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 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.216 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history. 

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


  • 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 h ...

    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

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Orphan nuclear receptor PXR
A, B
316Homo sapiensMutation(s): 0 
Gene Names: NR1I2 (PXR)
Find proteins for O75469 (Homo sapiens)
Go to Gene View: NR1I2
Go to UniProtKB:  O75469
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Nuclear Receptor Coactivator 1 isoform 3
C, D
25Homo sapiensMutation(s): 0 
Gene Names: NCOA1 (BHLHE74, SRC1)
EC: 2.3.1.48
Find proteins for Q15788 (Homo sapiens)
Go to Gene View: NCOA1
Go to UniProtKB:  Q15788
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SRL
Query on SRL
Download SDF File 
Download CCD File 
A, B
[2-(3,5-DI-TERT-BUTYL-4-HYDROXY-PHENYL)-1-(DIETHOXY-PHOSPHORYL)-VINYL]-PHOSPHONIC ACID DIETHLYL ESTER
SR12813
C24 H42 O7 P2
YQLJDECYQDRSBI-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.216 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 85.097α = 90.00
b = 89.478β = 90.00
c = 106.665γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling
AMoREphasing
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots


View more in-depth experimental data

Entry History 

Deposition Data

Revision History 

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