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.

Structures and Mechanisms of Enzymes Employed in the Synthesis and Degradation of PARP-Dependent Protein ADP-Ribosylation

“…The DNA-dependent activity of these DDR PARPs requires the presence of a conserved Tyr-Gly-Arg (WGR) domain, which is present in PARPs 1-3 (Langelier et al, 2012;Langelier et al, 2014). In addition to the WGR domain, PARP1, which is perhaps the most structurally complex member of the PARP family, also contains these regulatory domains: the breast cancer susceptibility protein-1 C terminus (BRCT) domain and three zinc finger domains (ZnF1-3) (Figure 2) Steffen et al, 2013).…”

“…PARP1 can also be activated by binding nucleosomes as well as abnormal DNA structures, such as DNA overhangs, hairpins, forks, and cruciform structures Langelier and Pascal, 2013;Langelier et al, 2012Langelier et al, , 2014. Adding further complexity, PARP1 can also be activated by interacting with its binding partners, such as phosphorylated ERK2, thus affecting further downstream signaling cascades or by being modified by a number of posttranslational modifications (Cohen-Armon et al, 2007).…”

“…Two other human DDR PARPs, PARP2 and 3, lack ZnF domains present in PARP1; nevertheless, they can be efficiently activated by DNA breaks directly via their WGR domains (Langelier et al, 2014). It has been shown that PARP2 and PARP3 are selectively activated by 5 0 -phosphorylated breaks.…”

A New Approach in Cancer Treatment: Poly(ADP-Ribose) Polymerase-1 Inhibitors

“…DNA bağlayan bölge olan N-terminal uç, hasarlı DNA'yı onarmaktan sorumludur. Mer- (15). PARP aktivasyonunun ilişkili olduğu bazı olaylar Tablo 2'de sunulmuştur (16,17).…”

PARP3 interacts with FoxM1 to confer glioblastoma cell radioresistance

“…Recent studies found that PARP-3 could be stimulated by DNA double-strand breaks (DSBs) in vitro and functioned in the same pathway as the poly (ADPribose)-binding protein APLF to accelerate chromosomal DNA DSB repair [9][10][11]. As a result, the absence of PARP3 confers hypersensitivity to anti-tumoral drugs generating DSB [11][12]. However, the underline molecular events remained elusive.…”