Poly(ADP-ribose) Binds to Specific Domains in DNA Damage Checkpoint Proteins

Abstract

Poly(ADP-ribose) is formed in possibly all multicellular organisms by a familiy of poly(ADP-ribose) polymerases (PARPs). PARP-1, the best understood and until recently the only known member of this family, is a DNA damage signal protein catalyzing its automodification with multiple, variably sized ADP-ribose polymers that may contain up to 200 residues and several branching points. Through these polymers, PARP-1 can interact noncovalently with other proteins and alter their functions. Here we report the discovery of a poly(ADP-ribose)-binding sequence motif in several important DNA damage checkpoint proteins. The 20-amino acid motif contains two conserved regions: (i) a cluster rich in basic amino acids and (ii) a pattern of hydrophobic amino acids interspersed with basic residues. Using a combination of alanine scanning, polymer blot analysis, and photoaffinity labeling, we have identified poly(ADP-ribose)-binding sites in the following proteins: p53, p21CIP1/WAF1 , xeroderma pigmentosum group A complementing protein, MSH6, DNA ligase III, XRCC1, DNA polymerase ε, DNA-PKCS, Ku70, NF-κB, inducible nitric-oxide synthase, caspase-activated DNase, and telomerase. The poly(ADP-ribose)-binding motif was found to overlap with five important functional domains responsible for (i) protein-protein interactions, (ii) DNA binding, (iii) nuclear localization, (iv) nuclear export, and (v) protein degradation. Thus, PARPs may target specific signal network proteins via poly(ADP-ribose) and regulate their domain functions. Poly(ADP-ribose) is formed in possibly all multicellular organisms by a familiy of poly(ADP-ribose) polymerases (PARPs). PARP-1, the best understood and until recently the only known member of this family, is a DNA damage signal protein catalyzing its automodification with multiple, variably sized ADP-ribose polymers that may contain up to 200 residues and several branching points. Through these polymers, PARP-1 can interact noncovalently with other proteins and alter their functions. Here we report the discovery of a poly(ADP-ribose)-binding sequence motif in several important DNA damage checkpoint proteins. The 20-amino acid motif contains two conserved regions: (i) a cluster rich in basic amino acids and (ii) a pattern of hydrophobic amino acids interspersed with basic residues. Using a combination of alanine scanning, polymer blot analysis, and photoaffinity labeling, we have identified poly(ADP-ribose)-binding sites in the following proteins: p53, p21CIP1/WAF1 , xeroderma pigmentosum group A complementing protein, MSH6, DNA ligase III, XRCC1, DNA polymerase ε, DNA-PKCS, Ku70, NF-κB, inducible nitric-oxide synthase, caspase-activated DNase, and telomerase. The poly(ADP-ribose)-binding motif was found to overlap with five important functional domains responsible for (i) protein-protein interactions, (ii) DNA binding, (iii) nuclear localization, (iv) nuclear export, and (v) protein degradation. Thus, PARPs may target specific signal network proteins via poly(ADP-ribose) and regulate their domain functions. poly(ADP-ribose) polymerase protein kinase poly(ADP-ribose) inducible NO synthase caspase-activated DNase telomerase reverse transcriptase base excision repair DNA-dependent kinase polyacrylamide gel electrophoresis amino acid(s) Tris-buffered saline with Tween 20 proliferating cell nuclear antigen BRCA1-C terminus myristoylated alanine-rich C kinase substrate xeroderma pigmentosum group A complementing protein Four different poly(ADP-ribose) polymerases (PARPs)1 have been