title: Crystal structures of human 3-hydroxyanthranilate 3,4-dioxygenase with native and non-native metals bound in the active site.
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 O2to 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.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Lakshmi Swarna Mukhi
authors.initials: LS
authors.lastname: Pidugu
authors.affiliation: Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Neu
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Tin Lok
authors.initials: TL
authors.lastname: Wong
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Edwin
authors.initials: E
authors.lastname: Pozharski
authors.affiliation: Chemical Sciences Division, National Institute of Standards and Technology, 100 Bureau Drive, Stop 8391, Gaithersburg, MD 20899-8391, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Molloy
authors.affiliation: Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore, MD 21201, USA.
authors.forename: Sarah L J
authors.initials: SL
authors.lastname: Michel
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
authors.forename: Eric A
authors.initials: EA
authors.lastname: Toth
mesh_terms: D050561:3-Hydroxyanthranilate 3,4-Dioxygenase / Q000737:chemistry* / Q000378:metabolism; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D006801:Humans; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D009532:Nickel / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D015032:Zinc / Q000737:chemistry / Q000378:metabolism
chemical_list: D009532:Nickel; D007501:Iron; D050561:3-Hydroxyanthranilate 3,4-Dioxygenase; D015032:Zinc
keywords: 3-hydroxyanthranilate 3,4-dioxygenase; kynurenine pathway; neurodegeneration; oxidoreductase; quinolinic acid