PDF(Pubmed)
Abstract：
In cells, mRNAs are transported to and positioned at subcellular areas to locally regulate protein production. Recent studies have identified the kinesin-3 family member motor protein KIF1C as an RNA transporter. However, it is not clear how KIF1C interacts with RNA molecules. Here, we show that the KIF1C C-terminal tail domain contains an intrinsically disordered region (IDR) that drives liquid-liquid phase separation (LLPS). KIF1C forms dynamic puncta in cells that display physical properties of liquid condensates and incorporate RNA molecules in a sequence-selective manner. Endogenous KIF1C forms condensates in cellular protrusions, where mRNAs are enriched in an IDR-dependent manner. Purified KIF1C tail constructs undergo LLPS in vitro at near-endogenous nM concentrations and in the absence of crowding agents and can directly recruit RNA molecules. Overall, our work uncovers an intrinsic correlation between the LLPS activity of KIF1C and its role in mRNA positioning. In addition, the LLPS activity of KIF1C\'s tail represents a new mode of motor-cargo interaction that extends our current understanding of cytoskeletal motor proteins.
摘要：
在细胞中，mRNA被转运并定位在亚细胞区域以局部调节蛋白质产生。最近的研究已经确定驱动蛋白-3家族成员运动蛋白KIF1C为RNA转运蛋白。然而,目前尚不清楚KIF1C如何与RNA分子相互作用。这里,我们表明KIF1CC末端尾部结构域包含驱动液-液相分离（LLPS）的固有无序区域（IDR）。KIF1C在细胞中形成动态点，显示液体缩合物的物理性质，并以序列选择性方式掺入RNA分子。内源性KIF1C在细胞突起中形成凝聚物，其中mRNA以IDR依赖性方式富集。纯化的KIF1C尾部构建体在接近内源性nM浓度且不存在拥挤剂的情况下在体外经历LLPS,并且可以直接募集RNA分子。总的来说,我们的工作揭示了KIF1C的LLPS活性与其在mRNA定位中的作用之间的内在相关性。此外,KIF1C尾部的LLPS活性代表了一种新的运动-货物相互作用模式，扩展了我们目前对细胞骨架运动蛋白的理解。
