sci U S A 2021; 118:e2108884118. [PMID: 34873060 PMCID: PMC8670461 DOI: 10.1073/pnas.2108884118] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2021] [Indexed: 12/14/2022] Open
Abstract
The relationship between sample thickness and quality of data obtained is investigated by microcrystal electron diffraction (MicroED). Several electron microscopy (EM) grids containing proteinase K microcrystals of similar sizes from the same crystallization batch were prepared. Each grid was transferred into a focused ion beam and a scanning electron microscope in which the crystals were then systematically thinned into lamellae between 95- and 1,650-nm thick. MicroED data were collected at either 120-, 200-, or 300-kV accelerating voltages. Lamellae thicknesses were expressed in multiples of the corresponding inelastic mean free path to allow the results from different acceleration voltages to be compared. The quality of the data and subsequently determined structures were assessed using standard crystallographic measures. Structures were reliably determined with similar quality from crystalline lamellae up to twice the inelastic mean free path. Lower resolution diffraction was observed at three times the mean free path for all three accelerating voltages, but the data quality was insufficient to yield structures. Finally, no coherent diffraction was observed from lamellae thicker than four times the calculated inelastic mean free path. This study benchmarks the ideal specimen thickness with implications for all cryo-EM methods.
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Affiliation(s)
- Michael W Martynowycz
- HHMI, University of California, Los Angeles, CA 90095
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Max T B Clabbers
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Johan Unge
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Johan Hattne
- HHMI, University of California, Los Angeles, CA 90095
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Tamir Gonen
- HHMI, University of California, Los Angeles, CA 90095;
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
- Department of Physiology, University of California, Los Angeles, CA 90095
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11
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Gruene T, Mugnaioli E. 3D Electron Diffraction for Chemical Analysis: Instrumentation Developments and Innovative Applications. Chem Rev 2021; 121:11823-11834. [PMID: 34533919 PMCID: PMC8517952 DOI: 10.1021/acs.chemrev.1c00207] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Indexed: 01/26/2023]
Abstract
In the past few years, many exciting papers reported results based on crystal structure determination by electron diffraction. The aim of this review is to provide general and practical information to structural chemists interested in stepping into this emerging field. We discuss technical characteristics of electron microscopes for research units that would like to acquire their own instrumentation, as well as those practical aspects that appear different between X-ray and electron crystallography. We also include a discussion about applications where electron crystallography provides information that is different, and possibly complementary, with respect to what is available from X-ray crystallography.
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Affiliation(s)
- Tim Gruene
- University
of Vienna, Faculty of Chemistry,
Department of Inorganic Chemistry, AT-1090 Vienna, Austria
| | - Enrico Mugnaioli
- Center
for Nanotechnology Innovation@NEST, Istituto
Italiano di Tecnologia, Piazza S. Silvestro 12, IT-56127 Pisa, Italy
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12
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Martynowycz MW, Gonen T. Protocol for the use of focused ion-beam milling to prepare crystalline lamellae for microcrystal electron diffraction (MicroED). STAR Protoc 2021; 2:100686. [PMID: 34382014 PMCID: PMC8339237 DOI: 10.1016/j.xpro.2021.100686] [Citation(s) in RCA: 9] [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] [Indexed: 12/30/2022] Open
Abstract
We present an in-depth protocol to reproducibly prepare crystalline lamellae from protein crystals for subsequent microcrystal electron diffraction (MicroED) experiments. This protocol covers typical soluble proteins and membrane proteins embedded in dense media. Following these steps will allow the user to prepare crystalline lamellae for protein structure determination by MicroED. For complete details on the use and execution of this protocol, please refer to Martynowycz et al. (2019a, 2020a).
