1
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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] [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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2
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Bernas T, Seo J, Wilson ZT, Tan BH, Deschenes I, Carter C, Liu J, Tseng GN. Persistent PKA activation redistributes NaV1.5 to the cell surface of adult rat ventricular myocytes. J Gen Physiol 2024; 156:e202313436. [PMID: 38226948 PMCID: PMC10791559 DOI: 10.1085/jgp.202313436] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 09/15/2023] [Accepted: 12/08/2023] [Indexed: 01/17/2024] Open
Abstract
During chronic stress, persistent activation of cAMP-dependent protein kinase (PKA) occurs, which can contribute to protective or maladaptive changes in the heart. We sought to understand the effect of persistent PKA activation on NaV1.5 channel distribution and function in cardiomyocytes using adult rat ventricular myocytes as the main model. PKA activation with 8CPT-cAMP and okadaic acid (phosphatase inhibitor) caused an increase in Na+ current amplitude without altering the total NaV1.5 protein level, suggesting a redistribution of NaV1.5 to the myocytes' surface. Biotinylation experiments in HEK293 cells showed that inhibiting protein trafficking from intracellular compartments to the plasma membrane prevented the PKA-induced increase in cell surface NaV1.5. Additionally, PKA activation induced a time-dependent increase in microtubule plus-end binding protein 1 (EB1) and clustering of EB1 at myocytes' peripheral surface and intercalated discs (ICDs). This was accompanied by a decrease in stable interfibrillar microtubules but an increase in dynamic microtubules along the myocyte surface. Imaging and coimmunoprecipitation experiments revealed that NaV1.5 interacted with EB1 and β-tubulin, and both interactions were enhanced by PKA activation. We propose that persistent PKA activation promotes NaV1.5 trafficking to the peripheral surface of myocytes and ICDs by providing dynamic microtubule tracks and enhanced guidance by EB1. Our proposal is consistent with an increase in the correlative distribution of NaV1.5, EB1, and β-tubulin at these subcellular domains in PKA-activated myocytes. Our study suggests that persistent PKA activation, at least during the initial phase, can protect impulse propagation in a chronically stressed heart by increasing NaV1.5 at ICDs.
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Affiliation(s)
- Tytus Bernas
- Department of Anatomy and Neurobiology, Virginia Commonwealth University, Richmond, VA, USA
| | - John Seo
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Zachary T. Wilson
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
| | - Bi-hua Tan
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Isabelle Deschenes
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, OH, USA
| | - Christiane Carter
- Massey Center Bioinformatics Shared Resource, Virginia Commonwealth University, Richmond, VA, USA
| | - Jinze Liu
- Massey Center Bioinformatics Shared Resource, Virginia Commonwealth University, Richmond, VA, USA
| | - Gea-Ny Tseng
- Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA, USA
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3
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Mosby LS, Straube A, Polin M. A general model for the motion of multivalent cargo interacting with substrates. J R Soc Interface 2023; 20:20230510. [PMID: 38016636 PMCID: PMC10684343 DOI: 10.1098/rsif.2023.0510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 11/03/2023] [Indexed: 11/30/2023] Open
Abstract
Multivalent interactions are common in biology at many different length scales, and can result in the directional motion of multivalent cargo along substrates. Here, a general analytical model has been developed that can describe the directional motion of multivalent cargo as a response to position dependence in the binding and unbinding rates exhibited by their interaction sites. Cargo exhibit both an effective velocity, which acts in the direction of increasing cargo-substrate binding rate and decreasing cargo-substrate unbinding rate, and an effective diffusivity. This model can reproduce previously published experimental findings using only the binding and unbinding rate distributions of cargo interaction sites, and without any further parameter fitting. Extension of the cargo binding model to two dimensions reveals an effective velocity with the same properties as that derived for the one-dimensional case.
