By-product formation during exposure of respiring Saccharomyces cerevisiae cultures to excess glucose is not caused by a limited capacity of pyruvate carboxylase.
Upon exposure to excess glucose, respiring cultures of Saccharomyces cerevisiae produce substantial amounts of ethanol and acetate. A possible role of a limited anaplerotic capacity in this process was investigated by overexpressing pyruvate carboxylase and by replacing it with a heterologous enzyme (Escherichia coli phosphoenolpyruvate carboxylase). Compared to the wild-type, neither the pyruvate carboxylase (Pyc)-overexpressing nor the transgenic strain exhibited reduced by-product formation after glucose pulses to aerobic glucose-limited chemostat cultures. An increased intracellular malate concentration was observed in the two engineered strains. It is concluded that by-product formation in S. cerevisiae is not caused by a limited anaplerotic capacity.
Bauer
J
J
Lesaffre Développement, P.O. Box 6027, 147, rue Gabriel Péri, 59706, Marcq en Baroeul, France.
Luttik
M A
MA
Flores
C L
CL
van Dijken
J P
JP
Pronk
J T
JT
Niederberger
P
P
D000085:Acetates / Q000378:metabolism; D001224:Aspartic Acid / Q000378:metabolism; D003470:Culture Media; D000431:Ethanol / Q000378:metabolism; D005285:Fermentation; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D008293:Malates / Q000378:metabolism; D062907:Oxaloacetic Acid / Q000378:metabolism; D010101:Oxygen Consumption; D011766:Pyruvate Carboxylase / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000502:physiology*
D000085:Acetates; D003470:Culture Media; D008293:Malates; D011773:Pyruvates; D062907:Oxaloacetic Acid; D001224:Aspartic Acid; D000431:Ethanol; D011766:Pyruvate Carboxylase; D005947:Glucose