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Dendooven T, Yatskevich S, Burt A, Chen ZA, Bellini D, Rappsilber J, Kilmartin JV, Barford D. Structure of the native γ-tubulin ring complex capping spindle microtubules. Nat Struct Mol Biol 2024; 31:1134-1144. [PMID: 38609662 PMCID: PMC11257966 DOI: 10.1038/s41594-024-01281-y] [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: 11/10/2023] [Accepted: 03/19/2024] [Indexed: 04/14/2024]
Abstract
Microtubule (MT) filaments, composed of α/β-tubulin dimers, are fundamental to cellular architecture, function and organismal development. They are nucleated from MT organizing centers by the evolutionarily conserved γ-tubulin ring complex (γTuRC). However, the molecular mechanism of nucleation remains elusive. Here we used cryo-electron tomography to determine the structure of the native γTuRC capping the minus end of a MT in the context of enriched budding yeast spindles. In our structure, γTuRC presents a ring of γ-tubulin subunits to seed nucleation of exclusively 13-protofilament MTs, adopting an active closed conformation to function as a perfect geometric template for MT nucleation. Our cryo-electron tomography reconstruction revealed that a coiled-coil protein staples the first row of α/β-tubulin of the MT to alternating positions along the γ-tubulin ring of γTuRC. This positioning of α/β-tubulin onto γTuRC suggests a role for the coiled-coil protein in augmenting γTuRC-mediated MT nucleation. Based on our results, we describe a molecular model for budding yeast γTuRC activation and MT nucleation.
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Affiliation(s)
| | - Stanislau Yatskevich
- MRC Laboratory of Molecular Biology, Cambridge, UK.
- Genentech, South San Francisco, CA, USA.
| | - Alister Burt
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Genentech, South San Francisco, CA, USA
| | - Zhuo A Chen
- Technische Universität Berlin, Chair of Bioanalytics, Berlin, Germany
| | - Dom Bellini
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Juri Rappsilber
- Technische Universität Berlin, Chair of Bioanalytics, Berlin, Germany
- Si-M/'Der Simulierte Mensch', Technische Universität Berlin and Charité, Universitätsmedizin Berlin, Berlin, Germany
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK
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Miller MP, Evans RK, Zelter A, Geyer EA, MacCoss MJ, Rice LM, Davis TN, Asbury CL, Biggins S. Kinetochore-associated Stu2 promotes chromosome biorientation in vivo. PLoS Genet 2019; 15:e1008423. [PMID: 31584935 PMCID: PMC6795502 DOI: 10.1371/journal.pgen.1008423] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 10/16/2019] [Accepted: 09/13/2019] [Indexed: 12/31/2022] Open
Abstract
Accurate segregation of chromosomes to daughter cells is a critical aspect of cell division. It requires the kinetochores on duplicated chromosomes to biorient, attaching to microtubules from opposite poles of the cell. Bioriented attachments come under tension, while incorrect attachments lack tension and must be released to allow proper attachments to form. A well-studied error correction pathway is mediated by the Aurora B kinase, which destabilizes low tension-bearing attachments. We recently discovered that in vitro, kinetochores display an additional intrinsic tension-sensing pathway that utilizes Stu2. The contribution of kinetochore-associated Stu2 to error correction in cells, however, was unknown. Here, we identify a Stu2 mutant that abolishes its kinetochore function and show that it causes biorientation defects in vivo. We also show that this Stu2-mediated pathway functions together with the Aurora B-mediated pathway. Altogether, our work indicates that cells employ multiple pathways to ensure biorientation and the accuracy of chromosome segregation. The precise regulation of cell division is critical to processes such as self-renewal, proliferation and development. A key event in the cell cycle is the partitioning of every pair of duplicated chromosomes to daughter cells. Defects in chromosome partitioning lead to aneuploidy, a condition that is a common hallmark of cancer cells and the cause of some birth defects. Chromosomes segregate using their kinetochores, the specialized protein structures that are assembled on centromeric DNA sequences and attach to spindle microtubules. Here, we report that a protein that associates with kinetochores called Stu2 ensures that each kinetochore attaches to the proper microtubules. We identified a Stu2 mutant that does not associate with kinetochores and found that it generates aneuploidy. Together, our work identifies a previously unknown mechanism where cells ensure that chromosomes are accurately inherited during cell division.
