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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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2
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Studying membrane proteins with MicroED. Biochem Soc Trans 2022; 50:231-239. [PMID: 35191473 PMCID: PMC9022970 DOI: 10.1042/bst20210911] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 12/27/2022]
Abstract
The structural investigation of biological macromolecules is indispensable in understanding the molecular mechanisms underlying diseases. Several structural biology techniques have been introduced to unravel the structural facets of biomolecules. Among these, the electron cryomicroscopy (cryo-EM) method microcrystal electron diffraction (MicroED) has produced atomic resolution structures of important biological and small molecules. Since its inception in 2013, MicroED established a demonstrated ability for solving structures of difficult samples using vanishingly small crystals. However, membrane proteins remain the next big frontier for MicroED. The intrinsic properties of membrane proteins necessitate improved sample handling and imaging techniques to be developed and optimized for MicroED. Here, we summarize the milestones of electron crystallography of two-dimensional crystals leading to MicroED of three-dimensional crystals. Then, we focus on four different membrane protein families and discuss representatives from each family solved by MicroED.
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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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Microcrystal electron diffraction in macromolecular and pharmaceutical structure determination. DRUG DISCOVERY TODAY. TECHNOLOGIES 2021; 37:93-105. [PMID: 34895659 DOI: 10.1016/j.ddtec.2020.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 12/08/2020] [Accepted: 12/11/2020] [Indexed: 02/05/2023]
Abstract
Microcrystal electron diffraction (MicroED) has recently shown to be a promising technique for structure determination in structural biology and pharmaceutical chemistry. Here, we discuss the unique properties of electrons and motivate its use for diffraction experiments. We review the latest developments in MicroED, and illustrate its applications in macromolecular crystallography, fragment screening and structure guided drug discovery. We discuss the perspectives of MicroED in synthetic chemistry and pharmaceutical development. We anticipate that the rapid advances MicroED showcased here will promote further development of electron crystallography and open up new opportunities for drug discovery.
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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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Richards LS, Millán C, Miao J, Martynowycz MW, Sawaya MR, Gonen T, Borges RJ, Usón I, Rodriguez JA. Fragment-based determination of a proteinase K structure from MicroED data using ARCIMBOLDO_SHREDDER. Acta Crystallogr D Struct Biol 2020; 76:703-712. [PMID: 32744252 PMCID: PMC7397493 DOI: 10.1107/s2059798320008049] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Accepted: 06/16/2020] [Indexed: 12/15/2022] Open
Abstract
Structure determination of novel biological macromolecules by X-ray crystallography can be facilitated by the use of small structural fragments, some of only a few residues in length, as effective search models for molecular replacement to overcome the phase problem. Independence from the need for a complete pre-existing model with sequence similarity to the crystallized molecule is the primary appeal of ARCIMBOLDO, a suite of programs which employs this ab initio algorithm for phase determination. Here, the use of ARCIMBOLDO is investigated to overcome the phase problem with the electron cryomicroscopy (cryoEM) method known as microcrystal electron diffraction (MicroED). The results support the use of the ARCIMBOLDO_SHREDDER pipeline to provide phasing solutions for a structure of proteinase K from 1.6 Å resolution data using model fragments derived from the structures of proteins sharing a sequence identity of as low as 20%. ARCIMBOLDO_SHREDDER identified the most accurate polyalanine fragments from a set of distantly related sequence homologues. Alternatively, such templates were extracted in spherical volumes and given internal degrees of freedom to refine towards the target structure. Both modes relied on the rotation function in Phaser to identify or refine fragment models and its translation function to place them. Model completion from the placed fragments proceeded through phase combination of partial solutions and/or density modification and main-chain autotracing using SHELXE. The combined set of fragments was sufficient to arrive at a solution that resembled that determined by conventional molecular replacement using the known target structure as a search model. This approach obviates the need for a single, complete and highly accurate search model when phasing MicroED data, and permits the evaluation of large fragment libraries for this purpose.
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Affiliation(s)
- Logan S. Richards
- Department of Chemistry and Biochemistry; UCLA–DOE Institute for Genomics and Proteomics; STROBE, NSF Science and Technology Center, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Claudia Millán
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB–CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Jennifer Miao
- Department of Chemistry and Biochemistry; UCLA–DOE Institute for Genomics and Proteomics; STROBE, NSF Science and Technology Center, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Michael W. Martynowycz
- Howard Hughes Medical Institute, University of California Los Angeles (UCLA), Los Angeles, California, USA
- Department of Biological Chemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Michael R. Sawaya
- Howard Hughes Medical Institute, University of California Los Angeles (UCLA), Los Angeles, California, USA
- Department of Biological Chemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
| | - Tamir Gonen
- Howard Hughes Medical Institute, University of California Los Angeles (UCLA), Los Angeles, California, USA
- Department of Biological Chemistry, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
- Department of Physiology, University of California Los Angeles (UCLA), Los Angeles, California, USA
| | - Rafael J. Borges
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB–CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
| | - Isabel Usón
- Crystallographic Methods, Institute of Molecular Biology of Barcelona (IBMB–CSIC), Barcelona Science Park, Helix Building, Baldiri Reixac 15, 08028 Barcelona, Spain
- ICREA, Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08003 Barcelona, Spain
| | - Jose A. Rodriguez
- Department of Chemistry and Biochemistry; UCLA–DOE Institute for Genomics and Proteomics; STROBE, NSF Science and Technology Center, University of California Los Angeles (UCLA), Los Angeles, CA 90095, USA
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Martynowycz MW, Hattne J, Gonen T. Experimental Phasing of MicroED Data Using Radiation Damage. Structure 2020; 28:458-464.e2. [PMID: 32023481 PMCID: PMC7313391 DOI: 10.1016/j.str.2020.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 01/06/2020] [Accepted: 01/15/2020] [Indexed: 10/24/2022]
Abstract
We previously demonstrated that microcrystal electron diffraction (MicroED) can be used to determine atomic-resolution structures from vanishingly small three-dimensional crystals. Here, we present an example of an experimentally phased structure using only MicroED data. The structure of a seven-residue peptide is solved starting from differences to the diffraction intensities induced by structural changes due to radiation damage. The same wedge of reciprocal space was recorded twice by continuous-rotation MicroED from a set of 11 individual crystals. The data from the first pass were merged to make a "low-dose dataset." The data from the second pass were similarly merged to form a "damaged dataset." Differences between these two datasets were used to identify a single heavy-atom site from a Patterson difference map, and initial phases were generated. Finally, the structure was completed by iterative cycles of modeling and refinement.
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Affiliation(s)
- Michael W Martynowycz
- Howard Hughes Medical Institute, Departments of Biological Chemistry and Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Johan Hattne
- Howard Hughes Medical Institute, Departments of Biological Chemistry and Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Tamir Gonen
- Howard Hughes Medical Institute, Departments of Biological Chemistry and Physiology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA.
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Muller MP, Jiang T, Sun C, Lihan M, Pant S, Mahinthichaichan P, Trifan A, Tajkhorshid E. Characterization of Lipid-Protein Interactions and Lipid-Mediated Modulation of Membrane Protein Function through Molecular Simulation. Chem Rev 2019; 119:6086-6161. [PMID: 30978005 PMCID: PMC6506392 DOI: 10.1021/acs.chemrev.8b00608] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The cellular membrane constitutes one of the most fundamental compartments of a living cell, where key processes such as selective transport of material and exchange of information between the cell and its environment are mediated by proteins that are closely associated with the membrane. The heterogeneity of lipid composition of biological membranes and the effect of lipid molecules on the structure, dynamics, and function of membrane proteins are now widely recognized. Characterization of these functionally important lipid-protein interactions with experimental techniques is however still prohibitively challenging. Molecular dynamics (MD) simulations offer a powerful complementary approach with sufficient temporal and spatial resolutions to gain atomic-level structural information and energetics on lipid-protein interactions. In this review, we aim to provide a broad survey of MD simulations focusing on exploring lipid-protein interactions and characterizing lipid-modulated protein structure and dynamics that have been successful in providing novel insight into the mechanism of membrane protein function.
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Affiliation(s)
- Melanie P. Muller
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Tao Jiang
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Chang Sun
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Muyun Lihan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Shashank Pant
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Paween Mahinthichaichan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Anda Trifan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Emad Tajkhorshid
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology
- Department of Biochemistry
- Center for Biophysics and Quantitative Biology
- College of Medicine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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Clabbers MTB, Abrahams JP. Electron diffraction and three-dimensional crystallography for structural biology. CRYSTALLOGR REV 2018. [DOI: 10.1080/0889311x.2018.1446427] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Max T. B. Clabbers
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Basel, Switzerland
| | - Jan Pieter Abrahams
- Center for Cellular Imaging and NanoAnalytics (C-CINA), Biozentrum, University of Basel, Basel, Switzerland
- Department of Biology and Chemistry, Paul Scherrer Institute (PSI), Villigen PSI, Switzerland
- Institute of Biology Leiden (IBL), Leiden, Netherlands
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Martynowycz MW, Gonen T. From electron crystallography of 2D crystals to MicroED of 3D crystals. Curr Opin Colloid Interface Sci 2018; 34:9-16. [PMID: 30166936 PMCID: PMC6112780 DOI: 10.1016/j.cocis.2018.01.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Electron crystallography is widespread in material science applications, but for biological samples its use has been restricted to a handful of examples where two-dimensional (2D) crystals or helical samples were studied either by electron diffraction and/or imaging. Electron crystallography in cryoEM, was developed in the mid-1970s and used to solve the structure of several membrane proteins and some soluble proteins. In 2013, a new method for cryoEM was unveiled and named Micro-crystal Electron Diffraction, or MicroED, which is essentially three-dimensional (3D) electron crystallography of microscopic crystals. This method uses truly 3D crystals, that are about a billion times smaller than those typically used for X-ray crystallography, for electron diffraction studies. There are several important differences and some similarities between electron crystallography of 2D crystals and MicroED. In this review, we describe the development of these techniques, their similarities and differences, and offer our opinion of future directions in both fields.
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Affiliation(s)
- Michael W Martynowycz
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA
| | - Tamir Gonen
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147, USA.,Howard Hughes Medical Institute, Departments of Physiology and Biological Chemistry, David Geffen School of Medicine, University of California Los Angeles (UCLA), Los Angeles, California 90095, USA
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Nannenga BL, Gonen T. MicroED opens a new era for biological structure determination. Curr Opin Struct Biol 2016; 40:128-135. [PMID: 27701014 PMCID: PMC5656569 DOI: 10.1016/j.sbi.2016.09.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 08/19/2016] [Accepted: 09/14/2016] [Indexed: 01/07/2023]
Abstract
In 2013 we unveiled the cryo-electron microscopy (CryoEM) method of MicroED, or three-dimensional (3D) electron diffraction of microscopic crystals. Here tiny 3D crystals of biological material are used in an electron microscope for diffraction data collection under cryogenic conditions. The data is indexed, integrated, merged and scaled using standard X-ray crystallography software to determine structures at atomic resolution. In this review we provide an overview of the MicroED method and compare it with other CryoEM methods.
