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Xin K, Zhang Y, Fan L, Qi Z, Feng C, Wang Q, Jiang C, Xu JR, Liu H. Experimental evidence for the functional importance and adaptive advantage of A-to-I RNA editing in fungi. Proc Natl Acad Sci U S A 2023; 120:e2219029120. [PMID: 36917661 PMCID: PMC10041177 DOI: 10.1073/pnas.2219029120] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 02/13/2023] [Indexed: 03/16/2023] Open
Abstract
Adenosine-to-inosine (A-to-I) editing is the most prevalent type of RNA editing in animals, and it occurs in fungi specifically during sexual reproduction. However, it is debatable whether A-to-I RNA editing is adaptive. Deciphering the functional importance of individual editing sites is essential for the mechanistic understanding of the adaptive advantages of RNA editing. Here, by performing gene deletion for 17 genes with conserved missense editing (CME) sites and engineering underedited (ue) and overedited (oe) mutants for 10 CME sites using site-specific mutagenesis at the native locus in Fusarium graminearum, we demonstrated that two CME sites in CME5 and CME11 genes are functionally important for sexual reproduction. Although the overedited mutant was normal in sexual reproduction, the underedited mutant of CME5 had severe defects in ascus and ascospore formation like the deletion mutant, suggesting that the CME site of CME5 is co-opted for sexual development. The preediting residue of Cme5 is evolutionarily conserved across diverse classes of Ascomycota, while the postediting one is rarely hardwired into the genome, implying that editing at this site leads to higher fitness than a genomic A-to-G mutation. More importantly, mutants expressing only the underedited or the overedited allele of CME11 are defective in ascosporogenesis, while those expressing both alleles displayed normal phenotypes, indicating that concurrently expressing edited and unedited versions of Cme11 is more advantageous than either. Our study provides convincing experimental evidence for the long-suspected adaptive advantages of RNA editing in fungi and likely in animals.
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Affiliation(s)
- Kaiyun Xin
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, Shaanxi712100, China
| | - Yang Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, Shaanxi712100, China
| | - Ligang Fan
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, Shaanxi712100, China
| | - Zhaomei Qi
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, Shaanxi712100, China
| | - Chanjing Feng
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, Shaanxi712100, China
| | - Qinhu Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, Shaanxi712100, China
| | - Cong Jiang
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, Shaanxi712100, China
| | - Jin-Rong Xu
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN47907
| | - Huiquan Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, College of Plant Protection, Northwest A&F University, Xianyang, Shaanxi712100, China
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2
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Zucca F, Visintin C, Li J, Gygi SP, Visintin R. APC/CCdc20-mediated degradation of Clb4 prompts astral microtubule stabilization at anaphase onset. J Cell Biol 2022; 222:213563. [PMID: 36269172 PMCID: PMC9595209 DOI: 10.1083/jcb.202203089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/12/2022] [Accepted: 10/05/2022] [Indexed: 11/22/2022] Open
Abstract
Key for accurate chromosome partitioning to the offspring is the ability of mitotic spindle microtubules to respond to different molecular signals and remodel their dynamics accordingly. Spindle microtubules are conventionally divided into three classes: kinetochore, interpolar, and astral microtubules (kMTs, iMTs, and aMTs, respectively). Among all, aMT regulation remains elusive. Here, we show that aMT dynamics are tightly regulated. aMTs remain unstable up to metaphase and are stabilized at anaphase onset. This switch in aMT dynamics, important for proper spindle orientation, specifically requires the degradation of the mitotic cyclin Clb4 by the Anaphase Promoting Complex bound to its activator subunit Cdc20 (APC/CCdc20). These data highlight a unique role for mitotic cyclin Clb4 in controlling aMT regulating factors, of which Kip2 is a prime candidate, provide a framework to understand aMT regulation in vertebrates, and uncover mechanistic principles of how the APC/CCdc20 choreographs the timing of late mitotic events by sequentially impacting on the three classes of spindle microtubules.
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Affiliation(s)
- Federico Zucca
- Department of Experimental Oncology, European Institute of Oncology IRCCS, Milan, Italy
| | - Clara Visintin
- Department of Experimental Oncology, European Institute of Oncology IRCCS, Milan, Italy
| | - Jiaming Li
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Steven P. Gygi
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | - Rosella Visintin
- Department of Experimental Oncology, European Institute of Oncology IRCCS, Milan, Italy,Correspondence to Rosella Visintin:
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3
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Bairwa NK, Shoket H, Pandita M, Sharma M. A Simple Assay for the Detection of Late-Stage Apoptosis Features in Saccharomyces cerevisiae. Curr Protoc 2022; 2:e525. [PMID: 36069669 DOI: 10.1002/cpz1.525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Unicellular eukaryotic organisms such as yeast and protozoa serve as useful models for studying the impact of chemicals on cell physiology, cellular growth, and genome duplication. The yeast Saccharomyces cerevisiae has been widely used to assess apoptosis induced by chemicals due to its genetic tractability, ease of evaluation, and readily available impact assessment tools. Apoptosis in S. cerevisiae is characterized by many features, including increased cell death, loss of membrane integrity, release of caspases, chromatin condensation, and nuclear fragmentation, which are similar to the ones observed in mammalian cells. Current methods of apoptosis assessment typically require specialized equipment and reagents, which limits wide adoption. Here, we describe a rapid, inexpensive, and easy-to-perform assay in yeast for the analysis of late-stage apoptotic features in cells treated with a chemical. We describe a protocol for assessing loss of cell survival and changes in the nucleus. We demonstrate the approach by using acetic acid and hydrogen peroxide as test chemicals. This assay for the study of late-stage apoptotic features in S. cerevisiae can be performed reliably and rapidly by any laboratory with basic equipment and may be extended for studying apoptosis in similar single-cell organisms after treatment with toxicological agents. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Culture of Saccharomyces cerevisiae, treatment with acetic acid or hydrogen peroxide, and semi-quantitative growth assay Basic Protocol 2: DAPI staining and fluorescence microscopy for the assessment of change in nucleus-to-cytoplasm ratio and nuclear integrity.
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Affiliation(s)
- Narendra K Bairwa
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu and Kashmir, India
| | - Heena Shoket
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu and Kashmir, India
| | - Monika Pandita
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu and Kashmir, India
| | - Meenu Sharma
- Genome Stability Regulation Lab, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, Jammu and Kashmir, India
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4
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Hunter B, Benoit MPMH, Asenjo AB, Doubleday C, Trofimova D, Frazer C, Shoukat I, Sosa H, Allingham JS. Kinesin-8-specific loop-2 controls the dual activities of the motor domain according to tubulin protofilament shape. Nat Commun 2022; 13:4198. [PMID: 35859148 PMCID: PMC9300613 DOI: 10.1038/s41467-022-31794-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Accepted: 07/04/2022] [Indexed: 12/29/2022] Open
Abstract
Kinesin-8s are dual-activity motor proteins that can move processively on microtubules and depolymerize microtubule plus-ends, but their mechanism of combining these distinct activities remains unclear. We addressed this by obtaining cryo-EM structures (2.6-3.9 Å) of Candida albicans Kip3 in different catalytic states on the microtubule lattice and on a curved microtubule end mimic. We also determined a crystal structure of microtubule-unbound CaKip3-ADP (2.0 Å) and analyzed the biochemical activity of CaKip3 and kinesin-1 mutants. These data reveal that the microtubule depolymerization activity of kinesin-8 originates from conformational changes of its motor core that are amplified by dynamic contacts between its extended loop-2 and tubulin. On curved microtubule ends, loop-1 inserts into preceding motor domains, forming head-to-tail arrays of kinesin-8s that complement loop-2 contacts with curved tubulin and assist depolymerization. On straight tubulin protofilaments in the microtubule lattice, loop-2-tubulin contacts inhibit conformational changes in the motor core, but in the ADP-Pi state these contacts are relaxed, allowing neck-linker docking for motility. We propose that these tubulin shape-induced alternations between pro-microtubule-depolymerization and pro-motility kinesin states, regulated by loop-2, are the key to the dual activity of kinesin-8 motors.
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Affiliation(s)
- Byron Hunter
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Matthieu P M H Benoit
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Ana B Asenjo
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Caitlin Doubleday
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Daria Trofimova
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Corey Frazer
- Department of Molecular Microbiology and Immunology, Brown University, Providence, RI, 02912, USA
| | - Irsa Shoukat
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada
| | - Hernando Sosa
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
| | - John S Allingham
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON, K7L 3N6, Canada.
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5
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Pavani M, Bonaiuti P, Chiroli E, Gross F, Natali F, Macaluso F, Póti Á, Pasqualato S, Farkas Z, Pompei S, Cosentino Lagomarsino M, Rancati G, Szüts D, Ciliberto A. Epistasis, aneuploidy, and functional mutations underlie evolution of resistance to induced microtubule depolymerization. EMBO J 2021; 40:e108225. [PMID: 34605051 DOI: 10.15252/embj.2021108225] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 09/09/2021] [Accepted: 09/14/2021] [Indexed: 11/09/2022] Open
Abstract
Cells with blocked microtubule polymerization are delayed in mitosis, but eventually manage to proliferate despite substantial chromosome missegregation. While several studies have analyzed the first cell division after microtubule depolymerization, we have asked how cells cope long-term with microtubule impairment. We allowed 24 clonal populations of yeast cells with beta-tubulin mutations preventing proper microtubule polymerization, to evolve for ˜150 generations. At the end of the laboratory evolution experiment, cells had regained the ability to form microtubules and were less sensitive to microtubule-depolymerizing drugs. Whole-genome sequencing identified recurrently mutated genes, in particular for tubulins and kinesins, as well as pervasive duplication of chromosome VIII. Recreating these mutations and chromosome VIII disomy prior to evolution confirmed that they allow cells to compensate for the original mutation in beta-tubulin. Most of the identified mutations did not abolish function, but rather restored microtubule functionality. Analysis of the temporal order of resistance development in independent populations repeatedly revealed the same series of events: disomy of chromosome VIII followed by a single additional adaptive mutation in either tubulins or kinesins. Since tubulins are highly conserved among eukaryotes, our results have implications for understanding resistance to microtubule-targeting drugs widely used in cancer therapy.
