Fumarate analogs act as allosteric inhibitors of the human mitochondrial NAD(P)+-dependent malic enzyme

PLoS One. 2014 Jun 9;9(6):e98385. doi: 10.1371/journal.pone.0098385. eCollection 2014.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Allosteric Regulation / drug effects
  • Cytosol / enzymology
  • Enzyme Inhibitors / chemistry*
  • Enzyme Inhibitors / pharmacology*
  • Fumarates / chemistry*
  • Fumarates / pharmacology*
  • Humans
  • Malate Dehydrogenase / antagonists & inhibitors*
  • Malate Dehydrogenase / chemistry*
  • Mitochondria / enzymology*

Substances

  • Enzyme Inhibitors
  • Fumarates
  • fumaric acid
  • Malate Dehydrogenase
  • malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)

Grants and funding

This work was supported by the Ministry of Science and Technology, ROC (NSC 101-2311-B-005-005-MY3 to H.-C.H.) and in part by the Ministry of Education, Taiwan, R.O.C. under the ATU plan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.