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Affiliation(s)
- Brent L Nannenga
- Chemical Engineering, School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, AZ 85287, USA
| | - Tamir Gonen
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
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Hattne J, Reyes FE, Nannenga BL, Shi D, de la Cruz MJ, Leslie AGW, Gonen T. MicroED data collection and processing. Acta Crystallogr A Found Adv 2015; 71:353-60. [PMID: 26131894 PMCID: PMC4487423 DOI: 10.1107/s2053273315010669] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 06/02/2015] [Indexed: 11/30/2022] Open
Abstract
MicroED, a method at the intersection of X-ray crystallography and electron cryo-microscopy, has rapidly progressed by exploiting advances in both fields and has already been successfully employed to determine the atomic structures of several proteins from sub-micron-sized, three-dimensional crystals. A major limiting factor in X-ray crystallography is the requirement for large and well ordered crystals. By permitting electron diffraction patterns to be collected from much smaller crystals, or even single well ordered domains of large crystals composed of several small mosaic blocks, MicroED has the potential to overcome the limiting size requirement and enable structural studies on difficult-to-crystallize samples. This communication details the steps for sample preparation, data collection and reduction necessary to obtain refined, high-resolution, three-dimensional models by MicroED, and presents some of its unique challenges.
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Affiliation(s)
- Johan Hattne
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Francis E. Reyes
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Brent L. Nannenga
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Dan Shi
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - M. Jason de la Cruz
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Andrew G. W. Leslie
- Medical Research Council Laboratory of Molecular Biology, Cambridge, England
| | - Tamir Gonen
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
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Shi D, Nannenga BL, Iadanza MG, Gonen T. Three-dimensional electron crystallography of protein microcrystals. eLife 2013; 2:e01345. [PMID: 24252878 PMCID: PMC3831942 DOI: 10.7554/elife.01345] [Citation(s) in RCA: 259] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We demonstrate that it is feasible to determine high-resolution protein structures by electron crystallography of three-dimensional crystals in an electron cryo-microscope (CryoEM). Lysozyme microcrystals were frozen on an electron microscopy grid, and electron diffraction data collected to 1.7 Å resolution. We developed a data collection protocol to collect a full-tilt series in electron diffraction to atomic resolution. A single tilt series contains up to 90 individual diffraction patterns collected from a single crystal with tilt angle increment of 0.1–1° and a total accumulated electron dose less than 10 electrons per angstrom squared. We indexed the data from three crystals and used them for structure determination of lysozyme by molecular replacement followed by crystallographic refinement to 2.9 Å resolution. This proof of principle paves the way for the implementation of a new technique, which we name ‘MicroED’, that may have wide applicability in structural biology. DOI:http://dx.doi.org/10.7554/eLife.01345.001 X-ray crystallography has been used to work out the atomic structure of a large number of proteins. In a typical X-ray crystallography experiment, a beam of X-rays is directed at a protein crystal, which scatters some of the X-ray photons to produce a diffraction pattern. The crystal is then rotated through a small angle and another diffraction pattern is recorded. Finally, after this process has been repeated enough times, it is possible to work backwards from the diffraction patterns to figure out the structure of the protein. The crystals used for X-ray crystallography must be large to withstand the damage caused by repeated exposure to the X-ray beam. However, some proteins do not form crystals at all, and others only form small crystals. It is possible to overcome this problem by using extremely short pulses of X-rays, but this requires a very large number of small crystals and ultrashort X-ray pulses are only available at a handful of research centers around the world. There is, therefore, a need for other approaches that can determine the structure of proteins that only form small crystals. Electron crystallography is similar to X-ray crystallography in that a protein crystal scatters a beam to produce a diffraction pattern. However, the interactions between the electrons in the beam and the crystal are much stronger than those between the X-ray photons and the crystal. This means that meaningful amounts of data can be collected from much smaller crystals. However, it is normally only possible to collect one diffraction pattern from each crystal because of beam induced damage. Researchers have developed methods to merge the diffraction patterns produced by hundreds of small crystals, but to date these techniques have only worked with very thin two-dimensional crystals that contain only one layer of the protein of interest. Now Shi et al. report a new approach to electron crystallography that works with very small three-dimensional crystals. Called MicroED, this