Tn5 mutagenesis of the enterochelin gene cluster of Escherichia coli.

Three recombinant plasmids have been studied which collectively carry all the nine known genes of the enterochelin system of iron transport in Escherichia coli K-12. The genetic organization of these genes was studied using a combination of Tn5 mutagenesis, subcloning of restriction fragments and restriction mapping. The order of the genes was established as entD, fes, entF, fep, and entCAGBE and the nine genes were shown to be distributed across 26 kb of DNA. The results of these studies indicate that the genes are organized into at least six transcriptional units.