Dynactin helps target Polo-like kinase 1 to kinetochores via its left-handed beta-helical p27 subunit

EMBO J. 2013 Apr 3;32(7):1023-35. doi: 10.1038/emboj.2013.30. Epub 2013 Mar 1.

Abstract

Dynactin is a protein complex required for the in vivo function of cytoplasmic dynein, a microtubule (MT)-based motor. Dynactin binds both dynein and MTs via its p150(Glued) subunit, but little is known about the 'pointed-end complex' that includes the protein subunits Arp11, p62 and the p27/p25 heterodimer. Here, we show that the p27/p25 heterodimer undergoes mitotic phosphorylation by cyclin-dependent kinase 1 (Cdk1) at a single site, p27 Thr186, to generate an anchoring site for polo-like kinase 1 (Plk1) at kinetochores. Removal of p27/p25 from dynactin results in reduced levels of Plk1 and its phosphorylated substrates at kinetochores in prometaphase, which correlates with aberrant kinetochore-MT interactions, improper chromosome alignment and abbreviated mitosis. To investigate the structural implications of p27 phosphorylation, we determined the structure of human p27. This revealed an unusual left-handed β-helix domain, with the phosphorylation site located within a disordered, C-terminal segment. We conclude that dynactin plays a previously undescribed regulatory role in the spindle assembly checkpoint by recruiting Plk1 to kinetochores and facilitating phosphorylation of important downstream targets.

Publication types

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

MeSH terms

  • Animals
  • Cattle
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Line
  • Chick Embryo
  • Dynactin Complex
  • Humans
  • Kinetochores / metabolism*
  • Mice
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism*
  • Microtubules / genetics
  • Microtubules / metabolism
  • Phosphorylation / physiology
  • Protein Structure, Tertiary
  • Protein Subunits / genetics
  • Protein Subunits / metabolism*
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Spindle Apparatus / genetics
  • Spindle Apparatus / metabolism

Substances

  • Cell Cycle Proteins
  • DCTN1 protein, human
  • Dctn1 protein, mouse
  • Dynactin Complex
  • Microtubule-Associated Proteins
  • Protein Subunits
  • Proto-Oncogene Proteins
  • Protein-Serine-Threonine Kinases
  • polo-like kinase 1