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Brilot AF, Lyon AS, Zelter A, Viswanath S, Maxwell A, MacCoss MJ, Muller EG, Sali A, Davis TN, Agard DA. CM1-driven assembly and activation of yeast γ-tubulin small complex underlies microtubule nucleation. eLife 2021; 10:e65168. [PMID: 33949948 PMCID: PMC8099430 DOI: 10.7554/elife.65168] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 04/12/2021] [Indexed: 01/08/2023] Open
Abstract
Microtubule (MT) nucleation is regulated by the γ-tubulin ring complex (γTuRC), conserved from yeast to humans. In Saccharomyces cerevisiae, γTuRC is composed of seven identical γ-tubulin small complex (γTuSC) sub-assemblies, which associate helically to template MT growth. γTuRC assembly provides a key point of regulation for the MT cytoskeleton. Here, we combine crosslinking mass spectrometry, X-ray crystallography, and cryo-EM structures of both monomeric and dimeric γTuSCs, and open and closed helical γTuRC assemblies in complex with Spc110p to elucidate the mechanisms of γTuRC assembly. γTuRC assembly is substantially aided by the evolutionarily conserved CM1 motif in Spc110p spanning a pair of adjacent γTuSCs. By providing the highest resolution and most complete views of any γTuSC assembly, our structures allow phosphorylation sites to be mapped, surprisingly suggesting that they are mostly inhibitory. A comparison of our structures with the CM1 binding site in the human γTuRC structure at the interface between GCP2 and GCP6 allows for the interpretation of significant structural changes arising from CM1 helix binding to metazoan γTuRC.
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Affiliation(s)
- Axel F Brilot
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
| | - Andrew S Lyon
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
| | - Alex Zelter
- Department of Biochemistry, University of WashingtonSeattleUnited States
| | - Shruthi Viswanath
- Department of Bioengineering and Therapeutic Sciences, University of California at San FranciscoSan FranciscoUnited States
| | - Alison Maxwell
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
| | - Michael J MacCoss
- Department of Genome Sciences, University of WashingtonSeattleUnited States
| | - Eric G Muller
- Department of Biochemistry, University of WashingtonSeattleUnited States
| | - Andrej Sali
- Department of Bioengineering and Therapeutic Sciences, University of California at San FranciscoSan FranciscoUnited States
| | - Trisha N Davis
- Department of Biochemistry, University of WashingtonSeattleUnited States
| | - David A Agard
- Department of Biochemistry and Biophysics, University of California at San FranciscoSan FranciscoUnited States
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2
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Geymonat M, Peng Q, Guo Z, Yu Z, Unruh JR, Jaspersen SL, Segal M. Orderly assembly underpinning built-in asymmetry in the yeast centrosome duplication cycle requires cyclin-dependent kinase. eLife 2020; 9:59222. [PMID: 32851976 PMCID: PMC7470843 DOI: 10.7554/elife.59222] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/21/2020] [Indexed: 12/13/2022] Open
Abstract
Asymmetric astral microtubule organization drives the polarized orientation of the S. cerevisiae mitotic spindle and primes the invariant inheritance of the old spindle pole body (SPB, the yeast centrosome) by the bud. This model has anticipated analogous centrosome asymmetries featured in self-renewing stem cell divisions. We previously implicated Spc72, the cytoplasmic receptor for the gamma-tubulin nucleation complex, as the most upstream determinant linking SPB age, functional asymmetry and fate. Here we used structured illumination microscopy and biochemical analysis to explore the asymmetric landscape of nucleation sites inherently built into the spindle pathway and under the control of cyclin-dependent kinase (CDK). We show that CDK enforces Spc72 asymmetric docking by phosphorylating Nud1/centriolin. Furthermore, CDK-imposed order in the construction of the new SPB promotes the correct balance of nucleation sites between the nuclear and cytoplasmic faces of the SPB. Together these contributions by CDK inherently link correct SPB morphogenesis, age and fate.
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Affiliation(s)
- Marco Geymonat
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Qiuran Peng
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Zhiang Guo
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Zulin Yu
- Stowers Institute for Medical Research, Kansas City, United States
| | - Jay R Unruh
- Stowers Institute for Medical Research, Kansas City, United States
| | - Sue L Jaspersen
- Stowers Institute for Medical Research, Kansas City, United States.,Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, United States
| | - Marisa Segal
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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3
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Microtubule nucleation by γ-tubulin complexes and beyond. Essays Biochem 2018; 62:765-780. [PMID: 30315097 PMCID: PMC6281477 DOI: 10.1042/ebc20180028] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2018] [Revised: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 12/21/2022]
Abstract
In this short review, we give an overview of microtubule nucleation within cells. It is nearly 30 years since the discovery of γ-tubulin, a member of the tubulin superfamily essential for proper microtubule nucleation in all eukaryotes. γ-tubulin associates with other proteins to form multiprotein γ-tubulin ring complexes (γ-TuRCs) that template and catalyse the otherwise kinetically unfavourable assembly of microtubule filaments. These filaments can be dynamic or stable and they perform diverse functions, such as chromosome separation during mitosis and intracellular transport in neurons. The field has come a long way in understanding γ-TuRC biology but several important and unanswered questions remain, and we are still far from understanding the regulation of microtubule nucleation in a multicellular context. Here, we review the current literature on γ-TuRC assembly, recruitment, and activation and discuss the potential importance of γ-TuRC heterogeneity, the role of non-γ-TuRC proteins in microtubule nucleation, and whether γ-TuRCs could serve as good drug targets for cancer therapy.
