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Tsilafakis K, Mavroidis M. Are the Head and Tail Domains of Intermediate Filaments Really Unstructured Regions? Genes (Basel) 2024; 15:633. [PMID: 38790262 PMCID: PMC11121635 DOI: 10.3390/genes15050633] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 05/01/2024] [Accepted: 05/14/2024] [Indexed: 05/26/2024] Open
Abstract
Intermediate filaments (IFs) are integral components of the cytoskeleton which provide cells with tissue-specific mechanical properties and are involved in a plethora of cellular processes. Unfortunately, due to their intricate architecture, the 3D structure of the complete molecule of IFs has remained unresolved. Even though most of the rod domain structure has been revealed by means of crystallographic analyses, the flanked head and tail domains are still mostly unknown. Only recently have studies shed light on head or tail domains of IFs, revealing certainsecondary structures and conformational changes during IF assembly. Thus, a deeper understanding of their structure could provide insights into their function.
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Affiliation(s)
- Konstantinos Tsilafakis
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece;
- Department of Biochemistry and Biotechnology, University of Thessaly, Biopolis, 41500 Larissa, Greece
| | - Manolis Mavroidis
- Center of Basic Research, Biomedical Research Foundation, Academy of Athens, 11527 Athens, Greece;
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2
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Schween L, Mücke N, Portet S, Goldmann WH, Herrmann H, Fabry B. Dual-wavelength stopped-flow analysis of the lateral and longitudinal assembly kinetics of vimentin. Biophys J 2022; 121:3850-3861. [PMID: 36101505 PMCID: PMC9674981 DOI: 10.1016/j.bpj.2022.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 08/08/2022] [Accepted: 09/07/2022] [Indexed: 11/18/2022] Open
Abstract
Vimentin is a highly charged intermediate filament protein that inherently forms extended dimeric coiled coils, which serve as the basic building blocks of intermediate filaments. Under low ionic strength conditions, vimentin filaments dissociate into uniform tetrameric complexes of two anti-parallel-oriented, half-staggered coiled-coil dimers. By addition of salt, vimentin tetramers spontaneously reassemble into filaments in a time-dependent process: 1) lateral assembly of tetramers into unit-length filaments, 2) longitudinal annealing of unit-length filaments, and 3) longitudinal assembly of filaments coupled with subsequent radial compaction. To independently determine the lateral and longitudinal assembly kinetics, we measure with a stopped-flow instrument the static light scattering signal at two different wavelengths (405 and 594 nm) with a temporal resolution of 3 ms and analyze the signals based on Rayleigh-Gans theory. This theory considers that the intensity of the scattered light depends not only on the molecular weight of the scattering object but also on its shape. This shape dependence is more pronounced at shorter wavelengths, allowing us to decompose the scattered light signal into its components arising from lateral and longitudinal filament assembly. We demonstrate that both the lateral and longitudinal filament assembly kinetics increase with salt concentration.
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Affiliation(s)
- Lovis Schween
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität of Erlangen-Nürnberg, Erlangen, Germany
| | - Norbert Mücke
- Division of Chromatin Networks, German Cancer Research Center, Heidelberg, Germany
| | - Stéphanie Portet
- Department of Mathematics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Wolfgang H Goldmann
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität of Erlangen-Nürnberg, Erlangen, Germany
| | - Harald Herrmann
- Institute of Neuropathology, University Hospital Erlangen, Erlangen, Germany; Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität of Erlangen-Nürnberg, Erlangen, Germany
| | - Ben Fabry
- Department of Physics, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany; Muscle Research Center Erlangen (MURCE), Friedrich-Alexander-Universität of Erlangen-Nürnberg, Erlangen, Germany.
