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Alempic JM, Bisio H, Villalta A, Santini S, Lartigue A, Schmitt A, Bugnot C, Notaro A, Belmudes L, Adrait A, Poirot O, Ptchelkine D, De Castro C, Couté Y, Abergel C. Functional redundancy revealed by the deletion of the mimivirus GMC-oxidoreductase genes. MICROLIFE 2024; 5:uqae006. [PMID: 38659623 PMCID: PMC11042495 DOI: 10.1093/femsml/uqae006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2024] [Accepted: 04/04/2024] [Indexed: 04/26/2024]
Abstract
The mimivirus 1.2 Mb genome was shown to be organized into a nucleocapsid-like genomic fiber encased in the nucleoid compartment inside the icosahedral capsid. The genomic fiber protein shell is composed of a mixture of two GMC-oxidoreductase paralogs, one of them being the main component of the glycosylated layer of fibrils at the surface of the virion. In this study, we determined the effect of the deletion of each of the corresponding genes on the genomic fiber and the layer of surface fibrils. First, we deleted the GMC-oxidoreductase, the most abundant in the genomic fiber, and determined its structure and composition in the mutant. As expected, it was composed of the second GMC-oxidoreductase and contained 5- and 6-start helices similar to the wild-type fiber. This result led us to propose a model explaining their coexistence. Then we deleted the GMC-oxidoreductase, the most abundant in the layer of fibrils, to analyze its protein composition in the mutant. Second, we showed that the fitness of single mutants and the double mutant were not decreased compared with the wild-type viruses under laboratory conditions. Third, we determined that deleting the GMC-oxidoreductase genes did not impact the glycosylation or the glycan composition of the layer of surface fibrils, despite modifying their protein composition. Because the glycosylation machinery and glycan composition of members of different clades are different, we expanded the analysis of the protein composition of the layer of fibrils to members of the B and C clades and showed that it was different among the three clades and even among isolates within the same clade. Taken together, the results obtained on two distinct central processes (genome packaging and virion coating) illustrate an unexpected functional redundancy in members of the family Mimiviridae, suggesting this may be the major evolutionary force behind their giant genomes.
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Affiliation(s)
- Jean-Marie Alempic
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
| | - Hugo Bisio
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
| | - Alejandro Villalta
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
| | - Sébastien Santini
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
| | - Audrey Lartigue
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
| | - Alain Schmitt
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
| | - Claire Bugnot
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
| | - Anna Notaro
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055 Portici, Italy
| | - Lucid Belmudes
- Univ. Grenoble Alpes, CEA, INSERM, UA13 BGE, CNRS, CEA, FR2048, 38000 Grenoble, France
| | - Annie Adrait
- Univ. Grenoble Alpes, CEA, INSERM, UA13 BGE, CNRS, CEA, FR2048, 38000 Grenoble, France
| | - Olivier Poirot
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
| | - Denis Ptchelkine
- Aix–Marseille University, Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques, Unité Mixte de Recherche 7257 (IM2B), 13288 Marseille Cedex 9, France
| | - Cristina De Castro
- Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055 Portici, Italy
| | - Yohann Couté
- Univ. Grenoble Alpes, CEA, INSERM, UA13 BGE, CNRS, CEA, FR2048, 38000 Grenoble, France
| | - Chantal Abergel
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale (IGS), Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B, IOM), 13288 Marseille Cedex 9, France
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Huber ST, Jakobi AJ. Structural biology of microbial gas vesicles: historical milestones and current knowledge. Biochem Soc Trans 2024; 52:205-215. [PMID: 38329160 PMCID: PMC10903477 DOI: 10.1042/bst20230396] [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: 12/14/2023] [Revised: 01/10/2024] [Accepted: 01/16/2024] [Indexed: 02/09/2024]
Abstract
Gas vesicles mediate buoyancy-based motility in aquatic bacteria and archaea and are the only protein-based structures known to enclose a gas-filled volume. Their unique physicochemical properties and ingenious architecture rank them among the most intriguing macromolecular assemblies characterised to date. This review covers the 60-year journey in quest for a high-resolution structural model of gas vesicles, first highlighting significant strides made in establishing the detailed ultrastructure of gas vesicles through transmission electron microscopy, X-ray fibre diffraction, atomic force microscopy, and NMR spectroscopy. We then survey the recent progress in cryogenic electron microscopy studies of gas vesicles, which eventually led to a comprehensive atomic model of the mature assembly. Synthesising insight from these structures, we examine possible mechanisms of gas vesicle biogenesis and growth, presenting a testable model to guide future experimental work. We conclude by discussing future directions in the structural biology of gas vesicles, particularly considering advancements in AI-driven structure prediction.
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Affiliation(s)
- Stefan T. Huber
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Arjen J. Jakobi
- Department of Bionanoscience, Kavli Institute of Nanoscience, Delft University of Technology, 2629 HZ Delft, The Netherlands
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Mishra S. Emerging Trends in Cryo-EM-based Structural Studies of Neuropathological Amyloids. J Mol Biol 2023; 435:168361. [PMID: 37949311 DOI: 10.1016/j.jmb.2023.168361] [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: 09/29/2023] [Revised: 11/02/2023] [Accepted: 11/03/2023] [Indexed: 11/12/2023]
Abstract
Tauopathies, synucleinopathies, Aβ amyloidosis, TDP-43 proteinopathies, and prion diseases- these neurodegenerative diseases have in common the formation of amyloid filaments rich in cross-β sheets. Cryo-electron microscopy now permits the visualization of amyloid assemblies at atomic resolution, ushering a wide range of structural studies on several of these poorly understood amyloidogenic proteins. Amyloids are polymorphic with minor modulations in reaction environment affecting the overall architecture of their assembly, making amyloids an extremely challenging venture for structure-based therapeutic intervention. In 2017, the first cryo-EM structure of tau filaments from an Alzheimer's disease-affected brain established that in vitro assemblies might not necessarily reflect the native amyloid fold. Since then, brain-derived amyloid structures for several proteins across many neurodegenerative diseases have uncovered the disease-relevant amyloid folds. It has now been shown for tauopathies, synucleinopathies and TDP-43 proteinopathies, that distinct amyloid folds of the same protein might be related to different diseases. Salient features of each of these brain-derived folds are discussed in detail. It was also recently observed that seeded aggregation does not necessarily replicate the brain-derived structural fold. Owing to high throughput structure determination, some of these native amyloid folds have also been successfully replicated in vitro. In vitro replication of disease-relevant filaments will aid development of imaging ligands and defibrillating drugs. Towards this direction, recent high-resolution structures of tau filaments with positron emission tomography tracers and a defibrillating drug are also discussed. This review summarizes and celebrates the recent advancements in structural understanding of neuropathological amyloid filaments using cryo-EM.
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Affiliation(s)
- Suman Mishra
- Molecular Biophysics Unit, Biological Sciences Division, Indian Institute of Science, Bengaluru 560 012, Karnataka, India.
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Villalta A, Schmitt A, Estrozi LF, Quemin ERJ, Alempic JM, Lartigue A, Pražák V, Belmudes L, Vasishtan D, Colmant AMG, Honoré FA, Couté Y, Grünewald K, Abergel C. The giant mimivirus 1.2 Mb genome is elegantly organized into a 30-nm diameter helical protein shield. eLife 2022; 11:e77607. [PMID: 35900198 PMCID: PMC9512402 DOI: 10.7554/elife.77607] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 07/27/2022] [Indexed: 11/13/2022] Open
Abstract
Mimivirus is the prototype of the Mimiviridae family of giant dsDNA viruses. Little is known about the organization of the 1.2 Mb genome inside the membrane-limited nucleoid filling the ~0.5 µm icosahedral capsids. Cryo-electron microscopy, cryo-electron tomography, and proteomics revealed that it is encased into a ~30-nm diameter helical protein shell surprisingly composed of two GMC-type oxidoreductases, which also form the glycosylated fibrils decorating the capsid. The genome is arranged in 5- or 6-start left-handed super-helices, with each DNA-strand lining the central channel. This luminal channel of the nucleoprotein fiber is wide enough to accommodate oxidative stress proteins and RNA polymerase subunits identified by proteomics. Such elegant supramolecular organization would represent a remarkable evolutionary strategy for packaging and protecting the genome, in a state ready for immediate transcription upon unwinding in the host cytoplasm. The parsimonious use of the same protein in two unrelated substructures of the virion is unexpected for a giant virus with thousand genes at its disposal.
