title: PARP-2 and PARP-3 are selectively activated by 5' phosphorylated DNA breaks through an allosteric regulatory mechanism shared with PARP-1.
abstract: PARP-1, PARP-2 and PARP-3 are DNA-dependent PARPs that localize to DNA damage, synthesize poly(ADP-ribose) (PAR) covalently attached to target proteins including themselves, and thereby recruit repair factors to DNA breaks to increase repair efficiency. PARP-1, PARP-2 and PARP-3 have in common two C-terminal domains-Trp-Gly-Arg (WGR) and catalytic (CAT). In contrast, the N-terminal region (NTR) of PARP-1 is over 500 residues and includes four regulatory domains, whereas PARP-2 and PARP-3 have smaller NTRs (70 and 40 residues, respectively) of unknown structural composition and function. Here, we show that PARP-2 and PARP-3 are preferentially activated by DNA breaks harboring a 5' phosphate (5'P), suggesting selective activation in response to specific DNA repair intermediates, in particular structures that are competent for DNA ligation. In contrast to PARP-1, the NTRs of PARP-2 and PARP-3 are not strictly required for DNA binding or for DNA-dependent activation. Rather, the WGR domain is the central regulatory domain of PARP-2 and PARP-3. Finally, PARP-1, PARP-2 and PARP-3 share an allosteric regulatory mechanism of DNA-dependent catalytic activation through a local destabilization of the CAT. Collectively, our study provides new insights into the specialization of the DNA-dependent PARPs and their specific roles in DNA repair pathways.
authors.affiliation: Department of Biochemistry & Molecular Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Langelier
authors.affiliation: Department of Biochemistry & Molecular Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA.
authors.forename: Amanda A
authors.initials: AA
authors.lastname: Riccio
authors.affiliation: Department of Biochemistry & Molecular Biology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA John.Pascal@Jefferson.edu.
authors.forename: John M
authors.initials: JM
authors.lastname: Pascal
mesh_terms: D000494:Allosteric Regulation; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D053960:DNA Breaks; D004789:Enzyme Activation; D010766:Phosphorylation; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary
chemical_list: D018797:Cell Cycle Proteins; C499320:PARP1 protein, human; C483041:PARP2 protein, human; C480979:PARP3 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases