Tocopherol content and activities of tyrosine aminotransferase and cystine lyase in Arabidopsis under stress conditions

Holländer-Czytko, Heike; Grabowski, Janine; Sandorf, Iris; Weckermann, Katrin; Weiler, Elmar W.

doi:10.1016/j.jplph.2005.04.019

Cited by 100 publications

(55 citation statements)

References 18 publications

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“…However, it is important to note that none of these purported TyrAT candidates has been demonstrated to accept Tyr as a substrate for transamination. In contrast, PsTyrAT showed relatively lower sequence identity with Arabidopsis AtTyrAT-1 (AAN15626), AtTyrAT-2 (NP_180058), and AtTyrAT-3 (AAG37062), which have been shown to function as TyrATs (Lopukhina et al, 2001;Holländer-Czytko et al, 2005). Recently, melon (Cucumis melo) CmTyrAT (ADC45389) and Arabidopsis AtTyrAT-4 (NM_124776) were characterized as TyrATs (Gonda et al, 2010;Prabhu and Hudson, 2010) and showed considerable sequence identity (55% and 58%, respectively) to PsTyrAT.…”

Section: Identification Of a Tyrat Cdna From Opium Poppymentioning

confidence: 99%

“…1). Previously, TyrAT cDNAs implicated in the biosynthesis of tocopherols or in fruit ripening have been characterized in Arabidopsis and melon, respectively (Lopukhina et al, 2001;Holländer-Czytko et al, 2005;Gonda et al, 2010;Prabhu and Hudson, 2010).…”

Section: Involvement Of Tyrat In Bia Metabolism In Opium Poppymentioning

confidence: 99%

“…Among the plant enzymes included in the phylogenetic analysis (Fig. 2), only TyrATs from Arabidopsis and melon have been isolated and characterized (Lopukhina et al, 2001;Holländer-Czytko et al, 2005;Gonda et al, 2010;Prabhu and Hudson, 2010). ArAT from melon (FJ896816; designated here as CmTyrAT) dis- Figure 6.…”

Section: Involvement Of Tyrat In Bia Metabolism In Opium Poppymentioning

confidence: 99%

“…Although the biochemical and structural characterization of tyrosine aminotransferase (TyrAT) in mammals and fungi is well established (Blankenfeldt et al, 1999;Sobrado et al, 2003;Schneider et al, 2008;Mehere et al, 2010), considerably less is known about these enzymes in plants. TyrAT is regulated by coronatine, wounding, and methyl jasmonate (MeJA) and has been implicated as the initial enzyme in tocopherol biosynthesis in Arabidopsis (Arabidopsis thaliana) plants (Lopukhina et al, 2001;Holländer-Czytko et al, 2005) and Amaranthus caudatus and Chenopodium quinoa cell cultures (Antognoni et al, 2009). TyrAT activity was reported in rosmarinic acid-producing cell cultures of Anchusa officinalis and Coleus blumei and in MeJAtreated hairy root cultures of Salvia miltiorrhiza (DeEknamkul and Ellis, 1987a;Xiao et al, 2009b).…”

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confidence: 99%

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Tyrosine Aminotransferase Contributes to Benzylisoquinoline Alkaloid Biosynthesis in Opium Poppy