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Affiliation(s)
- Matthew P. Miller
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Rena K. Evans
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Alex Zelter
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, United States of America
| | - Elisabeth A. Geyer
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, Texas, United States of America
| | - Michael J. MacCoss
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Luke M. Rice
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, Texas, United States of America
| | - Trisha N. Davis
- Department of Biochemistry, University of Washington, Seattle, Washington 98195, United States of America
| | - Charles L. Asbury
- Department of Physiology & Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * E-mail:
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3
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Cook BD, Chang F, Flor-Parra I, Al-Bassam J. Microtubule polymerase and processive plus-end tracking functions originate from distinct features within TOG domain arrays. Mol Biol Cell 2019; 30:1490-1504. [PMID: 30969896 PMCID: PMC6724690 DOI: 10.1091/mbc.e19-02-0093] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
XMAP215/Stu2/Alp14 accelerates tubulin polymerization while processively tracking microtubule (MT) plus ends via tumor overexpressed gene (TOG) domain arrays. It remains poorly understood how these functions arise from tubulin recruitment, mediated by the distinct TOG1 and TOG2 domains, or the assembly of these arrays into large square complexes. Here, we describe a relationship between MT plus-end tracking and polymerase functions revealing their distinct origin within TOG arrays. We study Alp14 mutants designed based on structural models, with defects in either tubulin recruitment or self-organization. Using in vivo live imaging in fission yeast and in vitro MT dynamics assays, we show that tubulins recruited by TOG1 and TOG2 serve concerted, yet distinct, roles in MT plus-end tracking and polymerase functions. TOG1 is critical for processive plus-end tracking, whereas TOG2 is critical for accelerating tubulin polymerization. Inactivating interfaces that stabilize square complexes lead to defects in both processive MT plus-end tracking and polymerase. Our studies suggest that a dynamic cycle between square and unfurled TOG array states gives rise to processive polymerase activity at MT plus ends.
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Affiliation(s)
- Brian D Cook
- Department of Molecular Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143
| | - Ignacio Flor-Parra
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide/CSIC/Junta de Andalucía, 41013 Seville, Spain
| | - Jawdat Al-Bassam
- Department of Molecular Cellular Biology, University of California, Davis, Davis, CA 95616
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Greenlee M, Alonso A, Rahman M, Meednu N, Davis K, Tabb V, Cook R, Miller RK. The TOG protein Stu2/XMAP215 interacts covalently and noncovalently with SUMO. Cytoskeleton (Hoboken) 2018; 75:290-306. [PMID: 29729126 PMCID: PMC6712953 DOI: 10.1002/cm.21449] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/27/2018] [Accepted: 04/30/2018] [Indexed: 01/21/2023]
Abstract
Stu2p is the yeast member of the XMAP215/Dis1/ch‐TOG family of microtubule‐associated proteins that promote microtubule polymerization. However, the factors that regulate its activity are not clearly understood. Here we report that Stu2p in the budding yeast Saccharomyces cerevisiae interacts with SUMO by covalent and noncovalent mechanisms. Stu2p interacted by two‐hybrid analysis with the yeast SUMO Smt3p, its E2 Ubc9p, and the E3 Nfi1p. A region of Stu2p containing the dimerization domain was both necessary and sufficient for interaction with SUMO and Ubc9p. Stu2p was found to be sumoylated both in vitro and in vivo. Stu2p copurified with SUMO in a pull‐down assay and vice versa. Stu2p also bound to a nonconjugatable form of SUMO, suggesting that Stu2p can interact noncovalently with SUMO. In addition, Stu2p interacted with the STUbL enzyme Ris1p. Stu2p also copurified with ubiquitin in a pull‐down assay, suggesting that it can be modified by both SUMO and ubiquitin. Tubulin, a major binding partner of Stu2p, also interacted noncovalently with SUMO. By two‐hybrid analysis, the beta‐tubulin Tub2p interacted with SUMO independently of the microtubule stressor, benomyl. Together, these findings raise the possibility that the microtubule polymerization activities mediated by Stu2p are regulated through sumoylation pathways.
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Affiliation(s)
- Matt Greenlee
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Annabel Alonso
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Maliha Rahman
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Nida Meednu
- Department of Biology, University of Rochester, Rochester, New York, 14627
| | - Kayla Davis
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Victoria Tabb
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - River Cook
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
| | - Rita K Miller
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, 74078
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