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Krattenmacher J, Lera-Ramirez M, Beber A, Herynek S, Grycova L, Liu X, Neuzil P, Nedelec F, Diez S, Braun M, Lansky Z. Ase1 selectively increases the lifetime of antiparallel microtubule overlaps. Curr Biol 2024:S0960-9822(24)00994-1. [PMID: 39137787 DOI: 10.1016/j.cub.2024.07.055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 04/30/2024] [Accepted: 07/15/2024] [Indexed: 08/15/2024]
Abstract
Microtubules (MTs) are dynamically unstable polar biopolymers switching between periods of polymerization and depolymerization, with the switch from the polymerization to the depolymerization phase termed catastrophe and the reverse transition termed rescue.1 In presence of MT-crosslinking proteins, MTs form parallel or anti-parallel overlaps and self-assemble reversibly into complex networks, such as the mitotic spindle. Differential regulation of MT dynamics in parallel and anti-parallel overlaps is critical for the self-assembly of these networks.2,3 Diffusible MT crosslinkers of the Ase1/MAP65/PRC1 family associate with different affinities to parallel and antiparallel MT overlaps, providing a basis for this differential regulation.4,5,6,7,8,9,10,11 Ase1/MAP65/PRC1 family proteins directly affect MT dynamics12 and recruit other proteins that locally alter MT dynamics, such as CLASP or kinesin-4.7,13,14,15,16 However, how Ase1 differentially regulates MT stability in parallel and antiparallel bundles is unknown. Here, we show that Ase1 selectively promotes antiparallel MT overlap longevity by slowing down the depolymerization velocity and by increasing the rescue frequency, specifically in antiparallelly crosslinked MTs. At the retracting ends of depolymerizing MTs, concomitant with slower depolymerization, we observe retention and accumulation of Ase1 between crosslinked MTs and on isolated MTs. We hypothesize that the ability of Ase1 to reduce the dissociation of tubulin subunits is sufficient to promote its enrichment at MT ends. A mathematical model built on this idea shows good agreement with the experiments. We propose that differential regulation of MT dynamics by Ase1 contributes to mitotic spindle assembly by specifically stabilizing antiparallel overlaps, compared to parallel overlaps or isolated MTs.
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Affiliation(s)
- Jochen Krattenmacher
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, 25250 Vestec, Czechia; B CUBE - Center of Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany; Faculty of Science, Charles University in Prague, 12800 Prague, Czech Republic
| | - Manuel Lera-Ramirez
- Institut Curie, PSL Research University, Sorbonne Université, CNRS UMR144, Paris, France
| | - Alexandre Beber
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, 25250 Vestec, Czechia
| | - Stepan Herynek
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, 25250 Vestec, Czechia
| | - Lenka Grycova
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, 25250 Vestec, Czechia
| | - Xiaocheng Liu
- School of Mechanical Engineering, Department of Microsystem Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P.R. China
| | - Pavel Neuzil
- School of Mechanical Engineering, Department of Microsystem Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, P.R. China
| | - Francois Nedelec
- Sainsbury Laboratory Cambridge, University of Cambridge, CB2 1LR Cambridge, UK.
| | - Stefan Diez
- B CUBE - Center of Molecular Bioengineering, Technische Universität Dresden, 01307 Dresden, Germany; Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany; Cluster of Excellence Physics of Life, Technische Universität Dresden, 01062 Dresden, Germany.
| | - Marcus Braun
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, 25250 Vestec, Czechia.
| | - Zdenek Lansky
- Institute of Biotechnology, Czech Academy of Sciences, BIOCEV, 25250 Vestec, Czechia.
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Salazar BM, Ohi R. Antiparallel microtubule bundling supports KIF15-driven mitotic spindle assembly. Mol Biol Cell 2024; 35:ar84. [PMID: 38598297 PMCID: PMC11238081 DOI: 10.1091/mbc.e24-01-0023] [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: 01/19/2024] [Revised: 04/02/2024] [Accepted: 04/05/2024] [Indexed: 04/12/2024] Open
Abstract
The spindle is a bipolar microtubule-based machine that is crucial for accurate chromosome segregation. Spindle bipolarity is generated by Eg5 (a kinesin-5), a conserved motor that drives spindle assembly by localizing to and sliding apart antiparallel microtubules. In the presence of Eg5 inhibitors (K5Is), KIF15 (a kinesin-12) can promote spindle assembly, resulting in K5I-resistant cells (KIRCs). However, KIF15 is a less potent motor than Eg5, suggesting that other factors may contribute to spindle formation in KIRCs. Protein Regulator of Cytokinesis 1 (PRC1) preferentially bundles antiparallel microtubules, and we previously showed that PRC1 promotes KIF15-microtubule binding, leading us to hypothesize that PRC1 may enhance KIF15 activity in KIRCs. Here, we demonstrate that: 1) loss of PRC1 in KIRCs decreases spindle bipolarity, 2) overexpression of PRC1 increases spindle formation efficiency in KIRCs, 3) overexpression of PRC1 protects K5I naïve cells against the K5I S-trityl-L-cysteine (STLC), and 4) PRC1 overexpression promotes the establishment of K5I resistance. These effects are not fully reproduced by a TPX2, a microtubule bundler with no known preference for microtubule orientation. These results suggest a model wherein PRC1-mediated bundling of microtubules creates a more favorable microtubule architecture for KIF15-driven mitotic spindle assembly in the context of Eg5 inhibition.
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Affiliation(s)
- Brittany M. Salazar
- Department of Cell and Developmental Biology, University of Michigan; Ann Arbor, MI 48109
| | - Ryoma Ohi
- Department of Cell and Developmental Biology, University of Michigan; Ann Arbor, MI 48109
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Kennard AS, Velle KB, Ranjan R, Schulz D, Fritz-Laylin LK. An internally controlled system to study microtubule network diversification links tubulin evolution to the use of distinct microtubule regulators. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.08.573270. [PMID: 38260630 PMCID: PMC10802493 DOI: 10.1101/2024.01.08.573270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Diverse eukaryotic cells assemble microtubule networks that vary in structure and composition. While we understand how cells build microtubule networks with specialized functions, we do not know how microtubule networks diversify across deep evolutionary timescales. This problem has remained unresolved because most organisms use shared pools of tubulins for multiple networks, making it impossible to trace the evolution of any single network. In contrast, the amoeboflagellate Naegleria uses distinct tubulin genes to build distinct microtubule networks: while Naegleria builds flagella from conserved tubulins during differentiation, it uses divergent tubulins to build its mitotic spindle. This genetic separation makes for an internally controlled system to study independent microtubule networks in a single organismal and genomic context. To explore the evolution of these microtubule networks, we identified conserved microtubule binding proteins and used transcriptional profiling of mitosis and differentiation to determine which are upregulated during the assembly of each network. Surprisingly, most microtubule binding proteins are upregulated during only one process, suggesting that Naegleria uses distinct component pools to specialize its microtubule networks. Furthermore, the divergent residues of mitotic tubulins tend to fall within the binding sites of differentiation-specific microtubule regulators, suggesting that interactions between microtubules and their binding proteins constrain tubulin sequence diversification. We therefore propose a model for cytoskeletal evolution in which pools of microtubule network components constrain and guide the diversification of the entire network, so that the evolution of tubulin is inextricably linked to that of its binding partners.
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Affiliation(s)
- Andrew S. Kennard
- Department of Biology, University of Massachusetts, Amherst MA, United States
| | - Katrina B. Velle
- Department of Biology, University of Massachusetts, Amherst MA, United States
| | - Ravi Ranjan
- Genomics Resource Laboratory, Institute of Applied Life Sciences, University of Massachusetts, Amherst MA, United States
| | - Danae Schulz
- Department of Biology, Harvey Mudd College, Claremont CA, United States
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Tan F, Xu J. Validation of the solution structure of dimerization domain of PRC1. PLoS One 2022; 17:e0270572. [PMID: 35930764 PMCID: PMC9355583 DOI: 10.1371/journal.pone.0270572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/13/2022] [Indexed: 11/18/2022] Open
Abstract
Cell-cycle dependent proteins are indispensible for the accurate division of cells, a group of proteins called Microtubule-associated proteins (MAPs) are important to cell division as it bind microtubules and participate with other co-factors to form the spindle midbody, which works as the workhorse of cell-division. PRC1 is a distinguishing member of MAPs, as it is a human MAP and works as the key in mediating daughter cell segregation in ana-phase and telo-phase. The physiological significance of PRC1 calls for a high resolution three-dimensional structure. The crystal structure of PRC1 was published but has low resolution (>3 Å) and incomplete sidechains, placing hurdles to understanding the structure-function relationships of PRC1, therefore, we determined the high-resolution solution structure of PRC1’s dimerization domain using NMR spectroscopy. Significant differences between the crystal structure and the solution structure can be observed, the main differences center around the N terminus and the end of the alpha-Helix H2. Furthermore, detailed structure analyses revealed that the hydrophobic core packing of the solution and crystal structures are also different. To validate the solution structure, we used Hydrogen-deuterium exchange experiments that address the structural discrepancies between the crystal and solution structure; we also generated mutants that are key to the differences in the crystal and solution structures, measuring its structural or thermal stability by NMR spectroscopy and Fluorescence Thermal Shift Assays. These results suggest that N terminal residues are key to the integrity of the whole protein, and the solution structure of the dimerization domain better reflects the conformation PRC1 adopted in solution conditions.
