The mechanism regulating the activity of oscillatory motor protein, dynein

鞭毛运动的一个显著特征是摆动。鞭毛振荡运动是基于动力蛋白的活性，动力蛋白是微管运动蛋白之一。本研究旨在阐明鞭毛轴突中动力蛋白活性的调控机制。本研究以海胆精子鞭毛为材料，对鞭毛进行脱膜、碎裂，然后用弹性蛋白酶处理。应用1mm ATP诱导弹性酶处理的轴突体滑动成两组双联体，其中一组包含中心对。当用几种荧光ATP代替ATP时，我们发现动力蛋白水解它们而不引起滑动。在第二个实验中，我们发现，在ATP存在的情况下，将外臂的350 kDa胰蛋白酶片段添加到轴突中，ATP诱导的轴突中有内臂和5%外臂的滑动速度显著增加。由于碎片的atp酶活性高于外臂，动力蛋白臂之间的活性可能是通过双态微管调节的。在第三个实验中，通过单线态微管与暴露的动力蛋白臂相互作用，研究了中心对对动力蛋白活性的影响，并对分裂轴突进行了超微结构分析。我们发现钙通过涉及中央对和径向辐复合体的调节机制抑制双联体上动力蛋白臂的活性。该机制可能控制轴突内动力蛋白活性的转换，从而诱导鞭毛的振荡弯曲运动。

A prominent feature of flagellar motility is an oscillation. Flagellar oscillatory movement is based on the activity of dynein, which is one of the microtubule motor proteins. In this study we aimed to elucidate the mechanism regulating the dynein activity in the flagellar axonemes. We used sea urchin sperm flagella, which were demembranated, fragmented and then treated with elastase. An application of 1 mM ATP induced sliding of the elastase-treated axonemes into two groups of doublets, one of them contained the central pair. When several kinds of fluorescent ATP were used instead of ATP, we found that the dynein hydrolysed them without inducing the sliding. In the second experiment, we found that the velocity of sliding induced by ATP in the elastase-treated axonemes, which had the inner arms and 5% of the outer arms, was significantly increased by adding 350 kDa trypsin-fragments of the outer arms to the axonemes in the presence of ATP. Because the ATPase activity of the fragments was higher than that of the outer arms, the activity between dynein arms might be regulated through the doublet microtubules. In the third experiment, the effect of the central pair on dynein activity was studied by using singlet microtubules, which interacted with exposed dynein arms on doublets of the doublet groups and ultrastructural analysis of split axonemes. We found that calcium inhibits the activity of dynein arms on the doublets through the regulatory mechanism that involves the central pair and the radial spoke complex. This mechanism might control the switching of the dynein activity within the axoneme to induce the oscillatory bending movement of the flagellum.