1
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Xu XP, Cao W, Swift MF, Pandit NG, Huehn AE, Sindelar CV, De La Cruz EM, Hanein D, Volkmann N. High-resolution yeast actin structures indicate the molecular mechanism of actin filament stiffening by cations. Commun Chem 2024; 7:164. [PMID: 39079963 PMCID: PMC11289367 DOI: 10.1038/s42004-024-01243-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2024] [Accepted: 07/10/2024] [Indexed: 08/02/2024] Open
Abstract
Actin filament assembly and the regulation of its mechanical properties are fundamental processes essential for eukaryotic cell function. Residue E167 in vertebrate actins forms an inter-subunit salt bridge with residue K61 of the adjacent subunit. Saccharomyces cerevisiae actin filaments are more flexible than vertebrate filaments and have an alanine at this position (A167). Substitution of this alanine for a glutamic acid (A167E) confers Saccharomyces cerevisiae actin filaments with salt-dependent stiffness similar to vertebrate actins. We developed an optimized cryogenic electron microscopy workflow refining sample preparation and vitrification to obtain near-atomic resolution structures of wild-type and A167E mutant Saccharomyces cerevisiae actin filaments. The difference between these structures allowed us to pinpoint the potential binding site of a filament-associated cation that controls the stiffness of the filaments in vertebrate and A167E Saccharomyces cerevisiae actins. Through an analysis of previously published high-resolution reconstructions of vertebrate actin filaments, along with a newly determined high-resolution vertebrate actin structure in the absence of potassium, we identified a unique peak near residue 167 consistent with the binding of a magnesium ion. Our findings show how magnesium can contribute to filament stiffening by directly bridging actin subunits and allosterically affecting the orientation of the DNase-I binding loop of actin, which plays a regulatory role in modulating actin filament stiffness and interactions with regulatory proteins.
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Affiliation(s)
- Xiao-Ping Xu
- Scintillon Institute, 6868 Nancy Ridge Drive, San Diego, CA, 92121, USA
| | - Wenxiang Cao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Mark F Swift
- Scintillon Institute, 6868 Nancy Ridge Drive, San Diego, CA, 92121, USA
| | - Nandan G Pandit
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Andrew E Huehn
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Charles V Sindelar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Enrique M De La Cruz
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA
| | - Dorit Hanein
- Department of Chemistry and Biochemistry and Department of Biological Engineering, University of California, Santa Barbara, CA, 93106, USA.
| | - Niels Volkmann
- Department of Biological Engineering, Department of Electrical and Computer Engineering, Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA, 93106, USA.
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2
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Zhao H, Li J, Xiang Y, Malik S, Vartak SV, Veronezi GMB, Young N, Riney M, Kalchschmidt J, Conte A, Jung SK, Ramachandran S, Roeder RG, Shi Y, Casellas R, Asturias FJ. An IDR-dependent mechanism for nuclear receptor control of Mediator interaction with RNA polymerase II. Mol Cell 2024; 84:2648-2664.e10. [PMID: 38955181 PMCID: PMC11283359 DOI: 10.1016/j.molcel.2024.06.006] [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: 06/28/2023] [Revised: 02/29/2024] [Accepted: 06/07/2024] [Indexed: 07/04/2024]
Abstract
The essential Mediator (MED) coactivator complex plays a well-understood role in regulation of basal transcription in all eukaryotes, but the mechanism underlying its role in activator-dependent transcription remains unknown. We investigated modulation of metazoan MED interaction with RNA polymerase II (RNA Pol II) by antagonistic effects of the MED26 subunit and the CDK8 kinase module (CKM). Biochemical analysis of CKM-MED showed that the CKM blocks binding of the RNA Pol II carboxy-terminal domain (CTD), preventing RNA Pol II interaction. This restriction is eliminated by nuclear receptor (NR) binding to CKM-MED, which enables CTD binding in a MED26-dependent manner. Cryoelectron microscopy (cryo-EM) and crosslinking-mass spectrometry (XL-MS) revealed that the structural basis for modulation of CTD interaction with MED relates to a large intrinsically disordered region (IDR) in CKM subunit MED13 that blocks MED26 and CTD interaction with MED but is repositioned upon NR binding. Hence, NRs can control transcription initiation by priming CKM-MED for MED26-dependent RNA Pol II interaction.
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Affiliation(s)
- Haiyan Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO 80045, USA
| | - Jiaqin Li
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO 80045, USA
| | - Yufei Xiang
- Center of Protein Engineering and Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Sohail Malik
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, NY 10065, USA
| | | | - Giovana M B Veronezi
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO 80045, USA
| | - Natalie Young
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO 80045, USA
| | - McKayla Riney
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO 80045, USA
| | | | - Andrea Conte
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Seol Kyoung Jung
- Biodata Mining and Discovery Section, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Srinivas Ramachandran
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado Anschutz Medical School, Aurora, CO 80045, USA
| | - Robert G Roeder
- Laboratory of Biochemistry and Molecular Biology, Rockefeller University, New York, NY 10065, USA
| | - Yi Shi
- Center of Protein Engineering and Therapeutics, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Rafael Casellas
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD 20892, USA
| | - Francisco J Asturias
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO 80045, USA.
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3
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Roldán D, Redenbach C, Schladitz K, Kübel C, Schlabach S. Image quality evaluation for FIB-SEM images. J Microsc 2024; 293:98-117. [PMID: 38112173 DOI: 10.1111/jmi.13254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 12/20/2023]
Abstract
Focused ion beam scanning electron microscopy (FIB-SEM) tomography is a serial sectioning technique where an FIB mills off slices from the material sample that is being analysed. After every slicing, an SEM image is taken showing the newly exposed layer of the sample. By combining all slices in a stack, a 3D image of the material is generated. However, specific artefacts caused by the imaging technique distort the images, hampering the morphological analysis of the structure. Typical quality problems in microscopy imaging are noise and lack of contrast or focus. Moreover, specific artefacts are caused by the FIB milling, namely, curtaining and charging artefacts. We propose quality indices for the evaluation of the quality of FIB-SEM data sets. The indices are validated on real and experimental data of different structures and materials.
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Affiliation(s)
| | | | - Katja Schladitz
- Fraunhofer Institute of Industrial Mathematics, Kaiserslautern, Germany
| | - Christian Kübel
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
- Research group in-situ electron microscopy, Joint Research Laboratory Nanomaterials, Department of Materials & Earth Sciences, Technical University Darmstadt, Darmstadt, Germany
| | - Sabine Schlabach
- Institute of Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
- Karlsruhe Nano Micro Facility (KNMFi), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
- Institute for Applied Materials (IAM), Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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4
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Cordoba JJ, Mullins EA, Salay LE, Eichman BF, Chazin WJ. Flexibility and Distributive Synthesis Regulate RNA Priming and Handoff in Human DNA Polymerase α-Primase. J Mol Biol 2023; 435:168330. [PMID: 37884206 PMCID: PMC10872500 DOI: 10.1016/j.jmb.2023.168330] [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: 08/01/2023] [Revised: 09/22/2023] [Accepted: 10/18/2023] [Indexed: 10/28/2023]
Abstract
DNA replication in eukaryotes relies on the synthesis of a ∼30-nucleotide RNA/DNA primer strand through the dual action of the heterotetrameric polymerase α-primase (pol-prim) enzyme. Synthesis of the 7-10-nucleotide RNA primer is regulated by the C-terminal domain of the primase regulatory subunit (PRIM2C) and is followed by intramolecular handoff of the primer to pol α for extension by ∼20 nucleotides of DNA. Here, we provide evidence that RNA primer synthesis is governed by a combination of the high affinity and flexible linkage of the PRIM2C domain and the surprisingly low affinity of the primase catalytic domain (PRIM1) for substrate. Using a combination of small angle X-ray scattering and electron microscopy, we found significant variability in the organization of PRIM2C and PRIM1 in the absence and presence of substrate, and that the population of structures with both PRIM2C and PRIM1 in a configuration aligned for synthesis is low. Crosslinking was used to visualize the orientation of PRIM2C and PRIM1 when engaged by substrate as observed by electron microscopy. Microscale thermophoresis was used to measure substrate affinities for a series of pol-prim constructs, which showed that the PRIM1 catalytic domain does not bind the template or emergent RNA-primed templates with appreciable affinity. Together, these findings support a model of RNA primer synthesis in which generation of the nascent RNA strand and handoff of the RNA-primed template from primase to polymerase α is mediated by the high degree of inter-domain flexibility of pol-prim, the ready dissociation of PRIM1 from its substrate, and the much higher affinity of the POLA1cat domain of polymerase α for full-length RNA-primed templates.
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Affiliation(s)
- John J Cordoba
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | - Elwood A Mullins
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
| | - Lauren E Salay
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
| | - Brandt F Eichman
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
| | - Walter J Chazin
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA; Department of Biochemistry, Vanderbilt University, Nashville, TN, USA; Department of Chemistry, Vanderbilt University, Nashville, TN, USA.
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5
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Tamborrini D, Wang Z, Wagner T, Tacke S, Stabrin M, Grange M, Kho AL, Rees M, Bennett P, Gautel M, Raunser S. Structure of the native myosin filament in the relaxed cardiac sarcomere. Nature 2023; 623:863-871. [PMID: 37914933 PMCID: PMC10665186 DOI: 10.1038/s41586-023-06690-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Accepted: 09/28/2023] [Indexed: 11/03/2023]
Abstract
The thick filament is a key component of sarcomeres, the basic units of striated muscle1. Alterations in thick filament proteins are associated with familial hypertrophic cardiomyopathy and other heart and muscle diseases2. Despite the central importance of the thick filament, its molecular organization remains unclear. Here we present the molecular architecture of native cardiac sarcomeres in the relaxed state, determined by cryo-electron tomography. Our reconstruction of the thick filament reveals the three-dimensional organization of myosin, titin and myosin-binding protein C (MyBP-C). The arrangement of myosin molecules is dependent on their position along the filament, suggesting specialized capacities in terms of strain susceptibility and force generation. Three pairs of titin-α and titin-β chains run axially along the filament, intertwining with myosin tails and probably orchestrating the length-dependent activation of the sarcomere. Notably, whereas the three titin-α chains run along the entire length of the thick filament, titin-β chains do not. The structure also demonstrates that MyBP-C bridges thin and thick filaments, with its carboxy-terminal region binding to the myosin tails and directly stabilizing the OFF state of the myosin heads in an unforeseen manner. These results provide a foundation for future research investigating muscle disorders involving sarcomeric components.
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Affiliation(s)
- Davide Tamborrini
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Zhexin Wang
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
- Structural Studies Division, MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Thorsten Wagner
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Sebastian Tacke
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Markus Stabrin
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Michael Grange
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
- Structural Biology, The Rosalind Franklin Institute, Didcot, UK
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, London, UK
| | - Martin Rees
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, London, UK
| | - Pauline Bennett
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, London, UK
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, London, UK
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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6
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Oosterheert W, Blanc FEC, Roy A, Belyy A, Sanders MB, Hofnagel O, Hummer G, Bieling P, Raunser S. Molecular mechanisms of inorganic-phosphate release from the core and barbed end of actin filaments. Nat Struct Mol Biol 2023; 30:1774-1785. [PMID: 37749275 PMCID: PMC10643162 DOI: 10.1038/s41594-023-01101-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 08/18/2023] [Indexed: 09/27/2023]
Abstract
The release of inorganic phosphate (Pi) from actin filaments constitutes a key step in their regulated turnover, which is fundamental to many cellular functions. The mechanisms underlying Pi release from the core and barbed end of actin filaments remain unclear. Here, using human and bovine actin isoforms, we combine cryo-EM with molecular-dynamics simulations and in vitro reconstitution to demonstrate how actin releases Pi through a 'molecular backdoor'. While constantly open at the barbed end, the backdoor is predominantly closed in filament-core subunits and opens only transiently through concerted amino acid rearrangements. This explains why Pi escapes rapidly from the filament end but slowly from internal subunits. In a nemaline-myopathy-associated actin variant, the backdoor is predominantly open in filament-core subunits, resulting in accelerated Pi release and filaments with drastically shortened ADP-Pi caps. Our results provide the molecular basis for Pi release from actin and exemplify how a disease-linked mutation distorts the nucleotide-state distribution and atomic structure of the filament.
