Tyrosine and Phenylalanine Are Synthesized within the Plastids in Arabidopsis

Rippert, Pascal; Puyaubert, Juliette; Grisollet, Delphine; Derrier, Laure; Matringe, Michel

doi:10.1104/pp.108.130070

Cited by 126 publications

(115 citation statements)

References 30 publications

(42 reference statements)

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“…To date, it is believed that aromatic amino acids are exclusively synthesized in the plastid 10,16,18,29,30 , and then transported into the cytosol to serve as building blocks for proteins and precursors of downstream metabolites. In light of the absence of an N-terminal targeting signal and the confirmed cytosolic localization of PhPPY-AT (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…In plants phenylalanine biosynthesis via the arogenate pathway takes place in plastids 10,16,18,29,30 . Surprisingly however, the protein targeting prediction programs (WolfPSort: http://wolfpsort.org/ 31 ; Predotar: http://urgi.versailles.inra.fr/predotar/predotar.html 32 ; TargetP: http://www.cbs.dtu.dk/services/TargetP/ 33 ) revealed the absence of an N-terminal transit peptide for plastidic localization in the PhPPY-AT protein.…”

Section: Phppa-at Suppression Inmentioning

confidence: 99%

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An alternative pathway contributes to phenylalanine biosynthesis in plants via a cytosolic tyrosine:phenylpyruvate aminotransferase

et al. 2013

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Phenylalanine is a vital component of proteins in all living organisms, and in plants is a precursor for thousands of additional metabolites. Animals are incapable of synthesizing phenylalanine and must primarily obtain it directly or indirectly from plants. Although plants can synthesize phenylalanine in plastids through arogenate, the contribution of an alternative pathway via phenylpyruvate, as occurs in most microbes, has not been demonstrated. Here we show that plants also utilize a microbial-like phenylpyruvate pathway to produce phenylalanine, and flux through this route is increased when the entry point to the arogenate pathway is limiting. Unexpectedly, we find the plant phenylpyruvate pathway utilizes a cytosolic aminotransferase that links the coordinated catabolism of tyrosine to serve as the amino donor, thus interconnecting the extra-plastidial metabolism of these amino acids. This discovery uncovers another level of complexity in the plant aromatic amino acid regulatory network, unveiling new targets for metabolic engineering.

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Section: Discussionmentioning

confidence: 99%

Section: Phppa-at Suppression Inmentioning

confidence: 99%

An alternative pathway contributes to phenylalanine biosynthesis in plants via a cytosolic tyrosine:phenylpyruvate aminotransferase

et al. 2013

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“…A chloroplast location is reasonable inasmuch as chloroplasts are rich in 10-CHO-THF (Orsomando et al, 2005;Mehrshahi et al, 2010) and are where the Phe substrate of AAH, and its product Tyr, are made from L-arogenate (Rippert et al, 2009). Because the 4a-carbinolamine produced (A) Transient expression in Arabidopsis mesophyll protoplasts of GFP fused to the C terminus of P. taeda AAH (top panels), P. patens AAH (middle panels), or GFP alone (bottom panels).…”

Section: Plant Aahs and Their Pcd Partners Are Chloroplast Localizedmentioning

confidence: 99%

Nonflowering Plants Possess a Unique Folate-Dependent Phenylalanine Hydroxylase That Is Localized in Chloroplasts

et al. 2010

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Tetrahydropterin-dependent aromatic amino acid hydroxylases (AAHs) are known from animals and microbes but not plants. A survey of genomes and ESTs revealed AAH-like sequences in gymnosperms, mosses, and algae. Analysis of fulllength AAH cDNAs from Pinus taeda, Physcomitrella patens, and Chlamydomonas reinhardtii indicated that the encoded proteins form a distinct clade within the AAH family. These proteins were shown to have Phe hydroxylase activity by functional complementation of an Escherichia coli Tyr auxotroph and by enzyme assays. The P. taeda and P. patens AAHs were specific for Phe, required iron, showed Michaelian kinetics, and were active as monomers. Uniquely, they preferred 10-formyltetrahydrofolate to any physiological tetrahydropterin as cofactor and, consistent with preferring a folate cofactor, retained activity in complementation tests with tetrahydropterin-depleted E. coli host strains. Targeting assays in Arabidopsis thaliana mesophyll protoplasts using green fluorescent protein fusions, and import assays with purified Pisum sativum chloroplasts, indicated chloroplastic localization. Targeting assays further indicated that pterin-4a-carbinolamine dehydratase, which regenerates the AAH cofactor, is also chloroplastic. Ablating the single AAH gene in P. patens caused accumulation of Phe and caffeic acid esters. These data show that nonflowering plants have functional plastidial AAHs, establish an unprecedented electron donor role for a folate, and uncover a novel link between folate and aromatic metabolism.

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“…The sequential reactions forming prephenate, arogenate, and Tyr, referred to as the ADH pathway (shown in Fig. 1), occur in plastids (Rippert et al, 2009;Tzin and Galili, 2010;Maeda and Dudareva, 2012). Tyr is then translocated into the cytoplasm, where it is converted to homogentisate, which is either oxidized by HGO for catabolism or translocated back into plastids for tocochromanol and plastoquinone biosynthesis (Hunter and Cahoon, 2007;Block et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

Identification of Homogentisate Dioxygenase as a Target for Vitamin E Biofortification in Oilseeds

et al. 2016

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Soybean (Glycine max) is a major plant source of protein and oil and produces important secondary metabolites beneficial for human health. As a tool for gene function discovery and improvement of this important crop, a mutant population was generated using fast neutron irradiation. Visual screening of mutagenized seeds identified a mutant line, designated MO12, which produced brown seeds as opposed to the yellow seeds produced by the unmodified Williams 82 parental cultivar. Using forward genetic methods combined with comparative genome hybridization analysis, we were able to establish that deletion of the GmHGO1 gene is the genetic basis of the brown seeded phenotype exhibited by the MO12 mutant line. GmHGO1 encodes a homogentisate dioxygenase (HGO), which catalyzes the committed enzymatic step in homogentisate catabolism. This report describes to our knowledge the first functional characterization of a plant HGO gene, defects of which are linked to the human genetic disease alkaptonuria. We show that reduced homogentisate catabolism in a soybean HGO mutant is an effective strategy for enhancing the production of lipid-soluble antioxidants such as vitamin E, as well as tolerance to herbicides that target pathways associated with homogentisate metabolism. Furthermore, this work demonstrates the utility of fast neutron mutagenesis in identifying novel genes that contribute to soybean agronomic traits.

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Tyrosine and Phenylalanine Are Synthesized within the Plastids in Arabidopsis

Cited by 126 publications

References 30 publications

An alternative pathway contributes to phenylalanine biosynthesis in plants via a cytosolic tyrosine:phenylpyruvate aminotransferase

An alternative pathway contributes to phenylalanine biosynthesis in plants via a cytosolic tyrosine:phenylpyruvate aminotransferase

Nonflowering Plants Possess a Unique Folate-Dependent Phenylalanine Hydroxylase That Is Localized in Chloroplasts

Identification of Homogentisate Dioxygenase as a Target for Vitamin E Biofortification in Oilseeds

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