Microtubule dynamics at low temperature: evidence that tubulin recycling limits assembly
Microtubule dynamics at low temperature: evidence that tubulin recycling limits assembly
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DOI：
10.1091/mbc.e19-11-0634
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发表时间：
2020-05-15
影响因子：
3.3
通讯作者：
Moore, Jeffrey K.
中科院分区：
文献类型：
--
作者：
Li, Gabriella;Moore, Jeffrey K.
温度如何具体影响微管动力学以及这些如何导致细胞中微管网络的变化尚未确定。我们在芽殖酵母中研究了这些问题，芽殖酵母是一种在不同环境中发现的生物，因此预测在很宽的温度范围内表现出动态微管。我们测量了活细胞中GFP标记的微管的动力学，发现将温度从37摄氏度降低到10摄氏度降低了聚合和解聚的速率，减少了灾难前组装的聚合物数量，并降低了微管从成核位点出现的频率。降低到4 ℃导致几乎所有微管聚合物的快速损失。我们提供的证据表明，微管动力学的这些影响可以部分解释辅因子依赖的微管蛋白的构象动力学的变化。消融的微管结合辅因子（TBCs）进一步敏感的细胞和他们的微管低温，我们强调了一个特定的作用TBCB/Alf 1微管维护在低温下。最后，我们表明，通过使用β-微管蛋白中的点突变体来抑制微管蛋白的成熟周期，可以在低温下赋予超稳定的微管，并且可以在低温下维持微管聚合物对TBCB/Alf 1的需求。总之，这些结果揭示了微管蛋白循环中不受重视的步骤。
How temperature specifically affects microtubule dynamics and how these lead to changes in microtubule networks in cells have not been established. We investigated these questions in budding yeast, an organism found in diverse environments and therefore predicted to exhibit dynamic microtubules across a broad temperature range. We measured the dynamics of GFP-labeled microtubules in living cells and found that lowering temperature from 37 degrees C to 10 degrees C decreased the rates of both polymerization and depolymerization, decreased the amount of polymer assembled before catastrophes, and decreased the frequency of microtubule emergence from nucleation sites. Lowering to 4 degrees C caused rapid loss of almost all microtubule polymer. We provide evidence that these effects on microtubule dynamics may be explained in part by changes in the cofactor-dependent conformational dynamics of tubulin proteins. Ablation of tubulin-binding cofactors (TBCs) further sensitizes cells and their microtubules to low temperatures, and we highlight a specific role for TBCB/ Alf1 in microtubule maintenance at low temperatures. Finally, we show that inhibiting the maturation cycle of tubulin by using a point mutant in beta-tubulin confers hyperstable microtubules at low temperatures and rescues the requirement for TBCB/Alf1 in maintaining microtubule polymer at low temperatures. Together, these results reveal an unappreciated step in the tubulin cycle.