51
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Tourigny JP, Schumacher K, Saleh MM, Devys D, Zentner GE. Architectural Mediator subunits are differentially essential for global transcription in Saccharomyces cerevisiae. Genetics 2021; 217:iyaa042. [PMID: 33789343 PMCID: PMC8045717 DOI: 10.1093/genetics/iyaa042] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 12/16/2020] [Indexed: 12/18/2022] Open
Abstract
Mediator is a modular coactivator complex involved in the transcription of the majority of RNA polymerase II-regulated genes. However, the degrees to which individual core subunits of Mediator contribute to its activity have been unclear. Here, we investigate the contribution of two essential architectural subunits of Mediator to transcription in Saccharomyces cerevisiae. We show that acute depletion of the main complex scaffold Med14 or the head module nucleator Med17 is lethal and results in global transcriptional downregulation, though Med17 removal has a markedly greater negative effect. Consistent with this, Med17 depletion impairs preinitiation complex (PIC) assembly to a greater extent than Med14 removal. Co-depletion of Med14 and Med17 reduced transcription and TFIIB promoter occupancy similarly to Med17 ablation alone, indicating that the contributions of Med14 and Med17 to Mediator function are not additive. We propose that, while the structural integrity of complete Mediator and the head module are both important for PIC assembly and transcription, the head module plays a greater role in this process and is thus the key functional module of Mediator in this regard.
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Affiliation(s)
- Jason P Tourigny
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Kenny Schumacher
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- UMR7104, Centre National de la Recherche Scientifique, 67404 Illkirch, France
- U964, Institut National de la Santé et de la Recherche Médicale, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
| | - Moustafa M Saleh
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Didier Devys
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France
- UMR7104, Centre National de la Recherche Scientifique, 67404 Illkirch, France
- U964, Institut National de la Santé et de la Recherche Médicale, 67404 Illkirch, France
- Université de Strasbourg, 67404 Illkirch, France
| | - Gabriel E Zentner
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
- Indiana University Melvin and Bren Simon Cancer Center, Indianapolis, IN 46202, USA
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52
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McIntosh JR. Anaphase A. Semin Cell Dev Biol 2021; 117:118-126. [PMID: 33781672 DOI: 10.1016/j.semcdb.2021.03.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Revised: 03/16/2021] [Accepted: 03/16/2021] [Indexed: 10/21/2022]
Abstract
Anaphase A is the motion of recently separated chromosomes to the spindle pole they face. It is accompanied by the shortening of kinetochore-attached microtubules. The requisite tubulin depolymerization may occur at kinetochores, at poles, or both, depending on the species and/or the time in mitosis. These depolymerization events are local and suggest that cells regulate microtubule dynamics in specific places, presumably by the localization of relevant enzymes and microtubule-associated proteins to specific loci, such as pericentriolar material and outer kinetochores. Motor enzymes can contribute to anaphase A, both by altering microtubule stability and by pushing or pulling microtubules through the cell. The generation of force on chromosomes requires couplings that can both withstand the considerable force that spindles can generate and simultaneously permit tubulin addition and loss. This chapter reviews literature on the molecules that regulate anaphase microtubule dynamics, couple dynamic microtubules to kinetochores and poles, and generate forces for microtubule and chromosome motion.
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Affiliation(s)
- J Richard McIntosh
- Dept. of Molecular, Cellular, and Developmental Biology University of Colorado, Boulder, CO 80309-0347, USA.
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53
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Shake It Off: The Elimination of Erroneous Kinetochore-Microtubule Attachments and Chromosome Oscillation. Int J Mol Sci 2021; 22:ijms22063174. [PMID: 33804687 PMCID: PMC8003821 DOI: 10.3390/ijms22063174] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 03/18/2021] [Indexed: 01/17/2023] Open
Abstract
Cell proliferation and sexual reproduction require the faithful segregation of chromosomes. Chromosome segregation is driven by the interaction of chromosomes with the spindle, and the attachment of chromosomes to the proper spindle poles is essential. Initial attachments are frequently erroneous due to the random nature of the attachment process; however, erroneous attachments are selectively eliminated. Proper attachment generates greater tension at the kinetochore than erroneous attachments, and it is thought that attachment selection is dependent on this tension. However, studies of meiotic chromosome segregation suggest that attachment elimination cannot be solely attributed to tension, and the precise mechanism of selective elimination of erroneous attachments remains unclear. During attachment elimination, chromosomes oscillate between the spindle poles. A recent study on meiotic chromosome segregation in fission yeast has suggested that attachment elimination is coupled to chromosome oscillation. In this review, the possible contribution of chromosome oscillation in the elimination of erroneous attachment is discussed in light of the recent finding.
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54
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Zahm JA, Stewart MG, Carrier JS, Harrison SC, Miller MP. Structural basis of Stu2 recruitment to yeast kinetochores. eLife 2021; 10:e65389. [PMID: 33591274 PMCID: PMC7909949 DOI: 10.7554/elife.65389] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 02/15/2021] [Indexed: 12/02/2022] Open
Abstract
Chromosome segregation during cell division requires engagement of kinetochores of sister chromatids with microtubules emanating from opposite poles. As the corresponding microtubules shorten, these 'bioriented' sister kinetochores experience tension-dependent stabilization of microtubule attachments. The yeast XMAP215 family member and microtubule polymerase, Stu2, associates with kinetochores and contributes to tension-dependent stabilization in vitro. We show here that a C-terminal segment of Stu2 binds the four-way junction of the Ndc80 complex (Ndc80c) and that residues conserved both in yeast Stu2 orthologs and in their metazoan counterparts make specific contacts with Ndc80 and Spc24. Mutations that perturb this interaction prevent association of Stu2 with kinetochores, impair cell viability, produce biorientation defects, and delay cell cycle progression. Ectopic tethering of the mutant Stu2 species to the Ndc80c junction restores wild-type function in vivo. These findings show that the role of Stu2 in tension-sensing depends on its association with kinetochores by binding with Ndc80c.
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Affiliation(s)
- Jacob A Zahm
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, and Howard Hughes Medical InstituteBostonUnited States
| | - Michael G Stewart
- Department of Biochemistry, University of Utah School of MedicineSalt Lake CityUnited States
| | - Joseph S Carrier
- Department of Biochemistry, University of Utah School of MedicineSalt Lake CityUnited States
| | - Stephen C Harrison
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, and Howard Hughes Medical InstituteBostonUnited States
| | - Matthew P Miller
- Department of Biochemistry, University of Utah School of MedicineSalt Lake CityUnited States
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55
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Wakiya M, Nishi E, Kawai S, Yamada K, Katsumata K, Hirayasu A, Itabashi Y, Yamamoto A. Chiasmata and the kinetochore component Dam1 are crucial for elimination of erroneous chromosome attachments and centromere oscillation at meiosis I. Open Biol 2021; 11:200308. [PMID: 33529549 PMCID: PMC8061696 DOI: 10.1098/rsob.200308] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Establishment of proper chromosome attachments to the spindle requires elimination of erroneous attachments, but the mechanism of this process is not fully understood. During meiosis I, sister chromatids attach to the same spindle pole (mono-oriented attachment), whereas homologous chromosomes attach to opposite poles (bi-oriented attachment), resulting in homologous chromosome segregation. Here, we show that chiasmata that link homologous chromosomes and kinetochore component Dam1 are crucial for elimination of erroneous attachments and oscillation of centromeres between the spindle poles at meiosis I in fission yeast. In chiasma-forming cells, Mad2 and Aurora B kinase, which provides time for attachment correction and destabilizes erroneous attachments, respectively, caused elimination of bi-oriented attachments of sister chromatids, whereas in chiasma-lacking cells, they caused elimination of mono-oriented attachments. In chiasma-forming cells, in addition, homologous centromere oscillation was coordinated. Furthermore, Dam1 contributed to attachment elimination in both chiasma-forming and chiasma-lacking cells, and drove centromere oscillation. These results demonstrate that chiasmata alter attachment correction patterns by enabling error correction factors to eliminate bi-oriented attachment of sister chromatids, and suggest that Dam1 induces elimination of erroneous attachments. The coincidental contribution of chiasmata and Dam1 to centromere oscillation also suggests a potential link between centromere oscillation and attachment elimination.
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Affiliation(s)
- Misuzu Wakiya
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Eriko Nishi
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Shinnosuke Kawai
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.,Department of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Kohei Yamada
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Kazuhiro Katsumata
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Ami Hirayasu
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Yuta Itabashi
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Ayumu Yamamoto
- Graduate School of Integrated Science and Technology, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan.,Department of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
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56
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The Proteomic Landscape of Centromeric Chromatin Reveals an Essential Role for the Ctf19 CCAN Complex in Meiotic Kinetochore Assembly. Curr Biol 2021; 31:283-296.e7. [PMID: 33157029 PMCID: PMC7846277 DOI: 10.1016/j.cub.2020.10.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/10/2020] [Accepted: 10/08/2020] [Indexed: 11/23/2022]
Abstract
Kinetochores direct chromosome segregation in mitosis and meiosis. Faithful gamete formation through meiosis requires that kinetochores take on new functions that impact homolog pairing, recombination, and the orientation of kinetochore attachment to microtubules in meiosis I. Using an unbiased proteomics pipeline, we determined the composition of centromeric chromatin and kinetochores at distinct cell-cycle stages, revealing extensive reorganization of kinetochores during meiosis. The data uncover a network of meiotic chromosome axis and recombination proteins that bind to centromeres in the absence of the microtubule-binding outer kinetochore sub-complexes during meiotic prophase. We show that the Ctf19cCCAN inner kinetochore complex is essential for kinetochore organization in meiosis. Our functional analyses identify a Ctf19cCCAN-dependent kinetochore assembly pathway that is dispensable for mitotic growth but becomes critical upon meiotic entry. Therefore, changes in kinetochore composition and a distinct assembly pathway specialize meiotic kinetochores for successful gametogenesis. The composition of meiotic centromeres and kinetochores is revealed Kinetochores undergo extensive changes between meiotic prophase I and metaphase I The Ctf19CCAN orchestrates meiotic kinetochore specialization A Ctf19CCAN-directed kinetochore assembly pathway is uniquely critical in meiosis
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57
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Herman JA, Miller MP, Biggins S. chTOG is a conserved mitotic error correction factor. eLife 2020; 9:e61773. [PMID: 33377866 PMCID: PMC7773332 DOI: 10.7554/elife.61773] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 12/22/2020] [Indexed: 12/28/2022] Open
Abstract
Accurate chromosome segregation requires kinetochores on duplicated chromatids to biorient by attaching to dynamic microtubules from opposite spindle poles, which exerts forces to bring kinetochores under tension. However, kinetochores initially bind to microtubules indiscriminately, resulting in errors that must be corrected. While the Aurora B protein kinase destabilizes low-tension attachments by phosphorylating kinetochores, low-tension attachments are intrinsically less stable than those under higher tension in vitro independent of Aurora activity. Intrinsic tension-sensitive behavior requires the microtubule regulator Stu2 (budding yeast Dis1/XMAP215 ortholog), which we demonstrate here is likely a conserved function for the TOG protein family. The human TOG protein, chTOG, localizes to kinetochores independent of microtubules by interacting with Hec1. We identify a chTOG mutant that regulates microtubule dynamics but accumulates erroneous kinetochore-microtubule attachments that are not destabilized by Aurora B. Thus, TOG proteins confer a unique, intrinsic error correction activity to kinetochores that ensures accurate chromosome segregation.
