Loss of fermentative capacity in baker's yeast can partly be explained by reduced glucose uptake capacity

Initial attempts to increase fermentative capacity of baker's yeast focussed on the overproduction of single enzymes, which proved to be insufficient. Nowadays many components of the system are monitored simultaneously in a search for a correlation with fermentative capacity. However, this strategy has not yet proven fruitful either. Here we investigate an element previously neglected, the glucose transporter, and find that a loss of glucose transport capacity correlates with a decrease of fermentative capacity during nutrient starvation. However the correlation is not unique, suggesting that the loss of fermentative capacity cannot be attributed to an inactivation of glucose transport alone. Our results suggest the necessity to use a detailed kinetic model as an underlying working hypothesis and to use Metabolic Control Analysis to examine the pathway's control properties.