Aurora B inhibits MCAK activity through a phosphoconformational switch that reduces microtubule association

Stephanie C. Ems-Mcclung, Sarah G. Hainline, Jenna Devare, Hailing Zong, Shang Cai, Stephanie K. Carnes, Sidney L. Shaw, Claire E. Walczak

Research output: Contribution to journalArticle

37 Scopus citations

Abstract

Background Proper spindle assembly and chromosome segregation rely on precise microtubule dynamics, which are governed in part by the kinesin-13 MCAK. MCAK microtubule depolymerization activity is inhibited by Aurora B-dependent phosphorylation, but the mechanism of this inhibition is not understood. Results Here, we develop the first Förster resonance energy transfer (FRET)-based biosensor for MCAK and show that MCAK in solution exists in a closed conformation mediated by an interaction between the C-terminal domain (CT) and the neck. Using fluorescence lifetime imaging (FLIM) we show that MCAK bound to microtubule ends is closed relative to MCAK associated with the microtubule lattice. Aurora B phosphorylation at S196 in the neck opens MCAK conformation and diminishes the interaction between the CT and the neck. Using FLIM and TIRF imaging, we find that changes in MCAK conformation are associated with a decrease in MCAK affinity for the microtubule. Conclusions Unlike motile kinesins, which are open when doing work, the high-affinity binding state for microtubule-depolymerizing kinesins is in a closed conformation. Phosphorylation switches MCAK conformation, which inhibits its ability to interact with microtubules and reduces its microtubule depolymerization activity. This work shows that the conformational model proposed for regulating kinesin activity is not universal and that microtubule-depolymerizing kinesins utilize a distinct conformational mode to regulate affinity for the microtubule, thus controlling their catalytic efficiency. Furthermore, our work provides a mechanism by which the robust microtubule depolymerization activity of kinesin-13s can be rapidly modulated to control cellular microtubule dynamics.

Original languageEnglish (US)
Pages (from-to)2491-2499
Number of pages9
JournalCurrent Biology
Volume23
Issue number24
DOIs
StatePublished - Dec 16 2013

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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    Ems-Mcclung, S. C., Hainline, S. G., Devare, J., Zong, H., Cai, S., Carnes, S. K., Shaw, S. L., & Walczak, C. E. (2013). Aurora B inhibits MCAK activity through a phosphoconformational switch that reduces microtubule association. Current Biology, 23(24), 2491-2499. https://doi.org/10.1016/j.cub.2013.10.054