Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA.
Mol Biol Cell. 2011 Dec;22(23):4527-38. doi: 10.1091/mbc.E11-08-0739. Epub 2011 Oct 12.
Generating the complex waveforms characteristic of beating cilia requires the coordinated activity of multiple dynein isoforms anchored to the axoneme. We previously identified a complex associated with the C1d projection of the central apparatus that includes primary ciliary dyskinesia protein 1 (Pcdp1). Reduced expression of complex members results in severe motility defects, indicating that C1d is essential for wild-type ciliary beating. To define a mechanism for Pcdp1/C1d regulation of motility, we took a functional and structural approach combined with mutants lacking C1d and distinct subsets of dynein arms. Unlike mutants completely lacking the central apparatus, dynein-driven microtubule sliding velocities are wild type in C1d- defective mutants. However, coordination of dynein activity among microtubule doublets is severely disrupted. Remarkably, mutations in either outer or inner dynein arm restore motility to mutants lacking C1d, although waveforms and beat frequency differ depending on which isoform is mutated. These results define a unique role for C1d in coordinating the activity of specific dynein isoforms to control ciliary motility.
产生具有纤毛跳动特征的复杂波形需要多个锚定在轴丝上的动力蛋白同工型的协调活动。我们之前确定了一个与中心体的 C1d 投射相关的复合物，其中包括原发性纤毛运动障碍蛋白 1（Pcdp1）。复合物成员的表达减少会导致严重的运动缺陷，表明 C1d 对于野生型纤毛跳动是必不可少的。为了定义 Pcdp1/C1d 对运动调节的机制，我们采用了功能和结构方法相结合的方法，结合了缺乏 C1d 和不同的动力蛋白臂亚类的突变体。与完全缺乏中心体的突变体不同，在 C1d 缺陷突变体中，动力蛋白驱动的微管滑动速度是野生型的。然而，微管二联体之间的动力蛋白活性的协调严重受损。值得注意的是，在外或内动力蛋白臂中的突变都可以使缺乏 C1d 的突变体恢复运动能力，尽管波形和跳动频率取决于突变的是哪种同工型。这些结果定义了 C1d 在协调特定动力蛋白同工型的活性以控制纤毛运动方面的独特作用。
