Glucose sensing and signalling properties in Saccharomyces cerevisiae require the presence of at least two members of the glucose transporter family

The kinetics of glucose transport in a number of different mutants of Saccharomyces cerevisiae with multiple deletions in the glucose transporter gene family were determined. The deletions led td differences in maximal rate and affinity for glucose uptake by the cells, dependent on the growth conditions. At the same time, there were changes in glucose repression, as determined by expression of invertase activity. Only in the strain with genes HXT1-4 and SNF3 deleted but carrying HXT6/7 were glucose uptake kinetics and invertase activity independent of the presence or concentration of glucose in the growth medium. Some degree of glucose sensitivity was recovered if the SNF3 or HXT2 gene was present in the multiple-deletion background. It is hypothesized that during growth on glucose, both modulation of the kinetics of glucose uptake and derepression of invertase activity require the presence of more than one active gene of the glucose transporter family.