2D0T

Crystal structure of 4-phenylimidazole bound form of human indoleamine 2,3-dioxygenase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.221 
  • R-Value Work: 0.191 
  • R-Value Observed: 0.242 

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This is version 1.2 of the entry. See complete history


Literature

Crystal structure of human indoleamine 2,3-dioxygenase: catalytic mechanism of O2 incorporation by a heme-containing dioxygenase.

Sugimoto, H.Oda, S.Otsuki, T.Hino, T.Yoshida, T.Shiro, Y.

(2006) Proc Natl Acad Sci U S A 103: 2611-2616

  • DOI: 10.1073/pnas.0508996103
  • Primary Citation of Related Structures:  
    2D0U, 2D0T

  • PubMed Abstract: 
  • Human indoleamine 2,3-dioxygenase (IDO) catalyzes the cleavage of the pyrrol ring of L-Trp and incorporates both atoms of a molecule of oxygen (O2). Here we report on the x-ray crystal structure of human IDO, complexed with the ligand inhibitor 4-phe ...

    Human indoleamine 2,3-dioxygenase (IDO) catalyzes the cleavage of the pyrrol ring of L-Trp and incorporates both atoms of a molecule of oxygen (O2). Here we report on the x-ray crystal structure of human IDO, complexed with the ligand inhibitor 4-phenylimidazole and cyanide. The overall structure of IDO shows two alpha-helical domains with the heme between them. A264 of the flexible loop in the heme distal side is in close proximity to the iron. A mutant analysis shows that none of the polar amino acid residues in the distal heme pocket are essential for activity, suggesting that, unlike the heme-containing monooxygenases (i.e., peroxidase and cytochrome P450), no protein group of IDO is essential in dioxygen activation or proton abstraction. These characteristics of the IDO structure provide support for a reaction mechanism involving the abstraction of a proton from the substrate by iron-bound dioxygen. Inactive mutants (F226A, F227A, and R231A) retain substrate-binding affinity, and an electron density map reveals that 2-(N-cyclohexylamino)ethane sulfonic acid is bound to these residues, mimicking the substrate. These findings suggest that strict shape complementarities between the indole ring of the substrate and the protein side chains are required, not for binding, but, rather, to permit the interaction between the substrate and iron-bound dioxygen in the first step of the reaction. This study provides the structural basis for a heme-containing dioxygenase mechanism, a missing piece in our understanding of heme chemistry.


    Organizational Affiliation

    Biometal Science Laboratory, RIKEN SPring-8 Center, Harima Institute, Hyogo 679-5148, Japan.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Indoleamine 2,3-dioxygenaseAB406Homo sapiensMutation(s): 0 
Gene Names: IDO1IDOINDO
EC: 1.13.11.42 (PDB Primary Data), 1.13.11.52 (UniProt)
Find proteins for P14902 (Homo sapiens)
Explore P14902 
Go to UniProtKB:  P14902
NIH Common Fund Data Resources
PHAROS  P14902
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
HEM
Query on HEM

Download CCD File 
A, B
PROTOPORPHYRIN IX CONTAINING FE
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
NHE
Query on NHE

Download CCD File 
A, B
2-[N-CYCLOHEXYLAMINO]ETHANE SULFONIC ACID
C8 H17 N O3 S
MKWKNSIESPFAQN-UHFFFAOYSA-N
 Ligand Interaction
PIM
Query on PIM

Download CCD File 
A, B
4-PHENYL-1H-IMIDAZOLE
C9 H8 N2
XHLKOHSAWQPOFO-UHFFFAOYSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
231IC50:  31000   nM  BindingDB
231IC50:  70300   nM  BindingDB
231IC50:  38000   nM  BindingDB
PIMIC50:  48000   nM  BindingDB
231IC50:  42000   nM  BindingDB
231IC50:  48000   nM  BindingDB
231IC50:  428000   nM  BindingDB
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.30 Å
  • R-Value Free: 0.221 
  • R-Value Work: 0.191 
  • R-Value Observed: 0.242 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 86.07α = 90
b = 98.027β = 90
c = 130.951γ = 90
Software Package:
Software NamePurpose
CNSrefinement
HKL-2000data reduction
SCALEPACKdata scaling
SHARPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-01-31
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance