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Kleywegt GJ, Adams PD, Butcher SJ, Lawson CL, Rohou A, Rosenthal PB, Subramaniam S, Topf M, Abbott S, Baldwin PR, Berrisford JM, Bricogne G, Choudhary P, Croll TI, Danev R, Ganesan SJ, Grant T, Gutmanas A, Henderson R, Heymann JB, Huiskonen JT, Istrate A, Kato T, Lander GC, Lok SM, Ludtke SJ, Murshudov GN, Pye R, Pintilie GD, Richardson JS, Sachse C, Salih O, Scheres SHW, Schroeder GF, Sorzano COS, Stagg SM, Wang Z, Warshamanage R, Westbrook JD, Winn MD, Young JY, Burley SK, Hoch JC, Kurisu G, Morris K, Patwardhan A, Velankar S. Community recommendations on cryoEM data archiving and validation. IUCRJ 2024; 11:140-151. [PMID: 38358351 PMCID: PMC10916293 DOI: 10.1107/s2052252524001246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Accepted: 02/06/2024] [Indexed: 02/16/2024]
Abstract
In January 2020, a workshop was held at EMBL-EBI (Hinxton, UK) to discuss data requirements for the deposition and validation of cryoEM structures, with a focus on single-particle analysis. The meeting was attended by 47 experts in data processing, model building and refinement, validation, and archiving of such structures. This report describes the workshop's motivation and history, the topics discussed, and the resulting consensus recommendations. Some challenges for future methods-development efforts in this area are also highlighted, as is the implementation to date of some of the recommendations.
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Affiliation(s)
| | - Paul D. Adams
- Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- University of California, Berkeley, CA, USA
| | | | | | | | | | | | - Maya Topf
- Birkbeck, University of London, London, United Kingdom
| | | | | | | | | | | | | | | | - Sai J. Ganesan
- University of California at San Francisco, San Francisco, CA, USA
| | | | | | | | | | | | | | | | | | | | | | | | - Ryan Pye
- EMBL-EBI, Cambridge, United Kingdom
| | | | | | | | | | | | | | | | | | - Zhe Wang
- EMBL-EBI, Cambridge, United Kingdom
| | | | | | - Martyn D. Winn
- Science and Technology Facilities Council, Research Complex at Harwell, Oxon, United Kingdom
| | - Jasmine Y. Young
- RCSB Protein Data Bank, The State University of New Jersey, NJ, USA
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2
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Kleywegt GJ, Adams PD, Butcher SJ, Lawson CL, Rohou A, Rosenthal PB, Subramaniam S, Topf M, Abbott S, Baldwin PR, Berrisford JM, Bricogne G, Choudhary P, Croll TI, Danev R, Ganesan SJ, Grant T, Gutmanas A, Henderson R, Heymann JB, Huiskonen JT, Istrate A, Kato T, Lander GC, Lok SM, Ludtke SJ, Murshudov GN, Pye R, Pintilie GD, Richardson JS, Sachse C, Salih O, Scheres SHW, Schroeder GF, Sorzano COS, Stagg SM, Wang Z, Warshamanage R, Westbrook JD, Winn MD, Young JY, Burley SK, Hoch JC, Kurisu G, Morris K, Patwardhan A, Velankar S. Community recommendations on cryoEM data archiving and validation: Outcomes of a wwPDB/EMDB workshop on cryoEM data management, deposition and validation. ARXIV 2024:arXiv:2311.17640v3. [PMID: 38076521 PMCID: PMC10705588] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
In January 2020, a workshop was held at EMBL-EBI (Hinxton, UK) to discuss data requirements for deposition and validation of cryoEM structures, with a focus on single-particle analysis. The meeting was attended by 47 experts in data processing, model building and refinement, validation, and archiving of such structures. This report describes the workshop's motivation and history, the topics discussed, and consensus recommendations resulting from the workshop. Some challenges for future methods-development efforts in this area are also highlighted, as is the implementation to date of some of the recommendations.
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Affiliation(s)
| | - Paul D Adams
- Lawrence Berkeley Laboratory, Berkeley, CA, USA and University of California, Berkeley, CA, USA
| | | | - Catherine L Lawson
- RCSB Protein Data Bank, Rutgers, The State University of New Jersey, USA
| | | | | | | | - Maya Topf
- Birkbeck, University of London, London, UK
| | | | | | | | | | | | | | | | - Sai J Ganesan
- University of California at San Francisco, San Francisco, CA, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - John D Westbrook
- RCSB Protein Data Bank, Rutgers, The State University of New Jersey, USA
| | - Martyn D Winn
- Science and Technology Facilities Council, Research Complex at Harwell, Oxon, UK
| | - Jasmine Y Young
- RCSB Protein Data Bank, Rutgers, The State University of New Jersey, USA
| | - Stephen K Burley
- RCSB Protein Data Bank, Rutgers, The State University of New Jersey, USA
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3
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Taheri A, Wang Z, Singal B, Guo F, Al-Bassam J. Cryo-EM structures of the tubulin cofactors reveal the molecular basis for the biogenesis of alpha/beta-tubulin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.29.577855. [PMID: 38405852 PMCID: PMC10889022 DOI: 10.1101/2024.01.29.577855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Microtubule polarity and dynamic polymerization originate from the self-association properties of the a-tubulin heterodimer. For decades, it has remained poorly understood how the tubulin cofactors, TBCD, TBCE, TBCC, and the Arl2 GTPase mediate a-tubulin biogenesis from α- and β-tubulins. Here, we use cryogenic electron microscopy to determine structures of tubulin cofactors bound to αβ-tubulin. These structures show that TBCD, TBCE, and Arl2 form a heterotrimeric cage-like TBC-DEG assembly around the a-tubulin heterodimer. TBCD wraps around Arl2 and almost entirely encircles -tubulin, while TBCE forms a lever arm that anchors along the other end of TBCD and rotates α-tubulin. Structures of the TBC-DEG-αβ-tubulin assemblies bound to TBCC reveal the clockwise rotation of the TBCE lever that twists a-tubulin by pulling its C-terminal tail while TBCD holds -tubulin in place. Altogether, these structures uncover transition states in αβ-tubulin biogenesis, suggesting a vise-like mechanism for the GTP-hydrolysis dependent a-tubulin biogenesis mediated by TBC-DEG and TBCC. These structures provide the first evidence of the critical functions of the tubulin cofactors as enzymes that regulate the invariant organization of αβ-tubulin, by catalyzing α- and β-tubulin assembly, disassembly, and subunit exchange which are crucial for regulating the polymerization capacities of αβ-tubulins into microtubules.
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4
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Beton JG, Mulvaney T, Cragnolini T, Topf M. Cryo-EM structure and B-factor refinement with ensemble representation. Nat Commun 2024; 15:444. [PMID: 38200043 PMCID: PMC10781738 DOI: 10.1038/s41467-023-44593-1] [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: 07/11/2022] [Accepted: 12/20/2023] [Indexed: 01/12/2024] Open
Abstract
Cryo-EM experiments produce images of macromolecular assemblies that are combined to produce three-dimensional density maps. Typically, atomic models of the constituent molecules are fitted into these maps, followed by a density-guided refinement. We introduce TEMPy-ReFF, a method for atomic structure refinement in cryo-EM density maps. Our method represents atomic positions as components of a Gaussian mixture model, utilising their variances as B-factors, which are used to derive an ensemble description. Extensively tested on a substantial dataset of 229 cryo-EM maps from EMDB ranging in resolution from 2.1-4.9 Å with corresponding PDB and CERES atomic models, our results demonstrate that TEMPy-ReFF ensembles provide a superior representation of cryo-EM maps. On a single-model basis, it performs similarly to the CERES re-refinement protocol, although there are cases where it provides a better fit to the map. Furthermore, our method enables the creation of composite maps free of boundary artefacts. TEMPy-ReFF is useful for better interpretation of flexible structures, such as those involving RNA, DNA or ligands.
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Affiliation(s)
- Joseph G Beton
- Leibniz Institute of Virology (LIV) and Universitätsklinikum Hamburg Eppendorf (UKE), Centre for Structural Systems Biology (CSSB), 22607, Hamburg, Germany
| | - Thomas Mulvaney
- Leibniz Institute of Virology (LIV) and Universitätsklinikum Hamburg Eppendorf (UKE), Centre for Structural Systems Biology (CSSB), 22607, Hamburg, Germany
| | - Tristan Cragnolini
- Leibniz Institute of Virology (LIV) and Universitätsklinikum Hamburg Eppendorf (UKE), Centre for Structural Systems Biology (CSSB), 22607, Hamburg, Germany
- Institute of Structural and Molecular Biology, Birkbeck, University of London, London, UK
| | - Maya Topf
- Leibniz Institute of Virology (LIV) and Universitätsklinikum Hamburg Eppendorf (UKE), Centre for Structural Systems Biology (CSSB), 22607, Hamburg, Germany.
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5
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Mulvaney T, Kretsch RC, Elliott L, Beton JG, Kryshtafovych A, Rigden DJ, Das R, Topf M. CASP15 cryo-EM protein and RNA targets: Refinement and analysis using experimental maps. Proteins 2023; 91:1935-1951. [PMID: 37994556 PMCID: PMC10697286 DOI: 10.1002/prot.26644] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 10/25/2023] [Accepted: 11/10/2023] [Indexed: 11/24/2023]
Abstract
CASP assessments primarily rely on comparing predicted coordinates with experimental reference structures. However, experimental structures by their nature are only models themselves-their construction involves a certain degree of subjectivity in interpreting density maps and translating them to atomic coordinates. Here, we directly utilized density maps to evaluate the predictions by employing a method for ranking the quality of protein chain predictions based on their fit into the experimental density. The fit-based ranking was found to correlate well with the CASP assessment scores. Overall, the evaluation against the density map indicated that the models are of high accuracy, and occasionally even better than the reference structure in some regions of the model. Local assessment of predicted side chains in a 1.52 Å resolution map showed that side-chains are sometimes poorly positioned. Additionally, the top 118 predictions associated with 9 protein target reference structures were selected for automated refinement, in addition to the top 40 predictions for 11 RNA targets. For both proteins and RNA, the refinement of CASP15 predictions resulted in structures that are close to the reference target structure. This refinement was successful despite large conformational changes often being required, showing that predictions from CASP-assessed methods could serve as a good starting point for building atomic models in cryo-EM maps for both proteins and RNA. Loop modeling continued to pose a challenge for predictors, and together with the lack of consensus amongst models in these regions suggests that modeling, in combination with model-fit to the density, holds the potential for identifying more flexible regions within the structure.
