Discovery and characterization of thermophilic limonene-1,2-epoxide hydrolases from hot spring metagenomic libraries

Erica Elisa Ferrandi, Christopher Sayer, Michail N. Isupov, Celeste Annovazzi, Carlotta Marchesi, Gianluca Iacobone, Xu Peng, Elizaveta Bonch-Osmolovskaya, Roland Wohlgemuth, Jennifer A. Littlechild, Daniela Monti

25 Citations (Scopus)

Abstract

The epoxide hydrolases (EHs) represent an attractive option for the synthesis of chiral epoxides and 1,2-diols which are valuable building blocks for the synthesis of several pharmaceutical compounds. A metagenomic approach has been used to identify two new members of the atypical EH limonene-1,2-epoxide hydrolase (LEH) family of enzymes. These two LEHs (Tomsk-LEH and CH55-LEH) show EH activities towards different epoxide substrates, differing in most cases from those previously identified for Rhodococcus erythropolis (Re-LEH) in terms of stereoselectivity. Tomsk-LEH and CH55-LEH, both from thermophilic sources, have higher optimal temperatures and apparent melting temperatures than Re-LEH. The new LEH enzymes have been crystallized and their structures solved to high resolution in the native form and in complex with the inhibitor valpromide for Tomsk-LEH and poly(ethylene glycol) for CH55-LEH. The structural analysis has provided insights into the LEH mechanism, substrate specificity and stereoselectivity of these new LEH enzymes, which has been supported by mutagenesis studies. Database The atomic coordinates and structure factors of the crystal structures have been deposited in the Protein Data Bank with the codes 5AIF (Tomsk-LEH native structure), 5AIG (Tomsk-LEH valpromide complex), 5AIH (CH55-LEH native structure) and 5AII (CH55-LEH PEG complex). Nucleotide sequence data are available in the GenBank databases under the accession numbers KP765711 (Tomsk-LEH) and KP765710 (CH55-LEH). Two limonene epoxide hydrolases have been identified from thermophilic metagenomes and were cloned, over-expressed and characterised. The new enzymes have activity towards epoxide substrates which differs from the related Rhodococcus enzyme. The high resolution X-ray structures of the native and inhibitor complexes provide insights into the catalytic mechanism, substrate specificity and stereoselectivity observed which have been supported by mutagenesis studies.

Original languageEnglish
JournalF E B S Journal
Volume282
Issue number15
Pages (from-to)2879-2894
Number of pages16
ISSN1742-464X
DOIs
Publication statusPublished - 1 Aug 2015

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