title: Biochemical association of poly(ADP-ribose) polymerase-1 and its apoptotic peptide fragments with DNA polymerase beta.
abstract: We have characterized the biochemical association of two DNA damage-dependent enzymes, poly(ADP-ribose) polymerase-1 (PARP-1) [EC 2.4.2.30] and DNA polymerase beta (pol beta) [2.7.7.7]. We reproducibly observed that pol beta is an efficient covalent target for ADP-ribose polymers under standard conditions of enzymatically catalyzed ADP-ribosylation of betaNAD+ as a substrate. The efficiency of poly(ADP-ribosyl)ation increased as a function of the pol beta and betaNAD+ concentrations. To further characterize the molecular interactions between these two unique polymerases, we also subjected human recombinant PARP-1 to peptide-specific enzymatic degradation with either caspase-3 or caspase-7 in vitro. This proteolytic treatment, commonly referred to as 'a hallmark of apoptosis', generated the two physiologically relevant peptide fragments of PARP-1, e.g., a 24-kDa amino-terminus and an 89-kDa carboxy-terminal domain. Interestingly, co-incubation of the two peptide fragments of PARP-1 with full-length pol beta resulted in their domain-specific molecular association as determined by co-immunoprecipitation and reciprocal immunoblotting. Therefore, our data strongly suggest that, once PARP-1 is proteolyzed by either caspase-3 or caspase-7 during cell death, the specific association of its apoptotic fragments with DNA repair enzymes, such as pol beta, may serve a regulatory molecular role in the execution phase of apoptosis.
authors.affiliation: The Department of Molecular Biology and Immunology, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107-2699, USA.
authors.forename: Nils F
authors.initials: NF
authors.lastname: Confer
authors.forename: Sunitha R
authors.initials: SR
authors.lastname: Kumari
authors.forename: Rafael
authors.initials: R
authors.lastname: Alvarez-Gonzalez
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D019951:DNA Polymerase beta / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology; D051381:Rats
chemical_list: D010446:Peptide Fragments; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D019951:DNA Polymerase beta