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Affiliation(s)
- Thomas Mulvaney
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Hamburg, Germany
- University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Rachael C Kretsch
- Biophysics Program, Stanford University School of Medicine, California, USA
| | - Luc Elliott
- Institute of Systems, Molecular & Integrative Biology, The University of Liverpool, Liverpool, UK
| | - Joseph G Beton
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Hamburg, Germany
| | | | - Daniel J Rigden
- Institute of Systems, Molecular & Integrative Biology, The University of Liverpool, Liverpool, UK
| | - Rhiju Das
- Biophysics Program, Stanford University School of Medicine, California, USA
- Department of Biochemistry, Stanford University School of Medicine, California, USA
- Howard Hughes Medical Institute, Stanford University, California, USA
| | - Maya Topf
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Hamburg, Germany
- University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
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6
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Semchonok DA, Kyrilis FL, Hamdi F, Kastritis PL. Cryo-EM of a heterogeneous biochemical fraction elucidates multiple protein complexes from a multicellular thermophilic eukaryote. J Struct Biol X 2023; 8:100094. [PMID: 37638207 PMCID: PMC10451023 DOI: 10.1016/j.yjsbx.2023.100094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 07/27/2023] [Accepted: 08/07/2023] [Indexed: 08/29/2023] Open
Abstract
Biomolecular complexes and their interactions govern cellular structure and function. Understanding their architecture is a prerequisite for dissecting the cell's inner workings, but their higher-order assembly is often transient and challenging for structural analysis. Here, we performed cryo-EM on a single, highly heterogeneous biochemical fraction derived from Chaetomium thermophilum cell extracts to visualize the biomolecular content of the multicellular eukaryote. After cryo-EM single-particle image processing, results showed that a simultaneous three-dimensional structural characterization of multiple chemically diverse biomacromolecules is feasible. Namely, the thermophilic, eukaryotic complexes of (a) ATP citrate-lyase, (b) Hsp90, (c) 20S proteasome, (d) Hsp60 and (e) UDP-glucose pyrophosphorylase were characterized. In total, all five complexes have been structurally dissected in a thermophilic eukaryote in a total imaged sample area of 190.64 μm2, and two, in particular, 20S proteasome and Hsp60, exhibit side-chain resolution features. The C. thermophilum Hsp60 near-atomic model was resolved at 3.46 Å (FSC = 0.143) and shows a hinge-like conformational change of its equatorial domain, highly similar to the one previously shown for its bacterial orthologue, GroEL. This work demonstrates that cryo-EM of cell extracts will greatly accelerate the structural analysis of cellular complexes and provide unprecedented opportunities to annotate architectures of biomolecules in a holistic approach.
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Affiliation(s)
- Dmitry A. Semchonok
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
| | - Fotis L. Kyrilis
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3, Halle/Saale, Germany
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece
| | - Farzad Hamdi
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
| | - Panagiotis L. Kastritis
- Interdisciplinary Research Center HALOmem, Charles Tanford Protein Center, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3a, Halle/Saale, Germany
- Institute of Biochemistry and Biotechnology, Martin Luther University Halle-Wittenberg, Kurt-Mothes-Straße 3, Halle/Saale, Germany
- Institute of Chemical Biology, National Hellenic Research Foundation, Athens, Greece
- Biozentrum, Martin Luther University Halle-Wittenberg, Weinbergweg 22, Halle/Saale, Germany
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7
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Miyashita O, Tama F. Advancing cryo-electron microscopy data analysis through accelerated simulation-based flexible fitting approaches. Curr Opin Struct Biol 2023; 82:102653. [PMID: 37451233 DOI: 10.1016/j.sbi.2023.102653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Revised: 05/30/2023] [Accepted: 06/19/2023] [Indexed: 07/18/2023]
Abstract
Flexible fitting based on molecular dynamics simulation is a technique for structure modeling from cryo-EM data. It has been utilized for nearly two decades, and while cryo-EM resolution has improved significantly, it remains a powerful approach that can provide structural and dynamical insights that are not directly accessible from experimental data alone. Molecular dynamics simulations provide a means to extract atomistic details of conformational changes that are encoded in cryo-EM data and can also assist in improving the quality of structural models. Additionally, molecular dynamics simulations enable the characterization of conformational heterogeneity in cryo-EM data. We will summarize the advancements made in these techniques and highlight recent developments in this field.
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Affiliation(s)
- Osamu Miyashita
- RIKEN Center for Computational Science, 6-7-1, Minatojima-minami-machi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
| | - Florence Tama
- RIKEN Center for Computational Science, 6-7-1, Minatojima-minami-machi, Chuo-ku, Kobe, Hyogo 650-0047, Japan; Department of Physics, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan; Institute of Transformative Bio-Molecules, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.
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8
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Mulvaney T, Kretsch RC, Elliott L, Beton J, Kryshtafovych A, Rigden DJ, Das R, Topf M. CASP15 cryoEM protein and RNA targets: refinement and analysis using experimental maps. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.07.552287. [PMID: 37609268 PMCID: PMC10441278 DOI: 10.1101/2023.08.07.552287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
CASP assessments primarily rely on comparing predicted coordinates with experimental reference structures. However, errors in the reference structures can potentially reduce the accuracy of the assessment. This issue is particularly prominent in cryoEM-determined structures, and therefore, in the assessment of CASP15 cryoEM targets, we directly utilized density maps to evaluate the predictions. A method for ranking the quality of protein chain predictions based on rigid fitting to experimental density was found to correlate well with the CASP assessment scores. Overall, the evaluation against the density map indicated that the models are of high accuracy although local assessment of predicted side chains in a 1.52 Å resolution map showed that side-chains are sometimes poorly positioned. The top 136 predictions associated with 9 protein target reference structures were selected for refinement, in addition to the top 40 predictions for 11 RNA targets. To this end, we have developed an automated hierarchical refinement pipeline in cryoEM maps. For both proteins and RNA, the refinement of CASP15 predictions resulted in structures that are close to the reference target structure, including some regions with better fit to the density. This refinement was successful despite large conformational changes and secondary structure element movements often being required, suggesting that predictions from CASP-assessed methods could serve as a good starting point for building atomic models in cryoEM maps for both proteins and RNA. Loop modeling continued to pose a challenge for predictors with even short loops failing to be accurately modeled or refined at times. The lack of consensus amongst models suggests that modeling holds the potential for identifying more flexible regions within the structure.
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9
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Marini G, Poland B, Leininger C, Lukoyanova N, Spielbauer D, Barry JK, Altier D, Lum A, Scolaro E, Ortega CP, Yalpani N, Sandahl G, Mabry T, Klever J, Nowatzki T, Zhao JZ, Sethi A, Kassa A, Crane V, Lu AL, Nelson ME, Eswar N, Topf M, Saibil HR. Structural journey of an insecticidal protein against western corn rootworm. Nat Commun 2023; 14:4171. [PMID: 37443175 PMCID: PMC10344926 DOI: 10.1038/s41467-023-39891-7] [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: 01/12/2023] [Accepted: 06/28/2023] [Indexed: 07/15/2023] Open
Abstract
The broad adoption of transgenic crops has revolutionized agriculture. However, resistance to insecticidal proteins by agricultural pests poses a continuous challenge to maintaining crop productivity and new proteins are urgently needed to replace those utilized for existing transgenic traits. We identified an insecticidal membrane attack complex/perforin (MACPF) protein, Mpf2Ba1, with strong activity against the devastating coleopteran pest western corn rootworm (WCR) and a novel site of action. Using an integrative structural biology approach, we determined monomeric, pre-pore and pore structures, revealing changes between structural states at high resolution. We discovered an assembly inhibition mechanism, a molecular switch that activates pre-pore oligomerization upon gut fluid incubation and solved the highest resolution MACPF pore structure to-date. Our findings demonstrate not only the utility of Mpf2Ba1 in the development of biotechnology solutions for protecting maize from WCR to promote food security, but also uncover previously unknown mechanistic principles of bacterial MACPF assembly.
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Affiliation(s)
- Guendalina Marini
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Brad Poland
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Chris Leininger
- Corteva Agriscience, Johnston, IA, 50131, USA
- Syngenta, Research Triangle Park, NC, 27709, USA
| | - Natalya Lukoyanova
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK
| | | | | | - Dan Altier
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Amy Lum
- Corteva Agriscience, Johnston, IA, 50131, USA
- Willow Biosciences, 319 N Bernardo Ave #4, Mountain View, CA, 94043, USA
| | | | - Claudia Pérez Ortega
- Corteva Agriscience, Johnston, IA, 50131, USA
- Hologic, Inc., 250 Campus Drive, Marlborough, MA, 01752, USA
| | - Nasser Yalpani
- Corteva Agriscience, Johnston, IA, 50131, USA
- Dept. of Biology, University of British Columbia Okanagan, 3187 University Way, Kelowna, BC, V1V 1V7, Canada
| | | | - Tim Mabry
- Corteva Agriscience, Ivesdale, IL, 61851, USA
| | | | | | | | - Amit Sethi
- Corteva Agriscience, Johnston, IA, 50131, USA
| | - Adane Kassa
- Corteva Agriscience, Johnston, IA, 50131, USA
| | | | - Albert L Lu
- Corteva Agriscience, Johnston, IA, 50131, USA
| | | | | | - Maya Topf
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK.
- Centre for Structural Systems Biology (CSSB), Leibniz-Institut für Virologie (LIV), Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany.
| | - Helen R Saibil
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet St, London, WC1E 7HX, UK.
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10
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Fujita J, Makino F, Asahara H, Moriguchi M, Kumano S, Anzai I, Kishikawa JI, Matsuura Y, Kato T, Namba K, Inoue T. Epoxidized graphene grid for highly efficient high-resolution cryoEM structural analysis. Sci Rep 2023; 13:2279. [PMID: 36755111 PMCID: PMC9908306 DOI: 10.1038/s41598-023-29396-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 02/03/2023] [Indexed: 02/10/2023] Open
Abstract
Functionalization of graphene is one of the most important fundamental technologies in a wide variety of fields including industry and biochemistry. We have successfully achieved a novel oxidative modification of graphene using photoactivated ClO2· as a mild oxidant and confirmed the oxidized graphene grid is storable with its functionality for at least three months under N2 atmosphere. Subsequent chemical functionalization enabled us to develop an epoxidized graphene grid (EG-grid™), which effectively adsorbs protein particles for electron cryomicroscopy (cryoEM) image analysis. The EG-grid dramatically improved the particle density and orientation distribution. The density maps of GroEL and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were reconstructed at 1.99 and 2.16 Å resolution from only 504 and 241 micrographs, respectively. A sample solution of 0.1 mg ml-1 was sufficient to reconstruct a 3.10 Å resolution map of SARS-CoV-2 spike protein from 1163 micrographs. The map resolutions of β-galactosidase and apoferritin easily reached 1.81 Å and 1.29 Å resolution, respectively, indicating its atomic-resolution imaging capability. Thus, the EG-grid will be an extremely powerful tool for highly efficient high-resolution cryoEM structural analysis of biological macromolecules.
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Affiliation(s)
- Junso Fujita
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,JEOL YOKOGUSHI Research Alliance Laboratories, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Fumiaki Makino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,JEOL YOKOGUSHI Research Alliance Laboratories, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,JEOL Ltd, 3-2-1 Musashino, Akishima, Tokyo, 196-8558, Japan
| | - Haruyasu Asahara
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Open and Transdisciplinary Research Initiatives, Osaka University, 2-8 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Maiko Moriguchi
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Shota Kumano
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Itsuki Anzai
- Department of Molecular Virology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Jun-Ichi Kishikawa
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Molecular Biosciences, Kyoto Sangyo University, Motoyama Kamigamo, Kita-ku, Kyoto, 603-8555, Japan
| | - Yoshiharu Matsuura
- Center for Infectious Disease Education and Research, Osaka University, 2-8 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Laboratory of Virus Control, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Takayuki Kato
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan. .,JEOL YOKOGUSHI Research Alliance Laboratories, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan. .,RIKEN Center for Biosystems Dynamics Research and SPring-8 Center, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Tsuyoshi Inoue
- Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka, 565-0871, Japan. .,Open and Transdisciplinary Research Initiatives, Osaka University, 2-8 Yamadaoka, Suita, Osaka, 565-0871, Japan. .,dotAqua Inc., 2-1 Yamadaoka, Suita, Osaka, Japan.
