Publications

• A novel alpha-ketoglutarate reductase activity of the serA-encoded 3-phosphoglycerate dehydrogenase of Escherichia coli K-12 and its possible implications for human 2-hydroxyglutaric aciduria.

  Zhao G., Winkler M.E.

  Escherichia coli serA-encoded 3-phosphoglycerate (3PG) dehydrogenase catalyzes the first step of the major phosphorylated pathway of L-serine (Ser) biosynthesis. The SerA enzyme is evolutionarily related to the pdxB gene product, 4-phosphoerythronate dehydrogenase, which catalyzes the second step ... >> More

  Escherichia coli serA-encoded 3-phosphoglycerate (3PG) dehydrogenase catalyzes the first step of the major phosphorylated pathway of L-serine (Ser) biosynthesis. The SerA enzyme is evolutionarily related to the pdxB gene product, 4-phosphoerythronate dehydrogenase, which catalyzes the second step in one branch of pyridoxal 5'-phosphate coenzyme biosynthesis. Both the Ser and pyridoxal 5'-phosphate biosynthetic pathways use the serC(pdxF)-encoded transaminase in their next steps. In an analysis of these parallel pathways, we attempted to couple the transaminase and dehydrogenase reactions in the reverse direction. Unexpectedly, we found that the SerA enzyme catalyzes a previously undetected reduction of alpha-ketoglutarate (alpha KG) to 2-hydroxyglutaric acid (HGA). Numerous criteria ruled out the possibility that this SerA alpha KG reductase activity was caused by contamination in the substrate or purified enzyme preparations. HGA was confirmed as the product of the SerA alpha KG reductase reaction by thin-layer chromatography and by enzyme assays showing that both the D- and L-isomers of HGA were substrates for the reverse (dehydrogenase) reaction. Detailed steady-state kinetic analyses showed that alpha KG reduction (apparent Michaelis-Menten constant [Km(app)] = 88 microM; apparent catalytic constant [kcat(app)] = 33.3 s-1) and 3-phosphohydroxypyruvate reduction (Km(app) = 3.2 microM; kcatapp = 27.8 s-1), which is the reverse reaction of 3PG oxidation, were the major in vitro activities of the SerA enzyme. The SerA alpha KG reductase was inhibited by Ser, D-HGA, 3PG, and glycine (Gly), whereas the D-HGA dehydrogenase was inhibited by Ser, alpha KG, 3-phosphohydroxypyruvate, and Gly. The implications of these findings for the regulation of Ser biosynthesis, the recycling of NADH, and the enzymology of 2-hydroxyacid dehydrogenases are discussed. Since the same pathway of Ser biosynthesis seems to be present in all organisms, these results suggest that a mutation in the human SerA homolog may contribute to the neurometabolic diseases D- and L-2-hydroxyglutaric aciduria, which lead to the accumulation of D-HGA and L-HGA, respectively. << Less

  J. Bacteriol. 178:232-239(1996) [PubMed] [EuropePMC]

  This publication is cited by 3 other entries.

• Human phosphoglycerate dehydrogenase produces the oncometabolite D-2-hydroxyglutarate.

  Fan J., Teng X., Liu L., Mattaini K.R., Looper R.E., Vander Heiden M.G., Rabinowitz J.D.

  Human d-3-phosphoglycerate dehydrogenase (PHGDH), the first enzyme in the serine biosynthetic pathway, is genomically amplified in tumors including breast cancer and melanoma. In PHGDH-amplified cancer cells, knockdown of PHGDH is not fully rescued by exogenous serine, suggesting possible addition ... >> More

  Human d-3-phosphoglycerate dehydrogenase (PHGDH), the first enzyme in the serine biosynthetic pathway, is genomically amplified in tumors including breast cancer and melanoma. In PHGDH-amplified cancer cells, knockdown of PHGDH is not fully rescued by exogenous serine, suggesting possible additional growth-promoting roles for the enzyme. Here we show that, in addition to catalyzing oxidation of 3-phosphoglycerate, PHGDH catalyzes NADH-dependent reduction of α-ketoglutarate (AKG) to the oncometabolite d-2-hydroxyglutarate (d-2HG). Knockdown of PHGDH decreased cellular 2HG by approximately 50% in the PHGDH-amplified breast cancer cell lines MDA-MB-468 (normal concentration 93 μM) and BT-20 (normal concentration 35 μM) and overexpression of PHGDH increased cellular 2HG by over 2-fold in non-PHGDH-amplified MDA-MB-231 breast cancer cells, which normally display very low PHGDH expression. The reduced 2HG level in PHGDH knockdown cell lines can be rescued by PHGDH re-expression, but not by a catalytically inactive PHGDH mutant. The initial connection between cancer and d-2HG involved production of high levels of d-2HG by mutant isocitrate dehydrogenase. More recently, however, elevated d-2HG has been observed in breast cancer tumors without isocitrate dehydrogenase mutation. Our results suggest that PHGDH is one source of this d-2HG. << Less

  ACS Chem. Biol. 10:510-516(2015) [PubMed] [EuropePMC]

  This publication is cited by 2 other entries.