Induction for the expression of yeast metallothionein gene, CUP1, by cobalt

Induction for the expression of the metallothionein gene, CUP1, in the yeast Saccharomyces cerevisiae by cobalt was examined using a reporter gene with the promoter of this gene fused to the coding region of lacZ. The expression of the gene was induced by cobalt as well as by copper and silver ions. The activity of beta-galactosidase showed high levels after treatment with 1.0 mM cobalt chloride. It has been reported that the induction for the transcription of CUP1 by copper and silver is mediated by the Ace1 transcription factor. However, the expression of the gene by cobalt occurred in yeast cells lacking the Ace1 factor. These results suggest the presence of a novel cobalt-specific transcription factor for the CUP1 gene.