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Affiliation(s)
- Jacob A Herman
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Matthew P Miller
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research CenterSeattleUnited States
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research CenterSeattleUnited States
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58
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Zhu Y, Zhang Y, Liu N, Ren W, Hou Y, Duan Y, Song X, Zhou M. The Dis1/Stu2/XMAP215 Family Gene FgStu2 Is Involved in Vegetative Growth, Morphology, Sexual and Asexual Reproduction, Pathogenicity and DON Production of Fusarium graminearum. Front Microbiol 2020; 11:545015. [PMID: 33329417 PMCID: PMC7714731 DOI: 10.3389/fmicb.2020.545015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 10/29/2020] [Indexed: 11/29/2022] Open
Abstract
The conserved Dis1/Stu2/XMAP215 microtubule association proteins (MAPs) family plays an important role in microtubule dynamics, nucleation, and kinetochore-microtubule attachments. However, function of Dis1/Stu2/XMAP215 homolog in plant pathogenic fungi has not been determined. Here, we identified and investigated the Dis1/Stu2/XMAP215 homolog (FGSG_10528) in Fusarium graminearum (FgStu2p). Co-localization experiment and co-immunoprecipitation (Co-IP) assay demonstrated that FgStu2p is a microtubule associated protein. Besides, FgStu2 could also interact with Fgγ-tubulin and presumed FgNdc80, which suggested that the FgStu2 gene might associate with microtubule nucleation and kinetochore-microtubule attachments like Dis1/Stu2/XMAP215 homologs in other species. Moreover, the FgStu2 promoter replacement mutants (FgStu2-Si mutants) produced twisted hyphae and decreased growth rate. Microscope examination further showed that the microtubule polymerization was reduced in FgStu2-Si mutants, which could account for the aberrant morphology. Although the microtubule polymerization was affected in FgStu2-Si mutants, the FgStu2-Si mutants didn't show highly increased sensitivity to anti-microtubule fungicide carbendazim (methyl benzimidazol-2-ylcarbamate [MBC]). In addition, the FgStu2-Si mutants exhibited curved conidia, decreased number of conidial production, blocked ability of perithecia production, decreased pathogenicity and deoxynivalenol (DON) production. Taken together, these results indicate that the FgStu2 gene plays a crucial role in vegetative growth, morphology, sexual reproduction, asexual reproduction, virulence and deoxynivalenol (DON) production of F. graminearum, which brings new insights into the functions of Dis1/Stu2/XMAP215 homolog in plant pathogenic fungi.
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Affiliation(s)
- Yuanye Zhu
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yuanshuai Zhang
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Na Liu
- College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, China
| | - Weichao Ren
- College of Plant Health and Medicine, Qingdao Agricultural University, Qingdao, China
| | - Yiping Hou
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yabing Duan
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Xiushi Song
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Mingguo Zhou
- College of Plant Protection, Nanjing Agricultural University, Nanjing, China
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59
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Girão H, Okada N, Rodrigues TA, Silva AO, Figueiredo AC, Garcia Z, Moutinho-Santos T, Hayashi I, Azevedo JE, Macedo-Ribeiro S, Maiato H. CLASP2 binding to curved microtubule tips promotes flux and stabilizes kinetochore attachments. J Cell Biol 2020; 219:jcb.201905080. [PMID: 31757788 PMCID: PMC7041679 DOI: 10.1083/jcb.201905080] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 10/17/2019] [Accepted: 11/04/2019] [Indexed: 12/11/2022] Open
Abstract
Girão et al. use structure-guided functional mutants of CLASP2 to show that recognition of growing microtubule plus-ends through EB–protein interaction and the ability to associate with curved microtubule protofilaments through TOG2 and TOG3 domains promote growth and stabilization of kinetochore–microtubules required for poleward flux. CLASPs are conserved microtubule plus-end–tracking proteins that suppress microtubule catastrophes and independently localize to kinetochores during mitosis. Thus, CLASPs are ideally positioned to regulate kinetochore–microtubule dynamics required for chromosome segregation fidelity, but the underlying mechanism remains unknown. Here, we found that human CLASP2 exists predominantly as a monomer in solution, but it can self-associate through its C-terminal kinetochore-binding domain. Kinetochore localization was independent of self-association, and driving monomeric CLASP2 to kinetochores fully rescued normal kinetochore–microtubule dynamics, while partially sustaining mitosis. CLASP2 kinetochore localization, recognition of growing microtubule plus-ends through EB–protein interaction, and the ability to associate with curved microtubule protofilaments through TOG2 and TOG3 domains independently sustained normal spindle length, timely spindle assembly checkpoint satisfaction, chromosome congression, and faithful segregation. Measurements of kinetochore–microtubule half-life and poleward flux revealed that CLASP2 regulates kinetochore–microtubule dynamics by integrating distinctive microtubule-binding properties at the kinetochore–microtubule interface. We propose that kinetochore CLASP2 suppresses microtubule depolymerization and detachment by binding to curved protofilaments at microtubule plus-ends.
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Affiliation(s)
- Hugo Girão
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Naoyuki Okada
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Tony A Rodrigues
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto, Portugal
| | - Alexandra O Silva
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Ana C Figueiredo
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Zaira Garcia
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Tatiana Moutinho-Santos
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Ikuko Hayashi
- International Graduate School of Arts and Sciences, Yokohama City University, Yokohama, Japan
| | - Jorge E Azevedo
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar da Universidade do Porto, Porto, Portugal
| | - Sandra Macedo-Ribeiro
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal
| | - Helder Maiato
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal.,Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Cell Division Group, Experimental Biology Unit, Department of Biomedicine, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
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60
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Microtubules pull the strings: disordered sequences as efficient couplers of microtubule-generated force. Essays Biochem 2020; 64:371-382. [PMID: 32502246 DOI: 10.1042/ebc20190078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/01/2020] [Accepted: 05/14/2020] [Indexed: 11/17/2022]
Abstract
Microtubules are dynamic polymers that grow and shrink through addition or loss of tubulin subunits at their ends. Microtubule ends generate mechanical force that moves chromosomes and cellular organelles, and provides mechanical tension. Recent literature describes a number of proteins and protein complexes that couple dynamics of microtubule ends to movements of their cellular cargoes. These 'couplers' are quite diverse in their microtubule-binding domains (MTBDs), while sharing similarity in function, but a systematic understanding of the principles underlying their activity is missing. Here, I review various types of microtubule couplers, focusing on their essential activities: ability to follow microtubule ends and capture microtubule-generated force. Most of the couplers require presence of unstructured positively charged sequences and multivalency in their microtubule-binding sites to efficiently convert the microtubule-generated force into useful connection to a cargo. An overview of the microtubule features supporting end-tracking and force-coupling, and the experimental methods to assess force-coupling properties is also provided.
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61
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Kinetochore-microtubule coupling mechanisms mediated by the Ska1 complex and Cdt1. Essays Biochem 2020; 64:337-347. [PMID: 32844209 DOI: 10.1042/ebc20190075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 08/03/2020] [Accepted: 08/06/2020] [Indexed: 11/17/2022]
Abstract
The faithful segregation of duplicated sister chromatids rely on the remarkable ability of kinetochores to sustain stable load bearing attachments with the dynamic plus ends of kinetochore-microtubules (kMTs). The outer layer of the kinetochore recruits several motor and non-motor microtubule-associated proteins (MAPs) that help the kinetochores establish and maintain a load bearing dynamic attachment with kMTs. The primary kMT-binding protein, the Ndc80 complex (Ndc80c), which is highly conserved among diverse organisms from yeast to humans, performs this essential function with assistance from other MAPs. These MAPs are not an integral part of the kinetochore, but they localize to the kinetochore periodically throughout mitosis and regulate the strength of the kinetochore microtubule attachments. Here, we attempt to summarize the recent advances that have been made toward furthering our understanding of this co-operation between the Ndc80c and these MAPs, focusing on the spindle and kinetochore-associated 1 (Ska1) complex (Ska1c) and Cdc10-dependent transcript 1 (Cdt1) in humans.
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62
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Petty EL, Pillus L. Cell cycle roles for GCN5 revealed through genetic suppression. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2020; 1864:194625. [PMID: 32798737 DOI: 10.1016/j.bbagrm.2020.194625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 08/11/2020] [Accepted: 08/11/2020] [Indexed: 11/17/2022]
Abstract
The conserved acetyltransferase Gcn5 is a member of several complexes in eukaryotic cells, playing roles in regulating chromatin organization, gene expression, metabolism, and cell growth and differentiation via acetylation of both nuclear and cytoplasmic proteins. Distinct functions of Gcn5 have been revealed through a combination of biochemical and genetic approaches in many in vitro studies and model organisms. In this review, we focus on the unique insights that have been gleaned from suppressor studies of gcn5 phenotypes in the budding yeast Saccharomyces cerevisiae. Such studies were fundamental in the early understanding of the balance of counteracting chromatin activities in regulating transcription. Most recently, suppressor screens have revealed roles for Gcn5 in early cell cycle (G1 to S) gene expression and regulation of chromosome segregation during mitosis. Much has been learned, but many questions remain which will be informed by focused analysis of additional genetic and physical interactions.
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Affiliation(s)
- Emily L Petty
- University of California, San Diego, Division of Biological Sciences, Section of Molecular Biology, UCSD Moores Cancer Center, United States of America.
| | - Lorraine Pillus
- University of California, San Diego, Division of Biological Sciences, Section of Molecular Biology, UCSD Moores Cancer Center, United States of America.
