Metabolic Consequences of Altered PhosphoenolpyruvateCarboxykinase Activity in Corynebacterium glutamicum Reveal Anaplerotic Regulation Mechanisms in Vivo

Pyruvate:Quinone Oxidoreductase from Corynebacterium glutamicum : Purification and Biochemical Characterization

“…The fact that both an acetate kinase mutant and a phosphotransacetylase mutant show growth behavior identical to that of the C. glutamicum WT strain (54) indicates that such a bypass of the pyruvate dehydrogenase complex is at least not essential for growth of C. glutamicum on minimal medium containing glucose. Moreover, compared to the pyruvate dehydrogenase complex, the pyruvate:quinone oxidoreductase has very low affinity for pyruvate (K m values of 0.8 and 30 mM, respectively) (61; also this work), and regarding the intracellular concentration of 0.5 to 0.8 mM pyruvate (50), it seems unlikely that pyruvate:quinone oxidoreductase significantly contributes to the oxidative pyruvate decarboxylation under the conditions in which C. glutamicum generally is cultivated. It may well be that a hitherto unknown intracellular factor (a so-far-unidentified metabolite or internal equilibria) positively affects the affinity of pyruvate:quinone oxidoreductase for pyruvate and/or that the enzyme can substitute for pyruvate dehydrogenase complex activity under certain conditions, e.g., when pyruvate dehydrogenase activity is low.…”

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

“…We found that Dld3 can also use oxaloacetate as an electron acceptor instead of pyruvate and then form D-malate instead of D-lactate. The lower intracellular concentrations of oxaloacetate as compared with pyruvate (64) and the much more pronounced effect of DLD3 gene deletion on intra-and extracellular D-lactate levels than on malate levels are, however, strong arguments in favor of pyruvate being the physiological electron acceptor for Dld3. This is further supported by comparison of the K m value of the Dld3 transhydrogenase for pyruvate (about 0.5 mM in the presence of a saturating concentration of D-2HG) with the pyruvate concentrations measured intracellularly (0.6 -1.1 mM; supplemental Fig.…”

Gluconeogenic carbon flow of tricarboxylic acid cycle intermediates is critical for Mycobacterium tuberculosis to establish and maintain infection

“…We examined 13 C label incorporation into the metabolites hexose-phosphate, serine, alanine, pyruvate, phosphoenolpyruvate (PEP), aspartate, and malate to follow carbon flow through glycolysis and gluconeogenesis (4). We could not measure OAA directly because of its instability (22), and instead measured aspartate the direct product and reporter of OAA (23). Metabolism of U-13 C glucose was indistinguishable between WT and ΔpckA (Fig.…”