Figure 4.

Effect of symmetric and asymmetric mutations on cAMP binding affinity. A, cAMP titrations to CRP_SC^WT/WT (green circles) and the symmetric mutants CRP_SC^D/D (red circles) and CRP_SC^S/S (dark purple circles). B, cAMP titrations to the single asymmetric mutants CRP_SC^D/WT (light pink squares) and CRP_SC^S/WT (light purple squares). C, cAMP titrations to the double asymmetric mutants CRP_SC^S+D/WT (dark brown diamonds) and CRP_SC^S/D (beige diamonds). For comparison, the dashed lines corresponding to the fits of the parent symmetric proteins obtained from A were included in B and C. The solid lines in all three panels represent the fit using a two-site binding model as described under “Materials and Methods.” Error bars correspond to the standard deviation of at least three repeats.