Biosynthetic pathway of shikimate and aromatic amino acid and its metabolic engineering in plants

Abstract

The aromatic amino acids, which are composed of L-phenylalanine, L-tyrosine and L-tryptophan, are general components of protein synthesis as well as precursors for a wide range of secondary metabolites. These aromatic amino acids-derived compounds play important roles as ingredients of diverse phenolics including pigments and cell walls, and hormones like auxin and salicylic acid in plants. Moreover, they also serve as the natural products of alkaloids and glucosinolates, which have a high potential to promote human health and nutrition. The biosynthetic pathways of aromatic amino acids share a chorismate, the common intermediate, which is originated from shikimate pathway. Then, tryptophan is synthesized via anthranilate and the other phenylalanine and tyrosine are synthesized via prephenate, as intermediates. This review reports recent studies about all the enzymatic steps involved in aromatic amino acid biosynthetic pathways and their gene regulation on transcriptional/posttranscriptional levels. Furthermore, results of metabolic engineering are introduced as efforts to improve the production of the aromatic amino acids-derived secondary metabolites in plants.