Active liquid crystals powered by force-sensing DNA-motor clusters

TL;DR

This paper introduces programmable DNA-linked kinesin motor clusters that generate active stresses in liquid crystal systems, revealing how molecular mechanics influence macroscale active nematic behaviors.

Contribution

It demonstrates the design of force-sensing, DNA-based motor clusters that control active nematic dynamics through molecular load regulation.

Findings

DNA linker properties enable force sensing in motor clusters

Clusters exhibit local nematic order similar to microtubules

Load-dependent cluster disassembly modulates active stresses

Abstract

Cytoskeletal active nematics exhibit striking non-equilibrium dynamics that are powered by energy-consuming molecular motors. To gain insight into the structure and mechanics of these materials, we design programmable clusters in which kinesin motors are linked by a double-stranded DNA linker. The efficiency by which DNA-based clusters power active nematics depends on both the stepping dynamics of the kinesin motors and the chemical structure of the polymeric linker. Fluorescence anisotropy measurements reveal that the motor clusters, like filamentous microtubules, exhibit local nematic order. The properties of the DNA linker enable the design of force-sensing clusters. When the load across the linker exceeds a critical threshold the clusters fall apart, ceasing to generate active stresses and slowing the system dynamics. Fluorescence readout reveals the fraction of bound clusters that generate interfilament sliding. In turn, this yields the average load experienced by the kinesin motors as they step along the microtubules. DNA-motor clusters provide a foundation for understanding the molecular mechanism by which nanoscale molecular motors collectively generate mesoscopic active stresses, which in turn power macroscale non-equilibrium dynamics of active nematics.