Models for the architecture of the human inner kinetochore on centromeric α-satellite CENP-A nucleosome arrays.
basic_science · Level V
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- Record sourced from PubMed, PMID 42120391.
- Also identified by DOI 10.1038/s41467-026-72856-0.
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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.