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Affiliation(s)
- Wout Oosterheert
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Florian E C Blanc
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany
| | - Ankit Roy
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Alexander Belyy
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Micaela Boiero Sanders
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Oliver Hofnagel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Frankfurt am Main, Germany.
- Institute for Biophysics, Goethe University, Frankfurt am Main, Germany.
| | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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7
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Rüttermann M, Koci M, Lill P, Geladas ED, Kaschani F, Klink BU, Erdmann R, Gatsogiannis C. Structure of the peroxisomal Pex1/Pex6 ATPase complex bound to a substrate. Nat Commun 2023; 14:5942. [PMID: 37741838 PMCID: PMC10518020 DOI: 10.1038/s41467-023-41640-9] [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: 11/09/2022] [Accepted: 09/12/2023] [Indexed: 09/25/2023] Open
Abstract
The double-ring AAA+ ATPase Pex1/Pex6 is required for peroxisomal receptor recycling and is essential for peroxisome formation. Pex1/Pex6 mutations cause severe peroxisome associated developmental disorders. Despite its pathophysiological importance, mechanistic details of the heterohexamer are not yet available. Here, we report cryoEM structures of Pex1/Pex6 from Saccharomyces cerevisiae, with an endogenous protein substrate trapped in the central pore of the catalytically active second ring (D2). Pairs of Pex1/Pex6(D2) subdomains engage the substrate via a staircase of pore-1 loops with distinct properties. The first ring (D1) is catalytically inactive but undergoes significant conformational changes resulting in alternate widening and narrowing of its pore. These events are fueled by ATP hydrolysis in the D2 ring and disengagement of a "twin-seam" Pex1/Pex6(D2) heterodimer from the staircase. Mechanical forces are propagated in a unique manner along Pex1/Pex6 interfaces that are not available in homo-oligomeric AAA-ATPases. Our structural analysis reveals the mechanisms of how Pex1 and Pex6 coordinate to achieve substrate translocation.
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Affiliation(s)
- Maximilian Rüttermann
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany
| | - Michelle Koci
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Pascal Lill
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Ermis Dionysios Geladas
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany
| | - Farnusch Kaschani
- Analytics Core Facility Essen, Center of Medical Biotechnology (ZMB), Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Björn Udo Klink
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany
| | - Ralf Erdmann
- Institute for Biochemistry and Pathobiochemistry, Department of Systems Biochemistry, Ruhr-University Bochum, Bochum, Germany
| | - Christos Gatsogiannis
- Institute for Medical Physics and Biophysics, University Münster, Münster, Germany.
- Center for Soft Nanoscience (SoN), University Münster, Münster, Germany.
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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8
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DiIorio MC, Kulczyk AW. Novel Artificial Intelligence-Based Approaches for Ab Initio Structure Determination and Atomic Model Building for Cryo-Electron Microscopy. MICROMACHINES 2023; 14:1674. [PMID: 37763837 PMCID: PMC10534518 DOI: 10.3390/mi14091674] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/21/2023] [Accepted: 08/25/2023] [Indexed: 09/29/2023]
Abstract
Single particle cryo-electron microscopy (cryo-EM) has emerged as the prevailing method for near-atomic structure determination, shedding light on the important molecular mechanisms of biological macromolecules. However, the inherent dynamics and structural variability of biological complexes coupled with the large number of experimental images generated by a cryo-EM experiment make data processing nontrivial. In particular, ab initio reconstruction and atomic model building remain major bottlenecks that demand substantial computational resources and manual intervention. Approaches utilizing recent innovations in artificial intelligence (AI) technology, particularly deep learning, have the potential to overcome the limitations that cannot be adequately addressed by traditional image processing approaches. Here, we review newly proposed AI-based methods for ab initio volume generation, heterogeneous 3D reconstruction, and atomic model building. We highlight the advancements made by the implementation of AI methods, as well as discuss remaining limitations and areas for future development.
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Affiliation(s)
- Megan C. DiIorio
- Institute for Quantitative Biomedicine, Rutgers University, 174 Frelinghuysen Road, Piscataway, NJ 08854, USA
| | - Arkadiusz W. Kulczyk
- Institute for Quantitative Biomedicine, Rutgers University, 174 Frelinghuysen Road, Piscataway, NJ 08854, USA
- Department of Biochemistry & Microbiology, Rutgers University, 76 Lipman Drive, New Brunswick, NJ 08901, USA
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9
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Cordoba JJ, Mullins EA, Salay LE, Eichman BF, Chazin WJ. Flexibility and distributive synthesis regulate RNA priming and handoff in human DNA polymerase α-primase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.01.551538. [PMID: 37577606 PMCID: PMC10418221 DOI: 10.1101/2023.08.01.551538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
DNA replication in eukaryotes relies on the synthesis of a ~30-nucleotide RNA/DNA primer strand through the dual action of the heterotetrameric polymerase α-primase (pol-prim) enzyme. Synthesis of the 7-10-nucleotide RNA primer is regulated by the C-terminal domain of the primase regulatory subunit (PRIM2C) and is followed by intramolecular handoff of the primer to pol α for extension by ~20 nucleotides of DNA. Here we provide evidence that RNA primer synthesis is governed by a combination of the high affinity and flexible linkage of the PRIM2C domain and the low affinity of the primase catalytic domain (PRIM1) for substrate. Using a combination of small angle X-ray scattering and electron microscopy, we found significant variability in the organization of PRIM2C and PRIM1 in the absence and presence of substrate, and that the population of structures with both PRIM2C and PRIM1 in a configuration aligned for synthesis is low. Crosslinking was used to visualize the orientation of PRIM2C and PRIM1 when engaged by substrate as observed by electron microscopy. Microscale thermophoresis was used to measure substrate affinities for a series of pol-prim constructs, which showed that the PRIM1 catalytic domain does not bind the template or emergent RNA-primed templates with appreciable affinity. Together, these findings support a model of RNA primer synthesis in which generation of the nascent RNA strand and handoff of the RNA-primed template from primase to polymerase α is mediated by the high degree of inter-domain flexibility of pol-prim, the ready dissociation of PRIM1 from its substrate, and the much higher affinity of the POLA1cat domain of polymerase α for full-length RNA-primed templates.
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Affiliation(s)
- John J. Cordoba
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee, USA
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Elwood A. Mullins
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
| | - Lauren E. Salay
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee, USA
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Brandt F. Eichman
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee, USA
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
| | - Walter J. Chazin
- Chemical and Physical Biology Program, Vanderbilt University, Nashville, Tennessee, USA
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
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10
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Quentin D, Schuhmacher JS, Klink BU, Lauer J, Shaikh TR, Huis In 't Veld PJ, Welp LM, Urlaub H, Zerial M, Raunser S. Structural basis of mRNA binding by the human FERRY Rab5 effector complex. Mol Cell 2023; 83:1856-1871.e9. [PMID: 37267906 DOI: 10.1016/j.molcel.2023.05.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 12/05/2022] [Accepted: 05/05/2023] [Indexed: 06/04/2023]
Abstract
The pentameric FERRY Rab5 effector complex is a molecular link between mRNA and early endosomes in mRNA intracellular distribution. Here, we determine the cryo-EM structure of human FERRY. It reveals a unique clamp-like architecture that bears no resemblance to any known structure of Rab effectors. A combination of functional and mutational studies reveals that while the Fy-2 C-terminal coiled-coil acts as binding region for Fy-1/3 and Rab5, both coiled-coils and Fy-5 concur to bind mRNA. Mutations causing truncations of Fy-2 in patients with neurological disorders impair Rab5 binding or FERRY complex assembly. Thus, Fy-2 serves as a binding hub connecting all five complex subunits and mediating the binding to mRNA and early endosomes via Rab5. Our study provides mechanistic insights into long-distance mRNA transport and demonstrates that the particular architecture of FERRY is closely linked to a previously undescribed mode of RNA binding, involving coiled-coil domains.
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Affiliation(s)
- Dennis Quentin
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Jan S Schuhmacher
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Björn U Klink
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany; Center for Soft Nanoscience and Institute of Molecular Physics and Biophysics, 48149 Münster, Germany
| | - Jeni Lauer
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Tanvir R Shaikh
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Pim J Huis In 't Veld
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Luisa M Welp
- Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany
| | - Henning Urlaub
- Max Planck Institute for Multidisciplinary Sciences, 37077 Göttingen, Germany; Institute of Clinical Chemistry, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Marino Zerial
- Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany.
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11
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Zhang D, Yan Y, Huang Y, Liu B, Zheng Q, Zhang J, Xia N. Unsupervised Cryo-EM Images Denoising and Clustering Based on Deep Convolutional Autoencoder and K-Means+. IEEE TRANSACTIONS ON MEDICAL IMAGING 2023; 42:1509-1521. [PMID: 37015394 DOI: 10.1109/tmi.2022.3231626] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Cryo-electron microscopy (cryo-EM) is a widely used structural determination technique. Because of the extremely low signal-to-noise ratio (SNR) of images captured by cryo-EM, clustering single-particle cryo-EM images with high accuracy is challenging. To address this, we proposed an iterative denoising and clustering method based on a deep convolutional variational autoencoder and K-means++. The proposed method contains two modules: a denoising ResNet variational autoencoder (DRVAE), and Balance size K-means++ (BSK-means++). First, the DRVAE is trained in a fully unsupervised manner to initialize the neural network and obtain preliminary denoised images. Second, BSK-means++ is built for clustering denoised images, and images closer to class centers are divided into reliable samples. Third, the training of DRVAE is continued, while the class-average images are used as pseudo supervision of reliable samples to reserve more detailed information of denoised images. Finally, the second and third steps mentioned above can be performed jointly and iteratively until convergence occurs. The experimental results showed that the proposed method can generate reliable class average images and achieve better clustering accuracy and normalized mutual information than current methods. This study confirmed that DRVAE with BSK-means++ could achieve a good denoise performance on single-particle cryo-EM images, which can help researchers obtain information such as symmetry and heterogeneity of the target particles. In addition, the proposed method avoids the extreme imbalance of class size, which improves the reliability of the clustering result.
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12
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Dupuy E, Van der Verren SE, Lin J, Wilson MA, Dachsbeck AV, Viela F, Latour E, Gennaris A, Vertommen D, Dufrêne YF, Iorga BI, Goemans CV, Remaut H, Collet JF. A molecular device for the redox quality control of GroEL/ES substrates. Cell 2023; 186:1039-1049.e17. [PMID: 36764293 PMCID: PMC10044410 DOI: 10.1016/j.cell.2023.01.013] [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: 04/04/2022] [Revised: 10/27/2022] [Accepted: 01/10/2023] [Indexed: 02/11/2023]
Abstract
Hsp60 chaperonins and their Hsp10 cofactors assist protein folding in all living cells, constituting the paradigmatic example of molecular chaperones. Despite extensive investigations of their structure and mechanism, crucial questions regarding how these chaperonins promote folding remain unsolved. Here, we report that the bacterial Hsp60 chaperonin GroEL forms a stable, functionally relevant complex with the chaperedoxin CnoX, a protein combining a chaperone and a redox function. Binding of GroES (Hsp10 cofactor) to GroEL induces CnoX release. Cryoelectron microscopy provided crucial structural information on the GroEL-CnoX complex, showing that CnoX binds GroEL outside the substrate-binding site via a highly conserved C-terminal α-helix. Furthermore, we identified complexes in which CnoX, bound to GroEL, forms mixed disulfides with GroEL substrates, indicating that CnoX likely functions as a redox quality-control plugin for GroEL. Proteins sharing structural features with CnoX exist in eukaryotes, suggesting that Hsp60 molecular plugins have been conserved through evolution.
