S. Ozcan et al., GLUCOSE-UPTAKE AND METABOLISM IN GRR1 CAT80 MUTANTS OF SACHAROMYCES-CEREVISIAE/, European journal of biochemistry, 224(2), 1994, pp. 605-611
Glucose repression in the yeast Saccharomyces cerevisiae designates a
global regulatory system controlling the expression of various sets of
genes required for the utilization of alternate carbon sources. In a
screen, designed for the selection of mutants with reduced glycolytic
flux we obtained isolates which were shown by complementation of the c
loned wild-type gene to be allelic to the glucose repression mutants g
rr1/cat80/cot2 previously described. We demonstrate that the grr1 lesi
on lead to a concentration-dependent decrease in glycolytic flux on gl
ucose. It is very likely that this is caused by a significant decrease
in the expression of various genes encoding hexose transporters (HXT1
,3) leading to a reduced glucose-uptake rate. In contrast, expression
of the maltose permease gene (MAL11) and maltose utilization is normal
. There is indirect evidence that grr1 affects the uptake of amino aci
ds, and others have shown that the sugar-induced transport of divalent
cations is impaired. These effects are not glucose-specific. We sugge
st that Grr1, a putative cytoplasmic protein, has a central function i
n the sensing of nutritional conditions for a variety of unrelated sub
stances, and that relief from glucose repression may be a corollary of
this defect in sensing.