technique involves placing the crystal in a transmission electron cryo-microscope, which is a fairly standard piece of equipment in many laboratories. The normal ‘low-dose’ electron beam in one of these microscopes would normally damage the crystal after a single diffraction pattern had been collected. However, Shi et al. realized that it was possible to obtain diffraction patterns without severely damaging the crystal if they dramatically reduced the normal low-dose electron beam. By reducing the electron dose by a factor of 200, it was possible to collect up to 90 diffraction patterns from the same, very small, three-dimensional crystal, and then—similar to what happens in X-ray crystallography—work backwards to figure out the structure of the protein. Shi et al. demonstrated the feasibility of the MicroED approach by using it to determine the structure of lysozyme, which is widely used as a test protein in crystallography, with a resolution of 2.9 Å. This proof-of principle study paves the way for crystallographers to study protein that cannot be studied with existing techniques. DOI:http://dx.doi.org/10.7554/eLife.01345.002
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Affiliation(s)
- Dan Shi
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, United States
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15
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Trinh MH, Odorico M, Pique ME, Teulon JM, Roberts VA, Ten Eyck LF, Getzoff ED, Parot P, Chen SWW, Pellequer JL. Computational reconstruction of multidomain proteins using atomic force microscopy data. Structure 2012; 20:113-20. [PMID: 22244760 DOI: 10.1016/j.str.2011.10.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Revised: 10/05/2011] [Accepted: 10/10/2011] [Indexed: 01/10/2023]
Abstract
Classical structural biology techniques face a great challenge to determine the structure at the atomic level of large and flexible macromolecules. We present a novel methodology that combines high-resolution AFM topographic images with atomic coordinates of proteins to assemble very large macromolecules or particles. Our method uses a two-step protocol: atomic coordinates of individual domains are docked beneath the molecular surface of the large macromolecule, and then each domain is assembled using a combinatorial search. The protocol was validated on three test cases: a simulated system of antibody structures; and two experimentally based test cases: Tobacco mosaic virus, a rod-shaped virus; and Aquaporin Z, a bacterial membrane protein. We have shown that AFM-intermediate resolution topography and partial surface data are useful constraints for building macromolecular assemblies. The protocol is applicable to multicomponent structures connected in the polypeptide chain or as disjoint molecules. The approach effectively increases the resolution of AFM beyond topographical information down to atomic-detail structures.
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Affiliation(s)
- Minh-Hieu Trinh
- CEA, iBEB, Department of Biochemistry and Nuclear Toxicology, F-30207 Bagnols sur Cèze, France
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Ubarretxena-Belandia I, Stokes DL. Membrane protein structure determination by electron crystallography. Curr Opin Struct Biol 2012; 22:520-8. [PMID: 22572457 DOI: 10.1016/j.sbi.2012.04.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2012] [Revised: 04/12/2012] [Accepted: 04/16/2012] [Indexed: 12/25/2022]
Abstract
During the past year, electron crystallography of membrane proteins has provided structural insights into the mechanism of several different transporters and into their interactions with lipid molecules within the bilayer. From a technical perspective there have been important advances in high-throughput screening of crystallization trials and in automated imaging of membrane crystals with the electron microscope. There have also been key developments in software, and in molecular replacement and phase extension methods designed to facilitate the process of structure determination.
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Affiliation(s)
- Iban Ubarretxena-Belandia
- Department of Structural and Chemical Biology, Mt. Sinai School of Medicine, New York, NY 10029, United States
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Pope CR, Unger VM. Electron crystallography--the waking beauty of structural biology. Curr Opin Struct Biol 2012; 22:514-9. [PMID: 22525160 DOI: 10.1016/j.sbi.2012.03.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 03/12/2012] [Accepted: 03/14/2012] [Indexed: 12/24/2022]
Abstract
Since its debut in the mid 1970s, electron crystallography has been a valuable alternative in the structure determination of biological macromolecules. Its reliance on single-layered or double-layered two-dimensionally ordered arrays and the ability to obtain structural information from small and disordered crystals make this approach particularly useful for the study of membrane proteins in a lipid bilayer environment. Despite its unique advantages, technological hurdles have kept electron crystallography from reaching its full potential. Addressing the issues, recent initiatives developed high-throughput pipelines for crystallization and screening. Adding progress in automating data collection, image analysis and phase extension methods, electron crystallography is poised to raise its profile and may lead the way in exploring the structural biology of macromolecular complexes.
