Carbon and amino acids reciprocally modulate the expression of glutamine synthetase in Arabidopsis

Igor C. Oliveira, Gloria M. Coruzzi

Research output: Contribution to journalArticle

Abstract

In bacteria and yeast, glutamine synthetase (GS) expression is tightly regulated by the metabolic status of the cell, both at the transcriptional and posttranscriptional levels. We discuss the relative contributions of light and metabolic cues on the regulation of members of the GS gene family (chloroplastic GS2 and cytosolic GS1) in Arabidopsis. These studies reveal that the dramatic induction of mRNA for chloroplastic GS2 by light is mediated in part by phytochrome and in part by light-induced changes in sucrose (Suc) levels. In contrast, the modest induction of mRNA for cytosolic GS1 by light is primarily mediated by changes in the levels of carbon metabolites. Suc induction of mRNA for GS2 and GS1 occurs in a time- and dose-dependent manner. Suc-induced changes in GS mRNA levels were also observed at the level of GS enzyme activity. In contrast, amino acids were shown to antagonize the Suc induction of GS, both at the level of mRNA accumulation and that of enzyme activity. For GS2, the gene whose expression was the most dramatically regulated by metabolites, we used a GS2 promoter-β-glucuronidase fusion to demonstrate that transcriptional control is involved in this metabolic regulation. Our results suggest that the metabolic regulation of GS expression in plants is controlled by the relative abundance of carbon skeletons versus amino acids. This would allow nitrogen assimilation into glutamine to proceed (or not) according to the metabolic status and biosynthetic needs of the plant. This type of GS gene regulation is reminiscent of the nitrogen regulatory system in bacteria, and suggests an evolutionary link between metabolic sensing and signaling in bacteria and plants.

Original languageEnglish (US)
Pages (from-to)301-309
Number of pages9
JournalPlant Physiology
Volume121
Issue number1
StatePublished - Sep 1999

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glutamate-ammonia ligase
Arabidopsis
amino acids
carbon
sucrose
bacteria
enzyme activity
metabolites
nitrogen
phytochrome
glutamine
skeleton
assimilation (physiology)
genes
promoter regions
yeasts
gene expression
dosage

ASJC Scopus subject areas

  • Plant Science

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Carbon and amino acids reciprocally modulate the expression of glutamine synthetase in Arabidopsis. / Oliveira, Igor C.; Coruzzi, Gloria M.

In: Plant Physiology, Vol. 121, No. 1, 09.1999, p. 301-309.

Research output: Contribution to journalArticle

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