Astrin-SKAP complex reconstitution reveals its kinetochore interaction with microtubule-bound Ndc80

Elife. 2017 Aug 25;6:e26866. doi: 10.7554/eLife.26866.

Abstract

Chromosome segregation requires robust interactions between the macromolecular kinetochore structure and dynamic microtubule polymers. A key outstanding question is how kinetochore-microtubule attachments are modulated to ensure that bi-oriented attachments are selectively stabilized and maintained. The Astrin-SKAP complex localizes preferentially to properly bi-oriented sister kinetochores, representing the final outer kinetochore component recruited prior to anaphase onset. Here, we reconstitute the 4-subunit Astrin-SKAP complex, including a novel MYCBP subunit. Our work demonstrates that the Astrin-SKAP complex contains separable kinetochore localization and microtubule binding domains. In addition, through cross-linking analysis in human cells and biochemical reconstitution, we show that the Astrin-SKAP complex binds synergistically to microtubules with the Ndc80 complex to form an integrated interface. We propose a model in which the Astrin-SKAP complex acts together with the Ndc80 complex to stabilize correctly formed kinetochore-microtubule interactions.

Keywords: biochemistry; cell biology; chromosome segregation; human; kinetochore; microtubule; mitosis.

MeSH terms

  • Binding Sites
  • Cell Cycle Proteins / metabolism*
  • Cell Line
  • Chromosome Segregation
  • Cytoskeletal Proteins
  • Humans
  • Kinetochores / metabolism*
  • Microtubule-Associated Proteins / metabolism*
  • Microtubules / metabolism*
  • Models, Biological
  • Nuclear Proteins / metabolism*
  • Protein Binding

Substances

  • Cell Cycle Proteins
  • Cytoskeletal Proteins
  • KNSTRN protein, human
  • Microtubule-Associated Proteins
  • NDC80 protein, human
  • Nuclear Proteins
  • SPAG5 protein, human