Tn7 transposes proximal to DNA double-strand breaks and into regions wherechromosomal DNA replication terminates

We report that the bacterial transposon Tn7 can preferentially transpose in to regions where chromosomal DNA replication terminates. DNA double-strand breaks are associated with the termination of chromosomal replication; ther efore, we directly tested the effect of DNA breaks on Tn7 transposition. Wh en DNA double-strand breaks are induced at specific sites in the chromosome , Tn7 transposition is stimulated and insertions are directed proximal to t he induced break. The targeting preference for the terminus of replication and DNA double-strand breaks is dependent on the Tn7-encoded protein TnsE. The results presented in this study could also explain the previous observa tion that Tn7 is attracted to events associated with conjugal DNA replicati on during plasmid DNA transfer.