The role of glutathione biosynthesis in heavy metal resistance in the fission yeast Schizosaccharomyces pombe |
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Authors: | Anke Coblenz Klaus Wolf |
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Institution: | lnstitut fiir Biologie IV (Mikrobiologie), Rheinisch-Westfälische Technische Hochsehule Aachen, Worringer Weg, D-52056 Aachen, FRG |
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Abstract: | Abstract: Plants and the fission yeast Schizosaccharomyces pombe synthesize small cadmium-binding peptides, called phytochelatins, in response to cadmium. Derived from glutathione (GSH: λ-Glu-Cys-Gly), they have the general structure (λ-Glu-Cys) n Gly, 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 λ-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 λ-glutamylcysteine synthetase was significantly increased compared with the wild-type. Possible mechanisms for Cd-resistance in the transformants are discussed. |
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Keywords: | Schizosaccharomyces pombe Glutathione Cadmium λ-Glutamylcysteine synthetase Phytochelatins |
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