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Affiliation(s)
- Emile Dupuy
- WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Sander Egbert Van der Verren
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium; Structural and Molecular Microbiology, Structural Biology Research Center, VIB, 1050 Brussels, Belgium
| | - Jiusheng Lin
- Department of Biochemistry and the Redox Biology Center, University of Nebraska, Lincoln, NE 68588, USA
| | - Mark Alan Wilson
- Department of Biochemistry and the Redox Biology Center, University of Nebraska, Lincoln, NE 68588, USA
| | - Alix Vincent Dachsbeck
- WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Felipe Viela
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-neuve, Belgium
| | - Emmanuelle Latour
- WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Alexandra Gennaris
- WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Didier Vertommen
- de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium
| | - Yves Frédéric Dufrêne
- Louvain Institute of Biomolecular Science and Technology, Université Catholique de Louvain, Croix du Sud 4-5, 1348 Louvain-la-neuve, Belgium
| | - Bogdan Iuliu Iorga
- WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium; Université Paris-Saclay, CNRS UPR 2301, Institut de Chimie des Substances Naturelles, 91198 Gif-sur-Yvette, France
| | - Camille Véronique Goemans
- WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium; European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
| | - Han Remaut
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium; Structural and Molecular Microbiology, Structural Biology Research Center, VIB, 1050 Brussels, Belgium.
| | - Jean-François Collet
- WELBIO, Avenue Hippocrate 75, 1200 Brussels, Belgium; de Duve Institute, Université catholique de Louvain, Avenue Hippocrate 75, 1200 Brussels, Belgium.
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13
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Bürgi J, Lill P, Giannopoulou EA, Jeffries CM, Chojnowski G, Raunser S, Gatsogiannis C, Wilmanns M. Asymmetric horseshoe-like assembly of peroxisomal yeast oxalyl-CoA synthetase. Biol Chem 2023; 404:195-207. [PMID: 36694962 DOI: 10.1515/hsz-2022-0273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 12/17/2022] [Indexed: 01/26/2023]
Abstract
Oxalyl-CoA synthetase from Saccharomyces cerevisiae is one of the most abundant peroxisomal proteins in yeast and hence has become a model to study peroxisomal translocation. It contains a C-terminal Peroxisome Targeting Signal 1, which however is partly dispensable, suggesting additional receptor bindings sites. To unravel any additional features that may contribute to its capacity to be recognized as peroxisomal target, we determined its assembly and overall architecture by an integrated structural biology approach, including X-ray crystallography, single particle cryo-electron microscopy and small angle X-ray scattering. Surprisingly, it assembles into mixture of concentration-dependent dimers, tetramers and hexamers by dimer self-association. Hexameric particles form an unprecedented asymmetric horseshoe-like arrangement, which considerably differs from symmetric hexameric assembly found in many other protein structures. A single mutation within the self-association interface is sufficient to abolish any higher-level oligomerization, resulting in a homogenous dimeric assembly. The small C-terminal domain of yeast Oxalyl-CoA synthetase is connected by a partly flexible hinge with the large N-terminal domain, which provides the sole basis for oligomeric assembly. Our data provide a basis to mechanistically study peroxisomal translocation of this target.
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Affiliation(s)
- Jérôme Bürgi
- European Molecular Biology Laboratory, Hamburg Unit, Notkestrasse 85, D-22607 Hamburg, Germany
| | - Pascal Lill
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, University of Münster, Busso-Peus-Str. 10, D-48149 Münster, Germany
| | | | - Cy M Jeffries
- European Molecular Biology Laboratory, Hamburg Unit, Notkestrasse 85, D-22607 Hamburg, Germany
| | - Grzegorz Chojnowski
- European Molecular Biology Laboratory, Hamburg Unit, Notkestrasse 85, D-22607 Hamburg, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
| | - Christos Gatsogiannis
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, D-44227 Dortmund, Germany
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, University of Münster, Busso-Peus-Str. 10, D-48149 Münster, Germany
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Notkestrasse 85, D-22607 Hamburg, Germany
- University Hamburg Clinical Center Hamburg-Eppendorf, University Hamburg, D-20251Hamburg, Germany
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14
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Pla‐Prats C, Cavadini S, Kempf G, Thomä NH. Recognition of the CCT5 di-Glu degron by CRL4 DCAF12 is dependent on TRiC assembly. EMBO J 2023; 42:e112253. [PMID: 36715408 PMCID: PMC9929631 DOI: 10.15252/embj.2022112253] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Revised: 10/21/2022] [Accepted: 12/14/2022] [Indexed: 01/31/2023] Open
Abstract
Assembly Quality Control (AQC) E3 ubiquitin ligases target incomplete or incorrectly assembled protein complexes for degradation. The CUL4-RBX1-DDB1-DCAF12 (CRL4DCAF12 ) E3 ligase preferentially ubiquitinates proteins that carry a C-terminal double glutamate (di-Glu) motif. Reported CRL4DCAF12 di-Glu-containing substrates include CCT5, a subunit of the TRiC chaperonin. How DCAF12 engages its substrates and the functional relationship between CRL4DCAF12 and CCT5/TRiC is currently unknown. Here, we present the cryo-EM structure of the DDB1-DCAF12-CCT5 complex at 2.8 Å resolution. DCAF12 serves as a canonical WD40 DCAF substrate receptor and uses a positively charged pocket at the center of the β-propeller to bind the C-terminus of CCT5. DCAF12 specifically reads out the CCT5 di-Glu side chains, and contacts other visible degron amino acids through Van der Waals interactions. The CCT5 C-terminus is inaccessible in an assembled TRiC complex, and functional assays demonstrate that DCAF12 binds and ubiquitinates monomeric CCT5, but not CCT5 assembled into TRiC. Our biochemical and structural results suggest a previously unknown role for the CRL4DCAF12 E3 ligase in overseeing the assembly of a key cellular complex.
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Affiliation(s)
- Carlos Pla‐Prats
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
- University of BaselBaselSwitzerland
| | - Simone Cavadini
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
| | - Georg Kempf
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
| | - Nicolas H Thomä
- Friedrich Miescher Institute for Biomedical ResearchBaselSwitzerland
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15
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Li Z. Editorial: Methods in structural biology: Cryo-electron microscopy. Front Mol Biosci 2022; 9:1041386. [DOI: 10.3389/fmolb.2022.1041386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 10/03/2022] [Indexed: 11/11/2022] Open
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16
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Oosterheert W, Klink BU, Belyy A, Pospich S, Raunser S. Structural basis of actin filament assembly and aging. Nature 2022; 611:374-379. [DOI: 10.1038/s41586-022-05241-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 08/16/2022] [Indexed: 12/12/2022]
Abstract
AbstractThe dynamic turnover of actin filaments (F-actin) controls cellular motility in eukaryotes and is coupled to changes in the F-actin nucleotide state1–3. It remains unclear how F-actin hydrolyses ATP and subsequently undergoes subtle conformational rearrangements that ultimately lead to filament depolymerization by actin-binding proteins. Here we present cryo-electron microscopy structures of F-actin in all nucleotide states, polymerized in the presence of Mg2+ or Ca2+ at approximately 2.2 Å resolution. The structures show that actin polymerization induces the relocation of water molecules in the nucleotide-binding pocket, activating one of them for the nucleophilic attack of ATP. Unexpectedly, the back door for the subsequent release of inorganic phosphate (Pi) is closed in all structures, indicating that Pi release occurs transiently. The small changes in the nucleotide-binding pocket after ATP hydrolysis and Pi release are sensed by a key amino acid, amplified and transmitted to the filament periphery. Furthermore, differences in the positions of water molecules in the nucleotide-binding pocket explain why Ca2+-actin shows slower polymerization rates than Mg2+-actin. Our work elucidates the solvent-driven rearrangements that govern actin filament assembly and aging and lays the foundation for the rational design of drugs and small molecules for imaging and therapeutic applications.
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17
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Abstract
Cryo-electron microscopy (CryoEM) has become a vital technique in structural biology. It is an interdisciplinary field that takes advantage of advances in biochemistry, physics, and image processing, among other disciplines. Innovations in these three basic pillars have contributed to the boosting of CryoEM in the past decade. This work reviews the main contributions in image processing to the current reconstruction workflow of single particle analysis (SPA) by CryoEM. Our review emphasizes the time evolution of the algorithms across the different steps of the workflow differentiating between two groups of approaches: analytical methods and deep learning algorithms. We present an analysis of the current state of the art. Finally, we discuss the emerging problems and challenges still to be addressed in the evolution of CryoEM image processing methods in SPA.
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Affiliation(s)
- Jose Luis Vilas
- Biocomputing Unit, Centro
Nacional de Biotecnologia (CNB-CSIC), Darwin, 3, Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain
| | - Jose Maria Carazo
- Biocomputing Unit, Centro
Nacional de Biotecnologia (CNB-CSIC), Darwin, 3, Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain
| | - Carlos Oscar S. Sorzano
- Biocomputing Unit, Centro
Nacional de Biotecnologia (CNB-CSIC), Darwin, 3, Campus Universidad Autonoma, 28049 Cantoblanco, Madrid, Spain
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18
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Du J, Vandavasi VG, Molloy KR, Yang H, Massenburg LN, Singh A, Kwansa AL, Yingling YG, O'Neill H, Chait BT, Kumar M, Nixon BT. Evidence for Plant-Conserved Region Mediated Trimeric CESAs in Plant Cellulose Synthase Complexes. Biomacromolecules 2022; 23:3663-3677. [PMID: 35948425 DOI: 10.1021/acs.biomac.2c00550] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Higher plants synthesize cellulose using membrane-bound, six-lobed cellulose synthase complexes, each lobe containing trimeric cellulose synthases (CESAs). Although molecular biology reports support heteromeric trimers composed of different isoforms, a homomeric trimer was reported for in vitro studies of the catalytic domain of CESA1 of Arabidopsis (AtCESA1CatD) and confirmed in cryoEM structures of full-length CESA8 and CESA7 of poplar and cotton, respectively. In both structures, a small portion of the plant-conserved region (P-CR) forms the only contacts between catalytic domains of the monomers. We report inter-subunit lysine-crosslinks that localize to the small P-CR, negative-stain EM structure, and modeling data for homotrimers of AtCESA1CatD. Molecular dynamics simulations for AtCESA1CatD trimers based on the CESA8 cryoEM structure were stable and dependent upon a small set of residue contacts. The results suggest that homomeric CESA trimers may be important for the synthesis of primary and secondary cell walls and identify key residues for future mutagenic studies.
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Affiliation(s)
- Juan Du
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu 610064 China.,Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, United States
| | - Venu Gopal Vandavasi
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Kelly R Molloy
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10065, United States
| | - Hui Yang
- Department of Biology, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, United States
| | - Lynnicia N Massenburg
- Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, United States
| | - Abhishek Singh
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Albert L Kwansa
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Yaroslava G Yingling
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Hugh O'Neill
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States
| | - Brian T Chait
- Laboratory of Mass Spectrometry and Gaseous Ion Chemistry, The Rockefeller University, New York, New York 10065, United States
| | - Manish Kumar
- Department of Chemical Engineering, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, United States
| | - B Tracy Nixon
- Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, State College, Pennsylvania 16802, United States
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Abstract
Shelterin is a multiprotein complex that plays central roles in telomere biology. Mutations in shelterin result in premature aging diseases and familial cancer predisposition. Mechanistic understanding of these so-called telomereopathies is hampered by our lack of knowledge regarding the structure and stoichiometry of shelterin. Here, we use multiple methods to probe the stoichiometry and conformational states of shelterin and reveal that it forms a fully dimeric complex with extensive conformational heterogeneity. Our results highlight the dynamic nature of this essential complex and explain why its high-resolution structure determination has yet to be achieved. Human shelterin is a six-subunit complex—composed of TRF1, TRF2, Rap1, TIN2, TPP1, and POT1—that binds telomeres, protects them from the DNA-damage response, and regulates the maintenance of telomeric DNA. Although high-resolution structures have been generated of the individual structured domains within shelterin, the architecture and stoichiometry of the full complex are currently unknown. Here, we report the purification of shelterin subcomplexes and reconstitution of the entire complex using full-length, recombinant subunits. By combining negative-stain electron microscopy (EM), cross-linking mass spectrometry (XLMS), AlphaFold modeling, mass photometry, and native mass spectrometry (MS), we obtain stoichiometries as well as domain-scale architectures of shelterin subcomplexes and determine that they feature extensive conformational heterogeneity. For POT1/TPP1 and POT1/TPP1/TIN2, we observe high variability in the positioning of the POT1 DNA-binding domain, the TPP1 oligonucleotide/oligosaccharide–binding (OB) fold, and the TIN2 TRFH domain with respect to the C-terminal domains of POT1. Truncation of unstructured linker regions in TIN2, TPP1, and POT1 did not reduce the conformational variability of the heterotrimer. Shelterin and TRF1-containing subcomplexes form fully dimeric stoichiometries, even in the absence of DNA substrates. Shelterin and its subcomplexes showed extensive conformational variability, regardless of the presence of DNA substrates. We conclude that shelterin adopts a multitude of conformations and argue that its unusual architectural variability is beneficial for its many functions at telomeres.
