Microtubule end conversion mediated by motors and diffusing proteins with no intrinsic microtubule end-binding activity

Nat Commun. 2019 Apr 11;10(1):1673. doi: 10.1038/s41467-019-09411-7.

Abstract

Accurate chromosome segregation relies on microtubule end conversion, the ill-understood ability of kinetochores to transit from lateral microtubule attachment to durable association with dynamic microtubule plus-ends. The molecular requirements for this conversion and the underlying biophysical mechanisms are elusive. We reconstituted end conversion in vitro using two kinetochore components: the plus end-directed kinesin CENP-E and microtubule-binding Ndc80 complex, combined on the surface of a microbead. The primary role of CENP-E is to ensure close proximity between Ndc80 complexes and the microtubule plus-end, whereas Ndc80 complexes provide lasting microtubule association by diffusing on the microtubule wall near its tip. Together, these proteins mediate robust plus-end coupling during several rounds of microtubule dynamics, in the absence of any specialized tip-binding or regulatory proteins. Using a Brownian dynamics model, we show that end conversion is an emergent property of multimolecular ensembles of microtubule wall-binding proteins with finely tuned force-dependent motility characteristics.

Publication types

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

MeSH terms

  • Animals
  • Chromosomal Proteins, Non-Histone / genetics
  • Chromosomal Proteins, Non-Histone / isolation & purification
  • Chromosomal Proteins, Non-Histone / metabolism
  • Chromosome Segregation*
  • Cytoskeletal Proteins
  • Kinesins / metabolism*
  • Kinetochores / metabolism*
  • Microscopy, Fluorescence
  • Microtubules / metabolism*
  • Models, Biological
  • Nonlinear Dynamics
  • Nuclear Proteins / genetics
  • Nuclear Proteins / isolation & purification
  • Nuclear Proteins / metabolism
  • Protein Binding
  • Recombinant Proteins / genetics
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Sf9 Cells
  • Single Molecule Imaging
  • Stochastic Processes
  • Xenopus Proteins / genetics
  • Xenopus Proteins / isolation & purification
  • Xenopus Proteins / metabolism

Substances

  • Chromosomal Proteins, Non-Histone
  • Cytoskeletal Proteins
  • NDC80 protein, human
  • Nuclear Proteins
  • Recombinant Proteins
  • Xenopus Proteins
  • centromere protein E
  • Kinesins