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Affiliation(s)
- L. S. Mosby
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, Coventry CV4 7AL, UK
- Physics Department, University of Warwick, Coventry CV4 7AL, UK
- Institute of Advanced Study, University of Warwick, Coventry CV4 7AL, UK
| | - A. Straube
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, Coventry CV4 7AL, UK
| | - M. Polin
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, Coventry CV4 7AL, UK
- Physics Department, University of Warwick, Coventry CV4 7AL, UK
- Instituto Mediterráneo de Estudios Avanzados, IMEDEA, Esporles, Illes Balears 07190, Spain
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4
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Song X, Cui L, Wu M, Wang S, Song Y, Liu Z, Xue Z, Chen W, Zhang Y, Li H, Sun L, Liang X. DCX-EMAP is a core organizer for the ultrastructure of Drosophila mechanosensory organelles. J Cell Biol 2023; 222:e202209116. [PMID: 37651176 PMCID: PMC10471123 DOI: 10.1083/jcb.202209116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 06/21/2023] [Accepted: 08/09/2023] [Indexed: 09/01/2023] Open
Abstract
Mechanoreceptor cells develop specialized mechanosensory organelles (MOs), where force-sensitive channels and supporting structures are organized in an orderly manner to detect forces. It is intriguing how MOs are formed. Here, we address this issue by studying the MOs of fly ciliated mechanoreceptors. We show that the main structure of the MOs is a compound cytoskeleton formed of short microtubules and electron-dense materials (EDMs). In a knock-out mutant of DCX-EMAP, this cytoskeleton is nearly absent, suggesting that DCX-EMAP is required for the formation of the MOs and in turn fly mechanotransduction. Further analysis reveals that DCX-EMAP expresses in fly ciliated mechanoreceptors and localizes to the MOs. Moreover, it plays dual roles by promoting the assembly/stabilization of the microtubules and the accumulation of the EDMs in the MOs. Therefore, DCX-EMAP serves as a core ultrastructural organizer of the MOs, and this finding provides novel molecular insights as to how fly MOs are formed.
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Affiliation(s)
- Xuewei Song
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Lihong Cui
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Menghua Wu
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Shan Wang
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yinlong Song
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Zhen Liu
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Zhaoyu Xue
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wei Chen
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yingjie Zhang
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Hui Li
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
| | - Landi Sun
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
- Guangzhou Laboratory, Guangzhou, China
| | - Xin Liang
- IDG/McGovern Institute for Brain Research, School of Life Sciences, Tsinghua University, Beijing, China
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5
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Zhou J, Wang A, Song Y, Liu N, Wang J, Li Y, Liang X, Li G, Chu H, Wang HW. Structural insights into the mechanism of GTP initiation of microtubule assembly. Nat Commun 2023; 14:5980. [PMID: 37749104 PMCID: PMC10519996 DOI: 10.1038/s41467-023-41615-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 09/08/2023] [Indexed: 09/27/2023] Open
Abstract
In eukaryotes, the dynamic assembly of microtubules (MT) plays an important role in numerous cellular processes. The underlying mechanism of GTP triggering MT assembly is still unknown. Here, we present cryo-EM structures of tubulin heterodimer at their GTP- and GDP-bound states, intermediate assembly states of GTP-tubulin, and final assembly stages of MT. Both GTP- and GDP-tubulin heterodimers adopt similar curved conformations with subtle flexibility differences. In head-to-tail oligomers of tubulin heterodimers, the inter-dimer interface of GDP-tubulin exhibits greater flexibility, particularly in tangential bending. Cryo-EM of the intermediate assembly states reveals two types of tubulin lateral contacts, "Tube-bond" and "MT-bond". Further, molecular dynamics (MD) simulations show that GTP triggers lateral contact formation in MT assembly in multiple sequential steps, gradually straightening the curved tubulin heterodimers. Therefore, we propose a flexible model of GTP-initiated MT assembly, including the formation of longitudinal and lateral contacts, to explain the nucleation and assembly of MT.
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Affiliation(s)
- Ju Zhou
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structures, Tsinghua University, Beijing, 100084, China
- University of California Berkeley, Berkeley, CA, USA
| | - Anhui Wang
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, China
| | - Yinlong Song
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Nan Liu
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structures, Tsinghua University, Beijing, 100084, China
| | - Jia Wang
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Beijing Frontier Research Center for Biological Structures, Tsinghua University, Beijing, 100084, China
| | - Yan Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, China
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China
| | - Guohui Li
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, China
| | - Huiying Chu
- Laboratory of Molecular Modeling and Design, State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Science, 457 Zhongshan Road, Dalian, 116023, China.
| | - Hong-Wei Wang
- State Key Laboratory of Membrane Biology, Tsinghua University, Beijing, 100084, China.
