Reflecting its pleiotropic functions, Polo-like kinase 1 (PLK1) localizes to various sub-cellular structures during mitosis. At kinetochores, PLK1 contributes to microtubule attachments and mitotic checkpoint signaling. Previous studies identified a wealth of potential PLK1 receptors at kinetochores, as well as requirements for various mitotic kinases, including BUB1, Aurora B, and PLK1 itself. Here, we combine ectopic localization, in vitro reconstitution, and kinetochore localization studies to demonstrate that most and likely all of the PLK1 is recruited through BUB1 in the outer kinetochore and centromeric protein U (CENP-U) in the inner kinetochore. BUB1 and CENP-U share a constellation of sequence motifs consisting of a putative PP2A-docking motif and two neighboring PLK1-docking sites, which, contingent on priming phosphorylation by cyclin-dependent kinase 1 and PLK1 itself, bind PLK1 and promote its dimerization. Our results rationalize previous observations and describe a unifying mechanism for recruitment of PLK1 to human kinetochores.

Polo 样激酶 1 (PLK1) 在有丝分裂过程中定位于各种亚细胞结构，反映了其多效性功能。在动粒处，PLK1 有助于微管附着和有丝分裂检查点信号传导。之前的研究发现了着丝粒上大量潜在的 PLK1 受体，以及各种有丝分裂激酶的需求，包括 BUB1、Aurora B 和 PLK1 本身。在这里，我们结合异位定位、体外重建和着丝粒定位研究来证明大多数甚至可能全部 PLK1 是通过外着丝粒中的 BUB1 和内着丝粒中的着丝粒蛋白 U (CENP-U) 招募的。 BUB1 和 CENP-U 共享一组序列基序，由一个假定的 PP2A 对接基序和两个相邻的 PLK1 对接位点组成，这些基序取决于细胞周期蛋白依赖性激酶 1 和 PLK1 本身的引发磷酸化，结合 PLK1 并促进其二聚化。我们的结果合理化了之前的观察结果，并描述了将 PLK1 招募到人类着丝粒的统一机制。