Single point mutations in Met4p impair the transcriptional repression of MET genes in Saccharomyces cerevisiae.
Transcription of MET genes in Saccharomyces cerevisiae depends on a transcriptional activator, the MET4 gene product (Met4p). Using in vitro mutagenesis, we isolated two mutant MET4 alleles encoding [Pro215]Met4p and [Ser156]Met4p. These mutations impeded Met4p's responsiveness to methionine in the media, and yeast cells carrying mutant alleles exhibited enhanced transcription of MET genes under repressing conditions. The enhanced transcription was dependent on the CBF1 gene, but did not compete with an excess of wild-type Met4p, suggesting that some changes in the affinity of Met4p to other factors might be involved in S-adenosylmethionine-mediated transcriptional regulation.
Omura
F
F
Institute for Fundamental Research, Suntory Ltd., Osaka, Japan. omura@nisiq.net
Fujita
A
A
Shibano
Y
Y
D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; D004271:DNA, Fungal; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D008715:Methionine / Q000378:metabolism*; D008969:Molecular Sequence Data; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D050976:Basic-Leucine Zipper Transcription Factors; C064042:CBF1 protein, S cerevisiae; D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C073675:MET4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D008715:Methionine