Figure 3.

NAD⁺-consuming reactions in genome maintenance.A, diphtheria toxin-like ADP-ribosyltransferases (ARTDs) catalyze the cleavage of N-glycosidic bond and covalently attaches ADP ribose (ADPR) moiety to target molecules: protein, DNA, or RNA. ARTD family members perform a transfer of either single ADPR units (MARylation) or multiple ADPR units (PARylation), connected in a linear or branched manner. B, sirtuins (SIRTs) mediate a transfer of an acyl group from protein to NAD⁺-derived ADPR, producing O-acyl-ADPR and NAM. C, DNA ligase IV (LIG IV) potentially uses α-phosphate moiety of NAD⁺ to form a new phosphodiester bond in the process of DNA nick repair. For references, see text.