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63
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Hara M, Fukagawa T. Dynamics of kinetochore structure and its regulations during mitotic progression. Cell Mol Life Sci 2020; 77:2981-2995. [PMID: 32052088 PMCID: PMC11104943 DOI: 10.1007/s00018-020-03472-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 12/27/2019] [Accepted: 01/28/2020] [Indexed: 12/12/2022]
Abstract
Faithful chromosome segregation during mitosis in eukaryotes requires attachment of the kinetochore, a large protein complex assembled on the centromere of each chromosome, to the spindle microtubules. The kinetochore is a structural interface for the microtubule attachment and provides molecular surveillance mechanisms that monitor and ensure the precise microtubule attachment as well, including error correction and spindle assembly checkpoint. During mitotic progression, the kinetochore undergoes dynamic morphological changes that are observable through electron microscopy as well as through fluorescence microscopy. These structural changes might be associated with the kinetochore function. In this review, we summarize how the dynamics of kinetochore morphology are associated with its functions and discuss recent findings on the switching of protein interaction networks in the kinetochore during cell cycle progression.
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Affiliation(s)
- Masatoshi Hara
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan.
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan.
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64
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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: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [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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65
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Benzi G, Piatti S. Killing two birds with one stone: how budding yeast Mps1 controls chromosome segregation and spindle assembly checkpoint through phosphorylation of a single kinetochore protein. Curr Genet 2020; 66:1037-1044. [PMID: 32632756 DOI: 10.1007/s00294-020-01091-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 06/23/2020] [Accepted: 06/25/2020] [Indexed: 12/11/2022]
Abstract
During mitosis, the identical sister chromatids of each chromosome must attach through their kinetochores to microtubules emanating from opposite spindle poles. This process, referred to as chromosome biorientation, is essential for equal partitioning of the genetic information to the two daughter cells. Defects in chromosome biorientation can give rise to aneuploidy, a hallmark of cancer and genetic diseases. A conserved surveillance mechanism called spindle assembly checkpoint (SAC) prevents the onset of anaphase until biorientation is attained. Key to chromosome biorientation is an error correction mechanism that allows kinetochores to establish proper bipolar attachments by disengaging faulty kinetochore-microtubule connections. Error correction relies on the Aurora B and Mps1 kinases that also promote SAC signaling, raising the possibility that they are part of a single sensory device responding to improper attachments and concomitantly controlling both their disengagement and a temporary mitotic arrest. In budding yeast, Aurora B and Mps1 promote error correction independently from one another, but while the substrates of Aurora B in this process are at least partially known, the mechanism underlying the involvement of Mps1 in the error correction pathway is unknown. Through the characterization of a novel mps1 mutant and an unbiased genetic screen for extragenic suppressors, we recently gained evidence that a common mechanism based on Mps1-dependent phosphorylation of the Knl1/Spc105 kinetochore scaffold and subsequent recruitment of the Bub1 kinase is critical for the function of Mps1 in chromosome biorientation as well as for SAC activation (Benzi et al. EMBO Rep, 2020).
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Affiliation(s)
- Giorgia Benzi
- CRBM, University of Montpellier, CNRS, 1919 Route de Mende, 34293, Montpellier, France
| | - Simonetta Piatti
- CRBM, University of Montpellier, CNRS, 1919 Route de Mende, 34293, Montpellier, France.
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66
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Ustinov NB, Korshunova AV, Gudimchuk NB. Protein Complex NDC80: Properties, Functions, and Possible Role in Pathophysiology of Cell Division. BIOCHEMISTRY (MOSCOW) 2020; 85:448-462. [PMID: 32569552 DOI: 10.1134/s0006297920040057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Mitotic division maintains genetic identity of any multicellular organism throughout an entire lifetime. Each time a parent cell divides, chromosomes are equally distributed between the daughter cells due to the action of mitotic spindle. Mitotic spindle is formed by the microtubules that represent dynamic polymers of tubulin protein. Spindle microtubules are attached end-on to kinetochores - large multi-protein complexes on chromosomes. This review focuses on the four-subunit NDC80 complex, one of the most important kinetochore elements that plays a major role in the attachment of assembling/disassembling microtubule ends to the chromosomes. Here, we summarize published data on the structure, properties, and regulation of the NDC80 complex and discuss possible relationship between changes in the expression of genes coding for the NDC80 complex components, mitotic disorders, and oncogenesis with special emphasis on the diagnostic and therapeutic potential of NDC80.
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Affiliation(s)
- N B Ustinov
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia
| | - A V Korshunova
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia.,Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia
| | - N B Gudimchuk
- Center for Theoretical Problems of Physico-Chemical Pharmacology, Russian Academy of Sciences, Moscow, 119991, Russia. .,Lomonosov Moscow State University, Faculty of Physics, Moscow, 119991, Russia
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67
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Hamilton GE, Helgeson LA, Noland CL, Asbury CL, Dimitrova YN, Davis TN. Reconstitution reveals two paths of force transmission through the kinetochore. eLife 2020; 9:56582. [PMID: 32406818 PMCID: PMC7367685 DOI: 10.7554/elife.56582] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 05/13/2020] [Indexed: 01/23/2023] Open
Abstract
Partitioning duplicated chromosomes equally between daughter cells is a microtubule-mediated process essential to eukaryotic life. A multi-protein machine, the kinetochore, drives chromosome segregation by coupling the chromosomes to dynamic microtubule tips, even as the tips grow and shrink through the gain and loss of subunits. The kinetochore must harness, transmit, and sense mitotic forces, as a lack of tension signals incorrect chromosome-microtubule attachment and precipitates error correction mechanisms. But though the field has arrived at a ‘parts list’ of dozens of kinetochore proteins organized into subcomplexes, the path of force transmission through these components has remained unclear. Here we report reconstitution of functional Saccharomyces cerevisiae kinetochore assemblies from recombinantly expressed proteins. The reconstituted kinetochores are capable of self-assembling in vitro, coupling centromeric nucleosomes to dynamic microtubules, and withstanding mitotically relevant forces. They reveal two distinct pathways of force transmission and Ndc80c recruitment.
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Affiliation(s)
- Grace E Hamilton
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Luke A Helgeson
- Department of Biochemistry, University of Washington, Seattle, United States
| | - Cameron L Noland
- Department of Structural Biology, Genentech Inc, South San Francisco, United States
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, United States
| | - Yoana N Dimitrova
- Department of Structural Biology, Genentech Inc, South San Francisco, United States
| | - Trisha N Davis
- Department of Biochemistry, University of Washington, Seattle, United States
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68
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Edelmaier C, Lamson AR, Gergely ZR, Ansari S, Blackwell R, McIntosh JR, Glaser MA, Betterton MD. Mechanisms of chromosome biorientation and bipolar spindle assembly analyzed by computational modeling. eLife 2020; 9:48787. [PMID: 32053104 PMCID: PMC7311174 DOI: 10.7554/elife.48787] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 02/12/2020] [Indexed: 01/19/2023] Open
Abstract
The essential functions required for mitotic spindle assembly and chromosome biorientation and segregation are not fully understood, despite extensive study. To illuminate the combinations of ingredients most important to align and segregate chromosomes and simultaneously assemble a bipolar spindle, we developed a computational model of fission-yeast mitosis. Robust chromosome biorientation requires progressive restriction of attachment geometry, destabilization of misaligned attachments, and attachment force dependence. Large spindle length fluctuations can occur when the kinetochore-microtubule attachment lifetime is long. The primary spindle force generators are kinesin-5 motors and crosslinkers in early mitosis, while interkinetochore stretch becomes important after biorientation. The same mechanisms that contribute to persistent biorientation lead to segregation of chromosomes to the poles after anaphase onset. This model therefore provides a framework to interrogate key requirements for robust chromosome biorientation, spindle length regulation, and force generation in the spindle. Before a cell divides, it must make a copy of its genetic material and then promptly split in two. This process, called mitosis, is coordinated by many different molecular machines. The DNA is copied, then the duplicated chromosomes line up at the middle of the cell. Next, an apparatus called the mitotic spindle latches onto the chromosomes before pulling them apart. The mitotic spindle is a bundle of long, thin filaments called microtubules. It attaches to chromosomes at the kinetochore, the point where two copied chromosomes are cinched together in their middle. Proper cell division is vital for the healthy growth of all organisms, big and small, and yet some parts of the process remain poorly understood despite extensive study. Specifically, there is more to learn about how the mitotic spindle self-assembles, and how microtubules and kinetochores work together to correctly orient and segregate chromosomes into two sister cells. These nanoscale processes are happening a hundred times a minute, so computer simulations are a good way to test what we know. Edelmaier et al. developed a computer model to simulate cell division in fission yeast, a species of yeast often used to study fundamental processes in the cell. The model simulates how the mitotic spindle assembles, how its microtubules attach to the kinetochore and the force required to pull two sister chromosomes apart. Building the simulation involved modelling interactions between the mitotic spindle and kinetochore, their movement and forces applied. To test its accuracy, model simulations were compared to recordings of the mitotic spindle – including its length, structure and position – imaged from dividing yeast cells. Running the simulation, Edelmaier et al. found that several key effects are essential for the proper movement of chromosomes in mitosis. This includes holding chromosomes in the correct orientation as the mitotic spindle assembles and controlling the relative position of microtubules as they attach to the kinetochore. Misaligned attachments must also be readily deconstructed and corrected to prevent any errors. The simulations also showed that kinetochores must begin to exert more force (to separate the chromosomes) once the mitotic spindle is attached correctly. Altogether, these findings improve the current understanding of how the mitotic spindle and its counterparts control cell division. Errors in chromosome segregation are associated with birth defects and cancer in humans, and this new simulation could potentially now be used to help make predictions about how to correct mistakes in the process.
