Kinetochore function is controlled by a phospho-dependent coexpansion of inner and outer components

J Cell Biol. 2015 Sep 14;210(6):899-916. doi: 10.1083/jcb.201506020.


It is widely accepted that the kinetochore is built on CENP-A-marked centromeric chromatin in a hierarchical order from inner to outer kinetochore. Recruitment of many kinetochore proteins depends on microtubule attachment status, but it remains unclear how their assembly/disassembly is orchestrated. Applying 3D structured illumination microscopy to Xenopus laevis egg extracts, here we reveal that in the absence of microtubule attachment, proteins responsible for lateral attachment and spindle checkpoint signaling expand to form micrometer-scale fibrous structures over CENP-A-free chromatin, whereas a core module responsible for end-on attachment (CENP-A, CENP-T, and Ndc80) does not. Both outer kinetochore proteins (Bub1, BubR1, Mad1, and CENP-E) and the inner kinetochore component CENP-C are integral components of the expandable module, whose assembly depends on multiple mitotic kinases (Aurora B, Mps1, and Plx1) and is suppressed by protein phosphatase 1. We propose that phospho-dependent coexpansion of CENP-C and outer kinetochore proteins promotes checkpoint signal amplification and lateral attachment, whereas their selective disassembly enables the transition to end-on attachment.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Aurora Kinase B / metabolism
  • Cell Cycle Proteins / metabolism
  • Cell Line
  • Chromatin / metabolism*
  • Chromosomal Proteins, Non-Histone / metabolism*
  • Humans
  • Kinetics
  • Kinetochores / metabolism*
  • Microscopy / methods*
  • Microtubules / metabolism
  • Mitosis
  • Multiprotein Complexes
  • Phosphorylation
  • Protein Phosphatase 1 / metabolism*
  • Protein Serine-Threonine Kinases / metabolism*
  • Signal Transduction
  • Xenopus Proteins / metabolism*
  • Xenopus laevis


  • Cell Cycle Proteins
  • Chromatin
  • Chromosomal Proteins, Non-Histone
  • Multiprotein Complexes
  • Xenopus Proteins
  • centromere protein C
  • Aurora Kinase B
  • Plk1 protein, Xenopus
  • Protein Serine-Threonine Kinases
  • RPS27 protein, Xenopus
  • aurkb protein, Xenopus
  • Protein Phosphatase 1