Toxin-Antitoxin Gene Pairs Found in Tn 3 Family Transposons Appear To Be an Integral Part of the Transposition Module

Abstract

Transposable elements (TEs) are important in genetic diversification due to their recombination properties and their ability to promote horizontal gene transfer. Over the last decades, much effort has been made to understand TE transposition mechanisms and their impact on prokaryotic genomes. For example, the Tn 3 family is ubiquitous in bacteria, molding their host genomes by the paste-and-copy mechanism. In addition to the transposition module, Tn 3 members often carry additional passenger genes (e.g., conferring antibiotic or heavy metal resistance and virulence), and three were previously known to carry a toxin-antitoxin (TA) system often associated with plasmid maintenance; however, the role of TA systems within the Tn 3 family is unknown. The genetic context of TA systems in Tn 3 members suggests that they may play a regulatory role in ensuring stable invasion of these Tns during transposition.