Tug-of-war as a cooperative mechanism for bidirectional cargo transport by molecular motors

TL;DR

This paper models bidirectional intracellular cargo transport as a cooperative tug-of-war between molecular motors, revealing multiple motility regimes and high sensitivity to parameter changes, which may regulate cellular traffic.

Contribution

It introduces a theoretical model of bidirectional transport based on load-dependent motor properties, showing complex cooperative behavior and multiple motility regimes.

Findings

Seven distinct motility regimes identified.

Transport highly sensitive to motor parameter variations.

Cooperative tug-of-war mechanism explains bidirectional movement.

Abstract

Intracellular transport is based on molecular motors that pull cargos along cytoskeletal filaments. One motor species always moves in one direction, e.g. conventional kinesin moves to the microtubule plus end, while cytoplasmic dynein moves to the microtubule minus end. However, many cellular cargos are observed to move bidirectionally, involving both plus-end and minus-end directed motors. The presumably simplest mechanism for such bidirectional transport is provided by a tug-of-war between the two motor species. This mechanism is studied theoretically using the load-dependent transport properties of individual motors as measured in single-molecule experiments. In contrast to previous expectations, such a tug-of-war is found to be highly cooperative and to exhibit seven different motility regimes depending on the precise values of the single motor parameters. The sensitivity of the transport process to small parameter changes can be used by the cell to regulate its cargo traffic.