title: The 39-kDa poly(ADP-ribose) glycohydrolase ARH3 hydrolyzes O-acetyl-ADP-ribose, a product of the Sir2 family of acetyl-histone deacetylases.
abstract: The silent information regulator 2 (Sir2) family of NAD-dependent N-acetyl-protein deacetylases participates in the regulation of gene silencing, chromatin structure, and longevity. In the Sir2-catalyzed reaction, the acetyl moiety of N-acetyl-histone is transferred to the ADP-ribose of NAD, yielding O-acetyl-ADP-ribose and nicotinamide. We hypothesized that, if O-acetyl-ADP-ribose were an important signaling molecule, a specific hydrolase would cleave the (O-acetyl)-(ADP-ribose) linkage. We report here that the poly(ADP-ribose) glycohydrolase ARH3 hydrolyzed O-acetyl-ADP-ribose to produce ADP-ribose in a time- and Mg(2+)-dependent reaction and thus could participate in two signaling pathways. This O-acetyl-ADP-ribose hydrolase belongs to a family of three structurally related 39-kDa ADP-ribose-binding proteins (ARH1-ARH3). ARH1 was reported to hydrolyze ADP-ribosylarginine, whereas ARH3 degraded poly(ADP-ribose). ARH3-catalyzed generation of ADP-ribose from O-acetyl-ADP-ribose was significantly faster than from poly(ADP-ribose). Like the degradation of poly(ADP-ribose) by ARH3, hydrolysis of O-acetyl-ADP-ribose was abolished by replacement of the vicinal aspartates at positions 77 and 78 of ARH3 with asparagine. The rate of O-acetyl-ADP-ribose hydrolysis by recombinant ARH3 was 250-fold that observed with ARH1; ARH2 and poly(ADP-ribose) glycohydrolase were inactive. All data support the conclusion that the Sir2 reaction product O-acetyl-ADP-ribose is degraded by ARH3.
authors.affiliation: Pulmonary-Critical Care Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1590, USA.
authors.forename: Tohru
authors.initials: T
authors.lastname: Ono
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kasamatsu
authors.forename: Shunya
authors.initials: S
authors.lastname: Oka
authors.forename: Joel
authors.initials: J
authors.lastname: Moss
mesh_terms: D019943:Amino Acid Substitution; D006026:Glycoside Hydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D038961:O-Acetyl-ADP-Ribose / Q000096:biosynthesis*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D056564:Sirtuin 1; D037761:Sirtuins / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D038961:O-Acetyl-ADP-Ribose; D011994:Recombinant Proteins; D006026:Glycoside Hydrolases; C508145:ADPRS protein, human; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D037761:Sirtuins; D008274:Magnesium