Perfect and near-perfect adaptation in a model of bacterial chemotaxis
Perfect and near-perfect adaptation in a model of bacterial chemotaxis
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DOI：
10.1016/s0006-3495(03)70021-6
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发表时间：
2003-05-01
影响因子：
3.4
通讯作者：
Tu, Y
中科院分区：
文献类型：
--
作者：
Mello, BA;Tu, Y
介导细菌趋化性的信号装置可以适应广泛的持续外部刺激。在许多情况下，细菌的活性会精确地恢复到刺激前的水平，这种完美的适应性对各种趋化性蛋白浓度的变化具有鲁棒性。我们模拟了细菌趋化性信号通路，从配体结合到CheY磷酸化。通过解析求解模型的稳态方程，我们得到了一套完整的条件，系统实现完美的适应。与该途径的磷酸化部分相关的条件是首次发现的，而其他条件是在以前的工作中发现的条件的概括。通过扰动这些条件来评估完美适应的灵敏度。我们发现，即使在一些完美的适应条件的情况下，适应可以实现与接近完美的精度作为结果的分离的尺度在两个趋化蛋白浓度和反应速率，或在不同的甲基化状态的受体分布的特定属性。由于接近完美的适应可以在比完美适应条件定义的参数空间大得多的区域中找到，因此它们的存在对于理解细菌趋化性的鲁棒性至关重要。
The signaling apparatus mediating bacterial chemotaxis can adapt to a wide range of persistent external stimuli. In many cases, the bacterial activity returns to its prestimulus level exactly, and this perfect adaptability is robust against variations in various chemotaxis protein concentrations. We model the bacterial chemotaxis signaling pathway, from ligand binding to CheY phosphorylation. By solving the steady-state equations of the model analytically, we derive a full set of conditions for the system to achieve perfect adaptation. The conditions related to the phosphorylation part of the pathway are discovered for the first time, while other conditions are generalizations of the ones found in previous works. Sensitivity of the perfect adaptation is evaluated by perturbing these conditions. We find that, even in the absence of some of the perfect adaptation conditions, adaptation can be achieved with near-perfect precision as a result of the separation of scales in both chemotaxis protein concentrations and reaction rates, or specific properties of the receptor distribution in different methylation states. Since near-perfect adaptation can be found in much larger regions of the parameter space than that defined by the perfect adaptation conditions, their existence is essential to understand robustness in bacterial chemotaxis.