1
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Perez-Bertoldi JM, Zhao Y, Thawani A, Yildiz A, Nogales E. Molecular interplay between HURP and Kif18A in mitotic spindle regulation. RESEARCH SQUARE 2024:rs.3.rs-4249615. [PMID: 38854046 PMCID: PMC11160874 DOI: 10.21203/rs.3.rs-4249615/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
During mitosis, microtubule dynamics are regulated to ensure proper alignment and segregation of chromosomes. The dynamics of kinetochore-attached microtubules are regulated by hepatoma-upregulated protein (HURP) and the mitotic kinesin-8 Kif18A, but the underlying mechanism remains elusive. Using single-molecule imaging in vitro, we demonstrate that Kif18A motility is regulated by HURP. While sparse decoration of HURP activates the motor, higher concentrations hinder processive motility. To shed light on this behavior, we determined the binding mode of HURP to microtubules using Cryo-EM. The structure reveals that one HURP motif spans laterally across β-tubulin, while a second motif binds between adjacent protofilaments. HURP partially overlaps with the microtubule-binding site of the Kif18A motor domain, indicating that excess HURP inhibits Kif18A motility by steric exclusion. We also observed that HURP and Kif18A function together to suppress dynamics of the microtubule plus-end, providing a mechanistic basis for how they collectively serve in spindle length control.
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Affiliation(s)
| | - Yuanchang Zhao
- Physics Department, University of California, Berkeley, CA, USA
| | - Akanksha Thawani
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Ahmet Yildiz
- Biophysics Graduate Group, University of California, Berkeley, CA, USA
- Physics Department, University of California, Berkeley, CA, USA
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Eva Nogales
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Molecular Biophysics and Integrative Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
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2
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Perez-Bertoldi JM, Zhao Y, Thawani A, Yildiz A, Nogales E. Molecular interplay between HURP and Kif18A in mitotic spindle regulation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.11.589088. [PMID: 38645125 PMCID: PMC11030443 DOI: 10.1101/2024.04.11.589088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/23/2024]
Abstract
During mitosis, microtubule dynamics are regulated to ensure proper alignment and segregation of chromosomes. The dynamics of kinetochore-attached microtubules are regulated by hepatoma-upregulated protein (HURP) and the mitotic kinesin-8 Kif18A, but the underlying mechanism remains elusive. Using single-molecule imaging in vitro , we demonstrate that Kif18A motility is regulated by HURP. While sparse decoration of HURP activates the motor, higher concentrations hinder processive motility. To shed light on this behavior, we determined the binding mode of HURP to microtubules using Cryo-EM. The structure reveals that one HURP motif spans laterally across β-tubulin, while a second motif binds between adjacent protofilaments. HURP partially overlaps with the microtubule-binding site of the Kif18A motor domain, indicating that excess HURP inhibits Kif18A motility by steric exclusion. We also observed that HURP and Kif18A function together to suppress dynamics of the microtubule plus-end, providing a mechanistic basis for how they collectively serve in spindle length control.
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3
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Laporte D, Massoni-Laporte A, Lefranc C, Dompierre J, Mauboules D, Nsamba ET, Royou A, Gal L, Schuldiner M, Gupta ML, Sagot I. A stable microtubule bundle formed through an orchestrated multistep process controls quiescence exit. eLife 2024; 12:RP89958. [PMID: 38527106 PMCID: PMC10963028 DOI: 10.7554/elife.89958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2024] Open
Abstract
Cells fine-tune microtubule assembly in both space and time to give rise to distinct edifices with specific cellular functions. In proliferating cells, microtubules are highly dynamics, and proliferation cessation often leads to their stabilization. One of the most stable microtubule structures identified to date is the nuclear bundle assembled in quiescent yeast. In this article, we characterize the original multistep process driving the assembly of this structure. This Aurora B-dependent mechanism follows a precise temporality that relies on the sequential actions of kinesin-14, kinesin-5, and involves both microtubule-kinetochore and kinetochore-kinetochore interactions. Upon quiescence exit, the microtubule bundle is disassembled via a cooperative process involving kinesin-8 and its full disassembly is required prior to cells re-entry into proliferation. Overall, our study provides the first description, at the molecular scale, of the entire life cycle of a stable microtubule structure in vivo and sheds light on its physiological function.
