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Publication Abstract from PubMed

Terpene cyclases (TCs), consisting of various combinations of alpha, beta, and gamma domains, have been extensively studied. Recently, non-canonical enzymes comprising a TCbeta domain and a haloacid dehalogenase (HAD)-like domain (referred to as HAD-TCbeta) have been discovered. However, their overall structure remains unclear. In this study, we determined the co-crystal structures of drimenol synthase from Aquimarina spongiae (AsDMS), which catalyzes the conversion of farnesyl pyrophosphate (1) into drimenol (2). Crystallographic analyses of the enzyme bound to substrates 1 and drimenyl monophosphate (3) demonstrated that the TCbeta domain catalyzes a class II cyclization reaction initiated by protonation, whereas the HAD domain catalyzes a phosphatase-like dephosphorylation reaction dependent on a divalent metal. Crystallographic and gel filtration analyses revealed that AsDMS adopts a dimeric assembly. This dimerization positioned the TCbeta and HAD domains to facilitate efficient substrate transfer via electrostatic substrate channeling. Furthermore, to investigate the structure-function relationship of the AsDMS TCbeta domain, we used AlphaFold2 to model the structure of the fungal albicanol (4) synthase. Comparative analysis of active-site residues between AsDMS and fungal 4-synthase enabled rational protein engineering, converting AsDMS activity from 2-synthase to 4-synthase. This study provides insights into the biosynthesis of valuable drimane-type sesquiterpenes via targeted mutagenesis.

Structural insights into a bacterial terpene cyclase fused with haloacid Dehalogenase-like phosphatase.,Fujiyama K, Takagi H, Vo NNQ, Morita N, Nogawa T, Takahashi S Chem Sci. 2025 Jul 28;16(34):15310-15319. doi: 10.1039/d5sc04719f. eCollection , 2025 Aug 27. PMID:40852458^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.