Saccharomyces cerevisiae O-acetylhomoserine sulfhydrylase (MET17/MET25/MET15) promoter
Methionine-repressible promoter of the S. cerevisiae MET17 gene (also called MET25 or MET15), which encodes O-acetyl homoserine sulphydrylase in sulfur amino acid biosynthesis. Methionine in the medium represses the promoter in a graded, logarithmic way, so expression is set by medium methionine concentration rather than a chemical inducer (Mumberg et al. 1994).
Origin: Saccharomyces cerevisiae
Characteristics
Expression is repressed by methionine and by S-adenosylmethionine, its metabolic derivative, and is highest in methionine-free medium. In lacZ fusions in strain YPH499, beta-galactosidase activity ranged from 550 U for the 2-micron plasmid without methionine to 9 U for the centromeric plasmid with 1 mM methionine, falling logarithmically as methionine rose. 1 mM methionine left about 10% residual activity (Mumberg et al. 1994).
Applications: Conditional expression of heterologous genes and reporters in S. cerevisiae at levels set by medium methionine, on low-copy centromeric or high-copy 2-micron vectors (Mumberg et al. 1994). Suited to cases where a graded, methionine-adjustable level is wanted and galactose or copper additions are undesirable.
Limitations: Repression is incomplete. 1 mM methionine left about 10% of the beta-galactosidase activity seen without methionine, estimated with the very stable lacZ product (Mumberg et al. 1994). In the same comparison no GAL1-derived vector showed significant activity under repressing conditions. Full expression requires methionine-free medium.
Sequence
References
- Mumberg et al. (1994). Regulatable promoters of Saccharomyces cerevisiae: comparison of transcriptional activity and their use for heterologous expression. Nucleic Acids Res - Mumberg 1994 Regulatable Promoters