Department of Cell Biology and Anatomy, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.
Elife. 2023 Apr 14;12:e84860. doi: 10.7554/eLife.84860.
Outer arm dynein (OAD) is the main force generator of ciliary beating. Although OAD loss is the most frequent cause of human primary ciliary dyskinesia, the docking mechanism of OAD onto the ciliary doublet microtubule (DMT) remains elusive in vertebrates. Here, we analyzed the functions of Calaxin/Efcab1 and Armc4, the two of five components of vertebrate OAD-DC (docking complex), using zebrafish spermatozoa and cryo-electron tomography. Mutation of caused complete loss of OAD, whereas mutation of caused only partial loss of OAD. Detailed structural analysis revealed that OADs are tethered to DMT through DC components other than Calaxin, and that recombinant Calaxin can autonomously rescue the deficient DC structure and the OAD instability. Our data demonstrate the discrete roles of Calaxin and Armc4 in the OAD-DMT interaction, suggesting the stabilizing process of OAD docking onto DMT in vertebrates.
外臂动力蛋白 (OAD) 是纤毛运动的主要力发生器。尽管 OAD 缺失是人类原发性纤毛运动障碍的最常见原因，但脊椎动物中 OAD 与纤毛双微管 (DMT) 的对接机制仍不清楚。在这里，我们使用斑马鱼精子和冷冻电镜断层扫描分析了 Calaxin/Efcab1 和 Armc4（脊椎动物 OAD-DC（对接复合物）的五个组成部分中的两个）的功能。 突变导致 OAD 完全缺失，而 突变仅导致 OAD 部分缺失。详细的结构分析表明，OAD 是通过除了 Calaxin 以外的 DC 成分与 DMT 连接的，重组 Calaxin 可以自主挽救 DC 结构和 OAD 不稳定性的缺陷。我们的数据表明 Calaxin 和 Armc4 在 OAD-DMT 相互作用中具有不同的作用，这表明在脊椎动物中 OAD 对接至 DMT 的稳定过程。
