In Vitro Study of ISApl1-Mediated Mobilization of the Colistin Resistance Gene mcr-1

The plasmid-mediated mcr-1 gene encodes a phosphoethanolamine transferase that confers resistance to polymyxins. The mcr-1 gene is associated with insertion sequence ISApl1 (IS30 family). In vitro mobilization assays demonstrated the functionality of the composite transposon structure ISApl1-mcr-1-ISApl1. Transposition generated a 2-bp duplication and occurred in AT-rich DNA regions. This is the first report demonstrating the mobility of the mcr-1 gene by transposition.