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Affiliation(s)
- Alejandro Villalta
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale, Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B)MarseilleFrance
| | - Alain Schmitt
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale, Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B)MarseilleFrance
| | - Leandro F Estrozi
- Univ. Grenoble Alpes, CNRS, CEA, Institut de Biologie Structurale (IBS)GrenobleFrance
| | - Emmanuelle RJ Quemin
- Centre for Structural Systems Biology, Leibniz Institute for Experimental Virology (HPI), University of HamburgHamburgGermany
| | - Jean-Marie Alempic
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale, Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B)MarseilleFrance
| | - Audrey Lartigue
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale, Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B)MarseilleFrance
| | - Vojtěch Pražák
- Centre for Structural Systems Biology, Leibniz Institute for Experimental Virology (HPI), University of HamburgHamburgGermany
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Lucid Belmudes
- Univ. Grenoble Alpes, CEA, INSERM, IRIG, BGEGrenobleFrance
| | - Daven Vasishtan
- Centre for Structural Systems Biology, Leibniz Institute for Experimental Virology (HPI), University of HamburgHamburgGermany
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Agathe MG Colmant
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale, Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B)MarseilleFrance
| | - Flora A Honoré
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale, Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B)MarseilleFrance
| | - Yohann Couté
- Univ. Grenoble Alpes, CEA, INSERM, IRIG, BGEGrenobleFrance
| | - Kay Grünewald
- Centre for Structural Systems Biology, Leibniz Institute for Experimental Virology (HPI), University of HamburgHamburgGermany
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Chantal Abergel
- Aix–Marseille University, Centre National de la Recherche Scientifique, Information Génomique & Structurale, Unité Mixte de Recherche 7256 (Institut de Microbiologie de la Méditerranée, FR3479, IM2B)MarseilleFrance
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5
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Miller JG, Hughes SA, Modlin C, Conticello VP. Structures of synthetic helical filaments and tubes based on peptide and peptido-mimetic polymers. Q Rev Biophys 2022; 55:1-103. [PMID: 35307042 DOI: 10.1017/s0033583522000014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
AbstractSynthetic peptide and peptido-mimetic filaments and tubes represent a diverse class of nanomaterials with a broad range of potential applications, such as drug delivery, vaccine development, synthetic catalyst design, encapsulation, and energy transduction. The structures of these filaments comprise supramolecular polymers based on helical arrangements of subunits that can be derived from self-assembly of monomers based on diverse structural motifs. In recent years, structural analyses of these materials at near-atomic resolution (NAR) have yielded critical insights into the relationship between sequence, local conformation, and higher-order structure and morphology. This structural information offers the opportunity for development of new tools to facilitate the predictable and reproduciblede novodesign of synthetic helical filaments. However, these studies have also revealed several significant impediments to the latter process – most notably, the common occurrence of structural polymorphism due to the lability of helical symmetry in structural space. This article summarizes the current state of knowledge on the structures of designed peptide and peptido-mimetic filamentous assemblies, with a focus on structures that have been solved to NAR for which reliable atomic models are available.
