Target Search Processes During Horizontal Gene Transfer in Bacteria

In the absence of sex as in higher organisms such as mammals and plants, bacteria engage in horizontal gene transfer processes in order to acquire new ben-eficial traits and drive their genetic diversity in one stroke. Often, exogenous DNA integrates into the genome of a host at unique sites that are found within physi-ologically relevant times, among millions of possible sites on the host’s genome. Here we address the question of what are the search mechanisms that allow these unique sites to be found efficiently, within the complex interior of a bacterial cell. We review recent advances in the field, enabled by the ability to follow in real time search processes at the level of individual molecules within single cells.