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Affiliation(s)
| | | | | | | | | | - Emmanuel T Nsamba
- Genetics, Development, and Cell Biology, Iowa State UniversityAmesUnited States
| | - Anne Royou
- Univ. Bordeaux, CNRS, IBGC, UMR 5095BordeauxFrance
| | - Lihi Gal
- Department of Molecular Genetics, Weizmann Institute of ScienceRehovotIsrael
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of ScienceRehovotIsrael
| | - Mohan L Gupta
- Genetics, Development, and Cell Biology, Iowa State UniversityAmesUnited States
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4
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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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5
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Ciorîță A, Bugiel M, Sudhakar S, Schäffer E, Jannasch A. Single depolymerizing and transport kinesins stabilize microtubule ends. Cytoskeleton (Hoboken) 2021; 78:177-184. [PMID: 34310069 DOI: 10.1002/cm.21681] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 07/14/2021] [Accepted: 07/19/2021] [Indexed: 11/07/2022]
Abstract
Microtubules are highly dynamic cellular filaments and an accurate control of their length is important for many intracellular processes like cell division. Among other factors, microtubule length is actively modulated by motors from the kinesin superfamily. For example, yeast kinesin-8, Kip3, motors depolymerize microtubules by a cooperative, force- and length-dependent mechanism. However, whether single motors can also depolymerize microtubules is unclear. Here, we measured how single kinesin motors influenced the stability of microtubules in an in vitro assay. Using label-free interference reflection microscopy, we determined the spontaneous microtubule depolymerization rate of stabilized microtubules in the presence of kinesins. Surprisingly, we found that both single Kip3 and nondepolymerizing kinesin-1 transport motors, used as a control, stabilized microtubules further. For Kip3, this behavior is contrary to the collective force-dependent depolymerization activity of multiple motors. Because of the control measurement, the finding may hint at a more general stabilization mechanism. The complex, concentration-dependent interaction with microtubule ends provides new insights into the molecular mechanism of kinesin-8 and its regulatory function of microtubule length.
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Affiliation(s)
- Alexandra Ciorîță
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany.,National Institute for Research and Development of Isotopic and Molecular Technologies, Integrated Electron Microscopy Laboratory, Cluj-Napoca, Romania
| | - Michael Bugiel
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Swathi Sudhakar
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany.,MRC London Institute of Medical Science, Imperial College London, London, UK
| | - Erik Schäffer
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
| | - Anita Jannasch
- Center for Plant Molecular Biology (ZMBP), University of Tübingen, Tübingen, Germany
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6
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Barisic M, Rajendraprasad G, Steblyanko Y. The metaphase spindle at steady state - Mechanism and functions of microtubule poleward flux. Semin Cell Dev Biol 2021; 117:99-117. [PMID: 34053864 DOI: 10.1016/j.semcdb.2021.05.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/13/2021] [Accepted: 05/13/2021] [Indexed: 11/24/2022]
Abstract
The mitotic spindle is a bipolar cellular structure, built from tubulin polymers, called microtubules, and interacting proteins. This macromolecular machine orchestrates chromosome segregation, thereby ensuring accurate distribution of genetic material into the two daughter cells during cell division. Powered by GTP hydrolysis upon tubulin polymerization, the microtubule ends exhibit a metastable behavior known as the dynamic instability, during which they stochastically switch between the growth and shrinkage phases. In the context of the mitotic spindle, dynamic instability is furthermore regulated by microtubule-associated proteins and motor proteins, which enables the spindle to undergo profound changes during mitosis. This highly dynamic behavior is essential for chromosome capture and congression in prometaphase, as well as for chromosome alignment to the spindle equator in metaphase and their segregation in anaphase. In this review we focus on the mechanisms underlying microtubule dynamics and sliding and their importance for the maintenance of shape, structure and dynamics of the metaphase spindle. We discuss how these spindle properties are related to the phenomenon of microtubule poleward flux, highlighting its highly cooperative molecular basis and role in keeping the metaphase spindle at a steady state.
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Affiliation(s)
- Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark; Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
| | - Girish Rajendraprasad
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark
| | - Yulia Steblyanko
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark
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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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Lin Y, Wei YL, She ZY. Kinesin-8 motors: regulation of microtubule dynamics and chromosome movements. Chromosoma 2020; 129:99-110. [PMID: 32417983 DOI: 10.1007/s00412-020-00736-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 05/06/2020] [Accepted: 05/07/2020] [Indexed: 02/01/2023]
Abstract
Microtubules are essential for intracellular transport, cell motility, spindle assembly, and chromosome segregation during cell division. Microtubule dynamics regulate the proper spindle organization and thus contribute to chromosome congression and segregation. Accumulating studies suggest that kinesin-8 motors are emerging regulators of microtubule dynamics and organizations. In this review, we provide an overview of the studies focused on kinesin-8 motors in cell division. We discuss the structures and molecular kinetics of kinesin-8 motors. We highlight the essential roles and mechanisms of kinesin-8 in the regulation of microtubule dynamics and spindle organization. We also shed light on the functions of kinesin-8 motors in chromosome movement and the spindle assembly checkpoint during the cell cycle.
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Affiliation(s)
- Yang Lin
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China.,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China
| | - Ya-Lan Wei
- Fujian Obstetrics and Gynecology Hospital, Fuzhou, 350011, Fujian, China.,Medical Research Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, 350001, Fujian, China
| | - Zhen-Yu She
- Department of Cell Biology and Genetics, The School of Basic Medical Sciences, Fujian Medical University, Fuzhou, 350122, Fujian, China. .,Key Laboratory of Stem Cell Engineering and Regenerative Medicine, Fujian Province University, Fuzhou, 350122, Fujian, China.
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9
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Gicking AM, Wang P, Liu C, Mickolajczyk KJ, Guo L, Hancock WO, Qiu W. The Orphan Kinesin PAKRP2 Achieves Processive Motility via a Noncanonical Stepping Mechanism. Biophys J 2019; 116:1270-1281. [PMID: 30902363 DOI: 10.1016/j.bpj.2019.02.019] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 02/07/2019] [Accepted: 02/19/2019] [Indexed: 12/27/2022] Open
Abstract
Phragmoplast-associated kinesin-related protein 2 (PAKRP2) is an orphan kinesin in Arabidopsis thaliana that is thought to transport vesicles along phragmoplast microtubules for cell plate formation. Here, using single-molecule fluorescence microscopy, we show that PAKRP2 is the first orphan kinesin to exhibit processive plus-end-directed motility on single microtubules as individual homodimers. Our results show that PAKRP2 processivity is achieved despite having an exceptionally long (32 residues) neck linker. Furthermore, using high-resolution nanoparticle tracking, we find that PAKRP2 steps via a hand-over-hand mechanism that includes frequent side steps, a prolonged diffusional search of the tethered head, and tight coupling of the ATP hydrolysis cycle to the forward-stepping cycle. Interestingly, truncating the PAKRP2 neck linker to 14 residues decreases the run length of PAKRP2; thus, the long neck linker enhances the processive behavior. Based on the canonical model of kinesin stepping, such a long neck linker is expected to decrease the processivity and disrupt the coupling of ATP hydrolysis to forward stepping. Therefore, we conclude that PAKRP2 employs a noncanonical strategy for processive motility, wherein a long neck linker is coupled with a slow ATP hydrolysis rate to allow for an extended diffusional search during each step without sacrificing processivity or efficiency.