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Affiliation(s)
- Jessalyn G Miller
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA30322
| | - Spencer A Hughes
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA30322
| | - Charles Modlin
- Department of Chemistry, Emory University, 1515 Dickey Drive, Atlanta, GA30322
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Zhang X. Python-based Helix Indexer: A graphical user interface program for finding symmetry of helical assembly through Fourier-Bessel indexing of electron microscopic data. Protein Sci 2022; 31:107-117. [PMID: 34529294 PMCID: PMC8740834 DOI: 10.1002/pro.4186] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/07/2021] [Accepted: 09/07/2021] [Indexed: 01/03/2023]
Abstract
Many macromolecules form helical assemblies to carry out their functions. Helical reconstruction from electron microscopic images is a powerful approach for solving high-resolution structures of such assemblies. Determination of the symmetry parameters of the helical assemblies is a prerequisite step in helical reconstruction. The most widely used method for deducing the symmetry is through Fourier-Bessel indexing the diffraction pattern of the helical assemblies. This method, however, often leads to incorrect solutions, due to intrinsic ambiguities in indexing helical diffraction patterns. Here, we present Python-based Helix Indexer (PyHI), which provides a graphical user interface (GUI) to guide the users through the process of symmetry determination. Diffraction patterns can be read into the program directly or calculated on the fly from two-dimensional class averages of helical assemblies. PyHI allows deducing the Bessel orders of diffraction peaks by using both the amplitudes and phases of the diffraction data. Based on the Bessel orders of two unit vectors, the Fourier space lattice is constructed with minimal user inputs. The program then uses a refinement algorithm to optimize the Fourier space lattice, and subsequently generate the helical assembly in real space. The program provides both a publication-quality graphic representation of the helical assembly and the symmetry parameters required for subsequent helical reconstruction steps.
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Affiliation(s)
- Xuewu Zhang
- Department of PharmacologyUniversity of Texas Southwestern Medical CenterDallasTexas,Department of BiophysicsUniversity of Texas Southwestern Medical CenterDallasTexas
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Lutter L, Serpell CJ, Tuite MF, Serpell LC, Xue WF. Three-dimensional reconstruction of individual helical nano-filament structures from atomic force microscopy topographs. Biomol Concepts 2020; 11:102-115. [PMID: 32374275 DOI: 10.1515/bmc-2020-0009] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 03/30/2020] [Indexed: 08/19/2023] Open
Abstract
Atomic force microscopy, AFM, is a powerful tool that can produce detailed topographical images of individual nano-structures with a high signal-to-noise ratio without the need for ensemble averaging. However, the application of AFM in structural biology has been hampered by the tip-sample convolution effect, which distorts images of nano-structures, particularly those that are of similar dimensions to the cantilever probe tips used in AFM. Here we show that the tip-sample convolution results in a feature-dependent and non-uniform distribution of image resolution on AFM topographs. We show how this effect can be utilised in structural studies of nano-sized upward convex objects such as spherical or filamentous molecular assemblies deposited on a flat surface, because it causes 'magnification' of such objects in AFM topographs. Subsequently, this enhancement effect is harnessed through contact-point based deconvolution of AFM topographs. Here, the application of this approach is demonstrated through the 3D reconstruction of the surface envelope of individual helical amyloid filaments without the need of cross-particle averaging using the contact-deconvoluted AFM topographs. Resolving the structural variations of individual macromolecular assemblies within inherently heterogeneous populations is paramount for mechanistic understanding of many biological phenomena such as amyloid toxicity and prion strains. The approach presented here will also facilitate the use of AFM for high-resolution structural studies and integrative structural biology analysis of single molecular assemblies.