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3
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Usman S, Aldehlawi H, Nguyen TKN, Teh MT, Waseem A. Impact of N-Terminal Tags on De Novo Vimentin Intermediate Filament Assembly. Int J Mol Sci 2022; 23:ijms23116349. [PMID: 35683030 PMCID: PMC9181571 DOI: 10.3390/ijms23116349] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/02/2022] [Accepted: 06/04/2022] [Indexed: 02/01/2023] Open
Abstract
Vimentin, a type III intermediate filament protein, is found in most cells along with microfilaments and microtubules. It has been shown that the head domain folds back to associate with the rod domain and this association is essential for filament assembly. The N-terminally tagged vimentin has been widely used to label the cytoskeleton in live cell imaging. Although there is previous evidence that EGFP tagged vimentin fails to form filaments but is able to integrate into a pre-existing network, no study has systematically investigated or established a molecular basis for this observation. To determine whether a tag would affect de novo filament assembly, we used vimentin fused at the N-terminus with two different sized tags, AcGFP (239 residues, 27 kDa) and 3 × FLAG (22 residues; 2.4 kDa) to assemble into filaments in two vimentin-deficient epithelial cells, MCF-7 and A431. We showed that regardless of tag size, N-terminally tagged vimentin aggregated into globules with a significant proportion co-aligning with β-catenin at cell–cell junctions. However, the tagged vimentin aggregates could form filaments upon adding untagged vimentin at a ratio of 1:1 or when introduced into cells containing pre-existing filaments. The resultant filament network containing a mixture of tagged and untagged vimentin was less stable compared to that formed by only untagged vimentin. The data suggest that placing a tag at the N-terminus may create steric hinderance in case of a large tag (AcGFP) or electrostatic repulsion in case of highly charged tag (3 × FLAG) perhaps inducing a conformational change, which deleteriously affects the association between head and rod domains. Taken together our results shows that a free N-terminus is essential for filament assembly as N-terminally tagged vimentin is not only incapable of forming filaments, but it also destabilises when integrated into a pre-existing network.
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Affiliation(s)
- Saima Usman
- Centre for Oral Immunobiology and Regenerative Medicine, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Newark Street, London E1 2AT, UK; (S.U.); (T.K.N.N.); (M.-T.T.)
| | - Hebah Aldehlawi
- Department of Oral Diagnostic Sciences, Division of Oral Pathology and Medicine, Faculty of Dentistry, King Abdul Aziz University, Jeddah 21589, Saudi Arabia;
| | - Thuan Khanh Ngoc Nguyen
- Centre for Oral Immunobiology and Regenerative Medicine, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Newark Street, London E1 2AT, UK; (S.U.); (T.K.N.N.); (M.-T.T.)
| | - Muy-Teck Teh
- Centre for Oral Immunobiology and Regenerative Medicine, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Newark Street, London E1 2AT, UK; (S.U.); (T.K.N.N.); (M.-T.T.)
| | - Ahmad Waseem
- Centre for Oral Immunobiology and Regenerative Medicine, Institute of Dentistry, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, Newark Street, London E1 2AT, UK; (S.U.); (T.K.N.N.); (M.-T.T.)
- Centre for Immunobiology and Regenerative Medicine, Blizard Institute, 4 Newark Street, London E1 2AT, UK
- Correspondence: ; Tel.: +44-207-882-2387; Fax: +44-207-882-7137
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4
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Kaus‐Drobek M, Mücke N, Szczepanowski RH, Wedig T, Czarnocki‐Cieciura M, Polakowska M, Herrmann H, Wysłouch‐Cieszyńska A, Dadlez M. Vimentin S-glutathionylation at Cys328 inhibits filament elongation and induces severing of mature filaments in vitro. FEBS J 2020; 287:5304-5322. [PMID: 32255262 PMCID: PMC7818121 DOI: 10.1111/febs.15321] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 02/17/2020] [Accepted: 03/31/2020] [Indexed: 12/26/2022]
Abstract
Vimentin intermediate filaments are a significant component of the cytoskeleton in cells of mesenchymal origin. In vivo, filaments assemble and disassemble and thus participate in the dynamic processes of the cell. Post-translational modifications (PTMs) such as protein phosphorylation regulate the multiphasic association of vimentin from soluble complexes to insoluble filaments and the reverse processes. The thiol side chain of the single vimentin cysteine at position 328 (Cys328) is a direct target of oxidative modifications inside cells. Here, we used atomic force microscopy, electron microscopy and a novel hydrogen-deuterium exchange mass spectrometry (HDex-MS) procedure to investigate the structural consequences of S-nitrosylation and S-glutathionylation of Cys328 for in vitro oligomerisation of human vimentin. Neither modification affects the lateral association of tetramers to unit-length filaments (ULF). However, S-glutathionylation of Cys328 blocks the longitudinal assembly of ULF into extended filaments. S-nitrosylation of Cys328 does not hinder but slows down the elongation. Likewise, S-glutathionylation of preformed vimentin filaments causes their extensive fragmentation to smaller oligomeric species. Chemical reduction of the S-glutathionylated Cys328 thiols induces reassembly of the small fragments into extended filaments. In conclusion, our in vitro results suggest S-glutathionylation as a candidate PTM for an efficient molecular switch in the dynamic rearrangements of vimentin intermediate filaments, observed in vivo, in response to changes in cellular redox status. Finally, we demonstrate that HDex-MS is a powerful method for probing the kinetics of vimentin filament formation and filament disassembly induced by PTMs.
