Flagellar dynamics reveal fluctuations and kinetic limit in the Escherichia coli chemotaxis network.
Flagellar dynamics reveal fluctuations and kinetic limit in the Escherichia coli chemotaxis network.
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DOI：
10.1038/s41598-023-49784-w
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发表时间：
2023-12-21
影响因子：
4.6
通讯作者：
中科院分区：
文献类型：
--
作者：
大肠杆菌趋化性网络是细菌调节其随机游动/翻滚游泳模式以适应其环境的网络，它必须像其他信号网络一样应对其分子组成中不可避免的数量波动(“噪声”)。顺时针(CW)鞭毛旋转的概率，或CW偏差，是趋化网络输出的衡量标准，其时间波动提供了网络噪声的替代。在这里，我们从鞭毛的切换统计数据中量化趋化信号网络的波动，该统计使用单个光学捕获的大肠杆菌细胞的时间分辨荧光显微镜观察。该方法允许在整个网络的动态范围内量化噪声。在稳态下发现了较大的CW偏置波动，这可能在驱动鞭毛切换和细胞翻滚中起到关键作用。当网络被化学刺激到更高的活性时，波动显著减少。一个随机理论模型受到基因表达噪声研究的启发，指出Chey在突发状态下激活，驱动CW偏差波动。该模型还表明，网络活动的内在动力学上限对激活的Chey和CW偏差设置了上限，当遇到这些偏差时，会抑制网络波动。这一限制还可以防止单元格在陡峭的渐变中徒劳地翻滚。
The Escherichia coli chemotaxis network, by which bacteria modulate their random run/tumble swimming pattern to navigate their environment, must cope with unavoidable number fluctuations (“noise”) in its molecular constituents like other signaling networks. The probability of clockwise (CW) flagellar rotation, or CW bias, is a measure of the chemotaxis network’s output, and its temporal fluctuations provide a proxy for network noise. Here we quantify fluctuations in the chemotaxis signaling network from the switching statistics of flagella, observed using time-resolved fluorescence microscopy of individual optically trapped E. coli cells. This approach allows noise to be quantified across the dynamic range of the network. Large CW bias fluctuations are revealed at steady state, which may play a critical role in driving flagellar switching and cell tumbling. When the network is stimulated chemically to higher activity, fluctuations dramatically decrease. A stochastic theoretical model, inspired by work on gene expression noise, points to CheY activation occurring in bursts, driving CW bias fluctuations. This model also shows that an intrinsic kinetic ceiling on network activity places an upper limit on activated CheY and CW bias, which when encountered suppresses network fluctuations. This limit may also prevent cells from tumbling unproductively in steep gradients.
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影响因子：
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作者：
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通讯作者：
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