Kinesin-8 Motors Act Cooperatively to Mediate Length-Dependent Microtubule Depolymerization
Kinesin-8 Motors Act Cooperatively to Mediate Length-Dependent Microtubule Depolymerization
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DOI：
10.1016/j.cell.2009.07.032
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发表时间：
2009-09-18
期刊：
影响因子：
64.5
通讯作者：
Howard, Jonathon
中科院分区：
文献类型：
--
作者：
Varga, Vladimir;Leduc, Cecile;Howard, Jonathon
驱动蛋白-8家族中的马达蛋白以长度依赖性的方式使微管变性，这可能对于控制细胞器例如有丝分裂纺锤体的长度至关重要。我们使用单分子显微镜来了解芽殖酵母驱动蛋白-8，Kip 3 p的长度依赖性解聚机制。我们发现，在微管上的一个随机位置结合并走到正端后，单个Kip 3 p分子在那里停留，直到进入的Kip 3 p分子将其撞掉。Kip 3 p解离伴随着仅去除一个或两个微管蛋白二聚体（平均）。这种合作机制导致解聚速率与马达到微管末端的通量成比例，并解释解聚的长度依赖性。长度和分解之间的这种类型的反馈可以作为理解分子系综如何测量和控制聚合物长度的模型。
Motor proteins in the kinesin-8 family depolymerize microtubules in a length-dependent manner that may be crucial for controlling the length of organelles such as the mitotic spindle. We used single-molecule microscopy to understand the mechanism of length-dependent depolymerization by the budding yeast kinesin-8, Kip3p. We found that after binding at a random position on a microtubule and walking to the plus end, an individual Kip3p molecule pauses there until an incoming Kip3p molecule bumps it off. Kip3p dissociation is accompanied by removal of just one or two tubulin dimers (on average). Such a cooperative mechanism leads to a depolymerization rate that is proportional to the flux of motors to the microtubule end and accounts for the length dependence of depolymerization. This type of feedback between length and disassembly may serve as a model for understanding how an ensemble of molecules can measure and control polymer length.