Characterization of Arabidopsis serine:glyoxylate aminotransferase, AGT1, as an asparagine aminotransferase

Zhang, Qianyi; Lee, Jamie; Pandurangan, Sudhakar; Clarke, Matthew W.; Pająk, Agnieszka; Marsolais, Frédéric

doi:10.1016/j.phytochem.2012.09.017

Cited by 51 publications

(44 citation statements)

References 43 publications

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“…This could be associated with the remobilization of assimilated nitrogen as proteins and other substance. According to Zhang et al (2013) Asn is a major form of N transported to sink tissues in Arabidopsis mutant. Our results confirmed their findings: free Asn was the dominant free AA in AH.…”

Section: Resultsmentioning

confidence: 99%

The changes of contents of selected free amino acids associated with cadmium stress in Noccaea caerulescens and Arabidopsis halleri

Zemanová¹,

Pavlı́k²,

Pavlı́ková³

et al. 2013

Plant Soil Environ.

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Changes of free amino acid (AA) contents (glutamic acid, glutamine, aspartic acid, asparagines, proline, hydroxyproline) in Noccaea caerulescens and Arabidopsis halleri under cadmium soil contamination (Cd1 = 30, Cd2 = 60, Cd3 = 90 mg/kg soil) are reported. Results of the pot experiment confirmed different effect of Cd on N. caerulescens in contrast to A. halleri and the higher stress adaptation of A. halleri. Total free AA contents in both plant species were not significantly modified by Cd contamination. The glutamic acid and glutamate contents in plant biomass were decreased under Cd2 and Cd3 stress. The declines of contents of both AA can be caused by intensive syntheses of plant defense elicitors, but declines in A. halleri were significantly lower in contrast to N. caerulescens. The content of aspartic acid was increased in N. caerulescens under Cd stress, but in A. halleri its changes were not observed. The different pathways of nitrogen utilization of tested plants were confirmed: the major AA forms used for nitrogen transport are glutamate for N. caerulescens and asparagine for A. halleri. The increase of proline content was determined only in N. caerulescens growing under Cd stress in the beginning of growing period.

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Section: Resultsmentioning

confidence: 99%

The changes of contents of selected free amino acids associated with cadmium stress in Noccaea caerulescens and Arabidopsis halleri

Zemanová¹,

Pavlı́k²,

Pavlı́ková³

et al. 2013

Plant Soil Environ.

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“…Thus, asparagine aminotransferase might play a role in detoxifying glyoxylate which can inhibit RuBisCO activity. Both the wild-type expression level of AGT1 and its high catalytic efficiency, expressed as V max /K m , of asparagine aminotransferase (10.4ˆ10´8 kcat mg´1¨mM´1), are similar to that of ASPGB1-encoded asparaginase (9.72ˆ10´8 kcat mg´1¨mM´1) [24,25], thus suggesting that asparagine hydrolysis not only provides ammonium but also pre-conditions aspartate and glutamate in response to the lower energy status of the germinating seeds. Despite ASN3 disruption, increased levels of 15 N-labeled asparagine in asn3-1 seeds may be due to the decreased endogenous asparagine content, suggesting that ASN3-encoded asparagine synthetase may contribute to providing at least a basal level of asparagine in germinating seeds.…”

Section: Discussionmentioning

confidence: 94%

“…Moreover, the imbibed asn3-1 seeds contained wild-type levels of AGT1 mRNA ( Figure 5). AGT1 is the single gene encoding serine:glyoxylate aminotransferase which catalyzes transamination reactions with multiple substrates including asparagine as an amino donor [22][23][24]. Previous studies demonstrated that Arabidopsis asparagine aminotransferase acts as a serine:glyoxylate aminotransferase [24].…”

Section: Discussionmentioning

confidence: 99%

Impact of the Disruption of ASN3-Encoding Asparagine Synthetase on Arabidopsis Development

et al. 2016

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Abstract:The aim of this study was to investigate the role of ASN3-encoded asparagine synthetase (AS, EC 6.3.5.4) during vegetative growth, seed development and germination of Arabidopsis thaliana. Phenotypic analysis of knockout (asn3-1) and knockdown (asn3-2) T-DNA insertion mutants for the ASN3 gene (At5g10240) demonstrated wild-type contents of asparagine synthetase protein, chlorophyll and ammonium in green leaves at 35 days after sowing. In situ hybridization localized ASN3 mRNA to phloem companion cells of vasculature. Young siliques of the asn3-1 knockout line showed a decrease in asparagine but an increase in glutamate. The seeds of asn3-1 and asn3-2 displayed a wild-type nitrogen status expressed as total nitrogen content, indicating that the repression of ASN3 expression had only a limited effect on mature seeds. An analysis of amino acid labeling of seeds imbibed with ( 15 N) ammonium for 24 h revealed that asn3-1 seeds contained 20% less total asparagine while 15 N-labeled asparagine ((2-15 N)asparagine, (4-15 N)asparagine and (2,4-15 N)asparagine) increased by 12% compared to wild-type seeds. The data indicate a fine regulation of asparagine synthesis and hydrolysis in Arabidopsis seeds.

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“…Red arrows indicate excess ‘SGAT’ activities including entry nodes for asparagine nitrogen. Red numbers are catalytic efficiencies of the individual ‘SGAT’ reactions according to Zhang et al (2013). Also shown are potential serine production from hydroxypyruvate at night (grey background) and the recycling of 2OS via ω-amidase at day and night.…”

Section: Introductionmentioning

confidence: 99%

“…Particularly, they do not consider that the two canonical photorespiratory aminotransferases are promiscuous enzymes that transaminate a range of different substrates (Rehfeld and Tolbert, 1972; Ireland and Joy, 1983; Murray et al , 1987; Liepman and Olsen, 2001, 2003; Kendziorek and Paszkowski, 2008; Zhang et al , 2013). SGAT, on which this report is focused, actually works most efficiently with asparagine as the amino donor (EC 2.6.1.14) to convert pyruvate, hydroxypyruvate and glyoxylate into the corresponding amino acids (Zhang et al , 2013). The 2-oxosuccinamate (2OS) produced is hydrolysed to oxaloacetate and ammonia by ω-amidase (Streeter, 1977; Zhang and Marsolais, 2014).…”

Section: Introductionmentioning

confidence: 99%

High serine:glyoxylate aminotransferase activity lowers leaf daytime serine levels, inducing the phosphoserine pathway in Arabidopsis

Modde

Timm

Florian

et al. 2016

EXBOTJ

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Characterization of Arabidopsis serine:glyoxylate aminotransferase, AGT1, as an asparagine aminotransferase

Cited by 51 publications

References 43 publications

The changes of contents of selected free amino acids associated with cadmium stress in Noccaea caerulescens and Arabidopsis halleri

The changes of contents of selected free amino acids associated with cadmium stress in Noccaea caerulescens and Arabidopsis halleri

Impact of the Disruption of ASN3-Encoding Asparagine Synthetase on Arabidopsis Development

High serine:glyoxylate aminotransferase activity lowers leaf daytime serine levels, inducing the phosphoserine pathway in Arabidopsis

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