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Affiliation(s)
| | - Pan Wang
- Department of Physics, Oregon State University, Corvallis, Oregon; School of Physics and Electronics, Henan University, Kaifeng, Henan, China
| | - Chun Liu
- Pearl River Fisheries Research Institute, Guangzhou, China
| | - Keith J Mickolajczyk
- Department of Biomedical Engineering, Penn State University, University Park, Pennsylvania; Intercollege Graduate Degree Program in Bioengineering, Penn State University, University Park, Pennsylvania
| | - Lijun Guo
- School of Physics and Electronics, Henan University, Kaifeng, Henan, China
| | - William O Hancock
- Department of Biomedical Engineering, Penn State University, University Park, Pennsylvania; Intercollege Graduate Degree Program in Bioengineering, Penn State University, University Park, Pennsylvania
| | - Weihong Qiu
- Department of Physics, Oregon State University, Corvallis, Oregon; Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon.
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10
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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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11
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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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12
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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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13
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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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14
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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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15
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Ghosh S, Pradeep VNS, Muhuri S, Pagonabarraga I, Chaudhuri D. Bidirectional motion of filaments: the role of motor proteins and passive cross linkers. SOFT MATTER 2017; 13:7129-7140. [PMID: 28858369 DOI: 10.1039/c7sm01110e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In eukaryotic cells, motor proteins (MPs) bind to cytoskeletal filaments and move along them in a directed manner generating active stresses. During cell division a spindle structure of overlapping antiparallel microtubules forms whose stability and dynamics under the influence of MPs have been studied extensively. Although passive cross linkers (PCLs) are known to provide structural stability to a filamentous network, consequences of the interplay between ATP dependent active forces of MPs and passive entropic forces of PCLs on filamentous overlap remain largely unexplored. Here, we formulate and characterize a model to study this, using linear stability analysis and numerical integration. In the presence of PCLs, we find dynamic phase transitions with changing activity exhibiting regimes of stable partial overlap with or without oscillations, instability towards complete overlap, and stable limit cycle oscillations that emerge via a supercritical Hopf bifurcation characterized by an oscillation frequency determined by the MP and PCL parameters. We show that the overlap dynamics and stability depend crucially on whether both the filaments of an overlapping pair are movable or one is immobilized, having potential implications for in vivo and in vitro studies.
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Affiliation(s)
- Subhadip Ghosh
- Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005, India.
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16
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Ghiretti AE, Thies E, Tokito MK, Lin T, Ostap EM, Kneussel M, Holzbaur ELF. Activity-Dependent Regulation of Distinct Transport and Cytoskeletal Remodeling Functions of the Dendritic Kinesin KIF21B. Neuron 2016; 92:857-872. [PMID: 27817978 DOI: 10.1016/j.neuron.2016.10.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 08/05/2016] [Accepted: 09/20/2016] [Indexed: 01/19/2023]
Abstract
The dendritic arbor is subject to continual activity-dependent remodeling, requiring a balance between directed cargo trafficking and dynamic restructuring of the underlying microtubule tracks. How cytoskeletal components are able to dynamically regulate these processes to maintain this balance remains largely unknown. By combining single-molecule assays and live imaging in rat hippocampal neurons, we have identified the kinesin-4 KIF21B as a molecular regulator of activity-dependent trafficking and microtubule dynamicity in dendrites. We find that KIF21B contributes to the retrograde trafficking of brain-derived neurotrophic factor (BDNF)-TrkB complexes and also regulates microtubule dynamics through a separable, non-motor microtubule-binding domain. Neuronal activity enhances the motility of KIF21B at the expense of its role in cytoskeletal remodeling, the first example of a kinesin whose function is directly tuned to neuronal activity state. These studies suggest a model in which KIF21B navigates the complex cytoskeletal environment of dendrites by compartmentalizing functions in an activity-dependent manner.
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Affiliation(s)
- Amy E Ghiretti
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Edda Thies
- Department of Molecular Neurogenetics, ZMNH, University Medical Center Hamburg-Eppendorf, Falkenried 94, 20251 Hamburg, Germany
| | - Mariko K Tokito
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Tianming Lin
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - E Michael Ostap
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, Philadelphia, PA 19104, USA
| | - Matthias Kneussel
- Department of Molecular Neurogenetics, ZMNH, University Medical Center Hamburg-Eppendorf, Falkenried 94, 20251 Hamburg, Germany
| | - Erika L F Holzbaur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, 415 Curie Boulevard, Philadelphia, PA 19104, USA.
