Cyclin-dependent protein kinase and cyclin homologs SSN3 and SSN8 contribute to transcriptional control in yeast.
The SSN3 and SSN8 genes of Saccharomyces cerevisiae were identified by mutations that suppress a defect in SNF1, a protein kinase required for release from glucose repression. Mutations in SSN3 and SSN8 also act synergistically with a mutation of the MIG1 repressor protein to relieve glucose repression. We have cloned the SSN3 and SSN8 genes. SSN3 encodes a cyclin-dependent protein kinase (cdk) homolog and is identical to UME5. SSN8 encodes a cyclin homolog 35% identical to human cyclin C. SSN3 and SSN8 fusion proteins interact in the two-hybrid system and coimmunoprecipitate from yeast cell extracts. Using an immune complex assay, we detected protein kinase activity that depends on both SSN3 and SSN8. Thus, the two SSN proteins are likely to function as a cdk-cyclin pair. Genetic analysis indicates that the SSN3-SSN8 complex contributes to transcriptional repression of diversely regulated genes and also affects induction of the GAL1 promoter.
Kuchin
S
S
Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Yeghiayan
P
P
Carlson
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D056850:Cyclin-Dependent Kinase 8; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism; D004330:Drosophila; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000096:biosynthesis
D016213:Cyclins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C093345:SSN8 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D056850:Cyclin-Dependent Kinase 8; D018844:Cyclin-Dependent Kinases; C498309:SSN3 protein, S cerevisiae; D001616:beta-Galactosidase