The interaction of the ferric uptake regulation protein with DNA.

The interaction of the Ferric Uptake Regulation (Fur) protein with the backbone of operator DNA was analyzed by hydroxyl radical footprinting and the ethylation interference assay. Comparison of the contacts made by Fur and those made by proteins containing the helix-turn-helix or related motifs shows that the mode of DNA binding by this repressor is unique. Ethylation interference experiments demonstrate that there are relatively few phosphate contacts of unique disposition while hydroxyl radical footprinting demonstrates that Fur-operator contacts are segregated on one face of the helix and span nearly three successive major grooves.