Mitchell David R, Nakatsugawa Masako
Department of Cell and Developmental Biology, State University of New York Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA.
J Cell Biol. 2004 Aug 30;166(5):709-15. doi: 10.1083/jcb.200406148.
Regulation of motile 9+2 cilia and flagella depends on interactions between radial spokes and a central pair apparatus. Although the central pair rotates during bend propagation in flagella of many organisms and rotation correlates with a twisted central pair structure, propulsive forces for central pair rotation and twist are unknown. Here we compared central pair conformation in straight, quiescent flagella to that in actively beating flagella using wild-type Chlamydomonas reinhardtii and mutants that lack radial spoke heads. Twists occur in quiescent flagella in both the presence and absence of spoke heads, indicating that spoke--central pair interactions are not needed to generate torque for twisting. Central pair orientation in propagating bends was also similar in wild type and spoke head mutant strains, thus orientation is a passive response to bend formation. These results indicate that bend propagation drives central pair rotation and suggest that dynein regulation by central pair--radial spoke interactions involves passive central pair reorientation to changes in bend plane.
能动的9+2型纤毛和鞭毛的调控依赖于辐条与中央微管对之间的相互作用。尽管在许多生物体的鞭毛中，中央微管对在弯曲传播过程中会旋转，且这种旋转与中央微管对的扭曲结构相关，但中央微管对旋转和扭曲的推进力尚不清楚。在这里，我们使用野生型莱茵衣藻和缺乏辐条头部的突变体，比较了静止鞭毛与活跃摆动鞭毛中的中央微管对构象。无论有无辐条头部，静止鞭毛中都会出现扭曲，这表明产生扭曲扭矩不需要辐条与中央微管对之间的相互作用。在野生型和辐条头部突变体菌株中，传播弯曲时中央微管对的方向也相似，因此方向是对弯曲形成的被动反应。这些结果表明弯曲传播驱动中央微管对旋转，并表明中央微管对 - 辐条相互作用对动力蛋白的调控涉及中央微管对被动重新定向以适应弯曲平面的变化。
