Campus Units

Biochemistry, Biophysics and Molecular Biology, Roy J. Carver Department of

Document Type

Article

Publication Version

Accepted Manuscript

Publication Date

6-2018

Journal or Book Title

The Plant Journal

Volume

94

Issue

5

First Page

847

Last Page

856

DOI

10.1111/tpj.13901

Abstract

The astounding structural and biological diversity of the large class of terpenoid natural products are imparted by both their complex hydrocarbon backbones and further elaboration by the addition of multiple hydroxyl groups, which provide both solubility and specific binding properties. While the role of terpene synthases in generating hydrocarbons with complex backbones is well known, these also are known to generate (singly) hydroxylated products by the addition of water prior to terminating deprotonation. Here a maize sesquiterpene synthase was unexpectedly found to generate dually hydroxylated products directly from (E,E)-farnesyl diphosphate, primarily eudesmane-2,11-diol, along with two closely related structural isomers. The unprecedented formation of these diols was proposed to proceed via initial addition of water to a germacradienyl+ intermediate, followed by protonation of the internal carbon-6,7-double-bond in the resulting hedycarol, with subsequent cyclization and further addition of water to an eudesmolyl+ intermediate. Evidence for the proposed mechanism was provided by labeling studies, as well as site-directed mutagenesis, based on structural modeling, which identified an active site phenylalanine required for the protonation and further elaboration of hedycaryol. This di-hydroxylated sesquiterpenoid synthase was specifically expressed in maize roots and induced by pathogen infection, with its major enzymatic product only detected in root exudates or infected roots, suggesting a role in defense. Regardless of the ultimate metabolic fate or physiological role of these diols, this report not only reveals an unanticipated extension of the catalytic prowess of terpene synthases, but also provides insight into the underlying enzymatic mechanism.

Comments

This is the peer reviewed version of the following article: Liang, Jin, Jiang Liu, Reid Brown, Meirong Jia, Ke Zhou, Reuben J. Peters, and Qiang Wang. "Direct production of dihydroxylated sesquiterpenoids by a maize terpene synthase." The Plant Journal 94 (2018): 847-856, which has been published in final form at doi:10.1111/tpj.13901. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Copyright Owner

The Authors, The Plant Journal, John Wiley & Sons Ltd

Language

en

File Format

application/pdf

Published Version

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