Opposite responses by different chemoreceptors set a tunable preference point in Escherichia coli pH taxis
Opposite responses by different chemoreceptors set a tunable preference point in Escherichia coli pH taxis
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DOI：
10.1111/mmi.12070
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发表时间：
2012-12
影响因子：
3.6
通讯作者：
Yiling Yang;V. Sourjik
中科院分区：
文献类型：
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作者：
Yiling Yang;V. Sourjik
在细菌栖息地，跟随影响生长和生存的环境因素的空间梯度的能力在很大程度上是有利的。细菌在典型的引诱剂或驱避剂（如营养物质或毒素）梯度中单向趋化运动的策略已被很好地理解。然而，其他因素的最佳水平可能在梯度的中间点找到，因此需要向最佳方向进行双向策略运动。在这里，我们研究了大肠杆菌对pH的趋化反应，作为这种双向趋化的一个例子。我们证实大肠杆菌使用趋化性来避免极端的低pH和高pH，并证明在明确定义的pH值下，反应的标志从趋碱到趋酸颠倒。这种反转是通过两种主要的化学受体Tar和Tsr的相反pH感应实现的，因此反应的相对强度是由适应性受体甲基化调节的。我们进一步证明，pH响应的反转点可以根据细胞密度的变化而调整。
In bacterial habitats, the ability to follow spatial gradients of environmental factors that affect growth and survival can be largely advantageous. The bacterial strategy for unidirectional chemotactic movement in gradients of typical attractants or repellents, such as nutrients or toxins, is well understood. Optimal levels of other factors, however, may be found at intermediate points of a gradient and thus require a bidirectional tactic movement towards the optimum. Here we investigate the chemotactic response of Escherichia coli to pH as an example of such bidirectional taxis. We confirm that E. coli uses chemotaxis to avoid both extremes of low and high pH and demonstrate that the sign of the response is inverted from base‐seeking to acid‐seeking at a well‐defined value of pH. Such inversion is enabled by opposing pH sensing by the two major chemoreceptors, Tar and Tsr, such that the relative strength of the response is modulated by adaptive receptor methylation. We further demonstrate that the inversion point of the pH response can be adjusted in response to changes in the cell density.