Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, Sevilla 41012, Spain.
Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41012, Spain.
Proc Natl Acad Sci U S A. 2024 Sep 3;121(36):e2322371121. doi: 10.1073/pnas.2322371121. Epub 2024 Aug 30.
Epigenetic mechanisms can generate bacterial lineages capable of spontaneously switching between distinct phenotypes. Currently, mathematical models and simulations propose epigenetic switches as a mechanism of adaptation to deal with fluctuating environments. However, bacterial evolution experiments for testing these predictions are lacking. Here, we exploit an epigenetic switch in the operon, to show clear evidence that OpvAB bistability persists in changing environments but not in stable conditions. Epigenetic control of transcription in the operon produces OpvAB (phage-sensitive) and OpvAB (phage-resistant) cells in a reversible manner and may be interpreted as an example of bet-hedging to preadapt populations to the encounter with phages. Our experimental observations and computational simulations illustrate the adaptive value of epigenetic variation as an evolutionary strategy for mutation avoidance in fluctuating environments. In addition, our study provides experimental support to game theory models predicting that phenotypic heterogeneity is advantageous in changing and unpredictable environments.
表观遗传机制可以产生能够在不同表型之间自发转换的细菌谱系。目前，数学模型和模拟提出了表观遗传开关作为一种适应机制来应对不断变化的环境。然而，缺乏用于测试这些预测的细菌进化实验。在这里，我们利用操纵子中的一个表观遗传开关，清楚地表明 OpvAB 双稳态在不断变化的环境中持续存在，但在稳定条件下则不存在。操纵子中转录的表观遗传控制以可逆的方式产生 OpvAB（噬菌体敏感）和 OpvAB（噬菌体抗性）细胞，并且可以解释为预先适应种群与噬菌体相遇的一种风险分散策略。我们的实验观察和计算模拟说明了表观遗传变异作为一种在波动环境中避免突变的进化策略的适应性价值。此外，我们的研究为预测表型异质性在变化和不可预测的环境中有利的博弈论模型提供了实验支持。
