1
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Nashchekin D, Squires I, Prokop A, St Johnston D. The Shot CH1 domain recognises a distinct form of F-actin during Drosophila oocyte determination. Development 2024; 151:dev202370. [PMID: 38564309 PMCID: PMC11058685 DOI: 10.1242/dev.202370] [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: 09/21/2023] [Accepted: 03/04/2024] [Indexed: 04/04/2024]
Abstract
In Drosophila, only one cell in a multicellular female germline cyst is specified as an oocyte and a similar process occurs in mammals. The symmetry-breaking cue for oocyte selection is provided by the fusome, a tubular structure connecting all cells in the cyst. The Drosophila spectraplakin Shot localises to the fusome and translates its asymmetry into a polarised microtubule network that is essential for oocyte specification, but how Shot recognises the fusome is unclear. Here, we demonstrate that the actin-binding domain (ABD) of Shot is necessary and sufficient to localise Shot to the fusome and mediates Shot function in oocyte specification together with the microtubule-binding domains. The calponin homology domain 1 of the Shot ABD recognises fusomal F-actin and requires calponin homology domain 2 to distinguish it from other forms of F-actin in the cyst. By contrast, the ABDs of utrophin, Fimbrin, Filamin, Lifeact and F-tractin do not recognise fusomal F-actin. We therefore propose that Shot propagates fusome asymmetry by recognising a specific conformational state of F-actin on the fusome.
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Affiliation(s)
- Dmitry Nashchekin
- The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Iolo Squires
- The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
| | - Andreas Prokop
- The University of Manchester, Manchester Academic Health Science Centre, Faculty of Biology, Medicine and Health, School of Biology, Manchester M13 9PT, UK
| | - Daniel St Johnston
- The Gurdon Institute and the Department of Genetics, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK
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2
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Gunasekara H, Perera T, Chao CJ, Bruno J, Saed B, Anderson J, Zhao Z, Hu YS. Quantitative Superresolution Imaging of F-Actin in the Cell Body and Cytoskeletal Protrusions Using Phalloidin-Based Single-Molecule Labeling and Localization Microscopy. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.04.583337. [PMID: 38496456 PMCID: PMC10942307 DOI: 10.1101/2024.03.04.583337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
We present single-molecule labeling and localization microscopy (SMLLM) using dye-conjugated phalloidin to achieve enhanced superresolution imaging of filamentous actin (F-actin). We demonstrate that the intrinsic phalloidin dissociation enables SMLLM in an imaging buffer containing low concentrations of dye-conjugated phalloidin. We further show enhanced single-molecule labeling by chemically promoting phalloidin dissociation. Two benefits of phalloidin-based SMLLM are better preservation of cellular structures sensitive to mechanical and shear forces during standard sample preparation and more consistent F-actin quantification at the nanoscale. In a proof-of-concept study, we employed SMLLM to super-resolve F-actin structures in U2OS and dendritic cells (DCs) and demonstrate more consistent F-actin quantification in the cell body and structurally delicate cytoskeletal proportions, which we termed membrane fibers, of DCs compared to direct stochastic optical reconstruction microscopy (dSTORM). Using DC2.4 mouse dendritic cells as the model system, we show F-actin redistribution from podosomes to actin filaments and altered prevalence of F-actin-associated membrane fibers on the culture glass surface after lipopolysaccharide exposure. While our work demonstrates SMLLM for F-actin, the concept opens new possibilities for protein-specific single-molecule labeling and localization in the same step using commercially available reagents.
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Affiliation(s)
- Hirushi Gunasekara
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, 60607, USA
| | - Thilini Perera
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, 60607, USA
| | - Chih-Jia Chao
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois Chicago, Chicago, IL, 60612, USA
| | - Joshua Bruno
- Department of Biological Sciences, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, 60607, USA
| | - Badeia Saed
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, 60607, USA
| | - Jesse Anderson
- Department of Chemical Engineering, College of Engineering, University of Illinois Chicago, Chicago, IL, 60607, USA
| | - Zongmin Zhao
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Illinois Chicago, Chicago, IL, 60612, USA
| | - Ying S. Hu
- Department of Chemistry, College of Liberal Arts and Sciences, University of Illinois Chicago, Chicago, IL, 60607, USA
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3
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Verrier N, Debailleul M, Haeberlé O. Recent Advances and Current Trends in Transmission Tomographic Diffraction Microscopy. SENSORS (BASEL, SWITZERLAND) 2024; 24:1594. [PMID: 38475130 DOI: 10.3390/s24051594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 02/21/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024]
Abstract
Optical microscopy techniques are among the most used methods in biomedical sample characterization. In their more advanced realization, optical microscopes demonstrate resolution down to the nanometric scale. These methods rely on the use of fluorescent sample labeling in order to break the diffraction limit. However, fluorescent molecules' phototoxicity or photobleaching is not always compatible with the investigated samples. To overcome this limitation, quantitative phase imaging techniques have been proposed. Among these, holographic imaging has demonstrated its ability to image living microscopic samples without staining. However, for a 3D assessment of samples, tomographic acquisitions are needed. Tomographic Diffraction Microscopy (TDM) combines holographic acquisitions with tomographic reconstructions. Relying on a 3D synthetic aperture process, TDM allows for 3D quantitative measurements of the complex refractive index of the investigated sample. Since its initial proposition by Emil Wolf in 1969, the concept of TDM has found a lot of applications and has become one of the hot topics in biomedical imaging. This review focuses on recent achievements in TDM development. Current trends and perspectives of the technique are also discussed.
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Affiliation(s)
- Nicolas Verrier
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, 68093 Mulhouse, France
| | - Matthieu Debailleul
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, 68093 Mulhouse, France
| | - Olivier Haeberlé
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, 68093 Mulhouse, France
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4
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Yuan B, Scholz J, Wald J, Thuenauer R, Hennell James R, Ellenberg I, Windhorst S, Faix J, Marlovits TC. Structural basis for subversion of host cell actin cytoskeleton during Salmonella infection. SCIENCE ADVANCES 2023; 9:eadj5777. [PMID: 38064550 PMCID: PMC10708208 DOI: 10.1126/sciadv.adj5777] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Accepted: 11/09/2023] [Indexed: 12/18/2023]
Abstract
Secreted bacterial type III secretion system (T3SS) proteins are essential for successful infection by many human pathogens. Both T3SS translocator SipC and effector SipA are critical for Salmonella infection by subversion of the host cell cytoskeleton, but the precise molecular interplay between them remains unknown. Here, using cryo-electron microscopy, we show that SipA binds along the F-actin grooves with a unique binding pattern. SipA stabilizes F-actin through charged interface residues and appears to prevent inorganic phosphate release through closure of the "back door" of adenosine 5'-triphosphate pocket. We also show that SipC enhances the binding of SipA to F-actin, thus demonstrating that a sequential presence of T3SS proteins in host cells is associated with a sequence of infection events-starting with actin nucleation, filament growth, and stabilization. Together, our data explain the coordinated interplay of a precisely tuned and highly effective mechanism during Salmonella infection and provide a blueprint for interfering with Salmonella effectors acting on actin.
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Affiliation(s)
- Biao Yuan
- University Medical Center Hamburg-Eppendorf (UKE), Institute of Structural and Systems Biology, Hamburg, Germany
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Deutsches Elektronen-Synchrotron Zentrum (DESY), Hamburg, Germany
| | - Jonas Scholz
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Jiri Wald
- University Medical Center Hamburg-Eppendorf (UKE), Institute of Structural and Systems Biology, Hamburg, Germany
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Deutsches Elektronen-Synchrotron Zentrum (DESY), Hamburg, Germany
| | - Roland Thuenauer
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Technology Platform Light Microscopy (TPLM), University of Hamburg, Hamburg, Germany
- Technology Platform Microscopy and Image Analysis (TP MIA), Leibniz Institute of Virology (LIV), Hamburg, Germany
| | - Rory Hennell James
- University Medical Center Hamburg-Eppendorf (UKE), Institute of Structural and Systems Biology, Hamburg, Germany
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Deutsches Elektronen-Synchrotron Zentrum (DESY), Hamburg, Germany
| | - Irina Ellenberg
- University Medical Center Hamburg-Eppendorf (UKE), Institute for Biochemistry and Signal Transduction, Hamburg, Germany
| | - Sabine Windhorst
- University Medical Center Hamburg-Eppendorf (UKE), Institute for Biochemistry and Signal Transduction, Hamburg, Germany
| | - Jan Faix
- Institute for Biophysical Chemistry, Hannover Medical School, Hannover, Germany
| | - Thomas C. Marlovits
- University Medical Center Hamburg-Eppendorf (UKE), Institute of Structural and Systems Biology, Hamburg, Germany
- Centre for Structural Systems Biology (CSSB), Hamburg, Germany
- Deutsches Elektronen-Synchrotron Zentrum (DESY), Hamburg, Germany
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5
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Effiong UM, Khairandish H, Ramirez-Velez I, Wang Y, Belardi B. Turn-On Protein Switches for Controlling Actin Binding in Cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.26.561921. [PMID: 37961502 PMCID: PMC10634840 DOI: 10.1101/2023.10.26.561921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Within a shared cytoplasm, filamentous actin (F-actin) plays numerous and critical roles across the cell body. Cells rely on actin-binding proteins (ABPs) to organize F-actin and to integrate its polymeric characteristics into diverse cellular processes. Yet, the multitude of ABPs that engage with and shape F-actin make studying a single ABP's influence on cellular activities a significant challenge. Moreover, without a means of manipulating actin-binding subcellularly, harnessing the F-actin cytoskeleton for synthetic biology purposes remains elusive. Here, we describe a suite of designed proteins, Controllable Actin-binding Switch Tools (CASTs), whose actin-binding behavior can be controlled with external stimuli. CASTs were developed that respond to different external inputs, providing options for turn-on kinetics and enabling orthogonality. Being genetically encoded, we show that CASTs can be inserted into native protein sequences to control F-actin association locally and engineered into new structures to control cell and tissue shape and behavior.
