Max Planck Institute of Biochemistry, Department of Structural Cell Biology, Am Klopferspitz 18, D-82152, Martinsried, Germany.
University of Lausanne, Department of Fundamental Microbiology, CH-1015, Lausanne, Switzerland.
Nat Commun. 2018 Nov 8;9(1):4684. doi: 10.1038/s41467-018-07037-9.
The cilium is an organelle used for motility and cellular signaling. Intraflagellar transport (IFT) is a process to move ciliary building blocks and signaling components into the cilium. How IFT controls the movement of ciliary components is currently poorly understood. IFT172 is the largest IFT subunit essential for ciliogenesis. Due to its large size, the characterization of IFT172 has been challenging. Using giant unilamellar vesicles (GUVs), we show that IFT172 is a membrane-interacting protein with the ability to remodel large membranes into small vesicles. Purified IFT172 has an architecture of two globular domains with a long rod-like protrusion, resembling the domain organization of coatomer proteins such as COPI-II or clathrin. IFT172 adopts two different conformations that can be manipulated by lipids or detergents: 1) an extended elongated conformation and 2) a globular closed architecture. Interestingly, the association of IFT172 with membranes is mutually exclusive with IFT57, implicating multiple functions for IFT172 within IFT.
纤毛是一种用于运动和细胞信号传导的细胞器。内鞭毛运输（IFT）是将纤毛构建块和信号成分运送到纤毛中的过程。IFT 如何控制纤毛成分的运动目前还知之甚少。IFT172 是纤毛发生所必需的最大 IFT 亚基。由于其体积庞大，IFT172 的特性一直具有挑战性。使用巨大的单分子层囊泡（GUV），我们表明 IFT172 是一种与膜相互作用的蛋白质，具有将大膜重塑成小囊泡的能力。纯化的 IFT172 具有两个球形结构域和一个长杆状突起的结构，类似于 COPI-II 或网格蛋白等包被蛋白的结构域组织。IFT172 采用两种不同的构象，可以通过脂质或去污剂进行操作：1）伸展的伸长构象和 2）球形封闭结构。有趣的是，IFT172 与膜的结合与 IFT57 相互排斥，这意味着 IFT172 在 IFT 中具有多种功能。
