Gene expression and characterization of a stress‐induced tyrosine decarboxylase from <i>Arabidopsis thaliana</i>

Lehmann, Thomas; Pollmann, Stephan

doi:10.1016/j.febslet.2009.05.017

Cited by 67 publications

(51 citation statements)

References 24 publications

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“…Likewise, the major enzymes of Tyr biosynthesis have been localized to the chloroplast (Tzin and Galili, 2010), placing JrPPO1 and Tyr in the same compartment. Tyr decarboxylase, the enzyme that converts Tyr to tyramine, has been localized to the cytosol in Arabidopsis (Lehmann and Pollmann, 2009), so tyramine would presumably need to be transported back to the chloroplast for catalysis by PPO.…”

Section: Discussionmentioning

confidence: 99%

Novel Roles for the Polyphenol Oxidase Enzyme in Secondary Metabolism and the Regulation of Cell Death in Walnut

et al. 2014

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The enzyme polyphenol oxidase (PPO) catalyzes the oxidation of phenolic compounds into highly reactive quinones. Polymerization of PPO-derived quinones causes the postharvest browning of cut or bruised fruit, but the native physiological functions of PPOs in undamaged, intact plant cells are not well understood. Walnut (Juglans regia) produces a rich array of phenolic compounds and possesses a single PPO enzyme, rendering it an ideal model to study PPO. We generated a series of PPO-silenced transgenic walnut lines that display less than 5% of wild-type PPO activity. Strikingly, the PPO-silenced plants developed spontaneous necrotic lesions on their leaves in the absence of pathogen challenge (i.e. a lesion mimic phenotype). To gain a clearer perspective on the potential functions of PPO and its possible connection to cell death, we compared the leaf transcriptomes and metabolomes of wild-type and PPO-silenced plants. Silencing of PPO caused major alterations in the metabolism of phenolic compounds and their derivatives (e.g. coumaric acid and catechin) and in the expression of phenylpropanoid pathway genes. Several observed metabolic changes point to a direct role for PPO in the metabolism of tyrosine and in the biosynthesis of the hydroxycoumarin esculetin in vivo. In addition, PPOsilenced plants displayed massive (9-fold) increases in the tyrosine-derived metabolite tyramine, whose exogenous application elicits cell death in walnut and several other plant species. Overall, these results suggest that PPO plays a novel and fundamental role in secondary metabolism and acts as an indirect regulator of cell death in walnut.

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Section: Discussionmentioning

confidence: 99%

Novel Roles for the Polyphenol Oxidase Enzyme in Secondary Metabolism and the Regulation of Cell Death in Walnut

et al. 2014

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“…Mammalian DDC has been the most extensively studied AAAD in terms of substrate specificity and catalytic reactions. Based on literature, mammalian DDC can use both DOPA and 5-HTP as substrates (24,25), but the plant AAADs or AASs use aromatic amino acids with either the indole ring or benzene ring, but never both (1,8,9). Other than its typical decarboxylation activity to DOPA and 5-HTP, mammalian DDC can also catalyze oxidative deamination of dopamine and 5-HT (26,27).…”

Section: Discussionmentioning

confidence: 99%

“…Tryptamine and 5-hydroxytryptamine (5-HT), produced by specific plant AAADs, are precursors for the synthesis of thousands of indole alkaloid compounds (1,6,7). Because their substrate specificity provides functional relevant information, some AAADs have been further annotated on their principle substrate as tyrosine decarboxylases (TyDC) and tryptophan decarboxylases (TDC) (8,9).…”

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confidence: 99%

Biochemical Evaluation of the Decarboxylation and Decarboxylation-Deamination Activities of Plant Aromatic Amino Acid Decarboxylases

Torrens-Spence

Liu

Ding

et al. 2013

Journal of Biological Chemistry

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Background: Plant arylalkylamine and aldehyde synthesizing aromatic amino acid decarboxylases (AAAD) are effectively indistinguishable. Results: Mutagenesis of a single AAAD residue enables the interconversion of activities. Conclusion: A single residue is primarily responsible for differentiating plant AAAD decarboxylase and aldehyde synthase activities. Significance: AAAD activity differentiation enables primary sequence activity identification, generation of unusual AAAD enzyme products, and AAAD mechanistic insights.

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“…To investigate whether the cytosolic pool of tyrosine can influence phenylalanine levels in vivo, the level of tyrosine was depleted in petunia flowers of PhADT1xPhPPA-AT RNAi via transient overexpression of the cytosolic Arabidopsis tyrosine decarboxylase (AtTYDC), which exclusively catalyses decarboxylation of L-tyrosine to tyramine 37,38 . AtTYDC overexpression resulted in 50% reduction of the tyrosine pool and a 9-fold increase in tyramine levels with a concomitant 50% decrease in phenylalanine levels (Fig.…”

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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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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Gene expression and characterization of a stress‐induced tyrosine decarboxylase from Arabidopsis thaliana

Cited by 67 publications

References 24 publications

Novel Roles for the Polyphenol Oxidase Enzyme in Secondary Metabolism and the Regulation of Cell Death in Walnut

Novel Roles for the Polyphenol Oxidase Enzyme in Secondary Metabolism and the Regulation of Cell Death in Walnut

Biochemical Evaluation of the Decarboxylation and Decarboxylation-Deamination Activities of Plant Aromatic Amino Acid Decarboxylases

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

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