Transfer of Non-coding DNA Drives Regulatory Rewiring in Bacteria

The rapid pace of evolution in bacteria is widely attributed to the promiscuous horizontal transfer and recombination of protein-coding genes. However, it is not known whether the same forces also drive the evolution of non-coding regulatory regions. Here we demonstrate that regulatory region can ‘switch’ between non-homologous alternatives and that such switching is ubiquitous, occurring across the bacterial domain. We show that such regulatory switching strongly impacts promoter architecture and expression divergence. We further show that regulatory transfer facilitates rapid phenotypic diversification of a human pathogen. This regulatory mobility enables bacterial genes to access a vast pool of potential regulatory elements, facilitating efficient exploration of the regulatory landscape. Overall design: Examination of 2 E. coli strains in 2 conditions