Cryo‐EM structure of the CENP‐A nucleosome in complex with phosphorylated CENP‐C

The CENP‐A nucleosome is a key structure for kinetochore assembly. Once the CENP‐A nucleosome is established in the centromere, additional proteins recognize the CENP‐A nucleosome to form a kinetochore. CENP‐C and CENP‐N are CENP‐A binding proteins. We previously demonstrated that vertebrate CENP‐C binding to the CENP‐A nucleosome is regulated by CDK1‐mediated CENP‐C phosphorylation. However, it is still unknown how the phosphorylation of CENP‐C regulates its binding to CENP‐A. It is also not completely understood how and whether CENP‐C and CENP‐N act together on the CENP‐A nucleosome. Here, using cryo‐electron microscopy (cryo‐EM) in combination with biochemical approaches, we reveal a stable CENP‐A nucleosome‐binding mode of CENP‐C through unique regions. The chicken CENP‐C structure bound to the CENP‐A nucleosome is stabilized by an intramolecular link through the phosphorylated CENP‐C residue. The stable CENP‐A‐CENP‐C complex excludes CENP‐N from the CENP‐A nucleosome. These findings provide mechanistic insights into the dynamic kinetochore assembly regulated by CDK1‐mediated CENP‐C phosphorylation.