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Affiliation(s)
- Mattia Pavani
- IFOM, The Firc Institute of Molecular Oncology, Milano, Italy
| | - Paolo Bonaiuti
- IFOM, The Firc Institute of Molecular Oncology, Milano, Italy
| | - Elena Chiroli
- IFOM, The Firc Institute of Molecular Oncology, Milano, Italy
| | - Fridolin Gross
- IFOM, The Firc Institute of Molecular Oncology, Milano, Italy
| | - Federica Natali
- Institute of Medical Biology (IMB), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | | | - Ádám Póti
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Sebastiano Pasqualato
- IEO, European Institute of Oncology IRCCS, Milan, Italy.,Human Technopole, Milano, Italy
| | - Zoltán Farkas
- Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre, Szeged, Hungary
| | - Simone Pompei
- IFOM, The Firc Institute of Molecular Oncology, Milano, Italy
| | | | - Giulia Rancati
- Institute of Medical Biology (IMB), Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Dávid Szüts
- Institute of Enzymology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Andrea Ciliberto
- IFOM, The Firc Institute of Molecular Oncology, Milano, Italy.,Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia, Italy
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6
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Denarier E, Ecklund KH, Berthier G, Favier A, O'Toole ET, Gory-Fauré S, De Macedo L, Delphin C, Andrieux A, Markus SM, Boscheron C. Modeling a disease-correlated tubulin mutation in budding yeast reveals insight into MAP-mediated dynein function. Mol Biol Cell 2021; 32:ar10. [PMID: 34379441 PMCID: PMC8684761 DOI: 10.1091/mbc.e21-05-0237] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mutations in the genes that encode α- and β-tubulin underlie many neurological diseases, most notably malformations in cortical development. In addition to revealing the molecular basis for disease etiology, studying such mutations can provide insight into microtubule function and the role of the large family of microtubule effectors. In this study, we use budding yeast to model one such mutation—Gly436Arg in α-tubulin, which is causative of malformations in cortical development—in order to understand how it impacts microtubule function in a simple eukaryotic system. Using a combination of in vitro and in vivo methodologies, including live cell imaging and electron tomography, we find that the mutant tubulin is incorporated into microtubules, causes a shift in α-tubulin isotype usage, and dramatically enhances dynein activity, which leads to spindle-positioning defects. We find that the basis for the latter phenotype is an impaired interaction between She1—a dynein inhibitor—and the mutant microtubules. In addition to revealing the natural balance of α-tubulin isotype utilization in cells, our results provide evidence of an impaired interaction between microtubules and a dynein regulator as a consequence of a tubulin mutation and sheds light on a mechanism that may be causative of neurodevelopmental diseases.
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Affiliation(s)
- E Denarier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - K H Ecklund
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States
| | - G Berthier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - A Favier
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - E T O'Toole
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, Boulder, Colorado, United States
| | - S Gory-Fauré
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - L De Macedo
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - C Delphin
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - A Andrieux
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
| | - S M Markus
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado, United States
| | - C Boscheron
- Univ. Grenoble Alpes, CEA, CNRS, GIN, IBS, Inserm, IRIG, F-38000 Grenoble, France
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7
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King BR, Meehl JB, Vojnar T, Winey M, Muller EG, Davis TN. Microtubule-associated proteins and motors required for ectopic microtubule array formation in Saccharomyces cerevisiae. Genetics 2021; 218:6180076. [PMID: 33752231 DOI: 10.1093/genetics/iyab050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 03/04/2021] [Indexed: 12/17/2022] Open
Abstract
The mitotic spindle is resilient to perturbation due to the concerted, and sometimes redundant, action of motors and microtubule-associated proteins. Here, we utilize an inducible ectopic microtubule nucleation site in the nucleus of Saccharomyces cerevisiae to study three necessary steps in the formation of a bipolar array: the recruitment of the γ-tubulin complex, nucleation and elongation of microtubules (MTs), and the organization of MTs relative to each other. This novel tool, an Spc110 chimera, reveals previously unreported roles of the microtubule-associated proteins Stu2, Bim1, and Bik1, and the motors Vik1 and Kip3. We report that Stu2 and Bim1 are required for nucleation and that Bik1 and Kip3 promote nucleation at the ectopic site. Stu2, Bim1, and Kip3 join their homologs XMAP215, EB1 and kinesin-8 as promoters of microtubule nucleation, while Bik1 promotes MT nucleation indirectly via its role in SPB positioning. Furthermore, we find that the nucleation activity of Stu2 in vivo correlates with its polymerase activity in vitro. Finally, we provide the first evidence that Vik1, a subunit of Kar3/Vik1 kinesin-14, promotes microtubule minus end focusing at the ectopic site.
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Affiliation(s)
- Brianna R King
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Janet B Meehl
- Department of Molecular Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309, USA
| | - Tamira Vojnar
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Mark Winey
- Department of Molecular and Cellular Biology, University of California, Davis, CA 95616, USA
| | - Eric G Muller
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Trisha N Davis
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
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8
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Bioenergetics of the Dictyostelium Kinesin-8 Motor Isoform. Biomolecules 2020; 10:biom10040563. [PMID: 32272590 PMCID: PMC7226124 DOI: 10.3390/biom10040563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Revised: 03/27/2020] [Accepted: 04/02/2020] [Indexed: 12/29/2022] Open
Abstract
The functional organization of microtubules in eukaryotic cells requires a combination of their inherent dynamic properties, interactions with motor machineries, and interactions with accessory proteins to affect growth, shrinkage, stability, and architecture. In most organisms, the Kinesin-8 family of motors play an integral role in these organizations, well known for their mitotic activities in microtubule (MT) length control and kinetochore interactions. In Dictyostelium discoideum, the function of Kinesin-8 remains elusive. We present here some biochemical properties and localization data that indicate that this motor (DdKif10) shares some motility properties with other Kinesin-8s but also illustrates differences in microtubule localization and depolymerase action that highlight functional diversity.
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9
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Mittal P, Ghule K, Trakroo D, Prajapati HK, Ghosh SK. Meiosis-Specific Functions of Kinesin Motors in Cohesin Removal and Maintenance of Chromosome Integrity in Budding Yeast. Mol Cell Biol 2020; 40:e00386-19. [PMID: 31964755 PMCID: PMC7108822 DOI: 10.1128/mcb.00386-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2019] [Revised: 09/20/2019] [Accepted: 12/26/2019] [Indexed: 12/31/2022] Open
Abstract
Kinesin motors provide the molecular forces at the kinetochore-microtubule interface and along the spindle to control chromosome segregation. During meiosis with two rounds of microtubule assembly-disassembly, the roles of motor proteins remain unexplored. We observed that in contrast to mitosis, Cin8 and Kip3 together are indispensable for meiosis. While examining meiosis in cin8Δ kip3Δ cells, we detected chromosome breakage in the meiosis II cells. The double mutant exhibits a delay in cohesin removal during anaphase I. Consequently, some cells fail to undergo meiosis II and form dyads, while some, as they progress through meiosis II, cause a defect in chromosome integrity. We believe that in the latter cells, an imbalance of spindle-mediated force and the simultaneous persistence of cohesin on chromosomes cause their breakage. We provide evidence that tension generated by Cin8 and Kip3 through microtubule cross-linking is essential for signaling efficient cohesin removal and the maintenance of chromosome integrity during meiosis.
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Affiliation(s)
- Priyanka Mittal
- National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Komal Ghule
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, India
| | - Deepika Trakroo
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, India
| | - Hemant Kumar Prajapati
- National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Santanu K Ghosh
- Department of Biosciences and Bioengineering, Indian Institute of Technology, Bombay, Powai, Mumbai, India
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10
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Zeeshan M, Shilliday F, Liu T, Abel S, Mourier T, Ferguson DJP, Rea E, Stanway RR, Roques M, Williams D, Daniel E, Brady D, Roberts AJ, Holder AA, Pain A, Le Roch KG, Moores CA, Tewari R. Plasmodium kinesin-8X associates with mitotic spindles and is essential for oocyst development during parasite proliferation and transmission. PLoS Pathog 2019; 15:e1008048. [PMID: 31600347 PMCID: PMC6786531 DOI: 10.1371/journal.ppat.1008048] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Accepted: 08/26/2019] [Indexed: 12/17/2022] Open
Abstract
Kinesin-8 proteins are microtubule motors that are often involved in regulation of mitotic spindle length and chromosome alignment. They move towards the plus ends of spindle microtubules and regulate the dynamics of these ends due, at least in some species, to their microtubule depolymerization activity. Plasmodium spp. exhibit an atypical endomitotic cell division in which chromosome condensation and spindle dynamics in the different proliferative stages are not well understood. Genome-wide shared orthology analysis of Plasmodium spp. revealed the presence of two kinesin-8 motor proteins, kinesin-8X and kinesin-8B. Here we studied the biochemical properties of kinesin-8X and its role in parasite proliferation. In vitro, kinesin-8X has motility and depolymerization activities like other kinesin-8 motors. To understand the role of Plasmodium kinesin-8X in cell division, we used fluorescence-tagging and live cell imaging to define its location, and gene targeting to analyse its function, during all proliferative stages of the rodent malaria parasite P. berghei life cycle. The results revealed a spatio-temporal involvement of kinesin-8X in spindle dynamics and an association with both mitotic and meiotic spindles and the putative microtubule organising centre (MTOC). Deletion of the kinesin-8X gene revealed a defect in oocyst development, confirmed by ultrastructural studies, suggesting that this protein is required for oocyst development and sporogony. Transcriptome analysis of Δkinesin-8X gametocytes revealed modulated expression of genes involved mainly in microtubule-based processes, chromosome organisation and the regulation of gene expression, supporting a role for kinesin-8X in cell division. Kinesin-8X is thus required for parasite proliferation within the mosquito and for transmission to the vertebrate host.
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Affiliation(s)
- Mohammad Zeeshan
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Fiona Shilliday
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, United Kingdom
| | - Tianyang Liu
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, United Kingdom
| | - Steven Abel
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California, United States of America
| | - Tobias Mourier
- Biological Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Jeddah, Kingdom of Saudi Arabia
| | - David J. P. Ferguson
- Nuffield Department of Clinical Laboratory Sciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
- Department of Biological and Medical Sciences, Faculty of Health and Life Science, Oxford Brookes University, Gipsy Lane, Oxford, United Kingdom
| | - Edward Rea
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | | | - Magali Roques
- Institute of Cell Biology, University of Bern, Bern, Switzerland
| | - Desiree Williams
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California, United States of America
| | - Emilie Daniel
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Declan Brady
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, United Kingdom
| | - Anthony J. Roberts
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, United Kingdom
| | - Anthony A. Holder
- Malaria Parasitology Laboratory, The Francis Crick Institute, London, United Kingdom
| | - Arnab Pain
- Biological Environmental Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Jeddah, Kingdom of Saudi Arabia
- Research Center for Zoonosis Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Kita-ku, Sapporo, Japan
| | - Karine G. Le Roch
- Department of Molecular, Cell and Systems Biology, University of California Riverside, Riverside, California, United States of America
| | - Carolyn A. Moores
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London, United Kingdom
| | - Rita Tewari
- School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham, United Kingdom
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11
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Denarier E, Brousse C, Sissoko A, Andrieux A, Boscheron C. A neurodevelopmental TUBB2B β-tubulin mutation impairs Bim1 (yeast EB1)-dependent spindle positioning. Biol Open 2019; 8:bio.038620. [PMID: 30674462 PMCID: PMC6361202 DOI: 10.1242/bio.038620] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Malformations of the human cerebral cortex can be caused by mutations in tubulins that associate to compose microtubules. Cerebral cortical folding relies on neuronal migration and on progenitor proliferation partly dictated by microtubule-dependent mitotic spindle positioning. A single amino acid change, F265L, in the conserved TUBB2B β-tubulin gene has been identified in patients with abnormal cortex formation. A caveat for studying this mutation in mammalian cells is that nine genes encode β-tubulin in human. Here, we generate a yeast strain expressing F265L tubulin mutant as the sole source of β-tubulin. The F265L mutation does not preclude expression of a stable β-tubulin protein which is incorporated into microtubules. However, impaired cell growth was observed at high temperatures along with altered microtubule dynamics and stability. In addition, F265L mutation produces a highly specific mitotic spindle positioning defect related to Bim1 (yeast EB1) dysfunction. Indeed, F265L cells display an abnormal Bim1 recruitment profile at microtubule plus-ends. These results indicate that the F265L β-tubulin mutation affects microtubule plus-end complexes known to be important for microtubule dynamics and for microtubule function during mitotic spindle positioning.
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Affiliation(s)
- Eric Denarier
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000, Grenoble, France.,Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38000, Grenoble, France.,Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Biosciences and Biotechnology Institute of Grenoble, Grenoble, France
| | - Carine Brousse
- Institut National de la Transfusion Sanguine (INTS), F-75015 Paris, France
| | | | - Annie Andrieux
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000, Grenoble, France.,Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38000, Grenoble, France.,Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Biosciences and Biotechnology Institute of Grenoble, Grenoble, France
| | - Cécile Boscheron
- Univ. Grenoble Alpes, Grenoble Institut des Neurosciences, GIN, F-38000, Grenoble, France .,Institut National de la Santé et de la Recherche Médicale (INSERM), U1216, F-38000, Grenoble, France.,Institut de Biologie Structurale (IBS) , F-38000 Grenoble, France
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12
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Shrestha S, Hazelbaker M, Yount AL, Walczak CE. Emerging Insights into the Function of Kinesin-8 Proteins in Microtubule Length Regulation. Biomolecules 2018; 9:biom9010001. [PMID: 30577528 PMCID: PMC6359247 DOI: 10.3390/biom9010001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 12/15/2018] [Accepted: 12/17/2018] [Indexed: 12/14/2022] Open
Abstract
Proper regulation of microtubules (MTs) is critical for the execution of diverse cellular processes, including mitotic spindle assembly and chromosome segregation. There are a multitude of cellular factors that regulate the dynamicity of MTs and play critical roles in mitosis. Members of the Kinesin-8 family of motor proteins act as MT-destabilizing factors to control MT length in a spatially and temporally regulated manner. In this review, we focus on recent advances in our understanding of the structure and function of the Kinesin-8 motor domain, and the emerging contributions of the C-terminal tail of Kinesin-8 proteins to regulate motor activity and localization.
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Affiliation(s)
- Sanjay Shrestha
- Medical Sciences Program, Indiana University, Bloomington, IN 47405, USA.
| | - Mark Hazelbaker
- Medical Sciences Program, Indiana University, Bloomington, IN 47405, USA.
| | - Amber L Yount
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
| | - Claire E Walczak
- Medical Sciences Program, Indiana University, Bloomington, IN 47405, USA.
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13
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Bergman ZJ, Wong J, Drubin DG, Barnes G. Microtubule dynamics regulation reconstituted in budding yeast lysates. J Cell Sci 2018; 132:jcs.219386. [PMID: 30185524 DOI: 10.1242/jcs.219386] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 08/23/2018] [Indexed: 01/14/2023] Open
Abstract
Microtubules (MTs) are important for cellular structure, transport of cargoes and segregation of chromosomes and organelles during mitosis. The stochastic growth and shrinkage of MTs, known as dynamic instability, is necessary for these functions. Previous studies to determine how individual MT-associated proteins (MAPs) affect MT dynamics have been performed either through in vivo studies, which provide limited opportunity for observation of individual MTs or manipulation of conditions, or in vitro studies, which focus either on purified proteins, and therefore lack cellular complexity, or on cell extracts made from genetically intractable organisms. In order to investigate the ensemble activities of all MAPs on MT dynamics using lysates made from a genetically tractable organism, we developed a cell-free assay for budding yeast lysates using total internal reflection fluorescence (TIRF) microscopy. Lysates were prepared from yeast strains expressing GFP-tubulin. MT polymerization from pre-assembled MT seeds adhered to a coverslip was observed in real time. Through use of cell division cycle (cdc) and MT depolymerase mutants, we found that MT polymerization and dynamic instability are dependent on the cell cycle state and the activities of specific MAPs.
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Affiliation(s)
- Zane J Bergman
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Jonathan Wong
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - David G Drubin
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
| | - Georjana Barnes
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
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14
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Directionally biased sidestepping of Kip3/kinesin-8 is regulated by ATP waiting time and motor-microtubule interaction strength. Proc Natl Acad Sci U S A 2018; 115:E7950-E7959. [PMID: 30093386 DOI: 10.1073/pnas.1801820115] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Kinesin-8 motors, which move in a highly processive manner toward microtubule plus ends where they act as depolymerases, are essential regulators of microtubule dynamics in cells. To understand their navigation strategy on the microtubule lattice, we studied the 3D motion of single yeast kinesin-8 motors, Kip3, on freely suspended microtubules in vitro. We observed short-pitch, left-handed helical trajectories indicating that kinesin-8 motors frequently switch protofilaments in a directionally biased manner. Intriguingly, sidestepping was not directly coupled to forward stepping but rather depended on the average dwell time per forward step under limiting ATP concentrations. Based on our experimental findings and numerical simulations we propose that effective sidestepping toward the left is regulated by a bifurcation in the Kip3 step cycle, involving a transition from a two-head-bound to a one-head-bound conformation in the ATP-waiting state. Results from a kinesin-1 mutant with extended neck linker hint toward a generic sidestepping mechanism for processive kinesins, facilitating the circumvention of intracellular obstacles on the microtubule surface.
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15
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Dave S, Anderson SJ, Sinha Roy P, Nsamba ET, Bunning AR, Fukuda Y, Gupta ML. Discrete regions of the kinesin-8 Kip3 tail differentially mediate astral microtubule stability and spindle disassembly. Mol Biol Cell 2018; 29:1866-1877. [PMID: 29874146 PMCID: PMC6085823 DOI: 10.1091/mbc.e18-03-0199] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
To function in diverse cellular processes, the dynamic properties of microtubules must be tightly regulated. Cellular microtubules are influenced by a multitude of regulatory proteins, but how their activities are spatiotemporally coordinated within the cell, or on specific microtubules, remains mostly obscure. The conserved kinesin-8 motor proteins are important microtubule regulators, and family members from diverse species combine directed motility with the ability to modify microtubule dynamics. Yet how kinesin-8 activities are appropriately deployed in the cellular context is largely unknown. Here we reveal the importance of the nonmotor tail in differentially controlling the physiological functions of the budding yeast kinesin-8, Kip3. We demonstrate that the tailless Kip3 motor domain adequately governs microtubule dynamics at the bud tip to allow spindle positioning in early mitosis. Notably, discrete regions of the tail mediate specific functions of Kip3 on astral and spindle microtubules. The region proximal to the motor domain operates to spatially regulate astral microtubule stability, while the distal tail serves a previously unrecognized role to control the timing of mitotic spindle disassembly. These findings provide insights into how nonmotor tail domains differentially control kinesin functions in cells and the mechanisms that spatiotemporally control the stability of cellular microtubules.
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Affiliation(s)
- Sandeep Dave
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Samuel J Anderson
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Pallavi Sinha Roy
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Emmanuel T Nsamba
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Angela R Bunning
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
| | - Yusuke Fukuda
- Cell and Molecular Biology, The University of Chicago, Chicago, IL 60637
| | - Mohan L Gupta
- Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011
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16
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Xiang X. Nuclear movement in fungi. Semin Cell Dev Biol 2017; 82:3-16. [PMID: 29241689 DOI: 10.1016/j.semcdb.2017.10.024] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 10/17/2017] [Accepted: 10/23/2017] [Indexed: 12/22/2022]
Abstract
Nuclear movement within a cell occurs in a variety of eukaryotic organisms including yeasts and filamentous fungi. Fungal molecular genetic studies identified the minus-end-directed microtubule motor cytoplasmic dynein as a critical protein for nuclear movement or orientation of the mitotic spindle contained in the nucleus. Studies in the budding yeast first indicated that dynein anchored at the cortex via its anchoring protein Num1 exerts pulling force on an astral microtubule to orient the anaphase spindle across the mother-daughter axis before nuclear division. Prior to anaphase, myosin V interacts with the plus end of an astral microtubule via Kar9-Bim1/EB1 and pulls the plus end along the actin cables to move the nucleus/spindle close to the bud neck. In addition, pushing or pulling forces generated from cortex-linked polymerization or depolymerization of microtubules drive nuclear movements in yeasts and possibly also in filamentous fungi. In filamentous fungi, multiple nuclei within a hyphal segment undergo dynein-dependent back-and-forth movements and their positioning is also influenced by cytoplasmic streaming toward the hyphal tip. In addition, nuclear movement occurs at various stages of fungal development and fungal infection of plant tissues. This review discusses our current understanding on the mechanisms of nuclear movement in fungal organisms, the importance of nuclear positioning and the regulatory strategies that ensure the proper positioning of nucleus/spindle.
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Affiliation(s)
- Xin Xiang
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences - F. Edward Hébert School of Medicine, Bethesda, MD, USA.
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17
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Abstract
Kinesins are a superfamily of ATP-dependent motors important for many microtubule-based functions, including multiple roles in mitosis. Small-molecule inhibitors of mitotic kinesins disrupt cell division and are being developed as antimitotic therapies. We investigated the molecular mechanism of the multitasking human mitotic kinesin Kif18A and its inhibition by the small molecule BTB-1. We used cryo-electron microscopy to visualize nucleotide-dependent conformational changes in microtubule-bound Kif18A, and the conformation of microtubule-bound, BTB-1-bound Kif18A. We calculated a putative BTB-1–binding site and validated this site experimentally to reveal the BTB-1 inhibition mechanism. Our work points to a general mechanism of kinesin inhibition, with wide implications for a targeted blockade of these motors in both dividing and interphase cells. Kinesin motors play diverse roles in mitosis and are targets for antimitotic drugs. The clinical significance of these motors emphasizes the importance of understanding the molecular basis of their function. Equally important, investigations into the modes of inhibition of these motors provide crucial information about their molecular mechanisms. Kif18A regulates spindle microtubules through its dual functionality, with microtubule-based stepping and regulation of microtubule dynamics. We investigated the mechanism of Kif18A and its inhibition by the small molecule BTB-1. The Kif18A motor domain drives ATP-dependent plus-end microtubule gliding, and undergoes conformational changes consistent with canonical mechanisms of plus-end–directed motility. The Kif18A motor domain also depolymerizes microtubule plus and minus ends. BTB-1 inhibits both of these microtubule-based Kif18A activities. A reconstruction of BTB-1–bound, microtubule-bound Kif18A, in combination with computational modeling, identified an allosteric BTB-1–binding site near loop5, where it blocks the ATP-dependent conformational changes that we characterized. Strikingly, BTB-1 binding is close to that of well-characterized Kif11 inhibitors that block tight microtubule binding, whereas BTB-1 traps Kif18A on the microtubule. Our work highlights a general mechanism of kinesin inhibition in which small-molecule binding near loop5 prevents a range of conformational changes, blocking motor function.