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20
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Belyy A, Lindemann F, Roderer D, Funk J, Bardiaux B, Protze J, Bieling P, Oschkinat H, Raunser S. Mechanism of threonine ADP-ribosylation of F-actin by a Tc toxin. Nat Commun 2022; 13:4202. [PMID: 35858890 PMCID: PMC9300711 DOI: 10.1038/s41467-022-31836-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Accepted: 07/01/2022] [Indexed: 11/25/2022] Open
Abstract
Tc toxins deliver toxic enzymes into host cells by a unique injection mechanism. One of these enzymes is the actin ADP-ribosyltransferase TccC3, whose activity leads to the clustering of the cellular cytoskeleton and ultimately cell death. Here, we show in atomic detail how TccC3 modifies actin. We find that the ADP-ribosyltransferase does not bind to G-actin but interacts with two consecutive actin subunits of F-actin. The binding of TccC3 to F-actin occurs via an induced-fit mechanism that facilitates access of NAD+ to the nucleotide binding pocket. The following nucleophilic substitution reaction results in the transfer of ADP-ribose to threonine-148 of F-actin. We demonstrate that this site-specific modification of F-actin prevents its interaction with depolymerization factors, such as cofilin, which impairs actin network turnover and leads to steady actin polymerization. Our findings reveal in atomic detail a mechanism of action of a bacterial toxin through specific targeting and modification of F-actin. Entomopathogenic bacteria used for pest control secrete potent Tc toxins. Here, the authors combine biochemistry, solution and solid-state NMR spectroscopy and cryo-EM to show in atomic detail how the toxin disrupts the host cell cytoskeleton and kills the target cell.
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Affiliation(s)
- Alexander Belyy
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Florian Lindemann
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - Daniel Roderer
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany.,Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - Johanna Funk
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Benjamin Bardiaux
- Institut Pasteur, Université Paris Cité, CNRS UMR3528, Structural Bioinformatics Unit, 25-28 Rue du Docteur Roux, F-75015, Paris, France
| | - Jonas Protze
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany
| | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Hartmut Oschkinat
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie, Robert-Rössle-Str. 10, 13125, Berlin, Germany.
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany.
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21
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Schöenfeld F, Stabrin M, Shaikh TR, Wagner T, Raunser S. Accelerated 2D Classification With ISAC Using GPUs. Front Mol Biosci 2022; 9:919994. [PMID: 35874605 PMCID: PMC9296836 DOI: 10.3389/fmolb.2022.919994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 05/31/2022] [Indexed: 11/13/2022] Open
Abstract
A widely used approach to analyze single particles in electron microscopy data is 2D classification. This process is very computationally expensive, especially when large data sets are analyzed. In this paper we present GPU ISAC, a newly developed, GPU-accelerated version of the established Iterative Stable Alignment and Clustering (ISAC) algorithm for 2D images and generating class averages. While the previously existing implementation of ISAC relied on a computer cluster, GPU ISAC enables users to produce high quality 2D class averages from large-scale data sets on a single desktop machine equipped with affordable, consumer-grade GPUs such as Nvidia GeForce GTX 1080 TI cards. With only two such cards GPU ISAC matches the performance of twelve high end cluster nodes and, using high performance GPUs, is able to produce class averages from a million particles in between six to thirteen hours, depending on data set quality and box size. We also show GPU ISAC to scale linearly in all input dimensions, and thereby capable of scaling well with the increasing data load demand of future data sets. Further user experience improvements integrate GPU ISAC seamlessly into the existing SPHIRE GUI, as well as the TranSPHIRE on-the-fly processing pipeline. It is open source and can be downloaded at https://gitlab.gwdg.de/mpi-dortmund/sphire/cuISAC/
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22
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Raisch T, Ciossani G, d’Amico E, Cmentowski V, Carmignani S, Maffini S, Merino F, Wohlgemuth S, Vetter IR, Raunser S, Musacchio A. Structure of the RZZ complex and molecular basis of Spindly-driven corona assembly at human kinetochores. EMBO J 2022; 41:e110411. [PMID: 35373361 PMCID: PMC9058546 DOI: 10.15252/embj.2021110411] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 03/09/2022] [Accepted: 03/11/2022] [Indexed: 11/09/2022] Open
Abstract
In metazoans, a ≈1 megadalton (MDa) multiprotein complex comprising the dynein-dynactin adaptor Spindly and the ROD-Zwilch-ZW10 (RZZ) complex is the building block of a fibrous biopolymer, the kinetochore fibrous corona. The corona assembles on mitotic kinetochores to promote microtubule capture and spindle assembly checkpoint (SAC) signaling. We report here a high-resolution cryo-EM structure that captures the essential features of the RZZ complex, including a farnesyl-binding site required for Spindly binding. Using a highly predictive in vitro assay, we demonstrate that the SAC kinase MPS1 is necessary and sufficient for corona assembly at supercritical concentrations of the RZZ-Spindly (RZZS) complex, and describe the molecular mechanism of phosphorylation-dependent filament nucleation. We identify several structural requirements for RZZS polymerization in rings and sheets. Finally, we identify determinants of kinetochore localization and corona assembly of Spindly. Our results describe a framework for the long-sought-for molecular basis of corona assembly on metazoan kinetochores.
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Affiliation(s)
- Tobias Raisch
- Department of Structural BiochemistryMax Planck Institute of Molecular PhysiologyDortmundGermany
| | - Giuseppe Ciossani
- Department of Mechanistic Cell BiologyMax Planck Institute of Molecular PhysiologyDortmundGermany
- Present address:
European Institute of OncologyMilanItaly
| | - Ennio d’Amico
- Department of Mechanistic Cell BiologyMax Planck Institute of Molecular PhysiologyDortmundGermany
| | - Verena Cmentowski
- Department of Mechanistic Cell BiologyMax Planck Institute of Molecular PhysiologyDortmundGermany
| | - Sara Carmignani
- Department of Mechanistic Cell BiologyMax Planck Institute of Molecular PhysiologyDortmundGermany
| | - Stefano Maffini
- Department of Mechanistic Cell BiologyMax Planck Institute of Molecular PhysiologyDortmundGermany
| | - Felipe Merino
- Department of Structural BiochemistryMax Planck Institute of Molecular PhysiologyDortmundGermany
- Present address:
Department of Protein EvolutionMax Planck Institute for Developmental BiologyTübingenGermany
| | - Sabine Wohlgemuth
- Department of Mechanistic Cell BiologyMax Planck Institute of Molecular PhysiologyDortmundGermany
| | - Ingrid R Vetter
- Department of Mechanistic Cell BiologyMax Planck Institute of Molecular PhysiologyDortmundGermany
| | - Stefan Raunser
- Department of Structural BiochemistryMax Planck Institute of Molecular PhysiologyDortmundGermany
| | - Andrea Musacchio
- Department of Mechanistic Cell BiologyMax Planck Institute of Molecular PhysiologyDortmundGermany
- Centre for Medical BiotechnologyFaculty of BiologyUniversity Duisburg‐EssenEssenGermany
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DeVore K, Chiu PL. Probing Structural Perturbation of Biomolecules by Extracting Cryo-EM Data Heterogeneity. Biomolecules 2022; 12:628. [PMID: 35625556 PMCID: PMC9138638 DOI: 10.3390/biom12050628] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 04/15/2022] [Accepted: 04/18/2022] [Indexed: 02/04/2023] Open
Abstract
Single-particle cryogenic electron microscopy (cryo-EM) has become an indispensable tool to probe high-resolution structural detail of biomolecules. It enables direct visualization of the biomolecules and opens a possibility for averaging molecular images to reconstruct a three-dimensional Coulomb potential density map. Newly developed algorithms for data analysis allow for the extraction of structural heterogeneity from a massive and low signal-to-noise-ratio (SNR) cryo-EM dataset, expanding our understanding of multiple conformational states, or further implications in dynamics, of the target biomolecule. This review provides an overview that briefly describes the workflow of single-particle cryo-EM, including imaging and data processing, and new methods developed for analyzing the data heterogeneity to understand the structural variability of biomolecules.
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Affiliation(s)
| | - Po-Lin Chiu
- School of Molecular Sciences, Biodesign Center for Applied Structural Discovery, Arizona State University, Tempe, AZ 85287, USA;
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24
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Zhang C, Jiang H, Liu W, Li J, Tang S, Juhas M, Zhang Y. Correction of out-of-focus microscopic images by deep learning. Comput Struct Biotechnol J 2022; 20:1957-1966. [PMID: 35521557 PMCID: PMC9062264 DOI: 10.1016/j.csbj.2022.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 04/01/2022] [Accepted: 04/02/2022] [Indexed: 11/03/2022] Open
Abstract
Motivation Microscopic images are widely used in basic biomedical research, disease diagnosis and medical discovery. Obtaining high-quality in-focus microscopy images has been a cornerstone of the microscopy. However, images obtained by microscopes are often out-of-focus, resulting in poor performance in research and diagnosis. Results To solve the out-of-focus issue in microscopy, we developed a Cycle Generative Adversarial Network (CycleGAN) based model and a multi-component weighted loss function. We train and test our network in two self-collected datasets, namely Leishmania parasite dataset captured by a bright-field microscope, and bovine pulmonary artery endothelial cells (BPAEC) captured by a confocal fluorescence microscope. In comparison to other GAN-based deblurring methods, the proposed model reached state-of-the-art performance in correction. Another publicly available dataset, human cells dataset from the Broad Bioimage Benchmark Collection is used for evaluating the generalization abilities of the model. Our model showed excellent generalization capability, which could transfer to different types of microscopic image datasets. Availability and Implementation Code and dataset are publicly available at: https://github.com/jiangdat/COMI.
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Affiliation(s)
- Chi Zhang
- College of Science, Harbin Institute of Technology, Shenzhen, China
- School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu, China
| | - Hao Jiang
- College of Science, Harbin Institute of Technology, Shenzhen, China
| | - Weihuang Liu
- College of Science, Harbin Institute of Technology, Shenzhen, China
- Department of Computer and Information Science, University of Macau, Macau, China
| | - Junyi Li
- School of Computer Science and Technology, Harbin Institute of Technology (Shenzhen), Shenzhen, Guangdong 518055, China
| | - Shiming Tang
- School of Computing and Engineering, University of Missouri-Kansas City, MO, United States
| | - Mario Juhas
- Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| | - Yang Zhang
- College of Science, Harbin Institute of Technology, Shenzhen, China
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25
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Wang Z, Grange M, Pospich S, Wagner T, Kho AL, Gautel M, Raunser S. Structures from intact myofibrils reveal mechanism of thin filament regulation through nebulin. Science 2022; 375:eabn1934. [PMID: 35175800 DOI: 10.1126/science.abn1934] [Citation(s) in RCA: 54] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In skeletal muscle, nebulin stabilizes and regulates the length of thin filaments, but the underlying mechanism remains nebulous. In this work, we used cryo-electron tomography and subtomogram averaging to reveal structures of native nebulin bound to thin filaments within intact sarcomeres. This in situ reconstruction provided high-resolution details of the interaction between nebulin and actin, demonstrating the stabilizing role of nebulin. Myosin bound to the thin filaments exhibited different conformations of the neck domain, highlighting its inherent structural variability in muscle. Unexpectedly, nebulin did not interact with myosin or tropomyosin, but it did interact with a troponin T linker through two potential binding motifs on nebulin, explaining its regulatory role. Our structures support the role of nebulin as a thin filament "molecular ruler" and provide a molecular basis for studying nemaline myopathies.