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Affiliation(s)
- Michael W. Martynowycz
- Howard Hughes Medical Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Tamir Gonen
- Howard Hughes Medical Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Biological Chemistry, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
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13
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Martynowycz MW, Shiriaeva A, Ge X, Hattne J, Nannenga BL, Cherezov V, Gonen T. MicroED structure of the human adenosine receptor determined from a single nanocrystal in LCP. Proc Natl Acad Sci U S A 2021; 118:e2106041118. [PMID: 34462357 PMCID: PMC8433539 DOI: 10.1073/pnas.2106041118] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
G protein-coupled receptors (GPCRs), or seven-transmembrane receptors, are a superfamily of membrane proteins that are critically important to physiological processes in the human body. Determining high-resolution structures of GPCRs without bound cognate signaling partners, such as a G protein, requires crystallization in lipidic cubic phase (LCP). GPCR crystals grown in LCP are often too small for traditional X-ray crystallography. These microcrystals are ideal for investigation by microcrystal electron diffraction (MicroED), but the gel-like nature of LCP makes traditional approaches to MicroED sample preparation insurmountable. Here, we show that the structure of a human A2A adenosine receptor can be determined by MicroED after converting the LCP into the sponge phase followed by focused ion-beam milling. We determined the structure of the A2A adenosine receptor to 2.8-Å resolution and resolved an antagonist in its orthosteric ligand-binding site, as well as four cholesterol molecules bound around the receptor. This study lays the groundwork for future structural studies of lipid-embedded membrane proteins by MicroED using single microcrystals that would be impossible with other crystallographic methods.
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Affiliation(s)
- Michael W Martynowycz
- HHMI, University of California, Los Angeles, CA 90095
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Anna Shiriaeva
- Bridge Institute, University of Southern California Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA 90007
- Department of Chemistry, University of Southern California, Los Angeles, CA 90007
| | - Xuanrui Ge
- Bridge Institute, University of Southern California Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA 90007
- Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90007
| | - Johan Hattne
- HHMI, University of California, Los Angeles, CA 90095
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Brent L Nannenga
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287
- Biodesign Center for Applied Structural Discovery, Biodesign Institute, Arizona State University, Tempe, AZ 85287
| | - Vadim Cherezov
- Bridge Institute, University of Southern California Michelson Center for Convergent Biosciences, University of Southern California, Los Angeles, CA 90007;
- Department of Chemistry, University of Southern California, Los Angeles, CA 90007
| | - Tamir Gonen
- HHMI, University of California, Los Angeles, CA 90095;
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
- Department of Physiology, University of California, Los Angeles, CA 90095
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14
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Zhao J, Xu H, Lebrette H, Carroni M, Taberman H, Högbom M, Zou X. A simple pressure-assisted method for MicroED specimen preparation. Nat Commun 2021; 12:5036. [PMID: 34413316 PMCID: PMC8377027 DOI: 10.1038/s41467-021-25335-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 07/19/2021] [Indexed: 11/16/2022] Open
Abstract
Micro-crystal electron diffraction (MicroED) has shown great potential for structure determination of macromolecular crystals too small for X-ray diffraction. However, specimen preparation remains a major bottleneck. Here, we report a simple method for preparing MicroED specimens, named Preassis, in which excess liquid is removed through an EM grid with the assistance of pressure. We show the ice thicknesses can be controlled by tuning the pressure in combination with EM grids with appropriate carbon hole sizes. Importantly, Preassis can handle a wide range of protein crystals grown in various buffer conditions including those with high viscosity, as well as samples with low crystal concentrations. Preassis is a simple and universal method for MicroED specimen preparation, and will significantly broaden the applications of MicroED.
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Affiliation(s)
- Jingjing Zhao
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden
| | - Hongyi Xu
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
| | - Hugo Lebrette
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Marta Carroni
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
- Science for Life Laboratory, Stockholm University, Solna, Sweden
| | - Helena Taberman
- Max Delbrück Centrum for Molecular Medicine, Berlin, Germany
- Macromolecular Crystallography, Helmholtz-Zentrum Berlin, Berlin, Germany
| | - Martin Högbom
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Xiaodong Zou
- Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, Sweden.