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Affiliation(s)
- Unyime M. Effiong
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Hannah Khairandish
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Isabela Ramirez-Velez
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Yanran Wang
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
| | - Brian Belardi
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712
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6
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Borutzki Y, Skos L, Gerner C, Meier‐Menches SM. Exploring the Potential of Metal-Based Candidate Drugs as Modulators of the Cytoskeleton. Chembiochem 2023; 24:e202300178. [PMID: 37345897 PMCID: PMC10946712 DOI: 10.1002/cbic.202300178] [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: 03/03/2023] [Revised: 06/21/2023] [Accepted: 06/22/2023] [Indexed: 06/23/2023]
Abstract
During recent years, accumulating evidence suggested that metal-based candidate drugs are promising modulators of cytoskeletal and cytoskeleton-associated proteins. This was substantiated by the identification and validation of actin, vimentin and plectin as targets of distinct ruthenium(II)- and platinum(II)-based modulators. Despite this, structural information about molecular interaction is scarcely available. Here, we compile the scattered reports about metal-based candidate molecules that influence the cytoskeleton, its associated proteins and explore their potential to interfere in cancer-related processes, including proliferation, invasion and the epithelial-to-mesenchymal transition. Advances in this field depend crucially on determining binding sites and on gaining comprehensive insight into molecular drug-target interactions. These are key steps towards establishing yet elusive structure-activity relationships.
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Affiliation(s)
- Yasmin Borutzki
- Institute of Inorganic ChemistryFaculty of ChemistryUniversity of Vienna1090ViennaAustria
- Department of Analytical ChemistryFaculty of ChemistryUniversity of Vienna1090ViennaAustria
- Doctoral School of ChemistryUniversity of Vienna1090ViennaAustria
| | - Lukas Skos
- Department of Analytical ChemistryFaculty of ChemistryUniversity of Vienna1090ViennaAustria
- Doctoral School of ChemistryUniversity of Vienna1090ViennaAustria
| | - Christopher Gerner
- Department of Analytical ChemistryFaculty of ChemistryUniversity of Vienna1090ViennaAustria
- Joint Metabolome FacilityUniversity of Vienna and Medical University Vienna1090ViennaAustria
| | - Samuel M. Meier‐Menches
- Institute of Inorganic ChemistryFaculty of ChemistryUniversity of Vienna1090ViennaAustria
- Department of Analytical ChemistryFaculty of ChemistryUniversity of Vienna1090ViennaAustria
- Joint Metabolome FacilityUniversity of Vienna and Medical University Vienna1090ViennaAustria
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7
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Atang AE, Keller AR, Denha SA, Avery AW. Increased Actin Binding Is a Shared Molecular Consequence of Numerous SCA5 Mutations in β-III-Spectrin. Cells 2023; 12:2100. [PMID: 37626910 PMCID: PMC10453832 DOI: 10.3390/cells12162100] [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: 06/13/2023] [Revised: 07/28/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
Spinocerebellar ataxia type 5 (SCA5) is a neurodegenerative disease caused by mutations in the SPTBN2 gene encoding the cytoskeletal protein β-III-spectrin. Previously, we demonstrated that a L253P missense mutation, localizing to the β-III-spectrin actin-binding domain (ABD), causes increased actin-binding affinity. Here we investigate the molecular consequences of nine additional ABD-localized, SCA5 missense mutations: V58M, K61E, T62I, K65E, F160C, D255G, T271I, Y272H, and H278R. We show that all of the mutations, similar to L253P, are positioned at or near the interface of the two calponin homology subdomains (CH1 and CH2) comprising the ABD. Using biochemical and biophysical approaches, we demonstrate that the mutant ABD proteins can attain a well-folded state. However, thermal denaturation studies show that all nine mutations are destabilizing, suggesting a structural disruption at the CH1-CH2 interface. Importantly, all nine mutations cause increased actin binding. The mutant actin-binding affinities vary greatly, and none of the nine mutations increase actin-binding affinity as much as L253P. ABD mutations causing high-affinity actin binding, with the notable exception of L253P, appear to be associated with an early age of symptom onset. Altogether, the data indicate that increased actin-binding affinity is a shared molecular consequence of numerous SCA5 mutations, which has important therapeutic implications.
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Affiliation(s)
| | | | | | - Adam W. Avery
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA
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8
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Ignácz A, Nagy-Herczeg D, Hausser A, Schlett K. Dendritic effects of genetically encoded actin-labeling probes in cultured hippocampal neurons. Mol Biol Cell 2023; 34:br8. [PMID: 36989034 PMCID: PMC10295473 DOI: 10.1091/mbc.e22-08-0331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 03/14/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023] Open
Abstract
Actin cytoskeleton predominantly regulates the formation and maintenance of synapses by controlling dendritic spine morphology and motility. To visualize actin dynamics, actin molecules can be labeled by genetically fusing fluorescent proteins to actin monomers, actin-binding proteins, or single-chain anti-actin antibodies. In the present study, we compared the dendritic effect of EGFP-actin, LifeAct-TagGFP2 (LifeAct-GFP), and Actin-Chromobody-TagGFP2 (AC-GFP) in mouse cultured hippocampal neurons using unbiased quantitative methods. The actin-binding probes LifeAct-GFP and AC-GFP showed similar affinity to F-actin, but in contrast to EGFP-actin, they did not reveal subtle changes in actin remodeling between mushroom-shaped spines and filopodia. All tested actin probes colocalized with phalloidin similarly; however, the enrichment of LifeAct-GFP in dendritic spines was remarkably lower compared with the other constructs. LifeAct-GFP expression was tolerated at a higher expression level compared with EGFP-actin and AC-GFP with only subtle differences identified in dendritic spine morphology and protrusion density. While EGFP-actin and LifeAct-GFP expression did not alter dendritic arborization, AC-GFP-expressing neurons displayed a reduced dendritic tree. Thus, although all tested actin probes may be suitable for actin imaging studies, certain limitations should be considered before performing experiments with a particular actin-labeling probe in primary neurons.
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Affiliation(s)
- Attila Ignácz
- Department of Physiology and Neurobiology, Eötvös Loránd University, Budapest, Hungary
| | - Domonkos Nagy-Herczeg
- Department of Physiology and Neurobiology, Eötvös Loránd University, Budapest, Hungary
| | - Angelika Hausser
- Institute of Cell Biology and Immunology, University of Stuttgart, Stuttgart, Germany
- Stuttgart Research Center Systems Biology, University of Stuttgart, Stuttgart, Germany
| | - Katalin Schlett
- Department of Physiology and Neurobiology, Eötvös Loránd University, Budapest, Hungary
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9
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Atang AE, Rebbeck RT, Thomas DD, Avery AW. Cardiomyopathy-associated variants alter the structure and function of the α-actinin-2 actin-binding domain. Biochem Biophys Res Commun 2023; 670:12-18. [PMID: 37271035 DOI: 10.1016/j.bbrc.2023.05.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 05/15/2023] [Indexed: 06/06/2023]
Abstract
Hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), and restrictive cardiomyopathy (RCM) are characterized by thickening, thinning, or stiffening, respectively, of the ventricular myocardium, resulting in diastolic or systolic dysfunction that can lead to heart failure and sudden cardiac death. Recently, variants in the ACTN2 gene, encoding the protein α-actinin-2, have been reported in HCM, DCM, and RCM patients. However, functional data supporting the pathogenicity of these variants is limited, and potential mechanisms by which these variants cause disease are largely unexplored. Currently, NIH ClinVar lists 34 ACTN2 missense variants, identified in cardiomyopathy patients, which we predict are likely to disrupt actin binding, based on their localization to specific substructures in the α-actinin-2 actin binding domain (ABD). We investigated the molecular consequences of three ABD localized, HCM-associated variants: A119T, M228T and T247 M. Using circular dichroism, we demonstrate that the mutant ABD proteins can attain a well-folded state. However, thermal denaturation studies show that all three mutations are destabilizing, suggesting a structural disruption. Importantly, A119T decreased actin binding, and M228T and T247M cause increased actin binding. We suggest that altered actin binding underlies pathogenesis for cardiomyopathy mutations localizing to the ABD of α-actinin-2.
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Affiliation(s)
- Alexandra E Atang
- Department of Chemistry, Oakland University, Rochester, MI, 48309-4479, USA
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, 55455, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, 55455, USA
| | - Adam W Avery
- Department of Chemistry, Oakland University, Rochester, MI, 48309-4479, USA.
