1
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Vermeulen BJ, Böhler A, Gao Q, Neuner A, Župa E, Chu Z, Würtz M, Jäkle U, Gruss OJ, Pfeffer S, Schiebel E. γ-TuRC asymmetry induces local protofilament mismatch at the RanGTP-stimulated microtubule minus end. EMBO J 2024; 43:2062-2085. [PMID: 38600243 DOI: 10.1038/s44318-024-00087-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Revised: 03/15/2024] [Accepted: 03/18/2024] [Indexed: 04/12/2024] Open
Abstract
The γ-tubulin ring complex (γ-TuRC) is a structural template for de novo microtubule assembly from α/β-tubulin units. The isolated vertebrate γ-TuRC assumes an asymmetric, open structure deviating from microtubule geometry, suggesting that γ-TuRC closure may underlie regulation of microtubule nucleation. Here, we isolate native γ-TuRC-capped microtubules from Xenopus laevis egg extract nucleated through the RanGTP-induced pathway for spindle assembly and determine their cryo-EM structure. Intriguingly, the microtubule minus end-bound γ-TuRC is only partially closed and consequently, the emanating microtubule is locally misaligned with the γ-TuRC and asymmetric. In the partially closed conformation of the γ-TuRC, the actin-containing lumenal bridge is locally destabilised, suggesting lumenal bridge modulation in microtubule nucleation. The microtubule-binding protein CAMSAP2 specifically binds the minus end of γ-TuRC-capped microtubules, indicating that the asymmetric minus end structure may underlie recruitment of microtubule-modulating factors for γ-TuRC release. Collectively, we reveal a surprisingly asymmetric microtubule minus end protofilament organisation diverging from the regular microtubule structure, with direct implications for the kinetics and regulation of nucleation and subsequent modulation of microtubules during spindle assembly.
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Affiliation(s)
- Bram Ja Vermeulen
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Anna Böhler
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Qi Gao
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Erik Župa
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Zhenzhen Chu
- Institut für Genetik, Universität Bonn, Bonn, Germany
- Key Laboratory of Carcinogenesis and Translational Research (Ministry of Education, Beijing), Lymphoma Department, Peking University Cancer Hospital & Institute, Beijing, China
| | - Martin Würtz
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Ursula Jäkle
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | | | - Stefan Pfeffer
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany.
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie, Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany.
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2
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Liang LY, Geoghegan ND, Mlodzianoski M, Leis A, Whitehead LW, Surudoi MG, Young SN, Janes P, Shepherd D, Ghosal D, Rogers KL, Murphy JM, Lucet IS. Co-clustering of EphB6 and ephrinB1 in trans restrains cancer cell invasion. Commun Biol 2024; 7:461. [PMID: 38627519 PMCID: PMC11021433 DOI: 10.1038/s42003-024-06118-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Accepted: 03/27/2024] [Indexed: 04/19/2024] Open
Abstract
EphB6 is an understudied ephrin receptor tyrosine pseudokinase that is downregulated in multiple types of metastatic cancers. Unlike its kinase-active counterparts which autophosphorylate and transmit signals upon intercellular interaction, little is known about how EphB6 functions in the absence of intrinsic kinase activity. Here, we unveil a molecular mechanism of cell-cell interaction driven by EphB6. We identify ephrinB1 as a cognate ligand of EphB6 and show that in trans interaction of EphB6 with ephrinB1 on neighboring cells leads to the formation of large co-clusters at the plasma membrane. These co-clusters exhibit a decreased propensity towards endocytosis, suggesting a unique characteristic for this type of cell-cell interaction. Using lattice light-sheet microscopy, 3D structured illumination microscopy and cryo-electron tomography techniques, we show that co-clustering of EphB6 and ephrinB1 promotes the formation of double-membrane tubular structures between cells. Importantly, we also demonstrate that these intercellular structures stabilize cell-cell adhesion, leading to a reduction in the invasive behavior of cancer cells. Our findings rationalize a role for EphB6 pseudokinase as a tumor suppressor when interacting with its ligands in trans.
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Affiliation(s)
- Lung-Yu Liang
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Niall D Geoghegan
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Michael Mlodzianoski
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Andrew Leis
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Lachlan W Whitehead
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Minglyanna G Surudoi
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Samuel N Young
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - Peter Janes
- Olivia Newton-John Cancer Research Institute and La Trobe School of Cancer Medicine, Level 5, ONJ Centre, 145 Studley Rd, Heidelberg, VIC, 3084, Australia
| | - Doulin Shepherd
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Debnath Ghosal
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3052, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3052, Australia
| | - Kelly L Rogers
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia
| | - James M Murphy
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, 3052, Australia.
| | - Isabelle S Lucet
- Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- Department of Medical Biology, University of Melbourne, 1G Royal Parade, Parkville, VIC, 3052, Australia.
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, 3052, Australia.
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3
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Okenve-Ramos P, Gosling R, Chojnowska-Monga M, Gupta K, Shields S, Alhadyian H, Collie C, Gregory E, Sanchez-Soriano N. Neuronal ageing is promoted by the decay of the microtubule cytoskeleton. PLoS Biol 2024; 22:e3002504. [PMID: 38478582 PMCID: PMC10962844 DOI: 10.1371/journal.pbio.3002504] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 03/25/2024] [Accepted: 01/17/2024] [Indexed: 03/26/2024] Open
Abstract
Natural ageing is accompanied by a decline in motor, sensory, and cognitive functions, all impacting quality of life. Ageing is also the predominant risk factor for many neurodegenerative diseases, including Parkinson's disease and Alzheimer's disease. We need to therefore gain a better understanding of the cellular and physiological processes underlying age-related neuronal decay. However, gaining this understanding is a slow process due to the large amount of time required to age mammalian or vertebrate animal models. Here, we introduce a new cellular model within the Drosophila brain, in which we report classical ageing hallmarks previously observed in the primate brain. These hallmarks include axonal swellings, cytoskeletal decay, a reduction in axonal calibre, and morphological changes arising at synaptic terminals. In the fly brain, these changes begin to occur within a few weeks, ideal to study the underlying mechanisms of ageing. We discovered that the decay of the neuronal microtubule (MT) cytoskeleton precedes the onset of other ageing hallmarks. We showed that the MT-binding factors Tau, EB1, and Shot/MACF1, are necessary for MT maintenance in axons and synapses, and that their functional loss during ageing triggers MT bundle decay, followed by a decline in axons and synaptic terminals. Furthermore, genetic manipulations that improve MT networks slowed down the onset of neuronal ageing hallmarks and confer aged specimens the ability to outperform age-matched controls. Our work suggests that MT networks are a key lesion site in ageing neurons and therefore the MT cytoskeleton offers a promising target to improve neuronal decay in advanced age.
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Affiliation(s)
- Pilar Okenve-Ramos
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Rory Gosling
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Monika Chojnowska-Monga
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Kriti Gupta
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Samuel Shields
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Haifa Alhadyian
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Ceryce Collie
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Emilia Gregory
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Natalia Sanchez-Soriano
- Department of Biochemistry, Cell and Systems Biology, Institute of Systems, Molecular & Integrative Biology, University of Liverpool, Liverpool, United Kingdom
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4
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Gonzalez SJ, Heckel JM, Goldblum RR, Reid TA, McClellan M, Gardner MK. Rapid binding to protofilament edge sites facilitates tip tracking of EB1 at growing microtubule plus-ends. eLife 2024; 13:e91719. [PMID: 38385657 PMCID: PMC10883673 DOI: 10.7554/elife.91719] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
EB1 is a key cellular protein that delivers regulatory molecules throughout the cell via the tip-tracking of growing microtubule plus-ends. Thus, it is important to understand the mechanism for how EB1 efficiently tracks growing microtubule plus-ends. It is widely accepted that EB1 binds with higher affinity to GTP-tubulin subunits at the growing microtubule tip, relative to GDP-tubulin along the microtubule length. However, it is unclear whether this difference in affinity alone is sufficient to explain the tip-tracking of EB1 at growing microtubule tips. Previously, we found that EB1 binds to exposed microtubule protofilament-edge sites at a ~70 fold faster rate than to closed-lattice sites, due to diffusional steric hindrance to binding. Thus, we asked whether rapid protofilament-edge binding could contribute to efficient EB1 tip tracking. A computational simulation with differential EB1 on-rates based on closed-lattice or protofilament-edge binding, and with EB1 off-rates that were dependent on the tubulin hydrolysis state, robustly recapitulated experimental EB1 tip tracking. To test this model, we used cell-free biophysical assays, as well as live-cell imaging, in combination with a Designed Ankyrin Repeat Protein (DARPin) that binds exclusively to protofilament-edge sites, and whose binding site partially overlaps with the EB1 binding site. We found that DARPin blocked EB1 protofilament-edge binding, which led to a decrease in EB1 tip tracking on dynamic microtubules. We conclude that rapid EB1 binding to microtubule protofilament-edge sites contributes to robust EB1 tip tracking at the growing microtubule plus-end.
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Affiliation(s)
- Samuel J Gonzalez
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Julia M Heckel
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Rebecca R Goldblum
- Department of Biophysics, Molecular Biology, and Biochemistry, University of Minnesota, Minneapolis, United States
- Medical Scientist Training Program, University of Minnesota, Minneapolis, United States
| | - Taylor A Reid
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Mark McClellan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Melissa K Gardner
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
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5
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Ori-McKenney KM, McKenney RJ. Tau oligomerization on microtubules in health and disease. Cytoskeleton (Hoboken) 2024; 81:35-40. [PMID: 37747123 PMCID: PMC10841430 DOI: 10.1002/cm.21785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/22/2023] [Accepted: 08/23/2023] [Indexed: 09/26/2023]
Affiliation(s)
- Kassandra M Ori-McKenney
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, California, USA
| | - Richard J McKenney
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, California, USA
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6
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Kim JY, Yang JE, Mitchell JW, English LA, Yang SZ, Tenpas T, Dent EW, Wildonger J, Wright ER. Handling Difficult Cryo-ET Samples: A Study with Primary Neurons from Drosophila melanogaster. Microsc Microanal 2023; 29:2127-2148. [PMID: 37966978 DOI: 10.1093/micmic/ozad125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/01/2023] [Accepted: 10/18/2023] [Indexed: 11/17/2023]
Abstract
Cellular neurobiology has benefited from recent advances in the field of cryo-electron tomography (cryo-ET). Numerous structural and ultrastructural insights have been obtained from plunge-frozen primary neurons cultured on electron microscopy grids. With most primary neurons having been derived from rodent sources, we sought to expand the breadth of sample availability by using primary neurons derived from 3rd instar Drosophila melanogaster larval brains. Ultrastructural abnormalities were encountered while establishing this model system for cryo-ET, which were exemplified by excessive membrane blebbing and cellular fragmentation. To optimize neuronal samples, we integrated substrate selection, micropatterning, montage data collection, and chemical fixation. Efforts to address difficulties in establishing Drosophila neurons for future cryo-ET studies in cellular neurobiology also provided insights that future practitioners can use when attempting to establish other cell-based model systems.
