PARP-3 Is a Mono-ADP-ribosylase That Activates PARP-1 in the Absence of DNA

Abstract

The PARP-3 protein is closely related to the PARP-1 and PARP-2 proteins, which are involved in DNA repair and genome maintenance. Here, we characterized the biochemical properties of human PARP-3. PARP-3 is able to ADP-ribosylate itself as well as histone H1, a previously unknown substrate for PARP-3. PARP-3 is not activated upon binding to DNA and is a mono-ADP-ribosylase, in contrast to PARP-1 and PARP-2. PARP-3 interacts with PARP-1 and activates PARP-1 in the absence of DNA, resulting in synthesis of polymers of ADPribose. The N-terminal WGR domain of PARP-3 is involved in this activation. The functional interaction between PARP-3 and PARP-1 suggests that it may have a role in DNA repair. However, here we report that PARP-3 small interfering RNA-depleted cells are not sensitive to the topoisomerase I poison camptothecin, inducing DNA single-strand breaks, and repair these lesions as efficiently as wild-type cells. Altogether, these results suggest that the interaction between PARP-1 and PARP-3 is unrelated to DNA single-strand break repair.Poly(ADP-ribosylation) is a ubiquitous protein modification that is important in the regulation of transcription, cell proliferation, differentiation, and apoptosis. Poly(ADP-ribosylation) occurs in almost all nucleated cells of mammals, plants, and lower eukaryotes but is absent in yeast. It represents an immediate cellular response to DNA damage induced by ionizing radiation, alkylating agents, and oxidants (1, 2). PARP-1 (poly(ADP-ribose) polymerase 1) is an abundant nuclear protein that is activated by DNA strand breaks to modify acceptor proteins with poly(ADP-ribose) (PAR) 4 (3). PARP-1 protects DNA breaks and chromatin structure and recruits DNA repair and checkpoint proteins to sites of damage (4 -6). ADP-ribose is produced from NAD ϩ by cleavage of the glycosidic bond between nicotinamide and ribose, a reaction catalyzed by PARPs. Hydrolysis of the high energy bond between the nicotinamide and ribose produces a free energy of Ϫ34.3 kJ/mol (Ϫ8.2 kcal/mol). This energy is used by PARPs for post-translational modification of proteins by synthesizing ADP-ribose polymers attached to the proteins. PARPs can auto-modify themselves or heteromodify other proteins (1, 2).Human PARPs constitute a large family of 17 proteins encoded by different genes and displaying a conserved catalytic domain. In addition to a catalytic domain, PARP family members typically contain one or more additional motifs or domains, including zinc fingers, BRCT (BRCA1 C terminuslike) motifs, ankyrin repeats, macrodomains and different types of protein/protein interaction sites (7,8). PARP-1 has a highly conserved structure, including an N-terminal DNA-binding domain, a central auto-modification domain, and a C-terminal catalytic domain.Of the human PARP enzymes, at least PARP-1, PARP-2, and tankyrase-1 are required for the maintenance of genome stability. Inhibition of PARP-1 is synthetic lethal with defects in homologous recombination and is currently tested as a monotherapy for heritable breast and...

Poly(ADP-ribose) polymerase 3 (PARP3), a newcomer in cellular response to DNA damage and mitotic progression

“…Together, these data suggest a role of PARP3 in cellular response to DNA damage. Accordingly, we found that the knockdown of human PARP3 confers specific susceptibility to DSBs as revealed by prolonged persistence of unrepaired X-rays that induced γH2AX foci, whereas SSBR remained unaffected (18). Therefore, although the basic features of DNA damage recognition by PARP3 still needs to be addressed, our data emphasize a particular role of PARP3 in cellular response to DSBs.…”

“…S5A). Based on recent biochemical studies, it has been proposed that PARP3 interacts with and activates PARP1 (6,18). One interesting scenario would be that PARP3 serves to accelerate PARP1-dependent DSB repair.…”

Small-Molecule Chemical Probe Rescues Cells from Mono-ADP-Ribosyltransferase ARTD10/PARP10-Induced Apoptosis and Sensitizes Cancer Cells to DNA Damage

“…PARylating ARTDs (pARTDs; ARTD1-6), most prominently ARTD1, have been the focus of cancer related research during the past two decades. Due to their sequence and structural similarity ARTD3 and ARTD4 are classified here as pARTDs, although their ability to form PAR chains is not well established and they have also been postulated to be mARTDs (Kickhoefer et al, 1999;Loseva et al, 2010;). An ARTD inhibitor, Olaparib, has been approved to treat ovarian cancer with BRCA mutations.…”

PARP12, an Interferon-stimulated Gene Involved in the Control of Protein Translation and Inflammation

“…Of note, two members of this family (PARP-9 and -13), appear to lack any enzymatic activity. Despite the presence of a glutamate in the catalytic domain (Glu 514 ), PARP-3 only expresses mono-ADP-ribosylating capacities (10), indicating thus that the active-site glutamate is not the sole feature that determines poly-ADP-ribosyl transferase activity. It is worth stressing however that the classification of PARP members in either mono or poly-ADP-ribosyl transferases is hampered by the lack of knowledge of their natural substrate(s) and often relies of the analysis of the transferred ADP-ribosyl moiety during an in vitro automodification reaction.…”