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing, 100084, China.
- Beijing Frontier Research Center for Biological Structures, Tsinghua University, Beijing, 100084, China.
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6
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Xie S, Li J, Sun S, Chen W, Cheng H, Song Y, Li Y, Liu M, Zhu X, Liang X, Zhou J. TUBright: A Peptide Probe for Imaging Microtubules. Anal Chem 2022; 94:11168-11174. [PMID: 35917443 DOI: 10.1021/acs.analchem.2c01285] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In vitro assays using reconstituted microtubules have provided molecular insights into the principles of microtubule dynamics and the roles of microtubule-associated proteins. Emerging questions that further uncover the complexity in microtubule dynamics, especially those on tubulin isotypes and post-translational modifications, raise new technical challenges on how to visualize microtubules composed of tubulin purified from limited sources, primarily due to the low efficiency of the conventional tubulin labeling protocol. Here, we develop a peptide probe, termed TUBright, that labels in vitro reconstituted microtubules. TUBright, when coupled with different fluorescent dyes, provides flexible labeling of microtubules with a high signal-to-noise ratio. TUBright does not interfere with the dynamic behaviors of microtubules and microtubule-associated proteins. Therefore, TUBright is a useful tool for imaging microtubules, making it feasible to use tubulin from limited sources for answering many open questions on microtubule dynamics.
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Affiliation(s)
- Songbo Xie
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Jingrui Li
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Shuang Sun
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Wei Chen
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Haisu Cheng
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yinlong Song
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yuyang Li
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Min Liu
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China
| | - Xueliang Zhu
- State Key Laboratory of Cell Biology, Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xin Liang
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Center for Life Science, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jun Zhou
- Center for Cell Structure and Function, Shandong Provincial Key Laboratory of Animal Resistance Biology, Collaborative Innovation Center of Cell Biology in Universities of Shandong, College of Life Sciences, Shandong Normal University, Jinan 250014, China.,State Key Laboratory of Medicinal Chemical Biology, Haihe Laboratory of Cell Ecosystem, College of Life Sciences, Nankai University, Tianjin 300071, China
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7
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Kinesin-14 motors participate in a force balance at microtubule plus-ends to regulate dynamic instability. Proc Natl Acad Sci U S A 2022; 119:2108046119. [PMID: 35173049 PMCID: PMC8872730 DOI: 10.1073/pnas.2108046119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/03/2022] [Indexed: 01/08/2023] Open
Abstract
Kinesin-14 motors represent an essential class of molecular motors that bind to microtubules and then walk toward the microtubule minus-end. However, whether these motors can interact with growing plus-ends of microtubules to impact the lengthening of microtubules remains unknown. We found that Kinesin-14 motors could bind to a protein that resides at growing microtubule plus-ends and then pull this protein away from the growing end. This interaction acted to disrupt microtubule growth and decrease microtubule lengths in cells, likely by exerting minus-end–directed forces at the microtubule tip to alter the configuration of the growing microtubule plus-end. This work demonstrates general principles for the diverse roles that force-generating molecular motors can play in regulating cellular processes. Kinesin-14 molecular motors represent an essential class of proteins that bind microtubules and walk toward their minus-ends. Previous studies have described important roles for Kinesin-14 motors at microtubule minus-ends, but their role in regulating plus-end dynamics remains controversial. Kinesin-14 motors have been shown to bind the EB family of microtubule plus-end binding proteins, suggesting that these minus-end–directed motors could interact with growing microtubule plus-ends. In this work, we explored the role of minus-end–directed Kinesin-14 motor forces in controlling plus-end microtubule dynamics. In cells, a Kinesin-14 mutant with reduced affinity to EB proteins led to increased microtubule lengths. Cell-free biophysical microscopy assays were performed using Kinesin-14 motors and an EB family marker of growing microtubule plus-ends, Mal3, which revealed that when Kinesin-14 motors bound to Mal3 at growing microtubule plus-ends, the motors subsequently walked toward the minus-end, and Mal3 was pulled away from the growing microtubule tip. Strikingly, these interactions resulted in an approximately twofold decrease in the expected postinteraction microtubule lifetime. Furthermore, generic minus-end–directed tension forces, generated by tethering growing plus-ends to the coverslip using λ-DNA, led to an approximately sevenfold decrease in the expected postinteraction microtubule growth length. In contrast, the inhibition of Kinesin-14 minus-end–directed motility led to extended tip interactions and to an increase in the expected postinteraction microtubule lifetime, indicating that plus-ends were stabilized by nonmotile Kinesin-14 motors. Together, we find that Kinesin-14 motors participate in a force balance at microtubule plus-ends to regulate microtubule lengths in cells.