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Affiliation(s)
- Joseph Y Kim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jie E Yang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Josephine W Mitchell
- Department of Chemistry and Biochemistry, Kalamazoo College, Kalamazoo, MI 49006, USA
| | - Lauren A English
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Sihui Z Yang
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Tanner Tenpas
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Erik W Dent
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Jill Wildonger
- Departments of Pediatrics and Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Elizabeth R Wright
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI 53715, USA
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7
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Romeiro Motta M, Biswas S, Schaedel L. Beyond uniformity: Exploring the heterogeneous and dynamic nature of the microtubule lattice. Eur J Cell Biol 2023; 102:151370. [PMID: 37922811 DOI: 10.1016/j.ejcb.2023.151370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 10/17/2023] [Accepted: 10/26/2023] [Indexed: 11/07/2023] Open
Abstract
A fair amount of research on microtubules since their discovery in 1963 has focused on their dynamic tips. In contrast, the microtubule lattice was long believed to be highly regular and static, and consequently received far less attention. Yet, as it turned out, the microtubule lattice is neither as regular, nor as static as previously believed: structural studies uncovered the remarkable wealth of different conformations the lattice can accommodate. In the last decade, the microtubule lattice was shown to be labile and to spontaneously undergo renovation, a phenomenon that is intimately linked to structural defects and was called "microtubule self-repair". Following this breakthrough discovery, further recent research provided a deeper understanding of the lattice self-repair mechanism, which we review here. Instrumental to these discoveries were in vitro microtubule reconstitution assays, in which microtubules are grown from the minimal components required for their dynamics. In this review, we propose a shift from the term "lattice self-repair" to "lattice dynamics", since this phenomenon is an inherent property of microtubules and can happen without microtubule damage. We focus on how in vitro microtubule reconstitution assays helped us learn (1) which types of structural variations microtubules display, (2) how these structural variations influence lattice dynamics and microtubule damage caused by mechanical stress, (3) how lattice dynamics impact tip dynamics, and (4) how microtubule-associated proteins (MAPs) can play a role in structuring the lattice. Finally, we discuss the unanswered questions about lattice dynamics and how technical advances will help us tackle these questions.
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Affiliation(s)
- Mariana Romeiro Motta
- Department of Physics, Center for Biophysics, Campus A2 4, Saarland University, 66123 Saarbrücken, Germany; Laboratoire Reproduction et Développement des Plantes, Université de Lyon, École normale supérieure de Lyon, Lyon 69364, France
| | - Subham Biswas
- Department of Physics, Center for Biophysics, Campus A2 4, Saarland University, 66123 Saarbrücken, Germany
| | - Laura Schaedel
- Department of Physics, Center for Biophysics, Campus A2 4, Saarland University, 66123 Saarbrücken, Germany.
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8
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Kim JY, Yang JE, Mitchell JW, English LA, Yang SZ, Tenpas T, Dent EW, Wildonger J, Wright ER. Handling difficult cryo-ET samples: A study with primary neurons from Drosophila melanogaster. bioRxiv 2023:2023.07.10.548468. [PMID: 37502991 PMCID: PMC10369871 DOI: 10.1101/2023.07.10.548468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Cellular neurobiology has benefited from recent advances in the field of cryo-electron tomography (cryo-ET). Numerous structural and ultrastructural insights have been obtained from plunge-frozen primary neurons cultured on electron microscopy grids. With most primary neurons been derived from rodent sources, we sought to expand the breadth of sample availability by using primary neurons derived from 3rd instar Drosophila melanogaster larval brains. Ultrastructural abnormalities were encountered while establishing this model system for cryo-ET, which were exemplified by excessive membrane blebbing and cellular fragmentation. To optimize neuronal samples, we integrated substrate selection, micropatterning, montage data collection, and chemical fixation. Efforts to address difficulties in establishing Drosophila neurons for future cryo-ET studies in cellular neurobiology also provided insights that future practitioners can use when attempting to establish other cell-based model systems.
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Affiliation(s)
- Joseph Y. Kim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Jie E. Yang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Josephine W. Mitchell
- Department of Chemistry and Biochemistry, Kalamazoo College, Kalamazoo, MI, 49006, USA
| | - Lauren A. English
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Sihui Z. Yang
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Tanner Tenpas
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Erik W. Dent
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Jill Wildonger
- Departments of Pediatrics and Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Elizabeth R. Wright
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI, 53715, USA
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9
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Lawrence EJ, Chatterjee S, Zanic M. CLASPs stabilize the pre-catastrophe intermediate state between microtubule growth and shrinkage. J Cell Biol 2023; 222:e202107027. [PMID: 37184584 PMCID: PMC10195879 DOI: 10.1083/jcb.202107027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 12/03/2022] [Accepted: 04/18/2023] [Indexed: 05/16/2023] Open
Abstract
Cytoplasmic linker-associated proteins (CLASPs) regulate microtubules in fundamental cellular processes. CLASPs stabilize dynamic microtubules by suppressing microtubule catastrophe and promoting rescue, the switch-like transitions between growth and shrinkage. How CLASPs specifically modulate microtubule transitions is not understood. Here, we investigate the effects of CLASPs on the pre-catastrophe intermediate state of microtubule dynamics, employing distinct microtubule substrates to mimic the intermediate state. Surprisingly, we find that CLASP1 promotes the depolymerization of stabilized microtubules in the presence of GTP, but not in the absence of nucleotide. This activity is also observed for CLASP2 family members and a minimal TOG2-domain construct. Conversely, we find that CLASP1 stabilizes unstable microtubules upon tubulin dilution in the presence of GTP. Strikingly, our results reveal that CLASP1 drives microtubule substrates with vastly different inherent stabilities into the same slowly depolymerizing state in a nucleotide-dependent manner. We interpret this state as the pre-catastrophe intermediate state. Therefore, we conclude that CLASPs suppress microtubule catastrophe by stabilizing the intermediate state between growth and shrinkage.
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Affiliation(s)
- Elizabeth J. Lawrence
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Saptarshi Chatterjee
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN, USA
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, USA
- Department of Biochemistry, Vanderbilt University, Nashville, TN, USA
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10
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Abstract
Microtubules are critical for a variety of important functions in eukaryotic cells. During intracellular trafficking, molecular motor proteins of the kinesin superfamily drive the transport of cellular cargoes by stepping processively along the microtubule surface. Traditionally, the microtubule has been viewed as simply a track for kinesin motility. New work is challenging this classic view by showing that kinesin-1 and kinesin-4 proteins can induce conformational changes in tubulin subunits while they are stepping. These conformational changes appear to propagate along the microtubule such that the kinesins can work allosterically through the lattice to influence other proteins on the same track. Thus, the microtubule is a plastic medium through which motors and other microtubule-associated proteins (MAPs) can communicate. Furthermore, stepping kinesin-1 can damage the microtubule lattice. Damage can be repaired by the incorporation of new tubulin subunits, but too much damage leads to microtubule breakage and disassembly. Thus, the addition and loss of tubulin subunits are not restricted to the ends of the microtubule filament but rather, the lattice itself undergoes continuous repair and remodeling. This work leads to a new understanding of how kinesin motors and their microtubule tracks engage in allosteric interactions that are critical for normal cell physiology.
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Affiliation(s)
- Kristen J. Verhey
- Department of Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Author for correspondence ()
| | - Ryoma Ohi
- Department of Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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11
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Luchniak A, Kuo YW, McGuinness C, Sutradhar S, Orbach R, Mahamdeh M, Howard J. Dynamic microtubules slow down during their shrinkage phase. Biophys J 2023; 122:616-623. [PMID: 36659852 PMCID: PMC9989939 DOI: 10.1016/j.bpj.2023.01.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 11/25/2022] [Accepted: 01/17/2023] [Indexed: 01/21/2023] Open
Abstract
Microtubules are dynamic polymers that undergo stochastic transitions between growing and shrinking phases. The structural and chemical properties of these phases remain poorly understood. The transition from growth to shrinkage, termed catastrophe, is not a first-order reaction but rather a multistep process whose frequency increases with the growth time: the microtubule ages as the older microtubule tip becomes more unstable. Aging shows that the growing phase is not a single state but comprises several substates of increasing instability. To investigate whether the shrinking phase is also multistate, we characterized the kinetics of microtubule shrinkage following catastrophe using an in vitro reconstitution assay with purified tubulins. We found that the shrinkage speed is highly variable across microtubules and that the shrinkage speed of individual microtubules slows down over time by as much as several fold. The shrinkage slowdown was observed in both fluorescently labeled and unlabeled microtubules as well as in microtubules polymerized from tubulin purified from different species, suggesting that the shrinkage slowdown is a general property of microtubules. These results indicate that microtubule shrinkage, like catastrophe, is time dependent and that the shrinking microtubule tip passes through a succession of states of increasing stability. We hypothesize that the shrinkage slowdown is due to destabilizing events that took place during growth, which led to multistep catastrophe. This suggests that the aging associated with growth is also manifested during shrinkage, with the older, more unstable growing tip being associated with a faster depolymerizing shrinking tip.
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Affiliation(s)
- Anna Luchniak
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Yin-Wei Kuo
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Catherine McGuinness
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Sabyasachi Sutradhar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Ron Orbach
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Mohammed Mahamdeh
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut.
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12
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Gazzola M, Schaeffer A, Butler-Hallissey C, Friedl K, Vianay B, Gaillard J, Leterrier C, Blanchoin L, Théry M. Microtubules self-repair in living cells. Curr Biol 2023; 33:122-133.e4. [PMID: 36565699 DOI: 10.1016/j.cub.2022.11.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 09/21/2022] [Accepted: 11/24/2022] [Indexed: 12/24/2022]
Abstract
Microtubule self-repair has been studied both in vitro and in vivo as an underlying mechanism of microtubule stability. The turnover of tubulin dimers along the microtubule has challenged the pre-existing dogma that only growing ends are dynamic. However, although there is clear evidence of tubulin incorporation into the shaft of polymerized microtubules in vitro, the possibility of such events occurring in living cells remains uncertain. In this study, we investigated this possibility by microinjecting purified tubulin dimers labeled with a red fluorophore into the cytoplasm of cells expressing GFP-tubulin. We observed the appearance of red dots along the pre-existing green microtubule within minutes. We found that the fluorescence intensities of these red dots were inversely correlated with the green signal, suggesting that the red dimers were incorporated into the microtubules and replaced the pre-existing green dimers. Lateral distance from the microtubule center was similar to that in incorporation sites and in growing ends. The saturation of the size and spatial frequency of incorporations as a function of injected tubulin concentration and post-injection delay suggested that the injected dimers incorporated into a finite number of damaged sites. By our low estimate, within a few minutes of the injections, free dimers incorporated into major repair sites every 70 μm of microtubules. Finally, we mapped the location of these sites in micropatterned cells and found that they were more concentrated in regions where the actin filament network was less dense and where microtubules exhibited greater lateral fluctuations.
