Motor protein-driven unidirectional transport of micrometer-sized cargoes across isopolar microtubule arrays

Abstract

Conventional kinesin is a motor protein which translocates organelles from cell centre to cell periphery along specialized filamentous tracks, called microtubules. The direction of translocation is determined by microtubule polarity. This process of biological force generation can be simulated outside cells with kinesin-coated particles actively moving along immobilized microtubules. The in vitro approaches of kinesin-mediated transport described so far had the disadvantage that concerning their polarity the microtubules were randomly distributed resulting in random transport direction. The present paper demonstrates the unidirectional translocation of kinesin-coated cargoes across arrays of microtubules aligned not only in a geometrically parallel but also in an isopolar fashion. As cargo, glass, gold, and polystyrene beads with diameters between 1 and 10 µm were used. Independent of material and size, these beads were observed to move unidirectionally with average velocities of 0.3-1.0 µm s-1 over distances up to 2.2 mm. Moreover, the isopolar microtubule arrays even enabled the transport of large flat glass particles with an area of up to 24 µm×12 µm and 2-5 µm thickness which obviously contacted more than one microtubule. The controlling transport direction is considered to be an essential step for future developments of motor protein-based microdevices working in nanometre steps.

Viscoelasticity in Biological Systems: A Special Focus on Microbes

“…The subunit forms the end of the microtubule localized to the centrosome, close to the center of the cell, and the microtubule grows out to peripheral regions of the cell ending with a tubulin. The alternating and tubulins render the microtubule polar and its orientation guides the unidirectional movement of microtubule motor proteins from the kinesin and dynein families [72,73]. Microtubule aggregation is dependent on temperature and the relative amount of tubulin-GTP dimers [74].…”

Relationship between Size and Function of Natural Substance Particles

“…For example, ferromagnetic nanoparticles have Intrinsic peroxidase-like activity and can manufacture water and oxygen molecules from hydrogen peroxide [34]. More excitingly, some specialist deliberately designed NPs can manufacture various ChPs [35][36][37][38]. MPs, especially the life MPs, have much more potent functions to manufacture other particles-not only those smaller than themselves but also those much larger than themselves.…”

Active self-organization of microtubules in an inert chamber system

“…Currently, the in vitro motility assay is also used to determine the feasibility of constructing motor protein-based artificial biomachines, for which actin-myosin or MT-kinesin systems are considered promising building blocks. [8][9][10][11][12][13][14][15][16] New classes of devices including nanoscale molecular shuttles, 17,18 surface-imaging processes, 19 force measurements 20 and lab-on-a-chip devices 21 have been developed using knowledge obtained through the in vitro motility assay. To improve the organizational hierarchy of motor protein-based systems with emergent functions similar to those observed in natural systems, several active self-organization (AcSO) techniques have been developed.…”