Crystal structure of human 3HAO with iron bound in the active site

Experimental Data Snapshot

  • Resolution: 1.88 Å
  • R-Value Free: 0.218 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.203 

Starting Model: experimental
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Crystal structures of human 3-hydroxyanthranilate 3,4-dioxygenase with native and non-native metals bound in the active site.

Pidugu, L.S.Neu, H.Wong, T.L.Pozharski, E.Molloy, J.L.Michel, S.L.Toth, E.A.

(2017) Acta Crystallogr D Struct Biol 73: 340-348

  • DOI: https://doi.org/10.1107/S2059798317002029
  • Primary Citation of Related Structures:  
    5TK5, 5TKQ

  • PubMed Abstract: 

    3-Hydroxyanthranilate 3,4-dioxygenase (3HAO) is an enzyme in the microglial branch of the kynurenine pathway of tryptophan degradation. 3HAO is a non-heme iron-containing, ring-cleaving extradiol dioxygenase that catalyzes the addition of both atoms of O 2 to the kynurenine pathway metabolite 3-hydroxyanthranilic acid (3-HANA) to form quinolinic acid (QUIN). QUIN is a highly potent excitotoxin that has been implicated in a number of neurodegenerative conditions, making 3HAO a target for pharmacological downregulation. Here, the first crystal structure of human 3HAO with the native iron bound in its active site is presented, together with an additional structure with zinc (a known inhibitor of human 3HAO) bound in the active site. The metal-binding environment is examined both structurally and via inductively coupled plasma mass spectrometry (ICP-MS), X-ray fluorescence spectroscopy (XRF) and electron paramagnetic resonance spectroscopy (EPR). The studies identified Met35 as the source of potential new interactions with substrates and inhibitors, which may prove useful in future therapeutic efforts.

  • Organizational Affiliation

    Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
3-hydroxyanthranilate 3,4-dioxygenase290Homo sapiensMutation(s): 0 
Gene Names: HAAO
UniProt & NIH Common Fund Data Resources
Find proteins for P46952 (Homo sapiens)
Explore P46952 
Go to UniProtKB:  P46952
PHAROS:  P46952
GTEx:  ENSG00000162882 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP46952
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.88 Å
  • R-Value Free: 0.218 
  • R-Value Work: 0.203 
  • R-Value Observed: 0.203 
  • Space Group: P 65 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 57.076α = 90
b = 57.076β = 90
c = 415.871γ = 120
Software Package:
Software NamePurpose
XDSdata reduction
Aimlessdata scaling

Structure Validation

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Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
National Science Foundation (NSF, United States)United StatesCHE1306208

Revision History  (Full details and data files)

  • Version 1.0: 2017-04-12
    Type: Initial release
  • Version 1.1: 2017-09-27
    Changes: Author supporting evidence
  • Version 1.2: 2018-04-18
    Changes: Data collection, Database references
  • Version 1.3: 2019-11-27
    Changes: Author supporting evidence, Derived calculations
  • Version 1.4: 2023-10-04
    Changes: Data collection, Database references, Refinement description