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Affiliation(s)
- Morgan Gazzola
- University of Paris, INSERM, CEA, UMRS1160, Institut de Recherche Saint Louis, CytoMorpho Lab, Hôpital Saint Louis, 10 Avenue Claude Vellefaux, 75010 Paris, France
| | - Alexandre Schaeffer
- University of Paris, INSERM, CEA, UMRS1160, Institut de Recherche Saint Louis, CytoMorpho Lab, Hôpital Saint Louis, 10 Avenue Claude Vellefaux, 75010 Paris, France
| | - Ciarán Butler-Hallissey
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto Lab, 27 Boulevard Jean Moulin, 13385 Marseille, France
| | - Karoline Friedl
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto Lab, 27 Boulevard Jean Moulin, 13385 Marseille, France; Abbelight, 191 Avenue Aristide Briand, 94230 Cachan, France
| | - Benoit Vianay
- University of Paris, INSERM, CEA, UMRS1160, Institut de Recherche Saint Louis, CytoMorpho Lab, Hôpital Saint Louis, 10 Avenue Claude Vellefaux, 75010 Paris, France
| | - Jérémie Gaillard
- University of Grenoble-Alpes, CEA, CNRS, UMR5168, Interdisciplinary Research Institute of Grenoble, CytoMorpho Lab, 17 rue des Martyrs, 38054 Grenoble, France
| | - Christophe Leterrier
- Aix Marseille Université, CNRS, INP UMR7051, NeuroCyto Lab, 27 Boulevard Jean Moulin, 13385 Marseille, France
| | - Laurent Blanchoin
- University of Grenoble-Alpes, CEA, CNRS, UMR5168, Interdisciplinary Research Institute of Grenoble, CytoMorpho Lab, 17 rue des Martyrs, 38054 Grenoble, France.
| | - Manuel Théry
- University of Paris, INSERM, CEA, UMRS1160, Institut de Recherche Saint Louis, CytoMorpho Lab, Hôpital Saint Louis, 10 Avenue Claude Vellefaux, 75010 Paris, France.
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13
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Farmer VJ, Zanic M. Beyond the GTP-cap: Elucidating the molecular mechanisms of microtubule catastrophe. Bioessays 2023; 45:e2200081. [PMID: 36398561 PMCID: PMC10648283 DOI: 10.1002/bies.202200081] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 11/03/2022] [Accepted: 11/04/2022] [Indexed: 11/19/2022]
Abstract
Almost 40 years since the discovery of microtubule dynamic instability, the molecular mechanisms underlying microtubule dynamics remain an area of intense research interest. The "standard model" of microtubule dynamics implicates a "cap" of GTP-bound tubulin dimers at the growing microtubule end as the main determinant of microtubule stability. Loss of the GTP-cap leads to microtubule "catastrophe," a switch-like transition from microtubule growth to shrinkage. However, recent studies, using biochemical in vitro reconstitution, cryo-EM, and computational modeling approaches, challenge the simple GTP-cap model. Instead, a new perspective on the mechanisms of microtubule dynamics is emerging. In this view, highly dynamic transitions between different structural conformations of the growing microtubule end - which may or may not be directly linked to the nucleotide content at the microtubule end - ultimately drive microtubule catastrophe.
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Affiliation(s)
- Veronica J. Farmer
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Biomolecular and Chemical Engineering, Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA
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14
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Tsuji C, Dodding MP. Lumenal components of cytoplasmic microtubules. Biochem Soc Trans 2022; 50:1953-1962. [PMID: 36524962 DOI: 10.1042/bst20220851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 11/30/2022] [Accepted: 12/01/2022] [Indexed: 07/30/2023]
Abstract
The lumen of cytoplasmic microtubules is a poorly explored expanse of intracellular space. Although typically represented in textbooks as a hollow tube, studies over several decades have shown that the microtubule lumen is occupied by a range of morphologically diverse components. These are predominantly globular particles of varying sizes which appear to exist either in isolation, bind to the microtubule wall, or form discontinuous columns that extend through the lumenal space. Actin filaments with morphologies distinct from the canonical cytoplasmic forms have also now been found within the microtubule lumen. In this review, we examine the historic literature that observed these lumenal components in tissues from diverse species and integrate it with recent cryo-electron tomography studies that have begun to identify lumenal proteins. We consider their cell and tissue distribution, possible mechanisms of incorporation, and potential functions. It is likely that continuing work in this area will open a new frontier in cytoskeletal biology.
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Affiliation(s)
- Chisato Tsuji
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, U.K
| | - Mark P Dodding
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol BS8 1TD, U.K
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15
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Abstract
Neurons are highly polarized cells with elaborate shapes that allow them to perform their function. In neurons, microtubule organization—length, density, and dynamics—are essential for the establishment of polarity, growth, and transport. A mounting body of evidence shows that modulation of the microtubule cytoskeleton by microtubule-associated proteins fine tunes key aspects of neuronal cell biology. In this respect, microtubule severing enzymes—spastin, katanin and fidgetin—a group of microtubule-associated proteins that bind to and generate internal breaks in the microtubule lattice, are emerging as key modulators of the microtubule cytoskeleton in different model systems. In this review, we provide an integrative view on the latest research demonstrating the key role of spastin in neurons, specifically in the context of axonal cell biology. We focus on the function of spastin in the regulation of microtubule organization, and axonal transport, that underlie its importance in the intricate control of axon growth, branching and regeneration.
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Affiliation(s)
- Ana Catarina Costa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação Em Saúde (i3S), University of Porto, Porto, Portugal
- Graduate Program in Molecular and Cell Biology, Instituto de Ciências Biomédicas Abel Salazar (ICBAS), University of Porto, Porto, Portugal
- *Correspondence: Ana Catarina Costa, ; Monica Mendes Sousa,
| | - Monica Mendes Sousa
- Nerve Regeneration Group, Instituto de Biologia Molecular e Celular (IBMC), Instituto de Investigação e Inovação Em Saúde (i3S), University of Porto, Porto, Portugal
- *Correspondence: Ana Catarina Costa, ; Monica Mendes Sousa,
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16
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Budaitis BG, Badieyan S, Yue Y, Blasius TL, Reinemann DN, Lang MJ, Cianfrocco MA, Verhey KJ. A kinesin-1 variant reveals motor-induced microtubule damage in cells. Curr Biol 2022; 32:2416-2429.e6. [PMID: 35504282 PMCID: PMC9993403 DOI: 10.1016/j.cub.2022.04.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 03/11/2022] [Accepted: 04/08/2022] [Indexed: 12/16/2022]
Abstract
Kinesins drive the transport of cellular cargoes as they walk along microtubule tracks; however, recent work has suggested that the physical act of kinesins walking along microtubules can stress the microtubule lattice. Here, we describe a kinesin-1 KIF5C mutant with an increased ability to generate damage sites in the microtubule lattice as compared with the wild-type motor. The expression of the mutant motor in cultured cells resulted in microtubule breakage and fragmentation, suggesting that kinesin-1 variants with increased damage activity would have been selected against during evolution. The increased ability to damage microtubules is not due to the enhanced motility properties of the mutant motor, as the expression of the kinesin-3 motor KIF1A, which has similar single-motor motility properties, also caused increased microtubule pausing, bending, and buckling but not breakage. In cells, motor-induced microtubule breakage could not be prevented by increased α-tubulin K40 acetylation, a post-translational modification known to increase microtubule flexibility. In vitro, lattice damage induced by wild-type KIF5C was repaired by soluble tubulin and resulted in increased rescues and overall microtubule growth, whereas lattice damage induced by the KIF5C mutant resulted in larger repair sites that made the microtubule vulnerable to breakage and fragmentation when under mechanical stress. These results demonstrate that kinesin-1 motility causes defects in and damage to the microtubule lattice in cells. While cells have the capacity to repair lattice damage, conditions that exceed this capacity result in microtubule breakage and fragmentation and may contribute to human disease.
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Affiliation(s)
- Breane G Budaitis
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA; Department of Cell & Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Somayesadat Badieyan
- Department of Biological Chemistry and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yang Yue
- Department of Cell & Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - T Lynne Blasius
- Department of Cell & Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Dana N Reinemann
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37240, USA
| | - Matthew J Lang
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37240, USA
| | - Michael A Cianfrocco
- Department of Biological Chemistry and Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kristen J Verhey
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI 48109, USA; Department of Cell & Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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17
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Atherton J, Stouffer M, Francis F, Moores CA. Visualising the cytoskeletal machinery in neuronal growth cones using cryo-electron tomography. J Cell Sci 2022; 135:274968. [PMID: 35383828 PMCID: PMC9016625 DOI: 10.1242/jcs.259234] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Accepted: 03/02/2022] [Indexed: 12/12/2022] Open
Abstract
Neurons extend axons to form the complex circuitry of the mature brain. This depends on the coordinated response and continuous remodelling of the microtubule and F-actin networks in the axonal growth cone. Growth cone architecture remains poorly understood at nanoscales. We therefore investigated mouse hippocampal neuron growth cones using cryo-electron tomography to directly visualise their three-dimensional subcellular architecture with molecular detail. Our data showed that the hexagonal arrays of actin bundles that form filopodia penetrate and terminate deep within the growth cone interior. We directly observed the modulation of these and other growth cone actin bundles by alteration of individual F-actin helical structures. Microtubules with blunt, slightly flared or gently curved ends predominated in the growth cone, frequently contained lumenal particles and exhibited lattice defects. Investigation of the effect of absence of doublecortin, a neurodevelopmental cytoskeleton regulator, on growth cone cytoskeleton showed no major anomalies in overall growth cone organisation or in F-actin subpopulations. However, our data suggested that microtubules sustained more structural defects, highlighting the importance of microtubule integrity during growth cone migration. Summary: Cryo-electron tomographic reconstruction of neuronal growth cone subdomains reveals distinctive F-actin and microtubule cytoskeleton architectures and modulation at molecular detail.
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Affiliation(s)
- Joseph Atherton
- Randall Centre for Cell and Molecular Biophysics, King's College, London SE1 1YR, UK.,Institute of Structural and Molecular Biology, Birkbeck, University of London, London WC1E 7HX, UK
| | - Melissa Stouffer
- INSERM UMR-S 1270, 17 Rue du Fer à Moulin, 75005 Paris, France.,Sorbonne University UMR-S 1270, 4 Place Jussieu, 75005 Paris, France.,Institut du Fer à Moulin, 17 Rue du Fer à Moulin, 75005 Paris, France.,Institute of Science and Technology Austria, Am campus 1, 3400 Klosterneuberg, Austria
| | - Fiona Francis
- INSERM UMR-S 1270, 17 Rue du Fer à Moulin, 75005 Paris, France.,Sorbonne University UMR-S 1270, 4 Place Jussieu, 75005 Paris, France.,Institut du Fer à Moulin, 17 Rue du Fer à Moulin, 75005 Paris, France
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Birkbeck, University of London, London WC1E 7HX, UK
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18
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Abstract
The mechanochemical basis of microtubule growth, which is essential for the normal function and division of eukaryotic cells, has remained elusive and controversial, despite extensive work. In particular, recent findings have created the paradox that the microtubule plus-end tips look very similar during both growing and shrinking phases, thereby challenging the traditional textbook picture. Our large-scale atomistic simulations resolve this paradox and explain microtubule growth and shrinkage dynamics as a process governed by energy barriers between protofilament conformations, the heights of which are in turn fine-tuned by different nucleotide states, thus implementing an information-driven Brownian ratchet. Microtubules (MTs), mesoscopic cellular filaments, grow primarily by the addition of GTP-bound tubulin dimers at their dynamic flaring plus-end tips. They operate as chemomechanical energy transducers with stochastic transitions to an astounding shortening motion upon hydrolyzing GTP to GDP. Time-resolved dynamics of the MT tip—a key determinant of this behavior—as a function of nucleotide state, internal lattice strain, and stabilizing lateral interactions have not been fully understood. Here we use atomistic simulations to study the spontaneous relaxation of complete GTP-MT and GDP-MT tip models from unfavorable straight to relaxed splayed conformations and to comprehensively characterize the elasticity of MT tips. Our simulations reveal the dominance of viscoelastic dynamics of MT protofilaments during the relaxation process, driven by the stored bending-torsional strain and counterbalanced by the interprotofilament interactions. We show that the posthydrolysis MT tip is exposed to higher activation energy barriers for straight lattice formation, which translates into its inability to elongate. Our study provides an information-driven Brownian ratchet mechanism for the elastic energy conversion and release by MT tips and offers insights into the mechanoenzymatics of MTs.
