ISSN:
1573-5028
Keywords:
Arabidopsis
;
glutathione
;
heavy metals
;
phytochelatin
;
Schizosaccharomyces pombe
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract Glutathione is essential for protecting plants from a range of environmental stresses, including heavy metals where it acts as a precursor for the synthesis of phytochelatins. A 1658 bp cDNA clone for glutathione synthetase (gsh2) was isolated fromArabidopsis thaliana plants that were actively synthesizing glutathione upon exposure to cadmium. The sequence of the clone revealed a protein with an estimated molecular mass of 53858 Da that was very similar to the protein from higher eukaryotes, was less similar to the gene from the fission yeast,Schizosaccharomyces pombe, and shared only a small region of similarity with theEscherichia coli protein. A 4.3 kbSstI fragment containing the genomic clone for glutathione synthetase was also isolated and sequenced. A comparison of the cDNA and genomic sequences revealed that the gene was composed of twelve exons. When theArabidopsis cDNA cloned in a special shuttle vector was expressed in aS. pombe mutant deficient in glutathione synthetase activity, the plant cDNA was able to complement the yeast mutation. Glutathione synthetase activity was measurable in wild-type yeast cells, below detectable levels in thegsh2 - mutant, and restored to substantial levels by the expression of theArabidopsis cDNA. TheS. pombe mutant expressing the plant cDNA had near wild type levels of total cellular thiols,109Cd2+ binding activity, and cadmium resistance. Since theArabidopsis cDNA was under control of a thiamine-repressible promoter, growth of the transformed yeast on thiamine-free medium increased expression of the cDNA resulting in increases in cadmium resistance.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00040827
