Distribution of 14C-labelled carbon from glucose and glutamate during anaerobic growth of Saccharomyces cerevisiae.
The distribution of carbon from glucose and glutamate was studied using anaerobically grown Saccharomyces cerevisiae. The yeast was grown on glucose (20 g l-1) as the carbon/energy source and glutamic acid (3.5 g l-1) as additional carbon and sole nitrogen source. The products formed were identified using labelled [U-14C]glucose or [U-14C]glutamic acid. A seldom-reported metabolite in S. cerevisiae, 2-hydroxyglutarate, was found in significant amounts. It is suggested that 2-hydroxyglutarate is formed from the reduction of 2-oxoglutarate in a reaction catalysed by a dehydrogenase. Succinate, 2-oxoglutarate and 2-hydroxyglutarate were found to be derived exclusively from glutamate. Based on radioactivity measurements, 55%, 17% and 14% of the labelled glutamate was converted to 2-oxoglutarate, succinate and 2-hydroxyglutarate, respectively, and 55%, 9% and 3% of the labelled glucose was converted to ethanol, glycerol and pyruvate, respectively. No labelled glucose was converted to 2-oxoglutarate, succinate or 2-hydroxyglutarate. Furthermore, very little of the evolved CO2 was derived from glutamate. Separation of the amino acids from biomass by paper chromatography revealed that the glutamate family of amino acids (glutamic acid, glutamine, proline, arginine and lysine) originated almost exclusively from the carbon skeleton of glutamic acid. It can be concluded that the carbon flow follows two separate paths, and that the only major reactions utilized in the tricarboxylic acid (TCA) cycle are those reactions involved in the conversion of 2-oxoglutarate to succinate.
Albers
Eva
E
Department of General and Marine Microbiology, Lundberg Laboratory, University of Göteborg, Box 462, S-405 30 Göteborg, Sweden.|Department of Chemical Reaction Engineering, Chalmers University of Technology, S-41296 Göteborg, Sweden.
Gustafsson
Lena
L
Department of General and Marine Microbiology, Lundberg Laboratory, University of Göteborg, Box 462, S-405 30 Göteborg, Sweden.
Niklasson
Claes
C
Department of Chemical Reaction Engineering, Chalmers University of Technology, S-41296 Göteborg, Sweden.
Lidén
Gunnar
G
Department of Chemical Reaction Engineering, Chalmers University of Technology, S-41296 Göteborg, Sweden.
D000596:Amino Acids / Q000378:metabolism; D000693:Anaerobiosis; D002250:Carbon Radioisotopes / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D002854:Chromatography, Paper; D002952:Citric Acid Cycle; D005947:Glucose / Q000378:metabolism*; D005971:Glutamates / Q000378:metabolism*; D005977:Glutarates / Q000032:analysis; D007656:Ketoglutaric Acids / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism*; D013386:Succinates / Q000378:metabolism
D000596:Amino Acids; D002250:Carbon Radioisotopes; D005971:Glutamates; D005977:Glutarates; D007656:Ketoglutaric Acids; D013386:Succinates; C019417:alpha-hydroxyglutarate; D010088:Oxidoreductases; D005947:Glucose