Evaluation of Microtubules Binary Collisions using Nano-Patterned Kinesins

Abstract

Collective motion is a ubiquitous phenomenon manifested in a wide range of living systems ranging from bacterial swarming to animal flocking. The transition from a random distribution to an ordered state resulting in large scale patterns is a fascinating feature demonstrated in collective motion. The reconstituted biomolecular motor system of microtubules propelled by kinesin or dynein motor proteins has been envisioned as an ideal candidate to investigate underlies mechanism of collective motion in vitro. The earlier studies on microtubule/kinesin gliding assay suggest that the alignment of microtubules in binary collisions plays an indispensable factor in achieving collective motion. Therefore, in our ongoing research, we are studying the alignment interactions between microtubule filaments by controlling kinesin number and spacing using gold nanopillars fabricated on the SiO2. To assess the alignment interaction we studied the binary collision events of the microtubules and found colliding microtubules align with each other with high probability at low kinesin spacing. However, with the increase in kinesin spacing microtubules preferred to show overlapping in collisions. Additionally, we measured other parameters related to the binary collisions like the incoming collision angle (i.e., the angle between two approaching microtubules). We found that the distribution of microtubules incoming angle depends on kinesin spacing and arrangements. Our analysis show that at higher spacing microtubules prefer to collide orthogonally and resulted in overlapping events. We also investigated the effect of other parameters like microtubules flexural rigidity and found no significant effects on alignment interactions. Finally, we increased the concentration of microtubules and observed the emergence of bundles and stream patterns in collective motion depending on microtubule concentrations without any influence of depleting or binding agents. This study may provide new insights in understanding the collective motion in nature.