The microtubule polymerase Stu2 promotes oligomerization of the γ-TuSC for cytoplasmic microtubule nucleation.
The microtubule polymerase Stu2 promotes oligomerization of the γ-TuSC for cytoplasmic microtubule nucleation.
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DOI：
10.7554/elife.39932
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发表时间：
2018-09-17
期刊：
影响因子：
7.7
通讯作者：
Schiebel E
中科院分区：
文献类型：
--
作者：
Gunzelmann J;Rüthnick D;Lin TC;Zhang W;Neuner A;Jäkle U;Schiebel E
Stu2/XMAP215/ZYG - 9/Dis1/Alp14/Msps/ch - TOG家族成员与γ - 微管蛋白复合物相关，可使微管成核，但我们对这些成核因子之间的相互作用知之甚少。在此，我们表明，在体外，芽殖酵母的Stu2与γ - 微管蛋白受体Spc72形成的复合物在没有小γ - 微管蛋白复合物（γ - TuSC）的情况下可使微管成核。加入γ - TuSC后，Stu2通过与Spc72和γ - TuSC结合促进Spc72 - γ - TuSC相互作用。Stu2与Spc72 - γ - TuSC一起在一个依赖于Stu2的TOG结构域的过程中增加微管成核。重要的是，这些活性对于体内微管成核也很重要。Stu2使Spc72 - γ - TuSC在细胞质微管（cMTs）的负端稳定，体内实验表明cMT成核需要Stu2的TOG结构域。在γ - 微管蛋白耗尽时，我们观察到在远离纺锤体极体（SPB）处有效的cMT成核，这依赖于Stu2。因此，γ - TuSC将cMT组装限制在SPB，而Stu2与γ - TuSC一起使cMT成核，并使γ - TuSC在cMT负端稳定。
Stu2/XMAP215/ZYG-9/Dis1/Alp14/Msps/ch-TOG family members in association with with γ-tubulin complexes nucleate microtubules, but 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 in a process that is dependent 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 spindle pole body (SPB), which was dependent on Stu2. Thus, γ-TuSC restricts cMT assembly to the SPB whereas Stu2 nucleates cMTs together with γ-TuSC and stabilizes γ-TuSC at the cMT minus end.