Open Access

ARTICLE

Identification of a Unique Germacrene A Oxidase from Xanthium strumarium

by Lifen Zheng¹, Fangfang Chen², Yuanjun Li³, Changfu Li^1,*

1 Shanghai Key Laboratory of Bio-Energy Crops, Research Center for Natural Products, Plant Science Center, School of Life Sciences, Shanghai University, Shanghai, 200444, China
2 Songjiang Yunjian School Affiliated to Shanghai Foreign Language School, Shanghai, 201600, China
3 College of Medicine, Henan University of Chinese Medicine, Zhengzhou, 450046, China

* Corresponding Author: Changfu Li. Email:

(This article belongs to the Special Issue: Plant Omics in Challenging Environment)

Phyton-International Journal of Experimental Botany 2022, 91(5), 989-998. https://doi.org/10.32604/phyton.2022.019219

Received 09 September 2021; Accepted 09 October 2021; Issue published 24 January 2022

Abstract

8,12-sesquiterpene lactones (STLs) are an important class of natural products with unique pharmaceutical activities. For years the pathway leading to 8,12-STLs remains an enigma. Xanthium strumarium accumulates abundant 8,12-STLs, and xanthatin is a characteristic 8,12-STL in it. Xanthatin has been previously postulated to be derived from germacrene A, but the steps from germacrene A to xanthatin are unknown. As part of an effort to understand the xanthatin biosynthetic pathway. This study reports the characterization of a unique germacrene A oxidase (XsGAO) from X. strumarium. Unlike a classical GAO enzyme, which is known to catalyze a three-step oxidation of germarene A to yield germacrene A acid (GAA), surprisingly, XsGAO catalyzed only one-step conversion of germacrene A to germacrene A alcohol. We discussed that GAO may be pressured to acquire a novel activity during the evolutionary path for the biosynthesis of 8,12-STLs.

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