NAD-dependent lysine demalonylase, desuccinylase and deglutarylase that specifically removes malonyl, succinyl and glutaryl groups on target proteins. Activates CPS1 and contributes to the regulation of blood ammonia levels during prolonged fasting: acts by mediating desuccinylation and deglutarylation of CPS1, thereby increasing CPS1 activity in response to elevated NAD levels during fasting. Activates SOD1 by mediating its desuccinylation, leading to reduced reactive oxygen species. Activates SHMT2 by mediating its desuccinylation. Modulates ketogenesis through the desuccinylation and activation of HMGCS2. Has weak NAD-dependent protein deacetylase activity; however this activity may not be physiologically relevant in vivo. Can deacetylate cytochrome c (CYCS) and a number of other proteins in vitro such as UOX. H2O + N(6)-malonyl-L-lysyl-[protein] + NAD(+) = 2''-O-malonyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide H2O + N(6)-succinyl-L-lysyl-[protein] + NAD(+) = 2''-O-succinyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide H2O + N(6)-glutaryl-L-lysyl-[protein] + NAD(+) = 2''-O-glutaryl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide Binds 1 zinc ion per subunit. Monomer. Homodimer. Interacts with CPS1. Interacts with PCCA (By similarity). Mainly mitochondrial. Also present extramitochondrially, with a fraction present in the cytosol and very small amounts also detected in the nucleus. In contrast to class I sirtuins, class III sirtuins have only weak deacetylase activity. Difference in substrate specificity is probably due to a larger hydrophobic pocket with 2 residues (Tyr-102 and Arg-105) that bind to malonylated and succinylated substrates and define the specificity. Belongs to the sirtuin family. Class III subfamily.