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19
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Alkemade C, Wierenga H, Volkov VA, Preciado López M, Akhmanova A, Ten Wolde PR, Dogterom M, Koenderink GH. Cross-linkers at growing microtubule ends generate forces that drive actin transport. Proc Natl Acad Sci U S A 2022; 119:e2112799119. [PMID: 35271394 DOI: 10.1073/pnas.2112799119] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Complex cellular processes such as cell migration require coordinated remodeling of both the actin and the microtubule cytoskeleton. The two networks for instance exert forces on each other via active motor proteins. Here we show that, surprisingly, coupling via passive cross-linkers can also result in force generation. We specifically study the transport of actin filaments by growing microtubule ends. We show by cell-free reconstitution experiments, computer simulations, and theoretical modeling that this transport is driven by the affinity of the cross-linker for the chemically distinct microtubule tip region. Our work predicts that growing microtubules could potentially rapidly relocate newly nucleated actin filaments to the leading edge of the cell and thus boost migration. The actin and microtubule cytoskeletons form active networks in the cell that can contract and remodel, resulting in vital cellular processes such as cell division and motility. Motor proteins play an important role in generating the forces required for these processes, but more recently the concept of passive cross-linkers being able to generate forces has emerged. So far, these passive cross-linkers have been studied in the context of separate actin and microtubule systems. Here, we show that cross-linkers also allow actin and microtubules to exert forces on each other. More specifically, we study single actin filaments that are cross-linked to growing microtubule ends, using in vitro reconstitution, computer simulations, and a minimal theoretical model. We show that microtubules can transport actin filaments over large (micrometer-range) distances and find that this transport results from two antagonistic forces arising from the binding of cross-linkers to the overlap between the actin and microtubule filaments. The cross-linkers attempt to maximize the overlap between the actin and the tip of the growing microtubules, creating an affinity-driven forward condensation force, and simultaneously create a competing friction force along the microtubule lattice. We predict and verify experimentally how the average transport time depends on the actin filament length and the microtubule growth velocity, confirming the competition between a forward condensation force and a backward friction force. In addition, we theoretically predict and experimentally verify that the condensation force is of the order of 0.1 pN. Thus, our results reveal an active mechanism for local actin remodeling by growing microtubules that relies on passive cross-linkers.
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20
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Foster HE, Ventura Santos C, Carter AP. A cryo-ET survey of microtubules and intracellular compartments in mammalian axons. J Cell Biol 2022; 221:e202103154. [PMID: 34878519 PMCID: PMC7612188 DOI: 10.1083/jcb.202103154] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 09/28/2021] [Accepted: 11/16/2021] [Indexed: 12/16/2022] Open
Abstract
The neuronal axon is packed with cytoskeletal filaments, membranes, and organelles, many of which move between the cell body and axon tip. Here, we used cryo-electron tomography to survey the internal components of mammalian sensory axons. We determined the polarity of the axonal microtubules (MTs) by combining subtomogram classification and visual inspection, finding MT plus and minus ends are structurally similar. Subtomogram averaging of globular densities in the MT lumen suggests they have a defined structure, which is surprising given they likely contain the disordered protein MAP6. We found the endoplasmic reticulum in axons is tethered to MTs through multiple short linkers. We surveyed membrane-bound cargos and describe unexpected internal features such as granules and broken membranes. In addition, we detected proteinaceous compartments, including numerous virus-like capsid particles. Our observations outline novel features of axonal cargos and MTs, providing a platform for identification of their constituents.
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21
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Garnett JA, Atherton J. Structure Determination of Microtubules and Pili: Past, Present, and Future Directions. Front Mol Biosci 2022; 8:830304. [PMID: 35096976 PMCID: PMC8795688 DOI: 10.3389/fmolb.2021.830304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 12/28/2021] [Indexed: 11/30/2022] Open
Abstract
Historically proteins that form highly polymeric and filamentous assemblies have been notoriously difficult to study using high resolution structural techniques. This has been due to several factors that include structural heterogeneity, their large molecular mass, and available yields. However, over the past decade we are now seeing a major shift towards atomic resolution insight and the study of more complex heterogenous samples and in situ/ex vivo examination of multi-subunit complexes. Although supported by developments in solid state nuclear magnetic resonance spectroscopy (ssNMR) and computational approaches, this has primarily been due to advances in cryogenic electron microscopy (cryo-EM). The study of eukaryotic microtubules and bacterial pili are good examples, and in this review, we will give an overview of the technical innovations that have enabled this transition and highlight the advancements that have been made for these two systems. Looking to the future we will also describe systems that remain difficult to study and where further technical breakthroughs are required.
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Affiliation(s)
- James A. Garnett
- Centre for Host-Microbiome Interactions, Faculty of Dental, Oral and Craniofacial Sciences, King’s College London, London, United Kingdom
| | - Joseph Atherton
- Randall Centre for Cell and Molecular Biophysics, King’s College London, London, United Kingdom
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22
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Gory-Fauré S, Delaroche J, Cuveillier C, Delphin C, Arnal I. Cryo-EM Visualization of Neuronal Particles Inside Microtubules. Methods Mol Biol 2022; 2430:375-383. [PMID: 35476345 DOI: 10.1007/978-1-0716-1983-4_24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Neuronal microtubules have long been known to contain intraluminal particles, called MIPs (microtubule inner proteins), most likely involved in the extreme stability of microtubules in neurons. This chapter describes a cryo-electron microscopy-based assay to visualize microtubules containing neuronal MIPs. We present two protocols to prepare MIPs-containing microtubules, using either in vitro microtubule polymerization assays or extraction of microtubules from mouse hippocampal neurons in culture.
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Affiliation(s)
- Sylvie Gory-Fauré
- Univ. Grenoble Alpes, Inserm U1216, CNRS, Grenoble Institut Neurosciences, Grenoble, France
| | - Julie Delaroche
- Univ. Grenoble Alpes, Inserm U1216, CNRS, Grenoble Institut Neurosciences, Grenoble, France
| | - Camille Cuveillier
- Univ. Grenoble Alpes, Inserm U1216, CNRS, Grenoble Institut Neurosciences, Grenoble, France
| | - Christian Delphin
- Univ. Grenoble Alpes, Inserm U1216, CNRS, Grenoble Institut Neurosciences, Grenoble, France
| | - Isabelle Arnal
- Univ. Grenoble Alpes, Inserm U1216, CNRS, Grenoble Institut Neurosciences, Grenoble, France.
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23
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Rai A, Liu T, Katrukha EA, Estévez-Gallego J, Manka SW, Paterson I, Díaz JF, Kapitein LC, Moores CA, Akhmanova A. Lattice defects induced by microtubule-stabilizing agents exert a long-range effect on microtubule growth by promoting catastrophes. Proc Natl Acad Sci U S A 2021; 118:e2112261118. [PMID: 34916292 DOI: 10.1073/pnas.2112261118] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/02/2021] [Indexed: 11/18/2022] Open
Abstract
Microtubules are major cytoskeletal filaments important for cell division, growth, and differentiation. Microtubules can rapidly switch between phases of growth and shortening, and this dynamic behavior is essential for shaping microtubule arrays. To obtain insights into mechanisms controlling microtubule dynamics, here we used microtubule-stabilizing agents such as Taxol and their fluorescent analogs to manipulate microtubule protofilament number and generate stable defects in microtubule lattices that can be visualized using fluorescence microscopy. We show that microtubule polymerization rate increases with protofilament number and that drug-induced microtubule lattice discontinuities can promote plus-end catastrophes at a distance of several micrometers. Our data indicate that structural defects in the microtubule wall can have long-range propagating effects on microtubule tip dynamics. Microtubules are dynamic cytoskeletal polymers that spontaneously switch between phases of growth and shrinkage. The probability of transitioning from growth to shrinkage, termed catastrophe, increases with microtubule age, but the underlying mechanisms are poorly understood. Here, we set out to test whether microtubule lattice defects formed during polymerization can affect growth at the plus end. To generate microtubules with lattice defects, we used microtubule-stabilizing agents that promote formation of polymers with different protofilament numbers. By employing different agents during nucleation of stable microtubule seeds and the subsequent polymerization phase, we could reproducibly induce switches in protofilament number and induce stable lattice defects. Such drug-induced defects led to frequent catastrophes, which were not observed when microtubules were grown in the same conditions but without a protofilament number mismatch. Microtubule severing at the site of the defect was sufficient to suppress catastrophes. We conclude that structural defects within the microtubule lattice can exert effects that can propagate over long distances and affect the dynamic state of the microtubule end.
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24
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Bujak Ł, Holanová K, García Marín A, Henrichs V, Barvík I, Braun M, Lánský Z, Piliarik M. Fast Leaps between Millisecond Confinements Govern Ase1 Diffusion along Microtubules. Small Methods 2021; 5:e2100370. [PMID: 34927934 DOI: 10.1002/smtd.202100370] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/24/2021] [Indexed: 06/14/2023]
Abstract
Diffusion is the most fundamental mode of protein translocation within cells. Confined diffusion of proteins along the electrostatic potential constituted by the surface of microtubules, although modeled meticulously in molecular dynamics simulations, has not been experimentally observed in real-time. Here, interferometric scattering microscopy is used to directly visualize the movement of the microtubule-associated protein Ase1 along the microtubule surface at nanometer and microsecond resolution. Millisecond confinements of Ase1 and fast leaps between these positions of dwelling preferentially occurring along the microtubule protofilaments are resolved, revealing Ase1's mode of diffusive translocation along the microtubule's periodic surface. The derived interaction potential closely matches the tubulin-dimer periodicity and the distribution of the electrostatic potential on the microtubule lattice. It is anticipated that mapping the interaction landscapes for different proteins on microtubules, finding plausible energetic barriers of different positioning and heights, can provide valuable insights into regulating the dynamics of essential cytoskeletal processes, such as intracellular cargo trafficking, cell division, and morphogenesis, all of which rely on diffusive translocation of proteins along microtubules.
