The cargo adaptor proteins RILPL2 and melanophilin co-regulate myosin-5a motor activity
The cargo adaptor proteins RILPL2 and melanophilin co-regulate myosin-5a motor activity
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货物接头蛋白 RILPL2 和亲黑素共同调节肌球蛋白 5a 运动活性
DOI：
10.1074/jbc.ra119.007384
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发表时间：
2019-07-19
影响因子：
4.8
通讯作者：
Li, Xiang-dong
中科院分区：
文献类型：
--
作者：
Cao, Qing-Juan;Zhang, Ning;Li, Xiang-dong
脊椎动物肌球蛋白-5a是一种与肌动蛋白网络相关的ATP加工马达，负责多种囊泡货物的运输和定位。为了有效地运输货物并防止无效的ATP水解，必须严格调节肌球蛋白-5a运动功能。肌球蛋白-5a的球状尾结构域（GTD）不仅作为抑制结构域起作用，而且还作为许多货物衔接蛋白的结合位点，包括亲黑素（Mlph）和Rab相互作用溶酶体蛋白样2（RILPL 2）。在这项研究中，使用各种生物化学方法，包括ATP酶，单分子运动，GST下拉测定，和分析ultracentrapgation，我们证明，结合Mlph和RILPL 2的GTD的肌球蛋白-5a的肌球蛋白-5a运动功能的激活所需的生理离子条件下。我们还发现，这种激活是由小的GTTRab 36，RILPL 2的结合伴侣调节。总之，我们的研究结果表明，RILPL 2是所需的Mlph介导的激活Myo 5a运动活性在生理条件下，Rab 36促进这种激活。我们建议Rab 36刺激RILPL 2与肌球蛋白-5a GTD相互作用;这种相互作用然后诱导暴露GTD中的Mlph结合位点，使Mlph与GTD相互作用并激活肌球蛋白-5a运动活性。
Vertebrate myosin-5a is an ATP-utilizing processive motor associated with the actin network and responsible for the transport and localization of several vesicle cargoes. To transport cargo efficiently and prevent futile ATP hydrolysis, myosin-5a motor function must be tightly regulated. The globular tail domain (GTD) of myosin-5a not only functions as the inhibitory domain but also serves as the binding site for a number of cargo adaptor proteins, including melanophilin (Mlph) and Rab-interacting lysosomal protein–like 2 (RILPL2). In this study, using various biochemical approaches, including ATPase, single-molecule motility, GST pulldown assays, and analytical ultracentrifugation, we demonstrate that the binding of both Mlph and RILPL2 to the GTD of myosin-5a is required for the activation of myosin-5a motor function under physiological ionic conditions. We also found that this activation is regulated by the small GTPase Rab36, a binding partner of RILPL2. In summary, our results indicate that RILPL2 is required for Mlph-mediated activation of Myo5a motor activity under physiological conditions and that Rab36 promotes this activation. We propose that Rab36 stimulates RILPL2 to interact with the myosin-5a GTD; this interaction then induces exposure of the Mlph-binding site in the GTD, enabling Mlph to interact with the GTD and activate myosin-5a motor activity.