Live-cell fluorescence imaging reveals dynamic production and loss of bacterial flagella
Live-cell fluorescence imaging reveals dynamic production and loss of bacterial flagella
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DOI：
10.1111/mmi.14511
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发表时间：
2020-05-02
影响因子：
3.6
通讯作者：
Bai, Fan
中科院分区：
文献类型：
--
作者：
Zhuang, Xiang-Yu;Guo, Shihao;Bai, Fan
细菌鞭毛是纳米机器，驱动细菌的运动性和趋化性，以应对环境变化。鞭毛是否是永久性的细胞结构，如果不是，在细菌生命周期中其产生和丧失的环境和时间仍然知之甚少。在这里，我们使用溶藻弧菌的单极鞭毛作为我们的模型，并实施体内荧光成像显示，在不同的生长阶段，在人口中的鞭毛细菌（PFB）的百分比变化很大。在指数生长早期，PFB通过鞭毛的广泛产生而迅速增加。在指数中期，PFB峰值在76%左右，鞭毛在子细胞之间的分配为1：1，并且严格地在旧极。进入稳定期后，PFB开始下降，主要是因为子细胞在细胞分裂后停止制造新的鞭毛。有趣的是，我们观察到细菌在长时间的静止培养后可以主动放弃鞭毛，尽管细胞分裂早已暂停。进一步的实验研究证实，鞭毛在溶藻弧菌中从杆中的断裂开始喷射。我们的研究结果强调了鞭毛在细菌生命周期中的动态产生和损失。重要性鞭毛运动对许多细菌物种至关重要。细菌鞭毛在其最终结构中由大约20种不同类型的蛋白质组成，并且可以自组装。目前对细菌鞭毛的寿命和耐久性的了解非常有限。在本研究中，我们监测溶藻弧菌鞭毛的组装和损失，在体内荧光标记，并发现，鞭毛细菌的百分比在不同的生长阶段有很大的不同。鞭毛的产生与细胞生长同步，但当细胞进入稳定期时停止。令人惊讶的是，我们观察到，细菌可以主动放弃鞭毛后，长期的静态培养，以及在低葡萄糖缓冲介质。然后我们证实溶藻弧菌鞭毛的射出是从杆的断裂开始的。我们的研究结果突出了细菌生命周期中鞭毛的动态产生和损失。
Bacterial flagella are nanomachines that drive bacteria motility and taxis in response to environmental changes. Whether flagella are permanent cell structures and, if not, the circumstances and timing of their production and loss during the bacterial life cycle remain poorly understood. Here we used the single polar flagellum of Vibrio alginolyticus as our model and implementing in vivo fluorescence imaging revealed that the percentage of flagellated bacteria (PFB) in a population varies substantially across different growth phases. In the early-exponential phase, the PFB increases rapidly through the widespread production of flagella. In the mid-exponential phase, the PFB peaks at around 76% and the partitioning of flagella between the daughter cells are 1:1 and strictly at the old poles. After entering the stationary phase, the PFB starts to decline, mainly because daughter cells stop making new flagella after cell division. Interestingly, we observed that bacteria can actively abandon flagella after prolonged stationary culturing, though cell division has long been suspended. Further experimental investigations confirmed that flagella were ejected in V. alginolyticus, starting from breakage in the rod. Our results highlight the dynamic production and loss of flagella during the bacterial life cycle.Importance Flagella motility is critical for many bacterial species. The bacterial flagellum is made up of about 20 different types of proteins in its final structure and can be self-assembled. The current understanding of the lifetime and durability of bacterial flagella is very limited. In the present study, we monitored Vibrio alginolyticus flagellar assembly and loss by in vivo fluorescence labeling, and found that the percentage of flagellated bacteria varies substantially across different growth phases. The production of flagella was synchronized with cell growth but stopped when cells entered the stationary phase. Surprisingly, we observed that bacteria can actively abandon flagella after prolonged stationary culturing, as well as in the low glucose buffering medium. We then confirmed the ejection of flagella in V. alginolyticus started with breakage of the rod. Our results highlight the dynamic production and loss of flagella during the bacterial life cycle.