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Affiliation(s)
- Łukasz Bujak
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 18251, Czech Republic
| | - Kristýna Holanová
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 18251, Czech Republic
| | - Antonio García Marín
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 18251, Czech Republic
| | - Verena Henrichs
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 25250, Czech Republic
| | - Ivan Barvík
- Faculty of Mathematics and Physics, Institute of Physics, Charles University, Ke Karlovu 2026/5, Prague, 12116, Czech Republic
| | - Marcus Braun
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 25250, Czech Republic
| | - Zdeněk Lánský
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 25250, Czech Republic
| | - Marek Piliarik
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 18251, Czech Republic
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25
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Gudimchuk NB, McIntosh JR. Regulation of microtubule dynamics, mechanics and function through the growing tip. Nat Rev Mol Cell Biol 2021. [PMID: 34408299 DOI: 10.1038/s41580-021-00399-x] [Citation(s) in RCA: 77] [Impact Index Per Article: 25.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/05/2021] [Indexed: 02/07/2023]
Abstract
Microtubule dynamics and their control are essential for the normal function and division of all eukaryotic cells. This plethora of functions is, in large part, supported by dynamic microtubule tips, which can bind to various intracellular targets, generate mechanical forces and couple with actin microfilaments. Here, we review progress in the understanding of microtubule assembly and dynamics, focusing on new information about the structure of microtubule tips. First, we discuss evidence for the widely accepted GTP cap model of microtubule dynamics. Next, we address microtubule dynamic instability in the context of structural information about assembly intermediates at microtubule tips. Three currently discussed models of microtubule assembly and dynamics are reviewed. These are considered in the context of established facts and recent data, which suggest that some long-held views must be re-evaluated. Finally, we review structural observations about the tips of microtubules in cells and describe their implications for understanding the mechanisms of microtubule regulation by associated proteins, by mechanical forces and by microtubule-targeting drugs, prominently including cancer chemotherapeutics.
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26
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Nihongaki Y, Matsubayashi HT, Inoue T. A molecular trap inside microtubules probes luminal access by soluble proteins. Nat Chem Biol 2021; 17:888-895. [PMID: 33941924 PMCID: PMC8319117 DOI: 10.1038/s41589-021-00791-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 03/30/2021] [Indexed: 02/02/2023]
Abstract
The uniquely hollow structure of microtubules (MTs) confers characteristic mechanical and biological properties. Although most regulatory processes take place at the outer surface, molecular events inside MTs, such as α-tubulin acetylation, also play a critical role. However, how regulatory proteins reach the site of action remains obscure. To assess luminal accessibility, we first identified luminally positioned residues of β-tubulin that can be fused to a protein of interest. We then developed a chemically inducible technique with which cytosolic proteins can be rapidly trapped at the lumen of intact MTs in cells. A luminal trapping assay revealed that soluble proteins of moderate size can enter the lumen via diffusion through openings at the MT ends and sides. Additionally, proteins forming a complex with tubulins can be incorporated to the lumen through the plus ends. Our approach may not only illuminate this understudied territory, but may also help understand its roles in MT-mediated functions.
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Affiliation(s)
- Yuta Nihongaki
- Department of Cell Biology and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,To whom correspondence should be addressed. ,
| | - Hideaki T. Matsubayashi
- Department of Cell Biology and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Takanari Inoue
- Department of Cell Biology and Center for Cell Dynamics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA,To whom correspondence should be addressed. ,
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27
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Farmer V, Arpağ G, Hall SL, Zanic M. XMAP215 promotes microtubule catastrophe by disrupting the growing microtubule end. J Cell Biol 2021; 220:212518. [PMID: 34324632 PMCID: PMC8327381 DOI: 10.1083/jcb.202012144] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 05/11/2021] [Accepted: 07/08/2021] [Indexed: 01/13/2023] Open
Abstract
The GTP-tubulin cap is widely accepted to protect microtubules against catastrophe. The GTP-cap size is thought to increase with the microtubule growth rate, presumably endowing fast-growing microtubules with enhanced stability. It is unknown what GTP-cap properties permit frequent microtubule catastrophe despite fast growth. Here, we investigate microtubules growing in the presence and absence of the polymerase XMAP215. Using EB1 as a GTP-cap marker, we find that GTP-cap size increases regardless of whether growth acceleration is achieved by increasing tubulin concentration or by XMAP215. Despite increased mean GTP-cap size, microtubules grown with XMAP215 display increased catastrophe frequency, in contrast to microtubules grown with more tubulin, for which catastrophe is abolished. However, microtubules polymerized with XMAP215 have large fluctuations in growth rate; display tapered and curled ends; and undergo catastrophe at faster growth rates and with higher EB1 end-localization. Our results suggest that structural perturbations induced by XMAP215 override the protective effects of the GTP-cap, ultimately driving microtubule catastrophe.
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Affiliation(s)
- Veronica Farmer
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Göker Arpağ
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Sarah L Hall
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN.,Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN.,Department of Biochemistry, Vanderbilt University, Nashville, TN
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28
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Mani N, Wijeratne SS, Subramanian R. Micron-scale geometrical features of microtubules as regulators of microtubule organization. eLife 2021; 10:e63880. [PMID: 34114950 PMCID: PMC8195601 DOI: 10.7554/elife.63880] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 06/02/2021] [Indexed: 12/20/2022] Open
Abstract
The organization of micron-sized, multi-microtubule arrays from individual microtubules is essential for diverse cellular functions. The microtubule polymer is largely viewed as a passive building block during the organization process. An exception is the 'tubulin code' where alterations to tubulin at the amino acid level can influence the activity of microtubule-associated proteins. Recent studies reveal that micron-scale geometrical features of individual microtubules and polymer networks, such as microtubule length, overlap length, contact angle, and lattice defects, can also regulate the activity of microtubule-associated proteins and modulate polymer dynamics. We discuss how the interplay between such geometrical properties of the microtubule lattice and the activity of associated proteins direct multiple aspects of array organization, from microtubule nucleation and coalignment to specification of array dimensions and remodeling of dynamic networks. The mechanisms reviewed here highlight micron-sized features of microtubules as critical parameters to be routinely investigated in the study of microtubule self-organization.
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Affiliation(s)
- Nandini Mani
- Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Department of Genetics, Harvard Medical SchoolBostonUnited States
| | - Sithara S Wijeratne
- Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Department of Genetics, Harvard Medical SchoolBostonUnited States
| | - Radhika Subramanian
- Department of Molecular Biology, Massachusetts General HospitalBostonUnited States
- Department of Genetics, Harvard Medical SchoolBostonUnited States
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29
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Abstract
Microtubules are dynamic cytoskeletal filaments composed of αβ-tubulin heterodimers. Historically, the dynamics of single tubulin interactions at the growing microtubule tip have been inferred from steady-state growth kinetics. However, recent advances in the production of recombinant tubulin and in high-resolution optical and cryo-electron microscopies have opened new windows into understanding the impacts of specific intermolecular interactions during growth. The microtubule lattice is held together by lateral and longitudinal tubulin-tubulin interactions, and these interactions are in turn regulated by the GTP hydrolysis state of the tubulin heterodimer. Furthermore, tubulin can exist in either an extended or a compacted state in the lattice. Growing evidence has led to the suggestion that binding of microtubule-associated proteins (MAPs) or motors can induce changes in tubulin conformation and that this information can be communicated through the microtubule lattice. Progress in understanding how dynamic tubulin-tubulin interactions control dynamic instability has benefitted from visualizing structures of growing microtubule plus ends and through stochastic biochemical models constrained by experimental data. Here, we review recent insights into the molecular basis of microtubule growth and discuss how MAPs and regulatory proteins alter tubulin-tubulin interactions to exert their effects on microtubule growth and stability.
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Affiliation(s)
- Joseph M Cleary
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA
| | - William O Hancock
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA 16802, USA.
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30
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Wilson JO, Zaragoza AD, Xu J. Tuning ensemble-averaged cargo run length via fractional change in mean kinesin number. Phys Biol 2021; 18. [PMID: 33827070 DOI: 10.1088/1478-3975/abf5b3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 04/07/2021] [Indexed: 11/12/2022]
Abstract
The number of motors carrying cargos in biological cells is not well-defined, instead varying from cargo to cargo about a statistical mean. Predictive understanding of motility in cells therefore requires quantitative insights into mixed ensembles of cargos. Toward this goal, here we employed Monte Carlo simulations to investigate statistical ensembles of cargos carried by a Poisson-distributed number of motors. Focusing on the key microtubule-based motor kinesin-1, our simulations utilized experimentally determined single-kinesin characteristics and alterations in kinesin's on- and off-rates caused by cellular factors and/or physical load. We found that a fractional increase in mean kinesin number enhances the ensemble-averaged cargo run length and amplifies run-length sensitivity to changes in single-kinesin on-rate and off-rate. These tuning effects can be further enhanced as solution viscosity increases over the range reported for cells. Together, our data indicate that the physiological range of kinesin number sensitively tunes the motility of mixed cargo populations. These effects have rich implications for quantitative and predictive understanding of cellular motility and its regulation.
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Affiliation(s)
- John O Wilson
- Physics, University of California, Merced, CA, United States of America
| | - Arturo D Zaragoza
- Mechanical Engineering, University of California, Merced, CA, United States of America
| | - Jing Xu
- Physics, University of California, Merced, CA, United States of America
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31
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Cuveillier C, Boulan B, Ravanello C, Denarier E, Deloulme JC, Gory-Fauré S, Delphin C, Bosc C, Arnal I, Andrieux A. Beyond Neuronal Microtubule Stabilization: MAP6 and CRMPS, Two Converging Stories. Front Mol Neurosci 2021; 14:665693. [PMID: 34025352 PMCID: PMC8131560 DOI: 10.3389/fnmol.2021.665693] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 04/09/2021] [Indexed: 12/21/2022] Open
Abstract
The development and function of the central nervous system rely on the microtubule (MT) and actin cytoskeletons and their respective effectors. Although the structural role of the cytoskeleton has long been acknowledged in neuronal morphology and activity, it was recently recognized to play the role of a signaling platform. Following this recognition, research into Microtubule Associated Proteins (MAPs) diversified. Indeed, historically, structural MAPs—including MAP1B, MAP2, Tau, and MAP6 (also known as STOP);—were identified and described as MT-binding and -stabilizing proteins. Extensive data obtained over the last 20 years indicated that these structural MAPs could also contribute to a variety of other molecular roles. Among multi-role MAPs, MAP6 provides a striking example illustrating the diverse molecular and cellular properties of MAPs and showing how their functional versatility contributes to the central nervous system. In this review, in addition to MAP6’s effect on microtubules, we describe its impact on the actin cytoskeleton, on neuroreceptor homeostasis, and its involvement in signaling pathways governing neuron development and maturation. We also discuss its roles in synaptic plasticity, brain connectivity, and cognitive abilities, as well as the potential relationships between the integrated brain functions of MAP6 and its molecular activities. In parallel, the Collapsin Response Mediator Proteins (CRMPs) are presented as examples of how other proteins, not initially identified as MAPs, fall into the broader MAP family. These proteins bind MTs as well as exhibiting molecular and cellular properties very similar to MAP6. Finally, we briefly summarize the multiple similarities between other classical structural MAPs and MAP6 or CRMPs.In summary, this review revisits the molecular properties and the cellular and neuronal roles of the classical MAPs, broadening our definition of what constitutes a MAP.
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Vala M, Bujak Ł, García Marín A, Holanová K, Henrichs V, Braun M, Lánský Z, Piliarik M. Nanoscopic Structural Fluctuations of Disassembling Microtubules Revealed by Label-Free Super-Resolution Microscopy. Small Methods 2021; 5:e2000985. [PMID: 34927839 DOI: 10.1002/smtd.202000985] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/22/2020] [Indexed: 06/14/2023]
Abstract
Microtubules are cytoskeletal polymers of tubulin dimers assembled into protofilaments that constitute nanotubes undergoing periods of assembly and disassembly. Static electron micrographs suggest a structural transition of straight protofilaments into curved ones occurring at the tips of disassembling microtubules. However, these structural transitions have never been observed and the process of microtubule disassembly thus remains unclear. Here, label-free optical microscopy capable of selective imaging of the transient structural changes of protofilaments at the tip of a disassembling microtubule is introduced. Upon induced disassembly, the transition of ordered protofilaments into a disordered conformation is resolved at the tip of the microtubule. Imaging the unbinding of individual tubulin oligomers from the microtubule tip reveals transient pauses and relapses in the disassembly, concurrent with increased organization of protofilament segments at the microtubule tip. These findings show that microtubule disassembly is a discrete process and suggest a stochastic mechanism of switching from the disassembly to the assembly phase.
