Molecular basis of Cyclin B1-CDK1 recruitment by MAD1
- 1Division of Cell and Molecular Biology, The Institute of Cancer Research, London, UK; Department of Cell and Molecular Biology, St. Jude Children?s Research Hos
Abstract
The interaction between Cyclin B1-CDK1 and MAD1 recruits kinase activity to the nuclear pore complex and kinetochore corona to sustain spindle assembly checkpoint (SAC) signaling. Here, we characterize a short linear motif (SLiM) within MAD1 that mediates its interaction with Cyclin B1. This SLiM peptide is specific for B-type cyclins and lacks the canonical "RxL" cyclin-binding consensus sequence, suggesting a distinct mode of cyclin recognition. Using a combination of deep mutational scanning, structural analysis by cryogenic electron microscopy, and binding affinity measurements, we define the molecular basis of the Cyclin B1-MAD1 interaction. These approaches reveal that a short MAD1 peptide binds as an -helix to the RxL-binding hydrophobic patch of Cyclin B1. The interaction employs hydrophobic contacts that overlap with those used by canonical RxL motifs, but is distinguished by additional contacts and sequence features that confer preferential recognition by B-type cyclins while excluding other cyclin types. We also show that the MAD1 motif is sufficient to confer B-type cyclin-specific substrate phosphorylation in mitotic cells. Together, these findings reveal a non-canonical, B-type cyclin-specific helical binding mode that ensures selective Cyclin B1-CDK1 recruitment at two critical stages of SAC signaling, and suggest potential strategies for selective therapeutic targeting of this interaction.
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BibTeX
@misc{ord2026molecular,
title = {{Molecular basis of Cyclin B1-CDK1 recruitment by MAD1}},
author = {M. Ord and N. de Martin Garrido and M. J. Winters and M. S. Subbanna and J. Kliche and C. Benz and S. L. Williams and Y. Ivarsson and B. J. Greber and P. M. Pryciak and N. E. Davey},
howpublished = {bioRxiv},
year = {2026},
month = nov,
doi = {10.64898/2026.11.01.762963},
url = {https://www.biorxiv.org/content/10.64898/2026.11.01.762963v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - Molecular basis of Cyclin B1-CDK1 recruitment by MAD1
AU - M. Ord
AU - N. de Martin Garrido
AU - M. J. Winters
AU - M. S. Subbanna
AU - J. Kliche
AU - C. Benz
AU - S. L. Williams
AU - Y. Ivarsson
AU - B. J. Greber
AU - P. M. Pryciak
AU - N. E. Davey
PY - 2026
DA - 2026/11/01
PB - bioRxiv
DO - 10.64898/2026.11.01.762963
UR - https://www.biorxiv.org/content/10.64898/2026.11.01.762963v1
AB - The interaction between Cyclin B1-CDK1 and MAD1 recruits kinase activity to the nuclear pore complex and kinetochore corona to sustain spindle assembly checkpoint (SAC) signaling. Here, we characterize a short linear motif (SLiM) within MAD1 that mediates its interaction with Cyclin B1. This SLiM peptide is specific for B-type cyclins and lacks the canonical "RxL" cyclin-binding consensus sequence, suggesting a distinct mode of cyclin recognition. Using a combination of deep mutational scanning, structural analysis by cryogenic electron microscopy, and binding affinity measurements, we define the molecular basis of the Cyclin B1-MAD1 interaction. These approaches reveal that a short MAD1 peptide binds as an -helix to the RxL-binding hydrophobic patch of Cyclin B1. The interaction employs hydrophobic contacts that overlap with those used by canonical RxL motifs, but is distinguished by additional contacts and sequence features that confer preferential recognition by B-type cyclins while excluding other cyclin types. We also show that the MAD1 motif is sufficient to confer B-type cyclin-specific substrate phosphorylation in mitotic cells. Together, these findings reveal a non-canonical, B-type cyclin-specific helical binding mode that ensures selective Cyclin B1-CDK1 recruitment at two critical stages of SAC signaling, and suggest potential strategies for selective therapeutic targeting of this interaction.
ER -