Cyclin B1 scaffolds MAD1 at the kinetochore corona to activate the mitotic checkpoint

Lindsey A. Allan, Magda Camacho Reis, Giuseppe Ciossani, Pim J. Huigs in ‘t Veld, Sabine Wohlgemuth, Geert J. P. L. Kops, Andrea Musacchio, Adrian T. Saurin (Lead / Corresponding author)

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    40 Citations (Scopus)
    248 Downloads (Pure)

    Abstract

    Cyclin B:CDK1 is the master kinase regulator of mitosis. We show here that, in addition to its kinase functions, mammalian Cyclin B also scaffolds a localised signalling pathway to help preserve genome stability. Cyclin B1 localises to an expanded region of the outer kinetochore, known as the corona, where it scaffolds the spindle assembly checkpoint (SAC) machinery by binding directly to MAD1. In vitro reconstitutions map the key binding interface to a few acidic residues in the N‐terminal region of MAD1, and point mutations in this sequence abolish MAD1 corona localisation and weaken the SAC. Therefore, Cyclin B1 is the long‐sought‐after scaffold that links MAD1 to the corona, and this specific pool of MAD1 is needed to generate a robust SAC response. Robustness arises because Cyclin B1:MAD1 localisation loses dependence on MPS1 kinase after the corona has been established, ensuring that corona‐localised MAD1 can still be phosphorylated when MPS1 activity is low. Therefore, this study explains how corona‐MAD1 generates a robust SAC signal, and it reveals a scaffolding role for the key mitotic kinase, Cyclin B1:CDK1, which ultimately helps to inhibit its own degradation.

    Original languageEnglish
    Article numbere103180
    Number of pages16
    JournalEMBO Journal
    Volume39
    Issue number12
    Early online date23 Mar 2020
    DOIs
    Publication statusPublished - 17 Jun 2020

    Keywords

    • Cyclin B1
    • MAD
    • RZZ complex
    • kinetochore corona
    • spindle assembly checkpoint

    ASJC Scopus subject areas

    • General Neuroscience
    • Molecular Biology
    • General Biochemistry,Genetics and Molecular Biology
    • General Immunology and Microbiology

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