Mechanical properties of inner-arm dynein-F (dynein I1) studied with in vitro motility assays
Mechanical properties of inner-arm dynein-F (dynein I1) studied with in vitro motility assays
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DOI：
10.1529/biophysj.106.101964
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发表时间：
2007-08-01
影响因子：
3.4
通讯作者：
Oiwa, Kazuhiro
中科院分区：
文献类型：
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作者：
Kotani, Norito;Sakakibara, Hitoshi;Oiwa, Kazuhiro
衣原体鞭毛的内臂动力蛋白f是一种异源二聚体动力蛋白。我们进行了传统的体外运动性测定，表明动力蛋白-f以相对较低的速度（类似于1.2 μ m/s）移位微管。根据动力蛋白-f的表面密度与速度的关系，我们估计其占空比为0.6-0.7。微管着陆率和表面密度的动力蛋白-f之间的关系很好地拟合的一次幂的依赖性，如预期的进行性电机。在低的动力蛋白密度，进步微管不规则地旋转的表面上，在一个单一的动力蛋白-f分子大概位于一个固定的点。我们得出结论，动力蛋白f具有高的持续合成能力。然而，在轴丝中，缓慢和进行性动力蛋白-f可以阻止由其他快速动力蛋白驱动的微管滑动（例如，动力蛋白-c）。为了深入了解动力蛋白-f在体内的作用，我们测量了由动力蛋白-c和-f的混合物驱动的微管在各种混合比例下的滑动速度。速度作为混合物中动力蛋白-f比例的函数进行调制。这种调制表明，动力蛋白-f作为轴丝中的负载，但力推动动力蛋白-f分子向前似乎加速其从微管的解离。
Inner-arm dynein-f of Chlamydomonas flagella is a heterodimeric dynein. We performed conventional in vitro motility assays showing that dynein-f translocates microtubules at the comparatively low velocity of similar to 1.2 mu m/s. From the dependence of velocity upon the surface density of dynein-f, we estimate its duty ratio to be 0.6-0.7. The relation between microtubule landing rate and surface density of dynein-f are well fitted by the first-power dependence, as expected for a processive motor. At low dynein densities, progressing microtubules rotate erratically about a fixed point on the surface, at which a single dynein-f molecule is presumably located. We conclude that dynein-f has high processivity. In an axoneme, however, slow and processive dynein-f could impede microtubule sliding driven by other fast dyneins (e.g., dynein-c). To obtain insight into the in vivo roles of dynein-f, we measured the sliding velocity of microtubules driven by a mixture of dyneins-c and -f at various mixing ratios. The velocity is modulated as a function of the ratio of dynein-f in the mixture. This modulation suggests that dynein-f acts as a load in the axoneme, but force pushing dynein-f molecules forward seems to accelerate their dissociation from microtubules.