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8
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Mechanistic insights into central spindle assembly mediated by the centralspindlin complex. Proc Natl Acad Sci U S A 2021; 118:2112039118. [PMID: 34588311 PMCID: PMC8501884 DOI: 10.1073/pnas.2112039118] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2021] [Indexed: 02/07/2023] Open
Abstract
Centralspindlin bundles microtubules to assemble the central spindle, being essential for cytokinesis of the cell. It is a heterotetramer formed by ZEN-4 and CYK-4 in a 2:2 manner. We determined the crystal structures of centralspindlin, which revealed the detailed mechanism of complex formation. We found that centralspindlin clustered to undergo liquid–liquid phase separation (LLPS), which depended on the complementary charged residues located at ZEN-4 and CYK-4, respectively, explaining the synergy of the two subunits for the function. The LLPS of centralspindlin is critical for the microtubule bundling activity in vitro and the assembly of the central spindle in vivo. Together, our study provides angstrom-to-micron mechanistic insights into central spindle assembly mediated by the centralspindlin complex. The central spindle spatially and temporally regulates the formation of division plane during cytokinesis in animal cells. The heterotetrameric centralspindlin complex bundles microtubules to assemble the central spindle, the mechanism of which is poorly understood. Here, we determined the crystal structures of the molecular backbone of ZEN-4/CYK-4 centralspindlin from Caenorhabditis elegans, which revealed the detailed mechanism of complex formation. The molecular backbone of centralspindlin has the intrinsic propensity to undergo liquid–liquid phase separation. The condensation of centralspindlin requires two patches of basic residues at ZEN-4 and multiple acidic residues at the intrinsically disordered region of CYK-4, explaining the synergy of the two subunits for the function. These complementary charged residues were critical for the microtubule bundling activity of centralspindlin in vitro and for the assembly of the central spindle in vivo. Together, our findings provide insights into the mechanism of central spindle assembly mediated by centralspindlin through charge-driven macromolecular condensation.
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9
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Diao L, Liu MY, Song YL, Zhang X, Liang X, Bao L. α1A and α1C form microtubules to display distinct properties mainly mediated by their C-terminal tails. J Mol Cell Biol 2021; 13:864-875. [PMID: 34609491 PMCID: PMC8800519 DOI: 10.1093/jmcb/mjab062] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/13/2022] Open
Abstract
Microtubules consisting of α/β-tubulin dimers play critical roles in cells. More than seven genes encode α-tubulin in vertebrates. However, the property of microtubules composed of different α-tubulin isotypes is largely unknown. Here, we purified recombinant tubulin heterodimers of mouse α-tubulin isotypes including α1A and α1C with β-tubulin isotype β2A. In vitro microtubule reconstitution assay detected that α1C/β2A microtubules grew faster and underwent catastrophe less frequently than α1A/β2A microtubules. Generation of chimeric tail-swapped and point-mutation tubulins revealed that the carboxyl-terminal (C-terminal) tails of α-tubulin isotypes largely accounted for the differences in polymerization dynamics of α1A/β2A and α1C/β2A microtubules. Kinetics analysis showed that in comparison to α1A/β2A microtubules, α1C/β2A microtubules displayed higher on-rate, lower off-rate, and similar GTP hydrolysis rate at the plus-end, suggesting a contribution of higher plus-end affinity to faster growth and less frequent catastrophe of α1C/β2A microtubules. Furthermore, EB1 had a higher binding ability to α1C/β2A microtubules than to α1A/β2A ones, which could also be attributed to the difference in the C-terminal tails of these two α-tubulin isotypes. Thus, α-tubulin isotypes diversify microtubule properties, which, to a great extent, could be accounted by their C-terminal tails.
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Affiliation(s)
- Lei Diao
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ming-Yi Liu
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yin-Long Song
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xu Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Lan Bao
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
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