Mechanism and regulation of synthesis of aerobactin in Escherichia coli K12 (pColV-K30).

The aerobactin operon of the virulence plasmid pColV-K30 of Escherichia coli K12 consists of four genes for biosynthesis and one for transport of the siderophore. Regulation by iron occurs at the transcriptional level and is mediated by a ferrous iron binding protein designated Fur (ferric uptake regulation). The metallated Fur repressor binds at a palindromic dyad, the "iron box" operator, situated in the vicinity of the RNA polymerase attachment site of the promoter. Evidence suggests that the ferrous iron enters the C-terminal domain of Fur to cause a conformational change in the N-terminal part of the protein. This results in greatly enhanced affinity of the repressor for the operator.