title: Metabolic consequences of altered phosphoenolpyruvate carboxykinase activity in Corynebacterium glutamicum reveal anaplerotic regulation mechanisms in vivo.
abstract: Corynebacterium glutamicum possesses high in vivo activity of the gluconeogenic phosphoenolpyruvate carboxykinase (PEPCk) during growth on glucose, resulting together with anaplerotic carboxylation reactions in a PEP/pyruvate/oxaloacetate substrate cycle. The present study investigated the changes in intracellular fluxes and metabolite concentrations that are caused by altered PEPCk activity in L-lysine-producing C. glutamicum MH20-22B, applying a recently developed (13)C labeling-based strategy for anaplerotic flux resolution and quantification. Abolition of PEPCk activity by deletion of the respective pck gene resulted in increased intracellular concentrations of oxaloacetate L-aspartate, alpha-ketoglutarate, pyruvate, and L-lysine and in a 60% enhanced flux toward L-lysine biosynthesis, whereas increasing the PEPCk activity by pck overexpression had opposite effects. The results of the combined measurements of enzyme activities, in vivo fluxes, and metabolite concentrations were exploited to elucidate the in vivo regulation of anaplerotic reactions in C. glutamicum, and implications for the metabolic engineering of amino-acid-producing strains are discussed.
authors.affiliation: Institute of Biotechnology 1, Research Center Jülich, 52425 Jülich, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Petersen
authors.forename: C
authors.initials: C
authors.lastname: Mack
authors.forename: A A
authors.initials: AA
authors.lastname: de Graaf
authors.forename: C
authors.initials: C
authors.lastname: Riedel
authors.forename: B J
authors.initials: BJ
authors.lastname: Eikmanns
authors.forename: H
authors.initials: H
authors.lastname: Sahm
mesh_terms: D003352:Corynebacterium / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D062907:Oxaloacetic Acid / Q000032:analysis / Q000378:metabolism; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics / Q000378:metabolism*; D019289:Pyruvic Acid / Q000378:metabolism
chemical_list: D062907:Oxaloacetic Acid; D019289:Pyruvic Acid; D019764:Phosphoenolpyruvate Carboxykinase (ATP)