identified in multicellular organisms to catalyze poly(ADP-ribose) [PAR] synthesis from NAD+ (1Jacobson M.K. Jacobson E.L. Trends Biochem. Sci. 1999; 24: 415-417Abstract Full Text Full Text PDF PubMed Scopus (88) Google Scholar). The best understood member of the PARP family is PARP-1. As a highly conserved, multimodular 113-kDa protein, PARP-1 shares many hallmarks with proteins of the cellular DNA damage signal network (2Agarwal M.L. Taylor W.R. Chernov M.V. Chernova O.B. Stark G.R. J. Biol. Chem. 1998; 273: 1-4Abstract Full Text Full Text PDF PubMed Scopus (649) Google Scholar). Like ATM, ATR, DNA-PK, and p53 (3Smith G.C.M. Jackson S.P. Genes Dev. 1999; 13: 916-934Crossref PubMed Scopus (769) Google Scholar), PARP-1 binds to and is activated by DNA strand breaks and interacts with several other DNA damage checkpoint proteins. In addition, PARP-1 can regulate its protein and DNA interactions by catalyzing its automodification with multiple PAR molecules. An alternative product of the PARP-1 gene is sPARP-1, a 55.3-kDa protein with nuclear localization and sequence identity to the catalytic domain of PARP-1 (4Sallmann F.R. Vodenicharov M.D. Wang Z.Q. Poirier G.G. J. Biol. Chem. 2000; 275: 15504-15511Abstract Full Text Full Text PDF PubMed Scopus (79) Google Scholar). It is also activated by DNA damaging agents but apparently does not require DNA strand breaks for activation. Tankyrase, another member of the PARP family, is a multimodular 142-kDa protein with a catalytic domain homologous to PARP-1 (5Smith S. Giriat I. Schmitt A. de Lange T. Science. 1998; 282: 1484-1487Crossref PubMed Scopus (908) Google Scholar). In vitro, tankyrase catalyzes its automodification as well as the modification of the telomere-specific protein TRF1 in a DNA-independent manner. The third member of the PARP family, PARP-2, is a 62-kDa protein (6Berghammer H. Ebner M. Marksteiner R. Auer B. FEBS Lett. 1999; 449: 259-263Crossref PubMed Scopus (58) Google Scholar, 7Amé J.C. Rolli V. Schreiber V. Niedergang C. Apiou F. Decker P. Muller S. Höger T. Ménissier-de Murcia J. de Murcia G. J. Biol. Chem. 1999; 274: 17860-17868Abstract Full Text Full Text PDF PubMed Scopus (616) Google Scholar). It is activated by DNA strand breaks, but its function is unknown. Finally, vault PARP, a 193-kDa protein, has recently been identified as a protein component of vaults (8Kickhoefer V.A. Siva A.C. Kedersha N.L. Inman E.M. Ruland C. Streuli M. Rome L.H. J. Cell Biol. 1999; 146: 917-928Crossref PubMed Scopus (340) Google Scholar), large ribonucleoprotein complexes of unknown function (9Kickhoefer V.A. Vasu S.K. Rome L.H. Trends Cell Biol. 1996; 6: 174-178Abstract Full Text PDF PubMed Scopus (68) Google Scholar). Vault PARP catalyzes the poly(ADP-ribosyl)ation of a major vault protein. The presence of a larger family of PARPs in multicellular organisms illustrates the potential importance of PAR in regulating cellular functions. We have previously shown that the noncovalent binding of PAR to p53 (10Malanga M. Pleschke J.M. Kleczkowska H.E. Althaus F.R. J. Biol. Chem. 1998; 273: 11839-11843Abstract Full Text Full Text PDF PubMed Scopus (196) Google Scholar) or members of the MARCKS protein family (11Schmitz A.P. Pleschke J.M. Kleczkowska H.E. Althaus F.R. Vergères G. Biochemistry. 1998; 37: 9520-9527Crossref PubMed Scopus (18) Google Scholar) may drastically alter several domain-specific functions of these proteins. Apart from its specificity, PAR binding to proteins is exceptionally strong. For example, we have previously found that PAR-histone complexes resist phenol partitioning, strong acids, chaotropes, detergents, and high salt concentrations (12Panzeter P.L. Realini C.A. Althaus F.R. Biochemistry. 