Crystal structure of MtbCRP in complex with cAMP

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.213 

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Structural Insights into the Mechanism of the Allosteric Transitions of Mycobacterium tuberculosis cAMP Receptor Protein.

Reddy, M.C.Palaninathan, S.K.Bruning, J.B.Thurman, C.Smith, D.Sacchettini, J.C.

(2009) J Biol Chem 284: 36581-36591

  • DOI: https://doi.org/10.1074/jbc.M109.041343
  • Primary Citation of Related Structures:  
    3I54, 3I59

  • 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.

  • Organizational Affiliation

    Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Transcriptional regulator, Crp/Fnr family
A, B, C, D
249Mycobacterium tuberculosisMutation(s): 0 
Gene Names: MT3777Rv3676
Find proteins for P9WMH3 (Mycobacterium tuberculosis (strain ATCC 25618 / H37Rv))
Explore P9WMH3 
Go to UniProtKB:  P9WMH3
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP9WMH3
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.211 
  • R-Value Observed: 0.213 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 68.252α = 90
b = 96.335β = 113.46
c = 79.255γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PDB_EXTRACTdata extraction
HKL-2000data collection
HKL-2000data reduction

Structure Validation

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Ligand Structure Quality Assessment 

Entry History 

Revision History  (Full details and data files)

  • Version 1.0: 2009-09-08
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Advisory, Version format compliance
  • Version 1.2: 2017-11-01
    Changes: Refinement description
  • Version 1.3: 2024-02-21
    Changes: Data collection, Database references, Derived calculations