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Affiliation(s)
- Liisa Lutter
- Kent Fungal Group, School of Biosciences, University of Kent, CT2 7NJ, Canterbury, UK
| | | | - Mick F Tuite
- Kent Fungal Group, School of Biosciences, University of Kent, CT2 7NJ, Canterbury, UK
| | - Louise C Serpell
- Sussex Neuroscience, School of Life Sciences, University of Sussex, BN1 9QG, Falmer, Brighton, UK
| | - Wei-Feng Xue
- Kent Fungal Group, School of Biosciences, University of Kent, CT2 7NJ, Canterbury, UK
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8
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de Oliveira GAP, Cordeiro Y, Silva JL, Vieira TCRG. Liquid-liquid phase transitions and amyloid aggregation in proteins related to cancer and neurodegenerative diseases. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2019; 118:289-331. [PMID: 31928729 DOI: 10.1016/bs.apcsb.2019.08.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Liquid-liquid phase separation (LLPS) and phase transition (LLPT) of proteins and nucleic acids have emerged as a new paradigm in cell biology. Here we will describe the recent findings about LLPS and LLPT, including the molecular and physical determinants leading to their formation, the resulting functions and their implications in cell physiology and disease. Amyloid aggregation is implicated in many neurodegenerative diseases and cancer, and LLPS of proteins involved in these diseases appear to be related to their function in different cell contexts. Amyloid formation would correspond to an irreversible liquid-to-solid transition, as clearly observed in the case of PrP, TDP43, FUS/TLS and tau protein in neurodegenerative pathologies as well as with the mutant tumor suppressor p53 in cancer. Nucleic acids play a modulatory effect on both LLPS and amyloid aggregation. Understanding the molecular events regulating how the demixing process advances to solid-like fibril materials is crucial for the development of novel therapeutic strategies against cancer and neurodegenerative maladies.
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Affiliation(s)
- Guilherme A P de Oliveira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil; Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, United States
| | - Yraima Cordeiro
- Faculty of Pharmacy, Federal University of Rio de Janeiro, Rio de Janeiro-RJ, Brazil
| | - Jerson L Silva
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Tuane C R G Vieira
- Programa de Biologia Estrutural, Instituto de Bioquímica Médica Leopoldo de Meis, Instituto Nacional de Biologia Estrutural e Bioimagem, Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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Hughes SA, Wang F, Wang S, Kreutzberger MAB, Osinski T, Orlova A, Wall JS, Zuo X, Egelman EH, Conticello VP. Ambidextrous helical nanotubes from self-assembly of designed helical hairpin motifs. Proc Natl Acad Sci U S A 2019; 116:14456-14464. [PMID: 31262809 PMCID: PMC6642399 DOI: 10.1073/pnas.1903910116] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Tandem repeat proteins exhibit native designability and represent potentially useful scaffolds for the construction of synthetic biomimetic assemblies. We have designed 2 synthetic peptides, HEAT_R1 and LRV_M3Δ1, based on the consensus sequences of single repeats of thermophilic HEAT (PBS_HEAT) and Leucine-Rich Variant (LRV) structural motifs, respectively. Self-assembly of the peptides afforded high-aspect ratio helical nanotubes. Cryo-electron microscopy with direct electron detection was employed to analyze the structures of the solvated filaments. The 3D reconstructions from the cryo-EM maps led to atomic models for the HEAT_R1 and LRV_M3Δ1 filaments at resolutions of 6.0 and 4.4 Å, respectively. Surprisingly, despite sequence similarity at the lateral packing interface, HEAT_R1 and LRV_M3Δ1 filaments adopt the opposite helical hand and differ significantly in helical geometry, while retaining a local conformation similar to previously characterized repeat proteins of the same class. The differences in the 2 filaments could be rationalized on the basis of differences in cohesive interactions at the lateral and axial interfaces. These structural data reinforce previous observations regarding the structural plasticity of helical protein assemblies and the need for high-resolution structural analysis. Despite these observations, the native designability of tandem repeat proteins offers the opportunity to engineer novel helical nanotubes. Moreover, the resultant nanotubes have independently addressable and chemically distinguishable interior and exterior surfaces that would facilitate applications in selective recognition, transport, and release.
