Yeast silencers create domains of nuclease-resistant chromatin in an SIR4-dependent manner.
Previous analysis of the repression of the silent mating type loci in Saccharomyces cerevisiae has linked the mechanism of silencing to the formation of a chromatin domain at the silenced loci. In this study, a TRP1 reporter gene was used to examine changes in chromatin structure in a neutral environment. This enabled the chromatin structure organized by yeast silencers to be compared directly with changes effected by the yeast alpha2 repressor. It was found that silencers mediate the formation of lengthy nuclease-resistant domains on the DNA, rather than specifically positioning nucleosomes over promoter regions as the alpha2 repressor does. Silencing at the TRP1 reporter gene closely resembled silencing at the HMR and HML loci. Repression of the test gene was optimal when two silencers flanking the reporter gene were used, mimicking the situation at the silent loci. In addition, both repression of the reporter gene and the formation of nuclease-resistant chromatin domains was SIR4 dependent.
Reimer
S K
SK
Center for Gene Regulation, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA. Reimersk@jmu.edu
Buchman
A R
AR
D019747:Aldose-Ketose Isomerases; D001483:Base Sequence; D002843:Chromatin / Q000235:genetics*; D004271:DNA, Fungal / Q000235:genetics; D003851:Deoxyribonucleases; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D049770:Genes, Mating Type, Fungal; D017930:Genes, Reporter; D005822:Genetic Vectors; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009707:Nucleosomes / Q000235:genetics; D009875:Operator Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae
D002843:Chromatin; D004271:DNA, Fungal; D005656:Fungal Proteins; D009707:Nucleosomes; C061573:SIR4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; D003851:Deoxyribonucleases; D019747:Aldose-Ketose Isomerases; C490353:TRP1 protein, S cerevisiae