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Affiliation(s)
- Zhexin Wang
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Michael Grange
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Sabrina Pospich
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Thorsten Wagner
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
| | - Ay Lin Kho
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, Guy's Campus, London SE1 1UL, UK
| | - Mathias Gautel
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Centre of Research Excellence, Guy's Campus, London SE1 1UL, UK
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227 Dortmund, Germany
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26
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Wu JG, Yan Y, Zhang DX, Liu BW, Zheng QB, Xie XL, Liu SQ, Ge SX, Hou ZG, Xia NS. Machine Learning for Structure Determination in Single-Particle Cryo-Electron Microscopy: A Systematic Review. IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2022; 33:452-472. [PMID: 34932487 DOI: 10.1109/tnnls.2021.3131325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Recently, single-particle cryo-electron microscopy (cryo-EM) has become an indispensable method for determining macromolecular structures at high resolution to deeply explore the relevant molecular mechanism. Its recent breakthrough is mainly because of the rapid advances in hardware and image processing algorithms, especially machine learning. As an essential support of single-particle cryo-EM, machine learning has powered many aspects of structure determination and greatly promoted its development. In this article, we provide a systematic review of the applications of machine learning in this field. Our review begins with a brief introduction of single-particle cryo-EM, followed by the specific tasks and challenges of its image processing. Then, focusing on the workflow of structure determination, we describe relevant machine learning algorithms and applications at different steps, including particle picking, 2-D clustering, 3-D reconstruction, and other steps. As different tasks exhibit distinct characteristics, we introduce the evaluation metrics for each task and summarize their dynamics of technology development. Finally, we discuss the open issues and potential trends in this promising field.
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27
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Günther P, Quentin D, Ahmad S, Sachar K, Gatsogiannis C, Whitney JC, Raunser S. Structure of a bacterial Rhs effector exported by the type VI secretion system. PLoS Pathog 2022; 18:e1010182. [PMID: 34986192 PMCID: PMC8765631 DOI: 10.1371/journal.ppat.1010182] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 01/18/2022] [Accepted: 12/08/2021] [Indexed: 11/20/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread protein export apparatus found in Gram-negative bacteria. The majority of T6SSs deliver toxic effector proteins into competitor bacteria. Yet, the structure, function, and activation of many of these effectors remains poorly understood. Here, we present the structures of the T6SS effector RhsA from Pseudomonas protegens and its cognate T6SS spike protein, VgrG1, at 3.3 Å resolution. The structures reveal that the rearrangement hotspot (Rhs) repeats of RhsA assemble into a closed anticlockwise β-barrel spiral similar to that found in bacterial insecticidal Tc toxins and in metazoan teneurin proteins. We find that the C-terminal toxin domain of RhsA is autoproteolytically cleaved but remains inside the Rhs ‘cocoon’ where, with the exception of three ordered structural elements, most of the toxin is disordered. The N-terminal ‘plug’ domain is unique to T6SS Rhs proteins and resembles a champagne cork that seals the Rhs cocoon at one end while also mediating interactions with VgrG1. Interestingly, this domain is also autoproteolytically cleaved inside the cocoon but remains associated with it. We propose that mechanical force is required to remove the cleaved part of the plug, resulting in the release of the toxin domain as it is delivered into a susceptible bacterial cell by the T6SS. Bacteria have developed a variety of strategies to compete for nutrients and limited resources. One system widely used by Gram-negative bacteria is the T6 secretion system which delivers a plethora of effectors into competing bacterial cells. Known functions of effectors are degradation of the cell wall, the depletion of essential metabolites such as NAD+ or the cleavage of DNA. RhsA is an effector from the widespread plant-protecting bacteria Pseudomonas protegens. We found that RhsA forms a closed cocoon similar to that found in bacterial Tc toxins and metazoan teneurin proteins. The effector cleaves its polypeptide chain by itself in three pieces, namely the N-terminal domain including a seal, the cocoon and the actual toxic component which potentially cleaves DNA. The toxic component is encapsulated in the large cocoon, so that the effector producing bacterium is protected from the toxin. In order for the toxin to exit the cocoon, we propose that the seal, which closes the cocoon at one end, is removed by mechanical forces during injection of the effector by the T6 secretion system. We further hypothesize about different scenarios for the delivery of the toxin into the cytoplasm of the host cell. Together, our findings expand the knowledge of the mechanism of action of the T6 secretion system and its essential role in interbacterial competition.
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Affiliation(s)
- Patrick Günther
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Dennis Quentin
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Shehryar Ahmad
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Kartik Sachar
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - Christos Gatsogiannis
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - John C. Whitney
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
- Michael DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Canada
- David Braley Centre for Antibiotic Discovery, McMaster University, Hamilton, Canada
- * E-mail: (J.C.W.); (S.R.)
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
- * E-mail: (J.C.W.); (S.R.)
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Small molecule modulation of the Drosophila Slo channel elucidated by cryo-EM. Nat Commun 2021; 12:7164. [PMID: 34887422 PMCID: PMC8660915 DOI: 10.1038/s41467-021-27435-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 11/18/2021] [Indexed: 12/16/2022] Open
Abstract
Slowpoke (Slo) potassium channels display extraordinarily high conductance, are synergistically activated by a positive transmembrane potential and high intracellular Ca2+ concentrations and are important targets for insecticides and antiparasitic drugs. However, it is unknown how these compounds modulate ion translocation and whether there are insect-specific binding pockets. Here, we report structures of Drosophila Slo in the Ca2+-bound and Ca2+-free form and in complex with the fungal neurotoxin verruculogen and the anthelmintic drug emodepside. Whereas the architecture and gating mechanism of Slo channels are conserved, potential insect-specific binding pockets exist. Verruculogen inhibits K+ transport by blocking the Ca2+-induced activation signal and precludes K+ from entering the selectivity filter. Emodepside decreases the conductance by suboptimal K+ coordination and uncouples ion gating from Ca2+ and voltage sensing. Our results expand the mechanistic understanding of Slo regulation and lay the foundation for the rational design of regulators of Slo and other voltage-gated ion channels. Slowpoke (Slo) channels are voltage-gated potassium channels that are activated by high intracellular Ca2+ concentrations, and they are targets for insecticides and antiparasitic drugs. Here, the authors present the cryo-EM structures of the Drosophila melanogaster Slo channel in the Ca2+-bound and Ca2+-free conformations, as well as in complex with the fungal neurotoxin verruculogen and the anthelmintic drug emodepside and discuss the mechanisms by which they affect the activity of Slo.
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29
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Chen M, Blum D, Engelhard L, Raunser S, Wagner R, Gatsogiannis C. Molecular architecture of black widow spider neurotoxins. Nat Commun 2021; 12:6956. [PMID: 34845192 PMCID: PMC8630228 DOI: 10.1038/s41467-021-26562-8] [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: 04/19/2021] [Accepted: 10/11/2021] [Indexed: 12/14/2022] Open
Abstract
Latrotoxins (LaTXs) are presynaptic pore-forming neurotoxins found in the venom of Latrodectus spiders. The venom contains a toxic cocktail of seven LaTXs, with one of them targeting vertebrates (α-latrotoxin (α-LTX)), five specialized on insects (α, β, γ, δ, ε- latroinsectotoxins (LITs), and one on crustaceans (α-latrocrustatoxin (α-LCT)). LaTXs bind to specific receptors on the surface of neuronal cells, inducing the release of neurotransmitters either by directly stimulating exocytosis or by forming Ca2+-conductive tetrameric pores in the membrane. Despite extensive studies in the past decades, a high-resolution structure of a LaTX is not yet available and the precise mechanism of LaTX action remains unclear. Here, we report cryoEM structures of the α-LCT monomer and the δ-LIT dimer. The structures reveal that LaTXs are organized in four domains. A C-terminal domain of ankyrin-like repeats shields a central membrane insertion domain of six parallel α-helices. Both domains are flexibly linked via an N-terminal α-helical domain and a small β-sheet domain. A comparison between the structures suggests that oligomerization involves major conformational changes in LaTXs with longer C-terminal domains. Based on our data we propose a cyclic mechanism of oligomerization, taking place prior membrane insertion. Both recombinant α-LCT and δ-LIT form channels in artificial membrane bilayers, that are stabilized by Ca2+ ions and allow calcium flux at negative membrane potentials. Our comparative analysis between α-LCT and δ-LIT provides first crucial insights towards understanding the molecular mechanism of the LaTX family. The venom of Latrodectus spiders contains seven Latrotoxins (LaTXs), among them α-latrocrustatoxin (LCT) and δ- latroinsectotoxins δ-LIT. LaTXs bind to specific receptors on the surface of neuronal cells and target the molecular exocytosis machinery. Here, the authors present the cryo-EM structure of the α-LCT monomer and the δ-LIT dimer, which reveal that LaTXs are organized in four domains and they discuss the potential oligomerisation mechanism that takes place before LaTXs membrane insertion. Both recombinant α-LCT and δ-LIT form channels in artificial membrane bilayers, that are stabilized by Ca2+ ions.
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Affiliation(s)
- Minghao Chen
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms Universität Münster, 48149, Münster, Germany.,Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Daniel Blum
- MOLIFE Research Center, Jacobs University Bremen, 28759, Bremen, Germany
| | - Lena Engelhard
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany
| | - Richard Wagner
- MOLIFE Research Center, Jacobs University Bremen, 28759, Bremen, Germany
| | - Christos Gatsogiannis
- Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms Universität Münster, 48149, Münster, Germany. .,Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, 44227, Dortmund, Germany.
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30
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Pospich S, Sweeney HL, Houdusse A, Raunser S. High-resolution structures of the actomyosin-V complex in three nucleotide states provide insights into the force generation mechanism. eLife 2021; 10:e73724. [PMID: 34812732 PMCID: PMC8735999 DOI: 10.7554/elife.73724] [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: 09/08/2021] [Accepted: 11/22/2021] [Indexed: 11/13/2022] Open
Abstract
The molecular motor myosin undergoes a series of major structural transitions during its force-producing motor cycle. The underlying mechanism and its coupling to ATP hydrolysis and actin binding are only partially understood, mostly due to sparse structural data on actin-bound states of myosin. Here, we report 26 high-resolution cryo-EM structures of the actomyosin-V complex in the strong-ADP, rigor, and a previously unseen post-rigor transition state that binds the ATP analog AppNHp. The structures reveal a high flexibility of myosin in each state and provide valuable insights into the structural transitions of myosin-V upon ADP release and binding of AppNHp, as well as the actomyosin interface. In addition, they show how myosin is able to specifically alter the structure of F-actin.
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Affiliation(s)
- Sabrina Pospich
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | - H Lee Sweeney
- Department of Pharmacology and Therapeutics and the Myology Institute, University of FloridaGainesvilleUnited States
| | - Anne Houdusse
- Structural Motility, Institut Curie, Centre National de la Recherche ScientifiqueParisFrance
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
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31
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Pandey S, Kumari P, Baidya M, Kise R, Cao Y, Dwivedi-Agnihotri H, Banerjee R, Li XX, Cui CS, Lee JD, Kawakami K, Maharana J, Ranjan A, Chaturvedi M, Jhingan GD, Laporte SA, Woodruff TM, Inoue A, Shukla AK. Intrinsic bias at non-canonical, β-arrestin-coupled seven transmembrane receptors. Mol Cell 2021; 81:4605-4621.e11. [PMID: 34582793 PMCID: PMC7612807 DOI: 10.1016/j.molcel.2021.09.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Revised: 07/13/2021] [Accepted: 09/02/2021] [Indexed: 12/31/2022]
Abstract
G-protein-coupled receptors (GPCRs), also known as seven transmembrane receptors (7TMRs), typically interact with two distinct signal-transducers, i.e., G proteins and β-arrestins (βarrs). Interestingly, there are some non-canonical 7TMRs that lack G protein coupling but interact with barrs, although an understanding of their transducer coupling preference, downstream signaling, and structural mechanism remains elusive. Here, we characterize two such non-canonical 7TMRs, namely, the decoy D6 receptor (D6R) and the complement C5a receptor subtype 2 (C5aR2), in parallel with their canonical GPCR counterparts. We discover that D6R and C5aR2 efficiently couple to βarrs, exhibit distinct engagement of GPCR kinases (GRKs), and activate non-canonical downstream signaling pathways. We also observe that βarrs adopt distinct conformations for D6R and C5aR2, compared to their canonical GPCR counterparts, in response to common natural agonists. Our study establishes D6R and C5aR2 as βarr-coupled 7TMRs and provides key insights into their regulation and signaling with direct implication for biased agonism.