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11
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Sánchez Rodríguez F, Chojnowski G, Keegan RM, Rigden DJ. Using deep-learning predictions of inter-residue distances for model validation. Acta Crystallogr D Struct Biol 2022; 78:1412-1427. [PMID: 36458613 PMCID: PMC9716559 DOI: 10.1107/s2059798322010415] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/28/2022] [Indexed: 11/27/2022] Open
Abstract
Determination of protein structures typically entails building a model that satisfies the collected experimental observations and its deposition in the Protein Data Bank. Experimental limitations can lead to unavoidable uncertainties during the process of model building, which result in the introduction of errors into the deposited model. Many metrics are available for model validation, but most are limited to consideration of the physico-chemical aspects of the model or its match to the experimental data. The latest advances in the field of deep learning have enabled the increasingly accurate prediction of inter-residue distances, an advance which has played a pivotal role in the recent improvements observed in the field of protein ab initio modelling. Here, new validation methods are presented based on the use of these precise inter-residue distance predictions, which are compared with the distances observed in the protein model. Sequence-register errors are particularly clearly detected and the register shifts required for their correction can be reliably determined. The method is available in the ConKit package (https://www.conkit.org).
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Affiliation(s)
- Filomeno Sánchez Rodríguez
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom,Life Science, Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Grzegorz Chojnowski
- European Molecular Biology Laboratory, Hamburg Unit, Notkestrasse 85, 22607 Hamburg, Germany
| | - Ronan M. Keegan
- UKRI–STFC, Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
| | - Daniel J. Rigden
- Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom,Correspondence e-mail:
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12
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Beton JG, Cragnolini T, Kaleel M, Mulvaney T, Sweeney A, Topf M. Integrating model simulation tools and
cryo‐electron
microscopy. WIRES COMPUTATIONAL MOLECULAR SCIENCE 2022. [DOI: 10.1002/wcms.1642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Joseph George Beton
- Centre for Structural Systems Biology (CSSB) Leibniz‐Institut für Virologie (LIV) Hamburg Germany
| | - Tristan Cragnolini
- Institute of Structural and Molecular Biology, Birkbeck and University College London London UK
| | - Manaz Kaleel
- Centre for Structural Systems Biology (CSSB) Leibniz‐Institut für Virologie (LIV) Hamburg Germany
| | - Thomas Mulvaney
- Centre for Structural Systems Biology (CSSB) Leibniz‐Institut für Virologie (LIV) Hamburg Germany
| | - Aaron Sweeney
- Centre for Structural Systems Biology (CSSB) Leibniz‐Institut für Virologie (LIV) Hamburg Germany
| | - Maya Topf
- Centre for Structural Systems Biology (CSSB) Leibniz‐Institut für Virologie (LIV) Hamburg Germany
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13
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Joseph AP, Malhotra S, Burnley T, Winn MD. Overview and applications of map and model validation tools in the CCP-EM software suite. Faraday Discuss 2022; 240:196-209. [PMID: 35916020 PMCID: PMC9642004 DOI: 10.1039/d2fd00103a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cryogenic electron microscopy (cryo-EM) has recently been established as a powerful technique for solving macromolecular structures. Although the best resolutions achievable are improving, a significant majority of data are still resolved at resolutions worse than 3 Å, where it is non-trivial to build or fit atomic models. The map reconstructions and atomic models derived from the maps are also prone to errors accumulated through the different stages of data processing. Here, we highlight the need to evaluate both model geometry and fit to data at different resolutions. Assessment of cryo-EM structures from SARS-CoV-2 highlights a bias towards optimising the model geometry to agree with the most common conformations, compared to the agreement with data. We present the CoVal web service which provides multiple validation metrics to reflect the quality of atomic models derived from cryo-EM data of structures from SARS-CoV-2. We demonstrate that further refinement can lead to improvement of the agreement with data without the loss of geometric quality. We also discuss the recent CCP-EM developments aimed at addressing some of the current shortcomings.
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Affiliation(s)
- Agnel Praveen Joseph
- Scientific Computing Department, Science and Technology Facilities CouncilDidcot OX11 0FAUK
| | - Sony Malhotra
- Scientific Computing Department, Science and Technology Facilities CouncilDidcot OX11 0FAUK
| | - Tom Burnley
- Scientific Computing Department, Science and Technology Facilities CouncilDidcot OX11 0FAUK
| | - Martyn D. Winn
- Scientific Computing Department, Science and Technology Facilities CouncilDidcot OX11 0FAUK
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14
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Bouvier G, Bardiaux B, Pellarin R, Rapisarda C, Nilges M. Building Protein Atomic Models from Cryo-EM Density Maps and Residue Co-Evolution. Biomolecules 2022; 12:biom12091290. [PMID: 36139128 PMCID: PMC9496541 DOI: 10.3390/biom12091290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/01/2022] [Accepted: 09/09/2022] [Indexed: 11/16/2022] Open
Abstract
Electron cryo-microscopy (cryo-EM) has emerged as a powerful method by which to obtain three-dimensional (3D) structures of macromolecular complexes at atomic or near-atomic resolution. However, de novo building of atomic models from near-atomic resolution (3–5 Å) cryo-EM density maps is a challenging task, in particular because poorly resolved side-chain densities hamper sequence assignment by automatic procedures at a lower resolution. Furthermore, segmentation of EM density maps into individual subunits remains a difficult problem when the structure of the subunits is not known, or when significant conformational rearrangement occurs between the isolated and associated form of the subunits. To tackle these issues, we have developed a graph-based method to thread most of the C-α trace of the protein backbone into the EM density map. The EM density is described as a weighted graph such that the resulting minimum spanning tree encompasses the high-density regions of the map. A pruning algorithm cleans the tree and finds the most probable positions of the C-α atoms, by using side-chain density when available, as a collection of C-α trace fragments. By complementing experimental EM maps with contact predictions from sequence co-evolutionary information, we demonstrate that this approach can correctly segment EM maps into individual subunits and assign amino acid sequences to backbone traces to generate atomic models.
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Affiliation(s)
- Guillaume Bouvier
- Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, CNRS UMR 3528, 75015 Paris, France
- Correspondence: (G.B.); (B.B.)
| | - Benjamin Bardiaux
- Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, CNRS UMR 3528, 75015 Paris, France
- Correspondence: (G.B.); (B.B.)
| | - Riccardo Pellarin
- Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, CNRS UMR 3528, 75015 Paris, France
| | - Chiara Rapisarda
- Microbiologie Fondamentale et Pathogènicité, University of Bordeaux, CNRS UMR 5234, 33076 Bordeaux, France
- Institut Européen de Chimie et Biologie, University of Bordeaux, 33600 Pessac, France
| | - Michael Nilges
- Structural Bioinformatics Unit, Institut Pasteur, Université Paris Cité, CNRS UMR 3528, 75015 Paris, France
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15
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Klebl DP, Wang Y, Sobott F, Thompson RF, Muench SP. It started with a Cys: Spontaneous cysteine modification during cryo-EM grid preparation. Front Mol Biosci 2022; 9:945772. [PMID: 35992264 PMCID: PMC9389043 DOI: 10.3389/fmolb.2022.945772] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 06/27/2022] [Indexed: 12/31/2022] Open
Abstract
Advances in single particle cryo-EM data collection and processing have seen a significant rise in its use. However, the influences of the environment generated through grid preparation, by for example interactions of proteins with the air-water interface are poorly understood and can be a major hurdle in structure determination by cryo-EM. Initial interactions of proteins with the air-water interface occur quickly and proteins can adopt preferred orientation or partially unfold within hundreds of milliseconds. It has also been shown previously that thin-film layers create hydroxyl radicals. To investigate the potential this might have in cryo-EM sample preparation, we studied two proteins, HSPD1, and beta-galactosidase, and show that cysteine residues are modified in a time-dependent manner. In the case of both HSPD1 and beta-galactosidase, this putative oxidation is linked to partial protein unfolding, as well as more subtle structural changes. We show these modifications can be alleviated through increasing the speed of grid preparation, the addition of DTT, or by sequestering away from the AWI using continuous support films. We speculate that the modification is oxidation by reactive oxygen species which are formed and act at the air-water interface. Finally, we show grid preparation on a millisecond timescale outruns cysteine modification, showing that the reaction timescale is in the range of 100s to 1,000s milliseconds and offering an alternative approach to prevent spontaneous cysteine modification and its consequences during cryo-EM grid preparation.
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Affiliation(s)
- David P. Klebl
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Yiheng Wang
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Frank Sobott
- School of Molecular and Cellular Biology, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
| | - Rebecca F. Thompson
- School of Molecular and Cellular Biology, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
- *Correspondence: Rebecca F. Thompson, ; Stephen P. Muench,
| | - Stephen P. Muench
- School of Biomedical Sciences, Faculty of Biological Sciences & Astbury Centre for Structural and Molecular Biology, University of Leeds, Leeds, United Kingdom
- *Correspondence: Rebecca F. Thompson, ; Stephen P. Muench,
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16
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Lubbe L, Sewell BT, Woodward JD, Sturrock ED. Cryo-EM reveals mechanisms of angiotensin I-converting enzyme allostery and dimerization. EMBO J 2022; 41:e110550. [PMID: 35818993 PMCID: PMC9379546 DOI: 10.15252/embj.2021110550] [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: 12/29/2021] [Revised: 04/21/2022] [Accepted: 05/27/2022] [Indexed: 11/09/2022] Open
Abstract
Hypertension (high blood pressure) is a major risk factor for cardiovascular disease, which is the leading cause of death worldwide. The somatic isoform of angiotensin I‐converting enzyme (sACE) plays a critical role in blood pressure regulation, and ACE inhibitors are thus widely used to treat hypertension and cardiovascular disease. Our current understanding of sACE structure, dynamics, function, and inhibition has been limited because truncated, minimally glycosylated forms of sACE are typically used for X‐ray crystallography and molecular dynamics simulations. Here, we report the first cryo‐EM structures of full‐length, glycosylated, soluble sACE (sACES1211). Both monomeric and dimeric forms of the highly flexible apo enzyme were reconstructed from a single dataset. The N‐ and C‐terminal domains of monomeric sACES1211 were resolved at 3.7 and 4.1 Å, respectively, while the interacting N‐terminal domains responsible for dimer formation were resolved at 3.8 Å. Mechanisms are proposed for intradomain hinging, cooperativity, and homodimerization. Furthermore, the observation that both domains were in the open conformation has implications for the design of sACE modulators.