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10
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Dans MG, Piirainen H, Nguyen W, Khurana S, Mehra S, Razook Z, Geoghegan ND, Dawson AT, Das S, Parkyn Schneider M, Jonsdottir TK, Gabriela M, Gancheva MR, Tonkin CJ, Mollard V, Goodman CD, McFadden GI, Wilson DW, Rogers KL, Barry AE, Crabb BS, de Koning-Ward TF, Sleebs BE, Kursula I, Gilson PR. Sulfonylpiperazine compounds prevent Plasmodium falciparum invasion of red blood cells through interference with actin-1/profilin dynamics. PLoS Biol 2023; 21:e3002066. [PMID: 37053271 PMCID: PMC10128974 DOI: 10.1371/journal.pbio.3002066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 04/25/2023] [Accepted: 03/06/2023] [Indexed: 04/15/2023] Open
Abstract
With emerging resistance to frontline treatments, it is vital that new antimalarial drugs are identified to target Plasmodium falciparum. We have recently described a compound, MMV020291, as a specific inhibitor of red blood cell (RBC) invasion, and have generated analogues with improved potency. Here, we generated resistance to MMV020291 and performed whole genome sequencing of 3 MMV020291-resistant populations. This revealed 3 nonsynonymous single nucleotide polymorphisms in 2 genes; 2 in profilin (N154Y, K124N) and a third one in actin-1 (M356L). Using CRISPR-Cas9, we engineered these mutations into wild-type parasites, which rendered them resistant to MMV020291. We demonstrate that MMV020291 reduces actin polymerisation that is required by the merozoite stage parasites to invade RBCs. Additionally, the series inhibits the actin-1-dependent process of apicoplast segregation, leading to a delayed death phenotype. In vitro cosedimentation experiments using recombinant P. falciparum proteins indicate that potent MMV020291 analogues disrupt the formation of filamentous actin in the presence of profilin. Altogether, this study identifies the first compound series interfering with the actin-1/profilin interaction in P. falciparum and paves the way for future antimalarial development against the highly dynamic process of actin polymerisation.
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Affiliation(s)
- Madeline G Dans
- Burnet Institute, Melbourne, Victoria, Australia
- School of Medicine and Institute for Mental and Physical Health and Clinical Translation, Deakin University, Waurn Ponds, Victoria, Australia
- Walter and Eliza Hall Institute, Parkville, Victoria, Australia
| | - Henni Piirainen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
| | - William Nguyen
- Walter and Eliza Hall Institute, Parkville, Victoria, Australia
| | - Sachin Khurana
- Walter and Eliza Hall Institute, Parkville, Victoria, Australia
| | - Somya Mehra
- Burnet Institute, Melbourne, Victoria, Australia
| | - Zahra Razook
- Burnet Institute, Melbourne, Victoria, Australia
- School of Medicine and Institute for Mental and Physical Health and Clinical Translation, Deakin University, Waurn Ponds, Victoria, Australia
| | | | | | - Sujaan Das
- Ludwig Maximilian University, Faculty of Veterinary Medicine, Munich, Germany
| | | | - Thorey K Jonsdottir
- Burnet Institute, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
| | - Mikha Gabriela
- Burnet Institute, Melbourne, Victoria, Australia
- School of Medicine and Institute for Mental and Physical Health and Clinical Translation, Deakin University, Waurn Ponds, Victoria, Australia
| | - Maria R Gancheva
- Research Centre for Infectious Diseases, The University of Adelaide, Adelaide, Australia
| | | | - Vanessa Mollard
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | | | - Geoffrey I McFadden
- School of Biosciences, The University of Melbourne, Parkville, Victoria, Australia
| | - Danny W Wilson
- Research Centre for Infectious Diseases, The University of Adelaide, Adelaide, Australia
| | - Kelly L Rogers
- Walter and Eliza Hall Institute, Parkville, Victoria, Australia
| | - Alyssa E Barry
- Burnet Institute, Melbourne, Victoria, Australia
- School of Medicine and Institute for Mental and Physical Health and Clinical Translation, Deakin University, Waurn Ponds, Victoria, Australia
| | - Brendan S Crabb
- Burnet Institute, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
| | - Tania F de Koning-Ward
- School of Medicine and Institute for Mental and Physical Health and Clinical Translation, Deakin University, Waurn Ponds, Victoria, Australia
| | - Brad E Sleebs
- Walter and Eliza Hall Institute, Parkville, Victoria, Australia
| | - Inari Kursula
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Oulu, Finland
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Paul R Gilson
- Burnet Institute, Melbourne, Victoria, Australia
- Department of Microbiology and Immunology, The University of Melbourne, Parkville, Victoria, Australia
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11
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Atang AE, Keller AR, Denha SA, Avery AW. Increased actin binding is a shared molecular consequence of numerous spinocerebellar ataxia mutations in β-III-spectrin. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.20.529285. [PMID: 36865188 PMCID: PMC9980045 DOI: 10.1101/2023.02.20.529285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Spinocerebellar ataxia type 5 (SCA5) is a neurodegenerative disease caused by mutations in the SPTBN2 gene encoding the cytoskeletal protein β-III-spectrin. Previously, we demonstrated that a L253P missense mutation, localizing to the β-III-spectrin actin-binding domain (ABD), causes increased actin-binding affinity. Here we investigate the molecular consequences of nine additional ABD-localized, SCA5 missense mutations: V58M, K61E, T62I, K65E, F160C, D255G, T271I, Y272H, and H278R. We show that all of the mutations, similar to L253P, are positioned at or near the interface of the two calponin homology subdomains (CH1 and CH2) comprising the ABD. Using biochemical and biophysical approaches, we demonstrate that the mutant ABD proteins can attain a well-folded state. However, thermal denaturation studies show that all nine mutations are destabilizing, suggesting a structural disruption at the CH1-CH2 interface. Importantly, all nine mutations cause increased actin binding. The mutant actin-binding affinities vary greatly, and none of the nine mutations increase actin-binding affinity as much as L253P. ABD mutations causing high-affinity actin binding, with the notable exception of L253P, appear to be associated with early age of symptom onset. Altogether, the data indicate increased actin-binding affinity is a shared molecular consequence of numerous SCA5 mutations, which has important therapeutic implications.
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Affiliation(s)
| | - Amanda R. Keller
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA
| | - Sarah A. Denha
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA
| | - Adam W. Avery
- Department of Chemistry, Oakland University, Rochester, MI 48309, USA
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12
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Li N, Chen S, Xu K, He MT, Dong MQ, Zhang QC, Gao N. Structural basis of membrane skeleton organization in red blood cells. Cell 2023; 186:1912-1929.e18. [PMID: 37044097 DOI: 10.1016/j.cell.2023.03.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 02/12/2023] [Accepted: 03/15/2023] [Indexed: 04/14/2023]
Abstract
The spectrin-based membrane skeleton is a ubiquitous membrane-associated two-dimensional cytoskeleton underneath the lipid membrane of metazoan cells. Mutations of skeleton proteins impair the mechanical strength and functions of the membrane, leading to several different types of human diseases. Here, we report the cryo-EM structures of the native spectrin-actin junctional complex (from porcine erythrocytes), which is a specialized short F-actin acting as the central organizational unit of the membrane skeleton. While an α-/β-adducin hetero-tetramer binds to the barbed end of F-actin as a flexible cap, tropomodulin and SH3BGRL2 together create an absolute cap at the pointed end. The junctional complex is strengthened by ring-like structures of dematin in the middle actin layers and by patterned periodic interactions with tropomyosin over its entire length. This work serves as a structural framework for understanding the assembly and dynamics of membrane skeleton and offers insights into mechanisms of various ubiquitous F-actin-binding factors in other F-actin systems.
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Affiliation(s)
- Ningning Li
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China; Changping Laboratory, Beijing 102206, China.
| | - Siyi Chen
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China; Changping Laboratory, Beijing 102206, China; Changping Laboratory Graduate Program, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Kui Xu
- MOE Key Laboratory of Bioinformatics, Center for Synthetic and Systems Biology, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Meng-Ting He
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China
| | - Meng-Qiu Dong
- National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China
| | - Qiangfeng Cliff Zhang
- MOE Key Laboratory of Bioinformatics, Center for Synthetic and Systems Biology, Beijing Advanced Innovation Center for Structural Biology & Frontier Research Center for Biological Structure, Tsinghua-Peking Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ning Gao
- State Key Laboratory of Membrane Biology, Peking-Tsinghua Joint Center for Life Sciences, School of Life Sciences, Peking University, Beijing 100871, China; Changping Laboratory, Beijing 102206, China; National Biomedical Imaging Center, Peking University, Beijing 100871, China.
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13
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Wu K, Bai H, Chang YT, Redler R, McNally KE, Sheffler W, Brunette TJ, Hicks DR, Morgan TE, Stevens TJ, Broerman A, Goreshnik I, DeWitt M, Chow CM, Shen Y, Stewart L, Derivery E, Silva DA, Bhabha G, Ekiert DC, Baker D. De novo design of modular peptide-binding proteins by superhelical matching. Nature 2023; 616:581-589. [PMID: 37020023 PMCID: PMC10115654 DOI: 10.1038/s41586-023-05909-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 03/01/2023] [Indexed: 04/07/2023]
Abstract
General approaches for designing sequence-specific peptide-binding proteins would have wide utility in proteomics and synthetic biology. However, designing peptide-binding proteins is challenging, as most peptides do not have defined structures in isolation, and hydrogen bonds must be made to the buried polar groups in the peptide backbone1-3. Here, inspired by natural and re-engineered protein-peptide systems4-11, we set out to design proteins made out of repeating units that bind peptides with repeating sequences, with a one-to-one correspondence between the repeat units of the protein and those of the peptide. We use geometric hashing to identify protein backbones and peptide-docking arrangements that are compatible with bidentate hydrogen bonds between the side chains of the protein and the peptide backbone12. The remainder of the protein sequence is then optimized for folding and peptide binding. We design repeat proteins to bind to six different tripeptide-repeat sequences in polyproline II conformations. The proteins are hyperstable and bind to four to six tandem repeats of their tripeptide targets with nanomolar to picomolar affinities in vitro and in living cells. Crystal structures reveal repeating interactions between protein and peptide interactions as designed, including ladders of hydrogen bonds from protein side chains to peptide backbones. By redesigning the binding interfaces of individual repeat units, specificity can be achieved for non-repeating peptide sequences and for disordered regions of native proteins.
