Abstract
Human kinetochores assemble onto centromeric DNA comprising repetitive arrays of the 171 bp α-satellite sequence. To understand the higher-order architecture of the inner kinetochore assembled onto α-satellite arrays, we show cryo-EM structures of CCAN with free DNA, and α-satellite repeat monomers and dimers with CENP-A nucleosomes. CCAN bound to free DNA and a monomeric CENP-A nucleosome engages 70 bp of DNA comprising 30 bp of an upstream α-satellite repeat. This upstream DNA interacts with the histone-fold domain subunits of the CENP-TWSX module in a manner resembling how nucleosomes wrap DNA gyres. A complex of CCAN assembled onto a dimeric α-satellite repeat with two CENP-A nucleosomes shows that CCAN can only be accommodated on the linker DNA by unwrapping DNA from both the CENP-TWSX module and the upstream nucleosome. We discuss the implications of these results for models of CCAN assembly on arrays of α-satellite chromatin containing CENP-A nucleosomes.
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Acknowledgments
We are grateful to the LMB EM Facility and the UK’s national Electron Bioimaging Center (eBIC) for help with the EM data collection; J. Grimmett, T. Darling and I. Clayson for scientific computing; and K. Turton for help with insect cell expression. We thank Andrea Musacchio, Marion Pesenti and Ingrid Vetter for sharing unpublished experimental observations. This work was supported by grants from UKRI/Medical Research Council MC_UP_1201/6 (D.B.) and Cancer Research UK C576/A25675 (D.B.) and to eBIC (proposal BI37660) from the Wellcome Trust, UKRI/MRC and UKRI/BBSRC.
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Yu, C., Muir, K.W., Yang, J. et al. Models for the architecture of the human inner kinetochore on centromeric α-satellite CENP-A nucleosome arrays. Nat Commun (2026). https://doi.org/10.1038/s41467-026-72856-0
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DOI: https://doi.org/10.1038/s41467-026-72856-0
