Biomolecular motor-driven microtubule translocation in the presence of shear flow: analysis of redirection behaviours

Abstract

We suggest a concept for powering microfluidic devices with biomolecular motors and microtubules to meet the demands for highly efficient microfluidic devices. However, to successfully implement such devices, we require methods for active control over the direction of microtubule translocation. While most previous work has employed largely microfabricated passive mechanical patterns designed to guide the direction of microtubules, in this paper we demonstrate that hydrodynamic shear flow can be used to align microtubules translocating on a kinesin-coated surface in a direction parallel to the fluid flow. Our evidence supports the hypothesis that the mechanism of microtubule redirection is simply that drag force induced by viscous shear bends the leading end of a microtubule, which may be cantilevered beyond its kinesin supports. This cantilevered end deflects towards the flow direction, until it is subsequently bound to additional kinesins; as translocation continues, the process repeats until the microtubule is largely aligned with the flow, to a limit determined by random fluctuations created by thermal energy. We present statistics on the rate of microtubule alignment versus various strengths of shear flow as well as concentrations of kinesin, and also investigate the effects of shear flow on the motility.

Formation of motile assembly of microtubules driven by kinesins

“…Actin-myosin or MT-kinesin (or dynein), which are well-known linear motor systems, has been proposed as the building blocks of ATP-fueled biomachines [ref. 7,[11][12][13][14][15][16][17][18].…”

Simultaneous and bidirectional transport of kinesin‐coated microspheres and dynein‐coated microspheres on polarity‐oriented microtubules

“…Kinesin molecules are selectively absorbed on a substrate to confine microtubule motility in a certain area, or microtubules are guided by microfabricated tracks. Other active control methods also have been proposed such as electrical fields (Kim et al, 2007b) and hydrodynamic flow (Kim et al, 2007a;Prots et al, 2003;Stracke et al, 2000), in which electrophoretic and viscous drag forces, respectively, are applied to gliding microtubules. These forces work as bias in the gliding assay to rectify microtubules in a designated direction.…”

Engineering Applications of Biomolecular Motors

“…The path chosen by a molecular shuttle depends on its internal mechanics and can be constrained by tracks (55)(56)(57)(58) or controlled by external forces (59)(60)(61)(62). Thermal fluctuations of the advancing tip of the cytoskeletal filament cause the deviations from a straight path, and, as a result, the trajectory can be described by a persistence length (63,64).…”