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| Plant aromatic L-amino acid decarboxylases: evolution, biochemistry, regulation, and metabolic engineering applications |
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| Author(s): Facchini PJ, Huber-Allanach KL, Tari LW |
| Source: PHYTOCHEMISTRY Volume: 54 Issue: 2 Pages: 121-138 Published: MAY 2000 |
| Times Cited: 44 References: 111 |
| Abstract: A comprehensive survey of the extensive literature relevant to the evolution, physiology, biochemistry, regulation, and genetic engineering applications of plant aromatic L-amino acid decarboxylases (AADCs) is presented. AADCs catalyze the pyridoxal-5'-phosphate (PLP)-dependent decarboxylation of select aromatic L-amino acids in plants, mammals, and insects. Two plant AADCs, L-tryptophan decarboxylase (TDC) and L-tyrosine decarboxylase (TYDC), have attracted considerable attention because of their role in the biosynthesis of pharmaceutically important monoterpenoid indole alkaloids and benzylisoquinoline alkaloids, respectively. Although plant and animal AADCs share extensive amino acid homology, the enzymes display striking differences in their substrate specificities. AADCs from mammals and insects accept a broad range of aromatic L-amino acids, whereas TDC and TYDC from plants exhibit exclusive substrate specificity for L-amino acids with either indole or phenol side chains, but not both. Recent biochemical and kinetic studies on animal AADCs support basic features of the classic AADC reaction mechanism. The catalytic mechanism involves the formation of a Schiff base between PLP and an invariable lysine residue, followed by a transaldimination reaction with an aromatic L-amino acid substrate. Both TDC and TYDC are primarily regulated at the transcriptional level by developmental and environmental factors. However, the putative post-translational regulation of TDC via the ubiquitin pathway, by an ATP-dependent proteolytic process, has also been suggested. Isolated TDC and TYDC genes have been used to genetically alter the regulation of secondary metabolic pathways derived from aromatic amino acids in several plant species. The metabolic modifications include increased serotonin levers, reduced indole glucosinolate levels, redirected shikimate metabolism, increased indole alkaloid levels, and increased cell wall-bound tyramine levels. (C) 2000 Elsevier Science Ltd. All rights reserved. |
| Document Type: Review |
| Language: English |
| Reprint Address: Facchini, PJ (reprint author), Univ Calgary, Dept Biol Sci, 2500 Univ Dr 1 NW, Calgary, AB T2N 1N4 Canada |
Addresses:
1. Univ Calgary, Dept Biol Sci, Calgary, AB T2N 1N4 Canada |
| Publisher: PERGAMON-ELSEVIER SCIENCE LTD, THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLAND |
| Subject Category: Biochemistry & Molecular Biology; Plant Sciences |
| IDS Number: 319UQ |
| ISSN: 0031-9422 |
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| | | | | | | | | Record from Web of Science® | | | | | | | | | |