3I9T

Crystal structure of the rat heme oxygenase (HO-1) in complex with heme binding dithiothreitol (DTT)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.162 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Dioxygen activation for the self-degradation of heme: reaction mechanism and regulation of heme oxygenase.

Matsui, T.Iwasaki, M.Sugiyama, R.Unno, M.Ikeda-Saito, M.

(2010) Inorg.Chem. 49: 3602-3609

  • DOI: 10.1021/ic901869t
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Heme oxygenase (HO) catalyzes the regiospecific conversion of heme to biliverdin, CO, and free iron through three successive oxygenation reactions. HO catalysis is unique in that all three O(2) activations are performed by the substrate itself. This ...

    Heme oxygenase (HO) catalyzes the regiospecific conversion of heme to biliverdin, CO, and free iron through three successive oxygenation reactions. HO catalysis is unique in that all three O(2) activations are performed by the substrate itself. This Forum Article overviews our current understanding on the structural and biochemical properties of HO catalysis, especially its first and third oxygenation steps. The HO first step, regiospecific hydroxylation of the porphyrin alpha-meso-carbon atom, is of particular interest because of its sharp contrast to O(2) activation by cytochrome P450. HO was proposed to utilize the FeOOH species but not conventional ferryl hemes as a reactive intermediate for self-hydroxylation. We have succeeded in preparing and characterizing the FeOOH species of HO at low temperature, and our analyses of its reaction, together with mutational and crystallographic studies, reveal that protonation of FeOOH by a distal water molecule is critical in promoting the unique self-hydroxylation. The second oxygenation is a rapid, spontaneous autooxidation of the reactive alpha-meso-hydroxyheme in which the HO enzyme does not play a critical role. Further O(2) activation by verdoheme cleaves its porphyrin macrocycle to form biliverdin and free ferrous iron. This third step has been considered to be a major rate-determining step of HO catalysis to regulate the enzyme activity. Our reaction analysis strongly supports the FeOOH verdoheme as the key intermediate of the ring-opening reaction. This mechanism is very similar to that of the first meso-hydroxylation, and the distal water is suggested to enhance the third step as expected from the similarity. The HO mechanistic studies highlight the catalytic importance of the distal hydrogen-bonding network, and this manuscript also involves our attempts to develop HO inhibitors targeting the unique distal structure.


    Organizational Affiliation

    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba, Sendai 980-8577, Japan. matsui@tagen.tohoku.ac.jp




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Heme oxygenase 1
A
263Rattus norvegicusMutation(s): 0 
Gene Names: Hmox1
EC: 1.14.14.18
Find proteins for P06762 (Rattus norvegicus)
Go to UniProtKB:  P06762
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
DTV
Query on DTV

Download SDF File 
Download CCD File 
A
(2S,3S)-1,4-DIMERCAPTOBUTANE-2,3-DIOL
C4 H10 O2 S2
VHJLVAABSRFDPM-QWWZWVQMSA-N
 Ligand Interaction
HEM
Query on HEM

Download SDF File 
Download CCD File 
A
PROTOPORPHYRIN IX CONTAINING FE
HEME
C34 H32 Fe N4 O4
KABFMIBPWCXCRK-RGGAHWMASA-L
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.15 Å
  • R-Value Free: 0.209 
  • R-Value Work: 0.162 
  • Space Group: P 32 2 1
Unit Cell:
Length (Å)Angle (°)
a = 65.739α = 90.00
b = 65.739β = 90.00
c = 120.663γ = 120.00
Software Package:
Software NamePurpose
CNSrefinement
HKL-2000data scaling
HKL-2000data reduction
CNSphasing
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2010-05-19
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance