Diffusible Crosslinkers Generate Directed Forces in Microtubule Networks
Diffusible Crosslinkers Generate Directed Forces in Microtubule Networks
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DOI：
10.1016/j.cell.2015.01.051
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发表时间：
2015-03-12
期刊：
影响因子：
64.5
通讯作者：
Diez, Stefan
中科院分区：
文献类型：
--
作者：
Lansky, Zdenek;Braun, Marcus;Diez, Stefan
细胞骨架重塑是真核细胞分裂和形态发生的关键。驱动重组的机械力归因于分子马达的作用和细胞骨架细丝的动力学，它们都消耗化学能。相比之下，非酶促长丝交联剂被认为仅仅是产生摩擦的实体。在这里，我们实验证明，扩散微管交联剂的Ase 1/PRC 1/Map 65家庭产生定向微管滑动时，限制在部分重叠的微管之间。Ase 1产生的力，直接测量的光镊在微微牛顿范围内，足以拮抗马达蛋白驱动的微管滑动。力的产生是定量解释的熵膨胀的限制Ase 1分子扩散内的微管重叠。因此，交联剂的热运动被利用来产生类似于压缩气体推动气缸中的活塞的机械功。由于可扩散蛋白质的限制在细胞中是普遍存在的，因此相关的熵力对于细胞骨架网络之外的细胞力学可能是重要的。
Cytoskeletal remodeling is essential to eukaryotic cell division and morphogenesis. The mechanical forces driving the restructuring are attributed to the action of molecular motors and the dynamics of cytoskeletal filaments, which both consume chemical energy. By contrast, non-enzymatic filament cross-linkers are regarded as mere friction-generating entities. Here, we experimentally demonstrate that diffusible microtubule crosslinkers of the Ase1/PRC1/Map65 family generate directed microtubule sliding when confined between partially overlapping microtubules. The Ase1-generated forces, directly measured by optical tweezers to be in the piconewton-range, were sufficient to antagonize motor-protein driven microtubule sliding. Force generation is quantitatively explained by the entropic expansion of confined Ase1 molecules diffusing within the microtubule overlaps. The thermal motion of crosslinkers is thus harnessed to generate mechanical work analogous to compressed gas propelling a piston in a cylinder. As confinement of diffusible proteins is ubiquitous in cells, the associated entropic forces are likely of importance for cellular mechanics beyond cytoskeletal networks.