Identification of a plant gene encoding glutamate/aspartate‐prephenate aminotransferase: The last homeless enzyme of aromatic amino acids biosynthesis

Graindorge, M.; Giustini, Cécile; Jacomin, Anne-Claire; Kraut, Alexandra; Curien, Gilles; Matringe, Michel

doi:10.1016/j.febslet.2010.09.037

Cited by 56 publications

(56 citation statements)

References 33 publications

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“…For instance, the two genes annotated as Asp aminotransferases (ASP4, At1g62800; AAT, At2g22250) are likely involved in the aminotransferase step in phenylpropanoid biosynthesis, with Asp as amino group donor and prephenate as amino group acceptor. For AAT, this is in line with its recent in vitro characterization (Graindorge et al, 2010). Two chloroplast-located transporters (PHT4;2, At2g38060; PHT2;1, At3g26570) might be involved in translocating intermediates of the shikimate and Phe biosynthesis (e.g., phospoenolpyruvate, shikimate, and Phe) across the chloroplast membrane (Grace and Logan, 2000;Versaw and Harrison, 2002;Guo et al, 2008).…”

Section: A Role For Transaldolase2 In Lignificationsupporting

confidence: 64%

A Systems Biology View of Responses to Lignin Biosynthesis Perturbations inArabidopsis

et al. 2012

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Lignin engineering is an attractive strategy to improve lignocellulosic biomass quality for processing to biofuels and other bio-based products. However, lignin engineering also results in profound metabolic consequences in the plant. We used a systems biology approach to study the plant's response to lignin perturbations. To this end, inflorescence stems of 20 Arabidopsis thaliana mutants, each mutated in a single gene of the lignin biosynthetic pathway (phenylalanine ammonia-lyase1, and cinnamyl alcohol dehydrogenase6 [CAD6], two mutant alleles each), were analyzed by transcriptomics and metabolomics. A total of 566 compounds were detected, of which 187 could be tentatively identified based on mass spectrometry fragmentation and many were new for Arabidopsis. Up to 675 genes were differentially expressed in mutants that did not have any obvious visible phenotypes. Comparing the responses of all mutants indicated that c4h, 4cl1, ccoaomt1, and ccr1, mutants that produced less lignin, upregulated the shikimate, methyl-donor, and phenylpropanoid pathways (i.e., the pathways supplying the monolignols). By contrast, f5h1 and comt, mutants that provoked lignin compositional shifts, downregulated the very same pathways. Reductions in the flux to lignin were associated with the accumulation of various classes of 4-O-and 9-O-hexosylated phenylpropanoids. By combining metabolomic and transcriptomic data in a correlation network, system-wide consequences of the perturbations were revealed and genes with a putative role in phenolic metabolism were identified. Together, our data provide insight into lignin biosynthesis and the metabolic network it is embedded in and provide a systems view of the plant's response to pathway perturbations.

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Section: A Role For Transaldolase2 In Lignificationsupporting

confidence: 64%

A Systems Biology View of Responses to Lignin Biosynthesis Perturbations inArabidopsis

et al. 2012

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“…(2) PPA-AT activity from Arabidopsis thaliana culture cells was purified to a single peak corresponding to AspAT Ib, encoded by At2g22250 (Graindorge et al, 2010). (3) Plant AspAT Ib genes are strongly coexpressed with shikimate, Phe, and phenylpropanoid pathway genes (Dal Cin et al, 2011;Maeda et al, 2011), which is not the case for plant homologs of microbial BCAT-and S-DAPAT-type PPA-ATs (Supplemental Data Set 1).…”

Section: Introductionmentioning

confidence: 99%

Phylobiochemical Characterization of Class-Ib Aspartate/Prephenate Aminotransferases Reveals Evolution of the Plant Arogenate Phenylalanine Pathway

et al. 2014

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The aromatic amino acid Phe is required for protein synthesis and serves as the precursor of abundant phenylpropanoid plant natural products. While Phe is synthesized from prephenate exclusively via a phenylpyruvate intermediate in model microbes, the alternative pathway via arogenate is predominant in plant Phe biosynthesis. However, the molecular and biochemical evolution of the plant arogenate pathway is currently unknown. Here, we conducted phylogenetically informed biochemical characterization of prephenate aminotransferases (PPA-ATs) that belong to class-Ib aspartate aminotransferases (AspAT Ibs) and catalyze the first committed step of the arogenate pathway in plants. Plant PPA-ATs and succeeding arogenate dehydratases (ADTs) were found to be most closely related to homologs from Chlorobi/Bacteroidetes bacteria. The Chlorobium tepidum PPA-AT and ADT homologs indeed efficiently converted prephenate and arogenate into arogenate and Phe, respectively. A subset of AspAT Ib enzymes exhibiting PPA-AT activity was further identified from both Plantae and prokaryotes and, together with site-directed mutagenesis, showed that Thr-84 and Lys-169 play key roles in specific recognition of dicarboxylic keto (prephenate) and amino (aspartate) acid substrates. The results suggest that, along with ADT, a gene encoding prephenate-specific PPA-AT was transferred from a Chlorobi/Bacteroidetes ancestor to a eukaryotic ancestor of Plantae, allowing efficient Phe and phenylpropanoid production via arogenate in plants today.