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Affiliation(s)
- Fei Tan
- Peking University, Beijing, China
- * E-mail:
| | - Jin Xu
- Peking University, Beijing, China
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N-Terminus-Mediated Solution Structure of Dimerization Domain of PRC1. Curr Issues Mol Biol 2022; 44:1626-1645. [PMID: 35723369 PMCID: PMC9164050 DOI: 10.3390/cimb44040111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/01/2022] [Accepted: 04/06/2022] [Indexed: 11/30/2022] Open
Abstract
Microtubule-associated proteins (MAPs) are essential for the accurate division of a cell into two daughter cells. These proteins target specific microtubules to be incorporated into the spindle midzone, which comprises a special array of microtubules that initiate cytokinesis during anaphase. A representative member of the MAPs is Protein Regulator of Cytokinesis 1 (PRC1), which self-multimerizes to cross-link microtubules, the malfunction of which might result in cancerous cells. The importance of PRC1 multimerization makes it a popular target for structural studies. The available crystal structure of PRC1 has low resolution (>3 Å) and accuracy, limiting a better understanding of the structure-related functions of PRC1. Therefore, we used NMR spectroscopy to better determine the structure of the dimerization domain of PRC1. The NMR structure shows that the PRC1 N terminus is crucial to the overall structure integrity, but the crystal structure bespeaks otherwise. We systematically addressed the role of the N terminus by generating a series of mutants in which N-terminal residues methionine (Met1) and arginine (Arg2) were either deleted, extended or substituted with other rationally selected amino acids. Each mutant was subsequently analyzed by NMR spectroscopy or fluorescence thermal shift assays for its structural or thermal stability; we found that N-terminal perturbations indeed affected the overall protein structure and that the solution structure better reflects the conformation of PRC1 under solution conditions. These results reveal that the structure of PRC1 is governed by its N terminus through hydrophobic interactions with other core residues, such hitherto unidentified N-terminal conformations might shed light on the structure−function relationships of PRC1 or other proteins. Therefore, our study is of major importance in terms of identifying a novel structural feature and can further the progress of protein folding and protein engineering.
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Vukušić K, Tolić IM. Anaphase B: Long-standing models meet new concepts. Semin Cell Dev Biol 2021; 117:127-139. [PMID: 33849764 PMCID: PMC8406420 DOI: 10.1016/j.semcdb.2021.03.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 12/16/2022]
Abstract
Mitotic cell divisions ensure stable transmission of genetic information from a mother to daughter cells in a series of generations. To ensure this crucial task is accomplished, the cell forms a bipolar structure called the mitotic spindle that divides sister chromatids to the opposite sides of the dividing mother cell. After successful establishment of stable attachments of microtubules to chromosomes and inspection of connections between them, at the heart of mitosis, the cell starts the process of segregation. This spectacular moment in the life of a cell is termed anaphase, and it involves two distinct processes: depolymerization of microtubules bound to chromosomes, which is also known as anaphase A, and elongation of the spindle or anaphase B. Both processes ensure physical separation of disjointed sister chromatids. In this chapter, we review the mechanisms of anaphase B spindle elongation primarily in mammalian systems, combining different pioneering ideas and concepts with more recent findings that shed new light on the force generation and regulation of biochemical modules operating during spindle elongation. Finally, we present a comprehensive model of spindle elongation that includes structural, biophysical, and molecular aspects of anaphase B.
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Affiliation(s)
- Kruno Vukušić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
| | - Iva M Tolić
- Division of Molecular Biology, Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb, Croatia.
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7
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Elting MW. Cytoskeletal biophysics: Passive crosslinker adapts to keep microtubule bundles on track. Curr Biol 2021; 31:R793-R796. [PMID: 34157264 DOI: 10.1016/j.cub.2021.04.065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Assembly of the mitotic spindle requires dynamic adaptation and coordination among an array of motors and crosslinkers. A new study demonstrates in vitro how the mitotic crosslinker PRC1 can tune its behavior to regulate the speed of microtubule sliding.
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Affiliation(s)
- Mary Williard Elting
- Department of Physics, Cluster for Quantitative and Computational Developmental Biology, North Carolina State University, Raleigh, NC 27607, USA.
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