title: 13C-NMR analysis of Aspergillus mutants disturbed in pyruvate metabolism.
abstract: The metabolic consequences of two defects in pyruvate metabolism of the hyphal fungus Aspergillus nidulans have been investigated by natural abundance 13C-NMR spectroscopy. A pyruvate dehydrogenase complex (pdh) mutant, grown on acetate, accumulates alanine upon starvation which is derived from mannitol reserves. The L-alanine level increases further upon incubation with the non-permissive substrate D-glucose. L-Glutamate is absent from these spectra as it is required both for the transamination of pyruvate and as a reaction on an impaired energy metabolism in such a pdh-deficient strain. A pyruvate carboxylase (pyc) mutant, grown upon acetate, only starts to accumulate alanine after a long incubation period with D-glucose, due to the long-lasting presence of phosphoenolpyruvate carboxykinase and malic enzyme, which are both induced by growth on acetate. When this strain is grown on D-fructose and L-glutamate, alanine also accumulates within 3 h upon transfer to D-glucose.
authors.affiliation: Department of Molecular Physics, Agricultural University, Wageningen, The Netherlands.
authors.forename: C
authors.initials: C
authors.lastname: Dijkema
authors.forename: J
authors.initials: J
authors.lastname: Visser
mesh_terms: D000085:Acetates / Q000378:metabolism; D000409:Alanine / Q000032:analysis; D001233:Aspergillus nidulans / Q000235:genetics* / Q000378:metabolism; D002250:Carbon Radioisotopes / Q000378:metabolism; D005632:Fructose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D011766:Pyruvate Carboxylase / Q000235:genetics* / Q000378:metabolism; D011768:Pyruvate Dehydrogenase Complex / Q000235:genetics* / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism*; D019289:Pyruvic Acid; D013395:Sucrose / Q000378:metabolism
chemical_list: D000085:Acetates; D002250:Carbon Radioisotopes; D011768:Pyruvate Dehydrogenase Complex; D011773:Pyruvates; D005632:Fructose; D013395:Sucrose; D019289:Pyruvic Acid; D011766:Pyruvate Carboxylase; D005947:Glucose; D000409:Alanine