tn2

Tn2 is a transposable element, or transposon, identified in bacteria and considered a member of the Tn3 family of transposable elements. As with many members of this family, Tn2 typically features terminal inverted repeats, a transposase gene that mediates movement, and a resolvase gene within a res locus that participates in the resolution of cointegrate intermediates formed during transposition. Tn2 commonly carries antibiotic resistance determinants, most notably beta-lactamase genes, which can confer resistance to beta-lactam antibiotics when the element is located on plasmids or chromosomes.

Movement of Tn2 occurs by replicative transposition, whereby a new copy of the transposon is generated and inserted into a target DNA molecule, often producing a cointegrate structure. The resolvase acts to resolve this cointegrate, resulting in the transposon being present in the recipient DNA and, in many cases, preserving resistance genes that can spread between genetic elements.

Distribution and impact of Tn2 have been documented in a range of Gram-negative bacteria, including both plasmids and chromosomal contexts. Through its ability to move between DNA molecules, Tn2 contributes to the horizontal transfer of antibiotic resistance traits, which has implications for clinical treatment and public health. Its study helps illuminate broader aspects of transposition mechanisms, element regulation, and the epidemiology of resistance determinants.

In summary, Tn2 is a well-characterized bacterial transposon that exemplifies how mobile genetic elements facilitate the dissemination of antibiotic resistance within and between bacterial populations.