Coexistence of Two Chiral Helices Produces Kink Translation in Spiroplasma Swimming
Coexistence of Two Chiral Helices Produces Kink Translation in Spiroplasma Swimming
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DOI：
10.1128/jb.00735-19
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发表时间：
2020-04-01
影响因子：
3.2
通讯作者：
Nishizaka, Takayuki
中科院分区：
文献类型：
--
作者：
Nakane, Daisuke;Ito, Tatsuro;Nishizaka, Takayuki
螺旋体游泳的机制是一个谜。这种小细菌一次拥有两个反手的螺旋形状，它们之间的边界称为扭结，向下移动，可能伴随着这些物理上相连的螺旋结构的双重旋转，没有任何旋转马达，如鞭毛。虽然已经提出了动力学和结构基础的轮廓，但缺乏解释扭结翻译的深层原因。在此，我们证明了在加入氰基-3-氯苯肼(CCCP)停止运动后，毛状螺旋体的细胞形态被固定在右手螺旋上，并在光照射的触发下将优先状态转变为反手状态。这一过程与人造扭结的产生和传播相结合，想必没有任何通过生物马达输入的能量。这些发现表明，两个手性螺旋的共存足以繁殖扭结，从而推动细胞体。然而，非鞭毛细菌螺旋体(Spirodium spp.)游泳时不要使用附属物。这种微小的无壁细菌一次拥有两个手性螺旋，称为扭结的边界向下移动，可能伴随着螺旋的双重旋转。为了解决这个谜团，我们开发了一种方法来确定单风水平上身体螺旋的利手性，并证明了身体螺旋的共存触发了扭结的平移，细胞体通过由此产生的细胞弯曲繁殖而移动。这一发现为我们提供了细菌运动的一个全新的方面，身体就像一个可变形的螺丝钉一样推动自己前进。
The mechanism underlying Spiroplasma swimming is an enigma. This small bacterium possesses two helical shapes with opposite-handedness at a time, and the boundary between them, called a kink, travels down, possibly accompanying the dual rotations of these physically connected helical structures, without any rotary motors such as flagella. Although the outline of dynamics and structural basis has been proposed, the underlying cause to explain the kink translation is missing. We here demonstrated that the cell morphology of Spiroplasma eriocheiris was fixed at the right-handed helix after motility was stopped by the addition of carbonyl cyanide 3-chlorophenylhydrazone (CCCP), and the preferential state was transformed to the other-handedness by the trigger of light irradiation. This process coupled with the generation and propagation of the artificial kink, presumably without any energy input through biological motors. These findings indicate that the coexistence of two chiral helices is sufficient to propagate the kink and thus to propel the cell body.IMPORTANCE Many swimming bacteria generate a propulsion force by rotating helical filaments like a propeller. However, the nonflagellated bacteria Spiroplasma spp. swim without the use of the appendages. The tiny wall-less bacteria possess two chiral helices at a time, and the boundary called a kink travels down, possibly accompanying the dual rotations of the helices. To solve this enigma, we developed an assay to determine the handedness of the body helices at the single-wind level, and demonstrated that the coexistence of body helices triggers the translation of the kink and that the cell body moves by the resultant cell bend propagation. This finding provides us a totally new aspect of bacterial motility, where the body functions as a transformable screw to propel itself forward.