title: Fumarate analogs act as allosteric inhibitors of the human mitochondrial NAD(P)+-dependent malic enzyme.
abstract: Human mitochondrial NAD(P)+-dependent malic enzyme (m-NAD(P)-ME) is allosterically activated by the four-carbon trans dicarboxylic acid, fumarate. Previous studies have suggested that the dicarboxylic acid in a trans conformation around the carbon-carbon double bond is required for the allosteric activation of the enzyme. In this paper, the allosteric effects of fumarate analogs on m-NAD(P)-ME are investigated. Two fumarate-insensitive mutants, m-NAD(P)-ME_R67A/R91A and m-NAD(P)-ME_K57S/E59N/K73E/D102S, as well as c-NADP-ME, were used as the negative controls. Among these analogs, mesaconate, trans-aconitate, monomethyl fumarate and monoethyl fumarate were allosteric activators of the enzyme, while oxaloacetate, diethyl oxalacetate, and dimethyl fumarate were found to be allosteric inhibitors of human m-NAD(P)-ME. The IC50 value for diethyl oxalacetate was approximately 2.5 mM. This paper suggests that the allosteric inhibitors may impede the conformational change from open form to closed form and therefore inhibit m-NAD(P)-ME enzyme activity.
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Ju-Yi
authors.initials: JY
authors.lastname: Hsieh
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan; Institute of Genomics and Bioinformatics, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Jyung-Hurng
authors.initials: JH
authors.lastname: Liu
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Pai-Chun
authors.initials: PC
authors.lastname: Yang
authors.affiliation: Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan.
authors.forename: Chi-Li
authors.initials: CL
authors.lastname: Lin
authors.affiliation: Institute of Microbiology & Immunology, Chung Shan Medical University, and Division of Allergy, Immunology, and Rheumatology, Chung Shan Medical University Hospital, Taichung, Taiwan.
authors.forename: Guang-Yaw
authors.initials: GY
authors.lastname: Liu
authors.affiliation: Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan; Institute of Genomics and Bioinformatics, National Chung Hsing University, Taichung, Taiwan; Agricultural Biotechnology Center (ABC), National Chung Hsing University, Taichung, Taiwan.
authors.forename: Hui-Chih
authors.initials: HC
authors.lastname: Hung
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects; D003600:Cytosol / Q000201:enzymology; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D005650:Fumarates / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D008291:Malate Dehydrogenase / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D008928:Mitochondria / Q000201:enzymology*
chemical_list: D004791:Enzyme Inhibitors; D005650:Fumarates; C032005:fumaric acid; D008291:Malate Dehydrogenase; C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)