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Affiliation(s)
| | - Adam R Lamson
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Zachary R Gergely
- Department of Physics, University of Colorado Boulder, Boulder, United States.,Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
| | - Saad Ansari
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Robert Blackwell
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - J Richard McIntosh
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
| | - Matthew A Glaser
- Department of Physics, University of Colorado Boulder, Boulder, United States
| | - Meredith D Betterton
- Department of Physics, University of Colorado Boulder, Boulder, United States.,Department of Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, United States
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69
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Chen J, Liao A, Powers EN, Liao H, Kohlstaedt LA, Evans R, Holly RM, Kim JK, Jovanovic M, Ünal E. Aurora B-dependent Ndc80 degradation regulates kinetochore composition in meiosis. Genes Dev 2020; 34:209-225. [PMID: 31919192 PMCID: PMC7000919 DOI: 10.1101/gad.333997.119] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 12/12/2019] [Indexed: 12/24/2022]
Abstract
The kinetochore complex is a conserved machinery that connects chromosomes to spindle microtubules. During meiosis, the kinetochore is restructured to accommodate a specialized chromosome segregation pattern. In budding yeast, meiotic kinetochore remodeling is mediated by the temporal changes in the abundance of a single subunit called Ndc80. We previously described the regulatory events that control the timely synthesis of Ndc80. Here, we report that Ndc80 turnover is also tightly regulated in meiosis: Ndc80 degradation is active in meiotic prophase, but not in metaphase I. Ndc80 degradation depends on the ubiquitin ligase APCAma1 and is mediated by the proteasome. Importantly, Aurora B-dependent Ndc80 phosphorylation, a mark that has been previously implicated in correcting erroneous microtubule-kinetochore attachments, is essential for Ndc80 degradation in a microtubule-independent manner. The N terminus of Ndc80, including a 27-residue sequence and Aurora B phosphorylation sites, is both necessary and sufficient for kinetochore protein degradation. Finally, defects in Ndc80 turnover predispose meiotic cells to chromosome mis-segregation. Our study elucidates the mechanism by which meiotic cells modulate their kinetochore composition through regulated Ndc80 degradation, and demonstrates that Aurora B-dependent regulation of kinetochores extends beyond altering microtubule attachments.
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Affiliation(s)
- Jingxun Chen
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Andrew Liao
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Emily N Powers
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Hanna Liao
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Lori A Kohlstaedt
- UC Berkeley QB3 Proteomics Facility, University of California at Berkeley, Berkeley, California 94720, USA
| | - Rena Evans
- Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Ryan M Holly
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Jenny Kim Kim
- Department of Biology, Columbia University, New York City, New York 10027, USA
| | - Marko Jovanovic
- Department of Biology, Columbia University, New York City, New York 10027, USA
| | - Elçin Ünal
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
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70
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Huis In 't Veld PJ, Volkov VA, Stender ID, Musacchio A, Dogterom M. Molecular determinants of the Ska-Ndc80 interaction and their influence on microtubule tracking and force-coupling. eLife 2019; 8:49539. [PMID: 31804178 PMCID: PMC6927755 DOI: 10.7554/elife.49539] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 11/26/2019] [Indexed: 12/12/2022] Open
Abstract
Errorless chromosome segregation requires load-bearing attachments of the plus ends of spindle microtubules to chromosome structures named kinetochores. How these end-on kinetochore attachments are established following initial lateral contacts with the microtubule lattice is poorly understood. Two microtubule-binding complexes, the Ndc80 and Ska complexes, are important for efficient end-on coupling and may function as a unit in this process, but precise conditions for their interaction are unknown. Here, we report that the Ska-Ndc80 interaction is phosphorylation-dependent and does not require microtubules, applied force, or several previously identified functional determinants including the Ndc80-loop and the Ndc80-tail. Both the Ndc80-tail, which we reveal to be essential for microtubule end-tracking, and Ndc80-bound Ska stabilize microtubule ends in a stalled conformation. Modulation of force-coupling efficiency demonstrates that the duration of stalled microtubule disassembly predicts whether a microtubule is stabilized and rescued by the kinetochore, likely reflecting a structural transition of the microtubule end.
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Affiliation(s)
- Pim J Huis In 't Veld
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Vladimir A Volkov
- Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
| | - Isabelle D Stender
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.,Centre for Medical Biotechnology, Faculty of Biology, University Duisburg, Essen, Germany
| | - Marileen Dogterom
- Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
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71
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Roy B, Verma V, Sim J, Fontan A, Joglekar AP. Delineating the contribution of Spc105-bound PP1 to spindle checkpoint silencing and kinetochore microtubule attachment regulation. J Cell Biol 2019; 218:3926-3942. [PMID: 31649151 PMCID: PMC6891095 DOI: 10.1083/jcb.201810172] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 06/19/2019] [Accepted: 09/18/2019] [Indexed: 02/01/2023] Open
Abstract
Roy et al. highlight a harmful cross-talk that can arise between spindle assembly checkpoint silencing and chromosome biorientation due to the involvement of protein phosphatase 1 in both the processes. Accurate chromosome segregation during cell division requires the spindle assembly checkpoint (SAC), which detects unattached kinetochores, and an error correction mechanism that destabilizes incorrect kinetochore–microtubule attachments. While the SAC and error correction are both regulated by protein phosphatase 1 (PP1), which silences the SAC and stabilizes kinetochore–microtubule attachments, how these distinct PP1 functions are coordinated remains unclear. Here, we investigate the contribution of PP1, docked on its conserved kinetochore receptor Spc105/Knl1, to SAC silencing and attachment regulation. We find that Spc105-bound PP1 is critical for SAC silencing but dispensable for error correction; in fact, reduced PP1 docking on Spc105 improved chromosome segregation and viability of mutant/stressed states. We additionally show that artificially recruiting PP1 to Spc105/Knl1 before, but not after, chromosome biorientation interfered with error correction. These observations lead us to propose that recruitment of PP1 to Spc105/Knl1 is carefully regulated to ensure that chromosome biorientation precedes SAC silencing, thereby ensuring accurate chromosome segregation.
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Affiliation(s)
- Babhrubahan Roy
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Vikash Verma
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Janice Sim
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Adrienne Fontan
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI
| | - Ajit P Joglekar
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI .,Department of Biophysics, University of Michigan, Ann Arbor, MI
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72
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Campbell S, Amin MA, Varma D, Bidone TC. Computational model demonstrates that Ndc80-associated proteins strengthen kinetochore-microtubule attachments in metaphase. Cytoskeleton (Hoboken) 2019; 76:549-561. [PMID: 31525284 DOI: 10.1002/cm.21562] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 08/30/2019] [Accepted: 09/05/2019] [Indexed: 01/22/2023]
Abstract
Chromosome segregation is mediated by spindle microtubules that attach to the kinetochore via dynamic protein complexes, such as Ndc80, Ska, Cdt1 and ch-TOG during mitotic metaphase. While experimental studies have previously shown that these proteins and protein complexes are all essential for maintaining a stable kinetochore-microtubule (kMT) interface, their exact roles in the mitotic metaphase remains elusive. In this study, we employed experimental and computational methods in order to characterize how these proteins can strengthen kMT attachments in both nonload-bearing and load-bearing conditions, typical of prometaphase and metaphase, respectively. Immunofluorescence staining of HeLa cells showed that the levels of Ska and Cdt1 significantly increased from prometaphase to metaphase, while levels of the Ndc80 complex remained unchanged. Our new computational model showed that by incorporating binding and unbinding of each protein complex coupled with a biased diffusion mechanism, the displacement of a possible complex formed by Ndc80-Ska-Cdt1 is significantly higher than that of Ndc80 alone or Ndc80-Ska. In addition, when we incorporate Ndc80/ch-TOG in the model, rupture force and time of attachment of the kMT interface increases. These results support the hypothesis that Ndc80-associated proteins strengthen kMT attachments, and that the interplay between kMT protein complexes in metaphase ensures stable attachments.
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Affiliation(s)
- Samuel Campbell
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah
| | - Mohammed A Amin
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Dileep Varma
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Tamara C Bidone
- Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah.,Scientific Computing and Imaging Institute, University of Utah, Salt Lake City, Utah.,School of Computing, University of Utah, Salt Lake City, Utah
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73
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Drechsler H, Xu Y, Geyer VF, Zhang Y, Diez S. Multivalent electrostatic microtubule interactions of synthetic peptides are sufficient to mimic advanced MAP-like behavior. Mol Biol Cell 2019; 30:2953-2968. [PMID: 31599700 PMCID: PMC6857568 DOI: 10.1091/mbc.e19-05-0247] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Microtubule-associated proteins (MAPs) are a functionally highly diverse class of proteins that help to adjust the shape and function of the microtubule cytoskeleton in space and time. For this purpose, MAPs structurally support microtubules, modulate their dynamic instability, or regulate the activity of associated molecular motors. The microtubule-binding domains of MAPs are structurally divergent, but often depend on electrostatic interactions with the negatively charged surface of the microtubule. This suggests that the surface exposure of positive charges rather than a certain structural fold is sufficient for a protein to associate with microtubules. Consistently, positively charged artificial objects have been shown to associate with microtubules and to diffuse along their lattice. Natural MAPs, however, show a more sophisticated functionality beyond lattice-diffusion. Here, we asked whether basic electrostatic interactions are sufficient to also support advanced MAP functionality. To test this hypothesis, we studied simple positively charged peptide sequences for the occurrence of typical MAP-like behavior. We found that a multivalent peptide construct featuring four lysine-alanine heptarepeats (starPEG-(KA7)4)-but not its monovalent KA7-subunits-show advanced, biologically relevant MAP-like behavior: starPEG-(KA7)4 binds microtubules in the low nanomolar range, diffuses along their lattice with the ability to switch between intersecting microtubules, and tracks depolymerizing microtubule ends. Further, starPEG-(KA7)4 promotes microtubule nucleation and growth, mediates depolymerization coupled pulling at plus ends, and bundles microtubules without significantly interfering with other proteins on the microtubule lattice (as exemplified by the motor kinesin-1). Our results show that positive charges and multivalency are sufficient to mimic advanced MAP-like behavior.
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Affiliation(s)
- Hauke Drechsler
- B CUBE-Center for Molecular Bioengineering, Technische -Universität -Dresden, Dresden 01307, Germany
| | - Yong Xu
- B CUBE-Center for Molecular Bioengineering, Technische -Universität -Dresden, Dresden 01307, Germany
| | - Veikko F Geyer
- B CUBE-Center for Molecular Bioengineering, Technische -Universität -Dresden, Dresden 01307, Germany
| | - Yixin Zhang
- B CUBE-Center for Molecular Bioengineering, Technische -Universität -Dresden, Dresden 01307, Germany
| | - Stefan Diez
- B CUBE-Center for Molecular Bioengineering, Technische -Universität -Dresden, Dresden 01307, Germany.,Cluster of Excellence Physics of Life, Technische -Universität -Dresden, Dresden 01307, Germany.,Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany
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74
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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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75
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Amin MA, Agarwal S, Varma D. Mapping the kinetochore MAP functions required for stabilizing microtubule attachments to chromosomes during metaphase. Cytoskeleton (Hoboken) 2019; 76:398-412. [PMID: 31454167 DOI: 10.1002/cm.21559] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 08/07/2019] [Accepted: 08/22/2019] [Indexed: 12/24/2022]
Abstract
In mitosis, faithful chromosome segregation is orchestrated by the dynamic interactions between the spindle microtubules (MTs) emanating from the opposite poles and the kinetochores of the chromosomes. However, the precise mechanism that coordinates the coupling of the kinetochore components to dynamic MTs has been a long-standing question. Microtubule-associated proteins (MAPs) regulate MT nucleation and dynamics, MT-mediated transport and MT cross-linking in cells. During mitosis, MAPs play an essential role not only in determining spindle length, position, and orientation but also in facilitating robust kinetochore-microtubule (kMT) attachments by linking the kinetochores to spindle MTs efficiently. The stability of MTs imparted by the MAPs is critical to ensure accurate chromosome segregation. This review primarily focuses on the specific function of nonmotor kinetochore MAPs, their recruitment to kinetochores and their MT-binding properties. We also attempt to synthesize and strengthen our understanding of how these MAPs work in coordination with the kinetochore-bound Ndc80 complex (the key component at the MT-binding interface in metaphase and anaphase) to establish stable kMT attachments and control accurate chromosome segregation during mitosis.
