1NRL

Crystal Structure of the human PXR-LBD in complex with an SRC-1 coactivator peptide and SR12813

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.216 

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Literature

Coactivator binding promotes the specific interaction between ligand and the pregnane X receptor

Watkins, R.E., Davis-Searles, P.R., Lambert, M.H., Redinbo, M.R.

(2003) J Mol Biol 331: 815-828

  • DOI: 10.1016/s0022-2836(03)00795-2
  • Primary Citation of Related Structures:  
    1NRL

  • PubMed Abstract: 

    • The pregnane X receptor (PXR) detects the presence of a wide variety of endogenous and xenobiotic compounds, and is a master regulator of the expression of genes central to drug metabolism and excretion. We present the 2.0A crystal structure of the human PXR ligand-binding domain (LBD) in complex with the cholesterol-lowering compound SR12813 and a 25 amino acid residue fragment of the human steroid receptor coactivator-1 (SRC-1) containing one LXXLL motif ...

    The pregnane X receptor (PXR) detects the presence of a wide variety of endogenous and xenobiotic compounds, and is a master regulator of the expression of genes central to drug metabolism and excretion. We present the 2.0A crystal structure of the human PXR ligand-binding domain (LBD) in complex with the cholesterol-lowering compound SR12813 and a 25 amino acid residue fragment of the human steroid receptor coactivator-1 (SRC-1) containing one LXXLL motif. PXR crystallizes as a homodimer in the asymmetric unit in this structure and possesses a novel alpha2 helix adjacent to its ligand-binding cavity. The SRC-1 peptide forms two distinct helices and binds adjacent to the ligand-dependent transactivation AF-2 helix on the surface of PXR. In contrast with previous PXR structures, in which SR12813 bound in multiple orientations, the small SR12813 agonist in this structure binds in a single, unique orientation within the receptor's ligand-binding pocket and contacts the AF-2 helix. Thermal denaturation studies reveal that the SR12813 ligand and SRC-1 coactivator peptide each stabilize the LBD of PXR, and that together they exert an additive effect on the stability of the receptor. These results indicate that the binding of coactivator to the surface of PXR limits the ability of this promiscuous receptor to "breathe" and helps to trap a single, active conformation of SR12813. They further reveal that specificity is required for PXR activation.

    Organizational Affiliation: 

    Departments of Chemistry and Biochemistry & Biophysics, and the Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Orphan nuclear receptor PXRA, B316Homo sapiensMutation(s): 0 
Gene Names: NR112 or PXR, NR1I2, PXR
UniProt & NIH Common Fund Data Resources
Find proteins for O75469 (Homo sapiens)
Explore O75469 
Go to UniProtKB:  O75469
PHAROS:  O75469
GTEx:  ENSG00000144852 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO75469
Protein Feature View
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  • Reference Sequence
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Entity ID: 2
MoleculeChainsSequence LengthOrganismDetailsImage
Nuclear Receptor Coactivator 1 isoform 3C, D25N/AMutation(s): 0 
UniProt & NIH Common Fund Data Resources
Find proteins for Q15788 (Homo sapiens)
Explore Q15788 
Go to UniProtKB:  Q15788
PHAROS:  Q15788
GTEx:  ENSG00000084676 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ15788
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SRL
Query on SRL
Download Ideal Coordinates CCD File 
E [auth A],
F [auth B]		[2-(3,5-DI-TERT-BUTYL-4-HYDROXY-PHENYL)-1-(DIETHOXY-PHOSPHORYL)-VINYL]-PHOSPHONIC ACID DIETHLYL ESTER
C24 H42 O7 P2
YQLJDECYQDRSBI-UHFFFAOYSA-N		 Ligand Interaction
Binding Affinity Annotations 
IDSourceBinding Affinity
SRL BindingDB:  1NRL EC50: min: 60, max: 440 (nM) from 3 assay(s)
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.216 
  • R-Value Observed: 0.216 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 85.097α = 90
b = 89.478β = 90
c = 106.665γ = 90
Software Package:
Software NamePurpose
CNSrefinement
HKL-2000data reduction
SCALEPACKdata scaling
AMoREphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-08-19
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance