Fig. 8. Schematic model. The interaction between α-NTD and cAMP–CRP at –41 (CRP1 site) should, therefore, be important for activation of deoP2, class II CRP-dependent promoter (A). In the presence of CytR (B), the cAMP–CRP, especially that bound at the promoter-proximal site, undergoes an allosteric change such that it no longer interacts with α-NTD positively, but instead negatively. In this model, we speculate that CytR converts cAMP–CRP, especially at the promoter-proximal site, from an activator into a repressor to interfere with the RNP acting on deoP2.