A microtubule-dynein tethering complex regulates the axonemal inner dynein f (I1).
A microtubule-dynein tethering complex regulates the axonemal inner dynein f (I1).
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DOI：
10.1091/mbc.e17-11-0689
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发表时间：
2018-05-01
影响因子：
3.3
通讯作者：
Oda T
中科院分区：
文献类型：
--
作者：
Kubo T;Hou Y;Cochran DA;Witman GB;Oda T
FAP 44和FAP 43/FAP 244形成一个复合物，将内动力蛋白亚种f拴在衣原体鞭毛的微管上。系链复合物通过抑制动力蛋白马达的构象变化来调节鞭毛运动。纤毛/鞭毛的运动是由成千上万的动力蛋白的协调活动产生的。内动力蛋白臂（IDAs）对于纤毛/鞭毛波形的形成特别重要，但IDA调节的分子机制知之甚少。在这里，我们显示使用冷冻电子断层扫描和生化分析的衣原体鞭毛的保守蛋白FAP 44形成一个复杂的系留IDA f（I1动力蛋白）头域的A-微管的轴丝外双微管。在野生型鞭毛中，IDA f除了在垂直于微管滑动方向的f β头上倾斜外，几乎没有核苷酸依赖性运动。然而，在没有系链复合物的情况下，添加ATP和钒酸盐引起IDA f头部结构域的大的构象变化，表明IDA f的运动受到系链复合物的机械限制。运动缺陷鞭毛失踪的系绳表明IDA F-系链相互作用的重要性，在纤毛/鞭毛跳动的调节。
FAP44 and FAP43/FAP244 form a complex that tethers the Inner dynein subspecies f to the microtubule in Chlamydomonas flagella. The tether complex regulates flagellar motility by restraining conformational change in the dynein motor. Motility of cilia/flagella is generated by a coordinated activity of thousands of dyneins. Inner dynein arms (IDAs) are particularly important for the formation of ciliary/flagellar waveforms, but the molecular mechanism of IDA regulation is poorly understood. Here we show using cryoelectron tomography and biochemical analyses of Chlamydomonas flagella that a conserved protein FAP44 forms a complex that tethers IDA f (I1 dynein) head domains to the A-tubule of the axonemal outer doublet microtubule. In wild-type flagella, IDA f showed little nucleotide-dependent movement except for a tilt in the f β head perpendicular to the microtubule-sliding direction. In the absence of the tether complex, however, addition of ATP and vanadate caused a large conformational change in the IDA f head domains, suggesting that the movement of IDA f is mechanically restricted by the tether complex. Motility defects in flagella missing the tether demonstrates the importance of the IDA f-tether interaction in the regulation of ciliary/flagellar beating.