Silencers are required for inheritance of the repressed state in yeast.
Transcriptional silencers in the yeast Saccharomyces induce position-specific, sequence-independent repression by promoting formation of a heterochromatin-like structure across sequences adjacent to them. We have examined the role of silencers in maintenance and inheritance of repression at the silent mating-type cassettes in yeast by monitoring the expression state of one of these cassettes following in vivo deletion of the adjacent silencer. Our experiments indicate that although silencer sequences are dispensable for the maintenance of repression in the absence of cell-cycle progression, silencers are required for the stable inheritance of a repressed state. That is, silenced loci from which the silencer is deleted most often become derepressed within one generation of losing the silencer. Thus, the heritability of a repressed state is not intrinsic to a silenced locus or to the chromatin encompassing it; rather, heritability of repression appears to be a property of the silencer itself.
Holmes
S G
SG
Department of Molecular Biology, Princeton University, New Jersey 08544, USA.
Broach
J R
JR
D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D015966:Gene Expression Regulation, Fungal; D006570:Heterochromatin / Q000502:physiology; D000072235:Mating Factor; D010455:Peptides / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D015534:Trans-Activators / Q000235:genetics; D014158:Transcription, Genetic
D005656:Fungal Proteins; D006570:Heterochromatin; D010455:Peptides; D012333:RNA, Messenger; D012097:Repressor Proteins; C084122:SIR3 protein, S cerevisiae; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D015534:Trans-Activators; D000072235:Mating Factor; D004254:DNA Nucleotidyltransferases; C045119:FLP recombinase