Transposon Insertion Sequencing in a Clinical Isolate of Legionella pneumophila Identifies Essential Genes and Determinants of Natural Transformation.

is a Gram-negative bacterium ubiquitous in freshwater environments which, if inhaled, can cause a severe pneumonia in humans. The emergence of is linked to several traits selected in the environment, the acquisition of some of which involved intra- and interkingdom horizontal gene transfer events. Transposon insertion sequencing (TIS) is a powerful method to identify the genetic basis of selectable traits as well as to identify fitness determinants and essential genes, which are possible antibiotic targets.

Diverse conjugative elements silence natural transformation in species.

Natural transformation (i.e., the uptake of DNA and its stable integration in the chromosome) is a major mechanism of horizontal gene transfer in bacteria.

Natural transformation occurs independently of the essential actin-like MreB cytoskeleton in Legionella pneumophila.

Natural transformation is the process by which bacteria can actively take up and integrate exogenous DNA thereby providing a source of genetic diversity. Under specific growth conditions the coordinated expression of several genes--a situation referred to as "competence"--allows bacteria to assemble a highly processive and dedicated system that can import high molecular weight DNA. Within the cell these large imported DNA molecules are protected from degradation and brought to the chromosome for recombination.