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Affiliation(s)
- Shubhi Pandey
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Punita Kumari
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Mithu Baidya
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Ryoji Kise
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Yubo Cao
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC H3G 1Y6, Canada
| | - Hemlata Dwivedi-Agnihotri
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Ramanuj Banerjee
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Xaria X Li
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane 4072, Australia
| | - Cedric S Cui
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane 4072, Australia
| | - John D Lee
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane 4072, Australia
| | - Kouki Kawakami
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Jagannath Maharana
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Ashutosh Ranjan
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | - Madhu Chaturvedi
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India
| | | | - Stéphane A Laporte
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC H3G 1Y6, Canada; Department of Medicine, McGill University Health Center, McGill University, Montréal, QC H4A 3J1, Canada
| | - Trent M Woodruff
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, Brisbane 4072, Australia; Queensland Brain Institute, The University of Queensland, Brisbane 4072, Australia
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Arun K Shukla
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology, Kanpur 208016, India.
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32
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Belyy A, Merino F, Mechold U, Raunser S. Mechanism of actin-dependent activation of nucleotidyl cyclase toxins from bacterial human pathogens. Nat Commun 2021; 12:6628. [PMID: 34785651 PMCID: PMC8595890 DOI: 10.1038/s41467-021-26889-2] [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: 07/15/2021] [Accepted: 10/25/2021] [Indexed: 12/19/2022] Open
Abstract
Bacterial human pathogens secrete initially inactive nucleotidyl cyclases that become potent enzymes by binding to actin inside eukaryotic host cells. The underlying molecular mechanism of this activation is, however, unclear. Here, we report structures of ExoY from Pseudomonas aeruginosa and Vibrio vulnificus bound to their corresponding activators F-actin and profilin-G-actin. The structures reveal that in contrast to the apo-state, two flexible regions become ordered and interact strongly with actin. The specific stabilization of these regions results in an allosteric stabilization of the nucleotide binding pocket and thereby to an activation of the enzyme. Differences in the sequence and conformation of the actin-binding regions are responsible for the selective binding to either F- or G-actin. Other nucleotidyl cyclase toxins that bind to calmodulin rather than actin undergo a similar disordered-to-ordered transition during activation, suggesting that the allosteric activation-by-stabilization mechanism of ExoY is conserved in these enzymes, albeit the different activator.
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Affiliation(s)
- Alexander Belyy
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Max-Planck-Ring 5, 72076, Tübingen, Germany
| | - Undine Mechold
- Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie, Institut Pasteur, CNRS UMR 3528, Paris, France
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany.
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Structural and Computational Study of the GroEL-Prion Protein Complex. Biomedicines 2021; 9:biomedicines9111649. [PMID: 34829878 PMCID: PMC8615626 DOI: 10.3390/biomedicines9111649] [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: 09/29/2021] [Revised: 11/02/2021] [Accepted: 11/05/2021] [Indexed: 11/16/2022] Open
Abstract
The molecular chaperone GroEL is designed to promote protein folding and prevent aggregation. However, the interaction between GroEL and the prion protein, PrPC, could lead to pathogenic transformation of the latter to the aggregation-prone PrPSc form. Here, the molecular basis of the interactions in the GroEL-PrP complex is studied with cryo-EM and molecular dynamics approaches. The obtained cryo-EM structure shows PrP to be bound to several subunits of GroEL at the level of their apical domains. According to MD simulations, the disordered N-domain of PrP forms much more intermolecular contacts with GroEL. Upon binding to the GroEL, the N-domain of PrP begins to form short helices, while the C-domain of PrP exhibits a tendency to unfold its α2-helix. In the absence of the nucleotides in the system, these processes are manifested at the hundred nanoseconds to microsecond timescale.
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34
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A Fast Image Alignment Approach for 2D Classification of Cryo-EM Images Using Spectral Clustering. Curr Issues Mol Biol 2021; 43:1652-1668. [PMID: 34698131 PMCID: PMC8928942 DOI: 10.3390/cimb43030117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 10/14/2021] [Accepted: 10/14/2021] [Indexed: 01/22/2023] Open
Abstract
Three-dimensional (3D) reconstruction in single-particle cryo-electron microscopy (cryo-EM) is a significant technique for recovering the 3D structure of proteins or other biological macromolecules from their two-dimensional (2D) noisy projection images taken from unknown random directions. Class averaging in single-particle cryo-EM is an important procedure for producing high-quality initial 3D structures, where image alignment is a fundamental step. In this paper, an efficient image alignment algorithm using 2D interpolation in the frequency domain of images is proposed to improve the estimation accuracy of alignment parameters of rotation angles and translational shifts between the two projection images, which can obtain subpixel and subangle accuracy. The proposed algorithm firstly uses the Fourier transform of two projection images to calculate a discrete cross-correlation matrix and then performs the 2D interpolation around the maximum value in the cross-correlation matrix. The alignment parameters are directly determined according to the position of the maximum value in the cross-correlation matrix after interpolation. Furthermore, the proposed image alignment algorithm and a spectral clustering algorithm are used to compute class averages for single-particle 3D reconstruction. The proposed image alignment algorithm is firstly tested on a Lena image and two cryo-EM datasets. Results show that the proposed image alignment algorithm can estimate the alignment parameters accurately and efficiently. The proposed method is also used to reconstruct preliminary 3D structures from a simulated cryo-EM dataset and a real cryo-EM dataset and to compare them with RELION. Experimental results show that the proposed method can obtain more high-quality class averages than RELION and can obtain higher reconstruction resolution than RELION even without iteration.
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35
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Funk J, Merino F, Schaks M, Rottner K, Raunser S, Bieling P. A barbed end interference mechanism reveals how capping protein promotes nucleation in branched actin networks. Nat Commun 2021; 12:5329. [PMID: 34504078 PMCID: PMC8429771 DOI: 10.1038/s41467-021-25682-5] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Accepted: 08/18/2021] [Indexed: 12/26/2022] Open
Abstract
Heterodimeric capping protein (CP/CapZ) is an essential factor for the assembly of branched actin networks, which push against cellular membranes to drive a large variety of cellular processes. Aside from terminating filament growth, CP potentiates the nucleation of actin filaments by the Arp2/3 complex in branched actin networks through an unclear mechanism. Here, we combine structural biology with in vitro reconstitution to demonstrate that CP not only terminates filament elongation, but indirectly stimulates the activity of Arp2/3 activating nucleation promoting factors (NPFs) by preventing their association to filament barbed ends. Key to this function is one of CP's C-terminal "tentacle" extensions, which sterically masks the main interaction site of the terminal actin protomer. Deletion of the β tentacle only modestly impairs capping. However, in the context of a growing branched actin network, its removal potently inhibits nucleation promoting factors by tethering them to capped filament ends. End tethering of NPFs prevents their loading with actin monomers required for activation of the Arp2/3 complex and thus strongly inhibits branched network assembly both in cells and reconstituted motility assays. Our results mechanistically explain how CP couples two opposed processes-capping and nucleation-in branched actin network assembly.
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Affiliation(s)
- Johanna Funk
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Department of Protein Evolution, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Matthias Schaks
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Klemens Rottner
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany.,Department of Cell Biology, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
| | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
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36
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Yu J, Raia P, Ghent CM, Raisch T, Sadian Y, Cavadini S, Sabale PM, Barford D, Raunser S, Morgan DO, Boland A. Structural basis of human separase regulation by securin and CDK1-cyclin B1. Nature 2021; 596:138-142. [PMID: 34290405 PMCID: PMC8482764 DOI: 10.1038/s41586-021-03764-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 06/23/2021] [Indexed: 02/06/2023]
Abstract
In early mitosis, the duplicated chromosomes are held together by the ring-shaped cohesin complex1. Separation of chromosomes during anaphase is triggered by separase-a large cysteine endopeptidase that cleaves the cohesin subunit SCC1 (also known as RAD212-4). Separase is activated by degradation of its inhibitors, securin5 and cyclin B6, but the molecular mechanisms of separase regulation are not clear. Here we used cryogenic electron microscopy to determine the structures of human separase in complex with either securin or CDK1-cyclin B1-CKS1. In both complexes, separase is inhibited by pseudosubstrate motifs that block substrate binding at the catalytic site and at nearby docking sites. As in Caenorhabditis elegans7 and yeast8, human securin contains its own pseudosubstrate motifs. By contrast, CDK1-cyclin B1 inhibits separase by deploying pseudosubstrate motifs from intrinsically disordered loops in separase itself. One autoinhibitory loop is oriented by CDK1-cyclin B1 to block the catalytic sites of both separase and CDK19,10. Another autoinhibitory loop blocks substrate docking in a cleft adjacent to the separase catalytic site. A third separase loop contains a phosphoserine6 that promotes complex assembly by binding to a conserved phosphate-binding pocket in cyclin B1. Our study reveals the diverse array of mechanisms by which securin and CDK1-cyclin B1 bind and inhibit separase, providing the molecular basis for the robust control of chromosome segregation.
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Affiliation(s)
- Jun Yu
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Pierre Raia
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
| | - Chloe M Ghent
- Department of Physiology, University of California, San Francisco, San Francisco, CA, USA
| | - Tobias Raisch
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Yashar Sadian
- Bioimaging Center, University of Geneva, Geneva, Switzerland
| | - Simone Cavadini
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Pramod M Sabale
- Department of Organic Chemistry, NCCR Chemical Biology, University of Geneva, Geneva, Switzerland
| | | | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - David O Morgan
- Department of Physiology, University of California, San Francisco, San Francisco, CA, USA
| | - Andreas Boland
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland.
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37
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Dudziak A, Engelhard L, Bourque C, Klink BU, Rombaut P, Kornakov N, Jänen K, Herzog F, Gatsogiannis C, Westermann S. Phospho-regulated Bim1/EB1 interactions trigger Dam1c ring assembly at the budding yeast outer kinetochore. EMBO J 2021; 40:e108004. [PMID: 34313341 PMCID: PMC8441410 DOI: 10.15252/embj.2021108004] [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: 02/12/2021] [Revised: 07/01/2021] [Accepted: 07/07/2021] [Indexed: 11/16/2022] Open
Abstract
Kinetochores form the link between chromosomes and microtubules of the mitotic spindle. The heterodecameric Dam1 complex (Dam1c) is a major component of the Saccharomyces cerevisiae outer kinetochore, assembling into 3 MDa‐sized microtubule‐embracing rings, but how ring assembly is specifically initiated in vivo remains to be understood. Here, we describe a molecular pathway that provides local control of ring assembly during the establishment of sister kinetochore bi‐orientation. We show that Dam1c and the general microtubule plus end‐associated protein (+TIP) Bim1/EB1 form a stable complex depending on a conserved motif in the Duo1 subunit of Dam1c. EM analyses reveal that Bim1 crosslinks protrusion domains of adjacent Dam1c heterodecamers and promotes the formation of oligomers with defined curvature. Disruption of the Dam1c‐Bim1 interaction impairs kinetochore localization of Dam1c in metaphase and delays mitosis. Phosphorylation promotes Dam1c‐Bim1 binding by relieving an intramolecular inhibition of the Dam1 C‐terminus. In addition, Bim1 recruits Bik1/CLIP‐170 to Dam1c and induces formation of full rings even in the absence of microtubules. Our data help to explain how new kinetochore end‐on attachments are formed during the process of attachment error correction.
