C‐terminal dimerization of apo‐cyclicAMPreceptor protein validated in solution

Abstract

Although cyclic AMP receptor protein (CRP) has long served as a typical example of effector-mediated protein allostery, mechanistic details into its regulation have been controversial due to discrepancy between the known crystal structure and NMR structure of apo-CRP. Here, we report that the recombinant protein corresponding to its C-terminal DNA-binding domain (CDD) forms a dimer. This result, together with structural information obtained in the present NMR study, is consistent with the previous crystal structure and validates its relevance also in solution. Therefore, our findings suggest that dissociation of the CDD may be critically involved in cAMP-induced allosteric activation of CRP.

Structural Basis of Dual Specificity of Sinorhizobium meliloti Clr, a cAMP and cGMP Receptor Protein

“…The latter interaction between the N 2 -amine of cGMP and T141 of the adjacent molecule is a substantial difference between Clr and the inactive cGMP complex of E. coli CAP ( 52 ). Interaction of the cAMP nucleotide with both α5 helices has been described to trigger a coil-to-helix transition in the C-terminal part of the hinge and to shift the HTH domain toward its active conformation for CAP ( 53 ). So far, cGMP appeared to be incapable of such an interaction with the second helix for promoting CRP activation ( 46 ).…”

Structural basis of bifunctionality ofSinorhizobium melilotiClr, a cAMP and cGMP receptor protein

“…The latter interaction between the N 2 -amine of cGMP and T141 of the adjacent molecule is a substantial difference between Clr and the inactive cGMP complex of E. coli CAP (50). Interaction of the cAMP nucleotide with both α5 helices has been described to trigger a coil-to-helix transition in the C- terminal part of the hinge and shift the HTH domain towards its active conformation for CAP (51). So far, cGMP appeared to be incapable of such an interaction with the second helix for promoting CRP activation (44).…”