1HW5

THE CAP/CRP VARIANT T127L/S128A


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.82 Å
  • R-Value Free: 0.300 
  • R-Value Work: 0.227 
  • R-Value Observed: 0.228 

Starting Model: experimental
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This is version 1.5 of the entry. See complete history


Literature

The structure of the T127L/S128A mutant of cAMP receptor protein facilitates promoter site binding

Chu, S.Y.Tordova, M.Gilliland, G.L.Gorshkova, I.Shi, Y.Wang, S.Schwarz, F.P.

(2001) J Biol Chem 276: 11230-11236

  • DOI: https://doi.org/10.1074/jbc.M010428200
  • Primary Citation of Related Structures:  
    1HW5

  • PubMed Abstract: 

    The x-ray crystal structure of the cAMP-ligated T127L/S128A double mutant of cAMP receptor protein (CRP) was determined to a resolution of 2.2 A. Although this structure is close to that of the x-ray crystal structure of cAMP-ligated CRP with one subunit in the open form and one subunit in the closed form, a bound syn-cAMP is clearly observed in the closed subunit in a third binding site in the C-terminal domain. In addition, water-mediated interactions replace the hydrogen bonding interactions between the N(6) of anti-cAMP bound in the N-terminal domains of each subunit and the OH groups of the Thr(127) and Ser(128) residues in the C alpha-helix of wild type CRP. This replacement induces flexibility in the C alpha-helix at Ala(128), which swings the C-terminal domain of the open subunit more toward the N-terminal domain in the T127L/S128A double mutant of CRP (CRP*) than is observed in the open subunit of cAMP-ligated CRP. Isothermal titration calorimetry measurements on the binding of cAMP to CRP* show that the binding mechanism changes from an exothermic independent two-site binding mechanism at pH 7.0 to an endothermic interacting two-site mechanism at pH 5.2, similar to that observed for CRP at both pH levels. Differential scanning calorimetry measurements exhibit a broadening of the thermal denaturation transition of CRP* relative to that of CRP at pH 7.0 but similar to the multipeak transitions observed for cAMP-ligated CRP. These properties and the bound syn-cAMP ligand, which has only been previously observed in the DNA bound x-ray crystal structure of cAMP-ligated CRP by Passner and Steitz (Passner, J. M., and Steitz, T. A. (1997) Proc. Natl. Acad. Sci. U. S. A. 94, 2843-2847), imply that the cAMP-ligated CRP* structure is closer to the conformation of the allosterically activated structure than cAMP-ligated CRP. This may be induced by the unique flexibility at Ala(128) and/or by the bound syn-cAMP in the hinge region of CRP*.


  • Organizational Affiliation

    Center for Advanced Research in Biotechnology of the National Institute of Standards and Technology and the University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
CATABOLITE GENE ACTIVATOR
A, B
210Escherichia coliMutation(s): 2 
Gene Names: CRP/CAP
UniProt
Find proteins for P0ACJ8 (Escherichia coli (strain K12))
Explore P0ACJ8 
Go to UniProtKB:  P0ACJ8
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0ACJ8
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.82 Å
  • R-Value Free: 0.300 
  • R-Value Work: 0.227 
  • R-Value Observed: 0.228 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 46.1α = 90
b = 93.1β = 90
c = 104.4γ = 90
Software Package:
Software NamePurpose
X-GENdata scaling
X-GENdata reduction
AMoREphasing
SHELXL-97refinement

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2001-01-17
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-10-04
    Changes: Refinement description
  • Version 1.4: 2021-10-27
    Changes: Database references, Derived calculations
  • Version 1.5: 2023-08-09
    Changes: Data collection, Refinement description