MAT alpha 1 can mediate gene activation by a-mating factor.
In the yeast Saccharomyces cerevisiae, expression of alpha-specific genes is governed by the MAT alpha 1 and MCM1 gene products. MAT alpha 1 and MCM1 bind cooperatively to PQ elements upstream of alpha-specific genes. The PQ element not only directs alpha-specific expression but can also direct gene induction in response to treatment with a-mating pheromone. We have used gene fusions to investigate whether induction conferred by the PQ box is mediated through either MAT alpha 1 or MCM1, or a combination of both. When MCM1 is fused to the DNA-binding domain of the bacterial repressor LexA, this fusion protein is capable of trans-activating a lacZ reporter gene driven by a LexA operator. However, the transcriptional activity of the MCM1-LexA fusion is not further enhanced by treatment of cells with a-factor. A MAT alpha 1-LexA fusion protein is also capable of trans-activation through a LexA operator. Moreover, the activity of the MAT alpha 1-LexA fusion protein can be further induced by treatment with a-factor. When progressive deletions are made from the amino terminus of MAT alpha 1 in the fusion protein, the basal level of trans-activation progressively decreases, but the inducibility of the fusion protein increases. MAT alpha 1-LexA fusion proteins, which have greater than or equal to 57 amino acids deleted from the amino terminus of MAT alpha 1 are not capable of trans-activation. In addition, the activity of the MAT alpha 1-LexA fusion protein is dependent on the functions of the STE7, STE11, and STE12 genes that encode components of the pheromone response pathway.
Sengupta
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MIT Center for Cancer Research and Department of Biology, Cambridge, Massachusetts 02139.
Cochran
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BH
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002872:Chromosome Deletion; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D018398:Homeodomain Proteins; D000072235:Mating Factor; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D010455:Peptides / Q000235:genetics*; D010675:Pheromones / Q000235:genetics; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D013698:Templates, Genetic; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D005656:Fungal Proteins; D018398:Homeodomain Proteins; D000072235:Mating Factor; D009838:Oligodeoxyribonucleotides; D010455:Peptides; D010675:Pheromones; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099160:LexA Repressor Protein; C062928:MATA2 protein, S cerevisiae