驱动蛋白-8马达蛋白Kip3p介导的微管解聚：一个数学模型
Microtubule depolymerization by the Kinesin-8 motor Kip3p: a mathematical model.
作者信息
Hough L E, Schwabe Anne, Glaser Matthew A, McIntosh J Richard, Betterton M D
机构信息
Physics Department, University of Colorado at Boulder, Boulder, Colorado, USA.
出版信息
Biophys J. 2009 Apr 22;96(8):3050-64. doi: 10.1016/j.bpj.2009.01.017.
Proteins from the kinesin-8 family promote microtubule (MT) depolymerization, a process thought to be important for the control of microtubule length in living cells. In addition to this MT shortening activity, kinesin 8s are motors that show plus-end directed motility on MTs. Here we describe a simple model that incorporates directional motion and destabilization of the MT plus-end by kinesin 8. Our model quantitatively reproduces the key features of length-versus-time traces for stabilized MTs in the presence of purified kinesin 8, including length-dependent depolymerization. Comparison of model predictions with experiments suggests that kinesin 8 depolymerizes processively, i.e., one motor can remove multiple tubulin dimers from a stabilized MT. Fluctuations in MT length as a function of time are related to depolymerization processivity. We have also determined the parameter regime in which the rate of MT depolymerization is length dependent: length-dependent depolymerization occurs only when MTs are sufficiently short; this crossover is sensitive to the bulk motor concentration.
驱动蛋白-8家族的蛋白质可促进微管（MT）解聚，这一过程被认为对活细胞中微管长度的控制至关重要。除了这种微管缩短活性外，驱动蛋白8还是能在微管上向正端移动的分子马达。在此，我们描述了一个简单模型，该模型纳入了驱动蛋白8对微管正端的定向运动和去稳定作用。我们的模型定量再现了在纯化的驱动蛋白8存在下稳定微管的长度与时间关系曲线的关键特征，包括长度依赖性解聚。模型预测与实验结果的比较表明，驱动蛋白8进行性地解聚，即一个分子马达可以从稳定的微管中去除多个微管蛋白二聚体。微管长度随时间的波动与解聚进行性有关。我们还确定了微管解聚速率与长度相关的参数范围：长度依赖性解聚仅在微管足够短时发生；这种转变对总体分子马达浓度敏感。
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