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Affiliation(s)
- Lizelle Lubbe
- Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
| | - Bryan Trevor Sewell
- Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa.,Electron Microscope Unit, University of Cape Town, Cape Town, South Africa
| | - Jeremy D Woodward
- Electron Microscope Unit, University of Cape Town, Cape Town, South Africa
| | - Edward D Sturrock
- Department of Integrative Biomedical Sciences, Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Cape Town, South Africa
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17
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Watanabe G, Lieber MR, Williams DR. Structural analysis of the basal state of the Artemis:DNA-PKcs complex. Nucleic Acids Res 2022; 50:7697-7720. [PMID: 35801871 PMCID: PMC9303282 DOI: 10.1093/nar/gkac564] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 06/05/2022] [Accepted: 06/17/2022] [Indexed: 01/17/2023] Open
Abstract
Artemis nuclease and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) are key components in nonhomologous DNA end joining (NHEJ), the major repair mechanism for double-strand DNA breaks. Artemis activation by DNA-PKcs resolves hairpin DNA ends formed during V(D)J recombination. Artemis deficiency disrupts development of adaptive immunity and leads to radiosensitive T- B- severe combined immunodeficiency (RS-SCID). An activated state of Artemis in complex with DNA-PK was solved by cryo-EM recently, which showed Artemis bound to the DNA. Here, we report that the pre-activated form (basal state) of the Artemis:DNA-PKcs complex is stable on an agarose-acrylamide gel system, and suitable for cryo-EM structural analysis. Structures show that the Artemis catalytic domain is dynamically positioned externally to DNA-PKcs prior to ABCDE autophosphorylation and show how both the catalytic and regulatory domains of Artemis interact with the N-HEAT and FAT domains of DNA-PKcs. We define a mutually exclusive binding site for Artemis and XRCC4 on DNA-PKcs and show that an XRCC4 peptide disrupts the Artemis:DNA-PKcs complex. All of the findings are useful in explaining how a hypomorphic L3062R missense mutation of DNA-PKcs could lead to insufficient Artemis activation, hence RS-SCID. Our results provide various target site candidates to design disruptors for Artemis:DNA-PKcs complex formation.
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Affiliation(s)
- Go Watanabe
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Computational & Molecular Biology, USC Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Ave, Rm. 5428, Los Angeles, CA 90089, USA
| | - Michael R Lieber
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Computational & Molecular Biology, USC Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Ave, Rm. 5428, Los Angeles, CA 90089, USA
| | - Dewight R Williams
- Eyring Materials Center, John Cowley Center for High Resolution Electron Microscopy, Arizona State University, Tempe, AZ 85281, USA
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18
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Chojnowski G. Sequence-assignment validation in cryo-EM models with checkMySequence. ACTA CRYSTALLOGRAPHICA SECTION D STRUCTURAL BIOLOGY 2022; 78:806-816. [PMID: 35775980 PMCID: PMC9248842 DOI: 10.1107/s2059798322005009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 05/10/2022] [Indexed: 01/18/2023]
Abstract
A new method, checkMySequence, for the fast and automated detection of register errors in protein models built into cryo-EM reconstructions is presented. The availability of new artificial intelligence-based protein-structure-prediction tools has radically changed the way that cryo-EM maps are interpreted, but it has not eliminated the challenges of map interpretation faced by a microscopist. Models will continue to be locally rebuilt and refined using interactive tools. This inevitably results in occasional errors, among which register shifts remain one of the most difficult to identify and correct. Here, checkMySequence, a fast, fully automated and parameter-free method for detecting register shifts in protein models built into cryo-EM maps, is introduced. It is shown that the method can assist model building in cases where poorer map resolution hinders visual interpretation. It is also shown that checkMySequence could have helped to avoid a widely discussed sequence-register error in a model of SARS-CoV-2 RNA-dependent RNA polymerase that was originally detected thanks to a visual residue-by-residue inspection by members of the structural biology community. The software is freely available at https://gitlab.com/gchojnowski/checkmysequence.
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19
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Wang Z, Patwardhan A, Kleywegt GJ. Validation analysis of EMDB entries. Acta Crystallogr D Struct Biol 2022; 78:542-552. [PMID: 35503203 PMCID: PMC9063848 DOI: 10.1107/s205979832200328x] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 03/23/2022] [Indexed: 11/17/2022] Open
Abstract
The Electron Microscopy Data Bank (EMDB) is the central archive of the electron cryo-microscopy (cryo-EM) community for storing and disseminating volume maps and tomograms. With input from the community, EMDB has developed new resources for the validation of cryo-EM structures, focusing on the quality of the volume data alone and that of the fit of any models, themselves archived in the Protein Data Bank (PDB), to the volume data. Based on recommendations from community experts, the validation resources are developed in a three-tiered system. Tier 1 covers an extensive and evolving set of validation metrics, including tried and tested metrics as well as more experimental ones, which are calculated for all EMDB entries and presented in the Validation Analysis (VA) web resource. This system is particularly useful for cryo-EM experts, both to validate individual structures and to assess the utility of new validation metrics. Tier 2 comprises a subset of the validation metrics covered by the VA resource that have been subjected to extensive testing and are considered to be useful for specialists as well as nonspecialists. These metrics are presented on the entry-specific web pages for the entire archive on the EMDB website. As more experience is gained with the metrics included in the VA resource, it is expected that consensus will emerge in the community regarding a subset that is suitable for inclusion in the tier 2 system. Tier 3, finally, consists of the validation reports and servers that are produced by the Worldwide Protein Data Bank (wwPDB) Consortium. Successful metrics from tier 2 will be proposed for inclusion in the wwPDB validation pipeline and reports. The details of the new resource are described, with an emphasis on the tier 1 system. The output of all three tiers is publicly available, either through the EMDB website (tiers 1 and 2) or through the wwPDB ftp sites (tier 3), although the content of all three will evolve over time (fastest for tier 1 and slowest for tier 3). It is our hope that these validation resources will help the cryo-EM community to obtain a better understanding of the quality and of the best ways to assess the quality of cryo-EM structures in EMDB and PDB.
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Affiliation(s)
- Zhe Wang
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL–EBI), Wellcome Genome Campus, Hinxton CB10 1SD, United Kingdom
| | - Ardan Patwardhan
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL–EBI), Wellcome Genome Campus, Hinxton CB10 1SD, United Kingdom
| | - Gerard J. Kleywegt
- European Molecular Biology Laboratory, European Bioinformatics Institute (EMBL–EBI), Wellcome Genome Campus, Hinxton CB10 1SD, United Kingdom
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20
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Kelly JJ, Tranter D, Pardon E, Chi G, Kramer H, Happonen L, Knee KM, Janz JM, Steyaert J, Bulawa C, Paavilainen VO, Huiskonen JT, Yue WW. Snapshots of actin and tubulin folding inside the TRiC chaperonin. Nat Struct Mol Biol 2022; 29:420-429. [PMID: 35449234 PMCID: PMC9113939 DOI: 10.1038/s41594-022-00755-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2021] [Accepted: 03/01/2022] [Indexed: 01/16/2023]
Abstract
The integrity of a cell's proteome depends on correct folding of polypeptides by chaperonins. The chaperonin TCP-1 ring complex (TRiC) acts as obligate folder for >10% of cytosolic proteins, including he cytoskeletal proteins actin and tubulin. Although its architecture and how it recognizes folding substrates are emerging from structural studies, the subsequent fate of substrates inside the TRiC chamber is not defined. We trapped endogenous human TRiC with substrates (actin, tubulin) and cochaperone (PhLP2A) at different folding stages, for structure determination by cryo-EM. The already-folded regions of client proteins are anchored at the chamber wall, positioning unstructured regions toward the central space to achieve their native fold. Substrates engage with different sections of the chamber during the folding cycle, coupled to TRiC open-and-close transitions. Further, the cochaperone PhLP2A modulates folding, acting as a molecular strut between substrate and TRiC chamber. Our structural snapshots piece together an emerging model of client protein folding within TRiC.
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Affiliation(s)
- John J Kelly
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Dale Tranter
- Institute of Biotechnology, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Gamma Chi
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Holger Kramer
- Biological Mass Spectrometry and Proteomics Facility, MRC London Institute of Medical Sciences, Imperial College London, Hammersmith Hospital Campus, London, UK
| | - Lotta Happonen
- Division of Infection Medicine, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Kelly M Knee
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., Cambridge, MA, USA
| | - Jay M Janz
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., Cambridge, MA, USA
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel (VUB), Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Christine Bulawa
- Pfizer Rare Disease Research Unit, Worldwide Research and Development, Pfizer Inc., Cambridge, MA, USA
| | - Ville O Paavilainen
- Institute of Biotechnology, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland
| | - Juha T Huiskonen
- Institute of Biotechnology, Helsinki Institute of Life Science HiLIFE, University of Helsinki, Helsinki, Finland.
- Molecular and Integrative Biosciences Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland.
- Division of Structural Biology, Wellcome Centre for Human Genetics, Roosevelt Drive, University of Oxford, Oxford, UK.
| | - Wyatt W Yue
- Centre for Medicines Discovery, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
- Biosciences Institute, Medical School, Newcastle University, Newcastle upon Tyne, UK.
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21
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Exploring cryo-electron microscopy with molecular dynamics. Biochem Soc Trans 2022; 50:569-581. [PMID: 35212361 DOI: 10.1042/bst20210485] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/31/2022] [Accepted: 02/02/2022] [Indexed: 11/17/2022]
Abstract
Single particle analysis cryo-electron microscopy (EM) and molecular dynamics (MD) have been complimentary methods since cryo-EM was first applied to the field of structural biology. The relationship started by biasing structural models to fit low-resolution cryo-EM maps of large macromolecular complexes not amenable to crystallization. The connection between cryo-EM and MD evolved as cryo-EM maps improved in resolution, allowing advanced sampling algorithms to simultaneously refine backbone and sidechains. Moving beyond a single static snapshot, modern inferencing approaches integrate cryo-EM and MD to generate structural ensembles from cryo-EM map data or directly from the particle images themselves. We summarize the recent history of MD innovations in the area of cryo-EM modeling. The merits for the myriad of MD based cryo-EM modeling methods are discussed, as well as, the discoveries that were made possible by the integration of molecular modeling with cryo-EM. Lastly, current challenges and potential opportunities are reviewed.
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22
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CR-I-TASSER: assemble protein structures from cryo-EM density maps using deep convolutional neural networks. Nat Methods 2022; 19:195-204. [PMID: 35132244 PMCID: PMC8852347 DOI: 10.1038/s41592-021-01389-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 12/17/2021] [Indexed: 11/19/2022]
Abstract
Cryo-electron microscopy (cryo-EM) has become a leading approach for protein structure determination, but it remains challenging to accurately model atomic structures with cryo-EM density maps. We propose a hybrid method, CR-I-TASSER, which integrates deep neural-network learning with I-TASSER assembly simulations for automated cryo-EM structure determination. The method is benchmarked on 778 proteins with simulated and experimental density maps, where CR-I-TASSER constructs models with a correct fold (TM-score>0.5) for 643 targets that is 64% higher than the best of other de novo and refinement-based approaches on high-resolution data samples. Detailed data analyses showed that the major advantage of CR-I-TASSER lies in the deep-learning based Cα position prediction, which significantly improves the threading template quality and therefore boosts the accuracy of final models through optimized fragment assembly simulations. These results demonstrate a new avenue to determine cryo-EM protein structures with high accuracy and robustness covering various target types and density-map resolutions.