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Affiliation(s)
- Mohammed A Amin
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Shivangi Agarwal
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
| | - Dileep Varma
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois
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76
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Autophosphorylation is sufficient to release Mps1 kinase from native kinetochores. Proc Natl Acad Sci U S A 2019; 116:17355-17360. [PMID: 31405987 DOI: 10.1073/pnas.1901653116] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Accurate mitosis depends on a surveillance system called the spindle assembly checkpoint. This checkpoint acts at kinetochores, which attach chromosomes to the dynamic tips of spindle microtubules. When a kinetochore is unattached or improperly attached, the protein kinase Mps1 phosphorylates kinetochore components, catalyzing the generation of a diffusible "wait" signal that delays anaphase and gives the cell time to correct the error. When a kinetochore becomes properly attached, its checkpoint signal is silenced to allow progression into anaphase. Recently, microtubules were found to compete directly against recombinant human Mps1 fragments for binding to the major microtubule-binding kinetochore element Ndc80c, suggesting a direct competition model for silencing the checkpoint signal at properly attached kinetochores. Here, by developing single-particle fluorescence-based assays, we tested whether such direct competition occurs in the context of native kinetochores isolated from yeast. Mps1 levels were not reduced on kinetochore particles bound laterally to the sides of microtubules or on particles tracking processively with disassembling tips. Instead, we found that Mps1 kinase activity was sufficient to promote its release from the isolated kinetochores. Mps1 autophosphorylation, rather than phosphorylation of other kinetochore components, was responsible for this dissociation. Our findings suggest that checkpoint silencing in yeast does not arise from a direct competition between Mps1 and microtubules, and that phosphoregulation of Mps1 may be a critical aspect of the silencing mechanism.
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77
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Cherry AE, Vicente JJ, Xu C, Morrison RS, Ong SE, Wordeman L, Stella N. GPR124 regulates microtubule assembly, mitotic progression, and glioblastoma cell proliferation. Glia 2019; 67:1558-1570. [PMID: 31058365 PMCID: PMC6557680 DOI: 10.1002/glia.23628] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Revised: 03/25/2019] [Accepted: 04/05/2019] [Indexed: 01/26/2023]
Abstract
GPR124 is involved in embryonic development and remains expressed by select organs. The importance of GPR124 during development suggests that its aberrant expression might participate in tumor growth. Here we show that both increases and decreases in GPR124 expression in glioblastoma cells reduce cell proliferation by differentially altering the duration mitotic progression. Using mass spectrometry-based proteomics, we discovered that GPR124 interacts with ch-TOG, a known regulator of both microtubule (MT)-plus-end assembly and mitotic progression. Accordingly, changes in GPR124 expression and ch-TOG similarly affect MT assembly measured by real-time microscopy in cells. Our study describes a novel molecular interaction involving GPR124 and ch-TOG at the plasma membrane that controls glioblastoma cell proliferation by modifying MT assembly rates and controlling the progression of distinct phases of mitosis.
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Affiliation(s)
- Allison E. Cherry
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - Juan Jesus Vicente
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington
| | - Cong Xu
- Department of Pharmacology, University of Washington, Seattle, Washington
| | | | - Shao-En Ong
- Department of Pharmacology, University of Washington, Seattle, Washington
| | - Linda Wordeman
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington
| | - Nephi Stella
- Department of Pharmacology, University of Washington, Seattle, Washington
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington
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78
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Guérin TM, Béneut C, Barinova N, López V, Lazar-Stefanita L, Deshayes A, Thierry A, Koszul R, Dubrana K, Marcand S. Condensin-Mediated Chromosome Folding and Internal Telomeres Drive Dicentric Severing by Cytokinesis. Mol Cell 2019; 75:131-144.e3. [PMID: 31204167 DOI: 10.1016/j.molcel.2019.05.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 02/12/2019] [Accepted: 05/13/2019] [Indexed: 12/13/2022]
Abstract
In Saccharomyces cerevisiae, dicentric chromosomes stemming from telomere fusions preferentially break at the fusion. This process restores a normal karyotype and protects chromosomes from the detrimental consequences of accidental fusions. Here, we address the molecular basis of this rescue pathway. We observe that tandem arrays tightly bound by the telomere factor Rap1 or a heterologous high-affinity DNA binding factor are sufficient to establish breakage hotspots, mimicking telomere fusions within dicentrics. We also show that condensins generate forces sufficient to rapidly refold dicentrics prior to breakage by cytokinesis and are essential to the preferential breakage at telomere fusions. Thus, the rescue of fused telomeres results from a condensin- and Rap1-driven chromosome folding that favors fusion entrapment where abscission takes place. Because a close spacing between the DNA-bound Rap1 molecules is essential to this process, Rap1 may act by stalling condensins.
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Affiliation(s)
- Thomas M Guérin
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Claire Béneut
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Natalja Barinova
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Virginia López
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Luciana Lazar-Stefanita
- Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS UMR 3525, Sorbonne Université, Paris, France
| | - Alice Deshayes
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Agnès Thierry
- Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS UMR 3525, Sorbonne Université, Paris, France
| | - Romain Koszul
- Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS UMR 3525, Sorbonne Université, Paris, France
| | - Karine Dubrana
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Stéphane Marcand
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France.
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79
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French BT, Straight AF. The Power of Xenopus Egg Extract for Reconstitution of Centromere and Kinetochore Function. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2019; 56:59-84. [PMID: 28840233 DOI: 10.1007/978-3-319-58592-5_3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Faithful transmission of genetic information during cell division requires attachment of chromosomes to the mitotic spindle via the kinetochore. In vitro reconstitution studies are beginning to uncover how the kinetochore is assembled upon the underlying centromere, how the kinetochore couples chromosome movement to microtubule dynamics, and how cells ensure the site of kinetochore assembly is maintained from one generation to the next. Here we give special emphasis to advances made in Xenopus egg extract, which provides a unique, biochemically tractable in vitro system that affords the complexity of cytoplasm and nucleoplasm to permit reconstitution of the dynamic, cell cycle-regulated functions of the centromere and kinetochore.
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Affiliation(s)
- Bradley T French
- Department of Biochemistry, Stanford University, 279 Campus Drive, Beckman 409, Stanford, CA, 94305, USA
| | - Aaron F Straight
- Department of Biochemistry, Stanford University, 279 Campus Drive, Beckman 409, Stanford, CA, 94305, USA.
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80
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Mukherjee S, Sandri BJ, Tank D, McClellan M, Harasymiw LA, Yang Q, Parker LL, Gardner MK. A Gradient in Metaphase Tension Leads to a Scaled Cellular Response in Mitosis. Dev Cell 2019; 49:63-76.e10. [PMID: 30799228 PMCID: PMC6535804 DOI: 10.1016/j.devcel.2019.01.018] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 11/20/2018] [Accepted: 01/21/2019] [Indexed: 12/27/2022]
Abstract
During mitosis, motor proteins associate with microtubules to exert pushing forces that establish a mitotic spindle. These pushing forces generate opposing tension in the chromatin that connects oppositely attached sister chromatids, which may then act as a mechanical signal to ensure the fidelity of chromosome segregation during mitosis. However, the role of tension in mitotic cellular signaling remains controversial. In this study, we generated a gradient in tension over multiple isogenic budding yeast cell lines by genetically altering the magnitude of motor-based spindle forces. We found that a decreasing gradient in tension led to an increasing gradient in the rates of kinetochore detachment and anaphase chromosome mis-segregration, and in metaphase time. Simulations and experiments indicated that these tension responses originate from a tension-dependent kinetochore phosphorylation gradient. We conclude that the cell is exquisitely tuned to the magnitude of tension as a signal to detect potential chromosome segregation errors during mitosis.
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Affiliation(s)
- Soumya Mukherjee
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brian J Sandri
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Damien Tank
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Mark McClellan
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Lauren A Harasymiw
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Qing Yang
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Laurie L Parker
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Melissa K Gardner
- Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, MN 55455, USA.
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81
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Funabiki H. Correcting aberrant kinetochore microtubule attachments: a hidden regulation of Aurora B on microtubules. Curr Opin Cell Biol 2019; 58:34-41. [PMID: 30684807 DOI: 10.1016/j.ceb.2018.12.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 12/16/2018] [Indexed: 01/06/2023]
Abstract
For equal chromosome segregation, a pair of kinetochores on each duplicated chromosome must attach to microtubules connecting to opposite poles. The protein kinase Aurora B plays a critical role in destabilizing microtubules attached in a wrong orientation through phosphorylating kinetochore proteins. The mechanism behind this selective destabilization of aberrant attachments remains elusive. While Aurora B is most enriched on the centromere from prophase to metaphase, emerging evidence suggests the importance of Aurora B on microtubules in this process. Here I discuss two hypothetical models that could explain the requirement of Aurora B on microtubules for selective destabilization of aberrant attachments; microtubule-induced substrate masking and treadmill-removal of Aurora B on microtubules proximal to polymerizing ends.
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Affiliation(s)
- Hironori Funabiki
- Laboratory of Chromosome and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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82
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Edwards F, Maton G, Gareil N, Canman JC, Dumont J. BUB-1 promotes amphitelic chromosome biorientation via multiple activities at the kinetochore. eLife 2018; 7:40690. [PMID: 30547880 PMCID: PMC6303103 DOI: 10.7554/elife.40690] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 12/13/2018] [Indexed: 12/03/2022] Open
Abstract
Accurate chromosome segregation relies on bioriented amphitelic attachments of chromosomes to microtubules of the mitotic spindle, in which sister chromatids are connected to opposite spindle poles. BUB-1 is a protein of the Spindle Assembly Checkpoint (SAC) that coordinates chromosome attachment with anaphase onset. BUB-1 is also required for accurate sister chromatid segregation independently of its SAC function, but the underlying mechanism remains unclear. Here we show that, in Caenorhabditis elegans embryos, BUB-1 accelerates the establishment of non-merotelic end-on kinetochore-microtubule attachments by recruiting the RZZ complex and its downstream partner dynein-dynactin at the kinetochore. In parallel, BUB-1 limits attachment maturation by the SKA complex. This activity opposes kinetochore-microtubule attachment stabilisation promoted by CLS-2CLASP-dependent kinetochore-microtubule assembly. BUB-1 is therefore a SAC component that coordinates the function of multiple downstream kinetochore-associated proteins to ensure accurate chromosome segregation.
