Transient binding of dynein controls bidirectional long-range motility of early endosomes
Transient binding of dynein controls bidirectional long-range motility of early endosomes
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DOI：
10.1073/pnas.1015839108
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发表时间：
2011-02
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影响因子：
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通讯作者：
M. Schuster;R. Lipowsky;Marcus-Alexander Assmann;P. Lenz;G. Steinberg
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作者：
M. Schuster;R. Lipowsky;Marcus-Alexander Assmann;P. Lenz;G. Steinberg
在许多细胞类型中，双向长程内体转运由相反的马达蛋白动力蛋白和驱动蛋白-3介导。在这里，我们使用一个真菌模型系统，以调查如何在早期内体（EE）运动的两个电机合作。以前有报道，Kin 3，驱动蛋白-3家族的成员，和细胞质动力蛋白介导的双向运动的EEs在真菌玉米黑粉菌。我们将绿色荧光蛋白融合到内源性动力蛋白重链和kin 3基因上，并在活细胞中观察到马达及其货物。而驱动蛋白-3被发现在顺行和逆行EE，动力蛋白电机本地化只逆行细胞器。活细胞成像显示，逆行运动的动力蛋白与顺行运动的内体的结合改变了细胞器的运输方向。当动力蛋白离开EE时，细胞器切换回基于驱动蛋白-3的顺行运动。定量光漂白和比较与核孔作为内部校准标准表明，单一的动力蛋白电机和四到五个驱动蛋白-3电机绑定的细胞器。这些数据表明，动力蛋白控制驱动蛋白-3活性的EE，从而决定了长距离的运动行为的细胞器。
In many cell types, bidirectional long-range endosome transport is mediated by the opposing motor proteins dynein and kinesin-3. Here we use a fungal model system to investigate how both motors cooperate in early endosome (EE) motility. It was previously reported that Kin3, a member of the kinesin-3 family, and cytoplasmic dynein mediate bidirectional motility of EEs in the fungus Ustilago maydis. We fused the green fluorescent protein to the endogenous dynein heavy chain and the kin3 gene and visualized both motors and their cargo in the living cells. Whereas kinesin-3 was found on anterograde and retrograde EEs, dynein motors localize only to retrograde organelles. Live cell imaging shows that binding of retrograde moving dynein to anterograde moving endosomes changes the transport direction of the organelles. When dynein is leaving the EEs, the organelles switch back to anterograde kinesin-3–based motility. Quantitative photobleaching and comparison with nuclear pores as an internal calibration standard show that single dynein motors and four to five kinesin-3 motors bind to the organelles. These data suggest that dynein controls kinesin-3 activity on the EEs and thereby determines the long-range motility behavior of the organelles.