Nucleophilic water capture or proton loss: single amino acid switch converts δ-Cadinene synthase into germacradien-4-ol synthase

Loizzi, Marianna, Gonzalez Gonzalez, Veronica, Miller, David J. and Allemann, Rudolf K. ORCID: https://orcid.org/0000-0002-1323-8830 2018. Nucleophilic water capture or proton loss: single amino acid switch converts δ-Cadinene synthase into germacradien-4-ol synthase. Chembiochem 19 (1) , pp. 100-105. 10.1002/cbic.201700531

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Abstract

δ-Cadinene synthase is a sesquiterpene cyclase that utilises the universal achiral precursor farnesyl diphosphate (FDP) to generate predominantly the bicyclic sesquiterpene δ-cadinene and about 2 % germacradien-4-ol, which is also generated from FDP by the cyclase germacradien-4-ol synthase. Herein, the mechanism by which sesquiterpene synthases discriminate between deprotonation and reaction with a nucleophilic water molecule was investigated by site-directed mutagenesis of δ-cadinene synthase. If W279 in δ-cadinene synthase was replaced with various smaller amino acids, the ratio of alcohol versus hydrocarbon product was directly proportional to the van der Waals volume of the amino acid side chain. DCS-W279A is a catalytically highly efficient germacradien-4-ol synthase (kcat/KM=1.4×10−3 μm s−1) that produces predominantly germacradien-4-ol in addition to 11 % δ-cadinene. Water capture is not achieved through strategic positioning of a water molecule in the active site, but through a coordinated series of loop movements that allow bulk water access to the final carbocation in the active site prior to product release.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	Wiley
ISSN:	1439-4227
Funders:	Biotechnology and Biological Sciences Research Council
Date of First Compliant Deposit:	7 December 2017
Date of Acceptance:	2 November 2017
Last Modified:	04 May 2024 01:07
URI:	https://orca.cardiff.ac.uk/id/eprint/107399

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