title: 3'-5' phosphoadenosine phosphate is an inhibitor of PARP-1 and a potential mediator of the lithium-dependent inhibition of PARP-1 in vivo.
abstract: pAp (3'-5' phosphoadenosine phosphate) is a by-product of sulfur and lipid metabolism and has been shown to have strong inhibitory properties on RNA catabolism. In the present paper we report a new target of pAp, PARP-1 [poly(ADP-ribose) polymerase 1], a key enzyme in the detection of DNA single-strand breaks. We show that pAp can interact with PARP-1 and inhibit its poly(ADP-ribosyl)ation activity. In vitro, inhibition of PARP-1 was detectable at micromolar concentrations of pAp and altered both PARP-1 automodification and heteromodification of histones. Analysis of the kinetic parameters revealed that pAp acted as a mixed inhibitor that modulated both the Km and the Vmax of PARP-1. In addition, we showed that upon treatment with lithium, a very potent inhibitor of the enzyme responsible for pAp recycling, HeLa cells exhibited a reduced level of poly(ADP-ribosyl)ation in response to oxidative stress. From these results, we propose that pAp might be a physiological regulator of PARP-1 activity.
authors.affiliation: Institut Pasteur, CNRS UMR 3528, Unité de Biochimie des Interactions macromoléculaires, Département de Biologie Strucurale et Chimie, Paris, France. elie.toledano@pasteur.fr
authors.forename: Elie
authors.initials: E
authors.lastname: Toledano
authors.forename: Vasily
authors.initials: V
authors.lastname: Ogryzko
authors.forename: Antoine
authors.initials: A
authors.lastname: Danchin
authors.forename: Daniel
authors.initials: D
authors.lastname: Ladant
authors.forename: Undine
authors.initials: U
authors.lastname: Mechold
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology*; D006367:HeLa Cells; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008094:Lithium / Q000378:metabolism*; D000071137:Poly (ADP-Ribose) Polymerase-1; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D006657:Histones; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D000244:Adenosine Diphosphate; D008094:Lithium; C010840:adenosine 3'-phosphate-5'-phosphate; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases