1
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Abstract
The chromosomal passenger complex (CPC) is an important regulator of cell division, which shows dynamic subcellular localization throughout mitosis, including kinetochores and the spindle midzone. In traditional model eukaryotes such as yeasts and humans, the CPC consists of the catalytic subunit Aurora B kinase, its activator INCENP, and the localization module proteins Borealin and Survivin. Intriguingly, Aurora B and INCENP as well as their localization pattern are conserved in kinetoplastids, an evolutionarily divergent group of eukaryotes that possess unique kinetochore proteins and lack homologs of Borealin or Survivin. It is not understood how the kinetoplastid CPC assembles nor how it is targeted to its subcellular destinations during the cell cycle. Here, we identify two orphan kinesins, KIN-A and KIN-B, as bona fide CPC proteins in Trypanosoma brucei, the kinetoplastid parasite that causes African sleeping sickness. KIN-A and KIN-B form a scaffold for the assembly of the remaining CPC subunits. We show that the C-terminal unstructured tail of KIN-A interacts with the KKT8 complex at kinetochores, while its N-terminal motor domain promotes CPC translocation to spindle microtubules. Thus, the KIN-A:KIN-B complex constitutes a unique 'two-in-one' CPC localization module, which directs the CPC to kinetochores from S phase until metaphase and to the central spindle in anaphase. Our findings highlight the evolutionary diversity of CPC proteins and raise the possibility that kinesins may have served as the original transport vehicles for Aurora kinases in early eukaryotes.
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Affiliation(s)
- Daniel Ballmer
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
- The Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological SciencesEdinburghUnited Kingdom
| | - Bungo Akiyoshi
- Department of Biochemistry, University of OxfordOxfordUnited Kingdom
- The Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological SciencesEdinburghUnited Kingdom
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2
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Ludzia P, Hayashi H, Robinson T, Akiyoshi B, Redfield C. NMR study of the structure and dynamics of the BRCT domain from the kinetochore protein KKT4. Biomol NMR Assign 2024:10.1007/s12104-024-10163-9. [PMID: 38453826 DOI: 10.1007/s12104-024-10163-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/18/2024] [Indexed: 03/09/2024]
Abstract
KKT4 is a multi-domain kinetochore protein specific to kinetoplastids, such as Trypanosoma brucei. It lacks significant sequence similarity to known kinetochore proteins in other eukaryotes. Our recent X-ray structure of the C-terminal region of KKT4 shows that it has a tandem BRCT (BRCA1 C Terminus) domain fold with a sulfate ion bound in a typical binding site for a phosphorylated serine or threonine. Here we present the 1H, 13C and 15N resonance assignments for the BRCT domain of KKT4 (KKT4463-645) from T. brucei. We show that the BRCT domain can bind phosphate ions in solution using residues involved in sulfate ion binding in the X-ray structure. We have used these assignments to characterise the secondary structure and backbone dynamics of the BRCT domain in solution. Mutating the residues involved in phosphate ion binding in T. brucei KKT4 BRCT results in growth defects confirming the importance of the BRCT phosphopeptide-binding activity in vivo. These results may facilitate rational drug design efforts in the future to combat diseases caused by kinetoplastid parasites.
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Affiliation(s)
- Patryk Ludzia
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Hanako Hayashi
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Timothy Robinson
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
- Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Michael Swann Building, Max Born Crescent, Edinburgh, EH9 3BF, UK.
| | - Christina Redfield
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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3
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Ballmer D, Lou HJ, Ishii M, Turk BE, Akiyoshi B. An unconventional regulatory circuitry involving Aurora B controls anaphase onset and error-free chromosome segregation in trypanosomes. bioRxiv 2024:2024.01.20.576407. [PMID: 38293145 PMCID: PMC10827227 DOI: 10.1101/2024.01.20.576407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Accurate chromosome segregation during mitosis requires that all chromosomes establish stable bi-oriented attachments with the spindle apparatus. Kinetochores form the interface between chromosomes and spindle microtubules and as such are under tight control by complex regulatory circuitry. As part of the chromosomal passenger complex (CPC), the Aurora B kinase plays a central role within this circuitry by destabilizing improper kinetochore-microtubule attachments and relaying the attachment status to the spindle assembly checkpoint, a feedback control system that delays the onset of anaphase by inhibiting the anaphase-promoting complex/cyclosome. Intriguingly, Aurora B is conserved even in kinetoplastids, an evolutionarily divergent group of eukaryotes, whose kinetochores are composed of a unique set of structural and regulatory proteins. Kinetoplastids do not have a canonical spindle checkpoint and it remains unclear how their kinetochores are regulated to ensure the fidelity and timing of chromosome segregation. Here, we show in Trypanosoma brucei, the kinetoplastid parasite that causes African sleeping sickness, that inhibition of Aurora B using an analogue-sensitive approach arrests cells in metaphase, with a reduction in properly bi-oriented kinetochores. Aurora B phosphorylates several kinetochore proteins in vitro, including the N-terminal region of the divergent Bub1-like protein KKT14. Depletion of KKT14 partially overrides the cell cycle arrest caused by Aurora B inhibition, while overexpression of a non-phosphorylatable KKT14 protein results in a prominent delay in the metaphase-to-anaphase transition. Finally, we demonstrate using a nanobody-based system that re-targeting the catalytic module of the CPC to the outer kinetochore is sufficient to promote mitotic exit but causes massive chromosome mis-segregation in anaphase. Our results indicate that the CPC and KKT14 are involved in an unconventional pathway controlling mitotic exit and error-free chromosome segregation in trypanosomes.
