Fluctuation in the Sliding Movement of Kinesin-Driven Microtubules Is Regulated Using the Deep-Sea Osmolyte Trimethylamine N-Oxide.

Nowadays, biomolecular motor-based miniaturized lab-on-a-chip devices have been attracting much attention for their wide range of nanotechnological applications. Most of the applications are dependent on the motor-driven active transportation of their associated filamentous proteins as shuttles. Fluctuation in the movement of the shuttles is a major contributor to the dispersion in motor-driven active transportation, which limits the efficiency of the miniaturized devices. In this work, by employing the biomolecular motor kinesin and its associated protein filament microtubule as a model active transport system, we demonstrate that the deep-sea osmolyte trimethylamine N-oxide (TMAO) is useful in regulating the fluctuation in the motility of microtubule shuttles. We show that the motional diffusion coefficient, a measure of the fluctuation in the movement of the kinesin-propelled microtubules, gradually decreases upon increasing the concentration of TMAO in the transportation system. We have been able to reduce the motional diffusion coefficient of microtubules more than 200 times by employing TMAO at a concentration of 2 M. We also show that upon elimination of TMAO, the motional diffusion coefficient of microtubules can be restored, which confirms that TMAO can be used as a tool to reversibly regulate the fluctuation in the sliding movement of kinesin-propelled microtubule shuttles. Such reversible regulation of the dynamic behavior of the shuttles does not require sacrificing the concentration of fuel used for transportation. Our results confirm the ability to manipulate the nanoscale motion of biomolecular motor-driven active transporters in an artificial environment. This work is expected to further enhance the tunability of biomolecular motor functions, which, in turn, will foster their nanotechnological applications based on active transportation.

Controlling the Rigidity of Kinesin-Propelled Microtubules in an In Vitro Gliding Assay Using the Deep-Sea Osmolyte Trimethylamine N-Oxide.

The biomolecular motor protein kinesin and its associated filamentous protein microtubule have been finding important nanotechnological applications in the recent years. Rigidity of the microtubules, which are propelled by kinesin motors in an in vitro gliding assay, is an important metric that determines the success of utilization of microtubules and kinesins in various applications, such as transportation, sensing, sorting, molecular robotics, etc. Therefore, regulating the rigidity of kinesin-propelled microtubules has been critical. In this work, we report a simple strategy to regulate the rigidity of kinesin-propelled microtubules in an in vitro gliding assay. We demonstrate that rigidity of the microtubules, propelled by kinesins in an in vitro gliding assay, can be modulated simply by using the natural osmolyte trimethylamine N-oxide (TMAO). By varying the concentration of TMAO in the gliding assay, the rigidity of microtubules can be modulated over a wide range. Based on this strategy, we are able to reduce the persistence length of microtubules, a measure of microtubule rigidity, ∼8 fold by using TMAO at the concentration of 1.5 M. Furthermore, we found that the decreased rigidity of the kinesin-propelled microtubules can be restored upon elimination of TMAO from the in vitro gliding assay. Alteration in the rigidity of microtubules is accounted for by the non-uniformity of the force applied by kinesins along the microtubules in the presence of TMAO. This work offers a facile strategy to reversibly regulate the rigidity of kinesin-propelled microtubules in situ, which would widen the applications of the biomolecular motor kinesin and its associated protein microtubule in various fields.

Controlling the kinetics of interaction between microtubules and kinesins over a wide temperature range using the deep-sea osmolyte trimethylamine N-oxide.

Trimethylamine N-oxide is found to be effective in regulating the interaction between microtubules and kinesins over a wide temperature range. The lifetime of the motility of microtubules on kinesins at high temperatures is prolonged using trimethylamine N-oxide. The activation energy of microtubule motility is increased by trimethylamine N-oxide. Prolonged operation at high temperatures decreased the activation energy of MT motility despite the increase in concentration of trimethylamine N-oxide.