TY - JOUR

T1 - Glutamate in plants: metabolism, regulation and signalling

AU - Forde, Brian

AU - Lea, Peter

PY - 2007

Y1 - 2007

N2 - Glutamate occupies a central position in amino acidmetabolism in plants. The acidic amino acid is formedby the action of glutamate synthase, utilizing glutamineand 2-oxoglutarate. However, glutamate is alsothe substrate for the synthesis of glutamine fromammonia, catalysed by glutamine synthetase. Thea-amino group of glutamate may be transferred toother amino acids by the action of a wide range ofmultispecific aminotransferases. In addition, both thecarbon skeleton and a-amino group of glutamate formthe basis for the synthesis of g-aminobutyric acid,arginine, and proline. Finally, glutamate may bedeaminated by glutamate dehydrogenase to formammonia and 2-oxoglutarate. The possibility that thecellular concentrations of glutamate within the plantare homeostatically regulated by the combined actionof these pathways is examined. Evidence that the well knownsignalling properties of glutamate in animalsmay also extend to the plant kingdom is reviewed. Theexistence in plants of glutamate-activated ion channelsand their possible relationship to the GLR gene familythat is homologous to ionotropic glutamate receptors(iGluRs) in animals are discussed. Glutamate signallingis examined from an evolutionary perspective, andthe roles it might play in plants, both in endogenoussignalling pathways and in determining the capacity ofthe root to respond to sources of organic N in the soil,are considered.

AB - Glutamate occupies a central position in amino acidmetabolism in plants. The acidic amino acid is formedby the action of glutamate synthase, utilizing glutamineand 2-oxoglutarate. However, glutamate is alsothe substrate for the synthesis of glutamine fromammonia, catalysed by glutamine synthetase. Thea-amino group of glutamate may be transferred toother amino acids by the action of a wide range ofmultispecific aminotransferases. In addition, both thecarbon skeleton and a-amino group of glutamate formthe basis for the synthesis of g-aminobutyric acid,arginine, and proline. Finally, glutamate may bedeaminated by glutamate dehydrogenase to formammonia and 2-oxoglutarate. The possibility that thecellular concentrations of glutamate within the plantare homeostatically regulated by the combined actionof these pathways is examined. Evidence that the well knownsignalling properties of glutamate in animalsmay also extend to the plant kingdom is reviewed. Theexistence in plants of glutamate-activated ion channelsand their possible relationship to the GLR gene familythat is homologous to ionotropic glutamate receptors(iGluRs) in animals are discussed. Glutamate signallingis examined from an evolutionary perspective, andthe roles it might play in plants, both in endogenoussignalling pathways and in determining the capacity ofthe root to respond to sources of organic N in the soil,are considered.

KW - glutamate

KW - SIGNALING

KW - Metabolism

KW - glutamate receptor

U2 - 10.1093/jxb/erm121

DO - 10.1093/jxb/erm121

M3 - Literature review

VL - 58

SP - 2339

EP - 2358

JO - Journal of Experimental Botany

JF - Journal of Experimental Botany

SN - 1460-2431

IS - 9

ER -