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Affiliation(s)
- Alexander Dudziak
- Department of Molecular Genetics I, Center of Molecular Biotechnology, University of Duisburg-Essen, Essen, Germany
| | - Lena Engelhard
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Cole Bourque
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Björn Udo Klink
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Pascaline Rombaut
- Gene Center Munich, Ludwig Maximilian University Munich, Munich, Germany
| | - Nikolay Kornakov
- Department of Molecular Genetics I, Center of Molecular Biotechnology, University of Duisburg-Essen, Essen, Germany
| | - Karolin Jänen
- Department of Molecular Genetics I, Center of Molecular Biotechnology, University of Duisburg-Essen, Essen, Germany
| | - Franz Herzog
- Gene Center Munich, Ludwig Maximilian University Munich, Munich, Germany
| | - Christos Gatsogiannis
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Institute for Medical Physics and Biophysics and Center for Soft Nanoscience, Westfälische Wilhelms-Universität Münster, Münster, Germany
| | - Stefan Westermann
- Department of Molecular Genetics I, Center of Molecular Biotechnology, University of Duisburg-Essen, Essen, Germany
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38
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Structures of rhodopsin in complex with G-protein-coupled receptor kinase 1. Nature 2021; 595:600-605. [PMID: 34262173 PMCID: PMC8607881 DOI: 10.1038/s41586-021-03721-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 06/11/2021] [Indexed: 02/06/2023]
Abstract
G-protein-coupled receptor (GPCR) kinases (GRKs) selectively phosphorylate activated GPCRs, thereby priming them for desensitization1. Although it is unclear how GRKs recognize these receptors2-4, a conserved region at the GRK N terminus is essential for this process5-8. Here we report a series of cryo-electron microscopy single-particle reconstructions of light-activated rhodopsin (Rho*) bound to rhodopsin kinase (GRK1), wherein the N terminus of GRK1 forms a helix that docks into the open cytoplasmic cleft of Rho*. The helix also packs against the GRK1 kinase domain and stabilizes it in an active configuration. The complex is further stabilized by electrostatic interactions between basic residues that are conserved in most GPCRs and acidic residues that are conserved in GRKs. We did not observe any density for the regulator of G-protein signalling homology domain of GRK1 or the C terminus of rhodopsin. Crosslinking with mass spectrometry analysis confirmed these results and revealed dynamic behaviour in receptor-bound GRK1 that would allow the phosphorylation of multiple sites in the receptor tail. We have identified GRK1 residues whose mutation augments kinase activity and crosslinking with Rho*, as well as residues that are involved in activation by acidic phospholipids. From these data, we present a general model for how a small family of protein kinases can recognize and be activated by hundreds of different GPCRs.
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39
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Dijkman PM, Marzluf T, Zhang Y, Chang SYS, Helm D, Lanzer M, Bujard H, Kudryashev M. Structure of the merozoite surface protein 1 from Plasmodium falciparum. SCIENCE ADVANCES 2021; 7:eabg0465. [PMID: 34078606 PMCID: PMC11210306 DOI: 10.1126/sciadv.abg0465] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/14/2021] [Indexed: 06/12/2023]
Abstract
The merozoite surface protein 1 (MSP-1) is the most abundant protein on the surface of the erythrocyte-invading Plasmodium merozoite, the causative agent of malaria. MSP-1 is essential for merozoite formation, entry into and escape from erythrocytes, and is a promising vaccine candidate. Here, we present monomeric and dimeric structures of full-length MSP-1. MSP-1 adopts an unusual fold with a large central cavity. Its fold includes several coiled-coils and shows structural homology to proteins associated with membrane and cytoskeleton interactions. MSP-1 formed dimers through these domains in a concentration-dependent manner. Dimerization is affected by the presence of the erythrocyte cytoskeleton protein spectrin, which may compete for the dimerization interface. Our work provides structural insights into the possible mode of interaction of MSP-1 with erythrocytes and establishes a framework for future investigations into the role of MSP-1 in Plasmodium infection and immunity.
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Affiliation(s)
- Patricia M Dijkman
- Max-Planck-Institute of Biophysics, Frankfurt am Main, Germany.
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt, Frankfurt am Main, Germany
| | - Tanja Marzluf
- Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg University, Heidelberg, Germany
- MS-based Protein Analysis Unit, Genomics and Proteomics Core Facility, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Yingyi Zhang
- Max-Planck-Institute of Biophysics, Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt, Frankfurt am Main, Germany
| | - Shih-Ying Scott Chang
- Max-Planck-Institute of Biophysics, Frankfurt am Main, Germany
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt, Frankfurt am Main, Germany
| | - Dominic Helm
- MS-based Protein Analysis Unit, Genomics and Proteomics Core Facility, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Michael Lanzer
- Centre for Infectious Diseases, Parasitology Unit, Heidelberg University Hospital, Heidelberg University, Heidelberg, Germany
| | - Hermann Bujard
- Sumaya Biotech GmbH & Co. KG, Heidelberg, Germany
- Centre for Molecular Biology Heidelberg, Heidelberg University, Heidelberg, Germany
| | - Mikhail Kudryashev
- Max-Planck-Institute of Biophysics, Frankfurt am Main, Germany.
- Buchmann Institute for Molecular Life Sciences (BMLS), Goethe University of Frankfurt, Frankfurt am Main, Germany
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40
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Wang Z, Grange M, Wagner T, Kho AL, Gautel M, Raunser S. The molecular basis for sarcomere organization in vertebrate skeletal muscle. Cell 2021; 184:2135-2150.e13. [PMID: 33765442 PMCID: PMC8054911 DOI: 10.1016/j.cell.2021.02.047] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/27/2021] [Accepted: 02/22/2021] [Indexed: 12/20/2022]
Abstract
Sarcomeres are force-generating and load-bearing devices of muscles. A precise molecular picture of how sarcomeres are built underpins understanding their role in health and disease. Here, we determine the molecular architecture of native vertebrate skeletal sarcomeres by electron cryo-tomography. Our reconstruction reveals molecular details of the three-dimensional organization and interaction of actin and myosin in the A-band, I-band, and Z-disc and demonstrates that α-actinin cross-links antiparallel actin filaments by forming doublets with 6-nm spacing. Structures of myosin, tropomyosin, and actin at ~10 Å further reveal two conformations of the "double-head" myosin, where the flexible orientation of the lever arm and light chains enable myosin not only to interact with the same actin filament, but also to split between two actin filaments. Our results provide unexpected insights into the fundamental organization of vertebrate skeletal muscle and serve as a strong foundation for future investigations of muscle diseases.
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Affiliation(s)
- Zhexin Wang
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Michael Grange
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Thorsten Wagner
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany
| | - Ay Lin Kho
- The Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Excellence Centre, New Hunt's House, Guy's Campus, London SE1 1UL, UK
| | - Mathias Gautel
- The Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, Kings College London BHF Excellence Centre, New Hunt's House, Guy's Campus, London SE1 1UL, UK
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany.
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41
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Zhao H, Young N, Kalchschmidt J, Lieberman J, El Khattabi L, Casellas R, Asturias FJ. Structure of mammalian Mediator complex reveals Tail module architecture and interaction with a conserved core. Nat Commun 2021; 12:1355. [PMID: 33649303 PMCID: PMC7921410 DOI: 10.1038/s41467-021-21601-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 02/01/2021] [Indexed: 01/04/2023] Open
Abstract
The Mediator complex plays an essential and multi-faceted role in regulation of RNA polymerase II transcription in all eukaryotes. Structural analysis of yeast Mediator has provided an understanding of the conserved core of the complex and its interaction with RNA polymerase II but failed to reveal the structure of the Tail module that contains most subunits targeted by activators and repressors. Here we present a molecular model of mammalian (Mus musculus) Mediator, derived from a 4.0 Å resolution cryo-EM map of the complex. The mammalian Mediator structure reveals that the previously unresolved Tail module, which includes a number of metazoan specific subunits, interacts extensively with core Mediator and has the potential to influence its conformation and interactions.
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Affiliation(s)
- Haiyan Zhao
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO, USA
| | - Natalie Young
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO, USA
| | | | | | - Laila El Khattabi
- Institut Cochin Laboratoire de Cytogénétique Constitutionnelle Pré et Post Natale, Paris, France
| | - Rafael Casellas
- Lymphocyte Nuclear Biology, NIAMS, NIH, Bethesda, MD, USA.,Center for Cancer Research, NCI, NIH, Bethesda, MD, USA
| | - Francisco J Asturias
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical School, Aurora, CO, USA.
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42
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Visualization of the mechanosensitive ion channel MscS under membrane tension. Nature 2021; 590:509-514. [PMID: 33568813 DOI: 10.1038/s41586-021-03196-w] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 01/06/2021] [Indexed: 12/20/2022]
Abstract
Mechanosensitive channels sense mechanical forces in cell membranes and underlie many biological sensing processes1-3. However, how exactly they sense mechanical force remains under investigation4. The bacterial mechanosensitive channel of small conductance, MscS, is one of the most extensively studied mechanosensitive channels4-8, but how it is regulated by membrane tension remains unclear, even though the structures are known for its open and closed states9-11. Here we used cryo-electron microscopy to determine the structure of MscS in different membrane environments, including one that mimics a membrane under tension. We present the structures of MscS in the subconducting and desensitized states, and demonstrate that the conformation of MscS in a lipid bilayer in the open state is dynamic. Several associated lipids have distinct roles in MscS mechanosensation. Pore lipids are necessary to prevent ion conduction in the closed state. Gatekeeper lipids stabilize the closed conformation and dissociate with membrane tension, allowing the channel to open. Pocket lipids in a solvent-exposed pocket between subunits are pulled out under sustained tension, allowing the channel to transition to the subconducting state and then to the desensitized state. Our results provide a mechanistic underpinning and expand on the 'force-from-lipids' model for MscS mechanosensation4,11.
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43
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Cohen SE, Brignole EJ, Wittenborn EC, Can M, Thompson S, Ragsdale SW, Drennan CL. Negative-Stain Electron Microscopy Reveals Dramatic Structural Rearrangements in Ni-Fe-S-Dependent Carbon Monoxide Dehydrogenase/Acetyl-CoA Synthase. Structure 2021; 29:43-49.e3. [PMID: 32937101 PMCID: PMC7796957 DOI: 10.1016/j.str.2020.08.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/13/2020] [Accepted: 08/25/2020] [Indexed: 10/23/2022]
Abstract
The Ni-Fe-S-containing A-cluster of acetyl-coenzyme A (CoA) synthase (ACS) assembles acetyl-CoA from carbon monoxide (CO), a methyl group (CH3+), and CoA. To accomplish this feat, ACS must bind CoA and interact with two other proteins that contribute the CO and CH3+, respectively: CO dehydrogenase (CODH) and corrinoid Fe-S protein (CFeSP). Previous structural data show that, in the model acetogen Moorella thermoacetica, domain 1 of ACS binds to CODH such that a 70-Å-long internal channel is created that allows CO to travel from CODH to the A-cluster. The A-cluster is largely buried and is inaccessible to CFeSP for methylation. Here we use electron microscopy to capture multiple snapshots of ACS that reveal previously uncharacterized domain motion, forming extended and hyperextended structural states. In these structural states, the A-cluster is accessible for methylation by CFeSP.
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Affiliation(s)
- Steven E Cohen
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Edward J Brignole
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Elizabeth C Wittenborn
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Mehmet Can
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Samuel Thompson
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Stephen W Ragsdale
- Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Catherine L Drennan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Fellow, Bio-inspired Solar Energy Program, Canadian Institute for Advanced Research (CIFAR), Toronto, ON M5G 1M1.
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44
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Ahmad S, Tsang KK, Sachar K, Quentin D, Tashin TM, Bullen NP, Raunser S, McArthur AG, Prehna G, Whitney JC. Structural basis for effector transmembrane domain recognition by type VI secretion system chaperones. eLife 2020; 9:e62816. [PMID: 33320089 PMCID: PMC7773334 DOI: 10.7554/elife.62816] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Accepted: 12/14/2020] [Indexed: 12/21/2022] Open
Abstract
Type VI secretion systems (T6SSs) deliver antibacterial effector proteins between neighboring bacteria. Many effectors harbor N-terminal transmembrane domains (TMDs) implicated in effector translocation across target cell membranes. However, the distribution of these TMD-containing effectors remains unknown. Here, we discover prePAAR, a conserved motif found in over 6000 putative TMD-containing effectors encoded predominantly by 15 genera of Proteobacteria. Based on differing numbers of TMDs, effectors group into two distinct classes that both require a member of the Eag family of T6SS chaperones for export. Co-crystal structures of class I and class II effector TMD-chaperone complexes from Salmonella Typhimurium and Pseudomonas aeruginosa, respectively, reveals that Eag chaperones mimic transmembrane helical packing to stabilize effector TMDs. In addition to participating in the chaperone-TMD interface, we find that prePAAR residues mediate effector-VgrG spike interactions. Taken together, our findings reveal mechanisms of chaperone-mediated stabilization and secretion of two distinct families of T6SS membrane protein effectors.