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18
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Möckel MM, Heim A, Tischer T, Mayer TU. Xenopus laevis Kif18A is a highly processive kinesin required for meiotic spindle integrity. Biol Open 2017; 6:463-470. [PMID: 28228376 PMCID: PMC5399559 DOI: 10.1242/bio.023952] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The assembly and functionality of the mitotic spindle depends on the coordinated activities of microtubule-associated motor proteins of the dynein and kinesin superfamily. Our current understanding of the function of motor proteins is significantly shaped by studies using Xenopus laevis egg extract as its open structure allows complex experimental manipulations hardly feasible in other model systems. Yet, the Kinesin-8 orthologue of human Kif18A has not been described in Xenopus laevis so far. Here, we report the cloning and characterization of Xenopus laevis (Xl) Kif18A. Xenopus Kif18A is expressed during oocyte maturation and its depletion from meiotic egg extract results in severe spindle defects. These defects can be rescued by wild-type Kif18A, but not Kif18A lacking motor activity or the C-terminus. Single-molecule microscopy assays revealed that Xl_Kif18A possesses high processivity, which depends on an additional C-terminal microtubule-binding site. Human tissue culture cells depleted of endogenous Kif18A display mitotic defects, which can be rescued by wild-type, but not tail-less Xl_Kif18A. Thus, Xl_Kif18A is the functional orthologue of human Kif18A whose activity is essential for the correct function of meiotic spindles in Xenopus oocytes. Summary: The highly processive kinesin Kif18A, which is expressed during oocyte maturation in Xenopus laevis, is required for correct spindle formation in meiotic egg extracts and can functionally complement human Kif18A in tissue culture cells.
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Affiliation(s)
- Martin M Möckel
- Department of Molecular Genetics and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, Konstanz 78457, Germany
| | - Andreas Heim
- Department of Molecular Genetics and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, Konstanz 78457, Germany
| | - Thomas Tischer
- Department of Molecular Genetics and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, Konstanz 78457, Germany
| | - Thomas U Mayer
- Department of Molecular Genetics and Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, Konstanz 78457, Germany
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19
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Bowne-Anderson H, Hibbel A, Howard J. Regulation of Microtubule Growth and Catastrophe: Unifying Theory and Experiment. Trends Cell Biol 2016; 25:769-779. [PMID: 26616192 DOI: 10.1016/j.tcb.2015.08.009] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/27/2015] [Accepted: 08/27/2015] [Indexed: 10/22/2022]
Abstract
Recent studies have found that microtubule-associated proteins (MAPs) can regulate the dynamical properties of microtubules in unexpected ways. For most MAPs, there is an inverse relationship between their effects on the speed of growth and the frequency of catastrophe, the conversion of a growing microtubule to a shrinking one. Such a negative correlation is predicted by the standard GTP-cap model, which posits that catastrophe is due to loss of a stabilizing cap of GTP-tubulin at the end of a growing microtubule. However, many other MAPs, notably Kinesin-4 and combinations of EB1 with XMAP215, contradict this general rule. In this review, we show that a more nuanced, but still simple, GTP-cap model, can account for the diverse regulatory activities of MAPs.
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Affiliation(s)
| | - Anneke Hibbel
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden 01307, Germany; ETH Zurich, Institute for Biochemistry, HPM E8.1, Otto-Stern-Weg 3, 8093 Zurich, Switzerland
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20
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Walczak CE, Zong H, Jain S, Stout JR. Spatial regulation of astral microtubule dynamics by Kif18B in PtK cells. Mol Biol Cell 2016; 27:3021-3030. [PMID: 27559136 PMCID: PMC5063611 DOI: 10.1091/mbc.e16-04-0254] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 08/19/2016] [Indexed: 01/07/2023] Open
Abstract
The spatial and temporal control of microtubule dynamics is fundamentally important for proper spindle assembly and chromosome segregation. This is achieved, in part, by the multitude of proteins that bind to and regulate spindle microtubules, including kinesin superfamily members, which act as microtubule-destabilizing enzymes. These fall into two general classes: the kinesin-13 proteins, which directly depolymerize microtubules, and the kinesin-8 proteins, which are plus end-directed motors that either destabilize microtubules or cap the microtubule plus ends. Here we analyze the contribution of a PtK kinesin-8 protein, Kif18B, in the control of mitotic microtubule dynamics. Knockdown of Kif18B causes defects in spindle microtubule organization and a dramatic increase in astral microtubules. Kif18B-knockdown cells had defects in chromosome alignment, but there were no defects in chromosome segregation. The long astral microtubules that occur in the absence of Kif18B are limited in length by the cell cortex. Using EB1 tracking, we show that Kif18B activity is spatially controlled, as loss of Kif18B has the most dramatic effect on the lifetimes of astral microtubules that extend toward the cell cortex. Together our studies provide new insight into how diverse kinesins contribute to spatial microtubule organization in the spindle.
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Affiliation(s)
| | - Hailing Zong
- Department of Biology, Indiana University, Bloomington, IN 47405
| | - Sachin Jain
- Department of Biology, Indiana University, Bloomington, IN 47405
| | - Jane R Stout
- Medical Sciences, Indiana University, Bloomington, IN 47405
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21
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Gergely ZR, Crapo A, Hough LE, McIntosh JR, Betterton MD. Kinesin-8 effects on mitotic microtubule dynamics contribute to spindle function in fission yeast. Mol Biol Cell 2016; 27:3490-3514. [PMID: 27146110 PMCID: PMC5221583 DOI: 10.1091/mbc.e15-07-0505] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 04/26/2016] [Indexed: 11/17/2022] Open
Abstract
Kinesin-8 motor proteins destabilize microtubules and increase chromosome loss in mitosis. In fission yeast, aberrant microtubule-driven kinetochore pushing movements, tripolar mitotic spindles, and fluctuations in metaphase spindle length occurred in kinesin-8–deletion mutants. A mathematical model can explain these results. Kinesin-8 motor proteins destabilize microtubules. Their absence during cell division is associated with disorganized mitotic chromosome movements and chromosome loss. Despite recent work studying effects of kinesin-8s on microtubule dynamics, it remains unclear whether the kinesin-8 mitotic phenotypes are consequences of their effect on microtubule dynamics, their well-established motor activity, or additional, unknown functions. To better understand the role of kinesin-8 proteins in mitosis, we studied the effects of deletion of the fission yeast kinesin-8 proteins Klp5 and Klp6 on chromosome movements and spindle length dynamics. Aberrant microtubule-driven kinetochore pushing movements and tripolar mitotic spindles occurred in cells lacking Klp5 but not Klp6. Kinesin-8–deletion strains showed large fluctuations in metaphase spindle length, suggesting a disruption of spindle length stabilization. Comparison of our results from light microscopy with a mathematical model suggests that kinesin-8–induced effects on microtubule dynamics, kinetochore attachment stability, and sliding force in the spindle can explain the aberrant chromosome movements and spindle length fluctuations seen.
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Affiliation(s)
- Zachary R Gergely
- Department of Physics, University of Colorado at Boulder, Boulder, CO 80309.,Department of MCD Biology, University of Colorado at Boulder, Boulder, CO 80309
| | - Ammon Crapo
- Department of Physics, University of Colorado at Boulder, Boulder, CO 80309
| | - Loren E Hough
- Department of Physics, University of Colorado at Boulder, Boulder, CO 80309
| | - J Richard McIntosh
- Department of MCD Biology, University of Colorado at Boulder, Boulder, CO 80309
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22
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Biased Brownian motion as a mechanism to facilitate nanometer-scale exploration of the microtubule plus end by a kinesin-8. Proc Natl Acad Sci U S A 2015; 112:E3826-35. [PMID: 26150501 DOI: 10.1073/pnas.1500272112] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Kinesin-8s are plus-end-directed motors that negatively regulate microtubule (MT) length. Well-characterized members of this subfamily (Kip3, Kif18A) exhibit two important properties: (i) They are "ultraprocessive," a feature enabled by a second MT-binding site that tethers the motors to a MT track, and (ii) they dissociate infrequently from the plus end. Together, these characteristics combined with their plus-end motility cause Kip3 and Kif18A to enrich preferentially at the plus ends of long MTs, promoting MT catastrophes or pausing. Kif18B, an understudied human kinesin-8, also limits MT growth during mitosis. In contrast to Kif18A and Kip3, localization of Kif18B to plus ends relies on binding to the plus-end tracking protein EB1, making the relationship between its potential plus-end-directed motility and plus-end accumulation unclear. Using single-molecule assays, we show that Kif18B is only modestly processive and that the motor switches frequently between directed and diffusive modes of motility. Diffusion is promoted by the tail domain, which also contains a second MT-binding site that decreases the off rate of the motor from the MT lattice. In cells, Kif18B concentrates at the extreme tip of a subset of MTs, superseding EB1. Our data demonstrate that kinesin-8 motors use diverse design principles to target MT plus ends, which likely target them to the plus ends of distinct MT subpopulations in the mitotic spindle.
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23
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Abstract
Accurate segregation of genetic material into two daughter cells is essential for organism reproduction, development, and survival. The cell assembles a macromolecular structure called the mitotic spindle, which is composed of dynamic microtubules (MTs) and many associated proteins that assemble the spindle and drive the segregation of the chromosomes. Members of the kinesin superfamily of MT associated proteins use the energy of ATP hydrolysis to help organize the spindle, to transport cargo within the spindle, and to regulate spindle MT dynamics. The Kinesin-8 and Kinesin-13 families are involved in controlling mitotic spindle morphology, spindle positioning, and chromosome movement. While both kinesin families are MT destabilizing enzymes, it is unclear whether their mechanisms of MT destabilization are mechanistically similar or how they act to destabilize MTs. Recently, three groups identified an additional MT binding domain within the tail of Kinesin-8s that is essential for their roles in regulating MT dynamics and chromosome positioning.
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24
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Messin LJ, Millar JBA. Role and regulation of kinesin-8 motors through the cell cycle. SYSTEMS AND SYNTHETIC BIOLOGY 2014; 8:205-13. [PMID: 25136382 DOI: 10.1007/s11693-014-9140-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/11/2014] [Accepted: 03/15/2014] [Indexed: 10/25/2022]
Abstract
Members of the kinesin-8 motor family play a central role in controlling microtubule length throughout the eukaryotic cell cycle. Inactivation of kinesin-8 causes defects in cell polarity during interphase and astral and mitotic spindle length, metaphase chromosome alignment, timing of anaphase onset and accuracy of chromosome segregation. Although the biophysical mechanism by which kinesin-8 molecules influence microtubule dynamics has been studied extensively in a variety of species, a consensus view has yet to emerge. One reason for this might be that some members of the kinesin-8 family can associate to other microtubule-associated proteins, cell cycle regulatory proteins and other kinesin family members. In this review we consider how cell cycle specific modification and its association to other regulatory proteins may modulate the function of kinesin-8 to enable it to function as a master regulator of microtubule dynamics.
