Cargo rigidity affects the sensitivity of dynein ensembles to individual motor pausing.

Abstract

Cytoplasmic dynein is a minus-end directed microtubule-based motor protein that drives intracellular cargo transport in eukaryotic cells. Although many intracellular cargos are propelled by small groups of dynein motors, the biophysical mechanisms governing ensemble motility remain largely unknown. To investigate the emergent motility of motor ensembles, we have designed a programmable DNA origami synthetic cargo "chassis" enabling us to control the number of dynein motors in the ensemble and vary the rigidity of the cargo chassis itself. Using total internal reflection fluorescence microscopy, we have observed dynein ensembles transporting these cargo chassis along microtubules in vitro. We find that ensemble motility depends on cargo rigidity: as the number of motors increases, ensembles transporting flexible cargos move comparatively faster than a single motor, whereas ensembles transporting rigid cargos move slower than a single motor. To explain this, we show that ensembles connected through flexible cargos are less sensitive to the pauses of individual motors within the ensemble. We conclude that cargo rigidity plays an important role in communicating and coordinating the states of motors, and consequently in the subsequent mechanisms of collective motility. The insensitivity of ensemble-driven cargos to the pausing of individual motors may contribute to the robustness and versatility of intracellular cargo transport. © 2016 Wiley Periodicals, Inc.