Figure 7.

Mechanism of CRP activation and interaction with DNA. In the absence of cAMP, CRP is in an inactive state. Binding of cAMP to one CRP subunit triggers a conformational change in the DNA-binding domain of the bound subunit, generating an asymmetric conformation within the dimer. The cAMP-bound subunit induces a re-orientation in the unliganded neighboring subunit that is compatible with strong DNA interactions. Binding of a second cAMP molecule can occur to either the singly cAMP-bound CRP or to the ternary complex DNA-CRP-cAMP.