Molecular basis of cooperative assembly of the Ndc80-Ska kinetochore complex on microtubules

niu, y.; Martsch, D.; Ghetti, S.; Mak, J.; Hofnagel, O.; Prumbaum, D.; Funabiki, H.; Musacchio, A.

doi:10.64898/2026.04.18.719381

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bioRxiv · 10.64898/2026.04.18.719381

Molecular basis of cooperative assembly of the Ndc80-Ska kinetochore complex on microtubules

niu, y.·Martsch, D.·Ghetti, S.·Mak, J.·Hofnagel, O.·Prumbaum, D.·Funabiki, H.·Musacchio, A.

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Abstract

Successful chromosome segregation depends on robust kinetochore-microtubule attachments. The outer kinetochore load-bearers Ndc80 and Ska complexes functionally cooperate, but the molecular basis of their interaction remains elusive. Here, we combine cryo-EM and functional investigations of Ndc80:Ska on microtubules. Ndc80 forms longitudinal arrays along single protofilaments using two modules. The HEC1 N-terminal tail stabilizes interactions between microtubule-binding heads regulated by Aurora B. The HEC1 loop, away from microtubules, organizes Ndc80 coiled-coils into stacks matching the periodicity of tubulin subunits. SkaC binds to a previously unknown interface of Ndc80 as well as to microtubules, simultaneously stapling tubulin dimers longitudinally and neighboring protofilaments laterally. Our work demonstrates how several weak interactions of a small number of individual complexes are harnessed to generate a robust and regulated kinetochore coupler.

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niu, y., Martsch, D., Ghetti, S., Mak, J., Hofnagel, O., Prumbaum, D., Funabiki, H., Musacchio, A.. 2026-04-21. Molecular basis of cooperative assembly of the Ndc80-Ska kinetochore complex on microtubules. https://doi.org/10.64898/2026.04.18.719381

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