Transient locking of the hook procures enhanced motility to flagellated bacteria
Transient locking of the hook procures enhanced motility to flagellated bacteria
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DOI：
10.1038/s41598-017-16562-4
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发表时间：
2017-11-27
影响因子：
4.6
通讯作者：
Rainville, Simon
中科院分区：
文献类型：
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作者：
Duchesne, Ismael;Galstian, Tigran;Rainville, Simon
鞭毛细菌通常在非均匀环境中增殖，如生物膜、菌群和土壤。在这样的介质中，细菌只有通过大幅改变游动方向，甚至完全逆转游动方向，才能走出“死胡同”，才能有效地运动。尽管这种重新定向无处不在，但我们直到最近才开始描述和理解它们是如何发生的。在目前的工作中，我们可视化的鞭毛的细菌游泳在软琼脂溶液。令人惊讶的观察是，当从细胞的一侧翻转到另一侧时，细丝并不旋转，这表明反转直接由马达驱动，而不是由旋转细丝产生的推力驱动。这一点通过观察液晶中的细菌得到了证实，其中细菌的线性运动大大简化了分析。这些观察结果表明，反转和重新定位过程涉及鞭毛钩的暂时锁定，鞭毛钩是旋转马达和推动细胞的长螺旋丝之间的正常柔性接头。这种新描述的锁钩模式仅在电机切换到顺时针旋转时发生。这与其他现象相关，这些现象是由一个方向的开关触发的，而不是另一个方向。
Flagellated bacteria often proliferate in inhomogeneous environments, such as biofilms, swarms and soil. In such media, bacteria are observed to move efficiently only if they can get out of "dead ends" by changing drastically their swimming direction, and even to completely reverse it. Even though these reorientations are ubiquitous, we have only recently begun to describe and understand how they happen. In the present work, we visualized the flagella of bacteria swimming in a soft agar solution. The surprising observation that the filaments do not rotate while being flipped from one side of the cell to the other suggests that reversals are driven directly by the motor rather than by the thrust created by the rotating filament. This was confirmed by observing bacteria in a liquid crystal, where the linear movement of bacteria greatly simplifies the analysis. These observations suggest that the reversal and reorientation processes involve a temporary locking of the flagellum's hook, which is the normally flexible joint between the rotary motor and the long helical filament that propels the cell. This newly described locked-hook mode occurs only when the motor switches to a clockwise rotation. That correlates with other phenomena that are triggered by a switch in one direction and not the other.