Plastidic aspartate aminotransferases and the biosynthesis of essential amino acids in plants

• Published in: Journal of experimental botany Vol. 65; no. 19; pp. 5527 - 5534
• Main Authors: de la Torre, Fernando, Cañas, Rafael A, Pascual, M. Belén, Avila, Concepción, Cánovas, Francisco M
• Format: Journal Article
• Language: English
• Published: England Oxford University Press [etc.] 01.10.2014; Oxford University Press
• Subjects: Amino acid metabolism; Amino acids; Amino Acids, Essential - metabolism; Aspartate Aminotransferases - genetics; Aspartate Aminotransferases - metabolism; aspartate transaminase; aspartic acid; Aspartic Acid - metabolism; Biochemistry; Biosynthesis; chloroplasts; Chloroplasts - enzymology; Cyclic amino acids; Enzymes; Essential amino acids; Genes; glutamic acid; Glutamic Acid - metabolism; Ketoglutaric Acids - metabolism; metabolites; Models, Biological; Oxaloacetic Acid - metabolism; Phylogeny; plant growth; Plant Proteins - genetics; Plant Proteins - metabolism; Plants - enzymology; Plastids; Plastids - enzymology; reproduction; REVIEW PAPER; Substrate Specificity; transamination; Tyrosine - metabolism; Vascular plants; prephenate; aromatic amino acids; plastid; aspartate; aspartate metabolic pathway; Arogenate
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/eru240

In the chloroplasts and in non-green plastids of plants, aspartate is the precursor for the biosynthesis of different amino acids and derived metabolites that play distinct and important roles in plant growth, reproduction, development or defence. Aspartate biosynthesis is mediated by the enzyme aspartate aminotransferase (EC 2.6.1.1), which catalyses the reversible transamination between glutamate and oxaloacetate to generate aspartate and 2-oxoglutarate. Plastids contain two aspartate aminotransferases: a eukaryotic-type and a prokaryotic-type bifunctional enzyme displaying aspartate and prephenate aminotransferase activities. A general overview of the biochemistry, regulation, functional significance, and phylogenetic origin of both enzymes is presented. The roles of these plastidic aminotransferases in the biosynthesis of essential amino acids are discussed.