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4
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Fong KK, Zelter A, Graczyk B, Hoyt JM, Riffle M, Johnson R, MacCoss MJ, Davis TN. Novel phosphorylation states of the yeast spindle pole body. Biol Open 2018; 7:bio.033647. [PMID: 29903865 PMCID: PMC6215409 DOI: 10.1242/bio.033647] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Phosphorylation regulates yeast spindle pole body (SPB) duplication and separation and likely regulates microtubule nucleation. We report a phosphoproteomic analysis using tandem mass spectrometry of enriched Saccharomyces cerevisiae SPBs for two cell cycle arrests, G1/S and the mitotic checkpoint, expanding on previously reported phosphoproteomic data sets. We present a novel phosphoproteomic state of SPBs arrested in G1/S by a cdc4-1 temperature-sensitive mutation, with particular focus on phosphorylation events on the γ-tubulin small complex (γ-TuSC). The cdc4-1 arrest is the earliest arrest at which microtubule nucleation has occurred at the newly duplicated SPB. Several novel phosphorylation sites were identified in G1/S and during mitosis on the microtubule nucleating γ-TuSC. These sites were analyzed in vivo by fluorescence microscopy and were shown to be required for proper regulation of spindle length. Additionally, in vivo analysis of two mitotic sites in Spc97 found that phosphorylation of at least one of these sites is required for progression through the cell cycle. This phosphoproteomic data set not only broadens the scope of the phosphoproteome of SPBs, it also identifies several γ-TuSC phosphorylation sites that influence microtubule formation. Summary: A phosphoproteome of yeast spindle pole bodies in G1/S or M phase identifies phosphorylation sites involved in spindle length control and provides direction for future phosphorylation analyses of spindle pole components.
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Affiliation(s)
- Kimberly K Fong
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Alex Zelter
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Beth Graczyk
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Jill M Hoyt
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Michael Riffle
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Richard Johnson
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Michael J MacCoss
- Department of Genome Sciences, University of Washington, Seattle, WA 98195, USA
| | - Trisha N Davis
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
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5
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Geymonat M, Segal M. Intrinsic and Extrinsic Determinants Linking Spindle Pole Fate, Spindle Polarity, and Asymmetric Cell Division in the Budding Yeast S. cerevisiae. Results Probl Cell Differ 2017; 61:49-82. [PMID: 28409300 DOI: 10.1007/978-3-319-53150-2_3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The budding yeast S. cerevisiae is a powerful model to understand the multiple layers of control driving an asymmetric cell division. In budding yeast, asymmetric targeting of the spindle poles to the mother and bud cell compartments respectively orients the mitotic spindle along the mother-bud axis. This program exploits an intrinsic functional asymmetry arising from the age distinction between the spindle poles-one inherited from the preceding division and the other newly assembled. Extrinsic mechanisms convert this age distinction into differential fate. Execution of this program couples spindle orientation with the segregation of the older spindle pole to the bud. Remarkably, similar stereotyped patterns of inheritance occur in self-renewing stem cell divisions underscoring the general importance of studying spindle polarity and differential fate in yeast. Here, we review the mechanisms accounting for this pivotal interplay between intrinsic and extrinsic asymmetries that translate spindle pole age into differential fate.
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Affiliation(s)
- Marco Geymonat
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Marisa Segal
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK.
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6
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Igamberdiev AU, Shklovskiy-Kordi NE. The quantum basis of spatiotemporality in perception and consciousness. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2017; 130:15-25. [PMID: 28232245 DOI: 10.1016/j.pbiomolbio.2017.02.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Accepted: 02/16/2017] [Indexed: 12/21/2022]
Abstract
Living systems inhabit the area of the world which is shaped by the predictable space-time of physical objects and forces that can be incorporated into their perception pattern. The process of selecting a "habitable" space-time is the internal quantum measurement in which living systems become embedded into the environment that supports their living state. This means that living organisms choose a coordinate system in which the influence of measurement is minimal. We discuss specific roles of biological macromolecules, in particular of the cytoskeleton, in shaping perception patterns formed in the internal measurement process. Operation of neuron is based on the transmission of signals via cytoskeleton where the digital output is generated that can be decoded through a reflective action of the perceiving agent. It is concluded that the principle of optimality in biology as formulated by Liberman et al. (BioSystems 22, 135-154, 1989) is related to the establishment of spatiotemporal patterns that are maximally predictable and can hold the living state for a prolonged time. This is achieved by the selection of a habitable space approximated to the conditions described by classical physics.