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Affiliation(s)
- Liam J Messin
- Mechanochemical Cell Biology Building, Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Gibbet Hill, Coventry, CV4 7AL UK
| | - Jonathan B A Millar
- Mechanochemical Cell Biology Building, Division of Biomedical Cell Biology, Warwick Medical School, University of Warwick, Gibbet Hill, Coventry, CV4 7AL UK
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25
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Abstract
The microtubule (MT) cytoskeleton supports a broad range of cellular functions, from providing tracks for intracellular transport, to supporting movement of cilia and flagella, to segregating chromosomes in mitosis. These functions are facilitated by the organizational and dynamic plasticity of MT networks. An important class of enzymes that alters MT dynamics is the depolymerizing kinesin-like proteins, which use their catalytic activities to regulate MT end dynamics. In this review, we discuss four topics surrounding these MT-depolymerizing kinesins. We provide a historical overview of studies focused on these motors and discuss their phylogeny. In the second half, we discuss their enzymology and biophysics and give an overview of their known cellular functions. This discussion highlights the fact that MT-depolymerizing kinesins exhibit a diverse range of design principles, which in turn increases their functional versatility in cells.
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Affiliation(s)
- Claire E Walczak
- Medical Sciences, Indiana University, Bloomington, Indiana 47405;
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26
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Move in for the kill: motile microtubule regulators. Trends Cell Biol 2012; 22:567-75. [PMID: 22959403 DOI: 10.1016/j.tcb.2012.08.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Revised: 08/01/2012] [Accepted: 08/09/2012] [Indexed: 12/18/2022]
Abstract
The stereotypical function of kinesin superfamily motors is to transport cargo along microtubules. However, some kinesins also shape the microtubule track by regulating microtubule assembly and disassembly. Recent work has shown that the kinesin-8 family of motors emerge as key regulators of cellular microtubule length. The studied kinesin-8s are highly processive motors that walk towards the microtubule plus-end. Once at plus-ends, they have complex effects on polymer dynamics; kinesin-8s either destabilize or stabilize microtubules, depending on the context. This review focuses on the mechanisms underlying kinesin-8-microtubule interactions and microtubule length control. We compare and contrast kinesin-8s with the other major microtubule-regulating kinesins (kinesin-4 and kinesin-13), to survey the current understanding of the diverse ways that kinesins control microtubule dynamics.
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27
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Merlini L, Piatti S. The mother-bud neck as a signaling platform for the coordination between spindle position and cytokinesis in budding yeast. Biol Chem 2012; 392:805-12. [PMID: 21824008 DOI: 10.1515/bc.2011.090] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
During asymmetric cell division, spindle positioning is critical for ensuring the unequal inheritance of polarity factors. In budding yeast, the mother-bud neck determines the cleavage plane and a correct nuclear division between mother and daughter cell requires orientation of the mitotic spindle along the mother-bud axis. A surveillance device called the spindle position/orientation checkpoint (SPOC) oversees this process and delays mitotic exit and cytokinesis until the spindle is properly oriented along the division axis, thus ensuring genome stability. Cytoskeletal proteins called septins form a ring at the bud neck that is essential for cytokinesis. Furthermore, septins and septin-associated proteins are implicated in spindle positioning and SPOC. In this review, we discuss the emerging connections between septins and the SPOC and the role of the mother-bud neck as a signaling platform to couple proper chromosome segregation to cytokinesis.
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Affiliation(s)
- Laura Merlini
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy
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Su X, Qiu W, Gupta ML, Pereira-Leal JB, Reck-Peterson SL, Pellman D. Mechanisms underlying the dual-mode regulation of microtubule dynamics by Kip3/kinesin-8. Mol Cell 2011; 43:751-63. [PMID: 21884976 DOI: 10.1016/j.molcel.2011.06.027] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 06/18/2011] [Accepted: 06/21/2011] [Indexed: 12/16/2022]
Abstract
The kinesin-8 family of microtubule motors plays a critical role in microtubule length control in cells. These motors have complex effects on microtubule dynamics: they destabilize growing microtubules yet stabilize shrinking microtubules. The budding yeast kinesin-8, Kip3, accumulates on plus ends of growing but not shrinking microtubules. Here we identify an essential role of the tail domain of Kip3 in mediating both its destabilizing and its stabilizing activities. The Kip3 tail promotes Kip3's accumulation at the plus ends and facilitates the destabilizing effect of Kip3. However, the Kip3 tail also inhibits microtubule shrinkage and is required for promoting microtubule rescue by Kip3. These effects of the tail domain are likely to be mediated by the tubulin- and microtubule-binding activities that we describe. We propose a concentration-dependent model for the coordination of the destabilizing and stabilizing activities of Kip3 and discuss its relevance to cellular microtubule organization.
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Affiliation(s)
- Xiaolei Su
- Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
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Stout JR, Yount AL, Powers JA, Leblanc C, Ems-McClung SC, Walczak CE. Kif18B interacts with EB1 and controls astral microtubule length during mitosis. Mol Biol Cell 2011; 22:3070-80. [PMID: 21737685 PMCID: PMC3164455 DOI: 10.1091/mbc.e11-04-0363] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Kif18B is a newly discovered plus-tip-tracking protein that is enriched on astral microtubule (MT) ends during early mitosis. Kif18B binds directly to EB1, and this interaction is required for proper localization of Kif18B and to control astral MT length. Regulation of microtubule (MT) dynamics is essential for proper spindle assembly and organization. Kinesin-8 family members are plus-end-directed motors that modulate plus-end MT dynamics by acting as MT depolymerases or as MT plus-end capping proteins. In this paper, we show that the human kinesin-8 Kif18B functions during mitosis to control astral MT organization. Kif18B is a MT plus-tip-tracking protein that localizes to the nucleus in interphase and is enriched at astral MT plus ends during early mitosis. Knockdown of Kif18B caused spindle defects, resulting in an increased number and length of MTs. A yeast two-hybrid screen identified an interaction of the C-terminal domain of Kif18B with the plus-end MT-binding protein EB1. EB1 knockdown disrupted Kif18B targeting to MT plus ends, indicating that EB1/Kif18B interaction is physiologically important. This interaction is direct, as the far C-terminal end of Kif18B is sufficient for binding to EB1 in vitro. Overexpression of this domain is sufficient for plus-end MT targeting in cells; however, targeting is enhanced by the motor domain, which cooperates with the tail to achieve proper Kif18B localization at MT plus ends. Our results suggest that Kif18B is a new MT dynamics regulatory protein that interacts with EB1 to control astral MT length.
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Affiliation(s)
- Jane R Stout
- Medical Sciences Program, Indiana University, Bloomington, IN 47405, USA
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Wargacki MM, Tay JC, Muller EG, Asbury CL, Davis TN. Kip3, the yeast kinesin-8, is required for clustering of kinetochores at metaphase. Cell Cycle 2011; 9:2581-8. [PMID: 20603597 DOI: 10.4161/cc.9.13.12076] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
In Saccharomyces cerevisiae, chromosome congression clusters kinetochores on either side of the spindle equator at metaphase. Many organisms require one or more kinesin-8 molecular motors to achieve chromosome alignment. The yeast kinesin-8, Kip3, has been well studied in vitro but a role in chromosome congression has not been reported. We investigated Kip3's role in this process using semi-automated, quantitative fluorescence microscopy and time-lapse imaging and found that Kip3 is required for congression. Deletion of KIP3 increases inter-kinetochore distances and increases the variability in the position of sister kinetochores along the spindle axis during metaphase. Kip3 does not regulate spindle length and is not required for kinetochore-microtubule attachment. Instead, Kip3 clusters kinetochores on the metaphase spindle by tightly regulating kinetochore microtubule lengths.
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Affiliation(s)
- Megan M Wargacki
- Department of Biochemistry, University of Washington, Seattle, WA, USA
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31
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Peters C, Brejc K, Belmont L, Bodey AJ, Lee Y, Yu M, Guo J, Sakowicz R, Hartman J, Moores CA. Insight into the molecular mechanism of the multitasking kinesin-8 motor. EMBO J 2010; 29:3437-47. [PMID: 20818331 PMCID: PMC2964168 DOI: 10.1038/emboj.2010.220] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2010] [Accepted: 08/17/2010] [Indexed: 11/08/2022] Open
Abstract
Members of the kinesin-8 motor class have the remarkable ability to both walk towards microtubule plus-ends and depolymerise these ends on arrival, thereby regulating microtubule length. To analyse how kinesin-8 multitasks, we studied the structure and function of the kinesin-8 motor domain. We determined the first crystal structure of a kinesin-8 and used cryo-electron microscopy to calculate the structure of the microtubule-bound motor. Microtubule-bound kinesin-8 reveals a new conformation compared with the crystal structure, including a bent conformation of the α4 relay helix and ordering of functionally important loops. The kinesin-8 motor domain does not depolymerise stabilised microtubules with ATP but does form tubulin rings in the presence of a non-hydrolysable ATP analogue. This shows that, by collaborating, kinesin-8 motor domain molecules can release tubulin from microtubules, and that they have a similar mechanical effect on microtubule ends as kinesin-13, which enables depolymerisation. Our data reveal aspects of the molecular mechanism of kinesin-8 motors that contribute to their unique dual motile and depolymerising functions, which are adapted to control microtubule length.
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Affiliation(s)
- Carsten Peters
- Institute of Structural and Molecular Biology, Birkbeck College, London, UK
| | | | | | - Andrew J Bodey
- Institute of Structural and Molecular Biology, Birkbeck College, London, UK
| | - Yan Lee
- Cytokinetics, San Francisco, CA, USA
| | - Ming Yu
- Cytokinetics, San Francisco, CA, USA
| | - Jun Guo
- Cytokinetics, San Francisco, CA, USA
| | | | | | - Carolyn A Moores
- Institute of Structural and Molecular Biology, Birkbeck College, London, UK
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Grava S, Philippsen P. Dynamics of multiple nuclei in Ashbya gossypii hyphae depend on the control of cytoplasmic microtubules length by Bik1, Kip2, Kip3, and not on a capture/shrinkage mechanism. Mol Biol Cell 2010; 21:3680-92. [PMID: 20844079 PMCID: PMC2965685 DOI: 10.1091/mbc.e10-06-0527] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Ashbya gossypii has a budding yeast-like genome but grows exclusively as multinucleated hyphae. In contrast to budding yeast where positioning of nuclei at the bud neck is a major function of cytoplasmic microtubules (cMTs), A. gossypii nuclei are constantly in motion and positioning is not an issue. To investigate the role of cMTs in nuclear oscillation and bypassing, we constructed mutants potentially affecting cMT lengths. Hyphae lacking the plus (+)end marker Bik1 or the kinesin Kip2 cannot polymerize long cMTs and lose wild-type nuclear movements. Interestingly, hyphae lacking the kinesin Kip3 display longer cMTs concomitant with increased nuclear oscillation and bypassing. Polymerization and depolymerization rates of cMTs are 3 times higher in A. gossypii than in budding yeast and cMT catastrophes are rare. Growing cMTs slide along the hyphal cortex and exert pulling forces on nuclei. Surprisingly, a capture/shrinkage mechanism seems to be absent in A. gossypii. cMTs reaching a hyphal tip do not shrink, and cMT +ends accumulate in hyphal tips. Thus, differences in cMT dynamics and length control between budding yeast and A. gossypii are key elements in the adaptation of the cMT cytoskeleton to much longer cells and much higher degrees of nuclear mobilities.
