Cocrystals of Escherichia coli trp repressor bound to an alternative operator DNA sequence

Cocrystals of a 2:1 complex of trp repressor dimers with a DNA duplex containing a single, central operator half-site sequence are described. Crystals with different morphologies grew under diverse crystallization conditions within days to weeks by hanging-drop vapor-diffusion. Twinned rods split along their longitudinal cleft produce single crystals with space group C2 and unit cell dimensions a = 112.34 Å, b = 90.16 Å, c = 58.65 Å and β = 113.92°. The crystals diffract to 2.4 Å and are thus suitable for structural analysis by X-ray diffraction. Several heavy-atom derivative cocrystals have been obtained with iodouridine-substituted DNAs.