|YANG, TIANHONG - Arkansas State University
|FANG, LINGLING - Arkansas State University
|MOCKAITIS, KEITHANNE - Indiana State University
|MEDINA-BOLIVAR, FABRICIO - Arkansas State University
Submitted to: Plant Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/25/2016
Publication Date: 6/29/2016
Citation: Yang, T., Fang, L., Rimando, A.M., Sobolev, V., Mockaitis, K., Medina-Bolivar, F. 2016. A stilbenoid-specific prenyltransferase utilizes dimethylallyl pyrophosphate from the plastidic terpenoid pathway. Plant Physiology. 171:2483–2498.
Interpretive Summary: Low-molecular weight compounds with beneficial properties, stilbenoids, are found in the peanut plant challenged by exogenous stimuli. These stilbenoids bear one or two isoprenyl moieties with five carbon atoms bound to the aromatic ring of the stilbene molecule. The exact mechanism of this kind of stilbenoid formation in peanuts is not known. Present research revealed stilbenoid-specific prenyltransferase, an enzyme from the microsomal fraction of peanut hairy roots. This enzyme was demonstrated to be involved in the biosynthesis of peanut prenylated stilbenoids. In addition, a new prenylated stilbenoid was isolated from hairy roots. Its structure was unambiguously elucidated by modern instrumental means. The first plant membrane-bound stilbenoid-specific prenyltransferase from the microsomal fraction of peanut hairy roots was further characterized. The characteristics of this enzyme provide important information for subsequent cloning prenyltransferase gene(s) from peanut. In addition, the enzymatic degradation of exogenous resveratrol, the simplest peanut stilbenoid, in the peanut hairy root tissue will help to elucidate the distinct metabolism of prenylated stilbenoids in peanut.
Technical Abstract: Prenylated stilbenoids found preferentially in a few legume plants exhibit phytoalexin properties and pharmacological activities with potential benefits to human health. Despite their importance, the biosynthetic pathways of these compounds remain to be elucidated. Peanut (Arachis hypogaea) hairy root cultures produce a diverse array of prenylated stilbenoids upon treatment with elicitors. Using metabolic inhibitors of the plastidic and cytosolic isoprenoid biosynthetic pathways, we demonstrated that the prenyl moiety on the prenylated stilbenoids derives from the plastidic pathway. We further characterized the first plant membrane-bound stilbenoid-specific prenyltransferase from the microsomal fraction of peanut hairy roots. This microsomal fraction-derived resveratrol 4'-dimethyllyltransferase (AhR4DT) utilizes 3,3-dimethylallyl pyrophosphate as a prenyl donor and prenylates resveratrol to form arachidin-2. The microsomal fraction also prenylates pinosylvin to chiricanine A and piceatannol to arachidin-5, a new prenylated stilbenoid identified in this study. AhR4DT exhibits strict substrate specificity for stilbenoids and does not prenylate flavanone, flavone or isoflavone backbones, even though it shares several common features with flavonoid-specific prenyltransferases.