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Affiliation(s)
- Sandrine Grava
- Department of Molecular Microbiology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland
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Wickstead B, Gull K, Richards TA. Patterns of kinesin evolution reveal a complex ancestral eukaryote with a multifunctional cytoskeleton. BMC Evol Biol 2010; 10:110. [PMID: 20423470 PMCID: PMC2867816 DOI: 10.1186/1471-2148-10-110] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Accepted: 04/27/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The genesis of the eukaryotes was a pivotal event in evolution and was accompanied by the acquisition of numerous new cellular features including compartmentalization by cytoplasmic organelles, mitosis and meiosis, and ciliary motility. Essential for the development of these features was the tubulin cytoskeleton and associated motors. It is therefore possible to map ancient cell evolution by reconstructing the evolutionary history of motor proteins. Here, we have used the kinesin motor repertoire of 45 extant eukaryotes to infer the ancestral state of this superfamily in the last common eukaryotic ancestor (LCEA). RESULTS We bioinformatically identified 1624 putative kinesin proteins, determined their protein domain architectures and calculated a comprehensive Bayesian phylogeny for the kinesin superfamily with statistical support. These data enabled us to define 51 anciently-derived kinesin paralogs (including three new kinesin families) and 105 domain architectures. We then mapped these characters across eukaryotes, accounting for secondary loss within established eukaryotic groupings, and alternative tree topologies. CONCLUSIONS We show that a minimum of 11 kinesin families and 3 protein domain architectures were present in the LCEA. This demonstrates that the microtubule-based cytoskeleton of the LCEA was surprisingly highly developed in terms of kinesin motor types, but that domain architectures have been extensively modified during the diversification of the eukaryotes. Our analysis provides molecular evidence for the existence of several key cellular functions in the LCEA, and shows that a large proportion of motor family diversity and cellular complexity had already arisen in this ancient cell.
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Fujita I, Yamashita A, Yamamoto M. Contribution of dynein light intermediate and intermediate chains to subcellular localization of the dynein-dynactin motor complex in Schizosaccharomyces pombe. Genes Cells 2010; 15:359-72. [PMID: 20298435 DOI: 10.1111/j.1365-2443.2010.01386.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In fission yeast Schizosaccharomyces pombe, cytoplasmic dynein drives oscillatory nuclear movement during meiotic prophase, which may facilitate pairing of homologous chromosomes. Here, we report the identification of a dynein light intermediate chain (LIC) in fission yeast, termed Dli1p, and show that Dli1p and dynein intermediate chain (IC) Dic1p are essential for the appropriate subcellular localization and proper function of dynein during meiotic prophase. Expression of both the dli1 and dic1 genes was observed only in cells undergoing meiosis. Dli1p interacted and colocalized with dynein heavy chain Dhc1p. The subcellular localization of Dli1p was dependent on Dhc1p, and vice versa. The Dhc1p-Dli1p subcomplex could localize to the spindle pole body (SPB) with no aid of Dic1p and dynactin subunit Ssm4p, but its localization to microtubules was dependent on these two proteins. Dic1p localized to microtubules depending on Ssm4p, but not on Dhc1p and Dli1p. Its localization to the SPB, however, was dependent on Dhc1p and Dli1p. Localization of Ssm4p to the SPB was largely dependent on Dhc1p, Dli1p and Dic1p. Thus, Dli1p and Dic1p contribute differently in localizing the dynein-dynactin motor complex to organelles, providing novel insight into the in vivo function of dynein subunits in fission yeast.
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Affiliation(s)
- Ikumi Fujita
- Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan
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35
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Tischfield MA, Baris HN, Wu C, Rudolph G, Van Maldergem L, He W, Chan WM, Andrews C, Demer JL, Robertson RL, Mackey DA, Ruddle JB, Bird TD, Gottlob I, Pieh C, Traboulsi EI, Pomeroy SL, Hunter DG, Soul JS, Newlin A, Sabol LJ, Doherty EJ, de Uzcátegui CE, de Uzcátegui N, Collins MLZ, Sener EC, Wabbels B, Hellebrand H, Meitinger T, de Berardinis T, Magli A, Schiavi C, Pastore-Trossello M, Koc F, Wong AM, Levin AV, Geraghty MT, Descartes M, Flaherty M, Jamieson RV, Møller HU, Meuthen I, Callen DF, Kerwin J, Lindsay S, Meindl A, Gupta ML, Pellman D, Engle EC. Human TUBB3 mutations perturb microtubule dynamics, kinesin interactions, and axon guidance. Cell 2010; 140:74-87. [PMID: 20074521 PMCID: PMC3164117 DOI: 10.1016/j.cell.2009.12.011] [Citation(s) in RCA: 413] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2009] [Revised: 09/11/2009] [Accepted: 11/02/2009] [Indexed: 01/14/2023]
Abstract
We report that eight heterozygous missense mutations in TUBB3, encoding the neuron-specific beta-tubulin isotype III, result in a spectrum of human nervous system disorders that we now call the TUBB3 syndromes. Each mutation causes the ocular motility disorder CFEOM3, whereas some also result in intellectual and behavioral impairments, facial paralysis, and/or later-onset axonal sensorimotor polyneuropathy. Neuroimaging reveals a spectrum of abnormalities including hypoplasia of oculomotor nerves and dysgenesis of the corpus callosum, anterior commissure, and corticospinal tracts. A knock-in disease mouse model reveals axon guidance defects without evidence of cortical cell migration abnormalities. We show that the disease-associated mutations can impair tubulin heterodimer formation in vitro, although folded mutant heterodimers can still polymerize into microtubules. Modeling each mutation in yeast tubulin demonstrates that all alter dynamic instability whereas a subset disrupts the interaction of microtubules with kinesin motors. These findings demonstrate that normal TUBB3 is required for axon guidance and maintenance in mammals.
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Affiliation(s)
- Max A. Tischfield
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- The Manton Center for Orphan Disease Research, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Hagit N. Baris
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115 USA
| | - Chen Wu
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
| | - Guenther Rudolph
- University Eye Hospital, Ludwig-Maximilians-University, Munich, Germany
| | - Lionel Van Maldergem
- Centre de génétique humaine Université de Liège, Domaine universitaire du Sart-Tilman, B-4000 Liège, Belgium
| | - Wei He
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
| | - Wai-Man Chan
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Caroline Andrews
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
| | - Joseph L. Demer
- Department of Ophthalmology and Jules Stein Eye Institute, David Geffen Medical School at University of California Los Angeles
- Department of Neurology, David Geffen Medical School at University of California Los Angeles
- Neuroscience Interdepartmental Program, David Geffen Medical School at University of California Los Angeles
- Bioengineering Interdepartmental Program, David Geffen Medical School at University of California Los Angeles
| | | | - David A. Mackey
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, 3002, Australia
- Department of Ophthalmology, Royal Hobart Hospital, University of Tasmania, Hobart Tasmania, 7000, Australia
| | - Jonathan B. Ruddle
- Centre for Eye Research Australia, Department of Ophthalmology, University of Melbourne, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, 3002, Australia
| | - Thomas D. Bird
- Department of Neurology and the Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195, USA
- GRECC, VA Puget Sound Health Care System, Seattle, WA
| | - Irene Gottlob
- Ophthalmology Group, University of Leicester, Leicester, LE2 7LX, UK
| | - Christina Pieh
- University Eye Hospital, University of Freiburg, Killianstr. 6, 79106 Freiburg, Germany
| | - Elias I. Traboulsi
- Cole Eye Institute, Cleveland Clinic i32, 9500 Euclid Avenue Cleveland, OH 44195
| | - Scott L. Pomeroy
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - David G. Hunter
- Department of Ophthalmology, Children’s Hospital Boston, Boston, MA 02115 USA
| | - Janet S. Soul
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
| | - Anna Newlin
- Center for Medical Genetics, NorthShore University HealthSystem, Evanston, IL 60201
| | - Louise J. Sabol
- Department of Ophthalmology, Geisinger Medical Institute, Danville, Pennsylvania
| | - Edward J. Doherty
- Atlantic Health Science Centre, Saint John Regional Hospital, Saint John New Brunswick, Canada
| | - Clara E. de Uzcátegui
- Instituto de Oftalmologia, Av. Cajigal 48. Piso 3 Consultorio 8. San Bernardino, Caracas 1010 Venezuela
| | - Nicolas de Uzcátegui
- Department of Ophthalmology, Upstate Medical University SUNY. Eye Consultants Of Syracuse, 1101 Erie Blvd. East Ste 100. Syracuse NY 13210
| | | | - Emin C. Sener
- Department of Ophthalmology, Hacettepe University Hospitals, Ankara 06100, Turkey
| | - Bettina Wabbels
- Department of Ophthalmology, University of Bonn, Abbestr. 2, D-53127, Bonn, Germany
| | - Heide Hellebrand
- Department of Obstetrics and Gynaecology, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr 22, 81675 Munich, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr 22, 81675 Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, Ingolstädter Landstr. 1, 85764 Neuherberg, Germany
| | - Teresa de Berardinis
- Department of Ophthalmologic Sciences, Faculty of Medicine and Surgery, University “Federico II”, Naples, Italy
| | - Adriano Magli
- Department of Ophthalmologic Sciences, Faculty of Medicine and Surgery, University “Federico II”, Naples, Italy
| | | | - Marco Pastore-Trossello
- Department of Neuro-Radiology, S.Orsola-Malpighi Hospital via Albertoni, 15, 40138, Bologna, Italy
| | - Feray Koc
- Department of Ophthalmology and Strabismus, and Neuroophthalmology, Acıbadem University Kocaeli Hospital, Kocaeli 41100 Turkey
| | - Agnes M. Wong
- Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, Toronto, Ontario Canada
| | - Alex V. Levin
- Pediatric Ophthalmology and Ocular Genetics, Wills Eye Institute, Philadelphia, PA
| | | | - Maria Descartes
- Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama
| | - Maree Flaherty
- Department of Ophthalmology, The Children’s Hospital at Westmead, Sydney, Australia
| | - Robyn V. Jamieson
- Department of Clinical Genetics, The Children’s Hospital at Westmead, Sydney, Australia
- The University of Sydney, Sydney, Australia
| | - H. U. Møller
- Department of Ophthalmology, Viborg Hospital, DK 8000 Viborg Denmark
| | - Ingo Meuthen
- Department of Hematology-Oncology, Kliniken der Stadt Köln, Neufelderstr. 32, 51067 Köln, Germany
| | - David F. Callen
- Breast Cancer Genetics Group, School of Medicine, University of Adelaide, Australia
| | - Janet Kerwin
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Susan Lindsay
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
- MRC-Wellcome Trust Human Developmental Biology Resource (Newcastle), Newcastle University, Newcastle upon Tyne NE1 3BZ, UK
| | - Alfons Meindl
- Department of Obstetrics and Gynaecology, Klinikum rechts der Isar, Technische Universität München, Ismaningerstr 22, 81675 Munich, Germany
| | - Mohan L. Gupta
- Division of Hematology/Oncology, Harvard Medical School, Boston, MA 02115, USA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - David Pellman
- Division of Hematology/Oncology, Children’s Hospital Boston, Boston, MA 02115 USA
- Division of Hematology/Oncology, Harvard Medical School, Boston, MA 02115, USA
- Department of Pediatric Oncology, Dana-Farber Cancer Institute, Boston, MA 02115, USA
| | - Elizabeth C. Engle
- Department of Neurology, Children’s Hospital Boston, Boston, MA 02115 USA
- FM Kirby Neurobiology Center, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Genomics, Children’s Hospital Boston, Boston, MA 02115 USA
- The Manton Center for Orphan Disease Research, Children’s Hospital Boston, Boston, MA 02115 USA
- Department of Medicine (Genetics), Children’s Hospital Boston, Boston, MA 02115 USA
- Department of Ophthalmology, Children’s Hospital Boston, Boston, MA 02115 USA
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA
- Department of Neurology, Harvard Medical School, Boston, MA 02115, USA
- Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA
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Abstract
Kinesin-8 family members function in microtubule length control and exhibit highly processive plus-end directed motility in conjunction with microtubule dissassembly activity. In a recent issue of Cell, Varga and colleagues describe how these two activities may be used to simultaneously measure and adjust the length of cellular microtubules.
