L-2-Hydroxyglutarate Production Arises From Noncanonical Enzyme Function at Acidic pH

Nat Chem Biol. 2017 May;13(5):494-500. doi: 10.1038/nchembio.2307. Epub 2017 Mar 6.

Abstract

The metabolite 2-hydroxyglutarate (2HG) can be produced as either a D-R- or L-S- enantiomer, each of which inhibits α-ketoglutarate (αKG)-dependent enzymes involved in diverse biologic processes. Oncogenic mutations in isocitrate dehydrogenase (IDH) produce D-2HG, which causes a pathologic blockade in cell differentiation. On the other hand, oxygen limitation leads to accumulation of L-2HG, which can facilitate physiologic adaptation to hypoxic stress in both normal and malignant cells. Here we demonstrate that purified lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) catalyze stereospecific production of L-2HG via 'promiscuous' reduction of the alternative substrate αKG. Acidic pH enhances production of L-2HG by promoting a protonated form of αKG that binds to a key residue in the substrate-binding pocket of LDHA. Acid-enhanced production of L-2HG leads to stabilization of hypoxia-inducible factor 1 alpha (HIF-1α) in normoxia. These findings offer insights into mechanisms whereby microenvironmental factors influence production of metabolites that alter cell fate and function.

MeSH terms

  • Biocatalysis*
  • Gas Chromatography-Mass Spectrometry
  • Glutarates / metabolism*
  • Humans
  • Hydrogen-Ion Concentration
  • Ketoglutaric Acids / chemistry
  • Ketoglutaric Acids / metabolism
  • L-Lactate Dehydrogenase / metabolism*
  • Malate Dehydrogenase / metabolism*
  • Molecular Structure
  • Stereoisomerism

Substances

  • Glutarates
  • Ketoglutaric Acids
  • alpha-hydroxyglutarate
  • L-Lactate Dehydrogenase
  • Malate Dehydrogenase