Effects of a hexokinase II deletion on the dynamics of glycolysis in continuous cultures of Saccharomyces cerevisiae.
In glucose-limited aerobic chemostat cultures of a wild-type Saccharomyces cerevisiae and a derived hxk2 null strain, metabolic fluxes were identical. However, the concentrations of intracellular metabolites, especially fructose 1,6-bisphosphate, and hexose-phosphorylating activities differed. Interestingly, the hxk2 null strain showed a higher maximal growth rate and higher Crabtree threshold dilution rate, revealing a higher oxidative capacity for this strain. After a pulse of glucose, aerobic glucose-limited cultures of wild-type S. cerevisiae displayed an overshoot in the intracellular concentrations of glucose 6-phosphate, fructose 6-phosphate, and fructose 1,6-bisphosphate before a new steady state was established, in contrast to the hxk2 null strain which reached a new steady state without overshoot of these metabolites. At low dilution rates the overshoot of intracellular metabolites in the wild-type strain coincided with the immediate production of ethanol after the glucose pulse. In contrast, in the hxk2 null strain the production of ethanol started gradually. However, in spite of the initial differences in ethanol production and dynamic behaviour of the intracellular metabolites, the steady-state fluxes after transition from glucose limitation to glucose excess were not significantly different in the wild-type strain and the hxk2 null strain at any dilution rate.
Diderich
Jasper A
JA
Swammerdam Institute for Life Sciences, BioCentrum Amsterdam, Faculty of Science, University of Amsterdam, Plantage Muidergracht 12, Netherlands.
Raamsdonk
Léonie M
LM
Kuiper
Arthur
A
Kruckeberg
Arthur L
AL
Berden
Jan A
JA
Teixeira de Mattos
M Joost
MJ
van Dam
Karel
K
D000332:Aerobiosis; D003470:Culture Media; D017353:Gene Deletion; D005800:Genes, Fungal; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis; D006593:Hexokinase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*
D003470:Culture Media; D006593:Hexokinase; D005947:Glucose