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Affiliation(s)
- Linda Wordeman
- Department of Physiology and Biophysics. University of Washington School of Medicine. Seattle, WA 98195, USA.
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Ptak C, Anderson AM, Scott RJ, Van de Vosse D, Rogers RS, Sydorskyy Y, Aitchison JD, Wozniak RW. A role for the karyopherin Kap123p in microtubule stability. Traffic 2009; 10:1619-34. [PMID: 19761543 DOI: 10.1111/j.1600-0854.2009.00978.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Several components of the nuclear transport machinery play a role in mitotic spindle assembly in higher eukaryotes. To further investigate the role of this family of proteins in microtubule function, we screened for mutations in Saccharomyces cerevisiae that confer sensitivity to microtubule-destabilizing drugs. One mutant exhibiting this phenotype lacked the gene encoding the karyopherin Kap123p. Analysis of kap123Delta cells revealed that the drug sensitivity was caused by a defect in microtubule stability and/or assembly. In support of this idea, we demonstrated genetic interactions between the kap123Delta mutation and mutated alleles of genes encoding alpha-tubulins and factors controlling microtubule dynamics. Moreover, kap123Delta cells exhibit defects in spindle structure and dynamics as well as nuclear positioning defects during mitosis. Cultures of kap123Delta strains are enriched for mononucleated large-budded cells often containing short spindles and nuclei positioned away from the budneck, phenotypes indicative of defects in both cytoplasmic and nuclear microtubules. Finally, we identified a gene, CAJ1, which when deleted in combination with KAP123 exacerbated the microtubule-related defects of the kap123Delta mutants. We propose that Kap123p and Caj1p, a member of the Hsp40 family of proteins, together play an essential role in normal microtubule function.
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Affiliation(s)
- Christopher Ptak
- Department of Cell Biology, University of Alberta, Edmonton, AB T6G 2H7 Canada
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Bartolini F, Gundersen GG. Formins and microtubules. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2009; 1803:164-73. [PMID: 19631698 DOI: 10.1016/j.bbamcr.2009.07.006] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 05/29/2009] [Accepted: 07/04/2009] [Indexed: 02/06/2023]
Abstract
Formins have recently been recognized as prominent regulators of the microtubule (MT) cytoskeleton where they modulate the dynamics of selected MTs in interphase and mitosis. The association of formins with the MT cytoskeleton and their action on MT dynamics are relatively unexplored areas, yet growing evidence supports a direct role in their regulation of MT stability independent of their activity on actin. Formins regulate MT stability alone or in combination with accessory MT binding proteins that have previously been implicated in the stabilization of MTs downstream of polarity cues. As actin and MT arrays are typically remodeled downstream of signaling pathways that orchestrate cell shape and division, formins are emerging as excellent candidates for coordinating the responses of the cytoskeletal in diverse regulated and homeostatic processes.
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Affiliation(s)
- F Bartolini
- Department of Pathology and Cell Biology, Columbia University, New York, NY, USA
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Xing L, Li J, Xu Y, Xu Z, Chong K. Phosphorylation modification of wheat lectin VER2 is associated with vernalization-induced O-GlcNAc signaling and intracellular motility. PLoS One 2009; 4:e4854. [PMID: 19287503 PMCID: PMC2654674 DOI: 10.1371/journal.pone.0004854] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2008] [Accepted: 02/09/2009] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND O-linked beta-N-acetylglucosamine (O-GlcNAc) modification of proteins mediates stress response and cellular motility in animal cells. The plant lectin concanavalin A can increase nuclear O-GlcNAc levels and decrease cytoplasmic O-GlcNAc levels in T lymphocytes. However, the functions of O-GlcNAc signaling in plants, as well as the relation between plant lectins and O-GlcNAc in response to environmental stimuli are largely undefined. METHODOLOGY/PRINCIPAL FINDINGS We describe a jacalin-like lectin VER2 in wheat that shows N-acetylglucosamine and galactose specificity. Immunocytochemical localization showed VER2 expression induced predominantly at potential nuclear structures in shoot tips and young leaves and weakly in cytoplasm in response to vernalization. In contrast, under devernalization (continuous stimulation with a higher temperature after vernalization), VER2 signals appeared predominantly in cytoplasm. 2-D electrophoresis, together with western blot analysis, showed phosphorylation modification of VER2 under vernalization. Immunoblot assay with O-GlcNAc-specific antibody revealed that vernalization increased O-GlcNAc modification of proteins at the global level. An O-GlcNAc-modified protein co-immunoprecipitated with VER2 in vernalized wheat plants but not in devernalized materials. The dynamic of VER2 was observed in transgenic Arabidopsis overexpressing the VER2-GFP fusion protein. Overexpressed VER2 accelerated nuclear migration. Immunogold labeling and indirect immunofluoresence colocalization assay indicated that VER2-GFP was targeted to the secretory pathway. CONCLUSIONS/SIGNIFICANCE O-GlcNAc signaling is involved in the vernalization response in wheat, and phosphorylation is necessary for the lectin VER2 involving O-GlcNAc signaling during vernalization. Our findings open the way to studies of O-GlcNAc protein modification in response to environmental signals in plants.
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Affiliation(s)
- Lijing Xing
- Research Center for Molecular Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, Beijing, China
| | - Juan Li
- Research Center for Molecular Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, Beijing, China
| | - Yunyuan Xu
- Research Center for Molecular Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, Beijing, China
| | - Zhihong Xu
- National Centre for Plant Gene Research, Beijing, China
| | - Kang Chong
- Research Center for Molecular Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, The Chinese Academy of Sciences, Beijing, China
- National Centre for Plant Gene Research, Beijing, China
- * E-mail:
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Grissom PM, Fiedler T, Grishchuk EL, Nicastro D, West RR, McIntosh JR. Kinesin-8 from fission yeast: a heterodimeric, plus-end-directed motor that can couple microtubule depolymerization to cargo movement. Mol Biol Cell 2008; 20:963-72. [PMID: 19037096 DOI: 10.1091/mbc.e08-09-0979] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Fission yeast expresses two kinesin-8s, previously identified and characterized as products of the klp5(+) and klp6(+) genes. These polypeptides colocalize throughout the vegetative cell cycle as they bind cytoplasmic microtubules during interphase, spindle microtubules, and/or kinetochores during early mitosis, and the interpolar spindle as it elongates in anaphase B. Here, we describe in vitro properties of these motor proteins and some truncated versions expressed in either bacteria or Sf9 cells. The motor-plus-neck domain of Klp6p formed soluble dimers that cross-linked microtubules and showed both microtubule-activated ATPase and plus-end-directed motor activities. Full-length Klp5p and Klp6p, coexpressed in Sf9 cells, formed soluble heterodimers with the same activities. The latter recombinant protein could also couple microbeads to the ends of shortening microtubules and use energy from tubulin depolymerization to pull a load in the minus end direction. These results, together with the spindle localizations of these proteins in vivo and their requirement for cell viability in the absence of the Dam1/DASH kinetochore complex, support the hypothesis that fission yeast kinesin-8 contributes both to chromosome congression to the metaphase plate and to the coupling of spindle microtubules to kinetochores during anaphase A.
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Affiliation(s)
- Paula M Grissom
- Department of Molecular, Cellular, and Developmental Biology, University of Colorado, Boulder, CO 80309-0347, USA
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Nag DK, Tikhonenko I, Soga I, Koonce MP. Disruption of four kinesin genes in dictyostelium. BMC Cell Biol 2008; 9:21. [PMID: 18430243 PMCID: PMC2396615 DOI: 10.1186/1471-2121-9-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Accepted: 04/22/2008] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND Kinesin and dynein are the two families of microtubule-based motors that drive much of the intracellular movements in eukaryotic cells. Using a gene knockout strategy, we address here the individual function(s) of four of the 13 kinesin proteins in Dictyostelium. The goal of our ongoing project is to establish a minimal motility proteome for this basal eukaryote, enabling us to contrast motor functions here with the often far more elaborate motor families in the metazoans. RESULTS We performed individual disruptions of the kinesin genes, kif4, kif8, kif10, and kif11. None of the motors encoded by these genes are essential for development or viability of Dictyostelium. Removal of Kif4 (kinesin-7; CENP-E family) significantly impairs the rate of cell growth and, when combined with a previously characterized dynein inhibition, results in dramatic defects in mitotic spindle assembly. Kif8 (kinesin-4; chromokinesin family) and Kif10 (kinesin-8; Kip3 family) appear to cooperate with dynein to organize the interphase radial microtubule array. CONCLUSION The results reported here extend the number of kinesin gene disruptions in Dictyostelium, to now total 10, among the 13 isoforms. None of these motors, individually, are required for short-term viability. In contrast, homologs of at least six of the 10 kinesins are considered essential in humans. Our work underscores the functional redundancy of motor isoforms in basal organisms while highlighting motor specificity in more complex metazoans. Since motor disruption in Dictyostelium can readily be combined with other motility insults and stresses, this organism offers an excellent system to investigate functional interactions among the kinesin motor family.
