In the face of uncertainty, cell populations tend to diversify to enhance survival and growth. Previous studies established that cells can optimize such bet hedging upon environmental change by modulating gene expression to adapt both the average and diversity of phenotypes. Here, we demonstrate that cells can tune phenotypic diversity also using posttranslational modifications. In the chemotaxis network of Escherichia coli, we find, for both major chemoreceptors Tar and Tsr, that cell-to-cell variation in response sensitivity is dynamically modulated depending on the presence or absence of their cognate chemoeffector ligands in the environment. Combining experiments with mathematical modeling, we show that this diversity tuning requires only the environment-dependent covalent modification of chemoreceptors and a standing cell-to-cell variation in their allosteric coupling. Thus, when environmental cues are unavailable, phenotypic diversity enhances the population’s readiness for many signals. However, once a signal is perceived, the population focuses on tracking that signal.

面对不确定性，细胞群倾向于多样化以增强生存和生长。先前的研究表明，细胞可以通过调节基因表达来优化这种对环境变化的对冲，以适应表型的平均和多样性。在这里，我们证明细胞也可以使用翻译后修饰来调整表型多样性。在大肠杆菌的趋化网络中，我们发现，对于主要的化学感受器 Tar 和 Tsr，细胞间反应敏感性的变化是动态调节的，这取决于环境中它们的同源化学效应配体的存在与否。将实验与数学模型相结合，我们表明这种多样性调整只需要化学感受器的环境依赖性共价修饰和它们的变构耦合中的常设细胞间变化。因此，当环境线索不可用时，表型多样性增强了人口对许多信号的准备。但是，一旦感知到信号，人们就会专注于跟踪该信号。