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Affiliation(s)
- Magdalena Kaus‐Drobek
- Laboratory of Mass SpectrometryInstitute of Biochemistry and BiophysicsPolish Academy of SciencesWarsawPoland
| | - Norbert Mücke
- Biophysics of MacromoleculesGerman Cancer Research Center (DKFZ)HeidelbergGermany
- Chromatin NetworksGerman Cancer Research Center (DKFZ)HeidelbergGermany
| | - Roman H. Szczepanowski
- Biophysics Core FacilityInternational Institute of Molecular and Cell BiologyWarsawPoland
| | - Tatjana Wedig
- Biophysics of MacromoleculesGerman Cancer Research Center (DKFZ)HeidelbergGermany
| | | | - Magdalena Polakowska
- Laboratory of Mass SpectrometryInstitute of Biochemistry and BiophysicsPolish Academy of SciencesWarsawPoland
| | - Harald Herrmann
- Institute of NeuropathologyUniversity Hospital ErlangenGermany
- Division of Molecular GeneticsGerman Cancer Research Center (DKFZ)HeidelbergGermany
| | | | - Michał Dadlez
- Laboratory of Mass SpectrometryInstitute of Biochemistry and BiophysicsPolish Academy of SciencesWarsawPoland
- Biology DepartmentInstitute of Genetics and BiotechnologyWarsaw UniversityPoland
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5
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The Cytoskeleton-A Complex Interacting Meshwork. Cells 2019; 8:cells8040362. [PMID: 31003495 PMCID: PMC6523135 DOI: 10.3390/cells8040362] [Citation(s) in RCA: 179] [Impact Index Per Article: 35.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/22/2022] Open
Abstract
The cytoskeleton of animal cells is one of the most complicated and functionally versatile structures, involved in processes such as endocytosis, cell division, intra-cellular transport, motility, force transmission, reaction to external forces, adhesion and preservation, and adaptation of cell shape. These functions are mediated by three classical cytoskeletal filament types, as follows: Actin, microtubules, and intermediate filaments. The named filaments form a network that is highly structured and dynamic, responding to external and internal cues with a quick reorganization that is orchestrated on the time scale of minutes and has to be tightly regulated. Especially in brain tumors, the cytoskeleton plays an important role in spreading and migration of tumor cells. As the cytoskeletal organization and regulation is complex and many-faceted, this review aims to summarize the findings about cytoskeletal filament types, including substructures formed by them, such as lamellipodia, stress fibers, and interactions between intermediate filaments, microtubules and actin. Additionally, crucial regulatory aspects of the cytoskeletal filaments and the formed substructures are discussed and integrated into the concepts of cell motility. Even though little is known about the impact of cytoskeletal alterations on the progress of glioma, a final point discussed will be the impact of established cytoskeletal alterations in the cellular behavior and invasion of glioma.
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6
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Brennich ME, Vainio U, Wedig T, Bauch S, Herrmann H, Köster S. Mutation-induced alterations of intra-filament subunit organization in vimentin filaments revealed by SAXS. SOFT MATTER 2019; 15:1999-2008. [PMID: 30719518 DOI: 10.1039/c8sm02281j] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Vimentin intermediate filaments constitute a distinct filament system in mesenchymal cells that is instrumental for cellular mechanics and migration. In vitro, the rod-like monomers assemble in a multi-step, salt-dependent manner into micrometer long biopolymers. To disclose the underlying mechanisms further, we employed small angle X-ray scattering on two recombinant vimentin variants, whose assembly departs at strategic points from the normal assembly route: (i) vimentin with a tyrosine to leucine change at position 117; (ii) vimentin missing the non-α-helical carboxyl-terminal domain. Y117L vimentin assembles into unit-length filaments (ULFs) only, whereas ΔT vimentin assembles into filaments containing a higher number of tetramers per cross section than normal vimentin filaments. We show that the shape and inner structure of these mutant filaments is significantly altered. ULFs assembled from Y117L vimentin contain more, less tightly bundled vimentin tetramers, and ΔT vimentin filaments preserve the number density despite the higher number of tetramers per filament cross-section.
