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Polley S, Raisch T, Ghetti S, Körner M, Terbeck M, Gräter F, Raunser S, Aponte-Santamaría C, Vetter IR, Musacchio A. Structure of the human KMN complex and implications for regulation of its assembly. Nat Struct Mol Biol 2024; 31:861-873. [PMID: 38459128 PMCID: PMC11189300 DOI: 10.1038/s41594-024-01230-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 01/19/2024] [Indexed: 03/10/2024]
Abstract
Biorientation of chromosomes during cell division is necessary for precise dispatching of a mother cell's chromosomes into its two daughters. Kinetochores, large layered structures built on specialized chromosome loci named centromeres, promote biorientation by binding and sensing spindle microtubules. One of the outer layer main components is a ten-subunit assembly comprising Knl1C, Mis12C and Ndc80C (KMN) subcomplexes. The KMN is highly elongated and docks on kinetochores and microtubules through interfaces at its opposite extremes. Here, we combine cryogenic electron microscopy reconstructions and AlphaFold2 predictions to generate a model of the human KMN that reveals all intra-KMN interfaces. We identify and functionally validate two interaction interfaces that link Mis12C to Ndc80C and Knl1C. Through targeted interference experiments, we demonstrate that this mutual organization strongly stabilizes the KMN assembly. Our work thus reports a comprehensive structural and functional analysis of this part of the kinetochore microtubule-binding machinery and elucidates the path of connections from the chromatin-bound components to the force-generating components.
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Affiliation(s)
- Soumitra Polley
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Tobias Raisch
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Sabrina Ghetti
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Marie Körner
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
| | - Melina Terbeck
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Frauke Gräter
- Heidelberg Institute for Theoretical Studies, Heidelberg, Germany
- Max Planck School Matter to Life, Heidelberg, Germany
| | - Stefan Raunser
- Department of Structural Biochemistry, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | | | - Ingrid R Vetter
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Andrea Musacchio
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany.
- Max Planck School Matter to Life, Heidelberg, Germany.
- Centre for Medical Biotechnology, Faculty of Biology, University Duisburg-Essen, Essen, Germany.
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Streeter SA, Williams AG, Evans JR, Wang J, Guarnaccia AD, Florian AC, Al-Tobasei R, Liu Q, Tansey WP, Weissmiller AM. Mitotic gene regulation by the N-MYC-WDR5-PDPK1 nexus. BMC Genomics 2024; 25:360. [PMID: 38605297 PMCID: PMC11007937 DOI: 10.1186/s12864-024-10282-6] [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] [Received: 10/15/2023] [Accepted: 04/03/2024] [Indexed: 04/13/2024] Open
Abstract
BACKGROUND During mitosis the cell depends on proper attachment and segregation of replicated chromosomes to generate two identical progeny. In cancers defined by overexpression or dysregulation of the MYC oncogene this process becomes impaired, leading to genomic instability and tumor evolution. Recently it was discovered that the chromatin regulator WDR5-a critical MYC cofactor-regulates expression of genes needed in mitosis through a direct interaction with the master kinase PDPK1. However, whether PDPK1 and WDR5 contribute to similar mitotic gene regulation in MYC-overexpressing cancers remains unclear. Therefore, to characterize the influence of WDR5 and PDPK1 on mitotic gene expression in cells with high MYC levels, we performed a comparative transcriptomic analysis in neuroblastoma cell lines defined by MYCN-amplification, which results in high cellular levels of the N-MYC protein. RESULTS Using RNA-seq analysis, we identify the genes regulated by N-MYC and PDPK1 in multiple engineered CHP-134 neuroblastoma cell lines and compare them to previously published gene expression data collected in CHP-134 cells following inhibition of WDR5. We find that as expected N-MYC regulates a multitude of genes, including those related to mitosis, but that PDPK1 regulates specific sets of genes involved in development, signaling, and mitosis. Analysis of N-MYC- and PDPK1-regulated genes reveals a small group of commonly controlled genes associated with spindle pole formation and chromosome segregation, which overlap with genes that are also regulated by WDR5. We also find that N-MYC physically interacts with PDPK1 through the WDR5-PDPK1 interaction suggesting regulation of mitotic gene expression may be achieved through a N-MYC-WDR5-PDPK1 nexus. CONCLUSIONS Overall, we identify a small group of genes highly enriched within functional gene categories related to mitotic processes that are commonly regulated by N-MYC, WDR5, and PDPK1 and suggest that a tripartite interaction between the three regulators may be responsible for setting the level of mitotic gene regulation in N-MYC amplified cell lines. This study provides a foundation for future studies to determine the exact mechanism by which N-MYC, WDR5, and PDPK1 converge on cell cycle related processes.
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Affiliation(s)
- Sarah A Streeter
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - Alexandria G Williams
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - James R Evans
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, 37132, USA
| | - Jing Wang
- Center for Quantitative Sciences, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, 37203, USA
| | - Alissa D Guarnaccia
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA
- Department of Discovery Oncology, Genentech Inc, South San Francisco, CA, 94080, USA
| | - Andrea C Florian
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA
- Department of Biology, Belmont University, Nashville, TN, 37212, USA
| | - Rafet Al-Tobasei
- Department of Computer Science, Middle Tennessee State University, Murfreesboro, TN, 32132, USA
| | - Qi Liu
- Center for Quantitative Sciences, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, 37203, USA
| | - William P Tansey
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA
| | - April M Weissmiller
- Department of Biology, Middle Tennessee State University, Murfreesboro, TN, 37132, USA.
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Narayanan A, Reza MH, Sanyal K. Behind the scenes: Centromere-driven genomic innovations in fungal pathogens. PLoS Pathog 2024; 20:e1012080. [PMID: 38547101 PMCID: PMC10977804 DOI: 10.1371/journal.ppat.1012080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/02/2024] Open
Affiliation(s)
- Aswathy Narayanan
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
| | - Md. Hashim Reza
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
| | - Kaustuv Sanyal
- Molecular Mycology Laboratory, Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru, India
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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] [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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Sridhar S, Fukagawa T. Kinetochore Architecture Employs Diverse Linker Strategies Across Evolution. Front Cell Dev Biol 2022; 10:862637. [PMID: 35800888 PMCID: PMC9252888 DOI: 10.3389/fcell.2022.862637] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 05/23/2022] [Indexed: 01/09/2023] Open
Abstract
The assembly of a functional kinetochore on centromeric chromatin is necessary to connect chromosomes to the mitotic spindle, ensuring accurate chromosome segregation. This connecting function of the kinetochore presents multiple internal and external structural challenges. A microtubule interacting outer kinetochore and centromeric chromatin interacting inner kinetochore effectively confront forces from the external spindle and centromere, respectively. While internally, special inner kinetochore proteins, defined as “linkers,” simultaneously interact with centromeric chromatin and the outer kinetochore to enable association with the mitotic spindle. With the ability to simultaneously interact with outer kinetochore components and centromeric chromatin, linker proteins such as centromere protein (CENP)-C or CENP-T in vertebrates and, additionally CENP-QOkp1-UAme1 in yeasts, also perform the function of force propagation within the kinetochore. Recent efforts have revealed an array of linker pathways strategies to effectively recruit the largely conserved outer kinetochore. In this review, we examine these linkages used to propagate force and recruit the outer kinetochore across evolution. Further, we look at their known regulatory pathways and implications on kinetochore structural diversity and plasticity.
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