Experimental Evolution of Anticipatory Regulation in Escherichia coli

Abstract

Environmental cues in an ecological niche are often temporal in nature. For instance, in temperate climates, temperature is higher in daytime compared to during night. In response to these temporal cues, bacteria have been known to exhibit anticipatory regulation, whereby triggering response to a yet to appear cue. Such an anticipatory response in known to enhance Darwinian fitness, and hence, is likely an important feature of regulatory networks in microorganisms. However, the conditions under which an anticipatory response evolves as an adaptive response are not known. In this work, we develop a quantitative model to study response of a population to two temporal environmental cues, and predict variables which are likely important for evolution of anticipatory regulatory response. We follow this with experimental evolution of Escherichia coli in alternating environments of rhamnose and paraquat for ∼850 generations. We demonstrate that growth in this cyclical environment leads to evolution of anticipatory regulation. As a result, pre-exposure to rhamnose leads to a greater fitness in paraquat environment. Genome sequencing reveals that this anticipatory regulation is encoded via mutations in global regulators. Overall, our study contributes to understanding of how environment shapes the topology of regulatory networks in an organism.

Adaptive and pleiotropic effects of evolution in synonymous sugar environments

“…Fluctuating environments are known to generate genetic diversity (Abdul-Rahman et al, 2021; Ellegren & Galtier, 2016; Yamamichi et al, 2023), and alter gene expression via mutations in global regulators (López-Maury et al, 2008; Mahilkar et al, 2021; Podrabsky & Somero, 2004). By pointing at how minute changes in the evolution environment can also generate diverse genotypic changes, we have identified a simple yet significant driver of the process of generation of biodiversity in prokaryotes.…”

Convergent genetic adaptation of Escherichia coli in minimal media leads to pleiotropic divergence

“…Mutations in global regulators facilitate adaptation by altering gene regulation patterns ( Fong et al, 2005 ; Saxer et al, 2014 ; Rodriguez-Verdugo et al, 2016 ; Gonzalez-Gonzalez et al, 2017 ; Iyer et al, 2021 ; Mahilkar et al, 2021 ). Altered motility is one of the outcomes of change in gene regulation ( Conrad et al, 2010a ; Perez-Varela et al, 2017 ; Cutugno et al, 2020 ).…”