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Affiliation(s)
- Shehryar Ahmad
- Michael DeGroote Institute for Infectious Disease Research, McMaster UniversityHamiltonCanada
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamiltonCanada
| | - Kara K Tsang
- Michael DeGroote Institute for Infectious Disease Research, McMaster UniversityHamiltonCanada
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamiltonCanada
| | - Kartik Sachar
- Department of Microbiology, University of ManitobaWinnipegCanada
| | - Dennis Quentin
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | - Tahmid M Tashin
- Michael DeGroote Institute for Infectious Disease Research, McMaster UniversityHamiltonCanada
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamiltonCanada
| | - Nathan P Bullen
- Michael DeGroote Institute for Infectious Disease Research, McMaster UniversityHamiltonCanada
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamiltonCanada
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | - Andrew G McArthur
- Michael DeGroote Institute for Infectious Disease Research, McMaster UniversityHamiltonCanada
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamiltonCanada
- David Braley Centre for Antibiotic Discovery, McMaster UniversityHamiltonCanada
| | - Gerd Prehna
- Department of Microbiology, University of ManitobaWinnipegCanada
| | - John C Whitney
- Michael DeGroote Institute for Infectious Disease Research, McMaster UniversityHamiltonCanada
- Department of Biochemistry and Biomedical Sciences, McMaster UniversityHamiltonCanada
- David Braley Centre for Antibiotic Discovery, McMaster UniversityHamiltonCanada
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45
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Caesar J, Reboul CF, Machello C, Kiesewetter S, Tang ML, Deme JC, Johnson S, Elmlund D, Lea SM, Elmlund H. WITHDRAWN: SIMPLE 3.0. Stream single-particle cryo-EM analysis in real time. J Struct Biol 2020; 212:107635. [PMID: 33022362 DOI: 10.1016/j.jsb.2020.107635] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 09/26/2020] [Accepted: 09/28/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Joseph Caesar
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK; Central Oxford Structural Microscopy and Imaging Centre, University of Oxford, Oxford UK
| | - Cyril F Reboul
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Chiara Machello
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Simon Kiesewetter
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Molly L Tang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK; Central Oxford Structural Microscopy and Imaging Centre, University of Oxford, Oxford UK
| | - Justin C Deme
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK; Central Oxford Structural Microscopy and Imaging Centre, University of Oxford, Oxford UK
| | - Steven Johnson
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Dominika Elmlund
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Susan M Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK; Central Oxford Structural Microscopy and Imaging Centre, University of Oxford, Oxford UK.
| | - Hans Elmlund
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia.
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46
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Vinayagam D, Quentin D, Yu-Strzelczyk J, Sitsel O, Merino F, Stabrin M, Hofnagel O, Yu M, Ledeboer MW, Nagel G, Malojcic G, Raunser S. Structural basis of TRPC4 regulation by calmodulin and pharmacological agents. eLife 2020; 9:e60603. [PMID: 33236980 PMCID: PMC7735759 DOI: 10.7554/elife.60603] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 11/23/2020] [Indexed: 02/07/2023] Open
Abstract
Canonical transient receptor potential channels (TRPC) are involved in receptor-operated and/or store-operated Ca2+ signaling. Inhibition of TRPCs by small molecules was shown to be promising in treating renal diseases. In cells, the channels are regulated by calmodulin (CaM). Molecular details of both CaM and drug binding have remained elusive so far. Here, we report structures of TRPC4 in complex with three pyridazinone-based inhibitors and CaM. The structures reveal that all the inhibitors bind to the same cavity of the voltage-sensing-like domain and allow us to describe how structural changes from the ligand-binding site can be transmitted to the central ion-conducting pore of TRPC4. CaM binds to the rib helix of TRPC4, which results in the ordering of a previously disordered region, fixing the channel in its closed conformation. This represents a novel CaM-induced regulatory mechanism of canonical TRP channels.
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Affiliation(s)
| | - Dennis Quentin
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | - Jing Yu-Strzelczyk
- Department of Neurophysiology, Physiological Institute, Julius-Maximilians-Universität WürzburgWürzburgGermany
| | - Oleg Sitsel
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | - Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | - Markus Stabrin
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | - Oliver Hofnagel
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
| | | | | | - Georg Nagel
- Department of Neurophysiology, Physiological Institute, Julius-Maximilians-Universität WürzburgWürzburgGermany
| | | | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular PhysiologyDortmundGermany
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47
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Stabrin M, Schoenfeld F, Wagner T, Pospich S, Gatsogiannis C, Raunser S. TranSPHIRE: automated and feedback-optimized on-the-fly processing for cryo-EM. Nat Commun 2020; 11:5716. [PMID: 33177513 PMCID: PMC7658977 DOI: 10.1038/s41467-020-19513-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 10/15/2020] [Indexed: 12/17/2022] Open
Abstract
Single particle cryo-EM requires full automation to allow high-throughput structure determination. Although software packages exist where parts of the cryo-EM pipeline are automated, a complete solution that offers reliable on-the-fly processing, resulting in high-resolution structures, does not exist. Here we present TranSPHIRE: A software package for fully-automated processing of cryo-EM datasets during data acquisition. TranSPHIRE transfers data from the microscope, automatically applies the common pre-processing steps, picks particles, performs 2D clustering, and 3D refinement parallel to image recording. Importantly, TranSPHIRE introduces a machine learning-based feedback loop to re-train its picking model to adapt to any given data set live during processing. This elegant approach enables TranSPHIRE to process data more effectively, producing high-quality particle stacks. TranSPHIRE collects and displays all metrics and microscope settings to allow users to quickly evaluate data during acquisition. TranSPHIRE can run on a single work station and also includes the automated processing of filaments.
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Affiliation(s)
- Markus Stabrin
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227, Dortmund, Germany
| | - Fabian Schoenfeld
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227, Dortmund, Germany
| | - Thorsten Wagner
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227, Dortmund, Germany
| | - Sabrina Pospich
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227, Dortmund, Germany
| | - Christos Gatsogiannis
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Straße 11, 44227, Dortmund, Germany.
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48
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Caesar J, Reboul CF, Machello C, Kiesewetter S, Tang ML, Deme JC, Johnson S, Elmlund D, Lea SM, Elmlund H. SIMPLE 3.0. Stream single-particle cryo-EM analysis in real time. JOURNAL OF STRUCTURAL BIOLOGY-X 2020; 4:100040. [PMID: 33294840 PMCID: PMC7695977 DOI: 10.1016/j.yjsbx.2020.100040] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
We here introduce the third major release of the SIMPLE (Single-particle IMage Processing Linux Engine) open-source software package for analysis of cryogenic transmission electron microscopy (cryo-EM) movies of single-particles (Single-Particle Analysis, SPA). Development of SIMPLE 3.0 has been focused on real-time data processing using minimal CPU computing resources to allow easy and cost-efficient scaling of processing as data rates escalate. Our stream SPA tool implements the steps of anisotropic motion correction and CTF estimation, rapid template-based particle identification and 2D clustering with automatic class rejection. SIMPLE 3.0 additionally features an easy-to-use web-based graphical user interface (GUI) that can be run on any device (workstation, laptop, tablet or phone) and supports a remote multi-user environment over the network. The new project-based execution model automatically records the executed workflow and represents it as a flow diagram in the GUI. This facilitates meta-data handling and greatly simplifies usage. Using SIMPLE 3.0, it is possible to automatically obtain a clean SP data set amenable to high-resolution 3D reconstruction directly upon completion of the data acquisition, without the need for extensive image processing post collection. Only minimal standard CPU computing resources are required to keep up with a rate of ∼300 Gatan K3 direct electron detector movies per hour. SIMPLE 3.0 is available for download from simplecryoem.com.
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Affiliation(s)
- Joseph Caesar
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.,Central Oxford Structural Microscopy and Imaging Centre, University of Oxford, Oxford UK
| | - Cyril F Reboul
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Chiara Machello
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Simon Kiesewetter
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Molly L Tang
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.,Central Oxford Structural Microscopy and Imaging Centre, University of Oxford, Oxford UK
| | - Justin C Deme
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.,Central Oxford Structural Microscopy and Imaging Centre, University of Oxford, Oxford UK
| | - Steven Johnson
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Dominika Elmlund
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
| | - Susan M Lea
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.,Central Oxford Structural Microscopy and Imaging Centre, University of Oxford, Oxford UK
| | - Hans Elmlund
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia.,Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Melbourne, Victoria, Australia
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49
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Chung SC, Lin HH, Niu PY, Huang SH, Tu IP, Chang WH. Pre-pro is a fast pre-processor for single-particle cryo-EM by enhancing 2D classification. Commun Biol 2020; 3:508. [PMID: 32917929 PMCID: PMC7486923 DOI: 10.1038/s42003-020-01229-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 07/13/2020] [Indexed: 01/04/2023] Open
Abstract
2D classification plays a pivotal role in analyzing single particle cryo-electron microscopy images. Here, we introduce a simple and loss-less pre-processor that incorporates a fast dimension-reduction (2SDR) de-noiser to enhance 2D classification. By implementing this 2SDR pre-processor prior to a representative classification algorithm like RELION and ISAC, we compare the performances with and without the pre-processor. Tests on multiple cryo-EM experimental datasets show the pre-processor can make classification faster, improve yield of good particles and increase the number of class-average images to generate better initial models. Testing on the nanodisc-embedded TRPV1 dataset with high heterogeneity using a 3D reconstruction workflow with an initial model from class-average images highlights the pre-processor improves the final resolution to 2.82 Å, close to 0.9 Nyquist. Those findings and analyses suggest the 2SDR pre-processor, of minimal cost, is widely applicable for boosting 2D classification, while its generalization to accommodate neural network de-noisers is envisioned.
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Affiliation(s)
- Szu-Chi Chung
- Institute of Statistical Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - Hsin-Hung Lin
- Institute of Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - Po-Yao Niu
- Institute of Statistical Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - Shih-Hsin Huang
- Institute of Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan
| | - I-Ping Tu
- Institute of Statistical Science, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan.
| | - Wei-Hau Chang
- Institute of Chemistry, Academia Sinica, 128 Academia Road, Section 2, Nankang, Taipei, 11529, Taiwan.
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50
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Buitrago L, Zafar H, Zhang Y, Li J, Walz T, Coller BS. Dominant role of αIIbβ3 in platelet interactions with cross-linked fibrin fragment D-dimer. Blood Adv 2020; 4:2939-2949. [PMID: 32603423 PMCID: PMC7362365 DOI: 10.1182/bloodadvances.2020001545] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Accepted: 05/23/2020] [Indexed: 12/14/2022] Open
Abstract
Although much is known about the interaction of fibrinogen with αIIbβ3, much less is known about the interaction of platelets with cross-linked fibrin. Fibrinogen residue Lys406 plays a vital role in the interaction of fibrinogen with αIIbβ3, but because it participates in fibrin cross-linking, it is not available for interacting with αIIbβ3. We studied the adhesion of platelets and HEK cells expressing normal and constitutively active αIIbβ3 to both immobilized fibrinogen and D-dimer, a proteolytic fragment of cross-linked fibrin, as well as platelet-mediated clot retraction. Nonactivated platelets and HEK cells expressing normal αIIbβ3 adhered to fibrinogen but not D-dimer, whereas activated platelets as well as HEK cells expressing activated αIIbβ3 both bound to D-dimer. Small-molecule antagonists of the αIIbβ3 RGD (Arg-Gly-Asp) binding pocket inhibited adhesion to D-dimer, and an Asp119Ala mutation that disrupts the β3 metal ion-dependent adhesion site inhibited αIIbβ3-mediated adhesion to D-dimer. D-dimer and a polyclonal antibody against D-dimer inhibited clot retraction. The monoclonal antibody (mAb) 10E5, directed at αIIb and a potent inhibitor of platelet interactions with fibrinogen, did not inhibit the interaction of activated platelets with D-dimer or clot retraction, whereas the mAb 7E3, directed at β3, inhibited both phenomena. We conclude that activated, but not nonactivated, αIIbβ3 mediates interactions between platelets and D-dimer, and by extrapolation, to cross-linked fibrin. Although the interaction of αIIbβ3 with D-dimer differs from that with fibrinogen, it probably involves contributions from regions on β3 that are close to, or that are affected by, changes in the RGD binding pocket.
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Affiliation(s)
| | - Hina Zafar
- Laboratory of Blood and Vascular Biology and
| | - Yixiao Zhang
- Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, NY
| | - Jihong Li
- Laboratory of Blood and Vascular Biology and
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, Rockefeller University, New York, NY
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