NAD-dependent histone deacetylase involved in telomeric silencing. Histone deacetylase proteins act via the formation of large multiprotein complexes that are responsible for the deacetylation of lysine residues on the N-terminal part of the core histones (H2A, H2B, H3 and H4). Histone deacetylation gives a tag for epigenetic repression and plays an important role in transcriptional regulation, cell cycle progression and developmental events. Restores silencing at HMR in SIR2 mutants when overexpressed. Required to repress middle sporulation genes during vegetative growth. Acts as a sensor of NAD(+) levels and regulator of NAD(+) biosynthesis. Regulates the gene expression of de novo NAD(+) biosynthesis genes. H2O + N(6)-acetyl-L-lysyl-[protein] + NAD(+) = 2''-O-acetyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide Binds 1 zinc ion per subunit. Identified in the Set3C complex with HOS2, SIF2, SNT1, CPR1, HOS4/YIL112W and SET3. Its presence is however not essential for meiotic repression by the Set3C complex. Interacts with SUM1 and RFM1. The interaction with SUM1 is mediated by RFM1. But not nucleolar, and cytoplasmic. Present with 1440 molecules/cell in log phase SD medium. Belongs to the sirtuin family. Class I subfamily.