The role of glutathione biosynthesis in heavy metal resistance in the fission yeast Schizosaccharomyces pombe.
Plants and the fission yeast Schizosaccharomyces pombe synthesize small cadmium-binding peptides, called phytochelatins, in response to cadmium. Derived from glutathione (GSH: gamma-Glu-Cys-Gly), they have the general structure (gamma-Glu-Cys)nGly, where n is 2-11. In order to study the biosynthesis of phytochelatins, we used the mutagen N-methyl-N'-nitro-N nitrosoguanidine (MNNG) to select mutants with a lowered GSH content. GSH-deficient mutants show a Cd-sensitive phenotype, whereas resistance to Cu is only slightly influenced. These Cd-sensitive mutants contain 2-15% of the wild-type GSH level. For three mutants a lowered activity of gamma-glutamylcysteine synthetase was measured. One of the mutants was transformed to Cd-resistance and the complementing fragment was analyzed further. The complementing fragment hybridized with chromosome III. In the transformants, GSH content was restored up to wild-type levels, whereas the activity of gamma-glutamylcysteine synthetase was significantly increased compared with the wild-type. Possible mechanisms for Cd-resistance in the transformants are discussed.
Coblenz
A
A
Institut für Biologie IV (Mikrobiologie), Rheinisch-Westfälische Technische Hochschule Aachen, FRG.
Wolf
K
K
D002104:Cadmium / Q000494:pharmacology*; D003300:Copper / Q000494:pharmacology; D004351:Drug Resistance; D005978:Glutathione / Q000096:biosynthesis*; D008667:Metalloproteins / Q000096:biosynthesis; D009154:Mutation; D054811:Phytochelatins; D010940:Plant Proteins / Q000096:biosynthesis; D012568:Schizosaccharomyces / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic
D008667:Metalloproteins; D010940:Plant Proteins; D002104:Cadmium; D003300:Copper; D054811:Phytochelatins; D005978:Glutathione