NAD-dependent histone deacetylase that is involved in nuclear silencing events. Derepresses subtelomeric silencing and increases repression in nucleolar (rDNA) silencing. Its function is negatively regulated by active nuclear export. H2O + N(6)-acetyl-L-lysyl-[protein] + NAD(+) = 2''-O-acetyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide Binds 1 zinc ion per subunit. Inhibited by ADP-ribose and nicotinamide. Homotrimer. Monomer. Homotrimeric in its unliganded state. Undergoes a trimer-monomer transition upon acetyl-lysine substrate binding. Shuttles between the nucleus and cytoplasm, but is largely cytoplasmic owing to efficient nuclear export. Nuclear exclusion is mediated by the exportin CRM1. Present with 5260 molecules/cell in log phase SD medium. Belongs to the sirtuin family. Class I subfamily.