1992; 31: 1379-1385Crossref PubMed Scopus (104) Google Scholar). These observations led us to postulate the involvement of a specific sequence motif in PAR binding to proteins. The results of the present study confirm the presence of a PAR-binding consensus sequence in a family of important DNA damage checkpoint proteins. The following peptides derived from human proteins were used (Chiron Mimotopes, Clayton, Victoria, Australia): MARCKS effector peptides, alanine substituted as described in Fig. 1 B; CDN1 (9–32), RQNPCGSKACRRLFGPVDSEQLSR; CDN1 (), RKRRQTSMTDFYHSKRRLIFSKRK; XPA (25–46), RASIERKRQRALMLRQARLAAR; XPA (), KQKKFDKKVKELRRAVR- SSVWKR; MSH2 (), RKRADFSTKDIYQDLNRLLKGKK; MSH6 (), KVARKRKRMVTGNGSLKRKSSRK; DNL3 (12–34), KRGTAGCKKCKEKIVKGVCRIGK; DNL3 (), SRKAPSKPSASTKKAEGKLSNS; DPOB (26–48), KNVSQAIHKYNAYRKAASVIAKY; DPOB (39–61), RKAASVIAKYPHKIKSGAEAKKL; KU70 (), RKVRAKETRKRALSRLKLKLNK; KU86 (), KKFEKRHIEIFTDLSSRFSKSQ; DNA-PKCS (2728–2752), RRR- FMRDQEKLSLMYARKGVAEQKR; KBF2 (), KELKK- VMDLSIVRLRFSAFLR; NOS2 (), KRRPKRREIPLKVLVKAVLFA; caspase-activated DNase (CAD) (), RFQSKSG- YLRYSCESRIRSYLR; TERT (), RGFKAGRNMRRKLFGVLRLKCH. Expression and purification of p21 was as described (13Podust V.N. Podust L.M. Goubin F. Ducommun B. Hubscher U. Biochemistry. 1995; 34: 8869-8875Crossref PubMed Scopus (109) Google Scholar), XPA was bacterially expressed with a N-terminal His tag (14Jones C.J. Wood R.D. Biochemistry. 1993; 32: 12096-12104Crossref PubMed Scopus (284) Google Scholar), and the hMutSα heterodimer, hMSH2, and hMSH6 were purified from a baculovirus system as described (15Iaccarino I. Marra G. Palombo F. Jiricny J. EMBO J. 1998; 17: 2677-2686Crossref PubMed Scopus (145) Google Scholar). Polymer blot analysis was performed as described (16Panzeter P.L. Zweifel B. Malanga M. Waser S.H. Richard M.C. Althaus F.R. J. Biol. Chem. 1993; 268: 17662-17664Abstract Full Text PDF PubMed Google Scholar). Pure peptides or proteins were dot-blotted directly onto nitrocellulose membrane. The membrane was rinsed with three changes of TBST (10 mm Tris, pH 7.4, 0.15 mNaCl, 0.05% Tween 20). [32P]PAR (0.5 μCi/nmol ADP-ribose; 0.5–1.0 nmol of total ADP-ribose; mean PAR size, 20 residues) were diluted to 10 ml with TBST and added to the nitrocellulose. After incubation for 1 h at room temperature with gentle agitation, the membrane was washed with TBST containing 1m NaCl to eliminate unspecific binding. The results of polymer blot analysis were only considered positive if PAR binding resisted the high stringency (i.e. 1 m NaCl) conditions. The nitrocellulose was dried and subjected to autoradiography. Although proteins and polypeptides immobilized on nitrocellulose still bind sonicated calf thymus DNA, this binding is not resistant to washing with 1 m NaCl (17Malanga M. Atorino L. Tramontano F. Farina B. Quesada P. Biochim. Biophys. Acta. 1998; 1399: 154-160Crossref PubMed Scopus (29) Google Scholar). In the presence of a 10-fold excess (w/w) of competing calf thymus DNA, PAR binding to immobilized polypeptides with a PAR-binding motif is not reduced, whereas a 100-fold excess DNA reduces this binding by ∼50% (17Malanga M. Atorino L. Tramontano F. Farina B. Quesada P. Biochim. Biophys. Acta. 1998; 1399: 154-160Crossref PubMed Scopus (29) Google Scholar). Similar results were obtained when a 27-nucleotide double-stranded DNA fragment was used for competition experiments. Moreover, branched PAR polymers and large linear polymers exhibited a higher binding affinity than short linear polymers (for details, cf. Refs. 11Schmitz A.P. Pleschke J.M. Kleczkowska H.E. Althaus F.R. Vergères G. Biochemistry. 