Polo-like kinase 1 independently controls microtubule-nucleating capacity and size of the centrosome

Centrosomes are composed of a centriolar core surrounded by a pericentriolar material (PCM) matrix that docks microtubulenucleating gamma-tubulin complexes. During mitotic entry, the PCM matrix increases in size and nucleating capacity in a process called centrosome maturation. Polo-like kinase 1 (PLK1) is recruited to centrosomes and phosphorylates PCM matrix proteins to drive their self-assembly, which leads to PCM expansion. Here, we show that in addition to controlling PCM expansion, PLK1 independently controls the generation of binding sites for.-tubulin complexes on the PCM matrix. Selectively preventing the generation of PLK1-dependent gamma-tubulin docking sites led to spindle defects and impaired chromosome segregation without affecting PCM expansion, highlighting the importance of phospho-regulated centrosomal.-tubulin docking sites in spindle assembly. Inhibiting both.-tubulin docking and PCM expansion by mutating substrate target sites recapitulated the effects of loss of centrosomal PLK1 on the ability of centrosomes to catalyze spindle assembly.

Automated summary

PLK1 not only controls the expansion of PCM, but also independently regulates the generation of binding sites for gamma-tubulin complexes on the PCM matrix. Inhibiting PLK1-dependent gamma-tubulin docking sites leads to spindle defects and impaired chromosome segregation, highlighting the importance of phospho-regulated centrosomal gamma-tubulin docking sites in spindle assembly.