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Affiliation(s)
- Milan Vala
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 182 51, Czech Republic
| | - Łukasz Bujak
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 182 51, Czech Republic
| | - Antonio García Marín
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 182 51, Czech Republic
| | - Kristýna Holanová
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 182 51, Czech Republic
| | - Verena Henrichs
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 252 50, Czech Republic
| | - Marcus Braun
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 252 50, Czech Republic
| | - Zdeněk Lánský
- Institute of Biotechnology of the Czech Academy of Sciences, BIOCEV, Průmyslová 595, Vestec, 252 50, Czech Republic
| | - Marek Piliarik
- Institute of Photonics and Electronics of the Czech Academy of Sciences, Chaberská 1014/57, Prague, 182 51, Czech Republic
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33
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Ulyanov EV, Vinogradov DS, McIntosh JR, Gudimchuk NB. Brownian dynamics simulation of protofilament relaxation during rapid freezing. PLoS One 2021; 16:e0247022. [PMID: 33577570 PMCID: PMC7880439 DOI: 10.1371/journal.pone.0247022] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 01/31/2021] [Indexed: 11/18/2022] Open
Abstract
Electron cryo-microscopy (Cryo-EM) is a powerful method for visualizing biological objects with up to near-angstrom resolution. Instead of chemical fixation, the method relies on very rapid freezing to immobilize the sample. Under these conditions, crystalline ice does not have time to form and distort structure. For many practical applications, the rate of cooling is fast enough to consider sample immobilization instantaneous, but in some cases, a more rigorous analysis of structure relaxation during freezing could be essential. This difficult yet important problem has been significantly under-reported in the literature, despite spectacular recent developments in Cryo-EM. Here we use Brownian dynamics modeling to examine theoretically the possible effects of cryo-immobilization on the apparent shapes of biological polymers. The main focus of our study is on tubulin protofilaments. These structures are integral parts of microtubules, which in turn are key elements of the cellular skeleton, essential for intracellular transport, maintenance of cell shape, cell division and migration. We theoretically examine the extent of protofilament relaxation within the freezing time as a function of the cooling rate, the filament's flexural rigidity, and the effect of cooling on water's viscosity. Our modeling suggests that practically achievable cooling rates are not rapid enough to capture tubulin protofilaments in conformations that are incompletely relaxed, suggesting that structures seen by cryo-EM are good approximations to physiological shapes. This prediction is confirmed by our analysis of curvatures of tubulin protofilaments, using samples, prepared and visualized with a variety of methods. We find, however, that cryofixation may capture incompletely relaxed shapes of more flexible polymers, and it may affect Cryo-EM-based measurements of their persistence lengths. This analysis will be valuable for understanding of structures of different types of biopolymers, observed with Cryo-EM.
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Affiliation(s)
- Evgeniy V. Ulyanov
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
| | | | - J. Richard McIntosh
- Department of MCD Biology, University of Colorado, Boulder, CO, United States of America
| | - Nikita B. Gudimchuk
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
- Department of MCD Biology, University of Colorado, Boulder, CO, United States of America
- Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
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Affiliation(s)
- Christophe Leterrier
- Aix Marseille Université, Centre National de la Recherche Scientifique, INP Unité Mixte de Recherche 7051, NeuroCyto, Marseille 13005, France
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35
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Abstract
The stochastic switching between microtubule growth and shrinkage is a fascinating and unique process in the regulation of the cytoskeleton. To understand it, almost all attention has been focused on the microtubule ends. However, recent research has revived the idea that tubulin dimers can also be exchanged in protofilaments along the microtubule shaft, thus repairing the microtubule and protecting it from disassembly. Here, we review the research describing this phenomenon, the mechanisms regulating the removal and insertion of tubulin dimers, as well as the potential implications for key functions of the microtubule network, such as intracellular transport and cell polarization.
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Affiliation(s)
- Manuel Théry
- University of Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, Grenoble, 38054, France; University of Paris, INSERM, CEA, Institut de Recherche Saint Louis, U976, HIPI, CytoMorpho Lab, Paris, 75010, France.
| | - Laurent Blanchoin
- University of Grenoble-Alpes, CEA, CNRS, INRA, Interdisciplinary Research Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, Grenoble, 38054, France; University of Paris, INSERM, CEA, Institut de Recherche Saint Louis, U976, HIPI, CytoMorpho Lab, Paris, 75010, France.
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36
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Paul DM, Mantell J, Borucu U, Coombs J, Surridge KJ, Squire JM, Verkade P, Dodding MP. In situ cryo-electron tomography reveals filamentous actin within the microtubule lumen. J Cell Biol 2020; 219:e201911154. [PMID: 32478855 PMCID: PMC7480112 DOI: 10.1083/jcb.201911154] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 03/16/2020] [Accepted: 05/13/2020] [Indexed: 11/22/2022] Open
Abstract
Microtubules and filamentous (F-) actin engage in complex interactions to drive many cellular processes from subcellular organization to cell division and migration. This is thought to be largely controlled by proteins that interface between the two structurally distinct cytoskeletal components. Here, we use cryo-electron tomography to demonstrate that the microtubule lumen can be occupied by extended segments of F-actin in small molecule-induced, microtubule-based, cellular projections. We uncover an unexpected versatility in cytoskeletal form that may prompt a significant development of our current models of cellular architecture and offer a new experimental approach for the in situ study of microtubule structure and contents.
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Affiliation(s)
- Danielle M. Paul
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Judith Mantell
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Ufuk Borucu
- GW4 Facility for High-Resolution Electron Cryo-Microscopy, University of Bristol, Bristol, United Kingdom
| | - Jennifer Coombs
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Katherine J. Surridge
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - John M. Squire
- School of Physiology, Pharmacology and Neuroscience, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
- Department of Metabolism, Digestion and Reproduction, Imperial College, London, United Kingdom
| | - Paul Verkade
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
| | - Mark P. Dodding
- School of Biochemistry, Faculty of Life Sciences, University of Bristol, Bristol, United Kingdom
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37
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Abstract
Tubulin dimers associate longitudinally and laterally to form metastable microtubules (MTs). MT disassembly is preceded by subtle structural changes in tubulin fueled by GTP hydrolysis. These changes render the MT lattice unstable, but it is unclear exactly how they affect lattice energetics and strain. We performed long-time atomistic simulations to interrogate the impacts of GTP hydrolysis on tubulin lattice conformation, lateral inter-dimer interactions, and (non-)local lateral coordination of dimer motions. The simulations suggest that most of the hydrolysis energy is stored in the lattice in the form of longitudinal strain. While not significantly affecting lateral bond stability, the stored elastic energy results in more strongly confined and correlated dynamics of GDP-tubulins, thereby entropically destabilizing the MT lattice.
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Affiliation(s)
- Maxim Igaev
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
| | - Helmut Grubmüller
- Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, D-37077 Göttingen, Germany
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39
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Ohto-Fujita E, Hayasaki S, Atomi A, Fujiki S, Watanabe T, Boelens WC, Shimizu M, Atomi Y. Dynamic localization of αB-crystallin at the microtubule cytoskeleton network in beating heart cells. J Biochem 2020; 168:125-137. [PMID: 32725133 DOI: 10.1093/jb/mvaa025] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 02/05/2020] [Indexed: 01/17/2023] Open
Abstract
αB-crystallin is highly expressed in the heart and slow skeletal muscle; however, the roles of αB-crystallin in the muscle are obscure. Previously, we showed that αB-crystallin localizes at the sarcomere Z-bands, corresponding to the focal adhesions of cultured cells. In myoblast cells, αB-crystallin completely colocalizes with microtubules and maintains cell shape and adhesion. In this study, we show that in beating cardiomyocytes α-tubulin and αB-crystallin colocalize at the I- and Z-bands of the myocardium, where it may function as a molecular chaperone for tubulin/microtubules. Fluorescence recovery after photobleaching (FRAP) analysis revealed that the striated patterns of GFP-αB-crystallin fluorescence recovered quickly at 37°C. FRAP mobility assay also showed αB-crystallin to be associated with nocodazole-treated free tubulin dimers but not with taxol-treated microtubules. The interaction of αB-crystallin and free tubulin was further confirmed by immunoprecipitation and microtubule sedimentation assay in the presence of 1-100 μM calcium, which destabilizes microtubules. Förster resonance energy transfer analysis showed that αB-crystallin and tubulin were at 1-10 nm apart from each other in the presence of colchicine. These results suggested that αB-crystallin may play an essential role in microtubule dynamics by maintaining free tubulin in striated muscles, such as the soleus or cardiac muscles.
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Affiliation(s)
- Eri Ohto-Fujita
- Material Health Science Laboratory, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Saaya Hayasaki
- Material Health Science Laboratory, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Aya Atomi
- Material Health Science Laboratory, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Soichiro Fujiki
- Department of Physiology and Biological Information, Dokkyo Medical University, Mibu, Tochigi 321-0293, Japan
| | - Toshiyuki Watanabe
- Division of Applied Chemistry, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Wilbert C Boelens
- Department of Biomolecular Chemistry, Institute for Molecules and Materials (IMM), Radboud University, Nijmegen, The Netherlands
| | - Miho Shimizu
- Material Health Science Laboratory, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
| | - Yoriko Atomi
- Material Health Science Laboratory, Graduate School of Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo 184-8588, Japan
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40
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Gudimchuk NB, Ulyanov EV, O'Toole E, Page CL, Vinogradov DS, Morgan G, Li G, Moore JK, Szczesna E, Roll-Mecak A, Ataullakhanov FI, Richard McIntosh J. Mechanisms of microtubule dynamics and force generation examined with computational modeling and electron cryotomography. Nat Commun 2020; 11:3765. [PMID: 32724196 PMCID: PMC7387542 DOI: 10.1038/s41467-020-17553-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 07/08/2020] [Indexed: 01/15/2023] Open
Abstract
Microtubules are dynamic tubulin polymers responsible for many cellular processes, including the capture and segregation of chromosomes during mitosis. In contrast to textbook models of tubulin self-assembly, we have recently demonstrated that microtubules elongate by addition of bent guanosine triphosphate tubulin to the tips of curving protofilaments. Here we explore this mechanism of microtubule growth using Brownian dynamics modeling and electron cryotomography. The previously described flaring shapes of growing microtubule tips are remarkably consistent under various assembly conditions, including different tubulin concentrations, the presence or absence of a polymerization catalyst or tubulin-binding drugs. Simulations indicate that development of substantial forces during microtubule growth and shortening requires a high activation energy barrier in lateral tubulin-tubulin interactions. Modeling offers a mechanism to explain kinetochore coupling to growing microtubule tips under assisting force, and it predicts a load-dependent acceleration of microtubule assembly, providing a role for the flared morphology of growing microtubule ends.
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Affiliation(s)
- Nikita B Gudimchuk
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia.
