Required for deacetylation in the mating-type region and the centromere. Acts upstream of the histone deacetylases to promote transcriptional silencing. Required for proper positioning of nucleosomes at heterochromatic loci and for transcriptional gene silencing (TGS) function of the Snf2/Hdac-containing repressor complex (SHREC). Interacts with clr3. Associates with major heterochromatin, centromeres, sub-telomeres, rDNA and the mat locus.