ESP and ESM1 mediate indol-3-acetonitrile production from indol-3-ylmethyl glucosinolate in Arabidopsis

• Published in: Phytochemistry (Oxford) 2008-02, Vol.69 (3), p.663-671
• Main Authors: Burow, Meike, Zhang, Zhi-Yong, Ober, James A., Lambrix, Virginia M., Wittstock, Ute, Gershenzon, Jonathan, Kliebenstein, Daniel J.
• Format: Article
• Language: English
• Subjects: Arabidopsis - chemistry; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Biochemical assay; Biological and medical sciences; Brassicaceae; Enzymes - metabolism; Epithiospecifier modifier 1 protein; Epithiospecifier protein; Fundamental and applied biological sciences. Psychology; glucosinolates; Glucosinolates - chemistry; Glucosinolates - metabolism; Hydrolysis; Indol-3-acetonitrile; Indol-3-carbinol; Indole glucosinolate; indoles; Indoles - chemistry; Indoles - metabolism; Metabolism; Metabolism. Physicochemical requirements; nitriles; Plant physiology and development; plant proteins; quantitative analysis; Quantitative genetics; Sensitivity and Specificity; thioglucosidase; Time Factors
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2007.08.027

Multiple proteins function to control the production of indol-3-acetonitrile during indole glucosinolate activation/hydrolysis. Glucosinolates are plant secondary metabolites that act as direct defenses against insect herbivores and various pathogens. Recent analysis has shown that methionine-derived glucosinolates are hydrolyzed/activated into either nitriles or isothiocyanates depending upon the plants genotype at multiple loci. While it has been hypothesized that tryptophan-derived glucosinolates can be a source of indole-acetonitriles, it has not been explicitly shown if the same proteins control nitrile production from tryptophan-derived glucosinolates as from methionine-derived glucosinolates. In this report, we formally test if the proteins involved in controlling aliphatic glucosinolate hydrolysis during tissue disruption can control production of nitriles during indolic glucosinolate hydrolysis. We show that myrosinase is not sufficient for indol-3-acetonitrile production from indol-3-ylmethyl glucosinolate and requires the presence of functional epithospecifier protein in planta and in vitro to produce significant levels of indol-3-acetonitrile. This reaction is also controlled by the Epithiospecifier modifier 1 gene. Thus, like formation of nitriles from aliphatic glucosinolates, indol-3-acetonitrile production following tissue disruption is controlled by multiple loci raising the potential for complex regulation and fine tuning of indol-3-acetonitrile production from indol-3-ylmethyl glucosinolate.