Shao Qiang, Gao Yi Qin
Department of Chemistry, Texas A&M University, College Station, Texas 77845, USA.
Biochemistry. 2007 Aug 7;46(31):9098-106. doi: 10.1021/bi602382w. Epub 2007 Jul 14.
Several lines of experimental evidence suggest that the conventional kinesin 1 walks by an asymmetric hand-over-hand mechanism, although it is a homodimer. In the previous study, we examined several important force-dependent features of the hand-over-hand mechanism of kinesin. In this study, we focus on the asymmetry in the hand-over-hand mechanism. We show that the experimentally observed kinesin limping can be explained in our model by the variation of the neck linker lengths in the kinesin stepping (which has also been suggested earlier by others). We also study the experimentally observed processive motion of a mutant heterodimer of kinesin, in which only one of the two heads has the capability of ATP hydrolysis, as well as the walking of wild-type kinesin in the presence of both ATP and its analogue AMPPNP. We show that the possible processive walking of the heterodimeric kinesin can be explained by introducing a force-generating intermediate, the kinesin-ATP complex, which is different from the posthydrolytic species, kinesin-ADP/Pi.
几条实验证据表明，传统驱动蛋白1虽为同型二聚体，却以不对称的手拉手机制移动。在之前的研究中，我们研究了驱动蛋白手拉手机制的几个重要的力依赖性特征。在本研究中，我们关注手拉手机制中的不对称性。我们表明，实验观察到的驱动蛋白跛行现象在我们的模型中可以通过驱动蛋白步移时颈部连接体长度的变化来解释（其他人之前也提出过这一点）。我们还研究了实验观察到的驱动蛋白突变异源二聚体的持续运动，其中两个头部中只有一个具有ATP水解能力，以及野生型驱动蛋白在ATP及其类似物AMPPNP存在下的移动。我们表明，异源二聚体驱动蛋白可能的持续移动可以通过引入一种产生力的中间体——驱动蛋白 - ATP复合物来解释，该复合物不同于水解后产物驱动蛋白 - ADP/Pi。
