In Vitro Study of IS Apl1 -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 IS Apl1 (IS 30 family). In vitro mobilization assays demonstrated the functionality of the composite transposon structure IS Apl1-mcr-1 -IS Apl1 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.