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Affiliation(s)
- Martha E Brennich
- Institute for X-ray Physics, University of Goettingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
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7
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Danielsson F, Peterson MK, Caldeira Araújo H, Lautenschläger F, Gad AKB. Vimentin Diversity in Health and Disease. Cells 2018; 7:E147. [PMID: 30248895 PMCID: PMC6210396 DOI: 10.3390/cells7100147] [Citation(s) in RCA: 157] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 09/16/2018] [Accepted: 09/17/2018] [Indexed: 12/11/2022] Open
Abstract
Vimentin is a protein that has been linked to a large variety of pathophysiological conditions, including cataracts, Crohn's disease, rheumatoid arthritis, HIV and cancer. Vimentin has also been shown to regulate a wide spectrum of basic cellular functions. In cells, vimentin assembles into a network of filaments that spans the cytoplasm. It can also be found in smaller, non-filamentous forms that can localise both within cells and within the extracellular microenvironment. The vimentin structure can be altered by subunit exchange, cleavage into different sizes, re-annealing, post-translational modifications and interacting proteins. Together with the observation that different domains of vimentin might have evolved under different selection pressures that defined distinct biological functions for different parts of the protein, the many diverse variants of vimentin might be the cause of its functional diversity. A number of review articles have focussed on the biology and medical aspects of intermediate filament proteins without particular commitment to vimentin, and other reviews have focussed on intermediate filaments in an in vitro context. In contrast, the present review focusses almost exclusively on vimentin, and covers both ex vivo and in vivo data from tissue culture and from living organisms, including a summary of the many phenotypes of vimentin knockout animals. Our aim is to provide a comprehensive overview of the current understanding of the many diverse aspects of vimentin, from biochemical, mechanical, cellular, systems biology and medical perspectives.
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Affiliation(s)
- Frida Danielsson
- Science for Life Laboratory, Royal Institute of Technology, 17165 Stockholm, Sweden.
| | | | | | - Franziska Lautenschläger
- Campus D2 2, Leibniz-Institut für Neue Materialien gGmbH (INM) and Experimental Physics, NT Faculty, E 2 6, Saarland University, 66123 Saarbrücken, Germany.
| | - Annica Karin Britt Gad
- Centro de Química da Madeira, Universidade da Madeira, 9020105 Funchal, Portugal.
- Department of Medical Biochemistry and Microbiology, Uppsala University, 75237 Uppsala, Sweden.
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8
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Pang AH, Obiero JM, Kulczyk AW, Sviripa VM, Tsodikov OV. A crystal structure of coil 1B of vimentin in the filamentous form provides a model of a high-order assembly of a vimentin filament. FEBS J 2018; 285:2888-2899. [PMID: 29905014 DOI: 10.1111/febs.14585] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 05/01/2018] [Accepted: 06/13/2018] [Indexed: 12/25/2022]
Abstract
Vimentin is an intermediate filament (IF) protein that is expressed in leukocytes, fibroblasts and endothelial cells of blood vessels. Vimentin filaments contribute to structural stability of the cell membrane, organelle positioning and protein transport. Vimentin self-assembles into a dimer that subsequently forms high-order structures, including tetramers and octamers. The details of IF assembly at crystallographic resolutions are limited to the tetrameric form. We describe a crystal structure of a fragment of a vimentin rod domain (coil 1B) with a dimer of tetramers in the asymmetric unit. Coil 1B in the crystal is in an infinitely high-order filamentous assembly state, in which the tetramers are packed against each other laterally in an antiparallel fashion across the crystal lattice. In one of the directions of lateral packing, the tetramers pack against each other strictly head-to-tail, and in the orthogonal direction the tetramers pack in a staggered manner. This organization of the tetramers of coil 1B in the crystal lattice, together with previously reported biochemical and structural data, yield a model of high-order vimentin filament assembly. DATABASE Structural data are available in the PDB under the accession number 5WHF.
