| Popis: |
Dynein and kinesin motors mediate long-range intracellular transport, translocating towards microtubule minus and plus ends, respectively. Cargoes often undergo bidirectional transport by binding to both motors simultaneously. However, it is not known how motor activities are coordinated in such circumstances. InDrosophila, sequential activities of the dynein-dynactin-BicD-Egalitarian (DDBE) complex and of kinesin-1 deliveroskarmRNA from nurse cells to the oocyte, and within the oocyte to the posterior pole. Here, throughin vitroreconstitution, we show that Tm1-I/C, a Tropomyosin-1 isoform, links kinesin-1 in an inactive state to DDBE-associatedoskarmRNA. NMR spectroscopy, small-angle X-ray scattering and structural modeling indicate that Tm1-I/C suppresses kinesin-1 activity by stabilizing its autoinhibited conformation, thus preventing a tug-of-war between the opposite polarity motors until kinesin-1 is activated in the oocyte. Our work reveals a novel strategy ensuring sequential activity of microtubule motors. |
