title: Coordination of opposite-polarity microtubule motors.
abstract: Many cargoes move bidirectionally, frequently reversing course between plus- and minus-end microtubule travel. For such cargoes, the extent and importance of interactions between the opposite-polarity motors is unknown. In this paper we test whether opposite-polarity motors on lipid droplets in Drosophila embryos are coordinated and avoid interfering with each other's activity, or whether they engage in a tug of war. To this end we impaired the minus-end transport machinery using dynein and dynactin mutations, and then investigated whether plus-end motion was improved or disrupted. We observe a surprisingly severe impairment of plus-end motion due to these alterations of minus-end motor activity. These observations are consistent with a coordination hypothesis, but cannot be easily explained with a tug of war model. Our measurements indicate that dynactin plays a crucial role in the coordination of plus- and minus-end-directed motors. Specifically, we propose that dynactin enables dynein to participate efficiently in bidirectional transport, increasing its ability to stay "on" during minus-end motion and keeping it "off" during plus-end motion.
authors.affiliation: Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Gross
authors.forename: Michael A
authors.initials: MA
authors.lastname: Welte
authors.forename: Steven M
authors.initials: SM
authors.lastname: Block
authors.forename: Eric F
authors.initials: EF
authors.lastname: Wieschaus
mesh_terms: D000818:Animals; D004331:Drosophila melanogaster / Q000196:embryology; D000072159:Dynactin Complex; D004398:Dyneins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D008297:Male; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*
chemical_list: D000072159:Dynactin Complex; D008869:Microtubule-Associated Proteins; D004398:Dyneins