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Affiliation(s)
- Abir U Igamberdiev
- Department of Biology, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada.
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7
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Guo Z, Segal M. Analysis of the Localization of MEN Components by Live Cell Imaging Microscopy. Methods Mol Biol 2017; 1505:151-166. [PMID: 27826863 DOI: 10.1007/978-1-4939-6502-1_12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Mitotic exit is determined by multiple spatial and temporal cues from the spindle poles and the two compartments in a dividing yeast cell-the mother and the bud. These signals are ultimately integrated by the activation of the mitotic exit network (MEN) to promote persistent release of Cdc14 from the nucleolus. Live imaging analysis using fluorescent protein tags is invaluable to dissect this critical decision-making trigger. Here, we present protocols for routine yeast live cell microscopy applicable to this problem.
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Affiliation(s)
- Zhiang Guo
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Marisa Segal
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK.
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8
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Villoria MT, Ramos F, Dueñas E, Faull P, Cutillas PR, Clemente-Blanco A. Stabilization of the metaphase spindle by Cdc14 is required for recombinational DNA repair. EMBO J 2016; 36:79-101. [PMID: 27852625 PMCID: PMC5210157 DOI: 10.15252/embj.201593540] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 10/05/2016] [Accepted: 10/18/2016] [Indexed: 11/24/2022] Open
Abstract
Cells are constantly threatened by multiple sources of genotoxic stress that cause DNA damage. To maintain genome integrity, cells have developed a coordinated signalling network called DNA damage response (DDR). While multiple kinases have been thoroughly studied during DDR activation, the role of protein dephosphorylation in the damage response remains elusive. Here, we show that the phosphatase Cdc14 is essential to fulfil recombinational DNA repair in budding yeast. After DNA double‐strand break (DSB) generation, Cdc14 is transiently released from the nucleolus and activated. In this state, Cdc14 targets the spindle pole body (SPB) component Spc110 to counterbalance its phosphorylation by cyclin‐dependent kinase (Cdk). Alterations in the Cdk/Cdc14‐dependent phosphorylation status of Spc110, or its inactivation during the induction of a DNA lesion, generate abnormal oscillatory SPB movements that disrupt DSB‐SPB interactions. Remarkably, these defects impair DNA repair by homologous recombination indicating that SPB integrity is essential during the repair process. Together, these results show that Cdc14 promotes spindle stability and DSB‐SPB tethering during DNA repair, and imply that metaphase spindle maintenance is a critical feature of the repair process.
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Affiliation(s)
- María Teresa Villoria
- Cell Cycle and Genome Stability Group, Instituto de Biología Funcional y Genómica Consejo Superior de Investigaciones Científicas (CSIC) Universidad de Salamanca (USAL), Salamanca, Spain
| | - Facundo Ramos
- Cell Cycle and Genome Stability Group, Instituto de Biología Funcional y Genómica Consejo Superior de Investigaciones Científicas (CSIC) Universidad de Salamanca (USAL), Salamanca, Spain
| | - Encarnación Dueñas
- Cell Cycle and Genome Stability Group, Instituto de Biología Funcional y Genómica Consejo Superior de Investigaciones Científicas (CSIC) Universidad de Salamanca (USAL), Salamanca, Spain
| | - Peter Faull
- Biological Mass Spectrometry and Proteomics Laboratory, Medical Research Council Clinical Science Centre Imperial College, London, UK
| | - Pedro Rodríguez Cutillas
- Biological Mass Spectrometry and Proteomics Laboratory, Medical Research Council Clinical Science Centre Imperial College, London, UK
| | - Andrés Clemente-Blanco
- Cell Cycle and Genome Stability Group, Instituto de Biología Funcional y Genómica Consejo Superior de Investigaciones Científicas (CSIC) Universidad de Salamanca (USAL), Salamanca, Spain
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9
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Lyon AS, Morin G, Moritz M, Yabut KCB, Vojnar T, Zelter A, Muller E, Davis TN, Agard DA. Higher-order oligomerization of Spc110p drives γ-tubulin ring complex assembly. Mol Biol Cell 2016; 27:2245-58. [PMID: 27226487 PMCID: PMC4945142 DOI: 10.1091/mbc.e16-02-0072] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 05/19/2016] [Indexed: 02/01/2023] Open
Abstract
Assembly of the microtubule-nucleating γ-tubulin ring complex (γTuRC) requires higher-order oligomerization of Spc110p, which connects γTuRC to the yeast spindle pole body (SPB). Because Spc110p is highly concentrated at the SPB, spatial regulation of microtubule nucleation is thus achieved by exclusive assembly of γTuRCs proximal to the SPB. The microtubule (MT) cytoskeleton plays important roles in many cellular processes. In vivo, MT nucleation is controlled by the γ-tubulin ring complex (γTuRC), a 2.1-MDa complex composed of γ-tubulin small complex (γTuSC) subunits. The mechanisms underlying the assembly of γTuRC are largely unknown. In yeast, the conserved protein Spc110p both stimulates the assembly of the γTuRC and anchors the γTuRC to the spindle pole body. Using a quantitative in vitro FRET assay, we show that γTuRC assembly is critically dependent on the oligomerization state of Spc110p, with higher-order oligomers dramatically enhancing the stability of assembled γTuRCs. Our in vitro findings were confirmed with a novel in vivo γTuSC recruitment assay. We conclude that precise spatial control over MT nucleation is achieved by coupling localization and higher-order oligomerization of the receptor for γTuRC.
