Alp7/TACC-Alp14/TOG generates long-lived, fast-growing MTs by an unconventional mechanism.
Alp7/TACC-Alp14/TOG generates long-lived, fast-growing MTs by an unconventional mechanism.
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DOI：
10.1038/srep20653
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发表时间：
2016-02-11
影响因子：
4.6
通讯作者：
Cross RA
中科院分区：
文献类型：
--
作者：
Hussmann F;Drummond DR;Peet DR;Martin DS;Cross RA
Alp 14是来自S. pombe跟踪加上结束和加速他们的成长。为了探究其机制，我们重组了动态不稳定的单一亚型S。粟酒裂殖酵母微管与全长Alp 14/TOG和Alp 7，TACC家族的Alp 14的结合伴侣。我们发现，Alp 14可以驱动微管加端生长在GTP-微管蛋白浓度至少10倍低于通常的临界浓度，在增加的灾难为代价。这表明Alp 14是一种非常不寻常的酶，它会使其催化的反应平衡发生偏差。Alp 7/TACC通过增加其占用率来增强Alp 14的有效性。与此一致，我们在活细胞中发现，Alp 7缺失产生与Alp 14缺失非常相似的MT动力学缺陷。Alp 7/14在微管正末端加速和偏置GTP-微管蛋白交换的能力允许其在非常低的细胞游离微管蛋白浓度下产生长寿命、快速生长的微管。
Alp14 is a TOG-family microtubule polymerase from S. pombe that tracks plus ends and accelerates their growth. To interrogate its mechanism, we reconstituted dynamically unstable single isoform S. pombe microtubules with full length Alp14/TOG and Alp7, the TACC-family binding partner of Alp14. We find that Alp14 can drive microtubule plus end growth at GTP-tubulin concentrations at least 10-fold below the usual critical concentration, at the expense of increased catastrophe. This reveals Alp14 to be a highly unusual enzyme that biases the equilibrium for the reaction that it catalyses. Alp7/TACC enhances the effectiveness of Alp14, by increasing its occupancy. Consistent with this, we show in live cells that Alp7 deletion produces very similar MT dynamics defects to Alp14 deletion. The ability of Alp7/14 to accelerate and bias GTP-tubulin exchange at microtubule plus ends allows it to generate long-lived, fast-growing microtubules at very low cellular free tubulin concentrations.