Hou Yuqing, Witman George B
Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655.
Division of Cell Biology and Imaging, Department of Radiology, University of Massachusetts Medical School, Worcester, MA 01655
Mol Biol Cell. 2017 Sep 1;28(18):2420-2433. doi: 10.1091/mbc.E17-03-0172. Epub 2017 Jul 12.
Cilia are assembled via intraflagellar transport (IFT). The IFT machinery is composed of motors and multisubunit particles, termed IFT-A and IFT-B, that carry cargo into the cilium. Knowledge of how the IFT subunits interact with their cargo is of critical importance for understanding how the unique ciliary domain is established. We previously reported a mutant, , that fails to express the IFT-B protein IFT46, has greatly reduced levels of other IFT-B proteins, and assembles only very short flagella. A spontaneous suppression of restored IFT-B levels and enabled growth of longer flagella, but the flagella lacked outer dynein arms. Here we show that the suppression is due to insertion of the transposon into the allele, causing the expression of a fusion protein including the IFT46 C-terminal 240 amino acids. The IFT46 C-terminus can assemble into and stabilize IFT-B but does not support transport of outer arm dynein into flagella. ODA16, a cargo adaptor specific for outer arm dynein, also fails to be imported into the flagella in the absence of the IFT46 N-terminus. We conclude that the IFT46 N-terminus, ODA16, and outer arm dynein interact for IFT of the latter.
纤毛通过鞭毛内运输（IFT）组装而成。IFT机制由马达和多亚基颗粒组成，分别称为IFT-A和IFT-B，它们将货物运入纤毛。了解IFT亚基如何与其货物相互作用对于理解独特的纤毛结构域如何形成至关重要。我们之前报道了一个突变体，它无法表达IFT-B蛋白IFT46，其他IFT-B蛋白水平大幅降低，并且只能组装非常短的鞭毛。该突变体的一个自发抑制恢复了IFT-B水平，并使更长鞭毛得以生长，但这些鞭毛缺乏外动力蛋白臂。在这里我们表明，这种抑制是由于转座子插入等位基因，导致一种包含IFT46 C端240个氨基酸的融合蛋白表达。IFT46的C端可以组装并稳定IFT-B，但不支持外臂动力蛋白运输到鞭毛中。ODA16是外臂动力蛋白的一种货物适配体，在没有IFT46 N端的情况下也无法导入鞭毛。我们得出结论，IFT46的N端、ODA16和外臂动力蛋白相互作用以实现后者的IFT。