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15
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Bruhn JF, Scapin G, Cheng A, Mercado BQ, Waterman DG, Ganesh T, Dallakyan S, Read BN, Nieusma T, Lucier KW, Mayer ML, Chiang NJ, Poweleit N, McGilvray PT, Wilson TS, Mashore M, Hennessy C, Thomson S, Wang B, Potter CS, Carragher B. Small Molecule Microcrystal Electron Diffraction for the Pharmaceutical Industry-Lessons Learned From Examining Over Fifty Samples. Front Mol Biosci 2021; 8:648603. [PMID: 34327213 PMCID: PMC8313502 DOI: 10.3389/fmolb.2021.648603] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 04/16/2021] [Indexed: 11/13/2022] Open
Abstract
The emerging field of microcrystal electron diffraction (MicroED) is of great interest to industrial researchers working in the drug discovery and drug development space. The promise of being able to routinely solve high-resolution crystal structures without the need to grow large crystals is very appealing. Despite MicroED's exciting potential, adoption across the pharmaceutical industry has been slow, primarily owing to a lack of access to specialized equipment and expertise. Here we present our experience building a small molecule MicroED service pipeline for members of the pharmaceutical industry. In the past year, we have examined more than fifty small molecule samples submitted by our clients, the majority of which have yielded data suitable for structure solution. We also detail our experience determining small molecule MicroED structures of pharmaceutical interest and offer some insights into the typical experimental outcomes. This experience has led us to conclude that small molecule MicroED adoption will continue to grow within the pharmaceutical industry where it is able to rapidly provide structures inaccessible by other methods.
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Affiliation(s)
| | | | - Anchi Cheng
- NanoImaging Services, San Diego, CA, United States
| | - Brandon Q Mercado
- Department of Chemistry, Yale University, New Haven, CT, United States
| | - David G Waterman
- UKRI STFC Rutherford Appleton Laboratory, Didcot, United Kingdom.,CCP4, Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, United Kingdom
| | | | | | | | | | | | | | | | | | | | | | | | | | - Sean Thomson
- NanoImaging Services, San Diego, CA, United States
| | - Bo Wang
- Biogen, Cambridge, MA, United States
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16
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Jha KK, Gruza B, Chodkiewicz ML, Jelsch C, Dominiak PM. Refinements on electron diffraction data of β-glycine in MoPro: a quest for an improved structure model. J Appl Crystallogr 2021. [DOI: 10.1107/s160057672100580x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The advancement in 3D electron diffraction (3D ED) techniques that lead to a revolution in molecular structure determination using nano-sized crystals is now achieving atomic resolution. The structures can be obtained from 3D ED data with tools similar to those used for X-ray structure determination. In this context, the MoPro software, originally designed for structure and charge density refinements using X-ray diffraction data, has been adapted. Structure refinement on 3D ED data was achieved via implementation of electron scattering factors available in the literature and by application of the Mott–Bethe equation to X-ray scattering factors computed from the multipolar atom model. The multipolar model was parametrized using the transferable pseudoatom databanks ELMAM2 and UBDB. Applying the independent atom model (IAM), i.e. spherical neutral atom refinement, to 3D ED data on β-glycine in MoPro resulted in structure and refinement statistics comparable to those obtained from other well known software. Use of the transferred aspherical atom model (TAAM) led to improvement of the refinement statistics and a better fit of the model to the 3D ED data as compared with the spherical atom refinement. The anisotropic displacement parameters of non-H atoms appear underestimated by typically 0.003 Å2 for the non-H atoms in IAM refinement compared with TAAM. Thus, MoPro is shown to be an effective tool for crystal structure refinement on 3D ED data and allows use of a spherical or a multipolar atom model. Electron density databases can be readily transferred with no further modification needed when the Mott–Bethe equation is applied.
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17
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Clabbers MTB, Xu H. Macromolecular crystallography using microcrystal electron diffraction. Acta Crystallogr D Struct Biol 2021; 77:313-324. [PMID: 33645535 PMCID: PMC7919406 DOI: 10.1107/s2059798320016368] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 12/16/2020] [Indexed: 11/10/2022] Open
Abstract
Microcrystal electron diffraction (MicroED) has recently emerged as a promising method for macromolecular structure determination in structural biology. Since the first protein structure was determined in 2013, the method has been evolving rapidly. Several protein structures have been determined and various studies indicate that MicroED is capable of (i) revealing atomic structures with charges, (ii) solving new protein structures by molecular replacement, (iii) visualizing ligand-binding interactions and (iv) determining membrane-protein structures from microcrystals embedded in lipidic mesophases. However, further development and optimization is required to make MicroED experiments more accurate and more accessible to the structural biology community. Here, we provide an overview of the current status of the field, and highlight the ongoing development, to provide an indication of where the field may be going in the coming years. We anticipate that MicroED will become a robust method for macromolecular structure determination, complementing existing methods in structural biology.
