Physical and technical parameters determining thefunctioning of a kinesin-based cell-free motorsystem

Abstract

Kinesin is a microtubule-associated protein,converting chemical into mechanical energy. Based on itsability to also work outside cells, it has recently been shownthat this biological machinery might be usable fornanotechnological developments. Possible applications of thekinesin-based motor system require the solution of numerousmethodological and technical problems, including theorientation of force generation into a desired direction and thedetermination of the tolerable roughness of the surfaces used,the minimal free vertical space still enabling force-generatingactivity, and the temporal stability of the system. This paperreports on the example of microtubules gliding acrosskinesin-coated surfaces and shows that the force-generatingsystem needs a minimal free working space of about 100 nm heightand works up to 3 h with nearly constant velocity. Individualmicrotubules were observed to cover distances of at least 1 mmwithout being detached from the surface and to overcome steps ofup to 286 nm height. In addition, mechanically induced flowfields were shown to force gliding microtubules to move in oneand the same direction. This result is regarded as being anessential step towards future developments of kinesin-basedmicrodevices as this approach avoids neutralization of singleforces acting in opposite directions.