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Affiliation(s)
- Daniel Ballmer
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom
| | - Hua Jane Lou
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
| | - Midori Ishii
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom
- The Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Max Born Crescent Edinburgh, EH9 3BF, United Kingdom
| | - Benjamin E. Turk
- Department of Pharmacology, Yale School of Medicine, New Haven, CT, USA
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, United Kingdom
- The Wellcome Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Max Born Crescent Edinburgh, EH9 3BF, United Kingdom
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4
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Ishii M, Ludzia P, Marcianò G, Allen W, Nerusheva OO, Akiyoshi B. Divergent polo boxes in KKT2 bind KKT1 to initiate the kinetochore assembly cascade in Trypanosoma brucei. Mol Biol Cell 2022; 33:ar143. [PMID: 36129769 PMCID: PMC9727816 DOI: 10.1091/mbc.e22-07-0269-t] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 09/09/2022] [Accepted: 09/14/2022] [Indexed: 02/04/2023] Open
Abstract
Chromosome segregation requires assembly of the macromolecular kinetochore complex onto centromeric DNA. While most eukaryotes have canonical kinetochore proteins that are widely conserved among eukaryotes, evolutionarily divergent kinetoplastids have a unique set of kinetochore proteins. Little is known about the mechanism of kinetochore assembly in kinetoplastids. Here we characterize two homologous kinetoplastid kinetochore proteins, KKT2 and KKT3, that constitutively localize at centromeres. They have three domains that are highly conserved among kinetoplastids: an N-terminal kinase domain of unknown function, the centromere localization domain in the middle, and the C-terminal domain that has weak similarity to polo boxes of Polo-like kinases. We show that the kinase activity of KKT2 is essential for accurate chromosome segregation, while that of KKT3 is dispensable for cell growth in Trypanosoma brucei. Crystal structures of their divergent polo boxes reveal differences between KKT2 and KKT3. We also show that the divergent polo boxes of KKT3 are sufficient to recruit KKT2 in trypanosomes. Furthermore, we demonstrate that the divergent polo boxes of KKT2 interact directly with KKT1 and that KKT1 interacts with KKT6. These results show that the divergent polo boxes of KKT2 and KKT3 are protein-protein interaction domains that initiate kinetochore assembly in T. brucei.
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Affiliation(s)
- Midori Ishii
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Patryk Ludzia
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Gabriele Marcianò
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - William Allen
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Olga O. Nerusheva
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
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5
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Ishii M, Akiyoshi B. Targeted protein degradation using deGradFP in Trypanosoma brucei. Wellcome Open Res 2022; 7:175. [PMID: 35865221 PMCID: PMC9277568 DOI: 10.12688/wellcomeopenres.17964.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/05/2022] [Indexed: 11/20/2022] Open
Abstract
Targeted protein degradation is an invaluable tool in studying the function of proteins. Such a tool was not available in Trypanosoma brucei, an evolutionarily divergent eukaryote that causes human African trypanosomiasis. Here, we have adapted deGradFP (degrade green fluorescent protein [GFP]), a protein degradation system based on the SCF E3 ubiquitin ligase complex and anti-GFP nanobody, in T. brucei. As a proof of principle, we targeted a kinetoplastid kinetochore protein (KKT3) that constitutively localizes at kinetochores in the nucleus. Induction of deGradFP in a cell line that had both alleles of KKT3 tagged with yellow fluorescent protein (YFP) caused a more severe growth defect than RNAi in procyclic (insect form) cells. deGradFP also worked on a cytoplasmic protein (COPII subunit, SEC31). Given the ease in making GFP fusion cell lines in T. brucei, deGradFP can serve as a powerful tool to rapidly deplete proteins of interest, especially those with low turnover rates.
