Torque Generation by Axonemal Outer-Arm Dynein
Torque Generation by Axonemal Outer-Arm Dynein
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DOI：
10.1016/j.bpj.2014.12.038
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发表时间：
2015-02-17
影响因子：
3.4
通讯作者：
Yajima，Junichiro
中科院分区：
文献类型：
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作者：
Yamaguchi，Shin;Saito，Kei;Yajima，Junichiro
外臂动力蛋白是纤毛提供动力的主要引擎。利用三维跟踪显微镜，我们发现与以前的报道相反，在微管螺旋分析中，四膜纤毛状三头外臂动力蛋白(αβγ)以及蛋白水解性产生的双头(βγ)和单头(α)亚颗粒显示每个滑动的微管绕其纵轴顺时针旋转。通过测量旋转螺距作为三磷酸腺苷浓度的函数，我们还发现微管螺旋螺距与三磷酸腺苷浓度无关，但在三头αβγ和单头α产生的螺距明显较长的情况下除外。相比之下，双头βγ驱动的俯仰没有表现出这种敏感性。在含有不同比例的α和βγ混合物的草坪上进行的测试中，随着α在混合物中比例的增加，螺旋螺距以非线性的方式急剧增加。即使是很小比例的α-亚颗粒也能显著增加混合物的螺旋螺距。我们的数据表明，扭矩的产生不需要三头外臂动力蛋白(αβγ)，而是轴线动力蛋白亚粒子的内在属性，也表明每个亚粒子可能具有不同的力学性质。
Outer-arm dynein is the main engine providing the motive force in cilia. Using three-dimensional tracking microscopy, we found that contrary to previous reportsTetrahymenaciliary three-headed outer-arm dynein (αβγ) as well as proteolytically generated two-headed (βγ) and one-headed (α) subparticles showed clockwise rotation of each sliding microtubule around its longitudinal axis in microtubule corkscrewing assays. By measuring the rotational pitch as a function of ATP concentration, we also found that the microtubule corkscrewing pitch is independent of ATP concentration, except at low ATP concentrations where the pitch generated by both three-headedαβγand one-headedαexhibited significantly longer pitch. In contrast, the pitch driven by two-headedβγdid not display this sensitivity. In the assays on lawns containing mixtures ofαandβγat various ratios, the corkscrewing pitch increased dramatically in a nonlinear fashion as the ratio ofαin the mixture increased. Even small proportions ofα-subparticle could significantly increase the corkscrewing pitch of the mixture. Our data show that torque generation does not require the three-headed outer-arm dynein (αβγ) but is an intrinsic property of the subparticles of axonemal dyneins and also suggest that each subparticle may have distinct mechanical properties.