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia.
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia.
| | - Evgeni V Ulyanov
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
| | - Eileen O'Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Cynthia L Page
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Dmitrii S Vinogradov
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
| | - Garry Morgan
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Gabriella Li
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Jeffrey K Moore
- Department of Cell and Developmental Biology, University of Colorado School of Medicine, Aurora, CO, USA
| | - Ewa Szczesna
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, USA
| | - Fazoil I Ataullakhanov
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
- Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - J Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO, USA
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41
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Chakraborty S, Jasnin M, Baumeister W. Three-dimensional organization of the cytoskeleton: A cryo-electron tomography perspective. Protein Sci 2020; 29:1302-1320. [PMID: 32216120 PMCID: PMC7255506 DOI: 10.1002/pro.3858] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 03/17/2020] [Accepted: 03/20/2020] [Indexed: 01/01/2023]
Abstract
Traditionally, structures of cytoskeletal components have been studied ex situ, that is, with biochemically purified materials. There are compelling reasons to develop approaches to study them in situ in their native functional context. In recent years, cryo-electron tomography emerged as a powerful method for visualizing the molecular organization of unperturbed cellular landscapes with the potential to attain near-atomic resolution. Here, we review recent works on the cytoskeleton using cryo-electron tomography, demonstrating the power of in situ studies. We also highlight the potential of this method in addressing important questions pertinent to the field of cytoskeletal biomechanics.
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Affiliation(s)
- Saikat Chakraborty
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
| | - Marion Jasnin
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
| | - Wolfgang Baumeister
- Department of Molecular Structural BiologyMax Planck Institute of BiochemistryMartinsriedGermany
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42
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Cuveillier C, Delaroche J, Seggio M, Gory-Fauré S, Bosc C, Denarier E, Bacia M, Schoehn G, Mohrbach H, Kulić I, Andrieux A, Arnal I, Delphin C. MAP6 is an intraluminal protein that induces neuronal microtubules to coil. Sci Adv 2020; 6:eaaz4344. [PMID: 32270043 PMCID: PMC7112752 DOI: 10.1126/sciadv.aaz4344] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/09/2020] [Indexed: 06/01/2023]
Abstract
Neuronal activities depend heavily on microtubules, which shape neuronal processes and transport myriad molecules within them. Although constantly remodeled through growth and shrinkage events, neuronal microtubules must be sufficiently stable to maintain nervous system wiring. This stability is somehow maintained by various microtubule-associated proteins (MAPs), but little is known about how these proteins work. Here, we show that MAP6, previously known to confer cold stability to microtubules, promotes growth. More unexpectedly, MAP6 localizes in the lumen of microtubules, induces the microtubules to coil into a left-handed helix, and forms apertures in the lattice, likely to relieve mechanical stress. These features have not been seen in microtubules before and could play roles in maintaining axonal width or providing flexibility in the face of compressive forces during development.
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Affiliation(s)
- Camille Cuveillier
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Julie Delaroche
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Maxime Seggio
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Sylvie Gory-Fauré
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Christophe Bosc
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Eric Denarier
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Maria Bacia
- Univ. Grenoble Alpes, CNRS, CEA, Institut for Structural Biology (IBS), 38000 Grenoble, France
| | - Guy Schoehn
- Univ. Grenoble Alpes, CNRS, CEA, Institut for Structural Biology (IBS), 38000 Grenoble, France
| | - Hervé Mohrbach
- Laboratoire de Chimie et Physique Théorique, UMR 7019, Université de Lorraine
| | - Igor Kulić
- Institut Charles Sandron, CNRS-UdS, 67034 Strasbourg, France
| | - Annie Andrieux
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Isabelle Arnal
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Christian Delphin
- Univ. Grenoble Alpes, Inserm U1216, CEA, CNRS, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
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43
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Estévez-Gallego J, Josa-Prado F, Ku S, Buey RM, Balaguer FA, Prota AE, Lucena-Agell D, Kamma-Lorger C, Yagi T, Iwamoto H, Duchesne L, Barasoain I, Steinmetz MO, Chrétien D, Kamimura S, Díaz JF, Oliva MA. Structural model for differential cap maturation at growing microtubule ends. eLife 2020; 9:50155. [PMID: 32151315 PMCID: PMC7064335 DOI: 10.7554/elife.50155] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 01/25/2020] [Indexed: 11/13/2022] Open
Abstract
Microtubules (MTs) are hollow cylinders made of tubulin, a GTPase responsible for essential functions during cell growth and division, and thus, key target for anti-tumor drugs. In MTs, GTP hydrolysis triggers structural changes in the lattice, which are responsible for interaction with regulatory factors. The stabilizing GTP-cap is a hallmark of MTs and the mechanism of the chemical-structural link between the GTP hydrolysis site and the MT lattice is a matter of debate. We have analyzed the structure of tubulin and MTs assembled in the presence of fluoride salts that mimic the GTP-bound and GDP•Pi transition states. Our results challenge current models because tubulin does not change axial length upon GTP hydrolysis. Moreover, analysis of the structure of MTs assembled in the presence of several nucleotide analogues and of taxol allows us to propose that previously described lattice expansion could be a post-hydrolysis stage involved in Pi release.
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Affiliation(s)
- Juan Estévez-Gallego
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | - Fernando Josa-Prado
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | - Siou Ku
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, Rennes, France
| | - Ruben M Buey
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain.,Departamento de Microbiología y Genética, Universidad de Salamanca-Campus Miguel de Unamuno, Salamanca, Spain
| | - Francisco A Balaguer
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | - Andrea E Prota
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland
| | - Daniel Lucena-Agell
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | | | - Toshiki Yagi
- Department of Life Sciences, Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Hiroyuki Iwamoto
- Diffraction and Scattering Division, Japan Synchrotron Radiation Research Institute, Hyogo, Japan
| | - Laurence Duchesne
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, Rennes, France
| | - Isabel Barasoain
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | - Michel O Steinmetz
- Division of Biology and Chemistry, Laboratory of Biomolecular Research, Paul Scherrer Institut, Villigen, Switzerland.,University of Basel, Biozentrum, Basel, Switzerland
| | - Denis Chrétien
- Univ Rennes, CNRS, IGDR (Institut de Génétique et Développement de Rennes) - UMR 6290, Rennes, France
| | - Shinji Kamimura
- Department of Biological Sciences, Faculty of Science and Engineering, Chuo University, Tokyo, Japan
| | - J Fernando Díaz
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
| | - Maria A Oliva
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain
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44
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Atherton J, Luo Y, Xiang S, Yang C, Rai A, Jiang K, Stangier M, Vemu A, Cook AD, Wang S, Roll-Mecak A, Steinmetz MO, Akhmanova A, Baldus M, Moores CA. Structural determinants of microtubule minus end preference in CAMSAP CKK domains. Nat Commun 2019; 10:5236. [PMID: 31748546 PMCID: PMC6868217 DOI: 10.1038/s41467-019-13247-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 10/23/2019] [Indexed: 12/20/2022] Open
Abstract
CAMSAP/Patronins regulate microtubule minus-end dynamics. Their end specificity is mediated by their CKK domains, which we proposed recognise specific tubulin conformations found at minus ends. To critically test this idea, we compared the human CAMSAP1 CKK domain (HsCKK) with a CKK domain from Naegleria gruberi (NgCKK), which lacks minus-end specificity. Here we report near-atomic cryo-electron microscopy structures of HsCKK- and NgCKK-microtubule complexes, which show that these CKK domains share the same protein fold, bind at the intradimer interprotofilament tubulin junction, but exhibit different footprints on microtubules. NMR experiments show that both HsCKK and NgCKK are remarkably rigid. However, whereas NgCKK binding does not alter the microtubule architecture, HsCKK remodels its microtubule interaction site and changes the underlying polymer structure because the tubulin lattice conformation is not optimal for its binding. Thus, in contrast to many MAPs, the HsCKK domain can differentiate subtly specific tubulin conformations to enable microtubule minus-end recognition.
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Affiliation(s)
- Joseph Atherton
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, UK.
| | - Yanzhang Luo
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Shengqi Xiang
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
- MOE Key Lab for biomolecular Condensates & Cellular Dynamics, School of Life Sciences, University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026, Anhui, China
| | - Chao Yang
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Ankit Rai
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Kai Jiang
- Medical Research Institute, School of Medicine, Wuhan University, 430071, Wuhan, China
| | - Marcel Stangier
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, PSI, Switzerland
| | - Annapurna Vemu
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, 20892, USA
| | - Alexander D Cook
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, UK
| | - Su Wang
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, UK
| | - Antonina Roll-Mecak
- Cell Biology and Biophysics Unit, National Institute of Neurological Disorders and Stroke, Bethesda, MD, 20892, USA
- Biophysics Center, National Heart, Lung and Blood Institute, Bethesda, MD, 20892, USA
| | - Michel O Steinmetz
- Laboratory of Biomolecular Research, Division of Biology and Chemistry, Paul Scherrer Institut, Villigen, PSI, Switzerland
- University of Basel, Biozentrum, CH-4056, Basel, Switzerland
| | - Anna Akhmanova
- Cell Biology, Department of Biology, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Marc Baldus
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands.
| | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Birkbeck, University of London, Malet Street, London, UK.
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45
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Cook AD, Manka SW, Wang S, Moores CA, Atherton J. A microtubule RELION-based pipeline for cryo-EM image processing. J Struct Biol 2020; 209:107402. [PMID: 31610239 DOI: 10.1016/j.jsb.2019.10.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 10/04/2019] [Accepted: 10/07/2019] [Indexed: 12/20/2022]
Abstract
MiRP is a pipeline for processing cryo-EM images of microtubules in RELION. MiRP manages microtubule heterogeneity and pseudo-symmetry. MiRP reduces errors in angular and translational alignment. MiRP improved reconstructions from three different microtubule datasets.
Microtubules are polar filaments built from αβ-tubulin heterodimers that exhibit a range of architectures in vitro and in vivo. Tubulin heterodimers are arranged helically in the microtubule wall but many physiologically relevant architectures exhibit a break in helical symmetry known as the seam. Noisy 2D cryo-electron microscopy projection images of pseudo-helical microtubules therefore depict distinct but highly similar views owing to the high structural similarity of α- and β-tubulin. The determination of the αβ-tubulin register and seam location during image processing is essential for alignment accuracy that enables determination of biologically relevant structures. Here we present a pipeline designed for image processing and high-resolution reconstruction of cryo-electron microscopy microtubule datasets, based in the popular and user-friendly RELION image-processing package, Microtubule RELION-based Pipeline (MiRP). The pipeline uses a combination of supervised classification and prior knowledge about geometric lattice constraints in microtubules to accurately determine microtubule architecture and seam location. The presented method is fast and semi-automated, producing near-atomic resolution reconstructions with test datasets that contain a range of microtubule architectures and binding proteins.