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Affiliation(s)
- Midori Ishii
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
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6
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López-Escobar L, Hänisch B, Halliday C, Ishii M, Akiyoshi B, Dean S, Sunter JD, Wheeler RJ, Gull K. Stage-specific transcription activator ESB1 regulates monoallelic antigen expression in Trypanosoma brucei. Nat Microbiol 2022; 7:1280-1290. [PMID: 35879525 PMCID: PMC9352583 DOI: 10.1038/s41564-022-01175-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 06/14/2022] [Indexed: 11/09/2022]
Abstract
Variant surface glycoprotein (VSG) coats bloodstream form Trypanosoma brucei parasites, and monoallelic VSG expression underpins the antigenic variation necessary for pathogenicity. One of thousands of VSG genes is transcribed by RNA polymerase I in a singular nuclear structure called the expression site body (ESB), but how monoallelic VSG transcription is achieved remains unclear. Using a localization screen of 153 proteins we found one, ESB-specific protein 1 (ESB1), that localized only to the ESB and is expressed only in VSG-expressing life cycle stages. ESB1 associates with DNA near the active VSG promoter and is necessary for VSG expression, with overexpression activating inactive VSG promoters. Mechanistically, ESB1 is necessary for recruitment of a subset of ESB components, including RNA polymerase I, revealing that the ESB has separately assembled subdomains. Because many trypanosomatid parasites have divergent ESB1 orthologues yet do not undergo antigenic variation, ESB1 probably represents an important class of transcription regulators.
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Affiliation(s)
| | - Benjamin Hänisch
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Clare Halliday
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Midori Ishii
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Samuel Dean
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.,Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, UK
| | - Jack Daniel Sunter
- Department of Biological and Medical Sciences, Oxford Brookes University, Oxford, UK.
| | | | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
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7
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Abstract
Targeted protein degradation is an invaluable tool in studying the function of proteins. Such a tool was not available in Trypanosoma brucei, an evolutionarily divergent eukaryote that causes human African trypanosomiasis. Here, we have adapted deGradFP (degrade green fluorescent protein [GFP]), a protein degradation system based on the SCF E3 ubiquitin ligase complex and anti-GFP nanobody, in T. brucei. As a proof of principle, we targeted a kinetoplastid kinetochore protein (KKT3) that constitutively localizes at kinetochores in the nucleus. Induction of deGradFP in a cell line that had both alleles of KKT3 tagged with yellow fluorescent protein (YFP) caused a more severe growth defect than RNAi in procyclic (insect form) cells. deGradFP also worked on a cytoplasmic protein (COPII subunit, SEC31). Given the ease in making GFP fusion cell lines in T. brucei, deGradFP can serve as a powerful tool to rapidly deplete proteins of interest, especially those with low turnover rates.
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Affiliation(s)
- Midori Ishii
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
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8
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Ishii M, Akiyoshi B. Plasticity in centromere organization and kinetochore composition: Lessons from diversity. Curr Opin Cell Biol 2022; 74:47-54. [PMID: 35108654 PMCID: PMC9089191 DOI: 10.1016/j.ceb.2021.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2021] [Revised: 12/27/2021] [Accepted: 12/29/2021] [Indexed: 11/16/2022]
Abstract
Kinetochores are the macromolecular protein complexes that govern chromosome movement by binding spindle microtubules during mitosis and meiosis. Centromeres are the specific chromosomal regions that serve as the platform on which kinetochores assemble. Despite their essentiality for proper chromosome segregation, the size and organization of centromeres vary dramatically between species, while different compositions of kinetochores are found among eukaryotes. Here we discuss recent progress in understanding centromeres and kinetochores in non-traditional model eukaryotes. We specifically focus on select lineages (holocentric insects, early diverging fungi, and kinetoplastids) that lack CENP-A, a centromere-specific histone H3 variant that is critical for kinetochore specification and assembly in many eukaryotes. We also highlight some organisms that might have hitherto unknown types of kinetochore proteins.
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Affiliation(s)
- Midori Ishii
- Department of Biochemistry, University of Oxford, UK
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9
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Marcianò G, Ishii M, Nerusheva OO, Akiyoshi B. Kinetoplastid kinetochore proteins KKT2 and KKT3 have unique centromere localization domains. J Cell Biol 2021; 220:212224. [PMID: 34081090 PMCID: PMC8178753 DOI: 10.1083/jcb.202101022] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/29/2021] [Accepted: 05/12/2021] [Indexed: 12/31/2022] Open
Abstract
The kinetochore is the macromolecular protein complex that assembles onto centromeric DNA and binds spindle microtubules. Evolutionarily divergent kinetoplastids have an unconventional set of kinetochore proteins. It remains unknown how kinetochores assemble at centromeres in these organisms. Here, we characterize KKT2 and KKT3 in the kinetoplastid parasite Trypanosoma brucei. In addition to the N-terminal kinase domain and C-terminal divergent polo boxes, these proteins have a central domain of unknown function. We show that KKT2 and KKT3 are important for the localization of several kinetochore proteins and that their central domains are sufficient for centromere localization. Crystal structures of the KKT2 central domain from two divergent kinetoplastids reveal a unique zinc-binding domain (termed the CL domain for centromere localization), which promotes its kinetochore localization in T. brucei. Mutations in the equivalent domain in KKT3 abolish its kinetochore localization and function. Our work shows that the unique central domains play a critical role in mediating the centromere localization of KKT2 and KKT3.
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Affiliation(s)
| | - Midori Ishii
- Department of Biochemistry, University of Oxford, Oxford, UK
| | | | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, UK
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10
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Abstract
Chromosome segregation in eukaryotes is driven by the kinetochore, a macromolecular complex that connects centromeric DNA to microtubules of the spindle apparatus. Kinetochores in well-studied model eukaryotes consist of a core set of proteins that are broadly conserved among distant eukaryotic phyla. By contrast, unicellular flagellates of the class Kinetoplastida have a unique set of 36 kinetochore components. The evolutionary origin and history of these kinetochores remain unknown. Here, we report evidence of homology between axial element components of the synaptonemal complex and three kinetoplastid kinetochore proteins KKT16-18. The synaptonemal complex is a zipper-like structure that assembles between homologous chromosomes during meiosis to promote recombination. By using sensitive homology detection protocols, we identify divergent orthologues of KKT16-18 in most eukaryotic supergroups, including experimentally established chromosomal axis components, such as Red1 and Rec10 in budding and fission yeast, ASY3-4 in plants and SYCP2-3 in vertebrates. Furthermore, we found 12 recurrent duplications within this ancient eukaryotic SYCP2–3 gene family, providing opportunities for new functional complexes to arise, including KKT16-18 in the kinetoplastid parasite Trypanosoma brucei. We propose the kinetoplastid kinetochore system evolved by repurposing meiotic components of the chromosome synapsis and homologous recombination machinery that were already present in early eukaryotes.
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Affiliation(s)
- Eelco C Tromer
- Department of Biochemistry, University of Cambridge, Cambridge, UK.,Cell Biochemistry, Groningen Institute of Biomolecular Sciences & Biotechnology, University of Groningen, Groningen, The Netherlands
| | - Thomas A Wemyss
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Patryk Ludzia
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Ross F Waller
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, UK
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11
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Ludzia P, Lowe ED, Marcianò G, Mohammed S, Redfield C, Akiyoshi B. Structural characterization of KKT4, an unconventional microtubule-binding kinetochore protein. Structure 2021; 29:1014-1028.e8. [PMID: 33915106 PMCID: PMC8443799 DOI: 10.1016/j.str.2021.04.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 02/17/2021] [Accepted: 04/08/2021] [Indexed: 01/01/2023]
Abstract
The kinetochore is the macromolecular machinery that drives chromosome segregation by interacting with spindle microtubules. Kinetoplastids (such as Trypanosoma brucei), a group of evolutionarily divergent eukaryotes, have a unique set of kinetochore proteins that lack any significant homology to canonical kinetochore components. To date, KKT4 is the only kinetoplastid kinetochore protein that is known to bind microtubules. Here we use X-ray crystallography, NMR spectroscopy, and crosslinking mass spectrometry to characterize the structure and dynamics of KKT4. We show that its microtubule-binding domain consists of a coiled-coil structure followed by a positively charged disordered tail. The structure of the C-terminal BRCT domain of KKT4 reveals that it is likely a phosphorylation-dependent protein-protein interaction domain. The BRCT domain interacts with the N-terminal region of the KKT4 microtubule-binding domain and with a phosphopeptide derived from KKT8. Taken together, these results provide structural insights into the unconventional kinetoplastid kinetochore protein KKT4. Structures of microtubule-binding and BRCT domains in KKT4 are reported The microtubule-binding domain consists of a coiled coil and a disordered tail KKT4 interacts with microtubules via a basic surface at the coiled-coil N terminus KKT4 has a phosphopeptide-binding BRCT domain
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Affiliation(s)
- Patryk Ludzia
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Edward D Lowe
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Gabriele Marcianò
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Shabaz Mohammed
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | | | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
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12
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Ludzia P, Akiyoshi B, Redfield C. 1H, 13C and 15N resonance assignments for the microtubule-binding domain of the kinetoplastid kinetochore protein KKT4 from Trypanosoma brucei. Biomol NMR Assign 2020; 14:309-315. [PMID: 32696260 PMCID: PMC7462909 DOI: 10.1007/s12104-020-09968-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 07/06/2020] [Indexed: 06/11/2023]
Abstract
KKT4 is a kinetoplastid-specific microtubule-binding kinetochore protein that lacks significant similarity to any known kinetochore or microtubule-binding proteins. Here we present the 1H, 13C and 15N resonance assignments for several fragments from the microtubule-binding domain of KKT4 (KKT4115-343) from Trypanosoma brucei. These assignments provide the starting point for detailed investigations of the structure, dynamics and interactions of the microtubule-binding region of KKT4.
