Department of Condensed Matter Physics, Science Faculty, Universidad Autónoma de Madrid, Madrid, Spain.
PLoS One. 2010 Aug 26;5(8):e12314. doi: 10.1371/journal.pone.0012314.
Genetic circuits can implement elaborated tasks of amplitude or frequency signal detection. What type of constraints could circuits experience in the performance of these tasks, and how are they affected by molecular noise? Here, we consider a simple detection process-a signal acting on a two-component module-to analyze these issues. We show that the presence of a feedback interaction in the detection module imposes a trade-off on amplitude and frequency detection, whose intensity depends on feedback strength. A direct interaction between the signal and the output species, in a type of feed-forward loop architecture, greatly modifies these trade-offs. Indeed, we observe that coherent feed-forward loops can act simultaneously as good frequency and amplitude noise-tolerant detectors. Alternatively, incoherent feed-forward loop structures can work as high-pass filters improving high frequency detection, and reaching noise tolerance by means of noise filtering. Analysis of experimental data from several specific coherent and incoherent feed-forward loops shows that these properties can be realized in a natural context. Overall, our results emphasize the limits imposed by circuit structure on its characteristic stimulus response, the functional plasticity of coherent feed-forward loops, and the seemingly paradoxical advantage of improving signal detection with noisy circuit components.
遗传电路可以实现对幅度或频率信号检测的复杂任务。在执行这些任务时，电路可能会遇到哪些类型的约束，以及分子噪声如何影响这些约束？在这里，我们考虑一个简单的检测过程——信号作用于一个双组分模块——来分析这些问题。我们表明，检测模块中存在反馈相互作用会对幅度和频率检测产生权衡，其强度取决于反馈强度。信号与输出物质之间的直接相互作用，在一种前馈环结构中，会极大地改变这些权衡。实际上，我们观察到相干前馈环可以同时作为频率和幅度噪声容忍检测器。或者，非相干前馈环结构可以作为高通滤波器，提高高频检测性能，并通过噪声滤波实现噪声容忍。对来自几个特定的相干和非相干前馈环的实验数据的分析表明，这些特性可以在自然环境中实现。总的来说，我们的结果强调了电路结构对其特征刺激反应的限制、相干前馈环的功能可塑性，以及用噪声电路元件提高信号检测的看似矛盾的优势。
