University of Oulu

Tiila-Riikka Kiema, Chandan J. Thapa, Mikko Laitaoja, Werner Schmitz, Mirko M. Maksimainen, Toshiyuki Fukao, Juha Rouvinen, Janne Jänis, Rik K. Wierenga (2019) The peroxisomal zebrafish SCP2-thiolase (type-1) is a weak transient dimer as revealed by crystal structures and native mass spectrometry. Biochemical Journal Jan 2019, 476 (2) 307-332; DOI: 10.1042/BCJ20180788

The peroxisomal zebrafish SCP2-thiolase (type-1) is a weak transient dimer as revealed by crystal structures and native mass spectrometry

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Author: Kiema, Tiila-Riikka1; Thapa, Chandan J.1; Laitaoja, Mikko2;
Organizations: 1Biocenter Oulu and Faculty of Biochemistry and Molecular Medicine, University of Oulu, PO Box 5400, FI-90014 Oulu, Finland
2Department of Chemistry, University of Eastern Finland, PO Box 111, 80101 Joensuu, Finland
3Theodor Boveri Institute of Biosciences (Biocenter), University of Würzburg, Am Hubland, D-97074 Würzburg, German
4Department of Pediatrics, Graduate School of Medicine, Gifu University, Yanagido 1-1, Gifu 501-1194, Japan
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 14.1 MB)
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Language: English
Published: Portland Press, 2019
Publish Date: 2020-01-25


The SCP2 (sterol carrier protein 2)-thiolase (type-1) functions in the vertebrate peroxisomal, bile acid synthesis pathway, converting 24-keto-THC-CoA and CoA into choloyl-CoA and propionyl-CoA. This conversion concerns the β-oxidation chain shortening of the steroid fatty acyl-moiety of 24-keto-THC-CoA. This class of dimeric thiolases has previously been poorly characterized. High-resolution crystal structures of the zebrafish SCP2-thiolase (type-1) now reveal an open catalytic site, shaped by residues of both subunits. The structure of its non-dimerized monomeric form has also been captured in the obtained crystals. Four loops at the dimer interface adopt very different conformations in the monomeric form. These loops also shape the active site and their structural changes explain why a competent active site is not present in the monomeric form. Native mass spectrometry studies confirm that the zebrafish SCP2-thiolase (type-1) as well as its human homolog are weak transient dimers in solution. The crystallographic binding studies reveal the mode of binding of CoA and octanoyl-CoA in the active site, highlighting the conserved geometry of the nucleophilic cysteine, the catalytic acid/base cysteine and the two oxyanion holes. The dimer interface of SCP2-thiolase (type-1) is equally extensive as in other thiolase dimers; however, it is more polar than any of the corresponding interfaces, which correlates with the notion that the enzyme forms a weak transient dimer. The structure comparison of the monomeric and dimeric forms suggests functional relevance of this property. These comparisons provide also insights into the structural rearrangements that occur when the folded inactive monomers assemble into the mature dimer.

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Series: Biochemical journal
ISSN: 0264-6021
ISSN-E: 1470-8728
ISSN-L: 0264-6021
Volume: 476
Issue: 2
Pages: 307 - 332
DOI: 10.1042/BCJ20180788
Type of Publication: A1 Journal article – refereed
Field of Science: 1182 Biochemistry, cell and molecular biology
Funding: The FT-ICR MS facility of the University of Eastern Finland is also supported by the European Regional Development Fund (grant no. A70135) and EU's Horizon 2020 Research and Innovation Program (grant no. 731077).
Dataset Reference: Supplementary Material Available at
Copyright information: © 2019 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.