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Affiliation(s)
- Patryk Ludzia
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
| | - Christina Redfield
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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13
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Abstract
Centromeres in eukaryotes can be classified into three categories: point centromeres, regional centromeres, or holocentric. Now, a hybrid-type centromere is found in a pathogenic fungus that lacks the key kinetochore component CENP-A.
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Affiliation(s)
- Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
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14
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Ishii M, Akiyoshi B. Characterization of unconventional kinetochore kinases KKT10 and KKT19 in Trypanosoma brucei. J Cell Sci 2020; 133:jcs240978. [PMID: 32184264 PMCID: PMC7197874 DOI: 10.1242/jcs.240978] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 03/02/2020] [Indexed: 12/23/2022] Open
Abstract
The kinetochore is a macromolecular protein complex that drives chromosome segregation in eukaryotes. Unlike most eukaryotes that have canonical kinetochore proteins, evolutionarily divergent kinetoplastids, such as Trypanosoma brucei, have unconventional kinetochore proteins. T. brucei also lacks a canonical spindle checkpoint system, and it therefore remains unknown how mitotic progression is regulated in this organism. Here, we characterized, in the procyclic form of T. brucei, two paralogous kinetochore proteins with a CLK-like kinase domain, KKT10 and KKT19, which localize at kinetochores in metaphase but disappear at the onset of anaphase. We found that these proteins are functionally redundant. Double knockdown of KKT10 and KKT19 led to a significant delay in the metaphase to anaphase transition. We also found that phosphorylation of two kinetochore proteins, KKT4 and KKT7, depended on KKT10 and KKT19 in vivo Finally, we showed that the N-terminal part of KKT7 directly interacts with KKT10 and that kinetochore localization of KKT10 depends not only on KKT7 but also on the KKT8 complex. Our results reveal that kinetochore localization of KKT10 and KKT19 is tightly controlled to regulate the metaphase to anaphase transition in T. bruceiThis article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Midori Ishii
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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15
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Abstract
The kinetochore is a multi-protein complex that drives chromosome segregation in eukaryotes. It assembles onto centromere DNA and interacts with spindle microtubules during mitosis and meiosis. Although most eukaryotes have canonical kinetochore proteins, kinetochores of evolutionarily divergent kinetoplastid species consist of at least 20 unconventional kinetochore proteins (KKT1–20). In addition, 12 proteins (KKT-interacting proteins 1–12, KKIP1–12) are known to localize at kinetochore regions during mitosis. It remains unclear whether KKIP proteins interact with KKT proteins. Here, we report the identification of four additional kinetochore proteins, KKT22–25, in Trypanosoma brucei. KKT22 and KKT23 constitutively localize at kinetochores, while KKT24 and KKT25 localize from S phase to anaphase. KKT23 has a Gcn5-related N-acetyltransferase domain, which is not found in any kinetochore protein known to date. We also show that KKIP1 co-purifies with KKT proteins, but not with KKIP proteins. Finally, our affinity purification of KKIP2/3/4/6 identifies a number of proteins as their potential interaction partners, many of which are implicated in RNA binding or processing. These findings further support the idea that kinetoplastid kinetochores are unconventional.
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Affiliation(s)
- Olga O Nerusheva
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Patryk Ludzia
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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16
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Llauró A, Hayashi H, Bailey ME, Wilson A, Ludzia P, Asbury CL, Akiyoshi B. The kinetoplastid kinetochore protein KKT4 is an unconventional microtubule tip-coupling protein. J Cell Biol 2018; 217:3886-3900. [PMID: 30209069 PMCID: PMC6219724 DOI: 10.1083/jcb.201711181] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 07/23/2018] [Accepted: 08/24/2018] [Indexed: 01/08/2023] Open
Abstract
The evolutionarily divergent class of kinetoplastid organisms has a set of unconventional kinetochore proteins that drive chromosome segregation, but it is unclear which components interact with spindle microtubules. Llauró et al. now identify KKT4 as the first microtubule-binding kinetochore protein in Trypanosoma brucei, a major human pathogenic parasite. Kinetochores are multiprotein machines that drive chromosome segregation by maintaining persistent, load-bearing linkages between chromosomes and dynamic microtubule tips. Kinetochores in commonly studied eukaryotes bind microtubules through widely conserved components like the Ndc80 complex. However, in evolutionarily divergent kinetoplastid species such as Trypanosoma brucei, which causes sleeping sickness, the kinetochores assemble from a unique set of proteins lacking homology to any known microtubule-binding domains. Here, we show that the T. brucei kinetochore protein KKT4 binds directly to microtubules and maintains load-bearing attachments to both growing and shortening microtubule tips. The protein localizes both to kinetochores and to spindle microtubules in vivo, and its depletion causes defects in chromosome segregation. We define a microtubule-binding domain within KKT4 and identify several charged residues important for its microtubule-binding activity. Thus, despite its lack of significant similarity to other known microtubule-binding proteins, KKT4 has key functions required for driving chromosome segregation. We propose that it represents a primary element of the kinetochore–microtubule interface in kinetoplastids.
