Abstract

This study proposes a physical mechanism underlying the torque generation of a bacterial flagellar motor (BFM), in which the torque for the rotation of the rotor can be generated from impulsive forces resulting from collisions between the randomly moving stator and rotor. The torque required for the rotation of the rotor may be generated through two coexisting mechanisms: mechanism (A), in which the stator collides with the rotor, whose rotation axis fluctuates asymmetrically, generating a torque in the direction of the rod, and mechanism (B), in which physical collisions between the stator and the asymmetric \(\hbox {FliG}_{{\mathrm{N}}\, }\)and \(\hbox {FliG}_{{\mathrm{M}}}\) generate the torque in the direction of the rod. Mechanism (A) might be related the bidirectional rotation and the tumbling of the motion of the cell. Mechanism (B) might be related to occurrence of the steps in the time traces of the rotational angle, backward stepping or switching of the rotational direction, and the knee-shaped \(\uptau _{{\mathrm{ext}}}\)–\(\upomega \) relation. The above-mentioned characteristics of the rotation of BFM are reproduced in a model device designed to confirm the applicability of the proposed concept to real BFM. Moreover, a prediction of the disappearance of the knee-shaped \(\uptau _{\mathrm{ext}}\)–\(\upomega \) relation of the actual BFM at a high temperature is proposed.

Graphic abstract

中文翻译：

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细菌鞭毛马达扭矩产生的物理机制

摘要

本研究提出了细菌鞭毛马达 (BFM) 产生扭矩的物理机制，其中转子旋转的扭矩可以由随机移动的定子和转子之间的碰撞产生的脉冲力产生。转子旋转所需的扭矩可以通过两种并存的机构产生：机构（A），其中定子与转子碰撞，其旋转轴不对称波动，产生沿杆方向的扭矩，机构（ B)，其中定子与非对称的\(\hbox {FliG}_{{\mathrm{N}}\, }\)和\(\hbox {FliG}_{{\mathrm{M} }}\)产生沿杆方向的扭矩。机制（A）可能与双向旋转和细胞运动的翻滚有关。机制 (B) 可能与旋转角度的时间轨迹中出现阶跃、旋转方向的后退或切换以及膝状\(\uptau _{{\mathrm{ext}}}\ ) – \(\upomega \)关系。BFM 旋转的上述特征在模型设备中重现，该模型设备旨在确认所提出的概念对实际 BFM 的适用性。此外，还提出了高温下实际 BFM的膝形\(\uptau _{\mathrm{ext}}\) - \(\upomega \)关系消失的预测。

图形摘要