Crystal Structures of the Ferric, Ferrous, and Ferrous-NO Forms of the Asp140Ala Mutant of Human Heme Oxygenase-1:Catalytic Implications

Experimental Data Snapshot

  • Resolution: 2.19 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.209 

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Crystal structures of the ferric, ferrous, and ferrous-NO forms of the Asp140Ala mutant of human heme oxygenase-1: catalytic implications

Lad, L.Wang, J.Li, H.Friedman, J.Bhaskar, B.Ortiz de Montellano, P.R.Poulos, T.L.

(2003) J Mol Biol 330: 527-538

  • DOI: https://doi.org/10.1016/s0022-2836(03)00578-3
  • Primary Citation of Related Structures:  
    1OYK, 1OYL, 1OZE, 1OZL, 1OZR, 1OZW

  • PubMed Abstract: 

    Site-directed mutagenesis studies have shown that Asp140 in both human and rat heme oxygenase-1 is critical for enzyme activity. Here, we report the D140A mutant crystal structure in the Fe(III) and Fe(II) redox states as well as the Fe(II)-NO complex as a model for the Fe(II)-oxy complex. These structures are compared to the corresponding wild-type structures. The mutant and wild-type structures are very similar, except for the distal heme pocket solvent structure. In the Fe(III) D140A mutant one water molecule takes the place of the missing Asp140 carboxylate side-chain and a second water molecule, novel to the mutant, binds in the distal pocket. Upon reduction to the Fe(II) state, the distal helix running along one face of the heme moves closer to the heme in both the wild-type and mutant structures thus tightening the active site. NO binds to both the wild-type and mutant in a bent conformation that orients the NO O atom toward the alpha-meso heme carbon atom. A network of water molecules provides a H-bonded network to the NO ligand, suggesting a possible proton shuttle pathway required to activate dioxygen for catalysis. In the wild-type structure, Asp140 exhibits two conformations, suggesting a dynamic role for Asp140 in shuttling protons from bulk solvent via the water network to the iron-linked oxy complex. On the basis of these structures, we consider why the D140A mutant is inactive as a heme oxygenase but active as a peroxidase.

  • Organizational Affiliation

    Department of Molecular Biology and Biochemistry, University of California at Irvine, Irvine, CA 92697-3900, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Heme oxygenase 1
A, B
233Homo sapiensMutation(s): 1 
Gene Names: HMOX1
UniProt & NIH Common Fund Data Resources
Find proteins for P09601 (Homo sapiens)
Explore P09601 
Go to UniProtKB:  P09601
PHAROS:  P09601
GTEx:  ENSG00000100292 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP09601
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on HEM

Download Ideal Coordinates CCD File 
C [auth A],
D [auth B]
C34 H32 Fe N4 O4
Experimental Data & Validation

Experimental Data

  • Resolution: 2.19 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.209 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 61.662α = 90
b = 54.368β = 99.82
c = 71.748γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
SCALEPACKdata scaling
HKL-2000data reduction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-08-05
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-10-27
    Changes: Database references, Derived calculations
  • Version 1.4: 2023-08-16
    Changes: Data collection, Refinement description