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Affiliation(s)
- Aida Llauró
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Hanako Hayashi
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Megan E Bailey
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Alex Wilson
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Patryk Ludzia
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Charles L Asbury
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, UK
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17
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Abstract
Kinetoplastids have a nucleus that contains the nuclear genome and a kinetoplast that contains the mitochondrial genome. These single-copy organelles must be duplicated and segregated faithfully to daughter cells at each cell division. In Trypanosoma brucei, although duplication of both organelles starts around the same time, segregation of the kinetoplast precedes that of the nucleus. Cytokinesis subsequently takes place so that daughter cells inherit a single copy of each organelle. Very little is known about the molecular mechanism that governs the timing of these events. Furthermore, it is thought that T. brucei lacks a spindle checkpoint that delays the onset of nuclear division in response to spindle defects. Here we show that a mitotic cyclin CYC6 has a dynamic localization pattern during the cell cycle, including kinetochore localization. Using CYC6 as a molecular cell cycle marker, we confirmed that T. brucei cannot delay the onset of anaphase in response to a bipolar spindle assembly defect. Interestingly, expression of a stabilized form of CYC6 caused the nucleus to arrest in a metaphase-like state without preventing cytokinesis. We propose that trypanosomes have an ability to regulate the timing of nuclear division by modulating the CYC6 protein level, without a spindle checkpoint.
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Affiliation(s)
- Hanako Hayashi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
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18
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Akiyoshi B, Nelson CR, Ranish JA, Biggins S. Corrigendum: Quantitative proteomic analysis of purified yeast kinetochores identifies a PP1 regulatory subunit. Genes Dev 2016; 30:2339. [DOI: 10.1101/gad.291450.116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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Abstract
Kinetochores are macromolecular machines that drive eukaryotic chromosome segregation by interacting with centromeric DNA and spindle microtubules. While most eukaryotes possess conventional kinetochore proteins, evolutionarily distant kinetoplastid species have unconventional kinetochore proteins, composed of at least 19 proteins (KKT1-19). Polo-like kinase (PLK) is not a structural kinetochore component in either system. Here, we report the identification of an additional kinetochore protein, KKT20, in Trypanosoma brucei. KKT20 has sequence similarity with KKT2 and KKT3 in the Cys-rich region, and all three proteins have weak but significant similarity to the polo box domain (PBD) of PLK. These divergent PBDs of KKT2 and KKT20 are sufficient for kinetochore localization in vivo. We propose that the ancestral PLK acquired a Cys-rich region and then underwent gene duplication events to give rise to three structural kinetochore proteins in kinetoplastids.
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Affiliation(s)
| | - Bungo Akiyoshi
- Department of Biochemistry, University of Oxford, Oxford, UK
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20
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Akiyoshi B. Discovery of Unconventional Kinetochores in Kinetoplastids. FASEB J 2015. [DOI: 10.1096/fasebj.29.1_supplement.86.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Bungo Akiyoshi
- Department of BiochemistryUniversity of OxfordOxfordUnited Kingdom
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21
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Kim J, Ishiguro KI, Nambu A, Akiyoshi B, Yokobayashi S, Kagami A, Ishiguro T, Pendas AM, Takeda N, Sakakibara Y, Kitajima TS, Tanno Y, Sakuno T, Watanabe Y. Meikin is a conserved regulator of meiosis-I-specific kinetochore function. Nature 2015; 517:466-71. [PMID: 25533956 DOI: 10.1038/nature14097] [Citation(s) in RCA: 112] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 11/19/2014] [Indexed: 12/11/2022]
Abstract
The kinetochore is the crucial apparatus regulating chromosome segregation in mitosis and meiosis. Particularly in meiosis I, unlike in mitosis, sister kinetochores are captured by microtubules emanating from the same spindle pole (mono-orientation) and centromeric cohesion mediated by cohesin is protected in the following anaphase. Although meiotic kinetochore factors have been identified only in budding and fission yeasts, these molecules and their functions are thought to have diverged earlier. Therefore, a conserved mechanism for meiotic kinetochore regulation remains elusive. Here we have identified in mouse a meiosis-specific kinetochore factor that we termed MEIKIN, which functions in meiosis I but not in meiosis II or mitosis. MEIKIN plays a crucial role in both mono-orientation and centromeric cohesion protection, partly by stabilizing the localization of the cohesin protector shugoshin. These functions are mediated mainly by the activity of Polo-like kinase PLK1, which is enriched to kinetochores in a MEIKIN-dependent manner. Our integrative analysis indicates that the long-awaited key regulator of meiotic kinetochore function is Meikin, which is conserved from yeasts to humans.
