Donovan Kirk W, Bretscher Anthony
Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853.
Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853
J Cell Biol. 2015 May 11;209(3):359-65. doi: 10.1083/jcb.201411010. Epub 2015 May 4.
Cell organization requires regulated cargo transport along cytoskeletal elements. Myosin V motors are among the most conserved organelle motors and have been well characterized in both yeast and mammalian systems. Biochemical data for mammalian myosin V suggest that a head-to-tail autoinhibitory interaction is a primary means of regulation, but the in vivo significance of this interaction has not been studied. Here we generated and characterized mutations in the yeast myosin V Myo2p to reveal that it is regulated by a head-to-tail interaction and that loss of regulation renders the myosin V constitutively active. We show that an unregulated motor is very deleterious for growth, resulting in severe defects in Myo2-mediated transport processes, including secretory vesicle transport, mitochondrial inheritance, and nuclear orientation. All of the defects associated with motor misregulation could be rescued by artificially restoring regulation. Thus, spatial and temporal regulation of myosin V in vivo by a head-to-tail interaction is critical for the normal delivery functions of the motor.
细胞组织需要沿着细胞骨架元件进行有调控的货物运输。肌球蛋白V马达是最保守的细胞器马达之一，在酵母和哺乳动物系统中都有很好的特征描述。哺乳动物肌球蛋白V的生化数据表明，头对尾的自抑制相互作用是一种主要的调控方式，但这种相互作用在体内的意义尚未得到研究。在这里，我们在酵母肌球蛋白V Myo2p中产生并表征了突变，以揭示它受头对尾相互作用的调控，并且调控的丧失使肌球蛋白V组成型激活。我们表明，不受调控的马达对生长非常有害，导致Myo2介导的运输过程出现严重缺陷，包括分泌囊泡运输、线粒体遗传和核定位。所有与马达调控异常相关的缺陷都可以通过人工恢复调控来挽救。因此，肌球蛋白V在体内通过头对尾相互作用进行的空间和时间调控对于马达的正常运输功能至关重要。
