title: 3-nitropropionic acid is a suicide inhibitor of mitochondrial respiration that, upon oxidation by complex II, forms a covalent adduct with a catalytic base arginine in the active site of the enzyme.
abstract: We report three new structures of mitochondrial respiratory Complex II (succinate ubiquinone oxidoreductase, E.C. 1.3.5.1) at up to 2.1 A resolution, with various inhibitors. The structures define the conformation of the bound inhibitors and suggest the residues involved in substrate binding and catalysis at the dicarboxylate site. In particular they support the role of Arg(297) as a general base catalyst accepting a proton in the dehydrogenation of succinate. The dicarboxylate ligand in oxaloacetate-containing crystals appears to be the same as that reported for Shewanella flavocytochrome c treated with fumarate. The plant and fungal toxin 3-nitropropionic acid, an irreversible inactivator of succinate dehydrogenase, forms a covalent adduct with the side chain of Arg(297). The modification eliminates a trypsin cleavage site in the flavoprotein, and tandem mass spectroscopic analysis of the new fragment shows the mass of Arg(297) to be increased by 83 Da and to have the potential of losing 44 Da, consistent with decarboxylation, during fragmentation.
authors.affiliation: Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Li-shar
authors.initials: LS
authors.lastname: Huang
authors.forename: Gang
authors.initials: G
authors.lastname: Sun
authors.forename: David
authors.initials: D
authors.lastname: Cobessi
authors.forename: Andy C
authors.initials: AC
authors.lastname: Wang
authors.forename: John T
authors.initials: JT
authors.lastname: Shen
authors.forename: Eric Y
authors.initials: EY
authors.lastname: Tung
authors.forename: Vernon E
authors.initials: VE
authors.lastname: Anderson
authors.forename: Edward A
authors.initials: EA
authors.lastname: Berry
mesh_terms: D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001665:Binding Sites; D002261:Carboxin / Q000737:chemistry / Q000378:metabolism; D019069:Cell Respiration / Q000502:physiology*; D002645:Chickens; D003292:Convulsants / Q000378:metabolism*; D018360:Crystallography, X-Ray; D042963:Electron Transport Complex II / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D008958:Models, Molecular; D015394:Molecular Structure; D009574:Nitro Compounds / Q000378:metabolism*; D010084:Oxidation-Reduction; D011422:Propionates / Q000378:metabolism*; D011487:Protein Conformation; D013385:Succinate Dehydrogenase / Q000037:antagonists & inhibitors; D019802:Succinic Acid / Q000378:metabolism; D013552:Swine
chemical_list: D003292:Convulsants; D009574:Nitro Compounds; D011422:Propionates; D002261:Carboxin; D001120:Arginine; D019802:Succinic Acid; D042963:Electron Transport Complex II; D013385:Succinate Dehydrogenase; C015392:3-nitropropionic acid