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Affiliation(s)
- Dilip K Nag
- Division of Molecular Medicine, Wadsworth Center, Albany, NY, 12201-0509, USA
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY, 12201-0509, USA
| | - Irina Tikhonenko
- Division of Molecular Medicine, Wadsworth Center, Albany, NY, 12201-0509, USA
| | - Ikko Soga
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY, 12201-0509, USA
| | - Michael P Koonce
- Division of Molecular Medicine, Wadsworth Center, Albany, NY, 12201-0509, USA
- Department of Biomedical Sciences, School of Public Health, University at Albany, Albany, NY, 12201-0509, USA
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Khmelinskii A, Lawrence C, Roostalu J, Schiebel E. Cdc14-regulated midzone assembly controls anaphase B. ACTA ACUST UNITED AC 2007; 177:981-93. [PMID: 17562791 PMCID: PMC2064359 DOI: 10.1083/jcb.200702145] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Spindle elongation in anaphase of mitosis is a cell cycle–regulated process that requires coordination between polymerization, cross-linking, and sliding of microtubules (MTs). Proteins that assemble at the spindle midzone may be important for this process. In this study, we show that Ase1 and the separase–Slk19 complex drive midzone assembly in yeast. Whereas the conserved MT-bundling protein Ase1 establishes a midzone, separase–Slk19 is required to focus and center midzone components. An important step leading to spindle midzone assembly is the dephosphorylation of Ase1 by the protein phosphatase Cdc14 at the beginning of anaphase. Failure to dephosphorylate Ase1 delocalizes midzone proteins and delays the second, slower phase of anaphase B. In contrast, in cells expressing nonphosphorylated Ase1, anaphase spindle extension is faster, and spindles frequently break. Cdc14 also controls the separase–Slk19 complex indirectly via the Aurora B kinase. Thus, Cdc14 regulates spindle midzone assembly and function directly through Ase1 and indirectly via the separase–Slk19 complex.
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Affiliation(s)
- Anton Khmelinskii
- Zentrum für Molekulare Biologie der Universität Heidelberg, 69120 Heidelberg, Germany
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Haarer BK, Helfant AH, Nelson SA, Cooper JA, Amberg DC. Stable preanaphase spindle positioning requires Bud6p and an apparent interaction between the spindle pole bodies and the neck. EUKARYOTIC CELL 2007; 6:797-807. [PMID: 17416900 PMCID: PMC1899834 DOI: 10.1128/ec.00332-06] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Faithful partitioning of genetic material during cell division requires accurate spatial and temporal positioning of nuclei within dividing cells. In Saccharomyces cerevisiae, nuclear positioning is regulated by an elegant interplay between components of the actin and microtubule cytoskeletons. Regulators of this process include Bud6p (also referred to as the actin-interacting protein Aip3p) and Kar9p, which function to promote contacts between cytoplasmic microtubule ends and actin-delimited cortical attachment points. Here, we present the previously undetected association of Bud6p with the cytoplasmic face of yeast spindle pole bodies, the functional equivalent of metazoan centrosomes. Cells lacking Bud6p show exaggerated movements of the nucleus between mother and daughter cells and display reduced amounts of time a given spindle pole body spends in close association with the neck region of budding cells. Furthermore, overexpression of BUD6 greatly enhances interactions between the spindle pole body and mother-bud neck in a spindle alignment-defective dynactin mutant. These results suggest that association of either spindle pole body with neck components, rather than simply entry of a spindle pole body into the daughter cell, provides a positive signal for the progression of mitosis. We propose that Bud6p, through its localization at both spindle pole bodies and at the mother-bud neck, supports this positive signal and provides a regulatory mechanism to prevent excessive oscillations of preanaphase nuclei, thus reducing the likelihood of mitotic delays and nuclear missegregation.
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Affiliation(s)
- Brian K Haarer
- Department of Biochemistry and Molecular Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
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Mayr MI, Hümmer S, Bormann J, Grüner T, Adio S, Woehlke G, Mayer TU. The human kinesin Kif18A is a motile microtubule depolymerase essential for chromosome congression. Curr Biol 2007; 17:488-98. [PMID: 17346968 DOI: 10.1016/j.cub.2007.02.036] [Citation(s) in RCA: 228] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2006] [Revised: 02/06/2007] [Accepted: 02/08/2007] [Indexed: 10/23/2022]
Abstract
BACKGROUND The accurate alignment of chromosomes at the spindle equator is fundamental for the equal distribution of the genome in mitosis and thus for the genetic integrity of eukaryotes. Although it is well established that chromosome movements are coupled to microtubule dynamics, the underlying mechanism is not well understood. RESULTS By combining RNAi-depletion experiments with in vitro biochemical assays, we demonstrate that the human kinesin Kif18A is a motile microtubule depolymerase essential for chromosome congression in mammalian tissue culture cells. We show that in vitro Kif18A is a slow plus-end-directed kinesin that possesses microtubule depolymerizing activity. Notably, Kif18A like its yeast ortholog Kip3p depolymerizes longer microtubules more quickly than shorter ones. In vivo, Kif18A accumulates in mitosis where it localizes close to the plus ends of kinetochore microtubules. The depletion of Kif18A induces aberrantly long mitotic spindles and loss of tension across sister kinetochores, resulting in the activation of the Mad2-dependent spindle-assembly checkpoint. Live-cell microscopy studies revealed that in Kif18A-depleted cells, chromosomes move at reduced speed and completely fail to align at the spindle equator. CONCLUSIONS These studies identify Kif18A as a dual-functional kinesin and a key component of chromosome congression in mammalian cells.
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Affiliation(s)
- Monika I Mayr
- Chemical Genetics, Independent Research Group, Department of Cell Biology, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany
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Hamada T. Microtubule-associated proteins in higher plants. JOURNAL OF PLANT RESEARCH 2007; 120:79-98. [PMID: 17285404 DOI: 10.1007/s10265-006-0057-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2006] [Accepted: 11/09/2006] [Indexed: 05/09/2023]
Abstract
A variety of microtubule-associated proteins (MAPs) have been reported in higher plants. Microtubule (MT) polymerization starts from the gamma-tubulin complex (gammaTuC), a component of the MT nucleation site. MAP200/MOR1 and katanin regulate the length of the MT by promoting the dynamic instability of MTs and cutting MTs, respectively. In construction of different MT structures, MTs are bundled or are associated with other components--actin filaments, the plasma membrane, and organelles. The MAP65 family and some of kinesin family are important in bundling MTs. MT plus-end-tracking proteins (+TIPs) including end-binding protein 1 (EB1), Arabidopsis thaliana kinesin 5 (ATK5), and SPIRAL 1 (SPR1) localize to the plus end of MTs. It has been suggested that +TIPs are involved in binding of MT to other structures. Phospholipase D (PLD) is a possible candidate responsible for binding of MTs to the plasma membrane. Many candidates have been reported as actin-binding MAPs, for example calponin-homology domain (KCH) family kinesin, kinesin-like calmodulin-binding protein (KCBP), and MAP190. RNA distribution and translation depends on MT structures, and several RNA-related MAPs have been reported. This article gives an overview of predicted roles of these MAPs in higher plants.
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Affiliation(s)
- Takahiro Hamada
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Harima Science Park City, Hyogo 678-1297, Japan.
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Steinberg G. Preparing the way: fungal motors in microtubule organization. Trends Microbiol 2006; 15:14-21. [PMID: 17129730 DOI: 10.1016/j.tim.2006.11.007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2006] [Revised: 09/27/2006] [Accepted: 11/15/2006] [Indexed: 12/24/2022]
Abstract
Fungal growth, development and pathogenicity require hyphal tip growth, which is supported by polar exocytosis at the expanding growth region. It is assumed that molecular motors transport growth supplies along the fibrous elements of the cytoskeleton, such as microtubules, to the hyphal apex. Recent advances in live-cell imaging of fungi revealed additional roles for motors in organizing their own tracks. These unexpected roles of the molecular motors are modifying microtubule dynamics directly, targeting stability-determining factors to microtubule plus ends, and transporting and arranging already-assembled microtubules.
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Affiliation(s)
- Gero Steinberg
- Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany.
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49
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Strawn LA, True HL. Deletion of RNQ1 gene reveals novel functional relationship between divergently transcribed Bik1p/CLIP-170 and Sfi1p in spindle pole body separation. Curr Genet 2006; 50:347-66. [PMID: 16972090 DOI: 10.1007/s00294-006-0098-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2006] [Revised: 08/17/2006] [Accepted: 08/19/2006] [Indexed: 02/03/2023]
Abstract
Spindle pole body (SPB; the microtubule organizing center in yeast) duplication is essential to form a bipolar spindle. The duplicated SPBs must then separate and migrate to opposite sides of the nucleus. We identified a novel functional relationship in SPB separation between the microtubule stabilizing protein Bik1p/CLIP-170 and the SPB half-bridge protein Sfi1p. A genetic interaction between BIK1 and SFI1 was discovered in a synthetic lethal screen using a strain deficient in the prion protein gene RNQ1. RNQ1 deletion reduced expression from the divergently transcribed BIK1, allowing us to identify genetic interactors with bik1. The sfi1-1 bik1 synthetic lethality was suppressed by over-expression of CIK1, KAR1, and PPH21. Genetic analysis indicated that the sfi1-1 bik1 synthetic lethality was unlikely related to the function of Bik1p in the dynein pathway or to defects in spindle position. Furthermore, a sfi1-1 Deltakip2 mutant was viable, suggesting that the Bik1p pool at the cytoplasmic microtubule plus-ends may not be required in sfi1-1. Microscopic examination indicated the sfi1-1 mutant was delayed in SPB duplication, SPB separation, or spindle elongation and the sfi-1 Deltabik1 double mutant arrested with duplicated but unseparated SPBs. These results suggest that Bik1p has a previously uncharacterized function in the separation of duplicated SPBs.
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Affiliation(s)
- Lisa A Strawn
- Department of Cell Biology and Physiology, Washington University School of Medicine, 660 S Euclid Ave, Campus Box 8228, St Louis, MO, 63110, USA.
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50
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Gupta ML, Carvalho P, Roof DM, Pellman D. Plus end-specific depolymerase activity of Kip3, a kinesin-8 protein, explains its role in positioning the yeast mitotic spindle. Nat Cell Biol 2006; 8:913-23. [PMID: 16906148 DOI: 10.1038/ncb1457] [Citation(s) in RCA: 253] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Accepted: 07/27/2006] [Indexed: 11/09/2022]
Abstract
The budding yeast protein Kip3p is a member of the conserved kinesin-8 family of microtubule motors, which are required for microtubule-cortical interactions, normal spindle assembly and kinetochore dynamics. Here, we demonstrate that Kip3p is both a plus end-directed motor and a plus end-specific depolymerase--a unique combination of activities not found in other kinesins. The ATPase activity of Kip3p was activated by both microtubules and unpolymerized tubulin. Furthermore, Kip3p in the ATP-bound state formed a complex with unpolymerized tubulin. Thus, motile kinesin-8s may depolymerize microtubules by a mechanism that is similar to that used by non-motile kinesin-13 proteins. Fluorescent speckle analysis established that, in vivo, Kip3p moved toward and accumulated on the plus ends of growing microtubules, suggesting that motor activity brings Kip3p to its site of action. Globally, and more dramatically on cortical contact, Kip3p promoted catastrophes and pausing, and inhibited microtubule growth. These findings explain the role of Kip3p in positioning the mitotic spindle in budding yeast and potentially other processes controlled by kinesin-8 family members.
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Affiliation(s)
- Mohan L Gupta
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Division of Hematology/Oncology, Children's Hospital Boston and Harvard Medical School, Boston, MA 02115, USA
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