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Affiliation(s)
- Max T. B. Clabbers
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden
| | - Hongyi Xu
- Department of Materials and Environmental Chemistry, Stockholm University, 106 91 Stockholm, Sweden
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18
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Blum TB, Housset D, Clabbers MTB, van Genderen E, Bacia-Verloop M, Zander U, McCarthy AA, Schoehn G, Ling WL, Abrahams JP. Statistically correcting dynamical electron scattering improves the refinement of protein nanocrystals, including charge refinement of coordinated metals. Acta Crystallogr D Struct Biol 2021; 77:75-85. [PMID: 33404527 PMCID: PMC7787111 DOI: 10.1107/s2059798320014540] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 11/02/2020] [Indexed: 11/10/2022] Open
Abstract
Electron diffraction allows protein structure determination when only nanosized crystals are available. Nevertheless, multiple elastic (or dynamical) scattering, which is prominent in electron diffraction, is a concern. Current methods for modeling dynamical scattering by multi-slice or Bloch wave approaches are not suitable for protein crystals because they are not designed to cope with large molecules. Here, dynamical scattering of nanocrystals of insulin, thermolysin and thaumatin was limited by collecting data from thin crystals. To accurately measure the weak diffraction signal from the few unit cells in the thin crystals, a low-noise hybrid pixel Timepix electron-counting detector was used. The remaining dynamical component was further reduced in refinement using a likelihood-based correction, which was introduced previously for analyzing electron diffraction data of small-molecule nanocrystals and was adapted here for protein crystals. The procedure is shown to notably improve the structural refinement, in one case allowing the location of solvent molecules. It also allowed refinement of the charge states of bound metal atoms, an important element in protein function, through B-factor analysis of the metal atoms and their ligands. These results clearly increase the value of macromolecular electron crystallography as a complementary structural biology technique.
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Affiliation(s)
- Thorsten B. Blum
- Department of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Dominique Housset
- Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Max T. B. Clabbers
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, 4058 Basel, Switzerland
| | - Eric van Genderen
- Department of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
| | - Maria Bacia-Verloop
- Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Ulrich Zander
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Andrew A. McCarthy
- European Molecular Biology Laboratory, 71 Avenue des Martyrs, 38042 Grenoble, France
| | - Guy Schoehn
- Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Wai Li Ling
- Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des Martyrs, 38000 Grenoble, France
| | - Jan Pieter Abrahams
- Department of Biology and Chemistry, Paul Scherrer Institute, 5232 Villigen, Switzerland
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Mattenstrasse 26, 4058 Basel, Switzerland
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19
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Martynowycz MW, Khan F, Hattne J, Abramson J, Gonen T. MicroED structure of lipid-embedded mammalian mitochondrial voltage-dependent anion channel. Proc Natl Acad Sci U S A 2020; 117:32380-32385. [PMID: 33293416 PMCID: PMC7768720 DOI: 10.1073/pnas.2020010117] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
A structure of the murine voltage-dependent anion channel (VDAC) was determined by microcrystal electron diffraction (MicroED). Microcrystals of an essential mutant of VDAC grew in a viscous bicelle suspension, making it unsuitable for conventional X-ray crystallography. Thin, plate-like crystals were identified using scanning-electron microscopy (SEM). Crystals were milled into thin lamellae using a focused-ion beam (FIB). MicroED data were collected from three crystal lamellae and merged for completeness. The refined structure revealed unmodeled densities between protein monomers, indicative of lipids that likely mediate contacts between the proteins in the crystal. This body of work demonstrates the effectiveness of milling membrane protein microcrystals grown in viscous media using a focused ion beam for subsequent structure determination by MicroED. This approach is well suited for samples that are intractable by X-ray crystallography. To our knowledge, the presented structure is a previously undescribed mutant of the membrane protein VDAC, crystallized in a lipid bicelle matrix and solved by MicroED.
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Affiliation(s)
- Michael W Martynowycz
- Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Farha Khan
- Department of Physiology, University of California, Los Angeles, CA 90095
| | - Johan Hattne
- Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
| | - Jeff Abramson
- Department of Physiology, University of California, Los Angeles, CA 90095
| | - Tamir Gonen
- Howard Hughes Medical Institute, University of California, Los Angeles, CA 90095;
- Department of Biological Chemistry, University of California, Los Angeles, CA 90095
- Department of Physiology, University of California, Los Angeles, CA 90095
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