1998; 37: 9520-9527Crossref PubMed Scopus (18) Google Scholar, 12Panzeter P.L. Realini C.A. Althaus F.R. Biochemistry. 1992; 31: 1379-1385Crossref PubMed Scopus (104) Google Scholar, and17Malanga M. Atorino L. Tramontano F. Farina B. Quesada P. Biochim. Biophys. Acta. 1998; 1399: 154-160Crossref PubMed Scopus (29) Google Scholar). PAR containing photoactive azido groups was prepared as described previously (18Kiehlbauch Jacobson E.L. Jacobson M.K. Biochem. 1993; PubMed Scopus Google Scholar) with The 200 and was from all to of the azido The of photoactive PAR was performed by high The NaCl used was as by a m to m in 1 m to m in m in m to in m to m in m to m in by a with 1 m mm pH of protein or of photoactive PAR of a were for on in ml of and for at room temperature a at a of 1 The were by of mm pH and After electrophoresis on the were with and dried were obtained by at a In was also by sequence analysis was performed the of the For the of the shown in Fig. 1 C was used to different Using the base was for The for was a acid the effector Using we have previously that this domain is and for noncovalent PAR binding to MARCKS proteins (11Schmitz A.P. Pleschke J.M. Kleczkowska H.E. Althaus F.R. Vergères G. Biochemistry. 1998; 37: 9520-9527Crossref PubMed Scopus (18) Google Scholar). A of effector peptides was dot-blotted onto nitrocellulose and for PAR binding blot high stringency NaCl) As PAR to the effector domain Fig. 1 and a excess of competing (11Schmitz A.P. Pleschke J.M. Kleczkowska H.E. Althaus F.R. Vergères G. Biochemistry. 1998; 37: 9520-9527Crossref PubMed Scopus (18) Google Scholar) or a 10-fold excess of sonicated calf thymus DNA (17Malanga M. Atorino L. Tramontano F. Farina B. Quesada P. Biochim. Biophys. Acta. 1998; 1399: 154-160Crossref PubMed Scopus (29) Google Scholar) not PAR binding of basic amino acids were substituted by or in PAR binding was not 1 alanine of two with up to 10 basic residues the binding only 1 that amino acids not to PAR binding. all hydrophobic amino acids of the effector to alanine PAR binding 1 and when N-terminal were substituted by of three or at a drastically PAR binding and by polymer blot analysis when the N-terminal cluster was as well An of the in the residues in to cluster 1 of basic amino acids was by was 1 these results the importance of hydrophobic amino acids for PAR binding. the sequence motif of the MARCKS effector at we for the of in other proteins. Fig. 1 C a motif with identified in the and (16Panzeter P.L. Zweifel B. Malanga M. Waser S.H. Richard M.C. Althaus F.R. J. Biol. Chem. 1993; 268: 17662-17664Abstract Full Text PDF PubMed Google Scholar). A of the is the presence of a pattern of hydrophobic amino acids interspersed with basic and a cluster of basic amino acids at the N-terminal of the these peptides positive in the polymer blot not We used the to amino acid with and of the hydrophobic amino acid of the These were used to the with the sequence P. Chem. 1996; PubMed Scopus Google Scholar). the the proteins that were to interact with PAR from their function and localization were for the presence of a cluster of basic residues at the N-terminal was to for the PAR-binding motif in proteins that were known or to interact with PARP-1. Thus, the PAR-binding motif in protein was by sequence analysis and The kinase p21 directly by the kinase of a of complexes G. S. 1993; Full Text PDF PubMed Scopus Google Scholar, G. H. R. 1993; PubMed Scopus Google Scholar). PARP-1 has been as a DNA damage checkpoint protein cell M. T. T. 1995; PubMed