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17
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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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18
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Sekulic DL, Sataric BM, Zdravkovic S, Bugay AN, Sataric MV. Nonlinear dynamics of C-terminal tails in cellular microtubules. CHAOS (WOODBURY, N.Y.) 2016; 26:073119. [PMID: 27475079 DOI: 10.1063/1.4959802] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The mechanical and electrical properties, and information processing capabilities of microtubules are the permanent subject of interest for carrying out experiments in vitro and in silico, as well as for theoretical attempts to elucidate the underlying processes. In this paper, we developed a new model of the mechano-electrical waves elicited in the rows of very flexible C-terminal tails which decorate the outer surface of each microtubule. The fact that C-terminal tails play very diverse roles in many cellular functions, such as recruitment of motor proteins and microtubule-associated proteins, motivated us to consider their collective dynamics as the source of localized waves aimed for communication between microtubule and associated proteins. Our approach is based on the ferroelectric liquid crystal model and it leads to the effective asymmetric double-well potential which brings about the conditions for the appearance of kink-waves conducted by intrinsic electric fields embedded in microtubules. These kinks can serve as the signals for control and regulation of intracellular traffic along microtubules performed by processive motions of motor proteins, primarly from kinesin and dynein families. On the other hand, they can be precursors for initiation of dynamical instability of microtubules by recruiting the proper proteins responsible for the depolymerization process.
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Affiliation(s)
- Dalibor L Sekulic
- University of Novi Sad, Faculty of Technical Sciences, Novi Sad, Serbia
| | - Bogdan M Sataric
- University of Novi Sad, Faculty of Technical Sciences, Novi Sad, Serbia
| | - Slobodan Zdravkovic
- University of Belgrade, Institute of Nuclear Sciences Vinca, Belgrade, Serbia
| | - Aleksandr N Bugay
- Laboratory of Radiation Biology, Joint Institute for Nuclear Research, Dubna, Russia
| | - Miljko V Sataric
- University of Novi Sad, Faculty of Technical Sciences, Novi Sad, Serbia
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19
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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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Markus SM, Omer S, Baranowski K, Lee WL. Improved Plasmids for Fluorescent Protein Tagging of Microtubules in Saccharomyces cerevisiae. Traffic 2015; 16:773-786. [PMID: 25711127 PMCID: PMC4795465 DOI: 10.1111/tra.12276] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 02/23/2015] [Accepted: 02/22/2015] [Indexed: 01/13/2023]
Abstract
The ability to fluorescently label microtubules in live cells has enabled numerous studies of motile and mitotic processes. Such studies are particularly useful in budding yeast owing to the ease with which they can be genetically manipulated and imaged by live cell fluorescence microscopy. Because of problems associated with fusing genes encoding fluorescent proteins (FPs) to the native α-tubulin (TUB1) gene, the FP-Tub1 fusion is generally integrated into the genome such that the endogenous TUB1 locus is left intact. Although such modifications have no apparent consequences on cell viability, it is unknown if these genome-integrated FP-tubulin fusions negatively affect microtubule functions. Thus, a simple, economical and highly sensitive assay of microtubule function is required. Furthermore, the current plasmids available for generation of FP-Tub1 fusions have not kept pace with the development of improved FPs. Here, we have developed a simple and sensitive assay of microtubule function that is sufficient to identify microtubule defects that were not apparent by fluorescence microscopy or cell growth assays. Using results obtained from this assay, we have engineered a new family of 30 FP-Tub1 plasmids that use various improved FPs and numerous selectable markers that upon genome integration have no apparent defect on microtubule function.
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Affiliation(s)
| | | | - Kaitlyn Baranowski
- Biology Department, University of Massachusetts Amherst, 221 Morrill South, 611 North Pleasant Street, Amherst, MA 01003
| | - Wei-Lih Lee
- Biology Department, University of Massachusetts Amherst, 221 Morrill South, 611 North Pleasant Street, Amherst, MA 01003
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