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Affiliation(s)
- Kejia Wu
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
- Biological Physics, Structure and Design Graduate Program, University of Washington, Seattle, WA, USA
| | - Hua Bai
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA
| | - Ya-Ting Chang
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Rachel Redler
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | | | - William Sheffler
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - T J Brunette
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Derrick R Hicks
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | | | | | - Adam Broerman
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
- Department of Chemical Engineering, University of Washington, Seattle, WA, USA
| | - Inna Goreshnik
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Michelle DeWitt
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Cameron M Chow
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | - Yihang Shen
- Department of Computational Biology, Carnegie Mellon University, Pittsburgh, PA, USA
| | - Lance Stewart
- Department of Biochemistry, University of Washington, Seattle, WA, USA
- Institute for Protein Design, University of Washington, Seattle, WA, USA
| | | | - Daniel Adriano Silva
- Department of Biochemistry, University of Washington, Seattle, WA, USA.
- Institute for Protein Design, University of Washington, Seattle, WA, USA.
- Division of Life Science, The Hong Kong University of Science and Technology, Kowloon, Hong Kong.
- Monod Bio, Seattle, WA, USA.
| | - Gira Bhabha
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Damian C Ekiert
- Department of Cell Biology, New York University School of Medicine, New York, NY, USA
- Department of Microbiology, New York University School of Medicine, New York, NY, USA
| | - David Baker
- Department of Biochemistry, University of Washington, Seattle, WA, USA.
- Institute for Protein Design, University of Washington, Seattle, WA, USA.
- Howard Hughes Medical Institute, University of Washington, Seattle, WA, USA.
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14
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Deciphering the molecular mechanisms of actin cytoskeleton regulation in cell migration using cryo-EM. Biochem Soc Trans 2023; 51:87-99. [PMID: 36695514 PMCID: PMC9987995 DOI: 10.1042/bst20220221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/12/2023] [Accepted: 01/12/2023] [Indexed: 01/26/2023]
Abstract
The actin cytoskeleton plays a key role in cell migration and cellular morphodynamics in most eukaryotes. The ability of the actin cytoskeleton to assemble and disassemble in a spatiotemporally controlled manner allows it to form higher-order structures, which can generate forces required for a cell to explore and navigate through its environment. It is regulated not only via a complex synergistic and competitive interplay between actin-binding proteins (ABP), but also by filament biochemistry and filament geometry. The lack of structural insights into how geometry and ABPs regulate the actin cytoskeleton limits our understanding of the molecular mechanisms that define actin cytoskeleton remodeling and, in turn, impact emerging cell migration characteristics. With the advent of cryo-electron microscopy (cryo-EM) and advanced computational methods, it is now possible to define these molecular mechanisms involving actin and its interactors at both atomic and ultra-structural levels in vitro and in cellulo. In this review, we will provide an overview of the available cryo-EM methods, applicable to further our understanding of the actin cytoskeleton, specifically in the context of cell migration. We will discuss how these methods have been employed to elucidate ABP- and geometry-defined regulatory mechanisms in initiating, maintaining, and disassembling cellular actin networks in migratory protrusions.
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15
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Bhaskar H, Kleinjan D, Oi C, Gidden Z, Rosser SJ, Horrocks MH, Regan L. Live-cell super-resolution imaging of actin using LifeAct-14 with a PAINT-based approach. Protein Sci 2023; 32:e4558. [PMID: 36585831 PMCID: PMC9878614 DOI: 10.1002/pro.4558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/27/2022] [Accepted: 12/29/2022] [Indexed: 01/01/2023]
Abstract
We present direct-LIVE-PAINT, an easy-to-implement approach for the nanoscopic imaging of protein structures in live cells using labeled binding peptides. We demonstrate the feasibility of direct-LIVE-PAINT with an actin-binding peptide fused to EGFP, the location of which can be accurately determined as it transiently binds to actin filaments. We show that direct-LIVE-PAINT can be used to image actin structures below the diffraction-limit of light and have used it to observe the dynamic nature of actin in live cells. We envisage a similar approach could be applied to imaging other proteins within live mammalian cells.
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Affiliation(s)
- Haresh Bhaskar
- The School of Biological SciencesUniversity of EdinburghEdinburghUK,EaStCHEM School of ChemistryUniversity of EdinburghEdinburghUK
| | - Dirk‐Jan Kleinjan
- Centre for Synthetic and Systems Biology and UK Centre for Mammalian Synthetic Biology, School of Biological SciencesUniversity of EdinburghEdinburghUK
| | - Curran Oi
- Department of Genome SciencesUniversity of WashingtonSeattleWashingtonUSA
| | - Zoe Gidden
- The School of Biological SciencesUniversity of EdinburghEdinburghUK,EaStCHEM School of ChemistryUniversity of EdinburghEdinburghUK
| | - Susan J. Rosser
- Centre for Synthetic and Systems Biology and UK Centre for Mammalian Synthetic Biology, School of Biological SciencesUniversity of EdinburghEdinburghUK
| | | | - Lynne Regan
- The School of Biological SciencesUniversity of EdinburghEdinburghUK
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16
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Verrier N, Taddese AM, Abbessi R, Debailleul M, Haeberlé O. 3D differential interference contrast microscopy using polarisation-sensitive tomographic diffraction microscopy. J Microsc 2023; 289:128-133. [PMID: 36408663 PMCID: PMC10107843 DOI: 10.1111/jmi.13160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/18/2022] [Accepted: 11/14/2022] [Indexed: 11/22/2022]
Abstract
Tomographic diffraction microscopy (TDM) is a generalisation of digital holographic microscopy (DHM), for which the illumination angle onto the sample is fully controlled, which has become a tool of choice for 3D, high-resolution imaging of unlabelled samples. TDM makes it possible to obtain the optical field in both amplitude and phase for each illumination angle. Proper information reallocation eventually allows for 3D reconstruction of the complex refractive index map. On the other hand, polarisation array sensors (PAS) paves new way for TDM, as vectorial information assessment about the investigated sample. In this contribution, we show an alternative use of this polarisation information based on the phase sensitive nature of TDM. Here, we demonstrated that TDM coupled with PAS can lead to a 3D differential interference contrast (DIC) microscope with almost no experimental configuration modification.
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Affiliation(s)
- Nicolas Verrier
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, Mulhouse Cedex, France
| | - Asemare Mengistie Taddese
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, Mulhouse Cedex, France
| | - Riadh Abbessi
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, Mulhouse Cedex, France
| | - Matthieu Debailleul
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, Mulhouse Cedex, France
| | - Olivier Haeberlé
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, Mulhouse Cedex, France
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17
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Ali MF, Shin JM, Fatema U, Kurihara D, Berger F, Yuan L, Kawashima T. Cellular dynamics of coenocytic endosperm development in Arabidopsis thaliana. NATURE PLANTS 2023; 9:330-342. [PMID: 36646830 DOI: 10.1038/s41477-022-01331-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 12/12/2022] [Indexed: 06/17/2023]
Abstract
After double fertilization, the endosperm in the seeds of many flowering plants undergoes repeated mitotic nuclear divisions without cytokinesis, resulting in a large coenocytic endosperm that then cellularizes. Growth during the coenocytic phase is strongly associated with the final seed size; however, a detailed description of the cellular dynamics controlling the unique coenocytic development in flowering plants has remained elusive. By integrating confocal microscopy live-cell imaging and genetics, we have characterized the entire development of the coenocytic endosperm of Arabidopsis thaliana including nuclear divisions, their timing intervals, nuclear movement and cytoskeleton dynamics. Around each nucleus, microtubules organize into aster-shaped structures that drive actin filament (F-actin) organization. Microtubules promote nuclear movement after division, while F-actin restricts it. F-actin is also involved in controlling the size of both the coenocytic endosperm and the mature seed. The characterization of cytoskeleton dynamics in real time throughout the entire coenocyte endosperm period provides foundational knowledge of plant coenocytic development, insights into the coordination of F-actin and microtubules in nuclear dynamics, and new opportunities to increase seed size and our food security.
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Affiliation(s)
- Mohammad Foteh Ali
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | - Ji Min Shin
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
- Kentucky Tobacco Research and Development Center, University of Kentucky, Lexington, KY, USA
| | - Umma Fatema
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
| | - Daisuke Kurihara
- Institute of Transformative Bio-Molecules (ITbM), Nagoya University, Nagoya, Japan
- Institute for Advanced Research (IAR), Nagoya University, Nagoya, Japan
| | - Frédéric Berger
- Gregor Mendel Institute, Austrian Academy of Sciences, Vienna BioCenter, Vienna, Austria
| | - Ling Yuan
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
- Kentucky Tobacco Research and Development Center, University of Kentucky, Lexington, KY, USA
- Key Laboratory of South China Agricultural Plant Molecular Analysis and Genetic Improvement & Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
| | - Tomokazu Kawashima
- Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA.
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18
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Kroll KL, French AR, Sosnick TR, Rock RS. LILAC: enhanced actin imaging with an optogenetic Lifeact. Nat Methods 2023; 20:214-217. [PMID: 36717692 PMCID: PMC10986358 DOI: 10.1038/s41592-022-01761-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 12/20/2022] [Indexed: 01/31/2023]
Abstract
Lifeact is a popular peptide-based label of actin filaments in live cells. We have designed an improved Lifeact variant, LILAC, that binds to actin in light using the LOV2 protein. Light control allows the user to modulate actin labeling, enabling image analysis that leverages modulation for an enhanced view of F-actin dynamics in cells. Furthermore, the tool reduces actin perturbations and cell sickness caused by Lifeact overexpression.
