Growth and glucose repression are controlled by glucose transport in Saccharomyces cerevisiae cells containing only one glucose transporter

A set of Saccharomyces cerevisiae strains with variable expression of only the high-affinity Hxt7 glucose transporter was constructed by partial delet ion of the HXT7 promoter in vitro and integration of the gene at various co py numbers into the genome of an hxt1-7 gal2 deletion strain. The glucose t ransport capacity increased in strains with higher levels of HXT7 expressio n. The consequences for various physiological properties of varying the glu cose transport capacity were examined. The control coefficient of glucose t ransport with respect to growth rate was 0.54. At high extracellular glucos e concentrations, both invertase activity and the rate of oxidative glucose metabolism increased manyfold with decreasing glucose transport capacity, which is indicative of release from glucose repression. These results sugge st that the intracellular glucose concentration produces the signal for glu cose repression.