Lee

Facchini

2011

Plant Physiology

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Tyrosine aminotransferase (TyrAT) catalyzes the transamination of L-Tyr and a-ketoglutarate, yielding 4-hydroxyphenylpyruvic acid and L-glutamate. The decarboxylation product of 4-hydroxyphenylpyruvic acid, 4-hydroxyphenylacetaldehyde, is a precursor to a large and diverse group of natural products known collectively as benzylisoquinoline alkaloids (BIAs). We have isolated and characterized a TyrAT cDNA from opium poppy (Papaver somniferum), which remains the only commercial source for several pharmaceutical BIAs, including codeine, morphine, and noscapine. TyrAT belongs to group I pyridoxal 5#-phosphate (PLP)-dependent enzymes wherein Schiff base formation occurs between PLP and a specific Lys residue. The amino acid sequence of TyrAT showed considerable homology to other putative plant TyrATs, although few of these have been functionally characterized. Purified, recombinant TyrAT displayed a molecular mass of approximately 46 kD and a substrate preference for L-Tyr and a-ketoglutarate, with apparent K m values of 1.82 and 0.35 mM, respectively. No specific requirement for PLP was detected in vitro. Liquid chromatography-tandem mass spectrometry confirmed the conversion of L-Tyr to 4-hydroxyphenylpyruvate. TyrAT gene transcripts were most abundant in roots and stems of mature opium poppy plants. Virus-induced gene silencing was used to evaluate the contribution of TyrAT to BIA metabolism in opium poppy. TyrAT transcript levels were reduced by at least 80% in silenced plants compared with controls and showed a moderate reduction in total alkaloid content. The modest correlation between transcript levels and BIA accumulation in opium poppy supports a role for TyrAT in the generation of alkaloid precursors, but it also suggests the occurrence of other sources for 4-hydroxyphenylacetaldehyde.

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Section: Identification Of a Tyrat Cdna From Opium Poppymentioning

confidence: 99%

Section: Involvement Of Tyrat In Bia Metabolism In Opium Poppymentioning

confidence: 99%

Section: Involvement Of Tyrat In Bia Metabolism In Opium Poppymentioning

confidence: 99%

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confidence: 99%

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Tyrosine Aminotransferase Contributes to Benzylisoquinoline Alkaloid Biosynthesis in Opium Poppy

Lee

Facchini

2011

Plant Physiology

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“…26,27 The reactive oxygen species scavenging properties of flavonoids are most prominent in structures with dihydroxy B-ring substituted glycosides. The biosynthesis of flavonoids is induced by stresses of different nature, ranging from nitrogen/phosphate starvation to cold, salinity and drought.…”

Section: Discussionmentioning

confidence: 99%

Metabolomic shifts inBrassica napuslines with enhancedBnPLC2expression impact their response to low temperature stress and plant pathogens

et al. 2014

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Phosphatidylinositol-specific phospholipase C2 (PLC2) is a signaling enzyme with hydrolytic activity against membrane-bound phosphoinositides. It catalyzes the cleavage of phosphatidylinositol(4,5)bisphosphate (PtdIns(4,5) P 2 ) into two initial second messengers, myo-inositol-1,4,5-trisphosphate (InsP 3 ) and diacylglycerol (DAG). The former, as well as its fully phosphorylated derivative, myo-inositol-1,2,3,4,5,6-hexakisphosphate (InsP 6 ), play a major role in calcium signaling events within the cell, while DAG may be used in the regeneration of phospholipids or as a precursor for phosphatidic acid (PA) biosynthesis, an important signaling molecule involved in both biotic and abiotic types of stress tolerance. Overexpression of the gene for Brassica napus phospholipase C2 (BnPLC2) in Brassica napus has been shown to enhance drought tolerance, modulate multiple genes involved in different processes and favorably affect hormonal levels in different tissues. We, therefore, undertook the current study with a view to examining, at the metabolome level, its effect on both abiotic (low temperature) and biotic (stem white rot disease) types of stress in canola. Thus, while transgenic plants exhibited a significant rise in maltose levels and a concomitant elevation in some unsaturated free fatty acids (FFAs), glycerol, and glycerol 3-phosphate under subzero temperatures, they accumulated high levels of raffinose, stachyose and other sugars as well as some flavonoids under acclimatization conditions. Collectively, overexpression of BnPLC2 appears to have triggered different metabolite patterns consistent with its abiotic and, to a limited extent, biotic stress tolerance phenotypes.

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Organic Synthesis with Lyases

2022

Enzyme‐Based Organic Synthesis

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Tocopherol content and activities of tyrosine aminotransferase and cystine lyase in Arabidopsis under stress conditions

Cited by 100 publications

References 18 publications

Tyrosine Aminotransferase Contributes to Benzylisoquinoline Alkaloid Biosynthesis in Opium Poppy

Tyrosine Aminotransferase Contributes to Benzylisoquinoline Alkaloid Biosynthesis in Opium Poppy

Metabolomic shifts inBrassica napuslines with enhancedBnPLC2expression impact their response to low temperature stress and plant pathogens

Organic Synthesis with Lyases

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