Journal article
The arogenate dehydratase gene family: Towards understanding differential regulation of carbon flux through phenylalanine into primary versus secondary metabolic pathways
Phytochemistry (Oxford), Vol.82, pp.22-37
10/2012
Handle:
https://hdl.handle.net/2376/104261
PMID: 22818526
Abstract
Arogenate dehydratase (ADT) was differentially knocked out in a series of mutant lines. The impact on free amino acid pools was determined with the most significant effect being on Phe pool sizes in lignifying stems. [Display omitted]
► Twenty-five Arabidopsis thaliana arogenate dehydratase mutants were analyzed for amino acid pool sizes. ► Those mutants, which had ADT directed to Phe conversion into stem lignin, had much reduced Phe levels. ► No other significant effects on amino acid pool sizes were observed.
Phe is formed from arogenate in planta through the action of arogenate dehydratase (ADT), and there are six ADT isoenzymes in the “model” vascular plant species Arabidopsis thaliana. This raised the possibility that specific ADTs may be differentially regulated so as to control Phe biosynthesis for protein synthesis vs its much more massive deployment for phenylpropanoid metabolism. In our previous reverse genetics study using 25 single/multiple ADT knockout (KO) lines, a subset of these knockouts was differentially reduced in their lignin contents.
In the current investigation, it was hypothesized that Phe pool sizes might correlate well with reduction in lignin contents in the affected KO lines. The free amino acid contents of these KO lines were thus comprehensively analyzed in stem, leaf and root tissues, over a growth/developmental time course from 3 to 8weeks until senescence. The data obtained were then compared to, and contrasted with, the differential extent of lignin deposition occurring in the various lines. Relative changes in pool sizes were also analyzed by performing a pairwise confirmatory factor analysis for Phe:Tyr, Phe:Trp and Tyr:Trp, following determination of the deviation from the mean for Phe, Tyr and Trp in each plant line. It was found that the Phe pool sizes measured were differentially reduced only in lignin-deficient lines, and in tissues and at time points where lignin biosynthesis was constitutively highly active (in wild type lines) under the growth conditions employed. In contrast, this trend was not evident across all ADT KO lines, possibly due to maintenance of Phe pools by non-targeted isoenzymes, or by feedback mechanisms known to be in place.
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Details
- Title
- The arogenate dehydratase gene family: Towards understanding differential regulation of carbon flux through phenylalanine into primary versus secondary metabolic pathways
- Creators
- Oliver R.A CoreaDiana L BedgarLaurence B DavinNorman G Lewis
- Publication Details
- Phytochemistry (Oxford), Vol.82, pp.22-37
- Academic Unit
- Biological Chemistry, Institute of
- Publisher
- Elsevier Ltd
- Identifiers
- 99900546676201842
- Language
- English
- Resource Type
- Journal article