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Affiliation(s)
- Allan H Pang
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Josiah M Obiero
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Arkadiusz W Kulczyk
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA, USA
| | - Vitaliy M Sviripa
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, USA
| | - Oleg V Tsodikov
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA
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9
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Mücke N, Kämmerer L, Winheim S, Kirmse R, Krieger J, Mildenberger M, Baßler J, Hurt E, Goldmann WH, Aebi U, Toth K, Langowski J, Herrmann H. Assembly Kinetics of Vimentin Tetramers to Unit-Length Filaments: A Stopped-Flow Study. Biophys J 2018; 114:2408-2418. [PMID: 29754715 DOI: 10.1016/j.bpj.2018.04.032] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 03/20/2018] [Accepted: 04/19/2018] [Indexed: 01/01/2023] Open
Abstract
Intermediate filaments (IFs) are principal components of the cytoskeleton, a dynamic integrated system of structural proteins that provides the functional architecture of metazoan cells. They are major contributors to the elasticity of cells and tissues due to their high mechanical stability and intrinsic flexibility. The basic building block for the assembly of IFs is a rod-like, 60-nm-long tetrameric complex made from two antiparallel, half-staggered coiled coils. In low ionic strength, tetramers form stable complexes that rapidly assemble into filaments upon raising the ionic strength. The first assembly products, "frozen" by instantaneous chemical fixation and viewed by electron microscopy, are 60-nm-long "unit-length" filaments (ULFs) that apparently form by lateral in-register association of tetramers. ULFs are the active elements of IF growth, undergoing longitudinal end-to-end annealing with one another and with growing filaments. Originally, we have employed quantitative time-lapse atomic force and electron microscopy to analyze the kinetics of vimentin-filament assembly starting from a few seconds to several hours. To obtain detailed quantitative insight into the productive reactions that drive ULF formation, we now introduce a "stopped-flow" approach in combination with static light-scattering measurements. Thereby, we determine the basic rate constants for lateral assembly of tetramers to ULFs. Processing of the recorded data by a global fitting procedure enables us to describe the hierarchical steps of IF formation. Specifically, we propose that tetramers are consumed within milliseconds to yield octamers that are obligatory intermediates toward ULF formation. Although the interaction of tetramers is diffusion controlled, it is strongly driven by their geometry to mediate effective subunit targeting. Importantly, our model conclusively reflects the previously described occurrence of polymorphic ULF and mature filaments in terms of their number of tetramers per cross section.
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Affiliation(s)
- Norbert Mücke
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Lara Kämmerer
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Stefan Winheim
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Robert Kirmse
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Jan Krieger
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Maria Mildenberger
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Jochen Baßler
- Biochemistry Center of Heidelberg University, Heidelberg, Germany
| | - Ed Hurt
- Biochemistry Center of Heidelberg University, Heidelberg, Germany
| | - Wolfgang H Goldmann
- Department of Physics, Biophysics group, Friedrich-Alexander-University of Erlangen-Nuremberg, Erlangen, Germany
| | - Ueli Aebi
- Biozentrum, University of Basel, Basel, Switzerland
| | - Katalin Toth
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Jörg Langowski
- Division Biophysics of Macromolecules, German Cancer Research Center, Heidelberg, Germany
| | - Harald Herrmann
- Institute of Neuropathology, University Hospital Erlangen, Erlangen, Germany; Division of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany.
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10
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Abstract
Proteins of the intermediate filament (IF) supergene family are ubiquitous structural components that comprise, in a cell type-specific manner, the cytoskeleton proper in animal tissues. All IF proteins show a distinctly organized, extended α-helical conformation prone to form two-stranded coiled coils, which are the basic building blocks of these highly flexible, stress-resistant cytoskeletal filaments. IF proteins are highly charged, thus representing versatile polyampholytes with multiple functions. Taking vimentin, keratins, and the nuclear lamins as our prime examples, we present an overview of their molecular and structural parameters. These, in turn, document the ability of IF proteins to form distinct, highly diverse supramolecular assemblies and biomaterials found, for example, at the inner nuclear membrane, throughout the cytoplasm, and in highly complex extracellular appendages, such as hair and nails, of vertebrate organisms. Ultimately, our aim is to set the stage for a more rational understanding of the immediate effects that missense mutations in IF genes have on cellular functions and for their far-reaching impact on the development of the numerous IF diseases caused by them.
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Affiliation(s)
- Harald Herrmann
- Functional Architecture of the Cell (B065), German Cancer Research Center (DKFZ), D-69120 Heidelberg, Germany, and Institute of Neuropathology, University Hospital Erlangen, D-91054 Erlangen, Germany
| | - Ueli Aebi
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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11
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Rivera-Najera LY, Saab-Rincón G, Battaglia M, Amero C, Pulido NO, García-Hernández E, Solórzano RM, Reyes JL, Covarrubias AA. A group 6 late embryogenesis abundant protein from common bean is a disordered protein with extended helical structure and oligomer-forming properties. J Biol Chem 2014; 289:31995-32009. [PMID: 25271167 DOI: 10.1074/jbc.m114.583369] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Late embryogenesis-abundant proteins accumulate to high levels in dry seeds. Some of them also accumulate in response to water deficit in vegetative tissues, which leads to a remarkable association between their presence and low water availability conditions. A major sub-group of these proteins, also known as typical LEA proteins, shows high hydrophilicity and a high percentage of glycine and other small amino acid residues, distinctive physicochemical properties that predict a high content of structural disorder. Although all typical LEA proteins share these characteristics, seven groups can be distinguished by sequence similarity, indicating structural and functional diversity among them. Some of these groups have been extensively studied; however, others require a more detailed analysis to advance in their functional understanding. In this work, we report the structural characterization of a group 6 LEA protein from a common bean (Phaseolus vulgaris L.) (PvLEA6) by circular dichroism and nuclear magnetic resonance showing that it is a disordered protein in aqueous solution. Using the same techniques, we show that despite its unstructured nature, the addition of trifluoroethanol exhibited an intrinsic potential in this protein to gain helicity. This property was also promoted by high osmotic potentials or molecular crowding. Furthermore, we demonstrate that PvLEA6 protein is able to form soluble homo-oligomeric complexes that also show high levels of structural disorder. The association between PvLEA6 monomers to form dimers was shown to occur in plant cells by bimolecular fluorescence complementation, pointing to the in vivo functional relevance of this association.
