Yang Lu, Li Tang, Øyvind Strømland, Chatrin Chatrin, Kang Zhu, Deeksha Munnur, Joséphine Groslambert, Petra Mikolčević, H. Schüler, Gyula Timinszky, Guillaume Gabant, Marcin J. Suskiewicz, Andreja Mikoč, Vincent Aucagne, Dragana Ahel, Qiang Liu, Ivan Ahel
ADP-ribosylation is a conserved modification that uses NAD+ as a co-substrate to regulate essential cellular processes, such as genome stability and transcription, with Poly(ADP-ribose) Polymerases (PARPs) serving as the major catalyzing enzymes in humans. Historically defined as a protein post-translational modification, ADP-ribosylation on nucleic acids has been increasingly recognized in recent years, particularly in bacterial systems, but remains poorly understood in higher organisms. Here, we identify human PARP10 as a candidate enzyme that ADP-ribosylates nucleic acid bases, showing apparent activity on uracil bases in RNA, and a relatively weaker activity toward thymine bases in DNA. Furthermore, we show that human TARG1, a neurodegenerative disorder-linked protein previously reported to hydrolyse thymine base ADP-ribosylation, also efficiently reverses uracil base ADP-ribosylation (U-ADPr). To improve the efficient characterization of the enzymes for U-ADPr reversal, we developed chemical probes. Using these probes, we demonstrated that human TARG1 and TARG1-like macrodomain proteins are the efficient hydrolases for U-ADPr reversal in humans, Drosophila melanogaster, and bacterial homologues. The widespread distribution of U-ADPr hydrolases among different organisms suggests the potential evolutionary conservation of U-ADPr as a biological signal.