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23
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Joseph AP, Olek M, Malhotra S, Zhang P, Cowtan K, Burnley T, Winn MD. Atomic model validation using the CCP-EM software suite. Acta Crystallogr D Struct Biol 2022; 78:152-161. [PMID: 35102881 PMCID: PMC8805302 DOI: 10.1107/s205979832101278x] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 12/01/2021] [Indexed: 12/02/2022] Open
Abstract
Recently, there has been a dramatic improvement in the quality and quantity of data derived using cryogenic electron microscopy (cryo-EM). This is also associated with a large increase in the number of atomic models built. Although the best resolutions that are achievable are improving, often the local resolution is variable, and a significant majority of data are still resolved at resolutions worse than 3 Å. Model building and refinement is often challenging at these resolutions, and hence atomic model validation becomes even more crucial to identify less reliable regions of the model. Here, a graphical user interface for atomic model validation, implemented in the CCP-EM software suite, is presented. It is aimed to develop this into a platform where users can access multiple complementary validation metrics that work across a range of resolutions and obtain a summary of evaluations. Based on the validation estimates from atomic models associated with cryo-EM structures from SARS-CoV-2, it was observed that models typically favor adopting the most common conformations over fitting the observations when compared with the model agreement with data. At low resolutions, the stereochemical quality may be favored over data fit, but care should be taken to ensure that the model agrees with the data in terms of resolvable features. It is demonstrated that further re-refinement can lead to improvement of the agreement with data without the loss of geometric quality. This also highlights the need for improved resolution-dependent weight optimization in model refinement and an effective test for overfitting that would help to guide the refinement process.
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Affiliation(s)
- Agnel Praveen Joseph
- Scientific Computing Department, Science and Technology Facilities Council, Didcot, United Kingdom
| | - Mateusz Olek
- Department of Chemistry, University of York, York, United Kingdom
- Electron BioImaging Center, Diamond Light Source, Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Sony Malhotra
- Scientific Computing Department, Science and Technology Facilities Council, Didcot, United Kingdom
| | - Peijun Zhang
- Electron BioImaging Center, Diamond Light Source, Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Kevin Cowtan
- Department of Chemistry, University of York, York, United Kingdom
| | - Tom Burnley
- Scientific Computing Department, Science and Technology Facilities Council, Didcot, United Kingdom
| | - Martyn D. Winn
- Scientific Computing Department, Science and Technology Facilities Council, Didcot, United Kingdom
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24
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Saibil HR. Cryo-EM in molecular and cellular biology. Mol Cell 2022; 82:274-284. [DOI: 10.1016/j.molcel.2021.12.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 12/13/2021] [Accepted: 12/14/2021] [Indexed: 11/16/2022]
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25
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Cragnolini T, Kryshtafovych A, Topf M. Cryo-EM targets in CASP14. Proteins 2021; 89:1949-1958. [PMID: 34398978 PMCID: PMC8630773 DOI: 10.1002/prot.26216] [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: 05/07/2021] [Revised: 07/27/2021] [Accepted: 08/06/2021] [Indexed: 11/22/2022]
Abstract
Structures of seven CASP14 targets were determined using cryo-electron microscopy (cryo-EM) technique with resolution between 2.1 and 3.8 Å. We provide an evaluation of the submitted models versus the experimental data (cryo-EM density maps) and experimental reference structures built into the maps. The accuracy of models is measured in terms of coordinate-to-density and coordinate-to-coordinate fit. A-posteriori refinement of the most accurate models in their corresponding cryo-EM density resulted in structures that are close to the reference structure, including some regions with better fit to the density. Regions that were found to be less "refineable" correlate well with regions of high diversity between the CASP models and low goodness-of-fit to density in the reference structure.
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Affiliation(s)
- Tristan Cragnolini
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, UK
| | | | - Maya Topf
- Center for Structural Systems Biology, Leibniz-Institut für Experimentelle Virologie and Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
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26
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Cook AD, Roberts AJ, Atherton J, Tewari R, Topf M, Moores CA. Cryo-EM structure of a microtubule-bound parasite kinesin motor and implications for its mechanism and inhibition. J Biol Chem 2021; 297:101063. [PMID: 34375637 PMCID: PMC8526983 DOI: 10.1016/j.jbc.2021.101063] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 07/23/2021] [Accepted: 08/05/2021] [Indexed: 11/25/2022] Open
Abstract
Plasmodium parasites cause malaria and are responsible annually for hundreds of thousands of deaths. Kinesins are a superfamily of microtubule-dependent ATPases that play important roles in the parasite replicative machinery, which is a potential target for antiparasite drugs. Kinesin-5, a molecular motor that cross-links microtubules, is an established antimitotic target in other disease contexts, but its mechanism in Plasmodium falciparum is unclear. Here, we characterized P. falciparum kinesin-5 (PfK5) using cryo-EM to determine the motor's nucleotide-dependent microtubule-bound structure and introduced 3D classification of individual motors into our microtubule image processing pipeline to maximize our structural insights. Despite sequence divergence in PfK5, the motor exhibits classical kinesin mechanochemistry, including ATP-induced subdomain rearrangement and cover neck bundle formation, consistent with its plus-ended directed motility. We also observed that an insertion in loop5 of the PfK5 motor domain creates a different environment in the well-characterized human kinesin-5 drug-binding site. Our data reveal the possibility for selective inhibition of PfK5 and can be used to inform future exploration of Plasmodium kinesins as antiparasite targets.
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Affiliation(s)
- Alexander D Cook
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom
| | - Anthony J Roberts
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom
| | - Joseph Atherton
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom
| | - Rita Tewari
- School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - Maya Topf
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck, University of London, London, United Kingdom.
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27
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Simpkin AJ, Winn MD, Rigden DJ, Keegan RM. Redeployment of automated MrBUMP search-model identification for map fitting in cryo-EM. Acta Crystallogr D Struct Biol 2021; 77:1378-1385. [PMID: 34726166 PMCID: PMC8561737 DOI: 10.1107/s2059798321009165] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Accepted: 09/03/2021] [Indexed: 11/22/2022] Open
Abstract
In crystallography, the phase problem can often be addressed by the careful preparation of molecular-replacement search models. This has led to the development of pipelines such as MrBUMP that can automatically identify homologous proteins from an input sequence and edit them to focus on the areas that are most conserved. Many of these approaches can be applied directly to cryo-EM to help discover, prepare and correctly place models (here called cryo-EM search models) into electrostatic potential maps. This can significantly reduce the amount of manual model building that is required for structure determination. Here, MrBUMP is repurposed to fit automatically obtained PDB-derived chains and domains into cryo-EM maps. MrBUMP was successfully able to identify and place cryo-EM search models across a range of resolutions. Methods such as map segmentation are also explored as potential routes to improved performance. Map segmentation was also found to improve the effectiveness of the pipeline for higher resolution (<8 Å) data sets.
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Affiliation(s)
- Adam J. Simpkin
- Institute of Structural, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Martyn D. Winn
- UKRI–STFC, Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
| | - Daniel J. Rigden
- Institute of Structural, Molecular and Integrative Biology, University of Liverpool, Liverpool L69 7ZB, United Kingdom
| | - Ronan M. Keegan
- UKRI–STFC, Rutherford Appleton Laboratory, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
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28
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Markert J, Zhou K, Luger K. SMARCAD1 is an ATP-dependent histone octamer exchange factor with de novo nucleosome assembly activity. SCIENCE ADVANCES 2021; 7:eabk2380. [PMID: 34652950 PMCID: PMC8519567 DOI: 10.1126/sciadv.abk2380] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The adenosine 5′-triphosphate (ATP)–dependent chromatin remodeler SMARCAD1 acts on nucleosomes during DNA replication, repair, and transcription, but despite its implication in disease, information on its function and biochemical activities is scarce. Chromatin remodelers use the energy of ATP hydrolysis to slide nucleosomes, evict histones, or exchange histone variants. Here, we show that SMARCAD1 transfers the entire histone octamer from one DNA segment to another in an ATP-dependent manner but is also capable of de novo nucleosome assembly from histone octamer because of its ability to simultaneously bind all histones. We present a low-resolution cryo–electron microscopy structure of SMARCAD1 in complex with a nucleosome and show that the adenosine triphosphatase domains engage their substrate unlike any other chromatin remodeler. Our biochemical and structural data provide mechanistic insights into SMARCAD1-induced nucleosome disassembly and reassembly.
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Affiliation(s)
- Jonathan Markert
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Keda Zhou
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Karolin Luger
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
- Corresponding author.
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29
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Smith SM, Larocque G, Wood KM, Morris KL, Roseman AM, Sessions RB, Royle SJ, Smith CJ. Multi-modal adaptor-clathrin contacts drive coated vesicle assembly. EMBO J 2021; 40:e108795. [PMID: 34487371 PMCID: PMC8488560 DOI: 10.15252/embj.2021108795] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 07/30/2021] [Accepted: 08/03/2021] [Indexed: 12/17/2022] Open
Abstract
Clathrin‐coated pits are formed by the recognition of membrane and cargo by the AP2 complex and the subsequent recruitment of clathrin triskelia. A role for AP2 in coated‐pit assembly beyond initial clathrin recruitment has not been explored. Clathrin binds the β2 subunit of AP2, and several binding sites have been identified, but our structural knowledge of these interactions is incomplete and their functional importance during endocytosis is unclear. Here, we analysed the cryo‐EM structure of clathrin cages assembled in the presence of β2 hinge‐appendage (β2HA). We find that the β2‐appendage binds in at least two positions in the cage, demonstrating that multi‐modal binding is a fundamental property of clathrin‐AP2 interactions. In one position, β2‐appendage cross‐links two adjacent terminal domains from different triskelia. Functional analysis of β2HA‐clathrin interactions reveals that endocytosis requires two clathrin interaction sites: a clathrin‐box motif on the hinge and the “sandwich site” on the appendage. We propose that β2‐appendage binding to more than one triskelion is a key feature of the system and likely explains why assembly is driven by AP2.
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Affiliation(s)
- Sarah M Smith
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Gabrielle Larocque
- Centre for Mechanochemical Cell Biology, Warwick Medical School, University of Warwick, Coventry, UK
| | | | - Kyle L Morris
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Alan M Roseman
- Division of Molecular and Cellular Function, School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | | | - Stephen J Royle
- Centre for Mechanochemical Cell Biology, Warwick Medical School, University of Warwick, Coventry, UK
| | - Corinne J Smith
- School of Life Sciences, University of Warwick, Coventry, UK
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30
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Pintilie G, Chiu W. Validation, analysis and annotation of cryo-EM structures. Acta Crystallogr D Struct Biol 2021; 77:1142-1152. [PMID: 34473085 PMCID: PMC8411978 DOI: 10.1107/s2059798321006069] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 06/09/2021] [Indexed: 11/08/2023] Open
Abstract
The process of turning 2D micrographs into 3D atomic models of the imaged macromolecules has been under rapid development and scrutiny in the field of cryo-EM. Here, some important methods for validation at several stages in this process are described. Firstly, how Fourier shell correlation of two independent maps and phase randomization beyond a certain frequency address the assessment of map resolution is reviewed. Techniques for local resolution estimation and map sharpening are also touched upon. The topic of validating models which are either built de novo or based on a known atomic structure fitted into a cryo-EM map is then approached. Map-model comparison using Q-scores and Fourier shell correlation plots is used to assure the agreement of the model with the observed map density. The importance of annotating the model with B factors to account for the resolvability of individual atoms in the map is illustrated. Finally, the timely topic of detecting and validating water molecules and metal ions in maps that have surpassed ∼2 Å resolution is described.
