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Crystal structure and catalytic characterization of the dehydrogenase/reductase SDR family member 4 ( DHRS 4) from Caenorhabditis elegans
Author(s) -
Kisiela Michael,
Faust Annette,
Ebert Bettina,
Maser Edmund,
Scheidig Axel J.
Publication year - 2018
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/febs.14337
Subject(s) - caenorhabditis elegans , chemistry , biochemistry , thermostability , stereochemistry , protein family , enzyme , biology , gene
The human dehydrogenase/reductase SDR family member 4 ( DHRS 4) is a tetrameric protein that is involved in the metabolism of several aromatic carbonyl compounds, steroids, and bile acids. The only invertebrate DHRS 4 that has been characterized to date is that from the model organism Caenorhabditis elegans . We have previously cloned and initially characterized this protein that was recently annotated as DHRS 4_ CAEEL in the UniProtKB database. Crystallization and X‐ray diffraction studies of the full‐length DHRS 4_ CAEEL protein in complex with diacetyl revealed its tetrameric structure and showed that two subunits are connected via an intermolecular disulfide bridge that is formed by N‐terminal cysteine residues (Cys5) of each protein chain, which increases the enzymatic activity. A more detailed biochemical and catalytic characterization shows that DHRS 4_ CAEEL shares some properties with human DHRS 4 such as relatively low substrate affinities with aliphatic α‐diketones and a preference for aromatic dicarbonyls such as isatin, with a 30‐fold lower Km value compared with the human enzyme. Moreover, DHRS 4_ CAEEL is active with aliphatic aldehydes (e.g. hexanal), while human DHRS 4 is not. Dehydrogenase activity with alcohols was only observed with aromatic alcohols. Protein thermal shift assay revealed a stabilizing effect of phosphate buffer that was accompanied by an increase in catalytic activity of more than two‐fold. The study of DHRS 4 homologs in simple lineages such as C. elegans may contribute to our understanding of the original function of this protein that has been shaped by evolutionary processes in the course of the development from invertebrates to higher mammalian species. Database Structural data are available in the PDB under the accession numbers 5OJG and 5OJI .