Involved in silencing within the mating-type region; at the telomeres; and according to PubMed:12867036 also within centromeric DNA regions. Required for the localization of swi6 to the telomeres; silent mating type region; and according to PubMed:12867036 to the centromeric DNA regions. According to PubMed:15545655 not required for the localization of swi6 to centromeric foci. Deacetylates histone H3 on 'Lys-9' and 'Lys-16' of histone H4. This has a direct role in heterochromatin assembly. {ECO:0000269|PubMed:12867036; ECO:0000269|PubMed:15545655}.