The glutathione-deficient, cadmium-sensitive mutant, cad2-1, of Arabidopsis thaliana is deficient in gamma-glutamylcysteine synthetase

Plant J. 1998 Oct;16(1):73-8. doi: 10.1046/j.1365-313x.1998.00262.x.


This paper reports that the glutathione (GSH)-deficient mutant, cad2-1, of Arabidopsis is deficient in the first enzyme in the pathway of GSH biosynthesis, gamma-glutamylcysteine synthetase (GCS). The mutant accumulates a substrate of GCS, cysteine, and is deficient in the product, gamma-glutamylcysteine. In vitro enzyme assays showed that the cad2-1 mutant has 40% of wild-type levels of GCS activity but is unchanged in the activity of the second enzyme in the pathway, GSH synthetase. The CAD2 locus maps to chromosome 4 and is tightly linked to a gene, GSHA, identified by a previously isolated cDNA. A genomic clone of GSHA complements both the phenotypic and biochemical deficiencies of the cad2-1 mutant. The nucleotide sequence of the gene has been determined and, in the mutant, this gene contains a 6 bp deletion within an exon. These data demonstrate that the CAD2 gene encodes GCS. The cad2-1 mutation is close to the conserved cysteine which is believed to bind the substrate glutamate and the specific inhibitor L-buthionine-[S,R] sulfoximine (BSO). Both root growth and GCS activity of the cad2-1 mutant was less sensitive than the wild-type to inhibition by BSO, indicating that the mutation may alter the affinity of the inhibitor binding site.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alcohol Oxidoreductases / genetics
  • Alcohol Oxidoreductases / metabolism
  • Amino Acid Sequence
  • Arabidopsis / enzymology*
  • Arabidopsis / genetics*
  • Base Sequence
  • Cadmium / pharmacology*
  • Chromosome Mapping
  • Dipeptides / metabolism
  • Genes, Plant
  • Glutamate-Cysteine Ligase / deficiency*
  • Glutamate-Cysteine Ligase / genetics*
  • Glutathione / deficiency*
  • Molecular Sequence Data
  • Plant Proteins / genetics
  • Plant Proteins / metabolism
  • Polymorphism, Restriction Fragment Length


  • Dipeptides
  • Plant Proteins
  • Cadmium
  • Alcohol Oxidoreductases
  • cinnamyl alcohol dehydrogenase
  • Glutamate-Cysteine Ligase
  • Glutathione
  • gamma-glutamylcysteine

Associated data

  • GENBANK/AF068299