Yeast alpha 2 repressor positions nucleosomes in TRP1/ARS1 chromatin.
The yeast alpha 2 repressor suppresses expression of a-mating-type-specific genes in haploid alpha and diploid a/alpha cell types. We inserted the alpha 2-binding site into the multicopy TRP1/ARS1 yeast plasmid and examined the effects of alpha 2 on the chromatin structure of the derivative plasmids in alpha cells, and a/alpha cells. Whereas no effect on nucleosome position was observed in a cells, nucleosomes were precisely and stably positioned over sequences flanking the alpha 2 operator in alpha and a/alpha cells. In addition, when the alpha 2 operator was located upstream of the TRP1 gene, an extended array of positioned nucleosomes was formed in alpha cells and a/alpha cells, with formation of a nucleosome not present in a cells, and TRP1 mRNA production was substantially reduced. These data indicate that alpha 2 causes a positioning of nucleosomes over sequences proximal to its operator in TRP1/ARS1 chromatin and suggest that changes in chromatin structure may be related to alpha 2 repression of cell-type-specific genes.
Roth
S Y
SY
Laboratory of Cellular and Developmental Biology, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.
Dean
A
A
Simpson
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RT
D015966:Gene Expression Regulation, Fungal; D000072235:Mating Factor; D008836:Micrococcal Nuclease / Q000494:pharmacology; D009707:Nucleosomes / Q000648:ultrastructure*; D009875:Operator Regions, Genetic; D010455:Peptides / Q000502:physiology; D010957:Plasmids; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology*; D014364:Tryptophan
D009707:Nucleosomes; D010455:Peptides; D012097:Repressor Proteins; D014157:Transcription Factors; D000072235:Mating Factor; D014364:Tryptophan; D008836:Micrococcal Nuclease