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.
MIT Center for Cancer Research and Department of Biology, Cambridge, Massachusetts 02139.
P
P
Sengupta
B H
BH
Cochran
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