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Affiliation(s)
- Frances Edwards
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Gilliane Maton
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Nelly Gareil
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University, New York, United States
| | - Julien Dumont
- Institut Jacques Monod, CNRS, UMR 7592, University Paris Diderot, Sorbonne Paris Cité, Paris, France
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83
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Nithianantham S, Cook BD, Beans M, Guo F, Chang F, Al-Bassam J. Structural basis of tubulin recruitment and assembly by microtubule polymerases with tumor overexpressed gene (TOG) domain arrays. eLife 2018; 7:38922. [PMID: 30422110 PMCID: PMC6251626 DOI: 10.7554/elife.38922] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 10/31/2018] [Indexed: 12/21/2022] Open
Abstract
XMAP215/Stu2/Alp14 proteins accelerate microtubule plus-end polymerization by recruiting tubulins via arrays of tumor overexpressed gene (TOG) domains, yet their mechanism remains unknown. Here, we describe the biochemical and structural basis for TOG arrays in recruiting and polymerizing tubulins. Alp14 binds four tubulins via dimeric TOG1-TOG2 subunits, in which each domain exhibits a distinct exchange rate for tubulin. X-ray structures revealed square-shaped assemblies composed of pseudo-dimeric TOG1-TOG2 subunits assembled head-to-tail, positioning four unpolymerized tubulins in a polarized wheel-like configuration. Crosslinking and electron microscopy show Alp14-tubulin forms square assemblies in solution, and inactivating their interfaces destabilize this organization without influencing tubulin binding. An X-ray structure determined using approach to modulate tubulin polymerization revealed an unfurled assembly, in which TOG1-TOG2 uniquely bind to two polymerized tubulins. Our findings suggest a new microtubule polymerase model in which TOG arrays recruit tubulins by forming square assemblies that then unfurl, facilitating their concerted polymerization into protofilaments.
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Affiliation(s)
- Stanley Nithianantham
- Molecular Cellular Biology Department, University of California, Davis, United States
| | - Brian D Cook
- Molecular Cellular Biology Department, University of California, Davis, United States
| | - Madeleine Beans
- Molecular Cellular Biology Department, University of California, Davis, United States
| | - Fei Guo
- Molecular Cellular Biology Department, University of California, Davis, United States
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, United States
| | - Jawdat Al-Bassam
- Molecular Cellular Biology Department, University of California, Davis, United States
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84
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Ti SC, Alushin GM, Kapoor TM. Human β-Tubulin Isotypes Can Regulate Microtubule Protofilament Number and Stability. Dev Cell 2018; 47:175-190.e5. [PMID: 30245156 DOI: 10.1016/j.devcel.2018.08.014] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 06/28/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022]
Abstract
Cell biological studies have shown that protofilament number, a fundamental feature of microtubules, can correlate with the expression of different tubulin isotypes. However, it is not known if tubulin isotypes directly control this basic microtubule property. Here, we report high-resolution cryo-EM reconstructions (3.5-3.65 Å) of purified human α1B/β3 and α1B/β2B microtubules and find that the β-tubulin isotype can determine protofilament number. Comparisons of atomic models of 13- and 14-protofilament microtubules reveal how tubulin subunit plasticity, manifested in "accordion-like" distributed structural changes, can accommodate distinct lattice organizations. Furthermore, compared to α1B/β3 microtubules, α1B/β2B filaments are more stable to passive disassembly and against depolymerization by MCAK or chTOG, microtubule-associated proteins with distinct mechanisms of action. Mixing tubulin isotypes in different proportions results in microtubules with protofilament numbers and stabilities intermediate to those of isotypically pure filaments. Together, our findings indicate that microtubule protofilament number and stability can be controlled through β-tubulin isotype composition.
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Affiliation(s)
- Shih-Chieh Ti
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Gregory M Alushin
- Laboratory of Structural Biophysics and Mechanobiology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
| | - Tarun M Kapoor
- Laboratory of Chemistry and Cell Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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85
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Llauró A, Hayashi H, Bailey ME, Wilson A, Ludzia P, Asbury CL, Akiyoshi B. The kinetoplastid kinetochore protein KKT4 is an unconventional microtubule tip-coupling protein. J Cell Biol 2018; 217:3886-3900. [PMID: 30209069 PMCID: PMC6219724 DOI: 10.1083/jcb.201711181] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 07/23/2018] [Accepted: 08/24/2018] [Indexed: 01/08/2023] Open
Abstract
The evolutionarily divergent class of kinetoplastid organisms has a set of unconventional kinetochore proteins that drive chromosome segregation, but it is unclear which components interact with spindle microtubules. Llauró et al. now identify KKT4 as the first microtubule-binding kinetochore protein in Trypanosoma brucei, a major human pathogenic parasite. Kinetochores are multiprotein machines that drive chromosome segregation by maintaining persistent, load-bearing linkages between chromosomes and dynamic microtubule tips. Kinetochores in commonly studied eukaryotes bind microtubules through widely conserved components like the Ndc80 complex. However, in evolutionarily divergent kinetoplastid species such as Trypanosoma brucei, which causes sleeping sickness, the kinetochores assemble from a unique set of proteins lacking homology to any known microtubule-binding domains. Here, we show that the T. brucei kinetochore protein KKT4 binds directly to microtubules and maintains load-bearing attachments to both growing and shortening microtubule tips. The protein localizes both to kinetochores and to spindle microtubules in vivo, and its depletion causes defects in chromosome segregation. We define a microtubule-binding domain within KKT4 and identify several charged residues important for its microtubule-binding activity. Thus, despite its lack of significant similarity to other known microtubule-binding proteins, KKT4 has key functions required for driving chromosome segregation. We propose that it represents a primary element of the kinetochore–microtubule interface in kinetoplastids.
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Affiliation(s)
- Aida Llauró
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Hanako Hayashi
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Megan E Bailey
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Alex Wilson
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Patryk Ludzia
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, UK
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86
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Suzuki A, Gupta A, Long SK, Evans R, Badger BL, Salmon ED, Biggins S, Bloom K. A Kinesin-5, Cin8, Recruits Protein Phosphatase 1 to Kinetochores and Regulates Chromosome Segregation. Curr Biol 2018; 28:2697-2704.e3. [PMID: 30174190 DOI: 10.1016/j.cub.2018.08.038] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 08/02/2018] [Accepted: 08/16/2018] [Indexed: 01/03/2023]
Abstract
Kinesin-5 is a highly conserved homo-tetrameric protein complex responsible for crosslinking microtubules and pushing spindle poles apart. The budding yeast Kinesin-5, Cin8, is highly concentrated at kinetochores in mitosis before anaphase, but its functions there are largely unsolved. Here, we show that Cin8 localizes to kinetochores in a cell-cycle-dependent manner and concentrates near the microtubule binding domains of Ndc80 at metaphase. Cin8's kinetochore localization depends on the Ndc80 complex, kinetochore microtubules, and the Dam1 complex. Consistent with its kinetochore localization, a Cin8 deletion induces a loss of tension at the Ndc80 microtubule binding domains and a major delay in mitotic progression. Cin8 associates with Protein Phosphatase 1 (PP1), and mutants that inhibit its PP1 binding also induce a loss of tension at the Ndc80 microtubule binding domains and delay mitotic progression. Taken together, our results suggest that Cin8-PP1 plays a critical role at kinetochores to promote accurate chromosome segregation by controlling Ndc80 attachment to microtubules.
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Affiliation(s)
- Aussie Suzuki
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA; McArdle Laboratory for Cancer Research, Department of Oncology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA.
| | - Amitabha Gupta
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Sarah K Long
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Rena Evans
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
| | - Benjamin L Badger
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Edward D Salmon
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA.
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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87
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Lang J, Barber A, Biggins S. An assay for de novo kinetochore assembly reveals a key role for the CENP-T pathway in budding yeast. eLife 2018; 7:37819. [PMID: 30117803 PMCID: PMC6097842 DOI: 10.7554/elife.37819] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 08/06/2018] [Indexed: 01/25/2023] Open
Abstract
Chromosome segregation depends on the kinetochore, the machine that establishes force-bearing attachments between DNA and spindle microtubules. Kinetochores are formed every cell cycle via a highly regulated process that requires coordinated assembly of multiple subcomplexes on specialized chromatin. To elucidate the underlying mechanisms, we developed an assay to assemble kinetochores de novo using centromeric DNA and budding yeast extracts. Assembly is enhanced by mitotic phosphorylation of the Dsn1 kinetochore protein and generates kinetochores capable of binding microtubules. We used this assay to investigate why kinetochores recruit the microtubule-binding Ndc80 complex via two receptors: the Mis12 complex and CENP-T. Although the CENP-T pathway is non-essential in yeast, we demonstrate that it becomes essential for viability and Ndc80c recruitment when the Mis12 pathway is crippled by defects in Dsn1 phosphorylation. Assembling kinetochores de novo in yeast extracts provides a powerful and genetically tractable method to elucidate critical regulatory events in the future.
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Affiliation(s)
- Jackie Lang
- Division of Basic Sciences, Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Program, University of Washington, Seattle, United States
| | - Adrienne Barber
- Division of Basic Sciences, Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Sue Biggins
- Division of Basic Sciences, Howard Hughes Medical Institute, Fred Hutchinson Cancer Research Center, Seattle, United States
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88
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Joglekar AP, Kukreja AA. How Kinetochore Architecture Shapes the Mechanisms of Its Function. Curr Biol 2018; 27:R816-R824. [PMID: 28829971 DOI: 10.1016/j.cub.2017.06.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The eukaryotic kinetochore is a sophisticated multi-protein machine that segregates chromosomes during cell division. To ensure accurate chromosome segregation, it performs three major functions using disparate molecular mechanisms. It operates a mechanosensitive signaling cascade known as the spindle assembly checkpoint (SAC) to detect and signal the lack of attachment to spindle microtubules, and delay anaphase onset in response. In addition, after attaching to spindle microtubules, the kinetochore generates the force necessary to move chromosomes. Finally, if the two sister kinetochores on a chromosome are both attached to microtubules emanating from the same spindle pole, they activate another mechanosensitive mechanism to correct the monopolar attachments. All three of these functions maintain genome stability during cell division. The outlines of the biochemical activities responsible for these functions are now available. How the kinetochore integrates the underlying molecular mechanisms is still being elucidated. In this Review, we discuss how the nanoscale protein organization in the kinetochore, which we refer to as kinetochore 'architecture', organizes its biochemical activities to facilitate the realization and integration of emergent mechanisms underlying its three major functions. For this discussion, we will use the relatively simple budding yeast kinetochore as a model, and extrapolate insights gained from this model to elucidate functional roles of the architecture of the much more complex human kinetochore.