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Affiliation(s)
- Grigore Pintilie
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA 94305, USA
| | - Wah Chiu
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA 94305, USA
- Division of Cryo-EM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA 94025, USA
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31
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Malhotra S, Joseph AP, Thiyagalingam J, Topf M. Assessment of protein-protein interfaces in cryo-EM derived assemblies. Nat Commun 2021; 12:3399. [PMID: 34099703 PMCID: PMC8184972 DOI: 10.1038/s41467-021-23692-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 04/14/2021] [Indexed: 02/05/2023] Open
Abstract
Structures of macromolecular assemblies derived from cryo-EM maps often contain errors that become more abundant with decreasing resolution. Despite efforts in the cryo-EM community to develop metrics for map and atomistic model validation, thus far, no specific scoring metrics have been applied systematically to assess the interface between the assembly subunits. Here, we comprehensively assessed protein-protein interfaces in macromolecular assemblies derived by cryo-EM. To this end, we developed Protein Interface-score (PI-score), a density-independent machine learning-based metric, trained using the features of protein-protein interfaces in crystal structures. We evaluated 5873 interfaces in 1053 PDB-deposited cryo-EM models (including SARS-CoV-2 complexes), as well as the models submitted to CASP13 cryo-EM targets and the EM model challenge. We further inspected the interfaces associated with low-scores and found that some of those, especially in intermediate-to-low resolution (worse than 4 Å) structures, were not captured by density-based assessment scores. A combined score incorporating PI-score and fit-to-density score showed discriminatory power, allowing our method to provide a powerful complementary assessment tool for the ever-increasing number of complexes solved by cryo-EM.
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Affiliation(s)
- Sony Malhotra
- grid.4464.20000 0001 2161 2573Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London, UK ,grid.14467.30Scientific Computing Department, Science and Technology Facilities Council, Didcot, UK
| | - Agnel Praveen Joseph
- grid.14467.30Scientific Computing Department, Science and Technology Facilities Council, Didcot, UK
| | - Jeyan Thiyagalingam
- grid.14467.30Scientific Computing Department, Science and Technology Facilities Council, Didcot, UK
| | - Maya Topf
- grid.4464.20000 0001 2161 2573Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, London, UK ,grid.13648.380000 0001 2180 3484Centre for Structural Systems Biology, Leibniz-Institut für Experimentelle Virologie and Universitätsklinikum Hamburg-Eppendorf (UKE), Hamburg, Germany
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32
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Olek M, Joseph AP. Cryo-EM Map-Based Model Validation Using the False Discovery Rate Approach. Front Mol Biosci 2021; 8:652530. [PMID: 34084774 PMCID: PMC8167059 DOI: 10.3389/fmolb.2021.652530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/26/2021] [Indexed: 01/18/2023] Open
Abstract
Significant technological developments and increasing scientific interest in cryogenic electron microscopy (cryo-EM) has resulted in a rapid increase in the amount of data generated by these experiments and the derived atomic models. Robust measures for the validation of 3D reconstructions and atomic models are essential for appropriate interpretation of the data. The resolution of data and availability of software tools that work across a range of resolutions often limit the quality of derived models. Hence, the final atomic model is often incomplete or contains regions where atomic positions are less reliable or incorrectly built. Extensive manual pruning and local adjustments or rebuilding are usually required to address these issues. The presented research introduces a software tool for the validation of the backbone trace of atomic models built in the cryo-EM density maps. In this study, we use the false discovery rate analysis, which can be used to segregate molecular signals from the background. Each atomic position in the model can be associated with an FDR backbone validation score, which can be used to identify potential mistraced residues. We demonstrate that the proposed validation score is complementary to existing validation metrics and is useful especially in cases where the model is built in the maps having varying local resolution. We also discuss the application of the score for automated pruning of atomic models built ab-initio during the iterative model building process in Buccaneer. We have implemented this score in the CCP-EM software suite.
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Affiliation(s)
- Mateusz Olek
- Department of Chemistry, University of York, York, United Kingdom.,Electron BioImaging Center, Rutherford Appleton Laboratory, Didcot, United Kingdom
| | - Agnel Praveen Joseph
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot, United Kingdom
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33
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Croll TI, Diederichs K, Fischer F, Fyfe CD, Gao Y, Horrell S, Joseph AP, Kandler L, Kippes O, Kirsten F, Müller K, Nolte K, Payne AM, Reeves M, Richardson JS, Santoni G, Stäb S, Tronrud DE, von Soosten LC, Williams CJ, Thorn A. Making the invisible enemy visible. Nat Struct Mol Biol 2021; 28:404-408. [PMID: 33972785 DOI: 10.1038/s41594-021-00593-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
| | | | - Florens Fischer
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany.,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | | | - Yunyun Gao
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany.,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | | | | | - Luise Kandler
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany.,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Oliver Kippes
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany.,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Ferdinand Kirsten
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany.,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Konstantin Müller
- Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | - Kristopher Nolte
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany.,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | | | - Matthew Reeves
- Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | | | | | - Sabrina Stäb
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany.,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | | | - Lea C von Soosten
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany.,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany
| | | | - Andrea Thorn
- Institut für Nanostruktur und Festkörperphysik, Universität Hamburg, Hamburg, Germany. .,Rudolf-Virchow-Zentrum, Julius-Maximilians-Universität Würzburg, Würzburg, Germany.
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34
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Structure of the full-length human Pannexin1 channel and insights into its role in pyroptosis. Cell Discov 2021; 7:30. [PMID: 33947837 PMCID: PMC8096850 DOI: 10.1038/s41421-021-00259-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 03/10/2021] [Indexed: 12/11/2022] Open
Abstract
Pannexin1 (PANX1) is a large-pore ATP efflux channel with a broad distribution, which allows the exchange of molecules and ions smaller than 1 kDa between the cytoplasm and extracellular space. In this study, we show that in human macrophages PANX1 expression is upregulated by diverse stimuli that promote pyroptosis, which is reminiscent of the previously reported lipopolysaccharide-induced upregulation of PANX1 during inflammasome activation. To further elucidate the function of PANX1, we propose the full-length human Pannexin1 (hPANX1) model through cryo-electron microscopy (cryo-EM) and molecular dynamics (MD) simulation studies, establishing hPANX1 as a homo-heptamer and revealing that both the N-termini and C-termini protrude deeply into the channel pore funnel. MD simulations also elucidate key energetic features governing the channel that lay a foundation to understand the channel gating mechanism. Structural analyses, functional characterizations, and computational studies support the current hPANX1-MD model, suggesting the potential role of hPANX1 in pyroptosis during immune responses.
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35
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Zhang N, Shan H, Liu M, Li T, Luo R, Yang L, Qi L, Chu X, Su X, Wang R, Liu Y, Sun W, Shen QT. Structure and assembly of double-headed Sendai virus nucleocapsids. Commun Biol 2021; 4:494. [PMID: 33888861 PMCID: PMC8062630 DOI: 10.1038/s42003-021-02027-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Accepted: 03/23/2021] [Indexed: 01/17/2023] Open
Abstract
Paramyxoviruses, including the mumps virus, measles virus, Nipah virus and Sendai virus (SeV), have non-segmented single-stranded negative-sense RNA genomes which are encapsidated by nucleoproteins into helical nucleocapsids. Here, we reported a double-headed SeV nucleocapsid assembled in a tail-to-tail manner, and resolved its helical stems and clam-shaped joint at the respective resolutions of 2.9 and 3.9 Å, via cryo-electron microscopy. Our structures offer important insights into the mechanism of the helical polymerization, in particular via an unnoticed exchange of a N-terminal hole formed by three loops of nucleoproteins, and unveil the clam-shaped joint in a hyper-closed state for nucleocapsid dimerization. Direct visualization of the loop from the disordered C-terminal tail provides structural evidence that C-terminal tail is correlated to the curvature of nucleocapsid and links nucleocapsid condensation and genome replication and transcription with different assembly forms.
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Affiliation(s)
- Na Zhang
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Hong Shan
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Mingdong Liu
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Tianhao Li
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Rui Luo
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Liuyan Yang
- State Key Laboratory of Microbial Technology, Marine Biotechnology Research Center, Shandong University, Qingdao, China
- College of Marine Life Sciences, Ocean University of China, Qingdao, China
| | - Lei Qi
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China
| | - Xiaofeng Chu
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xin Su
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Rui Wang
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yunhui Liu
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Wenzhi Sun
- Chinese Institute for Brain Research, Beijing, China
- School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Qing-Tao Shen
- iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
- Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao, China.
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36
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Han X, Terashi G, Christoffer C, Chen S, Kihara D. VESPER: global and local cryo-EM map alignment using local density vectors. Nat Commun 2021; 12:2090. [PMID: 33828103 PMCID: PMC8027200 DOI: 10.1038/s41467-021-22401-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Accepted: 03/12/2021] [Indexed: 11/16/2022] Open
Abstract
An increasing number of density maps of biological macromolecules have been determined by cryo-electron microscopy (cryo-EM) and stored in the public database, EMDB. To interpret the structural information contained in EM density maps, alignment of maps is an essential step for structure modeling, comparison of maps, and for database search. Here, we developed VESPER, which captures the similarity of underlying molecular structures embedded in density maps by taking local gradient directions into consideration. Compared to existing methods, VESPER achieved substantially more accurate global and local alignment of maps as well as database retrieval.
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Affiliation(s)
- Xusi Han
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | - Genki Terashi
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA
| | | | - Siyang Chen
- Department of Computer Science, Purdue University, West Lafayette, IN, USA
| | - Daisuke Kihara
- Department of Biological Sciences, Purdue University, West Lafayette, IN, USA.
- Department of Computer Science, Purdue University, West Lafayette, IN, USA.
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37
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Gilbert RJC. Electron microscopy as a critical tool in the determination of pore forming mechanisms in proteins. Methods Enzymol 2021; 649:71-102. [PMID: 33712203 DOI: 10.1016/bs.mie.2021.01.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Electron microscopy has consistently played an important role in the description of pore-forming protein systems. The discovery of pore-forming proteins has depended on visualization of the structural pores formed by their oligomeric protein complexes, and as electron microscopy has advanced technologically so has the degree of insight it has been able to give. This review considers a large number of published studies of pore-forming complexes in prepore and pore states determined using single-particle cryo-electron microscopy. Sample isolation and preparation, imaging and image analysis, structure determination and optimization of results are all discussed alongside challenges which pore-forming proteins particularly present. The review also considers the use made of cryo-electron tomography to study pores within their membrane environment and which will prove an increasingly important approach for the future.
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Affiliation(s)
- Robert J C Gilbert
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom.
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38
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Zhang B, Zhang W, Pearce R, Zhang Y, Shen HB. Fitting Low-Resolution Protein Structures into Cryo-EM Density Maps by Multiobjective Optimization of Global and Local Correlations. J Phys Chem B 2021; 125:528-538. [PMID: 33397114 DOI: 10.1021/acs.jpcb.0c09903] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The rigid-body fitting of predicted structural models into cryo-electron microscopy (cryo-EM) density maps is a necessary procedure for density map-guided protein structure determination and prediction. We proposed a novel multiobjective optimization protocol, MOFIT, which performs a rigid-body density-map fitting based on particle swarm optimization (PSO). MOFIT was tested on a large set of 292 nonhomologous single-domain proteins. Starting from structural models predicted by I-TASSER, MOFIT achieved an average coordinate root-mean-square deviation of 2.46 Å, which was 1.57, 2.79, and 3.95 Å lower than three leading single-objective function-based methods, where the differences were statistically significant with p-values of 1.65 × 10-6, 6.36 × 10-8, and 6.44 × 10-11 calculated using two-tail Student's t tests. Detailed analyses showed that the major advantages of MOFIT lie in the multiobjective protocol and the extensive PSO search simulations guided by the composite objective functions, which integrates complementary correlation coefficients from the global structure, local fragments, and individual residues with the cryo-EM density maps.
