Effect of some heavy metal ions on copper-induced metallothionein synthesis in the yeast Saccharomyces cerevisiae.
Copper-induced metallothionein (MT) synthesis in Saccharomyces cerevisiae was investigated in order to associate this exclusively with Cu2+ in vivo, when cultured in nutrient medium containing other heavy metal ions. Expression of the CUP1 promoter/lacZ fusion gene was inhibited by all heavy metal ions tested, especially Cd2+ and Mn2+. By adding Cd2+ and Mn2+ at 10 microM concentration, the beta-galactosidase activity decreased by about 80% and 50% of the maximum induction observed with 1 mM CuSO4, respectively. Furthermore, cell growth was markedly inhibited by combinations of 1 mM-Cu2+ and 1 microM-Cd2+. Therefore, the yeast S. cerevisiae could not rely on MT synthesis as one of the copper-resistance mechanisms, when grown in a Cd2+ environment. In contrast, the presence of Mn2+ in the nutrient medium showed alleviation rather than growth inhibition by high concentrations of Cu2+. The recovery from growth inhibition by Mn2+ was due to decreased Cu2+ accumulation. Inhibitory concentrations of Co2+, Ni2+ and Zn2+ on expression of the CUP1p/lacZ fusion gene were at least one order of magnitude higher than that of Cd2+ and Mn2+. These results are discussed in relation to Cu2+ transport and Cu-induced MT synthesis in the copper-resistance mechanism of the yeast S. cerevisiae.
Okuyama
M
M
Ehime Prefectural Institute of Public Health and Environmental Science, Matsuyama, Japan.
Kobayashi
Y
Y
Inouhe
M
M
Tohoyama
H
H
Joho
M
M
D002104:Cadmium / Q000494:pharmacology; D002413:Cations, Divalent / Q000494:pharmacology*; D003300:Copper / Q000494:pharmacology*; D019327:Copper Sulfate / Q000494:pharmacology; D007700:Kinetics; D008345:Manganese / Q000494:pharmacology; D008668:Metallothionein / Q000096:biosynthesis* / Q000235:genetics; D019216:Metals, Heavy / Q000494:pharmacology*; D009532:Nickel / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015032:Zinc / Q000494:pharmacology; D001616:beta-Galactosidase / Q000235:genetics
D002413:Cations, Divalent; D019216:Metals, Heavy; D011993:Recombinant Fusion Proteins; D002104:Cadmium; D008345:Manganese; D003300:Copper; D009532:Nickel; D008668:Metallothionein; D001616:beta-Galactosidase; D015032:Zinc; D019327:Copper Sulfate