Mechanical coupling of microtubule-dependent motor teams during peroxisome transport in Drosophila S2 cells

Abstract

Background: Intracellular transport requires molecular motors that step along<br />cytoskeletal filaments actively dragging cargoes through the crowded cytoplasm. Here,<br />we explore the interplay of the opposed polarity motors kinesin-1 and cytoplasmic<br />dynein during peroxisome transport along microtubules in Drosophila S2 cells.<br />Methods: We used single particle tracking with nanometer accuracy and millisecond<br />time resolution to extract quantitative information on the bidirectional motion of<br />organelles. The transport performance was studied in cells expressing a slow chimeric<br />plus-end directed motor or the kinesin heavy chain. We also analyzed the influence of<br />peroxisomes membrane fluidity in methyl--ciclodextrin treated cells. The experimental<br />data was also confronted with numerical simulations of two well-established tug of war<br />scenarios.<br />SC<br />Results and conclusions: The velocity distributions of retrograde and anterograde<br />peroxisomes showed a multimodal pattern suggesting that multiple motor teams drive<br />transport in either direction. The chimeric motors interfered with the performance of<br />anterograde transport and also reduced the speed of the slowest retrograde team. In<br />addition, increasing the fluidity of peroxisomes membrane decreased the speed of the<br />slowest anterograde and retrograde teams.<br />General Significance: Our results support the existence of a crosstalk between<br />opposed-polarity motor teams. Moreover, the slowest teams seem to mechanically<br />communicate with each other through the membrane to trigger transport.