机械负荷下的驱动蛋白后台阶
Kinesin's backsteps under mechanical load
摘要：
驱动蛋白通过水解ATP向微管的正端移动。从酶的角度来看，与核苷酸化学反应耦合的机械运动机制通常可以使用单环循环反应很好地解释。然而，一些困难出现在解释驱动蛋白的backstepping在这个框架内，特别是当外力反对运动的驱动蛋白。我们回顾了证据，如ATP独立的失速力和后退的较慢周期时间，这些证据已经出现，以挑战驱动蛋白后退是由于ATP合成的想法，即，驱动蛋白的前向化学机制的逆向循环。补充传统的单回路化学力学与路线的ATP水解后退步骤和核苷酸的步骤，特别是在负载下，给出了一个更好的物理解释的实验数据backsteps。
英文摘要：
Kinesins move processively toward the plus end of microtubules by hydrolyzing ATP for each step. From an enzymatic perspective, the mechanism of mechanical motion coupled to the nucleotide chemistry is often well explained using a single-loop cyclic reaction. However, several difficulties arise in interpreting kinesin's backstepping within this framework, especially when external forces oppose the motion of kinesin. We review evidence, such as an ATP-independent stall force and a slower cycle time for backsteps, that has emerged to challenge the idea that kinesin backstepping is due to ATP synthesis, i.e., the reverse cycle of kinesin's forward-stepping chemomechanics. Supplementing the conventional single-loop chemomechanics with routes for ATP-hydrolyzing backward steps and nucleotide-free steps, especially under load, gives a better physical interpretation of the experimental data on backsteps.
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