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- Title
New alleles of SIR2 define cell-cycle-specific silencing functions.
- Authors
Matecic, Mirela; Martins-Taylor, Kristen; Hickman, Merrit; Tanny, Jason; Moazed, Danesh; Holmes, Scott G
- Abstract
The establishment of transcriptional silencing in yeast requires cell-cycle progression, but the nature of this requirement is unknown. Sir2 is a protein deacetylase that is required for gene silencing in yeast. We have used temperature-sensitive alleles of the SIR2 gene to assess Sir2's contribution to silencing as a function of the cell cycle. When examined in vivo, these conditional alleles fall into two classes: one class exhibits a loss of silencing when raised to the nonpermissive temperature regardless of cell-cycle position, while the second class exhibits a mitosis-specific silencing defect. Alleles of the first class have a primary defect in protein deacetylase activity, while the alleles of the second class are specifically defective in Sir2-Sir4 interactions at nonpermissive temperatures. Using a SIR2 temperature-sensitive allele, we show that silencing can be established at the HML locus during progression through the G2/M-G1 interval. These results suggest that yeast heterochromatin undergoes structural transitions as a function of the cell cycle and support the existence of a critical assembly step for silent chromatin in mitosis.
- Publication
Genetics, 2006, Vol 173, Issue 4, p1939
- ISSN
0016-6731
- Publication type
Journal Article
- DOI
10.1534/genetics.106.055491