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Affiliation(s)
- Biao Zhang
- Institute of Image Processing and Pattern Recognition, Shanghai Jiao Tong University, and Key Laboratory of System Control and Information Processing, Ministry of Education of China, Shanghai, China.,Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Wenyi Zhang
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310024, China
| | - Robin Pearce
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Yang Zhang
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Hong-Bin Shen
- Institute of Image Processing and Pattern Recognition, Shanghai Jiao Tong University, and Key Laboratory of System Control and Information Processing, Ministry of Education of China, Shanghai, China
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39
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Cragnolini T, Sahota H, Joseph AP, Sweeney A, Malhotra S, Vasishtan D, Topf M. TEMPy2: a Python library with improved 3D electron microscopy density-fitting and validation workflows. Acta Crystallogr D Struct Biol 2021; 77:41-47. [PMID: 33404524 PMCID: PMC7787107 DOI: 10.1107/s2059798320014928] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/10/2020] [Indexed: 11/10/2022] Open
Abstract
Structural determination of molecular complexes by cryo-EM requires large, often complex processing of the image data that are initially obtained. Here, TEMPy2, an update of the TEMPy package to process, optimize and assess cryo-EM maps and the structures fitted to them, is described. New optimization routines, comprehensive automated checks and workflows to perform these tasks are described.
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Affiliation(s)
- Tristan Cragnolini
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Harpal Sahota
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Agnel Praveen Joseph
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Aaron Sweeney
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Sony Malhotra
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
| | - Daven Vasishtan
- Oxford Particle Imaging Centre, Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Maya Topf
- Institute of Structural and Molecular Biology, Birkbeck, University College London, London, United Kingdom
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40
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Croll T, Diederichs K, Fischer F, Fyfe C, Gao Y, Horrell S, Joseph AP, Kandler L, Kippes O, Kirsten F, Müller K, Nolte K, Payne A, Reeves MG, Richardson J, Santoni G, Stäb S, Tronrud D, von Soosten L, Williams C, Thorn A. Making the invisible enemy visible. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2020:2020.10.07.307546. [PMID: 33052340 PMCID: PMC7553165 DOI: 10.1101/2020.10.07.307546] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
During the COVID-19 pandemic, structural biologists rushed to solve the structures of the 28 proteins encoded by the SARS-CoV-2 genome in order to understand the viral life cycle and enable structure-based drug design. In addition to the 204 previously solved structures from SARS-CoV-1, 548 structures covering 16 of the SARS-CoV-2 viral proteins have been released in a span of only 6 months. These structural models serve as the basis for research to understand how the virus hijacks human cells, for structure-based drug design, and to aid in the development of vaccines. However, errors often occur in even the most careful structure determination - and may be even more common among these structures, which were solved quickly and under immense pressure. The Coronavirus Structural Task Force has responded to this challenge by rapidly categorizing, evaluating and reviewing all of these experimental protein structures in order to help downstream users and original authors. In addition, the Task Force provided improved models for key structures online, which have been used by Folding@Home, OpenPandemics, the EU JEDI COVID-19 challenge and others.
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41
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Cowtan K, Metcalfe S, Bond P. Shift-field refinement of macromolecular atomic models. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2020; 76:1192-1200. [PMID: 33263325 PMCID: PMC7709196 DOI: 10.1107/s2059798320013170] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 09/29/2020] [Indexed: 11/11/2022]
Abstract
The aim of crystallographic structure solution is typically to determine an atomic model which accurately accounts for an observed diffraction pattern. A key step in this process is the refinement of the parameters of an initial model, which is most often determined by molecular replacement using another structure which is broadly similar to the structure of interest. In macromolecular crystallography, the resolution of the data is typically insufficient to determine the positional and uncertainty parameters for each individual atom, and so stereochemical information is used to supplement the observational data. Here, a new approach to refinement is evaluated in which a `shift field' is determined which describes changes to model parameters affecting whole regions of the model rather than individual atoms only, with the size of the affected region being a key parameter of the calculation which can be changed in accordance with the resolution of the data. It is demonstrated that this approach can improve the radius of convergence of the refinement calculation while also dramatically reducing the calculation time.
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Affiliation(s)
- K Cowtan
- Department of Chemistry, University of York, York, United Kingdom
| | - S Metcalfe
- Derpartment of Mechanical Engineering, McGill University, Montréal, Canada
| | - P Bond
- Department of Chemistry, University of York, York, United Kingdom
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42
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Junglas B, Orru R, Axt A, Siebenaller C, Steinchen W, Heidrich J, Hellmich UA, Hellmann N, Wolf E, Weber SAL, Schneider D. IM30 IDPs form a membrane-protective carpet upon super-complex disassembly. Commun Biol 2020; 3:595. [PMID: 33087858 PMCID: PMC7577978 DOI: 10.1038/s42003-020-01314-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Accepted: 09/22/2020] [Indexed: 12/26/2022] Open
Abstract
Members of the phage shock protein A (PspA) family, including the inner membrane-associated protein of 30 kDa (IM30), are suggested to stabilize stressed cellular membranes. Furthermore, IM30 is essential in thylakoid membrane-containing chloroplasts and cyanobacteria, where it is involved in membrane biogenesis and/or remodeling. While it is well known that PspA and IM30 bind to membranes, the mechanism of membrane stabilization is still enigmatic. Here we report that ring-shaped IM30 super-complexes disassemble on membranes, resulting in formation of a membrane-protecting protein carpet. Upon ring dissociation, the C-terminal domain of IM30 unfolds, and the protomers self-assemble on membranes. IM30 assemblies at membranes have been observed before in vivo and were associated with stress response in cyanobacteria and chloroplasts. These assemblies likely correspond to the here identified carpet structures. Our study defines the thus far enigmatic structural basis for the physiological function of IM30 and related proteins, including PspA, and highlights a hitherto unrecognized concept of membrane stabilization by intrinsically disordered proteins.
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Affiliation(s)
- Benedikt Junglas
- Department of Chemistry, Biochemistry, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
| | - Roberto Orru
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
| | - Amelie Axt
- Max Planck-Institute for Polymer Research, 55128, Mainz, Germany
- Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany
| | - Carmen Siebenaller
- Department of Chemistry, Biochemistry, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
| | - Wieland Steinchen
- Philipps-University Marburg, Center for Synthetic Microbiology (SYNMIKRO) and Department of Chemistry, 35032, Marburg, Germany
| | - Jennifer Heidrich
- Department of Chemistry, Biochemistry, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
| | - Ute A Hellmich
- Department of Chemistry, Biochemistry, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
- Centre for Biomolecular Magnetic Resonance (BMRZ), Goethe-University Frankfurt, 60438, Frankfurt, Germany
| | - Nadja Hellmann
- Department of Chemistry, Biochemistry, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
| | - Eva Wolf
- Institute of Molecular Physiology, Johannes Gutenberg University Mainz, 55128, Mainz, Germany
- Institute of Molecular Biology (IMB), 55128, Mainz, Germany
| | - Stefan A L Weber
- Max Planck-Institute for Polymer Research, 55128, Mainz, Germany
- Institute of Physics, Johannes Gutenberg University Mainz, 55099, Mainz, Germany
| | - Dirk Schneider
- Department of Chemistry, Biochemistry, Johannes Gutenberg University Mainz, 55128, Mainz, Germany.
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43
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Joseph AP, Lagerstedt I, Jakobi A, Burnley T, Patwardhan A, Topf M, Winn M. Comparing Cryo-EM Reconstructions and Validating Atomic Model Fit Using Difference Maps. J Chem Inf Model 2020; 60:2552-2560. [PMID: 32043355 PMCID: PMC7254831 DOI: 10.1021/acs.jcim.9b01103] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cryogenic electron microscopy (cryo-EM) is a powerful technique for determining structures of multiple conformational or compositional states of macromolecular assemblies involved in cellular processes. Recent technological developments have led to a leap in the resolution of many cryo-EM data sets, making atomic model building more common for data interpretation. We present a method for calculating differences between two cryo-EM maps or a map and a fitted atomic model. The proposed approach works by scaling the maps using amplitude matching in resolution shells. To account for variability in local resolution of cryo-EM data, we include a procedure for local amplitude scaling that enables appropriate scaling of local map contrast. The approach is implemented as a user-friendly tool in the CCP-EM software package. To obtain clean and interpretable differences, we propose a protocol involving steps to process the input maps and output differences. We demonstrate the utility of the method for identifying conformational and compositional differences including ligands. We also highlight the use of difference maps for evaluating atomic model fit in cryo-EM maps.
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Affiliation(s)
- Agnel Praveen Joseph
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
| | - Ingvar Lagerstedt
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Arjen Jakobi
- Kavli Institute of Nanoscience Delft (KIND), Department of Bionanoscienes, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands
| | - Tom Burnley
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
| | - Ardan Patwardhan
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Maya Topf
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, University of London, Malet Street, London WC1E 7HX, United Kingdom
| | - Martyn Winn
- Scientific Computing Department, Science and Technology Facilities Council, Research Complex at Harwell, Didcot OX11 0FA, United Kingdom
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44
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Peña A, Sweeney A, Cook AD, Locke J, Topf M, Moores CA. Structure of Microtubule-Trapped Human Kinesin-5 and Its Mechanism of Inhibition Revealed Using Cryoelectron Microscopy. Structure 2020; 28:450-457.e5. [PMID: 32084356 PMCID: PMC7139217 DOI: 10.1016/j.str.2020.01.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/12/2019] [Accepted: 01/28/2020] [Indexed: 01/23/2023]
Abstract
Kinesin-5 motors are vital mitotic spindle components, and disruption of their function perturbs cell division. We investigated the molecular mechanism of the human kinesin-5 inhibitor GSK-1, which allosterically promotes tight microtubule binding. GSK-1 inhibits monomeric human kinesin-5 ATPase and microtubule gliding activities, and promotes the motor's microtubule stabilization activity. Using cryoelectron microscopy, we determined the 3D structure of the microtubule-bound motor-GSK-1 at 3.8 Å overall resolution. The structure reveals that GSK-1 stabilizes the microtubule binding surface of the motor in an ATP-like conformation, while destabilizing regions of the motor around the empty nucleotide binding pocket. Density corresponding to GSK-1 is located between helix-α4 and helix-α6 in the motor domain at its interface with the microtubule. Using a combination of difference mapping and protein-ligand docking, we characterized the kinesin-5-GSK-1 interaction and further validated this binding site using mutagenesis. This work opens up new avenues of investigation of kinesin inhibition and spindle perturbation.
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Affiliation(s)
- Alejandro Peña
- Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | - Aaron Sweeney
- Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | - Alexander D Cook
- Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | - Julia Locke
- Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | - Maya Topf
- Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, UK.
