Model of the Subcellular Organization of Avenacin A-1 Biosynthesis in Oat.The acyl group of avenacin A-1 originates from the shikimate pathway in the plastid

Model of the Subcellular Organization of Avenacin A-1 Biosynthesis in Oat.The acyl group of avenacin A-1 originates from the shikimate pathway in the plastid. Anthranilate (Anth) (which fluoresces purple under UV illumination) is methylated by MT1 (encoded by Sad9) to produce N-methyl anthranilate (NMA) (which fluoresces blue) and then glucosylated by UGT74H5 to give N-methyl anthraniloyl-O-glucose (NMA-Glc). NMA-Glc is transported into the vacuole by an unknown mechanism, where it serves as the acyl donor substrate for SCPL1 (SAD7). The triterpene glycoside is synthesized from the cytoplasmic mevalonate (MVA) pathway products, and the early steps are catalyzed by β-amyrin synthase (SAD1/AsβAS1) and CYP51H10 (SAD2). These steps are likely to be associated with the endoplasmic reticulum (ER) membrane (). Des-acyl avenacin A is then formed by a series of as yet uncharacterized oxidation and glycosylation steps. The triterpene glycoside is transported into the vacuole, either by a vacuolar membrane transporter or possibly through vesicular trafficking from the endoplasmic reticulum to the vacuole.

Publication

Modularity of Plant Metabolic Gene Clusters: A Trio of Linked Genes That Are Collectively Required for Acylation of Triterpenes in Oat. (2013) Sam T. Mugford, et al. Plant Cell. 2013 Mar;25(3):1078-1092. Figure: F8. Arabidopsis thaliana

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