Reciprocal regulation of distinct asparagine synthetase genes by light and metabolites in Arabidopsis thaliana

Hon Ming Lam, Ming Hsiun Hsieh, Gloria Coruzzi

Research output: Contribution to journalArticle

Abstract

In plants, the amino acid asparagine serves as an important nitrogen transport compound whose levels are dramatically regulated by light in many plant species, including Arabidopsis thaliana. To elucidate the mechanisms regulating the flux of assimilated nitrogen into asparagine, we examined the regulation of the gene family for asparagine synthetase in Arabidopsis. In addition to the previously identified ASN1 gene, we identified a novel class of asparagine synthetase genes in Arabidopsis (ASN2 and ASN3) by functional complementation of a yeast asparagine auxotroph. The proteins encoded by the ASN2/3 cDNAs contain a Pur-F type glutamine-binding triad suggesting that they, like ASN1, encode glutamine-dependent asparagine synthetase isoenzymes. However, the ASN2/3 isoenyzmes form a novel dendritic group with monocot AS genes which is distinct from all other dicot AS genes including Arabidopsis ASN1. In addition to these distinctions in sequence, the ASN1 and ASN2 genes are reciprocally regulated by light and metabolites. Time-course experiments reveal that light induces levels of ASN2 mRNA while it represses levels of ASN1 mRNA in a kinetically reciprocal fashion. Moreover, the levels of ASN2 and ASN1 mRNA are also reciprocally regulated by carbon and nitrogen metabolites. The distinct regulation of ASN1 and ASN2 genes combined with their distinct encoded isoenzymes suggest that they may play different roles in nitrogen metabolism, as discussed in this paper.

Original languageEnglish (US)
Pages (from-to)345-353
Number of pages9
JournalPlant Journal
Volume16
Issue number3
DOIs
StatePublished - Nov 1998

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Aspartate-Ammonia Ligase
aspartate-ammonia ligase
Arabidopsis
Arabidopsis thaliana
metabolites
Light
Asparagine
Genes
asparagine
genes
Nitrogen
Glutamine
glutamine
Messenger RNA
Isoenzymes
isozymes
nitrogen
Nitrogen Compounds
auxotrophs
nitrogen metabolism

ASJC Scopus subject areas

  • Plant Science

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Reciprocal regulation of distinct asparagine synthetase genes by light and metabolites in Arabidopsis thaliana. / Lam, Hon Ming; Hsieh, Ming Hsiun; Coruzzi, Gloria.

In: Plant Journal, Vol. 16, No. 3, 11.1998, p. 345-353.

Research output: Contribution to journalArticle

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