The microtubule-based motor Kar3 and plus end-binding protein Bim1 provide structural support for the anaphase spindle

Melissa K. Gardner, Julian Haase, Karthikeyan Mythreye, Jeffrey N. Molk, MaryBeth Anderson, Ajit P. Joglekar, Eileen T. O'Toole, Mark Winey, E. D. Salmon, David J. Odde, Kerry Bloom

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Abstract

In budding yeast, the mitotic spindle is comprised of 32 kinetochore microtubules (kMTs) and ∼8 interpolar MTs (ipMTs). Upon anaphase onset, kMTs shorten to the pole, whereas ipMTs increase in length. Overlapping MTs are responsible for the maintenance of spindle integrity during anaphase. To dissect the requirements for anaphase spindle stability, we introduced a conditionally functional dicentric chromosome into yeast. When centromeres from the same sister chromatid attach to opposite poles, anaphase spindle elongation is delayed and a DNA breakage-fusion-bridge cycle ensues that is dependent on DNA repair proteins. We find that cell survival after dicentric chromosome activation requires the MT-binding proteins Kar3p, Bim1p, and Ase1p. In their absence, anaphase spindles are prone to collapse and buckle in the presence of a dicentric chromosome. Our analysis reveals the importance of Bim1p in maintaining a stable ipMT overlap zone by promoting polymerization of ipMTs during anaphase, whereas Kar3p contributes to spindle stability by cross-linking spindle MTs.

Original languageEnglish (US)
Pages (from-to)91-100
Number of pages10
JournalJournal of Cell Biology
Volume180
Issue number1
DOIs
StatePublished - Jan 14 2008
Externally publishedYes

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ASJC Scopus subject areas

  • Cell Biology

Cite this

Gardner, M. K., Haase, J., Mythreye, K., Molk, J. N., Anderson, M., Joglekar, A. P., O'Toole, E. T., Winey, M., Salmon, E. D., Odde, D. J., & Bloom, K. (2008). The microtubule-based motor Kar3 and plus end-binding protein Bim1 provide structural support for the anaphase spindle. Journal of Cell Biology, 180(1), 91-100. https://doi.org/10.1083/jcb.200710164