The dosage of chromatin proteins affects transcriptional silencing and DNA repair in Saccharomyces cerevisiae

Abstract

Alterations in protein composition or dosage within chromatin may trigger changes in processes such as gene expression and DNA repair. Through transposon mutagenesis and targeted gene deletions in haploids and diploids of Saccharomyces cerevisiae, we identified mutations that affect telomeric silencing in genes encoding telomere-associated Sir4p and Yku80p and chromatin remodeling ATPases Ies2p and Rsc1p. We found that sir4/SIR4 heterozygous diploids efficiently silence the mating type locus HMR but not telomeres, and diploids heterozygous for yku80 and ies2 mutations are inefficient at DNA repair. In contrast, strains heterozygous for most chromatin remodeling ATPase mutations retain wild-type silencing and DNA repair levels. Thus, in diploids, chromatin structures required for DNA repair and telomeric silencing are sensitive to dosage changes.

Unexpected Function of the Glucanosyltransferase Gas1 in the DNA Damage Response Linked to Histone H3 Acetyltransferases in Saccharomyces cerevisiae

“…We demonstrate that deletion of both enzymes leads to restoration of silencing to wild-type levels at all loci analyzed (Figure 2A). Locus-specific silencing relies on a balance of silencing proteins and other chromatin factors, some of which are limiting (Smith et al 1998;Benbow and Dubois 2008). Altering the distribution of these factors can lead to changes in the strength of silencing between loci (Lustig et al 1996).…”