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Affiliation(s)
- Andrew S Lyon
- Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158
| | - Geneviève Morin
- Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Michelle Moritz
- Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158
| | | | - Tamira Vojnar
- Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Alex Zelter
- Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Eric Muller
- Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - Trisha N Davis
- Department of Biochemistry, University of Washington, Seattle, WA 98195
| | - David A Agard
- Department of Biochemistry and Biophysics and Howard Hughes Medical Institute, University of California, San Francisco, San Francisco, CA 94158
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10
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Diaz-Muñoz G, Harchar TA, Lai TP, Shen KF, Hopper AK. Requirement of the spindle pole body for targeting and/or tethering proteins to the inner nuclear membrane. Nucleus 2015; 5:352-66. [PMID: 25482124 PMCID: PMC4152349 DOI: 10.4161/nucl.29793] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Appropriate targeting of inner nuclear membrane (INM) proteins is important for nuclear function and architecture. To gain new insights into the mechanism(s) for targeting and/or tethering peripherally associated proteins to the INM, we screened a collection of temperature sensitive S. cerevisiae yeast mutants for defects in INM location of the peripheral protein, Trm1-II-GFP. We uncovered numerous genes encoding components of the Spindle Pole Body (SPB), the yeast centrosome. SPB alterations affect the localization of both an integral (Heh2) and a peripheral INM protein (Trm1-II-GFP), but not a nucleoplasmic protein (Pus1). In wild-type cells Trm1-II-GFP is evenly distributed around the INM, but in SPB mutants, Trm1-II-GFP mislocalizes as a spot(s) near ER-nucleus junctions, perhaps its initial contact site with the nuclear envelope. Employing live cell imaging over time in a microfluidic perfusion system to study protein dynamics, we show that both Trm1-II-GFP INM targeting and maintenance depend upon the SPB. We propose a novel targeting and/or tethering model for a peripherally associated INM protein that combines mechanisms of both integral and soluble nuclear proteins, and describe a role of the SPB in nuclear envelope dynamics that affects this process.
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Affiliation(s)
- Greetchen Diaz-Muñoz
- a Molecular, Cellular and Developmental Biology Interdisciplinary Program; The Ohio State University; Columbus, OH USA
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11
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Avena JS, Burns S, Yu Z, Ebmeier CC, Old WM, Jaspersen SL, Winey M. Licensing of yeast centrosome duplication requires phosphoregulation of sfi1. PLoS Genet 2014; 10:e1004666. [PMID: 25340401 PMCID: PMC4207612 DOI: 10.1371/journal.pgen.1004666] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 08/13/2014] [Indexed: 11/18/2022] Open
Abstract
Duplication of centrosomes once per cell cycle is essential for bipolar spindle formation and genome maintenance and is controlled in part by cyclin-dependent kinases (Cdks). Our study identifies Sfi1, a conserved component of centrosomes, as the first Cdk substrate required to restrict centrosome duplication to once per cell cycle. We found that reducing Cdk1 phosphorylation by changing Sfi1 phosphorylation sites to nonphosphorylatable residues leads to defects in separation of duplicated spindle pole bodies (SPBs, yeast centrosomes) and to inappropriate SPB reduplication during mitosis. These cells also display defects in bipolar spindle assembly, chromosome segregation, and growth. Our findings lead to a model whereby phosphoregulation of Sfi1 by Cdk1 has the dual function of promoting SPB separation for spindle formation and preventing premature SPB duplication. In addition, we provide evidence that the protein phosphatase Cdc14 has the converse role of activating licensing, likely via dephosphorylation of Sfi1.
