The oligonucleotide/oligosaccharide-binding fold motif is a poly(ADP-ribose)-binding domain that mediates DNA damage response

Abstract

Oligonucleotide/oligosaccharide-binding (OB) fold is a ssDNA or RNA binding motif in prokaryotes and eukaryotes. Unexpectedly, we found that the OB fold of human ssDNA-binding protein 1 (hSSB1) is a poly(ADP ribose) (PAR) binding domain. hSSB1 exhibits highaffinity binding to PAR and recognizes iso-ADP ribose (ADPR), the linkage between two ADPR units. This interaction between PAR and hSSB1 mediates the early recruitment of hSSB1 to the sites of DNA damage. Mutations in the OB fold of hSSB1 that disrupt PAR binding abolish the relocation of hSSB1 to the sites of DNA damage. Moreover, PAR-mediated recruitment of hSSB1 is important for early DNA damage repair. We have screened other OB folds and found that several other OB folds also recognize PAR. Taken together, our study reveals a PAR-binding domain that mediates DNA damage repair.G enomic integrity is constantly challenged by various types of DNA damage, which are induced by DNA replication errors, environmental hazards, and other genotoxic stress. In response to this stress, cells activate an evolutionarily conserved pathway termed the DNA damage response (DDR), to orchestrate various cellular responses for maintaining genomic stability (1-3). It has been shown that poly(ADP ribosyl)ation plays an important role in DDR (4-6). Upon DNA damage induction, poly(ADP ribose) (PAR) polymerases (PARPs), such as PARP1, the founding member of the PARP family, rapidly detect DNA breaks, including single-strand breaks (SSBs) and double-strand breaks (DSBs), and activate PAR synthesis at or adjacent to DNA lesions (7,8). Recent evidence suggests that DNA damage-induced PAR may serve as a docking signal to recruit DDR factors to DNA lesions (7-14). For example, our recent study showed that the BRCT domains of BARD1 and NBS1 recognize PAR, which facilitates the rapid recruitment of the BRCA1/BARD1 complex and NBS1 to the site of DNA damage (15, 16). These results indicate that other DDR factors may also be recruited to DNA damage sites by PAR. Thus, it is important to identify other "readers" of PAR to elucidate the molecular mechanism of PAR in DDR.Previous studies have shown that human ssDNA-binding protein 1 (hSSB1) plays a key role in . hSSB1 is a 211-residue polypeptide containing an oligonucleotide/oligosaccharide-binding (OB) fold at the N terminus. Following DNA damage, hSSB1 quickly relocates to DNA damage sites and regulates foci formation of other DNA damage repair proteins, such as BRCA1 and RAD51 (17,(21)(22)(23)(24). Thus, depletion of hSSB1 impairs the repair of DSBs. In response to DNA damage, hSSB1 is phosphorylated by ATM and regulates ATM-dependent cell cycle checkpoint activation (17,(21)(22)(23)(24). By protein affinity purifications, hSSB1 was shown to tightly associate with other proteins, such as INTS3, forming a multisubunit complex (21-24). INTS3 is a well-folded protein and previously identified as a member in the INTS complex that regulates RNA processing and gene transcription (25). Like hSSB1, INTS3 is also quickly relocated to DNA lesions in r...

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

“…Proteins that specifically sense and modulate the ADP-ribosylation signals often contain structurally distinct, evolutionary conserved ADP-ribose binding modules (Barkauskaite et al, 2013b;Zhang et al, 2014). The structure-function relationships, detailing the recognition of ADP-ribosylation, have been described only for three of these ADP-ribose binding modules: the poly(ADP-ribose)-binding zinc finger (PBZ), WWE domains, and the macrodomain.…”

Poly(ADP-Ribose) Mediates the BRCA2-Dependent Early DNA Damage Response

“…Upon DNA damage induction, PARP1, the founding member of PARPs, rapidly detects DNA single-strand breaks (SSBs) or double-strand breaks (DSBs), and is activated for PAR synthesis at DNA lesions within a few seconds in response to DNA damage(Kim et al, 2005; Luo and Kraus, 2012). Moreover, our previous study suggests that the solo OB-fold motif is able to recognize iso-ADP-ribose, the linkage between two ADP-ribose unites (Zhang et al, 2014). Here, our results suggested that the tandem OB-folds of BRCA2 recognize DNA damage-induced PAR and target BRCA2 to DNA lesions.…”

Poly(ADP-ribosyl)ation is recognized by ECT2 during mitosis

“…[1][2][3][4] Using nicotinamide adenine dinucleotide (NAD) as the donor, a group of enzymes, namely poly (ADP-ribose) polymerases (PARPs), catalyze this posttranslational modification by covalently linking ADP-ribose to protein targets and building the linear and branched chains of poly (ADP-ribose) (PAR). [5][6][7] Interestingly, recent studies suggest that PARylation occurs at the spindle apparatus during mitosis, [8][9][10] implying a novel function of PAR during mitosis.…”