NAD-dependent lysine deacetylase and desuccinylase that specifically removes acetyl and succinyl groups on target proteins. Modulates the activities of several proteins which are inactive in their acylated form. Involved in non-homologous end joining (NHEJ) repair of blunt, 5' overhang and 3' overhang DNA double strand breaks (DSB). Overexpression increases the efficiency of NHEJ of the above DSBs 2-fold with no effect on repair fidelity. H2O + N(6)-succinyl-L-lysyl-[protein] + NAD(+) = 2''-O-succinyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide H2O + N(6)-acetyl-L-lysyl-[protein] + NAD(+) = 2''-O-acetyl-ADP-D-ribose + L-lysyl-[protein] + nicotinamide Binds 1 zinc ion per subunit. Interacts with both Ku and LigD; may form a trimeric complex during NHEJ. 2 residues (Tyr-53 and Arg-56) present in a large hydrophobic pocket are probably involved in substrate specificity. They are important for desuccinylation activity, but dispensable for deacetylation activity. Not essential for growth in the absence of DNA damage. Increased sensitivity to ionizing radiation in log, stationary and late stationary phase. Decreased efficiency of NHEJ on blunt, 5' overhang and 3' overhanging DSB, fidelity the same as for wild-type NHEJ. Belongs to the sirtuin family. Class III subfamily.