3I54

Crystal structure of MtbCRP in complex with cAMP

Summary for 3I54

• Entry DOI: 10.2210/pdb3i54/pdb
• Related: 3I59
• Descriptor: Transcriptional regulator, Crp/Fnr family, ADENOSINE-3',5'-CYCLIC-MONOPHOSPHATE (3 entities in total)
• Functional Keywords: mycobacterium tuberculosis, camp receptor protein, allosteric mechanism, dna binding, inhibition, structural genomics, tb structural genomics consortium, tbsgc, dna-binding, transcription, transcription regulation, dna binding protein
• Biological source: Mycobacterium tuberculosis
• Total number of polymer chains: 4
• Total formula weight: 111706.00

Authors

Reddy, M.C.,Palaninathan, S.K.,Bruning, J.B.,Thurman, C.,Smith, D.,Sacchettini, J.C.,TB Structural Genomics Consortium (TBSGC) (deposition date: 2009-07-03, release date: 2009-09-08, Last modification date: 2024-02-21)

Primary citation

Reddy, M.C.,Palaninathan, S.K.,Bruning, J.B.,Thurman, C.,Smith, D.,Sacchettini, J.C.
Structural Insights into the Mechanism of the Allosteric Transitions of Mycobacterium tuberculosis cAMP Receptor Protein.
J.Biol.Chem., 284:36581-36591, 2009

PubMed Abstract: The cAMP receptor protein (CRP) from Mycobacterium tuberculosis is a cAMP-responsive global transcriptional regulator, responsible for the regulation of a multitude of diverse proteins. We have determined the crystal structures of the CRP.cAMP and CRP.N(6)-cAMP derivative-bound forms of the enzyme to 2.2- and 2.3 A-resolution, respectively, to investigate cAMP-mediated conformational and structural changes. The allosteric switch from the open, inactive conformation to the closed, active conformation begins with a number of changes in the ligand-binding cavity upon cAMP binding. These subtle structural changes and numerous non-bonding interactions between cAMP, the N-domain residues, and the C-domain helices demonstrate that the N-domain hairpin loop acts as a structural mediator of the allosteric switch. Based on the CRP.N(6)-cAMP crystal structure, binding of N(6)-cAMP with a bulkier methylphenylethyl extension from the N6 atom stabilizes the cAMP-binding domain, N-domain hairpin, and C-terminal domain in a similar manner as that of the CRP.cAMP structure, maintaining structural integrity within the subunits. However, the bulkier N6 extension of N(6)-cAMP (in R conformation) is accommodated only in subunit A with minor changes, whereas in subunit B, the N6 extension is in the S conformation hindering the hinge region of the central helix. As a result, the entire N-domain and the C-domain of subunit B integrated by the cAMP portion of this ligand, together tilt away ( approximately 7 degrees tilt) from central helix C, positioning the helix-turn-helix motif in an unfavorable position for the DNA substrate, asymmetrically. Together, these crystal structures demonstrate the mechanism of action of the cAMP molecule and its role in integrating the active CRP structure.

PubMed: 19740754
DOI: 10.1074/jbc.M109.041343

Experimental method

X-RAY DIFFRACTION (2.2 Å)