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Affiliation(s)
- Lucero Y Rivera-Najera
- Departamentos de Biología Molecular de Plantas and Universidad Nacional Autónoma de México, Apdo. Postal 510-3, 62250 Cuernavaca, Mor
| | - Gloria Saab-Rincón
- Departamentos de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 510-3, 62250 Cuernavaca, Mor
| | - Marina Battaglia
- Departamentos de Biología Molecular de Plantas and Universidad Nacional Autónoma de México, Apdo. Postal 510-3, 62250 Cuernavaca, Mor
| | - Carlos Amero
- Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Av. Universidad No. 1001, Col Chamilpa, 62209 Cuernavaca, Morelos, and
| | - Nancy O Pulido
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México 04510, D. F. México
| | - Enrique García-Hernández
- Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, México 04510, D. F. México
| | - Rosa M Solórzano
- Departamentos de Biología Molecular de Plantas and Universidad Nacional Autónoma de México, Apdo. Postal 510-3, 62250 Cuernavaca, Mor
| | - José L Reyes
- Departamentos de Biología Molecular de Plantas and Universidad Nacional Autónoma de México, Apdo. Postal 510-3, 62250 Cuernavaca, Mor
| | - Alejandra A Covarrubias
- Departamentos de Biología Molecular de Plantas and Universidad Nacional Autónoma de México, Apdo. Postal 510-3, 62250 Cuernavaca, Mor..
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12
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Robert A, Herrmann H, Davidson MW, Gelfand VI. Microtubule-dependent transport of vimentin filament precursors is regulated by actin and by the concerted action of Rho- and p21-activated kinases. FASEB J 2014; 28:2879-90. [PMID: 24652946 DOI: 10.1096/fj.14-250019] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Intermediate filaments (IFs) form a dense and dynamic network that is functionally associated with microtubules and actin filaments. We used the GFP-tagged vimentin mutant Y117L to study vimentin-cytoskeletal interactions and transport of vimentin filament precursors. This mutant preserves vimentin interaction with other components of the cytoskeleton, but its assembly is blocked at the unit-length filament (ULF) stage. ULFs are easy to track, and they allow a reliable and quantifiable analysis of movement. Our results show that in cultured human vimentin-negative SW13 cells, 2% of vimentin-ULFs move along microtubules bidirectionally, while the majority are stationary and tightly associated with actin filaments. Rapid motor-dependent transport of ULFs along microtubules is enhanced ≥ 5-fold by depolymerization of actin cytoskeleton with latrunculin B. The microtubule-dependent transport of vimentin ULFs is further regulated by Rho-kinase (ROCK) and p21-activated kinase (PAK): ROCK inhibits ULF transport, while PAK stimulates it. Both kinases act on microtubule transport independently of their effects on actin cytoskeleton. Our study demonstrates the importance of the actin cytoskeleton to restrict IF transport and reveals a new role for PAK and ROCK in the regulation of IF precursor transport.-Robert, A., Herrmann, H., Davidson, M. W., and Gelfand, V. I. Microtubule-dependent transport of vimentin filament precursors is regulated by actin and by the concerted action of Rho- and p21-activated kinases.
