Pulsed field gel electrophoresis to rapidly detect the presence of IncJ conjugative transposon-like elements

Aims: To develop a screening method to detect the presence of the IncJ group of integrating conjugative transposon-like elements upon transfer to Escherichia coli. Methods and Results: The unique insertion site of known IncJ elements, the prfC gene, is located in a region of the E. coli chromosome between 98.5 and 100 min on the E. coli genetic map. Using pulsed field gel electrophoresis and the rare cutting restriction enzymes SfiI and XbaI insertions of IncJ elements and an estimate of their size could be determined physically. Conclusions: This method allows initial screening of putative IncJ conjugative transposon-like elements by physical determination of their integration. Significance and Impact of the Study: IncJ-like elements, which appear to be highly homologous to the prototype IncJ element R391, have been found associated with recent epidemic outbreaks of cholera in a number of locations worldwide. Because of their integrative biology this method provides the first initial screening method to physically determine their presence upon transfer to E. coli.