Cyclic di-GMP Allosterically Inhibits the CRP-Like Protein (Clp) of Xanthomonas axonopodis pv. citri

The protein Clp from Xanthomonas axonopodis pv. citri regulates pathogenesis and is a member of the CRP (cyclic AMP receptor protein) superfamily. We show that unlike the DNA-binding activity of other members of this family, the DNA-binding activity of Clp is allosterically inhibited by its effector and that cyclic di-GMP serves as that effector at physiological concentrations.