The N-terminus of IFT46 mediates intraflagellar transport of outer arm dynein and its cargo-adaptor ODA16.
The N-terminus of IFT46 mediates intraflagellar transport of outer arm dynein and its cargo-adaptor ODA16.
复制标题
IFT46的N末端介导了外臂动力蛋白及其货物适应器ODA16的flagellar内运输。
DOI：
10.1091/mbc.e17-03-0172
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发表时间：
2017-09-01
影响因子：
3.3
通讯作者：
Witman GB
中科院分区：
文献类型：
--
作者：
Hou Y;Witman GB
转座子事件导致衣藻IFT46零突变体的部分抑制，从而可以探索IFT46 n端在鞭毛组装中的功能。IFT46 n端不是IFT复合体组装所必需的，但它是外臂动力蛋白及其适配器ODA16进入鞭毛的运输所必需的。纤毛通过鞭毛内运输（IFT）组装。IFT机器由马达和多亚单位粒子组成，称为IFT- a和IFT- b，它们将货物运送到纤毛中。了解IFT亚基如何与它们的货物相互作用对于理解独特的纤毛结构域是如何建立的至关重要。我们之前报道了一个衣藻突变体IFT46 -1，它不能表达IFT-B蛋白IFT46，大大降低了其他IFT-B蛋白的水平，并且只组装很短的鞭毛。ift46-1的自发抑制恢复了IFT-B水平，并使鞭毛生长更长，但鞭毛缺乏外部动力蛋白臂。在这里，我们发现这种抑制是由于转座子MRC1插入IFT46 -1等位基因，导致包含IFT46 c端240个氨基酸的融合蛋白的表达。IFT46 c端可以组装并稳定IFT-B，但不支持外臂动力蛋白向鞭毛的运输。在缺少IFT46 n端时，ODA16（一种外臂动力蛋白专用的负载适配器）也无法导入鞭毛。我们得出结论，IFT46 n端、ODA16和外臂动力蛋白对后者的IFT相互作用。
A transposon event, resulting in partial suppression of a Chlamydomonas IFT46 null mutant, allowed the function of the N-terminus of IFT46 in flagellar assembly to be explored. The IFT46 N-terminus is not required for IFT complex assembly but is required for transport of outer arm dynein and its adaptor, ODA16, into the flagellum. 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 Chlamydomonas mutant, ift46-1, 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 ift46-1 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 MRC1 into the ift46-1 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.