Department of Physics, Wake Forest University, PO Box 7507, Winston-Salem, NC 27109, USA.
Eur Biophys J. 2011 Sep;40(9):1071-9. doi: 10.1007/s00249-011-0724-1. Epub 2011 Jul 7.
Although the velocity of single kinesin motors against an opposing force F of 0-10 pN is well known, the behavior of multiple kinesin motors working to overcome a larger load is still poorly understood. We have carried out gliding assays in which 3-7 Drosophila kinesin-1 motors moved a microtubule at 200-700 μm/s against a 0-31 pN load at saturating [ATP]. The load F was generated by applying a spatially uniform magnetic field gradient to a superparamagnetic bead attached to the (+) end of the microtubule. When F was scaled by the average number of motors [Symbol: see text]n[Symbol: see text], the force-velocity relationship for multiple motors was similar to the force-velocity relationship for a single motor, supporting a minimal load-sharing model. The velocity distribution at low load has a single mode consistent with rapid fluctuations of n. However, against a load of 2.5-4.7 pN/motor, additional modes appeared at lower velocity. These observations support the Klumpp-Lipowsky model of multimotor transport [Proc Natl Acad Sci USA 102. 17284-17289 (2005)].
尽管单个肌球蛋白马达在 0-10 pN 的反向力 F 下的速度是众所周知的，但多个肌球蛋白马达克服更大负载的工作行为仍知之甚少。我们进行了滑行实验，在这些实验中，3-7 个果蝇肌球蛋白-1 马达以 200-700 μm/s 的速度在饱和 [ATP] 下推动微管，负载 F 通过对附着在 (+) 端的超顺磁珠施加空间均匀磁场梯度来产生微管。当 F 除以平均马达数 [Symbol: see text]n[Symbol: see text]时，多马达的力-速度关系类似于单个马达的力-速度关系，支持最小负载共享模型。在低负载下的速度分布具有与 n 的快速波动一致的单模态。然而，在负载为 2.5-4.7 pN/马达时，在较低速度下出现了其他模态。这些观察结果支持 Klumpp-Lipowsky 多马达运输模型 [Proc Natl Acad Sci USA 102. 17284-17289 (2005)]。
