The microtubule polymerase Stu2 promotes oligomerization of the γ-TuSC for cytoplasmic microtubule nucleation
Abstract
Stu2/XMAP215/ZYG-9/Dis1/Alp14/Msps/ch-TOG family members nucleate microtubules together with γ-tubulin complexes. However, we know little about the interplay of these nucleation factors. Here, we show that the budding yeast Stu2 in complex with the γ-tubulin receptor Spc72 nucleates microtubules in vitro without the small γ-tubulin complex (γ-TuSC). Upon γ-TuSC addition, Stu2 facilitates Spc72-γ-TuSC interaction by binding to Spc72 and γ-TuSC. Stu2 together with Spc72-γ-TuSC increases microtubule nucleation depended on the TOG domains of Stu2. Importantly, these activities are also important for microtubule nucleation in vivo. Stu2 stabilizes Spc72-γ-TuSC at the minus end of cytoplasmic microtubules (cMTs) and an in vivo assay indicates that cMT nucleation requires the TOG domains of Stu2. Upon γ-tubulin depletion, we observed efficient cMT nucleation away from the SPB, which was dependent on Stu2. Thus, γ-TuSC restricts cMT assembly to the SPB while Stu2 nucleates cMTs together with γ-TuSC and stabilizes γ-TuSC at the cMT minus end.
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All data generated or analysed during this study are included in the manuscript and supporting files.
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Funding
Deutsche Forschungsgemeinschaft (Schi295/4-3)
- Judith Gunzelmann
- Tien-chen Lin
- Annett Neuner
- Ursula Jäkle
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2018, Gunzelmann et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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