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Affiliation(s)
- Kourtney L Kroll
- Biophysical Sciences Graduate Program, The University of Chicago, Chicago, IL, USA
| | - Alexander R French
- Neuroscience Program, University of Illinois Urbana-Champaign, Urbana, IL, USA
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, IL, USA
| | - Tobin R Sosnick
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL, USA.
| | - Ronald S Rock
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
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19
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Willig KI. In vivo super-resolution of the brain – How to visualize the hidden nanoplasticity? iScience 2022; 25:104961. [PMID: 36093060 PMCID: PMC9449647 DOI: 10.1016/j.isci.2022.104961] [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] [Indexed: 11/15/2022] Open
Abstract
Super-resolution fluorescence microscopy has entered most biological laboratories worldwide and its benefit is undisputable. Its application to brain imaging, for example in living mice, enables the study of sub-cellular structural plasticity and brain function directly in a living mammal. The demands of brain imaging on the different super-resolution microscopy techniques (STED, RESOLFT, SIM, ISM) and labeling strategies are discussed here as well as the challenges of the required cranial window preparation. Applications of super-resolution in the anesthetized mouse brain enlighten the stability and plasticity of synaptic nanostructures. These studies show the potential of in vivo super-resolution imaging and justify its application more widely in vivo to investigate the role of nanostructures in memory and learning.
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20
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CAPG Is Required for Ebola Virus Infection by Controlling Virus Egress from Infected Cells. Viruses 2022; 14:v14091903. [PMID: 36146710 PMCID: PMC9505868 DOI: 10.3390/v14091903] [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: 08/03/2022] [Revised: 08/24/2022] [Accepted: 08/26/2022] [Indexed: 11/16/2022] Open
Abstract
The replication of Ebola virus (EBOV) is dependent upon actin functionality, especially at cell entry through macropinocytosis and at release of virus from cells. Previously, major actin-regulatory factors involved in actin nucleation, such as Rac1 and Arp2/3, were shown important in both steps. However, downstream of nucleation, many other cell factors are needed to control actin dynamics. How these regulate EBOV infection remains largely unclear. Here, we identified the actin-regulating protein, CAPG, as important for EBOV replication. Notably, knockdown of CAPG specifically inhibited viral infectivity and yield of infectious particles. Cell-based mechanistic analysis revealed a requirement of CAPG for virus production from infected cells. Proximity ligation and split-green fluorescent protein reconstitution assays revealed strong association of CAPG with VP40 that was mediated through the S1 domain of CAPG. Overall, CAPG is a novel host factor regulating EBOV infection through connecting actin filament stabilization to viral egress from cells.
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21
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Xie S, Li J, Sun S, Chen W, Cheng H, Song Y, Li Y, Liu M, Zhu X, Liang X, Zhou J. TUBright: A Peptide Probe for Imaging Microtubules. Anal Chem 2022; 94:11168-11174. [PMID: 35917443 DOI: 10.1021/acs.analchem.2c01285] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In vitro assays using reconstituted microtubules have provided molecular insights into the principles of microtubule dynamics and the roles of microtubule-associated proteins. Emerging questions that further uncover the complexity in microtubule dynamics, especially those on tubulin isotypes and post-translational modifications, raise new technical challenges on how to visualize microtubules composed of tubulin purified from limited sources, primarily due to the low efficiency of the conventional tubulin labeling protocol. Here, we develop a peptide probe, termed TUBright, that labels in vitro reconstituted microtubules. TUBright, when coupled with different fluorescent dyes, provides flexible labeling of microtubules with a high signal-to-noise ratio. TUBright does not interfere with the dynamic behaviors of microtubules and microtubule-associated proteins. Therefore, TUBright is a useful tool for imaging microtubules, making it feasible to use tubulin from limited sources for answering many open questions on microtubule dynamics.
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Affiliation(s)
- Songbo Xie
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Jingrui Li
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Shuang Sun
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Wei Chen
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Haisu Cheng
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yinlong Song
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuyang Li
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Min Liu
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xin Liang
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jun Zhou
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China.,State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, College of Life Sciences, Nankai University, Tianjin 300071, China
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22
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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: 5] [Impact Index Per Article: 2.5] [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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23
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Biochemical Interactions through Microscopic Techniques: Structural and Molecular Characterization. Polymers (Basel) 2022; 14:polym14142853. [PMID: 35890632 PMCID: PMC9318543 DOI: 10.3390/polym14142853] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 07/06/2022] [Accepted: 07/06/2022] [Indexed: 11/17/2022] Open
Abstract
Many researchers and scientists have contributed significantly to provide structural and molecular characterizations of biochemical interactions using microscopic techniques in the recent decade, as these biochemical interactions play a crucial role in the production of diverse biomaterials and the organization of biological systems. The properties, activities, and functionalities of the biomaterials and biological systems need to be identified and modified for different purposes in both the material and life sciences. The present study aimed to review the advantages and disadvantages of three main branches of microscopy techniques (optical microscopy, electron microscopy, and scanning probe microscopy) developed for the characterization of these interactions. First, we explain the basic concepts of microscopy and then the breadth of their applicability to different fields of research. This work could be useful for future research works on biochemical self-assembly, biochemical aggregation and localization, biological functionalities, cell viability, live-cell imaging, material stability, and membrane permeability, among others. This understanding is of high importance in rapid, inexpensive, and accurate analysis of biochemical interactions.
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Abbessi R, Verrier N, Taddese AM, Laroche S, Debailleul M, Lo M, Courbot JB, Haeberlé O. Multimodal image reconstruction from tomographic diffraction microscopy data. J Microsc 2022; 288:193-206. [PMID: 35775607 DOI: 10.1111/jmi.13131] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 06/18/2022] [Accepted: 06/24/2022] [Indexed: 11/29/2022]
Abstract
Tomographic Diffraction Microscopy (TDM) is a tool of choice for high-resolution, marker-less 3D imaging of biological samples. Based on a generalization of Digital Holographic Microscopy (DHM) with full control of the sample's illumination, TDM measures, from many illumination directions, the diffracted fields in both phase and amplitude. Photon budget associated to TDM imaging is low. Therefore, TDM is not limited by photo-toxicity issues. The recorded information makes it possible to reconstruct 3D refractive index distribution (with both refraction and absorption contributions) of the object under scrutiny, without any staining. In this contribution, we show an alternate use of this information. A tutorial for multimodal image reconstruction is proposed. Both intensity contrasts and phase contrasts are proposed, from the image formation model to the final reconstruction with both 2D and 3D rendering, turning TDM into a kind of "universal" digital microscope. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Riadh Abbessi
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, Mulhouse Cedex, 68093, France
| | - Nicolas Verrier
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, Mulhouse Cedex, 68093, France
| | - Asemare Mengistie Taddese
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, Mulhouse Cedex, 68093, France
| | - Steve Laroche
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, Mulhouse Cedex, 68093, France
| | - Matthieu Debailleul
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, Mulhouse Cedex, 68093, France
| | - Mohamed Lo
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, Mulhouse Cedex, 68093, France
| | - Jean-Baptiste Courbot
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, Mulhouse Cedex, 68093, France
| | - Olivier Haeberlé
- Institut Recherche en Informatique, Mathématiques, Automatique et Signal (IRIMAS UR UHA 7499), Université de Haute-Alsace, IUT Mulhouse, 61 rue Albert Camus, Mulhouse Cedex, 68093, France
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Goleń J, Tyszka J, Godos K, Janse M. A Model of F-actin Organization in Granuloreticulopodia in Foraminifera: Morphogenetic and Evolutionary Implications from Novel Fluorescent and Polarised Light Observations. Protist 2022; 173:125886. [DOI: 10.1016/j.protis.2022.125886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 04/22/2022] [Accepted: 05/08/2022] [Indexed: 11/29/2022]
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Ma OX, Chong WG, Lee JKE, Cai S, Siebert CA, Howe A, Zhang P, Shi J, Surana U, Gan L. Cryo-ET detects bundled triple helices but not ladders in meiotic budding yeast. PLoS One 2022; 17:e0266035. [PMID: 35421110 PMCID: PMC9009673 DOI: 10.1371/journal.pone.0266035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Accepted: 03/13/2022] [Indexed: 11/19/2022] Open
Abstract
In meiosis, cells undergo two sequential rounds of cell division, termed meiosis I and meiosis II. Textbook models of the meiosis I substage called pachytene show that nuclei have conspicuous 100-nm-wide, ladder-like synaptonemal complexes and ordered chromatin loops. It remains unknown if these cells have any other large, meiosis-related intranuclear structures. Here we present cryo-ET analysis of frozen-hydrated budding yeast cells before, during, and after pachytene. We found no cryo-ET densities that resemble dense ladder-like structures or ordered chromatin loops. Instead, we found large numbers of 12-nm-wide triple-helices that pack into ordered bundles. These structures, herein called meiotic triple helices (MTHs), are present in meiotic cells, but not in interphase cells. MTHs are enriched in the nucleus but not enriched in the cytoplasm. Bundles of MTHs form at the same timeframe as synaptonemal complexes (SCs) in wild-type cells and in mutant cells that are unable to form SCs. These results suggest that in yeast, SCs coexist with previously unreported large, ordered assemblies.
