MET3 promoter: A tightly regulated promoter and its application in construction of conditional lethal strain

The beta-galactosidase activity driven by MET3 promoter was assayed in the absence of methionine and in the presence of different concentration of methionine in medium. To compare its activity with GAL1 promoter and the data reported by Mumburg about MET25 promoter, the MET3 promoter was a weak but tightly controlled promoter. Its successful application in the construction of methionine-sensitive tri-mutant (cln1Deltacln2Deltapho85Delta) demonstrated that the MET3 promoter is a useful promoter in construction of conditional lethal strain and heterologous expression in Saccharomyces cerevisiae.