Figure 5.

DNA-CRP_SC interactions using saturating and non-saturating cAMP concentrations. A, interaction of CRP_SC^S/D with the 32-bp lac promoter using 0, 30, and 1000 μm cAMP, which correspond to unbound (open squares), singly (gray triangles), and doubly (black circles) cAMP-bound states. The solid lines represent the fit as described in Ref. 32. B, DNA binding affinity constants of CRP_SC^S/D, CRP_SC^S/WT, and CRP_SC^S/S when the proteins are in the unbound (open squares), singly (gray triangles), and doubly (black circles) cAMP-bound states. C, DNA binding affinity constants obtained from fluorescence anisotropy experiments for symmetric and asymmetric CRP_SC in the absence (open squares) and presence of saturating cAMP concentrations (black circles). For CRP_SC^WT/WT, CRP_SC^D/D, and CRP_SC^D/WT, [cAMP] = 200 μm. For CRP_SC^S/S, [cAMP] = 2000 μm. For CRP_SC^S/D, CRP_SC^S/WT, and CRP_SC^S+D/WT, [cAMP] = 1000 μm.