Role of Protein Kinase PLK1 in the Epigenetic Maintenance of Centromeres

The centromere, a chromosome locus defined by the histone H3–like protein centromeric protein A (CENP-A), promotes assembly of the kinetochore to bind microtubules during cell division. Centromere maintenance requires CENP-A to be actively replenished by dedicated protein machinery in the early G 1 phase of the cell cycle to compensate for its dilution after DNA replication. Cyclin-dependent kinases (CDKs) limit CENP-A deposition to once per cell cycle and function as negative regulators outside of early G 1 . Antithetically, Polo-like kinase 1 (PLK1) promotes CENP-A deposition in early G 1 , but the molecular details of this process are still unknown. We reveal here a phosphorylation network that recruits PLK1 to the deposition machinery to control a conformational switch required for licensing the CENP-A deposition reaction. Our findings clarify how PLK1 contributes to the epigenetic maintenance of centromeres.