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Affiliation(s)
| | - Fengbin Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908
| | - Shengyuan Wang
- Department of Chemistry, Emory University, Atlanta, GA 30322
| | - Mark A B Kreutzberger
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908
| | - Tomasz Osinski
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908
| | - Albina Orlova
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908
| | - Joseph S Wall
- Department of Biology, Brookhaven National Laboratory, Upton, NY 11973
| | - Xiaobing Zuo
- X-Ray Science Division, Argonne National Laboratory, Argonne, IL 60439
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908
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Li X, Buda F, de Groot HJ, Sevink GJA. Contrasting Modes of Self-Assembly and Hydrogen-Bonding Heterogeneity in Chlorosomes of Chlorobaculum tepidum. THE JOURNAL OF PHYSICAL CHEMISTRY. C, NANOMATERIALS AND INTERFACES 2018; 122:14877-14888. [PMID: 30258522 PMCID: PMC6150686 DOI: 10.1021/acs.jpcc.8b01790] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 05/30/2018] [Indexed: 06/08/2023]
Abstract
Chlorosome antennae form an interesting class of materials for studying the role of structural motifs and dynamics in nonadiabatic energy transfer. They perform robust and highly quantum-efficient transfer of excitonic energy while allowing for compositional variation and completely lacking the usual regulatory proteins. Here, we first cast the geometrical analysis for ideal tubular scaffolding models into a formal framework, to relate effective helical properties of the assembly structures to established characterization data for various types of chlorosomes. This analysis shows that helicity is uniquely defined for chlorosomes composed of bacteriochlorophyll (BChl) d and that three chiral angles are consistent with the nuclear magnetic resonance (NMR) and electron microscope data for BChl c, including two novel ones that are at variance with current interpretations of optical data based on perfect cylindrical symmetry. We use this information as a starting point for investigating dynamic and static heterogeneity at the molecular level by unconstrained molecular dynamics. We first identify a rotational degree of freedom, along the Mg-OH coordination bond, that alternates along the syn-anti stacks and underlies the (flexible) curvature on a larger scale. Because rotation directly relates to the formation or breaking of interstack hydrogen bonds of the O-H···O=C structural motif along the syn-anti stacks, we analyzed the relative fractions of hydrogen-bonded and the nonbonded regions, forming stripe domains in otherwise spectroscopically homogeneous curved slabs. The ratios 7:3 for BChl c and 9:1 for BChl d for the two distinct structural components agree well with the signal intensities determined by NMR. In addition, rotation with curvature-independent formation of stripe domains offers a viable explanation for the localization and dispersion of exciton states over two fractions, as observed in single chlorosome fluorescence decay studies.
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Abstract
Determining high-resolution structures of proteins with helical symmetry can be challenging due to limitations in experimental data. In such instances, structure-based protein simulations driven by experimental data can provide a valuable approach for building models of helical assemblies. This chapter describes how the Rosetta macromolecular package can be used to model homomeric protein assemblies with helical symmetry in a range of modeling scenarios including energy refinement, symmetrical docking, comparative modeling, and de novo structure prediction. Data-guided structure modeling of helical assemblies with experimental information from electron density, X-ray fiber diffraction, solid-state NMR, and chemical cross-linking mass spectrometry is also described.
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Affiliation(s)
- Ingemar André
- Department of Biochemistry and Structural Biology, Center for Molecular Protein Science, Lund University, Lund, Sweden.
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Huber ST, Kuhm T, Sachse C. Automated tracing of helical assemblies from electron cryo-micrographs. J Struct Biol 2017; 202:1-12. [PMID: 29191673 PMCID: PMC5847486 DOI: 10.1016/j.jsb.2017.11.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 11/24/2017] [Accepted: 11/26/2017] [Indexed: 01/17/2023]
Abstract
Structure determination of helical specimens commonly requires datasets from thousands of micrographs often obtained by automated cryo-EM data acquisition. Interactive tracing of helical assemblies from such a number of micrographs is labor-intense and time-consuming. Here, we introduce an automated tracing tool MicHelixTrace that precisely locates helix traces from micrographs of rigid as well as very flexible helical assemblies with small numbers of false positives. The computer program is fast and has low computational requirements. In addition to helix coordinates required for a subsequent helical reconstruction work-flow, we determine the persistence length of the polymer ensemble. This information provides a useful measure to characterize mechanical properties of helical assemblies and to evaluate the potential for high-resolution structure determination.
