[1] The existence of transposons was postulated in the late 1940s by Barbara McClintock, who was studying the inheritance of maize, but the actual molecular basis for transposition was described by later groups.

[2] Transposition is also important in creating genetic diversity within species and generating adaptability to changing living conditions.

[2] Transposase (Tnp) Tn5 is a member of the RNase superfamily of proteins which includes retroviral integrases.

Because DNA transposition events are inherently mutagenic, the low activity of transposases is necessary to reduce the risk of causing a fatal mutation in the host, and thus eliminating the transposable element.

[7] The DDE motif is said to coordinate divalent metal ions, most often magnesium and manganese, which are important in the catalytic reaction.

[3] There are several steps which catalyze the movement of the transposon, including Tnp binding, synapsis (the creation of a synaptic complex), cleavage, target capture, and strand transfer.

[3] In cleavage, the magnesium ions activate oxygen from water molecules and expose them to nucleophilic attack.

[6] This allows the water molecules to nick the 3' strands on both ends and create a hairpin formation, which separates the transposon from the donor DNA.

[3] As mentioned before, due to the mutations of the DDE, some steps of the process are lost—for example, when this experiment is performed in vitro, and SDS heat treatment denatures the transposase.

The Tn5-based strategy can simplify the library preparation protocol significantly and can even can be incorporated into the direct colony-PCR for large numbers of bacterial isolates with no obvious coverage bias.

[19][20] Specifically classified as a transposable element (transposon), the sequence can duplicate and move itself within a genome by utilizing a self-encoded recombinase enzyme called a transposase, resulting in effects such as creating or reversing mutations and changing genome size.

Much like other characterized transposons, the mechanism for Tn7 transposition involves cleavage of the 3' ends from the donating DNA by the TnsA protein of the TnsAB transposase.

The TnsC protein interacts with the transposase enzyme and the target DNA to promote the excision and insertion processes.

The TnsD and TnsE proteins are alternative target selectors that are also DNA binding activators that promote excision and insertion of Tn7.

When the TnsE protein interacts with the TnsABC core machinery, Tn7 preferentially directs insertions into conjugable plasmids.

When the TnsD protein interacts with TnsABC, Tn7 preferentially directs insertions downstream into a single essential and highly conserved site in the bacterial chromosome.