RT Journal Article
SR Electronic
T1 Vesicles driven by dynein and kinesin exhibit directional reversals without external regulators
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2022.09.27.509758
DO 10.1101/2022.09.27.509758
A1 Ashwin I. D’Souza
A1 Rahul Grover
A1 Gina A. Monzon
A1 Ludger Santen
A1 Stefan Diez
YR 2022
UL http://biorxiv.org/content/early/2022/09/28/2022.09.27.509758.abstract
AB Intracellular transport along cytoskeletal filaments propelled by molecular motors ensures the targeted delivery of cargoes to their destinations. Such transport is rarely unidirectional but rather bidirectional, including intermittent pauses and directional reversals owing to the simultaneous presence of opposite-polarity motors. It has been unclear whether such a complex motility pattern results from the sole mechanical interplay between opposite-polarity motors or requires external regulators. Here, we addressed this outstanding question by reconstituting cargo motility along microtubules in vitro by attaching purified Dynein-Dynactin-BICD2 (DDB) and kinesin-3 (KIF16B) to large unilamellar vesicles. Strikingly, we found that this minimal system is sufficient to recapitulate runs, pauses and reversals similar to in vivo cargo motility. In our experiments, reversals were always preceded by vesicle pausing and the transport directionality could be tuned by the relative numbers of opposite-polarity motors on the vesicles. Unexpectedly, during all runs the vesicle velocity was not influenced by the presence of the opposing motors. To gain mechanistic insight into bidirectional transport, we developed a mathematical model which predicts that low numbers of engaged motors are critical to transition between runs and pauses. Taken together, our results suggest that motors diffusively anchored to membranous cargo transiently engage in a tug-of-war during pauses where stochastic motor attachment and detachment events can lead to directional reversals without the necessity of external regulators.Competing Interest StatementThe authors have declared no competing interest.