University of Oulu

Helene J. Bustad, Juha P. Kallio, Mikko Laitaoja, Karen Toska, Inari Kursula, Aurora Martinez, Janne Jänis, Characterization of porphobilinogen deaminase mutants reveals that arginine-173 is crucial for polypyrrole elongation mechanism, iScience, Volume 24, Issue 3, 2021, 102152, ISSN 2589-0042,

Characterization of porphobilinogen deaminase mutants reveals that arginine-173 is crucial for polypyrrole elongation mechanism

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Author: Bustad, Helene J.1; Kallio, Juha P.1; Laitaoja, Mikko2;
Organizations: 1Department of Biomedicine, University of Bergen, Jonas Lies vei 91, 5009 Bergen, Norway
2Department of Chemistry, University of Eastern Finland, 80130 Joensuu, Finland
3Norwegian Porphyria Centre (NAPOS), Department for Medical Biochemistry and Pharmacology, Haukeland University Hospital, 5021 Bergen, Norway
4Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90570 Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 4.1 MB)
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Language: English
Published: Elsevier, 2021
Publish Date: 2021-05-17


Porphobilinogen deaminase (PBGD), the third enzyme in the heme biosynthesis, catalyzes the sequential coupling of four porphobilinogen (PBG) molecules into a heme precursor. Mutations in PBGD are associated with acute intermittent porphyria (AIP), a rare metabolic disorder. We used Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to demonstrate that wild-type PBGD and AIP-associated mutant R167W both existed as holoenzymes (Eholo) covalently attached to the dipyrromethane cofactor, and three intermediate complexes, ES, ES₂, and ES₃, where S represents PBG. In contrast, only ES₂ was detected in AIP-associated mutant R173W, indicating that the formation of ES₃ is inhibited. The R173W crystal structure in the ES₂-state revealed major rearrangements of the loops around the active site, compared to wild-type PBGD in the Eholo-state. These results contribute to elucidating the structural pathogenesis of two common AIP-associated mutations and reveal the important structural role of Arg173 in the polypyrrole elongation mechanism.

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Series: iScience
ISSN: 2589-0042
ISSN-E: 2589-0042
ISSN-L: 2589-0042
Volume: 24
Issue: 3
Article number: 102152
DOI: 10.1016/j.isci.2021.102152
Type of Publication: A1 Journal article – refereed
Field of Science: 3111 Biomedicine
Funding: This work was supported by grants from the Research Council of Norway (Program Biotek2021, project 285295 to JK and AM, and Program Toppforsk, project to HJB and AM), the Western Norway Regional Health Authority (to JK, IK, and AM (project 912246 to AM)), the Norwegian Porphyria Center (to KT) and European Union's Horizon 2020 Research and Innovation Program (grant agreement no. 731077). The FT-ICR MS facility is supported by Biocenter Kuopio, Biocenter Finland (FINStruct) and European Regional Development Fund (grant A70135).
Copyright information: © 2021 The Author(s). This is an open access article under the CC BY license (