0 avis
Insight into DNA substrate specificity of PARP1 catalyzed DNA poly(ADP-ribosyl)ation
Archive ouverte
Edité par CCSD -
International audience. Poly(ADP-ribose) polymerases (PARPs) use nicotine adenine dinucleotide as substrate to synthetize monomer or a branched polymer of ADP-ribose (MAR or PAR, respectively) covalently attached to the acceptor residue of target proteins. It is generally accepted that PARP1, PARP2 and PARP3 act as DNA break sensors, which at lower levels of cellular DNA damage regulate the DNA repair pathways by recruiting chromatin remodeling and DNA repair factors to double- and single-strand breaks (DSB and SSB) and at a higher level of DNA damage, promote cell death via necrosis, apoptosis or both.Recently, it was showed that PARP1-3 proteins can directly attach MAR or PAR moieties to the DNA termini at the sites of DNA strand breaks. This discovery provides novel molecular insights into the PARPs function. Each PARP recognizes distinct sets of DNA structures with breaks, suggesting that PARP1, 2 and 3 have non-overlapping functions in DNA repair. It was demonstrated that PARP3- and PARP2-catalysed ADP-ribosylation depend on the orientations and distances between DNA strand breaks in a single DNA molecule. Nevertheless, still little is known about the mechanisms governing substrate recognition and specificity of PARP1 accounting for most of cellular PARylation activity. Here, we characterized PARP1-mediated DNA PARylation of DNA duplexes containing different types of DSB termini at varying distances from SSB or G-quadruplex structures in the same molecule. Using a recombinant PARP1, we demonstrated that 3’-terminal phosphate residue can become a preferred acceptor site for PARP1-dependent ADP-ribosylation of DSB ends. Similar results were obtained with HeLa cell-free extracts. Our results suggest that the biological effects of ADP-ribosylation may strongly depend on the configuration of complex DNA strand breaks. The new knowledge about the role and mechanisms of PARPs actions in DSB repair will identify novel therapeutic or diagnostic targets in cancer and other age-related diseases
Consulter en ligne
Suggestions
Du même auteur
