Structure of Rhodococcus erythropolis limonene-1,2-epoxide hydrolase reveals a novel active site

Epoxide hydrolases are essential for the processing of epoxide‐containing compounds in detoxification or metabolism. The classic epoxide hydrolases have an α/β hydrolase fold and act via a two‐step reaction mechanism including an enzyme–substrate intermediate. We report here the structure of the lim...

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Bibliographic Details
Published in:	The EMBO journal 2003-06, Vol.22 (11), p.2583-2592
Main Authors:	Mowbray, Sherry L, Arand, Michael, Hallberg, B.Martin, Zou, Jinyu, Bergfors, Terese, Oesch, Franz, van der Werf, Mariët J, de Bont, Jan A.M, Jones, T.Alwyn
Format:	Article
Language:	eng
Subjects:	agrobacterium-radiobacter Amino Acid Sequence aspergillus-niger Bacterial Proteins Catalytic Domain cholesterol epoxide hydrolase crystal structure Crystallography, X-Ray dcl14 delta-3-ketosteroid isomerase Dimerization enantioselectivity enzyme epoxide hydrolase Epoxide Hydrolases - chemistry Epoxide Hydrolases - genetics Epoxide Hydrolases - metabolism Epoxide Hydrolases/chemistry/genetics/metabolism macromolecular structures mechanism Models, Molecular Molecular Sequence Data monoterpene degradation Mutagenesis, Site-Directed naphthalene 1,2-dioxygenase protein data-bank Protein Subunits Recombinant Proteins - chemistry Recombinant Proteins - genetics Recombinant Proteins - metabolism Recombinant Proteins/chemistry/genetics/metabolism Rhodococcus - enzymology Rhodococcus - genetics Rhodococcus/enzymology/genetics Sequence Homology, Amino Acid
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Summary:	Epoxide hydrolases are essential for the processing of epoxide‐containing compounds in detoxification or metabolism. The classic epoxide hydrolases have an α/β hydrolase fold and act via a two‐step reaction mechanism including an enzyme–substrate intermediate. We report here the structure of the limonene‐1,2‐epoxide hydrolase from Rhodococcus erythropolis, solved using single‐wavelength anomalous dispersion from a selenomethionine‐substituted protein and refined at 1.2 Å resolution. This enzyme represents a completely different structure and a novel one‐step mechanism. The fold features a highly curved six‐stranded mixed β‐sheet, with four α‐helices packed onto it to create a deep pocket. Although most residues lining this pocket are hydrophobic, a cluster of polar groups, including an Asp–Arg–Asp triad, interact at its deepest point. Site‐directed mutagenesis supports the conclusion that this is the active site. Further, a 1.7 Å resolution structure shows the inhibitor valpromide bound at this position, with its polar atoms interacting directly with the residues of the triad. We suggest that several bacterial proteins of currently unknown function will share this structure and, in some cases, catalytic properties.
ISSN:	0261-4189 1460-2075 1460-2075