Metal(loid)s and radionuclides cytotoxicity in Saccharomyces cerevisiae. Role of YCF1, glutathione and effect of buthionine sulfoximine.
The presence of heavy metal(loid)s in soils and waters is an important issue with regards to human health. Taking into account speciation problems, in the first part of this report, we investigated under identical growth conditions, yeast tolerance to a set of 15 cytotoxic metal(loid)s and radionuclides. The yeast cadmium factor 1 (YCF1) is an ATP-Binding Cassette transporter mediating the glutathione detoxification of heavy metals. In the second part, metal(loid)s that could be handled by YCF1 and a possible re-localisation of the transporter after heavy metal exposure were evaluated. YCF1 and a C-terminal GFP fusion, YCF1-GFP, were overexpressed in wild-type and Deltaycf1 strains. Both forms were functional, conferring a tolerance to Cd, Sb, As, Pb, Hg but not to Ni, Zn, Cu, Ag, Se, Te, Cr, Sr, Tc, U. Confocal experiments demonstrated that during exposure to cytotoxic metals, the localisation of YCF1-GFP was restricted to the yeast vacuolar membrane. In the last part, the role of glutathione in this resistance mechanism to metal(loid)s was studied. In the presence of heavy metals, application of buthionine sulfoximine (BSO), a well-known inhibitor of gamma-glutamylcysteine synthetase, led to a decrease in the cytosolic pool of GSH and to a limitation of yeast growth. Surprisingly, BSO was able to phenocopy the deletion of gamma-glutamylcysteine synthetase after exposure to Cd but not to Sb or As. In the genetic context of gsh1 and gsh2 yeast mutants, the critical role of GSH for Cd, As, Sb and Hg tolerance was compared to that of wild-type and Deltaycf1.
Prévéral
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CEA Cadarache, DSV-DEVM-LEMS, UMR 6191 CNRS-CEA-Université Aix-Marseille II, 13108 St Paul lez Durance, France.
Ansoborlo
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Mari
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Vavasseur
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Forestier
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D018528:ATP-Binding Cassette Transporters / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D019328:Buthionine Sulfoximine / Q000494:pharmacology*; D005978:Glutathione / Q000378:metabolism*; D008658:Inactivation, Metabolic; D008627:Mercuric Chloride / Q000633:toxicity; D008670:Metals / Q000633:toxicity*; D010957:Plasmids; D011868:Radioisotopes / Q000633:toxicity*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000187:drug effects* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D008670:Metals; D011868:Radioisotopes; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C089179:YCF1 protein, S cerevisiae; D019328:Buthionine Sulfoximine; D008627:Mercuric Chloride; D005978:Glutathione