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

Induction for the expression of the metallothionein gene, CUPS, in the yeas t Saccharomyces cerevisiae by cobalt was examined using a reporter gene wit h the promoter of this gene fused to the coding region of lacZ. The express ion 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 wit h 1.0 mM cobalt chloride. It has been reported that the induction for the t ranscription of CUP1 by copper and silver is mediated by the Ace1 transcrip tion factor. However, the expression of the gene by cobalt occurred in yeas t cells lacking the Ace1 factor. These results suggest the presence of a no vel cobalt-specific transcription factor for the CUP1 gene.