Transposon Tn7

Tp7 is a bacterial DNA cut and paste transposon that is distinguished by its ability to use several different pathways for target selection. It may insert into a single specific chromosomal site called attTn7 that provides a "safe haven", insert preferentially into a conjugating plasmid that can facilitate its dispersal through bacterial populations or not insert into these targets because of cis-acting target immunity. This sophisticated choice of target sites is mediated by a complex transposition machine including a novel two-polypeptide transposase, pathway-specific targeting proteins and an ATP-dependent regulator that bridges the donor DNA and the target DNA interactions. 7n7-like transposons are widespread in nature and are found in bacterial chromosomes, in some cases forming genomic islands, and also on plasmids.