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Affiliation(s)
- Jennifer S. Avena
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Shannon Burns
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Zulin Yu
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
| | - Christopher C. Ebmeier
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - William M. Old
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America
| | - Sue L. Jaspersen
- Stowers Institute for Medical Research, Kansas City, Missouri, United States of America
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, United States of America
| | - Mark Winey
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, United States of America
- * E-mail:
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12
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Lin TC, Neuner A, Schlosser YT, Scharf AND, Weber L, Schiebel E. Cell-cycle dependent phosphorylation of yeast pericentrin regulates γ-TuSC-mediated microtubule nucleation. eLife 2014; 3:e02208. [PMID: 24842996 PMCID: PMC4034690 DOI: 10.7554/elife.02208] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Budding yeast Spc110, a member of γ-tubulin complex receptor family (γ-TuCR), recruits γ-tubulin complexes to microtubule (MT) organizing centers (MTOCs). Biochemical studies suggest that Spc110 facilitates higher-order γ-tubulin complex assembly (Kollman et al., 2010). Nevertheless the molecular basis for this activity and the regulation are unclear. Here we show that Spc110 phosphorylated by Mps1 and Cdk1 activates γ-TuSC oligomerization and MT nucleation in a cell cycle dependent manner. Interaction between the N-terminus of the γ-TuSC subunit Spc98 and Spc110 is important for this activity. Besides the conserved CM1 motif in γ-TuCRs (Sawin et al., 2004), a second motif that we named Spc110/Pcp1 motif (SPM) is also important for MT nucleation. The activating Mps1 and Cdk1 sites lie between SPM and CM1 motifs. Most organisms have both SPM-CM1 (Spc110/Pcp1/PCNT) and CM1-only (Spc72/Mto1/Cnn/CDK5RAP2/myomegalin) types of γ-TuCRs. The two types of γ-TuCRs contain distinct but conserved C-terminal MTOC targeting domains. DOI:http://dx.doi.org/10.7554/eLife.02208.001 Microtubules are hollow structures made of proteins that have a central role in cell division and a variety of other important processes within cells. For a cell to divide successfully, the chromosomes containing the genetic information of the cell must be duplicated and then separated so that one copy of each chromosome ends up in each daughter cell. To separate the chromosomes, microtubules extend out from two structures called spindle pole bodies, which are found at either end of the cell, and pull one copy of each chromosome to opposite sides of the cell. Although the individual proteins that make up a microtubule can self-assemble into tubes, this occurs very slowly, so cells employ other molecules to speed up this process. In yeast cells, a protein called gamma-tubulin is recruited to the spindle pole body by the protein Spc110, where it combines with two other proteins to form a complex called the gamma-tubulin small complex. Several of these complexes then join together to form a ring, which probably acts as the platform that microtubules grow from. Recent observations suggested that Spc110 may help to construct this ring, but without revealing how. Now, Lin et al. reveal that Spc110 can regulate microtubule formation by controlling how several gamma-tubulin small complexes bind together, and have identified the exact section of Spc110 that interacts with the complexes. However, the Spc110 must become active before it can perform this role, and it is only activated during certain stages of cell division, through phosphorylation. The structures in Spc110 that bind to the gamma-tubulin small complex in yeast are also found in gamma-tubulin binding receptor proteins in human cells. The work of Lin et al. demonstrates that proteins that are assumed to have passive roles within cells, such as Spc110, often play more active roles instead. DOI:http://dx.doi.org/10.7554/eLife.02208.002
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Affiliation(s)
- Tien-Chen Lin
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany The Hartmut Hoffmann-Berling International Graduate School, University of Heidelberg, Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
| | - Yvonne T Schlosser
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
| | - Annette N D Scharf
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
| | - Lisa Weber
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
| | - Elmar Schiebel
- Zentrum für Molekulare Biologie (ZMBH), Universität Heidelberg, Heidelberg, Germany
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13
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Liang F, Richmond D, Wang Y. Coordination of chromatid separation and spindle elongation by antagonistic activities of mitotic and S-phase CDKs. PLoS Genet 2013; 9:e1003319. [PMID: 23468650 PMCID: PMC3584997 DOI: 10.1371/journal.pgen.1003319] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Accepted: 12/29/2012] [Indexed: 11/19/2022] Open
Abstract
Because cohesion prevents sister-chromatid separation and spindle elongation, cohesion dissolution may trigger these two events simultaneously. However, the relatively normal spindle elongation kinetics in yeast cohesin mutants indicates an additional mechanism for the temporal control of spindle elongation. Here we show evidence indicating that S-phase CDK (cyclin dependent kinase) negatively regulates spindle elongation. In contrast, mitotic CDK promotes spindle elongation by activating Cdc14 phosphatase, which reverses the protein phosphorylation imposed by S-phase CDK. Our data suggest that S-phase CDK negatively regulates spindle elongation partly through its phosphorylation of a spindle pole body (SPB) protein Spc110. We also show that hyperactive S-phase CDK compromises the microtubule localization of Stu2, a processive microtubule polymerase essential for spindle elongation. Strikingly, we found that hyperactive mitotic CDK induces uncoupled spindle elongation and sister-chromatid separation in securin mutants (pds1Δ), and we speculate that asynchronous chromosome segregation in pds1Δ cells contributes to this phenotype. Therefore, the tight temporal control of spindle elongation and cohesin cleavage assure orchestrated chromosome separation and spindle elongation.
