2O99

The crystal structure of E.coli IclR C-terminal fragment in complex with glyoxylate


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.204 
  • R-Value Observed: 0.207 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Glyoxylate and Pyruvate Are Antagonistic Effectors of the Escherichia coli IclR Transcriptional Regulator.

Lorca, G.L.Ezersky, A.Lunin, V.V.Walker, J.R.Altamentova, S.Evdokimova, E.Vedadi, M.Bochkarev, A.Savchenko, A.

(2007) J Biol Chem 282: 16476-16491

  • DOI: 10.1074/jbc.M610838200
  • Primary Citation of Related Structures:  
    2O99, 2O9A

  • PubMed Abstract: 
  • The Escherichia coli isocitrate lyase regulator (IclR) regulates the expression of the glyoxylate bypass operon (aceBAK). Founding member of a large family of common fold transcriptional regulators, IclR comprises a DNA binding domain that interacts with the operator sequence and a C-terminal domain (C-IclR) that binds a hitherto unknown small molecule ...

    The Escherichia coli isocitrate lyase regulator (IclR) regulates the expression of the glyoxylate bypass operon (aceBAK). Founding member of a large family of common fold transcriptional regulators, IclR comprises a DNA binding domain that interacts with the operator sequence and a C-terminal domain (C-IclR) that binds a hitherto unknown small molecule. We screened a chemical library of more than 150 metabolic scaffolds using a high-throughput protein stability assay to identify molecules that bind IclR and then tested the active compounds in in vitro assays of operator binding. Glyoxylate and pyruvate, identified by this method, bound the C-IclR domain with KD values of 0.9+/-0.2 and 156.2+/-7.9 microM, as defined by isothermal titration calorimetry. Both compounds altered IclR interactions with operator DNA in electrophoretic mobility shift assays but showed an antagonistic effect. Glyoxylate disrupted the formation of the IclR/operator complex in vitro by favoring the inactive dimeric state of the protein, whereas pyruvate increased the binding of IclR to the aceBAK promoter by stabilizing the active tetrameric form of the protein. Structures of the C-IclR domain alone and in complex with each effector were determined at 2.3 A, confirming the binding of both molecules in the effector recognition site previously characterized for the other representative of the family, the E. coli AllR regulator. Site-directed mutagenesis demonstrated the importance of hydrophobic patch formed by Met-146, Leu-154, Leu-220, and Leu-143 in interactions with effector molecules. In general, our strategy of combining chemical screens with functional assays and structural studies has uncovered two small molecules with antagonistic effects that regulate the IclR-dependent transcription of the aceBAK operon.


    Organizational Affiliation

    Banting and Best Department of Medical Research, Toronto, Ontario M5G 1L6, Canada. glorca@ufl.edu



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Acetate operon repressorA, B, C, D182Escherichia coliMutation(s): 7 
UniProt
Find proteins for P16528 (Escherichia coli (strain K12))
Explore P16528 
Go to UniProtKB:  P16528
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP16528
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
MSE
Query on MSE
A, B, C, D L-PEPTIDE LINKINGC5 H11 N O2 SeMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.70 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.204 
  • R-Value Observed: 0.207 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 53.538α = 90
b = 81.483β = 90
c = 154.693γ = 90
Software Package:
Software NamePurpose
d*TREKdata scaling
MOLREPphasing
REFMACrefinement
PDB_EXTRACTdata extraction
CrystalCleardata collection
d*TREKdata reduction

Structure Validation

View Full Validation Report




Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-04-10
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance