Saccharomyces cerevisiae Forms d-2-Hydroxyglutarate and Couples Its Degradation to d-Lactate Formation via a Cytosolic Transhydrogenase

• Published in: The Journal of biological chemistry Vol. 291; no. 12; pp. 6036 - 6058
• Main Authors: Becker-Kettern, Julia, Paczia, Nicole, Conrotte, Jean-François, Kay, Daniel P., Guignard, Cédric, Jung, Paul P., Linster, Carole L.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 18.03.2016; American Society for Biochemistry and Molecular Biology
• Subjects: 2-hydroxyglutarate; Alcohol Oxidoreductases - chemistry; Alcohol Oxidoreductases - genetics; Alcohol Oxidoreductases - metabolism; Carbohydrate Metabolism; dehydrogenase; enzyme kinetics; flavoprotein; Gene Expression; Glutarates - metabolism; inborn error of metabolism; Ketoglutarate Dehydrogenase Complex - metabolism; Kinetics; L-Lactate Dehydrogenase (Cytochrome) - chemistry; L-Lactate Dehydrogenase (Cytochrome) - genetics; L-Lactate Dehydrogenase (Cytochrome) - metabolism; Lactic Acid - chemistry; Lactic Acid - metabolism; Metabolism; Oxaloacetic Acid - chemistry; Phosphoglycerate Dehydrogenase - genetics; Phosphoglycerate Dehydrogenase - metabolism; Pyruvic Acid - chemistry; Saccharomyces cerevisiae - enzymology; Saccharomyces cerevisiae - growth & development; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Serine - metabolism; Substrate Specificity; transhydrogenase; yeast metabolism; transhydrogenase; yeast metabolism; flavoprotein; 2-hydroxyglutarate; inborn error of metabolism; dehydrogenase; enzyme kinetics
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M115.704494

The d or l form of 2-hydroxyglutarate (2HG) accumulates in certain rare neurometabolic disorders, and high d-2-hydroxyglutarate (d-2HG) levels are also found in several types of cancer. Although 2HG has been detected in Saccharomyces cerevisiae, its metabolism in yeast has remained largely unexplored. Here, we show that S. cerevisiae actively forms the d enantiomer of 2HG. Accordingly, the S. cerevisiae genome encodes two homologs of the human d-2HG dehydrogenase: Dld2, which, as its human homolog, is a mitochondrial protein, and the cytosolic protein Dld3. Intriguingly, we found that a dld3Δ knock-out strain accumulates millimolar levels of d-2HG, whereas a dld2Δ knock-out strain displayed only very moderate increases in d-2HG. Recombinant Dld2 and Dld3, both currently annotated as d-lactate dehydrogenases, efficiently oxidized d-2HG to α-ketoglutarate. Depletion of d-lactate levels in the dld3Δ, but not in the dld2Δ mutant, led to the discovery of a new type of enzymatic activity, carried by Dld3, to convert d-2HG to α-ketoglutarate, namely an FAD-dependent transhydrogenase activity using pyruvate as a hydrogen acceptor. We also provide evidence that Ser3 and Ser33, which are primarily known for oxidizing 3-phosphoglycerate in the main serine biosynthesis pathway, in addition reduce α-ketoglutarate to d-2HG using NADH and represent major intracellular sources of d-2HG in yeast. Based on our observations, we propose that d-2HG is mainly formed and degraded in the cytosol of S. cerevisiae cells in a process that couples d-2HG metabolism to the shuttling of reducing equivalents from cytosolic NADH to the mitochondrial respiratory chain via the d-lactate dehydrogenase Dld1.