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Affiliation(s)
- Fengshan Liang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, United States of America
| | - Daniel Richmond
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, United States of America
| | - Yanchang Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, United States of America
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Hotz M, Lengefeld J, Barral Y. The MEN mediates the effects of the spindle assembly checkpoint on Kar9-dependent spindle pole body inheritance in budding yeast. Cell Cycle 2012; 11:3109-16. [PMID: 22871738 DOI: 10.4161/cc.21504] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Many asymmetrically dividing cells segregate the poles of the mitotic spindle non-randomly between their two daughters. In budding yeast, the protein Kar9 localizes almost exclusively to the astral microtubules emanating from the old spindle pole body (SPB) and promotes its movement toward the bud. Thereby, Kar9 orients the spindle relative to the division axis. Here, we show that beyond perturbing Kar9 distribution, activation of the spindle assembly checkpoint (SAC) randomizes SPB inheritance. Inactivation of the B-type cyclin Clb5 led to a SAC-dependent defect in Kar9 orientation and SPB segregation. Furthermore, unlike the Clb4-dependent pathway, the Clb5- and SAC-dependent pathways functioned genetically upstream of the mitotic exit network (MEN) in SPB specification and Kar9-dependent SPB inheritance. Together, our study indicates that Clb5 functions in spindle assembly and that the SAC controls the specification and inheritance of yeast SPBs through inhibition of the MEN.
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Affiliation(s)
- Manuel Hotz
- Institute of Biochemistry, Biology Department, ETH Zurich, Zurich, Switzerland
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15
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Abstract
The Saccharomyces cerevisiae mitotic spindle in budding yeast is exemplified by its simplicity and elegance. Microtubules are nucleated from a crystalline array of proteins organized in the nuclear envelope, known as the spindle pole body in yeast (analogous to the centrosome in larger eukaryotes). The spindle has two classes of nuclear microtubules: kinetochore microtubules and interpolar microtubules. One kinetochore microtubule attaches to a single centromere on each chromosome, while approximately four interpolar microtubules emanate from each pole and interdigitate with interpolar microtubules from the opposite spindle to provide stability to the bipolar spindle. On the cytoplasmic face, two to three microtubules extend from the spindle pole toward the cell cortex. Processes requiring microtubule function are limited to spindles in mitosis and to spindle orientation and nuclear positioning in the cytoplasm. Microtubule function is regulated in large part via products of the 6 kinesin gene family and the 1 cytoplasmic dynein gene. A single bipolar kinesin (Cin8, class Kin-5), together with a depolymerase (Kip3, class Kin-8) or minus-end-directed kinesin (Kar3, class Kin-14), can support spindle function and cell viability. The remarkable feature of yeast cells is that they can survive with microtubules and genes for just two motor proteins, thus providing an unparalleled system to dissect microtubule and motor function within the spindle machine.
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16
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Ten Hoopen R, Cepeda-García C, Fernández-Arruti R, Juanes MA, Delgehyr N, Segal M. Mechanism for astral microtubule capture by cortical Bud6p priming spindle polarity in S. cerevisiae. Curr Biol 2012; 22:1075-83. [PMID: 22608510 DOI: 10.1016/j.cub.2012.04.059] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 03/29/2012] [Accepted: 04/17/2012] [Indexed: 12/16/2022]
Abstract
BACKGROUND Budding yeast is a unique model to dissect spindle orientation in a cell dividing asymmetrically. In yeast, this process begins with the capture of pole-derived astral microtubules (MTs) by the polarity determinant Bud6p at the cortex of the bud in G(1). Bud6p couples MT growth and shrinkage with spindle pole movement relative to the contact site. This activity resides in N-terminal sequences away from a domain linked to actin organization. Kip3p (kinesin-8), a MT depolymerase, may be implicated, but other molecular details are essentially unknown. RESULTS We show that Bud6p and Kip3p play antagonistic roles in controlling the length of MTs contacting the bud. The stabilizing role of Bud6p required the plus-end-tracking protein Bim1p (yeast EB1). Bim1p bound Bud6p N terminus, an interaction that proved essential for cortical capture of MTs in vivo. Moreover, Bud6p influenced Kip3p dynamic distribution through its effect on MT stability during cortical contacts via Bim1p. Coupling between Kip3p-driven depolymerization and shrinkage at the cell cortex required Bud6p, Bim1p, and dynein, a minus-end-directed motor helping tether the receding plus ends to the cell cortex. Validating these findings, live imaging of the interplay between dynein and Kip3p demonstrated that both motors decorated single astral MTs with dynein persisting at the plus end in association with the site of cortical contact during shrinkage at the cell cortex. CONCLUSIONS Astral MT shrinkage linked to Bud6p involves its direct interaction with Bim1p and the concerted action of two MT motors-Kip3p and dynein.
