UNC/NCSU Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514, USA.
Department of Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
Phys Rev E. 2019 Aug;100(2-1):022408. doi: 10.1103/PhysRevE.100.022408.
Single kinesin molecular motors can processively move along a microtubule (MT) a few micrometers on average before dissociating. However, cellular length scales over which transport occurs are several hundred microns and more. Why seemingly unreliable motors are used to transport cellular cargo remains poorly understood. We propose a theory for how low processivity, the average length of a single bout of directed motion, can enhance cellular transport when motors and cargos must first diffusively self-assemble into complexes. We employ stochastic modeling to determine the effect of processivity on overall cargo transport flux. We show that, under a wide range of physiologically relevant conditions, possessing "infinite" processivity does not maximize flux along MTs. Rather, we find that lowering processivity, i.e., weaker binding of motors to MTs, can improve transport flux. These results shed light on the relationship between processivity and transport efficiency and offer a theory for the physiological benefits of low motor processivity.
单个肌球蛋白分子马达在解离前可以沿着微管（MT）平均移动几微米。然而，发生运输的细胞长度尺度为数百微米甚至更大。为什么看似不可靠的马达被用于运输细胞货物仍然知之甚少。我们提出了一种理论，即当马达和货物必须首先扩散自组装成复合物时，低进程性，即单个定向运动的平均长度，如何增强细胞运输。我们采用随机建模来确定进程性对整体货物运输通量的影响。我们表明，在广泛的生理相关条件下，具有“无限”进程性并不能使 MT 上的通量最大化。相反，我们发现降低进程性，即降低马达与 MT 的结合强度，可以提高运输通量。这些结果揭示了进程性和运输效率之间的关系，并为低马达进程性的生理益处提供了一种理论。