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“…PATs are bifunctional enzymes competent to function not only as PATs but also as AATs in Arabidopsis (Graindorge et al, 2010;Maeda et al, 2011), petunia (Maeda et al, 2011), tomato (Solanum lycopersicum; Dal Cin et al, 2011), and P. pinaster (de la Torre et al, 2006). The analysis of recombinant PAT protein indicates that the enzyme exhibits a high affinity for substrates involved in both PAT and AAT activities.…”

Section: Suppression Of Pat Activity In N Benthamianamentioning

confidence: 99%

“…It is important to remark that in the presence of Glu as nitrogen donor, PAT exhibits similar values of the specificity constant for oxaloacetate and prephenate, indicating that the enzyme can operate both as a PAT and as a classical AAT (Graindorge et al, 2010). Consequently, PAT could be involved not only in the biosynthesis of aromatic amino acids but also in the biosynthesis of Asp-derived amino acids.…”

mentioning

confidence: 97%

“…The kinetic parameters of this enzyme were determined, highlighting its high affinity for Glu and Asp compared with other plant AATs (de la Torre et al, 2006). Recently, Graindorge et al (2010) and Maeda et al (2011) independently discovered that plant prokaryotic-type AATs displayed not only AAT activity but also prephenate aminotransferase (PAT) activity. PAT activity catalyzes the reversible transamination between Glu/Asp and prephenate to yield 2-oxoglutarate/oxaloacetate and arogenate.…”

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confidence: 99%

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Deciphering the Role of Aspartate and Prephenate Aminotransferase Activities in Plastid Nitrogen Metabolism

2013

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Chloroplasts and plastids of nonphotosynthetic plant cells contain two aspartate (Asp) aminotransferases: a eukaryotic type (Asp5) and a prokaryotic-type bifunctional enzyme displaying Asp and prephenate aminotransferase activities (PAT). We have identified the entire Asp aminotransferase gene family in Nicotiana benthamiana and isolated and cloned the genes encoding the isoenzymes with plastidic localization: NbAsp5 and NbPAT. Using a virus-induced gene silencing approach, we obtained N. benthamiana plants silenced for NbAsp5 and/or NbPAT. Phenotypic and metabolic analyses were conducted in silenced plants to investigate the specific roles of these enzymes in the biosynthesis of essential amino acids within the plastid. The NbAsp5 silenced plants had no changes in phenotype, exhibiting similar levels of free Asp and glutamate as control plants, but contained diminished levels of asparagine and much higher levels of lysine. In contrast, the suppression of NbPAT led to a severe reduction in growth and strong chlorosis symptoms. NbPAT silenced plants exhibited extremely reduced levels of asparagine and were greatly affected in their phenylalanine metabolism and lignin deposition. Furthermore, NbPAT suppression triggered a transcriptional reprogramming in plastid nitrogen metabolism. Taken together, our results indicate that NbPAT has an overlapping role with NbAsp5 in the biosynthesis of Asp and a key role in the production of phenylalanine for the biosynthesis of phenylpropanoids. The analysis of NbAsp5/NbPAT cosilenced plants highlights the central role of both plastidic aminotransferases in nitrogen metabolism; however, only NbPAT is essential for plant growth and development.

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Identification of a plant gene encoding glutamate/aspartate‐prephenate aminotransferase: The last homeless enzyme of aromatic amino acids biosynthesis

Cited by 56 publications

References 33 publications

A Systems Biology View of Responses to Lignin Biosynthesis Perturbations inArabidopsis

A Systems Biology View of Responses to Lignin Biosynthesis Perturbations inArabidopsis

Phylobiochemical Characterization of Class-Ib Aspartate/Prephenate Aminotransferases Reveals Evolution of the Plant Arogenate Phenylalanine Pathway

Deciphering the Role of Aspartate and Prephenate Aminotransferase Activities in Plastid Nitrogen Metabolism

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