Kaul Neha, Soppina Virupakshi, Verhey Kristen J
Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan.
Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan.
Biophys J. 2014 Jun 17;106(12):2636-43. doi: 10.1016/j.bpj.2014.05.008.
Long-range transport in cells is achieved primarily through motor-based transport along a network of microtubule tracks. Targeted transport by kinesin motors can be correlated with posttranslational modifications (PTMs) of the tubulin subunits in specific microtubules. To directly examine the influence of specific PTMs on kinesin-1 motility, we generated tubulin subunits that were either enriched in or lacking acetylation of α-tubulin lysine 40 (K40) or detyrosination of the α-tubulin C-terminal tail. We show that K40 acetylation does not result in significant changes in kinesin-1's landing rate or motility parameters (velocity and run length) across experimental conditions. In contrast, detyrosination causes a moderate increase in kinesin-1's landing rate. The fact that the effects of detyrosination are dampened by prior K40 acetylation indicates that the combination of PTMs may be an important aspect of the functional output of microtubule heterogeneity. Importantly, our results indicate that the moderate influences that single PTMs have on kinesin-1 in vitro do not explain the strong correlation between specific PTMs and kinesin-1 transport in cells. Thus, additional mechanisms for regulating kinesin-1 transport in cells must be explored in future work.
细胞中的长距离运输主要是通过沿着微管轨道网络的基于马达蛋白的运输来实现的。驱动蛋白马达的靶向运输可能与特定微管中微管蛋白亚基的翻译后修饰（PTM）相关。为了直接研究特定PTM对驱动蛋白-1运动性的影响，我们生成了富含或缺乏α-微管蛋白赖氨酸40（K40）乙酰化或α-微管蛋白C末端尾巴去酪氨酸化的微管蛋白亚基。我们发现，在各种实验条件下，K40乙酰化不会导致驱动蛋白-1的着陆率或运动参数（速度和运行长度）发生显著变化。相比之下，去酪氨酸化会使驱动蛋白-1的着陆率适度增加。先前的K40乙酰化会减弱去酪氨酸化的影响，这一事实表明PTM的组合可能是微管异质性功能输出的一个重要方面。重要的是，我们的结果表明，单个PTM在体外对驱动蛋白-1的适度影响并不能解释特定PTM与细胞中驱动蛋白-1运输之间的强相关性。因此，未来的工作必须探索调节细胞中驱动蛋白-1运输的其他机制。