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46
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Reid TA, Coombes C, Mukherjee S, Goldblum RR, White K, Parmar S, McClellan M, Zanic M, Courtemanche N, Gardner MK. Structural state recognition facilitates tip tracking of EB1 at growing microtubule ends. eLife 2019; 8:48117. [PMID: 31478831 PMCID: PMC6742484 DOI: 10.7554/elife.48117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Accepted: 08/23/2019] [Indexed: 11/13/2022] Open
Abstract
The microtubule binding protein EB1 specifically targets the growing ends of microtubules in cells, where EB1 facilitates the interactions of cellular proteins with microtubule plus-ends. Microtubule end targeting of EB1 has been attributed to high-affinity binding of EB1 to GTP-tubulin that is present at growing microtubule ends. However, our 3D single-molecule diffusion simulations predicted a ~ 6000% increase in EB1 arrivals to open, tapered microtubule tip structures relative to closed lattice conformations. Using quantitative fluorescence, single-molecule, and electron microscopy experiments, we found that the binding of EB1 onto opened, structurally disrupted microtubules was dramatically increased relative to closed, intact microtubules, regardless of hydrolysis state. Correspondingly, in cells, the blunting of growing microtubule plus-ends by Vinblastine was correlated with reduced EB1 targeting. Together, our results suggest that microtubule structural recognition, based on a fundamental diffusion-limited binding model, facilitates the tip tracking of EB1 at growing microtubule ends.
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Affiliation(s)
- Taylor A Reid
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Courtney Coombes
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Soumya Mukherjee
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Rebecca R Goldblum
- Medical Scientist Training Program, University of Minnesota, Minneapolis, United States.,Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, United States
| | - Kyle White
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Sneha Parmar
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Mark McClellan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, United States
| | - Naomi Courtemanche
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
| | - Melissa K Gardner
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, United States
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47
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Strothman C, Farmer V, Arpağ G, Rodgers N, Podolski M, Norris S, Ohi R, Zanic M. Microtubule minus-end stability is dictated by the tubulin off-rate. J Cell Biol 2019; 218:2841-2853. [PMID: 31420452 PMCID: PMC6719460 DOI: 10.1083/jcb.201905019] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/11/2019] [Accepted: 07/23/2019] [Indexed: 12/25/2022] Open
Abstract
Dynamic organization of microtubule minus ends is vital for the formation and maintenance of acentrosomal microtubule arrays. In vitro, both microtubule ends switch between phases of assembly and disassembly, a behavior called dynamic instability. Although minus ends grow slower, their lifetimes are similar to those of plus ends. The mechanisms underlying these distinct dynamics remain unknown. Here, we use an in vitro reconstitution approach to investigate minus-end dynamics. We find that minus-end lifetimes are not defined by the mean size of the protective GTP-tubulin cap. Rather, we conclude that the distinct tubulin off-rate is the primary determinant of the difference between plus- and minus-end dynamics. Further, our results show that the minus-end-directed kinesin-14 HSET/KIFC1 suppresses tubulin off-rate to specifically suppress minus-end catastrophe. HSET maintains its protective minus-end activity even when challenged by a known microtubule depolymerase, kinesin-13 MCAK. Our results provide novel insight into the mechanisms of minus-end dynamics, essential for our understanding of microtubule minus-end regulation in cells.
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Affiliation(s)
- Claire Strothman
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Veronica Farmer
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Göker Arpağ
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Nicole Rodgers
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Marija Podolski
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Stephen Norris
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
| | - Ryoma Ohi
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Marija Zanic
- Department of Cell and Developmental Biology, Vanderbilt University, Nashville, TN
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN
- Department of Biochemistry, Vanderbilt University, Nashville, TN
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48
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Fedorov VA, Orekhov PS, Kholina EG, Zhmurov AA, Ataullakhanov FI, Kovalenko IB, Gudimchuk NB. Mechanical properties of tubulin intra- and inter-dimer interfaces and their implications for microtubule dynamic instability. PLoS Comput Biol 2019; 15:e1007327. [PMID: 31469822 PMCID: PMC6742422 DOI: 10.1371/journal.pcbi.1007327] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 09/12/2019] [Accepted: 08/08/2019] [Indexed: 11/18/2022] Open
Abstract
Thirteen tubulin protofilaments, made of αβ-tubulin heterodimers, interact laterally to produce cytoskeletal microtubules. Microtubules exhibit the striking property of dynamic instability, manifested in their intermittent growth and shrinkage at both ends. This behavior is key to many cellular processes, such as cell division, migration, maintenance of cell shape, etc. Although assembly and disassembly of microtubules is known to be linked to hydrolysis of a guanosine triphosphate molecule in the pocket of β-tubulin, detailed mechanistic understanding of corresponding conformational changes is still lacking. Here we take advantage of the recent generation of in-microtubule structures of tubulin to examine the properties of protofilaments, which serve as important microtubule assembly and disassembly intermediates. We find that initially straight tubulin protofilaments, relax to similar non-radially curved and slightly twisted conformations. Our analysis further suggests that guanosine triphosphate hydrolysis primarily affects the flexibility and conformation of the inter-dimer interface, without a strong impact on the shape or flexibility of αβ-heterodimer. Inter-dimer interfaces are significantly more flexible compared to intra-dimer interfaces. We argue that such a difference in flexibility could be key for distinct stability of the plus and minus microtubule ends. The higher flexibility of the inter-dimer interface may have implications for development of pulling force by curving tubulin protofilaments during microtubule disassembly, a process of major importance for chromosome motions in mitosis.
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Affiliation(s)
| | - Philipp S. Orekhov
- Department of Biology, Lomonosov Moscow State University, Moscow, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Sechenov University, Moscow, Russia
| | | | - Artem A. Zhmurov
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Sechenov University, Moscow, Russia
| | - Fazoil I. Ataullakhanov
- Moscow Institute of Physics and Technology, Dolgoprudny, Russia
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
| | - Ilya B. Kovalenko
- Department of Biology, Lomonosov Moscow State University, Moscow, Russia
- Sechenov University, Moscow, Russia
- Federal Research and Clinical Center of Specialized Medical Care and Medical Technologies, Federal Medical and Biological Agency of Russia, Moscow, Russia
- Astrakhan State University, Astrakhan, Russia
- Peoples’ Friendship University of Russia (RUDN University), Moscow, Russia
| | - Nikita B. Gudimchuk
- Department of Physics, Lomonosov Moscow State University, Moscow, Russia
- Center for Theoretical Problems of Physicochemical Pharmacology, Russian Academy of Sciences, Moscow, Russia
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49
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Schaedel L, Triclin S, Chrétien D, Abrieu A, Aumeier C, Gaillard J, Blanchoin L, Théry M, John K. Lattice defects induce microtubule self-renewal. Nat Phys 2019; 15:830-838. [PMID: 31867047 PMCID: PMC6924994 DOI: 10.1038/s41567-019-0542-4] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Microtubules are dynamic polymers, which grow and shrink by addition and removal of tubulin dimers at their extremities. Within the microtubule shaft, dimers adopt a densely packed and highly ordered crystal-like lattice structure, which is generally not considered to be dynamic. Here we report that thermal forces are sufficient to remodel the microtubule shaft, despite its apparent stability. Our combined experimental data and numerical simulations on lattice dynamics and structure suggest that dimers can spontaneously leave and be incorporated into the lattice at structural defects. We propose a model mechanism, where the lattice dynamics is initiated via a passive breathing mechanism at dislocations, which are frequent in rapidly growing microtubules. These results show that we may need to extend the concept of dissipative dynamics, previously established for microtubule extremities, to the entire shaft, instead of considering it as a passive material.
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Affiliation(s)
- Laura Schaedel
- Univ. Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 38054 Grenoble, France
| | - Sarah Triclin
- Univ. Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 38054 Grenoble, France
| | - Denis Chrétien
- Univ. Rennes, CNRS, IGDR (Institute of Genetics and Development of Rennes) - UMR 6290, F-35000 Rennes, France
| | - Ariane Abrieu
- CRBM, CNRS, University of Montpellier, Montpellier, France
| | - Charlotte Aumeier
- Univ. Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 38054 Grenoble, France
| | - Jérémie Gaillard
- Univ. Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 38054 Grenoble, France
| | - Laurent Blanchoin
- Univ. Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 38054 Grenoble, France
- Univ. Paris Diderot, INSERM, CEA, Hôpital Saint Louis, Institut Universitaire d’Hematologie, UMRS1160, CytoMorpho Lab, 75010 Paris, France
- Address correspondence to: , ,
| | - Manuel Théry
- Univ. Grenoble-Alpes, CEA, CNRS, INRA, Biosciences & Biotechnology Institute of Grenoble, Laboratoire de Physiologie Cellulaire & Végétale, CytoMorpho Lab, 38054 Grenoble, France
- Univ. Paris Diderot, INSERM, CEA, Hôpital Saint Louis, Institut Universitaire d’Hematologie, UMRS1160, CytoMorpho Lab, 75010 Paris, France
- Address correspondence to: , ,
| | - Karin John
- Univ. Grenoble-Alpes, CNRS, Laboratoire Interdisciplinaire de Physique, 38000 Grenoble, France
- Address correspondence to: , ,
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Chen GY, Cleary JM, Asenjo AB, Chen Y, Mascaro JA, Arginteanu DFJ, Sosa H, Hancock WO. Kinesin-5 Promotes Microtubule Nucleation and Assembly by Stabilizing a Lattice-Competent Conformation of Tubulin. Curr Biol 2019; 29:2259-2269.e4. [PMID: 31280993 DOI: 10.1016/j.cub.2019.05.075] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 03/05/2019] [Accepted: 05/31/2019] [Indexed: 01/04/2023]
Abstract
Besides sliding apart antiparallel microtubules during spindle elongation, the mitotic kinesin-5, Eg5, promotes microtubule polymerization, emphasizing its importance in mitotic spindle length control. Here, we characterize the Eg5 microtubule polymerase mechanism by assessing motor-induced changes in the longitudinal and lateral tubulin-tubulin bonds that form the microtubule lattice. Isolated Eg5 motor domains promote microtubule nucleation, growth, and stability; thus, crosslinking tubulin by pairs of motor heads is not necessary for polymerase activity. Eg5 binds preferentially to microtubules over free tubulin, which contrasts with microtubule-depolymerizing kinesins that preferentially bind free tubulin over microtubules. Colchicine-like inhibitors that stabilize the bent conformation of tubulin allosterically inhibit Eg5 binding, consistent with a model in which Eg5 induces a curved-to-straight transition in tubulin. Domain swap experiments establish that the family-specific loop11-helix 4 junction, which resides near the nucleotide-sensing switch-II domain, is necessary and sufficient for the polymerase activity of Eg5. Thus, we propose a microtubule polymerase mechanism in which Eg5 at the plus-end promotes a curved-to-straight transition in tubulin that enhances lateral bond formation and thereby promotes microtubule growth and stability. One implication is that regulation of Eg5 motile properties by regulatory proteins or small molecule inhibitors could also have effects on intracellular microtubule dynamics.
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Affiliation(s)
- Geng-Yuan Chen
- Department of Biomedical Engineering and Bioengineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Joseph M Cleary
- Department of Biomedical Engineering and Bioengineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Ana B Asenjo
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Yalei Chen
- Center for Bioinformatics, Department of Public Health Sciences, Henry Ford Health System, Detroit, MI, USA
| | - Jacob A Mascaro
- Department of Biomedical Engineering and Bioengineering, Pennsylvania State University, University Park, PA 16802, USA
| | - David F J Arginteanu
- Department of Biomedical Engineering and Bioengineering, Pennsylvania State University, University Park, PA 16802, USA
| | - Hernando Sosa
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - William O Hancock
- Department of Biomedical Engineering and Bioengineering, Pennsylvania State University, University Park, PA 16802, USA.
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