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Affiliation(s)
- Jihye Kim
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Kei-ichiro Ishiguro
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Aya Nambu
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Bungo Akiyoshi
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Shihori Yokobayashi
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Ayano Kagami
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Tadashi Ishiguro
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Alberto M Pendas
- Instituto de Biología Molecular y Celular del Cáncer (CSIC-USAL), 37007 Salamanca, Spain
| | - Naoki Takeda
- Center for Animal Resources and Development, Kumamoto University, 2-2-1 Honjo, Kumamoto 860-0811 Japan
| | - Yogo Sakakibara
- Laboratory for Chromosome Segregation, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Tomoya S Kitajima
- Laboratory for Chromosome Segregation, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-Minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Yuji Tanno
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Takeshi Sakuno
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
| | - Yoshinori Watanabe
- Laboratory of Chromosome Dynamics, Institute of Molecular and Cellular Biosciences, University of Tokyo, 1-1-1Yayoi, Tokyo 113-0032, Japan
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22
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Abstract
The kinetochore is the macromolecular protein complex that directs chromosome segregation in eukaryotes. It has been widely assumed that the core kinetochore consists of proteins that are common to all eukaryotes. However, no conventional kinetochore components have been identified in any kinetoplastid genome, thus challenging this assumption of universality. Here, we report the identification of 19 kinetochore proteins (KKT1–19) in Trypanosoma brucei. The majority is conserved among kinetoplastids, but none of them has detectable homology to conventional kinetochore proteins. These proteins instead have a variety of features not found in conventional kinetochore proteins. We propose that kinetoplastids build kinetochores using a distinct set of proteins. These findings provide important insights into the longstanding problem of the position of the root of the eukaryotic tree of life. Conventional kinetochore proteins cannot be identified in any kinetoplastid genome 19 kinetochore proteins were identified in Trypanosoma brucei Kinetoplastids possess unconventional kinetochores This discovery supports the hypothesis that kinetoplastids branched very early
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Affiliation(s)
- Bungo Akiyoshi
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK; Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
| | - Keith Gull
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
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23
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Abstract
Faithful transmission of genetic material is essential for the survival of all organisms. Eukaryotic chromosome segregation is driven by the kinetochore that assembles onto centromeric DNA to capture spindle microtubules and govern the movement of chromosomes. Its molecular mechanism has been actively studied in conventional model eukaryotes, such as yeasts, worms, flies and human. However, these organisms are closely related in the evolutionary time scale and it therefore remains unclear whether all eukaryotes use a similar mechanism. The evolutionary origins of the segregation apparatus also remain enigmatic. To gain insights into these questions, it is critical to perform comparative studies. Here, we review our current understanding of the mitotic mechanism in Trypanosoma brucei, an experimentally tractable kinetoplastid parasite that branched early in eukaryotic history. No canonical kinetochore component has been identified, and the design principle of kinetochores might be fundamentally different in kinetoplastids. Furthermore, these organisms do not appear to possess a functional spindle checkpoint that monitors kinetochore-microtubule attachments. With these unique features and the long evolutionary distance from other eukaryotes, understanding the mechanism of chromosome segregation in T. brucei should reveal fundamental requirements for the eukaryotic segregation machinery, and may also provide hints about the origin and evolution of the segregation apparatus.
