Confirmation of the Fur operator site by insertion of a synthetic oligonucleotide into an operon fusion plasmid.

We constructed a synthetic oligonucleotide corresponding to the previously proposed consensus binding site for the Fur protein, a central iron-regulatory protein of Escherichia coli. When this oligonucleotide was introduced at the start of transcription of an operon fusion between the ompF promoter and the lacZ structural gene, beta-galactosidase activity became iron regulated. This consensus sequence is sufficient to function as an operator site for the binding of Fur protein in vivo.