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Affiliation(s)
- Amélie Robert
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA
| | - Harald Herrmann
- Division of Molecular Genetics, German Cancer Research Center, Heidelberg, Germany; and
| | - Michael W Davidson
- National High Magnetic Field Laboratory and Department of Biological Science, Florida State University, Tallahassee, Florida, USA
| | - Vladimir I Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois, USA;
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Atomic structure of the vimentin central α-helical domain and its implications for intermediate filament assembly. Proc Natl Acad Sci U S A 2012; 109:13620-5. [PMID: 22869704 DOI: 10.1073/pnas.1206836109] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Together with actin filaments and microtubules, intermediate filaments (IFs) are the basic cytoskeletal components of metazoan cells. Over 80 human diseases have been linked to mutations in various IF proteins to date. However, the filament structure is far from being resolved at the atomic level, which hampers rational understanding of IF pathologies. The elementary building block of all IF proteins is a dimer consisting of an α-helical coiled-coil (CC) "rod" domain flanked by the flexible head and tail domains. Here we present three crystal structures of overlapping human vimentin fragments that comprise the first half of its rod domain. Given the previously solved fragments, a nearly complete atomic structure of the vimentin rod has become available. It consists of three α-helical segments (coils 1A, 1B, and 2) interconnected by linkers (L1 and L12). Most of the CC structure has a left-handed twist with heptad repeats, but both coil 1B and coil 2 also exhibit untwisted, parallel stretches with hendecad repeats. In the crystal structure, linker L1 was found to be α-helical without being involved in the CC formation. The available data allow us to construct an atomic model of the antiparallel tetramer representing the second level of vimentin assembly. Although the presence of the nonhelical head domains is essential for proper tetramer stabilization, the precise alignment of the dimers forming the tetramer appears to depend on the complementarity of their surface charge distribution patterns, while the structural plasticity of linker L1 and coil 1A plays a role in the subsequent IF assembly process.
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14
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Ishii D, Abe R, Watanabe SI, Tsuchiya M, Nöcker B, Tsumoto K. Stepwise Characterization of the Thermodynamics of Trichocyte Intermediate Filament Protein Supramolecular Assembly. J Mol Biol 2011; 408:832-8. [DOI: 10.1016/j.jmb.2011.03.034] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 03/14/2011] [Accepted: 03/16/2011] [Indexed: 11/29/2022]
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15
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Deconstructing the late phase of vimentin assembly by total internal reflection fluorescence microscopy (TIRFM). PLoS One 2011; 6:e19202. [PMID: 21544245 PMCID: PMC3081349 DOI: 10.1371/journal.pone.0019202] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Accepted: 03/23/2011] [Indexed: 11/23/2022] Open
Abstract
Quantitative imaging of intermediate filaments (IF) during the advanced phase of the assembly process is technically difficult, since the structures are several µm long and therefore they exceed the field of view of many electron (EM) or atomic force microscopy (AFM) techniques. Thereby quantitative studies become extremely laborious and time-consuming. To overcome these difficulties, we prepared fluorescently labeled vimentin for visualization by total internal reflection fluorescence microscopy (TIRFM). In order to investigate if the labeling influences the assembly properties of the protein, we first determined the association state of unlabeled vimentin mixed with increasing amounts of labeled vimentin under low ionic conditions by analytical ultracentrifugation. We found that bona fide tetrameric complexes were formed even when half of the vimentin was labeled. Moreover, we demonstrate by quantitative atomic force microscopy and electron microscopy that the morphology and the assembly properties of filaments were not affected when the fraction of labeled vimentin was below 10%. Using fast frame rates we observed the rapid deposition of fluorescently labeled IFs on glass supports by TIRFM in real time. By tracing their contours, we have calculated the persistence length of long immobilized vimentin IFs to 1 µm, a value that is identical to those determined for shorter unlabeled vimentin. These results indicate that the structural properties of the filaments were not affected significantly by the dye. Furthermore, in order to analyze the late elongation phase, we mixed long filaments containing either Alexa 488- or Alexa 647-labeled vimentin. The ‘patchy’ structure of the filaments obtained unambiguously showed the elongation of long IFs through direct end-to-end annealing of individual filaments.