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Affiliation(s)
- Olivia X. Ma
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Wen Guan Chong
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Joy K. E. Lee
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Shujun Cai
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - C. Alistair Siebert
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
| | - Andrew Howe
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
| | - Peijun Zhang
- Diamond Light Source Ltd, Harwell Science & Innovation Campus, Didcot, Oxfordshire, United Kingdom
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | - Jian Shi
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
| | - Uttam Surana
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Proteos, Singapore
- Bioprocessing Technology Institute, A*STAR, Singapore, Singapore
- Biotransformation Innovation Platform, A*STAR, Singapore, Singapore
- Department of Pharmacology, National University of Singapore, Singapore, Singapore
| | - Lu Gan
- Department of Biological Sciences and Centre for BioImaging Sciences, National University of Singapore, Singapore, Singapore
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Gao J, Nakamura F. Actin-Associated Proteins and Small Molecules Targeting the Actin Cytoskeleton. Int J Mol Sci 2022; 23:ijms23042118. [PMID: 35216237 PMCID: PMC8880164 DOI: 10.3390/ijms23042118] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/10/2022] [Accepted: 02/11/2022] [Indexed: 02/06/2023] Open
Abstract
Actin-associated proteins (AAPs) act on monomeric globular actin (G-actin) and polymerized filamentous actin (F-actin) to regulate their dynamics and architectures which ultimately control cell movement, shape change, division; organelle localization and trafficking. Actin-binding proteins (ABPs) are a subset of AAPs. Since actin was discovered as a myosin-activating protein (hence named actin) in 1942, the protein has also been found to be expressed in non-muscle cells, and numerous AAPs continue to be discovered. This review article lists all of the AAPs discovered so far while also allowing readers to sort the list based on the names, sizes, functions, related human diseases, and the dates of discovery. The list also contains links to the UniProt and Protein Atlas databases for accessing further, related details such as protein structures, associated proteins, subcellular localization, the expression levels in cells and tissues, mutations, and pathology. Because the actin cytoskeleton is involved in many pathological processes such as tumorigenesis, invasion, and developmental diseases, small molecules that target actin and AAPs which hold potential to treat these diseases are also listed.
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Denha SA, Atang AE, Hays TS, Avery AW. β-III-spectrin N-terminus is required for high-affinity actin binding and SCA5 neurotoxicity. Sci Rep 2022; 12:1726. [PMID: 35110634 PMCID: PMC8810934 DOI: 10.1038/s41598-022-05762-2] [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: 08/20/2021] [Accepted: 01/17/2022] [Indexed: 11/09/2022] Open
Abstract
Recent structural studies of β-III-spectrin and related cytoskeletal proteins revealed N-terminal sequences that directly bind actin. These sequences are variable in structure, and immediately precede a conserved actin-binding domain composed of tandem calponin homology domains (CH1 and CH2). Here we investigated in Drosophila the significance of the β-spectrin N-terminus, and explored its functional interaction with a CH2-localized L253P mutation that underlies the neurodegenerative disease spinocerebellar ataxia type 5 (SCA5). We report that pan-neuronal expression of an N-terminally truncated β-spectrin fails to rescue lethality resulting from a β-spectrin loss-of-function allele, indicating that the N-terminus is essential to β-spectrin function in vivo. Significantly, N-terminal truncation rescues neurotoxicity and defects in dendritic arborization caused by L253P. In vitro studies show that N-terminal truncation eliminates L253P-induced high-affinity actin binding, providing a mechanistic basis for rescue. These data suggest that N-terminal sequences may be useful therapeutic targets for small molecule modulation of the aberrant actin binding associated with SCA5 β-spectrin and spectrin-related disease proteins.
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Affiliation(s)
- Sarah A Denha
- Department of Chemistry, Oakland University, Rochester, MI, USA
| | | | - Thomas S Hays
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA
| | - Adam W Avery
- Department of Chemistry, Oakland University, Rochester, MI, USA. .,Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, USA.
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Sing CN, Yang EJ, Swayne TC, Higuchi-Sanabria R, Tsang CA, Boldogh IR, Pon LA. Imaging the Actin Cytoskeleton in Live Budding Yeast Cells. Methods Mol Biol 2022; 2364:53-80. [PMID: 34542848 PMCID: PMC11060504 DOI: 10.1007/978-1-0716-1661-1_3] [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] [Indexed: 04/22/2023]
Abstract
Although budding yeast, Saccharomyces cerevisiae, is widely used as a model organism in biological research, studying cell biology in yeast was hindered due to its small size, rounded morphology, and cell wall. However, with improved techniques, researchers can acquire high-resolution images and carry out rapid multidimensional analysis of a yeast cell. As a result, imaging in yeast has emerged as an important tool to study cytoskeletal organization, function, and dynamics. This chapter describes techniques and approaches for visualizing the actin cytoskeleton in live yeast cells.
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Affiliation(s)
- Cierra N Sing
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | - Emily J Yang
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | - Theresa C Swayne
- Confocal and Specialized Microscopy Shared Resource, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Ryo Higuchi-Sanabria
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, USA
| | - Catherine A Tsang
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
| | - Istvan R Boldogh
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA
- Confocal and Specialized Microscopy Shared Resource, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA
| | - Liza A Pon
- Department of Pathology and Cell Biology, Columbia University, College of Physicians and Surgeons, New York, NY, USA.
- Confocal and Specialized Microscopy Shared Resource, Herbert Irving Comprehensive Cancer Center, Columbia University, New York, NY, USA.
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The Central Role of the F-Actin Surface in Myosin Force Generation. BIOLOGY 2021; 10:biology10121221. [PMID: 34943138 PMCID: PMC8698748 DOI: 10.3390/biology10121221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/17/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022]
Abstract
Simple Summary Although actin is a highly conserved protein, it is involved in many diverse cellular processes. Actin owes its diversity of function to its ability to bind to a host of actin-binding proteins (ABPs) that localize across its surface. Among the most studied ABPs is the molecular motor, myosin. Myosin generates force on actin filaments by pairing ATP hydrolysis, product release, and actin-binding to the conformational changes that lead to movement. Central to this process is the progression of myosin binding to the actin surface as it moves through its ATPase cycle. During binding, actin acts as a myosin ATPase activator, catalyzing essential hydrolysis release steps. Here, we use the current model of actin-myosin binding as a roadmap to describe the portions of the actin-myosin interface that are sequentially formed throughout the motor cycle. At each step, we compare the interactions of a diverse set of high-resolution actin-myosin cryo-electron microscopy structures to define what portions of the interface are conserved and which are isoform-specific. Abstract Actin is one of the most abundant and versatile proteins in eukaryotic cells. As discussed in many contributions to this Special Issue, its transition from a monomeric G-actin to a filamentous F-actin form plays a critical role in a variety of cellular processes, including control of cell shape and cell motility. Once polymerized from G-actin, F-actin forms the central core of muscle-thin filaments and acts as molecular tracks for myosin-based motor activity. The ATP-dependent cross-bridge cycle of myosin attachment and detachment drives the sliding of myosin thick filaments past thin filaments in muscle and the translocation of cargo in somatic cells. The variation in actin function is dependent on the variation in muscle and non-muscle myosin isoform behavior as well as interactions with a plethora of additional actin-binding proteins. Extensive work has been devoted to defining the kinetics of actin-based force generation powered by the ATPase activity of myosin. In addition, over the past decade, cryo-electron microscopy has revealed the atomic-evel details of the binding of myosin isoforms on the F-actin surface. Most accounts of the structural interactions between myosin and actin are described from the perspective of the myosin molecule. Here, we discuss myosin-binding to actin as viewed from the actin surface. We then describe conserved structural features of actin required for the binding of all or most myosin isoforms while also noting specific interactions unique to myosin isoforms.
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Xu R, Du S. Overexpression of Lifeact-GFP Disrupts F-Actin Organization in Cardiomyocytes and Impairs Cardiac Function. Front Cell Dev Biol 2021; 9:746818. [PMID: 34765602 PMCID: PMC8576398 DOI: 10.3389/fcell.2021.746818] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 10/07/2021] [Indexed: 11/28/2022] Open
Abstract
Lifeact-GFP is a frequently used molecular probe to study F-actin structure and dynamic assembly in living cells. In this study, we generated transgenic zebrafish models expressing Lifeact-GFP specifically in cardiac muscles to investigate the effect of Lifeact-GFP on heart development and its application to study cardiomyopathy. The data showed that transgenic zebrafish with low to moderate levels of Lifeact-GFP expression could be used as a good model to study contractile dynamics of actin filaments in cardiac muscles in vivo. Using this model, we demonstrated that loss of Smyd1b, a lysine methyltransferase, disrupted F-actin filament organization in cardiomyocytes of zebrafish embryos. Our studies, however, also demonstrated that strong Lifeact-GFP expression in cardiomyocytes was detrimental to actin filament organization in cardiomyocytes that led to pericardial edema and early embryonic lethality of zebrafish embryos. Collectively, these data suggest that although Lifeact-GFP is a good probe for visualizing F-actin dynamics, transgenic models need to be carefully evaluated to avoid artifacts induced by Lifeact-GFP overexpression.
