Boundaries of transcriptionally silent chromatin in Saccharomyces cerevisiae

Abstract

In the budding yeast Saccharomyces cerevisiae, heterochromatic gene silencing has been found within HMR and HML silent mating type loci, the telomeres, and the rRNA-encoding DNA. There may be boundary elements that regulate the spread of silencing to protect genes adjacent to silenced domains from this epigenetic repressive effect. Many assays show that specific DNA regulatory elements separate a euchromatic locus from a neighboring heterochromatic domain and thereby function as a boundary. Alternatively, DNA-independent mechanisms such as competition between acetylated and deacetylated histones are also reported to contribute to gene insulation. However, the mechanism by which boundaries are formed is not clear. Here, the characteristics and functions of boundaries at silenced domains in S. cerevisiae are discussed.

C‐terminus of the Sgf73 subunit of SAGA and SLIK is important for retention in the larger complex and for heterochromatin boundary function

“…Until recently, two distinct models were proposed to explain the mechanism of boundary formation (Sun et al . ). According to the DNA sequence‐dependent model, tDNA sequences at the right side of the HMR domain (Donze et al .…”

Single Cell Visualization of Yeast Gene Expression Shows Correlation of Epigenetic Switching between Multiple Heterochromatic Regions through Multiple Generations

“…Repression of gene expression in HMR , HML , and telomere regions is achieved via binding of a protein complex that includes Sir2p, Sir3p, and Sir4p, whereas repression of gene expression of the rDNA region is achieved by binding of Sir2p [1],[2]. Silencing at these regions is halted by boundaries that prevent extension along the entire length of the chromosome.…”

Fub1p, a novel protein isolated by boundary screening, binds the proteasome complex

“…In the Sir complex, Sir2p has histone deacetylation activity (Imai et al, 2000) and moves along the DNA by deacetylating the N-terminal of histone to allow the other Sir proEdited by Hiroshi Iwasaki * Corresponding author. E-mail: ma4sa6ya@u-fukui.ac.jp teins to bind to the nucleosomes (Rusche et al, 2003;Sun et al, 2011). While Sir2p, Sir3p, and Sir4p are all required for silencing at the HMR region, HML region and the telomeres, silencing of genes at the rDNA region requires only Sir2p (Rusche et al, 2003).…”