Role of the transcription activator Ste12p as a repressor of PRY3 expression.
Mating pheromone represses synthesis of full-length PRY3 mRNA, and a new transcript appears simultaneously with its 5' terminus 452 nucleotides inside the open reading frame (ORF). Synthesis of this shorter transcript results from activation of a promoter within the PRY3 locus, and its production is concomitant with the rapid disappearance of the full-length transcript. Evidence is consistent with the pheromone-induced transcription factor Ste12p binding two pheromone response elements within the PRY3 promoter, directly impeding transcription of the full-length mRNA while simultaneously inducing initiation of the short transcript. This process depends on a TATA box within the PRY3 ORF. Expression of full-length PRY3 inhibited mating, while no disadvantage was detectable for cells unable to make the short transcript. Therefore, Ste12p is utilized as a repressor of full-length PRY3 transcription, ensuring efficient mating. There is no evidence that production of the short PRY3 transcript is anything more than an adventitious by-product of this mechanism. It is possible that cryptic binding sites for transcriptional activators may occur frequently within genomes and have the potential of evolving for rapid, gene-specific repression by mechanisms analogous to PRY3. PRY3 regulation provides a model for the coordination of both inductive and repressive activities within a regulatory network.
Bickel
Kellie S
KS
Department of Biochemistry, University of Washington, Box 357350, Seattle, WA 98195, USA.
Morris
David R
DR
D024506:5' Flanking Region; D004268:DNA-Binding Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D016366:Open Reading Frames; D010675:Pheromones / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012319:RNA Polymerase II / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
C066778:ACE2 protein, S cerevisiae; D004268:DNA-Binding Proteins; C516543:PRY3 protein, S cerevisiae; D010675:Pheromones; D012333:RNA, Messenger; D012097:Repressor Proteins; C489241:STE12 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D012319:RNA Polymerase II