Scopus Google Scholar, C. de Murcia G. Murcia J. 1998; PubMed Scopus Google Scholar), we p21 as a PAR-binding protein. As shown in Fig. PAR noncovalently with human p21 in the polymer blot of the p21 a of amino acids to the PAR-binding A to this was found to bind PAR in the polymer blot whereas a from the N-terminal of p21 not the PAR-binding was not to interact with PAR polymers In a photoaffinity was used to confirm the results obtained with blot PAR containing a photoactive azido group were prepared (18Kiehlbauch Jacobson E.L. Jacobson M.K. Biochem. 1993; PubMed Scopus Google Scholar) and with p21 protein was with of two and by The in Fig. that p21 was in a manner. The p21 also whereas the N-terminal not that the of p21 was of p21 protein were with a of photoactive The was as shown in the of Fig. B. A analysis of the by that of binding was at a of p21 to photoactive of Finally, the of was in the presence of PAR polymers azido groups of was in a when of PAR of the were added by at a of 10 these results that the noncovalent of PAR with p21 in a well at the C terminus amino acids The excision repair protein XPA a of DNA and other proteins to repair DNA (14Jones C.J. Wood R.D. Biochemistry. 1993; 32: 12096-12104Crossref PubMed Scopus (284) Google Scholar, A. J. Biol. Chem. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar, M. A. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). The presence of a PAR-binding sequence motif at the C terminus XPA a for polymer XPA protein and two XPA peptides were subjected to polymer blot Fig. A that PAR to human XPA and a residues whereas a N-terminal was These results photoaffinity of XPA protein and XPA peptides with photoactive [32P]PAR The of PAR binding to XPA was by two experiments. with of the and at a of XPA to photoactive of of PAR azido groups as the of of a of photoactive the XPA protein of was at a of PAR to photoactive PAR polymers of the of the noncovalent the hMutSα is in the of and J. EMBO J. 1998; 17: PubMed Scopus Google Scholar). polymer blot we a noncovalent PAR and the hMutSα heterodimer, was to PAR binding to MSH6 The of proteins were for the presence of the PAR-binding A for a MSH6 but not for a MSH2 Fig. PARP-1 is activated the of the base excision repair results in of a DNA we for PAR-binding domains in proteins known to in the The PAR binding of peptides derived from different proteins was by polymer blot analysis An interact noncovalently with PAR as PAR binding was and for in DNA ligase A derived from DNA polymerase ε, the responsible for repair synthesis in P. B. S.H. Biochemistry. 1998; 37: PubMed Scopus Google Scholar), to whereas two peptides from the terminus of DNA polymerase the catalyzing short repair were in the polymer blot In this functional consensus PAR-binding were identified in XRCC1, DNA ligase III, and DNA polymerase and PARP-1 activated by DNA strand and in DNA is nuclear protein kinase of three The catalytic DNA-PKCS of shares a domain of with members of the family, and the is important for DNA binding A. H. Sci. U. S. A. 1992; PubMed Scopus (340) Google Scholar, Jackson S.P. 1993; Full Text PDF PubMed Scopus Google Scholar, H. A. S.P. Jackson S.P. 1995; Full Text PDF PubMed Scopus Google Scholar). We the of these proteins for the presence of PAR-binding and by polymer blot analysis and photoaffinity results were obtained for two peptides derived from DNA-PKCS and whereas the was by blot In with was with the whereas the peptides from and DNA-PKCS were positive in the not PARP-1 has been in cell PubMed Scopus Google Scholar, S.H. Sci. U. S. A. 1999; PubMed Scopus Google Scholar) as