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Affiliation(s)
- Rogier Ten Hoopen
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
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17
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Lin TC, Gombos L, Neuner A, Sebastian D, Olsen JV, Hrle A, Benda C, Schiebel E. Phosphorylation of the yeast γ-tubulin Tub4 regulates microtubule function. PLoS One 2011; 6:e19700. [PMID: 21573187 PMCID: PMC3088709 DOI: 10.1371/journal.pone.0019700] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 04/11/2011] [Indexed: 01/10/2023] Open
Abstract
The yeast γ-tubulin Tub4 is assembled with Spc97 and Spc98 into the small Tub4 complex. The Tub4 complex binds via the receptor proteins Spc72 and Spc110 to the spindle pole body (SPB), the functional equivalent of the mammalian centrosome, where the Tub4 complex organizes cytoplasmic and nuclear microtubules. Little is known about the regulation of the Tub4 complex. Here, we isolated the Tub4 complex with the bound receptors from yeast cells. Analysis of the purified Tub4 complex by mass spectrometry identified more than 50 phosphorylation sites in Spc72, Spc97, Spc98, Spc110 and Tub4. To examine the functional relevance of the phosphorylation sites, phospho-mimicking and non-phosphorylatable mutations in Tub4, Spc97 and Spc98 were analyzed. Three phosphorylation sites in Tub4 were found to be critical for Tub4 stability and microtubule organization. One of the sites is highly conserved in γ-tubulins from yeast to human.
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Affiliation(s)
- Tien-chen Lin
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Linda Gombos
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Annett Neuner
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | - Dominik Sebastian
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
| | | | - Ajla Hrle
- MPI Biochemistry, Martinsried, Germany
| | | | - Elmar Schiebel
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Heidelberg, Germany
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18
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Esposito M, Piatti S, Hofmann L, Frontali L, Delahodde A, Rinaldi T. Analysis of the rpn11-m1 proteasomal mutant reveals connection between cell cycle and mitochondrial biogenesis. FEMS Yeast Res 2010; 11:60-71. [PMID: 21059189 DOI: 10.1111/j.1567-1364.2010.00690.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
The proteasomal lid subunit Rpn11 is essential for maintaining a correct cell cycle and mitochondrial morphology in Saccharomyces cerevisiae. In this paper, we show that the rpn11-m1 mutant has a peculiar cell cycle defect reminiscent of mutants defective in the FEAR pathway that delay the release of the Cdc14 protein phosphatase from the nucleolus. We analyzed the rpn11-m1 phenotypes and found that overexpression of Cdc14 suppresses all the rpn11-m1 defects, including the mitochondrial ones. Suppression by Cdc14 of the rpn11-m1 mitochondrial morphology defect reveals an uncharacterized connection between mitochondrial and cell cycle events. Interestingly, the overexpression of Cdc14 also partially restores the tubular network in an Δmmm2 strain, which lacks a mitochondrial protein belonging to the complex necessary to anchor the mitochondrion to the actin cytoskeleton. Altogether our findings indicate, for the first time, a cross-talk between the cell cycle and mitochondrial morphology.
