Perfect anomalous transport of subdiffusive cargos by molecular motors in viscoelastic cytosol

TL;DR

This paper demonstrates how molecular motors can achieve perfect subdiffusive transport of cargos in viscoelastic cytosol through mechanochemical coupling, leading to efficient, synchronized, and fast anomalous transport with minimal ATP consumption.

Contribution

It reveals a natural emergence of a perfect subdiffusive ratchet regime driven by allosteric effects, enhancing understanding of anomalous transport mechanisms in cells.

Findings

Perfect subdiffusive ratchet regime due to allosteric effects

Synchronization of catalytic wheel rotations with motor steps

Efficient transport with minimal ATP consumption

Abstract

Multiple experiments show that various submicron particles such as magnetosomes, RNA messengers, viruses, and even much smaller nanoparticles such as globular proteins diffuse anomalously slow in viscoelastic cytosol of living cells. Hence, their sufficiently fast directional transport by molecular motors such as kinesins is crucial for the cell operation. It has been shown recently that the traditional flashing Brownian ratchet models of molecular motors are capable to describe both normal and anomalous transport of such subdiffusing cargos by molecular motors with a very high efficiency. This work elucidates further an important role of mechanochemical coupling in such an anomalous transport. It shows a natural emergence of a perfect subdiffusive ratchet regime due to allosteric effects, where the random rotations of a "catalytic wheel" at the heart of the motor operation become perfectly synchronized with the random stepping of a heavily loaded motor, so that only one ATP molecule is consumed at each motor step along microtubule on average. However, the number of rotations made by the catalytic engine and the traveling distance both scale sublinearly in time. Nevertheless, this anomalous transport can be very fast in absolute terms.