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Affiliation(s)
- Rui Xu
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Shaojun Du
- Department of Biochemistry and Molecular Biology, Institute of Marine and Environmental Technology, University of Maryland School of Medicine, Baltimore, MD, United States
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Vlassakis J, Hansen LL, Higuchi-Sanabria R, Zhou Y, Tsui CK, Dillin A, Huang H, Herr AE. Measuring expression heterogeneity of single-cell cytoskeletal protein complexes. Nat Commun 2021; 12:4969. [PMID: 34404787 PMCID: PMC8371148 DOI: 10.1038/s41467-021-25212-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 07/23/2021] [Indexed: 02/07/2023] Open
Abstract
Multimeric cytoskeletal protein complexes orchestrate normal cellular function. However, protein-complex distributions in stressed, heterogeneous cell populations remain unknown. Cell staining and proximity-based methods have limited selectivity and/or sensitivity for endogenous multimeric protein-complex quantification from single cells. We introduce micro-arrayed, differential detergent fractionation to simultaneously detect protein complexes in hundreds of individual cells. Fractionation occurs by 60 s size-exclusion electrophoresis with protein complex-stabilizing buffer that minimizes depolymerization. Proteins are measured with a ~5-hour immunoassay. Co-detection of cytoskeletal protein complexes in U2OS cells treated with filamentous actin (F-actin) destabilizing Latrunculin A detects a unique subpopulation (~2%) exhibiting downregulated F-actin, but upregulated microtubules. Thus, some cells may upregulate other cytoskeletal complexes to counteract the stress of Latrunculin A treatment. We also sought to understand the effect of non-chemical stress on cellular heterogeneity of F-actin. We find heat shock may dysregulate filamentous and globular actin correlation. In this work, our assay overcomes selectivity limitations to biochemically quantify single-cell protein complexes perturbed with diverse stimuli.
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Affiliation(s)
- Julea Vlassakis
- Department of Bioengineering, University of California Berkeley, Berkeley, CA, USA
| | - Louise L Hansen
- Department of Bioengineering, University of California Berkeley, Berkeley, CA, USA
| | - Ryo Higuchi-Sanabria
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Yun Zhou
- Division of Biostatistics, University of California Berkeley, Berkeley, CA, USA
| | - C Kimberly Tsui
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
| | - Andrew Dillin
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California Berkeley, Berkeley, CA, USA
| | - Haiyan Huang
- Department of Statistics, University of California Berkeley, Berkeley, CA, USA
- Center for Computational Biology, University of California Berkeley, Berkeley, CA, USA
| | - Amy E Herr
- Department of Bioengineering, University of California Berkeley, Berkeley, CA, USA.
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High stretch induces endothelial dysfunction accompanied by oxidative stress and actin remodeling in human saphenous vein endothelial cells. Sci Rep 2021; 11:13493. [PMID: 34188159 PMCID: PMC8242094 DOI: 10.1038/s41598-021-93081-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 05/17/2021] [Indexed: 12/12/2022] Open
Abstract
The rate of the remodeling of the arterialized saphenous vein conduit limits the outcomes of coronary artery bypass graft surgery (CABG), which may be influenced by endothelial dysfunction. We tested the hypothesis that high stretch (HS) induces human saphenous vein endothelial cell (hSVEC) dysfunction and examined candidate underlying mechanisms. Our results showed that in vitro HS reduces NO bioavailability, increases inflammatory adhesion molecule expression (E-selectin and VCAM1) and THP-1 cell adhesion. HS decreases F-actin in hSVECs, but not in human arterial endothelial cells, and is accompanied by G-actin and cofilin’s nuclear shuttling and increased reactive oxidative species (ROS). Pre-treatment with the broad-acting antioxidant N-acetylcysteine (NAC) supported this observation and diminished stretch-induced actin remodeling and inflammatory adhesive molecule expression. Altogether, we provide evidence that increased oxidative stress and actin cytoskeleton remodeling play a role in HS-induced saphenous vein endothelial cell dysfunction, which may contribute to predisposing saphenous vein graft to failure.
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Pospich S, Küllmer F, Nasufović V, Funk J, Belyy A, Bieling P, Arndt H, Raunser S. Cryo‐EM Resolves Molecular Recognition Of An Optojasp Photoswitch Bound To Actin Filaments In Both Switch States. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202013193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Sabrina Pospich
- Department of Structural Biochemistry Max Planck Institute of Molecular Physiology Otto-Hahn-Str. 11 44227 Dortmund Germany
| | - Florian Küllmer
- Institute of Organic Chemistry and Macromolecular Chemistry Friedrich-Schiller-University Humboldtstr. 10 07743 Jena Germany
| | - Veselin Nasufović
- Institute of Organic Chemistry and Macromolecular Chemistry Friedrich-Schiller-University Humboldtstr. 10 07743 Jena Germany
| | - Johanna Funk
- Department of Systemic Cell Biology Max Planck Institute of Molecular Physiology Otto-Hahn-Str. 11 44227 Dortmund Germany
| | - Alexander Belyy
- Department of Structural Biochemistry Max Planck Institute of Molecular Physiology Otto-Hahn-Str. 11 44227 Dortmund Germany
| | - Peter Bieling
- Department of Systemic Cell Biology Max Planck Institute of Molecular Physiology Otto-Hahn-Str. 11 44227 Dortmund Germany
| | - Hans‐Dieter Arndt
- Institute of Organic Chemistry and Macromolecular Chemistry Friedrich-Schiller-University Humboldtstr. 10 07743 Jena Germany
| | - Stefan Raunser
- Department of Structural Biochemistry Max Planck Institute of Molecular Physiology Otto-Hahn-Str. 11 44227 Dortmund Germany
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Pospich S, Küllmer F, Nasufović V, Funk J, Belyy A, Bieling P, Arndt HD, Raunser S. Cryo-EM Resolves Molecular Recognition Of An Optojasp Photoswitch Bound To Actin Filaments In Both Switch States. Angew Chem Int Ed Engl 2021; 60:8678-8682. [PMID: 33449370 PMCID: PMC8048601 DOI: 10.1002/anie.202013193] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 12/15/2020] [Indexed: 12/16/2022]
Abstract
Actin is essential for key processes in all eukaryotic cells. Cellpermeable optojasps provide spatiotemporal control of the actin cytoskeleton, confining toxicity and potentially rendering F-actin druggable by photopharmacology. Here, we report cryo electron microscopy (cryo-EM) structures of both isomeric states of one optojasp bound to actin filaments. The high-resolution structures reveal for the first time the pronounced effects of photoswitching a functionalized azobenzene. By characterizing the optojasp binding site and identifying conformational changes within F-actin that depend on the optojasp isomeric state, we refine determinants for the design of functional F-actin photoswitches.
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Affiliation(s)
- Sabrina Pospich
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Florian Küllmer
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich-Schiller-University, Humboldtstr. 10, 07743, Jena, Germany
| | - Veselin Nasufović
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich-Schiller-University, Humboldtstr. 10, 07743, Jena, Germany
| | - Johanna Funk
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Alexander Belyy
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Peter Bieling
- Department of Systemic Cell Biology, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
| | - Hans-Dieter Arndt
- Institute of Organic Chemistry and Macromolecular Chemistry, Friedrich-Schiller-University, Humboldtstr. 10, 07743, Jena, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Otto-Hahn-Str. 11, 44227, Dortmund, Germany
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Wang X, Jiang W, Luo S, Yang X, Wang C, Wang B, Dang Y, Shen Y, Ma DK. The C. elegans homolog of human panic-disorder risk gene TMEM132D orchestrates neuronal morphogenesis through the WAVE-regulatory complex. Mol Brain 2021; 14:54. [PMID: 33726789 PMCID: PMC7962252 DOI: 10.1186/s13041-021-00767-w] [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: 12/26/2020] [Accepted: 03/03/2021] [Indexed: 01/11/2023] Open
Abstract
TMEM132D is a human gene identified with multiple risk alleles for panic disorders, anxiety and major depressive disorders. Defining a conserved family of transmembrane proteins, TMEM132D and its homologs are still of unknown molecular functions. By generating loss-of-function mutants of the sole TMEM132 ortholog in C. elegans, we identify abnormal morphologic phenotypes in the dopaminergic PDE neurons. Using a yeast two-hybrid screen, we find that NAP1 directly interacts with the cytoplasmic domain of human TMEM132D, and mutations in C. elegans tmem-132 that disrupt interaction with NAP1 cause similar morphologic defects in the PDE neurons. NAP1 is a component of the WAVE regulatory complex (WRC) that controls F-actin cytoskeletal dynamics. Decreasing activity of WRC rescues the PDE defects in tmem-132 mutants, whereas gain-of-function of TMEM132D in mammalian cells inhibits WRC, leading to decreased abundance of select WRC components, impaired actin nucleation and cell motility. We propose that metazoan TMEM132 family proteins play evolutionarily conserved roles in regulating NAP1 protein homologs to restrict inappropriate WRC activity, cytoskeletal and morphologic changes in the cell.
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Affiliation(s)
- Xin Wang
- Cardiovascular Research Institute and Department of Physiology, University of California San Francisco, San Francisco, CA, 94158, USA.,State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, 650091, Yunnan, China
| | - Wei Jiang
- Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Fudan University, Shanghai, 200032, China
| | - Shuo Luo
- Cardiovascular Research Institute and Department of Physiology, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Xiaoyu Yang
- Institute for Human Genetics, Department of Neurology, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Changnan Wang
- Cardiovascular Research Institute and Department of Physiology, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Bingying Wang
- Cardiovascular Research Institute and Department of Physiology, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Yongjun Dang
- Key Laboratory of Metabolism and Molecular Medicine, the Ministry of Education, Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Shanghai Medical College of Fudan University, Fudan University, Shanghai, 200032, China
| | - Yin Shen
- Institute for Human Genetics, Department of Neurology, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Dengke K Ma
- Cardiovascular Research Institute and Department of Physiology, University of California San Francisco, San Francisco, CA, 94158, USA.
