NAD-dependent deacetylase, which participates in a wide range of cellular events including chromosome silencing, chromosome segregation, DNA recombination and the determination of life span. Involved in transcriptional repression of the silent mating-type loci HML and HMR and telomeric silencing via its association with SIR3 and SIR4. Plays a central role in ribosomal DNA (rDNA) silencing via its association with the RENT complex, preventing hyperrecombination, and repressing transcription from foreign promoters, which contributes to extending life span. Probably represses transcription via the formation of heterochromatin structure, which involves the compaction of chromatin fiber into a more condensed form, although this complex in at least one case can still bind euchromatic levels of positive transcription regulators. Although it displays some NAD-dependent histone deacetylase activity on histone H3K9Ac and H3K14Ac and histone H4K16Ac in vitro, such activity is unclear in vivo and may not be essential. H2O + N(6)-acetyl-L-lysyl-[protein] + NAD(+) = 2''-O-acetyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide Binds 1 zinc ion per subunit. Its activity is increased by calorie restriction, which slows the pace of aging and increases maximum lifespan. Activated by resveratrol (3,5,4'-trihydroxy-trans-stilbene), which is found in red wine. Homomultimer. Forms a complex with SIR3 and SIR4 (PubMed:9122169). Component of the RENT complex, at least composed of SIR2, CDC14 and NET1 (PubMed:10219244, PubMed:10219245). The RENT complex interacts with FOB1 (PubMed:12923057). Interacts with ESC8 (PubMed:12399377). Interacts with and ZDS2 (PubMed:10662670). Interacts with MCM10 (PubMed:16328881). Interacts with SLX5 (PubMed:18086879). Interacts with NSI1 (PubMed:22362748). Associated with nucleolar chromatin. Preferentially bound to the spacer regions of the rDNA repeats through its interaction with NET1. Its stability is directly linked to life span, which is extended when it is present in high dosage. Conversely, its absence shortens life span. The reported ADP-ribosyltransferase activity of sirtuins is likely some inefficient side reaction of the deacetylase activity and may not be physiologically relevant. Present with 3350 molecules/cell in log phase SD medium. Belongs to the sirtuin family. Class I subfamily. Was originally thought to be an ADP-ribosyltransferase. In vino vita? - Issue 40 of November 2003