Regulatory evolution at the host–pathogen interface1

Horizontal gene transfer plays a major role in microbial evolution by innovating the bacterial genome with new genetic blueprints to adapt to previously unexploited niches. However, to benefit from these genetic acquisitions, the bacterium must integrate the expression of these new genes into existing regulatory nodes and deploy them at the right time. There is much to gain from uncovering the genetic diversity in noncoding DNA that is selective during host infection because of the beneficial effect it has on bacterial gene expression. By identifying genes that have undergone regulatory evolution, a deeper understanding of the arms race between host and pathogen is gained.