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Rebbeck RT, Andrick AK, Denha SA, Svensson B, Guhathakurta P, Thomas DD, Hays TS, Avery AW. Novel drug discovery platform for spinocerebellar ataxia, using fluorescence technology targeting β-III-spectrin. J Biol Chem 2021; 296:100215. [PMID: 33839680 PMCID: PMC7948455 DOI: 10.1074/jbc.ra120.015417] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 11/30/2020] [Accepted: 12/21/2020] [Indexed: 02/02/2023] Open
Abstract
Numerous diseases are linked to mutations in the actin-binding domains (ABDs) of conserved cytoskeletal proteins, including β-III-spectrin, α-actinin, filamin, and dystrophin. A β-III-spectrin ABD mutation (L253P) linked to spinocerebellar ataxia type 5 (SCA5) causes a dramatic increase in actin binding. Reducing actin binding of L253P is thus a potential therapeutic approach for SCA5 pathogenesis. Here, we validate a high-throughput screening (HTS) assay to discover potential disrupters of the interaction between the mutant β-III-spectrin ABD and actin in live cells. This assay monitors FRET between fluorescent proteins fused to the mutant ABD and the actin-binding peptide Lifeact, in HEK293-6E cells. Using a specific and high-affinity actin-binding tool compound, swinholide A, we demonstrate HTS compatibility with an excellent Z'-factor of 0.67 ± 0.03. Screening a library of 1280 pharmacologically active compounds in 1536-well plates to determine assay robustness, we demonstrate high reproducibility across plates and across days. We identified nine Hits that reduced FRET between Lifeact and ABD. Four of those Hits were found to reduce Lifeact cosedimentation with actin, thus establishing the potential of our assay for detection of actin-binding modulators. Concurrent to our primary FRET assay, we also developed a high-throughput compatible counter screen to remove undesirable FRET Hits. Using the FRET Hits, we show that our counter screen is sensitive to undesirable compounds that cause cell toxicity or ABD aggregation. Overall, our FRET-based HTS platform sets the stage to screen large compound libraries for modulators of β-III-spectrin, or disease-linked spectrin-related proteins, for therapeutic development.
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Affiliation(s)
- Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Anna K Andrick
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sarah A Denha
- Department of Chemistry, Oakland University, Rochester, Michigan, USA
| | - Bengt Svensson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Piyali Guhathakurta
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Thomas S Hays
- Department of Genetics, Cellular Biology, and Development, University of Minnesota, Minneapolis, Minnesota, USA
| | - Adam W Avery
- Department of Chemistry, Oakland University, Rochester, Michigan, USA; Department of Genetics, Cellular Biology, and Development, University of Minnesota, Minneapolis, Minnesota, USA.
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Fäßler F, Dimchev G, Hodirnau VV, Wan W, Schur FKM. Cryo-electron tomography structure of Arp2/3 complex in cells reveals new insights into the branch junction. Nat Commun 2020; 11:6437. [PMID: 33353942 PMCID: PMC7755917 DOI: 10.1038/s41467-020-20286-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Accepted: 11/24/2020] [Indexed: 12/21/2022] Open
Abstract
The actin-related protein (Arp)2/3 complex nucleates branched actin filament networks pivotal for cell migration, endocytosis and pathogen infection. Its activation is tightly regulated and involves complex structural rearrangements and actin filament binding, which are yet to be understood. Here, we report a 9.0 Å resolution structure of the actin filament Arp2/3 complex branch junction in cells using cryo-electron tomography and subtomogram averaging. This allows us to generate an accurate model of the active Arp2/3 complex in the branch junction and its interaction with actin filaments. Notably, our model reveals a previously undescribed set of interactions of the Arp2/3 complex with the mother filament, significantly different to the previous branch junction model. Our structure also indicates a central role for the ArpC3 subunit in stabilizing the active conformation.
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Affiliation(s)
- Florian Fäßler
- Institute of Science and Technology (IST) Austria, Klosterneuburg, Austria
| | - Georgi Dimchev
- Institute of Science and Technology (IST) Austria, Klosterneuburg, Austria
| | | | - William Wan
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, United States of America
| | - Florian K M Schur
- Institute of Science and Technology (IST) Austria, Klosterneuburg, Austria.
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39
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Harris AR, Jreij P, Belardi B, Joffe AM, Bausch AR, Fletcher DA. Biased localization of actin binding proteins by actin filament conformation. Nat Commun 2020; 11:5973. [PMID: 33239610 PMCID: PMC7688639 DOI: 10.1038/s41467-020-19768-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 10/30/2020] [Indexed: 11/09/2022] Open
Abstract
The assembly of actin filaments into distinct cytoskeletal structures plays a critical role in cell physiology, but how proteins localize differentially to these structures within a shared cytoplasm remains unclear. Here, we show that the actin-binding domains of accessory proteins can be sensitive to filament conformational changes. Using a combination of live cell imaging and in vitro single molecule binding measurements, we show that tandem calponin homology domains (CH1-CH2) can be mutated to preferentially bind actin networks at the front or rear of motile cells. We demonstrate that the binding kinetics of CH1-CH2 domain mutants varies as actin filament conformation is altered by perturbations that include stabilizing drugs and other binding proteins. These findings suggest that conformational changes of actin filaments in cells could help to direct accessory binding proteins to different actin cytoskeletal structures through a biophysical feedback loop.
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Affiliation(s)
- Andrew R Harris
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA
| | - Pamela Jreij
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA
| | - Brian Belardi
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA
| | - Aaron M Joffe
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA
| | - Andreas R Bausch
- Lehrstuhl für Biophysik (E27), Technische Universität München, Garching, 85748, Germany
| | - Daniel A Fletcher
- Department of Bioengineering and Biophysics Program, University of California, Berkeley, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA.
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, 648 Stanley Hall MC 1762, Berkeley, CA, 94720, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
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40
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Belyy A, Merino F, Sitsel O, Raunser S. Structure of the Lifeact-F-actin complex. PLoS Biol 2020; 18:e3000925. [PMID: 33216759 PMCID: PMC7717565 DOI: 10.1371/journal.pbio.3000925] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 12/04/2020] [Accepted: 10/26/2020] [Indexed: 11/19/2022] Open
Abstract
Lifeact is a short actin-binding peptide that is used to visualize filamentous actin (F-actin) structures in live eukaryotic cells using fluorescence microscopy. However, this popular probe has been shown to alter cellular morphology by affecting the structure of the cytoskeleton. The molecular basis for such artefacts is poorly understood. Here, we determined the high-resolution structure of the Lifeact-F-actin complex using electron cryo-microscopy (cryo-EM). The structure reveals that Lifeact interacts with a hydrophobic binding pocket on F-actin and stretches over 2 adjacent actin subunits, stabilizing the DNase I-binding loop (D-loop) of actin in the closed conformation. Interestingly, the hydrophobic binding site is also used by actin-binding proteins, such as cofilin and myosin and actin-binding toxins, such as the hypervariable region of TccC3 (TccC3HVR) from Photorhabdus luminescens and ExoY from Pseudomonas aeruginosa. In vitro binding assays and activity measurements demonstrate that Lifeact indeed competes with these proteins, providing an explanation for the altering effects of Lifeact on cell morphology in vivo. Finally, we demonstrate that the affinity of Lifeact to F-actin can be increased by introducing mutations into the peptide, laying the foundation for designing improved actin probes for live cell imaging.
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Affiliation(s)
- Alexander Belyy
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Felipe Merino
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Oleg Sitsel
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
- * E-mail:
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41
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Kumari A, Kesarwani S, Javoor MG, Vinothkumar KR, Sirajuddin M. Structural insights into actin filament recognition by commonly used cellular actin markers. EMBO J 2020; 39:e104006. [PMID: 32567727 PMCID: PMC7360965 DOI: 10.15252/embj.2019104006] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 05/11/2020] [Accepted: 05/18/2020] [Indexed: 01/16/2023] Open
Abstract
Cellular studies of filamentous actin (F‐actin) processes commonly utilize fluorescent versions of toxins, peptides, and proteins that bind actin. While the choice of these markers has been largely based on availability and ease, there is a severe dearth of structural data for an informed judgment in employing suitable F‐actin markers for a particular requirement. Here, we describe the electron cryomicroscopy structures of phalloidin, lifeAct, and utrophin bound to F‐actin, providing a comprehensive high‐resolution structural comparison of widely used actin markers and their influence towards F‐actin. Our results show that phalloidin binding does not induce specific conformational change and lifeAct specifically recognizes closed D‐loop conformation, i.e., ADP‐Pi or ADP states of F‐actin. The structural models aided designing of minimal utrophin and a shorter lifeAct, which can be utilized as F‐actin marker. Together, our study provides a structural perspective, where the binding sites of utrophin and lifeAct overlap with majority of actin‐binding proteins and thus offering an invaluable resource for researchers in choosing appropriate actin markers and generating new marker variants.
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Affiliation(s)
- Archana Kumari
- Center for Cardiovascular Biology and Diseases, Institute for Stem Cell Science and Regenerative Medicine, Bengaluru, India
| | - Shubham Kesarwani
- Center for Cardiovascular Biology and Diseases, Institute for Stem Cell Science and Regenerative Medicine, Bengaluru, India.,Manipal Academy of Higher Education, Manipal, India
| | - Manjunath G Javoor
- Center for Cardiovascular Biology and Diseases, Institute for Stem Cell Science and Regenerative Medicine, Bengaluru, India.,Manipal Academy of Higher Education, Manipal, India
| | | | - Minhajuddin Sirajuddin
- Center for Cardiovascular Biology and Diseases, Institute for Stem Cell Science and Regenerative Medicine, Bengaluru, India
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