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45
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Dodd T, Yan C, Ivanov I. Simulation-Based Methods for Model Building and Refinement in Cryoelectron Microscopy. J Chem Inf Model 2020; 60:2470-2483. [PMID: 32202798 DOI: 10.1021/acs.jcim.0c00087] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Advances in cryoelectron microscopy (cryo-EM) have revolutionized the structural investigation of large macromolecular assemblies. In this review, we first provide a broad overview of modeling methods used for flexible fitting of molecular models into cryo-EM density maps. We give special attention to approaches rooted in molecular simulations-atomistic molecular dynamics and Monte Carlo. Concise descriptions of the methods are given along with discussion of their advantages, limitations, and most popular alternatives. We also describe recent extensions of the widely used molecular dynamics flexible fitting (MDFF) method and discuss how different model-building techniques could be incorporated into new hybrid modeling schemes and simulation workflows. Finally, we provide two illustrative examples of model-building and refinement strategies employing MDFF, cascade MDFF, and RosettaCM. These examples come from recent cryo-EM studies that elucidated transcription preinitiation complexes and shed light on the functional roles of these assemblies in gene expression and gene regulation.
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Affiliation(s)
- Thomas Dodd
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States
| | - Chunli Yan
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States
| | - Ivaylo Ivanov
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30302, United States.,Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, Georgia 30302, United States
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46
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Rodríguez CF, Pal M, Muñoz-Hernandez H, Pearl LH, Llorca O. Modeling of a 14 kDa RUVBL2-Binding Domain with Medium Resolution Cryo-EM Density. J Chem Inf Model 2020; 60:2541-2551. [PMID: 32175735 DOI: 10.1021/acs.jcim.9b01095] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The number of high-resolution structures of protein complexes obtained using cryo-electron microscopy (cryo-EM) is increasing rapidly. Cryo-EM maps of large macromolecular complexes frequently contain regions resolved at different resolution levels, and modeling atomic structures de novo can be difficult for domains determined at worse than 5 Å in the absence of atomic information from other structures. Here we describe the details and step-by-step decisions in the strategy we followed to model the RUVBL2-binding domain (RBD), a 14 kDa domain at the C-terminus of RNA Polymerase II associated protein 3 (RPAP3) for which atomic information was not available. Modeling was performed on a cryo-EM map at 4.0-5.5 Å resolution, integrating information from secondary structure predictions, homology modeling, restraints from cross-linked mass spectrometry, and molecular dynamics (MD) in AMBER. Here, we compare our model with the structure of RBD determined by NMR to evaluate our strategy. We also perform new MD simulations to describe important residues mediating the interaction of RBD with RUVBL2 and analyze their conservation in RBD homologous domains. Our approach and its evaluation can serve as an example to address the analysis of medium resolution regions in cryo-EM maps.
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Affiliation(s)
- Carlos F Rodríguez
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Mohinder Pal
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, U.K
| | - Hugo Muñoz-Hernandez
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
| | - Laurence H Pearl
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton BN1 9RH, U.K
| | - Oscar Llorca
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Melchor Fernández Almagro 3, 28029 Madrid, Spain
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47
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Pintilie G, Zhang K, Su Z, Li S, Schmid MF, Chiu W. Measurement of atom resolvability in cryo-EM maps with Q-scores. Nat Methods 2020; 17:328-334. [PMID: 32042190 PMCID: PMC7446556 DOI: 10.1038/s41592-020-0731-1] [Citation(s) in RCA: 192] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 12/31/2019] [Indexed: 01/18/2023]
Abstract
Cryogenic electron microscopy (cryo-EM) maps are now at the point where resolvability of individual atoms can be achieved. However, resolvability is not necessarily uniform throughout the map. We introduce a quantitative parameter to characterize the resolvability of individual atoms in cryo-EM maps, the map Q-score. Q-scores can be calculated for atoms in proteins, nucleic acids, water, ligands and other solvent atoms, using models fitted to or derived from cryo-EM maps. Q-scores can also be averaged to represent larger features such as entire residues and nucleotides. Averaged over entire models, Q-scores correlate very well with the estimated resolution of cryo-EM maps for both protein and RNA. Assuming the models they are calculated from are well fitted to the map, Q-scores can be used as a measure of resolvability in cryo-EM maps at various scales, from entire macromolecules down to individual atoms. Q-score analysis of multiple cryo-EM maps of the same proteins derived from different laboratories confirms the reproducibility of structural features from side chains down to water and ion atoms.
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Affiliation(s)
- Grigore Pintilie
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA, USA.
| | - Kaiming Zhang
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Zhaoming Su
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Shanshan Li
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA, USA
| | - Michael F Schmid
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, USA
| | - Wah Chiu
- Department of Bioengineering, James H. Clark Center, Stanford University, Stanford, CA, USA.
- Division of CryoEM and Bioimaging, SSRL, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, CA, USA.
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48
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Tiwari SP, Chhabra S, Tama F, Miyashita O. Computational Protocol for Assessing the Optimal Pixel Size to Improve the Accuracy of Single-particle Cryo-electron Microscopy Maps. J Chem Inf Model 2020; 60:2570-2580. [PMID: 32003995 DOI: 10.1021/acs.jcim.9b01107] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Cryo-electron microscopy (cryo-EM) single-particle analysis has come a long way in achieving atomic-level resolution when imaging biomolecules. To obtain the best possible three-dimensional (3D) structure in cryo-EM, many parameters have to be carefully considered. Here we address the often-overlooked parameter of the pixel size, which describes the magnification of the image produced by the experiment. While efforts are made to refine and validate this parameter in the analysis of cryo-EM experimental data, there is no systematic protocol in place. Since the pixel size parameter can have an impact on the resolution and accuracy of a cryo-EM map, and the atomic resolution 3D structure models derived from it, we propose a computational protocol to estimate the appropriate pixel size parameter. In our protocol, we fit and refine atomic structures against cryo-EM maps at multiple pixel sizes. The resulting fitted and refined structures are evaluated using the GOAP (generalized orientation-dependent, all-atom statistical potential) score, which we found to perform better than other commonly used functions, such as Molprobity and the correlation coefficient from refinement. Finally, we describe the efficacy of this protocol in retrieving appropriate pixel sizes for several examples; simulated data based on yeast elongation factor 2 and experimental data from Gro-EL chaperone, beta-galactosidase, and the TRPV1 ion channel.
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Affiliation(s)
- Sandhya P Tiwari
- Computational Structural Biology Division, RIKEN Center for Computational Science, Kobe, Hyogo Prefecture 650-0047, Japan
| | - Sahil Chhabra
- Department of Chemistry, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109-1382, United States.,Michigan Institute for Computational Discovery and Engineering, University of Michigan-Ann Arbor, Ann Arbor, Michigan 48109-1382, United States
| | - Florence Tama
- Computational Structural Biology Division, RIKEN Center for Computational Science, Kobe, Hyogo Prefecture 650-0047, Japan.,Graduate School of Science, Department of Physics, Nagoya University, Nagoya, Aichi Prefecture 464-8601, Japan.,Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Nagoya, Aichi Prefecture 464-8601, Japan
| | - Osamu Miyashita
- Computational Structural Biology Division, RIKEN Center for Computational Science, Kobe, Hyogo Prefecture 650-0047, Japan
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49
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Kryshtafovych A, Malhotra S, Monastyrskyy B, Cragnolini T, Joseph AP, Chiu W, Topf M. Cryo-electron microscopy targets in CASP13: Overview and evaluation of results. Proteins 2019; 87:1128-1140. [PMID: 31576602 PMCID: PMC7197460 DOI: 10.1002/prot.25817] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 08/30/2019] [Accepted: 09/13/2019] [Indexed: 11/07/2022]
Abstract
Structures of seven CASP13 targets were determined using cryo-electron microscopy (cryo-EM) technique with resolution between 3.0 and 4.0 Å. We provide an overview of the experimentally derived structures and describe results of the numerical evaluation of the submitted models. The evaluation is carried out by comparing coordinates of models to those of reference structures (CASP-style evaluation), as well as checking goodness-of-fit of modeled structures to the cryo-EM density maps. The performance of contributing research groups in the CASP-style evaluation is measured in terms of backbone accuracy, all-atom local geometry and similarity of inter-subunit interfaces. The results on the cryo-EM targets are compared with those on the whole set of eighty CASP13 targets. A posteriori refinement of the best models in their corresponding cryo-EM density maps resulted in structures that are very close to the reference structure, including some regions with better fit to the density.
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Affiliation(s)
- Andriy Kryshtafovych
- Genome Center, University of California, Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Sony Malhotra
- Institute of Structural and Molecular Biology, Birkbeck, University College London, Malet Street, London WC1E 7HX, UK
| | - Bohdan Monastyrskyy
- Genome Center, University of California, Davis, 451 Health Sciences Drive, Davis, CA 95616, USA
| | - Tristan Cragnolini
- Institute of Structural and Molecular Biology, Birkbeck, University College London, Malet Street, London WC1E 7HX, UK
| | - Agnel-Praveen Joseph
- Institute of Structural and Molecular Biology, Birkbeck, University College London, Malet Street, London WC1E 7HX, UK
| | - Wah Chiu
- Department of Bioengineering, Microbiology and Immunology and Photon Science, Stanford University, James H. Clark Center, MC5447, 318 Campus Drive, Stanford, CA 94305, USA
| | - Maya Topf
- Institute of Structural and Molecular Biology, Birkbeck, University College London, Malet Street, London WC1E 7HX, UK
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50
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Ramírez-Aportela E, Mota J, Conesa P, Carazo JM, Sorzano COS. DeepRes: a new deep-learning- and aspect-based local resolution method for electron-microscopy maps. IUCRJ 2019; 6:1054-1063. [PMID: 31709061 PMCID: PMC6830216 DOI: 10.1107/s2052252519011692] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 08/22/2019] [Indexed: 05/26/2023]
Abstract
In this article, a method is presented to estimate a new local quality measure for 3D cryoEM maps that adopts the form of a 'local resolution' type of information. The algorithm (DeepRes) is based on deep-learning 3D feature detection. DeepRes is fully automatic and parameter-free, and avoids the issues of most current methods, such as their insensitivity to enhancements owing to B-factor sharpening (unless the 3D mask is changed), among others, which is an issue that has been virtually neglected in the cryoEM field until now. In this way, DeepRes can be applied to any map, detecting subtle changes in local quality after applying enhancement processes such as isotropic filters or substantially more complex procedures, such as model-based local sharpening, non-model-based methods or denoising, that may be very difficult to follow using current methods. It performs as a human observer expects. The comparison with traditional local resolution indicators is also addressed.
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Affiliation(s)
- Erney Ramírez-Aportela
- Biocomputing Unit, National Center for Biotechnology (CSIC), Calle Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Javier Mota
- Biocomputing Unit, National Center for Biotechnology (CSIC), Calle Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Pablo Conesa
- Biocomputing Unit, National Center for Biotechnology (CSIC), Calle Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Jose Maria Carazo
- Biocomputing Unit, National Center for Biotechnology (CSIC), Calle Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
| | - Carlos Oscar S. Sorzano
- Biocomputing Unit, National Center for Biotechnology (CSIC), Calle Darwin 3, Campus Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
- Universidad CEU San Pablo, Campus Urbanizacion Montepríncipe, Boadilla del Monte, 28668 Madrid, Spain
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