Role and regulation of L-glutamate dehydrogenase activity in higher plants

Srivastava, H. S.; Singh, Rana Pratap

doi:10.1016/s0031-9422(00)84749-4

Cited by 240 publications

(148 citation statements)

References 179 publications

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“…In the citrus database, this enzyme was found in leaves, fruits and bark, but it was not possible to differentiate between the two enzyme forms. Sick plants have decreased expression and stressed plants did not express it, which agrees with the findings that the GDH isoenzymatic profile can be influenced by dark stress, natural senescence or fruit ripening (Srivastava and Singh-Rana, 1987).…”

Section: Searched Enzymessupporting

confidence: 90%

Nitrogen assimilation in Citrus based on CitEST data mining

et al. 2007

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Assimilation of nitrate and ammonium are vital procedures for plant development and growth. From these primary paths of inorganic nitrogen assimilation, this metabolism integrates diverse paths for biosynthesis of macromolecules, such as amino acids and nucleotides, and the central intermediate metabolism, like carbon metabolism and photorespiration. This paper reports research performed in the CitEST (Citrus Expressed Sequence Tag) database for the main genes involved in nitrogen metabolism and those previously described in other organisms. The results show that a complete cluster of genes involved in the assimilation of nitrogen and the metabolisms of glutamine, glutamate, aspartate and asparagine can be found in the CitEST data. The main enzymes found were nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthetase (GOGAT), glutamate dehydrogenase (GDH), aspartate aminotransferase (AspAT) and asparagine synthetase (AS). The different enzymes involved in this metabolism have been shown to be highly conserved among the Citrus and Poncirus species. This work serves as a guide for future functional analysis of these enzymes in citrus.

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Section: Searched Enzymessupporting

confidence: 90%

Nitrogen assimilation in Citrus based on CitEST data mining

et al. 2007

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“…It catalyses the reaction of NH 4 + with glutamate to glutamine with the aid of ATP (Choi & Kwon 1998). GDH-NADH also operates in the assimilation of NH 4 + thereby complementing the enzymes of the GS-GOGAT cycle in the synthesis of glutamate, especially under conditions of stress (Srivastava & Singh 1987).…”

Section: Introductionmentioning

confidence: 99%

Effects of different ammoniacal nitrogen sources on N-metabolism of the atmospheric bromeliad Tillandsia pohliana Mez

Tamaki

Mercier

2001

Rev. bras. Bot.

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-(Effects of different ammoniacal nitrogen sources on N-metabolism of the atmospheric bromeliad Tillandsia pohliana Mez). Increasing levels of atmospheric ammonia from anthropogenic sources have become a serious problem for natural vegetation. Short-term effects of different ammoniacal sources on the N metabolism of Tillandsia pohliana, an atmospheric bromeliad, were investigated. One-year-old, aseptically grown plants were transferred to a modified Knudson medium lacking N for three weeks. Plants were subsequently transferred to Knudson media supplemented with 0.5, 1.0, or 1.5 mM of N in the forms of NH 3 or NH 4 + as the sole N source. The activities of glutamine synthetase (GS) and glutamate dehydrogenase (GDH-NADH) were determined after 40 h. The GS activity was stimulated significantly by increasing the levels of the gaseous form. The GDH-NADH activity increased significantly under increasing N concentrations with NH 3 , while no significant differences were observed with NH 4 + as a N source. These results may reflect a faster NH 3 absorption by T. pohliana compared to NH 4 + uptake. The increased activity of GDH-NADH in NH 3 treatment may play a role in protecting the cells from the toxic effects of increased endogenous level of free ammonium. A raise in the concentration of N, especially in the form of NH 3 , greatly increased the content of free amino acids and soluble proteins. A possible utilisation of T. pohliana to evaluate the changes of atmospheric gaseous ammonia is proposed.RESUMO -(Efeitos de diferentes fontes amoniacais sobre o metabolismo de nitrogênio da bromélia atmosférica Tillandsia pohliana Mez). As fontes antropogênicas de amônia atmosférica têm se tornado um problema sério para a vegetação natural. No presente trabalho foram analisados os efeitos da aplicação de diferentes fontes amoniacais sobre o metabolismo do nitrogênio de Tillandsia pohliana, uma bromélia atmosférica. As sementes foram germinadas in vitro e as plantas cresceram em meio de cultura de Knudson por um ano. Após esse período, elas foram transferidas para o meio de Knudson sem as fontes nitrogenadas originais. Três semanas depois, as plantas foram colocadas nesse mesmo meio de cultura, porém, suplementado com 0,5, 1,0 ou 1,5 mM de N nas formas de NH 3 ou NH 4 + como fontes únicas de nitrogênio. O tempo de exposição a essas fontes foi de 40 h. As atividades enzimáticas da glutamina sintetase (GS) e da glutamato desidrogenase (GDH-NADH) foram analisadas. Os teores endógenos de amônio, de aminoácidos livres e de proteínas solúveis, presentes nos eixos caulinares dessa bromélia, também, foram determinados. As atividades da GS e da GDH-NADH foram estimuladas, significativamente, com o aumento do nitrogênio na forma gasosa. Esses resultados podem refletir a rápida absorção de NH 3 pela planta. Entretanto, a atividade aminante da GDH não apresentou diferença significativa em resposta ao aumento do N na forma de NH 4 + . Provavelmente, o incremento na atividade da GDH-NADH, no tratamento com NH 3 , está relacionado com...

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“…It was proposed that ammonium might be directly incorporated into Glu by amination of 2-oxoglutarate via mitochondrial Glu dehydrogenase (NADH-GDH; EC 1.4.1.2) and subsequently into Gln by cytosolic GS1 under particular physiological conditions. Studies on source-sink relations have shown that GDH is induced in old leaves when nitrogen remobilization is maximal (Srivastava and Singh, 1987;Masclaux et al, 2000). This led to the proposal that the physiological role of GDH is to synthesize Glu for translocation in senescing leaves (for review, see Miflin and Habash, 2002).…”

mentioning

confidence: 99%

Glutamine Synthetase-Glutamate Synthase Pathway and Glutamate Dehydrogenase Play Distinct Roles in the Sink-Source Nitrogen Cycle in Tobacco

et al. 2006

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Glutamate (Glu) metabolism and amino acid translocation were investigated in the young and old leaves of tobacco (Nicotiana tabacum L. cv Xanthi) using [15N]ammonium and [2-15N]Glu tracers. Regardless of leaf age, [15N]ammonium assimilation occurred via glutamine synthetase (GS; EC 6.1.1.3) and Glu synthase (ferredoxin [Fd]-GOGAT; EC 1.4.7.1; NADH-GOGAT; EC 1.4.1.14), both in the light and darkness, and it did not depend on Glu dehydrogenase (GDH; EC 1.4.1.2). The [15N]ammonium and ammonium accumulation patterns support the role of GDH in the deamination of [2-15N]Glu to provide 2-oxoglutarate and [15N]ammonium. In the dark, excess [15N]ammonium was incorporated into asparagine that served as an additional detoxification molecule. The constant Glu levels in the phloem sap suggested that Glu was continuously synthesized and supplied into the phloem regardless of leaf age. Further study using transgenic tobacco lines, harboring the promoter of the GLU1 gene (encoding Arabidopsis [Arabidopsis thaliana] Fd-GOGAT) fused to a GUS reporter gene, revealed that the expression of Fd-GOGAT remained higher in young leaves compared to old leaves, and higher in the veins compared to the mesophyll. Confocal laser-scanning microscopy localized the Fd-GOGAT protein to the phloem companion cells-sieve element complex in the leaf veins. The results are consistent with a role of Fd-GOGAT in supplying Glu for the synthesis and transport of amino acids. Taken together, the data provide evidence that the GS-GOGAT pathway and GDH play distinct roles in the source-sink nitrogen cycle of tobacco leaves.

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Role and regulation of L-glutamate dehydrogenase activity in higher plants

Cited by 240 publications

References 179 publications

Nitrogen assimilation in Citrus based on CitEST data mining

Nitrogen assimilation in Citrus based on CitEST data mining

Effects of different ammoniacal nitrogen sources on N-metabolism of the atmospheric bromeliad Tillandsia pohliana Mez

Glutamine Synthetase-Glutamate Synthase Pathway and Glutamate Dehydrogenase Play Distinct Roles in the Sink-Source Nitrogen Cycle in Tobacco

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