Bacterial regulatory networks are known to evolve rapidly due to lateral gene transfer and duplication events. However, the contribution of point mutations to this process is poorly understood. Using large-scale publicly available data, we addressed this question using E. coli as a model, eventually suggesting that large-effect point mutations in TFs may drive the early stages of adaptation but that transcriptiion factors are subjected to stronger purifying selection post-adaptation which might be driven by horizontal gene transfer.

Keywords: transcription factors, gene regulation, evolution, mutation