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Affiliation(s)
- Ajit P Joglekar
- Department of Cell & Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA; Department of Biophysics, University of Michigan, Ann Arbor, MI, USA.
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89
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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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90
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Abstract
Microtubules are dynamic polymers of αβ-tubulin that are essential for intracellular organization, organelle trafficking and chromosome segregation. Microtubule growth and shrinkage occur via addition and loss of αβ-tubulin subunits, which are biochemical processes. Dynamic microtubules can also engage in mechanical processes, such as exerting forces by pushing or pulling against a load. Recent advances at the intersection of biochemistry and mechanics have revealed the existence of multiple conformations of αβ-tubulin subunits and their central role in dictating the mechanisms of microtubule dynamics and force generation. It has become apparent that microtubule-associated proteins (MAPs) selectively target specific tubulin conformations to regulate microtubule dynamics, and mechanical forces can also influence microtubule dynamics by altering the balance of tubulin conformations. Importantly, the conformational states of tubulin dimers are likely to be coupled throughout the lattice: the conformation of one dimer can influence the conformation of its nearest neighbours, and this effect can propagate over longer distances. This coupling provides a long-range mechanism by which MAPs and forces can modulate microtubule growth and shrinkage. These findings provide evidence that the interplay between biochemistry and mechanics is essential for the cellular functions of microtubules.
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Affiliation(s)
- Gary J Brouhard
- Department of Biology, McGill University, Montréal, Quebec, Canada.
| | - Luke M Rice
- Department of Biophysics, University of Texas Southwestern, Dallas, TX, USA.
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91
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Geyer EA, Miller MP, Brautigam CA, Biggins S, Rice LM. Design principles of a microtubule polymerase. eLife 2018; 7:34574. [PMID: 29897335 PMCID: PMC5999394 DOI: 10.7554/elife.34574] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/10/2018] [Indexed: 11/16/2022] Open
Abstract
Stu2/XMAP215 microtubule polymerases use multiple tubulin-binding TOG domains and a lattice-binding basic region to processively promote faster elongation. How the domain composition and organization of these proteins dictate polymerase activity, end localization, and processivity is unknown. We show that polymerase activity does not require different kinds of TOGs, nor are there strict requirements for how the TOGs are linked. We identify an unexpected antagonism between the tubulin-binding TOGs and the lattice-binding basic region: lattice binding by the basic region is weak when at least two TOGs engage tubulins, strong when TOGs are empty. End-localization of Stu2 requires unpolymerized tubulin, at least two TOGs, and polymerase competence. We propose a ‘ratcheting’ model for processivity: transfer of tubulin from TOGs to the lattice activates the basic region, retaining the polymerase at the end for subsequent rounds of tubulin binding and incorporation. These results clarify design principles of the polymerase.
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Affiliation(s)
- Elisabeth A Geyer
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, United States
| | - Matthew P Miller
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Chad A Brautigam
- Departments of Biophysics and Microbiology, UT Southwestern Medical Center, Dallas, United States
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States
| | - Luke M Rice
- Departments of Biophysics and Biochemistry, UT Southwestern Medical Center, Dallas, United States
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92
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Dudka D, Noatynska A, Smith CA, Liaudet N, McAinsh AD, Meraldi P. Complete microtubule-kinetochore occupancy favours the segregation of merotelic attachments. Nat Commun 2018; 9:2042. [PMID: 29795284 PMCID: PMC5966435 DOI: 10.1038/s41467-018-04427-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 04/30/2018] [Indexed: 12/03/2022] Open
Abstract
Kinetochores are multi-protein complexes that power chromosome movements by tracking microtubules plus-ends in the mitotic spindle. Human kinetochores bind up to 20 microtubules, even though single microtubules can generate sufficient force to move chromosomes. Here, we show that high microtubule occupancy at kinetochores ensures robust chromosome segregation by providing a strong mechanical force that favours segregation of merotelic attachments during anaphase. Using low doses of the microtubules-targeting agent BAL27862 we reduce microtubule occupancy and observe that spindle morphology is unaffected and bi-oriented kinetochores can still oscillate with normal intra-kinetochore distances. Inter-kinetochore stretching is, however, dramatically reduced. The reduction in microtubule occupancy and inter-kinetochore stretching does not delay satisfaction of the spindle assembly checkpoint or induce microtubule detachment via Aurora-B kinase, which was so far thought to release microtubules from kinetochores under low stretching. Rather, partial microtubule occupancy slows down anaphase A and increases incidences of lagging chromosomes due to merotelically attached kinetochores. Single microtubules (MTs) can move chromosomes, but it is unclear why kinetochores bind up to 20 MTs. Here, the authors decrease the number of kinetochore MTs with BAL27862 and see lagging chromosomes, suggesting that numerous kinetochore MTs provide force ensuring robust chromosomal segregation.
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Affiliation(s)
- Damian Dudka
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland
| | - Anna Noatynska
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland
| | - Chris A Smith
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, University of Warwick, CV4 7AL, Coventry, UK.,Metabolic Research Laboratories and MRC Metabolic Diseases Unit, Institute of Metabolic Science, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0QQ, UK
| | - Nicolas Liaudet
- Bioimaging Facility, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland
| | - Andrew D McAinsh
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, University of Warwick, CV4 7AL, Coventry, UK
| | - Patrick Meraldi
- Department of Cell Physiology and Metabolism, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland. .,Translational Research Centre in Onco-hematology, Faculty of Medicine, University of Geneva, 1211, Geneva 4, Switzerland.
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93
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The XMAP215 Ortholog Alp14 Promotes Microtubule Nucleation in Fission Yeast. Curr Biol 2018; 28:1681-1691.e4. [PMID: 29779879 DOI: 10.1016/j.cub.2018.04.008] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 01/19/2018] [Accepted: 04/03/2018] [Indexed: 12/18/2022]
Abstract
The organization and number of microtubules (MTs) in a cell depend on the proper regulation of MT nucleation. Currently, the mechanism of nucleation is the most poorly understood aspect of MT dynamics. XMAP215/chTOG/Alp14/Stu2 proteins are MT polymerases that stimulate MT polymerization at MT plus ends by binding and releasing tubulin dimers. Although these proteins also localize to MT organizing centers and have nucleating activity in vitro, it is not yet clear whether these proteins participate in MT nucleation in vivo. Here, we demonstrate that in the fission yeast Schizosaccharomyces pombe, the XMAP215 ortholog Alp14 is critical for efficient MT nucleation in vivo. In multiple assays, loss of Alp14 function led to reduced nucleation rate and numbers of interphase MT bundles. Conversely, activation of Alp14 led to increased nucleation frequency. Alp14 associated with Mto1 and γ-tubulin complex components, and artificially targeting Alp14 to the γ-tubulin ring complexes (γ-TuRCs) stimulated nucleation. In imaging individual nucleation events, we found that Alp14 transiently associated with a γ-tubulin particle shortly before the appearance of a new MT. The transforming acidic coiled-coil (TACC) ortholog Alp7 mediated the localization of Alp14 at nucleation sites but not plus ends, and was required for efficient nucleation but not for MT polymerization. Our findings provide the strongest evidence to date that Alp14 serves as a critical MT nucleation factor in vivo. We suggest a model in which Alp14 associates with the γ-tubulin complex in an Alp7-dependent manner to facilitate the assembly or stabilization of the nascent MT.
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94
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Abstract
Chromosome segregation relies on forces generated by spindle microtubules that are translated into chromosome movement through interactions with kinetochores, highly conserved macromolecular machines that assemble on a specialized centromeric chromatin structure. Kinetochores not only have to stably attach to growing and shrinking microtubules, but they also need to recruit spindle assembly checkpoint proteins to halt cell cycle progression when there are attachment defects. Even the simplest kinetochore in budding yeast contains more than 50 unique components that are present in multiple copies, totaling more than 250 proteins in a single kinetochore. The complex nature of kinetochores makes it challenging to elucidate the contributions of individual components to its various functions. In addition, it is difficult to manipulate forces in vivo to understand how they regulate kinetochore-microtubule attachments and the checkpoint. To address these issues, we developed a technique to purify kinetochores from budding yeast that can be used to analyze kinetochore functions and composition as well as to reconstitute kinetochore-microtubule attachments in vitro.