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Affiliation(s)
- Christopher R Pope
- Department of Molecular Biosciences, Northwestern University, 2205 Campus Drive, Evanston, IL 60208, USA
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Jiang QX, Gonen T. The influence of lipids on voltage-gated ion channels. Curr Opin Struct Biol 2012; 22:529-36. [PMID: 22483432 PMCID: PMC3408884 DOI: 10.1016/j.sbi.2012.03.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 03/14/2012] [Indexed: 11/17/2022]
Abstract
Voltage-gated ion channels are responsible for transmitting electrochemical signals in both excitable and non-excitable cells. Structural studies of voltage-gated potassium and sodium channels by X-ray crystallography have revealed atomic details on their voltage-sensor domains (VSDs) and pore domains, and were put in context of disparate mechanistic views on the voltage-driven conformational changes in these proteins. Functional investigation of voltage-gated channels in membranes, however, showcased a mechanism of lipid-dependent gating for voltage-gated channels, suggesting that the lipids play an indispensible and critical role in the proper gating of many of these channels. Structure determination of membrane-embedded voltage-gated ion channels appears to be the next frontier in fully addressing the mechanism by which the VSDs control channel opening. Currently electron crystallography is the only structural biology method in which a membrane protein of interest is crystallized within a complete lipid-bilayer mimicking the native environment of a biological membrane. At a sufficiently high resolution, an electron crystallographic structure could reveal lipids, the channel and their mutual interactions at the atomic level. Electron crystallography is therefore a promising avenue toward understanding how lipids modulate channel activation through close association with the VSDs.
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Affiliation(s)
- Qiu-Xing Jiang
- Department of Cell Biology, UT Southwestern Medical Center, 5323 Harry Hines Blvd Dallas, TX 75390-9039, USA
- Correspondence to QXJ or TG: Qiu-Xing Jiang, PhD, , 214-648-6333 (phone); 214-648-8694 (fax) OR Tamir Gonen, PhD, , 571-209-4238 (phone); 571-291-6449 (fax)
| | - Tamir Gonen
- Janelia Farm Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
- Correspondence to QXJ or TG: Qiu-Xing Jiang, PhD, , 214-648-6333 (phone); 214-648-8694 (fax) OR Tamir Gonen, PhD, , 571-209-4238 (phone); 571-291-6449 (fax)
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Wisedchaisri G, Reichow SL, Gonen T. Advances in structural and functional analysis of membrane proteins by electron crystallography. Structure 2012; 19:1381-93. [PMID: 22000511 DOI: 10.1016/j.str.2011.09.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 09/01/2011] [Accepted: 09/06/2011] [Indexed: 12/27/2022]
Abstract
Electron crystallography is a powerful technique for the study of membrane protein structure and function in the lipid environment. When well-ordered two-dimensional crystals are obtained the structure of both protein and lipid can be determined and lipid-protein interactions analyzed. Protons and ionic charges can be visualized by electron crystallography and the protein of interest can be captured for structural analysis in a variety of physiologically distinct states. This review highlights the strengths of electron crystallography and the momentum that is building up in automation and the development of high throughput tools and methods for structural and functional analysis of membrane proteins by electron crystallography.
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Affiliation(s)
- Goragot Wisedchaisri
- Janelia Farm Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
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20
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High-resolution structures from low-resolution data. Nat Methods 2011. [DOI: 10.1038/nmeth.1692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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