Phosphorylation- and polo-box-dependent binding of Plk1 to Bub1 is required for the kinetochore localization of Plk1

Mol Biol Cell. 2006 Aug;17(8):3705-16. doi: 10.1091/mbc.e06-03-0240. Epub 2006 Jun 7.


Polo-like kinase 1 (Plk1) is required for the generation of the tension-sensing 3F3/2 kinetochore epitope and facilitates kinetochore localization of Mad2 and other spindle checkpoint proteins. Here, we investigate the mechanism by which Plk1 itself is recruited to kinetochores. We show that Plk1 binds to budding uninhibited by benzimidazole 1 (Bub1) in mitotic human cells. The Plk1-Bub1 interaction requires the polo-box domain (PBD) of Plk1 and is enhanced by cyclin-dependent kinase 1 (Cdk1)-mediated phosphorylation of Bub1 at T609. The PBD-dependent binding of Plk1 to Bub1 facilitates phosphorylation of Bub1 by Plk1 in vitro. Depletion of Bub1 in HeLa cells by RNA interference (RNAi) diminishes the kinetochore localization of Plk1. Ectopic expression of the wild-type Bub1, but not the Bub1-T609A mutant, in Bub1-RNAi cells restores the kinetochore localization of Plk1. Our results suggest that phosphorylation of Bub1 at T609 by Cdk1 creates a docking site for the PBD of Plk1 and facilitates the kinetochore recruitment of Plk1.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • CDC2 Protein Kinase / metabolism
  • Cell Cycle Proteins / metabolism*
  • Chromosomal Proteins, Non-Histone / metabolism
  • HeLa Cells
  • Humans
  • Kinetochores / metabolism*
  • Mitosis
  • Molecular Sequence Data
  • Phosphorylation
  • Protein Binding
  • Protein Kinases / chemistry
  • Protein Kinases / metabolism*
  • Protein Structure, Tertiary
  • Protein Transport
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / metabolism*
  • RNA Interference


  • Cell Cycle Proteins
  • Chromosomal Proteins, Non-Histone
  • INCENP protein, human
  • Proto-Oncogene Proteins
  • Protein Kinases
  • BUB1 protein, human
  • Bub1 spindle checkpoint protein
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1
  • CDC2 Protein Kinase