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95
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Volkov VA, Huis In 't Veld PJ, Dogterom M, Musacchio A. Multivalency of NDC80 in the outer kinetochore is essential to track shortening microtubules and generate forces. eLife 2018; 7:36764. [PMID: 29629870 PMCID: PMC5940359 DOI: 10.7554/elife.36764] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 03/31/2018] [Indexed: 12/31/2022] Open
Abstract
Presence of multiple copies of the microtubule-binding NDC80 complex is an evolutionary conserved feature of kinetochores, points of attachment of chromosomes to spindle microtubules. This may enable multivalent attachments to microtubules, with implications that remain unexplored. Using recombinant human kinetochore components, we show that while single NDC80 complexes do not track depolymerizing microtubules, reconstituted particles containing the NDC80 receptor CENP-T bound to three or more NDC80 complexes do so effectively, as expected for a kinetochore force coupler. To study multivalency systematically, we engineered modules allowing incremental addition of NDC80 complexes. The modules’ residence time on microtubules increased exponentially with the number of NDC80 complexes. Modules with two or more complexes tracked depolymerizing microtubules with increasing efficiencies, and stalled and rescued microtubule depolymerization in a force-dependent manner when conjugated to cargo. Our observations indicate that NDC80, rather than through biased diffusion, tracks depolymerizing microtubules by harnessing force generated during microtubule disassembly. Before a cell divides, its genome duplicates so that each copy can be given to the daughter cells. In a dividing cell, the chromosomes – the structures that store genetic information – look like an ‘X’. This is because each chromosome is formed of two identical, rod-like, ‘sister chromatids’ which are attached by their middle. Each daughter cell should inherit one of the chromatids. As division progresses, both sister chromatids in a pair fasten to ‘microtubules’, string-like structures made of a large number of identical proteins stacked together. These strings attach each chromatids to opposite sides of the cell. Then, the ends of the microtubules that bind to a chromatid start to peel off and disassemble. The microtubules get shorter and shorter, which creates a force that pulls the chromatids apart. Microtubules latch on a chromatid via a large structure known as the kinetochore, which has tether-like protein complexes called NDC80 at its surface. NDC80 links the kinetochore with the microtubules, yet little is known about this connection. In particular, it is unclear how this complex relays the forces from the shortening microtubules to the chromatids, and how many NDC80 complexes are required for this process. To study how these proteins interact without any molecular background ‘noise’ from the cell, Volkov, Huis in ‘t Veld et al. engineered simplified versions of the microtubule-kinetochore-NDC80 connection using components of human kinetochores. These versions, named ‘modules’, contained different numbers of NDC80 complexes, from one to four copies. Volkov, Huis in ‘t Veld et al. found that single NDC80 complexes did not follow the microtubules as they shortened, while the connections with two or more NDC80 complexes did. When a few modules, each with two or three NDC80s, were closeby, they also bound to the end of the same shortening microtubule, and captured more force as a team. NDC80 complexes therefore work together to connect to microtubule ends and harness their energy. The artificial kinetochore-microtubule-NDC80 connections developed by Volkov, Huis in ‘t Veld et al. provides a new method to study how cells divide, and it could reveal how other proteins and biological processes participate in this mechanism. It could also help understand how chromatids are kept from separating incorrectly during division, which is an error that could be fatal for the cell.
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Affiliation(s)
- Vladimir A Volkov
- Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
| | - Pim J Huis In 't Veld
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Marileen Dogterom
- Department of Bionanoscience, Faculty of Applied Sciences, Delft University of Technology, Delft, Netherlands
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
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96
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Majumdar S, Kim T, Chen Z, Munyoki S, Tso SC, Brautigam CA, Rice LM. An isolated CLASP TOG domain suppresses microtubule catastrophe and promotes rescue. Mol Biol Cell 2018; 29:1359-1375. [PMID: 29851564 PMCID: PMC5994897 DOI: 10.1091/mbc.e17-12-0748] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Microtubules are heavily regulated dynamic polymers of αβ-tubulin that are required for proper chromosome segregation and organization of the cytoplasm. Polymerases in the XMAP215 family use arrayed TOG domains to promote faster microtubule elongation. Regulatory factors in the cytoplasmic linker associated protein (CLASP) family that reduce catastrophe and/or increase rescue also contain arrayed TOGs, but how CLASP TOGs contribute to activity is poorly understood. Here, using Saccharomyces cerevisiae Stu1 as a model CLASP, we report structural, biochemical, and reconstitution studies that clarify functional properties of CLASP TOGs. The two TOGs in Stu1 have very different tubulin-binding properties: TOG2 binds to both unpolymerized and polymerized tubulin, and TOG1 binds very weakly to either. The structure of Stu1-TOG2 reveals a CLASP-specific residue that likely confers distinctive tubulin-binding properties. The isolated TOG2 domain strongly suppresses microtubule catastrophe and increases microtubule rescue in vitro, contradicting the expectation that regulatory activity requires an array of TOGs. Single point mutations on the tubulin-binding surface of TOG2 ablate its anti-catastrophe and rescue activity in vitro, and Stu1 function in cells. Revealing that an isolated CLASP TOG can regulate polymerization dynamics without being part of an array provides insight into the mechanism of CLASPs and diversifies the understanding of TOG function.
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Affiliation(s)
- Shreoshi Majumdar
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Tae Kim
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Zhe Chen
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390
| | - Sarah Munyoki
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Shih-Chia Tso
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390
| | - Chad A Brautigam
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Microbiology, UT Southwestern Medical Center, Dallas, TX 75390
| | - Luke M Rice
- Department of Biophysics, UT Southwestern Medical Center, Dallas, TX 75390.,Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
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97
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Samejima K, Booth DG, Ogawa H, Paulson JR, Xie L, Watson CA, Platani M, Kanemaki MT, Earnshaw WC. Functional analysis after rapid degradation of condensins and 3D-EM reveals chromatin volume is uncoupled from chromosome architecture in mitosis. J Cell Sci 2018; 131:jcs.210187. [PMID: 29361541 PMCID: PMC5868952 DOI: 10.1242/jcs.210187] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/15/2018] [Indexed: 01/01/2023] Open
Abstract
The requirement for condensin in chromosome formation in somatic cells remains unclear, as imperfectly condensed chromosomes do form in cells depleted of condensin by conventional methodologies. In order to dissect the roles of condensin at different stages of vertebrate mitosis, we have established a versatile cellular system that combines auxin-mediated rapid degradation with chemical genetics to obtain near-synchronous mitotic entry of chicken DT40 cells in the presence and absence of condensin. We analyzed the outcome by live- and fixed-cell microscopy methods, including serial block face scanning electron microscopy with digital reconstruction. Following rapid depletion of condensin, chromosomal defects were much more obvious than those seen after a slow depletion of condensin. The total mitotic chromatin volume was similar to that in control cells, but a single mass of mitotic chromosomes was clustered at one side of a bent mitotic spindle. Cultures arrest at prometaphase, eventually exiting mitosis without segregating chromosomes. Experiments where the auxin concentration was titrated showed that different condensin levels are required for anaphase chromosome segregation and formation of a normal chromosome architecture. This article has an associated First Person interview with the first author of the paper. Summary: Rapid condensin depletion reveals that different condensin levels are required for mitotic chromosome architecture and segregation. Condensin is not required for chromatin volume compaction during mitosis.
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Affiliation(s)
- Kumiko Samejima
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Daniel G Booth
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Hiromi Ogawa
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - James R Paulson
- Department of Chemistry, University of Wisconsin-Oshkosh, 800 Algoma Blvd, Oshkosh, WI 54901, USA
| | - Linfeng Xie
- Department of Chemistry, University of Wisconsin-Oshkosh, 800 Algoma Blvd, Oshkosh, WI 54901, USA
| | - Cara A Watson
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Melpomeni Platani
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
| | - Masato T Kanemaki
- Division of Molecular Cell Engineering, National Institute of Genetics, ROIS, and Department of Genetics, SOKENDAI, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - William C Earnshaw
- Wellcome Centre for Cell Biology, University of Edinburgh, King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, Scotland, UK
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98
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Haase KP, Fox JC, Byrnes AE, Adikes RC, Speed SK, Haase J, Friedman B, Cook DM, Bloom K, Rusan NM, Slep KC. Stu2 uses a 15-nm parallel coiled coil for kinetochore localization and concomitant regulation of the mitotic spindle. Mol Biol Cell 2018; 29:285-294. [PMID: 29187574 PMCID: PMC5996958 DOI: 10.1091/mbc.e17-01-0057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 10/10/2017] [Accepted: 11/22/2017] [Indexed: 11/23/2022] Open
Abstract
XMAP215/Dis1 family proteins are potent microtubule polymerases, critical for mitotic spindle structure and dynamics. While microtubule polymerase activity is driven by an N-terminal tumor overexpressed gene (TOG) domain array, proper cellular localization is a requisite for full activity and is mediated by a C-terminal domain. Structural insight into the C-terminal domain's architecture and localization mechanism remain outstanding. We present the crystal structure of the Saccharomyces cerevisiae Stu2 C-terminal domain, revealing a 15-nm parallel homodimeric coiled coil. The parallel architecture of the coiled coil has mechanistic implications for the arrangement of the homodimer's N-terminal TOG domains during microtubule polymerization. The coiled coil has two spatially distinct conserved regions: CRI and CRII. Mutations in CRI and CRII perturb the distribution and localization of Stu2 along the mitotic spindle and yield defects in spindle morphology including increased frequencies of mispositioned and fragmented spindles. Collectively, these data highlight roles for the Stu2 dimerization domain as a scaffold for factor binding that optimally positions Stu2 on the mitotic spindle to promote proper spindle structure and dynamics.
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Affiliation(s)
- Karen P Haase
- Molecular and Cellular Biophysics Program, University of North Carolina, Chapel Hill, NC 27599
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Jaime C Fox
- Molecular and Cellular Biophysics Program, University of North Carolina, Chapel Hill, NC 27599
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599
| | - Amy E Byrnes
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599
| | - Rebecca C Adikes
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Sarah K Speed
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Julian Haase
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Brandon Friedman
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Diana M Cook
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Kerry Bloom
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
| | - Nasser M Rusan
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Kevin C Slep
- Department of Biology, University of North Carolina, Chapel Hill, NC 27599
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99
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Kitajima TS. Mechanisms of kinetochore-microtubule attachment errors in mammalian oocytes. Dev Growth Differ 2018; 60:33-43. [PMID: 29318599 DOI: 10.1111/dgd.12410] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 10/03/2017] [Accepted: 10/04/2017] [Indexed: 12/21/2022]
Abstract
Proper kinetochore-microtubule attachment is essential for correct chromosome segregation. Therefore, cells normally possess multiple mechanisms for the prevention of errors in kinetochore-microtubule attachments and for selective stabilization of correct attachments. However, the oocyte, a cell that produces an egg through meiosis, exhibits a high frequency of errors in kinetochore-microtubule attachments. These attachment errors predispose oocytes to chromosome segregation errors, resulting in aneuploidy in eggs. This review aims to provide possible explanations for the error-prone nature of oocytes by examining key differences among other cell types in the mechanisms for the establishment of kinetochore-microtubule attachments.
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Affiliation(s)
- Tomoya S Kitajima
- Laboratory for Chromosome Segregation, RIKEN Center for Developmental Biology, Kobe, 650-0047, Japan
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100
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Lakshmi RB, Nair VM, Manna TK. Regulators of spindle microtubules and their mechanisms: Living together matters. IUBMB Life 2018; 70:101-111. [DOI: 10.1002/iub.1708] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 12/16/2017] [Indexed: 12/23/2022]
Affiliation(s)
- R. Bhagya Lakshmi
- School of Biology; Indian Institute of Science Education and Research, CET Campus; Thiruvananthapuram Kerala India
| | - Vishnu M. Nair
- School of Biology; Indian Institute of Science Education and Research, CET Campus; Thiruvananthapuram Kerala India
| | - Tapas K. Manna
- School of Biology; Indian Institute of Science Education and Research, CET Campus; Thiruvananthapuram Kerala India
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