FIG. 1.

Fur binding site. A shows the 19-bp consensus Fur binding site for E. coli and various models of recognition. The top sequence shows the consensus Fur binding site. The lower left sequence demonstrates the classical model of binding, as described in the introduction. The classical model shows each monomer binding a 9-bp inverted repeat (shown as arrows) of the consensus, with an A:T base pair in between. The lower right sequence depicts the hexamer model, also described in the introduction, with the unit of recognition being the sequence 5′-GATAAT-3′ (shown as arrows). It is uncertain how Fur would bind this sequence; some have suggested that each hexamer is recognized by a single dimer. B shows the binding sites tested in this study.