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Affiliation(s)
- Stefan T Huber
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Tanja Kuhm
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany
| | - Carsten Sachse
- European Molecular Biology Laboratory (EMBL), Structural and Computational Biology Unit, Meyerhofstraße 1, 69117 Heidelberg, Germany.
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Unique architecture of thermophilic archaeal virus APBV1 and its genome packaging. Nat Commun 2017; 8:1436. [PMID: 29127347 PMCID: PMC5681674 DOI: 10.1038/s41467-017-01668-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 10/05/2017] [Indexed: 12/13/2022] Open
Abstract
Archaeal viruses have evolved to infect hosts often thriving in extreme conditions such as high temperatures. However, there is a paucity of information on archaeal virion structures, genome packaging, and determinants of temperature resistance. The rod-shaped virus APBV1 (Aeropyrum pernix bacilliform virus 1) is among the most thermostable viruses known; it infects a hyperthermophile Aeropyrum pernix, which grows optimally at 90 °C. Here we report the structure of APBV1, determined by cryo-electron microscopy at near-atomic resolution. Tight packing of the major virion glycoprotein (VP1) is ensured by extended hydrophobic interfaces, and likely contributes to the extreme thermostability of the helical capsid. The double-stranded DNA is tightly packed in the capsid as a left-handed superhelix and held in place by the interactions with positively charged residues of VP1. The assembly is closed by specific capping structures at either end, which we propose to play a role in DNA packing and delivery. The rod-shaped virus APBV1 is among the most thermostable viruses known. Here, Ptchelkine et al. determine its structure at near-atomic resolution, show that the DNA is packed as left-handed superhelix and identify extended hydrophobic interfaces that likely contribute to the extreme thermostability of the capsid.
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In vitro assembly of the Rous Sarcoma Virus capsid protein into hexamer tubes at physiological temperature. Sci Rep 2017; 7:2913. [PMID: 28588198 PMCID: PMC5460288 DOI: 10.1038/s41598-017-02060-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 04/06/2017] [Indexed: 12/21/2022] Open
Abstract
During a proteolytically-driven maturation process, the orthoretroviral capsid protein (CA) assembles to form the convex shell that surrounds the viral genome. In some orthoretroviruses, including Rous Sarcoma Virus (RSV), CA carries a short and hydrophobic spacer peptide (SP) at its C-terminus early in the maturation process, which is progressively removed as maturation proceeds. In this work, we show that RSV CA assembles in vitro at near-physiological temperatures, forming hexamer tubes that effectively model the mature capsid surface. Tube assembly is strongly influenced by electrostatic effects, and is a nucleated process that remains thermodynamically favored at lower temperatures, but is effectively arrested by the large Gibbs energy barrier associated with nucleation. RSV CA tubes are multi-layered, being formed by nested and concentric tubes of capsid hexamers. However the spacer peptide acts as a layering determinant during tube assembly. If only a minor fraction of CA-SP is present, multi-layered tube formation is blocked, and single-layered tubes predominate. This likely prevents formation of biologically aberrant multi-layered capsids in the virion. The generation of single-layered hexamer tubes facilitated 3D helical image reconstruction from cryo-electron microscopy data, revealing the basic tube architecture.
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15
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Fromm S, Sachse C. Cryo-EM Structure Determination Using Segmented Helical Image Reconstruction. Methods Enzymol 2016; 579:307-28. [DOI: 10.1016/bs.mie.2016.05.034] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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