well as in by S.H. S. Poirier G.G. 1993; Google Scholar, S.H. S. Poirier G.G. PubMed Scopus Google Scholar). several cell regulating proteins were for the presence of PAR-binding The family of interacts with PARP-1 protein Biol. Chem. 1999; PubMed Scopus Google Scholar, Ménissier-de Murcia J. C. Decker P. R. Muller S. de G. J.C. de Murcia G. EMBO J. 1999; PubMed Scopus Google Scholar). A PAR-binding by polymer blot analysis for the of and Fig. The inducible NO synthase is by NF-κB, contains a PAR-binding sequence motif in the was the polymer blot is responsible for DNA M. H. H. A. S. 1998; PubMed Scopus Google Scholar). analysis and the presence of a functional PAR-binding motif Fig. a reverse transcriptase regulating and of Cell Biol. 1999; PubMed Scopus Google Scholar), was found to contain a PAR-binding sequence motif in the catalytic Fig. the of the PAR-binding is that the PAR-binding domains not contain a amino but is a consensus pattern of residues with conserved in The PAR-binding motif 20 amino acids and contains two conserved regions: (i) a cluster rich in positive residues and (ii) the consensus pattern h residues with hydrophobic for a for basic amino acids, and is amino The of basic residues in the consensus pattern and The consensus sequence in Fig. may a for and of PAR-binding proteins. study the presence of a PAR-binding in several proteins of the DNA damage signal A function of these proteins is that all to the of in The PAR-binding were found to overlap with five important responsible for (i) protein-protein interactions, (ii) DNA binding, (iii) nuclear localization (iv) nuclear and (v) protein degradation. In p53 protein, three important functional domains for noncovalent PAR the DNA binding the nuclear signal and the domain M. Pleschke J.M. Kleczkowska H.E. Althaus F.R. J. Biol. Chem. 1998; 273: 11839-11843Abstract Full Text Full Text PDF PubMed Scopus (196) Google Scholar). The PAR-binding of p21 a highly conserved responsible for binding J. P. M. S. B. Google Scholar, J. Jackson A. 1995; PubMed Scopus Google Scholar, M. G.R. EMBO J. 1995; PubMed Scopus Google Scholar). in this binding and p21 to C. Ducommun B. 1998; 17: PubMed Scopus Google Scholar). Moreover, p21 cell following of DNA damage by complexes with and G. H. R. 1993; PubMed Scopus Google Scholar, H. 1992; Full Text PDF PubMed Scopus Google Scholar). The of PARP-1 in and has been M. T. T. 1995; PubMed Scopus Google Scholar, V. C. B. de Murcia G. de Murcia J.M. Sci. U. S. A. 1995; PubMed Scopus Google Scholar). In the PAR-binding were identified in DNA-PKCS as well as in the The PAR-binding of of the conserved and is in to a The of is in DNA binding and Biol. 1996; PubMed Scopus Google Scholar). modification of DNA-PKCS by PARP-1 has been shown recently to T. J. H. J. Biol. Chem. 1998; 273: Full Text Full Text PDF PubMed Scopus Google Scholar). The modification of DNA-PKCS by PAR a in the DNA-PKCS and the via the noncovalent PAR-binding found in the protein. Moreover, the of complexes has been by from nuclear and these complexes bind to the S. T. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). Although the of these interactions to important of in C. L. Jackson S.P. Wang Z.Q. 17: PubMed Scopus Google Scholar). A conserved PAR-binding sequence is also present in several DNA repair proteins. In the damage protein is in the with excision repair A. J. Biol. Chem. 1995; Full Text Full Text PDF PubMed Scopus Google Scholar). In the DNA protein a protein of MSH2 and MSH6 J. EMBO J. 1998; 17: PubMed Scopus Google Scholar), a PAR-binding domain was in MSH6 but not in Thus, PAR binding with