Effect of some heavy metal ions on copper-induced metallothionein synthesis in the yeast Saccharomyces cerevisiae

Authors: Okuyama M-a.¹; Kobayashi Y.²; Inouhe M.²; Tohoyama H.²; Joho M.²

Source: BioMetals, Volume 12, Number 4, December 1999 , pp. 307-314(8)

Publisher: Springer

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Abstract:

Copper-induced metallothionein (MT) synthesis in Saccharomyces cerevisiae was investigated in order to associate this exclusively with Cu^2+ 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 Cd^2+ and Mn^2+. By adding Cd^2+ and Mn^2+ at 10 mgr M concentration, the bgr -galactosidase activity decreased by about 80% and 50% of the maximum induction observed with 1 mM CuSO_4, respectively. Furthermore, cell growth was markedly inhibited by combinations of 1 mM-Cu^2+ and 1 mgr M-Cd^2+. Therefore, the yeast S. cerevisiae could not rely on MT synthesis as one of the copper-resistance mechanisms, when grown in a Cd^2+ environment. In contrast, the presence of Mn^2+ in the nutrient medium showed alleviation rather than growth inhibition by high concentrations of Cu^2+. The recovery from growth inhibition by Mn^2+ was due to decreased Cu^2+ accumulation. Inhibitory concentrations of Co^2+, Ni^2+ and Zn^2+ on expression of the CUP1p/lacZ fusion gene were at least one order of magnitude higher than that of Cd^2+ and Mn^2+. These results are discussed in relation to Cu^2+ transport and Cu-induced MT synthesis in the copper-resistance mechanism of the yeast S. cerevisiae.

Keywords: copper; metal ions; metallothionein; yeast Saccharomyces cerevisiae

Language: English

Document Type: Regular paper

Affiliations: 1: Ehime Prefectural Institute of Public Health and Environmental Science, Sanban-cho, Matsuyama, 790-0003, Japan 2: Department of Biology, Faculty of Science, Ehime University, Matsuyama, 790-8577, Japan

Publication date: 1999-12-01