Microtubule stability is known to be governed by a stabilizing GTP/GDP-Pi cap, but the exact relation between growth velocity, GTP hydrolysis, and catastrophes remains unclear. We investigate the dynamics of the stabilizing cap through in vitro reconstitution of microtubule dynamics in contact with microfabricated barriers, using the plus-end binding protein GFP-EB3 as a marker for the nucleotide state of the tip. The interaction of growing microtubules with steric objects is known to slow down microtubule growth and accelerate catastrophes. We show that the lifetime distributions of stalled microtubules, as well as the corresponding lifetime distributions of freely growing microtubules, can be fully described with a simple phenomenological 1D model based on noisy microtubule growth and a single EB3-dependent hydrolysis rate. This same model is furthermore capable of explaining both the previously reported mild catastrophe dependence on microtubule growth rates and the catastrophe statistics during tubulin washout experiments.

中文翻译：

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EB3 告知的生长停滞期间微管稳定帽的动力学


已知微管稳定性由稳定的 GTP/GDP-Pi 帽控制，但生长速度、GTP 水解和灾难之间的确切关系仍不清楚。我们使用加端结合蛋白 GFP-EB3 作为尖端核苷酸状态的标志物，通过在体外重建与微加工屏障接触的微管动力学来研究稳定帽的动力学。众所周知，生长中的微管与空间物体的相互作用会减慢微管的生长并加速灾难。我们表明，停滞微管的寿命分布，以及自由生长的微管的相应寿命分布，可以用基于噪声微管生长和单个 EB3 依赖性水解速率的简单现象学一维模型来完全描述。同样的模型还能够解释先前报道的对微管生长速率的轻度灾难依赖性和微管蛋白清除实验期间的灾难统计数据。