the DNA damage of excision and proteins of the were also found to contain a PAR-binding In XRCC1, to a is present in a large of DNA repair and cell checkpoint proteins P. P. J. PubMed Scopus Google Scholar, I. FEBS Lett. PubMed Scopus Google Scholar). The domain of has recently been to bind to PARP-1 protein M. Niedergang C. Schreiber V. Muller S. Murcia J. de Murcia G. Biol. 1998; PubMed Scopus Google Scholar). It is that this the PAR-binding of Thus, the DNA damage automodification of PARP-1 may the of a is the by PAR The PAR-binding of is the binding sites for DNA polymerase and DNA ligase A. P. T. EMBO J. 1996; PubMed Scopus Google Scholar, T. Biochemistry. PubMed Scopus Google Scholar), these domains for of these other binding Moreover, DNA ligase contains a PAR-binding of its to the N-terminal domain and interactions with at the DNA strand The binding for the C terminus of DNA ligase III, also contains a domain P. P. J. PubMed Scopus Google Scholar, T. Biochemistry. PubMed Scopus Google Scholar). a PAR-binding was identified in DNA polymerase An can in the PAR-binding XRCC1, DNA ligase III, and DNA polymerase in the proteins to interact at DNA strand The of in the presence of NAD+ this Poirier G.G. T. J. Biol. Chem. 1993; 268: Full Text PDF PubMed Google Scholar, M. J. Biol. Chem. 2000; 275: Full Text Full Text PDF PubMed Google Scholar). The PAR-binding in the of the domain responsible for DNA binding, nuclear localization, and protein interactions S. 1998; PubMed Scopus Google Scholar). The is at the and the N-terminal domain and the a potential to other proteins P. C.J. Muller EMBO J. PubMed Google Scholar). The conserved hydrophobic motif can found also in that this may also have PAR-binding of complexes has been Biol. Chem. 1999; PubMed Scopus Google Scholar), and in and a of Biol. Chem. 1999; PubMed Scopus Google Scholar, Ménissier-de Murcia J. C. Decker P. R. Muller S. de G. J.C. de Murcia G. EMBO J. 1999; PubMed Scopus Google Scholar). of is by of PARP-1 S. P. A. Biochem. J. 1992; PubMed Scopus Google Scholar). A PAR-binding is also present in with the A domain can found in all members of the to the MARCKS protein family, interactions by PAR polymers (11Schmitz A.P. Pleschke J.M. Kleczkowska H.E. Althaus F.R. Vergères G. Biochemistry. 1998; 37: 9520-9527Crossref PubMed Scopus (18) Google Scholar). The PAR-binding in telomerase to the TERT catalytic at by a to the PARP family (5Smith S. Giriat I. Schmitt A. de Lange T. Science. 1998; 282: 1484-1487Crossref PubMed Scopus (908) Google Scholar). catalyzes its automodification in a DNA-independent and these PAR polymers directly interact with telomerase and regulate its a the of telomerase to the and (for Trends 1999; Full Text Full Text PDF PubMed Scopus Google Scholar). functional can derived for the PAR-binding in a caspase-activated DNase catalyzing DNA cell The is at a domain and the catalytic domain T. S. G. J. Biol. Chem. 1999; 274: Full Text Full Text PDF PubMed Scopus Google Scholar). In the of specific PAR-binding sites in several proteins of the cellular signal network that these proteins may of the PARP protein of these proteins PARP-1 members of the DNA damage signal specific domains in these PAR regulate protein-protein or interactions, protein localization, or protein degradation. PAR also a function in the DNA damage signal network by the of It to complexes formed in results of with this For example, complexes can with PAR MSH6 or from human cell F. R. and J. in p21 was a from U. Hubscher of of and XPA was obtained from H. of and of The hMutSα and MSH2 and MSH6 were obtained from J. Jiricny of of