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Affiliation(s)
- Michela Esposito
- Department of Cell and Developmental Biology, Pasteur Institute-Cenci Bolognetti Foundation, University of Rome, Rome, Italy
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19
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Cepeda-García C, Delgehyr N, Juanes Ortiz MA, ten Hoopen R, Zhiteneva A, Segal M. Actin-mediated delivery of astral microtubules instructs Kar9p asymmetric loading to the bud-ward spindle pole. Mol Biol Cell 2010; 21:2685-95. [PMID: 20534809 PMCID: PMC2912354 DOI: 10.1091/mbc.e10-03-0197] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
We show that Kar9p polarity is instructed by a feedback loop that requires astral microtubules, actin cables, and Myo2p-based transport to enforce Kar9p loading to the bud-ward pole. This novel mechanism also provides the basis for a model unifying Kar9p polarity and the stereotyped pattern of spindle pole inheritance known to occur in yeast. In Saccharomyces cerevisiae, Kar9p, one player in spindle alignment, guides the bud-ward spindle pole by linking astral microtubule plus ends to Myo2p-based transport along actin cables generated by the formins Bni1p and Bnr1p and the polarity determinant Bud6p. Initially, Kar9p labels both poles but progressively singles out the bud-ward pole. Here, we show that this polarization requires cell polarity determinants, actin cables, and microtubules. Indeed, in a bud6Δ bni1Δ mutant or upon direct depolymerization of actin cables Kar9p symmetry increased. Furthermore, symmetry was selectively induced by myo2 alleles, preventing Kar9p binding to the Myo2p cargo domain. Kar9p polarity was rebuilt after transient disruption of microtubules, dependent on cell polarity and actin cables. Symmetry breaking also occurred after transient depolymerization of actin cables, with Kar9p increasing at the spindle pole engaging in repeated cycles of Kar9p-mediated transport. Kar9p returning to the spindle pole on shrinking astral microtubules may contribute toward this bias. Thus, Myo2p transport along actin cables may support a feedback loop by which delivery of astral microtubule plus ends sustains Kar9p polarized recruitment to the bud-ward spindle pole. Our findings also explain the link between Kar9p polarity and the choice setting aside the old spindle pole for daughter-bound fate.
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20
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Holinger EP, Old WM, Giddings TH, Wong C, Yates JR, Winey M. Budding yeast centrosome duplication requires stabilization of Spc29 via Mps1-mediated phosphorylation. J Biol Chem 2009; 284:12949-55. [PMID: 19269975 DOI: 10.1074/jbc.m900088200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Protein phosphorylation plays an important role in the regulation of centrosome duplication. In budding yeast, numerous lines of evidence suggest a requirement for multiple phosphorylation events on individual components of the centrosome to ensure their proper assembly and function. Here, we report the first example of a single phosphorylation event on a component of the yeast centrosome, or spindle pole body (SPB), that is required for SPB duplication and cell viability. This phosphorylation event is on the essential SPB component Spc29 at a conserved Thr residue, Thr(240). Mutation of Thr(240) to Ala is lethal at normal gene dosage, but an increased copy number of this mutant allele results in a conditional phenotype. Phosphorylation of Thr(240) was found to promote the stability of the protein in vivo and is catalyzed in vitro by the Mps1 kinase. Furthermore, the stability of newly synthesized Spc29 is reduced in a mutant strain with reduced Mps1 kinase activity. These results demonstrate the first evidence for a single phosphorylation event on an SPB component that is absolutely required for SPB duplication and suggest that the Mps1 kinase is responsible for this protein-stabilizing phosphorylation.
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Affiliation(s)
- Eric P Holinger
- Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
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21
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Delgehyr N, Lopes CSJ, Moir CA, Huisman SM, Segal M. Dissecting the involvement of formins in Bud6p-mediated cortical capture of microtubules in S. cerevisiae. J Cell Sci 2008; 121:3803-14. [PMID: 18957510 DOI: 10.1242/jcs.036269] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In S. cerevisiae, spindle orientation is linked to the inheritance of the `old' spindle pole by the bud. A player in this asymmetric commitment, Bud6p, promotes cortical capture of astral microtubules. Additionally, Bud6p stimulates actin cable formation though the formin Bni1p. A relationship with the second formin, Bnr1p, is unclear. Another player is Kar9p, a protein that guides microtubules along actin cables organised by formins. Here, we ask whether formins mediate Bud6p-dependent microtubule capture beyond any links to Kar9p and actin. We found that both formins control Bud6p localisation. bni1 mutations advanced recruitment of Bud6p at the bud neck, ahead of spindle assembly, whereas bnr1Δ reduced Bud6p association with the bud neck. Accordingly, bni1 or bnr1 mutations redirected microtubule capture to or away from the bud neck, respectively. Furthermore, a Bni1p truncation that can form actin cables independently of Bud6p could not bypass a bud6Δ for microtubule capture. Conversely, Bud61-565p, a truncation insufficient for correct actin organisation via formins, supported microtubule capture. Finally, Bud6p or Bud61-565p associated with microtubules in vitro. Thus, surprisingly, Bud6p may promote microtubule capture independently of its links to actin organisation, whereas formins would contribute to the program of Bud6p-dependent microtubule-cortex interactions by controlling Bud6p localisation.
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Affiliation(s)
- Nathalie Delgehyr
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Cláudia S. J. Lopes
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Catherine A. Moir
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Stephen M. Huisman
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
| | - Marisa Segal
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK
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22
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Current awareness on yeast. Yeast 2007. [DOI: 10.1002/yea.1453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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