title: Schistosoma mansoni NAD(+) catabolizing enzyme: identification of key residues in catalysis.
abstract: Schistosoma mansoni NAD(+) catabolizing enzyme (SmNACE), a distant homolog of mammalian CD38, shows significant structural and functional analogy to the members of the CD38/ADP-ribosyl cyclase family. The hallmark of SmNACE is the lack of ADP-ribosyl cyclase activity that might be ascribed to subtle changes in its active site. To better characterize the residues of the active site we determined the kinetic parameters of nine mutants encompassing three acidic residues: (i) the putative catalytic residue Glu202 and (ii) two acidic residues within the 'signature' region (the conserved Glu124 and the downstream Asp133), (iii) Ser169, a strictly conserved polar residue and (iv) two aromatic residues (His103 and Trp165). We established the very important role of Glu202 and of the hydrophobic domains overwhelmingly in the efficiency of the nicotinamide-ribosyl bond cleavage step. We also demonstrated that in sharp contrast with mammalian CD38, the 'signature' Glu124 is as critical as Glu202 for catalysis by the parasite enzyme. The different environments of the two Glu residues in the crystal structure of CD38 and in the homology model of SmNACE could explain such functional discrepancies. Mutagenesis data and 3D structures also indicated the importance of aromatic residues, especially His103, in the stabilization of the reaction intermediate as well as in the selection of its conformation suitable for cyclization to cyclic ADP-ribose. Finally, we showed that inhibition of SmNACE by the natural product cyanidin requires the integrity of Glu202 and Glu124, but not of His103 and Trp165, hence suggesting different recognition modes for substrate and inhibitor.
authors.affiliation: Laboratoire de Conception et Application de Molécules Bioactives, UMR 7199 CNRS-Université de Strasbourg, Faculté de Pharmacie, Medalis Drug Discovery Center, 74 route du Rhin, 67400 Illkirch, France.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Kuhn
authors.forename: Esther
authors.initials: E
authors.lastname: Kellenberger
authors.forename: Francis
authors.initials: F
authors.lastname: Schuber
authors.forename: Hélène
authors.initials: H
authors.lastname: Muller-Steffner
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000737:chemistry / Q000235:genetics; D000596:Amino Acids; D000818:Animals; D000872:Anthocyanins / Q000737:chemistry; D020134:Catalytic Domain; D015801:Helminth Proteins / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D006867:Hydrolases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics; D008562:Membrane Glycoproteins / Q000737:chemistry / Q000235:genetics; D009243:NAD / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics; D017434:Protein Structure, Tertiary; D012550:Schistosoma mansoni / Q000201:enzymology* / Q000235:genetics; D040681:Structural Homology, Protein
chemical_list: D000596:Amino Acids; D000872:Anthocyanins; D015801:Helminth Proteins; D008562:Membrane Glycoproteins; D009243:NAD; C017154:cyanidin; D006867:Hydrolases; C021839:NAD degrading enzyme; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1
keywords: ADP-ribose; ADPR; CD38; Docking; GPI; NAADP(+); NAD(+); Schistosoma mansoni; Schistosoma mansoni NAD(+) catabolizing enzyme; SmNACE; cADPR; cyclic ADP-ribose; glycosyl phosphatidylinositol; nicotinamide adenine dinucleotide; nicotinic acid adenine dinucleotide