GC-MS based metabolite profiling implies three interdependent ways of ammonium assimilation in Medicago truncatula root nodules.

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Barsch A, Carvalho HG, Cullimore JV, Niehaus K

GC-MS based metabolite profiling implies three interdependent ways of ammonium assimilation in Medicago truncatula root nodules.

J Biotechnol. 2006 Dec 15;127(1):79-83. Epub 2006 Jun 21.

PubMed ID

16870293 [ View in PubMed

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Abstract

In symbiotic interaction with legume plants, bacteria termed Rhizobia can fix massive amounts of atmospheric nitrogen which is primarily provided in the form of ammonium to the host plants. Therefore, legume root nodules that house the symbiotic bacteria are ideally suited to study the process of primary ammonium assimilation. Here, we present a GC-MS based metabolite profiling analysis of Medicago truncatula root nodules (induced by the bacterium Sinorhizobium meliloti) before and after inhibition of glutamine synthetase (GS) by the chemical herbicide phosphinotricine. The primary role of GS in ammonium assimilation was revealed by drastically reduced levels of glutamine in phosphinotricine treated root nodules. In comparison to previous results of increased asparagine synthetase transcript and protein abundances in GS inhibited nodules the metabolic data revealed that decreased amounts of aspartate might preclude taking advantage of this elevated enzymatic activity. A potential role of glutamate dehydrogenase in ammonium assimilation was metabolically indicated 24 and 48 h after GS inhibition. Therefore, nodule ammonium assimilation might in principle involve three interdependent metabolic pathways which are adjusted to control basic nitrogen metabolism.

DrugBank Data that Cites this Article

Drug Enzymes

Drug	Enzyme	Kind	Organism	Pharmacological Action	Actions
L-Glutamine	Asparagine synthetase [glutamine-hydrolyzing]	Protein	Humans	Unknown	Substrate	Details