title: Hydrolysis of O-acetyl-ADP-ribose isomers by ADP-ribosylhydrolase 3.
abstract: O-acetyl-ADP-ribose (OAADPr), produced by the Sir2-catalyzed NAD(+)-dependent histone/protein deacetylase reaction, regulates diverse biological processes. Interconversion between two OAADPr isomers with acetyl attached to the C-2″ and C-3″ hydroxyl of ADP-ribose (ADPr) is rapid. We reported earlier that ADP-ribosylhydrolase 3 (ARH3), one of three ARH proteins sharing structural similarities, hydrolyzed OAADPr to ADPr and acetate, and poly(ADPr) to ADPr monomers. ARH1 also hydrolyzed OAADPr and poly(ADPr) as well as ADP-ribose-arginine, with arginine in α-anomeric linkage to C-1″ of ADP-ribose. Because both ARH3- and ARH1-catalyzed reactions involve nucleophilic attacks at the C-1″ position, it was perplexing that the ARH3 catalytic site would cleave OAADPr at either the 2″- or 3″-position, and we postulated the existence of a third isomer, 1″-OAADPr, in equilibrium with 2″- and 3″-isomers. A third isomer, consistent with 1″-OAADPr, was identified at pH 9.0. Further, ARH3 OAADPr hydrolase activity was greater at pH 9.0 than at neutral pH where 3″-OAADPr predominated. Consistent with our hypothesis, IC(50) values for ARH3 inhibition by 2″- and 3″-N-acetyl-ADPr analogs of OAADPr were significantly higher than that for ADPr. ARH1 also hydrolyzed OAADPr more rapidly at alkaline pH, but cleavage of ADP-ribose-arginine was faster at neutral pH than pH 9.0. ARH3-catalyzed hydrolysis of OAADPr in H(2)(18)O resulted in incorporation of one (18)O into ADP-ribose by mass spectrometric analysis, consistent with cleavage at the C-1″ position. Together, these data suggest that ARH family members, ARH1 and ARH3, catalyze hydrolysis of the 1″-O linkage in their structurally diverse substrates.
authors.affiliation: Cardiovascular and Pulmonary Branch, NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kasamatsu
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Nakao
authors.forename: Brian C
authors.initials: BC
authors.lastname: Smith
authors.forename: Lindsay R
authors.initials: LR
authors.lastname: Comstock
authors.forename: Tohru
authors.initials: T
authors.lastname: Ono
authors.forename: Jiro
authors.initials: J
authors.lastname: Kato
authors.forename: John M
authors.initials: JM
authors.lastname: Denu
authors.forename: Joel
authors.initials: J
authors.lastname: Moss
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000737:chemistry; D002384:Catalysis; D020134:Catalytic Domain; D015971:Gene Expression Regulation, Enzymologic; D006026:Glycoside Hydrolases / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D020128:Inhibitory Concentration 50; D008956:Models, Chemical; D008962:Models, Theoretical; D009699:N-Glycosyl Hydrolases / Q000737:chemistry*; D038961:O-Acetyl-ADP-Ribose / Q000378:metabolism*; D011064:Poly Adenosine Diphosphate Ribose / Q000737:chemistry; D020033:Protein Isoforms; D056564:Sirtuin 1 / Q000737:chemistry; D037761:Sirtuins / Q000737:chemistry
chemical_list: D038961:O-Acetyl-ADP-Ribose; D020033:Protein Isoforms; D000246:Adenosine Diphosphate Ribose; D011064:Poly Adenosine Diphosphate Ribose; D006026:Glycoside Hydrolases; C508145:ADPRS protein, human; D009699:N-Glycosyl Hydrolases; C046422:ADP-ribosylarginine hydrolase; C447939:SIRT1 protein, human; D056564:Sirtuin 1; D037761:Sirtuins