IS 26 -Mediated Formation of Transposons Carrying Antibiotic Resistance Genes

Abstract

In Gram-negative bacteria, IS 26 recruits antibiotic resistance genes into the mobile gene pool by forming transposons carrying many different resistance genes. In addition to replicative transposition, IS 26 was recently shown to use a novel conservative movement mechanism in which an incoming IS 26 targets a preexisting one. Here, we have demonstrated how IS 26 -bounded class I transposons can be produced from translocatable units (TUs) containing only an IS 26 and a resistance gene via the conservative reaction. TUs were incorporated next to an existing IS 26 , creating a class I transposon, and if the targeted IS 26 is in a transposon, the product resembles two transposons sharing a central IS 26 , a configuration observed in some resistance regions and when a transposon is tandemly duplicated. Though homologous recombination could also incorporate a TU, Tnp26 is far more efficient. This provides insight into how IS 26 builds transposons and brings additional transposons into resistance regions.