Mapping of Escherichia coli chromosomal Tn5 and F insertions by pulsed field gel electrophoresis.

A low resolution Not I physical map of Escherichia coli was recently constructed. In this report we demonstrated that this map can be used to map Tn5 and F insertions physically. The transposon, Tn5, contains Not I recognition sequences in its IS50 sequences. F plasmid contains an unmapped Not I site. Hence, the location of Tn5 and F in the chromosome can be mapped by identifying the location of the introduced Not I sites using pulsed field gel electrophoresis. The physical mapping of genetically mapped Tn5 insertions confirm the previously constructed Not I map and helps align the E. coli physical and genetic maps. The use of Tn5 can assist the construction of both physical and genetic maps for microorganisms lacking such maps. Variations on this approach will facilitate physical mapping with a wide variety of organisms, enzymes, and genetic elements.