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16
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A multi-scale approach to understand the mechanobiology of intermediate filaments. J Biomech 2010; 43:15-22. [DOI: 10.1016/j.jbiomech.2009.09.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/2009] [Indexed: 01/04/2023]
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17
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Portet S, Mücke N, Kirmse R, Langowski J, Beil M, Herrmann H. Vimentin intermediate filament formation: in vitro measurement and mathematical modeling of the filament length distribution during assembly. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:8817-23. [PMID: 20050052 DOI: 10.1021/la900509r] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The salt-induced in vitro assembly of cytoplasmic intermediate filament (IF) proteins such as vimentin is characterized by a very rapid lateral association of soluble tetrameric subunits into 60-nm-long full-width "unit-length" filaments (ULFs). We have demonstrated for this prototype IF protein that filament elongation occurs by the longitudinal annealing of ULFs into short IFs. These IFs further longitudinally anneal and thus constitute a progressively elongating filament population that over time yields filaments of several microm in length. Previously, we provided a mathematical model for the kinetics of the assembly process based on the average length distribution of filaments as determined by time-lapse electron and atomic force microscopy. Thereby, we were able to substantiate the concept that end-to-end-annealing of both ULFs and short filaments is obligatory for the formation of long IFs (Kirmse, R.; Portet, S.; Mücke, N. Aebi, U.; Herrmann, H.; Langowski, J. J. Biol. Chem. 2007, 282, 18563-18572). As the next step in understanding the mechanics of IF formation, we have expanded our mathematical model to describe the quantitative aspects of IF assembly by taking into account geometry constraints as well as the diffusion properties of rodlike linear aggregates. Thereby, we have developed a robust model for the time-dependent filament length distribution of IFs under standard conditions.
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Affiliation(s)
- Stéphanie Portet
- Department of Mathematics, 342 Machray Hall, University of Manitoba, Winnipeg, MB, Canada R3L 2N2.
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Herrmann H, Strelkov SV, Burkhard P, Aebi U. Intermediate filaments: primary determinants of cell architecture and plasticity. J Clin Invest 2009; 119:1772-83. [PMID: 19587452 DOI: 10.1172/jci38214] [Citation(s) in RCA: 220] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Intermediate filaments (IFs) are major constituents of the cytoskeleton and nuclear boundary in animal cells. They are of prime importance for the functional organization of structural elements. Depending on the cell type, morphologically similar but biochemically distinct proteins form highly viscoelastic filament networks with multiple nanomechanical functions. Besides their primary role in cell plasticity and their established function as cellular stress absorbers, recently discovered gene defects have elucidated that structural alterations of IFs can affect their involvement both in signaling and in controlling gene regulatory networks. Here, we highlight the basic structural and functional properties of IFs and derive a concept of how mutations may affect cellular architecture and thereby tissue construction and physiology.
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Affiliation(s)
- Harald Herrmann
- Group Functional Architecture of the Cell, German Cancer Research Center, Heidelberg, Germany.
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Meier M, Padilla GP, Herrmann H, Wedig T, Hergt M, Patel TR, Stetefeld J, Aebi U, Burkhard P. Vimentin coil 1A-A molecular switch involved in the initiation of filament elongation. J Mol Biol 2009; 390:245-61. [PMID: 19422834 DOI: 10.1016/j.jmb.2009.04.067] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2009] [Revised: 04/27/2009] [Accepted: 04/29/2009] [Indexed: 12/25/2022]
Abstract
Interestingly, our previously published structure of the coil 1A fragment of the human intermediate filament protein vimentin turned out to be a monomeric alpha-helical coil instead of the expected dimeric coiled coil. However, the 39-amino-acid-long helix had an intrinsic curvature compatible with a coiled coil. We have now designed four mutants of vimentin coil 1A, modifying key a and d positions in the heptad repeat pattern, with the aim of investigating the molecular criteria that are needed to stabilize a dimeric coiled-coil structure. We have analysed the biophysical properties of the mutants by circular dichroism spectroscopy, analytical ultracentrifugation and X-ray crystallography. All four mutants exhibited an increased stability over the wild type as indicated by a rise in the melting temperature (T(m)). At a concentration of 0.1 mg/ml, the T(m) of the peptide with the single point mutation Y117L increased dramatically by 46 degrees C compared with the wild-type peptide. In general, the introduction of a single stabilizing point mutation at an a or a d position did induce the formation of a stable dimer as demonstrated by sedimentation equilibrium experiments. The dimeric oligomerisation state of the Y117L peptide was furthermore confirmed by X-ray crystallography, which yielded a structure with a genuine coiled-coil geometry. Most notably, when this mutation was introduced into full-length vimentin, filament assembly was completely arrested at the unit-length filament (ULF) level, both in vitro and in cDNA-transfected cultured cells. Therefore, the low propensity of the wild-type coil 1A to form a stable two-stranded coiled coil is most likely a prerequisite for the end-to-end annealing of ULFs into filaments. Accordingly, the coil 1A domains might "switch" from a dimeric alpha-helical coiled coil into a more open structure, thus mediating, within the ULFs, the conformational rearrangements of the tetrameric subunits that are needed for the intermediate filament elongation reaction.
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Affiliation(s)
- Markus Meier
- Department of Chemistry, University of Manitoba, Winnipeg, Canada.
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