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Affiliation(s)
- Bungo Akiyoshi
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
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24
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Driver J, Powers A, Sarangapani K, Akiyoshi B, Duggan N, Biggins S, Asbury C. A Single-Molecule Study to Resolve How Kinases Prevent Chromosomal Mis-Segregation. Biophys J 2013. [DOI: 10.1016/j.bpj.2012.11.844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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25
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Akiyoshi B, Biggins S. Reconstituting the kinetochore–microtubule interface: what, why, and how. Chromosoma 2012; 121:235-50. [PMID: 22289864 DOI: 10.1007/s00412-012-0362-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 01/15/2012] [Accepted: 01/16/2012] [Indexed: 10/14/2022]
Abstract
The kinetochore is the proteinaceous complex that governs the movement of duplicated chromosomes by interacting with spindle microtubules during mitosis and meiosis. Faithful chromosome segregation requires that kinetochores form robust load-bearing attachments to the tips of dynamic spindle microtubules, correct microtubule attachment errors, and delay the onset of anaphase until all chromosomes have made proper attachments. To understand how this macromolecular machine operates to segregate duplicated chromosomes with exquisite accuracy, it is critical to reconstitute and study kinetochore–microtubule interactions in vitro using defined components. Here, we review the current status of reconstitution as well as recent progress in understanding the microtubule-binding functions of kinetochores in vivo.
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Affiliation(s)
- Bungo Akiyoshi
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
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26
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Gonen S, Akiyoshi B, Iadanza MG, Shi D, Duggan N, Biggins S, Gonen T. The structure of purified kinetochores reveals multiple microtubule-attachment sites. Nat Struct Mol Biol 2012; 19:925-9. [PMID: 22885327 PMCID: PMC3443262 DOI: 10.1038/nsmb.2358] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/09/2012] [Indexed: 01/21/2023]
Abstract
Chromosomes must be accurately partitioned to daughter cells to prevent aneuploidy, a hallmark of many tumors and birth defects. Kinetochores are the macromolecular machines that segregate chromosomes by maintaining load-bearing attachments to the dynamic tips of microtubules. Here, we present the structure of isolated budding yeast kinetochore particles as visualized by electron microscopy (EM) and electron tomography of negatively stained preparations. The kinetochore appears as a ~126 nm particle containing a large central hub surrounded by multiple outer globular domains. In the presence of microtubules, some particles also have a ring that encircles the microtubule. Our data show that kinetochores bind to microtubules via multivalent attachments and lay the foundation to uncover the key mechanical and regulatory mechanisms by which kinetochores control chromosome segregation and cell division.
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Affiliation(s)
- Shane Gonen
- Howard Hughes Medical Institute, Department of Biochemistry, University of Washington, Seattle, Washington, USA
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27
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Sarangapani K, Akiyoshi B, Arellano-Santoyo H, Driver J, Duggan N, Powers A, Biggins S, Asbury C. Biophysical Study of Native Yeast Kinetochores Indicates Distinct Roles for Phospho-Regulation of Core Microtubule-Binding Subcomplexes. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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28
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Asbury CL, Sarangapani KK, Akiyoshi B, Duggan N, Driver JW, Arellano-Santoyo H, Powers AF, Biggins S. How Kinetochores Promote Accuracy in Mitosis: Tension, Phosphoregulation, and the Chinese ‘Finger Trap’ Effect. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.1219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022] Open
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29
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Asbury CL, Akiyoshi B, Sarangapani KK, Powers AF, Nelson CR, Reichow SL, Gonen T, Ranish JA, Biggins S. Tension Directly Stabilizes Reconstituted Kinetochore-Microtubule Attachments. Biophys J 2011. [DOI: 10.1016/j.bpj.2010.12.3099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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30
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Akiyoshi B, Nelson CR, Ranish JA, Biggins S. Quantitative proteomic analysis of purified yeast kinetochores identifies a PP1 regulatory subunit. Genes Dev 2009; 23:2887-99. [PMID: 19948764 DOI: 10.1101/gad.1865909] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The kinetochore is a macromolecular complex that controls chromosome segregation and cell cycle progression. When sister kinetochores make bioriented attachments to microtubules from opposite poles, the spindle checkpoint is silenced. Biorientation and the spindle checkpoint are regulated by a balance between the Ipl1/Aurora B protein kinase and the opposing activity of protein phosphatase I (PP1). However, little is known about the regulation of PP1 localization and activity at the kinetochore. Here, we developed a method to purify centromere-bound kinetochores and used quantitative proteomics to identify the Fin1 protein as a PP1 regulatory subunit. The Fin1/PP1 complex is regulated by phosphorylation and 14-3-3 protein binding. When Fin1 is mislocalized, bipolar spindles fail to assemble but the spindle checkpoint is inappropriately silenced due to PP1 activity. These data suggest that Fin1 is a PP1 regulatory subunit whose spatial and temporal activity must be precisely controlled to ensure genomic stability.
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Affiliation(s)
- Bungo Akiyoshi
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
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31
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Akiyoshi B, Watanabe Y. [Modifications of centromeric cohesin for meiosis specific chromosome segregation]. Tanpakushitsu Kakusan Koso 2004; 49:2005-10. [PMID: 15449717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/30/2023]
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